Vendor import of clang trunk r300422:vendor/clang/clang-trunk-r300422

https://llvm.org/svn/llvm-project/cfe/trunk@300422

38 files changed, 5993 insertions, 2385 deletions

diff --git a/lib/Sema/AnalysisBasedWarnings.cpp b/lib/Sema/AnalysisBasedWarnings.cpp
index a987a8ce0b31..50ad113fc880 100644
--- a/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/lib/Sema/AnalysisBasedWarnings.cpp
@@ -972,7 +972,8 @@ namespace {
       }
     }
 
-    bool checkFallThroughIntoBlock(const CFGBlock &B, int &AnnotatedCnt) {
+    bool checkFallThroughIntoBlock(const CFGBlock &B, int &AnnotatedCnt,
+                                   bool IsTemplateInstantiation) {
       assert(!ReachableBlocks.empty() && "ReachableBlocks empty");
 
       int UnannotatedCnt = 0;
@@ -1002,8 +1003,12 @@ namespace {
                ElemIt != ElemEnd; ++ElemIt) {
             if (Optional<CFGStmt> CS = ElemIt->getAs<CFGStmt>()) {
               if (const AttributedStmt *AS = asFallThroughAttr(CS->getStmt())) {
-                S.Diag(AS->getLocStart(),
-                       diag::warn_fallthrough_attr_unreachable);
+                // Don't issue a warning for an unreachable fallthrough
+                // attribute in template instantiations as it may not be
+                // unreachable in all instantiations of the template.
+                if (!IsTemplateInstantiation)
+                  S.Diag(AS->getLocStart(),
+                         diag::warn_fallthrough_attr_unreachable);
                 markFallthroughVisited(AS);
                 ++AnnotatedCnt;
                 break;
@@ -1164,7 +1169,11 @@ static void DiagnoseSwitchLabelsFallthrough(Sema &S, AnalysisDeclContext &AC,
 
     int AnnotatedCnt;
 
-    if (!FM.checkFallThroughIntoBlock(*B, AnnotatedCnt))
+    bool IsTemplateInstantiation = false;
+    if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(AC.getDecl()))
+      IsTemplateInstantiation = Function->isTemplateInstantiation();
+    if (!FM.checkFallThroughIntoBlock(*B, AnnotatedCnt,
+                                      IsTemplateInstantiation))
       continue;
 
     S.Diag(Label->getLocStart(),
diff --git a/lib/Sema/CoroutineStmtBuilder.h b/lib/Sema/CoroutineStmtBuilder.h
new file mode 100644
index 000000000000..4958576219e5
--- /dev/null
+++ b/lib/Sema/CoroutineStmtBuilder.h
@@ -0,0 +1,70 @@
+//===- CoroutineStmtBuilder.h - Implicit coroutine stmt builder -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//===----------------------------------------------------------------------===//
+//
+//  This file defines CoroutineStmtBuilder, a class for building the implicit
+//  statements required for building a coroutine body.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LIB_SEMA_COROUTINESTMTBUILDER_H
+#define LLVM_CLANG_LIB_SEMA_COROUTINESTMTBUILDER_H
+
+#include "clang/AST/Decl.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/StmtCXX.h"
+#include "clang/Lex/Preprocessor.h"
+#include "clang/Sema/SemaInternal.h"
+
+namespace clang {
+
+class CoroutineStmtBuilder : public CoroutineBodyStmt::CtorArgs {
+  Sema &S;
+  FunctionDecl &FD;
+  sema::FunctionScopeInfo &Fn;
+  bool IsValid = true;
+  SourceLocation Loc;
+  QualType RetType;
+  SmallVector<Stmt *, 4> ParamMovesVector;
+  const bool IsPromiseDependentType;
+  CXXRecordDecl *PromiseRecordDecl = nullptr;
+
+public:
+  /// \brief Construct a CoroutineStmtBuilder and initialize the promise
+  /// statement and initial/final suspends from the FunctionScopeInfo.
+  CoroutineStmtBuilder(Sema &S, FunctionDecl &FD, sema::FunctionScopeInfo &Fn,
+                       Stmt *Body);
+
+  /// \brief Build the coroutine body statements, including the
+  /// "promise dependent" statements when the promise type is not dependent.
+  bool buildStatements();
+
+  /// \brief Build the coroutine body statements that require a non-dependent
+  /// promise type in order to construct.
+  ///
+  /// For example different new/delete overloads are selected depending on
+  /// if the promise type provides `unhandled_exception()`, and therefore they
+  /// cannot be built until the promise type is complete so that we can perform
+  /// name lookup.
+  bool buildDependentStatements();
+
+  bool isInvalid() const { return !this->IsValid; }
+
+private:
+  bool makePromiseStmt();
+  bool makeInitialAndFinalSuspend();
+  bool makeNewAndDeleteExpr();
+  bool makeOnFallthrough();
+  bool makeOnException();
+  bool makeReturnObject();
+  bool makeReturnOnAllocFailure();
+  bool makeParamMoves();
+};
+
+} // end namespace clang
+
+#endif // LLVM_CLANG_LIB_SEMA_COROUTINESTMTBUILDER_H
diff --git a/lib/Sema/MultiplexExternalSemaSource.cpp b/lib/Sema/MultiplexExternalSemaSource.cpp
index 077a56ff8e7f..b7e343c64718 100644
--- a/lib/Sema/MultiplexExternalSemaSource.cpp
+++ b/lib/Sema/MultiplexExternalSemaSource.cpp
@@ -94,6 +94,15 @@ MultiplexExternalSemaSource::GetExternalCXXCtorInitializers(uint64_t Offset) {
   return nullptr;
 }
 
+ExternalASTSource::ExtKind
+MultiplexExternalSemaSource::hasExternalDefinitions(const Decl *D) {
+  for (const auto &S : Sources)
+    if (auto EK = S->hasExternalDefinitions(D))
+      if (EK != EK_ReplyHazy)
+        return EK;
+  return EK_ReplyHazy;
+}
+
 bool MultiplexExternalSemaSource::
 FindExternalVisibleDeclsByName(const DeclContext *DC, DeclarationName Name) {
   bool AnyDeclsFound = false;
diff --git a/lib/Sema/ScopeInfo.cpp b/lib/Sema/ScopeInfo.cpp
index 3970b4136982..b309a36a30a3 100644
--- a/lib/Sema/ScopeInfo.cpp
+++ b/lib/Sema/ScopeInfo.cpp
@@ -40,10 +40,15 @@ void FunctionScopeInfo::Clear() {
   FirstCXXTryLoc = SourceLocation();
   FirstSEHTryLoc = SourceLocation();
 
+  // Coroutine state
+  FirstCoroutineStmtLoc = SourceLocation();
+  CoroutinePromise = nullptr;
+  NeedsCoroutineSuspends = true;
+  CoroutineSuspends.first = nullptr;
+  CoroutineSuspends.second = nullptr;
+
   SwitchStack.clear();
   Returns.clear();
-  CoroutinePromise = nullptr;
-  CoroutineStmts.clear();
   ErrorTrap.reset();
   PossiblyUnreachableDiags.clear();
   WeakObjectUses.clear();
@@ -184,7 +189,7 @@ void FunctionScopeInfo::markSafeWeakUse(const Expr *E) {
   }
 
   // Has this weak object been seen before?
-  FunctionScopeInfo::WeakObjectUseMap::iterator Uses;
+  FunctionScopeInfo::WeakObjectUseMap::iterator Uses = WeakObjectUses.end();
   if (const ObjCPropertyRefExpr *RefExpr = dyn_cast<ObjCPropertyRefExpr>(E)) {
     if (!RefExpr->isObjectReceiver())
       return;
@@ -197,10 +202,10 @@ void FunctionScopeInfo::markSafeWeakUse(const Expr *E) {
   }
   else if (const ObjCIvarRefExpr *IvarE = dyn_cast<ObjCIvarRefExpr>(E))
     Uses = WeakObjectUses.find(WeakObjectProfileTy(IvarE));
-  else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
-    Uses = WeakObjectUses.find(WeakObjectProfileTy(DRE));
-  else if (const ObjCMessageExpr *MsgE = dyn_cast<ObjCMessageExpr>(E)) {
-    Uses = WeakObjectUses.end();
+  else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
+    if (isa<VarDecl>(DRE->getDecl()))
+      Uses = WeakObjectUses.find(WeakObjectProfileTy(DRE));
+  } else if (const ObjCMessageExpr *MsgE = dyn_cast<ObjCMessageExpr>(E)) {
     if (const ObjCMethodDecl *MD = MsgE->getMethodDecl()) {
       if (const ObjCPropertyDecl *Prop = MD->findPropertyDecl()) {
         Uses =
diff --git a/lib/Sema/Sema.cpp b/lib/Sema/Sema.cpp
index 412f944f89c0..294b56059b33 100644
--- a/lib/Sema/Sema.cpp
+++ b/lib/Sema/Sema.cpp
@@ -122,8 +122,9 @@ Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
   // Tell diagnostics how to render things from the AST library.
   Diags.SetArgToStringFn(&FormatASTNodeDiagnosticArgument, &Context);
 
-  ExprEvalContexts.emplace_back(PotentiallyEvaluated, 0, CleanupInfo{}, nullptr,
-                                false);
+  ExprEvalContexts.emplace_back(
+      ExpressionEvaluationContext::PotentiallyEvaluated, 0, CleanupInfo{},
+      nullptr, false);
 
   FunctionScopes.push_back(new FunctionScopeInfo(Diags));
 
@@ -217,7 +218,6 @@ void Sema::Initialize() {
     if (getLangOpts().OpenCLVersion >= 200) {
       addImplicitTypedef("clk_event_t", Context.OCLClkEventTy);
       addImplicitTypedef("queue_t", Context.OCLQueueTy);
-      addImplicitTypedef("ndrange_t", Context.OCLNDRangeTy);
       addImplicitTypedef("reserve_id_t", Context.OCLReserveIDTy);
       addImplicitTypedef("atomic_int", Context.getAtomicType(Context.IntTy));
       addImplicitTypedef("atomic_uint",
@@ -328,7 +328,7 @@ bool Sema::makeUnavailableInSystemHeader(SourceLocation loc,
   if (!fn) return false;
 
   // If we're in template instantiation, it's an error.
-  if (!ActiveTemplateInstantiations.empty())
+  if (inTemplateInstantiation())
     return false;
 
   // If that function's not in a system header, it's an error.
@@ -745,7 +745,9 @@ void Sema::ActOnEndOfTranslationUnit() {
   UnusedFileScopedDecls.erase(
       std::remove_if(UnusedFileScopedDecls.begin(nullptr, true),
                      UnusedFileScopedDecls.end(),
-                     std::bind1st(std::ptr_fun(ShouldRemoveFromUnused), this)),
+                     [this](const DeclaratorDecl *DD) {
+                       return ShouldRemoveFromUnused(this, DD);
+                     }),
       UnusedFileScopedDecls.end());
 
   if (TUKind == TU_Prefix) {
@@ -1007,7 +1009,7 @@ void Sema::EmitCurrentDiagnostic(unsigned DiagID) {
   // and yet we also use the current diag ID on the DiagnosticsEngine. This has
   // been made more painfully obvious by the refactor that introduced this
   // function, but it is possible that the incoming argument can be
-  // eliminnated. If it truly cannot be (for example, there is some reentrancy
+  // eliminated. If it truly cannot be (for example, there is some reentrancy
   // issue I am not seeing yet), then there should at least be a clarifying
   // comment somewhere.
   if (Optional<TemplateDeductionInfo*> Info = isSFINAEContext()) {
@@ -1095,13 +1097,8 @@ void Sema::EmitCurrentDiagnostic(unsigned DiagID) {
   // that is different from the last template instantiation where
   // we emitted an error, print a template instantiation
   // backtrace.
-  if (!DiagnosticIDs::isBuiltinNote(DiagID) &&
-      !ActiveTemplateInstantiations.empty() &&
-      ActiveTemplateInstantiations.back()
-        != LastTemplateInstantiationErrorContext) {
-    PrintInstantiationStack();
-    LastTemplateInstantiationErrorContext = ActiveTemplateInstantiations.back();
-  }
+  if (!DiagnosticIDs::isBuiltinNote(DiagID))
+    PrintContextStack();
 }
 
 Sema::SemaDiagnosticBuilder
@@ -1236,21 +1233,21 @@ BlockScopeInfo *Sema::getCurBlock() {
   if (CurBSI && CurBSI->TheDecl &&
       !CurBSI->TheDecl->Encloses(CurContext)) {
     // We have switched contexts due to template instantiation.
-    assert(!ActiveTemplateInstantiations.empty());
+    assert(!CodeSynthesisContexts.empty());
     return nullptr;
   }
 
   return CurBSI;
 }
 
-LambdaScopeInfo *Sema::getCurLambda(bool IgnoreCapturedRegions) {
+LambdaScopeInfo *Sema::getCurLambda(bool IgnoreNonLambdaCapturingScope) {
   if (FunctionScopes.empty())
     return nullptr;
 
   auto I = FunctionScopes.rbegin();
-  if (IgnoreCapturedRegions) {
+  if (IgnoreNonLambdaCapturingScope) {
     auto E = FunctionScopes.rend();
-    while (I != E && isa<CapturedRegionScopeInfo>(*I))
+    while (I != E && isa<CapturingScopeInfo>(*I) && !isa<LambdaScopeInfo>(*I))
       ++I;
     if (I == E)
       return nullptr;
@@ -1259,7 +1256,7 @@ LambdaScopeInfo *Sema::getCurLambda(bool IgnoreCapturedRegions) {
   if (CurLSI && CurLSI->Lambda &&
       !CurLSI->Lambda->Encloses(CurContext)) {
     // We have switched contexts due to template instantiation.
-    assert(!ActiveTemplateInstantiations.empty());
+    assert(!CodeSynthesisContexts.empty());
     return nullptr;
   }
 
diff --git a/lib/Sema/SemaAttr.cpp b/lib/Sema/SemaAttr.cpp
index bad9e7024267..c6e3cc886316 100644
--- a/lib/Sema/SemaAttr.cpp
+++ b/lib/Sema/SemaAttr.cpp
@@ -215,6 +215,7 @@ void Sema::PragmaStack<ValueType>::Act(SourceLocation PragmaLocation,
                                        ValueType Value) {
   if (Action == PSK_Reset) {
     CurrentValue = DefaultValue;
+    CurrentPragmaLocation = PragmaLocation;
     return;
   }
   if (Action & PSK_Push)
@@ -447,16 +448,16 @@ void Sema::ActOnPragmaVisibility(const IdentifierInfo* VisType,
   }
 }
 
-void Sema::ActOnPragmaFPContract(tok::OnOffSwitch OOS) {
-  switch (OOS) {
-  case tok::OOS_ON:
-    FPFeatures.fp_contract = 1;
+void Sema::ActOnPragmaFPContract(LangOptions::FPContractModeKind FPC) {
+  switch (FPC) {
+  case LangOptions::FPC_On:
+    FPFeatures.setAllowFPContractWithinStatement();
     break;
-  case tok::OOS_OFF:
-    FPFeatures.fp_contract = 0; 
+  case LangOptions::FPC_Fast:
+    FPFeatures.setAllowFPContractAcrossStatement();
     break;
-  case tok::OOS_DEFAULT:
-    FPFeatures.fp_contract = getLangOpts().DefaultFPContract;
+  case LangOptions::FPC_Off:
+    FPFeatures.setDisallowFPContract();
     break;
   }
 }
diff --git a/lib/Sema/SemaCUDA.cpp b/lib/Sema/SemaCUDA.cpp
index 282633bbc9e1..b938ac387c4d 100644
--- a/lib/Sema/SemaCUDA.cpp
+++ b/lib/Sema/SemaCUDA.cpp
@@ -295,7 +295,7 @@ bool Sema::inferCUDATargetForImplicitSpecialMember(CXXRecordDecl *ClassDecl,
     }
 
     CXXRecordDecl *BaseClassDecl = cast<CXXRecordDecl>(BaseType->getDecl());
-    Sema::SpecialMemberOverloadResult *SMOR =
+    Sema::SpecialMemberOverloadResult SMOR =
         LookupSpecialMember(BaseClassDecl, CSM,
                             /* ConstArg */ ConstRHS,
                             /* VolatileArg */ false,
@@ -303,11 +303,10 @@ bool Sema::inferCUDATargetForImplicitSpecialMember(CXXRecordDecl *ClassDecl,
                             /* ConstThis */ false,
                             /* VolatileThis */ false);
 
-    if (!SMOR || !SMOR->getMethod()) {
+    if (!SMOR.getMethod())
       continue;
-    }
 
-    CUDAFunctionTarget BaseMethodTarget = IdentifyCUDATarget(SMOR->getMethod());
+    CUDAFunctionTarget BaseMethodTarget = IdentifyCUDATarget(SMOR.getMethod());
     if (!InferredTarget.hasValue()) {
       InferredTarget = BaseMethodTarget;
     } else {
@@ -339,7 +338,7 @@ bool Sema::inferCUDATargetForImplicitSpecialMember(CXXRecordDecl *ClassDecl,
     }
 
     CXXRecordDecl *FieldRecDecl = cast<CXXRecordDecl>(FieldType->getDecl());
-    Sema::SpecialMemberOverloadResult *SMOR =
+    Sema::SpecialMemberOverloadResult SMOR =
         LookupSpecialMember(FieldRecDecl, CSM,
                             /* ConstArg */ ConstRHS && !F->isMutable(),
                             /* VolatileArg */ false,
@@ -347,12 +346,11 @@ bool Sema::inferCUDATargetForImplicitSpecialMember(CXXRecordDecl *ClassDecl,
                             /* ConstThis */ false,
                             /* VolatileThis */ false);
 
-    if (!SMOR || !SMOR->getMethod()) {
+    if (!SMOR.getMethod())
       continue;
-    }
 
     CUDAFunctionTarget FieldMethodTarget =
-        IdentifyCUDATarget(SMOR->getMethod());
+        IdentifyCUDATarget(SMOR.getMethod());
     if (!InferredTarget.hasValue()) {
       InferredTarget = FieldMethodTarget;
     } else {
diff --git a/lib/Sema/SemaCXXScopeSpec.cpp b/lib/Sema/SemaCXXScopeSpec.cpp
index d8971c0d37eb..57471de78d3e 100644
--- a/lib/Sema/SemaCXXScopeSpec.cpp
+++ b/lib/Sema/SemaCXXScopeSpec.cpp
@@ -461,6 +461,7 @@ class NestedNameSpecifierValidatorCCC : public CorrectionCandidateCallback {
 ///        are allowed.  The bool value pointed by this parameter is set to
 ///       'true' if the identifier is treated as if it was followed by ':',
 ///        not '::'.
+/// \param OnlyNamespace If true, only considers namespaces in lookup.
 ///
 /// This routine differs only slightly from ActOnCXXNestedNameSpecifier, in
 /// that it contains an extra parameter \p ScopeLookupResult, which provides
@@ -473,15 +474,15 @@ class NestedNameSpecifierValidatorCCC : public CorrectionCandidateCallback {
 /// scope if it *knows* that the result is correct.  It should not return in a
 /// dependent context, for example. Nor will it extend \p SS with the scope
 /// specifier.
-bool Sema::BuildCXXNestedNameSpecifier(Scope *S,
-                                       NestedNameSpecInfo &IdInfo,
-                                       bool EnteringContext,
-                                       CXXScopeSpec &SS,
+bool Sema::BuildCXXNestedNameSpecifier(Scope *S, NestedNameSpecInfo &IdInfo,
+                                       bool EnteringContext, CXXScopeSpec &SS,
                                        NamedDecl *ScopeLookupResult,
                                        bool ErrorRecoveryLookup,
-                                       bool *IsCorrectedToColon) {
+                                       bool *IsCorrectedToColon,
+                                       bool OnlyNamespace) {
   LookupResult Found(*this, IdInfo.Identifier, IdInfo.IdentifierLoc,
-                     LookupNestedNameSpecifierName);
+                     OnlyNamespace ? LookupNamespaceName
+                                   : LookupNestedNameSpecifierName);
   QualType ObjectType = GetTypeFromParser(IdInfo.ObjectType);
 
   // Determine where to perform name lookup
@@ -594,7 +595,9 @@ bool Sema::BuildCXXNestedNameSpecifier(Scope *S,
         return true;
       }
       // Replacement '::' -> ':' is not allowed, just issue respective error.
-      Diag(R.getNameLoc(), diag::err_expected_class_or_namespace)
+      Diag(R.getNameLoc(), OnlyNamespace
+                               ? unsigned(diag::err_expected_namespace_name)
+                               : unsigned(diag::err_expected_class_or_namespace))
           << IdInfo.Identifier << getLangOpts().CPlusPlus;
       if (NamedDecl *ND = R.getAsSingle<NamedDecl>())
         Diag(ND->getLocation(), diag::note_entity_declared_at)
@@ -819,19 +822,17 @@ bool Sema::BuildCXXNestedNameSpecifier(Scope *S,
   return true;
 }
 
-bool Sema::ActOnCXXNestedNameSpecifier(Scope *S,
-                                       NestedNameSpecInfo &IdInfo,
-                                       bool EnteringContext,
-                                       CXXScopeSpec &SS,
+bool Sema::ActOnCXXNestedNameSpecifier(Scope *S, NestedNameSpecInfo &IdInfo,
+                                       bool EnteringContext, CXXScopeSpec &SS,
                                        bool ErrorRecoveryLookup,
-                                       bool *IsCorrectedToColon) {
+                                       bool *IsCorrectedToColon,
+                                       bool OnlyNamespace) {
   if (SS.isInvalid())
     return true;
 
-  return BuildCXXNestedNameSpecifier(S, IdInfo,
-                                     EnteringContext, SS,
+  return BuildCXXNestedNameSpecifier(S, IdInfo, EnteringContext, SS,
                                      /*ScopeLookupResult=*/nullptr, false,
-                                     IsCorrectedToColon);
+                                     IsCorrectedToColon, OnlyNamespace);
 }
 
 bool Sema::ActOnCXXNestedNameSpecifierDecltype(CXXScopeSpec &SS,
@@ -933,8 +934,8 @@ bool Sema::ActOnCXXNestedNameSpecifier(Scope *S,
 
   // We were able to resolve the template name to an actual template. 
   // Build an appropriate nested-name-specifier.
-  QualType T = CheckTemplateIdType(Template.get(), TemplateNameLoc, 
-                                   TemplateArgs);
+  QualType T =
+      CheckTemplateIdType(Template.get(), TemplateNameLoc, TemplateArgs);
   if (T.isNull())
     return true;
 
diff --git a/lib/Sema/SemaCast.cpp b/lib/Sema/SemaCast.cpp
index 6222e4cec47a..7e91709e67da 100644
--- a/lib/Sema/SemaCast.cpp
+++ b/lib/Sema/SemaCast.cpp
@@ -120,12 +120,12 @@ namespace {
       Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange);
     }
 
-    void checkObjCARCConversion(Sema::CheckedConversionKind CCK) {
-      assert(Self.getLangOpts().ObjCAutoRefCount);
+    void checkObjCConversion(Sema::CheckedConversionKind CCK) {
+      assert(Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers());
 
       Expr *src = SrcExpr.get();
-      if (Self.CheckObjCARCConversion(OpRange, DestType, src, CCK) ==
-            Sema::ACR_unbridged)
+      if (Self.CheckObjCConversion(OpRange, DestType, src, CCK) ==
+          Sema::ACR_unbridged)
         IsARCUnbridgedCast = true;
       SrcExpr = src;
     }
@@ -871,8 +871,8 @@ void CastOperation::CheckReinterpretCast() {
     }
     SrcExpr = ExprError();
   } else if (tcr == TC_Success) {
-    if (Self.getLangOpts().ObjCAutoRefCount)
-      checkObjCARCConversion(Sema::CCK_OtherCast);
+    if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers())
+      checkObjCConversion(Sema::CCK_OtherCast);
     DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange);
   }
 }
@@ -935,8 +935,8 @@ void CastOperation::CheckStaticCast() {
   } else if (tcr == TC_Success) {
     if (Kind == CK_BitCast)
       checkCastAlign();
-    if (Self.getLangOpts().ObjCAutoRefCount)
-      checkObjCARCConversion(Sema::CCK_OtherCast);
+    if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers())
+      checkObjCConversion(Sema::CCK_OtherCast);
   } else if (Kind == CK_BitCast) {
     checkCastAlign();
   }
@@ -1763,13 +1763,12 @@ static void DiagnoseCallingConvCast(Sema &Self, const ExprResult &SrcExpr,
   if (!DRE)
     return;
   auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl());
-  const FunctionDecl *Definition;
-  if (!FD || !FD->hasBody(Definition))
+  if (!FD)
     return;
 
   // Only warn if we are casting from the default convention to a non-default
   // convention. This can happen when the programmer forgot to apply the calling
-  // convention to the function definition and then inserted this cast to
+  // convention to the function declaration and then inserted this cast to
   // satisfy the type system.
   CallingConv DefaultCC = Self.getASTContext().getDefaultCallingConvention(
       FD->isVariadic(), FD->isCXXInstanceMember());
@@ -1792,7 +1791,7 @@ static void DiagnoseCallingConvCast(Sema &Self, const ExprResult &SrcExpr,
   // whose address was taken. Try to use the latest macro for the convention.
   // For example, users probably want to write "WINAPI" instead of "__stdcall"
   // to match the Windows header declarations.
-  SourceLocation NameLoc = Definition->getNameInfo().getLoc();
+  SourceLocation NameLoc = FD->getFirstDecl()->getNameInfo().getLoc();
   Preprocessor &PP = Self.getPreprocessor();
   SmallVector<TokenValue, 6> AttrTokens;
   SmallString<64> CCAttrText;
@@ -2273,8 +2272,9 @@ void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle,
     }
   }
 
-  if (Self.getLangOpts().ObjCAutoRefCount && tcr == TC_Success)
-    checkObjCARCConversion(CCK);
+  if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() &&
+      tcr == TC_Success)
+    checkObjCConversion(CCK);
 
   if (tcr != TC_Success && msg != 0) {
     if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
@@ -2540,12 +2540,13 @@ void CastOperation::CheckCStyleCast() {
   }
 
   // ARC imposes extra restrictions on casts.
-  if (Self.getLangOpts().ObjCAutoRefCount) {
-    checkObjCARCConversion(Sema::CCK_CStyleCast);
+  if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()) {
+    checkObjCConversion(Sema::CCK_CStyleCast);
     if (SrcExpr.isInvalid())
       return;
-    
-    if (const PointerType *CastPtr = DestType->getAs<PointerType>()) {
+
+    const PointerType *CastPtr = DestType->getAs<PointerType>();
+    if (Self.getLangOpts().ObjCAutoRefCount && CastPtr) {
       if (const PointerType *ExprPtr = SrcType->getAs<PointerType>()) {
         Qualifiers CastQuals = CastPtr->getPointeeType().getQualifiers();
         Qualifiers ExprQuals = ExprPtr->getPointeeType().getQualifiers();
@@ -2628,11 +2629,12 @@ ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc,
 }
 
 ExprResult Sema::BuildCXXFunctionalCastExpr(TypeSourceInfo *CastTypeInfo,
+                                            QualType Type,
                                             SourceLocation LPLoc,
                                             Expr *CastExpr,
                                             SourceLocation RPLoc) {
   assert(LPLoc.isValid() && "List-initialization shouldn't get here.");
-  CastOperation Op(*this, CastTypeInfo->getType(), CastExpr);
+  CastOperation Op(*this, Type, CastExpr);
   Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange();
   Op.OpRange = SourceRange(Op.DestRange.getBegin(), CastExpr->getLocEnd());
 
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 3aedb2a8c9bb..81db0d3d00a7 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -244,7 +244,7 @@ static bool SemaBuiltinSEHScopeCheck(Sema &SemaRef, CallExpr *TheCall,
   // Scopes aren't available during instantiation. Fortunately, builtin
   // functions cannot be template args so they cannot be formed through template
   // instantiation. Therefore checking once during the parse is sufficient.
-  if (!SemaRef.ActiveTemplateInstantiations.empty())
+  if (SemaRef.inTemplateInstantiation())
     return false;
 
   Scope *S = SemaRef.getCurScope();
@@ -315,7 +315,7 @@ static bool SemaOpenCLBuiltinKernelWorkGroupSize(Sema &S, CallExpr *TheCall) {
   return checkOpenCLBlockArgs(S, BlockArg);
 }
 
-/// Diagnose integer type and any valid implicit convertion to it.
+/// Diagnose integer type and any valid implicit conversion to it.
 static bool checkOpenCLEnqueueIntType(Sema &S, Expr *E,
                                       const QualType &IntType);
 
@@ -408,10 +408,10 @@ static bool SemaOpenCLBuiltinEnqueueKernel(Sema &S, CallExpr *TheCall) {
   }
 
   // Third argument is always an ndrange_t type.
-  if (!Arg2->getType()->isNDRangeT()) {
+  if (Arg2->getType().getAsString() != "ndrange_t") {
     S.Diag(TheCall->getArg(2)->getLocStart(),
            diag::err_opencl_enqueue_kernel_expected_type)
-        << S.Context.OCLNDRangeTy;
+        << "'ndrange_t'";
     return true;
   }
 
@@ -1619,32 +1619,28 @@ bool Sema::CheckMipsBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
   case Mips::BI__builtin_msa_copy_u_b:
   case Mips::BI__builtin_msa_insve_b:
   case Mips::BI__builtin_msa_splati_b: i = 1; l = 0; u = 15; break;
-  case Mips::BI__builtin_msa_sld_b:
   case Mips::BI__builtin_msa_sldi_b: i = 2; l = 0; u = 15; break;
   // These intrinsics take an unsigned 3 bit immediate.
   case Mips::BI__builtin_msa_copy_s_h:
   case Mips::BI__builtin_msa_copy_u_h:
   case Mips::BI__builtin_msa_insve_h:
   case Mips::BI__builtin_msa_splati_h: i = 1; l = 0; u = 7; break;
-  case Mips::BI__builtin_msa_sld_h:
   case Mips::BI__builtin_msa_sldi_h: i = 2; l = 0; u = 7; break;
   // These intrinsics take an unsigned 2 bit immediate.
   case Mips::BI__builtin_msa_copy_s_w:
   case Mips::BI__builtin_msa_copy_u_w:
   case Mips::BI__builtin_msa_insve_w:
   case Mips::BI__builtin_msa_splati_w: i = 1; l = 0; u = 3; break;
-  case Mips::BI__builtin_msa_sld_w:
   case Mips::BI__builtin_msa_sldi_w: i = 2; l = 0; u = 3; break;
   // These intrinsics take an unsigned 1 bit immediate.
   case Mips::BI__builtin_msa_copy_s_d:
   case Mips::BI__builtin_msa_copy_u_d:
   case Mips::BI__builtin_msa_insve_d:
   case Mips::BI__builtin_msa_splati_d: i = 1; l = 0; u = 1; break;
-  case Mips::BI__builtin_msa_sld_d:
   case Mips::BI__builtin_msa_sldi_d: i = 2; l = 0; u = 1; break;
   // Memory offsets and immediate loads.
   // These intrinsics take a signed 10 bit immediate.
-  case Mips::BI__builtin_msa_ldi_b: i = 0; l = -128; u = 127; break;
+  case Mips::BI__builtin_msa_ldi_b: i = 0; l = -128; u = 255; break;
   case Mips::BI__builtin_msa_ldi_h:
   case Mips::BI__builtin_msa_ldi_w:
   case Mips::BI__builtin_msa_ldi_d: i = 0; l = -512; u = 511; break;
@@ -1990,6 +1986,109 @@ bool Sema::CheckX86BuiltinRoundingOrSAE(unsigned BuiltinID, CallExpr *TheCall) {
     << Arg->getSourceRange();
 }
 
+// Check if the gather/scatter scale is legal.
+bool Sema::CheckX86BuiltinGatherScatterScale(unsigned BuiltinID,
+                                             CallExpr *TheCall) {
+  unsigned ArgNum = 0;
+  switch (BuiltinID) {
+  default:
+    return false;
+  case X86::BI__builtin_ia32_gatherpfdpd:
+  case X86::BI__builtin_ia32_gatherpfdps:
+  case X86::BI__builtin_ia32_gatherpfqpd:
+  case X86::BI__builtin_ia32_gatherpfqps:
+  case X86::BI__builtin_ia32_scatterpfdpd:
+  case X86::BI__builtin_ia32_scatterpfdps:
+  case X86::BI__builtin_ia32_scatterpfqpd:
+  case X86::BI__builtin_ia32_scatterpfqps:
+    ArgNum = 3;
+    break;
+  case X86::BI__builtin_ia32_gatherd_pd:
+  case X86::BI__builtin_ia32_gatherd_pd256:
+  case X86::BI__builtin_ia32_gatherq_pd:
+  case X86::BI__builtin_ia32_gatherq_pd256:
+  case X86::BI__builtin_ia32_gatherd_ps:
+  case X86::BI__builtin_ia32_gatherd_ps256:
+  case X86::BI__builtin_ia32_gatherq_ps:
+  case X86::BI__builtin_ia32_gatherq_ps256:
+  case X86::BI__builtin_ia32_gatherd_q:
+  case X86::BI__builtin_ia32_gatherd_q256:
+  case X86::BI__builtin_ia32_gatherq_q:
+  case X86::BI__builtin_ia32_gatherq_q256:
+  case X86::BI__builtin_ia32_gatherd_d:
+  case X86::BI__builtin_ia32_gatherd_d256:
+  case X86::BI__builtin_ia32_gatherq_d:
+  case X86::BI__builtin_ia32_gatherq_d256:
+  case X86::BI__builtin_ia32_gather3div2df:
+  case X86::BI__builtin_ia32_gather3div2di:
+  case X86::BI__builtin_ia32_gather3div4df:
+  case X86::BI__builtin_ia32_gather3div4di:
+  case X86::BI__builtin_ia32_gather3div4sf:
+  case X86::BI__builtin_ia32_gather3div4si:
+  case X86::BI__builtin_ia32_gather3div8sf:
+  case X86::BI__builtin_ia32_gather3div8si:
+  case X86::BI__builtin_ia32_gather3siv2df:
+  case X86::BI__builtin_ia32_gather3siv2di:
+  case X86::BI__builtin_ia32_gather3siv4df:
+  case X86::BI__builtin_ia32_gather3siv4di:
+  case X86::BI__builtin_ia32_gather3siv4sf:
+  case X86::BI__builtin_ia32_gather3siv4si:
+  case X86::BI__builtin_ia32_gather3siv8sf:
+  case X86::BI__builtin_ia32_gather3siv8si:
+  case X86::BI__builtin_ia32_gathersiv8df:
+  case X86::BI__builtin_ia32_gathersiv16sf:
+  case X86::BI__builtin_ia32_gatherdiv8df:
+  case X86::BI__builtin_ia32_gatherdiv16sf:
+  case X86::BI__builtin_ia32_gathersiv8di:
+  case X86::BI__builtin_ia32_gathersiv16si:
+  case X86::BI__builtin_ia32_gatherdiv8di:
+  case X86::BI__builtin_ia32_gatherdiv16si:
+  case X86::BI__builtin_ia32_scatterdiv2df:
+  case X86::BI__builtin_ia32_scatterdiv2di:
+  case X86::BI__builtin_ia32_scatterdiv4df:
+  case X86::BI__builtin_ia32_scatterdiv4di:
+  case X86::BI__builtin_ia32_scatterdiv4sf:
+  case X86::BI__builtin_ia32_scatterdiv4si:
+  case X86::BI__builtin_ia32_scatterdiv8sf:
+  case X86::BI__builtin_ia32_scatterdiv8si:
+  case X86::BI__builtin_ia32_scattersiv2df:
+  case X86::BI__builtin_ia32_scattersiv2di:
+  case X86::BI__builtin_ia32_scattersiv4df:
+  case X86::BI__builtin_ia32_scattersiv4di:
+  case X86::BI__builtin_ia32_scattersiv4sf:
+  case X86::BI__builtin_ia32_scattersiv4si:
+  case X86::BI__builtin_ia32_scattersiv8sf:
+  case X86::BI__builtin_ia32_scattersiv8si:
+  case X86::BI__builtin_ia32_scattersiv8df:
+  case X86::BI__builtin_ia32_scattersiv16sf:
+  case X86::BI__builtin_ia32_scatterdiv8df:
+  case X86::BI__builtin_ia32_scatterdiv16sf:
+  case X86::BI__builtin_ia32_scattersiv8di:
+  case X86::BI__builtin_ia32_scattersiv16si:
+  case X86::BI__builtin_ia32_scatterdiv8di:
+  case X86::BI__builtin_ia32_scatterdiv16si:
+    ArgNum = 4;
+    break;
+  }
+
+  llvm::APSInt Result;
+
+  // We can't check the value of a dependent argument.
+  Expr *Arg = TheCall->getArg(ArgNum);
+  if (Arg->isTypeDependent() || Arg->isValueDependent())
+    return false;
+
+  // Check constant-ness first.
+  if (SemaBuiltinConstantArg(TheCall, ArgNum, Result))
+    return true;
+
+  if (Result == 1 || Result == 2 || Result == 4 || Result == 8)
+    return false;
+
+  return Diag(TheCall->getLocStart(), diag::err_x86_builtin_invalid_scale)
+    << Arg->getSourceRange();
+}
+
 bool Sema::CheckX86BuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
   if (BuiltinID == X86::BI__builtin_cpu_supports)
     return SemaBuiltinCpuSupports(*this, TheCall);
@@ -2001,6 +2100,10 @@ bool Sema::CheckX86BuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
   if (CheckX86BuiltinRoundingOrSAE(BuiltinID, TheCall))
     return true;
 
+  // If the intrinsic has a gather/scatter scale immediate make sure its valid.
+  if (CheckX86BuiltinGatherScatterScale(BuiltinID, TheCall))
+    return true;
+
   // For intrinsics which take an immediate value as part of the instruction,
   // range check them here.
   int i = 0, l = 0, u = 0;
@@ -2197,6 +2300,16 @@ bool Sema::CheckX86BuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
   case X86::BI__builtin_ia32_pternlogq256_maskz:
     i = 3; l = 0; u = 255;
     break;
+  case X86::BI__builtin_ia32_gatherpfdpd:
+  case X86::BI__builtin_ia32_gatherpfdps:
+  case X86::BI__builtin_ia32_gatherpfqpd:
+  case X86::BI__builtin_ia32_gatherpfqps:
+  case X86::BI__builtin_ia32_scatterpfdpd:
+  case X86::BI__builtin_ia32_scatterpfdps:
+  case X86::BI__builtin_ia32_scatterpfqpd:
+  case X86::BI__builtin_ia32_scatterpfqps:
+    i = 4; l = 2; u = 3;
+    break;
   case X86::BI__builtin_ia32_pcmpestrm128:
   case X86::BI__builtin_ia32_pcmpestri128:
   case X86::BI__builtin_ia32_pcmpestria128:
@@ -6782,7 +6895,7 @@ void Sema::CheckMaxUnsignedZero(const CallExpr *Call,
   if (!Call || !FDecl) return;
 
   // Ignore template specializations and macros.
-  if (!ActiveTemplateInstantiations.empty()) return;
+  if (inTemplateInstantiation()) return;
   if (Call->getExprLoc().isMacroID()) return;
 
   // Only care about the one template argument, two function parameter std::max
@@ -7340,7 +7453,7 @@ CheckReturnStackAddr(Sema &S, Expr *RetValExp, QualType lhsType,
   if (!stackE)
     return; // Nothing suspicious was found.
 
-  // Parameters are initalized in the calling scope, so taking the address
+  // Parameters are initialized in the calling scope, so taking the address
   // of a parameter reference doesn't need a warning.
   for (auto *DRE : refVars)
     if (isa<ParmVarDecl>(DRE->getDecl()))
@@ -8235,7 +8348,7 @@ bool HasEnumType(Expr *E) {
 
 void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
   // Disable warning in template instantiations.
-  if (!S.ActiveTemplateInstantiations.empty())
+  if (S.inTemplateInstantiation())
     return;
 
   BinaryOperatorKind op = E->getOpcode();
@@ -8265,7 +8378,7 @@ void DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E, Expr *Constant,
                                   Expr *Other, const llvm::APSInt &Value,
                                   bool RhsConstant) {
   // Disable warning in template instantiations.
-  if (!S.ActiveTemplateInstantiations.empty())
+  if (S.inTemplateInstantiation())
     return;
 
   // TODO: Investigate using GetExprRange() to get tighter bounds
@@ -8616,13 +8729,66 @@ bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
     return false;
 
   Expr *OriginalInit = Init->IgnoreParenImpCasts();
+  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
 
   llvm::APSInt Value;
-  if (!OriginalInit->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects))
+  if (!OriginalInit->EvaluateAsInt(Value, S.Context,
+                                   Expr::SE_AllowSideEffects)) {
+    // The RHS is not constant.  If the RHS has an enum type, make sure the
+    // bitfield is wide enough to hold all the values of the enum without
+    // truncation.
+    if (const auto *EnumTy = OriginalInit->getType()->getAs<EnumType>()) {
+      EnumDecl *ED = EnumTy->getDecl();
+      bool SignedBitfield = BitfieldType->isSignedIntegerType();
+
+      // Enum types are implicitly signed on Windows, so check if there are any
+      // negative enumerators to see if the enum was intended to be signed or
+      // not.
+      bool SignedEnum = ED->getNumNegativeBits() > 0;
+
+      // Check for surprising sign changes when assigning enum values to a
+      // bitfield of different signedness.  If the bitfield is signed and we
+      // have exactly the right number of bits to store this unsigned enum,
+      // suggest changing the enum to an unsigned type. This typically happens
+      // on Windows where unfixed enums always use an underlying type of 'int'.
+      unsigned DiagID = 0;
+      if (SignedEnum && !SignedBitfield) {
+        DiagID = diag::warn_unsigned_bitfield_assigned_signed_enum;
+      } else if (SignedBitfield && !SignedEnum &&
+                 ED->getNumPositiveBits() == FieldWidth) {
+        DiagID = diag::warn_signed_bitfield_enum_conversion;
+      }
+
+      if (DiagID) {
+        S.Diag(InitLoc, DiagID) << Bitfield << ED;
+        TypeSourceInfo *TSI = Bitfield->getTypeSourceInfo();
+        SourceRange TypeRange =
+            TSI ? TSI->getTypeLoc().getSourceRange() : SourceRange();
+        S.Diag(Bitfield->getTypeSpecStartLoc(), diag::note_change_bitfield_sign)
+            << SignedEnum << TypeRange;
+      }
+
+      // Compute the required bitwidth. If the enum has negative values, we need
+      // one more bit than the normal number of positive bits to represent the
+      // sign bit.
+      unsigned BitsNeeded = SignedEnum ? std::max(ED->getNumPositiveBits() + 1,
+                                                  ED->getNumNegativeBits())
+                                       : ED->getNumPositiveBits();
+
+      // Check the bitwidth.
+      if (BitsNeeded > FieldWidth) {
+        Expr *WidthExpr = Bitfield->getBitWidth();
+        S.Diag(InitLoc, diag::warn_bitfield_too_small_for_enum)
+            << Bitfield << ED;
+        S.Diag(WidthExpr->getExprLoc(), diag::note_widen_bitfield)
+            << BitsNeeded << ED << WidthExpr->getSourceRange();
+      }
+    }
+
     return false;
+  }
 
   unsigned OriginalWidth = Value.getBitWidth();
-  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
 
   if (!Value.isSigned() || Value.isNegative())
     if (UnaryOperator *UO = dyn_cast<UnaryOperator>(OriginalInit))
@@ -8703,7 +8869,7 @@ void DiagnoseFloatingImpCast(Sema &S, Expr *E, QualType T,
 
                              SourceLocation CContext) {
   const bool IsBool = T->isSpecificBuiltinType(BuiltinType::Bool);
-  const bool PruneWarnings = !S.ActiveTemplateInstantiations.empty();
+  const bool PruneWarnings = S.inTemplateInstantiation();
 
   Expr *InnerE = E->IgnoreParenImpCasts();
   // We also want to warn on, e.g., "int i = -1.234"
@@ -10609,6 +10775,12 @@ void Sema::CheckArrayAccess(const Expr *expr) {
           CheckArrayAccess(rhs);
         return;
       }
+      case Stmt::CXXOperatorCallExprClass: {
+        const auto *OCE = cast<CXXOperatorCallExpr>(expr);
+        for (const auto *Arg : OCE->arguments())
+          CheckArrayAccess(Arg);
+        return;
+      }
       default:
         return;
     }
@@ -11314,7 +11486,7 @@ void Sema::DiagnoseSelfMove(const Expr *LHSExpr, const Expr *RHSExpr,
   if (Diags.isIgnored(diag::warn_sizeof_pointer_expr_memaccess, OpLoc))
     return;
 
-  if (!ActiveTemplateInstantiations.empty())
+  if (inTemplateInstantiation())
     return;
 
   // Strip parens and casts away.
@@ -11839,6 +12011,10 @@ void Sema::RefersToMemberWithReducedAlignment(
   if (!ME)
     return;
 
+  // No need to check expressions with an __unaligned-qualified type.
+  if (E->getType().getQualifiers().hasUnaligned())
+    return;
+
   // For a chain of MemberExpr like "a.b.c.d" this list
   // will keep FieldDecl's like [d, c, b].
   SmallVector<FieldDecl *, 4> ReverseMemberChain;
diff --git a/lib/Sema/SemaCodeComplete.cpp b/lib/Sema/SemaCodeComplete.cpp
index 94cfc4baca51..cfac3f1dc1de 100644
--- a/lib/Sema/SemaCodeComplete.cpp
+++ b/lib/Sema/SemaCodeComplete.cpp
@@ -1334,8 +1334,9 @@ static void AddTypeSpecifierResults(const LangOptions &LangOpts,
       Builder.AddChunk(CodeCompletionString::CK_RightParen);
       Results.AddResult(Result(Builder.TakeString()));
     }
-  }
-  
+  } else
+    Results.AddResult(Result("__auto_type", CCP_Type));
+
   // GNU extensions
   if (LangOpts.GNUMode) {
     // FIXME: Enable when we actually support decimal floating point.
@@ -1370,6 +1371,21 @@ static void AddStorageSpecifiers(Sema::ParserCompletionContext CCC,
   // in C++0x as a type specifier.
   Results.AddResult(Result("extern"));
   Results.AddResult(Result("static"));
+
+  if (LangOpts.CPlusPlus11) {
+    CodeCompletionAllocator &Allocator = Results.getAllocator();
+    CodeCompletionBuilder Builder(Allocator, Results.getCodeCompletionTUInfo());
+
+    // alignas
+    Builder.AddTypedTextChunk("alignas");
+    Builder.AddChunk(CodeCompletionString::CK_LeftParen);
+    Builder.AddPlaceholderChunk("expression");
+    Builder.AddChunk(CodeCompletionString::CK_RightParen);
+    Results.AddResult(Result(Builder.TakeString()));
+
+    Results.AddResult(Result("constexpr"));
+    Results.AddResult(Result("thread_local"));
+  }
 }
 
 static void AddFunctionSpecifiers(Sema::ParserCompletionContext CCC,
@@ -1527,6 +1543,21 @@ static void addThisCompletion(Sema &S, ResultBuilder &Results) {
   Results.AddResult(CodeCompletionResult(Builder.TakeString()));
 }
 
+static void AddStaticAssertResult(CodeCompletionBuilder &Builder,
+                                  ResultBuilder &Results,
+                                  const LangOptions &LangOpts) {
+  if (!LangOpts.CPlusPlus11)
+    return;
+
+  Builder.AddTypedTextChunk("static_assert");
+  Builder.AddChunk(CodeCompletionString::CK_LeftParen);
+  Builder.AddPlaceholderChunk("expression");
+  Builder.AddChunk(CodeCompletionString::CK_Comma);
+  Builder.AddPlaceholderChunk("message");
+  Builder.AddChunk(CodeCompletionString::CK_RightParen);
+  Results.AddResult(CodeCompletionResult(Builder.TakeString()));
+}
+
 /// \brief Add language constructs that show up for "ordinary" names.
 static void AddOrdinaryNameResults(Sema::ParserCompletionContext CCC,
                                    Scope *S,
@@ -1611,6 +1642,8 @@ static void AddOrdinaryNameResults(Sema::ParserCompletionContext CCC,
         Results.AddResult(Result(Builder.TakeString()));
       }
 
+      AddStaticAssertResult(Builder, Results, SemaRef.getLangOpts());
+
       if (CCC == Sema::PCC_Class) {
         AddTypedefResult(Results);
 
@@ -1824,6 +1857,8 @@ static void AddOrdinaryNameResults(Sema::ParserCompletionContext CCC,
     Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
     Builder.AddPlaceholderChunk("identifier");
     Results.AddResult(Result(Builder.TakeString()));
+
+    AddStaticAssertResult(Builder, Results, SemaRef.getLangOpts());
   }
 
   // Fall through (for statement expressions).
@@ -2253,6 +2288,15 @@ static std::string FormatFunctionParameter(const PrintingPolicy &Policy,
   FunctionProtoTypeLoc BlockProto;
   findTypeLocationForBlockDecl(Param->getTypeSourceInfo(), Block, BlockProto,
                                SuppressBlock);
+  // Try to retrieve the block type information from the property if this is a
+  // parameter in a setter.
+  if (!Block && ObjCMethodParam &&
+      cast<ObjCMethodDecl>(Param->getDeclContext())->isPropertyAccessor()) {
+    if (const auto *PD = cast<ObjCMethodDecl>(Param->getDeclContext())
+                             ->findPropertyDecl(/*CheckOverrides=*/false))
+      findTypeLocationForBlockDecl(PD->getTypeSourceInfo(), Block, BlockProto,
+                                   SuppressBlock);
+  }
 
   if (!Block) {
     // We were unable to find a FunctionProtoTypeLoc with parameter names
@@ -2585,6 +2629,7 @@ static void AddTypedNameChunk(ASTContext &Context, const PrintingPolicy &Policy,
                       Result.getAllocator().CopyString(ND->getNameAsString()));
     break;
       
+  case DeclarationName::CXXDeductionGuideName:
   case DeclarationName::CXXUsingDirective:
   case DeclarationName::ObjCZeroArgSelector:
   case DeclarationName::ObjCOneArgSelector:
@@ -3482,6 +3527,11 @@ void Sema::CodeCompleteDeclSpec(Scope *S, DeclSpec &DS,
     Results.AddResult(Result("restrict"));
 
   if (getLangOpts().CPlusPlus) {
+    if (getLangOpts().CPlusPlus11 &&
+        (DS.getTypeSpecType() == DeclSpec::TST_class ||
+         DS.getTypeSpecType() == DeclSpec::TST_struct))
+      Results.AddResult("final");
+
     if (AllowNonIdentifiers) {
       Results.AddResult(Result("operator")); 
     }
@@ -4012,30 +4062,54 @@ void Sema::CodeCompleteTag(Scope *S, unsigned TagSpec) {
                             Results.data(),Results.size());
 }
 
-void Sema::CodeCompleteTypeQualifiers(DeclSpec &DS) {
-  ResultBuilder Results(*this, CodeCompleter->getAllocator(),
-                        CodeCompleter->getCodeCompletionTUInfo(),
-                        CodeCompletionContext::CCC_TypeQualifiers);
-  Results.EnterNewScope();
+static void AddTypeQualifierResults(DeclSpec &DS, ResultBuilder &Results,
+                                    const LangOptions &LangOpts) {
   if (!(DS.getTypeQualifiers() & DeclSpec::TQ_const))
     Results.AddResult("const");
   if (!(DS.getTypeQualifiers() & DeclSpec::TQ_volatile))
     Results.AddResult("volatile");
-  if (getLangOpts().C99 &&
-      !(DS.getTypeQualifiers() & DeclSpec::TQ_restrict))
+  if (LangOpts.C99 && !(DS.getTypeQualifiers() & DeclSpec::TQ_restrict))
     Results.AddResult("restrict");
-  if (getLangOpts().C11 &&
-      !(DS.getTypeQualifiers() & DeclSpec::TQ_atomic))
+  if (LangOpts.C11 && !(DS.getTypeQualifiers() & DeclSpec::TQ_atomic))
     Results.AddResult("_Atomic");
-  if (getLangOpts().MSVCCompat &&
-      !(DS.getTypeQualifiers() & DeclSpec::TQ_unaligned))
+  if (LangOpts.MSVCCompat && !(DS.getTypeQualifiers() & DeclSpec::TQ_unaligned))
     Results.AddResult("__unaligned");
+}
+
+void Sema::CodeCompleteTypeQualifiers(DeclSpec &DS) {
+  ResultBuilder Results(*this, CodeCompleter->getAllocator(),
+                        CodeCompleter->getCodeCompletionTUInfo(),
+                        CodeCompletionContext::CCC_TypeQualifiers);
+  Results.EnterNewScope();
+  AddTypeQualifierResults(DS, Results, LangOpts);
   Results.ExitScope();
   HandleCodeCompleteResults(this, CodeCompleter, 
                             Results.getCompletionContext(),
                             Results.data(), Results.size());
 }
 
+void Sema::CodeCompleteFunctionQualifiers(DeclSpec &DS, Declarator &D,
+                                          const VirtSpecifiers *VS) {
+  ResultBuilder Results(*this, CodeCompleter->getAllocator(),
+                        CodeCompleter->getCodeCompletionTUInfo(),
+                        CodeCompletionContext::CCC_TypeQualifiers);
+  Results.EnterNewScope();
+  AddTypeQualifierResults(DS, Results, LangOpts);
+  if (LangOpts.CPlusPlus11) {
+    Results.AddResult("noexcept");
+    if (D.getContext() == Declarator::MemberContext && !D.isCtorOrDtor() &&
+        !D.isStaticMember()) {
+      if (!VS || !VS->isFinalSpecified())
+        Results.AddResult("final");
+      if (!VS || !VS->isOverrideSpecified())
+        Results.AddResult("override");
+    }
+  }
+  Results.ExitScope();
+  HandleCodeCompleteResults(this, CodeCompleter, Results.getCompletionContext(),
+                            Results.data(), Results.size());
+}
+
 void Sema::CodeCompleteBracketDeclarator(Scope *S) {
   CodeCompleteExpression(S, QualType(getASTContext().getSizeType()));
 }
@@ -4244,7 +4318,10 @@ void Sema::CodeCompleteCall(Scope *S, Expr *Fn, ArrayRef<Expr *> Args) {
       UME->copyTemplateArgumentsInto(TemplateArgsBuffer);
       TemplateArgs = &TemplateArgsBuffer;
     }
-    SmallVector<Expr *, 12> ArgExprs(1, UME->getBase());
+
+    // Add the base as first argument (use a nullptr if the base is implicit).
+    SmallVector<Expr *, 12> ArgExprs(
+        1, UME->isImplicitAccess() ? nullptr : UME->getBase());
     ArgExprs.append(Args.begin(), Args.end());
     UnresolvedSet<8> Decls;
     Decls.append(UME->decls_begin(), UME->decls_end());
@@ -5230,24 +5307,22 @@ namespace {
 /// when it has the same number of parameters as we have selector identifiers.
 ///
 /// \param Results the structure into which we'll add results.
-static void AddObjCMethods(ObjCContainerDecl *Container, 
-                           bool WantInstanceMethods,
-                           ObjCMethodKind WantKind,
+static void AddObjCMethods(ObjCContainerDecl *Container,
+                           bool WantInstanceMethods, ObjCMethodKind WantKind,
                            ArrayRef<IdentifierInfo *> SelIdents,
                            DeclContext *CurContext,
-                           VisitedSelectorSet &Selectors,
-                           bool AllowSameLength,
-                           ResultBuilder &Results,
-                           bool InOriginalClass = true) {
+                           VisitedSelectorSet &Selectors, bool AllowSameLength,
+                           ResultBuilder &Results, bool InOriginalClass = true,
+                           bool IsRootClass = false) {
   typedef CodeCompletionResult Result;
   Container = getContainerDef(Container);
   ObjCInterfaceDecl *IFace = dyn_cast<ObjCInterfaceDecl>(Container);
-  bool isRootClass = IFace && !IFace->getSuperClass();
+  IsRootClass = IsRootClass || (IFace && !IFace->getSuperClass());
   for (auto *M : Container->methods()) {
     // The instance methods on the root class can be messaged via the
     // metaclass.
     if (M->isInstanceMethod() == WantInstanceMethods ||
-        (isRootClass && !WantInstanceMethods)) {
+        (IsRootClass && !WantInstanceMethods)) {
       // Check whether the selector identifiers we've been given are a 
       // subset of the identifiers for this particular method.
       if (!isAcceptableObjCMethod(M, WantKind, SelIdents, AllowSameLength))
@@ -5273,8 +5348,8 @@ static void AddObjCMethods(ObjCContainerDecl *Container,
       for (ObjCList<ObjCProtocolDecl>::iterator I = Protocols.begin(),
                                                 E = Protocols.end(); 
            I != E; ++I)
-        AddObjCMethods(*I, WantInstanceMethods, WantKind, SelIdents, 
-                       CurContext, Selectors, AllowSameLength, Results, false);
+        AddObjCMethods(*I, WantInstanceMethods, WantKind, SelIdents, CurContext,
+                       Selectors, AllowSameLength, Results, false, IsRootClass);
     }
   }
   
@@ -5283,43 +5358,43 @@ static void AddObjCMethods(ObjCContainerDecl *Container,
   
   // Add methods in protocols.
   for (auto *I : IFace->protocols())
-    AddObjCMethods(I, WantInstanceMethods, WantKind, SelIdents,
-                   CurContext, Selectors, AllowSameLength, Results, false);
-  
+    AddObjCMethods(I, WantInstanceMethods, WantKind, SelIdents, CurContext,
+                   Selectors, AllowSameLength, Results, false, IsRootClass);
+
   // Add methods in categories.
   for (auto *CatDecl : IFace->known_categories()) {
     AddObjCMethods(CatDecl, WantInstanceMethods, WantKind, SelIdents,
-                   CurContext, Selectors, AllowSameLength,
-                   Results, InOriginalClass);
-    
+                   CurContext, Selectors, AllowSameLength, Results,
+                   InOriginalClass, IsRootClass);
+
     // Add a categories protocol methods.
     const ObjCList<ObjCProtocolDecl> &Protocols 
       = CatDecl->getReferencedProtocols();
     for (ObjCList<ObjCProtocolDecl>::iterator I = Protocols.begin(),
                                               E = Protocols.end();
          I != E; ++I)
-      AddObjCMethods(*I, WantInstanceMethods, WantKind, SelIdents, 
-                     CurContext, Selectors, AllowSameLength,
-                     Results, false);
-    
+      AddObjCMethods(*I, WantInstanceMethods, WantKind, SelIdents, CurContext,
+                     Selectors, AllowSameLength, Results, false, IsRootClass);
+
     // Add methods in category implementations.
     if (ObjCCategoryImplDecl *Impl = CatDecl->getImplementation())
-      AddObjCMethods(Impl, WantInstanceMethods, WantKind, SelIdents, 
-                     CurContext, Selectors, AllowSameLength,
-                     Results, InOriginalClass);
+      AddObjCMethods(Impl, WantInstanceMethods, WantKind, SelIdents, CurContext,
+                     Selectors, AllowSameLength, Results, InOriginalClass,
+                     IsRootClass);
   }
   
   // Add methods in superclass.
+  // Avoid passing in IsRootClass since root classes won't have super classes.
   if (IFace->getSuperClass())
-    AddObjCMethods(IFace->getSuperClass(), WantInstanceMethods, WantKind, 
-                   SelIdents, CurContext, Selectors,
-                   AllowSameLength, Results, false);
+    AddObjCMethods(IFace->getSuperClass(), WantInstanceMethods, WantKind,
+                   SelIdents, CurContext, Selectors, AllowSameLength, Results,
+                   /*IsRootClass=*/false);
 
   // Add methods in our implementation, if any.
   if (ObjCImplementationDecl *Impl = IFace->getImplementation())
-    AddObjCMethods(Impl, WantInstanceMethods, WantKind, SelIdents,
-                   CurContext, Selectors, AllowSameLength,
-                   Results, InOriginalClass);
+    AddObjCMethods(Impl, WantInstanceMethods, WantKind, SelIdents, CurContext,
+                   Selectors, AllowSameLength, Results, InOriginalClass,
+                   IsRootClass);
 }
 
 
diff --git a/lib/Sema/SemaCoroutine.cpp b/lib/Sema/SemaCoroutine.cpp
index 9814b4a84f29..4a55e51495a8 100644
--- a/lib/Sema/SemaCoroutine.cpp
+++ b/lib/Sema/SemaCoroutine.cpp
@@ -11,31 +11,46 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "clang/Sema/SemaInternal.h"
+#include "CoroutineStmtBuilder.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/StmtCXX.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/Initialization.h"
 #include "clang/Sema/Overload.h"
+#include "clang/Sema/SemaInternal.h"
+
 using namespace clang;
 using namespace sema;
 
+static bool lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
+                         SourceLocation Loc) {
+  DeclarationName DN = S.PP.getIdentifierInfo(Name);
+  LookupResult LR(S, DN, Loc, Sema::LookupMemberName);
+  // Suppress diagnostics when a private member is selected. The same warnings
+  // will be produced again when building the call.
+  LR.suppressDiagnostics();
+  return S.LookupQualifiedName(LR, RD);
+}
+
 /// Look up the std::coroutine_traits<...>::promise_type for the given
 /// function type.
 static QualType lookupPromiseType(Sema &S, const FunctionProtoType *FnType,
-                                  SourceLocation Loc) {
+                                  SourceLocation KwLoc,
+                                  SourceLocation FuncLoc) {
   // FIXME: Cache std::coroutine_traits once we've found it.
   NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace();
   if (!StdExp) {
-    S.Diag(Loc, diag::err_implied_std_coroutine_traits_not_found);
+    S.Diag(KwLoc, diag::err_implied_coroutine_type_not_found)
+        << "std::experimental::coroutine_traits";
     return QualType();
   }
 
   LookupResult Result(S, &S.PP.getIdentifierTable().get("coroutine_traits"),
-                      Loc, Sema::LookupOrdinaryName);
+                      FuncLoc, Sema::LookupOrdinaryName);
   if (!S.LookupQualifiedName(Result, StdExp)) {
-    S.Diag(Loc, diag::err_implied_std_coroutine_traits_not_found);
+    S.Diag(KwLoc, diag::err_implied_coroutine_type_not_found)
+        << "std::experimental::coroutine_traits";
     return QualType();
   }
 
@@ -49,56 +64,107 @@ static QualType lookupPromiseType(Sema &S, const FunctionProtoType *FnType,
   }
 
   // Form template argument list for coroutine_traits<R, P1, P2, ...>.
-  TemplateArgumentListInfo Args(Loc, Loc);
+  TemplateArgumentListInfo Args(KwLoc, KwLoc);
   Args.addArgument(TemplateArgumentLoc(
       TemplateArgument(FnType->getReturnType()),
-      S.Context.getTrivialTypeSourceInfo(FnType->getReturnType(), Loc)));
+      S.Context.getTrivialTypeSourceInfo(FnType->getReturnType(), KwLoc)));
   // FIXME: If the function is a non-static member function, add the type
   // of the implicit object parameter before the formal parameters.
   for (QualType T : FnType->getParamTypes())
     Args.addArgument(TemplateArgumentLoc(
-        TemplateArgument(T), S.Context.getTrivialTypeSourceInfo(T, Loc)));
+        TemplateArgument(T), S.Context.getTrivialTypeSourceInfo(T, KwLoc)));
 
   // Build the template-id.
   QualType CoroTrait =
-      S.CheckTemplateIdType(TemplateName(CoroTraits), Loc, Args);
+      S.CheckTemplateIdType(TemplateName(CoroTraits), KwLoc, Args);
   if (CoroTrait.isNull())
     return QualType();
-  if (S.RequireCompleteType(Loc, CoroTrait,
-                            diag::err_coroutine_traits_missing_specialization))
+  if (S.RequireCompleteType(KwLoc, CoroTrait,
+                            diag::err_coroutine_type_missing_specialization))
     return QualType();
 
-  CXXRecordDecl *RD = CoroTrait->getAsCXXRecordDecl();
+  auto *RD = CoroTrait->getAsCXXRecordDecl();
   assert(RD && "specialization of class template is not a class?");
 
   // Look up the ::promise_type member.
-  LookupResult R(S, &S.PP.getIdentifierTable().get("promise_type"), Loc,
+  LookupResult R(S, &S.PP.getIdentifierTable().get("promise_type"), KwLoc,
                  Sema::LookupOrdinaryName);
   S.LookupQualifiedName(R, RD);
   auto *Promise = R.getAsSingle<TypeDecl>();
   if (!Promise) {
-    S.Diag(Loc, diag::err_implied_std_coroutine_traits_promise_type_not_found)
+    S.Diag(FuncLoc,
+           diag::err_implied_std_coroutine_traits_promise_type_not_found)
         << RD;
     return QualType();
   }
-
   // The promise type is required to be a class type.
   QualType PromiseType = S.Context.getTypeDeclType(Promise);
-  if (!PromiseType->getAsCXXRecordDecl()) {
-    // Use the fully-qualified name of the type.
+
+  auto buildElaboratedType = [&]() {
     auto *NNS = NestedNameSpecifier::Create(S.Context, nullptr, StdExp);
     NNS = NestedNameSpecifier::Create(S.Context, NNS, false,
                                       CoroTrait.getTypePtr());
-    PromiseType = S.Context.getElaboratedType(ETK_None, NNS, PromiseType);
+    return S.Context.getElaboratedType(ETK_None, NNS, PromiseType);
+  };
 
-    S.Diag(Loc, diag::err_implied_std_coroutine_traits_promise_type_not_class)
-        << PromiseType;
+  if (!PromiseType->getAsCXXRecordDecl()) {
+    S.Diag(FuncLoc,
+           diag::err_implied_std_coroutine_traits_promise_type_not_class)
+        << buildElaboratedType();
     return QualType();
   }
+  if (S.RequireCompleteType(FuncLoc, buildElaboratedType(),
+                            diag::err_coroutine_promise_type_incomplete))
+    return QualType();
 
   return PromiseType;
 }
 
+/// Look up the std::coroutine_traits<...>::promise_type for the given
+/// function type.
+static QualType lookupCoroutineHandleType(Sema &S, QualType PromiseType,
+                                          SourceLocation Loc) {
+  if (PromiseType.isNull())
+    return QualType();
+
+  NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace();
+  assert(StdExp && "Should already be diagnosed");
+
+  LookupResult Result(S, &S.PP.getIdentifierTable().get("coroutine_handle"),
+                      Loc, Sema::LookupOrdinaryName);
+  if (!S.LookupQualifiedName(Result, StdExp)) {
+    S.Diag(Loc, diag::err_implied_coroutine_type_not_found)
+        << "std::experimental::coroutine_handle";
+    return QualType();
+  }
+
+  ClassTemplateDecl *CoroHandle = Result.getAsSingle<ClassTemplateDecl>();
+  if (!CoroHandle) {
+    Result.suppressDiagnostics();
+    // We found something weird. Complain about the first thing we found.
+    NamedDecl *Found = *Result.begin();
+    S.Diag(Found->getLocation(), diag::err_malformed_std_coroutine_handle);
+    return QualType();
+  }
+
+  // Form template argument list for coroutine_handle<Promise>.
+  TemplateArgumentListInfo Args(Loc, Loc);
+  Args.addArgument(TemplateArgumentLoc(
+      TemplateArgument(PromiseType),
+      S.Context.getTrivialTypeSourceInfo(PromiseType, Loc)));
+
+  // Build the template-id.
+  QualType CoroHandleType =
+      S.CheckTemplateIdType(TemplateName(CoroHandle), Loc, Args);
+  if (CoroHandleType.isNull())
+    return QualType();
+  if (S.RequireCompleteType(Loc, CoroHandleType,
+                            diag::err_coroutine_type_missing_specialization))
+    return QualType();
+
+  return CoroHandleType;
+}
+
 static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
                                     StringRef Keyword) {
   // 'co_await' and 'co_yield' are not permitted in unevaluated operands.
@@ -160,41 +226,48 @@ static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
   return !Diagnosed;
 }
 
-/// Check that this is a context in which a coroutine suspension can appear.
-static FunctionScopeInfo *checkCoroutineContext(Sema &S, SourceLocation Loc,
-                                                StringRef Keyword) {
-  if (!isValidCoroutineContext(S, Loc, Keyword))
-    return nullptr;
-
-  assert(isa<FunctionDecl>(S.CurContext) && "not in a function scope");
-  auto *FD = cast<FunctionDecl>(S.CurContext);
-  auto *ScopeInfo = S.getCurFunction();
-  assert(ScopeInfo && "missing function scope for function");
+static ExprResult buildOperatorCoawaitLookupExpr(Sema &SemaRef, Scope *S,
+                                                 SourceLocation Loc) {
+  DeclarationName OpName =
+      SemaRef.Context.DeclarationNames.getCXXOperatorName(OO_Coawait);
+  LookupResult Operators(SemaRef, OpName, SourceLocation(),
+                         Sema::LookupOperatorName);
+  SemaRef.LookupName(Operators, S);
+
+  assert(!Operators.isAmbiguous() && "Operator lookup cannot be ambiguous");
+  const auto &Functions = Operators.asUnresolvedSet();
+  bool IsOverloaded =
+      Functions.size() > 1 ||
+      (Functions.size() == 1 && isa<FunctionTemplateDecl>(*Functions.begin()));
+  Expr *CoawaitOp = UnresolvedLookupExpr::Create(
+      SemaRef.Context, /*NamingClass*/ nullptr, NestedNameSpecifierLoc(),
+      DeclarationNameInfo(OpName, Loc), /*RequiresADL*/ true, IsOverloaded,
+      Functions.begin(), Functions.end());
+  assert(CoawaitOp);
+  return CoawaitOp;
+}
 
-  // If we don't have a promise variable, build one now.
-  if (!ScopeInfo->CoroutinePromise) {
-    QualType T = FD->getType()->isDependentType()
-                     ? S.Context.DependentTy
-                     : lookupPromiseType(
-                           S, FD->getType()->castAs<FunctionProtoType>(), Loc);
-    if (T.isNull())
-      return nullptr;
-
-    // Create and default-initialize the promise.
-    ScopeInfo->CoroutinePromise =
-        VarDecl::Create(S.Context, FD, FD->getLocation(), FD->getLocation(),
-                        &S.PP.getIdentifierTable().get("__promise"), T,
-                        S.Context.getTrivialTypeSourceInfo(T, Loc), SC_None);
-    S.CheckVariableDeclarationType(ScopeInfo->CoroutinePromise);
-    if (!ScopeInfo->CoroutinePromise->isInvalidDecl())
-      S.ActOnUninitializedDecl(ScopeInfo->CoroutinePromise);
-  }
+/// Build a call to 'operator co_await' if there is a suitable operator for
+/// the given expression.
+static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, SourceLocation Loc,
+                                           Expr *E,
+                                           UnresolvedLookupExpr *Lookup) {
+  UnresolvedSet<16> Functions;
+  Functions.append(Lookup->decls_begin(), Lookup->decls_end());
+  return SemaRef.CreateOverloadedUnaryOp(Loc, UO_Coawait, Functions, E);
+}
 
-  return ScopeInfo;
+static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, Scope *S,
+                                           SourceLocation Loc, Expr *E) {
+  ExprResult R = buildOperatorCoawaitLookupExpr(SemaRef, S, Loc);
+  if (R.isInvalid())
+    return ExprError();
+  return buildOperatorCoawaitCall(SemaRef, Loc, E,
+                                  cast<UnresolvedLookupExpr>(R.get()));
 }
 
 static Expr *buildBuiltinCall(Sema &S, SourceLocation Loc, Builtin::ID Id,
-                              MutableArrayRef<Expr *> CallArgs) {
+                              MultiExprArg CallArgs) {
   StringRef Name = S.Context.BuiltinInfo.getName(Id);
   LookupResult R(S, &S.Context.Idents.get(Name), Loc, Sema::LookupOrdinaryName);
   S.LookupName(R, S.TUScope, /*AllowBuiltinCreation=*/true);
@@ -213,24 +286,41 @@ static Expr *buildBuiltinCall(Sema &S, SourceLocation Loc, Builtin::ID Id,
   return Call.get();
 }
 
-/// Build a call to 'operator co_await' if there is a suitable operator for
-/// the given expression.
-static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, Scope *S,
-                                           SourceLocation Loc, Expr *E) {
-  UnresolvedSet<16> Functions;
-  SemaRef.LookupOverloadedOperatorName(OO_Coawait, S, E->getType(), QualType(),
-                                       Functions);
-  return SemaRef.CreateOverloadedUnaryOp(Loc, UO_Coawait, Functions, E);
+static ExprResult buildCoroutineHandle(Sema &S, QualType PromiseType,
+                                       SourceLocation Loc) {
+  QualType CoroHandleType = lookupCoroutineHandleType(S, PromiseType, Loc);
+  if (CoroHandleType.isNull())
+    return ExprError();
+
+  DeclContext *LookupCtx = S.computeDeclContext(CoroHandleType);
+  LookupResult Found(S, &S.PP.getIdentifierTable().get("from_address"), Loc,
+                     Sema::LookupOrdinaryName);
+  if (!S.LookupQualifiedName(Found, LookupCtx)) {
+    S.Diag(Loc, diag::err_coroutine_handle_missing_member)
+        << "from_address";
+    return ExprError();
+  }
+
+  Expr *FramePtr =
+      buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_frame, {});
+
+  CXXScopeSpec SS;
+  ExprResult FromAddr =
+      S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
+  if (FromAddr.isInvalid())
+    return ExprError();
+
+  return S.ActOnCallExpr(nullptr, FromAddr.get(), Loc, FramePtr, Loc);
 }
 
 struct ReadySuspendResumeResult {
-  bool IsInvalid;
   Expr *Results[3];
+  OpaqueValueExpr *OpaqueValue;
+  bool IsInvalid;
 };
 
 static ExprResult buildMemberCall(Sema &S, Expr *Base, SourceLocation Loc,
-                                  StringRef Name,
-                                  MutableArrayRef<Expr *> Args) {
+                                  StringRef Name, MultiExprArg Args) {
   DeclarationNameInfo NameInfo(&S.PP.getIdentifierTable().get(Name), Loc);
 
   // FIXME: Fix BuildMemberReferenceExpr to take a const CXXScopeSpec&.
@@ -247,18 +337,23 @@ static ExprResult buildMemberCall(Sema &S, Expr *Base, SourceLocation Loc,
 
 /// Build calls to await_ready, await_suspend, and await_resume for a co_await
 /// expression.
-static ReadySuspendResumeResult buildCoawaitCalls(Sema &S, SourceLocation Loc,
-                                                  Expr *E) {
+static ReadySuspendResumeResult buildCoawaitCalls(Sema &S, VarDecl *CoroPromise,
+                                                  SourceLocation Loc, Expr *E) {
+  OpaqueValueExpr *Operand = new (S.Context)
+      OpaqueValueExpr(Loc, E->getType(), VK_LValue, E->getObjectKind(), E);
+
   // Assume invalid until we see otherwise.
-  ReadySuspendResumeResult Calls = {true, {}};
+  ReadySuspendResumeResult Calls = {{}, Operand, /*IsInvalid=*/true};
+
+  ExprResult CoroHandleRes = buildCoroutineHandle(S, CoroPromise->getType(), Loc);
+  if (CoroHandleRes.isInvalid())
+    return Calls;
+  Expr *CoroHandle = CoroHandleRes.get();
 
   const StringRef Funcs[] = {"await_ready", "await_suspend", "await_resume"};
+  MultiExprArg Args[] = {None, CoroHandle, None};
   for (size_t I = 0, N = llvm::array_lengthof(Funcs); I != N; ++I) {
-    Expr *Operand = new (S.Context) OpaqueValueExpr(
-      Loc, E->getType(), VK_LValue, E->getObjectKind(), E);
-
-    // FIXME: Pass coroutine handle to await_suspend.
-    ExprResult Result = buildMemberCall(S, Operand, Loc, Funcs[I], None);
+    ExprResult Result = buildMemberCall(S, Operand, Loc, Funcs[I], Args[I]);
     if (Result.isInvalid())
       return Calls;
     Calls.Results[I] = Result.get();
@@ -268,26 +363,177 @@ static ReadySuspendResumeResult buildCoawaitCalls(Sema &S, SourceLocation Loc,
   return Calls;
 }
 
+static ExprResult buildPromiseCall(Sema &S, VarDecl *Promise,
+                                   SourceLocation Loc, StringRef Name,
+                                   MultiExprArg Args) {
+
+  // Form a reference to the promise.
+  ExprResult PromiseRef = S.BuildDeclRefExpr(
+      Promise, Promise->getType().getNonReferenceType(), VK_LValue, Loc);
+  if (PromiseRef.isInvalid())
+    return ExprError();
+
+  // Call 'yield_value', passing in E.
+  return buildMemberCall(S, PromiseRef.get(), Loc, Name, Args);
+}
+
+VarDecl *Sema::buildCoroutinePromise(SourceLocation Loc) {
+  assert(isa<FunctionDecl>(CurContext) && "not in a function scope");
+  auto *FD = cast<FunctionDecl>(CurContext);
+
+  QualType T =
+      FD->getType()->isDependentType()
+          ? Context.DependentTy
+          : lookupPromiseType(*this, FD->getType()->castAs<FunctionProtoType>(),
+                              Loc, FD->getLocation());
+  if (T.isNull())
+    return nullptr;
+
+  auto *VD = VarDecl::Create(Context, FD, FD->getLocation(), FD->getLocation(),
+                             &PP.getIdentifierTable().get("__promise"), T,
+                             Context.getTrivialTypeSourceInfo(T, Loc), SC_None);
+  CheckVariableDeclarationType(VD);
+  if (VD->isInvalidDecl())
+    return nullptr;
+  ActOnUninitializedDecl(VD);
+  assert(!VD->isInvalidDecl());
+  return VD;
+}
+
+/// Check that this is a context in which a coroutine suspension can appear.
+static FunctionScopeInfo *checkCoroutineContext(Sema &S, SourceLocation Loc,
+                                                StringRef Keyword,
+                                                bool IsImplicit = false) {
+  if (!isValidCoroutineContext(S, Loc, Keyword))
+    return nullptr;
+
+  assert(isa<FunctionDecl>(S.CurContext) && "not in a function scope");
+
+  auto *ScopeInfo = S.getCurFunction();
+  assert(ScopeInfo && "missing function scope for function");
+
+  if (ScopeInfo->FirstCoroutineStmtLoc.isInvalid() && !IsImplicit)
+    ScopeInfo->setFirstCoroutineStmt(Loc, Keyword);
+
+  if (ScopeInfo->CoroutinePromise)
+    return ScopeInfo;
+
+  ScopeInfo->CoroutinePromise = S.buildCoroutinePromise(Loc);
+  if (!ScopeInfo->CoroutinePromise)
+    return nullptr;
+
+  return ScopeInfo;
+}
+
+static bool actOnCoroutineBodyStart(Sema &S, Scope *SC, SourceLocation KWLoc,
+                                    StringRef Keyword) {
+  if (!checkCoroutineContext(S, KWLoc, Keyword))
+    return false;
+  auto *ScopeInfo = S.getCurFunction();
+  assert(ScopeInfo->CoroutinePromise);
+
+  // If we have existing coroutine statements then we have already built
+  // the initial and final suspend points.
+  if (!ScopeInfo->NeedsCoroutineSuspends)
+    return true;
+
+  ScopeInfo->setNeedsCoroutineSuspends(false);
+
+  auto *Fn = cast<FunctionDecl>(S.CurContext);
+  SourceLocation Loc = Fn->getLocation();
+  // Build the initial suspend point
+  auto buildSuspends = [&](StringRef Name) mutable -> StmtResult {
+    ExprResult Suspend =
+        buildPromiseCall(S, ScopeInfo->CoroutinePromise, Loc, Name, None);
+    if (Suspend.isInvalid())
+      return StmtError();
+    Suspend = buildOperatorCoawaitCall(S, SC, Loc, Suspend.get());
+    if (Suspend.isInvalid())
+      return StmtError();
+    Suspend = S.BuildResolvedCoawaitExpr(Loc, Suspend.get(),
+                                         /*IsImplicit*/ true);
+    Suspend = S.ActOnFinishFullExpr(Suspend.get());
+    if (Suspend.isInvalid()) {
+      S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
+          << ((Name == "initial_suspend") ? 0 : 1);
+      S.Diag(KWLoc, diag::note_declared_coroutine_here) << Keyword;
+      return StmtError();
+    }
+    return cast<Stmt>(Suspend.get());
+  };
+
+  StmtResult InitSuspend = buildSuspends("initial_suspend");
+  if (InitSuspend.isInvalid())
+    return true;
+
+  StmtResult FinalSuspend = buildSuspends("final_suspend");
+  if (FinalSuspend.isInvalid())
+    return true;
+
+  ScopeInfo->setCoroutineSuspends(InitSuspend.get(), FinalSuspend.get());
+
+  return true;
+}
+
 ExprResult Sema::ActOnCoawaitExpr(Scope *S, SourceLocation Loc, Expr *E) {
-  auto *Coroutine = checkCoroutineContext(*this, Loc, "co_await");
-  if (!Coroutine) {
+  if (!actOnCoroutineBodyStart(*this, S, Loc, "co_await")) {
     CorrectDelayedTyposInExpr(E);
     return ExprError();
   }
+
   if (E->getType()->isPlaceholderType()) {
     ExprResult R = CheckPlaceholderExpr(E);
     if (R.isInvalid()) return ExprError();
     E = R.get();
   }
+  ExprResult Lookup = buildOperatorCoawaitLookupExpr(*this, S, Loc);
+  if (Lookup.isInvalid())
+    return ExprError();
+  return BuildUnresolvedCoawaitExpr(Loc, E,
+                                   cast<UnresolvedLookupExpr>(Lookup.get()));
+}
+
+ExprResult Sema::BuildUnresolvedCoawaitExpr(SourceLocation Loc, Expr *E,
+                                            UnresolvedLookupExpr *Lookup) {
+  auto *FSI = checkCoroutineContext(*this, Loc, "co_await");
+  if (!FSI)
+    return ExprError();
 
-  ExprResult Awaitable = buildOperatorCoawaitCall(*this, S, Loc, E);
+  if (E->getType()->isPlaceholderType()) {
+    ExprResult R = CheckPlaceholderExpr(E);
+    if (R.isInvalid())
+      return ExprError();
+    E = R.get();
+  }
+
+  auto *Promise = FSI->CoroutinePromise;
+  if (Promise->getType()->isDependentType()) {
+    Expr *Res =
+        new (Context) DependentCoawaitExpr(Loc, Context.DependentTy, E, Lookup);
+    return Res;
+  }
+
+  auto *RD = Promise->getType()->getAsCXXRecordDecl();
+  if (lookupMember(*this, "await_transform", RD, Loc)) {
+    ExprResult R = buildPromiseCall(*this, Promise, Loc, "await_transform", E);
+    if (R.isInvalid()) {
+      Diag(Loc,
+           diag::note_coroutine_promise_implicit_await_transform_required_here)
+          << E->getSourceRange();
+      return ExprError();
+    }
+    E = R.get();
+  }
+  ExprResult Awaitable = buildOperatorCoawaitCall(*this, Loc, E, Lookup);
   if (Awaitable.isInvalid())
     return ExprError();
 
-  return BuildCoawaitExpr(Loc, Awaitable.get());
+  return BuildResolvedCoawaitExpr(Loc, Awaitable.get());
 }
-ExprResult Sema::BuildCoawaitExpr(SourceLocation Loc, Expr *E) {
-  auto *Coroutine = checkCoroutineContext(*this, Loc, "co_await");
+
+ExprResult Sema::BuildResolvedCoawaitExpr(SourceLocation Loc, Expr *E,
+                                  bool IsImplicit) {
+  auto *Coroutine = checkCoroutineContext(*this, Loc, "co_await", IsImplicit);
   if (!Coroutine)
     return ExprError();
 
@@ -298,8 +544,8 @@ ExprResult Sema::BuildCoawaitExpr(SourceLocation Loc, Expr *E) {
   }
 
   if (E->getType()->isDependentType()) {
-    Expr *Res = new (Context) CoawaitExpr(Loc, Context.DependentTy, E);
-    Coroutine->CoroutineStmts.push_back(Res);
+    Expr *Res = new (Context)
+        CoawaitExpr(Loc, Context.DependentTy, E, IsImplicit);
     return Res;
   }
 
@@ -309,42 +555,27 @@ ExprResult Sema::BuildCoawaitExpr(SourceLocation Loc, Expr *E) {
     E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
 
   // Build the await_ready, await_suspend, await_resume calls.
-  ReadySuspendResumeResult RSS = buildCoawaitCalls(*this, Loc, E);
+  ReadySuspendResumeResult RSS =
+      buildCoawaitCalls(*this, Coroutine->CoroutinePromise, Loc, E);
   if (RSS.IsInvalid)
     return ExprError();
 
-  Expr *Res = new (Context) CoawaitExpr(Loc, E, RSS.Results[0], RSS.Results[1],
-                                        RSS.Results[2]);
-  Coroutine->CoroutineStmts.push_back(Res);
-  return Res;
-}
-
-static ExprResult buildPromiseCall(Sema &S, FunctionScopeInfo *Coroutine,
-                                   SourceLocation Loc, StringRef Name,
-                                   MutableArrayRef<Expr *> Args) {
-  assert(Coroutine->CoroutinePromise && "no promise for coroutine");
-
-  // Form a reference to the promise.
-  auto *Promise = Coroutine->CoroutinePromise;
-  ExprResult PromiseRef = S.BuildDeclRefExpr(
-      Promise, Promise->getType().getNonReferenceType(), VK_LValue, Loc);
-  if (PromiseRef.isInvalid())
-    return ExprError();
+  Expr *Res =
+      new (Context) CoawaitExpr(Loc, E, RSS.Results[0], RSS.Results[1],
+                                RSS.Results[2], RSS.OpaqueValue, IsImplicit);
 
-  // Call 'yield_value', passing in E.
-  return buildMemberCall(S, PromiseRef.get(), Loc, Name, Args);
+  return Res;
 }
 
 ExprResult Sema::ActOnCoyieldExpr(Scope *S, SourceLocation Loc, Expr *E) {
-  auto *Coroutine = checkCoroutineContext(*this, Loc, "co_yield");
-  if (!Coroutine) {
+  if (!actOnCoroutineBodyStart(*this, S, Loc, "co_yield")) {
     CorrectDelayedTyposInExpr(E);
     return ExprError();
   }
 
   // Build yield_value call.
-  ExprResult Awaitable =
-      buildPromiseCall(*this, Coroutine, Loc, "yield_value", E);
+  ExprResult Awaitable = buildPromiseCall(
+      *this, getCurFunction()->CoroutinePromise, Loc, "yield_value", E);
   if (Awaitable.isInvalid())
     return ExprError();
 
@@ -368,7 +599,6 @@ ExprResult Sema::BuildCoyieldExpr(SourceLocation Loc, Expr *E) {
 
   if (E->getType()->isDependentType()) {
     Expr *Res = new (Context) CoyieldExpr(Loc, Context.DependentTy, E);
-    Coroutine->CoroutineStmts.push_back(Res);
     return Res;
   }
 
@@ -378,28 +608,29 @@ ExprResult Sema::BuildCoyieldExpr(SourceLocation Loc, Expr *E) {
     E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
 
   // Build the await_ready, await_suspend, await_resume calls.
-  ReadySuspendResumeResult RSS = buildCoawaitCalls(*this, Loc, E);
+  ReadySuspendResumeResult RSS =
+      buildCoawaitCalls(*this, Coroutine->CoroutinePromise, Loc, E);
   if (RSS.IsInvalid)
     return ExprError();
 
   Expr *Res = new (Context) CoyieldExpr(Loc, E, RSS.Results[0], RSS.Results[1],
-                                        RSS.Results[2]);
-  Coroutine->CoroutineStmts.push_back(Res);
+                                        RSS.Results[2], RSS.OpaqueValue);
+
   return Res;
 }
 
-StmtResult Sema::ActOnCoreturnStmt(SourceLocation Loc, Expr *E) {
-  auto *Coroutine = checkCoroutineContext(*this, Loc, "co_return");
-  if (!Coroutine) {
+StmtResult Sema::ActOnCoreturnStmt(Scope *S, SourceLocation Loc, Expr *E) {
+  if (!actOnCoroutineBodyStart(*this, S, Loc, "co_return")) {
     CorrectDelayedTyposInExpr(E);
     return StmtError();
   }
   return BuildCoreturnStmt(Loc, E);
 }
 
-StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E) {
-  auto *Coroutine = checkCoroutineContext(*this, Loc, "co_return");
-  if (!Coroutine)
+StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E,
+                                   bool IsImplicit) {
+  auto *FSI = checkCoroutineContext(*this, Loc, "co_return", IsImplicit);
+  if (!FSI)
     return StmtError();
 
   if (E && E->getType()->isPlaceholderType() &&
@@ -412,48 +643,20 @@ StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E) {
   // FIXME: If the operand is a reference to a variable that's about to go out
   // of scope, we should treat the operand as an xvalue for this overload
   // resolution.
+  VarDecl *Promise = FSI->CoroutinePromise;
   ExprResult PC;
   if (E && (isa<InitListExpr>(E) || !E->getType()->isVoidType())) {
-    PC = buildPromiseCall(*this, Coroutine, Loc, "return_value", E);
+    PC = buildPromiseCall(*this, Promise, Loc, "return_value", E);
   } else {
     E = MakeFullDiscardedValueExpr(E).get();
-    PC = buildPromiseCall(*this, Coroutine, Loc, "return_void", None);
+    PC = buildPromiseCall(*this, Promise, Loc, "return_void", None);
   }
   if (PC.isInvalid())
     return StmtError();
 
   Expr *PCE = ActOnFinishFullExpr(PC.get()).get();
 
-  Stmt *Res = new (Context) CoreturnStmt(Loc, E, PCE);
-  Coroutine->CoroutineStmts.push_back(Res);
-  return Res;
-}
-
-static ExprResult buildStdCurrentExceptionCall(Sema &S, SourceLocation Loc) {
-  NamespaceDecl *Std = S.getStdNamespace();
-  if (!Std) {
-    S.Diag(Loc, diag::err_implied_std_current_exception_not_found);
-    return ExprError();
-  }
-  LookupResult Result(S, &S.PP.getIdentifierTable().get("current_exception"),
-                      Loc, Sema::LookupOrdinaryName);
-  if (!S.LookupQualifiedName(Result, Std)) {
-    S.Diag(Loc, diag::err_implied_std_current_exception_not_found);
-    return ExprError();
-  }
-
-  // FIXME The STL is free to provide more than one overload.
-  FunctionDecl *FD = Result.getAsSingle<FunctionDecl>();
-  if (!FD) {
-    S.Diag(Loc, diag::err_malformed_std_current_exception);
-    return ExprError();
-  }
-  ExprResult Res = S.BuildDeclRefExpr(FD, FD->getType(), VK_LValue, Loc);
-  Res = S.ActOnCallExpr(/*Scope*/ nullptr, Res.get(), Loc, None, Loc);
-  if (Res.isInvalid()) {
-    S.Diag(Loc, diag::err_malformed_std_current_exception);
-    return ExprError();
-  }
+  Stmt *Res = new (Context) CoreturnStmt(Loc, E, PCE, IsImplicit);
   return Res;
 }
 
@@ -482,21 +685,170 @@ static FunctionDecl *findDeleteForPromise(Sema &S, SourceLocation Loc,
   return OperatorDelete;
 }
 
-// Builds allocation and deallocation for the coroutine. Returns false on
-// failure.
-static bool buildAllocationAndDeallocation(Sema &S, SourceLocation Loc,
-                                           FunctionScopeInfo *Fn,
-                                           Expr *&Allocation,
-                                           Stmt *&Deallocation) {
-  TypeSourceInfo *TInfo = Fn->CoroutinePromise->getTypeSourceInfo();
-  QualType PromiseType = TInfo->getType();
-  if (PromiseType->isDependentType())
+
+void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body) {
+  FunctionScopeInfo *Fn = getCurFunction();
+  assert(Fn && Fn->CoroutinePromise && "not a coroutine");
+
+  if (!Body) {
+    assert(FD->isInvalidDecl() &&
+           "a null body is only allowed for invalid declarations");
+    return;
+  }
+
+  if (isa<CoroutineBodyStmt>(Body)) {
+    // FIXME(EricWF): Nothing todo. the body is already a transformed coroutine
+    // body statement.
+    return;
+  }
+
+  // Coroutines [stmt.return]p1:
+  //   A return statement shall not appear in a coroutine.
+  if (Fn->FirstReturnLoc.isValid()) {
+    assert(Fn->FirstCoroutineStmtLoc.isValid() &&
+                   "first coroutine location not set");
+    Diag(Fn->FirstReturnLoc, diag::err_return_in_coroutine);
+    Diag(Fn->FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
+            << Fn->getFirstCoroutineStmtKeyword();
+  }
+  CoroutineStmtBuilder Builder(*this, *FD, *Fn, Body);
+  if (Builder.isInvalid() || !Builder.buildStatements())
+    return FD->setInvalidDecl();
+
+  // Build body for the coroutine wrapper statement.
+  Body = CoroutineBodyStmt::Create(Context, Builder);
+}
+
+CoroutineStmtBuilder::CoroutineStmtBuilder(Sema &S, FunctionDecl &FD,
+                                           sema::FunctionScopeInfo &Fn,
+                                           Stmt *Body)
+    : S(S), FD(FD), Fn(Fn), Loc(FD.getLocation()),
+      IsPromiseDependentType(
+          !Fn.CoroutinePromise ||
+          Fn.CoroutinePromise->getType()->isDependentType()) {
+  this->Body = Body;
+  if (!IsPromiseDependentType) {
+    PromiseRecordDecl = Fn.CoroutinePromise->getType()->getAsCXXRecordDecl();
+    assert(PromiseRecordDecl && "Type should have already been checked");
+  }
+  this->IsValid = makePromiseStmt() && makeInitialAndFinalSuspend();
+}
+
+bool CoroutineStmtBuilder::buildStatements() {
+  assert(this->IsValid && "coroutine already invalid");
+  this->IsValid = makeReturnObject() && makeParamMoves();
+  if (this->IsValid && !IsPromiseDependentType)
+    buildDependentStatements();
+  return this->IsValid;
+}
+
+bool CoroutineStmtBuilder::buildDependentStatements() {
+  assert(this->IsValid && "coroutine already invalid");
+  assert(!this->IsPromiseDependentType &&
+         "coroutine cannot have a dependent promise type");
+  this->IsValid = makeOnException() && makeOnFallthrough() &&
+                  makeReturnOnAllocFailure() && makeNewAndDeleteExpr();
+  return this->IsValid;
+}
+
+bool CoroutineStmtBuilder::makePromiseStmt() {
+  // Form a declaration statement for the promise declaration, so that AST
+  // visitors can more easily find it.
+  StmtResult PromiseStmt =
+      S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(Fn.CoroutinePromise), Loc, Loc);
+  if (PromiseStmt.isInvalid())
+    return false;
+
+  this->Promise = PromiseStmt.get();
+  return true;
+}
+
+bool CoroutineStmtBuilder::makeInitialAndFinalSuspend() {
+  if (Fn.hasInvalidCoroutineSuspends())
+    return false;
+  this->InitialSuspend = cast<Expr>(Fn.CoroutineSuspends.first);
+  this->FinalSuspend = cast<Expr>(Fn.CoroutineSuspends.second);
+  return true;
+}
+
+static bool diagReturnOnAllocFailure(Sema &S, Expr *E,
+                                     CXXRecordDecl *PromiseRecordDecl,
+                                     FunctionScopeInfo &Fn) {
+  auto Loc = E->getExprLoc();
+  if (auto *DeclRef = dyn_cast_or_null<DeclRefExpr>(E)) {
+    auto *Decl = DeclRef->getDecl();
+    if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(Decl)) {
+      if (Method->isStatic())
+        return true;
+      else
+        Loc = Decl->getLocation();
+    }
+  }
+
+  S.Diag(
+      Loc,
+      diag::err_coroutine_promise_get_return_object_on_allocation_failure)
+      << PromiseRecordDecl;
+  S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
+      << Fn.getFirstCoroutineStmtKeyword();
+  return false;
+}
+
+bool CoroutineStmtBuilder::makeReturnOnAllocFailure() {
+  assert(!IsPromiseDependentType &&
+         "cannot make statement while the promise type is dependent");
+
+  // [dcl.fct.def.coroutine]/8
+  // The unqualified-id get_return_object_on_allocation_failure is looked up in
+  // the scope of class P by class member access lookup (3.4.5). ...
+  // If an allocation function returns nullptr, ... the coroutine return value
+  // is obtained by a call to ... get_return_object_on_allocation_failure().
+
+  DeclarationName DN =
+      S.PP.getIdentifierInfo("get_return_object_on_allocation_failure");
+  LookupResult Found(S, DN, Loc, Sema::LookupMemberName);
+  if (!S.LookupQualifiedName(Found, PromiseRecordDecl))
     return true;
 
+  CXXScopeSpec SS;
+  ExprResult DeclNameExpr =
+      S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
+  if (DeclNameExpr.isInvalid())
+    return false;
+
+  if (!diagReturnOnAllocFailure(S, DeclNameExpr.get(), PromiseRecordDecl, Fn))
+    return false;
+
+  ExprResult ReturnObjectOnAllocationFailure =
+      S.ActOnCallExpr(nullptr, DeclNameExpr.get(), Loc, {}, Loc);
+  if (ReturnObjectOnAllocationFailure.isInvalid())
+    return false;
+
+  // FIXME: ActOnReturnStmt expects a scope that is inside of the function, due
+  //   to CheckJumpOutOfSEHFinally(*this, ReturnLoc, *CurScope->getFnParent());
+  //   S.getCurScope()->getFnParent() == nullptr at ActOnFinishFunctionBody when
+  //   CoroutineBodyStmt is built. Figure it out and fix it.
+  //   Use BuildReturnStmt here to unbreak sanitized tests. (Gor:3/27/2017)
+  StmtResult ReturnStmt =
+      S.BuildReturnStmt(Loc, ReturnObjectOnAllocationFailure.get());
+  if (ReturnStmt.isInvalid())
+    return false;
+
+  this->ReturnStmtOnAllocFailure = ReturnStmt.get();
+  return true;
+}
+
+bool CoroutineStmtBuilder::makeNewAndDeleteExpr() {
+  // Form and check allocation and deallocation calls.
+  assert(!IsPromiseDependentType &&
+         "cannot make statement while the promise type is dependent");
+  QualType PromiseType = Fn.CoroutinePromise->getType();
+
   if (S.RequireCompleteType(Loc, PromiseType, diag::err_incomplete_type))
     return false;
 
-  // FIXME: Add support for get_return_object_on_allocation failure.
+  // FIXME: Add nothrow_t placement arg for global alloc
+  //        if ReturnStmtOnAllocFailure != nullptr.
   // FIXME: Add support for stateful allocators.
 
   FunctionDecl *OperatorNew = nullptr;
@@ -532,8 +884,6 @@ static bool buildAllocationAndDeallocation(Sema &S, SourceLocation Loc,
   if (NewExpr.isInvalid())
     return false;
 
-  Allocation = NewExpr.get();
-
   // Make delete call.
 
   QualType OpDeleteQualType = OperatorDelete->getType();
@@ -559,138 +909,107 @@ static bool buildAllocationAndDeallocation(Sema &S, SourceLocation Loc,
   if (DeleteExpr.isInvalid())
     return false;
 
-  Deallocation = DeleteExpr.get();
+  this->Allocate = NewExpr.get();
+  this->Deallocate = DeleteExpr.get();
 
   return true;
 }
 
-void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body) {
-  FunctionScopeInfo *Fn = getCurFunction();
-  assert(Fn && !Fn->CoroutineStmts.empty() && "not a coroutine");
+bool CoroutineStmtBuilder::makeOnFallthrough() {
+  assert(!IsPromiseDependentType &&
+         "cannot make statement while the promise type is dependent");
 
-  // Coroutines [stmt.return]p1:
-  //   A return statement shall not appear in a coroutine.
-  if (Fn->FirstReturnLoc.isValid()) {
-    Diag(Fn->FirstReturnLoc, diag::err_return_in_coroutine);
-    auto *First = Fn->CoroutineStmts[0];
-    Diag(First->getLocStart(), diag::note_declared_coroutine_here)
-        << (isa<CoawaitExpr>(First) ? 0 :
-            isa<CoyieldExpr>(First) ? 1 : 2);
-  }
+  // [dcl.fct.def.coroutine]/4
+  // The unqualified-ids 'return_void' and 'return_value' are looked up in
+  // the scope of class P. If both are found, the program is ill-formed.
+  const bool HasRVoid = lookupMember(S, "return_void", PromiseRecordDecl, Loc);
+  const bool HasRValue = lookupMember(S, "return_value", PromiseRecordDecl, Loc);
 
-  SourceLocation Loc = FD->getLocation();
+  StmtResult Fallthrough;
+  if (HasRVoid && HasRValue) {
+    // FIXME Improve this diagnostic
+    S.Diag(FD.getLocation(), diag::err_coroutine_promise_return_ill_formed)
+        << PromiseRecordDecl;
+    return false;
+  } else if (HasRVoid) {
+    // If the unqualified-id return_void is found, flowing off the end of a
+    // coroutine is equivalent to a co_return with no operand. Otherwise,
+    // flowing off the end of a coroutine results in undefined behavior.
+    Fallthrough = S.BuildCoreturnStmt(FD.getLocation(), nullptr,
+                                      /*IsImplicit*/false);
+    Fallthrough = S.ActOnFinishFullStmt(Fallthrough.get());
+    if (Fallthrough.isInvalid())
+      return false;
+  }
 
-  // Form a declaration statement for the promise declaration, so that AST
-  // visitors can more easily find it.
-  StmtResult PromiseStmt =
-      ActOnDeclStmt(ConvertDeclToDeclGroup(Fn->CoroutinePromise), Loc, Loc);
-  if (PromiseStmt.isInvalid())
-    return FD->setInvalidDecl();
+  this->OnFallthrough = Fallthrough.get();
+  return true;
+}
 
-  // Form and check implicit 'co_await p.initial_suspend();' statement.
-  ExprResult InitialSuspend =
-      buildPromiseCall(*this, Fn, Loc, "initial_suspend", None);
-  // FIXME: Support operator co_await here.
-  if (!InitialSuspend.isInvalid())
-    InitialSuspend = BuildCoawaitExpr(Loc, InitialSuspend.get());
-  InitialSuspend = ActOnFinishFullExpr(InitialSuspend.get());
-  if (InitialSuspend.isInvalid())
-    return FD->setInvalidDecl();
+bool CoroutineStmtBuilder::makeOnException() {
+  // Try to form 'p.unhandled_exception();'
+  assert(!IsPromiseDependentType &&
+         "cannot make statement while the promise type is dependent");
+
+  const bool RequireUnhandledException = S.getLangOpts().CXXExceptions;
+
+  if (!lookupMember(S, "unhandled_exception", PromiseRecordDecl, Loc)) {
+    auto DiagID =
+        RequireUnhandledException
+            ? diag::err_coroutine_promise_unhandled_exception_required
+            : diag::
+                  warn_coroutine_promise_unhandled_exception_required_with_exceptions;
+    S.Diag(Loc, DiagID) << PromiseRecordDecl;
+    return !RequireUnhandledException;
+  }
 
-  // Form and check implicit 'co_await p.final_suspend();' statement.
-  ExprResult FinalSuspend =
-      buildPromiseCall(*this, Fn, Loc, "final_suspend", None);
-  // FIXME: Support operator co_await here.
-  if (!FinalSuspend.isInvalid())
-    FinalSuspend = BuildCoawaitExpr(Loc, FinalSuspend.get());
-  FinalSuspend = ActOnFinishFullExpr(FinalSuspend.get());
-  if (FinalSuspend.isInvalid())
-    return FD->setInvalidDecl();
+  // If exceptions are disabled, don't try to build OnException.
+  if (!S.getLangOpts().CXXExceptions)
+    return true;
 
-  // Form and check allocation and deallocation calls.
-  Expr *Allocation = nullptr;
-  Stmt *Deallocation = nullptr;
-  if (!buildAllocationAndDeallocation(*this, Loc, Fn, Allocation, Deallocation))
-    return FD->setInvalidDecl();
+  ExprResult UnhandledException = buildPromiseCall(S, Fn.CoroutinePromise, Loc,
+                                                   "unhandled_exception", None);
+  UnhandledException = S.ActOnFinishFullExpr(UnhandledException.get(), Loc);
+  if (UnhandledException.isInvalid())
+    return false;
 
-  // control flowing off the end of the coroutine.
-  // Also try to form 'p.set_exception(std::current_exception());' to handle
-  // uncaught exceptions.
-  ExprResult SetException;
-  StmtResult Fallthrough;
-  if (Fn->CoroutinePromise &&
-      !Fn->CoroutinePromise->getType()->isDependentType()) {
-    CXXRecordDecl *RD = Fn->CoroutinePromise->getType()->getAsCXXRecordDecl();
-    assert(RD && "Type should have already been checked");
-    // [dcl.fct.def.coroutine]/4
-    // The unqualified-ids 'return_void' and 'return_value' are looked up in
-    // the scope of class P. If both are found, the program is ill-formed.
-    DeclarationName RVoidDN = PP.getIdentifierInfo("return_void");
-    LookupResult RVoidResult(*this, RVoidDN, Loc, Sema::LookupMemberName);
-    const bool HasRVoid = LookupQualifiedName(RVoidResult, RD);
-
-    DeclarationName RValueDN = PP.getIdentifierInfo("return_value");
-    LookupResult RValueResult(*this, RValueDN, Loc, Sema::LookupMemberName);
-    const bool HasRValue = LookupQualifiedName(RValueResult, RD);
-
-    if (HasRVoid && HasRValue) {
-      // FIXME Improve this diagnostic
-      Diag(FD->getLocation(), diag::err_coroutine_promise_return_ill_formed)
-          << RD;
-      return FD->setInvalidDecl();
-    } else if (HasRVoid) {
-      // If the unqualified-id return_void is found, flowing off the end of a
-      // coroutine is equivalent to a co_return with no operand. Otherwise,
-      // flowing off the end of a coroutine results in undefined behavior.
-      Fallthrough = BuildCoreturnStmt(FD->getLocation(), nullptr);
-      Fallthrough = ActOnFinishFullStmt(Fallthrough.get());
-      if (Fallthrough.isInvalid())
-        return FD->setInvalidDecl();
-    }
+  this->OnException = UnhandledException.get();
+  return true;
+}
 
-    // [dcl.fct.def.coroutine]/3
-    // The unqualified-id set_exception is found in the scope of P by class
-    // member access lookup (3.4.5).
-    DeclarationName SetExDN = PP.getIdentifierInfo("set_exception");
-    LookupResult SetExResult(*this, SetExDN, Loc, Sema::LookupMemberName);
-    if (LookupQualifiedName(SetExResult, RD)) {
-      // Form the call 'p.set_exception(std::current_exception())'
-      SetException = buildStdCurrentExceptionCall(*this, Loc);
-      if (SetException.isInvalid())
-        return FD->setInvalidDecl();
-      Expr *E = SetException.get();
-      SetException = buildPromiseCall(*this, Fn, Loc, "set_exception", E);
-      SetException = ActOnFinishFullExpr(SetException.get(), Loc);
-      if (SetException.isInvalid())
-        return FD->setInvalidDecl();
-    }
-  }
+bool CoroutineStmtBuilder::makeReturnObject() {
 
   // Build implicit 'p.get_return_object()' expression and form initialization
   // of return type from it.
   ExprResult ReturnObject =
-      buildPromiseCall(*this, Fn, Loc, "get_return_object", None);
+      buildPromiseCall(S, Fn.CoroutinePromise, Loc, "get_return_object", None);
   if (ReturnObject.isInvalid())
-    return FD->setInvalidDecl();
-  QualType RetType = FD->getReturnType();
+    return false;
+  QualType RetType = FD.getReturnType();
   if (!RetType->isDependentType()) {
     InitializedEntity Entity =
         InitializedEntity::InitializeResult(Loc, RetType, false);
-    ReturnObject = PerformMoveOrCopyInitialization(Entity, nullptr, RetType,
+    ReturnObject = S.PerformMoveOrCopyInitialization(Entity, nullptr, RetType,
                                                    ReturnObject.get());
     if (ReturnObject.isInvalid())
-      return FD->setInvalidDecl();
+      return false;
   }
-  ReturnObject = ActOnFinishFullExpr(ReturnObject.get(), Loc);
+  ReturnObject = S.ActOnFinishFullExpr(ReturnObject.get(), Loc);
   if (ReturnObject.isInvalid())
-    return FD->setInvalidDecl();
+    return false;
 
+  this->ReturnValue = ReturnObject.get();
+  return true;
+}
+
+bool CoroutineStmtBuilder::makeParamMoves() {
   // FIXME: Perform move-initialization of parameters into frame-local copies.
-  SmallVector<Expr*, 16> ParamMoves;
+  return true;
+}
 
-  // Build body for the coroutine wrapper statement.
-  Body = new (Context) CoroutineBodyStmt(
-      Body, PromiseStmt.get(), InitialSuspend.get(), FinalSuspend.get(),
-      SetException.get(), Fallthrough.get(), Allocation, Deallocation,
-      ReturnObject.get(), ParamMoves);
+StmtResult Sema::BuildCoroutineBodyStmt(CoroutineBodyStmt::CtorArgs Args) {
+  CoroutineBodyStmt *Res = CoroutineBodyStmt::Create(Context, Args);
+  if (!Res)
+    return StmtError();
+  return Res;
 }
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index adcf2ee00e75..c6a0b0101d37 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -67,7 +67,7 @@ class TypeNameValidatorCCC : public CorrectionCandidateCallback {
   TypeNameValidatorCCC(bool AllowInvalid, bool WantClass=false,
                        bool AllowTemplates=false)
       : AllowInvalidDecl(AllowInvalid), WantClassName(WantClass),
-        AllowClassTemplates(AllowTemplates) {
+        AllowTemplates(AllowTemplates) {
     WantExpressionKeywords = false;
     WantCXXNamedCasts = false;
     WantRemainingKeywords = false;
@@ -76,7 +76,7 @@ class TypeNameValidatorCCC : public CorrectionCandidateCallback {
   bool ValidateCandidate(const TypoCorrection &candidate) override {
     if (NamedDecl *ND = candidate.getCorrectionDecl()) {
       bool IsType = isa<TypeDecl>(ND) || isa<ObjCInterfaceDecl>(ND);
-      bool AllowedTemplate = AllowClassTemplates && isa<ClassTemplateDecl>(ND);
+      bool AllowedTemplate = AllowTemplates && getAsTypeTemplateDecl(ND);
       return (IsType || AllowedTemplate) &&
              (AllowInvalidDecl || !ND->isInvalidDecl());
     }
@@ -86,7 +86,7 @@ class TypeNameValidatorCCC : public CorrectionCandidateCallback {
  private:
   bool AllowInvalidDecl;
   bool WantClassName;
-  bool AllowClassTemplates;
+  bool AllowTemplates;
 };
 
 } // end anonymous namespace
@@ -252,7 +252,13 @@ ParsedType Sema::getTypeName(const IdentifierInfo &II, SourceLocation NameLoc,
                              ParsedType ObjectTypePtr,
                              bool IsCtorOrDtorName,
                              bool WantNontrivialTypeSourceInfo,
+                             bool IsClassTemplateDeductionContext,
                              IdentifierInfo **CorrectedII) {
+  // FIXME: Consider allowing this outside C++1z mode as an extension.
+  bool AllowDeducedTemplate = IsClassTemplateDeductionContext &&
+                              getLangOpts().CPlusPlus1z && !IsCtorOrDtorName &&
+                              !isClassName && !HasTrailingDot;
+
   // Determine where we will perform name lookup.
   DeclContext *LookupCtx = nullptr;
   if (ObjectTypePtr) {
@@ -334,10 +340,11 @@ ParsedType Sema::getTypeName(const IdentifierInfo &II, SourceLocation NameLoc,
   case LookupResult::NotFound:
   case LookupResult::NotFoundInCurrentInstantiation:
     if (CorrectedII) {
-      TypoCorrection Correction = CorrectTypo(
-          Result.getLookupNameInfo(), Kind, S, SS,
-          llvm::make_unique<TypeNameValidatorCCC>(true, isClassName),
-          CTK_ErrorRecovery);
+      TypoCorrection Correction =
+          CorrectTypo(Result.getLookupNameInfo(), Kind, S, SS,
+                      llvm::make_unique<TypeNameValidatorCCC>(
+                          true, isClassName, AllowDeducedTemplate),
+                      CTK_ErrorRecovery);
       IdentifierInfo *NewII = Correction.getCorrectionAsIdentifierInfo();
       TemplateTy Template;
       bool MemberOfUnknownSpecialization;
@@ -359,7 +366,8 @@ ParsedType Sema::getTypeName(const IdentifierInfo &II, SourceLocation NameLoc,
         ParsedType Ty = getTypeName(*NewII, NameLoc, S, NewSSPtr,
                                     isClassName, HasTrailingDot, ObjectTypePtr,
                                     IsCtorOrDtorName,
-                                    WantNontrivialTypeSourceInfo);
+                                    WantNontrivialTypeSourceInfo,
+                                    IsClassTemplateDeductionContext);
         if (Ty) {
           diagnoseTypo(Correction,
                        PDiag(diag::err_unknown_type_or_class_name_suggest)
@@ -391,7 +399,8 @@ ParsedType Sema::getTypeName(const IdentifierInfo &II, SourceLocation NameLoc,
     // Look to see if we have a type anywhere in the list of results.
     for (LookupResult::iterator Res = Result.begin(), ResEnd = Result.end();
          Res != ResEnd; ++Res) {
-      if (isa<TypeDecl>(*Res) || isa<ObjCInterfaceDecl>(*Res)) {
+      if (isa<TypeDecl>(*Res) || isa<ObjCInterfaceDecl>(*Res) ||
+          (AllowDeducedTemplate && getAsTypeTemplateDecl(*Res))) {
         if (!IIDecl ||
             (*Res)->getLocation().getRawEncoding() <
               IIDecl->getLocation().getRawEncoding())
@@ -425,33 +434,29 @@ ParsedType Sema::getTypeName(const IdentifierInfo &II, SourceLocation NameLoc,
 
   QualType T;
   if (TypeDecl *TD = dyn_cast<TypeDecl>(IIDecl)) {
+    // C++ [class.qual]p2: A lookup that would find the injected-class-name
+    // instead names the constructors of the class, except when naming a class.
+    // This is ill-formed when we're not actually forming a ctor or dtor name.
+    auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
+    auto *FoundRD = dyn_cast<CXXRecordDecl>(TD);
+    if (!isClassName && !IsCtorOrDtorName && LookupRD && FoundRD &&
+        FoundRD->isInjectedClassName() &&
+        declaresSameEntity(LookupRD, cast<Decl>(FoundRD->getParent())))
+      Diag(NameLoc, diag::err_out_of_line_qualified_id_type_names_constructor)
+          << &II << /*Type*/1;
+
     DiagnoseUseOfDecl(IIDecl, NameLoc);
 
     T = Context.getTypeDeclType(TD);
     MarkAnyDeclReferenced(TD->getLocation(), TD, /*OdrUse=*/false);
-
-    // NOTE: avoid constructing an ElaboratedType(Loc) if this is a
-    // constructor or destructor name (in such a case, the scope specifier
-    // will be attached to the enclosing Expr or Decl node).
-    if (SS && SS->isNotEmpty() && !IsCtorOrDtorName) {
-      if (WantNontrivialTypeSourceInfo) {
-        // Construct a type with type-source information.
-        TypeLocBuilder Builder;
-        Builder.pushTypeSpec(T).setNameLoc(NameLoc);
-
-        T = getElaboratedType(ETK_None, *SS, T);
-        ElaboratedTypeLoc ElabTL = Builder.push<ElaboratedTypeLoc>(T);
-        ElabTL.setElaboratedKeywordLoc(SourceLocation());
-        ElabTL.setQualifierLoc(SS->getWithLocInContext(Context));
-        return CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
-      } else {
-        T = getElaboratedType(ETK_None, *SS, T);
-      }
-    }
   } else if (ObjCInterfaceDecl *IDecl = dyn_cast<ObjCInterfaceDecl>(IIDecl)) {
     (void)DiagnoseUseOfDecl(IDecl, NameLoc);
     if (!HasTrailingDot)
       T = Context.getObjCInterfaceType(IDecl);
+  } else if (AllowDeducedTemplate) {
+    if (auto *TD = getAsTypeTemplateDecl(IIDecl))
+      T = Context.getDeducedTemplateSpecializationType(TemplateName(TD),
+                                                       QualType(), false);
   }
 
   if (T.isNull()) {
@@ -459,6 +464,27 @@ ParsedType Sema::getTypeName(const IdentifierInfo &II, SourceLocation NameLoc,
     Result.suppressDiagnostics();
     return nullptr;
   }
+
+  // NOTE: avoid constructing an ElaboratedType(Loc) if this is a
+  // constructor or destructor name (in such a case, the scope specifier
+  // will be attached to the enclosing Expr or Decl node).
+  if (SS && SS->isNotEmpty() && !IsCtorOrDtorName &&
+      !isa<ObjCInterfaceDecl>(IIDecl)) {
+    if (WantNontrivialTypeSourceInfo) {
+      // Construct a type with type-source information.
+      TypeLocBuilder Builder;
+      Builder.pushTypeSpec(T).setNameLoc(NameLoc);
+
+      T = getElaboratedType(ETK_None, *SS, T);
+      ElaboratedTypeLoc ElabTL = Builder.push<ElaboratedTypeLoc>(T);
+      ElabTL.setElaboratedKeywordLoc(SourceLocation());
+      ElabTL.setQualifierLoc(SS->getWithLocInContext(Context));
+      return CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
+    } else {
+      T = getElaboratedType(ETK_None, *SS, T);
+    }
+  }
+
   return ParsedType::make(T);
 }
 
@@ -636,6 +662,7 @@ void Sema::DiagnoseUnknownTypeName(IdentifierInfo *&II,
       if (Corrected.getCorrectionSpecifier())
         tmpSS.MakeTrivial(Context, Corrected.getCorrectionSpecifier(),
                           SourceRange(IILoc));
+      // FIXME: Support class template argument deduction here.
       SuggestedType =
           getTypeName(*Corrected.getCorrectionAsIdentifierInfo(), IILoc, S,
                       tmpSS.isSet() ? &tmpSS : SS, false, false, nullptr,
@@ -656,7 +683,8 @@ void Sema::DiagnoseUnknownTypeName(IdentifierInfo *&II,
                        Name, nullptr, true, TemplateResult,
                        MemberOfUnknownSpecialization) == TNK_Type_template) {
       TemplateName TplName = TemplateResult.get();
-      Diag(IILoc, diag::err_template_missing_args) << TplName;
+      Diag(IILoc, diag::err_template_missing_args)
+        << (int)getTemplateNameKindForDiagnostics(TplName) << TplName;
       if (TemplateDecl *TplDecl = TplName.getAsTemplateDecl()) {
         Diag(TplDecl->getLocation(), diag::note_template_decl_here)
           << TplDecl->getTemplateParameters()->getSourceRange();
@@ -782,6 +810,13 @@ Sema::ClassifyName(Scope *S, CXXScopeSpec &SS, IdentifierInfo *&Name,
   if (NextToken.is(tok::coloncolon)) {
     NestedNameSpecInfo IdInfo(Name, NameLoc, NextToken.getLocation());
     BuildCXXNestedNameSpecifier(S, IdInfo, false, SS, nullptr, false);
+  } else if (getLangOpts().CPlusPlus && SS.isSet() &&
+             isCurrentClassName(*Name, S, &SS)) {
+    // Per [class.qual]p2, this names the constructors of SS, not the
+    // injected-class-name. We don't have a classification for that.
+    // There's not much point caching this result, since the parser
+    // will reject it later.
+    return NameClassification::Unknown();
   }
 
   LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
@@ -1072,6 +1107,24 @@ Corrected:
   return BuildDeclarationNameExpr(SS, Result, ADL);
 }
 
+Sema::TemplateNameKindForDiagnostics
+Sema::getTemplateNameKindForDiagnostics(TemplateName Name) {
+  auto *TD = Name.getAsTemplateDecl();
+  if (!TD)
+    return TemplateNameKindForDiagnostics::DependentTemplate;
+  if (isa<ClassTemplateDecl>(TD))
+    return TemplateNameKindForDiagnostics::ClassTemplate;
+  if (isa<FunctionTemplateDecl>(TD))
+    return TemplateNameKindForDiagnostics::FunctionTemplate;
+  if (isa<VarTemplateDecl>(TD))
+    return TemplateNameKindForDiagnostics::VarTemplate;
+  if (isa<TypeAliasTemplateDecl>(TD))
+    return TemplateNameKindForDiagnostics::AliasTemplate;
+  if (isa<TemplateTemplateParmDecl>(TD))
+    return TemplateNameKindForDiagnostics::TemplateTemplateParam;
+  return TemplateNameKindForDiagnostics::DependentTemplate;
+}
+
 // Determines the context to return to after temporarily entering a
 // context.  This depends in an unnecessarily complicated way on the
 // exact ordering of callbacks from the parser.
@@ -2101,7 +2154,9 @@ void Sema::MergeTypedefNameDecl(Scope *S, TypedefNameDecl *New,
   // -Wtypedef-redefinition.  If either the original or the redefinition is
   // in a system header, don't emit this for compatibility with GCC.
   if (getDiagnostics().getSuppressSystemWarnings() &&
-      (Context.getSourceManager().isInSystemHeader(Old->getLocation()) ||
+      // Some standard types are defined implicitly in Clang (e.g. OpenCL).
+      (Old->isImplicit() ||
+       Context.getSourceManager().isInSystemHeader(Old->getLocation()) ||
        Context.getSourceManager().isInSystemHeader(New->getLocation())))
     return;
 
@@ -3035,7 +3090,7 @@ bool Sema::MergeFunctionDecl(FunctionDecl *New, NamedDecl *&OldD,
         //   [...] A member shall not be declared twice in the
         //   member-specification, except that a nested class or member
         //   class template can be declared and then later defined.
-        if (ActiveTemplateInstantiations.empty()) {
+        if (!inTemplateInstantiation()) {
           unsigned NewDiag;
           if (isa<CXXConstructorDecl>(OldMethod))
             NewDiag = diag::err_constructor_redeclared;
@@ -4622,6 +4677,34 @@ Sema::GetNameFromUnqualifiedId(const UnqualifiedId &Name) {
     NameInfo.setLoc(Name.StartLocation);
     return NameInfo;
 
+  case UnqualifiedId::IK_DeductionGuideName: {
+    // C++ [temp.deduct.guide]p3:
+    //   The simple-template-id shall name a class template specialization.
+    //   The template-name shall be the same identifier as the template-name
+    //   of the simple-template-id.
+    // These together intend to imply that the template-name shall name a
+    // class template.
+    // FIXME: template<typename T> struct X {};
+    //        template<typename T> using Y = X<T>;
+    //        Y(int) -> Y<int>;
+    //   satisfies these rules but does not name a class template.
+    TemplateName TN = Name.TemplateName.get().get();
+    auto *Template = TN.getAsTemplateDecl();
+    if (!Template || !isa<ClassTemplateDecl>(Template)) {
+      Diag(Name.StartLocation,
+           diag::err_deduction_guide_name_not_class_template)
+        << (int)getTemplateNameKindForDiagnostics(TN) << TN;
+      if (Template)
+        Diag(Template->getLocation(), diag::note_template_decl_here);
+      return DeclarationNameInfo();
+    }
+
+    NameInfo.setName(
+        Context.DeclarationNames.getCXXDeductionGuideName(Template));
+    NameInfo.setLoc(Name.StartLocation);
+    return NameInfo;
+  }
+
   case UnqualifiedId::IK_OperatorFunctionId:
     NameInfo.setName(Context.DeclarationNames.getCXXOperatorName(
                                            Name.OperatorFunctionId.Operator));
@@ -5382,8 +5465,13 @@ Sema::ActOnTypedefDeclarator(Scope* S, Declarator& D, DeclContext* DC,
          diag::err_concept_wrong_decl_kind);
 
   if (D.getName().Kind != UnqualifiedId::IK_Identifier) {
-    Diag(D.getName().StartLocation, diag::err_typedef_not_identifier)
-      << D.getName().getSourceRange();
+    if (D.getName().Kind == UnqualifiedId::IK_DeductionGuideName)
+      Diag(D.getName().StartLocation,
+           diag::err_deduction_guide_invalid_specifier)
+          << "typedef";
+    else
+      Diag(D.getName().StartLocation, diag::err_typedef_not_identifier)
+          << D.getName().getSourceRange();
     return nullptr;
   }
 
@@ -5444,6 +5532,10 @@ Sema::CheckTypedefForVariablyModifiedType(Scope *S, TypedefNameDecl *NewTD) {
 NamedDecl*
 Sema::ActOnTypedefNameDecl(Scope *S, DeclContext *DC, TypedefNameDecl *NewTD,
                            LookupResult &Previous, bool &Redeclaration) {
+
+  // Find the shadowed declaration before filtering for scope.
+  NamedDecl *ShadowedDecl = getShadowedDeclaration(NewTD, Previous);
+
   // Merge the decl with the existing one if appropriate. If the decl is
   // in an outer scope, it isn't the same thing.
   FilterLookupForScope(Previous, DC, S, /*ConsiderLinkage*/false,
@@ -5454,6 +5546,9 @@ Sema::ActOnTypedefNameDecl(Scope *S, DeclContext *DC, TypedefNameDecl *NewTD,
     MergeTypedefNameDecl(S, NewTD, Previous);
   }
 
+  if (ShadowedDecl && !Redeclaration)
+    CheckShadow(NewTD, ShadowedDecl, Previous);
+
   // If this is the C FILE type, notify the AST context.
   if (IdentifierInfo *II = NewTD->getIdentifier())
     if (!NewTD->isInvalidDecl() &&
@@ -5649,13 +5744,17 @@ static void checkDLLAttributeRedeclaration(Sema &S, NamedDecl *OldDecl,
   if (OldDecl->isInvalidDecl())
     return;
 
+  bool IsTemplate = false;
   if (TemplateDecl *OldTD = dyn_cast<TemplateDecl>(OldDecl)) {
     OldDecl = OldTD->getTemplatedDecl();
+    IsTemplate = true;
     if (!IsSpecialization)
       IsDefinition = false;
   }
-  if (TemplateDecl *NewTD = dyn_cast<TemplateDecl>(NewDecl))
+  if (TemplateDecl *NewTD = dyn_cast<TemplateDecl>(NewDecl)) {
     NewDecl = NewTD->getTemplatedDecl();
+    IsTemplate = true;
+  }
 
   if (!OldDecl || !NewDecl)
     return;
@@ -5708,9 +5807,10 @@ static void checkDLLAttributeRedeclaration(Sema &S, NamedDecl *OldDecl,
   }
 
   // A redeclaration is not allowed to drop a dllimport attribute, the only
-  // exceptions being inline function definitions, local extern declarations,
-  // qualified friend declarations or special MSVC extension: in the last case,
-  // the declaration is treated as if it were marked dllexport.
+  // exceptions being inline function definitions (except for function
+  // templates), local extern declarations, qualified friend declarations or
+  // special MSVC extension: in the last case, the declaration is treated as if
+  // it were marked dllexport.
   bool IsInline = false, IsStaticDataMember = false, IsQualifiedFriend = false;
   bool IsMicrosoft = S.Context.getTargetInfo().getCXXABI().isMicrosoft();
   if (const auto *VD = dyn_cast<VarDecl>(NewDecl)) {
@@ -5725,7 +5825,8 @@ static void checkDLLAttributeRedeclaration(Sema &S, NamedDecl *OldDecl,
                         FD->getFriendObjectKind() == Decl::FOK_Declared;
   }
 
-  if (OldImportAttr && !HasNewAttr && !IsInline && !IsStaticDataMember &&
+  if (OldImportAttr && !HasNewAttr &&
+      (!IsInline || (IsMicrosoft && IsTemplate)) && !IsStaticDataMember &&
       !NewDecl->isLocalExternDecl() && !IsQualifiedFriend) {
     if (IsMicrosoft && IsDefinition) {
       S.Diag(NewDecl->getLocation(),
@@ -5902,8 +6003,7 @@ NamedDecl *Sema::ActOnVariableDeclarator(
       Name = II;
     }
   } else if (!II) {
-    Diag(D.getIdentifierLoc(), diag::err_bad_variable_name)
-      << Name;
+    Diag(D.getIdentifierLoc(), diag::err_bad_variable_name) << Name;
     return nullptr;
   }
 
@@ -6017,7 +6117,7 @@ NamedDecl *Sema::ActOnVariableDeclarator(
     }
   }
 
-  bool IsExplicitSpecialization = false;
+  bool IsMemberSpecialization = false;
   bool IsVariableTemplateSpecialization = false;
   bool IsPartialSpecialization = false;
   bool IsVariableTemplate = false;
@@ -6029,7 +6129,7 @@ NamedDecl *Sema::ActOnVariableDeclarator(
                             D.getIdentifierLoc(), II,
                             R, TInfo, SC);
 
-    if (D.getDeclSpec().containsPlaceholderType() && R->getContainedAutoType())
+    if (R->getContainedDeducedType())
       ParsingInitForAutoVars.insert(NewVD);
 
     if (D.isInvalidType())
@@ -6095,7 +6195,7 @@ NamedDecl *Sema::ActOnVariableDeclarator(
             ? D.getName().TemplateId
             : nullptr,
         TemplateParamLists,
-        /*never a friend*/ false, IsExplicitSpecialization, Invalid);
+        /*never a friend*/ false, IsMemberSpecialization, Invalid);
 
     if (TemplateParams) {
       if (!TemplateParams->size() &&
@@ -6165,7 +6265,7 @@ NamedDecl *Sema::ActOnVariableDeclarator(
 
     // If this decl has an auto type in need of deduction, make a note of the
     // Decl so we can diagnose uses of it in its own initializer.
-    if (D.getDeclSpec().containsPlaceholderType() && R->getContainedAutoType())
+    if (R->getContainedDeducedType())
       ParsingInitForAutoVars.insert(NewVD);
 
     if (D.isInvalidType() || Invalid) {
@@ -6321,7 +6421,7 @@ NamedDecl *Sema::ActOnVariableDeclarator(
           << (IsPartialSpecialization ? 1 : 0)
           << FixItHint::CreateRemoval(
                  D.getDeclSpec().getModulePrivateSpecLoc());
-    else if (IsExplicitSpecialization)
+    else if (IsMemberSpecialization)
       Diag(NewVD->getLocation(), diag::err_module_private_specialization)
         << 2
         << FixItHint::CreateRemoval(D.getDeclSpec().getModulePrivateSpecLoc());
@@ -6436,7 +6536,7 @@ NamedDecl *Sema::ActOnVariableDeclarator(
   // declaration has linkage).
   FilterLookupForScope(Previous, OriginalDC, S, shouldConsiderLinkage(NewVD),
                        D.getCXXScopeSpec().isNotEmpty() ||
-                       IsExplicitSpecialization ||
+                       IsMemberSpecialization ||
                        IsVariableTemplateSpecialization);
 
   // Check whether the previous declaration is in the same block scope. This
@@ -6451,7 +6551,7 @@ NamedDecl *Sema::ActOnVariableDeclarator(
     D.setRedeclaration(CheckVariableDeclaration(NewVD, Previous));
   } else {
     // If this is an explicit specialization of a static data member, check it.
-    if (IsExplicitSpecialization && !NewVD->isInvalidDecl() &&
+    if (IsMemberSpecialization && !NewVD->isInvalidDecl() &&
         CheckMemberSpecialization(NewVD, Previous))
       NewVD->setInvalidDecl();
 
@@ -6566,7 +6666,7 @@ NamedDecl *Sema::ActOnVariableDeclarator(
   if (D.isRedeclaration() && !Previous.empty()) {
     checkDLLAttributeRedeclaration(
         *this, dyn_cast<NamedDecl>(Previous.getRepresentativeDecl()), NewVD,
-        IsExplicitSpecialization, D.isFunctionDefinition());
+        IsMemberSpecialization, D.isFunctionDefinition());
   }
 
   if (NewTemplate) {
@@ -6580,13 +6680,25 @@ NamedDecl *Sema::ActOnVariableDeclarator(
 }
 
 /// Enum describing the %select options in diag::warn_decl_shadow.
-enum ShadowedDeclKind { SDK_Local, SDK_Global, SDK_StaticMember, SDK_Field };
+enum ShadowedDeclKind {
+  SDK_Local,
+  SDK_Global,
+  SDK_StaticMember,
+  SDK_Field,
+  SDK_Typedef,
+  SDK_Using
+};
 
 /// Determine what kind of declaration we're shadowing.
 static ShadowedDeclKind computeShadowedDeclKind(const NamedDecl *ShadowedDecl,
                                                 const DeclContext *OldDC) {
-  if (isa<RecordDecl>(OldDC))
+  if (isa<TypeAliasDecl>(ShadowedDecl))
+    return SDK_Using;
+  else if (isa<TypedefDecl>(ShadowedDecl))
+    return SDK_Typedef;
+  else if (isa<RecordDecl>(OldDC))
     return isa<FieldDecl>(ShadowedDecl) ? SDK_Field : SDK_StaticMember;
+
   return OldDC->isFileContext() ? SDK_Global : SDK_Local;
 }
 
@@ -6601,28 +6713,48 @@ static SourceLocation getCaptureLocation(const LambdaScopeInfo *LSI,
   return SourceLocation();
 }
 
+static bool shouldWarnIfShadowedDecl(const DiagnosticsEngine &Diags,
+                                     const LookupResult &R) {
+  // Only diagnose if we're shadowing an unambiguous field or variable.
+  if (R.getResultKind() != LookupResult::Found)
+    return false;
+
+  // Return false if warning is ignored.
+  return !Diags.isIgnored(diag::warn_decl_shadow, R.getNameLoc());
+}
+
 /// \brief Return the declaration shadowed by the given variable \p D, or null
 /// if it doesn't shadow any declaration or shadowing warnings are disabled.
 NamedDecl *Sema::getShadowedDeclaration(const VarDecl *D,
                                         const LookupResult &R) {
-  // Return if warning is ignored.
-  if (Diags.isIgnored(diag::warn_decl_shadow, R.getNameLoc()))
+  if (!shouldWarnIfShadowedDecl(Diags, R))
     return nullptr;
 
   // Don't diagnose declarations at file scope.
   if (D->hasGlobalStorage())
     return nullptr;
 
-  // Only diagnose if we're shadowing an unambiguous field or variable.
-  if (R.getResultKind() != LookupResult::Found)
-    return nullptr;
-
   NamedDecl *ShadowedDecl = R.getFoundDecl();
   return isa<VarDecl>(ShadowedDecl) || isa<FieldDecl>(ShadowedDecl)
              ? ShadowedDecl
              : nullptr;
 }
 
+/// \brief Return the declaration shadowed by the given typedef \p D, or null
+/// if it doesn't shadow any declaration or shadowing warnings are disabled.
+NamedDecl *Sema::getShadowedDeclaration(const TypedefNameDecl *D,
+                                        const LookupResult &R) {
+  // Don't warn if typedef declaration is part of a class
+  if (D->getDeclContext()->isRecord())
+    return nullptr;
+  
+  if (!shouldWarnIfShadowedDecl(Diags, R))
+    return nullptr;
+
+  NamedDecl *ShadowedDecl = R.getFoundDecl();
+  return isa<TypedefNameDecl>(ShadowedDecl) ? ShadowedDecl : nullptr;
+}
+
 /// \brief Diagnose variable or built-in function shadowing.  Implements
 /// -Wshadow.
 ///
@@ -6632,7 +6764,7 @@ NamedDecl *Sema::getShadowedDeclaration(const VarDecl *D,
 /// \param ShadowedDecl the declaration that is shadowed by the given variable
 /// \param R the lookup of the name
 ///
-void Sema::CheckShadow(VarDecl *D, NamedDecl *ShadowedDecl,
+void Sema::CheckShadow(NamedDecl *D, NamedDecl *ShadowedDecl,
                        const LookupResult &R) {
   DeclContext *NewDC = D->getDeclContext();
 
@@ -6644,13 +6776,13 @@ void Sema::CheckShadow(VarDecl *D, NamedDecl *ShadowedDecl,
 
     // Fields shadowed by constructor parameters are a special case. Usually
     // the constructor initializes the field with the parameter.
-    if (isa<CXXConstructorDecl>(NewDC) && isa<ParmVarDecl>(D)) {
-      // Remember that this was shadowed so we can either warn about its
-      // modification or its existence depending on warning settings.
-      D = D->getCanonicalDecl();
-      ShadowingDecls.insert({D, FD});
-      return;
-    }
+    if (isa<CXXConstructorDecl>(NewDC))
+      if (const auto PVD = dyn_cast<ParmVarDecl>(D)) {
+        // Remember that this was shadowed so we can either warn about its
+        // modification or its existence depending on warning settings.
+        ShadowingDecls.insert({PVD->getCanonicalDecl(), FD});
+        return;
+      }
   }
 
   if (VarDecl *shadowedVar = dyn_cast<VarDecl>(ShadowedDecl))
@@ -6668,7 +6800,8 @@ void Sema::CheckShadow(VarDecl *D, NamedDecl *ShadowedDecl,
 
   unsigned WarningDiag = diag::warn_decl_shadow;
   SourceLocation CaptureLoc;
-  if (isa<VarDecl>(ShadowedDecl) && NewDC && isa<CXXMethodDecl>(NewDC)) {
+  if (isa<VarDecl>(D) && isa<VarDecl>(ShadowedDecl) && NewDC &&
+      isa<CXXMethodDecl>(NewDC)) {
     if (const auto *RD = dyn_cast<CXXRecordDecl>(NewDC->getParent())) {
       if (RD->isLambda() && OldDC->Encloses(NewDC->getLexicalParent())) {
         if (RD->getLambdaCaptureDefault() == LCD_None) {
@@ -6682,7 +6815,8 @@ void Sema::CheckShadow(VarDecl *D, NamedDecl *ShadowedDecl,
           // Remember that this was shadowed so we can avoid the warning if the
           // shadowed decl isn't captured and the warning settings allow it.
           cast<LambdaScopeInfo>(getCurFunction())
-              ->ShadowingDecls.push_back({D, cast<VarDecl>(ShadowedDecl)});
+              ->ShadowingDecls.push_back(
+                  {cast<VarDecl>(D), cast<VarDecl>(ShadowedDecl)});
           return;
         }
       }
@@ -7430,6 +7564,7 @@ static StorageClass getFunctionStorageClass(Sema &SemaRef, Declarator &D) {
   case DeclSpec::SCS_mutable:
     SemaRef.Diag(D.getDeclSpec().getStorageClassSpecLoc(),
                  diag::err_typecheck_sclass_func);
+    D.getMutableDeclSpec().ClearStorageClassSpecs();
     D.setInvalidType();
     break;
   case DeclSpec::SCS_unspecified: break;
@@ -7472,11 +7607,12 @@ static FunctionDecl* CreateNewFunctionDecl(Sema &SemaRef, Declarator &D,
     // Determine whether the function was written with a
     // prototype. This true when:
     //   - there is a prototype in the declarator, or
-    //   - the type R of the function is some kind of typedef or other reference
-    //     to a type name (which eventually refers to a function type).
+    //   - the type R of the function is some kind of typedef or other non-
+    //     attributed reference to a type name (which eventually refers to a
+    //     function type).
     bool HasPrototype =
       (D.isFunctionDeclarator() && D.getFunctionTypeInfo().hasPrototype) ||
-      (!isa<FunctionType>(R.getTypePtr()) && R->isFunctionProtoType());
+      (!R->getAsAdjusted<FunctionType>() && R->isFunctionProtoType());
 
     NewFD = FunctionDecl::Create(SemaRef.Context, DC,
                                  D.getLocStart(), NameInfo, R,
@@ -7562,6 +7698,12 @@ static FunctionDecl* CreateNewFunctionDecl(Sema &SemaRef, Declarator &D,
                                      R, TInfo, isInline, isExplicit,
                                      isConstexpr, SourceLocation());
 
+  } else if (Name.getNameKind() == DeclarationName::CXXDeductionGuideName) {
+    SemaRef.CheckDeductionGuideDeclarator(D, R, SC);
+
+    return CXXDeductionGuideDecl::Create(SemaRef.Context, DC, D.getLocStart(),
+                                         isExplicit, NameInfo, R, TInfo,
+                                         D.getLocEnd());
   } else if (DC->isRecord()) {
     // If the name of the function is the same as the name of the record,
     // then this must be an invalid constructor that has a return type.
@@ -7835,7 +7977,7 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
 
   bool isFriend = false;
   FunctionTemplateDecl *FunctionTemplate = nullptr;
-  bool isExplicitSpecialization = false;
+  bool isMemberSpecialization = false;
   bool isFunctionTemplateSpecialization = false;
 
   bool isDependentClassScopeExplicitSpecialization = false;
@@ -7891,7 +8033,7 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
     }
 
     SetNestedNameSpecifier(NewFD, D);
-    isExplicitSpecialization = false;
+    isMemberSpecialization = false;
     isFunctionTemplateSpecialization = false;
     if (D.isInvalidType())
       NewFD->setInvalidDecl();
@@ -7906,7 +8048,7 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
                 D.getName().getKind() == UnqualifiedId::IK_TemplateId
                     ? D.getName().TemplateId
                     : nullptr,
-                TemplateParamLists, isFriend, isExplicitSpecialization,
+                TemplateParamLists, isFriend, isMemberSpecialization,
                 Invalid)) {
       if (TemplateParams->size() > 0) {
         // This is a function template
@@ -8050,7 +8192,8 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
     //  The explicit specifier shall be used only in the declaration of a
     //  constructor or conversion function within its class definition;
     //  see 12.3.1 and 12.3.2.
-    if (isExplicit && !NewFD->isInvalidDecl()) {
+    if (isExplicit && !NewFD->isInvalidDecl() &&
+        !isa<CXXDeductionGuideDecl>(NewFD)) {
       if (!CurContext->isRecord()) {
         // 'explicit' was specified outside of the class.
         Diag(D.getDeclSpec().getExplicitSpecLoc(),
@@ -8239,7 +8382,7 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
   // Filter out previous declarations that don't match the scope.
   FilterLookupForScope(Previous, OriginalDC, S, shouldConsiderLinkage(NewFD),
                        D.getCXXScopeSpec().isNotEmpty() ||
-                       isExplicitSpecialization ||
+                       isMemberSpecialization ||
                        isFunctionTemplateSpecialization);
 
   // Handle GNU asm-label extension (encoded as an attribute).
@@ -8389,7 +8532,6 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
 
   if (!getLangOpts().CPlusPlus) {
     // Perform semantic checking on the function declaration.
-    bool isExplicitSpecialization=false;
     if (!NewFD->isInvalidDecl() && NewFD->isMain())
       CheckMain(NewFD, D.getDeclSpec());
 
@@ -8398,7 +8540,7 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
 
     if (!NewFD->isInvalidDecl())
       D.setRedeclaration(CheckFunctionDeclaration(S, NewFD, Previous,
-                                                  isExplicitSpecialization));
+                                                  isMemberSpecialization));
     else if (!Previous.empty())
       // Recover gracefully from an invalid redeclaration.
       D.setRedeclaration(true);
@@ -8533,7 +8675,7 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
             << FixItHint::CreateRemoval(
                                       D.getDeclSpec().getStorageClassSpecLoc());
       }
-    } else if (isExplicitSpecialization && isa<CXXMethodDecl>(NewFD)) {
+    } else if (isMemberSpecialization && isa<CXXMethodDecl>(NewFD)) {
       if (CheckMemberSpecialization(NewFD, Previous))
           NewFD->setInvalidDecl();
     }
@@ -8548,7 +8690,7 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
 
       if (!NewFD->isInvalidDecl())
         D.setRedeclaration(CheckFunctionDeclaration(S, NewFD, Previous,
-                                                    isExplicitSpecialization));
+                                                    isMemberSpecialization));
       else if (!Previous.empty())
         // Recover gracefully from an invalid redeclaration.
         D.setRedeclaration(true);
@@ -8654,7 +8796,7 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
     } else if (!D.isFunctionDefinition() &&
                isa<CXXMethodDecl>(NewFD) && NewFD->isOutOfLine() &&
                !isFriend && !isFunctionTemplateSpecialization &&
-               !isExplicitSpecialization) {
+               !isMemberSpecialization) {
       // An out-of-line member function declaration must also be a
       // definition (C++ [class.mfct]p2).
       // Note that this is not the case for explicit specializations of
@@ -8715,7 +8857,7 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
   if (D.isRedeclaration() && !Previous.empty()) {
     checkDLLAttributeRedeclaration(
         *this, dyn_cast<NamedDecl>(Previous.getRepresentativeDecl()), NewFD,
-        isExplicitSpecialization || isFunctionTemplateSpecialization,
+        isMemberSpecialization || isFunctionTemplateSpecialization,
         D.isFunctionDefinition());
   }
 
@@ -8840,15 +8982,16 @@ bool Sema::shouldLinkDependentDeclWithPrevious(Decl *D, Decl *PrevDecl) {
 /// that have been instantiated via C++ template instantiation (called
 /// via InstantiateDecl).
 ///
-/// \param IsExplicitSpecialization whether this new function declaration is
-/// an explicit specialization of the previous declaration.
+/// \param IsMemberSpecialization whether this new function declaration is
+/// a member specialization (that replaces any definition provided by the
+/// previous declaration).
 ///
 /// This sets NewFD->isInvalidDecl() to true if there was an error.
 ///
 /// \returns true if the function declaration is a redeclaration.
 bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD,
                                     LookupResult &Previous,
-                                    bool IsExplicitSpecialization) {
+                                    bool IsMemberSpecialization) {
   assert(!NewFD->getReturnType()->isVariablyModifiedType() &&
          "Variably modified return types are not handled here");
 
@@ -8895,14 +9038,10 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD,
         // with that name must be marked "overloadable".
         Diag(NewFD->getLocation(), diag::err_attribute_overloadable_missing)
           << Redeclaration << NewFD;
-        NamedDecl *OverloadedDecl = nullptr;
-        if (Redeclaration)
-          OverloadedDecl = OldDecl;
-        else if (!Previous.empty())
-          OverloadedDecl = Previous.getRepresentativeDecl();
-        if (OverloadedDecl)
-          Diag(OverloadedDecl->getLocation(),
-               diag::note_attribute_overloadable_prev_overload);
+        NamedDecl *OverloadedDecl =
+            Redeclaration ? OldDecl : Previous.getRepresentativeDecl();
+        Diag(OverloadedDecl->getLocation(),
+             diag::note_attribute_overloadable_prev_overload);
         NewFD->addAttr(OverloadableAttr::CreateImplicit(Context));
       }
     }
@@ -8961,7 +9100,7 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD,
 
       // Warn that we did this, if we're not performing template instantiation.
       // In that case, we'll have warned already when the template was defined.
-      if (ActiveTemplateInstantiations.empty()) {
+      if (!inTemplateInstantiation()) {
         SourceLocation AddConstLoc;
         if (FunctionTypeLoc FTL = MD->getTypeSourceInfo()->getTypeLoc()
                 .IgnoreParens().getAs<FunctionTypeLoc>())
@@ -8998,7 +9137,7 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD,
 
       // If this is an explicit specialization of a member that is a function
       // template, mark it as a member specialization.
-      if (IsExplicitSpecialization &&
+      if (IsMemberSpecialization &&
           NewTemplateDecl->getInstantiatedFromMemberTemplate()) {
         NewTemplateDecl->setMemberSpecialization();
         assert(OldTemplateDecl->isMemberSpecialization());
@@ -9048,6 +9187,15 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD,
     } else if (CXXConversionDecl *Conversion
                = dyn_cast<CXXConversionDecl>(NewFD)) {
       ActOnConversionDeclarator(Conversion);
+    } else if (auto *Guide = dyn_cast<CXXDeductionGuideDecl>(NewFD)) {
+      if (auto *TD = Guide->getDescribedFunctionTemplate())
+        CheckDeductionGuideTemplate(TD);
+
+      // A deduction guide is not on the list of entities that can be
+      // explicitly specialized.
+      if (Guide->getTemplateSpecializationKind() == TSK_ExplicitSpecialization)
+        Diag(Guide->getLocStart(), diag::err_deduction_guide_specialized)
+            << /*explicit specialization*/ 1;
     }
 
     // Find any virtual functions that this function overrides.
@@ -9395,7 +9543,7 @@ namespace {
       InitFieldIndex.pop_back();
     }
 
-    // Returns true if MemberExpr is checked and no futher checking is needed.
+    // Returns true if MemberExpr is checked and no further checking is needed.
     // Returns false if additional checking is required.
     bool CheckInitListMemberExpr(MemberExpr *E, bool CheckReference) {
       llvm::SmallVector<FieldDecl*, 4> Fields;
@@ -9703,11 +9851,36 @@ QualType Sema::deduceVarTypeFromInitializer(VarDecl *VDecl,
 
   VarDeclOrName VN{VDecl, Name};
 
-  ArrayRef<Expr *> DeduceInits = Init;
+  DeducedType *Deduced = Type->getContainedDeducedType();
+  assert(Deduced && "deduceVarTypeFromInitializer for non-deduced type");
+
+  // C++11 [dcl.spec.auto]p3
+  if (!Init) {
+    assert(VDecl && "no init for init capture deduction?");
+    Diag(VDecl->getLocation(), diag::err_auto_var_requires_init)
+      << VDecl->getDeclName() << Type;
+    return QualType();
+  }
+
+  ArrayRef<Expr*> DeduceInits = Init;
   if (DirectInit) {
-    if (auto *PL = dyn_cast<ParenListExpr>(Init))
+    if (auto *PL = dyn_cast_or_null<ParenListExpr>(Init))
       DeduceInits = PL->exprs();
-    else if (auto *IL = dyn_cast<InitListExpr>(Init))
+  }
+
+  if (isa<DeducedTemplateSpecializationType>(Deduced)) {
+    assert(VDecl && "non-auto type for init capture deduction?");
+    InitializedEntity Entity = InitializedEntity::InitializeVariable(VDecl);
+    InitializationKind Kind = InitializationKind::CreateForInit(
+        VDecl->getLocation(), DirectInit, Init);
+    // FIXME: Initialization should not be taking a mutable list of inits. 
+    SmallVector<Expr*, 8> InitsCopy(DeduceInits.begin(), DeduceInits.end());
+    return DeduceTemplateSpecializationFromInitializer(TSI, Entity, Kind,
+                                                       InitsCopy);
+  }
+
+  if (DirectInit) {
+    if (auto *IL = dyn_cast<InitListExpr>(Init))
       DeduceInits = IL->inits();
   }
 
@@ -9784,8 +9957,8 @@ QualType Sema::deduceVarTypeFromInitializer(VarDecl *VDecl,
   // checks.
   // We only want to warn outside of template instantiations, though:
   // inside a template, the 'id' could have come from a parameter.
-  if (ActiveTemplateInstantiations.empty() && !DefaultedAnyToId &&
-      !IsInitCapture && !DeducedType.isNull() && DeducedType->isObjCIdType()) {
+  if (!inTemplateInstantiation() && !DefaultedAnyToId && !IsInitCapture &&
+      !DeducedType.isNull() && DeducedType->isObjCIdType()) {
     SourceLocation Loc = TSI->getTypeLoc().getBeginLoc();
     Diag(Loc, diag::warn_auto_var_is_id) << VN << Range;
   }
@@ -9793,6 +9966,36 @@ QualType Sema::deduceVarTypeFromInitializer(VarDecl *VDecl,
   return DeducedType;
 }
 
+bool Sema::DeduceVariableDeclarationType(VarDecl *VDecl, bool DirectInit,
+                                         Expr *Init) {
+  QualType DeducedType = deduceVarTypeFromInitializer(
+      VDecl, VDecl->getDeclName(), VDecl->getType(), VDecl->getTypeSourceInfo(),
+      VDecl->getSourceRange(), DirectInit, Init);
+  if (DeducedType.isNull()) {
+    VDecl->setInvalidDecl();
+    return true;
+  }
+
+  VDecl->setType(DeducedType);
+  assert(VDecl->isLinkageValid());
+
+  // In ARC, infer lifetime.
+  if (getLangOpts().ObjCAutoRefCount && inferObjCARCLifetime(VDecl))
+    VDecl->setInvalidDecl();
+
+  // If this is a redeclaration, check that the type we just deduced matches
+  // the previously declared type.
+  if (VarDecl *Old = VDecl->getPreviousDecl()) {
+    // We never need to merge the type, because we cannot form an incomplete
+    // array of auto, nor deduce such a type.
+    MergeVarDeclTypes(VDecl, Old, /*MergeTypeWithPrevious*/ false);
+  }
+
+  // Check the deduced type is valid for a variable declaration.
+  CheckVariableDeclarationType(VDecl);
+  return VDecl->isInvalidDecl();
+}
+
 /// AddInitializerToDecl - Adds the initializer Init to the
 /// declaration dcl. If DirectInit is true, this is C++ direct
 /// initialization rather than copy initialization.
@@ -9832,32 +10035,7 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
     }
     Init = Res.get();
 
-    QualType DeducedType = deduceVarTypeFromInitializer(
-        VDecl, VDecl->getDeclName(), VDecl->getType(),
-        VDecl->getTypeSourceInfo(), VDecl->getSourceRange(), DirectInit, Init);
-    if (DeducedType.isNull()) {
-      RealDecl->setInvalidDecl();
-      return;
-    }
-
-    VDecl->setType(DeducedType);
-    assert(VDecl->isLinkageValid());
-
-    // In ARC, infer lifetime.
-    if (getLangOpts().ObjCAutoRefCount && inferObjCARCLifetime(VDecl))
-      VDecl->setInvalidDecl();
-
-    // If this is a redeclaration, check that the type we just deduced matches
-    // the previously declared type.
-    if (VarDecl *Old = VDecl->getPreviousDecl()) {
-      // We never need to merge the type, because we cannot form an incomplete
-      // array of auto, nor deduce such a type.
-      MergeVarDeclTypes(VDecl, Old, /*MergeTypeWithPrevious*/ false);
-    }
-
-    // Check the deduced type is valid for a variable declaration.
-    CheckVariableDeclarationType(VDecl);
-    if (VDecl->isInvalidDecl())
+    if (DeduceVariableDeclarationType(VDecl, DirectInit, Init))
       return;
   }
 
@@ -9963,28 +10141,9 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
   // Perform the initialization.
   ParenListExpr *CXXDirectInit = dyn_cast<ParenListExpr>(Init);
   if (!VDecl->isInvalidDecl()) {
-    // Handle errors like: int a({0})
-    if (CXXDirectInit && CXXDirectInit->getNumExprs() == 1 &&
-        !canInitializeWithParenthesizedList(VDecl->getType()))
-      if (auto IList = dyn_cast<InitListExpr>(CXXDirectInit->getExpr(0))) {
-        Diag(VDecl->getLocation(), diag::err_list_init_in_parens)
-            << VDecl->getType() << CXXDirectInit->getSourceRange()
-            << FixItHint::CreateRemoval(CXXDirectInit->getLocStart())
-            << FixItHint::CreateRemoval(CXXDirectInit->getLocEnd());
-        Init = IList;
-        CXXDirectInit = nullptr;
-      }
-
     InitializedEntity Entity = InitializedEntity::InitializeVariable(VDecl);
-    InitializationKind Kind =
-        DirectInit
-            ? CXXDirectInit
-                  ? InitializationKind::CreateDirect(VDecl->getLocation(),
-                                                     Init->getLocStart(),
-                                                     Init->getLocEnd())
-                  : InitializationKind::CreateDirectList(VDecl->getLocation())
-            : InitializationKind::CreateCopy(VDecl->getLocation(),
-                                             Init->getLocStart());
+    InitializationKind Kind = InitializationKind::CreateForInit(
+        VDecl->getLocation(), DirectInit, Init);
 
     MultiExprArg Args = Init;
     if (CXXDirectInit)
@@ -10047,7 +10206,8 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
     // we do not warn to warn spuriously when 'x' and 'y' are on separate
     // paths through the function. This should be revisited if
     // -Wrepeated-use-of-weak is made flow-sensitive.
-    if (VDecl->getType().getObjCLifetime() == Qualifiers::OCL_Strong &&
+    if ((VDecl->getType().getObjCLifetime() == Qualifiers::OCL_Strong ||
+         VDecl->getType().isNonWeakInMRRWithObjCWeak(Context)) &&
         !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak,
                          Init->getLocStart()))
       getCurFunction()->markSafeWeakUse(Init);
@@ -10111,7 +10271,7 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
     // C++11 [class.static.data]p3:
     //   If a non-volatile non-inline const static data member is of integral
     //   or enumeration type, its declaration in the class definition can
-    //   specify a brace-or-equal-initializer in which every initalizer-clause
+    //   specify a brace-or-equal-initializer in which every initializer-clause
     //   that is an assignment-expression is a constant expression. A static
     //   data member of literal type can be declared in the class definition
     //   with the constexpr specifier; if so, its declaration shall specify a
@@ -10281,18 +10441,6 @@ void Sema::ActOnInitializerError(Decl *D) {
   // though.
 }
 
-/// Checks if an object of the given type can be initialized with parenthesized
-/// init-list.
-///
-/// \param TargetType Type of object being initialized.
-///
-/// The function is used to detect wrong initializations, such as 'int({0})'.
-///
-bool Sema::canInitializeWithParenthesizedList(QualType TargetType) {
-  return TargetType->isDependentType() || TargetType->isRecordType() ||
-         TargetType->getContainedAutoType();
-}
-
 void Sema::ActOnUninitializedDecl(Decl *RealDecl) {
   // If there is no declaration, there was an error parsing it. Just ignore it.
   if (!RealDecl)
@@ -10308,13 +10456,9 @@ void Sema::ActOnUninitializedDecl(Decl *RealDecl) {
       return;
     }
 
-    // C++11 [dcl.spec.auto]p3
-    if (Type->isUndeducedType()) {
-      Diag(Var->getLocation(), diag::err_auto_var_requires_init)
-        << Var->getDeclName() << Type;
-      Var->setInvalidDecl();
+    if (Type->isUndeducedType() &&
+        DeduceVariableDeclarationType(Var, false, nullptr))
       return;
-    }
 
     // C++11 [class.static.data]p3: A static data member can be declared with
     // the constexpr specifier; if so, its declaration shall specify
@@ -10693,7 +10837,7 @@ void Sema::CheckCompleteVariableDeclaration(VarDecl *var) {
   // Apply section attributes and pragmas to global variables.
   bool GlobalStorage = var->hasGlobalStorage();
   if (GlobalStorage && var->isThisDeclarationADefinition() &&
-      ActiveTemplateInstantiations.empty()) {
+      !inTemplateInstantiation()) {
     PragmaStack<StringLiteral *> *Stack = nullptr;
     int SectionFlags = ASTContext::PSF_Implicit | ASTContext::PSF_Read;
     if (var->getType().isConstQualified())
@@ -10745,7 +10889,8 @@ void Sema::CheckCompleteVariableDeclaration(VarDecl *var) {
     // Regardless, we don't want to ignore array nesting when
     // constructing this copy.
     if (type->isStructureOrClassType()) {
-      EnterExpressionEvaluationContext scope(*this, PotentiallyEvaluated);
+      EnterExpressionEvaluationContext scope(
+          *this, ExpressionEvaluationContext::PotentiallyEvaluated);
       SourceLocation poi = var->getLocation();
       Expr *varRef =new (Context) DeclRefExpr(var, false, type, VK_LValue, poi);
       ExprResult result
@@ -10865,7 +11010,8 @@ Sema::FinalizeDeclaration(Decl *ThisDecl) {
   if (unsigned MaxAlign = Context.getTargetInfo().getMaxTLSAlign()) {
     // Protect the check so that it's not performed on dependent types and
     // dependent alignments (we can't determine the alignment in that case).
-    if (VD->getTLSKind() && !hasDependentAlignment(VD)) {
+    if (VD->getTLSKind() && !hasDependentAlignment(VD) &&
+        !VD->isInvalidDecl()) {
       CharUnits MaxAlignChars = Context.toCharUnitsFromBits(MaxAlign);
       if (Context.getDeclAlign(VD) > MaxAlignChars) {
         Diag(VD->getLocation(), diag::err_tls_var_aligned_over_maximum)
@@ -11045,6 +11191,11 @@ Sema::FinalizeDeclaration(Decl *ThisDecl) {
   }
 }
 
+static bool hasDeducedAuto(DeclaratorDecl *DD) {
+  auto *VD = dyn_cast<VarDecl>(DD);
+  return VD && !VD->getType()->hasAutoForTrailingReturnType();
+}
+
 Sema::DeclGroupPtrTy Sema::FinalizeDeclaratorGroup(Scope *S, const DeclSpec &DS,
                                                    ArrayRef<Decl *> Group) {
   SmallVector<Decl*, 8> Decls;
@@ -11055,29 +11206,46 @@ Sema::DeclGroupPtrTy Sema::FinalizeDeclaratorGroup(Scope *S, const DeclSpec &DS,
   DeclaratorDecl *FirstDeclaratorInGroup = nullptr;
   DecompositionDecl *FirstDecompDeclaratorInGroup = nullptr;
   bool DiagnosedMultipleDecomps = false;
+  DeclaratorDecl *FirstNonDeducedAutoInGroup = nullptr;
+  bool DiagnosedNonDeducedAuto = false;
 
   for (unsigned i = 0, e = Group.size(); i != e; ++i) {
     if (Decl *D = Group[i]) {
-      auto *DD = dyn_cast<DeclaratorDecl>(D);
-      if (DD && !FirstDeclaratorInGroup)
-        FirstDeclaratorInGroup = DD;
-
-      auto *Decomp = dyn_cast<DecompositionDecl>(D);
-      if (Decomp && !FirstDecompDeclaratorInGroup)
-        FirstDecompDeclaratorInGroup = Decomp;
-
-      // A decomposition declaration cannot be combined with any other
-      // declaration in the same group.
-      auto *OtherDD = FirstDeclaratorInGroup;
-      if (OtherDD == FirstDecompDeclaratorInGroup)
-        OtherDD = DD;
-      if (OtherDD && FirstDecompDeclaratorInGroup &&
-          OtherDD != FirstDecompDeclaratorInGroup &&
-          !DiagnosedMultipleDecomps) {
-        Diag(FirstDecompDeclaratorInGroup->getLocation(),
-             diag::err_decomp_decl_not_alone)
-          << OtherDD->getSourceRange();
-        DiagnosedMultipleDecomps = true;
+      // For declarators, there are some additional syntactic-ish checks we need
+      // to perform.
+      if (auto *DD = dyn_cast<DeclaratorDecl>(D)) {
+        if (!FirstDeclaratorInGroup)
+          FirstDeclaratorInGroup = DD;
+        if (!FirstDecompDeclaratorInGroup)
+          FirstDecompDeclaratorInGroup = dyn_cast<DecompositionDecl>(D);
+        if (!FirstNonDeducedAutoInGroup && DS.hasAutoTypeSpec() &&
+            !hasDeducedAuto(DD))
+          FirstNonDeducedAutoInGroup = DD;
+
+        if (FirstDeclaratorInGroup != DD) {
+          // A decomposition declaration cannot be combined with any other
+          // declaration in the same group.
+          if (FirstDecompDeclaratorInGroup && !DiagnosedMultipleDecomps) {
+            Diag(FirstDecompDeclaratorInGroup->getLocation(),
+                 diag::err_decomp_decl_not_alone)
+                << FirstDeclaratorInGroup->getSourceRange()
+                << DD->getSourceRange();
+            DiagnosedMultipleDecomps = true;
+          }
+
+          // A declarator that uses 'auto' in any way other than to declare a
+          // variable with a deduced type cannot be combined with any other
+          // declarator in the same group.
+          if (FirstNonDeducedAutoInGroup && !DiagnosedNonDeducedAuto) {
+            Diag(FirstNonDeducedAutoInGroup->getLocation(),
+                 diag::err_auto_non_deduced_not_alone)
+                << FirstNonDeducedAutoInGroup->getType()
+                       ->hasAutoForTrailingReturnType()
+                << FirstDeclaratorInGroup->getSourceRange()
+                << DD->getSourceRange();
+            DiagnosedNonDeducedAuto = true;
+          }
+        }
       }
 
       Decls.push_back(D);
@@ -11105,38 +11273,28 @@ Sema::BuildDeclaratorGroup(MutableArrayRef<Decl *> Group) {
   //   deduction, the program is ill-formed.
   if (Group.size() > 1) {
     QualType Deduced;
-    CanQualType DeducedCanon;
     VarDecl *DeducedDecl = nullptr;
     for (unsigned i = 0, e = Group.size(); i != e; ++i) {
-      if (VarDecl *D = dyn_cast<VarDecl>(Group[i])) {
-        AutoType *AT = D->getType()->getContainedAutoType();
-        // FIXME: DR1265: if we have a function pointer declaration, we can have
-        // an 'auto' from a trailing return type. In that case, the return type
-        // must match the various other uses of 'auto'.
-        if (!AT)
-          continue;
-        // Don't reissue diagnostics when instantiating a template.
-        if (D->isInvalidDecl())
-          break;
-        QualType U = AT->getDeducedType();
-        if (!U.isNull()) {
-          CanQualType UCanon = Context.getCanonicalType(U);
-          if (Deduced.isNull()) {
-            Deduced = U;
-            DeducedCanon = UCanon;
-            DeducedDecl = D;
-          } else if (DeducedCanon != UCanon) {
-            Diag(D->getTypeSourceInfo()->getTypeLoc().getBeginLoc(),
-                 diag::err_auto_different_deductions)
-              << (unsigned)AT->getKeyword()
-              << Deduced << DeducedDecl->getDeclName()
-              << U << D->getDeclName()
-              << DeducedDecl->getInit()->getSourceRange()
-              << D->getInit()->getSourceRange();
-            D->setInvalidDecl();
-            break;
-          }
-        }
+      VarDecl *D = dyn_cast<VarDecl>(Group[i]);
+      if (!D || D->isInvalidDecl())
+        break;
+      DeducedType *DT = D->getType()->getContainedDeducedType();
+      if (!DT || DT->getDeducedType().isNull())
+        continue;
+      if (Deduced.isNull()) {
+        Deduced = DT->getDeducedType();
+        DeducedDecl = D;
+      } else if (!Context.hasSameType(DT->getDeducedType(), Deduced)) {
+        auto *AT = dyn_cast<AutoType>(DT);
+        Diag(D->getTypeSourceInfo()->getTypeLoc().getBeginLoc(),
+             diag::err_auto_different_deductions)
+          << (AT ? (unsigned)AT->getKeyword() : 3)
+          << Deduced << DeducedDecl->getDeclName()
+          << DT->getDeducedType() << D->getDeclName()
+          << DeducedDecl->getInit()->getSourceRange()
+          << D->getInit()->getSourceRange();
+        D->setInvalidDecl();
+        break;
       }
     }
   }
@@ -11331,7 +11489,7 @@ ParmVarDecl *Sema::BuildParmVarDeclForTypedef(DeclContext *DC,
 void Sema::DiagnoseUnusedParameters(ArrayRef<ParmVarDecl *> Parameters) {
   // Don't diagnose unused-parameter errors in template instantiations; we
   // will already have done so in the template itself.
-  if (!ActiveTemplateInstantiations.empty())
+  if (inTemplateInstantiation())
     return;
 
   for (const ParmVarDecl *Parameter : Parameters) {
@@ -11549,8 +11707,6 @@ void
 Sema::CheckForFunctionRedefinition(FunctionDecl *FD,
                                    const FunctionDecl *EffectiveDefinition,
                                    SkipBodyInfo *SkipBody) {
-  // Don't complain if we're in GNU89 mode and the previous definition
-  // was an extern inline function.
   const FunctionDecl *Definition = EffectiveDefinition;
   if (!Definition)
     if (!FD->isDefined(Definition))
@@ -11635,9 +11791,6 @@ static void RebuildLambdaScopeInfo(CXXMethodDecl *CallOperator,
 
 Decl *Sema::ActOnStartOfFunctionDef(Scope *FnBodyScope, Decl *D,
                                     SkipBodyInfo *SkipBody) {
-  // Clear the last template instantiation error context.
-  LastTemplateInstantiationErrorContext = ActiveTemplateInstantiation();
-
   if (!D)
     return D;
   FunctionDecl *FD = nullptr;
@@ -11647,6 +11800,18 @@ Decl *Sema::ActOnStartOfFunctionDef(Scope *FnBodyScope, Decl *D,
   else
     FD = cast<FunctionDecl>(D);
 
+  // Check for defining attributes before the check for redefinition.
+  if (const auto *Attr = FD->getAttr<AliasAttr>()) {
+    Diag(Attr->getLocation(), diag::err_alias_is_definition) << FD << 0;
+    FD->dropAttr<AliasAttr>();
+    FD->setInvalidDecl();
+  }
+  if (const auto *Attr = FD->getAttr<IFuncAttr>()) {
+    Diag(Attr->getLocation(), diag::err_alias_is_definition) << FD << 1;
+    FD->dropAttr<IFuncAttr>();
+    FD->setInvalidDecl();
+  }
+
   // See if this is a redefinition.
   if (!FD->isLateTemplateParsed()) {
     CheckForFunctionRedefinition(FD, nullptr, SkipBody);
@@ -11671,14 +11836,14 @@ Decl *Sema::ActOnStartOfFunctionDef(Scope *FnBodyScope, Decl *D,
   // captures during transformation of nested lambdas, it is necessary to
   // have the LSI properly restored.
   if (isGenericLambdaCallOperatorSpecialization(FD)) {
-    assert(ActiveTemplateInstantiations.size() &&
-      "There should be an active template instantiation on the stack "
-      "when instantiating a generic lambda!");
+    assert(inTemplateInstantiation() &&
+           "There should be an active template instantiation on the stack "
+           "when instantiating a generic lambda!");
     RebuildLambdaScopeInfo(cast<CXXMethodDecl>(D), *this);
-  }
-  else
+  } else {
     // Enter a new function scope
     PushFunctionScope();
+  }
 
   // Builtin functions cannot be defined.
   if (unsigned BuiltinID = FD->getBuiltinID()) {
@@ -11793,7 +11958,7 @@ bool Sema::canDelayFunctionBody(const Declarator &D) {
 
   // We can't delay parsing the body of a function template with a deduced
   // return type (yet).
-  if (D.getDeclSpec().containsPlaceholderType()) {
+  if (D.getDeclSpec().hasAutoTypeSpec()) {
     // If the placeholder introduces a non-deduced trailing return type,
     // we can still delay parsing it.
     if (D.getNumTypeObjects()) {
@@ -11841,7 +12006,7 @@ Decl *Sema::ActOnFinishFunctionBody(Decl *dcl, Stmt *Body,
   sema::AnalysisBasedWarnings::Policy WP = AnalysisWarnings.getDefaultPolicy();
   sema::AnalysisBasedWarnings::Policy *ActivePolicy = nullptr;
 
-  if (getLangOpts().CoroutinesTS && !getCurFunction()->CoroutineStmts.empty())
+  if (getLangOpts().CoroutinesTS && getCurFunction()->CoroutinePromise)
     CheckCompletedCoroutineBody(FD, Body);
 
   if (FD) {
@@ -11962,7 +12127,7 @@ Decl *Sema::ActOnFinishFunctionBody(Decl *dcl, Stmt *Body,
           !LangOpts.CPlusPlus) {
         TypeSourceInfo *TI = FD->getTypeSourceInfo();
         TypeLoc TL = TI->getTypeLoc();
-        FunctionTypeLoc FTL = TL.castAs<FunctionTypeLoc>();
+        FunctionTypeLoc FTL = TL.getAsAdjusted<FunctionTypeLoc>();
         Diag(FTL.getLParenLoc(), diag::warn_strict_prototypes) << 1;
       }
     }
@@ -12555,7 +12720,7 @@ bool Sema::isAcceptableTagRedeclaration(const TagDecl *Previous,
     if (const CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Previous))
       isTemplate = Record->getDescribedClassTemplate();
 
-    if (!ActiveTemplateInstantiations.empty()) {
+    if (inTemplateInstantiation()) {
       // In a template instantiation, do not offer fix-its for tag mismatches
       // since they usually mess up the template instead of fixing the problem.
       Diag(NewTagLoc, diag::warn_struct_class_tag_mismatch)
@@ -12711,8 +12876,8 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
   bool ScopedEnum = ScopedEnumKWLoc.isValid();
 
-  // FIXME: Check explicit specializations more carefully.
-  bool isExplicitSpecialization = false;
+  // FIXME: Check member specializations more carefully.
+  bool isMemberSpecialization = false;
   bool Invalid = false;
 
   // We only need to do this matching if we have template parameters
@@ -12723,7 +12888,7 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
     if (TemplateParameterList *TemplateParams =
             MatchTemplateParametersToScopeSpecifier(
                 KWLoc, NameLoc, SS, nullptr, TemplateParameterLists,
-                TUK == TUK_Friend, isExplicitSpecialization, Invalid)) {
+                TUK == TUK_Friend, isMemberSpecialization, Invalid)) {
       if (Kind == TTK_Enum) {
         Diag(KWLoc, diag::err_enum_template);
         return nullptr;
@@ -12750,7 +12915,7 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
         // The "template<>" header is extraneous.
         Diag(TemplateParams->getTemplateLoc(), diag::err_template_tag_noparams)
           << TypeWithKeyword::getTagTypeKindName(Kind) << Name;
-        isExplicitSpecialization = true;
+        isMemberSpecialization = true;
       }
     }
   }
@@ -13070,7 +13235,7 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
     if (auto *Shadow = dyn_cast<UsingShadowDecl>(DirectPrevDecl)) {
       auto *OldTag = dyn_cast<TagDecl>(PrevDecl);
       if (SS.isEmpty() && TUK != TUK_Reference && TUK != TUK_Friend &&
-          isDeclInScope(Shadow, SearchDC, S, isExplicitSpecialization) &&
+          isDeclInScope(Shadow, SearchDC, S, isMemberSpecialization) &&
           !(OldTag && isAcceptableTagRedeclContext(
                           *this, OldTag->getDeclContext(), SearchDC))) {
         Diag(KWLoc, diag::err_using_decl_conflict_reverse);
@@ -13090,7 +13255,7 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
       // rementions the tag), reuse the decl.
       if (TUK == TUK_Reference || TUK == TUK_Friend ||
           isDeclInScope(DirectPrevDecl, SearchDC, S,
-                        SS.isNotEmpty() || isExplicitSpecialization)) {
+                        SS.isNotEmpty() || isMemberSpecialization)) {
         // Make sure that this wasn't declared as an enum and now used as a
         // struct or something similar.
         if (!isAcceptableTagRedeclaration(PrevTagDecl, Kind,
@@ -13195,7 +13360,7 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
               // is from an implicit instantiation, don't emit an error
               // here; we'll catch this in the general case below.
               bool IsExplicitSpecializationAfterInstantiation = false;
-              if (isExplicitSpecialization) {
+              if (isMemberSpecialization) {
                 if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Def))
                   IsExplicitSpecializationAfterInstantiation =
                     RD->getTemplateSpecializationKind() !=
@@ -13289,7 +13454,7 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
 
       // Otherwise, only diagnose if the declaration is in scope.
       } else if (!isDeclInScope(DirectPrevDecl, SearchDC, S,
-                                SS.isNotEmpty() || isExplicitSpecialization)) {
+                                SS.isNotEmpty() || isMemberSpecialization)) {
         // do nothing
 
       // Diagnose implicit declarations introduced by elaborated types.
@@ -13421,7 +13586,7 @@ CreateNewDecl:
       // for explicit specializations, because they have similar checking
       // (with more specific diagnostics) in the call to
       // CheckMemberSpecialization, below.
-      if (!isExplicitSpecialization &&
+      if (!isMemberSpecialization &&
           (TUK == TUK_Definition || TUK == TUK_Declaration) &&
           diagnoseQualifiedDeclaration(SS, DC, OrigName, Loc))
         Invalid = true;
@@ -13452,7 +13617,7 @@ CreateNewDecl:
   }
 
   if (ModulePrivateLoc.isValid()) {
-    if (isExplicitSpecialization)
+    if (isMemberSpecialization)
       Diag(New->getLocation(), diag::err_module_private_specialization)
         << 2
         << FixItHint::CreateRemoval(ModulePrivateLoc);
@@ -13465,7 +13630,7 @@ CreateNewDecl:
 
   // If this is a specialization of a member class (of a class template),
   // check the specialization.
-  if (isExplicitSpecialization && CheckMemberSpecialization(New, Previous))
+  if (isMemberSpecialization && CheckMemberSpecialization(New, Previous))
     Invalid = true;
 
   // If we're declaring or defining a tag in function prototype scope in C,
@@ -13489,9 +13654,6 @@ CreateNewDecl:
   if (Invalid)
     New->setInvalidDecl();
 
-  if (Attr)
-    ProcessDeclAttributeList(S, New, Attr);
-
   // Set the lexical context. If the tag has a C++ scope specifier, the
   // lexical context will be different from the semantic context.
   New->setLexicalDeclContext(CurContext);
@@ -13510,6 +13672,9 @@ CreateNewDecl:
   if (TUK == TUK_Definition)
     New->startDefinition();
 
+  if (Attr)
+    ProcessDeclAttributeList(S, New, Attr);
+
   // If this has an identifier, add it to the scope stack.
   if (TUK == TUK_Friend) {
     // We might be replacing an existing declaration in the lookup tables;
@@ -13632,8 +13797,9 @@ void Sema::ActOnTagFinishDefinition(Scope *S, Decl *TagD,
       RD->completeDefinition();
   }
 
-  if (isa<CXXRecordDecl>(Tag))
+  if (isa<CXXRecordDecl>(Tag)) {
     FieldCollector->FinishClass();
+  }
 
   // Exit this scope of this tag's definition.
   PopDeclContext();
@@ -14340,7 +14506,7 @@ void Sema::ActOnFields(Scope *S, SourceLocation RecLoc, Decl *EnclosingDecl,
   // Verify that all the fields are okay.
   SmallVector<FieldDecl*, 32> RecFields;
 
-  bool ARCErrReported = false;
+  bool ObjCFieldLifetimeErrReported = false;
   for (ArrayRef<Decl *>::iterator i = Fields.begin(), end = Fields.end();
        i != end; ++i) {
     FieldDecl *FD = cast<FieldDecl>(*i);
@@ -14475,16 +14641,16 @@ void Sema::ActOnFields(Scope *S, SourceLocation RecLoc, Decl *EnclosingDecl,
         << FixItHint::CreateInsertion(FD->getLocation(), "*");
       QualType T = Context.getObjCObjectPointerType(FD->getType());
       FD->setType(T);
-    } else if (getLangOpts().ObjCAutoRefCount && Record && !ARCErrReported &&
+    } else if (getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() &&
+               Record && !ObjCFieldLifetimeErrReported &&
                (!getLangOpts().CPlusPlus || Record->isUnion())) {
-      // It's an error in ARC if a field has lifetime.
+      // It's an error in ARC or Weak if a field has lifetime.
       // We don't want to report this in a system header, though,
       // so we just make the field unavailable.
       // FIXME: that's really not sufficient; we need to make the type
       // itself invalid to, say, initialize or copy.
       QualType T = FD->getType();
-      Qualifiers::ObjCLifetime lifetime = T.getObjCLifetime();
-      if (lifetime && lifetime != Qualifiers::OCL_ExplicitNone) {
+      if (T.hasNonTrivialObjCLifetime()) {
         SourceLocation loc = FD->getLocation();
         if (getSourceManager().isInSystemHeader(loc)) {
           if (!FD->hasAttr<UnavailableAttr>()) {
@@ -14495,7 +14661,7 @@ void Sema::ActOnFields(Scope *S, SourceLocation RecLoc, Decl *EnclosingDecl,
           Diag(FD->getLocation(), diag::err_arc_objc_object_in_tag)
             << T->isBlockPointerType() << Record->getTagKind();
         }
-        ARCErrReported = true;
+        ObjCFieldLifetimeErrReported = true;
       }
     } else if (getLangOpts().ObjC1 &&
                getLangOpts().getGC() != LangOptions::NonGC &&
@@ -15207,7 +15373,7 @@ static void CheckForDuplicateEnumValues(Sema &S, ArrayRef<Decl *> Elements,
 
 bool Sema::IsValueInFlagEnum(const EnumDecl *ED, const llvm::APInt &Val,
                              bool AllowMask) const {
-  assert(ED->hasAttr<FlagEnumAttr>() && "looking for value in non-flag enum");
+  assert(ED->isClosedFlag() && "looking for value in non-flag or open enum");
   assert(ED->isCompleteDefinition() && "expected enum definition");
 
   auto R = FlagBitsCache.insert(std::make_pair(ED, llvm::APInt()));
@@ -15452,7 +15618,7 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceRange BraceRange,
 
   CheckForDuplicateEnumValues(*this, Elements, Enum, EnumType);
 
-  if (Enum->hasAttr<FlagEnumAttr>()) {
+  if (Enum->isClosedFlag()) {
     for (Decl *D : Elements) {
       EnumConstantDecl *ECD = cast_or_null<EnumConstantDecl>(D);
       if (!ECD) continue;  // Already issued a diagnostic.
diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index c6a5bc74145c..a1ba9de368db 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -218,21 +218,45 @@ static bool checkAttributeAtMostNumArgs(Sema &S, const AttributeList &Attr,
                                    std::greater<unsigned>());
 }
 
+/// \brief A helper function to provide Attribute Location for the Attr types
+/// AND the AttributeList.
+template <typename AttrInfo>
+static typename std::enable_if<std::is_base_of<clang::Attr, AttrInfo>::value,
+                               SourceLocation>::type
+getAttrLoc(const AttrInfo &Attr) {
+  return Attr.getLocation();
+}
+static SourceLocation getAttrLoc(const clang::AttributeList &Attr) {
+  return Attr.getLoc();
+}
+
+/// \brief A helper function to provide Attribute Name for the Attr types
+/// AND the AttributeList.
+template <typename AttrInfo>
+static typename std::enable_if<std::is_base_of<clang::Attr, AttrInfo>::value,
+                               const AttrInfo *>::type
+getAttrName(const AttrInfo &Attr) {
+  return &Attr;
+}
+const IdentifierInfo *getAttrName(const clang::AttributeList &Attr) {
+  return Attr.getName();
+}
+
 /// \brief If Expr is a valid integer constant, get the value of the integer
 /// expression and return success or failure. May output an error.
-static bool checkUInt32Argument(Sema &S, const AttributeList &Attr,
-                                const Expr *Expr, uint32_t &Val,
-                                unsigned Idx = UINT_MAX) {
+template<typename AttrInfo>
+static bool checkUInt32Argument(Sema &S, const AttrInfo& Attr, const Expr *Expr,
+                                uint32_t &Val, unsigned Idx = UINT_MAX) {
   llvm::APSInt I(32);
   if (Expr->isTypeDependent() || Expr->isValueDependent() ||
       !Expr->isIntegerConstantExpr(I, S.Context)) {
     if (Idx != UINT_MAX)
-      S.Diag(Attr.getLoc(), diag::err_attribute_argument_n_type)
-        << Attr.getName() << Idx << AANT_ArgumentIntegerConstant
+      S.Diag(getAttrLoc(Attr), diag::err_attribute_argument_n_type)
+        << getAttrName(Attr) << Idx << AANT_ArgumentIntegerConstant
         << Expr->getSourceRange();
     else
-      S.Diag(Attr.getLoc(), diag::err_attribute_argument_type)
-        << Attr.getName() << AANT_ArgumentIntegerConstant
+      S.Diag(getAttrLoc(Attr), diag::err_attribute_argument_type)
+        << getAttrName(Attr) << AANT_ArgumentIntegerConstant
         << Expr->getSourceRange();
     return false;
   }
@@ -250,9 +274,9 @@ static bool checkUInt32Argument(Sema &S, const AttributeList &Attr,
 /// \brief Wrapper around checkUInt32Argument, with an extra check to be sure
 /// that the result will fit into a regular (signed) int. All args have the same
 /// purpose as they do in checkUInt32Argument.
-static bool checkPositiveIntArgument(Sema &S, const AttributeList &Attr,
-                                     const Expr *Expr, int &Val,
-                                     unsigned Idx = UINT_MAX) {
+template<typename AttrInfo>
+static bool checkPositiveIntArgument(Sema &S, const AttrInfo& Attr, const Expr *Expr,
+                                     int &Val, unsigned Idx = UINT_MAX) {
   uint32_t UVal;
   if (!checkUInt32Argument(S, Attr, Expr, UVal, Idx))
     return false;
@@ -287,11 +311,10 @@ static bool checkAttrMutualExclusion(Sema &S, Decl *D, SourceRange Range,
 /// instance method D.  May output an error.
 ///
 /// \returns true if IdxExpr is a valid index.
-static bool checkFunctionOrMethodParameterIndex(Sema &S, const Decl *D,
-                                                const AttributeList &Attr,
-                                                unsigned AttrArgNum,
-                                                const Expr *IdxExpr,
-                                                uint64_t &Idx) {
+template <typename AttrInfo>
+static bool checkFunctionOrMethodParameterIndex(
+    Sema &S, const Decl *D, const AttrInfo& Attr,
+    unsigned AttrArgNum, const Expr *IdxExpr, uint64_t &Idx) {
   assert(isFunctionOrMethodOrBlock(D));
 
   // In C++ the implicit 'this' function parameter also counts.
@@ -305,24 +328,24 @@ static bool checkFunctionOrMethodParameterIndex(Sema &S, const Decl *D,
   llvm::APSInt IdxInt;
   if (IdxExpr->isTypeDependent() || IdxExpr->isValueDependent() ||
       !IdxExpr->isIntegerConstantExpr(IdxInt, S.Context)) {
-    S.Diag(Attr.getLoc(), diag::err_attribute_argument_n_type)
-      << Attr.getName() << AttrArgNum << AANT_ArgumentIntegerConstant
+    S.Diag(getAttrLoc(Attr), diag::err_attribute_argument_n_type)
+      << getAttrName(Attr) << AttrArgNum << AANT_ArgumentIntegerConstant
       << IdxExpr->getSourceRange();
     return false;
   }
 
   Idx = IdxInt.getLimitedValue();
   if (Idx < 1 || (!IV && Idx > NumParams)) {
-    S.Diag(Attr.getLoc(), diag::err_attribute_argument_out_of_bounds)
-      << Attr.getName() << AttrArgNum << IdxExpr->getSourceRange();
+    S.Diag(getAttrLoc(Attr), diag::err_attribute_argument_out_of_bounds)
+      << getAttrName(Attr) << AttrArgNum << IdxExpr->getSourceRange();
     return false;
   }
   Idx--; // Convert to zero-based.
   if (HasImplicitThisParam) {
     if (Idx == 0) {
-      S.Diag(Attr.getLoc(),
+      S.Diag(getAttrLoc(Attr),
              diag::err_attribute_invalid_implicit_this_argument)
-        << Attr.getName() << IdxExpr->getSourceRange();
+        << getAttrName(Attr) << IdxExpr->getSourceRange();
       return false;
     }
     --Idx;
@@ -753,31 +776,48 @@ static void handleAssertExclusiveLockAttr(Sema &S, Decl *D,
                                      Attr.getAttributeSpellingListIndex()));
 }
 
-/// \brief Checks to be sure that the given parameter number is inbounds, and is
-/// an some integral type. Will emit appropriate diagnostics if this returns
+/// \brief Checks to be sure that the given parameter number is in bounds, and is
+/// an integral type. Will emit appropriate diagnostics if this returns
 /// false.
 ///
 /// FuncParamNo is expected to be from the user, so is base-1. AttrArgNo is used
 /// to actually retrieve the argument, so it's base-0.
+template <typename AttrInfo>
 static bool checkParamIsIntegerType(Sema &S, const FunctionDecl *FD,
-                                    const AttributeList &Attr,
-                                    unsigned FuncParamNo, unsigned AttrArgNo) {
-  assert(Attr.isArgExpr(AttrArgNo) && "Expected expression argument");
+                                    const AttrInfo &Attr, Expr *AttrArg,
+                                    unsigned FuncParamNo, unsigned AttrArgNo,
+                                    bool AllowDependentType = false) {
   uint64_t Idx;
-  if (!checkFunctionOrMethodParameterIndex(S, FD, Attr, FuncParamNo,
-                                           Attr.getArgAsExpr(AttrArgNo), Idx))
+  if (!checkFunctionOrMethodParameterIndex(S, FD, Attr, FuncParamNo, AttrArg,
+                                           Idx))
     return false;
 
   const ParmVarDecl *Param = FD->getParamDecl(Idx);
+  if (AllowDependentType && Param->getType()->isDependentType())
+    return true;
   if (!Param->getType()->isIntegerType() && !Param->getType()->isCharType()) {
-    SourceLocation SrcLoc = Attr.getArgAsExpr(AttrArgNo)->getLocStart();
+    SourceLocation SrcLoc = AttrArg->getLocStart();
     S.Diag(SrcLoc, diag::err_attribute_integers_only)
-        << Attr.getName() << Param->getSourceRange();
+        << getAttrName(Attr) << Param->getSourceRange();
     return false;
   }
   return true;
 }
 
+/// \brief Checks to be sure that the given parameter number is in bounds, and is
+/// an integral type. Will emit appropriate diagnostics if this returns false.
+///
+/// FuncParamNo is expected to be from the user, so is base-1. AttrArgNo is used
+/// to actually retrieve the argument, so it's base-0.
+static bool checkParamIsIntegerType(Sema &S, const FunctionDecl *FD,
+                                    const AttributeList &Attr,
+                                    unsigned FuncParamNo, unsigned AttrArgNo,
+                                    bool AllowDependentType = false) {
+  assert(Attr.isArgExpr(AttrArgNo) && "Expected expression argument");
+  return checkParamIsIntegerType(S, FD, Attr, Attr.getArgAsExpr(AttrArgNo),
+                                 FuncParamNo, AttrArgNo, AllowDependentType);
+}
+
 static void handleAllocSizeAttr(Sema &S, Decl *D, const AttributeList &Attr) {
   if (!checkAttributeAtLeastNumArgs(S, Attr, 1) ||
       !checkAttributeAtMostNumArgs(S, Attr, 2))
@@ -792,7 +832,7 @@ static void handleAllocSizeAttr(Sema &S, Decl *D, const AttributeList &Attr) {
 
   const Expr *SizeExpr = Attr.getArgAsExpr(0);
   int SizeArgNo;
-  // Paramater indices are 1-indexed, hence Index=1
+  // Parameter indices are 1-indexed, hence Index=1
   if (!checkPositiveIntArgument(S, Attr, SizeExpr, SizeArgNo, /*Index=*/1))
     return;
 
@@ -803,7 +843,7 @@ static void handleAllocSizeAttr(Sema &S, Decl *D, const AttributeList &Attr) {
   int NumberArgNo = 0;
   if (Attr.getNumArgs() == 2) {
     const Expr *NumberExpr = Attr.getArgAsExpr(1);
-    // Paramater indices are 1-based, hence Index=2
+    // Parameter indices are 1-based, hence Index=2
     if (!checkPositiveIntArgument(S, Attr, NumberExpr, NumberArgNo,
                                   /*Index=*/2))
       return;
@@ -1420,7 +1460,7 @@ static void handleNonNullAttr(Sema &S, Decl *D, const AttributeList &Attr) {
   // check if the attribute came from a macro expansion or a template
   // instantiation.
   if (NonNullArgs.empty() && Attr.getLoc().isFileID() &&
-      S.ActiveTemplateInstantiations.empty()) {
+      !S.inTemplateInstantiation()) {
     bool AnyPointers = isFunctionOrMethodVariadic(D);
     for (unsigned I = 0, E = getFunctionOrMethodNumParams(D);
          I != E && !AnyPointers; ++I) {
@@ -1484,6 +1524,12 @@ static void handleAssumeAlignedAttr(Sema &S, Decl *D,
                          Attr.getAttributeSpellingListIndex());
 }
 
+static void handleAllocAlignAttr(Sema &S, Decl *D,
+                                   const AttributeList &Attr) {
+  S.AddAllocAlignAttr(Attr.getRange(), D, Attr.getArgAsExpr(0),
+                      Attr.getAttributeSpellingListIndex());
+}
+
 void Sema::AddAssumeAlignedAttr(SourceRange AttrRange, Decl *D, Expr *E,
                                 Expr *OE, unsigned SpellingListIndex) {
   QualType ResultType = getFunctionOrMethodResultType(D);
@@ -1535,6 +1581,44 @@ void Sema::AddAssumeAlignedAttr(SourceRange AttrRange, Decl *D, Expr *E,
             AssumeAlignedAttr(AttrRange, Context, E, OE, SpellingListIndex));
 }
 
+void Sema::AddAllocAlignAttr(SourceRange AttrRange, Decl *D, Expr *ParamExpr,
+                             unsigned SpellingListIndex) {
+  QualType ResultType = getFunctionOrMethodResultType(D);
+
+  AllocAlignAttr TmpAttr(AttrRange, Context, 0, SpellingListIndex);
+  SourceLocation AttrLoc = AttrRange.getBegin();
+
+  if (!ResultType->isDependentType() &&
+      !isValidPointerAttrType(ResultType, /* RefOkay */ true)) {
+    Diag(AttrLoc, diag::warn_attribute_return_pointers_refs_only)
+        << &TmpAttr << AttrRange << getFunctionOrMethodResultSourceRange(D);
+    return;
+  }
+
+  uint64_t IndexVal;
+  const auto *FuncDecl = cast<FunctionDecl>(D);
+  if (!checkFunctionOrMethodParameterIndex(*this, FuncDecl, TmpAttr,
+                                           /*AttrArgNo=*/1, ParamExpr,
+                                           IndexVal))
+    return;
+
+  QualType Ty = getFunctionOrMethodParamType(D, IndexVal);
+  if (!Ty->isDependentType() && !Ty->isIntegralType(Context)) {
+    Diag(ParamExpr->getLocStart(), diag::err_attribute_integers_only)
+        << &TmpAttr << FuncDecl->getParamDecl(IndexVal)->getSourceRange();
+    return;
+  }
+
+  // We cannot use the Idx returned from checkFunctionOrMethodParameterIndex
+  // because that has corrected for the implicit this parameter, and is zero-
+  // based.  The attribute expects what the user wrote explicitly.
+  llvm::APSInt Val;
+  ParamExpr->EvaluateAsInt(Val, Context);
+
+  D->addAttr(::new (Context) AllocAlignAttr(
+      AttrRange, Context, Val.getZExtValue(), SpellingListIndex));
+}
+
 /// Normalize the attribute, __foo__ becomes foo.
 /// Returns true if normalization was applied.
 static bool normalizeName(StringRef &AttrName) {
@@ -1839,6 +1923,17 @@ static void handleNakedAttr(Sema &S, Decl *D, const AttributeList &Attr) {
                                                      Attr.getName()))
     return;
 
+  if (Attr.isDeclspecAttribute()) {
+    const auto &Triple = S.getASTContext().getTargetInfo().getTriple();
+    const auto &Arch = Triple.getArch();
+    if (Arch != llvm::Triple::x86 &&
+        (Arch != llvm::Triple::arm && Arch != llvm::Triple::thumb)) {
+      S.Diag(Attr.getLoc(), diag::err_attribute_not_supported_on_arch)
+          << Attr.getName() << Triple.getArchName();
+      return;
+    }
+  }
+
   D->addAttr(::new (S.Context) NakedAttr(Attr.getRange(), S.Context,
                                          Attr.getAttributeSpellingListIndex()));
 }
@@ -2409,6 +2504,32 @@ static void handleAvailabilityAttr(Sema &S, Decl *D,
   }
 }
 
+static void handleExternalSourceSymbolAttr(Sema &S, Decl *D,
+                                           const AttributeList &Attr) {
+  if (!checkAttributeAtLeastNumArgs(S, Attr, 1))
+    return;
+  assert(checkAttributeAtMostNumArgs(S, Attr, 3) &&
+         "Invalid number of arguments in an external_source_symbol attribute");
+
+  if (!isa<NamedDecl>(D)) {
+    S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
+        << Attr.getName() << ExpectedNamedDecl;
+    return;
+  }
+
+  StringRef Language;
+  if (const auto *SE = dyn_cast_or_null<StringLiteral>(Attr.getArgAsExpr(0)))
+    Language = SE->getString();
+  StringRef DefinedIn;
+  if (const auto *SE = dyn_cast_or_null<StringLiteral>(Attr.getArgAsExpr(1)))
+    DefinedIn = SE->getString();
+  bool IsGeneratedDeclaration = Attr.getArgAsIdent(2) != nullptr;
+
+  D->addAttr(::new (S.Context) ExternalSourceSymbolAttr(
+      Attr.getRange(), S.Context, Language, DefinedIn, IsGeneratedDeclaration,
+      Attr.getAttributeSpellingListIndex()));
+}
+
 template <class T>
 static T *mergeVisibilityAttr(Sema &S, Decl *D, SourceRange range,
                               typename T::VisibilityType value,
@@ -2917,6 +3038,28 @@ static void handleCleanupAttr(Sema &S, Decl *D, const AttributeList &Attr) {
                          Attr.getAttributeSpellingListIndex()));
 }
 
+static void handleEnumExtensibilityAttr(Sema &S, Decl *D,
+                                        const AttributeList &Attr) {
+  if (!Attr.isArgIdent(0)) {
+    S.Diag(Attr.getLoc(), diag::err_attribute_argument_n_type)
+        << Attr.getName() << 0 << AANT_ArgumentIdentifier;
+    return;
+  }
+
+  EnumExtensibilityAttr::Kind ExtensibilityKind;
+  IdentifierInfo *II = Attr.getArgAsIdent(0)->Ident;
+  if (!EnumExtensibilityAttr::ConvertStrToKind(II->getName(),
+                                               ExtensibilityKind)) {
+    S.Diag(Attr.getLoc(), diag::warn_attribute_type_not_supported)
+        << Attr.getName() << II;
+    return;
+  }
+
+  D->addAttr(::new (S.Context) EnumExtensibilityAttr(
+      Attr.getRange(), S.Context, ExtensibilityKind,
+      Attr.getAttributeSpellingListIndex()));
+}
+
 /// Handle __attribute__((format_arg((idx)))) attribute based on
 /// http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
 static void handleFormatArgAttr(Sema &S, Decl *D, const AttributeList &Attr) {
@@ -3193,8 +3336,9 @@ static void handleTransparentUnionAttr(Sema &S, Decl *D,
   }
 
   if (!RD->isCompleteDefinition()) {
-    S.Diag(Attr.getLoc(),
-        diag::warn_transparent_union_attribute_not_definition);
+    if (!RD->isBeingDefined())
+      S.Diag(Attr.getLoc(),
+             diag::warn_transparent_union_attribute_not_definition);
     return;
   }
 
@@ -4048,6 +4192,26 @@ static void handleCallConvAttr(Sema &S, Decl *D, const AttributeList &Attr) {
   }
 }
 
+static void handleSuppressAttr(Sema &S, Decl *D, const AttributeList &Attr) {
+  if (!checkAttributeAtLeastNumArgs(S, Attr, 1))
+    return;
+
+  std::vector<StringRef> DiagnosticIdentifiers;
+  for (unsigned I = 0, E = Attr.getNumArgs(); I != E; ++I) {
+    StringRef RuleName;
+
+    if (!S.checkStringLiteralArgumentAttr(Attr, I, RuleName, nullptr))
+      return;
+
+    // FIXME: Warn if the rule name is unknown. This is tricky because only
+    // clang-tidy knows about available rules.
+    DiagnosticIdentifiers.push_back(RuleName);
+  }
+  D->addAttr(::new (S.Context) SuppressAttr(
+      Attr.getRange(), S.Context, DiagnosticIdentifiers.data(),
+      DiagnosticIdentifiers.size(), Attr.getAttributeSpellingListIndex()));
+}
+
 bool Sema::CheckCallingConvAttr(const AttributeList &attr, CallingConv &CC, 
                                 const FunctionDecl *FD) {
   if (attr.isInvalid())
@@ -4397,6 +4561,19 @@ static void handleTypeTagForDatatypeAttr(Sema &S, Decl *D,
                                     Attr.getAttributeSpellingListIndex()));
 }
 
+static void handleXRayLogArgsAttr(Sema &S, Decl *D,
+                                  const AttributeList &Attr) {
+  uint64_t ArgCount;
+  if (!checkFunctionOrMethodParameterIndex(S, D, Attr, 1, Attr.getArgAsExpr(0),
+                                           ArgCount))
+    return;
+
+  // ArgCount isn't a parameter index [0;n), it's a count [1;n] - hence + 1.
+  D->addAttr(::new (S.Context)
+             XRayLogArgsAttr(Attr.getRange(), S.Context, ++ArgCount,
+             Attr.getAttributeSpellingListIndex()));
+}
+
 //===----------------------------------------------------------------------===//
 // Checker-specific attribute handlers.
 //===----------------------------------------------------------------------===//
@@ -5126,6 +5303,32 @@ static void handleAnyX86InterruptAttr(Sema &S, Decl *D,
   D->addAttr(UsedAttr::CreateImplicit(S.Context));
 }
 
+static void handleAVRInterruptAttr(Sema &S, Decl *D, const AttributeList &Attr) {
+  if (!isFunctionOrMethod(D)) {
+    S.Diag(D->getLocation(), diag::warn_attribute_wrong_decl_type)
+        << "'interrupt'" << ExpectedFunction;
+    return;
+  }
+
+  if (!checkAttributeNumArgs(S, Attr, 0))
+    return;
+
+  handleSimpleAttribute<AVRInterruptAttr>(S, D, Attr);
+}
+
+static void handleAVRSignalAttr(Sema &S, Decl *D, const AttributeList &Attr) {
+  if (!isFunctionOrMethod(D)) {
+    S.Diag(D->getLocation(), diag::warn_attribute_wrong_decl_type)
+        << "'signal'" << ExpectedFunction;
+    return;
+  }
+
+  if (!checkAttributeNumArgs(S, Attr, 0))
+    return;
+
+  handleSimpleAttribute<AVRSignalAttr>(S, D, Attr);
+}
+
 static void handleInterruptAttr(Sema &S, Decl *D, const AttributeList &Attr) {
   // Dispatch the interrupt attribute based on the current target.
   switch (S.Context.getTargetInfo().getTriple().getArch()) {
@@ -5140,6 +5343,9 @@ static void handleInterruptAttr(Sema &S, Decl *D, const AttributeList &Attr) {
   case llvm::Triple::x86_64:
     handleAnyX86InterruptAttr(S, D, Attr);
     break;
+  case llvm::Triple::avr:
+    handleAVRInterruptAttr(S, D, Attr);
+    break;
   default:
     handleARMInterruptAttr(S, D, Attr);
     break;
@@ -5700,6 +5906,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_AMDGPUNumVGPR:
     handleAMDGPUNumVGPRAttr(S, D, Attr);
     break;
+  case AttributeList::AT_AVRSignal:
+    handleAVRSignalAttr(S, D, Attr);
+    break;
   case AttributeList::AT_IBAction:
     handleSimpleAttribute<IBActionAttr>(S, D, Attr);
     break;
@@ -5772,6 +5981,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_ExtVectorType:
     handleExtVectorTypeAttr(S, scope, D, Attr);
     break;
+  case AttributeList::AT_ExternalSourceSymbol:
+    handleExternalSourceSymbolAttr(S, D, Attr);
+    break;
   case AttributeList::AT_MinSize:
     handleMinSizeAttr(S, D, Attr);
     break;
@@ -5781,6 +5993,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_FlagEnum:
     handleSimpleAttribute<FlagEnumAttr>(S, D, Attr);
     break;
+  case AttributeList::AT_EnumExtensibility:
+    handleEnumExtensibilityAttr(S, D, Attr);
+    break;
   case AttributeList::AT_Flatten:
     handleSimpleAttribute<FlattenAttr>(S, D, Attr);
     break;
@@ -5837,6 +6052,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_AssumeAligned:
     handleAssumeAlignedAttr(S, D, Attr);
     break;
+  case AttributeList::AT_AllocAlign:
+    handleAllocAlignAttr(S, D, Attr);
+    break;
   case AttributeList::AT_Overloadable:
     handleSimpleAttribute<OverloadableAttr>(S, D, Attr);
     break;
@@ -6056,6 +6274,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_PreserveAll:
     handleCallConvAttr(S, D, Attr);
     break;
+  case AttributeList::AT_Suppress:
+    handleSuppressAttr(S, D, Attr);
+    break;
   case AttributeList::AT_OpenCLKernel:
     handleSimpleAttribute<OpenCLKernelAttr>(S, D, Attr);
     break;
@@ -6223,6 +6444,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_XRayInstrument:
     handleSimpleAttribute<XRayInstrumentAttr>(S, D, Attr);
     break;
+  case AttributeList::AT_XRayLogArgs:
+    handleXRayLogArgsAttr(S, D, Attr);
+    break;
   }
 }
 
@@ -6282,6 +6506,15 @@ void Sema::ProcessDeclAttributeList(Scope *S, Decl *D,
   }
 }
 
+// Helper for delayed proccessing TransparentUnion attribute.
+void Sema::ProcessDeclAttributeDelayed(Decl *D, const AttributeList *AttrList) {
+  for (const AttributeList *Attr = AttrList; Attr; Attr = Attr->getNext())
+    if (Attr->getKind() == AttributeList::AT_TransparentUnion) {
+      handleTransparentUnionAttr(*this, D, *Attr);
+      break;
+    }
+}
+
 // Annotation attributes are the only attributes allowed after an access
 // specifier.
 bool Sema::ProcessAccessDeclAttributeList(AccessSpecDecl *ASDecl,
@@ -6611,6 +6844,7 @@ static void DoEmitAvailabilityWarning(Sema &S, AvailabilityResult K,
   // Diagnostics for deprecated or unavailable.
   unsigned diag, diag_message, diag_fwdclass_message;
   unsigned diag_available_here = diag::note_availability_specified_here;
+  SourceLocation NoteLocation = D->getLocation();
 
   // Matches 'diag::note_property_attribute' options.
   unsigned property_note_select;
@@ -6633,6 +6867,8 @@ static void DoEmitAvailabilityWarning(Sema &S, AvailabilityResult K,
     diag_fwdclass_message = diag::warn_deprecated_fwdclass_message;
     property_note_select = /* deprecated */ 0;
     available_here_select_kind = /* deprecated */ 2;
+    if (const auto *attr = D->getAttr<DeprecatedAttr>())
+      NoteLocation = attr->getLocation();
     break;
 
   case AR_Unavailable:
@@ -6751,7 +6987,7 @@ static void DoEmitAvailabilityWarning(Sema &S, AvailabilityResult K,
     }
   }
   else
-    S.Diag(D->getLocation(), diag_available_here)
+    S.Diag(NoteLocation, diag_available_here)
         << D << available_here_select_kind;
 
   if (K == AR_NotYetIntroduced)
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index f265f4c00f71..fd3f266c9a08 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -467,7 +467,7 @@ bool Sema::MergeCXXFunctionDecl(FunctionDecl *New, FunctionDecl *Old,
       // If only one of these is a local function declaration, then they are
       // declared in different scopes, even though isDeclInScope may think
       // they're in the same scope. (If both are local, the scope check is
-      // sufficent, and if neither is local, then they are in the same scope.)
+      // sufficient, and if neither is local, then they are in the same scope.)
       continue;
     }
 
@@ -647,6 +647,17 @@ bool Sema::MergeCXXFunctionDecl(FunctionDecl *New, FunctionDecl *Old,
     Invalid = true;
   }
 
+  // FIXME: It's not clear what should happen if multiple declarations of a
+  // deduction guide have different explicitness. For now at least we simply
+  // reject any case where the explicitness changes.
+  auto *NewGuide = dyn_cast<CXXDeductionGuideDecl>(New);
+  if (NewGuide && NewGuide->isExplicitSpecified() !=
+                      cast<CXXDeductionGuideDecl>(Old)->isExplicitSpecified()) {
+    Diag(New->getLocation(), diag::err_deduction_guide_explicit_mismatch)
+      << NewGuide->isExplicitSpecified();
+    Diag(Old->getLocation(), diag::note_previous_declaration);
+  }
+
   // C++11 [dcl.fct.default]p4: If a friend declaration specifies a default
   // argument expression, that declaration shall be a definition and shall be
   // the only declaration of the function or function template in the
@@ -970,7 +981,8 @@ namespace { enum class IsTupleLike { TupleLike, NotTupleLike, Error }; }
 
 static IsTupleLike isTupleLike(Sema &S, SourceLocation Loc, QualType T,
                                llvm::APSInt &Size) {
-  EnterExpressionEvaluationContext ContextRAII(S, Sema::ConstantEvaluated);
+  EnterExpressionEvaluationContext ContextRAII(
+      S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   DeclarationName Value = S.PP.getIdentifierInfo("value");
   LookupResult R(S, Value, Loc, Sema::LookupOrdinaryName);
@@ -2705,8 +2717,7 @@ void Sema::DiagnoseAbsenceOfOverrideControl(NamedDecl *D) {
   if (D->isInvalidDecl() || D->hasAttr<OverrideAttr>())
     return;
   CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(D);
-  if (!MD || MD->isImplicit() || MD->hasAttr<FinalAttr>() ||
-      isa<CXXDestructorDecl>(MD))
+  if (!MD || MD->isImplicit() || MD->hasAttr<FinalAttr>())
     return;
 
   SourceLocation Loc = MD->getLocation();
@@ -2716,10 +2727,12 @@ void Sema::DiagnoseAbsenceOfOverrideControl(NamedDecl *D) {
   SpellingLoc = getSourceManager().getSpellingLoc(SpellingLoc);
   if (SpellingLoc.isValid() && getSourceManager().isInSystemHeader(SpellingLoc))
       return;
-    
+
   if (MD->size_overridden_methods() > 0) {
-    Diag(MD->getLocation(), diag::warn_function_marked_not_override_overriding)
-      << MD->getDeclName();
+    unsigned DiagID = isa<CXXDestructorDecl>(MD)
+                          ? diag::warn_destructor_marked_not_override_overriding
+                          : diag::warn_function_marked_not_override_overriding;
+    Diag(MD->getLocation(), DiagID) << MD->getDeclName();
     const CXXMethodDecl *OMD = *MD->begin_overridden_methods();
     Diag(OMD->getLocation(), diag::note_overridden_virtual_function);
   }
@@ -2758,6 +2771,56 @@ static AttributeList *getMSPropertyAttr(AttributeList *list) {
   return nullptr;
 }
 
+// Check if there is a field shadowing.
+void Sema::CheckShadowInheritedFields(const SourceLocation &Loc,
+                                      DeclarationName FieldName,
+                                      const CXXRecordDecl *RD) {
+  if (Diags.isIgnored(diag::warn_shadow_field, Loc))
+    return;
+
+  // To record a shadowed field in a base
+  std::map<CXXRecordDecl*, NamedDecl*> Bases;
+  auto FieldShadowed = [&](const CXXBaseSpecifier *Specifier,
+                           CXXBasePath &Path) {
+    const auto Base = Specifier->getType()->getAsCXXRecordDecl();
+    // Record an ambiguous path directly
+    if (Bases.find(Base) != Bases.end())
+      return true;
+    for (const auto Field : Base->lookup(FieldName)) {
+      if ((isa<FieldDecl>(Field) || isa<IndirectFieldDecl>(Field)) &&
+          Field->getAccess() != AS_private) {
+        assert(Field->getAccess() != AS_none);
+        assert(Bases.find(Base) == Bases.end());
+        Bases[Base] = Field;
+        return true;
+      }
+    }
+    return false;
+  };
+
+  CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
+                     /*DetectVirtual=*/true);
+  if (!RD->lookupInBases(FieldShadowed, Paths))
+    return;
+
+  for (const auto &P : Paths) {
+    auto Base = P.back().Base->getType()->getAsCXXRecordDecl();
+    auto It = Bases.find(Base);
+    // Skip duplicated bases
+    if (It == Bases.end())
+      continue;
+    auto BaseField = It->second;
+    assert(BaseField->getAccess() != AS_private);
+    if (AS_none !=
+        CXXRecordDecl::MergeAccess(P.Access, BaseField->getAccess())) {
+      Diag(Loc, diag::warn_shadow_field)
+        << FieldName.getAsString() << RD->getName() << Base->getName();
+      Diag(BaseField->getLocation(), diag::note_shadow_field);
+      Bases.erase(It);
+    }
+  }
+}
+
 /// ActOnCXXMemberDeclarator - This is invoked when a C++ class member
 /// declarator is parsed. 'AS' is the access specifier, 'BW' specifies the
 /// bitfield width if there is one, 'InitExpr' specifies the initializer if
@@ -2957,6 +3020,8 @@ Sema::ActOnCXXMemberDeclarator(Scope *S, AccessSpecifier AS, Declarator &D,
       if (!Member)
         return nullptr;
     }
+
+    CheckShadowInheritedFields(Loc, Name, cast<CXXRecordDecl>(CurContext));
   } else {
     Member = HandleDeclarator(S, D, TemplateParameterLists);
     if (!Member)
@@ -3673,6 +3738,9 @@ Sema::BuildMemInitializer(Decl *ConstructorD,
     BaseType = GetTypeFromParser(TemplateTypeTy, &TInfo);
   } else if (DS.getTypeSpecType() == TST_decltype) {
     BaseType = BuildDecltypeType(DS.getRepAsExpr(), DS.getTypeSpecTypeLoc());
+  } else if (DS.getTypeSpecType() == TST_decltype_auto) {
+    Diag(DS.getTypeSpecTypeLoc(), diag::err_decltype_auto_invalid);
+    return true;
   } else {
     LookupResult R(*this, MemberOrBase, IdLoc, LookupOrdinaryName);
     LookupParsedName(R, S, &SS);
@@ -4332,11 +4400,8 @@ BuildImplicitMemberInitializer(Sema &SemaRef, CXXConstructorDecl *Constructor,
     }
   }
   
-  if (SemaRef.getLangOpts().ObjCAutoRefCount &&
-      FieldBaseElementType->isObjCRetainableType() &&
-      FieldBaseElementType.getObjCLifetime() != Qualifiers::OCL_None &&
-      FieldBaseElementType.getObjCLifetime() != Qualifiers::OCL_ExplicitNone) {
-    // ARC:
+  if (FieldBaseElementType.hasNonTrivialObjCLifetime()) {
+    // ARC and Weak:
     //   Default-initialize Objective-C pointers to NULL.
     CXXMemberInit
       = new (SemaRef.Context) CXXCtorInitializer(SemaRef.Context, Field, 
@@ -5015,6 +5080,10 @@ Sema::MarkBaseAndMemberDestructorsReferenced(SourceLocation Location,
     DiagnoseUseOfDecl(Dtor, Location);
   }
 
+  // We only potentially invoke the destructors of potentially constructed
+  // subobjects.
+  bool VisitVirtualBases = !ClassDecl->isAbstract();
+
   llvm::SmallPtrSet<const RecordType *, 8> DirectVirtualBases;
 
   // Bases.
@@ -5023,8 +5092,11 @@ Sema::MarkBaseAndMemberDestructorsReferenced(SourceLocation Location,
     const RecordType *RT = Base.getType()->getAs<RecordType>();
 
     // Remember direct virtual bases.
-    if (Base.isVirtual())
+    if (Base.isVirtual()) {
+      if (!VisitVirtualBases)
+        continue;
       DirectVirtualBases.insert(RT);
+    }
 
     CXXRecordDecl *BaseClassDecl = cast<CXXRecordDecl>(RT->getDecl());
     // If our base class is invalid, we probably can't get its dtor anyway.
@@ -5046,6 +5118,9 @@ Sema::MarkBaseAndMemberDestructorsReferenced(SourceLocation Location,
     MarkFunctionReferenced(Location, Dtor);
     DiagnoseUseOfDecl(Dtor, Location);
   }
+
+  if (!VisitVirtualBases)
+    return;
   
   // Virtual bases.
   for (const auto &VBase : ClassDecl->vbases()) {
@@ -5378,7 +5453,7 @@ static void ReferenceDllExportedMethods(Sema &S, CXXRecordDecl *Class) {
         // Synthesize and instantiate non-trivial implicit methods, explicitly
         // defaulted methods, and the copy and move assignment operators. The
         // latter are exported even if they are trivial, because the address of
-        // an operator can be taken and should compare equal accross libraries.
+        // an operator can be taken and should compare equal across libraries.
         DiagnosticErrorTrap Trap(S.Diags);
         S.MarkFunctionReferenced(Class->getLocation(), MD);
         if (Trap.hasErrorOccurred()) {
@@ -5786,7 +5861,7 @@ void Sema::CheckCompletedCXXClass(CXXRecordDecl *Record) {
 /// \param ConstRHS True if this is a copy operation with a const object
 ///        on its RHS, that is, if the argument to the outer special member
 ///        function is 'const' and this is not a field marked 'mutable'.
-static Sema::SpecialMemberOverloadResult *lookupCallFromSpecialMember(
+static Sema::SpecialMemberOverloadResult lookupCallFromSpecialMember(
     Sema &S, CXXRecordDecl *Class, Sema::CXXSpecialMember CSM,
     unsigned FieldQuals, bool ConstRHS) {
   unsigned LHSQuals = 0;
@@ -5909,13 +5984,13 @@ specialMemberIsConstexpr(Sema &S, CXXRecordDecl *ClassDecl,
   if (CSM == Sema::CXXDefaultConstructor)
     return ClassDecl->hasConstexprDefaultConstructor();
 
-  Sema::SpecialMemberOverloadResult *SMOR =
+  Sema::SpecialMemberOverloadResult SMOR =
       lookupCallFromSpecialMember(S, ClassDecl, CSM, Quals, ConstRHS);
-  if (!SMOR || !SMOR->getMethod())
+  if (!SMOR.getMethod())
     // A constructor we wouldn't select can't be "involved in initializing"
     // anything.
     return true;
-  return SMOR->getMethod()->isConstexpr();
+  return SMOR.getMethod()->isConstexpr();
 }
 
 /// Determine whether the specified special member function would be constexpr
@@ -6025,27 +6100,23 @@ static bool defaultedSpecialMemberIsConstexpr(
 }
 
 static Sema::ImplicitExceptionSpecification
+ComputeDefaultedSpecialMemberExceptionSpec(
+    Sema &S, SourceLocation Loc, CXXMethodDecl *MD, Sema::CXXSpecialMember CSM,
+    Sema::InheritedConstructorInfo *ICI);
+
+static Sema::ImplicitExceptionSpecification
 computeImplicitExceptionSpec(Sema &S, SourceLocation Loc, CXXMethodDecl *MD) {
-  switch (S.getSpecialMember(MD)) {
-  case Sema::CXXDefaultConstructor:
-    return S.ComputeDefaultedDefaultCtorExceptionSpec(Loc, MD);
-  case Sema::CXXCopyConstructor:
-    return S.ComputeDefaultedCopyCtorExceptionSpec(MD);
-  case Sema::CXXCopyAssignment:
-    return S.ComputeDefaultedCopyAssignmentExceptionSpec(MD);
-  case Sema::CXXMoveConstructor:
-    return S.ComputeDefaultedMoveCtorExceptionSpec(MD);
-  case Sema::CXXMoveAssignment:
-    return S.ComputeDefaultedMoveAssignmentExceptionSpec(MD);
-  case Sema::CXXDestructor:
-    return S.ComputeDefaultedDtorExceptionSpec(MD);
-  case Sema::CXXInvalid:
-    break;
-  }
-  assert(cast<CXXConstructorDecl>(MD)->getInheritedConstructor() &&
+  auto CSM = S.getSpecialMember(MD);
+  if (CSM != Sema::CXXInvalid)
+    return ComputeDefaultedSpecialMemberExceptionSpec(S, Loc, MD, CSM, nullptr);
+
+  auto *CD = cast<CXXConstructorDecl>(MD);
+  assert(CD->getInheritedConstructor() &&
          "only special members have implicit exception specs");
-  return S.ComputeInheritingCtorExceptionSpec(Loc,
-                                              cast<CXXConstructorDecl>(MD));
+  Sema::InheritedConstructorInfo ICI(
+      S, Loc, CD->getInheritedConstructor().getShadowDecl());
+  return ComputeDefaultedSpecialMemberExceptionSpec(
+      S, Loc, CD, Sema::CXXDefaultConstructor, &ICI);
 }
 
 static FunctionProtoType::ExtProtoInfo getImplicitMethodEPI(Sema &S,
@@ -6300,45 +6371,35 @@ void Sema::CheckDelayedMemberExceptionSpecs() {
 }
 
 namespace {
-struct SpecialMemberDeletionInfo {
+/// CRTP base class for visiting operations performed by a special member
+/// function (or inherited constructor).
+template<typename Derived>
+struct SpecialMemberVisitor {
   Sema &S;
   CXXMethodDecl *MD;
   Sema::CXXSpecialMember CSM;
   Sema::InheritedConstructorInfo *ICI;
-  bool Diagnose;
 
   // Properties of the special member, computed for convenience.
-  bool IsConstructor, IsAssignment, IsMove, ConstArg;
-  SourceLocation Loc;
-
-  bool AllFieldsAreConst;
+  bool IsConstructor = false, IsAssignment = false, ConstArg = false;
 
-  SpecialMemberDeletionInfo(Sema &S, CXXMethodDecl *MD,
-                            Sema::CXXSpecialMember CSM,
-                            Sema::InheritedConstructorInfo *ICI, bool Diagnose)
-      : S(S), MD(MD), CSM(CSM), ICI(ICI), Diagnose(Diagnose),
-        IsConstructor(false), IsAssignment(false), IsMove(false),
-        ConstArg(false), Loc(MD->getLocation()), AllFieldsAreConst(true) {
+  SpecialMemberVisitor(Sema &S, CXXMethodDecl *MD, Sema::CXXSpecialMember CSM,
+                       Sema::InheritedConstructorInfo *ICI)
+      : S(S), MD(MD), CSM(CSM), ICI(ICI) {
     switch (CSM) {
-      case Sema::CXXDefaultConstructor:
-      case Sema::CXXCopyConstructor:
-        IsConstructor = true;
-        break;
-      case Sema::CXXMoveConstructor:
-        IsConstructor = true;
-        IsMove = true;
-        break;
-      case Sema::CXXCopyAssignment:
-        IsAssignment = true;
-        break;
-      case Sema::CXXMoveAssignment:
-        IsAssignment = true;
-        IsMove = true;
-        break;
-      case Sema::CXXDestructor:
-        break;
-      case Sema::CXXInvalid:
-        llvm_unreachable("invalid special member kind");
+    case Sema::CXXDefaultConstructor:
+    case Sema::CXXCopyConstructor:
+    case Sema::CXXMoveConstructor:
+      IsConstructor = true;
+      break;
+    case Sema::CXXCopyAssignment:
+    case Sema::CXXMoveAssignment:
+      IsAssignment = true;
+      break;
+    case Sema::CXXDestructor:
+      break;
+    case Sema::CXXInvalid:
+      llvm_unreachable("invalid special member kind");
     }
 
     if (MD->getNumParams()) {
@@ -6348,21 +6409,109 @@ struct SpecialMemberDeletionInfo {
     }
   }
 
-  bool inUnion() const { return MD->getParent()->isUnion(); }
+  Derived &getDerived() { return static_cast<Derived&>(*this); }
 
-  Sema::CXXSpecialMember getEffectiveCSM() {
-    return ICI ? Sema::CXXInvalid : CSM;
+  /// Is this a "move" special member?
+  bool isMove() const {
+    return CSM == Sema::CXXMoveConstructor || CSM == Sema::CXXMoveAssignment;
   }
 
   /// Look up the corresponding special member in the given class.
-  Sema::SpecialMemberOverloadResult *lookupIn(CXXRecordDecl *Class,
-                                              unsigned Quals, bool IsMutable) {
+  Sema::SpecialMemberOverloadResult lookupIn(CXXRecordDecl *Class,
+                                             unsigned Quals, bool IsMutable) {
     return lookupCallFromSpecialMember(S, Class, CSM, Quals,
                                        ConstArg && !IsMutable);
   }
 
+  /// Look up the constructor for the specified base class to see if it's
+  /// overridden due to this being an inherited constructor.
+  Sema::SpecialMemberOverloadResult lookupInheritedCtor(CXXRecordDecl *Class) {
+    if (!ICI)
+      return {};
+    assert(CSM == Sema::CXXDefaultConstructor);
+    auto *BaseCtor =
+      cast<CXXConstructorDecl>(MD)->getInheritedConstructor().getConstructor();
+    if (auto *MD = ICI->findConstructorForBase(Class, BaseCtor).first)
+      return MD;
+    return {};
+  }
+
+  /// A base or member subobject.
   typedef llvm::PointerUnion<CXXBaseSpecifier*, FieldDecl*> Subobject;
 
+  /// Get the location to use for a subobject in diagnostics.
+  static SourceLocation getSubobjectLoc(Subobject Subobj) {
+    // FIXME: For an indirect virtual base, the direct base leading to
+    // the indirect virtual base would be a more useful choice.
+    if (auto *B = Subobj.dyn_cast<CXXBaseSpecifier*>())
+      return B->getBaseTypeLoc();
+    else
+      return Subobj.get<FieldDecl*>()->getLocation();
+  }
+
+  enum BasesToVisit {
+    /// Visit all non-virtual (direct) bases.
+    VisitNonVirtualBases,
+    /// Visit all direct bases, virtual or not.
+    VisitDirectBases,
+    /// Visit all non-virtual bases, and all virtual bases if the class
+    /// is not abstract.
+    VisitPotentiallyConstructedBases,
+    /// Visit all direct or virtual bases.
+    VisitAllBases
+  };
+
+  // Visit the bases and members of the class.
+  bool visit(BasesToVisit Bases) {
+    CXXRecordDecl *RD = MD->getParent();
+
+    if (Bases == VisitPotentiallyConstructedBases)
+      Bases = RD->isAbstract() ? VisitNonVirtualBases : VisitAllBases;
+
+    for (auto &B : RD->bases())
+      if ((Bases == VisitDirectBases || !B.isVirtual()) &&
+          getDerived().visitBase(&B))
+        return true;
+
+    if (Bases == VisitAllBases)
+      for (auto &B : RD->vbases())
+        if (getDerived().visitBase(&B))
+          return true;
+
+    for (auto *F : RD->fields())
+      if (!F->isInvalidDecl() && !F->isUnnamedBitfield() &&
+          getDerived().visitField(F))
+        return true;
+
+    return false;
+  }
+};
+}
+
+namespace {
+struct SpecialMemberDeletionInfo
+    : SpecialMemberVisitor<SpecialMemberDeletionInfo> {
+  bool Diagnose;
+
+  SourceLocation Loc;
+
+  bool AllFieldsAreConst;
+
+  SpecialMemberDeletionInfo(Sema &S, CXXMethodDecl *MD,
+                            Sema::CXXSpecialMember CSM,
+                            Sema::InheritedConstructorInfo *ICI, bool Diagnose)
+      : SpecialMemberVisitor(S, MD, CSM, ICI), Diagnose(Diagnose),
+        Loc(MD->getLocation()), AllFieldsAreConst(true) {}
+
+  bool inUnion() const { return MD->getParent()->isUnion(); }
+
+  Sema::CXXSpecialMember getEffectiveCSM() {
+    return ICI ? Sema::CXXInvalid : CSM;
+  }
+
+  bool visitBase(CXXBaseSpecifier *Base) { return shouldDeleteForBase(Base); }
+  bool visitField(FieldDecl *Field) { return shouldDeleteForField(Field); }
+
   bool shouldDeleteForBase(CXXBaseSpecifier *Base);
   bool shouldDeleteForField(FieldDecl *FD);
   bool shouldDeleteForAllConstMembers();
@@ -6370,7 +6519,7 @@ struct SpecialMemberDeletionInfo {
   bool shouldDeleteForClassSubobject(CXXRecordDecl *Class, Subobject Subobj,
                                      unsigned Quals);
   bool shouldDeleteForSubobjectCall(Subobject Subobj,
-                                    Sema::SpecialMemberOverloadResult *SMOR,
+                                    Sema::SpecialMemberOverloadResult SMOR,
                                     bool IsDtorCallInCtor);
 
   bool isAccessible(Subobject Subobj, CXXMethodDecl *D);
@@ -6400,16 +6549,16 @@ bool SpecialMemberDeletionInfo::isAccessible(Subobject Subobj,
 /// Check whether we should delete a special member due to the implicit
 /// definition containing a call to a special member of a subobject.
 bool SpecialMemberDeletionInfo::shouldDeleteForSubobjectCall(
-    Subobject Subobj, Sema::SpecialMemberOverloadResult *SMOR,
+    Subobject Subobj, Sema::SpecialMemberOverloadResult SMOR,
     bool IsDtorCallInCtor) {
-  CXXMethodDecl *Decl = SMOR->getMethod();
+  CXXMethodDecl *Decl = SMOR.getMethod();
   FieldDecl *Field = Subobj.dyn_cast<FieldDecl*>();
 
   int DiagKind = -1;
 
-  if (SMOR->getKind() == Sema::SpecialMemberOverloadResult::NoMemberOrDeleted)
+  if (SMOR.getKind() == Sema::SpecialMemberOverloadResult::NoMemberOrDeleted)
     DiagKind = !Decl ? 0 : 1;
-  else if (SMOR->getKind() == Sema::SpecialMemberOverloadResult::Ambiguous)
+  else if (SMOR.getKind() == Sema::SpecialMemberOverloadResult::Ambiguous)
     DiagKind = 2;
   else if (!isAccessible(Subobj, Decl))
     DiagKind = 3;
@@ -6479,7 +6628,7 @@ bool SpecialMemberDeletionInfo::shouldDeleteForClassSubobject(
   // -- any direct or virtual base class or non-static data member has a
   //    type with a destructor that is deleted or inaccessible
   if (IsConstructor) {
-    Sema::SpecialMemberOverloadResult *SMOR =
+    Sema::SpecialMemberOverloadResult SMOR =
         S.LookupSpecialMember(Class, Sema::CXXDestructor,
                               false, false, false, false, false);
     if (shouldDeleteForSubobjectCall(Subobj, SMOR, true))
@@ -6499,23 +6648,20 @@ bool SpecialMemberDeletionInfo::shouldDeleteForBase(CXXBaseSpecifier *Base) {
     return false;
   // If we have an inheriting constructor, check whether we're calling an
   // inherited constructor instead of a default constructor.
-  if (ICI) {
-    assert(CSM == Sema::CXXDefaultConstructor);
-    auto *BaseCtor =
-        ICI->findConstructorForBase(BaseClass, cast<CXXConstructorDecl>(MD)
-                                                   ->getInheritedConstructor()
-                                                   .getConstructor())
-            .first;
-    if (BaseCtor) {
-      if (BaseCtor->isDeleted() && Diagnose) {
-        S.Diag(Base->getLocStart(),
-               diag::note_deleted_special_member_class_subobject)
-          << getEffectiveCSM() << MD->getParent() << /*IsField*/false
-          << Base->getType() << /*Deleted*/1 << /*IsDtorCallInCtor*/false;
-        S.NoteDeletedFunction(BaseCtor);
-      }
-      return BaseCtor->isDeleted();
+  Sema::SpecialMemberOverloadResult SMOR = lookupInheritedCtor(BaseClass);
+  if (auto *BaseCtor = SMOR.getMethod()) {
+    // Note that we do not check access along this path; other than that,
+    // this is the same as shouldDeleteForSubobjectCall(Base, BaseCtor, false);
+    // FIXME: Check that the base has a usable destructor! Sink this into
+    // shouldDeleteForClassSubobject.
+    if (BaseCtor->isDeleted() && Diagnose) {
+      S.Diag(Base->getLocStart(),
+             diag::note_deleted_special_member_class_subobject)
+        << getEffectiveCSM() << MD->getParent() << /*IsField*/false
+        << Base->getType() << /*Deleted*/1 << /*IsDtorCallInCtor*/false;
+      S.NoteDeletedFunction(BaseCtor);
     }
+    return BaseCtor->isDeleted();
   }
   return shouldDeleteForClassSubobject(BaseClass, Base, 0);
 }
@@ -6564,7 +6710,7 @@ bool SpecialMemberDeletionInfo::shouldDeleteForField(FieldDecl *FD) {
     if (FieldType->isReferenceType()) {
       if (Diagnose)
         S.Diag(FD->getLocation(), diag::note_deleted_assign_field)
-          << IsMove << MD->getParent() << FD << FieldType << /*Reference*/0;
+          << isMove() << MD->getParent() << FD << FieldType << /*Reference*/0;
       return true;
     }
     if (!FieldRecord && FieldType.isConstQualified()) {
@@ -6572,7 +6718,7 @@ bool SpecialMemberDeletionInfo::shouldDeleteForField(FieldDecl *FD) {
       // -- a non-static data member of const non-class type (or array thereof)
       if (Diagnose)
         S.Diag(FD->getLocation(), diag::note_deleted_assign_field)
-          << IsMove << MD->getParent() << FD << FD->getType() << /*Const*/1;
+          << isMove() << MD->getParent() << FD << FD->getType() << /*Const*/1;
       return true;
     }
   }
@@ -6743,24 +6889,15 @@ bool Sema::ShouldDeleteSpecialMember(CXXMethodDecl *MD, CXXSpecialMember CSM,
 
   SpecialMemberDeletionInfo SMI(*this, MD, CSM, ICI, Diagnose);
 
-  for (auto &BI : RD->bases())
-    if ((SMI.IsAssignment || !BI.isVirtual()) &&
-        SMI.shouldDeleteForBase(&BI))
-      return true;
-
   // Per DR1611, do not consider virtual bases of constructors of abstract
-  // classes, since we are not going to construct them. For assignment
-  // operators, we only assign (and thus only consider) direct bases.
-  if ((!RD->isAbstract() || !SMI.IsConstructor) && !SMI.IsAssignment) {
-    for (auto &BI : RD->vbases())
-      if (SMI.shouldDeleteForBase(&BI))
-        return true;
-  }
-
-  for (auto *FI : RD->fields())
-    if (!FI->isInvalidDecl() && !FI->isUnnamedBitfield() &&
-        SMI.shouldDeleteForField(FI))
-      return true;
+  // classes, since we are not going to construct them.
+  // Per DR1658, do not consider virtual bases of destructors of abstract
+  // classes either.
+  // Per DR2180, for assignment operators we only assign (and thus only
+  // consider) direct bases.
+  if (SMI.visit(SMI.IsAssignment ? SMI.VisitDirectBases
+                                 : SMI.VisitPotentiallyConstructedBases))
+    return true;
 
   if (SMI.shouldDeleteForAllConstMembers())
     return true;
@@ -6874,18 +7011,18 @@ static bool findTrivialSpecialMember(Sema &S, CXXRecordDecl *RD,
   case Sema::CXXMoveConstructor:
   case Sema::CXXMoveAssignment:
   NeedOverloadResolution:
-    Sema::SpecialMemberOverloadResult *SMOR =
+    Sema::SpecialMemberOverloadResult SMOR =
         lookupCallFromSpecialMember(S, RD, CSM, Quals, ConstRHS);
 
     // The standard doesn't describe how to behave if the lookup is ambiguous.
     // We treat it as not making the member non-trivial, just like the standard
     // mandates for the default constructor. This should rarely matter, because
     // the member will also be deleted.
-    if (SMOR->getKind() == Sema::SpecialMemberOverloadResult::Ambiguous)
+    if (SMOR.getKind() == Sema::SpecialMemberOverloadResult::Ambiguous)
       return true;
 
-    if (!SMOR->getMethod()) {
-      assert(SMOR->getKind() ==
+    if (!SMOR.getMethod()) {
+      assert(SMOR.getKind() ==
              Sema::SpecialMemberOverloadResult::NoMemberOrDeleted);
       return false;
     }
@@ -6893,8 +7030,8 @@ static bool findTrivialSpecialMember(Sema &S, CXXRecordDecl *RD,
     // We deliberately don't check if we found a deleted special member. We're
     // not supposed to!
     if (Selected)
-      *Selected = SMOR->getMethod();
-    return SMOR->getMethod()->isTrivial();
+      *Selected = SMOR.getMethod();
+    return SMOR.getMethod()->isTrivial();
   }
 
   llvm_unreachable("unknown special method kind");
@@ -7009,8 +7146,7 @@ static bool checkTrivialClassMembers(Sema &S, CXXRecordDecl *RD,
     //   [...] nontrivally ownership-qualified types are [...] not trivially
     //   default constructible, copy constructible, move constructible, copy
     //   assignable, move assignable, or destructible [...]
-    if (S.getLangOpts().ObjCAutoRefCount &&
-        FieldType.hasNonTrivialObjCLifetime()) {
+    if (FieldType.hasNonTrivialObjCLifetime()) {
       if (Diagnose)
         S.Diag(FI->getLocation(), diag::note_nontrivial_objc_ownership)
           << RD << FieldType.getObjCLifetime();
@@ -8033,6 +8169,154 @@ Decl *Sema::ActOnConversionDeclarator(CXXConversionDecl *Conversion) {
   return Conversion;
 }
 
+namespace {
+/// Utility class to accumulate and print a diagnostic listing the invalid
+/// specifier(s) on a declaration.
+struct BadSpecifierDiagnoser {
+  BadSpecifierDiagnoser(Sema &S, SourceLocation Loc, unsigned DiagID)
+      : S(S), Diagnostic(S.Diag(Loc, DiagID)) {}
+  ~BadSpecifierDiagnoser() {
+    Diagnostic << Specifiers;
+  }
+
+  template<typename T> void check(SourceLocation SpecLoc, T Spec) {
+    return check(SpecLoc, DeclSpec::getSpecifierName(Spec));
+  }
+  void check(SourceLocation SpecLoc, DeclSpec::TST Spec) {
+    return check(SpecLoc,
+                 DeclSpec::getSpecifierName(Spec, S.getPrintingPolicy()));
+  }
+  void check(SourceLocation SpecLoc, const char *Spec) {
+    if (SpecLoc.isInvalid()) return;
+    Diagnostic << SourceRange(SpecLoc, SpecLoc);
+    if (!Specifiers.empty()) Specifiers += " ";
+    Specifiers += Spec;
+  }
+
+  Sema &S;
+  Sema::SemaDiagnosticBuilder Diagnostic;
+  std::string Specifiers;
+};
+}
+
+/// Check the validity of a declarator that we parsed for a deduction-guide.
+/// These aren't actually declarators in the grammar, so we need to check that
+/// the user didn't specify any pieces that are not part of the deduction-guide
+/// grammar.
+void Sema::CheckDeductionGuideDeclarator(Declarator &D, QualType &R,
+                                         StorageClass &SC) {
+  TemplateName GuidedTemplate = D.getName().TemplateName.get().get();
+  TemplateDecl *GuidedTemplateDecl = GuidedTemplate.getAsTemplateDecl();
+  assert(GuidedTemplateDecl && "missing template decl for deduction guide");
+
+  // C++ [temp.deduct.guide]p3:
+  //   A deduction-gide shall be declared in the same scope as the
+  //   corresponding class template.
+  if (!CurContext->getRedeclContext()->Equals(
+          GuidedTemplateDecl->getDeclContext()->getRedeclContext())) {
+    Diag(D.getIdentifierLoc(), diag::err_deduction_guide_wrong_scope)
+      << GuidedTemplateDecl;
+    Diag(GuidedTemplateDecl->getLocation(), diag::note_template_decl_here);
+  }
+
+  auto &DS = D.getMutableDeclSpec();
+  // We leave 'friend' and 'virtual' to be rejected in the normal way.
+  if (DS.hasTypeSpecifier() || DS.getTypeQualifiers() ||
+      DS.getStorageClassSpecLoc().isValid() || DS.isInlineSpecified() ||
+      DS.isNoreturnSpecified() || DS.isConstexprSpecified() ||
+      DS.isConceptSpecified()) {
+    BadSpecifierDiagnoser Diagnoser(
+        *this, D.getIdentifierLoc(),
+        diag::err_deduction_guide_invalid_specifier);
+
+    Diagnoser.check(DS.getStorageClassSpecLoc(), DS.getStorageClassSpec());
+    DS.ClearStorageClassSpecs();
+    SC = SC_None;
+
+    // 'explicit' is permitted.
+    Diagnoser.check(DS.getInlineSpecLoc(), "inline");
+    Diagnoser.check(DS.getNoreturnSpecLoc(), "_Noreturn");
+    Diagnoser.check(DS.getConstexprSpecLoc(), "constexpr");
+    Diagnoser.check(DS.getConceptSpecLoc(), "concept");
+    DS.ClearConstexprSpec();
+    DS.ClearConceptSpec();
+
+    Diagnoser.check(DS.getConstSpecLoc(), "const");
+    Diagnoser.check(DS.getRestrictSpecLoc(), "__restrict");
+    Diagnoser.check(DS.getVolatileSpecLoc(), "volatile");
+    Diagnoser.check(DS.getAtomicSpecLoc(), "_Atomic");
+    Diagnoser.check(DS.getUnalignedSpecLoc(), "__unaligned");
+    DS.ClearTypeQualifiers();
+
+    Diagnoser.check(DS.getTypeSpecComplexLoc(), DS.getTypeSpecComplex());
+    Diagnoser.check(DS.getTypeSpecSignLoc(), DS.getTypeSpecSign());
+    Diagnoser.check(DS.getTypeSpecWidthLoc(), DS.getTypeSpecWidth());
+    Diagnoser.check(DS.getTypeSpecTypeLoc(), DS.getTypeSpecType());
+    DS.ClearTypeSpecType();
+  }
+
+  if (D.isInvalidType())
+    return;
+
+  // Check the declarator is simple enough.
+  bool FoundFunction = false;
+  for (const DeclaratorChunk &Chunk : llvm::reverse(D.type_objects())) {
+    if (Chunk.Kind == DeclaratorChunk::Paren)
+      continue;
+    if (Chunk.Kind != DeclaratorChunk::Function || FoundFunction) {
+      Diag(D.getDeclSpec().getLocStart(),
+          diag::err_deduction_guide_with_complex_decl)
+        << D.getSourceRange();
+      break;
+    }
+    if (!Chunk.Fun.hasTrailingReturnType()) {
+      Diag(D.getName().getLocStart(),
+           diag::err_deduction_guide_no_trailing_return_type);
+      break;
+    }
+
+    // Check that the return type is written as a specialization of
+    // the template specified as the deduction-guide's name.
+    ParsedType TrailingReturnType = Chunk.Fun.getTrailingReturnType();
+    TypeSourceInfo *TSI = nullptr;
+    QualType RetTy = GetTypeFromParser(TrailingReturnType, &TSI);
+    assert(TSI && "deduction guide has valid type but invalid return type?");
+    bool AcceptableReturnType = false;
+    bool MightInstantiateToSpecialization = false;
+    if (auto RetTST =
+            TSI->getTypeLoc().getAs<TemplateSpecializationTypeLoc>()) {
+      TemplateName SpecifiedName = RetTST.getTypePtr()->getTemplateName();
+      bool TemplateMatches =
+          Context.hasSameTemplateName(SpecifiedName, GuidedTemplate);
+      if (SpecifiedName.getKind() == TemplateName::Template && TemplateMatches)
+        AcceptableReturnType = true;
+      else {
+        // This could still instantiate to the right type, unless we know it
+        // names the wrong class template.
+        auto *TD = SpecifiedName.getAsTemplateDecl();
+        MightInstantiateToSpecialization = !(TD && isa<ClassTemplateDecl>(TD) &&
+                                             !TemplateMatches);
+      }
+    } else if (!RetTy.hasQualifiers() && RetTy->isDependentType()) {
+      MightInstantiateToSpecialization = true;
+    }
+
+    if (!AcceptableReturnType) {
+      Diag(TSI->getTypeLoc().getLocStart(),
+           diag::err_deduction_guide_bad_trailing_return_type)
+        << GuidedTemplate << TSI->getType() << MightInstantiateToSpecialization
+        << TSI->getTypeLoc().getSourceRange();
+    }
+
+    // Keep going to check that we don't have any inner declarator pieces (we
+    // could still have a function returning a pointer to a function).
+    FoundFunction = true;
+  }
+
+  if (D.isFunctionDefinition())
+    Diag(D.getIdentifierLoc(), diag::err_deduction_guide_defines_function);
+}
+
 //===----------------------------------------------------------------------===//
 // Namespace Handling
 //===----------------------------------------------------------------------===//
@@ -8397,7 +8681,7 @@ QualType Sema::BuildStdInitializerList(QualType Element, SourceLocation Loc) {
       CheckTemplateIdType(TemplateName(StdInitializerList), Loc, Args));
 }
 
-bool Sema::isInitListConstructor(const CXXConstructorDecl* Ctor) {
+bool Sema::isInitListConstructor(const FunctionDecl *Ctor) {
   // C++ [dcl.init.list]p2:
   //   A constructor is an initializer-list constructor if its first parameter
   //   is of type std::initializer_list<E> or reference to possibly cv-qualified
@@ -8613,6 +8897,9 @@ Decl *Sema::ActOnUsingDeclaration(Scope *S,
     Diag(Name.getLocStart(), diag::err_using_decl_template_id)
       << SourceRange(Name.TemplateId->LAngleLoc, Name.TemplateId->RAngleLoc);
     return nullptr;
+
+  case UnqualifiedId::IK_DeductionGuideName:
+    llvm_unreachable("cannot parse qualified deduction guide name");
   }
 
   DeclarationNameInfo TargetNameInfo = GetNameFromUnqualifiedId(Name);
@@ -9169,15 +9456,18 @@ NamedDecl *Sema::BuildUsingDeclaration(Scope *S, AccessSpecifier AS,
                 HasTypenameKeyword, IsInstantiation, SS.getScopeRep(),
                 dyn_cast<CXXRecordDecl>(CurContext)),
             CTK_ErrorRecovery)) {
-      // We reject any correction for which ND would be NULL.
-      NamedDecl *ND = Corrected.getCorrectionDecl();
-
       // We reject candidates where DroppedSpecifier == true, hence the
       // literal '0' below.
       diagnoseTypo(Corrected, PDiag(diag::err_no_member_suggest)
                                 << NameInfo.getName() << LookupContext << 0
                                 << SS.getRange());
 
+      // If we picked a correction with no attached Decl we can't do anything
+      // useful with it, bail out.
+      NamedDecl *ND = Corrected.getCorrectionDecl();
+      if (!ND)
+        return BuildInvalid();
+
       // If we corrected to an inheriting constructor, handle it as one.
       auto *RD = dyn_cast<CXXRecordDecl>(ND);
       if (RD && RD->isInjectedClassName()) {
@@ -9816,123 +10106,113 @@ Decl *Sema::ActOnNamespaceAliasDef(Scope *S, SourceLocation NamespaceLoc,
   return AliasDecl;
 }
 
-Sema::ImplicitExceptionSpecification
-Sema::ComputeDefaultedDefaultCtorExceptionSpec(SourceLocation Loc,
-                                               CXXMethodDecl *MD) {
-  CXXRecordDecl *ClassDecl = MD->getParent();
+namespace {
+struct SpecialMemberExceptionSpecInfo
+    : SpecialMemberVisitor<SpecialMemberExceptionSpecInfo> {
+  SourceLocation Loc;
+  Sema::ImplicitExceptionSpecification ExceptSpec;
 
-  // C++ [except.spec]p14:
-  //   An implicitly declared special member function (Clause 12) shall have an 
-  //   exception-specification. [...]
-  ImplicitExceptionSpecification ExceptSpec(*this);
-  if (ClassDecl->isInvalidDecl())
-    return ExceptSpec;
+  SpecialMemberExceptionSpecInfo(Sema &S, CXXMethodDecl *MD,
+                                 Sema::CXXSpecialMember CSM,
+                                 Sema::InheritedConstructorInfo *ICI,
+                                 SourceLocation Loc)
+      : SpecialMemberVisitor(S, MD, CSM, ICI), Loc(Loc), ExceptSpec(S) {}
 
-  // Direct base-class constructors.
-  for (const auto &B : ClassDecl->bases()) {
-    if (B.isVirtual()) // Handled below.
-      continue;
-    
-    if (const RecordType *BaseType = B.getType()->getAs<RecordType>()) {
-      CXXRecordDecl *BaseClassDecl = cast<CXXRecordDecl>(BaseType->getDecl());
-      CXXConstructorDecl *Constructor = LookupDefaultConstructor(BaseClassDecl);
-      // If this is a deleted function, add it anyway. This might be conformant
-      // with the standard. This might not. I'm not sure. It might not matter.
-      if (Constructor)
-        ExceptSpec.CalledDecl(B.getLocStart(), Constructor);
-    }
-  }
+  bool visitBase(CXXBaseSpecifier *Base);
+  bool visitField(FieldDecl *FD);
 
-  // Virtual base-class constructors.
-  for (const auto &B : ClassDecl->vbases()) {
-    if (const RecordType *BaseType = B.getType()->getAs<RecordType>()) {
-      CXXRecordDecl *BaseClassDecl = cast<CXXRecordDecl>(BaseType->getDecl());
-      CXXConstructorDecl *Constructor = LookupDefaultConstructor(BaseClassDecl);
-      // If this is a deleted function, add it anyway. This might be conformant
-      // with the standard. This might not. I'm not sure. It might not matter.
-      if (Constructor)
-        ExceptSpec.CalledDecl(B.getLocStart(), Constructor);
-    }
-  }
-
-  // Field constructors.
-  for (auto *F : ClassDecl->fields()) {
-    if (F->hasInClassInitializer()) {
-      Expr *E = F->getInClassInitializer();
-      if (!E)
-        // FIXME: It's a little wasteful to build and throw away a
-        // CXXDefaultInitExpr here.
-        E = BuildCXXDefaultInitExpr(Loc, F).get();
-      if (E)
-        ExceptSpec.CalledExpr(E);
-    } else if (const RecordType *RecordTy
-              = Context.getBaseElementType(F->getType())->getAs<RecordType>()) {
-      CXXRecordDecl *FieldRecDecl = cast<CXXRecordDecl>(RecordTy->getDecl());
-      CXXConstructorDecl *Constructor = LookupDefaultConstructor(FieldRecDecl);
-      // If this is a deleted function, add it anyway. This might be conformant
-      // with the standard. This might not. I'm not sure. It might not matter.
-      // In particular, the problem is that this function never gets called. It
-      // might just be ill-formed because this function attempts to refer to
-      // a deleted function here.
-      if (Constructor)
-        ExceptSpec.CalledDecl(F->getLocation(), Constructor);
-    }
-  }
+  void visitClassSubobject(CXXRecordDecl *Class, Subobject Subobj,
+                           unsigned Quals);
 
-  return ExceptSpec;
+  void visitSubobjectCall(Subobject Subobj,
+                          Sema::SpecialMemberOverloadResult SMOR);
+};
 }
 
-Sema::ImplicitExceptionSpecification
-Sema::ComputeInheritingCtorExceptionSpec(SourceLocation Loc,
-                                         CXXConstructorDecl *CD) {
-  CXXRecordDecl *ClassDecl = CD->getParent();
+bool SpecialMemberExceptionSpecInfo::visitBase(CXXBaseSpecifier *Base) {
+  auto *RT = Base->getType()->getAs<RecordType>();
+  if (!RT)
+    return false;
 
-  // C++ [except.spec]p14:
-  //   An inheriting constructor [...] shall have an exception-specification. [...]
-  ImplicitExceptionSpecification ExceptSpec(*this);
-  if (ClassDecl->isInvalidDecl())
-    return ExceptSpec;
+  auto *BaseClass = cast<CXXRecordDecl>(RT->getDecl());
+  Sema::SpecialMemberOverloadResult SMOR = lookupInheritedCtor(BaseClass);
+  if (auto *BaseCtor = SMOR.getMethod()) {
+    visitSubobjectCall(Base, BaseCtor);
+    return false;
+  }
 
-  auto Inherited = CD->getInheritedConstructor();
-  InheritedConstructorInfo ICI(*this, Loc, Inherited.getShadowDecl());
+  visitClassSubobject(BaseClass, Base, 0);
+  return false;
+}
 
-  // Direct and virtual base-class constructors.
-  for (bool VBase : {false, true}) {
-    for (CXXBaseSpecifier &B :
-         VBase ? ClassDecl->vbases() : ClassDecl->bases()) {
-      // Don't visit direct vbases twice.
-      if (B.isVirtual() != VBase)
-        continue;
+bool SpecialMemberExceptionSpecInfo::visitField(FieldDecl *FD) {
+  if (CSM == Sema::CXXDefaultConstructor && FD->hasInClassInitializer()) {
+    Expr *E = FD->getInClassInitializer();
+    if (!E)
+      // FIXME: It's a little wasteful to build and throw away a
+      // CXXDefaultInitExpr here.
+      // FIXME: We should have a single context note pointing at Loc, and
+      // this location should be MD->getLocation() instead, since that's
+      // the location where we actually use the default init expression.
+      E = S.BuildCXXDefaultInitExpr(Loc, FD).get();
+    if (E)
+      ExceptSpec.CalledExpr(E);
+  } else if (auto *RT = S.Context.getBaseElementType(FD->getType())
+                            ->getAs<RecordType>()) {
+    visitClassSubobject(cast<CXXRecordDecl>(RT->getDecl()), FD,
+                        FD->getType().getCVRQualifiers());
+  }
+  return false;
+}
 
-      CXXRecordDecl *BaseClass = B.getType()->getAsCXXRecordDecl();
-      if (!BaseClass)
-        continue;
+void SpecialMemberExceptionSpecInfo::visitClassSubobject(CXXRecordDecl *Class,
+                                                         Subobject Subobj,
+                                                         unsigned Quals) {
+  FieldDecl *Field = Subobj.dyn_cast<FieldDecl*>();
+  bool IsMutable = Field && Field->isMutable();
+  visitSubobjectCall(Subobj, lookupIn(Class, Quals, IsMutable));
+}
 
-      CXXConstructorDecl *Constructor =
-          ICI.findConstructorForBase(BaseClass, Inherited.getConstructor())
-              .first;
-      if (!Constructor)
-        Constructor = LookupDefaultConstructor(BaseClass);
-      if (Constructor)
-        ExceptSpec.CalledDecl(B.getLocStart(), Constructor);
-    }
-  }
+void SpecialMemberExceptionSpecInfo::visitSubobjectCall(
+    Subobject Subobj, Sema::SpecialMemberOverloadResult SMOR) {
+  // Note, if lookup fails, it doesn't matter what exception specification we
+  // choose because the special member will be deleted.
+  if (CXXMethodDecl *MD = SMOR.getMethod())
+    ExceptSpec.CalledDecl(getSubobjectLoc(Subobj), MD);
+}
 
-  // Field constructors.
-  for (const auto *F : ClassDecl->fields()) {
-    if (F->hasInClassInitializer()) {
-      if (Expr *E = F->getInClassInitializer())
-        ExceptSpec.CalledExpr(E);
-    } else if (const RecordType *RecordTy
-              = Context.getBaseElementType(F->getType())->getAs<RecordType>()) {
-      CXXRecordDecl *FieldRecDecl = cast<CXXRecordDecl>(RecordTy->getDecl());
-      CXXConstructorDecl *Constructor = LookupDefaultConstructor(FieldRecDecl);
-      if (Constructor)
-        ExceptSpec.CalledDecl(F->getLocation(), Constructor);
-    }
-  }
+static Sema::ImplicitExceptionSpecification
+ComputeDefaultedSpecialMemberExceptionSpec(
+    Sema &S, SourceLocation Loc, CXXMethodDecl *MD, Sema::CXXSpecialMember CSM,
+    Sema::InheritedConstructorInfo *ICI) {
+  CXXRecordDecl *ClassDecl = MD->getParent();
 
-  return ExceptSpec;
+  // C++ [except.spec]p14:
+  //   An implicitly declared special member function (Clause 12) shall have an 
+  //   exception-specification. [...]
+  SpecialMemberExceptionSpecInfo Info(S, MD, CSM, ICI, Loc);
+  if (ClassDecl->isInvalidDecl())
+    return Info.ExceptSpec;
+
+  // C++1z [except.spec]p7:
+  //   [Look for exceptions thrown by] a constructor selected [...] to
+  //   initialize a potentially constructed subobject,
+  // C++1z [except.spec]p8:
+  //   The exception specification for an implicitly-declared destructor, or a
+  //   destructor without a noexcept-specifier, is potentially-throwing if and
+  //   only if any of the destructors for any of its potentially constructed
+  //   subojects is potentially throwing.
+  // FIXME: We respect the first rule but ignore the "potentially constructed"
+  // in the second rule to resolve a core issue (no number yet) that would have
+  // us reject:
+  //   struct A { virtual void f() = 0; virtual ~A() noexcept(false) = 0; };
+  //   struct B : A {};
+  //   struct C : B { void f(); };
+  // ... due to giving B::~B() a non-throwing exception specification.
+  Info.visit(Info.IsConstructor ? Info.VisitPotentiallyConstructedBases
+                                : Info.VisitAllBases);
+
+  return Info.ExceptSpec;
 }
 
 namespace {
@@ -9944,19 +10224,34 @@ struct DeclaringSpecialMember {
   bool WasAlreadyBeingDeclared;
 
   DeclaringSpecialMember(Sema &S, CXXRecordDecl *RD, Sema::CXXSpecialMember CSM)
-    : S(S), D(RD, CSM), SavedContext(S, RD) {
+      : S(S), D(RD, CSM), SavedContext(S, RD) {
     WasAlreadyBeingDeclared = !S.SpecialMembersBeingDeclared.insert(D).second;
     if (WasAlreadyBeingDeclared)
       // This almost never happens, but if it does, ensure that our cache
       // doesn't contain a stale result.
       S.SpecialMemberCache.clear();
-
-    // FIXME: Register a note to be produced if we encounter an error while
-    // declaring the special member.
+    else {
+      // Register a note to be produced if we encounter an error while
+      // declaring the special member.
+      Sema::CodeSynthesisContext Ctx;
+      Ctx.Kind = Sema::CodeSynthesisContext::DeclaringSpecialMember;
+      // FIXME: We don't have a location to use here. Using the class's
+      // location maintains the fiction that we declare all special members
+      // with the class, but (1) it's not clear that lying about that helps our
+      // users understand what's going on, and (2) there may be outer contexts
+      // on the stack (some of which are relevant) and printing them exposes
+      // our lies.
+      Ctx.PointOfInstantiation = RD->getLocation();
+      Ctx.Entity = RD;
+      Ctx.SpecialMember = CSM;
+      S.pushCodeSynthesisContext(Ctx);
+    }
   }
   ~DeclaringSpecialMember() {
-    if (!WasAlreadyBeingDeclared)
+    if (!WasAlreadyBeingDeclared) {
       S.SpecialMembersBeingDeclared.erase(D);
+      S.popCodeSynthesisContext();
+    }
   }
 
   /// \brief Are we already trying to declare this special member?
@@ -9978,7 +10273,7 @@ void Sema::CheckImplicitSpecialMemberDeclaration(Scope *S, FunctionDecl *FD) {
   R.resolveKind();
   R.suppressDiagnostics();
 
-  CheckFunctionDeclaration(S, FD, R, /*IsExplicitSpecialization*/false);
+  CheckFunctionDeclaration(S, FD, R, /*IsMemberSpecialization*/false);
 }
 
 CXXConstructorDecl *Sema::DeclareImplicitDefaultConstructor(
@@ -10262,45 +10557,6 @@ void Sema::DefineInheritingConstructor(SourceLocation CurrentLocation,
   DiagnoseUninitializedFields(*this, Constructor);
 }
 
-Sema::ImplicitExceptionSpecification
-Sema::ComputeDefaultedDtorExceptionSpec(CXXMethodDecl *MD) {
-  CXXRecordDecl *ClassDecl = MD->getParent();
-
-  // C++ [except.spec]p14: 
-  //   An implicitly declared special member function (Clause 12) shall have 
-  //   an exception-specification.
-  ImplicitExceptionSpecification ExceptSpec(*this);
-  if (ClassDecl->isInvalidDecl())
-    return ExceptSpec;
-
-  // Direct base-class destructors.
-  for (const auto &B : ClassDecl->bases()) {
-    if (B.isVirtual()) // Handled below.
-      continue;
-    
-    if (const RecordType *BaseType = B.getType()->getAs<RecordType>())
-      ExceptSpec.CalledDecl(B.getLocStart(),
-                   LookupDestructor(cast<CXXRecordDecl>(BaseType->getDecl())));
-  }
-
-  // Virtual base-class destructors.
-  for (const auto &B : ClassDecl->vbases()) {
-    if (const RecordType *BaseType = B.getType()->getAs<RecordType>())
-      ExceptSpec.CalledDecl(B.getLocStart(),
-                  LookupDestructor(cast<CXXRecordDecl>(BaseType->getDecl())));
-  }
-
-  // Field destructors.
-  for (const auto *F : ClassDecl->fields()) {
-    if (const RecordType *RecordTy
-        = Context.getBaseElementType(F->getType())->getAs<RecordType>())
-      ExceptSpec.CalledDecl(F->getLocation(),
-                  LookupDestructor(cast<CXXRecordDecl>(RecordTy->getDecl())));
-  }
-
-  return ExceptSpec;
-}
-
 CXXDestructorDecl *Sema::DeclareImplicitDestructor(CXXRecordDecl *ClassDecl) {
   // C++ [class.dtor]p2:
   //   If a class has no user-declared destructor, a destructor is
@@ -10852,7 +11108,7 @@ buildSingleCopyAssignRecursively(Sema &S, SourceLocation Loc, QualType T,
     = new (S.Context) BinaryOperator(IterationVarRefRVal.build(S, Loc),
                      IntegerLiteral::Create(S.Context, Upper, SizeType, Loc),
                                      BO_NE, S.Context.BoolTy,
-                                     VK_RValue, OK_Ordinary, Loc, false);
+                                     VK_RValue, OK_Ordinary, Loc, FPOptions());
 
   // Create the pre-increment of the iteration variable.
   Expr *Increment
@@ -10887,62 +11143,6 @@ buildSingleCopyAssign(Sema &S, SourceLocation Loc, QualType T,
   return Result;
 }
 
-Sema::ImplicitExceptionSpecification
-Sema::ComputeDefaultedCopyAssignmentExceptionSpec(CXXMethodDecl *MD) {
-  CXXRecordDecl *ClassDecl = MD->getParent();
-
-  ImplicitExceptionSpecification ExceptSpec(*this);
-  if (ClassDecl->isInvalidDecl())
-    return ExceptSpec;
-
-  const FunctionProtoType *T = MD->getType()->castAs<FunctionProtoType>();
-  assert(T->getNumParams() == 1 && "not a copy assignment op");
-  unsigned ArgQuals =
-      T->getParamType(0).getNonReferenceType().getCVRQualifiers();
-
-  // C++ [except.spec]p14:
-  //   An implicitly declared special member function (Clause 12) shall have an
-  //   exception-specification. [...]
-
-  // It is unspecified whether or not an implicit copy assignment operator
-  // attempts to deduplicate calls to assignment operators of virtual bases are
-  // made. As such, this exception specification is effectively unspecified.
-  // Based on a similar decision made for constness in C++0x, we're erring on
-  // the side of assuming such calls to be made regardless of whether they
-  // actually happen.
-  for (const auto &Base : ClassDecl->bases()) {
-    if (Base.isVirtual())
-      continue;
-
-    CXXRecordDecl *BaseClassDecl
-      = cast<CXXRecordDecl>(Base.getType()->getAs<RecordType>()->getDecl());
-    if (CXXMethodDecl *CopyAssign = LookupCopyingAssignment(BaseClassDecl,
-                                                            ArgQuals, false, 0))
-      ExceptSpec.CalledDecl(Base.getLocStart(), CopyAssign);
-  }
-
-  for (const auto &Base : ClassDecl->vbases()) {
-    CXXRecordDecl *BaseClassDecl
-      = cast<CXXRecordDecl>(Base.getType()->getAs<RecordType>()->getDecl());
-    if (CXXMethodDecl *CopyAssign = LookupCopyingAssignment(BaseClassDecl,
-                                                            ArgQuals, false, 0))
-      ExceptSpec.CalledDecl(Base.getLocStart(), CopyAssign);
-  }
-
-  for (const auto *Field : ClassDecl->fields()) {
-    QualType FieldType = Context.getBaseElementType(Field->getType());
-    if (CXXRecordDecl *FieldClassDecl = FieldType->getAsCXXRecordDecl()) {
-      if (CXXMethodDecl *CopyAssign =
-          LookupCopyingAssignment(FieldClassDecl,
-                                  ArgQuals | FieldType.getCVRQualifiers(),
-                                  false, 0))
-        ExceptSpec.CalledDecl(Field->getLocation(), CopyAssign);
-    }
-  }
-
-  return ExceptSpec;
-}
-
 CXXMethodDecl *Sema::DeclareImplicitCopyAssignment(CXXRecordDecl *ClassDecl) {
   // Note: The following rules are largely analoguous to the copy
   // constructor rules. Note that virtual bases are not taken into account
@@ -11286,59 +11486,6 @@ void Sema::DefineImplicitCopyAssignment(SourceLocation CurrentLocation,
   }
 }
 
-Sema::ImplicitExceptionSpecification
-Sema::ComputeDefaultedMoveAssignmentExceptionSpec(CXXMethodDecl *MD) {
-  CXXRecordDecl *ClassDecl = MD->getParent();
-
-  ImplicitExceptionSpecification ExceptSpec(*this);
-  if (ClassDecl->isInvalidDecl())
-    return ExceptSpec;
-
-  // C++0x [except.spec]p14:
-  //   An implicitly declared special member function (Clause 12) shall have an 
-  //   exception-specification. [...]
-
-  // It is unspecified whether or not an implicit move assignment operator
-  // attempts to deduplicate calls to assignment operators of virtual bases are
-  // made. As such, this exception specification is effectively unspecified.
-  // Based on a similar decision made for constness in C++0x, we're erring on
-  // the side of assuming such calls to be made regardless of whether they
-  // actually happen.
-  // Note that a move constructor is not implicitly declared when there are
-  // virtual bases, but it can still be user-declared and explicitly defaulted.
-  for (const auto &Base : ClassDecl->bases()) {
-    if (Base.isVirtual())
-      continue;
-
-    CXXRecordDecl *BaseClassDecl
-      = cast<CXXRecordDecl>(Base.getType()->getAs<RecordType>()->getDecl());
-    if (CXXMethodDecl *MoveAssign = LookupMovingAssignment(BaseClassDecl,
-                                                           0, false, 0))
-      ExceptSpec.CalledDecl(Base.getLocStart(), MoveAssign);
-  }
-
-  for (const auto &Base : ClassDecl->vbases()) {
-    CXXRecordDecl *BaseClassDecl
-      = cast<CXXRecordDecl>(Base.getType()->getAs<RecordType>()->getDecl());
-    if (CXXMethodDecl *MoveAssign = LookupMovingAssignment(BaseClassDecl,
-                                                           0, false, 0))
-      ExceptSpec.CalledDecl(Base.getLocStart(), MoveAssign);
-  }
-
-  for (const auto *Field : ClassDecl->fields()) {
-    QualType FieldType = Context.getBaseElementType(Field->getType());
-    if (CXXRecordDecl *FieldClassDecl = FieldType->getAsCXXRecordDecl()) {
-      if (CXXMethodDecl *MoveAssign =
-              LookupMovingAssignment(FieldClassDecl,
-                                     FieldType.getCVRQualifiers(),
-                                     false, 0))
-        ExceptSpec.CalledDecl(Field->getLocation(), MoveAssign);
-    }
-  }
-
-  return ExceptSpec;
-}
-
 CXXMethodDecl *Sema::DeclareImplicitMoveAssignment(CXXRecordDecl *ClassDecl) {
   assert(ClassDecl->needsImplicitMoveAssignment());
 
@@ -11449,13 +11596,13 @@ static void checkMoveAssignmentForRepeatedMove(Sema &S, CXXRecordDecl *Class,
 
       // If we're not actually going to call a move assignment for this base,
       // or the selected move assignment is trivial, skip it.
-      Sema::SpecialMemberOverloadResult *SMOR =
+      Sema::SpecialMemberOverloadResult SMOR =
         S.LookupSpecialMember(Base, Sema::CXXMoveAssignment,
                               /*ConstArg*/false, /*VolatileArg*/false,
                               /*RValueThis*/true, /*ConstThis*/false,
                               /*VolatileThis*/false);
-      if (!SMOR->getMethod() || SMOR->getMethod()->isTrivial() ||
-          !SMOR->getMethod()->isMoveAssignmentOperator())
+      if (!SMOR.getMethod() || SMOR.getMethod()->isTrivial() ||
+          !SMOR.getMethod()->isMoveAssignmentOperator())
         continue;
 
       if (BaseSpec->isVirtual()) {
@@ -11486,7 +11633,7 @@ static void checkMoveAssignmentForRepeatedMove(Sema &S, CXXRecordDecl *Class,
         // Only walk over bases that have defaulted move assignment operators.
         // We assume that any user-provided move assignment operator handles
         // the multiple-moves-of-vbase case itself somehow.
-        if (!SMOR->getMethod()->isDefaulted())
+        if (!SMOR.getMethod()->isDefaulted())
           continue;
 
         // We're going to move the base classes of Base. Add them to the list.
@@ -11723,52 +11870,6 @@ void Sema::DefineImplicitMoveAssignment(SourceLocation CurrentLocation,
   }
 }
 
-Sema::ImplicitExceptionSpecification
-Sema::ComputeDefaultedCopyCtorExceptionSpec(CXXMethodDecl *MD) {
-  CXXRecordDecl *ClassDecl = MD->getParent();
-
-  ImplicitExceptionSpecification ExceptSpec(*this);
-  if (ClassDecl->isInvalidDecl())
-    return ExceptSpec;
-
-  const FunctionProtoType *T = MD->getType()->castAs<FunctionProtoType>();
-  assert(T->getNumParams() >= 1 && "not a copy ctor");
-  unsigned Quals = T->getParamType(0).getNonReferenceType().getCVRQualifiers();
-
-  // C++ [except.spec]p14:
-  //   An implicitly declared special member function (Clause 12) shall have an 
-  //   exception-specification. [...]
-  for (const auto &Base : ClassDecl->bases()) {
-    // Virtual bases are handled below.
-    if (Base.isVirtual())
-      continue;
-    
-    CXXRecordDecl *BaseClassDecl
-      = cast<CXXRecordDecl>(Base.getType()->getAs<RecordType>()->getDecl());
-    if (CXXConstructorDecl *CopyConstructor =
-          LookupCopyingConstructor(BaseClassDecl, Quals))
-      ExceptSpec.CalledDecl(Base.getLocStart(), CopyConstructor);
-  }
-  for (const auto &Base : ClassDecl->vbases()) {
-    CXXRecordDecl *BaseClassDecl
-      = cast<CXXRecordDecl>(Base.getType()->getAs<RecordType>()->getDecl());
-    if (CXXConstructorDecl *CopyConstructor =
-          LookupCopyingConstructor(BaseClassDecl, Quals))
-      ExceptSpec.CalledDecl(Base.getLocStart(), CopyConstructor);
-  }
-  for (const auto *Field : ClassDecl->fields()) {
-    QualType FieldType = Context.getBaseElementType(Field->getType());
-    if (CXXRecordDecl *FieldClassDecl = FieldType->getAsCXXRecordDecl()) {
-      if (CXXConstructorDecl *CopyConstructor =
-              LookupCopyingConstructor(FieldClassDecl,
-                                       Quals | FieldType.getCVRQualifiers()))
-      ExceptSpec.CalledDecl(Field->getLocation(), CopyConstructor);
-    }
-  }
-
-  return ExceptSpec;
-}
-
 CXXConstructorDecl *Sema::DeclareImplicitCopyConstructor(
                                                     CXXRecordDecl *ClassDecl) {
   // C++ [class.copy]p4:
@@ -11896,65 +11997,6 @@ void Sema::DefineImplicitCopyConstructor(SourceLocation CurrentLocation,
   }
 }
 
-Sema::ImplicitExceptionSpecification
-Sema::ComputeDefaultedMoveCtorExceptionSpec(CXXMethodDecl *MD) {
-  CXXRecordDecl *ClassDecl = MD->getParent();
-
-  // C++ [except.spec]p14:
-  //   An implicitly declared special member function (Clause 12) shall have an 
-  //   exception-specification. [...]
-  ImplicitExceptionSpecification ExceptSpec(*this);
-  if (ClassDecl->isInvalidDecl())
-    return ExceptSpec;
-
-  // Direct base-class constructors.
-  for (const auto &B : ClassDecl->bases()) {
-    if (B.isVirtual()) // Handled below.
-      continue;
-    
-    if (const RecordType *BaseType = B.getType()->getAs<RecordType>()) {
-      CXXRecordDecl *BaseClassDecl = cast<CXXRecordDecl>(BaseType->getDecl());
-      CXXConstructorDecl *Constructor =
-          LookupMovingConstructor(BaseClassDecl, 0);
-      // If this is a deleted function, add it anyway. This might be conformant
-      // with the standard. This might not. I'm not sure. It might not matter.
-      if (Constructor)
-        ExceptSpec.CalledDecl(B.getLocStart(), Constructor);
-    }
-  }
-
-  // Virtual base-class constructors.
-  for (const auto &B : ClassDecl->vbases()) {
-    if (const RecordType *BaseType = B.getType()->getAs<RecordType>()) {
-      CXXRecordDecl *BaseClassDecl = cast<CXXRecordDecl>(BaseType->getDecl());
-      CXXConstructorDecl *Constructor =
-          LookupMovingConstructor(BaseClassDecl, 0);
-      // If this is a deleted function, add it anyway. This might be conformant
-      // with the standard. This might not. I'm not sure. It might not matter.
-      if (Constructor)
-        ExceptSpec.CalledDecl(B.getLocStart(), Constructor);
-    }
-  }
-
-  // Field constructors.
-  for (const auto *F : ClassDecl->fields()) {
-    QualType FieldType = Context.getBaseElementType(F->getType());
-    if (CXXRecordDecl *FieldRecDecl = FieldType->getAsCXXRecordDecl()) {
-      CXXConstructorDecl *Constructor =
-          LookupMovingConstructor(FieldRecDecl, FieldType.getCVRQualifiers());
-      // If this is a deleted function, add it anyway. This might be conformant
-      // with the standard. This might not. I'm not sure. It might not matter.
-      // In particular, the problem is that this function never gets called. It
-      // might just be ill-formed because this function attempts to refer to
-      // a deleted function here.
-      if (Constructor)
-        ExceptSpec.CalledDecl(F->getLocation(), Constructor);
-    }
-  }
-
-  return ExceptSpec;
-}
-
 CXXConstructorDecl *Sema::DeclareImplicitMoveConstructor(
                                                     CXXRecordDecl *ClassDecl) {
   assert(ClassDecl->needsImplicitMoveConstructor());
@@ -12198,7 +12240,7 @@ void Sema::DefineImplicitLambdaToBlockPointerConversion(
   // Set the body of the conversion function.
   Stmt *ReturnS = Return.get();
   Conv->setBody(new (Context) CompoundStmt(Context, ReturnS,
-                                           Conv->getLocation(), 
+                                           Conv->getLocation(),
                                            Conv->getLocation()));
   
   // We're done; notify the mutation listener, if any.
@@ -12750,7 +12792,7 @@ checkLiteralOperatorTemplateParameterList(Sema &SemaRef,
           PmArgs->getType()->getAs<TemplateTypeParmType>();
       if (TArgs && TArgs->getDepth() == PmType->getDepth() &&
           TArgs->getIndex() == PmType->getIndex()) {
-        if (SemaRef.ActiveTemplateInstantiations.empty())
+        if (!SemaRef.inTemplateInstantiation())
           SemaRef.Diag(TpDecl->getLocation(),
                        diag::ext_string_literal_operator_template);
         return false;
@@ -13076,7 +13118,8 @@ VarDecl *Sema::BuildExceptionDeclaration(Scope *S,
   if (!Invalid && !ExDeclType->isDependentType()) {
     if (const RecordType *recordType = ExDeclType->getAs<RecordType>()) {
       // Insulate this from anything else we might currently be parsing.
-      EnterExpressionEvaluationContext scope(*this, PotentiallyEvaluated);
+      EnterExpressionEvaluationContext scope(
+          *this, ExpressionEvaluationContext::PotentiallyEvaluated);
 
       // C++ [except.handle]p16:
       //   The object declared in an exception-declaration or, if the
@@ -13245,10 +13288,10 @@ FriendDecl *Sema::CheckFriendTypeDecl(SourceLocation LocStart,
   //   for a class.*
   //
   //   * The class-key of the elaborated-type-specifier is required.
-  if (!ActiveTemplateInstantiations.empty()) {
-    // Do not complain about the form of friend template types during
-    // template instantiation; we will already have complained when the
-    // template was declared.
+  if (!CodeSynthesisContexts.empty()) {
+    // Do not complain about the form of friend template types during any kind
+    // of code synthesis. For template instantiation, we will have complained
+    // when the template was defined.
   } else {
     if (!T->isElaboratedTypeSpecifier()) {
       // If we evaluated the type to a record type, suggest putting
@@ -13313,13 +13356,13 @@ Decl *Sema::ActOnTemplatedFriendTag(Scope *S, SourceLocation FriendLoc,
                                     MultiTemplateParamsArg TempParamLists) {
   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
 
-  bool isExplicitSpecialization = false;
+  bool IsMemberSpecialization = false;
   bool Invalid = false;
 
   if (TemplateParameterList *TemplateParams =
           MatchTemplateParametersToScopeSpecifier(
               TagLoc, NameLoc, SS, nullptr, TempParamLists, /*friend*/ true,
-              isExplicitSpecialization, Invalid)) {
+              IsMemberSpecialization, Invalid)) {
     if (TemplateParams->size() > 0) {
       // This is a declaration of a class template.
       if (Invalid)
@@ -13334,7 +13377,7 @@ Decl *Sema::ActOnTemplatedFriendTag(Scope *S, SourceLocation FriendLoc,
       // The "template<>" header is extraneous.
       Diag(TemplateParams->getTemplateLoc(), diag::err_template_tag_noparams)
         << TypeWithKeyword::getTagTypeKindName(Kind) << Name;
-      isExplicitSpecialization = true;
+      IsMemberSpecialization = true;
     }
   }
 
@@ -13744,6 +13787,9 @@ NamedDecl *Sema::ActOnFriendFunctionDecl(Scope *S, Declarator &D,
     case UnqualifiedId::IK_ConversionFunctionId:
       DiagArg = 2;
       break;
+    case UnqualifiedId::IK_DeductionGuideName:
+      DiagArg = 3;
+      break;
     case UnqualifiedId::IK_Identifier:
     case UnqualifiedId::IK_ImplicitSelfParam:
     case UnqualifiedId::IK_LiteralOperatorId:
@@ -14157,7 +14203,8 @@ void Sema::ActOnCXXEnterDeclInitializer(Scope *S, Decl *D) {
   // new expression evaluation context that is associated with this static
   // data member.
   if (isStaticDataMember(D))
-    PushExpressionEvaluationContext(PotentiallyEvaluated, D);
+    PushExpressionEvaluationContext(
+        ExpressionEvaluationContext::PotentiallyEvaluated, D);
 }
 
 /// ActOnCXXExitDeclInitializer - Invoked after we are finished parsing an
diff --git a/lib/Sema/SemaDeclObjC.cpp b/lib/Sema/SemaDeclObjC.cpp
index b43e5b9e3278..e50f8b206779 100644
--- a/lib/Sema/SemaDeclObjC.cpp
+++ b/lib/Sema/SemaDeclObjC.cpp
@@ -258,7 +258,8 @@ static void DiagnoseObjCImplementedDeprecations(Sema &S,
       S.Diag(ND->getLocation(), diag::note_method_declared_at)
         << ND->getDeclName();
     else
-      S.Diag(ND->getLocation(), diag::note_previous_decl) << "class";
+      S.Diag(ND->getLocation(), diag::note_previous_decl)
+          << (isa<ObjCCategoryDecl>(ND) ? "category" : "class");
   }
 }
 
@@ -1724,7 +1725,8 @@ ActOnStartCategoryInterface(SourceLocation AtInterfaceLoc,
                             Decl * const *ProtoRefs,
                             unsigned NumProtoRefs,
                             const SourceLocation *ProtoLocs,
-                            SourceLocation EndProtoLoc) {
+                            SourceLocation EndProtoLoc,
+                            AttributeList *AttrList) {
   ObjCCategoryDecl *CDecl;
   ObjCInterfaceDecl *IDecl = getObjCInterfaceDecl(ClassName, ClassLoc, true);
 
@@ -1801,6 +1803,9 @@ ActOnStartCategoryInterface(SourceLocation AtInterfaceLoc,
                                             NumProtoRefs, Context); 
   }
 
+  if (AttrList)
+    ProcessDeclAttributeList(TUScope, CDecl, AttrList);
+
   CheckObjCDeclScope(CDecl);
   return ActOnObjCContainerStartDefinition(CDecl);
 }
@@ -1865,9 +1870,10 @@ Decl *Sema::ActOnStartCategoryImplementation(
       CatIDecl->setImplementation(CDecl);
       // Warn on implementating category of deprecated class under 
       // -Wdeprecated-implementations flag.
-      DiagnoseObjCImplementedDeprecations(*this, 
-                                          dyn_cast<NamedDecl>(IDecl), 
-                                          CDecl->getLocation(), 2);
+      DiagnoseObjCImplementedDeprecations(
+          *this,
+          CatIDecl->isDeprecated() ? CatIDecl : dyn_cast<NamedDecl>(IDecl),
+          CDecl->getLocation(), 2);
     }
   }
 
diff --git a/lib/Sema/SemaExceptionSpec.cpp b/lib/Sema/SemaExceptionSpec.cpp
index 2ac2aca6f660..deb6cbb53aff 100644
--- a/lib/Sema/SemaExceptionSpec.cpp
+++ b/lib/Sema/SemaExceptionSpec.cpp
@@ -1182,6 +1182,7 @@ CanThrowResult Sema::canThrow(const Expr *E) {
   case Expr::ArraySubscriptExprClass:
   case Expr::OMPArraySectionExprClass:
   case Expr::BinaryOperatorClass:
+  case Expr::DependentCoawaitExprClass:
   case Expr::CompoundAssignOperatorClass:
   case Expr::CStyleCastExprClass:
   case Expr::CXXStaticCastExprClass:
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 0077d6c539c3..bb174521c72c 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -333,10 +333,8 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *D, SourceLocation Loc,
       Diag(Loc, diag::err_binding_cannot_appear_in_own_initializer)
         << D->getDeclName();
     } else {
-      const AutoType *AT = cast<VarDecl>(D)->getType()->getContainedAutoType();
-
       Diag(Loc, diag::err_auto_variable_cannot_appear_in_own_initializer)
-        << D->getDeclName() << (unsigned)AT->getKeyword();
+        << D->getDeclName() << cast<VarDecl>(D)->getType();
     }
     return true;
   }
@@ -706,8 +704,7 @@ ExprResult Sema::DefaultLvalueConversion(Expr *E) {
   
   // Loading a __weak object implicitly retains the value, so we need a cleanup to 
   // balance that.
-  if (getLangOpts().ObjCAutoRefCount &&
-      E->getType().getObjCLifetime() == Qualifiers::OCL_Weak)
+  if (E->getType().getObjCLifetime() == Qualifiers::OCL_Weak)
     Cleanup.setExprNeedsCleanups(true);
 
   ExprResult Res = ImplicitCastExpr::Create(Context, T, CK_LValueToRValue, E,
@@ -1434,7 +1431,8 @@ Sema::CreateGenericSelectionExpr(SourceLocation KeyLoc,
   // Decay and strip qualifiers for the controlling expression type, and handle
   // placeholder type replacement. See committee discussion from WG14 DR423.
   {
-    EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+    EnterExpressionEvaluationContext Unevaluated(
+        *this, Sema::ExpressionEvaluationContext::Unevaluated);
     ExprResult R = DefaultFunctionArrayLvalueConversion(ControllingExpr);
     if (R.isInvalid())
       return ExprError();
@@ -1443,7 +1441,7 @@ Sema::CreateGenericSelectionExpr(SourceLocation KeyLoc,
 
   // The controlling expression is an unevaluated operand, so side effects are
   // likely unintended.
-  if (ActiveTemplateInstantiations.empty() &&
+  if (!inTemplateInstantiation() &&
       ControllingExpr->HasSideEffects(Context, false))
     Diag(ControllingExpr->getExprLoc(),
          diag::warn_side_effects_unevaluated_context);
@@ -1774,7 +1772,10 @@ Sema::BuildDeclRefExpr(ValueDecl *D, QualType Ty, ExprValueKind VK,
       !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, E->getLocStart()))
       recordUseOfEvaluatedWeak(E);
 
-  if (FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
+  FieldDecl *FD = dyn_cast<FieldDecl>(D);
+  if (IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(D))
+    FD = IFD->getAnonField();
+  if (FD) {
     UnusedPrivateFields.remove(FD);
     // Just in case we're building an illegal pointer-to-member.
     if (FD->isBitField())
@@ -1890,9 +1891,10 @@ Sema::DiagnoseEmptyLookup(Scope *S, CXXScopeSpec &SS, LookupResult &R,
         // During a default argument instantiation the CurContext points
         // to a CXXMethodDecl; but we can't apply a this-> fixit inside a
         // function parameter list, hence add an explicit check.
-        bool isDefaultArgument = !ActiveTemplateInstantiations.empty() &&
-                              ActiveTemplateInstantiations.back().Kind ==
-            ActiveTemplateInstantiation::DefaultFunctionArgumentInstantiation;
+        bool isDefaultArgument =
+            !CodeSynthesisContexts.empty() &&
+            CodeSynthesisContexts.back().Kind ==
+                CodeSynthesisContext::DefaultFunctionArgumentInstantiation;
         CXXMethodDecl *CurMethod = dyn_cast<CXXMethodDecl>(CurContext);
         bool isInstance = CurMethod &&
                           CurMethod->isInstance() &&
@@ -2510,11 +2512,11 @@ Sema::LookupInObjCMethod(LookupResult &Lookup, Scope *S,
           ObjCIvarRefExpr(IV, IV->getUsageType(SelfExpr.get()->getType()), Loc,
                           IV->getLocation(), SelfExpr.get(), true, true);
 
+      if (IV->getType().getObjCLifetime() == Qualifiers::OCL_Weak) {
+        if (!Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, Loc))
+          recordUseOfEvaluatedWeak(Result);
+      }
       if (getLangOpts().ObjCAutoRefCount) {
-        if (IV->getType().getObjCLifetime() == Qualifiers::OCL_Weak) {
-          if (!Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, Loc))
-            recordUseOfEvaluatedWeak(Result);
-        }
         if (CurContext->isClosure())
           Diag(Loc, diag::warn_implicitly_retains_self)
             << FixItHint::CreateInsertion(Loc, "self->");
@@ -3038,6 +3040,9 @@ ExprResult Sema::BuildDeclarationNameExpr(
       break;
     }
 
+    case Decl::CXXDeductionGuide:
+      llvm_unreachable("building reference to deduction guide");
+
     case Decl::MSProperty:
       valueKind = VK_LValue;
       break;
@@ -3694,7 +3699,7 @@ bool Sema::CheckUnaryExprOrTypeTraitOperand(Expr *E,
   // The operand for sizeof and alignof is in an unevaluated expression context,
   // so side effects could result in unintended consequences.
   if ((ExprKind == UETT_SizeOf || ExprKind == UETT_AlignOf) &&
-      ActiveTemplateInstantiations.empty() && E->HasSideEffects(Context, false))
+      !inTemplateInstantiation() && E->HasSideEffects(Context, false))
     Diag(E->getExprLoc(), diag::warn_side_effects_unevaluated_context);
 
   if (CheckObjCTraitOperandConstraints(*this, ExprTy, E->getExprLoc(),
@@ -3969,7 +3974,8 @@ static void captureVariablyModifiedType(ASTContext &Context, QualType T,
       T = cast<DecltypeType>(Ty)->desugar();
       break;
     case Type::Auto:
-      T = cast<AutoType>(Ty)->getDeducedType();
+    case Type::DeducedTemplateSpecialization:
+      T = cast<DeducedType>(Ty)->getDeducedType();
       break;
     case Type::TypeOfExpr:
       T = cast<TypeOfExprType>(Ty)->getUnderlyingExpr()->getType();
@@ -4553,8 +4559,8 @@ bool Sema::CheckCXXDefaultArgExpr(SourceLocation CallLoc, FunctionDecl *FD,
   if (Param->hasUninstantiatedDefaultArg()) {
     Expr *UninstExpr = Param->getUninstantiatedDefaultArg();
 
-    EnterExpressionEvaluationContext EvalContext(*this, PotentiallyEvaluated,
-                                                 Param);
+    EnterExpressionEvaluationContext EvalContext(
+        *this, ExpressionEvaluationContext::PotentiallyEvaluated, Param);
 
     // Instantiate the expression.
     MultiLevelTemplateArgumentList MutiLevelArgList
@@ -5378,6 +5384,15 @@ Sema::BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
     return ExprError();
   }
 
+  // Interrupt handlers don't save off the VFP regs automatically on ARM,
+  // so there's some risk when calling out to non-interrupt handler functions
+  // that the callee might not preserve them. This is easy to diagnose here,
+  // but can be very challenging to debug.
+  if (auto *Caller = getCurFunctionDecl())
+    if (Caller->hasAttr<ARMInterruptAttr>())
+      if (!FDecl || !FDecl->hasAttr<ARMInterruptAttr>())
+        Diag(Fn->getExprLoc(), diag::warn_arm_interrupt_calling_convention);
+
   // Promote the function operand.
   // We special-case function promotion here because we only allow promoting
   // builtin functions to function pointers in the callee of a call.
@@ -6323,92 +6338,98 @@ static QualType checkConditionalPointerCompatibility(Sema &S, ExprResult &LHS,
   Qualifiers lhQual = lhptee.getQualifiers();
   Qualifiers rhQual = rhptee.getQualifiers();
 
+  unsigned ResultAddrSpace = 0;
+  unsigned LAddrSpace = lhQual.getAddressSpace();
+  unsigned RAddrSpace = rhQual.getAddressSpace();
+  if (S.getLangOpts().OpenCL) {
+    // OpenCL v1.1 s6.5 - Conversion between pointers to distinct address
+    // spaces is disallowed.
+    if (lhQual.isAddressSpaceSupersetOf(rhQual))
+      ResultAddrSpace = LAddrSpace;
+    else if (rhQual.isAddressSpaceSupersetOf(lhQual))
+      ResultAddrSpace = RAddrSpace;
+    else {
+      S.Diag(Loc,
+             diag::err_typecheck_op_on_nonoverlapping_address_space_pointers)
+          << LHSTy << RHSTy << 2 << LHS.get()->getSourceRange()
+          << RHS.get()->getSourceRange();
+      return QualType();
+    }
+  }
+
   unsigned MergedCVRQual = lhQual.getCVRQualifiers() | rhQual.getCVRQualifiers();
+  auto LHSCastKind = CK_BitCast, RHSCastKind = CK_BitCast;
   lhQual.removeCVRQualifiers();
   rhQual.removeCVRQualifiers();
 
+  // OpenCL v2.0 specification doesn't extend compatibility of type qualifiers
+  // (C99 6.7.3) for address spaces. We assume that the check should behave in
+  // the same manner as it's defined for CVR qualifiers, so for OpenCL two
+  // qual types are compatible iff
+  //  * corresponded types are compatible
+  //  * CVR qualifiers are equal
+  //  * address spaces are equal
+  // Thus for conditional operator we merge CVR and address space unqualified
+  // pointees and if there is a composite type we return a pointer to it with
+  // merged qualifiers.
+  if (S.getLangOpts().OpenCL) {
+    LHSCastKind = LAddrSpace == ResultAddrSpace
+                      ? CK_BitCast
+                      : CK_AddressSpaceConversion;
+    RHSCastKind = RAddrSpace == ResultAddrSpace
+                      ? CK_BitCast
+                      : CK_AddressSpaceConversion;
+    lhQual.removeAddressSpace();
+    rhQual.removeAddressSpace();
+  }
+
   lhptee = S.Context.getQualifiedType(lhptee.getUnqualifiedType(), lhQual);
   rhptee = S.Context.getQualifiedType(rhptee.getUnqualifiedType(), rhQual);
 
-  // For OpenCL:
-  // 1. If LHS and RHS types match exactly and:
-  //  (a) AS match => use standard C rules, no bitcast or addrspacecast
-  //  (b) AS overlap => generate addrspacecast
-  //  (c) AS don't overlap => give an error
-  // 2. if LHS and RHS types don't match:
-  //  (a) AS match => use standard C rules, generate bitcast
-  //  (b) AS overlap => generate addrspacecast instead of bitcast
-  //  (c) AS don't overlap => give an error
-
-  // For OpenCL, non-null composite type is returned only for cases 1a and 1b.
   QualType CompositeTy = S.Context.mergeTypes(lhptee, rhptee);
 
-  // OpenCL cases 1c, 2a, 2b, and 2c.
   if (CompositeTy.isNull()) {
     // In this situation, we assume void* type. No especially good
     // reason, but this is what gcc does, and we do have to pick
     // to get a consistent AST.
     QualType incompatTy;
-    if (S.getLangOpts().OpenCL) {
-      // OpenCL v1.1 s6.5 - Conversion between pointers to distinct address
-      // spaces is disallowed.
-      unsigned ResultAddrSpace;
-      if (lhQual.isAddressSpaceSupersetOf(rhQual)) {
-        // Cases 2a and 2b.
-        ResultAddrSpace = lhQual.getAddressSpace();
-      } else if (rhQual.isAddressSpaceSupersetOf(lhQual)) {
-        // Cases 2a and 2b.
-        ResultAddrSpace = rhQual.getAddressSpace();
-      } else {
-        // Cases 1c and 2c.
-        S.Diag(Loc,
-               diag::err_typecheck_op_on_nonoverlapping_address_space_pointers)
-            << LHSTy << RHSTy << 2 << LHS.get()->getSourceRange()
-            << RHS.get()->getSourceRange();
-        return QualType();
-      }
-
-      // Continue handling cases 2a and 2b.
-      incompatTy = S.Context.getPointerType(
-          S.Context.getAddrSpaceQualType(S.Context.VoidTy, ResultAddrSpace));
-      LHS = S.ImpCastExprToType(LHS.get(), incompatTy,
-                                (lhQual.getAddressSpace() != ResultAddrSpace)
-                                    ? CK_AddressSpaceConversion /* 2b */
-                                    : CK_BitCast /* 2a */);
-      RHS = S.ImpCastExprToType(RHS.get(), incompatTy,
-                                (rhQual.getAddressSpace() != ResultAddrSpace)
-                                    ? CK_AddressSpaceConversion /* 2b */
-                                    : CK_BitCast /* 2a */);
-    } else {
-      S.Diag(Loc, diag::ext_typecheck_cond_incompatible_pointers)
-          << LHSTy << RHSTy << LHS.get()->getSourceRange()
-          << RHS.get()->getSourceRange();
-      incompatTy = S.Context.getPointerType(S.Context.VoidTy);
-      LHS = S.ImpCastExprToType(LHS.get(), incompatTy, CK_BitCast);
-      RHS = S.ImpCastExprToType(RHS.get(), incompatTy, CK_BitCast);
-    }
+    incompatTy = S.Context.getPointerType(
+        S.Context.getAddrSpaceQualType(S.Context.VoidTy, ResultAddrSpace));
+    LHS = S.ImpCastExprToType(LHS.get(), incompatTy, LHSCastKind);
+    RHS = S.ImpCastExprToType(RHS.get(), incompatTy, RHSCastKind);
+    // FIXME: For OpenCL the warning emission and cast to void* leaves a room
+    // for casts between types with incompatible address space qualifiers.
+    // For the following code the compiler produces casts between global and
+    // local address spaces of the corresponded innermost pointees:
+    // local int *global *a;
+    // global int *global *b;
+    // a = (0 ? a : b); // see C99 6.5.16.1.p1.
+    S.Diag(Loc, diag::ext_typecheck_cond_incompatible_pointers)
+        << LHSTy << RHSTy << LHS.get()->getSourceRange()
+        << RHS.get()->getSourceRange();
     return incompatTy;
   }
 
   // The pointer types are compatible.
-  QualType ResultTy = CompositeTy.withCVRQualifiers(MergedCVRQual);
-  auto LHSCastKind = CK_BitCast, RHSCastKind = CK_BitCast;
+  // In case of OpenCL ResultTy should have the address space qualifier
+  // which is a superset of address spaces of both the 2nd and the 3rd
+  // operands of the conditional operator.
+  QualType ResultTy = [&, ResultAddrSpace]() {
+    if (S.getLangOpts().OpenCL) {
+      Qualifiers CompositeQuals = CompositeTy.getQualifiers();
+      CompositeQuals.setAddressSpace(ResultAddrSpace);
+      return S.Context
+          .getQualifiedType(CompositeTy.getUnqualifiedType(), CompositeQuals)
+          .withCVRQualifiers(MergedCVRQual);
+    } else
+      return CompositeTy.withCVRQualifiers(MergedCVRQual);
+  }();
   if (IsBlockPointer)
     ResultTy = S.Context.getBlockPointerType(ResultTy);
   else {
-    // Cases 1a and 1b for OpenCL.
-    auto ResultAddrSpace = ResultTy.getQualifiers().getAddressSpace();
-    LHSCastKind = lhQual.getAddressSpace() == ResultAddrSpace
-                      ? CK_BitCast /* 1a */
-                      : CK_AddressSpaceConversion /* 1b */;
-    RHSCastKind = rhQual.getAddressSpace() == ResultAddrSpace
-                      ? CK_BitCast /* 1a */
-                      : CK_AddressSpaceConversion /* 1b */;
     ResultTy = S.Context.getPointerType(ResultTy);
   }
 
-  // For case 1a of OpenCL, S.ImpCastExprToType will not insert bitcast
-  // if the target type does not change.
   LHS = S.ImpCastExprToType(LHS.get(), ResultTy, LHSCastKind);
   RHS = S.ImpCastExprToType(RHS.get(), ResultTy, RHSCastKind);
   return ResultTy;
@@ -7378,10 +7399,31 @@ checkBlockPointerTypesForAssignment(Sema &S, QualType LHSType,
   Sema::AssignConvertType ConvTy = Sema::Compatible;
 
   // For blocks we enforce that qualifiers are identical.
-  if (lhptee.getLocalQualifiers() != rhptee.getLocalQualifiers())
+  Qualifiers LQuals = lhptee.getLocalQualifiers();
+  Qualifiers RQuals = rhptee.getLocalQualifiers();
+  if (S.getLangOpts().OpenCL) {
+    LQuals.removeAddressSpace();
+    RQuals.removeAddressSpace();
+  }
+  if (LQuals != RQuals)
     ConvTy = Sema::CompatiblePointerDiscardsQualifiers;
 
-  if (!S.Context.typesAreBlockPointerCompatible(LHSType, RHSType))
+  // FIXME: OpenCL doesn't define the exact compile time semantics for a block
+  // assignment.
+  // The current behavior is similar to C++ lambdas. A block might be
+  // assigned to a variable iff its return type and parameters are compatible
+  // (C99 6.2.7) with the corresponding return type and parameters of the LHS of
+  // an assignment. Presumably it should behave in way that a function pointer
+  // assignment does in C, so for each parameter and return type:
+  //  * CVR and address space of LHS should be a superset of CVR and address
+  //  space of RHS.
+  //  * unqualified types should be compatible.
+  if (S.getLangOpts().OpenCL) {
+    if (!S.Context.typesAreBlockPointerCompatible(
+            S.Context.getQualifiedType(LHSType.getUnqualifiedType(), LQuals),
+            S.Context.getQualifiedType(RHSType.getUnqualifiedType(), RQuals)))
+      return Sema::IncompatibleBlockPointer;
+  } else if (!S.Context.typesAreBlockPointerCompatible(LHSType, RHSType))
     return Sema::IncompatibleBlockPointer;
 
   return ConvTy;
@@ -7603,7 +7645,12 @@ Sema::CheckAssignmentConstraints(QualType LHSType, ExprResult &RHS,
     // U^ -> void*
     if (RHSType->getAs<BlockPointerType>()) {
       if (LHSPointer->getPointeeType()->isVoidType()) {
-        Kind = CK_BitCast;
+        unsigned AddrSpaceL = LHSPointer->getPointeeType().getAddressSpace();
+        unsigned AddrSpaceR = RHSType->getAs<BlockPointerType>()
+                                  ->getPointeeType()
+                                  .getAddressSpace();
+        Kind =
+            AddrSpaceL != AddrSpaceR ? CK_AddressSpaceConversion : CK_BitCast;
         return Compatible;
       }
     }
@@ -7615,7 +7662,13 @@ Sema::CheckAssignmentConstraints(QualType LHSType, ExprResult &RHS,
   if (isa<BlockPointerType>(LHSType)) {
     // U^ -> T^
     if (RHSType->isBlockPointerType()) {
-      Kind = CK_BitCast;
+      unsigned AddrSpaceL = LHSType->getAs<BlockPointerType>()
+                                ->getPointeeType()
+                                .getAddressSpace();
+      unsigned AddrSpaceR = RHSType->getAs<BlockPointerType>()
+                                ->getPointeeType()
+                                .getAddressSpace();
+      Kind = AddrSpaceL != AddrSpaceR ? CK_AddressSpaceConversion : CK_BitCast;
       return checkBlockPointerTypesForAssignment(*this, LHSType, RHSType);
     }
 
@@ -7648,7 +7701,7 @@ Sema::CheckAssignmentConstraints(QualType LHSType, ExprResult &RHS,
       Kind = CK_BitCast;
       Sema::AssignConvertType result = 
         checkObjCPointerTypesForAssignment(*this, LHSType, RHSType);
-      if (getLangOpts().ObjCAutoRefCount &&
+      if (getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() &&
           result == Compatible && 
           !CheckObjCARCUnavailableWeakConversion(OrigLHSType, RHSType))
         result = IncompatibleObjCWeakRef;
@@ -7855,7 +7908,7 @@ Sema::CheckSingleAssignmentConstraints(QualType LHSType, ExprResult &CallerRHS,
       if (RHS.isInvalid())
         return Incompatible;
       Sema::AssignConvertType result = Compatible;
-      if (getLangOpts().ObjCAutoRefCount &&
+      if (getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() &&
           !CheckObjCARCUnavailableWeakConversion(LHSType, RHSType))
         result = IncompatibleObjCWeakRef;
       return result;
@@ -7932,9 +7985,9 @@ Sema::CheckSingleAssignmentConstraints(QualType LHSType, ExprResult &CallerRHS,
     // Check for various Objective-C errors. If we are not reporting
     // diagnostics and just checking for errors, e.g., during overload
     // resolution, return Incompatible to indicate the failure.
-    if (getLangOpts().ObjCAutoRefCount &&
-        CheckObjCARCConversion(SourceRange(), Ty, E, CCK_ImplicitConversion,
-                               Diagnose, DiagnoseCFAudited) != ACR_okay) {
+    if (getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() &&
+        CheckObjCConversion(SourceRange(), Ty, E, CCK_ImplicitConversion,
+                            Diagnose, DiagnoseCFAudited) != ACR_okay) {
       if (!Diagnose)
         return Incompatible;
     }
@@ -8094,7 +8147,7 @@ QualType Sema::CheckVectorOperands(ExprResult &LHS, ExprResult &RHS,
       return RHSType;
   }
 
-  // FIXME: The code below also handles convertion between vectors and
+  // FIXME: The code below also handles conversion between vectors and
   // non-scalars, we should break this down into fine grained specific checks
   // and emit proper diagnostics.
   QualType VecType = LHSVecType ? LHSType : RHSType;
@@ -9231,7 +9284,7 @@ QualType Sema::CheckCompareOperands(ExprResult &LHS, ExprResult &RHS,
       !(LHSType->isBlockPointerType() && IsRelational) &&
       !LHS.get()->getLocStart().isMacroID() &&
       !RHS.get()->getLocStart().isMacroID() &&
-      ActiveTemplateInstantiations.empty()) {
+      !inTemplateInstantiation()) {
     // For non-floating point types, check for self-comparisons of the form
     // x == x, x != x, x < x, etc.  These always evaluate to a constant, and
     // often indicate logic errors in the program.
@@ -9374,7 +9427,10 @@ QualType Sema::CheckCompareOperands(ExprResult &LHS, ExprResult &RHS,
     //   If both operands are pointers, [...] bring them to their composite
     //   pointer type.
     if ((int)LHSType->isPointerType() + (int)RHSType->isPointerType() >=
-        (IsRelational ? 2 : 1)) {
+            (IsRelational ? 2 : 1) &&
+        (!LangOpts.ObjCAutoRefCount ||
+         !(LHSType->isObjCObjectPointerType() ||
+           RHSType->isObjCObjectPointerType()))) {
       if (convertPointersToCompositeType(*this, Loc, LHS, RHS))
         return QualType();
       else
@@ -9560,16 +9616,17 @@ QualType Sema::CheckCompareOperands(ExprResult &LHS, ExprResult &RHS,
       if (LHSIsNull && !RHSIsNull) {
         Expr *E = LHS.get();
         if (getLangOpts().ObjCAutoRefCount)
-          CheckObjCARCConversion(SourceRange(), RHSType, E, CCK_ImplicitConversion);
+          CheckObjCConversion(SourceRange(), RHSType, E,
+                              CCK_ImplicitConversion);
         LHS = ImpCastExprToType(E, RHSType,
                                 RPT ? CK_BitCast :CK_CPointerToObjCPointerCast);
       }
       else {
         Expr *E = RHS.get();
         if (getLangOpts().ObjCAutoRefCount)
-          CheckObjCARCConversion(SourceRange(), LHSType, E,
-                                 CCK_ImplicitConversion, /*Diagnose=*/true,
-                                 /*DiagnoseCFAudited=*/false, Opc);
+          CheckObjCConversion(SourceRange(), LHSType, E, CCK_ImplicitConversion,
+                              /*Diagnose=*/true,
+                              /*DiagnoseCFAudited=*/false, Opc);
         RHS = ImpCastExprToType(E, LHSType,
                                 LPT ? CK_BitCast :CK_CPointerToObjCPointerCast);
       }
@@ -9657,24 +9714,45 @@ QualType Sema::CheckCompareOperands(ExprResult &LHS, ExprResult &RHS,
   return InvalidOperands(Loc, LHS, RHS);
 }
 
-
-// Return a signed type that is of identical size and number of elements.
-// For floating point vectors, return an integer type of identical size 
-// and number of elements.
+// Return a signed ext_vector_type that is of identical size and number of
+// elements. For floating point vectors, return an integer type of identical
+// size and number of elements. In the non ext_vector_type case, search from
+// the largest type to the smallest type to avoid cases where long long == long,
+// where long gets picked over long long.
 QualType Sema::GetSignedVectorType(QualType V) {
   const VectorType *VTy = V->getAs<VectorType>();
   unsigned TypeSize = Context.getTypeSize(VTy->getElementType());
-  if (TypeSize == Context.getTypeSize(Context.CharTy))
-    return Context.getExtVectorType(Context.CharTy, VTy->getNumElements());
-  else if (TypeSize == Context.getTypeSize(Context.ShortTy))
-    return Context.getExtVectorType(Context.ShortTy, VTy->getNumElements());
-  else if (TypeSize == Context.getTypeSize(Context.IntTy))
-    return Context.getExtVectorType(Context.IntTy, VTy->getNumElements());
+
+  if (isa<ExtVectorType>(VTy)) {
+    if (TypeSize == Context.getTypeSize(Context.CharTy))
+      return Context.getExtVectorType(Context.CharTy, VTy->getNumElements());
+    else if (TypeSize == Context.getTypeSize(Context.ShortTy))
+      return Context.getExtVectorType(Context.ShortTy, VTy->getNumElements());
+    else if (TypeSize == Context.getTypeSize(Context.IntTy))
+      return Context.getExtVectorType(Context.IntTy, VTy->getNumElements());
+    else if (TypeSize == Context.getTypeSize(Context.LongTy))
+      return Context.getExtVectorType(Context.LongTy, VTy->getNumElements());
+    assert(TypeSize == Context.getTypeSize(Context.LongLongTy) &&
+           "Unhandled vector element size in vector compare");
+    return Context.getExtVectorType(Context.LongLongTy, VTy->getNumElements());
+  }
+
+  if (TypeSize == Context.getTypeSize(Context.LongLongTy))
+    return Context.getVectorType(Context.LongLongTy, VTy->getNumElements(),
+                                 VectorType::GenericVector);
   else if (TypeSize == Context.getTypeSize(Context.LongTy))
-    return Context.getExtVectorType(Context.LongTy, VTy->getNumElements());
-  assert(TypeSize == Context.getTypeSize(Context.LongLongTy) &&
+    return Context.getVectorType(Context.LongTy, VTy->getNumElements(),
+                                 VectorType::GenericVector);
+  else if (TypeSize == Context.getTypeSize(Context.IntTy))
+    return Context.getVectorType(Context.IntTy, VTy->getNumElements(),
+                                 VectorType::GenericVector);
+  else if (TypeSize == Context.getTypeSize(Context.ShortTy))
+    return Context.getVectorType(Context.ShortTy, VTy->getNumElements(),
+                                 VectorType::GenericVector);
+  assert(TypeSize == Context.getTypeSize(Context.CharTy) &&
          "Unhandled vector element size in vector compare");
-  return Context.getExtVectorType(Context.LongLongTy, VTy->getNumElements());
+  return Context.getVectorType(Context.CharTy, VTy->getNumElements(),
+                               VectorType::GenericVector);
 }
 
 /// CheckVectorCompareOperands - vector comparisons are a clang extension that
@@ -9703,8 +9781,7 @@ QualType Sema::CheckVectorCompareOperands(ExprResult &LHS, ExprResult &RHS,
   // For non-floating point types, check for self-comparisons of the form
   // x == x, x != x, x < x, etc.  These always evaluate to a constant, and
   // often indicate logic errors in the program.
-  if (!LHSType->hasFloatingRepresentation() &&
-      ActiveTemplateInstantiations.empty()) {
+  if (!LHSType->hasFloatingRepresentation() && !inTemplateInstantiation()) {
     if (DeclRefExpr* DRL
           = dyn_cast<DeclRefExpr>(LHS.get()->IgnoreParenImpCasts()))
       if (DeclRefExpr* DRR
@@ -9722,7 +9799,7 @@ QualType Sema::CheckVectorCompareOperands(ExprResult &LHS, ExprResult &RHS,
     assert (RHS.get()->getType()->hasFloatingRepresentation());
     CheckFloatComparison(Loc, LHS.get(), RHS.get());
   }
-  
+
   // Return a signed type for the vector.
   return GetSignedVectorType(vType);
 }
@@ -9739,7 +9816,7 @@ QualType Sema::CheckVectorLogicalOperands(ExprResult &LHS, ExprResult &RHS,
   if (getLangOpts().OpenCL && getLangOpts().OpenCLVersion < 120 &&
       vType->hasFloatingRepresentation())
     return InvalidOperands(Loc, LHS, RHS);
-  
+
   return GetSignedVectorType(LHS.get()->getType());
 }
 
@@ -9792,7 +9869,7 @@ inline QualType Sema::CheckLogicalOperands(ExprResult &LHS, ExprResult &RHS,
       !LHS.get()->getType()->isBooleanType() &&
       RHS.get()->getType()->isIntegerType() && !RHS.get()->isValueDependent() &&
       // Don't warn in macros or template instantiations.
-      !Loc.isMacroID() && ActiveTemplateInstantiations.empty()) {
+      !Loc.isMacroID() && !inTemplateInstantiation()) {
     // If the RHS can be constant folded, and if it constant folds to something
     // that isn't 0 or 1 (which indicate a potential logical operation that
     // happened to fold to true/false) then warn.
@@ -10268,7 +10345,10 @@ QualType Sema::CheckAssignmentOperands(Expr *LHSExpr, ExprResult &RHS,
         const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(InnerLHS);
         if (!DRE || DRE->getDecl()->hasAttr<BlocksAttr>())
           checkRetainCycles(LHSExpr, RHS.get());
+      }
 
+      if (LHSType.getObjCLifetime() == Qualifiers::OCL_Strong ||
+          LHSType.isNonWeakInMRRWithObjCWeak(Context)) {
         // It is safe to assign a weak reference into a strong variable.
         // Although this code can still have problems:
         //   id x = self.weakProp;
@@ -10276,11 +10356,13 @@ QualType Sema::CheckAssignmentOperands(Expr *LHSExpr, ExprResult &RHS,
         // we do not warn to warn spuriously when 'x' and 'y' are on separate
         // paths through the function. This should be revisited if
         // -Wrepeated-use-of-weak is made flow-sensitive.
+        // For ObjCWeak only, we do not warn if the assign is to a non-weak
+        // variable, which will be valid for the current autorelease scope.
         if (!Diags.isIgnored(diag::warn_arc_repeated_use_of_weak,
                              RHS.get()->getLocStart()))
           getCurFunction()->markSafeWeakUse(RHS.get());
 
-      } else if (getLangOpts().ObjCAutoRefCount) {
+      } else if (getLangOpts().ObjCAutoRefCount || getLangOpts().ObjCWeak) {
         checkUnsafeExprAssigns(Loc, LHSExpr, RHS.get());
       }
     }
@@ -10328,7 +10410,7 @@ void Sema::DiagnoseCommaOperator(const Expr *LHS, SourceLocation Loc) {
     return;
 
   // Don't warn in template instantiations.
-  if (!ActiveTemplateInstantiations.empty())
+  if (inTemplateInstantiation())
     return;
 
   // Scope isn't fine-grained enough to whitelist the specific cases, so
@@ -10923,7 +11005,7 @@ static inline UnaryOperatorKind ConvertTokenKindToUnaryOpcode(
 /// suppressed in the event of macro expansions.
 static void DiagnoseSelfAssignment(Sema &S, Expr *LHSExpr, Expr *RHSExpr,
                                    SourceLocation OpLoc) {
-  if (!S.ActiveTemplateInstantiations.empty())
+  if (S.inTemplateInstantiation())
     return;
   if (OpLoc.isInvalid() || OpLoc.isMacroID())
     return;
@@ -11063,7 +11145,7 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
     if (LHSTy->isAtomicType() || RHSTy->isAtomicType()) {
       SourceRange SR(LHSExpr->getLocStart(), RHSExpr->getLocEnd());
       if (BO_Assign == Opc)
-        Diag(OpLoc, diag::err_atomic_init_constant) << SR;
+        Diag(OpLoc, diag::err_opencl_atomic_init) << 0 << SR;
       else
         ResultTy = InvalidOperands(OpLoc, LHS, RHS);
       return ExprError();
@@ -11212,7 +11294,7 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
   
   if (CompResultTy.isNull())
     return new (Context) BinaryOperator(LHS.get(), RHS.get(), Opc, ResultTy, VK,
-                                        OK, OpLoc, FPFeatures.fp_contract);
+                                        OK, OpLoc, FPFeatures);
   if (getLangOpts().CPlusPlus && LHS.get()->getObjectKind() !=
       OK_ObjCProperty) {
     VK = VK_LValue;
@@ -11220,7 +11302,7 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
   }
   return new (Context) CompoundAssignOperator(
       LHS.get(), RHS.get(), Opc, ResultTy, VK, OK, CompLHSTy, CompResultTy,
-      OpLoc, FPFeatures.fp_contract);
+      OpLoc, FPFeatures);
 }
 
 /// DiagnoseBitwisePrecedence - Emit a warning when bitwise and comparison
@@ -11659,7 +11741,7 @@ ExprResult Sema::CreateBuiltinUnaryOp(SourceLocation OpLoc,
                  Context.getLangOpts().OpenCLVersion < 120) {
         // OpenCL v1.1 6.3.h: The logical operator not (!) does not
         // operate on scalar float types.
-        if (!resultType->isIntegerType())
+        if (!resultType->isIntegerType() && !resultType->isPointerType())
           return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
                            << resultType << Input.get()->getSourceRange());
       }
@@ -12193,7 +12275,8 @@ void Sema::ActOnBlockStart(SourceLocation CaretLoc, Scope *CurScope) {
 
   // Enter a new evaluation context to insulate the block from any
   // cleanups from the enclosing full-expression.
-  PushExpressionEvaluationContext(PotentiallyEvaluated);  
+  PushExpressionEvaluationContext(
+      ExpressionEvaluationContext::PotentiallyEvaluated);
 }
 
 void Sema::ActOnBlockArguments(SourceLocation CaretLoc, Declarator &ParamInfo,
@@ -13086,7 +13169,7 @@ void Sema::PopExpressionEvaluationContext() {
   unsigned NumTypos = Rec.NumTypos;
 
   if (!Rec.Lambdas.empty()) {
-    if (Rec.isUnevaluated() || Rec.Context == ConstantEvaluated) {
+    if (Rec.isUnevaluated() || Rec.isConstantEvaluated()) {
       unsigned D;
       if (Rec.isUnevaluated()) {
         // C++11 [expr.prim.lambda]p2:
@@ -13107,7 +13190,7 @@ void Sema::PopExpressionEvaluationContext() {
       // are part of function-signatures.  Be mindful that P0315 (Lambdas in
       // unevaluated contexts) might lift some of these restrictions in a 
       // future version.
-      if (Rec.Context != ConstantEvaluated || !getLangOpts().CPlusPlus1z)
+      if (!Rec.isConstantEvaluated() || !getLangOpts().CPlusPlus1z)
         for (const auto *L : Rec.Lambdas)
           Diag(L->getLocStart(), D);
     } else {
@@ -13124,7 +13207,7 @@ void Sema::PopExpressionEvaluationContext() {
   // temporaries that we may have created as part of the evaluation of
   // the expression in that context: they aren't relevant because they
   // will never be constructed.
-  if (Rec.isUnevaluated() || Rec.Context == ConstantEvaluated) {
+  if (Rec.isUnevaluated() || Rec.isConstantEvaluated()) {
     ExprCleanupObjects.erase(ExprCleanupObjects.begin() + Rec.NumCleanupObjects,
                              ExprCleanupObjects.end());
     Cleanup = Rec.ParentCleanup;
@@ -13166,19 +13249,19 @@ ExprResult Sema::HandleExprEvaluationContextForTypeof(Expr *E) {
 /// captured by C++'s idea of an "unevaluated context".
 static bool isEvaluatableContext(Sema &SemaRef) {
   switch (SemaRef.ExprEvalContexts.back().Context) {
-    case Sema::Unevaluated:
-    case Sema::UnevaluatedAbstract:
-    case Sema::DiscardedStatement:
+    case Sema::ExpressionEvaluationContext::Unevaluated:
+    case Sema::ExpressionEvaluationContext::UnevaluatedAbstract:
+    case Sema::ExpressionEvaluationContext::DiscardedStatement:
       // Expressions in this context are never evaluated.
       return false;
 
-    case Sema::UnevaluatedList:
-    case Sema::ConstantEvaluated:
-    case Sema::PotentiallyEvaluated:
+    case Sema::ExpressionEvaluationContext::UnevaluatedList:
+    case Sema::ExpressionEvaluationContext::ConstantEvaluated:
+    case Sema::ExpressionEvaluationContext::PotentiallyEvaluated:
       // Expressions in this context could be evaluated.
       return true;
 
-    case Sema::PotentiallyEvaluatedIfUsed:
+    case Sema::ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
       // Referenced declarations will only be used if the construct in the
       // containing expression is used, at which point we'll be given another
       // turn to mark them.
@@ -13196,17 +13279,17 @@ static bool isOdrUseContext(Sema &SemaRef, bool SkipDependentUses = true) {
     return false;
 
   switch (SemaRef.ExprEvalContexts.back().Context) {
-    case Sema::Unevaluated:
-    case Sema::UnevaluatedList:
-    case Sema::UnevaluatedAbstract:
-    case Sema::DiscardedStatement:
+    case Sema::ExpressionEvaluationContext::Unevaluated:
+    case Sema::ExpressionEvaluationContext::UnevaluatedList:
+    case Sema::ExpressionEvaluationContext::UnevaluatedAbstract:
+    case Sema::ExpressionEvaluationContext::DiscardedStatement:
       return false;
 
-    case Sema::ConstantEvaluated:
-    case Sema::PotentiallyEvaluated:
+    case Sema::ExpressionEvaluationContext::ConstantEvaluated:
+    case Sema::ExpressionEvaluationContext::PotentiallyEvaluated:
       return true;
 
-    case Sema::PotentiallyEvaluatedIfUsed:
+    case Sema::ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
       return false;
   }
   llvm_unreachable("Invalid context");
@@ -13357,7 +13440,7 @@ void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func,
     if (!AlreadyInstantiated || Func->isConstexpr()) {
       if (isa<CXXRecordDecl>(Func->getDeclContext()) &&
           cast<CXXRecordDecl>(Func->getDeclContext())->isLocalClass() &&
-          ActiveTemplateInstantiations.size())
+          CodeSynthesisContexts.size())
         PendingLocalImplicitInstantiations.push_back(
             std::make_pair(Func, PointOfInstantiation));
       else if (Func->isConstexpr())
@@ -13540,6 +13623,13 @@ static bool isVariableCapturable(CapturingScopeInfo *CSI, VarDecl *Var,
     }
     return false;
   }
+  // OpenCL v2.0 s6.12.5: Blocks cannot reference/capture other blocks
+  if (S.getLangOpts().OpenCL && IsBlock &&
+      Var->getType()->isBlockPointerType()) {
+    if (Diagnose)
+      S.Diag(Loc, diag::err_opencl_block_ref_block);
+    return false;
+  }
 
   return true;
 }
@@ -13577,16 +13667,55 @@ static bool captureInBlock(BlockScopeInfo *BSI, VarDecl *Var,
   }
 
   // Warn about implicitly autoreleasing indirect parameters captured by blocks.
-  if (auto *PT = dyn_cast<PointerType>(CaptureType)) {
+  if (const auto *PT = CaptureType->getAs<PointerType>()) {
+    // This function finds out whether there is an AttributedType of kind
+    // attr_objc_ownership in Ty. The existence of AttributedType of kind
+    // attr_objc_ownership implies __autoreleasing was explicitly specified
+    // rather than being added implicitly by the compiler.
+    auto IsObjCOwnershipAttributedType = [](QualType Ty) {
+      while (const auto *AttrTy = Ty->getAs<AttributedType>()) {
+        if (AttrTy->getAttrKind() == AttributedType::attr_objc_ownership)
+          return true;
+
+        // Peel off AttributedTypes that are not of kind objc_ownership.
+        Ty = AttrTy->getModifiedType();
+      }
+
+      return false;
+    };
+
     QualType PointeeTy = PT->getPointeeType();
-    if (isa<ObjCObjectPointerType>(PointeeTy.getCanonicalType()) &&
+
+    if (PointeeTy->getAs<ObjCObjectPointerType>() &&
         PointeeTy.getObjCLifetime() == Qualifiers::OCL_Autoreleasing &&
-        !isa<AttributedType>(PointeeTy)) {
+        !IsObjCOwnershipAttributedType(PointeeTy)) {
       if (BuildAndDiagnose) {
         SourceLocation VarLoc = Var->getLocation();
         S.Diag(Loc, diag::warn_block_capture_autoreleasing);
-        S.Diag(VarLoc, diag::note_declare_parameter_autoreleasing) <<
-            FixItHint::CreateInsertion(VarLoc, "__autoreleasing");
+        {
+          auto AddAutoreleaseNote =
+              S.Diag(VarLoc, diag::note_declare_parameter_autoreleasing);
+          // Provide a fix-it for the '__autoreleasing' keyword at the
+          // appropriate location in the variable's type.
+          if (const auto *TSI = Var->getTypeSourceInfo()) {
+            PointerTypeLoc PTL =
+                TSI->getTypeLoc().getAsAdjusted<PointerTypeLoc>();
+            if (PTL) {
+              SourceLocation Loc = PTL.getPointeeLoc().getEndLoc();
+              Loc = Lexer::getLocForEndOfToken(Loc, 0, S.getSourceManager(),
+                                               S.getLangOpts());
+              if (Loc.isValid()) {
+                StringRef CharAtLoc = Lexer::getSourceText(
+                    CharSourceRange::getCharRange(Loc, Loc.getLocWithOffset(1)),
+                    S.getSourceManager(), S.getLangOpts());
+                AddAutoreleaseNote << FixItHint::CreateInsertion(
+                    Loc, CharAtLoc.empty() || !isWhitespace(CharAtLoc[0])
+                             ? " __autoreleasing "
+                             : " __autoreleasing");
+              }
+            }
+          }
+        }
         S.Diag(VarLoc, diag::note_declare_parameter_strong);
       }
     }
@@ -13615,7 +13744,8 @@ static bool captureInBlock(BlockScopeInfo *BSI, VarDecl *Var,
 
         // Enter a new evaluation context to insulate the copy
         // full-expression.
-        EnterExpressionEvaluationContext scope(S, S.PotentiallyEvaluated);
+        EnterExpressionEvaluationContext scope(
+            S, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
 
         // According to the blocks spec, the capture of a variable from
         // the stack requires a const copy constructor.  This is not true
@@ -13898,8 +14028,10 @@ bool Sema::tryCaptureVariable(
 
     // Check whether we've already captured it.
     if (isVariableAlreadyCapturedInScopeInfo(CSI, Var, Nested, CaptureType, 
-                                             DeclRefType)) 
+                                             DeclRefType)) {
+      CSI->getCapture(Var).markUsed(BuildAndDiagnose);
       break;
+    }
     // If we are instantiating a generic lambda call operator body, 
     // we do not want to capture new variables.  What was captured
     // during either a lambdas transformation or initial parsing
@@ -14227,8 +14359,9 @@ static void DoMarkVarDeclReferenced(Sema &SemaRef, SourceLocation Loc,
         (SemaRef.CurContext != Var->getDeclContext() &&
          Var->getDeclContext()->isFunctionOrMethod() && Var->hasLocalStorage());
     if (RefersToEnclosingScope) {
-      if (LambdaScopeInfo *const LSI =
-              SemaRef.getCurLambda(/*IgnoreCapturedRegions=*/true)) {
+      LambdaScopeInfo *const LSI =
+          SemaRef.getCurLambda(/*IgnoreNonLambdaCapturingScope=*/true);
+      if (LSI && !LSI->CallOperator->Encloses(Var->getDeclContext())) {
         // If a variable could potentially be odr-used, defer marking it so
         // until we finish analyzing the full expression for any
         // lvalue-to-rvalue
@@ -14363,7 +14496,8 @@ bool MarkReferencedDecls::TraverseTemplateArgument(
     const TemplateArgument &Arg) {
   {
     // A non-type template argument is a constant-evaluated context.
-    EnterExpressionEvaluationContext Evaluated(S, Sema::ConstantEvaluated);
+    EnterExpressionEvaluationContext Evaluated(
+        S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
     if (Arg.getKind() == TemplateArgument::Declaration) {
       if (Decl *D = Arg.getAsDecl())
         S.MarkAnyDeclReferenced(Loc, D, true);
@@ -14483,19 +14617,19 @@ void Sema::MarkDeclarationsReferencedInExpr(Expr *E,
 bool Sema::DiagRuntimeBehavior(SourceLocation Loc, const Stmt *Statement,
                                const PartialDiagnostic &PD) {
   switch (ExprEvalContexts.back().Context) {
-  case Unevaluated:
-  case UnevaluatedList:
-  case UnevaluatedAbstract:
-  case DiscardedStatement:
+  case ExpressionEvaluationContext::Unevaluated:
+  case ExpressionEvaluationContext::UnevaluatedList:
+  case ExpressionEvaluationContext::UnevaluatedAbstract:
+  case ExpressionEvaluationContext::DiscardedStatement:
     // The argument will never be evaluated, so don't complain.
     break;
 
-  case ConstantEvaluated:
+  case ExpressionEvaluationContext::ConstantEvaluated:
     // Relevant diagnostics should be produced by constant evaluation.
     break;
 
-  case PotentiallyEvaluated:
-  case PotentiallyEvaluatedIfUsed:
+  case ExpressionEvaluationContext::PotentiallyEvaluated:
+  case ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
     if (Statement && getCurFunctionOrMethodDecl()) {
       FunctionScopes.back()->PossiblyUnreachableDiags.
         push_back(sema::PossiblyUnreachableDiag(PD, Loc, Statement));
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 3afa95f7d1f2..d65570fcef76 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -323,20 +323,31 @@ ParsedType Sema::getDestructorName(SourceLocation TildeLoc,
   return nullptr;
 }
 
-ParsedType Sema::getDestructorType(const DeclSpec& DS, ParsedType ObjectType) {
-    if (DS.getTypeSpecType() == DeclSpec::TST_error || !ObjectType)
-      return nullptr;
-    assert(DS.getTypeSpecType() == DeclSpec::TST_decltype
-           && "only get destructor types from declspecs");
-    QualType T = BuildDecltypeType(DS.getRepAsExpr(), DS.getTypeSpecTypeLoc());
-    QualType SearchType = GetTypeFromParser(ObjectType);
-    if (SearchType->isDependentType() || Context.hasSameUnqualifiedType(SearchType, T)) {
-      return ParsedType::make(T);
-    }
+ParsedType Sema::getDestructorTypeForDecltype(const DeclSpec &DS,
+                                              ParsedType ObjectType) {
+  if (DS.getTypeSpecType() == DeclSpec::TST_error)
+    return nullptr;
+
+  if (DS.getTypeSpecType() == DeclSpec::TST_decltype_auto) {
+    Diag(DS.getTypeSpecTypeLoc(), diag::err_decltype_auto_invalid);
+    return nullptr;
+  }
+
+  assert(DS.getTypeSpecType() == DeclSpec::TST_decltype &&
+         "unexpected type in getDestructorType");
+  QualType T = BuildDecltypeType(DS.getRepAsExpr(), DS.getTypeSpecTypeLoc());
 
+  // If we know the type of the object, check that the correct destructor
+  // type was named now; we can give better diagnostics this way.
+  QualType SearchType = GetTypeFromParser(ObjectType);
+  if (!SearchType.isNull() && !SearchType->isDependentType() &&
+      !Context.hasSameUnqualifiedType(T, SearchType)) {
     Diag(DS.getTypeSpecTypeLoc(), diag::err_destructor_expr_type_mismatch)
       << T << SearchType;
     return nullptr;
+  }
+
+  return ParsedType::make(T);
 }
 
 bool Sema::checkLiteralOperatorId(const CXXScopeSpec &SS,
@@ -448,7 +459,7 @@ ExprResult Sema::BuildCXXTypeId(QualType TypeInfoType,
   if (E->getType()->isVariablyModifiedType())
     return ExprError(Diag(TypeidLoc, diag::err_variably_modified_typeid)
                      << E->getType());
-  else if (ActiveTemplateInstantiations.empty() &&
+  else if (!inTemplateInstantiation() &&
            E->HasSideEffects(Context, WasEvaluated)) {
     // The expression operand for typeid is in an unevaluated expression
     // context, so side effects could result in unintended consequences.
@@ -968,7 +979,7 @@ QualType Sema::getCurrentThisType() {
   }
 
   if (ThisTy.isNull() && isLambdaCallOperator(CurContext) &&
-      !ActiveTemplateInstantiations.empty()) {
+      inTemplateInstantiation()) {
 
     assert(isa<CXXRecordDecl>(DC) &&
            "Trying to get 'this' type from static method?");
@@ -1106,6 +1117,7 @@ bool Sema::CheckCXXThisCapture(SourceLocation Loc, const bool Explicit,
             dyn_cast<CapturingScopeInfo>(FunctionScopes[idx])) {
       if (CSI->CXXThisCaptureIndex != 0) {
         // 'this' is already being captured; there isn't anything more to do.
+        CSI->Captures[CSI->CXXThisCaptureIndex - 1].markUsed(BuildAndDiagnose);
         break;
       }
       LambdaScopeInfo *LSI = dyn_cast<LambdaScopeInfo>(CSI);
@@ -1216,17 +1228,6 @@ Sema::ActOnCXXTypeConstructExpr(ParsedType TypeRep,
   if (!TInfo)
     TInfo = Context.getTrivialTypeSourceInfo(Ty, SourceLocation());
 
-  // Handle errors like: int({0})
-  if (exprs.size() == 1 && !canInitializeWithParenthesizedList(Ty) &&
-      LParenLoc.isValid() && RParenLoc.isValid())
-    if (auto IList = dyn_cast<InitListExpr>(exprs[0])) {
-      Diag(TInfo->getTypeLoc().getLocStart(), diag::err_list_init_in_parens)
-          << Ty << IList->getSourceRange()
-          << FixItHint::CreateRemoval(LParenLoc)
-          << FixItHint::CreateRemoval(RParenLoc);
-      LParenLoc = RParenLoc = SourceLocation();
-    }
-
   auto Result = BuildCXXTypeConstructExpr(TInfo, LParenLoc, exprs, RParenLoc);
   // Avoid creating a non-type-dependent expression that contains typos.
   // Non-type-dependent expressions are liable to be discarded without
@@ -1255,58 +1256,79 @@ Sema::BuildCXXTypeConstructExpr(TypeSourceInfo *TInfo,
   }
 
   bool ListInitialization = LParenLoc.isInvalid();
-  assert((!ListInitialization || (Exprs.size() == 1 && isa<InitListExpr>(Exprs[0])))
-         && "List initialization must have initializer list as expression.");
+  assert((!ListInitialization ||
+          (Exprs.size() == 1 && isa<InitListExpr>(Exprs[0]))) &&
+         "List initialization must have initializer list as expression.");
   SourceRange FullRange = SourceRange(TyBeginLoc,
       ListInitialization ? Exprs[0]->getSourceRange().getEnd() : RParenLoc);
 
+  InitializedEntity Entity = InitializedEntity::InitializeTemporary(TInfo);
+  InitializationKind Kind =
+      Exprs.size()
+          ? ListInitialization
+                ? InitializationKind::CreateDirectList(TyBeginLoc)
+                : InitializationKind::CreateDirect(TyBeginLoc, LParenLoc,
+                                                   RParenLoc)
+          : InitializationKind::CreateValue(TyBeginLoc, LParenLoc, RParenLoc);
+
+  // C++1z [expr.type.conv]p1:
+  //   If the type is a placeholder for a deduced class type, [...perform class
+  //   template argument deduction...]
+  DeducedType *Deduced = Ty->getContainedDeducedType();
+  if (Deduced && isa<DeducedTemplateSpecializationType>(Deduced)) {
+    Ty = DeduceTemplateSpecializationFromInitializer(TInfo, Entity,
+                                                     Kind, Exprs);
+    if (Ty.isNull())
+      return ExprError();
+    Entity = InitializedEntity::InitializeTemporary(TInfo, Ty);
+  }
+
   // C++ [expr.type.conv]p1:
-  // If the expression list is a single expression, the type conversion
-  // expression is equivalent (in definedness, and if defined in meaning) to the
-  // corresponding cast expression.
-  if (Exprs.size() == 1 && !ListInitialization) {
+  // If the expression list is a parenthesized single expression, the type
+  // conversion expression is equivalent (in definedness, and if defined in
+  // meaning) to the corresponding cast expression.
+  if (Exprs.size() == 1 && !ListInitialization &&
+      !isa<InitListExpr>(Exprs[0])) {
     Expr *Arg = Exprs[0];
-    return BuildCXXFunctionalCastExpr(TInfo, LParenLoc, Arg, RParenLoc);
+    return BuildCXXFunctionalCastExpr(TInfo, Ty, LParenLoc, Arg, RParenLoc);
   }
 
-  // C++14 [expr.type.conv]p2: The expression T(), where T is a
-  //   simple-type-specifier or typename-specifier for a non-array complete
-  //   object type or the (possibly cv-qualified) void type, creates a prvalue
-  //   of the specified type, whose value is that produced by value-initializing
-  //   an object of type T.
+  //   For an expression of the form T(), T shall not be an array type.
   QualType ElemTy = Ty;
   if (Ty->isArrayType()) {
     if (!ListInitialization)
-      return ExprError(Diag(TyBeginLoc,
-                            diag::err_value_init_for_array_type) << FullRange);
+      return ExprError(Diag(TyBeginLoc, diag::err_value_init_for_array_type)
+                         << FullRange);
     ElemTy = Context.getBaseElementType(Ty);
   }
 
-  if (!ListInitialization && Ty->isFunctionType())
-    return ExprError(Diag(TyBeginLoc, diag::err_value_init_for_function_type)
-                     << FullRange);
+  // There doesn't seem to be an explicit rule against this but sanity demands
+  // we only construct objects with object types.
+  if (Ty->isFunctionType())
+    return ExprError(Diag(TyBeginLoc, diag::err_init_for_function_type)
+                       << Ty << FullRange);
 
+  // C++17 [expr.type.conv]p2:
+  //   If the type is cv void and the initializer is (), the expression is a
+  //   prvalue of the specified type that performs no initialization.
   if (!Ty->isVoidType() &&
       RequireCompleteType(TyBeginLoc, ElemTy,
                           diag::err_invalid_incomplete_type_use, FullRange))
     return ExprError();
 
-  InitializedEntity Entity = InitializedEntity::InitializeTemporary(TInfo);
-  InitializationKind Kind =
-      Exprs.size() ? ListInitialization
-      ? InitializationKind::CreateDirectList(TyBeginLoc)
-      : InitializationKind::CreateDirect(TyBeginLoc, LParenLoc, RParenLoc)
-      : InitializationKind::CreateValue(TyBeginLoc, LParenLoc, RParenLoc);
+  //   Otherwise, the expression is a prvalue of the specified type whose
+  //   result object is direct-initialized (11.6) with the initializer.
   InitializationSequence InitSeq(*this, Entity, Kind, Exprs);
   ExprResult Result = InitSeq.Perform(*this, Entity, Kind, Exprs);
 
-  if (Result.isInvalid() || !ListInitialization)
+  if (Result.isInvalid())
     return Result;
 
   Expr *Inner = Result.get();
   if (CXXBindTemporaryExpr *BTE = dyn_cast_or_null<CXXBindTemporaryExpr>(Inner))
     Inner = BTE->getSubExpr();
-  if (!isa<CXXTemporaryObjectExpr>(Inner)) {
+  if (!isa<CXXTemporaryObjectExpr>(Inner) &&
+      !isa<CXXScalarValueInitExpr>(Inner)) {
     // If we created a CXXTemporaryObjectExpr, that node also represents the
     // functional cast. Otherwise, create an explicit cast to represent
     // the syntactic form of a functional-style cast that was used here.
@@ -1317,7 +1339,7 @@ Sema::BuildCXXTypeConstructExpr(TypeSourceInfo *TInfo,
     // is sometimes handled by initialization and sometimes not.
     QualType ResultType = Result.get()->getType();
     Result = CXXFunctionalCastExpr::Create(
-        Context, ResultType, Expr::getValueKindForType(TInfo->getType()), TInfo,
+        Context, ResultType, Expr::getValueKindForType(Ty), TInfo,
         CK_NoOp, Result.get(), /*Path=*/nullptr, LParenLoc, RParenLoc);
   }
 
@@ -1509,7 +1531,7 @@ Sema::ActOnCXXNew(SourceLocation StartLoc, bool UseGlobal,
   if (D.getNumTypeObjects() > 0 &&
       D.getTypeObject(0).Kind == DeclaratorChunk::Array) {
     DeclaratorChunk &Chunk = D.getTypeObject(0);
-    if (D.getDeclSpec().containsPlaceholderType())
+    if (D.getDeclSpec().hasAutoTypeSpec())
       return ExprError(Diag(Chunk.Loc, diag::err_new_array_of_auto)
         << D.getSourceRange());
     if (Chunk.Arr.hasStatic)
@@ -1562,20 +1584,8 @@ Sema::ActOnCXXNew(SourceLocation StartLoc, bool UseGlobal,
     return ExprError();
 
   SourceRange DirectInitRange;
-  if (ParenListExpr *List = dyn_cast_or_null<ParenListExpr>(Initializer)) {
+  if (ParenListExpr *List = dyn_cast_or_null<ParenListExpr>(Initializer))
     DirectInitRange = List->getSourceRange();
-    // Handle errors like: new int a({0})
-    if (List->getNumExprs() == 1 &&
-        !canInitializeWithParenthesizedList(AllocType))
-      if (auto IList = dyn_cast<InitListExpr>(List->getExpr(0))) {
-        Diag(TInfo->getTypeLoc().getLocStart(), diag::err_list_init_in_parens)
-            << AllocType << List->getSourceRange()
-            << FixItHint::CreateRemoval(List->getLocStart())
-            << FixItHint::CreateRemoval(List->getLocEnd());
-        DirectInitRange = SourceRange();
-        Initializer = IList;
-      }
-  }
 
   return BuildCXXNew(SourceRange(StartLoc, D.getLocEnd()), UseGlobal,
                      PlacementLParen,
@@ -1643,8 +1653,38 @@ Sema::BuildCXXNew(SourceRange Range, bool UseGlobal,
     NumInits = List->getNumExprs();
   }
 
+  // C++11 [expr.new]p15:
+  //   A new-expression that creates an object of type T initializes that
+  //   object as follows:
+  InitializationKind Kind
+  //     - If the new-initializer is omitted, the object is default-
+  //       initialized (8.5); if no initialization is performed,
+  //       the object has indeterminate value
+    = initStyle == CXXNewExpr::NoInit
+        ? InitializationKind::CreateDefault(TypeRange.getBegin())
+  //     - Otherwise, the new-initializer is interpreted according to the
+  //       initialization rules of 8.5 for direct-initialization.
+        : initStyle == CXXNewExpr::ListInit
+            ? InitializationKind::CreateDirectList(TypeRange.getBegin())
+            : InitializationKind::CreateDirect(TypeRange.getBegin(),
+                                               DirectInitRange.getBegin(),
+                                               DirectInitRange.getEnd());
+
   // C++11 [dcl.spec.auto]p6. Deduce the type which 'auto' stands in for.
-  if (AllocType->isUndeducedType()) {
+  auto *Deduced = AllocType->getContainedDeducedType();
+  if (Deduced && isa<DeducedTemplateSpecializationType>(Deduced)) {
+    if (ArraySize)
+      return ExprError(Diag(ArraySize->getExprLoc(),
+                            diag::err_deduced_class_template_compound_type)
+                       << /*array*/ 2 << ArraySize->getSourceRange());
+
+    InitializedEntity Entity
+      = InitializedEntity::InitializeNew(StartLoc, AllocType);
+    AllocType = DeduceTemplateSpecializationFromInitializer(
+        AllocTypeInfo, Entity, Kind, MultiExprArg(Inits, NumInits));
+    if (AllocType.isNull())
+      return ExprError();
+  } else if (Deduced) {
     if (initStyle == CXXNewExpr::NoInit || NumInits == 0)
       return ExprError(Diag(StartLoc, diag::err_auto_new_requires_ctor_arg)
                        << AllocType << TypeRange);
@@ -1931,23 +1971,6 @@ Sema::BuildCXXNew(SourceRange Range, bool UseGlobal,
     else
       InitType = AllocType;
 
-    // C++11 [expr.new]p15:
-    //   A new-expression that creates an object of type T initializes that
-    //   object as follows:
-    InitializationKind Kind
-    //     - If the new-initializer is omitted, the object is default-
-    //       initialized (8.5); if no initialization is performed,
-    //       the object has indeterminate value
-      = initStyle == CXXNewExpr::NoInit
-          ? InitializationKind::CreateDefault(TypeRange.getBegin())
-    //     - Otherwise, the new-initializer is interpreted according to the
-    //       initialization rules of 8.5 for direct-initialization.
-          : initStyle == CXXNewExpr::ListInit
-              ? InitializationKind::CreateDirectList(TypeRange.getBegin())
-              : InitializationKind::CreateDirect(TypeRange.getBegin(),
-                                                 DirectInitRange.getBegin(),
-                                                 DirectInitRange.getEnd());
-
     InitializedEntity Entity
       = InitializedEntity::InitializeNew(StartLoc, InitType);
     InitializationSequence InitSeq(*this, Entity, Kind,
@@ -2025,9 +2048,10 @@ bool Sema::CheckAllocatedType(QualType AllocType, SourceLocation Loc,
   else if (AllocType->isVariablyModifiedType())
     return Diag(Loc, diag::err_variably_modified_new_type)
              << AllocType;
-  else if (unsigned AddressSpace = AllocType.getAddressSpace())
+  else if (AllocType.getAddressSpace())
     return Diag(Loc, diag::err_address_space_qualified_new)
-      << AllocType.getUnqualifiedType() << AddressSpace;
+      << AllocType.getUnqualifiedType()
+      << AllocType.getQualifiers().getAddressSpaceAttributePrintValue();
   else if (getLangOpts().ObjCAutoRefCount) {
     if (const ArrayType *AT = Context.getAsArrayType(AllocType)) {
       QualType BaseAllocType = Context.getBaseElementType(AT);
@@ -3094,10 +3118,11 @@ Sema::ActOnCXXDelete(SourceLocation StartLoc, bool UseGlobal,
     QualType Pointee = Type->getAs<PointerType>()->getPointeeType();
     QualType PointeeElem = Context.getBaseElementType(Pointee);
 
-    if (unsigned AddressSpace = Pointee.getAddressSpace())
+    if (Pointee.getAddressSpace())
       return Diag(Ex.get()->getLocStart(),
                   diag::err_address_space_qualified_delete)
-               << Pointee.getUnqualifiedType() << AddressSpace;
+               << Pointee.getUnqualifiedType()
+               << Pointee.getQualifiers().getAddressSpaceAttributePrintValue();
 
     CXXRecordDecl *PointeeRD = nullptr;
     if (Pointee->isVoidType() && !isSFINAEContext()) {
@@ -3703,10 +3728,9 @@ Sema::PerformImplicitConversion(Expr *From, QualType ToType,
       if (From->getType()->isObjCObjectPointerType() &&
           ToType->isObjCObjectPointerType())
         EmitRelatedResultTypeNote(From);
-    }
-    else if (getLangOpts().ObjCAutoRefCount &&
-             !CheckObjCARCUnavailableWeakConversion(ToType,
-                                                    From->getType())) {
+    } else if (getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() &&
+               !CheckObjCARCUnavailableWeakConversion(ToType,
+                                                      From->getType())) {
       if (Action == AA_Initializing)
         Diag(From->getLocStart(),
              diag::err_arc_weak_unavailable_assign);
@@ -3729,8 +3753,8 @@ Sema::PerformImplicitConversion(Expr *From, QualType ToType,
       (void) PrepareCastToObjCObjectPointer(E);
       From = E.get();
     }
-    if (getLangOpts().ObjCAutoRefCount)
-      CheckObjCARCConversion(SourceRange(), ToType, From, CCK);
+    if (getLangOpts().allowsNonTrivialObjCLifetimeQualifiers())
+      CheckObjCConversion(SourceRange(), ToType, From, CCK);
     From = ImpCastExprToType(From, ToType, Kind, VK_RValue, &BasePath, CCK)
              .get();
     break;
@@ -4033,6 +4057,7 @@ static bool CheckUnaryTypeTraitTypeCompleteness(Sema &S, TypeTrait UTT,
 
   // C++0x [meta.unary.prop] Table 49 requires the following traits to be
   // applied to a complete type.
+  case UTT_IsAggregate:
   case UTT_IsTrivial:
   case UTT_IsTriviallyCopyable:
   case UTT_IsStandardLayout:
@@ -4207,6 +4232,12 @@ static bool EvaluateUnaryTypeTrait(Sema &Self, TypeTrait UTT,
     if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
       return !RD->isUnion() && RD->isAbstract();
     return false;
+  case UTT_IsAggregate:
+    // Report vector extensions and complex types as aggregates because they
+    // support aggregate initialization. GCC mirrors this behavior for vectors
+    // but not _Complex.
+    return T->isAggregateType() || T->isVectorType() || T->isExtVectorType() ||
+           T->isAnyComplexType();
   // __is_interface_class only returns true when CL is invoked in /CLR mode and
   // even then only when it is used with the 'interface struct ...' syntax
   // Clang doesn't support /CLR which makes this type trait moot.
@@ -4495,25 +4526,6 @@ static bool EvaluateUnaryTypeTrait(Sema &Self, TypeTrait UTT,
   }
 }
 
-/// \brief Determine whether T has a non-trivial Objective-C lifetime in
-/// ARC mode.
-static bool hasNontrivialObjCLifetime(QualType T) {
-  switch (T.getObjCLifetime()) {
-  case Qualifiers::OCL_ExplicitNone:
-    return false;
-
-  case Qualifiers::OCL_Strong:
-  case Qualifiers::OCL_Weak:
-  case Qualifiers::OCL_Autoreleasing:
-    return true;
-
-  case Qualifiers::OCL_None:
-    return T->isObjCLifetimeType();
-  }
-
-  llvm_unreachable("Unknown ObjC lifetime qualifier");
-}
-
 static bool EvaluateBinaryTypeTrait(Sema &Self, TypeTrait BTT, QualType LhsT,
                                     QualType RhsT, SourceLocation KeyLoc);
 
@@ -4586,7 +4598,8 @@ static bool evaluateTypeTrait(Sema &S, TypeTrait Kind, SourceLocation KWLoc,
 
     // Perform the initialization in an unevaluated context within a SFINAE
     // trap at translation unit scope.
-    EnterExpressionEvaluationContext Unevaluated(S, Sema::Unevaluated);
+    EnterExpressionEvaluationContext Unevaluated(
+        S, Sema::ExpressionEvaluationContext::Unevaluated);
     Sema::SFINAETrap SFINAE(S, /*AccessCheckingSFINAE=*/true);
     Sema::ContextRAII TUContext(S, S.Context.getTranslationUnitDecl());
     InitializedEntity To(InitializedEntity::InitializeTemporary(Args[0]));
@@ -4607,10 +4620,9 @@ static bool evaluateTypeTrait(Sema &S, TypeTrait Kind, SourceLocation KWLoc,
       return S.canThrow(Result.get()) == CT_Cannot;
 
     if (Kind == clang::TT_IsTriviallyConstructible) {
-      // Under Objective-C ARC, if the destination has non-trivial Objective-C
-      // lifetime, this is a non-trivial construction.
-      if (S.getLangOpts().ObjCAutoRefCount &&
-          hasNontrivialObjCLifetime(T.getNonReferenceType()))
+      // Under Objective-C ARC and Weak, if the destination has non-trivial
+      // Objective-C lifetime, this is a non-trivial construction.
+      if (T.getNonReferenceType().hasNonTrivialObjCLifetime())
         return false;
 
       // The initialization succeeded; now make sure there are no non-trivial
@@ -4763,7 +4775,8 @@ static bool EvaluateBinaryTypeTrait(Sema &Self, TypeTrait BTT, QualType LhsT,
 
     // Perform the initialization in an unevaluated context within a SFINAE
     // trap at translation unit scope.
-    EnterExpressionEvaluationContext Unevaluated(Self, Sema::Unevaluated);
+    EnterExpressionEvaluationContext Unevaluated(
+        Self, Sema::ExpressionEvaluationContext::Unevaluated);
     Sema::SFINAETrap SFINAE(Self, /*AccessCheckingSFINAE=*/true);
     Sema::ContextRAII TUContext(Self, Self.Context.getTranslationUnitDecl());
     InitializationSequence Init(Self, To, Kind, FromPtr);
@@ -4814,7 +4827,8 @@ static bool EvaluateBinaryTypeTrait(Sema &Self, TypeTrait BTT, QualType LhsT,
 
     // Attempt the assignment in an unevaluated context within a SFINAE
     // trap at translation unit scope.
-    EnterExpressionEvaluationContext Unevaluated(Self, Sema::Unevaluated);
+    EnterExpressionEvaluationContext Unevaluated(
+        Self, Sema::ExpressionEvaluationContext::Unevaluated);
     Sema::SFINAETrap SFINAE(Self, /*AccessCheckingSFINAE=*/true);
     Sema::ContextRAII TUContext(Self, Self.Context.getTranslationUnitDecl());
     ExprResult Result = Self.BuildBinOp(/*S=*/nullptr, KeyLoc, BO_Assign, &Lhs,
@@ -4829,10 +4843,9 @@ static bool EvaluateBinaryTypeTrait(Sema &Self, TypeTrait BTT, QualType LhsT,
       return Self.canThrow(Result.get()) == CT_Cannot;
 
     if (BTT == BTT_IsTriviallyAssignable) {
-      // Under Objective-C ARC, if the destination has non-trivial Objective-C
-      // lifetime, this is a non-trivial assignment.
-      if (Self.getLangOpts().ObjCAutoRefCount &&
-          hasNontrivialObjCLifetime(LhsT.getNonReferenceType()))
+      // Under Objective-C ARC and Weak, if the destination has non-trivial
+      // Objective-C lifetime, this is a non-trivial assignment.
+      if (LhsT.getNonReferenceType().hasNonTrivialObjCLifetime())
         return false;
 
       return !Result.get()->hasNonTrivialCall(Self.Context);
@@ -5967,9 +5980,21 @@ ExprResult Sema::MaybeBindToTemporary(Expr *E) {
       } else if (ObjCBoxedExpr *BoxedExpr = dyn_cast<ObjCBoxedExpr>(E)) {
         D = BoxedExpr->getBoxingMethod();
       } else if (ObjCArrayLiteral *ArrayLit = dyn_cast<ObjCArrayLiteral>(E)) {
+        // Don't do reclaims if we're using the zero-element array
+        // constant.
+        if (ArrayLit->getNumElements() == 0 &&
+            Context.getLangOpts().ObjCRuntime.hasEmptyCollections())
+          return E;
+
         D = ArrayLit->getArrayWithObjectsMethod();
       } else if (ObjCDictionaryLiteral *DictLit
                                         = dyn_cast<ObjCDictionaryLiteral>(E)) {
+        // Don't do reclaims if we're using the zero-element dictionary
+        // constant.
+        if (DictLit->getNumElements() == 0 &&
+            Context.getLangOpts().ObjCRuntime.hasEmptyCollections())
+          return E;
+
         D = DictLit->getDictWithObjectsMethod();
       }
 
@@ -6136,7 +6161,7 @@ ExprResult Sema::ActOnDecltypeExpression(Expr *E) {
         return E;
       return new (Context) BinaryOperator(
           BO->getLHS(), RHS.get(), BO_Comma, BO->getType(), BO->getValueKind(),
-          BO->getObjectKind(), BO->getOperatorLoc(), BO->isFPContractable());
+          BO->getObjectKind(), BO->getOperatorLoc(), BO->getFPFeatures());
     }
   }
 
@@ -6402,6 +6427,23 @@ static bool CheckArrow(Sema& S, QualType& ObjectType, Expr *&Base,
   return false;
 }
 
+/// \brief Check if it's ok to try and recover dot pseudo destructor calls on
+/// pointer objects.
+static bool
+canRecoverDotPseudoDestructorCallsOnPointerObjects(Sema &SemaRef,
+                                                   QualType DestructedType) {
+  // If this is a record type, check if its destructor is callable.
+  if (auto *RD = DestructedType->getAsCXXRecordDecl()) {
+    if (CXXDestructorDecl *D = SemaRef.LookupDestructor(RD))
+      return SemaRef.CanUseDecl(D, /*TreatUnavailableAsInvalid=*/false);
+    return false;
+  }
+
+  // Otherwise, check if it's a type for which it's valid to use a pseudo-dtor.
+  return DestructedType->isDependentType() || DestructedType->isScalarType() ||
+         DestructedType->isVectorType();
+}
+
 ExprResult Sema::BuildPseudoDestructorExpr(Expr *Base,
                                            SourceLocation OpLoc,
                                            tok::TokenKind OpKind,
@@ -6436,15 +6478,36 @@ ExprResult Sema::BuildPseudoDestructorExpr(Expr *Base,
       = DestructedTypeInfo->getTypeLoc().getLocalSourceRange().getBegin();
     if (!DestructedType->isDependentType() && !ObjectType->isDependentType()) {
       if (!Context.hasSameUnqualifiedType(DestructedType, ObjectType)) {
-        Diag(DestructedTypeStart, diag::err_pseudo_dtor_type_mismatch)
-          << ObjectType << DestructedType << Base->getSourceRange()
-          << DestructedTypeInfo->getTypeLoc().getLocalSourceRange();
-
-        // Recover by setting the destructed type to the object type.
-        DestructedType = ObjectType;
-        DestructedTypeInfo = Context.getTrivialTypeSourceInfo(ObjectType,
-                                                           DestructedTypeStart);
-        Destructed = PseudoDestructorTypeStorage(DestructedTypeInfo);
+        // Detect dot pseudo destructor calls on pointer objects, e.g.:
+        //   Foo *foo;
+        //   foo.~Foo();
+        if (OpKind == tok::period && ObjectType->isPointerType() &&
+            Context.hasSameUnqualifiedType(DestructedType,
+                                           ObjectType->getPointeeType())) {
+          auto Diagnostic =
+              Diag(OpLoc, diag::err_typecheck_member_reference_suggestion)
+              << ObjectType << /*IsArrow=*/0 << Base->getSourceRange();
+
+          // Issue a fixit only when the destructor is valid.
+          if (canRecoverDotPseudoDestructorCallsOnPointerObjects(
+                  *this, DestructedType))
+            Diagnostic << FixItHint::CreateReplacement(OpLoc, "->");
+
+          // Recover by setting the object type to the destructed type and the
+          // operator to '->'.
+          ObjectType = DestructedType;
+          OpKind = tok::arrow;
+        } else {
+          Diag(DestructedTypeStart, diag::err_pseudo_dtor_type_mismatch)
+              << ObjectType << DestructedType << Base->getSourceRange()
+              << DestructedTypeInfo->getTypeLoc().getLocalSourceRange();
+
+          // Recover by setting the destructed type to the object type.
+          DestructedType = ObjectType;
+          DestructedTypeInfo =
+              Context.getTrivialTypeSourceInfo(ObjectType, DestructedTypeStart);
+          Destructed = PseudoDestructorTypeStorage(DestructedTypeInfo);
+        }
       } else if (DestructedType.getObjCLifetime() !=
                                                 ObjectType.getObjCLifetime()) {
 
@@ -6537,7 +6600,8 @@ ExprResult Sema::ActOnPseudoDestructorExpr(Scope *S, Expr *Base,
   if (SecondTypeName.getKind() == UnqualifiedId::IK_Identifier) {
     ParsedType T = getTypeName(*SecondTypeName.Identifier,
                                SecondTypeName.StartLocation,
-                               S, &SS, true, false, ObjectTypePtrForLookup);
+                               S, &SS, true, false, ObjectTypePtrForLookup,
+                               /*IsCtorOrDtorName*/true);
     if (!T &&
         ((SS.isSet() && !computeDeclContext(SS, false)) ||
          (!SS.isSet() && ObjectType->isDependentType()))) {
@@ -6566,10 +6630,12 @@ ExprResult Sema::ActOnPseudoDestructorExpr(Scope *S, Expr *Base,
     TypeResult T = ActOnTemplateIdType(TemplateId->SS,
                                        TemplateId->TemplateKWLoc,
                                        TemplateId->Template,
+                                       TemplateId->Name,
                                        TemplateId->TemplateNameLoc,
                                        TemplateId->LAngleLoc,
                                        TemplateArgsPtr,
-                                       TemplateId->RAngleLoc);
+                                       TemplateId->RAngleLoc,
+                                       /*IsCtorOrDtorName*/true);
     if (T.isInvalid() || !T.get()) {
       // Recover by assuming we had the right type all along.
       DestructedType = ObjectType;
@@ -6594,7 +6660,8 @@ ExprResult Sema::ActOnPseudoDestructorExpr(Scope *S, Expr *Base,
     if (FirstTypeName.getKind() == UnqualifiedId::IK_Identifier) {
       ParsedType T = getTypeName(*FirstTypeName.Identifier,
                                  FirstTypeName.StartLocation,
-                                 S, &SS, true, false, ObjectTypePtrForLookup);
+                                 S, &SS, true, false, ObjectTypePtrForLookup,
+                                 /*IsCtorOrDtorName*/true);
       if (!T) {
         Diag(FirstTypeName.StartLocation,
              diag::err_pseudo_dtor_destructor_non_type)
@@ -6615,10 +6682,12 @@ ExprResult Sema::ActOnPseudoDestructorExpr(Scope *S, Expr *Base,
       TypeResult T = ActOnTemplateIdType(TemplateId->SS,
                                          TemplateId->TemplateKWLoc,
                                          TemplateId->Template,
+                                         TemplateId->Name,
                                          TemplateId->TemplateNameLoc,
                                          TemplateId->LAngleLoc,
                                          TemplateArgsPtr,
-                                         TemplateId->RAngleLoc);
+                                         TemplateId->RAngleLoc,
+                                         /*IsCtorOrDtorName*/true);
       if (T.isInvalid() || !T.get()) {
         // Recover by dropping this type.
         ScopeType = QualType();
@@ -6681,7 +6750,8 @@ ExprResult Sema::BuildCXXMemberCallExpr(Expr *E, NamedDecl *FoundDecl,
       // follows the normal lifetime rules for block literals instead of being
       // autoreleased.
       DiagnosticErrorTrap Trap(Diags);
-      PushExpressionEvaluationContext(PotentiallyEvaluated);
+      PushExpressionEvaluationContext(
+          ExpressionEvaluationContext::PotentiallyEvaluated);
       ExprResult Exp = BuildBlockForLambdaConversion(E->getExprLoc(),
                                                      E->getExprLoc(),
                                                      Method, E);
@@ -6732,8 +6802,7 @@ ExprResult Sema::BuildCXXNoexceptExpr(SourceLocation KeyLoc, Expr *Operand,
   // The operand may have been modified when checking the placeholder type.
   Operand = R.get();
 
-  if (ActiveTemplateInstantiations.empty() &&
-      Operand->HasSideEffects(Context, false)) {
+  if (!inTemplateInstantiation() && Operand->HasSideEffects(Context, false)) {
     // The expression operand for noexcept is in an unevaluated expression
     // context, so side effects could result in unintended consequences.
     Diag(Operand->getExprLoc(), diag::warn_side_effects_unevaluated_context);
diff --git a/lib/Sema/SemaExprMember.cpp b/lib/Sema/SemaExprMember.cpp
index c9aa99ee383c..b18de7e94686 100644
--- a/lib/Sema/SemaExprMember.cpp
+++ b/lib/Sema/SemaExprMember.cpp
@@ -133,20 +133,20 @@ static IMAKind ClassifyImplicitMemberAccess(Sema &SemaRef,
   IMAKind AbstractInstanceResult = IMA_Static; // happens to be 'false'
   assert(!AbstractInstanceResult);
   switch (SemaRef.ExprEvalContexts.back().Context) {
-  case Sema::Unevaluated:
-  case Sema::UnevaluatedList:
+  case Sema::ExpressionEvaluationContext::Unevaluated:
+  case Sema::ExpressionEvaluationContext::UnevaluatedList:
     if (isField && SemaRef.getLangOpts().CPlusPlus11)
       AbstractInstanceResult = IMA_Field_Uneval_Context;
     break;
 
-  case Sema::UnevaluatedAbstract:
+  case Sema::ExpressionEvaluationContext::UnevaluatedAbstract:
     AbstractInstanceResult = IMA_Abstract;
     break;
 
-  case Sema::DiscardedStatement:
-  case Sema::ConstantEvaluated:
-  case Sema::PotentiallyEvaluated:
-  case Sema::PotentiallyEvaluatedIfUsed:
+  case Sema::ExpressionEvaluationContext::DiscardedStatement:
+  case Sema::ExpressionEvaluationContext::ConstantEvaluated:
+  case Sema::ExpressionEvaluationContext::PotentiallyEvaluated:
+  case Sema::ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
     break;
   }
 
@@ -284,6 +284,14 @@ IsRGBA(char c) {
   }
 }
 
+// OpenCL v1.1, s6.1.7
+// The component swizzle length must be in accordance with the acceptable
+// vector sizes.
+static bool IsValidOpenCLComponentSwizzleLength(unsigned len)
+{
+  return (len >= 1 && len <= 4) || len == 8 || len == 16;
+}
+
 /// Check an ext-vector component access expression.
 ///
 /// VK should be set in advance to the value kind of the base
@@ -376,6 +384,19 @@ CheckExtVectorComponent(Sema &S, QualType baseType, ExprValueKind &VK,
     }
   }
 
+  if (!HalvingSwizzle) {
+    unsigned SwizzleLength = CompName->getLength();
+
+    if (HexSwizzle)
+      SwizzleLength--;
+
+    if (IsValidOpenCLComponentSwizzleLength(SwizzleLength) == false) {
+      S.Diag(OpLoc, diag::err_opencl_ext_vector_component_invalid_length)
+        << SwizzleLength << SourceRange(CompLoc);
+      return QualType();
+    }
+  }
+
   // The component accessor looks fine - now we need to compute the actual type.
   // The vector type is implied by the component accessor. For example,
   // vec4.b is a float, vec4.xy is a vec2, vec4.rgb is a vec3, etc.
@@ -973,7 +994,7 @@ Sema::BuildMemberReferenceExpr(Expr *BaseExpr, QualType BaseExprType,
 
   // C++1z [expr.ref]p2:
   //   For the first option (dot) the first expression shall be a glvalue [...]
-  if (!IsArrow && BaseExpr->isRValue()) {
+  if (!IsArrow && BaseExpr && BaseExpr->isRValue()) {
     ExprResult Converted = TemporaryMaterializationConversion(BaseExpr);
     if (Converted.isInvalid())
       return ExprError();
@@ -1475,7 +1496,7 @@ static ExprResult LookupMemberExpr(Sema &S, LookupResult &R,
       }
     }
     bool warn = true;
-    if (S.getLangOpts().ObjCAutoRefCount) {
+    if (S.getLangOpts().ObjCWeak) {
       Expr *BaseExp = BaseExpr.get()->IgnoreParenImpCasts();
       if (UnaryOperator *UO = dyn_cast<UnaryOperator>(BaseExp))
         if (UO->getOpcode() == UO_Deref)
@@ -1502,11 +1523,9 @@ static ExprResult LookupMemberExpr(Sema &S, LookupResult &R,
         IV, IV->getUsageType(BaseType), MemberLoc, OpLoc, BaseExpr.get(),
         IsArrow);
 
-    if (S.getLangOpts().ObjCAutoRefCount) {
-      if (IV->getType().getObjCLifetime() == Qualifiers::OCL_Weak) {
-        if (!S.Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, MemberLoc))
-          S.recordUseOfEvaluatedWeak(Result);
-      }
+    if (IV->getType().getObjCLifetime() == Qualifiers::OCL_Weak) {
+      if (!S.Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, MemberLoc))
+        S.recordUseOfEvaluatedWeak(Result);
     }
 
     return Result;
diff --git a/lib/Sema/SemaExprObjC.cpp b/lib/Sema/SemaExprObjC.cpp
index 7dbd660f53ec..9cc443ed4fd9 100644
--- a/lib/Sema/SemaExprObjC.cpp
+++ b/lib/Sema/SemaExprObjC.cpp
@@ -1984,13 +1984,24 @@ ActOnClassPropertyRefExpr(IdentifierInfo &receiverName,
     }
   }
 
+  Selector GetterSel;
+  Selector SetterSel;
+  if (auto PD = IFace->FindPropertyDeclaration(
+          &propertyName, ObjCPropertyQueryKind::OBJC_PR_query_class)) {
+    GetterSel = PD->getGetterName();
+    SetterSel = PD->getSetterName();
+  } else {
+    GetterSel = PP.getSelectorTable().getNullarySelector(&propertyName);
+    SetterSel = SelectorTable::constructSetterSelector(
+        PP.getIdentifierTable(), PP.getSelectorTable(), &propertyName);
+  }
+
   // Search for a declared property first.
-  Selector Sel = PP.getSelectorTable().getNullarySelector(&propertyName);
-  ObjCMethodDecl *Getter = IFace->lookupClassMethod(Sel);
+  ObjCMethodDecl *Getter = IFace->lookupClassMethod(GetterSel);
 
   // If this reference is in an @implementation, check for 'private' methods.
   if (!Getter)
-    Getter = IFace->lookupPrivateClassMethod(Sel);
+    Getter = IFace->lookupPrivateClassMethod(GetterSel);
 
   if (Getter) {
     // FIXME: refactor/share with ActOnMemberReference().
@@ -2000,11 +2011,6 @@ ActOnClassPropertyRefExpr(IdentifierInfo &receiverName,
   }
 
   // Look for the matching setter, in case it is needed.
-  Selector SetterSel =
-    SelectorTable::constructSetterSelector(PP.getIdentifierTable(),
-                                            PP.getSelectorTable(),
-                                           &propertyName);
-
   ObjCMethodDecl *Setter = IFace->lookupClassMethod(SetterSel);
   if (!Setter) {
     // If this reference is in an @implementation, also check for 'private'
@@ -2260,6 +2266,53 @@ static void checkCocoaAPI(Sema &S, const ObjCMessageExpr *Msg) {
                      edit::rewriteObjCRedundantCallWithLiteral);
 }
 
+static void checkFoundationAPI(Sema &S, SourceLocation Loc,
+                               const ObjCMethodDecl *Method,
+                               ArrayRef<Expr *> Args, QualType ReceiverType,
+                               bool IsClassObjectCall) {
+  // Check if this is a performSelector method that uses a selector that returns
+  // a record or a vector type.
+  if (Method->getSelector().getMethodFamily() != OMF_performSelector ||
+      Args.empty())
+    return;
+  const auto *SE = dyn_cast<ObjCSelectorExpr>(Args[0]->IgnoreParens());
+  if (!SE)
+    return;
+  ObjCMethodDecl *ImpliedMethod;
+  if (!IsClassObjectCall) {
+    const auto *OPT = ReceiverType->getAs<ObjCObjectPointerType>();
+    if (!OPT || !OPT->getInterfaceDecl())
+      return;
+    ImpliedMethod =
+        OPT->getInterfaceDecl()->lookupInstanceMethod(SE->getSelector());
+    if (!ImpliedMethod)
+      ImpliedMethod =
+          OPT->getInterfaceDecl()->lookupPrivateMethod(SE->getSelector());
+  } else {
+    const auto *IT = ReceiverType->getAs<ObjCInterfaceType>();
+    if (!IT)
+      return;
+    ImpliedMethod = IT->getDecl()->lookupClassMethod(SE->getSelector());
+    if (!ImpliedMethod)
+      ImpliedMethod =
+          IT->getDecl()->lookupPrivateClassMethod(SE->getSelector());
+  }
+  if (!ImpliedMethod)
+    return;
+  QualType Ret = ImpliedMethod->getReturnType();
+  if (Ret->isRecordType() || Ret->isVectorType() || Ret->isExtVectorType()) {
+    QualType Ret = ImpliedMethod->getReturnType();
+    S.Diag(Loc, diag::warn_objc_unsafe_perform_selector)
+        << Method->getSelector()
+        << (!Ret->isRecordType()
+                ? /*Vector*/ 2
+                : Ret->isUnionType() ? /*Union*/ 1 : /*Struct*/ 0);
+    S.Diag(ImpliedMethod->getLocStart(),
+           diag::note_objc_unsafe_perform_selector_method_declared_here)
+        << ImpliedMethod->getSelector() << Ret;
+  }
+}
+
 /// \brief Diagnose use of %s directive in an NSString which is being passed
 /// as formatting string to formatting method.
 static void
@@ -2462,6 +2515,9 @@ ExprResult Sema::BuildClassMessage(TypeSourceInfo *ReceiverTypeInfo,
     if (!isImplicit)
       checkCocoaAPI(*this, Result);
   }
+  if (Method)
+    checkFoundationAPI(*this, SelLoc, Method, makeArrayRef(Args, NumArgs),
+                       ReceiverType, /*IsClassObjectCall=*/true);
   return MaybeBindToTemporary(Result);
 }
 
@@ -2501,6 +2557,24 @@ ExprResult Sema::BuildInstanceMessageImplicit(Expr *Receiver,
                               /*isImplicit=*/true);
 }
 
+static bool isMethodDeclaredInRootProtocol(Sema &S, const ObjCMethodDecl *M) {
+  if (!S.NSAPIObj)
+    return false;
+  const auto *Protocol = dyn_cast<ObjCProtocolDecl>(M->getDeclContext());
+  if (!Protocol)
+    return false;
+  const IdentifierInfo *II = S.NSAPIObj->getNSClassId(NSAPI::ClassId_NSObject);
+  if (const auto *RootClass = dyn_cast_or_null<ObjCInterfaceDecl>(
+          S.LookupSingleName(S.TUScope, II, Protocol->getLocStart(),
+                             Sema::LookupOrdinaryName))) {
+    for (const ObjCProtocolDecl *P : RootClass->all_referenced_protocols()) {
+      if (P->getCanonicalDecl() == Protocol->getCanonicalDecl())
+        return true;
+    }
+  }
+  return false;
+}
+
 /// \brief Build an Objective-C instance message expression.
 ///
 /// This routine takes care of both normal instance messages and
@@ -2676,7 +2750,7 @@ ExprResult Sema::BuildInstanceMessage(Expr *Receiver,
         if (!Method) {
           Method = LookupMethodInQualifiedType(Sel, QClassTy, true);
           // warn if instance method found for a Class message.
-          if (Method) {
+          if (Method && !isMethodDeclaredInRootProtocol(*this, Method)) {
             Diag(SelLoc, diag::warn_instance_method_on_class_found)
               << Method->getSelector() << Sel;
             Diag(Method->getLocation(), diag::note_method_declared_at)
@@ -2920,7 +2994,8 @@ ExprResult Sema::BuildInstanceMessage(Expr *Receiver,
     
     case OMF_performSelector:
       if (Method && NumArgs >= 1) {
-        if (ObjCSelectorExpr *SelExp = dyn_cast<ObjCSelectorExpr>(Args[0])) {
+        if (const auto *SelExp =
+                dyn_cast<ObjCSelectorExpr>(Args[0]->IgnoreParens())) {
           Selector ArgSel = SelExp->getSelector();
           ObjCMethodDecl *SelMethod = 
             LookupInstanceMethodInGlobalPool(ArgSel,
@@ -2936,7 +3011,6 @@ ExprResult Sema::BuildInstanceMessage(Expr *Receiver,
               case OMF_copy:
               case OMF_mutableCopy:
               case OMF_new:
-              case OMF_self:
               case OMF_init:
                 // Issue error, unless ns_returns_not_retained.
                 if (!SelMethod->hasAttr<NSReturnsNotRetainedAttr>()) {
@@ -2987,6 +3061,26 @@ ExprResult Sema::BuildInstanceMessage(Expr *Receiver,
     if (!isImplicit)
       checkCocoaAPI(*this, Result);
   }
+  if (Method) {
+    bool IsClassObjectCall = ClassMessage;
+    // 'self' message receivers in class methods should be treated as message
+    // sends to the class object in order for the semantic checks to be
+    // performed correctly. Messages to 'super' already count as class messages,
+    // so they don't need to be handled here.
+    if (Receiver && isSelfExpr(Receiver)) {
+      if (const auto *OPT = ReceiverType->getAs<ObjCObjectPointerType>()) {
+        if (OPT->getObjectType()->isObjCClass()) {
+          if (const auto *CurMeth = getCurMethodDecl()) {
+            IsClassObjectCall = true;
+            ReceiverType =
+                Context.getObjCInterfaceType(CurMeth->getClassInterface());
+          }
+        }
+      }
+    }
+    checkFoundationAPI(*this, SelLoc, Method, makeArrayRef(Args, NumArgs),
+                       ReceiverType, IsClassObjectCall);
+  }
 
   if (getLangOpts().ObjCAutoRefCount) {
     // In ARC, annotate delegate init calls.
@@ -3006,7 +3100,9 @@ ExprResult Sema::BuildInstanceMessage(Expr *Receiver,
     // In ARC, check for message sends which are likely to introduce
     // retain cycles.
     checkRetainCycles(Result);
+  }
 
+  if (getLangOpts().ObjCWeak) {
     if (!isImplicit && Method) {
       if (const ObjCPropertyDecl *Prop = Method->findPropertyDecl()) {
         bool IsWeak =
@@ -3259,7 +3355,7 @@ namespace {
       if (isAnyRetainable(TargetClass) &&
           isAnyRetainable(SourceClass) &&
           var &&
-          var->getStorageClass() == SC_Extern &&
+          !var->hasDefinition(Context) &&
           var->getType().isConstQualified()) {
 
         // In system headers, they can also be assumed to be immune to retains.
@@ -4012,11 +4108,10 @@ Sema::CheckObjCBridgeRelatedConversions(SourceLocation Loc,
 }
 
 Sema::ARCConversionResult
-Sema::CheckObjCARCConversion(SourceRange castRange, QualType castType,
-                             Expr *&castExpr, CheckedConversionKind CCK,
-                             bool Diagnose,
-                             bool DiagnoseCFAudited,
-                             BinaryOperatorKind Opc) {
+Sema::CheckObjCConversion(SourceRange castRange, QualType castType,
+                          Expr *&castExpr, CheckedConversionKind CCK,
+                          bool Diagnose, bool DiagnoseCFAudited,
+                          BinaryOperatorKind Opc) {
   QualType castExprType = castExpr->getType();
 
   // For the purposes of the classification, we assume reference types
@@ -4056,7 +4151,12 @@ Sema::CheckObjCARCConversion(SourceRange castRange, QualType castType,
     }
     return ACR_okay;
   }
-  
+
+  // The life-time qualifier cast check above is all we need for ObjCWeak.
+  // ObjCAutoRefCount has more restrictions on what is legal.
+  if (!getLangOpts().ObjCAutoRefCount)
+    return ACR_okay;
+
   if (isAnyCLike(exprACTC) && isAnyCLike(castACTC)) return ACR_okay;
 
   // Allow all of these types to be cast to integer types (but not
diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index b053c83c3f69..d0f530010a0d 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -623,6 +623,11 @@ InitListChecker::FillInEmptyInitializations(const InitializedEntity &Entity,
   assert((ILE->getType() != SemaRef.Context.VoidTy) &&
          "Should not have void type");
 
+  // A transparent ILE is not performing aggregate initialization and should
+  // not be filled in.
+  if (ILE->isTransparent())
+    return;
+
   if (const RecordType *RType = ILE->getType()->getAs<RecordType>()) {
     const RecordDecl *RDecl = RType->getDecl();
     if (RDecl->isUnion() && ILE->getInitializedFieldInUnion())
@@ -902,7 +907,7 @@ static void warnBracedScalarInit(Sema &S, const InitializedEntity &Entity,
   // Don't warn during template instantiation. If the initialization was
   // non-dependent, we warned during the initial parse; otherwise, the
   // type might not be scalar in some uses of the template.
-  if (!S.ActiveTemplateInstantiations.empty())
+  if (S.inTemplateInstantiation())
     return;
 
   unsigned DiagID = 0;
@@ -945,6 +950,7 @@ static void warnBracedScalarInit(Sema &S, const InitializedEntity &Entity,
   case InitializedEntity::EK_Base:
   case InitializedEntity::EK_Delegating:
   case InitializedEntity::EK_BlockElement:
+  case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
   case InitializedEntity::EK_Binding:
     llvm_unreachable("unexpected braced scalar init");
   }
@@ -2237,6 +2243,10 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
     }
 
     unsigned FieldIndex = 0;
+
+    if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RT->getDecl()))
+      FieldIndex = CXXRD->getNumBases();
+
     for (auto *FI : RT->getDecl()->fields()) {
       if (FI->isUnnamedBitfield())
         continue;
@@ -2260,15 +2270,17 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
           assert(StructuredList->getNumInits() == 1
                  && "A union should never have more than one initializer!");
 
-          // We're about to throw away an initializer, emit warning.
-          SemaRef.Diag(D->getFieldLoc(),
-                       diag::warn_initializer_overrides)
-            << D->getSourceRange();
           Expr *ExistingInit = StructuredList->getInit(0);
-          SemaRef.Diag(ExistingInit->getLocStart(),
-                       diag::note_previous_initializer)
-            << /*FIXME:has side effects=*/0
-            << ExistingInit->getSourceRange();
+          if (ExistingInit) {
+            // We're about to throw away an initializer, emit warning.
+            SemaRef.Diag(D->getFieldLoc(),
+                         diag::warn_initializer_overrides)
+              << D->getSourceRange();
+            SemaRef.Diag(ExistingInit->getLocStart(),
+                         diag::note_previous_initializer)
+              << /*FIXME:has side effects=*/0
+              << ExistingInit->getSourceRange();
+          }
 
           // remove existing initializer
           StructuredList->resizeInits(SemaRef.Context, 0);
@@ -2925,6 +2937,7 @@ DeclarationName InitializedEntity::getName() const {
   case EK_VectorElement:
   case EK_ComplexElement:
   case EK_BlockElement:
+  case EK_LambdaToBlockConversionBlockElement:
   case EK_CompoundLiteralInit:
   case EK_RelatedResult:
     return DeclarationName();
@@ -2954,6 +2967,7 @@ ValueDecl *InitializedEntity::getDecl() const {
   case EK_VectorElement:
   case EK_ComplexElement:
   case EK_BlockElement:
+  case EK_LambdaToBlockConversionBlockElement:
   case EK_LambdaCapture:
   case EK_CompoundLiteralInit:
   case EK_RelatedResult:
@@ -2983,6 +2997,7 @@ bool InitializedEntity::allowsNRVO() const {
   case EK_VectorElement:
   case EK_ComplexElement:
   case EK_BlockElement:
+  case EK_LambdaToBlockConversionBlockElement:
   case EK_LambdaCapture:
   case EK_RelatedResult:
     break;
@@ -3016,6 +3031,9 @@ unsigned InitializedEntity::dumpImpl(raw_ostream &OS) const {
   case EK_VectorElement: OS << "VectorElement " << Index; break;
   case EK_ComplexElement: OS << "ComplexElement " << Index; break;
   case EK_BlockElement: OS << "Block"; break;
+  case EK_LambdaToBlockConversionBlockElement:
+    OS << "Block (lambda)";
+    break;
   case EK_LambdaCapture:
     OS << "LambdaCapture ";
     OS << DeclarationName(Capture.VarID);
@@ -3103,6 +3121,7 @@ bool InitializationSequence::isAmbiguous() const {
 
   switch (getFailureKind()) {
   case FK_TooManyInitsForReference:
+  case FK_ParenthesizedListInitForReference:
   case FK_ArrayNeedsInitList:
   case FK_ArrayNeedsInitListOrStringLiteral:
   case FK_ArrayNeedsInitListOrWideStringLiteral:
@@ -3120,6 +3139,7 @@ bool InitializationSequence::isAmbiguous() const {
   case FK_ConversionFailed:
   case FK_ConversionFromPropertyFailed:
   case FK_TooManyInitsForScalar:
+  case FK_ParenthesizedListInitForScalar:
   case FK_ReferenceBindingToInitList:
   case FK_InitListBadDestinationType:
   case FK_DefaultInitOfConst:
@@ -3611,9 +3631,13 @@ static void TryConstructorInitialization(Sema &S,
   //       destination object.
   // Per DR (no number yet), this does not apply when initializing a base
   // class or delegating to another constructor from a mem-initializer.
+  // ObjC++: Lambda captured by the block in the lambda to block conversion
+  // should avoid copy elision.
   if (S.getLangOpts().CPlusPlus1z &&
       Entity.getKind() != InitializedEntity::EK_Base &&
       Entity.getKind() != InitializedEntity::EK_Delegating &&
+      Entity.getKind() !=
+          InitializedEntity::EK_LambdaToBlockConversionBlockElement &&
       UnwrappedArgs.size() == 1 && UnwrappedArgs[0]->isRValue() &&
       S.Context.hasSameUnqualifiedType(UnwrappedArgs[0]->getType(), DestType)) {
     // Convert qualifications if necessary.
@@ -3977,6 +4001,8 @@ static void TryListInitialization(Sema &S,
       ImplicitConversionSequence ICS;
       ICS.setStandard();
       ICS.Standard.setAsIdentityConversion();
+      if (!E->isRValue())
+        ICS.Standard.First = ICK_Lvalue_To_Rvalue;
       // If E is of a floating-point type, then the conversion is ill-formed
       // due to narrowing, but go through the motions in order to produce the
       // right diagnostic.
@@ -4675,15 +4701,7 @@ static void TryUserDefinedConversion(Sema &S,
 
     // Try to complete the type we're converting to.
     if (S.isCompleteType(Kind.getLocation(), DestType)) {
-      DeclContext::lookup_result R = S.LookupConstructors(DestRecordDecl);
-      // The container holding the constructors can under certain conditions
-      // be changed while iterating. To be safe we copy the lookup results
-      // to a new container.
-      SmallVector<NamedDecl*, 8> CopyOfCon(R.begin(), R.end());
-      for (SmallVectorImpl<NamedDecl *>::iterator
-             Con = CopyOfCon.begin(), ConEnd = CopyOfCon.end();
-           Con != ConEnd; ++Con) {
-        NamedDecl *D = *Con;
+      for (NamedDecl *D : S.LookupConstructors(DestRecordDecl)) {
         auto Info = getConstructorInfo(D);
         if (!Info.Constructor)
           continue;
@@ -5176,6 +5194,12 @@ void InitializationSequence::InitializeFrom(Sema &S,
     // (Therefore, multiple arguments are not permitted.)
     if (Args.size() != 1)
       SetFailed(FK_TooManyInitsForReference);
+    // C++17 [dcl.init.ref]p5:
+    //   A reference [...] is initialized by an expression [...] as follows:
+    // If the initializer is not an expression, presumably we should reject,
+    // but the standard fails to actually say so.
+    else if (isa<InitListExpr>(Args[0]))
+      SetFailed(FK_ParenthesizedListInitForReference);
     else
       TryReferenceInitialization(S, Entity, Kind, Args[0], *this);
     return;
@@ -5341,11 +5365,16 @@ void InitializationSequence::InitializeFrom(Sema &S,
     return;
   }
 
+  assert(Args.size() >= 1 && "Zero-argument case handled above");
+
+  // The remaining cases all need a source type.
   if (Args.size() > 1) {
     SetFailed(FK_TooManyInitsForScalar);
     return;
+  } else if (isa<InitListExpr>(Args[0])) {
+    SetFailed(FK_ParenthesizedListInitForScalar);
+    return;
   }
-  assert(Args.size() == 1 && "Zero-argument case handled above");
 
   //    - Otherwise, if the source type is a (possibly cv-qualified) class
   //      type, conversion functions are considered.
@@ -5472,6 +5501,7 @@ getAssignmentAction(const InitializedEntity &Entity, bool Diagnose = false) {
   case InitializedEntity::EK_VectorElement:
   case InitializedEntity::EK_ComplexElement:
   case InitializedEntity::EK_BlockElement:
+  case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
   case InitializedEntity::EK_LambdaCapture:
   case InitializedEntity::EK_CompoundLiteralInit:
     return Sema::AA_Initializing;
@@ -5495,6 +5525,7 @@ static bool shouldBindAsTemporary(const InitializedEntity &Entity) {
   case InitializedEntity::EK_ComplexElement:
   case InitializedEntity::EK_Exception:
   case InitializedEntity::EK_BlockElement:
+  case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
   case InitializedEntity::EK_LambdaCapture:
   case InitializedEntity::EK_CompoundLiteralInit:
     return false;
@@ -5521,6 +5552,7 @@ static bool shouldDestroyEntity(const InitializedEntity &Entity) {
     case InitializedEntity::EK_VectorElement:
     case InitializedEntity::EK_ComplexElement:
     case InitializedEntity::EK_BlockElement:
+    case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
     case InitializedEntity::EK_LambdaCapture:
       return false;
 
@@ -5568,6 +5600,7 @@ static SourceLocation getInitializationLoc(const InitializedEntity &Entity,
   case InitializedEntity::EK_VectorElement:
   case InitializedEntity::EK_ComplexElement:
   case InitializedEntity::EK_BlockElement:
+  case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
   case InitializedEntity::EK_CompoundLiteralInit:
   case InitializedEntity::EK_RelatedResult:
     return Initializer->getLocStart();
@@ -5918,7 +5951,8 @@ PerformConstructorInitialization(Sema &S,
     S.MarkFunctionReferenced(Loc, Constructor);
 
     CurInit = new (S.Context) CXXTemporaryObjectExpr(
-        S.Context, Constructor, TSInfo,
+        S.Context, Constructor,
+        Entity.getType().getNonLValueExprType(S.Context), TSInfo,
         ConstructorArgs, ParenOrBraceRange, HadMultipleCandidates,
         IsListInitialization, IsStdInitListInitialization,
         ConstructorInitRequiresZeroInit);
@@ -6004,6 +6038,7 @@ InitializedEntityOutlivesFullExpression(const InitializedEntity &Entity) {
   case InitializedEntity::EK_ArrayElement:
   case InitializedEntity::EK_VectorElement:
   case InitializedEntity::EK_BlockElement:
+  case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
   case InitializedEntity::EK_ComplexElement:
     // Could not determine what the full initialization is. Assume it might not
     // outlive the full-expression.
@@ -6092,6 +6127,7 @@ static const InitializedEntity *getEntityForTemporaryLifetimeExtension(
     return FallbackDecl;
 
   case InitializedEntity::EK_BlockElement:
+  case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
   case InitializedEntity::EK_LambdaCapture:
   case InitializedEntity::EK_Exception:
   case InitializedEntity::EK_VectorElement:
@@ -6250,7 +6286,7 @@ static void CheckMoveOnConstruction(Sema &S, const Expr *InitExpr,
   if (!InitExpr)
     return;
 
-  if (!S.ActiveTemplateInstantiations.empty())
+  if (S.inTemplateInstantiation())
     return;
 
   QualType DestType = InitExpr->getType();
@@ -6485,6 +6521,20 @@ InitializationSequence::Perform(Sema &S,
       << Init->getSourceRange();
   }
 
+  // OpenCL v2.0 s6.13.11.1. atomic variables can be initialized in global scope
+  QualType ETy = Entity.getType();
+  Qualifiers TyQualifiers = ETy.getQualifiers();
+  bool HasGlobalAS = TyQualifiers.hasAddressSpace() &&
+                     TyQualifiers.getAddressSpace() == LangAS::opencl_global;
+
+  if (S.getLangOpts().OpenCLVersion >= 200 &&
+      ETy->isAtomicType() && !HasGlobalAS &&
+      Entity.getKind() == InitializedEntity::EK_Variable && Args.size() > 0) {
+    S.Diag(Args[0]->getLocStart(), diag::err_opencl_atomic_init) << 1 <<
+    SourceRange(Entity.getDecl()->getLocStart(), Args[0]->getLocEnd());
+    return ExprError();
+  }
+
   // Diagnose cases where we initialize a pointer to an array temporary, and the
   // pointer obviously outlives the temporary.
   if (Args.size() == 1 && Args[0]->getType()->isArrayType() &&
@@ -6636,6 +6686,19 @@ InitializationSequence::Perform(Sema &S,
       if (S.CheckExceptionSpecCompatibility(CurInit.get(), DestType))
         return ExprError();
 
+      // We don't check for e.g. function pointers here, since address
+      // availability checks should only occur when the function first decays
+      // into a pointer or reference.
+      if (CurInit.get()->getType()->isFunctionProtoType()) {
+        if (auto *DRE = dyn_cast<DeclRefExpr>(CurInit.get()->IgnoreParens())) {
+          if (auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) {
+            if (!S.checkAddressOfFunctionIsAvailable(FD, /*Complain=*/true,
+                                                     DRE->getLocStart()))
+              return ExprError();
+          }
+        }
+      }
+
       // Even though we didn't materialize a temporary, the binding may still
       // extend the lifetime of a temporary. This happens if we bind a reference
       // to the result of a cast to reference type.
@@ -6670,14 +6733,10 @@ InitializationSequence::Perform(Sema &S,
                                   /*IsInitializerList=*/false,
                                   ExtendingEntity->getDecl());
 
-      // If we're binding to an Objective-C object that has lifetime, we
-      // need cleanups. Likewise if we're extending this temporary to automatic
-      // storage duration -- we need to register its cleanup during the
-      // full-expression's cleanups.
-      if ((S.getLangOpts().ObjCAutoRefCount &&
-           MTE->getType()->isObjCLifetimeType()) ||
-          (MTE->getStorageDuration() == SD_Automatic &&
-           MTE->getType().isDestructedType()))
+      // If we're extending this temporary to automatic storage duration -- we
+      // need to register its cleanup during the full-expression's cleanups.
+      if (MTE->getStorageDuration() == SD_Automatic &&
+          MTE->getType().isDestructedType())
         S.Cleanup.setExprNeedsCleanups(true);
 
       CurInit = MTE;
@@ -6986,7 +7045,7 @@ InitializationSequence::Perform(Sema &S,
                                                     Kind.getRange().getBegin());
 
         CurInit = new (S.Context) CXXScalarValueInitExpr(
-            TSInfo->getType().getNonLValueExprType(S.Context), TSInfo,
+            Entity.getType().getNonLValueExprType(S.Context), TSInfo,
             Kind.getRange().getEnd());
       } else {
         CurInit = new (S.Context) ImplicitValueInitExpr(Step->Type);
@@ -7161,7 +7220,7 @@ InitializationSequence::Perform(Sema &S,
       QualType SourceType = Init->getType();
       // Case 1
       if (Entity.isParameterKind()) {
-        if (!SourceType->isSamplerT()) {
+        if (!SourceType->isSamplerT() && !SourceType->isIntegerType()) {
           S.Diag(Kind.getLocation(), diag::err_sampler_argument_required)
             << SourceType;
           break;
@@ -7385,6 +7444,10 @@ bool InitializationSequence::Diagnose(Sema &S,
       S.Diag(Kind.getLocation(), diag::err_reference_has_multiple_inits)
         << SourceRange(Args.front()->getLocStart(), Args.back()->getLocEnd());
     break;
+  case FK_ParenthesizedListInitForReference:
+    S.Diag(Kind.getLocation(), diag::err_list_init_in_parens)
+      << 1 << Entity.getType() << Args[0]->getSourceRange();
+    break;
 
   case FK_ArrayNeedsInitList:
     S.Diag(Kind.getLocation(), diag::err_array_init_not_init_list) << 0;
@@ -7596,6 +7659,11 @@ bool InitializationSequence::Diagnose(Sema &S,
     break;
   }
 
+  case FK_ParenthesizedListInitForScalar:
+    S.Diag(Kind.getLocation(), diag::err_list_init_in_parens)
+      << 0 << Entity.getType() << Args[0]->getSourceRange();
+    break;
+
   case FK_ReferenceBindingToInitList:
     S.Diag(Kind.getLocation(), diag::err_reference_bind_init_list)
       << DestType.getNonReferenceType() << Args[0]->getSourceRange();
@@ -7759,7 +7827,8 @@ bool InitializationSequence::Diagnose(Sema &S,
     (void)Ovl;
     assert(Ovl == OR_Success && "Inconsistent overload resolution");
     CXXConstructorDecl *CtorDecl = cast<CXXConstructorDecl>(Best->Function);
-    S.Diag(CtorDecl->getLocation(), diag::note_constructor_declared_here);
+    S.Diag(CtorDecl->getLocation(),
+           diag::note_explicit_ctor_deduction_guide_here) << false;
     break;
   }
   }
@@ -7777,6 +7846,10 @@ void InitializationSequence::dump(raw_ostream &OS) const {
       OS << "too many initializers for reference";
       break;
 
+    case FK_ParenthesizedListInitForReference:
+      OS << "parenthesized list init for reference";
+      break;
+
     case FK_ArrayNeedsInitList:
       OS << "array requires initializer list";
       break;
@@ -7861,6 +7934,10 @@ void InitializationSequence::dump(raw_ostream &OS) const {
       OS << "too many initializers for scalar";
       break;
 
+    case FK_ParenthesizedListInitForScalar:
+      OS << "parenthesized list init for reference";
+      break;
+
     case FK_ReferenceBindingToInitList:
       OS << "referencing binding to initializer list";
       break;
@@ -8223,3 +8300,219 @@ Sema::PerformCopyInitialization(const InitializedEntity &Entity,
 
   return Result;
 }
+
+QualType Sema::DeduceTemplateSpecializationFromInitializer(
+    TypeSourceInfo *TSInfo, const InitializedEntity &Entity,
+    const InitializationKind &Kind, MultiExprArg Inits) {
+  auto *DeducedTST = dyn_cast<DeducedTemplateSpecializationType>(
+      TSInfo->getType()->getContainedDeducedType());
+  assert(DeducedTST && "not a deduced template specialization type");
+
+  // We can only perform deduction for class templates.
+  auto TemplateName = DeducedTST->getTemplateName();
+  auto *Template =
+      dyn_cast_or_null<ClassTemplateDecl>(TemplateName.getAsTemplateDecl());
+  if (!Template) {
+    Diag(Kind.getLocation(),
+         diag::err_deduced_non_class_template_specialization_type)
+      << (int)getTemplateNameKindForDiagnostics(TemplateName) << TemplateName;
+    if (auto *TD = TemplateName.getAsTemplateDecl())
+      Diag(TD->getLocation(), diag::note_template_decl_here);
+    return QualType();
+  }
+
+  // Can't deduce from dependent arguments.
+  if (Expr::hasAnyTypeDependentArguments(Inits))
+    return Context.DependentTy;
+
+  // FIXME: Perform "exact type" matching first, per CWG discussion?
+  //        Or implement this via an implied 'T(T) -> T' deduction guide?
+
+  // FIXME: Do we need/want a std::initializer_list<T> special case?
+
+  // Look up deduction guides, including those synthesized from constructors.
+  //
+  // C++1z [over.match.class.deduct]p1:
+  //   A set of functions and function templates is formed comprising:
+  //   - For each constructor of the class template designated by the
+  //     template-name, a function template [...]
+  //  - For each deduction-guide, a function or function template [...]
+  DeclarationNameInfo NameInfo(
+      Context.DeclarationNames.getCXXDeductionGuideName(Template),
+      TSInfo->getTypeLoc().getEndLoc());
+  LookupResult Guides(*this, NameInfo, LookupOrdinaryName);
+  LookupQualifiedName(Guides, Template->getDeclContext());
+
+  // FIXME: Do not diagnose inaccessible deduction guides. The standard isn't
+  // clear on this, but they're not found by name so access does not apply.
+  Guides.suppressDiagnostics();
+
+  // Figure out if this is list-initialization.
+  InitListExpr *ListInit =
+      (Inits.size() == 1 && Kind.getKind() != InitializationKind::IK_Direct)
+          ? dyn_cast<InitListExpr>(Inits[0])
+          : nullptr;
+
+  // C++1z [over.match.class.deduct]p1:
+  //   Initialization and overload resolution are performed as described in
+  //   [dcl.init] and [over.match.ctor], [over.match.copy], or [over.match.list]
+  //   (as appropriate for the type of initialization performed) for an object
+  //   of a hypothetical class type, where the selected functions and function
+  //   templates are considered to be the constructors of that class type
+  //
+  // Since we know we're initializing a class type of a type unrelated to that
+  // of the initializer, this reduces to something fairly reasonable.
+  OverloadCandidateSet Candidates(Kind.getLocation(),
+                                  OverloadCandidateSet::CSK_Normal);
+  OverloadCandidateSet::iterator Best;
+  auto tryToResolveOverload =
+      [&](bool OnlyListConstructors) -> OverloadingResult {
+    Candidates.clear();
+    for (auto I = Guides.begin(), E = Guides.end(); I != E; ++I) {
+      NamedDecl *D = (*I)->getUnderlyingDecl();
+      if (D->isInvalidDecl())
+        continue;
+
+      auto *TD = dyn_cast<FunctionTemplateDecl>(D);
+      auto *GD = dyn_cast_or_null<CXXDeductionGuideDecl>(
+          TD ? TD->getTemplatedDecl() : dyn_cast<FunctionDecl>(D));
+      if (!GD)
+        continue;
+
+      // C++ [over.match.ctor]p1: (non-list copy-initialization from non-class)
+      //   For copy-initialization, the candidate functions are all the
+      //   converting constructors (12.3.1) of that class.
+      // C++ [over.match.copy]p1: (non-list copy-initialization from class)
+      //   The converting constructors of T are candidate functions.
+      if (Kind.isCopyInit() && !ListInit) {
+        // Only consider converting constructors.
+        if (GD->isExplicit())
+          continue;
+
+        // When looking for a converting constructor, deduction guides that
+        // could never be called with one argument are not interesting to
+        // check or note.
+        if (GD->getMinRequiredArguments() > 1 ||
+            (GD->getNumParams() == 0 && !GD->isVariadic()))
+          continue;
+      }
+
+      // C++ [over.match.list]p1.1: (first phase list initialization)
+      //   Initially, the candidate functions are the initializer-list
+      //   constructors of the class T
+      if (OnlyListConstructors && !isInitListConstructor(GD))
+        continue;
+
+      // C++ [over.match.list]p1.2: (second phase list initialization)
+      //   the candidate functions are all the constructors of the class T
+      // C++ [over.match.ctor]p1: (all other cases)
+      //   the candidate functions are all the constructors of the class of
+      //   the object being initialized
+
+      // C++ [over.best.ics]p4:
+      //   When [...] the constructor [...] is a candidate by
+      //    - [over.match.copy] (in all cases)
+      // FIXME: The "second phase of [over.match.list] case can also
+      // theoretically happen here, but it's not clear whether we can
+      // ever have a parameter of the right type.
+      bool SuppressUserConversions = Kind.isCopyInit();
+
+      if (TD)
+        AddTemplateOverloadCandidate(TD, I.getPair(), /*ExplicitArgs*/ nullptr,
+                                     Inits, Candidates,
+                                     SuppressUserConversions);
+      else
+        AddOverloadCandidate(GD, I.getPair(), Inits, Candidates,
+                             SuppressUserConversions);
+    }
+    return Candidates.BestViableFunction(*this, Kind.getLocation(), Best);
+  };
+
+  OverloadingResult Result = OR_No_Viable_Function;
+
+  // C++11 [over.match.list]p1, per DR1467: for list-initialization, first
+  // try initializer-list constructors.
+  if (ListInit) {
+    bool TryListConstructors = true;
+
+    // Try list constructors unless the list is empty and the class has one or
+    // more default constructors, in which case those constructors win.
+    if (!ListInit->getNumInits()) {
+      for (NamedDecl *D : Guides) {
+        auto *FD = dyn_cast<FunctionDecl>(D->getUnderlyingDecl());
+        if (FD && FD->getMinRequiredArguments() == 0) {
+          TryListConstructors = false;
+          break;
+        }
+      }
+    }
+
+    if (TryListConstructors)
+      Result = tryToResolveOverload(/*OnlyListConstructor*/true);
+    // Then unwrap the initializer list and try again considering all
+    // constructors.
+    Inits = MultiExprArg(ListInit->getInits(), ListInit->getNumInits());
+  }
+
+  // If list-initialization fails, or if we're doing any other kind of
+  // initialization, we (eventually) consider constructors.
+  if (Result == OR_No_Viable_Function)
+    Result = tryToResolveOverload(/*OnlyListConstructor*/false);
+
+  switch (Result) {
+  case OR_Ambiguous:
+    Diag(Kind.getLocation(), diag::err_deduced_class_template_ctor_ambiguous)
+      << TemplateName;
+    // FIXME: For list-initialization candidates, it'd usually be better to
+    // list why they were not viable when given the initializer list itself as
+    // an argument.
+    Candidates.NoteCandidates(*this, OCD_ViableCandidates, Inits);
+    return QualType();
+
+  case OR_No_Viable_Function: {
+    CXXRecordDecl *Primary =
+        cast<ClassTemplateDecl>(Template)->getTemplatedDecl();
+    bool Complete =
+        isCompleteType(Kind.getLocation(), Context.getTypeDeclType(Primary));
+    Diag(Kind.getLocation(),
+         Complete ? diag::err_deduced_class_template_ctor_no_viable
+                  : diag::err_deduced_class_template_incomplete)
+      << TemplateName << !Guides.empty();
+    Candidates.NoteCandidates(*this, OCD_AllCandidates, Inits);
+    return QualType();
+  }
+
+  case OR_Deleted: {
+    Diag(Kind.getLocation(), diag::err_deduced_class_template_deleted)
+      << TemplateName;
+    NoteDeletedFunction(Best->Function);
+    return QualType();
+  }
+
+  case OR_Success:
+    // C++ [over.match.list]p1:
+    //   In copy-list-initialization, if an explicit constructor is chosen, the
+    //   initialization is ill-formed.
+    if (Kind.isCopyInit() && ListInit &&
+        cast<CXXDeductionGuideDecl>(Best->Function)->isExplicit()) {
+      bool IsDeductionGuide = !Best->Function->isImplicit();
+      Diag(Kind.getLocation(), diag::err_deduced_class_template_explicit)
+          << TemplateName << IsDeductionGuide;
+      Diag(Best->Function->getLocation(),
+           diag::note_explicit_ctor_deduction_guide_here)
+          << IsDeductionGuide;
+      return QualType();
+    }
+
+    // Make sure we didn't select an unusable deduction guide, and mark it
+    // as referenced.
+    DiagnoseUseOfDecl(Best->Function, Kind.getLocation());
+    MarkFunctionReferenced(Kind.getLocation(), Best->Function);
+    break;
+  }
+
+  // C++ [dcl.type.class.deduct]p1:
+  //  The placeholder is replaced by the return type of the function selected
+  //  by overload resolution for class template deduction.
+  return SubstAutoType(TSInfo->getType(), Best->Function->getReturnType());
+}
diff --git a/lib/Sema/SemaLambda.cpp b/lib/Sema/SemaLambda.cpp
index a0d574915eba..7a9a8ff911aa 100644
--- a/lib/Sema/SemaLambda.cpp
+++ b/lib/Sema/SemaLambda.cpp
@@ -312,7 +312,7 @@ Sema::getCurrentMangleNumberContext(const DeclContext *DC,
   //   In the following contexts [...] the one-definition rule requires closure
   //   types in different translation units to "correspond":
   bool IsInNonspecializedTemplate =
-    !ActiveTemplateInstantiations.empty() || CurContext->isDependentContext();
+      inTemplateInstantiation() || CurContext->isDependentContext();
   switch (Kind) {
   case Normal: {
     //  -- the bodies of non-exported nonspecialized template functions
@@ -763,7 +763,7 @@ QualType Sema::buildLambdaInitCaptureInitialization(SourceLocation Loc,
   // call-operator.
   Result = ActOnFinishFullExpr(Init, Loc, /*DiscardedValue*/ false,
                                /*IsConstexpr*/ false,
-                               /*IsLambdaInitCaptureInitalizer*/ true);
+                               /*IsLambdaInitCaptureInitializer*/ true);
   if (Result.isInvalid())
     return QualType();
 
@@ -1127,7 +1127,8 @@ void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
 
   // Enter a new evaluation context to insulate the lambda from any
   // cleanups from the enclosing full-expression.
-  PushExpressionEvaluationContext(PotentiallyEvaluated);  
+  PushExpressionEvaluationContext(
+      ExpressionEvaluationContext::PotentiallyEvaluated);
 }
 
 void Sema::ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope,
@@ -1384,7 +1385,7 @@ static void addBlockPointerConversion(Sema &S,
 }
 
 static ExprResult performLambdaVarCaptureInitialization(
-    Sema &S, LambdaScopeInfo::Capture &Capture, FieldDecl *Field) {
+    Sema &S, const LambdaScopeInfo::Capture &Capture, FieldDecl *Field) {
   assert(Capture.isVariableCapture() && "not a variable capture");
 
   auto *Var = Capture.getVariable();
@@ -1438,6 +1439,43 @@ mapImplicitCaptureStyle(CapturingScopeInfo::ImplicitCaptureStyle ICS) {
   llvm_unreachable("Unknown implicit capture style");
 }
 
+bool Sema::CaptureHasSideEffects(const LambdaScopeInfo::Capture &From) {
+  if (!From.isVLATypeCapture()) {
+    Expr *Init = From.getInitExpr();
+    if (Init && Init->HasSideEffects(Context))
+      return true;
+  }
+
+  if (!From.isCopyCapture())
+    return false;
+
+  const QualType T = From.isThisCapture()
+                         ? getCurrentThisType()->getPointeeType()
+                         : From.getCaptureType();
+
+  if (T.isVolatileQualified())
+    return true;
+
+  const Type *BaseT = T->getBaseElementTypeUnsafe();
+  if (const CXXRecordDecl *RD = BaseT->getAsCXXRecordDecl())
+    return !RD->isCompleteDefinition() || !RD->hasTrivialCopyConstructor() ||
+           !RD->hasTrivialDestructor();
+
+  return false;
+}
+
+void Sema::DiagnoseUnusedLambdaCapture(const LambdaScopeInfo::Capture &From) {
+  if (CaptureHasSideEffects(From))
+    return;
+
+  auto diag = Diag(From.getLocation(), diag::warn_unused_lambda_capture);
+  if (From.isThisCapture())
+    diag << "'this'";
+  else
+    diag << From.getVariable();
+  diag << From.isNonODRUsed();
+}
+
 ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
                                  LambdaScopeInfo *LSI) {
   // Collect information from the lambda scope.
@@ -1476,10 +1514,14 @@ ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
     // Translate captures.
     auto CurField = Class->field_begin();
     for (unsigned I = 0, N = LSI->Captures.size(); I != N; ++I, ++CurField) {
-      LambdaScopeInfo::Capture From = LSI->Captures[I];
+      const LambdaScopeInfo::Capture &From = LSI->Captures[I];
       assert(!From.isBlockCapture() && "Cannot capture __block variables");
       bool IsImplicit = I >= LSI->NumExplicitCaptures;
 
+      // Warn about unused explicit captures.
+      if (!CurContext->isDependentContext() && !IsImplicit && !From.isODRUsed())
+        DiagnoseUnusedLambdaCapture(From);
+
       // Handle 'this' capture.
       if (From.isThisCapture()) {
         Captures.push_back(
@@ -1564,9 +1606,9 @@ ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
     // C++11 [expr.prim.lambda]p2:
     //   A lambda-expression shall not appear in an unevaluated operand
     //   (Clause 5).
-    case Unevaluated:
-    case UnevaluatedList:
-    case UnevaluatedAbstract:
+    case ExpressionEvaluationContext::Unevaluated:
+    case ExpressionEvaluationContext::UnevaluatedList:
+    case ExpressionEvaluationContext::UnevaluatedAbstract:
     // C++1y [expr.const]p2:
     //   A conditional-expression e is a core constant expression unless the
     //   evaluation of e, following the rules of the abstract machine, would
@@ -1576,16 +1618,16 @@ ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
     // where this should be allowed.  We should probably fix this when DR1607 is
     // ratified, it lays out the exact set of conditions where we shouldn't
     // allow a lambda-expression.
-    case ConstantEvaluated:
+    case ExpressionEvaluationContext::ConstantEvaluated:
       // We don't actually diagnose this case immediately, because we
       // could be within a context where we might find out later that
       // the expression is potentially evaluated (e.g., for typeid).
       ExprEvalContexts.back().Lambdas.push_back(Lambda);
       break;
 
-    case DiscardedStatement:
-    case PotentiallyEvaluated:
-    case PotentiallyEvaluatedIfUsed:
+    case ExpressionEvaluationContext::DiscardedStatement:
+    case ExpressionEvaluationContext::PotentiallyEvaluated:
+    case ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
       break;
     }
   }
@@ -1607,10 +1649,9 @@ ExprResult Sema::BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
   CallOperator->markUsed(Context);
 
   ExprResult Init = PerformCopyInitialization(
-                      InitializedEntity::InitializeBlock(ConvLocation, 
-                                                         Src->getType(), 
-                                                         /*NRVO=*/false),
-                      CurrentLocation, Src);
+      InitializedEntity::InitializeLambdaToBlock(ConvLocation, Src->getType(),
+                                                 /*NRVO=*/false),
+      CurrentLocation, Src);
   if (!Init.isInvalid())
     Init = ActOnFinishFullExpr(Init.get());
   
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index e2cb2c8169ce..e4d420f36832 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -774,6 +774,7 @@ static bool isImplicitlyDeclaredMemberFunctionName(DeclarationName Name) {
 /// that need to be declared in the given declaration context, do so.
 static void DeclareImplicitMemberFunctionsWithName(Sema &S,
                                                    DeclarationName Name,
+                                                   SourceLocation Loc,
                                                    const DeclContext *DC) {
   if (!DC)
     return;
@@ -816,6 +817,10 @@ static void DeclareImplicitMemberFunctionsWithName(Sema &S,
     }
     break;
 
+  case DeclarationName::CXXDeductionGuideName:
+    S.DeclareImplicitDeductionGuides(Name.getCXXDeductionGuideTemplate(), Loc);
+    break;
+
   default:
     break;
   }
@@ -828,13 +833,12 @@ static bool LookupDirect(Sema &S, LookupResult &R, const DeclContext *DC) {
 
   // Lazily declare C++ special member functions.
   if (S.getLangOpts().CPlusPlus)
-    DeclareImplicitMemberFunctionsWithName(S, R.getLookupName(), DC);
+    DeclareImplicitMemberFunctionsWithName(S, R.getLookupName(), R.getNameLoc(),
+                                           DC);
 
   // Perform lookup into this declaration context.
   DeclContext::lookup_result DR = DC->lookup(R.getLookupName());
-  for (DeclContext::lookup_iterator I = DR.begin(), E = DR.end(); I != E;
-       ++I) {
-    NamedDecl *D = *I;
+  for (NamedDecl *D : DR) {
     if ((D = R.getAcceptableDecl(D))) {
       R.addDecl(D);
       Found = true;
@@ -1041,7 +1045,7 @@ bool Sema::CppLookupName(LookupResult &R, Scope *S) {
   if (isImplicitlyDeclaredMemberFunctionName(Name)) {
     for (Scope *PreS = S; PreS; PreS = PreS->getParent())
       if (DeclContext *DC = PreS->getEntity())
-        DeclareImplicitMemberFunctionsWithName(*this, Name, DC);
+        DeclareImplicitMemberFunctionsWithName(*this, Name, R.getNameLoc(), DC);
   }
 
   // Implicitly declare member functions with the name we're looking for, if in
@@ -1426,14 +1430,13 @@ static Module *getDefiningModule(Sema &S, Decl *Entity) {
 }
 
 llvm::DenseSet<Module*> &Sema::getLookupModules() {
-  unsigned N = ActiveTemplateInstantiations.size();
-  for (unsigned I = ActiveTemplateInstantiationLookupModules.size();
+  unsigned N = CodeSynthesisContexts.size();
+  for (unsigned I = CodeSynthesisContextLookupModules.size();
        I != N; ++I) {
-    Module *M =
-        getDefiningModule(*this, ActiveTemplateInstantiations[I].Entity);
+    Module *M = getDefiningModule(*this, CodeSynthesisContexts[I].Entity);
     if (M && !LookupModulesCache.insert(M).second)
       M = nullptr;
-    ActiveTemplateInstantiationLookupModules.push_back(M);
+    CodeSynthesisContextLookupModules.push_back(M);
   }
   return LookupModulesCache;
 }
@@ -1554,7 +1557,7 @@ bool LookupResult::isVisibleSlow(Sema &SemaRef, NamedDecl *D) {
          || (isa<FunctionDecl>(DC) && !SemaRef.getLangOpts().CPlusPlus))
             ? isVisible(SemaRef, cast<NamedDecl>(DC))
             : SemaRef.hasVisibleDefinition(cast<NamedDecl>(DC))) {
-      if (SemaRef.ActiveTemplateInstantiations.empty() &&
+      if (SemaRef.CodeSynthesisContexts.empty() &&
           // FIXME: Do something better in this case.
           !SemaRef.getLangOpts().ModulesLocalVisibility) {
         // Cache the fact that this declaration is implicitly visible because
@@ -2694,6 +2697,7 @@ addAssociatedClassesAndNamespaces(AssociatedLookup &Result, QualType Ty) {
 
     // Non-deduced auto types only get here for error cases.
     case Type::Auto:
+    case Type::DeducedTemplateSpecialization:
       break;
 
     // If T is an Objective-C object or interface type, or a pointer to an 
@@ -2814,13 +2818,13 @@ void Sema::LookupOverloadedOperatorName(OverloadedOperatorKind Op, Scope *S,
   Functions.append(Operators.begin(), Operators.end());
 }
 
-Sema::SpecialMemberOverloadResult *Sema::LookupSpecialMember(CXXRecordDecl *RD,
-                                                            CXXSpecialMember SM,
-                                                            bool ConstArg,
-                                                            bool VolatileArg,
-                                                            bool RValueThis,
-                                                            bool ConstThis,
-                                                            bool VolatileThis) {
+Sema::SpecialMemberOverloadResult Sema::LookupSpecialMember(CXXRecordDecl *RD,
+                                                           CXXSpecialMember SM,
+                                                           bool ConstArg,
+                                                           bool VolatileArg,
+                                                           bool RValueThis,
+                                                           bool ConstThis,
+                                                           bool VolatileThis) {
   assert(CanDeclareSpecialMemberFunction(RD) &&
          "doing special member lookup into record that isn't fully complete");
   RD = RD->getDefinition();
@@ -2844,15 +2848,15 @@ Sema::SpecialMemberOverloadResult *Sema::LookupSpecialMember(CXXRecordDecl *RD,
   ID.AddInteger(VolatileThis);
 
   void *InsertPoint;
-  SpecialMemberOverloadResult *Result =
+  SpecialMemberOverloadResultEntry *Result =
     SpecialMemberCache.FindNodeOrInsertPos(ID, InsertPoint);
 
   // This was already cached
   if (Result)
-    return Result;
+    return *Result;
 
-  Result = BumpAlloc.Allocate<SpecialMemberOverloadResult>();
-  Result = new (Result) SpecialMemberOverloadResult(ID);
+  Result = BumpAlloc.Allocate<SpecialMemberOverloadResultEntry>();
+  Result = new (Result) SpecialMemberOverloadResultEntry(ID);
   SpecialMemberCache.InsertNode(Result, InsertPoint);
 
   if (SM == CXXDestructor) {
@@ -2864,7 +2868,7 @@ Sema::SpecialMemberOverloadResult *Sema::LookupSpecialMember(CXXRecordDecl *RD,
     Result->setKind(DD->isDeleted() ?
                     SpecialMemberOverloadResult::NoMemberOrDeleted :
                     SpecialMemberOverloadResult::Success);
-    return Result;
+    return *Result;
   }
 
   // Prepare for overload resolution. Here we construct a synthetic argument
@@ -2947,7 +2951,7 @@ Sema::SpecialMemberOverloadResult *Sema::LookupSpecialMember(CXXRecordDecl *RD,
            "lookup for a constructor or assignment operator was empty");
     Result->setMethod(nullptr);
     Result->setKind(SpecialMemberOverloadResult::NoMemberOrDeleted);
-    return Result;
+    return *Result;
   }
 
   // Copy the candidates as our processing of them may load new declarations
@@ -3012,16 +3016,16 @@ Sema::SpecialMemberOverloadResult *Sema::LookupSpecialMember(CXXRecordDecl *RD,
       break;
   }
 
-  return Result;
+  return *Result;
 }
 
 /// \brief Look up the default constructor for the given class.
 CXXConstructorDecl *Sema::LookupDefaultConstructor(CXXRecordDecl *Class) {
-  SpecialMemberOverloadResult *Result =
+  SpecialMemberOverloadResult Result =
     LookupSpecialMember(Class, CXXDefaultConstructor, false, false, false,
                         false, false);
 
-  return cast_or_null<CXXConstructorDecl>(Result->getMethod());
+  return cast_or_null<CXXConstructorDecl>(Result.getMethod());
 }
 
 /// \brief Look up the copying constructor for the given class.
@@ -3029,21 +3033,21 @@ CXXConstructorDecl *Sema::LookupCopyingConstructor(CXXRecordDecl *Class,
                                                    unsigned Quals) {
   assert(!(Quals & ~(Qualifiers::Const | Qualifiers::Volatile)) &&
          "non-const, non-volatile qualifiers for copy ctor arg");
-  SpecialMemberOverloadResult *Result =
+  SpecialMemberOverloadResult Result =
     LookupSpecialMember(Class, CXXCopyConstructor, Quals & Qualifiers::Const,
                         Quals & Qualifiers::Volatile, false, false, false);
 
-  return cast_or_null<CXXConstructorDecl>(Result->getMethod());
+  return cast_or_null<CXXConstructorDecl>(Result.getMethod());
 }
 
 /// \brief Look up the moving constructor for the given class.
 CXXConstructorDecl *Sema::LookupMovingConstructor(CXXRecordDecl *Class,
                                                   unsigned Quals) {
-  SpecialMemberOverloadResult *Result =
+  SpecialMemberOverloadResult Result =
     LookupSpecialMember(Class, CXXMoveConstructor, Quals & Qualifiers::Const,
                         Quals & Qualifiers::Volatile, false, false, false);
 
-  return cast_or_null<CXXConstructorDecl>(Result->getMethod());
+  return cast_or_null<CXXConstructorDecl>(Result.getMethod());
 }
 
 /// \brief Look up the constructors for the given class.
@@ -3071,13 +3075,13 @@ CXXMethodDecl *Sema::LookupCopyingAssignment(CXXRecordDecl *Class,
          "non-const, non-volatile qualifiers for copy assignment arg");
   assert(!(ThisQuals & ~(Qualifiers::Const | Qualifiers::Volatile)) &&
          "non-const, non-volatile qualifiers for copy assignment this");
-  SpecialMemberOverloadResult *Result =
+  SpecialMemberOverloadResult Result =
     LookupSpecialMember(Class, CXXCopyAssignment, Quals & Qualifiers::Const,
                         Quals & Qualifiers::Volatile, RValueThis,
                         ThisQuals & Qualifiers::Const,
                         ThisQuals & Qualifiers::Volatile);
 
-  return Result->getMethod();
+  return Result.getMethod();
 }
 
 /// \brief Look up the moving assignment operator for the given class.
@@ -3087,13 +3091,13 @@ CXXMethodDecl *Sema::LookupMovingAssignment(CXXRecordDecl *Class,
                                             unsigned ThisQuals) {
   assert(!(ThisQuals & ~(Qualifiers::Const | Qualifiers::Volatile)) &&
          "non-const, non-volatile qualifiers for copy assignment this");
-  SpecialMemberOverloadResult *Result =
+  SpecialMemberOverloadResult Result =
     LookupSpecialMember(Class, CXXMoveAssignment, Quals & Qualifiers::Const,
                         Quals & Qualifiers::Volatile, RValueThis,
                         ThisQuals & Qualifiers::Const,
                         ThisQuals & Qualifiers::Volatile);
 
-  return Result->getMethod();
+  return Result.getMethod();
 }
 
 /// \brief Look for the destructor of the given class.
@@ -3105,7 +3109,7 @@ CXXMethodDecl *Sema::LookupMovingAssignment(CXXRecordDecl *Class,
 CXXDestructorDecl *Sema::LookupDestructor(CXXRecordDecl *Class) {
   return cast<CXXDestructorDecl>(LookupSpecialMember(Class, CXXDestructor,
                                                      false, false, false,
-                                                     false, false)->getMethod());
+                                                     false, false).getMethod());
 }
 
 /// LookupLiteralOperator - Determine which literal operator should be used for
@@ -3430,6 +3434,12 @@ NamedDecl *VisibleDeclsRecord::checkHidden(NamedDecl *ND) {
           SM == ShadowMaps.rbegin())
         continue;
 
+      // A shadow declaration that's created by a resolved using declaration
+      // is not hidden by the same using declaration.
+      if (isa<UsingShadowDecl>(ND) && isa<UsingDecl>(D) &&
+          cast<UsingShadowDecl>(ND)->getUsingDecl() == D)
+        continue;
+
       // We've found a declaration that hides this one.
       return D;
     }
@@ -4498,9 +4508,8 @@ std::unique_ptr<TypoCorrectionConsumer> Sema::makeTypoCorrectionConsumer(
   if (SS && SS->isInvalid())
     return nullptr;
 
-  // Never try to correct typos during template deduction or
-  // instantiation.
-  if (!ActiveTemplateInstantiations.empty())
+  // Never try to correct typos during any kind of code synthesis.
+  if (!CodeSynthesisContexts.empty())
     return nullptr;
 
   // Don't try to correct 'super'.
diff --git a/lib/Sema/SemaObjCProperty.cpp b/lib/Sema/SemaObjCProperty.cpp
index 3481b82679c2..6c5716454874 100644
--- a/lib/Sema/SemaObjCProperty.cpp
+++ b/lib/Sema/SemaObjCProperty.cpp
@@ -200,9 +200,10 @@ Decl *Sema::ActOnProperty(Scope *S, SourceLocation AtLoc,
   if (ObjCCategoryDecl *CDecl = dyn_cast<ObjCCategoryDecl>(ClassDecl)) {
     if (CDecl->IsClassExtension()) {
       Res = HandlePropertyInClassExtension(S, AtLoc, LParenLoc,
-                                           FD, GetterSel, SetterSel,
-                                           isReadWrite,
-                                           Attributes,
+                                           FD,
+                                           GetterSel, ODS.getGetterNameLoc(),
+                                           SetterSel, ODS.getSetterNameLoc(),
+                                           isReadWrite, Attributes,
                                            ODS.getPropertyAttributes(),
                                            T, TSI, MethodImplKind);
       if (!Res)
@@ -212,9 +213,10 @@ Decl *Sema::ActOnProperty(Scope *S, SourceLocation AtLoc,
 
   if (!Res) {
     Res = CreatePropertyDecl(S, ClassDecl, AtLoc, LParenLoc, FD,
-                             GetterSel, SetterSel, isReadWrite,
-                             Attributes, ODS.getPropertyAttributes(),
-                             T, TSI, MethodImplKind);
+                             GetterSel, ODS.getGetterNameLoc(), SetterSel,
+                             ODS.getSetterNameLoc(), isReadWrite, Attributes,
+                             ODS.getPropertyAttributes(), T, TSI,
+                             MethodImplKind);
     if (lexicalDC)
       Res->setLexicalDeclContext(lexicalDC);
   }
@@ -412,7 +414,10 @@ Sema::HandlePropertyInClassExtension(Scope *S,
                                      SourceLocation AtLoc,
                                      SourceLocation LParenLoc,
                                      FieldDeclarator &FD,
-                                     Selector GetterSel, Selector SetterSel,
+                                     Selector GetterSel,
+                                     SourceLocation GetterNameLoc,
+                                     Selector SetterSel,
+                                     SourceLocation SetterNameLoc,
                                      const bool isReadWrite,
                                      unsigned &Attributes,
                                      const unsigned AttributesAsWritten,
@@ -512,7 +517,8 @@ Sema::HandlePropertyInClassExtension(Scope *S,
   // Create a new ObjCPropertyDecl with the DeclContext being
   // the class extension.
   ObjCPropertyDecl *PDecl = CreatePropertyDecl(S, CDecl, AtLoc, LParenLoc,
-                                               FD, GetterSel, SetterSel,
+                                               FD, GetterSel, GetterNameLoc,
+                                               SetterSel, SetterNameLoc,
                                                isReadWrite,
                                                Attributes, AttributesAsWritten,
                                                T, TSI, MethodImplKind, DC);
@@ -562,7 +568,9 @@ ObjCPropertyDecl *Sema::CreatePropertyDecl(Scope *S,
                                            SourceLocation LParenLoc,
                                            FieldDeclarator &FD,
                                            Selector GetterSel,
+                                           SourceLocation GetterNameLoc,
                                            Selector SetterSel,
+                                           SourceLocation SetterNameLoc,
                                            const bool isReadWrite,
                                            const unsigned Attributes,
                                            const unsigned AttributesAsWritten,
@@ -640,8 +648,8 @@ ObjCPropertyDecl *Sema::CreatePropertyDecl(Scope *S,
 
   // Regardless of setter/getter attribute, we save the default getter/setter
   // selector names in anticipation of declaration of setter/getter methods.
-  PDecl->setGetterName(GetterSel);
-  PDecl->setSetterName(SetterSel);
+  PDecl->setGetterName(GetterSel, GetterNameLoc);
+  PDecl->setSetterName(SetterSel, SetterNameLoc);
   PDecl->setPropertyAttributesAsWritten(
                           makePropertyAttributesAsWritten(AttributesAsWritten));
 
@@ -2177,12 +2185,9 @@ void Sema::ProcessPropertyDecl(ObjCPropertyDecl *property) {
   DiagnosePropertyAccessorMismatch(property, GetterMethod,
                                    property->getLocation());
 
-  if (SetterMethod) {
-    ObjCPropertyDecl::PropertyAttributeKind CAttr =
-      property->getPropertyAttributes();
-    if ((!(CAttr & ObjCPropertyDecl::OBJC_PR_readonly)) &&
-        Context.getCanonicalType(SetterMethod->getReturnType()) !=
-            Context.VoidTy)
+  if (!property->isReadOnly() && SetterMethod) {
+    if (Context.getCanonicalType(SetterMethod->getReturnType()) !=
+        Context.VoidTy)
       Diag(SetterMethod->getLocation(), diag::err_setter_type_void);
     if (SetterMethod->param_size() != 1 ||
         !Context.hasSameUnqualifiedType(
diff --git a/lib/Sema/SemaOpenMP.cpp b/lib/Sema/SemaOpenMP.cpp
index dcd19c8d817d..616ab05eaec8 100644
--- a/lib/Sema/SemaOpenMP.cpp
+++ b/lib/Sema/SemaOpenMP.cpp
@@ -1050,7 +1050,8 @@ void Sema::StartOpenMPDSABlock(OpenMPDirectiveKind DKind,
                                const DeclarationNameInfo &DirName,
                                Scope *CurScope, SourceLocation Loc) {
   DSAStack->push(DKind, DirName, CurScope, Loc);
-  PushExpressionEvaluationContext(PotentiallyEvaluated);
+  PushExpressionEvaluationContext(
+      ExpressionEvaluationContext::PotentiallyEvaluated);
 }
 
 void Sema::StartOpenMPClause(OpenMPClauseKind K) {
@@ -1594,8 +1595,7 @@ void Sema::ActOnOpenMPRegionStart(OpenMPDirectiveKind DKind, Scope *CurScope) {
   case OMPD_parallel_for:
   case OMPD_parallel_for_simd:
   case OMPD_parallel_sections:
-  case OMPD_teams:
-  case OMPD_target_teams: {
+  case OMPD_teams: {
     QualType KmpInt32Ty = Context.getIntTypeForBitwidth(32, 1);
     QualType KmpInt32PtrTy =
         Context.getPointerType(KmpInt32Ty).withConst().withRestrict();
@@ -1608,6 +1608,28 @@ void Sema::ActOnOpenMPRegionStart(OpenMPDirectiveKind DKind, Scope *CurScope) {
                              Params);
     break;
   }
+  case OMPD_target_teams:
+  case OMPD_target_parallel: {
+    Sema::CapturedParamNameType ParamsTarget[] = {
+        std::make_pair(StringRef(), QualType()) // __context with shared vars
+    };
+    // Start a captured region for 'target' with no implicit parameters.
+    ActOnCapturedRegionStart(DSAStack->getConstructLoc(), CurScope, CR_OpenMP,
+                             ParamsTarget);
+    QualType KmpInt32Ty = Context.getIntTypeForBitwidth(32, 1);
+    QualType KmpInt32PtrTy =
+        Context.getPointerType(KmpInt32Ty).withConst().withRestrict();
+    Sema::CapturedParamNameType ParamsTeamsOrParallel[] = {
+        std::make_pair(".global_tid.", KmpInt32PtrTy),
+        std::make_pair(".bound_tid.", KmpInt32PtrTy),
+        std::make_pair(StringRef(), QualType()) // __context with shared vars
+    };
+    // Start a captured region for 'teams' or 'parallel'.  Both regions have
+    // the same implicit parameters.
+    ActOnCapturedRegionStart(DSAStack->getConstructLoc(), CurScope, CR_OpenMP,
+                             ParamsTeamsOrParallel);
+    break;
+  }
   case OMPD_simd:
   case OMPD_for:
   case OMPD_for_simd:
@@ -1622,7 +1644,6 @@ void Sema::ActOnOpenMPRegionStart(OpenMPDirectiveKind DKind, Scope *CurScope) {
   case OMPD_atomic:
   case OMPD_target_data:
   case OMPD_target:
-  case OMPD_target_parallel:
   case OMPD_target_parallel_for:
   case OMPD_target_parallel_for_simd:
   case OMPD_target_simd: {
@@ -1737,6 +1758,12 @@ void Sema::ActOnOpenMPRegionStart(OpenMPDirectiveKind DKind, Scope *CurScope) {
   }
 }
 
+int Sema::getOpenMPCaptureLevels(OpenMPDirectiveKind DKind) {
+  SmallVector<OpenMPDirectiveKind, 4> CaptureRegions;
+  getOpenMPCaptureRegions(CaptureRegions, DKind);
+  return CaptureRegions.size();
+}
+
 static OMPCapturedExprDecl *buildCaptureDecl(Sema &S, IdentifierInfo *Id,
                                              Expr *CaptureExpr, bool WithInit,
                                              bool AsExpression) {
@@ -1796,16 +1823,49 @@ static ExprResult buildCapture(Sema &S, Expr *CaptureExpr, DeclRefExpr *&Ref) {
   return CaptureExpr->isGLValue() ? Res : S.DefaultLvalueConversion(Res.get());
 }
 
+namespace {
+// OpenMP directives parsed in this section are represented as a
+// CapturedStatement with an associated statement.  If a syntax error
+// is detected during the parsing of the associated statement, the
+// compiler must abort processing and close the CapturedStatement.
+//
+// Combined directives such as 'target parallel' have more than one
+// nested CapturedStatements.  This RAII ensures that we unwind out
+// of all the nested CapturedStatements when an error is found.
+class CaptureRegionUnwinderRAII {
+private:
+  Sema &S;
+  bool &ErrorFound;
+  OpenMPDirectiveKind DKind;
+
+public:
+  CaptureRegionUnwinderRAII(Sema &S, bool &ErrorFound,
+                            OpenMPDirectiveKind DKind)
+      : S(S), ErrorFound(ErrorFound), DKind(DKind) {}
+  ~CaptureRegionUnwinderRAII() {
+    if (ErrorFound) {
+      int ThisCaptureLevel = S.getOpenMPCaptureLevels(DKind);
+      while (--ThisCaptureLevel >= 0)
+        S.ActOnCapturedRegionError();
+    }
+  }
+};
+} // namespace
+
 StmtResult Sema::ActOnOpenMPRegionEnd(StmtResult S,
                                       ArrayRef<OMPClause *> Clauses) {
+  bool ErrorFound = false;
+  CaptureRegionUnwinderRAII CaptureRegionUnwinder(
+      *this, ErrorFound, DSAStack->getCurrentDirective());
   if (!S.isUsable()) {
-    ActOnCapturedRegionError();
+    ErrorFound = true;
     return StmtError();
   }
 
   OMPOrderedClause *OC = nullptr;
   OMPScheduleClause *SC = nullptr;
   SmallVector<OMPLinearClause *, 4> LCs;
+  SmallVector<OMPClauseWithPreInit *, 8> PICs;
   // This is required for proper codegen.
   for (auto *Clause : Clauses) {
     if (isOpenMPPrivate(Clause->getClauseKind()) ||
@@ -1822,15 +1882,8 @@ StmtResult Sema::ActOnOpenMPRegionEnd(StmtResult S,
       }
       DSAStack->setForceVarCapturing(/*V=*/false);
     } else if (isParallelOrTaskRegion(DSAStack->getCurrentDirective())) {
-      // Mark all variables in private list clauses as used in inner region.
-      // Required for proper codegen of combined directives.
-      // TODO: add processing for other clauses.
-      if (auto *C = OMPClauseWithPreInit::get(Clause)) {
-        if (auto *DS = cast_or_null<DeclStmt>(C->getPreInitStmt())) {
-          for (auto *D : DS->decls())
-            MarkVariableReferenced(D->getLocation(), cast<VarDecl>(D));
-        }
-      }
+      if (auto *C = OMPClauseWithPreInit::get(Clause))
+        PICs.push_back(C);
       if (auto *C = OMPClauseWithPostUpdate::get(Clause)) {
         if (auto *E = C->getPostUpdateExpr())
           MarkDeclarationsReferencedInExpr(E);
@@ -1843,7 +1896,6 @@ StmtResult Sema::ActOnOpenMPRegionEnd(StmtResult S,
     else if (Clause->getClauseKind() == OMPC_linear)
       LCs.push_back(cast<OMPLinearClause>(Clause));
   }
-  bool ErrorFound = false;
   // OpenMP, 2.7.1 Loop Construct, Restrictions
   // The nonmonotonic modifier cannot be specified if an ordered clause is
   // specified.
@@ -1874,13 +1926,54 @@ StmtResult Sema::ActOnOpenMPRegionEnd(StmtResult S,
     ErrorFound = true;
   }
   if (ErrorFound) {
-    ActOnCapturedRegionError();
     return StmtError();
   }
-  return ActOnCapturedRegionEnd(S.get());
+  StmtResult SR = S;
+  SmallVector<OpenMPDirectiveKind, 4> CaptureRegions;
+  getOpenMPCaptureRegions(CaptureRegions, DSAStack->getCurrentDirective());
+  for (auto ThisCaptureRegion : llvm::reverse(CaptureRegions)) {
+    // Mark all variables in private list clauses as used in inner region.
+    // Required for proper codegen of combined directives.
+    // TODO: add processing for other clauses.
+    if (isParallelOrTaskRegion(DSAStack->getCurrentDirective())) {
+      for (auto *C : PICs) {
+        OpenMPDirectiveKind CaptureRegion = C->getCaptureRegion();
+        // Find the particular capture region for the clause if the
+        // directive is a combined one with multiple capture regions.
+        // If the directive is not a combined one, the capture region
+        // associated with the clause is OMPD_unknown and is generated
+        // only once.
+        if (CaptureRegion == ThisCaptureRegion ||
+            CaptureRegion == OMPD_unknown) {
+          if (auto *DS = cast_or_null<DeclStmt>(C->getPreInitStmt())) {
+            for (auto *D : DS->decls())
+              MarkVariableReferenced(D->getLocation(), cast<VarDecl>(D));
+          }
+        }
+      }
+    }
+    SR = ActOnCapturedRegionEnd(SR.get());
+  }
+  return SR;
 }
 
-static bool CheckNestingOfRegions(Sema &SemaRef, DSAStackTy *Stack,
+static bool checkCancelRegion(Sema &SemaRef, OpenMPDirectiveKind CurrentRegion,
+                              OpenMPDirectiveKind CancelRegion,
+                              SourceLocation StartLoc) {
+  // CancelRegion is only needed for cancel and cancellation_point.
+  if (CurrentRegion != OMPD_cancel && CurrentRegion != OMPD_cancellation_point)
+    return false;
+
+  if (CancelRegion == OMPD_parallel || CancelRegion == OMPD_for ||
+      CancelRegion == OMPD_sections || CancelRegion == OMPD_taskgroup)
+    return false;
+
+  SemaRef.Diag(StartLoc, diag::err_omp_wrong_cancel_region)
+      << getOpenMPDirectiveName(CancelRegion);
+  return true;
+}
+
+static bool checkNestingOfRegions(Sema &SemaRef, DSAStackTy *Stack,
                                   OpenMPDirectiveKind CurrentRegion,
                                   const DeclarationNameInfo &CurrentName,
                                   OpenMPDirectiveKind CancelRegion,
@@ -2180,7 +2273,9 @@ StmtResult Sema::ActOnOpenMPExecutableDirective(
     OpenMPDirectiveKind CancelRegion, ArrayRef<OMPClause *> Clauses,
     Stmt *AStmt, SourceLocation StartLoc, SourceLocation EndLoc) {
   StmtResult Res = StmtError();
-  if (CheckNestingOfRegions(*this, DSAStack, Kind, DirName, CancelRegion,
+  // First check CancelRegion which is then used in checkNestingOfRegions.
+  if (checkCancelRegion(*this, Kind, CancelRegion, StartLoc) ||
+      checkNestingOfRegions(*this, DSAStack, Kind, DirName, CancelRegion,
                             StartLoc))
     return StmtError();
 
@@ -2193,7 +2288,11 @@ StmtResult Sema::ActOnOpenMPExecutableDirective(
 
     // Check default data sharing attributes for referenced variables.
     DSAAttrChecker DSAChecker(DSAStack, *this, cast<CapturedStmt>(AStmt));
-    DSAChecker.Visit(cast<CapturedStmt>(AStmt)->getCapturedStmt());
+    int ThisCaptureLevel = getOpenMPCaptureLevels(Kind);
+    Stmt *S = AStmt;
+    while (--ThisCaptureLevel >= 0)
+      S = cast<CapturedStmt>(S)->getCapturedStmt();
+    DSAChecker.Visit(S);
     if (DSAChecker.isErrorFound())
       return StmtError();
     // Generate list of implicitly defined firstprivate variables.
@@ -4101,6 +4200,36 @@ CheckOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
       return 0;
   }
 
+  // Create: increment expression for distribute loop when combined in a same
+  // directive with for as IV = IV + ST; ensure upper bound expression based
+  // on PrevUB instead of NumIterations - used to implement 'for' when found
+  // in combination with 'distribute', like in 'distribute parallel for'
+  SourceLocation DistIncLoc;
+  ExprResult DistCond, DistInc, PrevEUB;
+  if (isOpenMPLoopBoundSharingDirective(DKind)) {
+    DistCond = SemaRef.BuildBinOp(CurScope, CondLoc, BO_LE, IV.get(), UB.get());
+    assert(DistCond.isUsable() && "distribute cond expr was not built");
+
+    DistInc =
+        SemaRef.BuildBinOp(CurScope, DistIncLoc, BO_Add, IV.get(), ST.get());
+    assert(DistInc.isUsable() && "distribute inc expr was not built");
+    DistInc = SemaRef.BuildBinOp(CurScope, DistIncLoc, BO_Assign, IV.get(),
+                                 DistInc.get());
+    DistInc = SemaRef.ActOnFinishFullExpr(DistInc.get());
+    assert(DistInc.isUsable() && "distribute inc expr was not built");
+
+    // Build expression: UB = min(UB, prevUB) for #for in composite or combined
+    // construct
+    SourceLocation DistEUBLoc;
+    ExprResult IsUBGreater =
+        SemaRef.BuildBinOp(CurScope, DistEUBLoc, BO_GT, UB.get(), PrevUB.get());
+    ExprResult CondOp = SemaRef.ActOnConditionalOp(
+        DistEUBLoc, DistEUBLoc, IsUBGreater.get(), PrevUB.get(), UB.get());
+    PrevEUB = SemaRef.BuildBinOp(CurScope, DistIncLoc, BO_Assign, UB.get(),
+                                 CondOp.get());
+    PrevEUB = SemaRef.ActOnFinishFullExpr(PrevEUB.get());
+  }
+
   // Build updates and final values of the loop counters.
   bool HasErrors = false;
   Built.Counters.resize(NestedLoopCount);
@@ -4215,6 +4344,8 @@ CheckOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
   Built.NUB = NextUB.get();
   Built.PrevLB = PrevLB.get();
   Built.PrevUB = PrevUB.get();
+  Built.DistInc = DistInc.get();
+  Built.PrevEUB = PrevEUB.get();
 
   Expr *CounterVal = SemaRef.DefaultLvalueConversion(IV.get()).get();
   // Fill data for doacross depend clauses.
@@ -5748,12 +5879,6 @@ StmtResult
 Sema::ActOnOpenMPCancellationPointDirective(SourceLocation StartLoc,
                                             SourceLocation EndLoc,
                                             OpenMPDirectiveKind CancelRegion) {
-  if (CancelRegion != OMPD_parallel && CancelRegion != OMPD_for &&
-      CancelRegion != OMPD_sections && CancelRegion != OMPD_taskgroup) {
-    Diag(StartLoc, diag::err_omp_wrong_cancel_region)
-        << getOpenMPDirectiveName(CancelRegion);
-    return StmtError();
-  }
   if (DSAStack->isParentNowaitRegion()) {
     Diag(StartLoc, diag::err_omp_parent_cancel_region_nowait) << 0;
     return StmtError();
@@ -5770,12 +5895,6 @@ StmtResult Sema::ActOnOpenMPCancelDirective(ArrayRef<OMPClause *> Clauses,
                                             SourceLocation StartLoc,
                                             SourceLocation EndLoc,
                                             OpenMPDirectiveKind CancelRegion) {
-  if (CancelRegion != OMPD_parallel && CancelRegion != OMPD_for &&
-      CancelRegion != OMPD_sections && CancelRegion != OMPD_taskgroup) {
-    Diag(StartLoc, diag::err_omp_wrong_cancel_region)
-        << getOpenMPDirectiveName(CancelRegion);
-    return StmtError();
-  }
   if (DSAStack->isParentNowaitRegion()) {
     Diag(StartLoc, diag::err_omp_parent_cancel_region_nowait) << 1;
     return StmtError();
@@ -6551,6 +6670,322 @@ OMPClause *Sema::ActOnOpenMPSingleExprClause(OpenMPClauseKind Kind, Expr *Expr,
   return Res;
 }
 
+// An OpenMP directive such as 'target parallel' has two captured regions:
+// for the 'target' and 'parallel' respectively.  This function returns
+// the region in which to capture expressions associated with a clause.
+// A return value of OMPD_unknown signifies that the expression should not
+// be captured.
+static OpenMPDirectiveKind getOpenMPCaptureRegionForClause(
+    OpenMPDirectiveKind DKind, OpenMPClauseKind CKind,
+    OpenMPDirectiveKind NameModifier = OMPD_unknown) {
+  OpenMPDirectiveKind CaptureRegion = OMPD_unknown;
+
+  switch (CKind) {
+  case OMPC_if:
+    switch (DKind) {
+    case OMPD_target_parallel:
+      // If this clause applies to the nested 'parallel' region, capture within
+      // the 'target' region, otherwise do not capture.
+      if (NameModifier == OMPD_unknown || NameModifier == OMPD_parallel)
+        CaptureRegion = OMPD_target;
+      break;
+    case OMPD_cancel:
+    case OMPD_parallel:
+    case OMPD_parallel_sections:
+    case OMPD_parallel_for:
+    case OMPD_parallel_for_simd:
+    case OMPD_target:
+    case OMPD_target_simd:
+    case OMPD_target_parallel_for:
+    case OMPD_target_parallel_for_simd:
+    case OMPD_target_teams:
+    case OMPD_target_teams_distribute:
+    case OMPD_target_teams_distribute_simd:
+    case OMPD_target_teams_distribute_parallel_for:
+    case OMPD_target_teams_distribute_parallel_for_simd:
+    case OMPD_teams_distribute_parallel_for:
+    case OMPD_teams_distribute_parallel_for_simd:
+    case OMPD_distribute_parallel_for:
+    case OMPD_distribute_parallel_for_simd:
+    case OMPD_task:
+    case OMPD_taskloop:
+    case OMPD_taskloop_simd:
+    case OMPD_target_data:
+    case OMPD_target_enter_data:
+    case OMPD_target_exit_data:
+    case OMPD_target_update:
+      // Do not capture if-clause expressions.
+      break;
+    case OMPD_threadprivate:
+    case OMPD_taskyield:
+    case OMPD_barrier:
+    case OMPD_taskwait:
+    case OMPD_cancellation_point:
+    case OMPD_flush:
+    case OMPD_declare_reduction:
+    case OMPD_declare_simd:
+    case OMPD_declare_target:
+    case OMPD_end_declare_target:
+    case OMPD_teams:
+    case OMPD_simd:
+    case OMPD_for:
+    case OMPD_for_simd:
+    case OMPD_sections:
+    case OMPD_section:
+    case OMPD_single:
+    case OMPD_master:
+    case OMPD_critical:
+    case OMPD_taskgroup:
+    case OMPD_distribute:
+    case OMPD_ordered:
+    case OMPD_atomic:
+    case OMPD_distribute_simd:
+    case OMPD_teams_distribute:
+    case OMPD_teams_distribute_simd:
+      llvm_unreachable("Unexpected OpenMP directive with if-clause");
+    case OMPD_unknown:
+      llvm_unreachable("Unknown OpenMP directive");
+    }
+    break;
+  case OMPC_num_threads:
+    switch (DKind) {
+    case OMPD_target_parallel:
+      CaptureRegion = OMPD_target;
+      break;
+    case OMPD_cancel:
+    case OMPD_parallel:
+    case OMPD_parallel_sections:
+    case OMPD_parallel_for:
+    case OMPD_parallel_for_simd:
+    case OMPD_target:
+    case OMPD_target_simd:
+    case OMPD_target_parallel_for:
+    case OMPD_target_parallel_for_simd:
+    case OMPD_target_teams:
+    case OMPD_target_teams_distribute:
+    case OMPD_target_teams_distribute_simd:
+    case OMPD_target_teams_distribute_parallel_for:
+    case OMPD_target_teams_distribute_parallel_for_simd:
+    case OMPD_teams_distribute_parallel_for:
+    case OMPD_teams_distribute_parallel_for_simd:
+    case OMPD_distribute_parallel_for:
+    case OMPD_distribute_parallel_for_simd:
+    case OMPD_task:
+    case OMPD_taskloop:
+    case OMPD_taskloop_simd:
+    case OMPD_target_data:
+    case OMPD_target_enter_data:
+    case OMPD_target_exit_data:
+    case OMPD_target_update:
+      // Do not capture num_threads-clause expressions.
+      break;
+    case OMPD_threadprivate:
+    case OMPD_taskyield:
+    case OMPD_barrier:
+    case OMPD_taskwait:
+    case OMPD_cancellation_point:
+    case OMPD_flush:
+    case OMPD_declare_reduction:
+    case OMPD_declare_simd:
+    case OMPD_declare_target:
+    case OMPD_end_declare_target:
+    case OMPD_teams:
+    case OMPD_simd:
+    case OMPD_for:
+    case OMPD_for_simd:
+    case OMPD_sections:
+    case OMPD_section:
+    case OMPD_single:
+    case OMPD_master:
+    case OMPD_critical:
+    case OMPD_taskgroup:
+    case OMPD_distribute:
+    case OMPD_ordered:
+    case OMPD_atomic:
+    case OMPD_distribute_simd:
+    case OMPD_teams_distribute:
+    case OMPD_teams_distribute_simd:
+      llvm_unreachable("Unexpected OpenMP directive with num_threads-clause");
+    case OMPD_unknown:
+      llvm_unreachable("Unknown OpenMP directive");
+    }
+    break;
+  case OMPC_num_teams:
+    switch (DKind) {
+    case OMPD_target_teams:
+      CaptureRegion = OMPD_target;
+      break;
+    case OMPD_cancel:
+    case OMPD_parallel:
+    case OMPD_parallel_sections:
+    case OMPD_parallel_for:
+    case OMPD_parallel_for_simd:
+    case OMPD_target:
+    case OMPD_target_simd:
+    case OMPD_target_parallel:
+    case OMPD_target_parallel_for:
+    case OMPD_target_parallel_for_simd:
+    case OMPD_target_teams_distribute:
+    case OMPD_target_teams_distribute_simd:
+    case OMPD_target_teams_distribute_parallel_for:
+    case OMPD_target_teams_distribute_parallel_for_simd:
+    case OMPD_teams_distribute_parallel_for:
+    case OMPD_teams_distribute_parallel_for_simd:
+    case OMPD_distribute_parallel_for:
+    case OMPD_distribute_parallel_for_simd:
+    case OMPD_task:
+    case OMPD_taskloop:
+    case OMPD_taskloop_simd:
+    case OMPD_target_data:
+    case OMPD_target_enter_data:
+    case OMPD_target_exit_data:
+    case OMPD_target_update:
+    case OMPD_teams:
+    case OMPD_teams_distribute:
+    case OMPD_teams_distribute_simd:
+      // Do not capture num_teams-clause expressions.
+      break;
+    case OMPD_threadprivate:
+    case OMPD_taskyield:
+    case OMPD_barrier:
+    case OMPD_taskwait:
+    case OMPD_cancellation_point:
+    case OMPD_flush:
+    case OMPD_declare_reduction:
+    case OMPD_declare_simd:
+    case OMPD_declare_target:
+    case OMPD_end_declare_target:
+    case OMPD_simd:
+    case OMPD_for:
+    case OMPD_for_simd:
+    case OMPD_sections:
+    case OMPD_section:
+    case OMPD_single:
+    case OMPD_master:
+    case OMPD_critical:
+    case OMPD_taskgroup:
+    case OMPD_distribute:
+    case OMPD_ordered:
+    case OMPD_atomic:
+    case OMPD_distribute_simd:
+      llvm_unreachable("Unexpected OpenMP directive with num_teams-clause");
+    case OMPD_unknown:
+      llvm_unreachable("Unknown OpenMP directive");
+    }
+    break;
+  case OMPC_thread_limit:
+    switch (DKind) {
+    case OMPD_target_teams:
+      CaptureRegion = OMPD_target;
+      break;
+    case OMPD_cancel:
+    case OMPD_parallel:
+    case OMPD_parallel_sections:
+    case OMPD_parallel_for:
+    case OMPD_parallel_for_simd:
+    case OMPD_target:
+    case OMPD_target_simd:
+    case OMPD_target_parallel:
+    case OMPD_target_parallel_for:
+    case OMPD_target_parallel_for_simd:
+    case OMPD_target_teams_distribute:
+    case OMPD_target_teams_distribute_simd:
+    case OMPD_target_teams_distribute_parallel_for:
+    case OMPD_target_teams_distribute_parallel_for_simd:
+    case OMPD_teams_distribute_parallel_for:
+    case OMPD_teams_distribute_parallel_for_simd:
+    case OMPD_distribute_parallel_for:
+    case OMPD_distribute_parallel_for_simd:
+    case OMPD_task:
+    case OMPD_taskloop:
+    case OMPD_taskloop_simd:
+    case OMPD_target_data:
+    case OMPD_target_enter_data:
+    case OMPD_target_exit_data:
+    case OMPD_target_update:
+    case OMPD_teams:
+    case OMPD_teams_distribute:
+    case OMPD_teams_distribute_simd:
+      // Do not capture thread_limit-clause expressions.
+      break;
+    case OMPD_threadprivate:
+    case OMPD_taskyield:
+    case OMPD_barrier:
+    case OMPD_taskwait:
+    case OMPD_cancellation_point:
+    case OMPD_flush:
+    case OMPD_declare_reduction:
+    case OMPD_declare_simd:
+    case OMPD_declare_target:
+    case OMPD_end_declare_target:
+    case OMPD_simd:
+    case OMPD_for:
+    case OMPD_for_simd:
+    case OMPD_sections:
+    case OMPD_section:
+    case OMPD_single:
+    case OMPD_master:
+    case OMPD_critical:
+    case OMPD_taskgroup:
+    case OMPD_distribute:
+    case OMPD_ordered:
+    case OMPD_atomic:
+    case OMPD_distribute_simd:
+      llvm_unreachable("Unexpected OpenMP directive with thread_limit-clause");
+    case OMPD_unknown:
+      llvm_unreachable("Unknown OpenMP directive");
+    }
+    break;
+  case OMPC_schedule:
+  case OMPC_dist_schedule:
+  case OMPC_firstprivate:
+  case OMPC_lastprivate:
+  case OMPC_reduction:
+  case OMPC_linear:
+  case OMPC_default:
+  case OMPC_proc_bind:
+  case OMPC_final:
+  case OMPC_safelen:
+  case OMPC_simdlen:
+  case OMPC_collapse:
+  case OMPC_private:
+  case OMPC_shared:
+  case OMPC_aligned:
+  case OMPC_copyin:
+  case OMPC_copyprivate:
+  case OMPC_ordered:
+  case OMPC_nowait:
+  case OMPC_untied:
+  case OMPC_mergeable:
+  case OMPC_threadprivate:
+  case OMPC_flush:
+  case OMPC_read:
+  case OMPC_write:
+  case OMPC_update:
+  case OMPC_capture:
+  case OMPC_seq_cst:
+  case OMPC_depend:
+  case OMPC_device:
+  case OMPC_threads:
+  case OMPC_simd:
+  case OMPC_map:
+  case OMPC_priority:
+  case OMPC_grainsize:
+  case OMPC_nogroup:
+  case OMPC_num_tasks:
+  case OMPC_hint:
+  case OMPC_defaultmap:
+  case OMPC_unknown:
+  case OMPC_uniform:
+  case OMPC_to:
+  case OMPC_from:
+  case OMPC_use_device_ptr:
+  case OMPC_is_device_ptr:
+    llvm_unreachable("Unexpected OpenMP clause.");
+  }
+  return CaptureRegion;
+}
+
 OMPClause *Sema::ActOnOpenMPIfClause(OpenMPDirectiveKind NameModifier,
                                      Expr *Condition, SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
@@ -6558,6 +6993,8 @@ OMPClause *Sema::ActOnOpenMPIfClause(OpenMPDirectiveKind NameModifier,
                                      SourceLocation ColonLoc,
                                      SourceLocation EndLoc) {
   Expr *ValExpr = Condition;
+  Stmt *HelperValStmt = nullptr;
+  OpenMPDirectiveKind CaptureRegion = OMPD_unknown;
   if (!Condition->isValueDependent() && !Condition->isTypeDependent() &&
       !Condition->isInstantiationDependent() &&
       !Condition->containsUnexpandedParameterPack()) {
@@ -6566,10 +7003,20 @@ OMPClause *Sema::ActOnOpenMPIfClause(OpenMPDirectiveKind NameModifier,
       return nullptr;
 
     ValExpr = MakeFullExpr(Val.get()).get();
+
+    OpenMPDirectiveKind DKind = DSAStack->getCurrentDirective();
+    CaptureRegion =
+        getOpenMPCaptureRegionForClause(DKind, OMPC_if, NameModifier);
+    if (CaptureRegion != OMPD_unknown) {
+      llvm::MapVector<Expr *, DeclRefExpr *> Captures;
+      ValExpr = tryBuildCapture(*this, ValExpr, Captures).get();
+      HelperValStmt = buildPreInits(Context, Captures);
+    }
   }
 
-  return new (Context) OMPIfClause(NameModifier, ValExpr, StartLoc, LParenLoc,
-                                   NameModifierLoc, ColonLoc, EndLoc);
+  return new (Context)
+      OMPIfClause(NameModifier, ValExpr, HelperValStmt, CaptureRegion, StartLoc,
+                  LParenLoc, NameModifierLoc, ColonLoc, EndLoc);
 }
 
 OMPClause *Sema::ActOnOpenMPFinalClause(Expr *Condition,
@@ -6665,6 +7112,8 @@ OMPClause *Sema::ActOnOpenMPNumThreadsClause(Expr *NumThreads,
                                              SourceLocation LParenLoc,
                                              SourceLocation EndLoc) {
   Expr *ValExpr = NumThreads;
+  Stmt *HelperValStmt = nullptr;
+  OpenMPDirectiveKind CaptureRegion = OMPD_unknown;
 
   // OpenMP [2.5, Restrictions]
   //  The num_threads expression must evaluate to a positive integer value.
@@ -6672,8 +7121,16 @@ OMPClause *Sema::ActOnOpenMPNumThreadsClause(Expr *NumThreads,
                                  /*StrictlyPositive=*/true))
     return nullptr;
 
-  return new (Context)
-      OMPNumThreadsClause(ValExpr, StartLoc, LParenLoc, EndLoc);
+  OpenMPDirectiveKind DKind = DSAStack->getCurrentDirective();
+  CaptureRegion = getOpenMPCaptureRegionForClause(DKind, OMPC_num_threads);
+  if (CaptureRegion != OMPD_unknown) {
+    llvm::MapVector<Expr *, DeclRefExpr *> Captures;
+    ValExpr = tryBuildCapture(*this, ValExpr, Captures).get();
+    HelperValStmt = buildPreInits(Context, Captures);
+  }
+
+  return new (Context) OMPNumThreadsClause(
+      ValExpr, HelperValStmt, CaptureRegion, StartLoc, LParenLoc, EndLoc);
 }
 
 ExprResult Sema::VerifyPositiveIntegerConstantInClause(Expr *E,
@@ -10451,7 +10908,8 @@ void Sema::ActOnOpenMPDeclareReductionCombinerStart(Scope *S, Decl *D) {
   else
     CurContext = DRD;
 
-  PushExpressionEvaluationContext(PotentiallyEvaluated);
+  PushExpressionEvaluationContext(
+      ExpressionEvaluationContext::PotentiallyEvaluated);
 
   QualType ReductionType = DRD->getType();
   // Create 'T* omp_parm;T omp_in;'. All references to 'omp_in' will
@@ -10505,7 +10963,8 @@ void Sema::ActOnOpenMPDeclareReductionInitializerStart(Scope *S, Decl *D) {
   else
     CurContext = DRD;
 
-  PushExpressionEvaluationContext(PotentiallyEvaluated);
+  PushExpressionEvaluationContext(
+      ExpressionEvaluationContext::PotentiallyEvaluated);
 
   QualType ReductionType = DRD->getType();
   // Create 'T* omp_parm;T omp_priv;'. All references to 'omp_priv' will
@@ -10566,6 +11025,8 @@ OMPClause *Sema::ActOnOpenMPNumTeamsClause(Expr *NumTeams,
                                            SourceLocation LParenLoc,
                                            SourceLocation EndLoc) {
   Expr *ValExpr = NumTeams;
+  Stmt *HelperValStmt = nullptr;
+  OpenMPDirectiveKind CaptureRegion = OMPD_unknown;
 
   // OpenMP [teams Constrcut, Restrictions]
   // The num_teams expression must evaluate to a positive integer value.
@@ -10573,7 +11034,16 @@ OMPClause *Sema::ActOnOpenMPNumTeamsClause(Expr *NumTeams,
                                  /*StrictlyPositive=*/true))
     return nullptr;
 
-  return new (Context) OMPNumTeamsClause(ValExpr, StartLoc, LParenLoc, EndLoc);
+  OpenMPDirectiveKind DKind = DSAStack->getCurrentDirective();
+  CaptureRegion = getOpenMPCaptureRegionForClause(DKind, OMPC_num_teams);
+  if (CaptureRegion != OMPD_unknown) {
+    llvm::MapVector<Expr *, DeclRefExpr *> Captures;
+    ValExpr = tryBuildCapture(*this, ValExpr, Captures).get();
+    HelperValStmt = buildPreInits(Context, Captures);
+  }
+
+  return new (Context) OMPNumTeamsClause(ValExpr, HelperValStmt, CaptureRegion,
+                                         StartLoc, LParenLoc, EndLoc);
 }
 
 OMPClause *Sema::ActOnOpenMPThreadLimitClause(Expr *ThreadLimit,
@@ -10581,6 +11051,8 @@ OMPClause *Sema::ActOnOpenMPThreadLimitClause(Expr *ThreadLimit,
                                               SourceLocation LParenLoc,
                                               SourceLocation EndLoc) {
   Expr *ValExpr = ThreadLimit;
+  Stmt *HelperValStmt = nullptr;
+  OpenMPDirectiveKind CaptureRegion = OMPD_unknown;
 
   // OpenMP [teams Constrcut, Restrictions]
   // The thread_limit expression must evaluate to a positive integer value.
@@ -10588,8 +11060,16 @@ OMPClause *Sema::ActOnOpenMPThreadLimitClause(Expr *ThreadLimit,
                                  /*StrictlyPositive=*/true))
     return nullptr;
 
-  return new (Context)
-      OMPThreadLimitClause(ValExpr, StartLoc, LParenLoc, EndLoc);
+  OpenMPDirectiveKind DKind = DSAStack->getCurrentDirective();
+  CaptureRegion = getOpenMPCaptureRegionForClause(DKind, OMPC_thread_limit);
+  if (CaptureRegion != OMPD_unknown) {
+    llvm::MapVector<Expr *, DeclRefExpr *> Captures;
+    ValExpr = tryBuildCapture(*this, ValExpr, Captures).get();
+    HelperValStmt = buildPreInits(Context, Captures);
+  }
+
+  return new (Context) OMPThreadLimitClause(
+      ValExpr, HelperValStmt, CaptureRegion, StartLoc, LParenLoc, EndLoc);
 }
 
 OMPClause *Sema::ActOnOpenMPPriorityClause(Expr *Priority,
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index f976b76727f5..29ba34479dab 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -131,7 +131,7 @@ ImplicitConversionRank clang::GetConversionRank(ImplicitConversionKind Kind) {
     ICR_Conversion,
     ICR_Conversion,
     ICR_Conversion,
-    ICR_Conversion,
+    ICR_OCL_Scalar_Widening,
     ICR_Complex_Real_Conversion,
     ICR_Conversion,
     ICR_Conversion,
@@ -917,40 +917,39 @@ static bool checkArgPlaceholdersForOverload(Sema &S,
   return false;
 }
 
-// IsOverload - Determine whether the given New declaration is an
-// overload of the declarations in Old. This routine returns false if
-// New and Old cannot be overloaded, e.g., if New has the same
-// signature as some function in Old (C++ 1.3.10) or if the Old
-// declarations aren't functions (or function templates) at all. When
-// it does return false, MatchedDecl will point to the decl that New
-// cannot be overloaded with.  This decl may be a UsingShadowDecl on
-// top of the underlying declaration.
-//
-// Example: Given the following input:
-//
-//   void f(int, float); // #1
-//   void f(int, int); // #2
-//   int f(int, int); // #3
-//
-// When we process #1, there is no previous declaration of "f",
-// so IsOverload will not be used.
-//
-// When we process #2, Old contains only the FunctionDecl for #1.  By
-// comparing the parameter types, we see that #1 and #2 are overloaded
-// (since they have different signatures), so this routine returns
-// false; MatchedDecl is unchanged.
-//
-// When we process #3, Old is an overload set containing #1 and #2. We
-// compare the signatures of #3 to #1 (they're overloaded, so we do
-// nothing) and then #3 to #2. Since the signatures of #3 and #2 are
-// identical (return types of functions are not part of the
-// signature), IsOverload returns false and MatchedDecl will be set to
-// point to the FunctionDecl for #2.
-//
-// 'NewIsUsingShadowDecl' indicates that 'New' is being introduced
-// into a class by a using declaration.  The rules for whether to hide
-// shadow declarations ignore some properties which otherwise figure
-// into a function template's signature.
+/// Determine whether the given New declaration is an overload of the
+/// declarations in Old. This routine returns Ovl_Match or Ovl_NonFunction if
+/// New and Old cannot be overloaded, e.g., if New has the same signature as
+/// some function in Old (C++ 1.3.10) or if the Old declarations aren't
+/// functions (or function templates) at all. When it does return Ovl_Match or
+/// Ovl_NonFunction, MatchedDecl will point to the decl that New cannot be
+/// overloaded with. This decl may be a UsingShadowDecl on top of the underlying
+/// declaration.
+///
+/// Example: Given the following input:
+///
+///   void f(int, float); // #1
+///   void f(int, int); // #2
+///   int f(int, int); // #3
+///
+/// When we process #1, there is no previous declaration of "f", so IsOverload
+/// will not be used.
+///
+/// When we process #2, Old contains only the FunctionDecl for #1. By comparing
+/// the parameter types, we see that #1 and #2 are overloaded (since they have
+/// different signatures), so this routine returns Ovl_Overload; MatchedDecl is
+/// unchanged.
+///
+/// When we process #3, Old is an overload set containing #1 and #2. We compare
+/// the signatures of #3 to #1 (they're overloaded, so we do nothing) and then
+/// #3 to #2. Since the signatures of #3 and #2 are identical (return types of
+/// functions are not part of the signature), IsOverload returns Ovl_Match and
+/// MatchedDecl will be set to point to the FunctionDecl for #2.
+///
+/// 'NewIsUsingShadowDecl' indicates that 'New' is being introduced into a class
+/// by a using declaration. The rules for whether to hide shadow declarations
+/// ignore some properties which otherwise figure into a function template's
+/// signature.
 Sema::OverloadKind
 Sema::CheckOverload(Scope *S, FunctionDecl *New, const LookupResult &Old,
                     NamedDecl *&Match, bool NewIsUsingDecl) {
@@ -4048,7 +4047,7 @@ CompareDerivedToBaseConversions(Sema &S, SourceLocation Loc,
         = S.Context.canAssignObjCInterfaces(ToPtr1, ToPtr2);
       bool ToAssignRight
         = S.Context.canAssignObjCInterfaces(ToPtr2, ToPtr1);
-      
+
       // A conversion to an a non-id object pointer type or qualified 'id' 
       // type is better than a conversion to 'id'.
       if (ToPtr1->isObjCIdType() &&
@@ -4082,11 +4081,25 @@ CompareDerivedToBaseConversions(Sema &S, SourceLocation Loc,
         return ImplicitConversionSequence::Better;
 
       //   -- "conversion of C* to B* is better than conversion of C* to A*,"
-      if (S.Context.hasSameType(FromType1, FromType2) && 
+      if (S.Context.hasSameType(FromType1, FromType2) &&
           !FromPtr1->isObjCIdType() && !FromPtr1->isObjCClassType() &&
-          (ToAssignLeft != ToAssignRight))
+          (ToAssignLeft != ToAssignRight)) {
+        if (FromPtr1->isSpecialized()) {
+          // "conversion of B<A> * to B * is better than conversion of B * to
+          // C *.
+          bool IsFirstSame =
+              FromPtr1->getInterfaceDecl() == ToPtr1->getInterfaceDecl();
+          bool IsSecondSame =
+              FromPtr1->getInterfaceDecl() == ToPtr2->getInterfaceDecl();
+          if (IsFirstSame) {
+            if (!IsSecondSame)
+              return ImplicitConversionSequence::Better;
+          } else if (IsSecondSame)
+            return ImplicitConversionSequence::Worse;
+        }
         return ToAssignLeft? ImplicitConversionSequence::Worse
                            : ImplicitConversionSequence::Better;
+      }
 
       //   -- "conversion of B* to A* is better than conversion of C* to A*,"
       if (S.Context.hasSameUnqualifiedType(ToType1, ToType2) &&
@@ -4264,7 +4277,7 @@ Sema::CompareReferenceRelationship(SourceLocation Loc,
     return Ref_Related;
 }
 
-/// \brief Look for a user-defined conversion to an value reference-compatible
+/// \brief Look for a user-defined conversion to a value reference-compatible
 ///        with DeclType. Return true if something definite is found.
 static bool
 FindConversionForRefInit(Sema &S, ImplicitConversionSequence &ICS,
@@ -5888,7 +5901,8 @@ Sema::AddOverloadCandidate(FunctionDecl *Function,
     return;
 
   // Overload resolution is always an unevaluated context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
 
   // Add this candidate
   OverloadCandidate &Candidate =
@@ -6307,30 +6321,45 @@ void Sema::AddFunctionCandidates(const UnresolvedSetImpl &Fns,
   for (UnresolvedSetIterator F = Fns.begin(), E = Fns.end(); F != E; ++F) {
     NamedDecl *D = F.getDecl()->getUnderlyingDecl();
     if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
-      if (isa<CXXMethodDecl>(FD) && !cast<CXXMethodDecl>(FD)->isStatic())
+      if (isa<CXXMethodDecl>(FD) && !cast<CXXMethodDecl>(FD)->isStatic()) {
+        QualType ObjectType;
+        Expr::Classification ObjectClassification;
+        if (Expr *E = Args[0]) {
+          // Use the explit base to restrict the lookup:
+          ObjectType = E->getType();
+          ObjectClassification = E->Classify(Context);
+        } // .. else there is an implit base.
         AddMethodCandidate(cast<CXXMethodDecl>(FD), F.getPair(),
-                           cast<CXXMethodDecl>(FD)->getParent(),
-                           Args[0]->getType(), Args[0]->Classify(Context),
-                           Args.slice(1), CandidateSet, SuppressUserConversions,
-                           PartialOverloading);
-      else
+                           cast<CXXMethodDecl>(FD)->getParent(), ObjectType,
+                           ObjectClassification, Args.slice(1), CandidateSet,
+                           SuppressUserConversions, PartialOverloading);
+      } else {
         AddOverloadCandidate(FD, F.getPair(), Args, CandidateSet,
                              SuppressUserConversions, PartialOverloading);
+      }
     } else {
       FunctionTemplateDecl *FunTmpl = cast<FunctionTemplateDecl>(D);
       if (isa<CXXMethodDecl>(FunTmpl->getTemplatedDecl()) &&
-          !cast<CXXMethodDecl>(FunTmpl->getTemplatedDecl())->isStatic())
+          !cast<CXXMethodDecl>(FunTmpl->getTemplatedDecl())->isStatic()) {
+        QualType ObjectType;
+        Expr::Classification ObjectClassification;
+        if (Expr *E = Args[0]) {
+          // Use the explit base to restrict the lookup:
+          ObjectType = E->getType();
+          ObjectClassification = E->Classify(Context);
+        } // .. else there is an implit base.
         AddMethodTemplateCandidate(
             FunTmpl, F.getPair(),
             cast<CXXRecordDecl>(FunTmpl->getDeclContext()),
-            ExplicitTemplateArgs, Args[0]->getType(),
-            Args[0]->Classify(Context), Args.slice(1), CandidateSet,
-            SuppressUserConversions, PartialOverloading);
-      else
+            ExplicitTemplateArgs, ObjectType, ObjectClassification,
+            Args.slice(1), CandidateSet, SuppressUserConversions,
+            PartialOverloading);
+      } else {
         AddTemplateOverloadCandidate(FunTmpl, F.getPair(),
                                      ExplicitTemplateArgs, Args,
                                      CandidateSet, SuppressUserConversions,
                                      PartialOverloading);
+      }
     }
   }
 }
@@ -6396,7 +6425,8 @@ Sema::AddMethodCandidate(CXXMethodDecl *Method, DeclAccessPair FoundDecl,
     return;
 
   // Overload resolution is always an unevaluated context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
 
   // Add this candidate
   OverloadCandidate &Candidate =
@@ -6652,7 +6682,8 @@ bool Sema::CheckNonDependentConversions(
       CandidateSet.allocateConversionSequences(ThisConversions + Args.size());
 
   // Overload resolution is always an unevaluated context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
 
   // For a method call, check the 'this' conversion here too. DR1391 doesn't
   // require that, but this check should never result in a hard error, and
@@ -6760,7 +6791,8 @@ Sema::AddConversionCandidate(CXXConversionDecl *Conversion,
     return;
 
   // Overload resolution is always an unevaluated context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
 
   // Add this candidate
   OverloadCandidate &Candidate = CandidateSet.addCandidate(1);
@@ -6951,7 +6983,8 @@ void Sema::AddSurrogateCandidate(CXXConversionDecl *Conversion,
     return;
 
   // Overload resolution is always an unevaluated context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
 
   OverloadCandidate &Candidate = CandidateSet.addCandidate(Args.size() + 1);
   Candidate.FoundDecl = FoundDecl;
@@ -7109,7 +7142,8 @@ void Sema::AddBuiltinCandidate(QualType ResultTy, QualType *ParamTys,
                                bool IsAssignmentOperator,
                                unsigned NumContextualBoolArguments) {
   // Overload resolution is always an unevaluated context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
 
   // Add this candidate
   OverloadCandidate &Candidate = CandidateSet.addCandidate(Args.size());
@@ -8991,6 +9025,12 @@ bool clang::isBetterOverloadCandidate(Sema &S, const OverloadCandidate &Cand1,
     // C++14 [over.match.best]p1 section 2 bullet 3.
   }
 
+  //    -- F1 is generated from a deduction-guide and F2 is not
+  auto *Guide1 = dyn_cast_or_null<CXXDeductionGuideDecl>(Cand1.Function);
+  auto *Guide2 = dyn_cast_or_null<CXXDeductionGuideDecl>(Cand2.Function);
+  if (Guide1 && Guide2 && Guide1->isImplicit() != Guide2->isImplicit())
+    return Guide2->isImplicit();
+
   //    -- F1 is a non-template function and F2 is a function template
   //       specialization, or, if not that,
   bool Cand1IsSpecialization = Cand1.Function &&
@@ -9488,7 +9528,8 @@ static void DiagnoseBadConversion(Sema &S, OverloadCandidate *Cand,
         << (unsigned) FnKind << FnDesc
         << (FromExpr ? FromExpr->getSourceRange() : SourceRange())
         << FromTy
-        << FromQs.getAddressSpace() << ToQs.getAddressSpace()
+        << FromQs.getAddressSpaceAttributePrintValue()
+        << ToQs.getAddressSpaceAttributePrintValue()
         << (unsigned) isObjectArgument << I+1;
       MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
       return;
@@ -11485,7 +11526,7 @@ DiagnoseTwoPhaseLookup(Sema &SemaRef, SourceLocation FnLoc,
                        TemplateArgumentListInfo *ExplicitTemplateArgs,
                        ArrayRef<Expr *> Args,
                        bool *DoDiagnoseEmptyLookup = nullptr) {
-  if (SemaRef.ActiveTemplateInstantiations.empty() || !SS.isEmpty())
+  if (!SemaRef.inTemplateInstantiation() || !SS.isEmpty())
     return false;
 
   for (DeclContext *DC = SemaRef.CurContext; DC; DC = DC->getParent()) {
@@ -11957,7 +11998,7 @@ Sema::CreateOverloadedUnaryOp(SourceLocation OpLoc, UnaryOperatorKind Opc,
                                      Fns.begin(), Fns.end());
     return new (Context)
         CXXOperatorCallExpr(Context, Op, Fn, ArgsArray, Context.DependentTy,
-                            VK_RValue, OpLoc, false);
+                            VK_RValue, OpLoc, FPOptions());
   }
 
   // Build an empty overload set.
@@ -12027,7 +12068,7 @@ Sema::CreateOverloadedUnaryOp(SourceLocation OpLoc, UnaryOperatorKind Opc,
       Args[0] = Input;
       CallExpr *TheCall =
         new (Context) CXXOperatorCallExpr(Context, Op, FnExpr.get(), ArgsArray,
-                                          ResultTy, VK, OpLoc, false);
+                                          ResultTy, VK, OpLoc, FPOptions());
 
       if (CheckCallReturnType(FnDecl->getReturnType(), OpLoc, TheCall, FnDecl))
         return ExprError();
@@ -12125,12 +12166,12 @@ Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
       if (Opc <= BO_Assign || Opc > BO_OrAssign)
         return new (Context) BinaryOperator(
             Args[0], Args[1], Opc, Context.DependentTy, VK_RValue, OK_Ordinary,
-            OpLoc, FPFeatures.fp_contract);
+            OpLoc, FPFeatures);
 
       return new (Context) CompoundAssignOperator(
           Args[0], Args[1], Opc, Context.DependentTy, VK_LValue, OK_Ordinary,
           Context.DependentTy, Context.DependentTy, OpLoc,
-          FPFeatures.fp_contract);
+          FPFeatures);
     }
 
     // FIXME: save results of ADL from here?
@@ -12144,7 +12185,7 @@ Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
                                      Fns.begin(), Fns.end());
     return new (Context)
         CXXOperatorCallExpr(Context, Op, Fn, Args, Context.DependentTy,
-                            VK_RValue, OpLoc, FPFeatures.fp_contract);
+                            VK_RValue, OpLoc, FPFeatures);
   }
 
   // Always do placeholder-like conversions on the RHS.
@@ -12259,7 +12300,7 @@ Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
         CXXOperatorCallExpr *TheCall =
           new (Context) CXXOperatorCallExpr(Context, Op, FnExpr.get(),
                                             Args, ResultTy, VK, OpLoc,
-                                            FPFeatures.fp_contract);
+                                            FPFeatures);
 
         if (CheckCallReturnType(FnDecl->getReturnType(), OpLoc, TheCall,
                                 FnDecl))
@@ -12407,7 +12448,7 @@ Sema::CreateOverloadedArraySubscriptExpr(SourceLocation LLoc,
 
     return new (Context)
         CXXOperatorCallExpr(Context, OO_Subscript, Fn, Args,
-                            Context.DependentTy, VK_RValue, RLoc, false);
+                            Context.DependentTy, VK_RValue, RLoc, FPOptions());
   }
 
   // Handle placeholders on both operands.
@@ -12483,7 +12524,7 @@ Sema::CreateOverloadedArraySubscriptExpr(SourceLocation LLoc,
           new (Context) CXXOperatorCallExpr(Context, OO_Subscript,
                                             FnExpr.get(), Args,
                                             ResultTy, VK, RLoc,
-                                            false);
+                                            FPOptions());
 
         if (CheckCallReturnType(FnDecl->getReturnType(), LLoc, TheCall, FnDecl))
           return ExprError();
@@ -13046,7 +13087,7 @@ Sema::BuildCallToObjectOfClassType(Scope *S, Expr *Obj,
 
   CXXOperatorCallExpr *TheCall = new (Context)
       CXXOperatorCallExpr(Context, OO_Call, NewFn.get(), MethodArgs, ResultTy,
-                          VK, RParenLoc, false);
+                          VK, RParenLoc, FPOptions());
 
   if (CheckCallReturnType(Method->getReturnType(), LParenLoc, TheCall, Method))
     return true;
@@ -13226,7 +13267,7 @@ Sema::BuildOverloadedArrowExpr(Scope *S, Expr *Base, SourceLocation OpLoc,
   ResultTy = ResultTy.getNonLValueExprType(Context);
   CXXOperatorCallExpr *TheCall =
     new (Context) CXXOperatorCallExpr(Context, OO_Arrow, FnExpr.get(),
-                                      Base, ResultTy, VK, OpLoc, false);
+                                      Base, ResultTy, VK, OpLoc, FPOptions());
 
   if (CheckCallReturnType(Method->getReturnType(), OpLoc, TheCall, Method))
     return ExprError();
diff --git a/lib/Sema/SemaPseudoObject.cpp b/lib/Sema/SemaPseudoObject.cpp
index 8e53fda846f4..b6b429d1f25c 100644
--- a/lib/Sema/SemaPseudoObject.cpp
+++ b/lib/Sema/SemaPseudoObject.cpp
@@ -447,7 +447,8 @@ PseudoOpBuilder::buildAssignmentOperation(Scope *Sc, SourceLocation opcLoc,
     syntactic = new (S.Context) BinaryOperator(syntacticLHS, capturedRHS,
                                                opcode, capturedRHS->getType(),
                                                capturedRHS->getValueKind(),
-                                               OK_Ordinary, opcLoc, false);
+                                               OK_Ordinary, opcLoc,
+                                               FPOptions());
   } else {
     ExprResult opLHS = buildGet();
     if (opLHS.isInvalid()) return ExprError();
@@ -465,7 +466,7 @@ PseudoOpBuilder::buildAssignmentOperation(Scope *Sc, SourceLocation opcLoc,
                                              OK_Ordinary,
                                              opLHS.get()->getType(),
                                              result.get()->getType(),
-                                             opcLoc, false);
+                                             opcLoc, FPOptions());
   }
 
   // The result of the assignment, if not void, is the value set into
@@ -841,12 +842,10 @@ ExprResult ObjCPropertyOpBuilder::buildRValueOperation(Expr *op) {
           result = S.ImpCastExprToType(result.get(), propType, CK_BitCast);
       }
     }
-    if (S.getLangOpts().ObjCAutoRefCount) {
-      Qualifiers::ObjCLifetime LT = propType.getObjCLifetime();
-      if (LT == Qualifiers::OCL_Weak)
-        if (!S.Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, RefExpr->getLocation()))
-              S.getCurFunction()->markSafeWeakUse(RefExpr);
-    }
+    if (propType.getObjCLifetime() == Qualifiers::OCL_Weak &&
+        !S.Diags.isIgnored(diag::warn_arc_repeated_use_of_weak,
+                           RefExpr->getLocation()))
+      S.getCurFunction()->markSafeWeakUse(RefExpr);
   }
 
   return result;
@@ -962,11 +961,11 @@ ObjCPropertyOpBuilder::buildIncDecOperation(Scope *Sc, SourceLocation opcLoc,
 }
 
 ExprResult ObjCPropertyOpBuilder::complete(Expr *SyntacticForm) {
-  if (S.getLangOpts().ObjCAutoRefCount && isWeakProperty() &&
+  if (isWeakProperty() &&
       !S.Diags.isIgnored(diag::warn_arc_repeated_use_of_weak,
                          SyntacticForm->getLocStart()))
-      S.recordUseOfEvaluatedWeak(SyntacticRefExpr,
-                                 SyntacticRefExpr->isMessagingGetter());
+    S.recordUseOfEvaluatedWeak(SyntacticRefExpr,
+                               SyntacticRefExpr->isMessagingGetter());
 
   return PseudoOpBuilder::complete(SyntacticForm);
 }
@@ -1127,8 +1126,8 @@ static void CheckKeyForObjCARCConversion(Sema &S, QualType ContainerT,
   if (!Getter)
     return;
   QualType T = Getter->parameters()[0]->getType();
-  S.CheckObjCARCConversion(Key->getSourceRange(), 
-                         T, Key, Sema::CCK_ImplicitConversion);
+  S.CheckObjCConversion(Key->getSourceRange(), T, Key,
+                        Sema::CCK_ImplicitConversion);
 }
 
 bool ObjCSubscriptOpBuilder::findAtIndexGetter() {
@@ -1587,7 +1586,8 @@ ExprResult Sema::checkPseudoObjectAssignment(Scope *S, SourceLocation opcLoc,
   // Do nothing if either argument is dependent.
   if (LHS->isTypeDependent() || RHS->isTypeDependent())
     return new (Context) BinaryOperator(LHS, RHS, opcode, Context.DependentTy,
-                                        VK_RValue, OK_Ordinary, opcLoc, false);
+                                        VK_RValue, OK_Ordinary, opcLoc,
+                                        FPOptions());
 
   // Filter out non-overload placeholder types in the RHS.
   if (RHS->getType()->isNonOverloadPlaceholderType()) {
@@ -1652,14 +1652,15 @@ Expr *Sema::recreateSyntacticForm(PseudoObjectExpr *E) {
                                                 cop->getObjectKind(),
                                                 cop->getComputationLHSType(),
                                                 cop->getComputationResultType(),
-                                                cop->getOperatorLoc(), false);
+                                                cop->getOperatorLoc(),
+                                                FPOptions());
   } else if (BinaryOperator *bop = dyn_cast<BinaryOperator>(syntax)) {
     Expr *lhs = stripOpaqueValuesFromPseudoObjectRef(*this, bop->getLHS());
     Expr *rhs = cast<OpaqueValueExpr>(bop->getRHS())->getSourceExpr();
     return new (Context) BinaryOperator(lhs, rhs, bop->getOpcode(),
                                         bop->getType(), bop->getValueKind(),
                                         bop->getObjectKind(),
-                                        bop->getOperatorLoc(), false);
+                                        bop->getOperatorLoc(), FPOptions());
   } else {
     assert(syntax->hasPlaceholderType(BuiltinType::PseudoObject));
     return stripOpaqueValuesFromPseudoObjectRef(*this, syntax);
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index 390e1b52c8ed..9be1c56f0622 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -290,9 +290,15 @@ void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
       DiagID = diag::warn_unused_property_expr;
   } else if (const CXXFunctionalCastExpr *FC
                                        = dyn_cast<CXXFunctionalCastExpr>(E)) {
-    if (isa<CXXConstructExpr>(FC->getSubExpr()) ||
-        isa<CXXTemporaryObjectExpr>(FC->getSubExpr()))
+    const Expr *E = FC->getSubExpr();
+    if (const CXXBindTemporaryExpr *TE = dyn_cast<CXXBindTemporaryExpr>(E))
+      E = TE->getSubExpr();
+    if (isa<CXXTemporaryObjectExpr>(E))
       return;
+    if (const CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(E))
+      if (const CXXRecordDecl *RD = CE->getType()->getAsCXXRecordDecl())
+        if (!RD->getAttr<WarnUnusedAttr>())
+          return;
   }
   // Diagnose "(void*) blah" as a typo for "(void) blah".
   else if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E)) {
@@ -711,6 +717,9 @@ static bool ShouldDiagnoseSwitchCaseNotInEnum(const Sema &S,
                                               EnumValsTy::iterator &EI,
                                               EnumValsTy::iterator &EIEnd,
                                               const llvm::APSInt &Val) {
+  if (!ED->isClosed())
+    return false;
+
   if (const DeclRefExpr *DRE =
           dyn_cast<DeclRefExpr>(CaseExpr->IgnoreParenImpCasts())) {
     if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
@@ -722,15 +731,14 @@ static bool ShouldDiagnoseSwitchCaseNotInEnum(const Sema &S,
     }
   }
 
-  if (ED->hasAttr<FlagEnumAttr>()) {
+  if (ED->hasAttr<FlagEnumAttr>())
     return !S.IsValueInFlagEnum(ED, Val, false);
-  } else {
-    while (EI != EIEnd && EI->first < Val)
-      EI++;
 
-    if (EI != EIEnd && EI->first == Val)
-      return false;
-  }
+  while (EI != EIEnd && EI->first < Val)
+    EI++;
+
+  if (EI != EIEnd && EI->first == Val)
+    return false;
 
   return true;
 }
@@ -1147,7 +1155,7 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
         }
       }
 
-      if (TheDefaultStmt && UnhandledNames.empty())
+      if (TheDefaultStmt && UnhandledNames.empty() && ED->isClosedNonFlag())
         Diag(TheDefaultStmt->getDefaultLoc(), diag::warn_unreachable_default);
 
       // Produce a nice diagnostic if multiple values aren't handled.
@@ -1198,6 +1206,9 @@ Sema::DiagnoseAssignmentEnum(QualType DstType, QualType SrcType,
         AdjustAPSInt(RhsVal, DstWidth, DstIsSigned);
         const EnumDecl *ED = ET->getDecl();
 
+        if (!ED->isClosed())
+          return;
+
         if (ED->hasAttr<FlagEnumAttr>()) {
           if (!IsValueInFlagEnum(ED, RhsVal, true))
             Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment)
@@ -1810,7 +1821,7 @@ Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
 
         D->setType(FirstType);
 
-        if (ActiveTemplateInstantiations.empty()) {
+        if (!inTemplateInstantiation()) {
           SourceLocation Loc =
               D->getTypeSourceInfo()->getTypeLoc().getBeginLoc();
           Diag(Loc, diag::warn_auto_var_is_id)
@@ -2866,7 +2877,8 @@ Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
   bool HasDeducedReturnType =
       CurLambda && hasDeducedReturnType(CurLambda->CallOperator);
 
-  if (ExprEvalContexts.back().Context == DiscardedStatement &&
+  if (ExprEvalContexts.back().Context ==
+          ExpressionEvaluationContext::DiscardedStatement &&
       (HasDeducedReturnType || CurCap->HasImplicitReturnType)) {
     if (RetValExp) {
       ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
@@ -3158,7 +3170,8 @@ StmtResult
 Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
                       Scope *CurScope) {
   StmtResult R = BuildReturnStmt(ReturnLoc, RetValExp);
-  if (R.isInvalid() || ExprEvalContexts.back().Context == DiscardedStatement)
+  if (R.isInvalid() || ExprEvalContexts.back().Context ==
+                           ExpressionEvaluationContext::DiscardedStatement)
     return R;
 
   if (VarDecl *VD =
@@ -3214,7 +3227,8 @@ StmtResult Sema::BuildReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
 
   // C++1z: discarded return statements are not considered when deducing a
   // return type.
-  if (ExprEvalContexts.back().Context == DiscardedStatement &&
+  if (ExprEvalContexts.back().Context ==
+          ExpressionEvaluationContext::DiscardedStatement &&
       FnRetType->getContainedAutoType()) {
     if (RetValExp) {
       ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc);
@@ -3914,7 +3928,8 @@ void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
   else
     CurContext = CD;
 
-  PushExpressionEvaluationContext(PotentiallyEvaluated);
+  PushExpressionEvaluationContext(
+      ExpressionEvaluationContext::PotentiallyEvaluated);
 }
 
 void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
@@ -3966,7 +3981,8 @@ void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
   else
     CurContext = CD;
 
-  PushExpressionEvaluationContext(PotentiallyEvaluated);
+  PushExpressionEvaluationContext(
+      ExpressionEvaluationContext::PotentiallyEvaluated);
 }
 
 void Sema::ActOnCapturedRegionError() {
diff --git a/lib/Sema/SemaStmtAsm.cpp b/lib/Sema/SemaStmtAsm.cpp
index 76de9e299399..5f91cac14a38 100644
--- a/lib/Sema/SemaStmtAsm.cpp
+++ b/lib/Sema/SemaStmtAsm.cpp
@@ -623,8 +623,9 @@ ExprResult Sema::LookupInlineAsmIdentifier(CXXScopeSpec &SS,
   Info.clear();
 
   if (IsUnevaluatedContext)
-    PushExpressionEvaluationContext(UnevaluatedAbstract,
-                                    ReuseLambdaContextDecl);
+    PushExpressionEvaluationContext(
+        ExpressionEvaluationContext::UnevaluatedAbstract,
+        ReuseLambdaContextDecl);
 
   ExprResult Result = ActOnIdExpression(getCurScope(), SS, TemplateKWLoc, Id,
                                         /*trailing lparen*/ false,
diff --git a/lib/Sema/SemaStmtAttr.cpp b/lib/Sema/SemaStmtAttr.cpp
index 01fa856132d7..4ee3412170a8 100644
--- a/lib/Sema/SemaStmtAttr.cpp
+++ b/lib/Sema/SemaStmtAttr.cpp
@@ -53,6 +53,31 @@ static Attr *handleFallThroughAttr(Sema &S, Stmt *St, const AttributeList &A,
   return ::new (S.Context) auto(Attr);
 }
 
+static Attr *handleSuppressAttr(Sema &S, Stmt *St, const AttributeList &A,
+                                SourceRange Range) {
+  if (A.getNumArgs() < 1) {
+    S.Diag(A.getLoc(), diag::err_attribute_too_few_arguments)
+        << A.getName() << 1;
+    return nullptr;
+  }
+
+  std::vector<StringRef> DiagnosticIdentifiers;
+  for (unsigned I = 0, E = A.getNumArgs(); I != E; ++I) {
+    StringRef RuleName;
+
+    if (!S.checkStringLiteralArgumentAttr(A, I, RuleName, nullptr))
+      return nullptr;
+
+    // FIXME: Warn if the rule name is unknown. This is tricky because only
+    // clang-tidy knows about available rules.
+    DiagnosticIdentifiers.push_back(RuleName);
+  }
+
+  return ::new (S.Context) SuppressAttr(
+      A.getRange(), S.Context, DiagnosticIdentifiers.data(),
+      DiagnosticIdentifiers.size(), A.getAttributeSpellingListIndex());
+}
+
 static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const AttributeList &A,
                                 SourceRange) {
   IdentifierLoc *PragmaNameLoc = A.getArgAsIdent(0);
@@ -279,6 +304,8 @@ static Attr *ProcessStmtAttribute(Sema &S, Stmt *St, const AttributeList &A,
     return handleLoopHintAttr(S, St, A, Range);
   case AttributeList::AT_OpenCLUnrollHint:
     return handleOpenCLUnrollHint(S, St, A, Range);
+  case AttributeList::AT_Suppress:
+    return handleSuppressAttr(S, St, A, Range);
   default:
     // if we're here, then we parsed a known attribute, but didn't recognize
     // it as a statement attribute => it is declaration attribute
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index ad1e89a0ca64..f522e76b0673 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -45,6 +45,26 @@ clang::getTemplateParamsRange(TemplateParameterList const * const *Ps,
   return SourceRange(Ps[0]->getTemplateLoc(), Ps[N-1]->getRAngleLoc());
 }
 
+namespace clang {
+/// \brief [temp.constr.decl]p2: A template's associated constraints are
+/// defined as a single constraint-expression derived from the introduced
+/// constraint-expressions [ ... ].
+///
+/// \param Params The template parameter list and optional requires-clause.
+///
+/// \param FD The underlying templated function declaration for a function
+/// template.
+static Expr *formAssociatedConstraints(TemplateParameterList *Params,
+                                       FunctionDecl *FD);
+}
+
+static Expr *clang::formAssociatedConstraints(TemplateParameterList *Params,
+                                              FunctionDecl *FD) {
+  // FIXME: Concepts: collect additional introduced constraint-expressions
+  assert(!FD && "Cannot collect constraints from function declaration yet.");
+  return Params->getRequiresClause();
+}
+
 /// \brief Determine whether the declaration found is acceptable as the name
 /// of a template and, if so, return that template declaration. Otherwise,
 /// returns NULL.
@@ -222,6 +242,37 @@ TemplateNameKind Sema::isTemplateName(Scope *S,
   return TemplateKind;
 }
 
+bool Sema::isDeductionGuideName(Scope *S, const IdentifierInfo &Name,
+                                SourceLocation NameLoc,
+                                ParsedTemplateTy *Template) {
+  CXXScopeSpec SS;
+  bool MemberOfUnknownSpecialization = false;
+
+  // We could use redeclaration lookup here, but we don't need to: the
+  // syntactic form of a deduction guide is enough to identify it even
+  // if we can't look up the template name at all.
+  LookupResult R(*this, DeclarationName(&Name), NameLoc, LookupOrdinaryName);
+  LookupTemplateName(R, S, SS, /*ObjectType*/QualType(),
+                     /*EnteringContext*/false, MemberOfUnknownSpecialization);
+
+  if (R.empty()) return false;
+  if (R.isAmbiguous()) {
+    // FIXME: Diagnose an ambiguity if we find at least one template.
+    R.suppressDiagnostics();
+    return false;
+  }
+
+  // We only treat template-names that name type templates as valid deduction
+  // guide names.
+  TemplateDecl *TD = R.getAsSingle<TemplateDecl>();
+  if (!TD || !getAsTypeTemplateDecl(TD))
+    return false;
+
+  if (Template)
+    *Template = TemplateTy::make(TemplateName(TD));
+  return true;
+}
+
 bool Sema::DiagnoseUnknownTemplateName(const IdentifierInfo &II,
                                        SourceLocation IILoc,
                                        Scope *S,
@@ -1137,6 +1188,9 @@ Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
     }
   }
 
+  // TODO Memory management; associated constraints are not always stored.
+  Expr *const CurAC = formAssociatedConstraints(TemplateParams, nullptr);
+
   if (PrevClassTemplate) {
     // Ensure that the template parameter lists are compatible. Skip this check
     // for a friend in a dependent context: the template parameter list itself
@@ -1148,6 +1202,29 @@ Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
                                         TPL_TemplateMatch))
       return true;
 
+    // Check for matching associated constraints on redeclarations.
+    const Expr *const PrevAC = PrevClassTemplate->getAssociatedConstraints();
+    const bool RedeclACMismatch = [&] {
+      if (!(CurAC || PrevAC))
+        return false; // Nothing to check; no mismatch.
+      if (CurAC && PrevAC) {
+        llvm::FoldingSetNodeID CurACInfo, PrevACInfo;
+        CurAC->Profile(CurACInfo, Context, /*Canonical=*/true);
+        PrevAC->Profile(PrevACInfo, Context, /*Canonical=*/true);
+        if (CurACInfo == PrevACInfo)
+          return false; // All good; no mismatch.
+      }
+      return true;
+    }();
+
+    if (RedeclACMismatch) {
+      Diag(CurAC ? CurAC->getLocStart() : NameLoc,
+           diag::err_template_different_associated_constraints);
+      Diag(PrevAC ? PrevAC->getLocStart() : PrevClassTemplate->getLocation(),
+           diag::note_template_prev_declaration) << /*declaration*/0;
+      return true;
+    }
+
     // C++ [temp.class]p4:
     //   In a redeclaration, partial specialization, explicit
     //   specialization or explicit instantiation of a class template,
@@ -1250,10 +1327,15 @@ Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
     AddMsStructLayoutForRecord(NewClass);
   }
 
+  // Attach the associated constraints when the declaration will not be part of
+  // a decl chain.
+  Expr *const ACtoAttach =
+      PrevClassTemplate && ShouldAddRedecl ? nullptr : CurAC;
+
   ClassTemplateDecl *NewTemplate
     = ClassTemplateDecl::Create(Context, SemanticContext, NameLoc,
                                 DeclarationName(Name), TemplateParams,
-                                NewClass);
+                                NewClass, ACtoAttach);
 
   if (ShouldAddRedecl)
     NewTemplate->setPreviousDecl(PrevClassTemplate);
@@ -1333,6 +1415,368 @@ Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
   return NewTemplate;
 }
 
+namespace {
+/// Transform to convert portions of a constructor declaration into the
+/// corresponding deduction guide, per C++1z [over.match.class.deduct]p1.
+struct ConvertConstructorToDeductionGuideTransform {
+  ConvertConstructorToDeductionGuideTransform(Sema &S,
+                                              ClassTemplateDecl *Template)
+      : SemaRef(S), Template(Template) {}
+
+  Sema &SemaRef;
+  ClassTemplateDecl *Template;
+
+  DeclContext *DC = Template->getDeclContext();
+  CXXRecordDecl *Primary = Template->getTemplatedDecl();
+  DeclarationName DeductionGuideName =
+      SemaRef.Context.DeclarationNames.getCXXDeductionGuideName(Template);
+
+  QualType DeducedType = SemaRef.Context.getTypeDeclType(Primary);
+
+  // Index adjustment to apply to convert depth-1 template parameters into
+  // depth-0 template parameters.
+  unsigned Depth1IndexAdjustment = Template->getTemplateParameters()->size();
+
+  /// Transform a constructor declaration into a deduction guide.
+  NamedDecl *transformConstructor(FunctionTemplateDecl *FTD,
+                                  CXXConstructorDecl *CD) {
+    SmallVector<TemplateArgument, 16> SubstArgs;
+
+    LocalInstantiationScope Scope(SemaRef);
+
+    // C++ [over.match.class.deduct]p1:
+    // -- For each constructor of the class template designated by the
+    //    template-name, a function template with the following properties:
+
+    //    -- The template parameters are the template parameters of the class
+    //       template followed by the template parameters (including default
+    //       template arguments) of the constructor, if any.
+    TemplateParameterList *TemplateParams = Template->getTemplateParameters();
+    if (FTD) {
+      TemplateParameterList *InnerParams = FTD->getTemplateParameters();
+      SmallVector<NamedDecl *, 16> AllParams;
+      AllParams.reserve(TemplateParams->size() + InnerParams->size());
+      AllParams.insert(AllParams.begin(),
+                       TemplateParams->begin(), TemplateParams->end());
+      SubstArgs.reserve(InnerParams->size());
+
+      // Later template parameters could refer to earlier ones, so build up
+      // a list of substituted template arguments as we go.
+      for (NamedDecl *Param : *InnerParams) {
+        MultiLevelTemplateArgumentList Args;
+        Args.addOuterTemplateArguments(SubstArgs);
+        Args.addOuterRetainedLevel();
+        NamedDecl *NewParam = transformTemplateParameter(Param, Args);
+        if (!NewParam)
+          return nullptr;
+        AllParams.push_back(NewParam);
+        SubstArgs.push_back(SemaRef.Context.getCanonicalTemplateArgument(
+            SemaRef.Context.getInjectedTemplateArg(NewParam)));
+      }
+      TemplateParams = TemplateParameterList::Create(
+          SemaRef.Context, InnerParams->getTemplateLoc(),
+          InnerParams->getLAngleLoc(), AllParams, InnerParams->getRAngleLoc(),
+          /*FIXME: RequiresClause*/ nullptr);
+    }
+
+    // If we built a new template-parameter-list, track that we need to
+    // substitute references to the old parameters into references to the
+    // new ones.
+    MultiLevelTemplateArgumentList Args;
+    if (FTD) {
+      Args.addOuterTemplateArguments(SubstArgs);
+      Args.addOuterRetainedLevel();
+    }
+
+    FunctionProtoTypeLoc FPTL = CD->getTypeSourceInfo()->getTypeLoc()
+                                   .getAsAdjusted<FunctionProtoTypeLoc>();
+    assert(FPTL && "no prototype for constructor declaration");
+
+    // Transform the type of the function, adjusting the return type and
+    // replacing references to the old parameters with references to the
+    // new ones.
+    TypeLocBuilder TLB;
+    SmallVector<ParmVarDecl*, 8> Params;
+    QualType NewType = transformFunctionProtoType(TLB, FPTL, Params, Args);
+    if (NewType.isNull())
+      return nullptr;
+    TypeSourceInfo *NewTInfo = TLB.getTypeSourceInfo(SemaRef.Context, NewType);
+
+    return buildDeductionGuide(TemplateParams, CD->isExplicit(), NewTInfo,
+                               CD->getLocStart(), CD->getLocation(),
+                               CD->getLocEnd());
+  }
+
+  /// Build a deduction guide with the specified parameter types.
+  NamedDecl *buildSimpleDeductionGuide(MutableArrayRef<QualType> ParamTypes) {
+    SourceLocation Loc = Template->getLocation();
+
+    // Build the requested type.
+    FunctionProtoType::ExtProtoInfo EPI;
+    EPI.HasTrailingReturn = true;
+    QualType Result = SemaRef.BuildFunctionType(DeducedType, ParamTypes, Loc,
+                                                DeductionGuideName, EPI);
+    TypeSourceInfo *TSI = SemaRef.Context.getTrivialTypeSourceInfo(Result, Loc);
+
+    FunctionProtoTypeLoc FPTL =
+        TSI->getTypeLoc().castAs<FunctionProtoTypeLoc>();
+
+    // Build the parameters, needed during deduction / substitution.
+    SmallVector<ParmVarDecl*, 4> Params;
+    for (auto T : ParamTypes) {
+      ParmVarDecl *NewParam = ParmVarDecl::Create(
+          SemaRef.Context, DC, Loc, Loc, nullptr, T,
+          SemaRef.Context.getTrivialTypeSourceInfo(T, Loc), SC_None, nullptr);
+      NewParam->setScopeInfo(0, Params.size());
+      FPTL.setParam(Params.size(), NewParam);
+      Params.push_back(NewParam);
+    }
+
+    return buildDeductionGuide(Template->getTemplateParameters(), false, TSI,
+                               Loc, Loc, Loc);
+  }
+
+private:
+  /// Transform a constructor template parameter into a deduction guide template
+  /// parameter, rebuilding any internal references to earlier parameters and
+  /// renumbering as we go.
+  NamedDecl *transformTemplateParameter(NamedDecl *TemplateParam,
+                                        MultiLevelTemplateArgumentList &Args) {
+    if (auto *TTP = dyn_cast<TemplateTypeParmDecl>(TemplateParam)) {
+      // TemplateTypeParmDecl's index cannot be changed after creation, so
+      // substitute it directly.
+      auto *NewTTP = TemplateTypeParmDecl::Create(
+          SemaRef.Context, DC, TTP->getLocStart(), TTP->getLocation(),
+          /*Depth*/0, Depth1IndexAdjustment + TTP->getIndex(),
+          TTP->getIdentifier(), TTP->wasDeclaredWithTypename(),
+          TTP->isParameterPack());
+      if (TTP->hasDefaultArgument()) {
+        TypeSourceInfo *InstantiatedDefaultArg =
+            SemaRef.SubstType(TTP->getDefaultArgumentInfo(), Args,
+                              TTP->getDefaultArgumentLoc(), TTP->getDeclName());
+        if (InstantiatedDefaultArg)
+          NewTTP->setDefaultArgument(InstantiatedDefaultArg);
+      }
+      SemaRef.CurrentInstantiationScope->InstantiatedLocal(TemplateParam,
+                                                           NewTTP);
+      return NewTTP;
+    }
+
+    if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(TemplateParam))
+      return transformTemplateParameterImpl(TTP, Args);
+
+    return transformTemplateParameterImpl(
+        cast<NonTypeTemplateParmDecl>(TemplateParam), Args);
+  }
+  template<typename TemplateParmDecl>
+  TemplateParmDecl *
+  transformTemplateParameterImpl(TemplateParmDecl *OldParam,
+                                 MultiLevelTemplateArgumentList &Args) {
+    // Ask the template instantiator to do the heavy lifting for us, then adjust
+    // the index of the parameter once it's done.
+    auto *NewParam =
+        cast_or_null<TemplateParmDecl>(SemaRef.SubstDecl(OldParam, DC, Args));
+    assert(NewParam->getDepth() == 0 && "unexpected template param depth");
+    NewParam->setPosition(NewParam->getPosition() + Depth1IndexAdjustment);
+    return NewParam;
+  }
+
+  QualType transformFunctionProtoType(TypeLocBuilder &TLB,
+                                      FunctionProtoTypeLoc TL,
+                                      SmallVectorImpl<ParmVarDecl*> &Params,
+                                      MultiLevelTemplateArgumentList &Args) {
+    SmallVector<QualType, 4> ParamTypes;
+    const FunctionProtoType *T = TL.getTypePtr();
+
+    //    -- The types of the function parameters are those of the constructor.
+    for (auto *OldParam : TL.getParams()) {
+      ParmVarDecl *NewParam = transformFunctionTypeParam(OldParam, Args);
+      if (!NewParam)
+        return QualType();
+      ParamTypes.push_back(NewParam->getType());
+      Params.push_back(NewParam);
+    }
+
+    //    -- The return type is the class template specialization designated by
+    //       the template-name and template arguments corresponding to the
+    //       template parameters obtained from the class template.
+    //
+    // We use the injected-class-name type of the primary template instead.
+    // This has the convenient property that it is different from any type that
+    // the user can write in a deduction-guide (because they cannot enter the
+    // context of the template), so implicit deduction guides can never collide
+    // with explicit ones.
+    QualType ReturnType = DeducedType;
+    TLB.pushTypeSpec(ReturnType).setNameLoc(Primary->getLocation());
+
+    // Resolving a wording defect, we also inherit the variadicness of the
+    // constructor.
+    FunctionProtoType::ExtProtoInfo EPI;
+    EPI.Variadic = T->isVariadic();
+    EPI.HasTrailingReturn = true;
+
+    QualType Result = SemaRef.BuildFunctionType(
+        ReturnType, ParamTypes, TL.getLocStart(), DeductionGuideName, EPI);
+    if (Result.isNull())
+      return QualType();
+
+    FunctionProtoTypeLoc NewTL = TLB.push<FunctionProtoTypeLoc>(Result);
+    NewTL.setLocalRangeBegin(TL.getLocalRangeBegin());
+    NewTL.setLParenLoc(TL.getLParenLoc());
+    NewTL.setRParenLoc(TL.getRParenLoc());
+    NewTL.setExceptionSpecRange(SourceRange());
+    NewTL.setLocalRangeEnd(TL.getLocalRangeEnd());
+    for (unsigned I = 0, E = NewTL.getNumParams(); I != E; ++I)
+      NewTL.setParam(I, Params[I]);
+
+    return Result;
+  }
+
+  ParmVarDecl *
+  transformFunctionTypeParam(ParmVarDecl *OldParam,
+                             MultiLevelTemplateArgumentList &Args) {
+    TypeSourceInfo *OldDI = OldParam->getTypeSourceInfo();
+    TypeSourceInfo *NewDI =
+        Args.getNumLevels()
+            ? SemaRef.SubstType(OldDI, Args, OldParam->getLocation(),
+                                OldParam->getDeclName())
+            : OldDI;
+    if (!NewDI)
+      return nullptr;
+
+    // Canonicalize the type. This (for instance) replaces references to
+    // typedef members of the current instantiations with the definitions of
+    // those typedefs, avoiding triggering instantiation of the deduced type
+    // during deduction.
+    // FIXME: It would be preferable to retain type sugar and source
+    // information here (and handle this in substitution instead).
+    NewDI = SemaRef.Context.getTrivialTypeSourceInfo(
+        SemaRef.Context.getCanonicalType(NewDI->getType()),
+        OldParam->getLocation());
+
+    // Resolving a wording defect, we also inherit default arguments from the
+    // constructor.
+    ExprResult NewDefArg;
+    if (OldParam->hasDefaultArg()) {
+      NewDefArg = Args.getNumLevels()
+                      ? SemaRef.SubstExpr(OldParam->getDefaultArg(), Args)
+                      : OldParam->getDefaultArg();
+      if (NewDefArg.isInvalid())
+        return nullptr;
+    }
+
+    ParmVarDecl *NewParam = ParmVarDecl::Create(SemaRef.Context, DC,
+                                                OldParam->getInnerLocStart(),
+                                                OldParam->getLocation(),
+                                                OldParam->getIdentifier(),
+                                                NewDI->getType(),
+                                                NewDI,
+                                                OldParam->getStorageClass(),
+                                                NewDefArg.get());
+    NewParam->setScopeInfo(OldParam->getFunctionScopeDepth(),
+                           OldParam->getFunctionScopeIndex());
+    return NewParam;
+  }
+
+  NamedDecl *buildDeductionGuide(TemplateParameterList *TemplateParams,
+                                 bool Explicit, TypeSourceInfo *TInfo,
+                                 SourceLocation LocStart, SourceLocation Loc,
+                                 SourceLocation LocEnd) {
+    DeclarationNameInfo Name(DeductionGuideName, Loc);
+    ArrayRef<ParmVarDecl *> Params =
+        TInfo->getTypeLoc().castAs<FunctionProtoTypeLoc>().getParams();
+
+    // Build the implicit deduction guide template.
+    auto *Guide =
+        CXXDeductionGuideDecl::Create(SemaRef.Context, DC, LocStart, Explicit,
+                                      Name, TInfo->getType(), TInfo, LocEnd);
+    Guide->setImplicit();
+    Guide->setParams(Params);
+
+    for (auto *Param : Params)
+      Param->setDeclContext(Guide);
+
+    auto *GuideTemplate = FunctionTemplateDecl::Create(
+        SemaRef.Context, DC, Loc, DeductionGuideName, TemplateParams, Guide);
+    GuideTemplate->setImplicit();
+    Guide->setDescribedFunctionTemplate(GuideTemplate);
+
+    if (isa<CXXRecordDecl>(DC)) {
+      Guide->setAccess(AS_public);
+      GuideTemplate->setAccess(AS_public);
+    }
+
+    DC->addDecl(GuideTemplate);
+    return GuideTemplate;
+  }
+};
+}
+
+void Sema::DeclareImplicitDeductionGuides(TemplateDecl *Template,
+                                          SourceLocation Loc) {
+  DeclContext *DC = Template->getDeclContext();
+  if (DC->isDependentContext())
+    return;
+
+  ConvertConstructorToDeductionGuideTransform Transform(
+      *this, cast<ClassTemplateDecl>(Template));
+  if (!isCompleteType(Loc, Transform.DeducedType))
+    return;
+
+  // Check whether we've already declared deduction guides for this template.
+  // FIXME: Consider storing a flag on the template to indicate this.
+  auto Existing = DC->lookup(Transform.DeductionGuideName);
+  for (auto *D : Existing)
+    if (D->isImplicit())
+      return;
+
+  // In case we were expanding a pack when we attempted to declare deduction
+  // guides, turn off pack expansion for everything we're about to do.
+  ArgumentPackSubstitutionIndexRAII SubstIndex(*this, -1);
+  // Create a template instantiation record to track the "instantiation" of
+  // constructors into deduction guides.
+  // FIXME: Add a kind for this to give more meaningful diagnostics. But can
+  // this substitution process actually fail?
+  InstantiatingTemplate BuildingDeductionGuides(*this, Loc, Template);
+
+  // Convert declared constructors into deduction guide templates.
+  // FIXME: Skip constructors for which deduction must necessarily fail (those
+  // for which some class template parameter without a default argument never
+  // appears in a deduced context).
+  bool AddedAny = false;
+  bool AddedCopyOrMove = false;
+  for (NamedDecl *D : LookupConstructors(Transform.Primary)) {
+    D = D->getUnderlyingDecl();
+    if (D->isInvalidDecl() || D->isImplicit())
+      continue;
+    D = cast<NamedDecl>(D->getCanonicalDecl());
+
+    auto *FTD = dyn_cast<FunctionTemplateDecl>(D);
+    auto *CD =
+        dyn_cast_or_null<CXXConstructorDecl>(FTD ? FTD->getTemplatedDecl() : D);
+    // Class-scope explicit specializations (MS extension) do not result in
+    // deduction guides.
+    if (!CD || (!FTD && CD->isFunctionTemplateSpecialization()))
+      continue;
+
+    Transform.transformConstructor(FTD, CD);
+    AddedAny = true;
+
+    AddedCopyOrMove |= CD->isCopyOrMoveConstructor();
+  }
+
+  // Synthesize an X() -> X<...> guide if there were no declared constructors.
+  // FIXME: The standard doesn't say (how) to do this.
+  if (!AddedAny)
+    Transform.buildSimpleDeductionGuide(None);
+
+  // Synthesize an X(X<...>) -> X<...> guide if there was no declared constructor
+  // resembling a copy or move constructor.
+  // FIXME: The standard doesn't say (how) to do this.
+  if (!AddedCopyOrMove)
+    Transform.buildSimpleDeductionGuide(Transform.DeducedType);
+}
+
 /// \brief Diagnose the presence of a default template argument on a
 /// template parameter, which is ill-formed in certain contexts.
 ///
@@ -1665,7 +2109,6 @@ struct DependencyChecker : RecursiveASTVisitor<DependencyChecker> {
   typedef RecursiveASTVisitor<DependencyChecker> super;
 
   unsigned Depth;
-  bool FindLessThanDepth;
 
   // Whether we're looking for a use of a template parameter that makes the
   // overall construct type-dependent / a dependent type. This is strictly
@@ -1676,16 +2119,25 @@ struct DependencyChecker : RecursiveASTVisitor<DependencyChecker> {
   bool Match;
   SourceLocation MatchLoc;
 
-  DependencyChecker(unsigned Depth, bool IgnoreNonTypeDependent,
-                    bool FindLessThanDepth = false)
-      : Depth(Depth), FindLessThanDepth(FindLessThanDepth),
-        IgnoreNonTypeDependent(IgnoreNonTypeDependent), Match(false) {}
+  DependencyChecker(unsigned Depth, bool IgnoreNonTypeDependent)
+      : Depth(Depth), IgnoreNonTypeDependent(IgnoreNonTypeDependent),
+        Match(false) {}
 
   DependencyChecker(TemplateParameterList *Params, bool IgnoreNonTypeDependent)
-      : DependencyChecker(Params->getDepth(), IgnoreNonTypeDependent) {}
+      : IgnoreNonTypeDependent(IgnoreNonTypeDependent), Match(false) {
+    NamedDecl *ND = Params->getParam(0);
+    if (TemplateTypeParmDecl *PD = dyn_cast<TemplateTypeParmDecl>(ND)) {
+      Depth = PD->getDepth();
+    } else if (NonTypeTemplateParmDecl *PD =
+                 dyn_cast<NonTypeTemplateParmDecl>(ND)) {
+      Depth = PD->getDepth();
+    } else {
+      Depth = cast<TemplateTemplateParmDecl>(ND)->getDepth();
+    }
+  }
 
   bool Matches(unsigned ParmDepth, SourceLocation Loc = SourceLocation()) {
-    if (FindLessThanDepth ^ (ParmDepth >= Depth)) {
+    if (ParmDepth >= Depth) {
       Match = true;
       MatchLoc = Loc;
       return true;
@@ -1802,8 +2254,9 @@ static SourceRange getRangeOfTypeInNestedNameSpecifier(ASTContext &Context,
 /// matching template parameters to scope specifiers in friend
 /// declarations.
 ///
-/// \param IsExplicitSpecialization will be set true if the entity being
-/// declared is an explicit specialization, false otherwise.
+/// \param IsMemberSpecialization will be set true if the scope specifier
+/// denotes a fully-specialized type, and therefore this is a declaration of
+/// a member specialization.
 ///
 /// \returns the template parameter list, if any, that corresponds to the
 /// name that is preceded by the scope specifier @p SS. This template
@@ -1815,8 +2268,8 @@ TemplateParameterList *Sema::MatchTemplateParametersToScopeSpecifier(
     SourceLocation DeclStartLoc, SourceLocation DeclLoc, const CXXScopeSpec &SS,
     TemplateIdAnnotation *TemplateId,
     ArrayRef<TemplateParameterList *> ParamLists, bool IsFriend,
-    bool &IsExplicitSpecialization, bool &Invalid) {
-  IsExplicitSpecialization = false;
+    bool &IsMemberSpecialization, bool &Invalid) {
+  IsMemberSpecialization = false;
   Invalid = false;
 
   // The sequence of nested types to which we will match up the template
@@ -1926,7 +2379,7 @@ TemplateParameterList *Sema::MatchTemplateParametersToScopeSpecifier(
       Diag(DeclLoc, diag::err_specialize_member_of_template)
         << !Recovery << Range;
       Invalid = true;
-      IsExplicitSpecialization = false;
+      IsMemberSpecialization = false;
       return true;
     }
 
@@ -1996,7 +2449,7 @@ TemplateParameterList *Sema::MatchTemplateParametersToScopeSpecifier(
         if (Record->getTemplateSpecializationKind()
                                                 != TSK_ExplicitSpecialization &&
             TypeIdx == NumTypes - 1)
-          IsExplicitSpecialization = true;
+          IsMemberSpecialization = true;
 
         continue;
       }
@@ -2030,9 +2483,9 @@ TemplateParameterList *Sema::MatchTemplateParametersToScopeSpecifier(
 
     if (NeedEmptyTemplateHeader) {
       // If we're on the last of the types, and we need a 'template<>' header
-      // here, then it's an explicit specialization.
+      // here, then it's a member specialization.
       if (TypeIdx == NumTypes - 1)
-        IsExplicitSpecialization = true;
+        IsMemberSpecialization = true;
 
       if (ParamIdx < ParamLists.size()) {
         if (ParamLists[ParamIdx]->size() > 0) {
@@ -2105,7 +2558,6 @@ TemplateParameterList *Sema::MatchTemplateParametersToScopeSpecifier(
     if (TemplateId && !IsFriend) {
       // We don't have a template header for the declaration itself, but we
       // should.
-      IsExplicitSpecialization = true;
       DiagnoseMissingExplicitSpecialization(SourceRange(TemplateId->LAngleLoc,
                                                         TemplateId->RAngleLoc));
 
@@ -2402,6 +2854,13 @@ QualType Sema::CheckTemplateIdType(TemplateName Name,
         Decl->setLexicalDeclContext(ClassTemplate->getLexicalDeclContext());
     }
 
+    if (Decl->getSpecializationKind() == TSK_Undeclared) {
+      MultiLevelTemplateArgumentList TemplateArgLists;
+      TemplateArgLists.addOuterTemplateArguments(Converted);
+      InstantiateAttrsForDecl(TemplateArgLists, ClassTemplate->getTemplatedDecl(),
+                              Decl);
+    }
+
     // Diagnose uses of this specialization.
     (void)DiagnoseUseOfDecl(Decl, TemplateLoc);
 
@@ -2421,14 +2880,51 @@ QualType Sema::CheckTemplateIdType(TemplateName Name,
 
 TypeResult
 Sema::ActOnTemplateIdType(CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
-                          TemplateTy TemplateD, SourceLocation TemplateLoc,
+                          TemplateTy TemplateD, IdentifierInfo *TemplateII,
+                          SourceLocation TemplateIILoc,
                           SourceLocation LAngleLoc,
                           ASTTemplateArgsPtr TemplateArgsIn,
                           SourceLocation RAngleLoc,
-                          bool IsCtorOrDtorName) {
+                          bool IsCtorOrDtorName, bool IsClassName) {
   if (SS.isInvalid())
     return true;
 
+  if (!IsCtorOrDtorName && !IsClassName && SS.isSet()) {
+    DeclContext *LookupCtx = computeDeclContext(SS, /*EnteringContext*/false);
+
+    // C++ [temp.res]p3:
+    //   A qualified-id that refers to a type and in which the
+    //   nested-name-specifier depends on a template-parameter (14.6.2)
+    //   shall be prefixed by the keyword typename to indicate that the
+    //   qualified-id denotes a type, forming an
+    //   elaborated-type-specifier (7.1.5.3).
+    if (!LookupCtx && isDependentScopeSpecifier(SS)) {
+      Diag(SS.getBeginLoc(), diag::err_typename_missing_template)
+        << SS.getScopeRep() << TemplateII->getName();
+      // Recover as if 'typename' were specified.
+      // FIXME: This is not quite correct recovery as we don't transform SS
+      // into the corresponding dependent form (and we don't diagnose missing
+      // 'template' keywords within SS as a result).
+      return ActOnTypenameType(nullptr, SourceLocation(), SS, TemplateKWLoc,
+                               TemplateD, TemplateII, TemplateIILoc, LAngleLoc,
+                               TemplateArgsIn, RAngleLoc);
+    }
+
+    // Per C++ [class.qual]p2, if the template-id was an injected-class-name,
+    // it's not actually allowed to be used as a type in most cases. Because
+    // we annotate it before we know whether it's valid, we have to check for
+    // this case here.
+    auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
+    if (LookupRD && LookupRD->getIdentifier() == TemplateII) {
+      Diag(TemplateIILoc,
+           TemplateKWLoc.isInvalid()
+               ? diag::err_out_of_line_qualified_id_type_names_constructor
+               : diag::ext_out_of_line_qualified_id_type_names_constructor)
+        << TemplateII << 0 /*injected-class-name used as template name*/
+        << 1 /*if any keyword was present, it was 'template'*/;
+    }
+  }
+
   TemplateName Template = TemplateD.get();
 
   // Translate the parser's template argument list in our AST format.
@@ -2448,7 +2944,7 @@ Sema::ActOnTemplateIdType(CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
     SpecTL.setElaboratedKeywordLoc(SourceLocation());
     SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
     SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
-    SpecTL.setTemplateNameLoc(TemplateLoc);
+    SpecTL.setTemplateNameLoc(TemplateIILoc);
     SpecTL.setLAngleLoc(LAngleLoc);
     SpecTL.setRAngleLoc(RAngleLoc);
     for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
@@ -2456,8 +2952,7 @@ Sema::ActOnTemplateIdType(CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
     return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
   }
 
-  QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
-
+  QualType Result = CheckTemplateIdType(Template, TemplateIILoc, TemplateArgs);
   if (Result.isNull())
     return true;
 
@@ -2466,7 +2961,7 @@ Sema::ActOnTemplateIdType(CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
   TemplateSpecializationTypeLoc SpecTL
     = TLB.push<TemplateSpecializationTypeLoc>(Result);
   SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
-  SpecTL.setTemplateNameLoc(TemplateLoc);
+  SpecTL.setTemplateNameLoc(TemplateIILoc);
   SpecTL.setLAngleLoc(LAngleLoc);
   SpecTL.setRAngleLoc(RAngleLoc);
   for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
@@ -2690,6 +3185,23 @@ static void checkMoreSpecializedThanPrimary(Sema &S, PartialSpecDecl *Partial) {
   S.Diag(Template->getLocation(), diag::note_template_decl_here);
 }
 
+static void
+noteNonDeducibleParameters(Sema &S, TemplateParameterList *TemplateParams,
+                           const llvm::SmallBitVector &DeducibleParams) {
+  for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
+    if (!DeducibleParams[I]) {
+      NamedDecl *Param = cast<NamedDecl>(TemplateParams->getParam(I));
+      if (Param->getDeclName())
+        S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
+            << Param->getDeclName();
+      else
+        S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
+            << "(anonymous)";
+    }
+  }
+}
+
+
 template<typename PartialSpecDecl>
 static void checkTemplatePartialSpecialization(Sema &S,
                                                PartialSpecDecl *Partial) {
@@ -2717,19 +3229,7 @@ static void checkTemplatePartialSpecialization(Sema &S,
       << (NumNonDeducible > 1)
       << SourceRange(Partial->getLocation(),
                      Partial->getTemplateArgsAsWritten()->RAngleLoc);
-    for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
-      if (!DeducibleParams[I]) {
-        NamedDecl *Param = cast<NamedDecl>(TemplateParams->getParam(I));
-        if (Param->getDeclName())
-          S.Diag(Param->getLocation(),
-                 diag::note_partial_spec_unused_parameter)
-            << Param->getDeclName();
-        else
-          S.Diag(Param->getLocation(),
-                 diag::note_partial_spec_unused_parameter)
-            << "(anonymous)";
-      }
-    }
+    noteNonDeducibleParameters(S, TemplateParams, DeducibleParams);
   }
 }
 
@@ -2743,6 +3243,29 @@ void Sema::CheckTemplatePartialSpecialization(
   checkTemplatePartialSpecialization(*this, Partial);
 }
 
+void Sema::CheckDeductionGuideTemplate(FunctionTemplateDecl *TD) {
+  // C++1z [temp.param]p11:
+  //   A template parameter of a deduction guide template that does not have a
+  //   default-argument shall be deducible from the parameter-type-list of the
+  //   deduction guide template.
+  auto *TemplateParams = TD->getTemplateParameters();
+  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
+  MarkDeducedTemplateParameters(TD, DeducibleParams);
+  for (unsigned I = 0; I != TemplateParams->size(); ++I) {
+    // A parameter pack is deducible (to an empty pack).
+    auto *Param = TemplateParams->getParam(I);
+    if (Param->isParameterPack() || hasVisibleDefaultArgument(Param))
+      DeducibleParams[I] = true;
+  }
+
+  if (!DeducibleParams.all()) {
+    unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
+    Diag(TD->getLocation(), diag::err_deduction_guide_template_not_deducible)
+      << (NumNonDeducible > 1);
+    noteNonDeducibleParameters(*this, TemplateParams, DeducibleParams);
+  }
+}
+
 DeclResult Sema::ActOnVarTemplateSpecialization(
     Scope *S, Declarator &D, TypeSourceInfo *DI, SourceLocation TemplateKWLoc,
     TemplateParameterList *TemplateParams, StorageClass SC,
@@ -3224,7 +3747,8 @@ TemplateNameKind Sema::ActOnDependentTemplateName(Scope *S,
                                                   UnqualifiedId &Name,
                                                   ParsedType ObjectType,
                                                   bool EnteringContext,
-                                                  TemplateTy &Result) {
+                                                  TemplateTy &Result,
+                                                  bool AllowInjectedClassName) {
   if (TemplateKWLoc.isValid() && S && !S->getTemplateParamParent())
     Diag(TemplateKWLoc,
          getLangOpts().CPlusPlus11 ?
@@ -3272,6 +3796,24 @@ TemplateNameKind Sema::ActOnDependentTemplateName(Scope *S,
       return TNK_Non_template;
     } else {
       // We found something; return it.
+      auto *LookupRD = dyn_cast<CXXRecordDecl>(LookupCtx);
+      if (!AllowInjectedClassName && SS.isSet() && LookupRD &&
+          Name.getKind() == UnqualifiedId::IK_Identifier && Name.Identifier &&
+          LookupRD->getIdentifier() == Name.Identifier) {
+        // C++14 [class.qual]p2:
+        //   In a lookup in which function names are not ignored and the
+        //   nested-name-specifier nominates a class C, if the name specified
+        //   [...] is the injected-class-name of C, [...] the name is instead
+        //   considered to name the constructor
+        //
+        // We don't get here if naming the constructor would be valid, so we
+        // just reject immediately and recover by treating the
+        // injected-class-name as naming the template.
+        Diag(Name.getLocStart(),
+             diag::ext_out_of_line_qualified_id_type_names_constructor)
+          << Name.Identifier << 0 /*injected-class-name used as template name*/
+          << 1 /*'template' keyword was used*/;
+      }
       return TNK;
     }
   }
@@ -3326,7 +3868,7 @@ bool Sema::CheckTemplateTypeArgument(TemplateTypeParmDecl *Param,
     SourceRange SR = AL.getSourceRange();
     TemplateName Name = Arg.getAsTemplate();
     Diag(SR.getBegin(), diag::err_template_missing_args)
-      << Name << SR;
+      << (int)getTemplateNameKindForDiagnostics(Name) << Name << SR;
     if (TemplateDecl *Decl = Name.getAsTemplateDecl())
       Diag(Decl->getLocation(), diag::note_template_decl_here);
 
@@ -3520,8 +4062,8 @@ SubstDefaultTemplateArgument(Sema &SemaRef,
   for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
     TemplateArgLists.addOuterTemplateArguments(None);
 
-  EnterExpressionEvaluationContext ConstantEvaluated(SemaRef,
-                                                     Sema::ConstantEvaluated);
+  EnterExpressionEvaluationContext ConstantEvaluated(
+      SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
   return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists);
 }
 
@@ -3657,6 +4199,39 @@ Sema::SubstDefaultTemplateArgumentIfAvailable(TemplateDecl *Template,
                 TempTempParm->getDefaultArgument().getTemplateNameLoc());
 }
 
+/// Convert a template-argument that we parsed as a type into a template, if
+/// possible. C++ permits injected-class-names to perform dual service as
+/// template template arguments and as template type arguments.
+static TemplateArgumentLoc convertTypeTemplateArgumentToTemplate(TypeLoc TLoc) {
+  // Extract and step over any surrounding nested-name-specifier.
+  NestedNameSpecifierLoc QualLoc;
+  if (auto ETLoc = TLoc.getAs<ElaboratedTypeLoc>()) {
+    if (ETLoc.getTypePtr()->getKeyword() != ETK_None)
+      return TemplateArgumentLoc();
+
+    QualLoc = ETLoc.getQualifierLoc();
+    TLoc = ETLoc.getNamedTypeLoc();
+  }
+
+  // If this type was written as an injected-class-name, it can be used as a
+  // template template argument.
+  if (auto InjLoc = TLoc.getAs<InjectedClassNameTypeLoc>())
+    return TemplateArgumentLoc(InjLoc.getTypePtr()->getTemplateName(),
+                               QualLoc, InjLoc.getNameLoc());
+
+  // If this type was written as an injected-class-name, it may have been
+  // converted to a RecordType during instantiation. If the RecordType is
+  // *not* wrapped in a TemplateSpecializationType and denotes a class
+  // template specialization, it must have come from an injected-class-name.
+  if (auto RecLoc = TLoc.getAs<RecordTypeLoc>())
+    if (auto *CTSD =
+            dyn_cast<ClassTemplateSpecializationDecl>(RecLoc.getDecl()))
+      return TemplateArgumentLoc(TemplateName(CTSD->getSpecializedTemplate()),
+                                 QualLoc, RecLoc.getNameLoc());
+
+  return TemplateArgumentLoc();
+}
+
 /// \brief Check that the given template argument corresponds to the given
 /// template parameter.
 ///
@@ -3863,6 +4438,17 @@ bool Sema::CheckTemplateArgument(NamedDecl *Param,
       return true;
   }
 
+  // C++1z [temp.local]p1: (DR1004)
+  //   When [the injected-class-name] is used [...] as a template-argument for
+  //   a template template-parameter [...] it refers to the class template
+  //   itself.
+  if (Arg.getArgument().getKind() == TemplateArgument::Type) {
+    TemplateArgumentLoc ConvertedArg = convertTypeTemplateArgumentToTemplate(
+        Arg.getTypeSourceInfo()->getTypeLoc());
+    if (!ConvertedArg.getArgument().isNull())
+      Arg = ConvertedArg;
+  }
+
   switch (Arg.getArgument().getKind()) {
   case TemplateArgument::Null:
     llvm_unreachable("Should never see a NULL template argument here");
@@ -3911,9 +4497,7 @@ static bool diagnoseArityMismatch(Sema &S, TemplateDecl *Template,
                         TemplateArgs.getRAngleLoc());
   S.Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
     << (NumArgs > NumParams)
-    << (isa<ClassTemplateDecl>(Template)? 0 :
-        isa<FunctionTemplateDecl>(Template)? 1 :
-        isa<TemplateTemplateParmDecl>(Template)? 2 : 3)
+    << (int)S.getTemplateNameKindForDiagnostics(TemplateName(Template))
     << Template << Range;
   S.Diag(Template->getLocation(), diag::note_template_decl_here)
     << Params->getSourceRange();
@@ -3978,11 +4562,11 @@ static bool diagnoseMissingArgument(Sema &S, SourceLocation Loc,
 
 /// \brief Check that the given template argument list is well-formed
 /// for specializing the given template.
-bool Sema::CheckTemplateArgumentList(TemplateDecl *Template,
-                                     SourceLocation TemplateLoc,
-                                     TemplateArgumentListInfo &TemplateArgs,
-                                     bool PartialTemplateArgs,
-                          SmallVectorImpl<TemplateArgument> &Converted) {
+bool Sema::CheckTemplateArgumentList(
+    TemplateDecl *Template, SourceLocation TemplateLoc,
+    TemplateArgumentListInfo &TemplateArgs, bool PartialTemplateArgs,
+    SmallVectorImpl<TemplateArgument> &Converted,
+    bool UpdateArgsWithConversions) {
   // Make a copy of the template arguments for processing.  Only make the
   // changes at the end when successful in matching the arguments to the
   // template.
@@ -4021,9 +4605,7 @@ bool Sema::CheckTemplateArgumentList(TemplateDecl *Template,
         // Not enough arguments for this parameter pack.
         Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
           << false
-          << (isa<ClassTemplateDecl>(Template)? 0 :
-              isa<FunctionTemplateDecl>(Template)? 1 :
-              isa<TemplateTemplateParmDecl>(Template)? 2 : 3)
+          << (int)getTemplateNameKindForDiagnostics(TemplateName(Template))
           << Template;
         Diag(Template->getLocation(), diag::note_template_decl_here)
           << Params->getSourceRange();
@@ -4222,7 +4804,8 @@ bool Sema::CheckTemplateArgumentList(TemplateDecl *Template,
 
   // No problems found with the new argument list, propagate changes back
   // to caller.
-  TemplateArgs = std::move(NewArgs);
+  if (UpdateArgsWithConversions)
+    TemplateArgs = std::move(NewArgs);
 
   return false;
 }
@@ -4362,6 +4945,11 @@ bool UnnamedLocalNoLinkageFinder::VisitAutoType(const AutoType *T) {
   return Visit(T->getDeducedType());
 }
 
+bool UnnamedLocalNoLinkageFinder::VisitDeducedTemplateSpecializationType(
+    const DeducedTemplateSpecializationType *T) {
+  return Visit(T->getDeducedType());
+}
+
 bool UnnamedLocalNoLinkageFinder::VisitRecordType(const RecordType* T) {
   return VisitTagDecl(T->getDecl());
 }
@@ -5093,6 +5681,19 @@ ExprResult Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
 
   // If the parameter type somehow involves auto, deduce the type now.
   if (getLangOpts().CPlusPlus1z && ParamType->isUndeducedType()) {
+    // During template argument deduction, we allow 'decltype(auto)' to
+    // match an arbitrary dependent argument.
+    // FIXME: The language rules don't say what happens in this case.
+    // FIXME: We get an opaque dependent type out of decltype(auto) if the
+    // expression is merely instantiation-dependent; is this enough?
+    if (CTAK == CTAK_Deduced && Arg->isTypeDependent()) {
+      auto *AT = dyn_cast<AutoType>(ParamType);
+      if (AT && AT->isDecltypeAuto()) {
+        Converted = TemplateArgument(Arg);
+        return Arg;
+      }
+    }
+
     // When checking a deduced template argument, deduce from its type even if
     // the type is dependent, in order to check the types of non-type template
     // arguments line up properly in partial ordering.
@@ -5160,8 +5761,8 @@ ExprResult Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
 
   // The initialization of the parameter from the argument is
   // a constant-evaluated context.
-  EnterExpressionEvaluationContext ConstantEvaluated(*this,
-                                                     Sema::ConstantEvaluated);
+  EnterExpressionEvaluationContext ConstantEvaluated(
+      *this, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   if (getLangOpts().CPlusPlus1z) {
     // C++1z [temp.arg.nontype]p1:
@@ -5217,7 +5818,7 @@ ExprResult Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
       // -- a temporary object
       // -- a string literal
       // -- the result of a typeid expression, or
-      // -- a predefind __func__ variable
+      // -- a predefined __func__ variable
       if (auto *E = Value.getLValueBase().dyn_cast<const Expr*>()) {
         if (isa<CXXUuidofExpr>(E)) {
           Converted = TemplateArgument(const_cast<Expr*>(E));
@@ -5748,8 +6349,9 @@ Sema::BuildExpressionFromDeclTemplateArgument(const TemplateArgument &Arg,
     if (RefExpr.isInvalid())
       return ExprError();
 
-    if (T->isFunctionType() || T->isArrayType()) {
-      // Decay functions and arrays.
+    if (!Context.hasSameUnqualifiedType(ParamType->getPointeeType(), T) &&
+        (T->isFunctionType() || T->isArrayType())) {
+      // Decay functions and arrays unless we're forming a pointer to array.
       RefExpr = DefaultFunctionArrayConversion(RefExpr.get());
       if (RefExpr.isInvalid())
         return ExprError();
@@ -5838,15 +6440,6 @@ Sema::BuildExpressionFromIntegralTemplateArgument(const TemplateArgument &Arg,
   return E;
 }
 
-static bool isDependentOnOuter(NonTypeTemplateParmDecl *NTTP) {
-  if (NTTP->getDepth() == 0 || !NTTP->getType()->isDependentType())
-    return false;
-  DependencyChecker Checker(NTTP->getDepth(), /*IgnoreNonTypeDependent*/ false,
-                            /*FindLessThanDepth*/ true);
-  Checker.TraverseType(NTTP->getType());
-  return Checker.Match;
-}
-
 /// \brief Match two template parameters within template parameter lists.
 static bool MatchTemplateParameterKind(Sema &S, NamedDecl *New, NamedDecl *Old,
                                        bool Complain,
@@ -5903,10 +6496,11 @@ static bool MatchTemplateParameterKind(Sema &S, NamedDecl *New, NamedDecl *Old,
 
     // If we are matching a template template argument to a template
     // template parameter and one of the non-type template parameter types
-    // is dependent on an outer template's parameter, then we must wait until
-    // template instantiation time to actually compare the arguments.
+    // is dependent, then we must wait until template instantiation time
+    // to actually compare the arguments.
     if (Kind == Sema::TPL_TemplateTemplateArgumentMatch &&
-        (isDependentOnOuter(OldNTTP) || isDependentOnOuter(NewNTTP)))
+        (OldNTTP->getType()->isDependentType() ||
+         NewNTTP->getType()->isDependentType()))
       return true;
 
     if (!S.Context.hasSameType(OldNTTP->getType(), NewNTTP->getType())) {
@@ -6205,7 +6799,7 @@ static bool CheckTemplateSpecializationScope(Sema &S,
       // Do not warn for class scope explicit specialization during
       // instantiation, warning was already emitted during pattern
       // semantic analysis.
-      if (!S.ActiveTemplateInstantiations.size())
+      if (!S.inTemplateInstantiation())
         S.Diag(Loc, diag::ext_function_specialization_in_class)
           << Specialized;
     } else {
@@ -6479,7 +7073,7 @@ Sema::ActOnClassTemplateSpecialization(Scope *S, unsigned TagSpec,
     return true;
   }
 
-  bool isExplicitSpecialization = false;
+  bool isMemberSpecialization = false;
   bool isPartialSpecialization = false;
 
   // Check the validity of the template headers that introduce this
@@ -6490,7 +7084,7 @@ Sema::ActOnClassTemplateSpecialization(Scope *S, unsigned TagSpec,
   TemplateParameterList *TemplateParams =
       MatchTemplateParametersToScopeSpecifier(
           KWLoc, TemplateNameLoc, SS, &TemplateId,
-          TemplateParameterLists, TUK == TUK_Friend, isExplicitSpecialization,
+          TemplateParameterLists, TUK == TUK_Friend, isMemberSpecialization,
           Invalid);
   if (Invalid)
     return true;
@@ -6540,8 +7134,6 @@ Sema::ActOnClassTemplateSpecialization(Scope *S, unsigned TagSpec,
                                 SourceRange(TemplateParams->getTemplateLoc(),
                                             TemplateParams->getRAngleLoc()))
         << SourceRange(LAngleLoc, RAngleLoc);
-    else
-      isExplicitSpecialization = true;
   } else {
     assert(TUK == TUK_Friend && "should have a 'template<>' for this decl");
   }
@@ -8087,6 +8679,14 @@ DeclResult Sema::ActOnExplicitInstantiation(Scope *S,
     return true;
   }
 
+  // A deduction guide is not on the list of entities that can be explicitly
+  // instantiated.
+  if (Name.getNameKind() == DeclarationName::CXXDeductionGuideName) {
+    Diag(D.getDeclSpec().getLocStart(), diag::err_deduction_guide_specialized)
+      << /*explicit instantiation*/ 0;
+    return true;
+  }
+
   // C++0x [temp.explicit]p2:
   //   There are two forms of explicit instantiation: an explicit instantiation
   //   definition and an explicit instantiation declaration. An explicit
@@ -8491,7 +9091,8 @@ Sema::ActOnTypenameType(Scope *S,
                         const CXXScopeSpec &SS,
                         SourceLocation TemplateKWLoc,
                         TemplateTy TemplateIn,
-                        SourceLocation TemplateNameLoc,
+                        IdentifierInfo *TemplateII,
+                        SourceLocation TemplateIILoc,
                         SourceLocation LAngleLoc,
                         ASTTemplateArgsPtr TemplateArgsIn,
                         SourceLocation RAngleLoc) {
@@ -8502,6 +9103,19 @@ Sema::ActOnTypenameType(Scope *S,
            diag::ext_typename_outside_of_template)
       << FixItHint::CreateRemoval(TypenameLoc);
 
+  // Strangely, non-type results are not ignored by this lookup, so the
+  // program is ill-formed if it finds an injected-class-name.
+  if (TypenameLoc.isValid()) {
+    auto *LookupRD =
+        dyn_cast_or_null<CXXRecordDecl>(computeDeclContext(SS, false));
+    if (LookupRD && LookupRD->getIdentifier() == TemplateII) {
+      Diag(TemplateIILoc,
+           diag::ext_out_of_line_qualified_id_type_names_constructor)
+        << TemplateII << 0 /*injected-class-name used as template name*/
+        << (TemplateKWLoc.isValid() ? 1 : 0 /*'template'/'typename' keyword*/);
+    }
+  }
+
   // Translate the parser's template argument list in our AST format.
   TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
   translateTemplateArguments(TemplateArgsIn, TemplateArgs);
@@ -8523,7 +9137,7 @@ Sema::ActOnTypenameType(Scope *S,
     SpecTL.setElaboratedKeywordLoc(TypenameLoc);
     SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
     SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
-    SpecTL.setTemplateNameLoc(TemplateNameLoc);
+    SpecTL.setTemplateNameLoc(TemplateIILoc);
     SpecTL.setLAngleLoc(LAngleLoc);
     SpecTL.setRAngleLoc(RAngleLoc);
     for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
@@ -8531,7 +9145,7 @@ Sema::ActOnTypenameType(Scope *S,
     return CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
   }
 
-  QualType T = CheckTemplateIdType(Template, TemplateNameLoc, TemplateArgs);
+  QualType T = CheckTemplateIdType(Template, TemplateIILoc, TemplateArgs);
   if (T.isNull())
     return true;
 
@@ -8540,7 +9154,7 @@ Sema::ActOnTypenameType(Scope *S,
   TemplateSpecializationTypeLoc SpecTL
     = Builder.push<TemplateSpecializationTypeLoc>(T);
   SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
-  SpecTL.setTemplateNameLoc(TemplateNameLoc);
+  SpecTL.setTemplateNameLoc(TemplateIILoc);
   SpecTL.setLAngleLoc(LAngleLoc);
   SpecTL.setRAngleLoc(RAngleLoc);
   for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
@@ -8667,14 +9281,49 @@ Sema::CheckTypenameType(ElaboratedTypeKeyword Keyword,
 
   case LookupResult::Found:
     if (TypeDecl *Type = dyn_cast<TypeDecl>(Result.getFoundDecl())) {
+      // C++ [class.qual]p2:
+      //   In a lookup in which function names are not ignored and the
+      //   nested-name-specifier nominates a class C, if the name specified
+      //   after the nested-name-specifier, when looked up in C, is the
+      //   injected-class-name of C [...] then the name is instead considered
+      //   to name the constructor of class C.
+      //
+      // Unlike in an elaborated-type-specifier, function names are not ignored
+      // in typename-specifier lookup. However, they are ignored in all the
+      // contexts where we form a typename type with no keyword (that is, in
+      // mem-initializer-ids, base-specifiers, and elaborated-type-specifiers).
+      //
+      // FIXME: That's not strictly true: mem-initializer-id lookup does not
+      // ignore functions, but that appears to be an oversight.
+      auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(Ctx);
+      auto *FoundRD = dyn_cast<CXXRecordDecl>(Type);
+      if (Keyword == ETK_Typename && LookupRD && FoundRD &&
+          FoundRD->isInjectedClassName() &&
+          declaresSameEntity(LookupRD, cast<Decl>(FoundRD->getParent())))
+        Diag(IILoc, diag::ext_out_of_line_qualified_id_type_names_constructor)
+            << &II << 1 << 0 /*'typename' keyword used*/;
+
       // We found a type. Build an ElaboratedType, since the
       // typename-specifier was just sugar.
       MarkAnyDeclReferenced(Type->getLocation(), Type, /*OdrUse=*/false);
-      return Context.getElaboratedType(ETK_Typename,
+      return Context.getElaboratedType(Keyword,
                                        QualifierLoc.getNestedNameSpecifier(),
                                        Context.getTypeDeclType(Type));
     }
 
+    // C++ [dcl.type.simple]p2:
+    //   A type-specifier of the form
+    //     typename[opt] nested-name-specifier[opt] template-name
+    //   is a placeholder for a deduced class type [...].
+    if (getLangOpts().CPlusPlus1z) {
+      if (auto *TD = getAsTypeTemplateDecl(Result.getFoundDecl())) {
+        return Context.getElaboratedType(
+            Keyword, QualifierLoc.getNestedNameSpecifier(),
+            Context.getDeducedTemplateSpecializationType(TemplateName(TD),
+                                                         QualType(), false));
+      }
+    }
+
     DiagID = diag::err_typename_nested_not_type;
     Referenced = Result.getFoundDecl();
     break;
diff --git a/lib/Sema/SemaTemplateDeduction.cpp b/lib/Sema/SemaTemplateDeduction.cpp
index 93e796ee9668..ebdf6dd57fc5 100644
--- a/lib/Sema/SemaTemplateDeduction.cpp
+++ b/lib/Sema/SemaTemplateDeduction.cpp
@@ -112,6 +112,15 @@ DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
                         SmallVectorImpl<DeducedTemplateArgument> &Deduced,
                         bool NumberOfArgumentsMustMatch);
 
+static void MarkUsedTemplateParameters(ASTContext &Ctx,
+                                       const TemplateArgument &TemplateArg,
+                                       bool OnlyDeduced, unsigned Depth,
+                                       llvm::SmallBitVector &Used);
+
+static void MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
+                                       bool OnlyDeduced, unsigned Level,
+                                       llvm::SmallBitVector &Deduced);
+
 /// \brief If the given expression is of a form that permits the deduction
 /// of a non-type template parameter, return the declaration of that
 /// non-type template parameter.
@@ -334,12 +343,24 @@ static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
   if (!S.getLangOpts().CPlusPlus1z)
     return Sema::TDK_Success;
 
+  if (NTTP->isExpandedParameterPack())
+    // FIXME: We may still need to deduce parts of the type here! But we
+    // don't have any way to find which slice of the type to use, and the
+    // type stored on the NTTP itself is nonsense. Perhaps the type of an
+    // expanded NTTP should be a pack expansion type?
+    return Sema::TDK_Success;
+
+  // Get the type of the parameter for deduction.
+  QualType ParamType = NTTP->getType();
+  if (auto *Expansion = dyn_cast<PackExpansionType>(ParamType))
+    ParamType = Expansion->getPattern();
+
   // FIXME: It's not clear how deduction of a parameter of reference
   // type from an argument (of non-reference type) should be performed.
   // For now, we just remove reference types from both sides and let
   // the final check for matching types sort out the mess.
   return DeduceTemplateArgumentsByTypeMatch(
-      S, TemplateParams, NTTP->getType().getNonReferenceType(),
+      S, TemplateParams, ParamType.getNonReferenceType(),
       ValueType.getNonReferenceType(), Info, Deduced, TDF_SkipNonDependent,
       /*PartialOrdering=*/false,
       /*ArrayBound=*/NewDeduced.wasDeducedFromArrayBound());
@@ -617,29 +638,68 @@ public:
                      SmallVectorImpl<DeducedTemplateArgument> &Deduced,
                      TemplateDeductionInfo &Info, TemplateArgument Pattern)
       : S(S), TemplateParams(TemplateParams), Deduced(Deduced), Info(Info) {
+    // Dig out the partially-substituted pack, if there is one.
+    const TemplateArgument *PartialPackArgs = nullptr;
+    unsigned NumPartialPackArgs = 0;
+    std::pair<unsigned, unsigned> PartialPackDepthIndex(-1u, -1u);
+    if (auto *Scope = S.CurrentInstantiationScope)
+      if (auto *Partial = Scope->getPartiallySubstitutedPack(
+              &PartialPackArgs, &NumPartialPackArgs))
+        PartialPackDepthIndex = getDepthAndIndex(Partial);
+
     // Compute the set of template parameter indices that correspond to
     // parameter packs expanded by the pack expansion.
     {
       llvm::SmallBitVector SawIndices(TemplateParams->size());
+
+      auto AddPack = [&](unsigned Index) {
+        if (SawIndices[Index])
+          return;
+        SawIndices[Index] = true;
+
+        // Save the deduced template argument for the parameter pack expanded
+        // by this pack expansion, then clear out the deduction.
+        DeducedPack Pack(Index);
+        Pack.Saved = Deduced[Index];
+        Deduced[Index] = TemplateArgument();
+
+        Packs.push_back(Pack);
+      };
+
+      // First look for unexpanded packs in the pattern.
       SmallVector<UnexpandedParameterPack, 2> Unexpanded;
       S.collectUnexpandedParameterPacks(Pattern, Unexpanded);
       for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
         unsigned Depth, Index;
         std::tie(Depth, Index) = getDepthAndIndex(Unexpanded[I]);
-        if (Depth == Info.getDeducedDepth() && !SawIndices[Index]) {
-          SawIndices[Index] = true;
-
-          // Save the deduced template argument for the parameter pack expanded
-          // by this pack expansion, then clear out the deduction.
-          DeducedPack Pack(Index);
-          Pack.Saved = Deduced[Index];
-          Deduced[Index] = TemplateArgument();
-
-          Packs.push_back(Pack);
-        }
+        if (Depth == Info.getDeducedDepth())
+          AddPack(Index);
       }
+      assert(!Packs.empty() && "Pack expansion without unexpanded packs?");
+
+      // This pack expansion will have been partially expanded iff the only
+      // unexpanded parameter pack within it is the partially-substituted pack.
+      IsPartiallyExpanded =
+          Packs.size() == 1 &&
+          PartialPackDepthIndex ==
+              std::make_pair(Info.getDeducedDepth(), Packs.front().Index);
+
+      // Skip over the pack elements that were expanded into separate arguments.
+      if (IsPartiallyExpanded)
+        PackElements += NumPartialPackArgs;
+
+      // We can also have deduced template parameters that do not actually
+      // appear in the pattern, but can be deduced by it (the type of a non-type
+      // template parameter pack, in particular). These won't have prevented us
+      // from partially expanding the pack.
+      llvm::SmallBitVector Used(TemplateParams->size());
+      MarkUsedTemplateParameters(S.Context, Pattern, /*OnlyDeduced*/true,
+                                 Info.getDeducedDepth(), Used);
+      for (int Index = Used.find_first(); Index != -1;
+           Index = Used.find_next(Index))
+        if (TemplateParams->getParam(Index)->isParameterPack())
+          AddPack(Index);
     }
-    assert(!Packs.empty() && "Pack expansion without unexpanded packs?");
 
     for (auto &Pack : Packs) {
       if (Info.PendingDeducedPacks.size() > Pack.Index)
@@ -648,18 +708,19 @@ public:
         Info.PendingDeducedPacks.resize(Pack.Index + 1);
       Info.PendingDeducedPacks[Pack.Index] = &Pack;
 
-      if (S.CurrentInstantiationScope) {
-        // If the template argument pack was explicitly specified, add that to
-        // the set of deduced arguments.
-        const TemplateArgument *ExplicitArgs;
-        unsigned NumExplicitArgs;
-        NamedDecl *PartiallySubstitutedPack =
-            S.CurrentInstantiationScope->getPartiallySubstitutedPack(
-                &ExplicitArgs, &NumExplicitArgs);
-        if (PartiallySubstitutedPack &&
-            getDepthAndIndex(PartiallySubstitutedPack) ==
-                std::make_pair(Info.getDeducedDepth(), Pack.Index))
-          Pack.New.append(ExplicitArgs, ExplicitArgs + NumExplicitArgs);
+      if (PartialPackDepthIndex ==
+            std::make_pair(Info.getDeducedDepth(), Pack.Index)) {
+        Pack.New.append(PartialPackArgs, PartialPackArgs + NumPartialPackArgs);
+        // We pre-populate the deduced value of the partially-substituted
+        // pack with the specified value. This is not entirely correct: the
+        // value is supposed to have been substituted, not deduced, but the
+        // cases where this is observable require an exact type match anyway.
+        //
+        // FIXME: If we could represent a "depth i, index j, pack elem k"
+        // parameter, we could substitute the partially-substituted pack
+        // everywhere and avoid this.
+        if (Pack.New.size() > PackElements)
+          Deduced[Pack.Index] = Pack.New[PackElements];
       }
     }
   }
@@ -671,16 +732,7 @@ public:
 
   /// Determine whether this pack has already been partially expanded into a
   /// sequence of (prior) function parameters / template arguments.
-  bool isPartiallyExpanded() {
-    if (Packs.size() != 1 || !S.CurrentInstantiationScope)
-      return false;
-
-    auto *PartiallySubstitutedPack =
-        S.CurrentInstantiationScope->getPartiallySubstitutedPack();
-    return PartiallySubstitutedPack &&
-           getDepthAndIndex(PartiallySubstitutedPack) ==
-               std::make_pair(Info.getDeducedDepth(), Packs.front().Index);
-  }
+  bool isPartiallyExpanded() { return IsPartiallyExpanded; }
 
   /// Move to deducing the next element in each pack that is being deduced.
   void nextPackElement() {
@@ -692,8 +744,13 @@ public:
       if (!Pack.New.empty() || !DeducedArg.isNull()) {
         while (Pack.New.size() < PackElements)
           Pack.New.push_back(DeducedTemplateArgument());
-        Pack.New.push_back(DeducedArg);
-        DeducedArg = DeducedTemplateArgument();
+        if (Pack.New.size() == PackElements)
+          Pack.New.push_back(DeducedArg);
+        else
+          Pack.New[PackElements] = DeducedArg;
+        DeducedArg = Pack.New.size() > PackElements + 1
+                         ? Pack.New[PackElements + 1]
+                         : DeducedTemplateArgument();
       }
     }
     ++PackElements;
@@ -730,6 +787,11 @@ public:
         std::copy(Pack.New.begin(), Pack.New.end(), ArgumentPack);
         NewPack = DeducedTemplateArgument(
             TemplateArgument(llvm::makeArrayRef(ArgumentPack, Pack.New.size())),
+            // FIXME: This is wrong, it's possible that some pack elements are
+            // deduced from an array bound and others are not:
+            //   template<typename ...T, T ...V> void g(const T (&...p)[V]);
+            //   g({1, 2, 3}, {{}, {}});
+            // ... should deduce T = {int, size_t (from array bound)}.
             Pack.New[0].wasDeducedFromArrayBound());
       }
 
@@ -779,6 +841,7 @@ private:
   SmallVectorImpl<DeducedTemplateArgument> &Deduced;
   TemplateDeductionInfo &Info;
   unsigned PackElements = 0;
+  bool IsPartiallyExpanded = false;
 
   SmallVector<DeducedPack, 2> Packs;
 };
@@ -963,6 +1026,32 @@ bool Sema::isSameOrCompatibleFunctionType(CanQualType Param,
   return Param == Arg;
 }
 
+/// Get the index of the first template parameter that was originally from the
+/// innermost template-parameter-list. This is 0 except when we concatenate
+/// the template parameter lists of a class template and a constructor template
+/// when forming an implicit deduction guide.
+static unsigned getFirstInnerIndex(FunctionTemplateDecl *FTD) {
+  auto *Guide = dyn_cast<CXXDeductionGuideDecl>(FTD->getTemplatedDecl());
+  if (!Guide || !Guide->isImplicit())
+    return 0;
+  return Guide->getDeducedTemplate()->getTemplateParameters()->size();
+}
+
+/// Determine whether a type denotes a forwarding reference.
+static bool isForwardingReference(QualType Param, unsigned FirstInnerIndex) {
+  // C++1z [temp.deduct.call]p3:
+  //   A forwarding reference is an rvalue reference to a cv-unqualified
+  //   template parameter that does not represent a template parameter of a
+  //   class template.
+  if (auto *ParamRef = Param->getAs<RValueReferenceType>()) {
+    if (ParamRef->getPointeeType().getQualifiers())
+      return false;
+    auto *TypeParm = ParamRef->getPointeeType()->getAs<TemplateTypeParmType>();
+    return TypeParm && TypeParm->getIndex() >= FirstInnerIndex;
+  }
+  return false;
+}
+
 /// \brief Deduce the template arguments by comparing the parameter type and
 /// the argument type (C++ [temp.deduct.type]).
 ///
@@ -1083,21 +1172,15 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
       //   taking the address of a function template (14.8.2.2) or when deducing
       //   template arguments from a function declaration (14.8.2.6) and Pi and
       //   Ai are parameters of the top-level parameter-type-list of P and A,
-      //   respectively, Pi is adjusted if it is an rvalue reference to a
-      //   cv-unqualified template parameter and Ai is an lvalue reference, in
+      //   respectively, Pi is adjusted if it is a forwarding reference and Ai
+      //   is an lvalue reference, in
       //   which case the type of Pi is changed to be the template parameter
       //   type (i.e., T&& is changed to simply T). [ Note: As a result, when
       //   Pi is T&& and Ai is X&, the adjusted Pi will be T, causing T to be
       //   deduced as X&. - end note ]
       TDF &= ~TDF_TopLevelParameterTypeList;
-
-      if (const RValueReferenceType *ParamRef
-                                        = Param->getAs<RValueReferenceType>()) {
-        if (isa<TemplateTypeParmType>(ParamRef->getPointeeType()) &&
-            !ParamRef->getPointeeType().getQualifiers())
-          if (Arg->isLValueReferenceType())
-            Param = ParamRef->getPointeeType();
-      }
+      if (isForwardingReference(Param, 0) && Arg->isLValueReferenceType())
+        Param = Param->getPointeeType();
     }
   }
 
@@ -1723,6 +1806,7 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
     case Type::Decltype:
     case Type::UnaryTransform:
     case Type::Auto:
+    case Type::DeducedTemplateSpecialization:
     case Type::DependentTemplateSpecialization:
     case Type::PackExpansion:
     case Type::Pipe:
@@ -2335,7 +2419,7 @@ static Sema::TemplateDeductionResult ConvertDeducedTemplateArguments(
   return Sema::TDK_Success;
 }
 
-DeclContext *getAsDeclContextOrEnclosing(Decl *D) {
+static DeclContext *getAsDeclContextOrEnclosing(Decl *D) {
   if (auto *DC = dyn_cast<DeclContext>(D))
     return DC;
   return D->getDeclContext();
@@ -2363,7 +2447,8 @@ FinishTemplateArgumentDeduction(
     SmallVectorImpl<DeducedTemplateArgument> &Deduced,
     TemplateDeductionInfo &Info) {
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(S, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      S, Sema::ExpressionEvaluationContext::Unevaluated);
   Sema::SFINAETrap Trap(S);
 
   Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Partial));
@@ -2435,13 +2520,14 @@ FinishTemplateArgumentDeduction(
 /// Complete template argument deduction for a class or variable template,
 /// when partial ordering against a partial specialization.
 // FIXME: Factor out duplication with partial specialization version above.
-Sema::TemplateDeductionResult FinishTemplateArgumentDeduction(
+static Sema::TemplateDeductionResult FinishTemplateArgumentDeduction(
     Sema &S, TemplateDecl *Template, bool PartialOrdering,
     const TemplateArgumentList &TemplateArgs,
     SmallVectorImpl<DeducedTemplateArgument> &Deduced,
     TemplateDeductionInfo &Info) {
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(S, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      S, Sema::ExpressionEvaluationContext::Unevaluated);
   Sema::SFINAETrap Trap(S);
 
   Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Template));
@@ -2491,7 +2577,8 @@ Sema::DeduceTemplateArguments(ClassTemplatePartialSpecializationDecl *Partial,
   //   list (14.8.2).
 
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
   SFINAETrap Trap(*this);
 
   SmallVector<DeducedTemplateArgument, 4> Deduced;
@@ -2533,7 +2620,8 @@ Sema::DeduceTemplateArguments(VarTemplatePartialSpecializationDecl *Partial,
   //   list (14.8.2).
 
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
   SFINAETrap Trap(*this);
 
   SmallVector<DeducedTemplateArgument, 4> Deduced;
@@ -2565,12 +2653,6 @@ static bool isSimpleTemplateIdType(QualType T) {
   return false;
 }
 
-static void
-MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
-                           bool OnlyDeduced,
-                           unsigned Level,
-                           llvm::SmallBitVector &Deduced);
-
 /// \brief Substitute the explicitly-provided template arguments into the
 /// given function template according to C++ [temp.arg.explicit].
 ///
@@ -2619,7 +2701,8 @@ Sema::SubstituteExplicitTemplateArguments(
   }
 
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
   SFINAETrap Trap(*this);
 
   // C++ [temp.arg.explicit]p3:
@@ -2633,18 +2716,15 @@ Sema::SubstituteExplicitTemplateArguments(
   // explicitly-specified template arguments against this function template,
   // and then substitute them into the function parameter types.
   SmallVector<TemplateArgument, 4> DeducedArgs;
-  InstantiatingTemplate Inst(*this, Info.getLocation(), FunctionTemplate,
-                             DeducedArgs,
-           ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution,
-                             Info);
+  InstantiatingTemplate Inst(
+      *this, Info.getLocation(), FunctionTemplate, DeducedArgs,
+      CodeSynthesisContext::ExplicitTemplateArgumentSubstitution, Info);
   if (Inst.isInvalid())
     return TDK_InstantiationDepth;
 
-  if (CheckTemplateArgumentList(FunctionTemplate,
-                                SourceLocation(),
-                                ExplicitTemplateArgs,
-                                true,
-                                Builder) || Trap.hasErrorOccurred()) {
+  if (CheckTemplateArgumentList(FunctionTemplate, SourceLocation(),
+                                ExplicitTemplateArgs, true, Builder, false) ||
+      Trap.hasErrorOccurred()) {
     unsigned Index = Builder.size();
     if (Index >= TemplateParams->size())
       Index = TemplateParams->size() - 1;
@@ -2920,16 +3000,16 @@ Sema::TemplateDeductionResult Sema::FinishTemplateArgumentDeduction(
     SmallVectorImpl<OriginalCallArg> const *OriginalCallArgs,
     bool PartialOverloading, llvm::function_ref<bool()> CheckNonDependent) {
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
   SFINAETrap Trap(*this);
 
   // Enter a new template instantiation context while we instantiate the
   // actual function declaration.
   SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
-  InstantiatingTemplate Inst(*this, Info.getLocation(), FunctionTemplate,
-                             DeducedArgs,
-              ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution,
-                             Info);
+  InstantiatingTemplate Inst(
+      *this, Info.getLocation(), FunctionTemplate, DeducedArgs,
+      CodeSynthesisContext::DeducedTemplateArgumentSubstitution, Info);
   if (Inst.isInvalid())
     return TDK_InstantiationDepth;
 
@@ -3186,12 +3266,9 @@ ResolveOverloadForDeduction(Sema &S, TemplateParameterList *TemplateParams,
 /// \returns true if the caller should not attempt to perform any template
 /// argument deduction based on this P/A pair because the argument is an
 /// overloaded function set that could not be resolved.
-static bool AdjustFunctionParmAndArgTypesForDeduction(Sema &S,
-                                          TemplateParameterList *TemplateParams,
-                                                      QualType &ParamType,
-                                                      QualType &ArgType,
-                                                      Expr *Arg,
-                                                      unsigned &TDF) {
+static bool AdjustFunctionParmAndArgTypesForDeduction(
+    Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
+    QualType &ParamType, QualType &ArgType, Expr *Arg, unsigned &TDF) {
   // C++0x [temp.deduct.call]p3:
   //   If P is a cv-qualified type, the top level cv-qualifiers of P's type
   //   are ignored for type deduction.
@@ -3222,13 +3299,10 @@ static bool AdjustFunctionParmAndArgTypesForDeduction(Sema &S,
       ArgType = Arg->getType();
     }
 
-    // C++0x [temp.deduct.call]p3:
-    //   If P is an rvalue reference to a cv-unqualified template
-    //   parameter and the argument is an lvalue, the type "lvalue
-    //   reference to A" is used in place of A for type deduction.
-    if (ParamRefType->isRValueReferenceType() &&
-        !ParamType.getQualifiers() &&
-        isa<TemplateTypeParmType>(ParamType) &&
+    // C++1z [temp.deduct.call]p3:
+    //   If P is a forwarding reference and the argument is an lvalue, the type
+    //   "lvalue reference to A" is used in place of A for type deduction.
+    if (isForwardingReference(QualType(ParamRefType, 0), FirstInnerIndex) &&
         Arg->isLValue())
       ArgType = S.Context.getLValueReferenceType(ArgType);
   } else {
@@ -3287,8 +3361,8 @@ hasDeducibleTemplateParameters(Sema &S, FunctionTemplateDecl *FunctionTemplate,
                                QualType T);
 
 static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
-    Sema &S, TemplateParameterList *TemplateParams, QualType ParamType,
-    Expr *Arg, TemplateDeductionInfo &Info,
+    Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
+    QualType ParamType, Expr *Arg, TemplateDeductionInfo &Info,
     SmallVectorImpl<DeducedTemplateArgument> &Deduced,
     SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
     bool DecomposedParam, unsigned ArgIdx, unsigned TDF);
@@ -3326,7 +3400,7 @@ static Sema::TemplateDeductionResult DeduceFromInitializerList(
   if (ElTy->isDependentType()) {
     for (Expr *E : ILE->inits()) {
       if (auto Result = DeduceTemplateArgumentsFromCallArgument(
-              S, TemplateParams, ElTy, E, Info, Deduced, OriginalCallArgs, true,
+              S, TemplateParams, 0, ElTy, E, Info, Deduced, OriginalCallArgs, true,
               ArgIdx, TDF))
         return Result;
     }
@@ -3340,10 +3414,12 @@ static Sema::TemplateDeductionResult DeduceFromInitializerList(
             getDeducedParameterFromExpr(Info, DependentArrTy->getSizeExpr())) {
       // We can perform template argument deduction for the given non-type
       // template parameter.
-      llvm::APInt Size(S.Context.getIntWidth(NTTP->getType()),
-                       ILE->getNumInits());
+      // C++ [temp.deduct.type]p13:
+      //   The type of N in the type T[N] is std::size_t.
+      QualType T = S.Context.getSizeType();
+      llvm::APInt Size(S.Context.getIntWidth(T), ILE->getNumInits());
       if (auto Result = DeduceNonTypeTemplateArgument(
-              S, TemplateParams, NTTP, llvm::APSInt(Size), NTTP->getType(),
+              S, TemplateParams, NTTP, llvm::APSInt(Size), T,
               /*ArrayBound=*/true, Info, Deduced))
         return Result;
     }
@@ -3355,8 +3431,8 @@ static Sema::TemplateDeductionResult DeduceFromInitializerList(
 /// \brief Perform template argument deduction per [temp.deduct.call] for a
 ///        single parameter / argument pair.
 static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
-    Sema &S, TemplateParameterList *TemplateParams, QualType ParamType,
-    Expr *Arg, TemplateDeductionInfo &Info,
+    Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
+    QualType ParamType, Expr *Arg, TemplateDeductionInfo &Info,
     SmallVectorImpl<DeducedTemplateArgument> &Deduced,
     SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
     bool DecomposedParam, unsigned ArgIdx, unsigned TDF) {
@@ -3365,8 +3441,8 @@ static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
 
   //   If P is a reference type [...]
   //   If P is a cv-qualified type [...]
-  if (AdjustFunctionParmAndArgTypesForDeduction(S, TemplateParams, ParamType,
-                                                ArgType, Arg, TDF))
+  if (AdjustFunctionParmAndArgTypesForDeduction(
+          S, TemplateParams, FirstInnerIndex, ParamType, ArgType, Arg, TDF))
     return Sema::TDK_Success;
 
   //   If [...] the argument is a non-empty initializer list [...]
@@ -3422,6 +3498,8 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
   FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
   unsigned NumParams = Function->getNumParams();
 
+  unsigned FirstInnerIndex = getFirstInnerIndex(FunctionTemplate);
+
   // C++ [temp.deduct.call]p1:
   //   Template argument deduction is done by comparing each function template
   //   parameter type (call it P) with the type of the corresponding argument
@@ -3476,7 +3554,7 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
 
     //   ... with the type of the corresponding argument
     return DeduceTemplateArgumentsFromCallArgument(
-        *this, TemplateParams, ParamType, Args[ArgIdx], Info, Deduced,
+        *this, TemplateParams, FirstInnerIndex, ParamType, Args[ArgIdx], Info, Deduced,
         OriginalCallArgs, /*Decomposed*/false, ArgIdx, /*TDF*/ 0);
   };
 
@@ -3659,7 +3737,8 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
   }
 
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
   SFINAETrap Trap(*this);
 
   Deduced.resize(TemplateParams->size());
@@ -3907,7 +3986,8 @@ Sema::DeduceTemplateArguments(FunctionTemplateDecl *ConversionTemplate,
   }
 
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
   SFINAETrap Trap(*this);
 
   // C++ [temp.deduct.conv]p1:
@@ -4020,17 +4100,26 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
 }
 
 namespace {
-  /// Substitute the 'auto' type specifier within a type for a given replacement
-  /// type.
-  class SubstituteAutoTransform :
-    public TreeTransform<SubstituteAutoTransform> {
+  /// Substitute the 'auto' specifier or deduced template specialization type
+  /// specifier within a type for a given replacement type.
+  class SubstituteDeducedTypeTransform :
+      public TreeTransform<SubstituteDeducedTypeTransform> {
     QualType Replacement;
-    bool UseAutoSugar;
+    bool UseTypeSugar;
   public:
-    SubstituteAutoTransform(Sema &SemaRef, QualType Replacement,
-                            bool UseAutoSugar = true)
-        : TreeTransform<SubstituteAutoTransform>(SemaRef),
-          Replacement(Replacement), UseAutoSugar(UseAutoSugar) {}
+    SubstituteDeducedTypeTransform(Sema &SemaRef, QualType Replacement,
+                            bool UseTypeSugar = true)
+        : TreeTransform<SubstituteDeducedTypeTransform>(SemaRef),
+          Replacement(Replacement), UseTypeSugar(UseTypeSugar) {}
+
+    QualType TransformDesugared(TypeLocBuilder &TLB, DeducedTypeLoc TL) {
+      assert(isa<TemplateTypeParmType>(Replacement) &&
+             "unexpected unsugared replacement kind");
+      QualType Result = Replacement;
+      TemplateTypeParmTypeLoc NewTL = TLB.push<TemplateTypeParmTypeLoc>(Result);
+      NewTL.setNameLoc(TL.getNameLoc());
+      return Result;
+    }
 
     QualType TransformAutoType(TypeLocBuilder &TLB, AutoTypeLoc TL) {
       // If we're building the type pattern to deduce against, don't wrap the
@@ -4040,21 +4129,29 @@ namespace {
       //   auto &&lref = lvalue;
       // must transform into "rvalue reference to T" not "rvalue reference to
       // auto type deduced as T" in order for [temp.deduct.call]p3 to apply.
-      if (!UseAutoSugar) {
-        assert(isa<TemplateTypeParmType>(Replacement) &&
-               "unexpected unsugared replacement kind");
-        QualType Result = Replacement;
-        TemplateTypeParmTypeLoc NewTL =
-          TLB.push<TemplateTypeParmTypeLoc>(Result);
-        NewTL.setNameLoc(TL.getNameLoc());
-        return Result;
-      } else {
-        QualType Result = SemaRef.Context.getAutoType(
-            Replacement, TL.getTypePtr()->getKeyword(), Replacement.isNull());
-        AutoTypeLoc NewTL = TLB.push<AutoTypeLoc>(Result);
-        NewTL.setNameLoc(TL.getNameLoc());
-        return Result;
-      }
+      //
+      // FIXME: Is this still necessary?
+      if (!UseTypeSugar)
+        return TransformDesugared(TLB, TL);
+
+      QualType Result = SemaRef.Context.getAutoType(
+          Replacement, TL.getTypePtr()->getKeyword(), Replacement.isNull());
+      auto NewTL = TLB.push<AutoTypeLoc>(Result);
+      NewTL.setNameLoc(TL.getNameLoc());
+      return Result;
+    }
+
+    QualType TransformDeducedTemplateSpecializationType(
+        TypeLocBuilder &TLB, DeducedTemplateSpecializationTypeLoc TL) {
+      if (!UseTypeSugar)
+        return TransformDesugared(TLB, TL);
+
+      QualType Result = SemaRef.Context.getDeducedTemplateSpecializationType(
+          TL.getTypePtr()->getTemplateName(),
+          Replacement, Replacement.isNull());
+      auto NewTL = TLB.push<DeducedTemplateSpecializationTypeLoc>(Result);
+      NewTL.setNameLoc(TL.getNameLoc());
+      return Result;
     }
 
     ExprResult TransformLambdaExpr(LambdaExpr *E) {
@@ -4105,7 +4202,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
 
   if (!DependentDeductionDepth &&
       (Type.getType()->isDependentType() || Init->isTypeDependent())) {
-    Result = SubstituteAutoTransform(*this, QualType()).Apply(Type);
+    Result = SubstituteDeducedTypeTransform(*this, QualType()).Apply(Type);
     assert(!Result.isNull() && "substituting DependentTy can't fail");
     return DAR_Succeeded;
   }
@@ -4128,7 +4225,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
         return DAR_FailedAlreadyDiagnosed;
       // FIXME: Support a non-canonical deduced type for 'auto'.
       Deduced = Context.getCanonicalType(Deduced);
-      Result = SubstituteAutoTransform(*this, Deduced).Apply(Type);
+      Result = SubstituteDeducedTypeTransform(*this, Deduced).Apply(Type);
       if (Result.isNull())
         return DAR_FailedAlreadyDiagnosed;
       return DAR_Succeeded;
@@ -4153,7 +4250,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
       Loc, Loc, TemplParamPtr, Loc, nullptr);
 
   QualType FuncParam =
-      SubstituteAutoTransform(*this, TemplArg, /*UseAutoSugar*/false)
+      SubstituteDeducedTypeTransform(*this, TemplArg, /*UseTypeSugar*/false)
           .Apply(Type);
   assert(!FuncParam.isNull() &&
          "substituting template parameter for 'auto' failed");
@@ -4168,7 +4265,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
   // might acquire a matching type in the instantiation.
   auto DeductionFailed = [&]() -> DeduceAutoResult {
     if (Init->isTypeDependent()) {
-      Result = SubstituteAutoTransform(*this, QualType()).Apply(Type);
+      Result = SubstituteDeducedTypeTransform(*this, QualType()).Apply(Type);
       assert(!Result.isNull() && "substituting DependentTy can't fail");
       return DAR_Succeeded;
     }
@@ -4187,7 +4284,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
 
     for (unsigned i = 0, e = InitList->getNumInits(); i < e; ++i) {
       if (DeduceTemplateArgumentsFromCallArgument(
-              *this, TemplateParamsSt.get(), TemplArg, InitList->getInit(i),
+              *this, TemplateParamsSt.get(), 0, TemplArg, InitList->getInit(i),
               Info, Deduced, OriginalCallArgs, /*Decomposed*/ true,
               /*ArgIdx*/ 0, /*TDF*/ 0))
         return DeductionFailed();
@@ -4199,7 +4296,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
     }
 
     if (DeduceTemplateArgumentsFromCallArgument(
-            *this, TemplateParamsSt.get(), FuncParam, Init, Info, Deduced,
+            *this, TemplateParamsSt.get(), 0, FuncParam, Init, Info, Deduced,
             OriginalCallArgs, /*Decomposed*/ false, /*ArgIdx*/ 0, /*TDF*/ 0))
       return DeductionFailed();
   }
@@ -4216,7 +4313,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
       return DAR_FailedAlreadyDiagnosed;
   }
 
-  Result = SubstituteAutoTransform(*this, DeducedType).Apply(Type);
+  Result = SubstituteDeducedTypeTransform(*this, DeducedType).Apply(Type);
   if (Result.isNull())
     return DAR_FailedAlreadyDiagnosed;
 
@@ -4239,15 +4336,22 @@ QualType Sema::SubstAutoType(QualType TypeWithAuto,
                              QualType TypeToReplaceAuto) {
   if (TypeToReplaceAuto->isDependentType())
     TypeToReplaceAuto = QualType();
-  return SubstituteAutoTransform(*this, TypeToReplaceAuto)
+  return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
       .TransformType(TypeWithAuto);
 }
 
-TypeSourceInfo* Sema::SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
-                             QualType TypeToReplaceAuto) {
+TypeSourceInfo *Sema::SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
+                                              QualType TypeToReplaceAuto) {
   if (TypeToReplaceAuto->isDependentType())
     TypeToReplaceAuto = QualType();
-  return SubstituteAutoTransform(*this, TypeToReplaceAuto)
+  return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
+      .TransformType(TypeWithAuto);
+}
+
+QualType Sema::ReplaceAutoType(QualType TypeWithAuto,
+                               QualType TypeToReplaceAuto) {
+  return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto,
+                                        /*UseTypeSugar*/ false)
       .TransformType(TypeWithAuto);
 }
 
@@ -4848,13 +4952,6 @@ bool Sema::isTemplateTemplateParameterAtLeastAsSpecializedAs(
   return isAtLeastAsSpecializedAs(*this, PType, AType, AArg, Info);
 }
 
-static void
-MarkUsedTemplateParameters(ASTContext &Ctx,
-                           const TemplateArgument &TemplateArg,
-                           bool OnlyDeduced,
-                           unsigned Depth,
-                           llvm::SmallBitVector &Used);
-
 /// \brief Mark the template parameters that are used by the given
 /// expression.
 static void
@@ -5154,8 +5251,9 @@ MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
     break;
 
   case Type::Auto:
+  case Type::DeducedTemplateSpecialization:
     MarkUsedTemplateParameters(Ctx,
-                               cast<AutoType>(T)->getDeducedType(),
+                               cast<DeducedType>(T)->getDeducedType(),
                                OnlyDeduced, Depth, Used);
 
   // None of these types have any template parameters in them.
diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index 9f744a1dc1b2..edd6edfce9dc 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -184,7 +184,7 @@ Sema::getTemplateInstantiationArgs(NamedDecl *D,
   return Result;
 }
 
-bool Sema::ActiveTemplateInstantiation::isInstantiationRecord() const {
+bool Sema::CodeSynthesisContext::isInstantiationRecord() const {
   switch (Kind) {
   case TemplateInstantiation:
   case ExceptionSpecInstantiation:
@@ -196,19 +196,19 @@ bool Sema::ActiveTemplateInstantiation::isInstantiationRecord() const {
     return true;
 
   case DefaultTemplateArgumentChecking:
+  case DeclaringSpecialMember:
     return false;
   }
 
-  llvm_unreachable("Invalid InstantiationKind!");
+  llvm_unreachable("Invalid SynthesisKind!");
 }
 
 Sema::InstantiatingTemplate::InstantiatingTemplate(
-    Sema &SemaRef, ActiveTemplateInstantiation::InstantiationKind Kind,
+    Sema &SemaRef, CodeSynthesisContext::SynthesisKind Kind,
     SourceLocation PointOfInstantiation, SourceRange InstantiationRange,
     Decl *Entity, NamedDecl *Template, ArrayRef<TemplateArgument> TemplateArgs,
     sema::TemplateDeductionInfo *DeductionInfo)
-    : SemaRef(SemaRef), SavedInNonInstantiationSFINAEContext(
-                            SemaRef.InNonInstantiationSFINAEContext) {
+    : SemaRef(SemaRef) {
   // Don't allow further instantiation if a fatal error and an uncompilable
   // error have occurred. Any diagnostics we might have raised will not be
   // visible, and we do not need to construct a correct AST.
@@ -219,7 +219,7 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
   }
   Invalid = CheckInstantiationDepth(PointOfInstantiation, InstantiationRange);
   if (!Invalid) {
-    ActiveTemplateInstantiation Inst;
+    CodeSynthesisContext Inst;
     Inst.Kind = Kind;
     Inst.PointOfInstantiation = PointOfInstantiation;
     Inst.Entity = Entity;
@@ -228,14 +228,12 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
     Inst.NumTemplateArgs = TemplateArgs.size();
     Inst.DeductionInfo = DeductionInfo;
     Inst.InstantiationRange = InstantiationRange;
+    SemaRef.pushCodeSynthesisContext(Inst);
+
     AlreadyInstantiating =
         !SemaRef.InstantiatingSpecializations
              .insert(std::make_pair(Inst.Entity->getCanonicalDecl(), Inst.Kind))
              .second;
-    SemaRef.InNonInstantiationSFINAEContext = false;
-    SemaRef.ActiveTemplateInstantiations.push_back(Inst);
-    if (!Inst.isInstantiationRecord())
-      ++SemaRef.NonInstantiationEntries;
   }
 }
 
@@ -243,14 +241,14 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
     Sema &SemaRef, SourceLocation PointOfInstantiation, Decl *Entity,
     SourceRange InstantiationRange)
     : InstantiatingTemplate(SemaRef,
-                            ActiveTemplateInstantiation::TemplateInstantiation,
+                            CodeSynthesisContext::TemplateInstantiation,
                             PointOfInstantiation, InstantiationRange, Entity) {}
 
 Sema::InstantiatingTemplate::InstantiatingTemplate(
     Sema &SemaRef, SourceLocation PointOfInstantiation, FunctionDecl *Entity,
     ExceptionSpecification, SourceRange InstantiationRange)
     : InstantiatingTemplate(
-          SemaRef, ActiveTemplateInstantiation::ExceptionSpecInstantiation,
+          SemaRef, CodeSynthesisContext::ExceptionSpecInstantiation,
           PointOfInstantiation, InstantiationRange, Entity) {}
 
 Sema::InstantiatingTemplate::InstantiatingTemplate(
@@ -259,7 +257,7 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
     SourceRange InstantiationRange)
     : InstantiatingTemplate(
           SemaRef,
-          ActiveTemplateInstantiation::DefaultTemplateArgumentInstantiation,
+          CodeSynthesisContext::DefaultTemplateArgumentInstantiation,
           PointOfInstantiation, InstantiationRange, getAsNamedDecl(Param),
           Template, TemplateArgs) {}
 
@@ -267,14 +265,14 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
     Sema &SemaRef, SourceLocation PointOfInstantiation,
     FunctionTemplateDecl *FunctionTemplate,
     ArrayRef<TemplateArgument> TemplateArgs,
-    ActiveTemplateInstantiation::InstantiationKind Kind,
+    CodeSynthesisContext::SynthesisKind Kind,
     sema::TemplateDeductionInfo &DeductionInfo, SourceRange InstantiationRange)
     : InstantiatingTemplate(SemaRef, Kind, PointOfInstantiation,
                             InstantiationRange, FunctionTemplate, nullptr,
                             TemplateArgs, &DeductionInfo) {
   assert(
-    Kind == ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution ||
-    Kind == ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution);
+    Kind == CodeSynthesisContext::ExplicitTemplateArgumentSubstitution ||
+    Kind == CodeSynthesisContext::DeducedTemplateArgumentSubstitution);
 }
 
 Sema::InstantiatingTemplate::InstantiatingTemplate(
@@ -284,7 +282,7 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
     sema::TemplateDeductionInfo &DeductionInfo, SourceRange InstantiationRange)
     : InstantiatingTemplate(
           SemaRef,
-          ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution,
+          CodeSynthesisContext::DeducedTemplateArgumentSubstitution,
           PointOfInstantiation, InstantiationRange, Template, nullptr,
           TemplateArgs, &DeductionInfo) {}
 
@@ -295,7 +293,7 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
     sema::TemplateDeductionInfo &DeductionInfo, SourceRange InstantiationRange)
     : InstantiatingTemplate(
           SemaRef,
-          ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution,
+          CodeSynthesisContext::DeducedTemplateArgumentSubstitution,
           PointOfInstantiation, InstantiationRange, PartialSpec, nullptr,
           TemplateArgs, &DeductionInfo) {}
 
@@ -306,7 +304,7 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
     sema::TemplateDeductionInfo &DeductionInfo, SourceRange InstantiationRange)
     : InstantiatingTemplate(
           SemaRef,
-          ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution,
+          CodeSynthesisContext::DeducedTemplateArgumentSubstitution,
           PointOfInstantiation, InstantiationRange, PartialSpec, nullptr,
           TemplateArgs, &DeductionInfo) {}
 
@@ -315,7 +313,7 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
     ArrayRef<TemplateArgument> TemplateArgs, SourceRange InstantiationRange)
     : InstantiatingTemplate(
           SemaRef,
-          ActiveTemplateInstantiation::DefaultFunctionArgumentInstantiation,
+          CodeSynthesisContext::DefaultFunctionArgumentInstantiation,
           PointOfInstantiation, InstantiationRange, Param, nullptr,
           TemplateArgs) {}
 
@@ -325,7 +323,7 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
     SourceRange InstantiationRange)
     : InstantiatingTemplate(
           SemaRef,
-          ActiveTemplateInstantiation::PriorTemplateArgumentSubstitution,
+          CodeSynthesisContext::PriorTemplateArgumentSubstitution,
           PointOfInstantiation, InstantiationRange, Param, Template,
           TemplateArgs) {}
 
@@ -335,7 +333,7 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
     SourceRange InstantiationRange)
     : InstantiatingTemplate(
           SemaRef,
-          ActiveTemplateInstantiation::PriorTemplateArgumentSubstitution,
+          CodeSynthesisContext::PriorTemplateArgumentSubstitution,
           PointOfInstantiation, InstantiationRange, Param, Template,
           TemplateArgs) {}
 
@@ -344,36 +342,59 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
     NamedDecl *Param, ArrayRef<TemplateArgument> TemplateArgs,
     SourceRange InstantiationRange)
     : InstantiatingTemplate(
-          SemaRef, ActiveTemplateInstantiation::DefaultTemplateArgumentChecking,
+          SemaRef, CodeSynthesisContext::DefaultTemplateArgumentChecking,
           PointOfInstantiation, InstantiationRange, Param, Template,
           TemplateArgs) {}
 
+void Sema::pushCodeSynthesisContext(CodeSynthesisContext Ctx) {
+  Ctx.SavedInNonInstantiationSFINAEContext = InNonInstantiationSFINAEContext;
+  InNonInstantiationSFINAEContext = false;
+
+  CodeSynthesisContexts.push_back(Ctx);
+
+  if (!Ctx.isInstantiationRecord())
+    ++NonInstantiationEntries;
+}
+
+void Sema::popCodeSynthesisContext() {
+  auto &Active = CodeSynthesisContexts.back();
+  if (!Active.isInstantiationRecord()) {
+    assert(NonInstantiationEntries > 0);
+    --NonInstantiationEntries;
+  }
+
+  InNonInstantiationSFINAEContext = Active.SavedInNonInstantiationSFINAEContext;
+
+  // Name lookup no longer looks in this template's defining module.
+  assert(CodeSynthesisContexts.size() >=
+             CodeSynthesisContextLookupModules.size() &&
+         "forgot to remove a lookup module for a template instantiation");
+  if (CodeSynthesisContexts.size() ==
+      CodeSynthesisContextLookupModules.size()) {
+    if (Module *M = CodeSynthesisContextLookupModules.back())
+      LookupModulesCache.erase(M);
+    CodeSynthesisContextLookupModules.pop_back();
+  }
+
+  // If we've left the code synthesis context for the current context stack,
+  // stop remembering that we've emitted that stack.
+  if (CodeSynthesisContexts.size() ==
+      LastEmittedCodeSynthesisContextDepth)
+    LastEmittedCodeSynthesisContextDepth = 0;
+
+  CodeSynthesisContexts.pop_back();
+}
+
 void Sema::InstantiatingTemplate::Clear() {
   if (!Invalid) {
-    auto &Active = SemaRef.ActiveTemplateInstantiations.back();
-    if (!Active.isInstantiationRecord()) {
-      assert(SemaRef.NonInstantiationEntries > 0);
-      --SemaRef.NonInstantiationEntries;
-    }
-    SemaRef.InNonInstantiationSFINAEContext
-      = SavedInNonInstantiationSFINAEContext;
-
-    // Name lookup no longer looks in this template's defining module.
-    assert(SemaRef.ActiveTemplateInstantiations.size() >=
-           SemaRef.ActiveTemplateInstantiationLookupModules.size() &&
-           "forgot to remove a lookup module for a template instantiation");
-    if (SemaRef.ActiveTemplateInstantiations.size() ==
-        SemaRef.ActiveTemplateInstantiationLookupModules.size()) {
-      if (Module *M = SemaRef.ActiveTemplateInstantiationLookupModules.back())
-        SemaRef.LookupModulesCache.erase(M);
-      SemaRef.ActiveTemplateInstantiationLookupModules.pop_back();
-    }
-
-    if (!AlreadyInstantiating)
+    if (!AlreadyInstantiating) {
+      auto &Active = SemaRef.CodeSynthesisContexts.back();
       SemaRef.InstantiatingSpecializations.erase(
           std::make_pair(Active.Entity, Active.Kind));
+    }
+
+    SemaRef.popCodeSynthesisContext();
 
-    SemaRef.ActiveTemplateInstantiations.pop_back();
     Invalid = true;
   }
 }
@@ -382,8 +403,8 @@ bool Sema::InstantiatingTemplate::CheckInstantiationDepth(
                                         SourceLocation PointOfInstantiation,
                                            SourceRange InstantiationRange) {
   assert(SemaRef.NonInstantiationEntries <=
-                                   SemaRef.ActiveTemplateInstantiations.size());
-  if ((SemaRef.ActiveTemplateInstantiations.size() - 
+         SemaRef.CodeSynthesisContexts.size());
+  if ((SemaRef.CodeSynthesisContexts.size() - 
           SemaRef.NonInstantiationEntries)
         <= SemaRef.getLangOpts().InstantiationDepth)
     return false;
@@ -401,18 +422,18 @@ bool Sema::InstantiatingTemplate::CheckInstantiationDepth(
 /// notes.
 void Sema::PrintInstantiationStack() {
   // Determine which template instantiations to skip, if any.
-  unsigned SkipStart = ActiveTemplateInstantiations.size(), SkipEnd = SkipStart;
+  unsigned SkipStart = CodeSynthesisContexts.size(), SkipEnd = SkipStart;
   unsigned Limit = Diags.getTemplateBacktraceLimit();
-  if (Limit && Limit < ActiveTemplateInstantiations.size()) {
+  if (Limit && Limit < CodeSynthesisContexts.size()) {
     SkipStart = Limit / 2 + Limit % 2;
-    SkipEnd = ActiveTemplateInstantiations.size() - Limit / 2;
+    SkipEnd = CodeSynthesisContexts.size() - Limit / 2;
   }
 
   // FIXME: In all of these cases, we need to show the template arguments
   unsigned InstantiationIdx = 0;
-  for (SmallVectorImpl<ActiveTemplateInstantiation>::reverse_iterator
-         Active = ActiveTemplateInstantiations.rbegin(),
-         ActiveEnd = ActiveTemplateInstantiations.rend();
+  for (SmallVectorImpl<CodeSynthesisContext>::reverse_iterator
+         Active = CodeSynthesisContexts.rbegin(),
+         ActiveEnd = CodeSynthesisContexts.rend();
        Active != ActiveEnd;
        ++Active, ++InstantiationIdx) {
     // Skip this instantiation?
@@ -421,13 +442,13 @@ void Sema::PrintInstantiationStack() {
         // Note that we're skipping instantiations.
         Diags.Report(Active->PointOfInstantiation,
                      diag::note_instantiation_contexts_suppressed)
-          << unsigned(ActiveTemplateInstantiations.size() - Limit);
+          << unsigned(CodeSynthesisContexts.size() - Limit);
       }
       continue;
     }
 
     switch (Active->Kind) {
-    case ActiveTemplateInstantiation::TemplateInstantiation: {
+    case CodeSynthesisContext::TemplateInstantiation: {
       Decl *D = Active->Entity;
       if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
         unsigned DiagID = diag::note_template_member_class_here;
@@ -469,7 +490,7 @@ void Sema::PrintInstantiationStack() {
       break;
     }
 
-    case ActiveTemplateInstantiation::DefaultTemplateArgumentInstantiation: {
+    case CodeSynthesisContext::DefaultTemplateArgumentInstantiation: {
       TemplateDecl *Template = cast<TemplateDecl>(Active->Template);
       SmallVector<char, 128> TemplateArgsStr;
       llvm::raw_svector_ostream OS(TemplateArgsStr);
@@ -483,7 +504,7 @@ void Sema::PrintInstantiationStack() {
       break;
     }
 
-    case ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution: {
+    case CodeSynthesisContext::ExplicitTemplateArgumentSubstitution: {
       FunctionTemplateDecl *FnTmpl = cast<FunctionTemplateDecl>(Active->Entity);
       Diags.Report(Active->PointOfInstantiation,
                    diag::note_explicit_template_arg_substitution_here)
@@ -495,7 +516,7 @@ void Sema::PrintInstantiationStack() {
       break;
     }
 
-    case ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution: {
+    case CodeSynthesisContext::DeducedTemplateArgumentSubstitution: {
       if (FunctionTemplateDecl *FnTmpl =
               dyn_cast<FunctionTemplateDecl>(Active->Entity)) {
         Diags.Report(Active->PointOfInstantiation,
@@ -533,7 +554,7 @@ void Sema::PrintInstantiationStack() {
       break;
     }
 
-    case ActiveTemplateInstantiation::DefaultFunctionArgumentInstantiation: {
+    case CodeSynthesisContext::DefaultFunctionArgumentInstantiation: {
       ParmVarDecl *Param = cast<ParmVarDecl>(Active->Entity);
       FunctionDecl *FD = cast<FunctionDecl>(Param->getDeclContext());
 
@@ -549,7 +570,7 @@ void Sema::PrintInstantiationStack() {
       break;
     }
 
-    case ActiveTemplateInstantiation::PriorTemplateArgumentSubstitution: {
+    case CodeSynthesisContext::PriorTemplateArgumentSubstitution: {
       NamedDecl *Parm = cast<NamedDecl>(Active->Entity);
       std::string Name;
       if (!Parm->getName().empty())
@@ -573,7 +594,7 @@ void Sema::PrintInstantiationStack() {
       break;
     }
 
-    case ActiveTemplateInstantiation::DefaultTemplateArgumentChecking: {
+    case CodeSynthesisContext::DefaultTemplateArgumentChecking: {
       TemplateParameterList *TemplateParams = nullptr;
       if (TemplateDecl *Template = dyn_cast<TemplateDecl>(Active->Template))
         TemplateParams = Template->getTemplateParameters();
@@ -591,12 +612,18 @@ void Sema::PrintInstantiationStack() {
       break;
     }
 
-    case ActiveTemplateInstantiation::ExceptionSpecInstantiation:
+    case CodeSynthesisContext::ExceptionSpecInstantiation:
       Diags.Report(Active->PointOfInstantiation,
                    diag::note_template_exception_spec_instantiation_here)
         << cast<FunctionDecl>(Active->Entity)
         << Active->InstantiationRange;
       break;
+
+    case CodeSynthesisContext::DeclaringSpecialMember:
+      Diags.Report(Active->PointOfInstantiation,
+                   diag::note_in_declaration_of_implicit_special_member)
+        << cast<CXXRecordDecl>(Active->Entity) << Active->SpecialMember;
+      break;
     }
   }
 }
@@ -605,39 +632,49 @@ Optional<TemplateDeductionInfo *> Sema::isSFINAEContext() const {
   if (InNonInstantiationSFINAEContext)
     return Optional<TemplateDeductionInfo *>(nullptr);
 
-  for (SmallVectorImpl<ActiveTemplateInstantiation>::const_reverse_iterator
-         Active = ActiveTemplateInstantiations.rbegin(),
-         ActiveEnd = ActiveTemplateInstantiations.rend();
+  for (SmallVectorImpl<CodeSynthesisContext>::const_reverse_iterator
+         Active = CodeSynthesisContexts.rbegin(),
+         ActiveEnd = CodeSynthesisContexts.rend();
        Active != ActiveEnd;
        ++Active) 
   {
-    switch(Active->Kind) {
-    case ActiveTemplateInstantiation::TemplateInstantiation:
+    switch (Active->Kind) {
+    case CodeSynthesisContext::TemplateInstantiation:
       // An instantiation of an alias template may or may not be a SFINAE
       // context, depending on what else is on the stack.
       if (isa<TypeAliasTemplateDecl>(Active->Entity))
         break;
       // Fall through.
-    case ActiveTemplateInstantiation::DefaultFunctionArgumentInstantiation:
-    case ActiveTemplateInstantiation::ExceptionSpecInstantiation:
+    case CodeSynthesisContext::DefaultFunctionArgumentInstantiation:
+    case CodeSynthesisContext::ExceptionSpecInstantiation:
       // This is a template instantiation, so there is no SFINAE.
       return None;
 
-    case ActiveTemplateInstantiation::DefaultTemplateArgumentInstantiation:
-    case ActiveTemplateInstantiation::PriorTemplateArgumentSubstitution:
-    case ActiveTemplateInstantiation::DefaultTemplateArgumentChecking:
+    case CodeSynthesisContext::DefaultTemplateArgumentInstantiation:
+    case CodeSynthesisContext::PriorTemplateArgumentSubstitution:
+    case CodeSynthesisContext::DefaultTemplateArgumentChecking:
       // A default template argument instantiation and substitution into
       // template parameters with arguments for prior parameters may or may 
       // not be a SFINAE context; look further up the stack.
       break;
 
-    case ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution:
-    case ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution:
+    case CodeSynthesisContext::ExplicitTemplateArgumentSubstitution:
+    case CodeSynthesisContext::DeducedTemplateArgumentSubstitution:
       // We're either substitution explicitly-specified template arguments
       // or deduced template arguments, so SFINAE applies.
       assert(Active->DeductionInfo && "Missing deduction info pointer");
       return Active->DeductionInfo;
+
+    case CodeSynthesisContext::DeclaringSpecialMember:
+      // This happens in a context unrelated to template instantiation, so
+      // there is no SFINAE.
+      return None;
     }
+
+    // The inner context was transparent for SFINAE. If it occurred within a
+    // non-instantiation SFINAE context, then SFINAE applies.
+    if (Active->SavedInNonInstantiationSFINAEContext)
+      return Optional<TemplateDeductionInfo *>(nullptr);
   }
 
   return None;
@@ -806,7 +843,8 @@ namespace {
     TransformTemplateName(CXXScopeSpec &SS, TemplateName Name,
                           SourceLocation NameLoc,
                           QualType ObjectType = QualType(),
-                          NamedDecl *FirstQualifierInScope = nullptr);
+                          NamedDecl *FirstQualifierInScope = nullptr,
+                          bool AllowInjectedClassName = false);
 
     const LoopHintAttr *TransformLoopHintAttr(const LoopHintAttr *LH);
 
@@ -1040,11 +1078,10 @@ TemplateInstantiator::RebuildElaboratedType(SourceLocation KeywordLoc,
                                                                     T);
 }
 
-TemplateName TemplateInstantiator::TransformTemplateName(CXXScopeSpec &SS,
-                                                         TemplateName Name,
-                                                         SourceLocation NameLoc,
-                                                         QualType ObjectType,
-                                             NamedDecl *FirstQualifierInScope) {
+TemplateName TemplateInstantiator::TransformTemplateName(
+    CXXScopeSpec &SS, TemplateName Name, SourceLocation NameLoc,
+    QualType ObjectType, NamedDecl *FirstQualifierInScope,
+    bool AllowInjectedClassName) {
   if (TemplateTemplateParmDecl *TTP
        = dyn_cast_or_null<TemplateTemplateParmDecl>(Name.getAsTemplateDecl())) {
     if (TTP->getDepth() < TemplateArgs.getNumLevels()) {
@@ -1095,9 +1132,10 @@ TemplateName TemplateInstantiator::TransformTemplateName(CXXScopeSpec &SS,
     Arg = getPackSubstitutedTemplateArgument(getSema(), Arg);
     return Arg.getAsTemplate();
   }
-  
-  return inherited::TransformTemplateName(SS, Name, NameLoc, ObjectType, 
-                                          FirstQualifierInScope);  
+
+  return inherited::TransformTemplateName(SS, Name, NameLoc, ObjectType,
+                                          FirstQualifierInScope,
+                                          AllowInjectedClassName);
 }
 
 ExprResult 
@@ -1120,6 +1158,23 @@ TemplateInstantiator::TransformTemplateParmRefExpr(DeclRefExpr *E,
     return E;
 
   TemplateArgument Arg = TemplateArgs(NTTP->getDepth(), NTTP->getPosition());
+
+  if (TemplateArgs.getNumLevels() != TemplateArgs.getNumSubstitutedLevels()) {
+    // We're performing a partial substitution, so the substituted argument
+    // could be dependent. As a result we can't create a SubstNonType*Expr
+    // node now, since that represents a fully-substituted argument.
+    // FIXME: We should have some AST representation for this.
+    if (Arg.getKind() == TemplateArgument::Pack) {
+      // FIXME: This won't work for alias templates.
+      assert(Arg.pack_size() == 1 && Arg.pack_begin()->isPackExpansion() &&
+             "unexpected pack arguments in partial substitution");
+      Arg = Arg.pack_begin()->getPackExpansionPattern();
+    }
+    assert(Arg.getKind() == TemplateArgument::Expression &&
+           "unexpected nontype template argument kind in partial substitution");
+    return Arg.getAsExpr();
+  }
+
   if (NTTP->isParameterPack()) {
     assert(Arg.getKind() == TemplateArgument::Pack && 
            "Missing argument pack");
@@ -1428,12 +1483,9 @@ TemplateInstantiator::TransformTemplateTypeParmType(TypeLocBuilder &TLB,
     NewTTPDecl = cast_or_null<TemplateTypeParmDecl>(
                                   TransformDecl(TL.getNameLoc(), OldTTPDecl));
 
-  QualType Result
-    = getSema().Context.getTemplateTypeParmType(T->getDepth()
-                                                 - TemplateArgs.getNumLevels(),
-                                                T->getIndex(),
-                                                T->isParameterPack(),
-                                                NewTTPDecl);
+  QualType Result = getSema().Context.getTemplateTypeParmType(
+      T->getDepth() - TemplateArgs.getNumSubstitutedLevels(), T->getIndex(),
+      T->isParameterPack(), NewTTPDecl);
   TemplateTypeParmTypeLoc NewTL = TLB.push<TemplateTypeParmTypeLoc>(Result);
   NewTL.setNameLoc(TL.getNameLoc());
   return Result;
@@ -1489,13 +1541,17 @@ TemplateInstantiator::TransformSubstTemplateTypeParmPackType(
 /// a cast expression) or that the entity has no name (e.g., an
 /// unnamed function parameter).
 ///
+/// \param AllowDeducedTST Whether a DeducedTemplateSpecializationType is
+/// acceptable as the top level type of the result.
+///
 /// \returns If the instantiation succeeds, the instantiated
 /// type. Otherwise, produces diagnostics and returns a NULL type.
 TypeSourceInfo *Sema::SubstType(TypeSourceInfo *T,
                                 const MultiLevelTemplateArgumentList &Args,
                                 SourceLocation Loc,
-                                DeclarationName Entity) {
-  assert(!ActiveTemplateInstantiations.empty() &&
+                                DeclarationName Entity,
+                                bool AllowDeducedTST) {
+  assert(!CodeSynthesisContexts.empty() &&
          "Cannot perform an instantiation without some context on the "
          "instantiation stack");
   
@@ -1504,14 +1560,15 @@ TypeSourceInfo *Sema::SubstType(TypeSourceInfo *T,
     return T;
 
   TemplateInstantiator Instantiator(*this, Args, Loc, Entity);
-  return Instantiator.TransformType(T);
+  return AllowDeducedTST ? Instantiator.TransformTypeWithDeducedTST(T)
+                         : Instantiator.TransformType(T);
 }
 
 TypeSourceInfo *Sema::SubstType(TypeLoc TL,
                                 const MultiLevelTemplateArgumentList &Args,
                                 SourceLocation Loc,
                                 DeclarationName Entity) {
-  assert(!ActiveTemplateInstantiations.empty() &&
+  assert(!CodeSynthesisContexts.empty() &&
          "Cannot perform an instantiation without some context on the "
          "instantiation stack");
   
@@ -1541,7 +1598,7 @@ TypeSourceInfo *Sema::SubstType(TypeLoc TL,
 QualType Sema::SubstType(QualType T,
                          const MultiLevelTemplateArgumentList &TemplateArgs,
                          SourceLocation Loc, DeclarationName Entity) {
-  assert(!ActiveTemplateInstantiations.empty() &&
+  assert(!CodeSynthesisContexts.empty() &&
          "Cannot perform an instantiation without some context on the "
          "instantiation stack");
 
@@ -1586,7 +1643,7 @@ TypeSourceInfo *Sema::SubstFunctionDeclType(TypeSourceInfo *T,
                                 DeclarationName Entity,
                                 CXXRecordDecl *ThisContext,
                                 unsigned ThisTypeQuals) {
-  assert(!ActiveTemplateInstantiations.empty() &&
+  assert(!CodeSynthesisContexts.empty() &&
          "Cannot perform an instantiation without some context on the "
          "instantiation stack");
 
@@ -1758,7 +1815,7 @@ bool Sema::SubstParmTypes(
     SmallVectorImpl<QualType> &ParamTypes,
     SmallVectorImpl<ParmVarDecl *> *OutParams,
     ExtParameterInfoBuilder &ParamInfos) {
-  assert(!ActiveTemplateInstantiations.empty() &&
+  assert(!CodeSynthesisContexts.empty() &&
          "Cannot perform an instantiation without some context on the "
          "instantiation stack");
   
@@ -1882,6 +1939,9 @@ namespace clang {
   namespace sema {
     Attr *instantiateTemplateAttribute(const Attr *At, ASTContext &C, Sema &S,
                             const MultiLevelTemplateArgumentList &TemplateArgs);
+    Attr *instantiateTemplateAttributeForDecl(
+        const Attr *At, ASTContext &C, Sema &S,
+        const MultiLevelTemplateArgumentList &TemplateArgs);
   }
 }
 
@@ -1942,8 +2002,8 @@ Sema::InstantiateClass(SourceLocation PointOfInstantiation,
   // Enter the scope of this instantiation. We don't use
   // PushDeclContext because we don't have a scope.
   ContextRAII SavedContext(*this, Instantiation);
-  EnterExpressionEvaluationContext EvalContext(*this, 
-                                               Sema::PotentiallyEvaluated);
+  EnterExpressionEvaluationContext EvalContext(
+      *this, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
 
   // If this is an instantiation of a local class, merge this local
   // instantiation scope with the enclosing scope. Otherwise, every
@@ -2173,8 +2233,8 @@ bool Sema::InstantiateEnum(SourceLocation PointOfInstantiation,
   // Enter the scope of this instantiation. We don't use
   // PushDeclContext because we don't have a scope.
   ContextRAII SavedContext(*this, Instantiation);
-  EnterExpressionEvaluationContext EvalContext(*this,
-                                               Sema::PotentiallyEvaluated);
+  EnterExpressionEvaluationContext EvalContext(
+      *this, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
 
   LocalInstantiationScope Scope(*this, /*MergeWithParentScope*/true);
 
@@ -2245,8 +2305,8 @@ bool Sema::InstantiateInClassInitializer(
   // Enter the scope of this instantiation. We don't use PushDeclContext because
   // we don't have a scope.
   ContextRAII SavedContext(*this, Instantiation->getParent());
-  EnterExpressionEvaluationContext EvalContext(*this,
-                                               Sema::PotentiallyEvaluated);
+  EnterExpressionEvaluationContext EvalContext(
+      *this, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
 
   LocalInstantiationScope Scope(*this, true);
 
diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 200775756d3a..9a71a17561c7 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -81,7 +81,8 @@ static void instantiateDependentAlignedAttr(
     const AlignedAttr *Aligned, Decl *New, bool IsPackExpansion) {
   if (Aligned->isAlignmentExpr()) {
     // The alignment expression is a constant expression.
-    EnterExpressionEvaluationContext Unevaluated(S, Sema::ConstantEvaluated);
+    EnterExpressionEvaluationContext Unevaluated(
+        S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
     ExprResult Result = S.SubstExpr(Aligned->getAlignmentExpr(), TemplateArgs);
     if (!Result.isInvalid())
       S.AddAlignedAttr(Aligned->getLocation(), New, Result.getAs<Expr>(),
@@ -138,7 +139,8 @@ static void instantiateDependentAssumeAlignedAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const AssumeAlignedAttr *Aligned, Decl *New) {
   // The alignment expression is a constant expression.
-  EnterExpressionEvaluationContext Unevaluated(S, Sema::ConstantEvaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   Expr *E, *OE = nullptr;
   ExprResult Result = S.SubstExpr(Aligned->getAlignment(), TemplateArgs);
@@ -161,20 +163,32 @@ static void instantiateDependentAlignValueAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const AlignValueAttr *Aligned, Decl *New) {
   // The alignment expression is a constant expression.
-  EnterExpressionEvaluationContext Unevaluated(S, Sema::ConstantEvaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
   ExprResult Result = S.SubstExpr(Aligned->getAlignment(), TemplateArgs);
   if (!Result.isInvalid())
     S.AddAlignValueAttr(Aligned->getLocation(), New, Result.getAs<Expr>(),
                         Aligned->getSpellingListIndex());
 }
 
+static void instantiateDependentAllocAlignAttr(
+    Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
+    const AllocAlignAttr *Align, Decl *New) {
+  Expr *Param = IntegerLiteral::Create(
+      S.getASTContext(), llvm::APInt(64, Align->getParamIndex()),
+      S.getASTContext().UnsignedLongLongTy, Align->getLocation());
+  S.AddAllocAlignAttr(Align->getLocation(), New, Param,
+                      Align->getSpellingListIndex());
+}
+
 static Expr *instantiateDependentFunctionAttrCondition(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const Attr *A, Expr *OldCond, const Decl *Tmpl, FunctionDecl *New) {
   Expr *Cond = nullptr;
   {
     Sema::ContextRAII SwitchContext(S, New);
-    EnterExpressionEvaluationContext Unevaluated(S, Sema::ConstantEvaluated);
+    EnterExpressionEvaluationContext Unevaluated(
+        S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
     ExprResult Result = S.SubstExpr(OldCond, TemplateArgs);
     if (Result.isInvalid())
       return nullptr;
@@ -229,7 +243,8 @@ static void instantiateDependentCUDALaunchBoundsAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const CUDALaunchBoundsAttr &Attr, Decl *New) {
   // The alignment expression is a constant expression.
-  EnterExpressionEvaluationContext Unevaluated(S, Sema::ConstantEvaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   ExprResult Result = S.SubstExpr(Attr.getMaxThreads(), TemplateArgs);
   if (Result.isInvalid())
@@ -328,6 +343,34 @@ static void instantiateOMPDeclareSimdDeclAttr(
       Attr.getRange());
 }
 
+static bool DeclContainsAttr(const Decl *D, const Attr *NewAttr) {
+  if (!D->hasAttrs() || NewAttr->duplicatesAllowed())
+    return false;
+  return llvm::find_if(D->getAttrs(), [NewAttr](const Attr *Attr) {
+           return Attr->getKind() == NewAttr->getKind();
+         }) != D->getAttrs().end();
+}
+
+void Sema::InstantiateAttrsForDecl(
+    const MultiLevelTemplateArgumentList &TemplateArgs, const Decl *Tmpl,
+    Decl *New, LateInstantiatedAttrVec *LateAttrs,
+    LocalInstantiationScope *OuterMostScope) {
+  if (NamedDecl *ND = dyn_cast<NamedDecl>(New)) {
+    for (const auto *TmplAttr : Tmpl->attrs()) {
+      // FIXME: If any of the special case versions from InstantiateAttrs become
+      // applicable to template declaration, we'll need to add them here.
+      CXXThisScopeRAII ThisScope(
+          *this, dyn_cast_or_null<CXXRecordDecl>(ND->getDeclContext()),
+          /*TypeQuals*/ 0, ND->isCXXInstanceMember());
+
+      Attr *NewAttr = sema::instantiateTemplateAttributeForDecl(
+          TmplAttr, Context, *this, TemplateArgs);
+      if (NewAttr && !DeclContainsAttr(New, NewAttr))
+        New->addAttr(NewAttr);
+    }
+  }
+}
+
 void Sema::InstantiateAttrs(const MultiLevelTemplateArgumentList &TemplateArgs,
                             const Decl *Tmpl, Decl *New,
                             LateInstantiatedAttrVec *LateAttrs,
@@ -352,6 +395,12 @@ void Sema::InstantiateAttrs(const MultiLevelTemplateArgumentList &TemplateArgs,
       continue;
     }
 
+    if (const auto *AllocAlign = dyn_cast<AllocAlignAttr>(TmplAttr)) {
+      instantiateDependentAllocAlignAttr(*this, TemplateArgs, AllocAlign, New);
+      continue;
+    }
+
+
     if (const auto *EnableIf = dyn_cast<EnableIfAttr>(TmplAttr)) {
       instantiateDependentEnableIfAttr(*this, TemplateArgs, EnableIf, Tmpl,
                                        cast<FunctionDecl>(New));
@@ -421,7 +470,8 @@ void Sema::InstantiateAttrs(const MultiLevelTemplateArgumentList &TemplateArgs,
 
       Attr *NewAttr = sema::instantiateTemplateAttribute(TmplAttr, Context,
                                                          *this, TemplateArgs);
-      if (NewAttr)
+
+      if (NewAttr && !DeclContainsAttr(New, NewAttr))
         New->addAttr(NewAttr);
     }
   }
@@ -657,10 +707,9 @@ Decl *TemplateDeclInstantiator::VisitVarDecl(VarDecl *D,
                                              ArrayRef<BindingDecl*> *Bindings) {
 
   // Do substitution on the type of the declaration
-  TypeSourceInfo *DI = SemaRef.SubstType(D->getTypeSourceInfo(),
-                                         TemplateArgs,
-                                         D->getTypeSpecStartLoc(),
-                                         D->getDeclName());
+  TypeSourceInfo *DI = SemaRef.SubstType(
+      D->getTypeSourceInfo(), TemplateArgs, D->getTypeSpecStartLoc(),
+      D->getDeclName(), /*AllowDeducedTST*/true);
   if (!DI)
     return nullptr;
 
@@ -746,8 +795,8 @@ Decl *TemplateDeclInstantiator::VisitFieldDecl(FieldDecl *D) {
     BitWidth = nullptr;
   else if (BitWidth) {
     // The bit-width expression is a constant expression.
-    EnterExpressionEvaluationContext Unevaluated(SemaRef,
-                                                 Sema::ConstantEvaluated);
+    EnterExpressionEvaluationContext Unevaluated(
+        SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
     ExprResult InstantiatedBitWidth
       = SemaRef.SubstExpr(BitWidth, TemplateArgs);
@@ -923,8 +972,8 @@ Decl *TemplateDeclInstantiator::VisitStaticAssertDecl(StaticAssertDecl *D) {
   Expr *AssertExpr = D->getAssertExpr();
 
   // The expression in a static assertion is a constant expression.
-  EnterExpressionEvaluationContext Unevaluated(SemaRef,
-                                               Sema::ConstantEvaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   ExprResult InstantiatedAssertExpr
     = SemaRef.SubstExpr(AssertExpr, TemplateArgs);
@@ -1034,8 +1083,8 @@ void TemplateDeclInstantiator::InstantiateEnumDefinition(
     ExprResult Value((Expr *)nullptr);
     if (Expr *UninstValue = EC->getInitExpr()) {
       // The enumerator's value expression is a constant expression.
-      EnterExpressionEvaluationContext Unevaluated(SemaRef,
-                                                   Sema::ConstantEvaluated);
+      EnterExpressionEvaluationContext Unevaluated(
+          SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
       Value = SemaRef.SubstExpr(UninstValue, TemplateArgs);
     }
@@ -1600,13 +1649,18 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D,
                                          TemplateArgs);
   }
 
-  FunctionDecl *Function =
-      FunctionDecl::Create(SemaRef.Context, DC, D->getInnerLocStart(),
-                           D->getNameInfo(), T, TInfo,
-                           D->getCanonicalDecl()->getStorageClass(),
-                           D->isInlineSpecified(), D->hasWrittenPrototype(),
-                           D->isConstexpr());
-  Function->setRangeEnd(D->getSourceRange().getEnd());
+  FunctionDecl *Function;
+  if (auto *DGuide = dyn_cast<CXXDeductionGuideDecl>(D))
+    Function = CXXDeductionGuideDecl::Create(
+        SemaRef.Context, DC, D->getInnerLocStart(), DGuide->isExplicit(),
+        D->getNameInfo(), T, TInfo, D->getSourceRange().getEnd());
+  else {
+    Function = FunctionDecl::Create(
+        SemaRef.Context, DC, D->getInnerLocStart(), D->getNameInfo(), T, TInfo,
+        D->getCanonicalDecl()->getStorageClass(), D->isInlineSpecified(),
+        D->hasWrittenPrototype(), D->isConstexpr());
+    Function->setRangeEnd(D->getSourceRange().getEnd());
+  }
 
   if (D->isInlined())
     Function->setImplicitlyInline();
@@ -1656,8 +1710,6 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D,
     FunctionTemplate->setLexicalDeclContext(LexicalDC);
 
     if (isFriend && D->isThisDeclarationADefinition()) {
-      // TODO: should we remember this connection regardless of whether
-      // the friend declaration provided a body?
       FunctionTemplate->setInstantiatedFromMemberTemplate(
                                            D->getDescribedFunctionTemplate());
     }
@@ -1668,13 +1720,10 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D,
                             TemplateArgumentList::CreateCopy(SemaRef.Context,
                                                              Innermost),
                                                 /*InsertPos=*/nullptr);
-  } else if (isFriend) {
-    // Note, we need this connection even if the friend doesn't have a body.
-    // Its body may exist but not have been attached yet due to deferred
-    // parsing.
-    // FIXME: It might be cleaner to set this when attaching the body to the
-    // friend function declaration, however that would require finding all the
-    // instantiations and modifying them.
+  } else if (isFriend && D->isThisDeclarationADefinition()) {
+    // Do not connect the friend to the template unless it's actually a
+    // definition. We don't want non-template functions to be marked as being
+    // template instantiations.
     Function->setInstantiationOfMemberFunction(D, TSK_ImplicitInstantiation);
   }
 
@@ -2075,13 +2124,10 @@ Decl *TemplateDeclInstantiator::VisitTemplateTypeParmDecl(
   // TODO: don't always clone when decls are refcounted.
   assert(D->getTypeForDecl()->isTemplateTypeParmType());
 
-  TemplateTypeParmDecl *Inst =
-    TemplateTypeParmDecl::Create(SemaRef.Context, Owner,
-                                 D->getLocStart(), D->getLocation(),
-                                 D->getDepth() - TemplateArgs.getNumLevels(),
-                                 D->getIndex(), D->getIdentifier(),
-                                 D->wasDeclaredWithTypename(),
-                                 D->isParameterPack());
+  TemplateTypeParmDecl *Inst = TemplateTypeParmDecl::Create(
+      SemaRef.Context, Owner, D->getLocStart(), D->getLocation(),
+      D->getDepth() - TemplateArgs.getNumSubstitutedLevels(), D->getIndex(),
+      D->getIdentifier(), D->wasDeclaredWithTypename(), D->isParameterPack());
   Inst->setAccess(AS_public);
 
   if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
@@ -2219,25 +2265,22 @@ Decl *TemplateDeclInstantiator::VisitNonTypeTemplateParmDecl(
   if (IsExpandedParameterPack)
     Param = NonTypeTemplateParmDecl::Create(
         SemaRef.Context, Owner, D->getInnerLocStart(), D->getLocation(),
-        D->getDepth() - TemplateArgs.getNumLevels(), D->getPosition(),
-        D->getIdentifier(), T, DI, ExpandedParameterPackTypes,
+        D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
+        D->getPosition(), D->getIdentifier(), T, DI, ExpandedParameterPackTypes,
         ExpandedParameterPackTypesAsWritten);
   else
-    Param = NonTypeTemplateParmDecl::Create(SemaRef.Context, Owner,
-                                            D->getInnerLocStart(),
-                                            D->getLocation(),
-                                    D->getDepth() - TemplateArgs.getNumLevels(),
-                                            D->getPosition(),
-                                            D->getIdentifier(), T,
-                                            D->isParameterPack(), DI);
+    Param = NonTypeTemplateParmDecl::Create(
+        SemaRef.Context, Owner, D->getInnerLocStart(), D->getLocation(),
+        D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
+        D->getPosition(), D->getIdentifier(), T, D->isParameterPack(), DI);
 
   Param->setAccess(AS_public);
   if (Invalid)
     Param->setInvalidDecl();
 
   if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
-    EnterExpressionEvaluationContext ConstantEvaluated(SemaRef,
-                                                       Sema::ConstantEvaluated);
+    EnterExpressionEvaluationContext ConstantEvaluated(
+        SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
     ExprResult Value = SemaRef.SubstExpr(D->getDefaultArgument(), TemplateArgs);
     if (!Value.isInvalid())
       Param->setDefaultArgument(Value.get());
@@ -2350,19 +2393,15 @@ TemplateDeclInstantiator::VisitTemplateTemplateParmDecl(
   // Build the template template parameter.
   TemplateTemplateParmDecl *Param;
   if (IsExpandedParameterPack)
-    Param = TemplateTemplateParmDecl::Create(SemaRef.Context, Owner,
-                                             D->getLocation(),
-                                   D->getDepth() - TemplateArgs.getNumLevels(),
-                                             D->getPosition(),
-                                             D->getIdentifier(), InstParams,
-                                             ExpandedParams);
+    Param = TemplateTemplateParmDecl::Create(
+        SemaRef.Context, Owner, D->getLocation(),
+        D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
+        D->getPosition(), D->getIdentifier(), InstParams, ExpandedParams);
   else
-    Param = TemplateTemplateParmDecl::Create(SemaRef.Context, Owner,
-                                             D->getLocation(),
-                                   D->getDepth() - TemplateArgs.getNumLevels(),
-                                             D->getPosition(),
-                                             D->isParameterPack(),
-                                             D->getIdentifier(), InstParams);
+    Param = TemplateTemplateParmDecl::Create(
+        SemaRef.Context, Owner, D->getLocation(),
+        D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
+        D->getPosition(), D->isParameterPack(), D->getIdentifier(), InstParams);
   if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
     NestedNameSpecifierLoc QualifierLoc =
         D->getDefaultArgument().getTemplateQualifierLoc();
@@ -2783,6 +2822,11 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D) {
   return VisitFunctionDecl(D, nullptr);
 }
 
+Decl *
+TemplateDeclInstantiator::VisitCXXDeductionGuideDecl(CXXDeductionGuideDecl *D) {
+  return VisitFunctionDecl(D, nullptr);
+}
+
 Decl *TemplateDeclInstantiator::VisitCXXMethodDecl(CXXMethodDecl *D) {
   return VisitCXXMethodDecl(D, nullptr);
 }
@@ -3555,6 +3599,8 @@ TemplateDeclInstantiator::InitFunctionInstantiation(FunctionDecl *New,
   if (Tmpl->isDeleted())
     New->setDeletedAsWritten();
 
+  New->setImplicit(Tmpl->isImplicit());
+
   // Forward the mangling number from the template to the instantiated decl.
   SemaRef.Context.setManglingNumber(New,
                                     SemaRef.Context.getManglingNumber(Tmpl));
@@ -3567,8 +3613,8 @@ TemplateDeclInstantiator::InitFunctionInstantiation(FunctionDecl *New,
   // into a template instantiation for this specific function template
   // specialization, which is not a SFINAE context, so that we diagnose any
   // further errors in the declaration itself.
-  typedef Sema::ActiveTemplateInstantiation ActiveInstType;
-  ActiveInstType &ActiveInst = SemaRef.ActiveTemplateInstantiations.back();
+  typedef Sema::CodeSynthesisContext ActiveInstType;
+  ActiveInstType &ActiveInst = SemaRef.CodeSynthesisContexts.back();
   if (ActiveInst.Kind == ActiveInstType::ExplicitTemplateArgumentSubstitution ||
       ActiveInst.Kind == ActiveInstType::DeducedTemplateArgumentSubstitution) {
     if (FunctionTemplateDecl *FunTmpl
@@ -3810,8 +3856,8 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
   // Copy the inner loc start from the pattern.
   Function->setInnerLocStart(PatternDecl->getInnerLocStart());
 
-  EnterExpressionEvaluationContext EvalContext(*this,
-                                               Sema::PotentiallyEvaluated);
+  EnterExpressionEvaluationContext EvalContext(
+      *this, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
 
   // Introduce a new scope where local variable instantiations will be
   // recorded, unless we're actually a member function within a local
@@ -3864,6 +3910,8 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
     if (Body.isInvalid())
       Function->setInvalidDecl();
 
+    // FIXME: finishing the function body while in an expression evaluation
+    // context seems wrong. Investigate more.
     ActOnFinishFunctionBody(Function, Body.get(),
                             /*IsInstantiation=*/true);
 
@@ -4073,9 +4121,11 @@ void Sema::InstantiateVariableInitializer(
 
   if (OldVar->getInit()) {
     if (Var->isStaticDataMember() && !OldVar->isOutOfLine())
-      PushExpressionEvaluationContext(Sema::ConstantEvaluated, OldVar);
+      PushExpressionEvaluationContext(
+          Sema::ExpressionEvaluationContext::ConstantEvaluated, OldVar);
     else
-      PushExpressionEvaluationContext(Sema::PotentiallyEvaluated, OldVar);
+      PushExpressionEvaluationContext(
+          Sema::ExpressionEvaluationContext::PotentiallyEvaluated, OldVar);
 
     // Instantiate the initializer.
     ExprResult Init;
@@ -4954,6 +5004,28 @@ NamedDecl *Sema::FindInstantiatedDecl(SourceLocation Loc, NamedDecl *D,
           DC = FD->getLexicalDeclContext();
           continue;
         }
+        // An implicit deduction guide acts as if it's within the class template
+        // specialization described by its name and first N template params.
+        auto *Guide = dyn_cast<CXXDeductionGuideDecl>(FD);
+        if (Guide && Guide->isImplicit()) {
+          TemplateDecl *TD = Guide->getDeducedTemplate();
+          // Convert the arguments to an "as-written" list.
+          TemplateArgumentListInfo Args(Loc, Loc);
+          for (TemplateArgument Arg : TemplateArgs.getInnermost().take_front(
+                                        TD->getTemplateParameters()->size())) {
+            ArrayRef<TemplateArgument> Unpacked(Arg);
+            if (Arg.getKind() == TemplateArgument::Pack)
+              Unpacked = Arg.pack_elements();
+            for (TemplateArgument UnpackedArg : Unpacked)
+              Args.addArgument(
+                  getTrivialTemplateArgumentLoc(UnpackedArg, QualType(), Loc));
+          }
+          QualType T = CheckTemplateIdType(TemplateName(TD), Loc, Args);
+          if (T.isNull())
+            return nullptr;
+          DC = T->getAsCXXRecordDecl();
+          continue;
+        }
       }
 
       DC = DC->getParent();
diff --git a/lib/Sema/SemaTemplateVariadic.cpp b/lib/Sema/SemaTemplateVariadic.cpp
index 725a3e425201..9f572007d8a7 100644
--- a/lib/Sema/SemaTemplateVariadic.cpp
+++ b/lib/Sema/SemaTemplateVariadic.cpp
@@ -321,6 +321,7 @@ bool Sema::DiagnoseUnexpandedParameterPack(const DeclarationNameInfo &NameInfo,
   case DeclarationName::CXXOperatorName:
   case DeclarationName::CXXLiteralOperatorName:
   case DeclarationName::CXXUsingDirective:
+  case DeclarationName::CXXDeductionGuideName:
     return false;
 
   case DeclarationName::CXXConstructorName:
diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index 2cdf76caa7ef..279b9ecef94e 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -742,7 +742,7 @@ static void diagnoseAndRemoveTypeQualifiers(Sema &S, const DeclSpec &DS,
     if (!(RemoveTQs & Qual.first))
       continue;
 
-    if (S.ActiveTemplateInstantiations.empty()) {
+    if (!S.inTemplateInstantiation()) {
       if (TypeQuals & Qual.first)
         S.Diag(Qual.second, DiagID)
           << DeclSpec::getSpecifierName(Qual.first) << TypeSoFar
@@ -1502,40 +1502,7 @@ static QualType ConvertDeclSpecToType(TypeProcessingState &state) {
     break;
 
   case DeclSpec::TST_auto:
-    // TypeQuals handled by caller.
-    // If auto is mentioned in a lambda parameter context, convert it to a 
-    // template parameter type immediately, with the appropriate depth and 
-    // index, and update sema's state (LambdaScopeInfo) for the current lambda 
-    // being analyzed (which tracks the invented type template parameter).
-    if (declarator.getContext() == Declarator::LambdaExprParameterContext) {
-      sema::LambdaScopeInfo *LSI = S.getCurLambda();
-      assert(LSI && "No LambdaScopeInfo on the stack!");
-      const unsigned TemplateParameterDepth = LSI->AutoTemplateParameterDepth;
-      const unsigned AutoParameterPosition = LSI->AutoTemplateParams.size();
-      const bool IsParameterPack = declarator.hasEllipsis();
-
-      // Turns out we must create the TemplateTypeParmDecl here to 
-      // retrieve the corresponding template parameter type. 
-      TemplateTypeParmDecl *CorrespondingTemplateParam =
-        TemplateTypeParmDecl::Create(Context, 
-        // Temporarily add to the TranslationUnit DeclContext.  When the 
-        // associated TemplateParameterList is attached to a template
-        // declaration (such as FunctionTemplateDecl), the DeclContext 
-        // for each template parameter gets updated appropriately via
-        // a call to AdoptTemplateParameterList. 
-        Context.getTranslationUnitDecl(), 
-        /*KeyLoc*/ SourceLocation(), 
-        /*NameLoc*/ declarator.getLocStart(),  
-        TemplateParameterDepth, 
-        AutoParameterPosition,  // our template param index 
-        /* Identifier*/ nullptr, false, IsParameterPack);
-      LSI->AutoTemplateParams.push_back(CorrespondingTemplateParam);
-      // Replace the 'auto' in the function parameter with this invented 
-      // template type parameter.
-      Result = QualType(CorrespondingTemplateParam->getTypeForDecl(), 0);
-    } else {
-      Result = Context.getAutoType(QualType(), AutoTypeKeyword::Auto, false);
-    }
+    Result = Context.getAutoType(QualType(), AutoTypeKeyword::Auto, false);
     break;
 
   case DeclSpec::TST_auto_type:
@@ -2766,6 +2733,12 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
                      D.getDeclSpec().getAttributes().getList());
     break;
 
+  case UnqualifiedId::IK_DeductionGuideName:
+    // Deduction guides have a trailing return type and no type in their
+    // decl-specifier sequence. Use a placeholder return type for now.
+    T = SemaRef.Context.DependentTy;
+    break;
+
   case UnqualifiedId::IK_ConversionFunctionId:
     // The result type of a conversion function is the type that it
     // converts to.
@@ -2778,12 +2751,20 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
     distributeTypeAttrsFromDeclarator(state, T);
 
   // C++11 [dcl.spec.auto]p5: reject 'auto' if it is not in an allowed context.
-  if (D.getDeclSpec().containsPlaceholderType()) {
+  if (DeducedType *Deduced = T->getContainedDeducedType()) {
+    AutoType *Auto = dyn_cast<AutoType>(Deduced);
     int Error = -1;
 
+    // Is this a 'auto' or 'decltype(auto)' type (as opposed to __auto_type or
+    // class template argument deduction)?
+    bool IsCXXAutoType =
+        (Auto && Auto->getKeyword() != AutoTypeKeyword::GNUAutoType);
+
     switch (D.getContext()) {
     case Declarator::LambdaExprContext:
-      llvm_unreachable("Can't specify a type specifier in lambda grammar");
+      // Declared return type of a lambda-declarator is implicit and is always
+      // 'auto'.
+      break;
     case Declarator::ObjCParameterContext:
     case Declarator::ObjCResultContext:
     case Declarator::PrototypeContext:
@@ -2791,9 +2772,35 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
       break;
     case Declarator::LambdaExprParameterContext:
       // In C++14, generic lambdas allow 'auto' in their parameters.
-      if (!(SemaRef.getLangOpts().CPlusPlus14 
-              && D.getDeclSpec().getTypeSpecType() == DeclSpec::TST_auto))
+      if (!SemaRef.getLangOpts().CPlusPlus14 ||
+          !Auto || Auto->getKeyword() != AutoTypeKeyword::Auto)
         Error = 16;
+      else {
+        // If auto is mentioned in a lambda parameter context, convert it to a 
+        // template parameter type.
+        sema::LambdaScopeInfo *LSI = SemaRef.getCurLambda();
+        assert(LSI && "No LambdaScopeInfo on the stack!");
+        const unsigned TemplateParameterDepth = LSI->AutoTemplateParameterDepth;
+        const unsigned AutoParameterPosition = LSI->AutoTemplateParams.size();
+        const bool IsParameterPack = D.hasEllipsis();
+
+        // Create the TemplateTypeParmDecl here to retrieve the corresponding
+        // template parameter type. Template parameters are temporarily added
+        // to the TU until the associated TemplateDecl is created.
+        TemplateTypeParmDecl *CorrespondingTemplateParam =
+            TemplateTypeParmDecl::Create(
+                SemaRef.Context, SemaRef.Context.getTranslationUnitDecl(),
+                /*KeyLoc*/SourceLocation(), /*NameLoc*/D.getLocStart(),
+                TemplateParameterDepth, AutoParameterPosition,
+                /*Identifier*/nullptr, false, IsParameterPack);
+        LSI->AutoTemplateParams.push_back(CorrespondingTemplateParam);
+        // Replace the 'auto' in the function parameter with this invented 
+        // template type parameter.
+        // FIXME: Retain some type sugar to indicate that this was written
+        // as 'auto'.
+        T = SemaRef.ReplaceAutoType(
+            T, QualType(CorrespondingTemplateParam->getTypeForDecl(), 0));
+      }
       break;
     case Declarator::MemberContext: {
       if (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static ||
@@ -2807,6 +2814,8 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
       case TTK_Class:  Error = 5; /* Class member */ break;
       case TTK_Interface: Error = 6; /* Interface member */ break;
       }
+      if (D.getDeclSpec().isFriendSpecified())
+        Error = 20; // Friend type
       break;
     }
     case Declarator::CXXCatchContext:
@@ -2814,8 +2823,10 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
       Error = 7; // Exception declaration
       break;
     case Declarator::TemplateParamContext:
-      if (!SemaRef.getLangOpts().CPlusPlus1z)
-        Error = 8; // Template parameter
+      if (isa<DeducedTemplateSpecializationType>(Deduced))
+        Error = 19; // Template parameter
+      else if (!SemaRef.getLangOpts().CPlusPlus1z)
+        Error = 8; // Template parameter (until C++1z)
       break;
     case Declarator::BlockLiteralContext:
       Error = 9; // Block literal
@@ -2828,15 +2839,17 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
       Error = 12; // Type alias
       break;
     case Declarator::TrailingReturnContext:
-      if (!SemaRef.getLangOpts().CPlusPlus14 ||
-          D.getDeclSpec().getTypeSpecType() == DeclSpec::TST_auto_type)
+      if (!SemaRef.getLangOpts().CPlusPlus14 || !IsCXXAutoType)
         Error = 13; // Function return type
       break;
     case Declarator::ConversionIdContext:
-      if (!SemaRef.getLangOpts().CPlusPlus14 ||
-          D.getDeclSpec().getTypeSpecType() == DeclSpec::TST_auto_type)
+      if (!SemaRef.getLangOpts().CPlusPlus14 || !IsCXXAutoType)
         Error = 14; // conversion-type-id
       break;
+    case Declarator::FunctionalCastContext:
+      if (isa<DeducedTemplateSpecializationType>(Deduced))
+        break;
+      LLVM_FALLTHROUGH;
     case Declarator::TypeNameContext:
       Error = 15; // Generic
       break;
@@ -2845,9 +2858,14 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
     case Declarator::ForContext:
     case Declarator::InitStmtContext:
     case Declarator::ConditionContext:
+      // FIXME: P0091R3 (erroneously) does not permit class template argument
+      // deduction in conditions, for-init-statements, and other declarations
+      // that are not simple-declarations.
       break;
     case Declarator::CXXNewContext:
-      if (D.getDeclSpec().getTypeSpecType() == DeclSpec::TST_auto_type)
+      // FIXME: P0091R3 does not permit class template argument deduction here,
+      // but we follow GCC and allow it anyway.
+      if (!IsCXXAutoType && !isa<DeducedTemplateSpecializationType>(Deduced))
         Error = 17; // 'new' type
       break;
     case Declarator::KNRTypeListContext:
@@ -2861,8 +2879,7 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
     // In Objective-C it is an error to use 'auto' on a function declarator
     // (and everywhere for '__auto_type').
     if (D.isFunctionDeclarator() &&
-        (!SemaRef.getLangOpts().CPlusPlus11 ||
-         D.getDeclSpec().getTypeSpecType() == DeclSpec::TST_auto_type))
+        (!SemaRef.getLangOpts().CPlusPlus11 || !IsCXXAutoType))
       Error = 13;
 
     bool HaveTrailing = false;
@@ -2872,21 +2889,11 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
     // level. Check all declarator chunks (outermost first) anyway, to give
     // better diagnostics.
     // We don't support '__auto_type' with trailing return types.
-    if (SemaRef.getLangOpts().CPlusPlus11 &&
-        D.getDeclSpec().getTypeSpecType() != DeclSpec::TST_auto_type) {
-      for (unsigned i = 0, e = D.getNumTypeObjects(); i != e; ++i) {
-        unsigned chunkIndex = e - i - 1;
-        state.setCurrentChunkIndex(chunkIndex);
-        DeclaratorChunk &DeclType = D.getTypeObject(chunkIndex);
-        if (DeclType.Kind == DeclaratorChunk::Function) {
-          const DeclaratorChunk::FunctionTypeInfo &FTI = DeclType.Fun;
-          if (FTI.hasTrailingReturnType()) {
-            HaveTrailing = true;
-            Error = -1;
-            break;
-          }
-        }
-      }
+    // FIXME: Should we only do this for 'auto' and not 'decltype(auto)'?
+    if (SemaRef.getLangOpts().CPlusPlus11 && IsCXXAutoType &&
+        D.hasTrailingReturnType()) {
+      HaveTrailing = true;
+      Error = -1;
     }
 
     SourceRange AutoRange = D.getDeclSpec().getTypeSpecTypeLoc();
@@ -2894,15 +2901,28 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
       AutoRange = D.getName().getSourceRange();
 
     if (Error != -1) {
-      unsigned Keyword;
-      switch (D.getDeclSpec().getTypeSpecType()) {
-      case DeclSpec::TST_auto: Keyword = 0; break;
-      case DeclSpec::TST_decltype_auto: Keyword = 1; break;
-      case DeclSpec::TST_auto_type: Keyword = 2; break;
-      default: llvm_unreachable("unknown auto TypeSpecType");
+      unsigned Kind;
+      if (Auto) {
+        switch (Auto->getKeyword()) {
+        case AutoTypeKeyword::Auto: Kind = 0; break;
+        case AutoTypeKeyword::DecltypeAuto: Kind = 1; break;
+        case AutoTypeKeyword::GNUAutoType: Kind = 2; break;
+        }
+      } else {
+        assert(isa<DeducedTemplateSpecializationType>(Deduced) &&
+               "unknown auto type");
+        Kind = 3;
       }
+
+      auto *DTST = dyn_cast<DeducedTemplateSpecializationType>(Deduced);
+      TemplateName TN = DTST ? DTST->getTemplateName() : TemplateName();
+
       SemaRef.Diag(AutoRange.getBegin(), diag::err_auto_not_allowed)
-        << Keyword << Error << AutoRange;
+        << Kind << Error << (int)SemaRef.getTemplateNameKindForDiagnostics(TN)
+        << QualType(Deduced, 0) << AutoRange;
+      if (auto *TD = TN.getAsTemplateDecl())
+        SemaRef.Diag(TD->getLocation(), diag::note_template_decl_here);
+
       T = SemaRef.Context.IntTy;
       D.setInvalidType(true);
     } else if (!HaveTrailing) {
@@ -2942,6 +2962,7 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
       DiagID = diag::err_type_defined_in_alias_template;
       break;
     case Declarator::TypeNameContext:
+    case Declarator::FunctionalCastContext:
     case Declarator::ConversionIdContext:
     case Declarator::TemplateParamContext:
     case Declarator::CXXNewContext:
@@ -3623,17 +3644,32 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
 
   // If T is 'decltype(auto)', the only declarators we can have are parens
   // and at most one function declarator if this is a function declaration.
-  if (const AutoType *AT = T->getAs<AutoType>()) {
-    if (AT->isDecltypeAuto()) {
+  // If T is a deduced class template specialization type, we can have no
+  // declarator chunks at all.
+  if (auto *DT = T->getAs<DeducedType>()) {
+    const AutoType *AT = T->getAs<AutoType>();
+    bool IsClassTemplateDeduction = isa<DeducedTemplateSpecializationType>(DT);
+    if ((AT && AT->isDecltypeAuto()) || IsClassTemplateDeduction) {
       for (unsigned I = 0, E = D.getNumTypeObjects(); I != E; ++I) {
         unsigned Index = E - I - 1;
         DeclaratorChunk &DeclChunk = D.getTypeObject(Index);
-        unsigned DiagId = diag::err_decltype_auto_compound_type;
+        unsigned DiagId = IsClassTemplateDeduction
+                              ? diag::err_deduced_class_template_compound_type
+                              : diag::err_decltype_auto_compound_type;
         unsigned DiagKind = 0;
         switch (DeclChunk.Kind) {
         case DeclaratorChunk::Paren:
+          // FIXME: Rejecting this is a little silly.
+          if (IsClassTemplateDeduction) {
+            DiagKind = 4;
+            break;
+          }
           continue;
         case DeclaratorChunk::Function: {
+          if (IsClassTemplateDeduction) {
+            DiagKind = 3;
+            break;
+          }
           unsigned FnIndex;
           if (D.isFunctionDeclarationContext() &&
               D.isFunctionDeclarator(FnIndex) && FnIndex == Index)
@@ -3834,6 +3870,7 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
     case Declarator::TemplateParamContext:
     case Declarator::TemplateTypeArgContext:
     case Declarator::TypeNameContext:
+    case Declarator::FunctionalCastContext:
       // Don't infer in these contexts.
       break;
     }
@@ -3922,7 +3959,7 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
 
   // If the type itself could have nullability but does not, infer pointer
   // nullability and perform consistency checking.
-  if (S.ActiveTemplateInstantiations.empty()) {
+  if (S.CodeSynthesisContexts.empty()) {
     if (T->canHaveNullability() && !T->getNullability(S.Context)) {
       if (isVaList(T)) {
         // Record that we've seen a pointer, but do nothing else.
@@ -4123,7 +4160,7 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
       if (!D.isInvalidType()) {
         // trailing-return-type is only required if we're declaring a function,
         // and not, for instance, a pointer to a function.
-        if (D.getDeclSpec().containsPlaceholderType() &&
+        if (D.getDeclSpec().hasAutoTypeSpec() &&
             !FTI.hasTrailingReturnType() && chunkIndex == 0 &&
             !S.getLangOpts().CPlusPlus14) {
           S.Diag(D.getDeclSpec().getTypeSpecTypeLoc(),
@@ -4135,16 +4172,25 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
         } else if (FTI.hasTrailingReturnType()) {
           // T must be exactly 'auto' at this point. See CWG issue 681.
           if (isa<ParenType>(T)) {
-            S.Diag(D.getDeclSpec().getTypeSpecTypeLoc(),
+            S.Diag(D.getLocStart(),
                  diag::err_trailing_return_in_parens)
-              << T << D.getDeclSpec().getSourceRange();
+              << T << D.getSourceRange();
             D.setInvalidType(true);
+          } else if (D.getName().getKind() ==
+                         UnqualifiedId::IK_DeductionGuideName) {
+            if (T != Context.DependentTy) {
+              S.Diag(D.getDeclSpec().getLocStart(),
+                     diag::err_deduction_guide_with_complex_decl)
+                  << D.getSourceRange();
+              D.setInvalidType(true);
+            }
           } else if (D.getContext() != Declarator::LambdaExprContext &&
                      (T.hasQualifiers() || !isa<AutoType>(T) ||
-                      cast<AutoType>(T)->getKeyword() != AutoTypeKeyword::Auto)) {
+                      cast<AutoType>(T)->getKeyword() !=
+                          AutoTypeKeyword::Auto)) {
             S.Diag(D.getDeclSpec().getTypeSpecTypeLoc(),
-                 diag::err_trailing_return_without_auto)
-              << T << D.getDeclSpec().getSourceRange();
+                   diag::err_trailing_return_without_auto)
+                << T << D.getDeclSpec().getSourceRange();
             D.setInvalidType(true);
           }
           T = S.GetTypeFromParser(FTI.getTrailingReturnType(), &TInfo);
@@ -4158,7 +4204,7 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
 
       // C99 6.7.5.3p1: The return type may not be a function or array type.
       // For conversion functions, we'll diagnose this particular error later.
-      if ((T->isArrayType() || T->isFunctionType()) &&
+      if (!D.isInvalidType() && (T->isArrayType() || T->isFunctionType()) &&
           (D.getName().getKind() != UnqualifiedId::IK_ConversionFunctionId)) {
         unsigned diagID = diag::err_func_returning_array_function;
         // Last processing chunk in block context means this function chunk
@@ -4442,6 +4488,11 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
             HasAnyInterestingExtParameterInfos = true;
           }
 
+          if (Param->hasAttr<PassObjectSizeAttr>()) {
+            ExtParameterInfos[i] = ExtParameterInfos[i].withHasPassObjectSize();
+            HasAnyInterestingExtParameterInfos = true;
+          }
+
           ParamTys.push_back(ParamTy);
         }
 
@@ -4574,14 +4625,18 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
     //
     // Core issue 547 also allows cv-qualifiers on function types that are
     // top-level template type arguments.
-    bool FreeFunction;
-    if (!D.getCXXScopeSpec().isSet()) {
-      FreeFunction = ((D.getContext() != Declarator::MemberContext &&
-                       D.getContext() != Declarator::LambdaExprContext) ||
-                      D.getDeclSpec().isFriendSpecified());
+    enum { NonMember, Member, DeductionGuide } Kind = NonMember;
+    if (D.getName().getKind() == UnqualifiedId::IK_DeductionGuideName)
+      Kind = DeductionGuide;
+    else if (!D.getCXXScopeSpec().isSet()) {
+      if ((D.getContext() == Declarator::MemberContext ||
+           D.getContext() == Declarator::LambdaExprContext) &&
+          !D.getDeclSpec().isFriendSpecified())
+        Kind = Member;
     } else {
       DeclContext *DC = S.computeDeclContext(D.getCXXScopeSpec());
-      FreeFunction = (DC && !DC->isRecord());
+      if (!DC || DC->isRecord())
+        Kind = Member;
     }
 
     // C++11 [dcl.fct]p6 (w/DR1417):
@@ -4601,7 +4656,7 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
     //
     // ... for instance.
     if (IsQualifiedFunction &&
-        !(!FreeFunction &&
+        !(Kind == Member &&
           D.getDeclSpec().getStorageClassSpec() != DeclSpec::SCS_static) &&
         !IsTypedefName &&
         D.getContext() != Declarator::TemplateTypeArgContext) {
@@ -4629,7 +4684,7 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
       }
 
       S.Diag(Loc, diag::err_invalid_qualified_function_type)
-        << FreeFunction << D.isFunctionDeclarator() << T
+        << Kind << D.isFunctionDeclarator() << T
         << getFunctionQualifiersAsString(FnTy)
         << FixItHint::CreateRemoval(RemovalRange);
 
@@ -4713,6 +4768,7 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
     case Declarator::ObjCParameterContext:  // FIXME: special diagnostic here?
     case Declarator::ObjCResultContext:     // FIXME: special diagnostic here?
     case Declarator::TypeNameContext:
+    case Declarator::FunctionalCastContext:
     case Declarator::CXXNewContext:
     case Declarator::AliasDeclContext:
     case Declarator::AliasTemplateContext:
@@ -5473,14 +5529,14 @@ static void HandleAddressSpaceTypeAttribute(QualType &Type,
       addrSpace.setIsSigned(false);
     }
     llvm::APSInt max(addrSpace.getBitWidth());
-    max = Qualifiers::MaxAddressSpace;
+    max = Qualifiers::MaxAddressSpace - LangAS::Count;
     if (addrSpace > max) {
       S.Diag(Attr.getLoc(), diag::err_attribute_address_space_too_high)
-        << int(Qualifiers::MaxAddressSpace) << ASArgExpr->getSourceRange();
+        << (unsigned)max.getZExtValue() << ASArgExpr->getSourceRange();
       Attr.setInvalid();
       return;
     }
-    ASIdx = static_cast<unsigned>(addrSpace.getZExtValue());
+    ASIdx = static_cast<unsigned>(addrSpace.getZExtValue()) + LangAS::Count;
   } else {
     // The keyword-based type attributes imply which address space to use.
     switch (Attr.getKind()) {
@@ -6893,8 +6949,10 @@ static void processTypeAttrs(TypeProcessingState &state, QualType &type,
       (TAL == TAL_DeclSpec || TAL == TAL_DeclChunk)) {
     Declarator &D = state.getDeclarator();
     if (state.getCurrentChunkIndex() > 0 &&
-        D.getTypeObject(state.getCurrentChunkIndex() - 1).Kind ==
-            DeclaratorChunk::Pointer) {
+        (D.getTypeObject(state.getCurrentChunkIndex() - 1).Kind ==
+             DeclaratorChunk::Pointer ||
+         D.getTypeObject(state.getCurrentChunkIndex() - 1).Kind ==
+             DeclaratorChunk::BlockPointer)) {
       type = state.getSema().Context.getAddrSpaceQualType(
           type, LangAS::opencl_generic);
     } else if (state.getCurrentChunkIndex() == 0 &&
@@ -7510,7 +7568,7 @@ QualType Sema::BuildDecltypeType(Expr *E, SourceLocation Loc,
   if (ER.isInvalid()) return QualType();
   E = ER.get();
 
-  if (AsUnevaluated && ActiveTemplateInstantiations.empty() &&
+  if (AsUnevaluated && CodeSynthesisContexts.empty() &&
       E->HasSideEffects(Context, false)) {
     // The expression operand for decltype is in an unevaluated expression
     // context, so side effects could result in unintended consequences.
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index f8e65a119c3c..693b5c088acc 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -14,6 +14,7 @@
 #ifndef LLVM_CLANG_LIB_SEMA_TREETRANSFORM_H
 #define LLVM_CLANG_LIB_SEMA_TREETRANSFORM_H
 
+#include "CoroutineStmtBuilder.h"
 #include "TypeLocBuilder.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclObjC.h"
@@ -307,6 +308,17 @@ public:
   ///
   QualType TransformType(TypeLocBuilder &TLB, TypeLoc TL);
 
+  /// \brief Transform a type that is permitted to produce a
+  /// DeducedTemplateSpecializationType.
+  ///
+  /// This is used in the (relatively rare) contexts where it is acceptable
+  /// for transformation to produce a class template type with deduced
+  /// template arguments.
+  /// @{
+  QualType TransformTypeWithDeducedTST(QualType T);
+  TypeSourceInfo *TransformTypeWithDeducedTST(TypeSourceInfo *DI);
+  /// @}
+
   /// \brief Transform the given statement.
   ///
   /// By default, this routine transforms a statement by delegating to the
@@ -505,7 +517,8 @@ public:
   TransformTemplateName(CXXScopeSpec &SS, TemplateName Name,
                         SourceLocation NameLoc,
                         QualType ObjectType = QualType(),
-                        NamedDecl *FirstQualifierInScope = nullptr);
+                        NamedDecl *FirstQualifierInScope = nullptr,
+                        bool AllowInjectedClassName = false);
 
   /// \brief Transform the given template argument.
   ///
@@ -671,6 +684,16 @@ public:
   OMPClause *Transform ## Class(Class *S);
 #include "clang/Basic/OpenMPKinds.def"
 
+  /// \brief Build a new qualified type given its unqualified type and type
+  /// qualifiers.
+  ///
+  /// By default, this routine adds type qualifiers only to types that can
+  /// have qualifiers, and silently suppresses those qualifiers that are not
+  /// permitted. Subclasses may override this routine to provide different
+  /// behavior.
+  QualType RebuildQualifiedType(QualType T, SourceLocation Loc,
+                                Qualifiers Quals);
+
   /// \brief Build a new pointer type given its pointee type.
   ///
   /// By default, performs semantic analysis when building the pointer type.
@@ -875,6 +898,14 @@ public:
                                        /*IsDependent*/ false);
   }
 
+  /// By default, builds a new DeducedTemplateSpecializationType with the given
+  /// deduced type.
+  QualType RebuildDeducedTemplateSpecializationType(TemplateName Template,
+      QualType Deduced) {
+    return SemaRef.Context.getDeducedTemplateSpecializationType(
+        Template, Deduced, /*IsDependent*/ false);
+  }
+
   /// \brief Build a new template specialization type.
   ///
   /// By default, performs semantic analysis when building the template
@@ -889,7 +920,7 @@ public:
   /// By default, builds a new ParenType type from the inner type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildParenType(QualType InnerType) {
-    return SemaRef.Context.getParenType(InnerType);
+    return SemaRef.BuildParenType(InnerType);
   }
 
   /// \brief Build a new qualified name type.
@@ -916,14 +947,15 @@ public:
                                           NestedNameSpecifierLoc QualifierLoc,
                                           const IdentifierInfo *Name,
                                           SourceLocation NameLoc,
-                                          TemplateArgumentListInfo &Args) {
+                                          TemplateArgumentListInfo &Args,
+                                          bool AllowInjectedClassName) {
     // Rebuild the template name.
     // TODO: avoid TemplateName abstraction
     CXXScopeSpec SS;
     SS.Adopt(QualifierLoc);
     TemplateName InstName
       = getDerived().RebuildTemplateName(SS, *Name, NameLoc, QualType(),
-                                         nullptr);
+                                         nullptr, AllowInjectedClassName);
 
     if (InstName.isNull())
       return QualType();
@@ -958,7 +990,8 @@ public:
                                     SourceLocation KeywordLoc,
                                     NestedNameSpecifierLoc QualifierLoc,
                                     const IdentifierInfo *Id,
-                                    SourceLocation IdLoc) {
+                                    SourceLocation IdLoc,
+                                    bool DeducedTSTContext) {
     CXXScopeSpec SS;
     SS.Adopt(QualifierLoc);
 
@@ -970,9 +1003,25 @@ public:
                                                     Id);
     }
 
-    if (Keyword == ETK_None || Keyword == ETK_Typename)
-      return SemaRef.CheckTypenameType(Keyword, KeywordLoc, QualifierLoc,
-                                       *Id, IdLoc);
+    if (Keyword == ETK_None || Keyword == ETK_Typename) {
+      QualType T = SemaRef.CheckTypenameType(Keyword, KeywordLoc, QualifierLoc,
+                                             *Id, IdLoc);
+      // If a dependent name resolves to a deduced template specialization type,
+      // check that we're in one of the syntactic contexts permitting it.
+      if (!DeducedTSTContext) {
+        if (auto *Deduced = dyn_cast_or_null<DeducedTemplateSpecializationType>(
+                T.isNull() ? nullptr : T->getContainedDeducedType())) {
+          SemaRef.Diag(IdLoc, diag::err_dependent_deduced_tst)
+            << (int)SemaRef.getTemplateNameKindForDiagnostics(
+                   Deduced->getTemplateName())
+            << QualType(QualifierLoc.getNestedNameSpecifier()->getAsType(), 0);
+          if (auto *TD = Deduced->getTemplateName().getAsTemplateDecl())
+            SemaRef.Diag(TD->getLocation(), diag::note_template_decl_here);
+          return QualType();
+        }
+      }
+      return T;
+    }
 
     TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForKeyword(Keyword);
 
@@ -1088,7 +1137,8 @@ public:
                                    const IdentifierInfo &Name,
                                    SourceLocation NameLoc,
                                    QualType ObjectType,
-                                   NamedDecl *FirstQualifierInScope);
+                                   NamedDecl *FirstQualifierInScope,
+                                   bool AllowInjectedClassName);
 
   /// \brief Build a new template name given a nested name specifier and the
   /// overloaded operator name that is referred to as a template.
@@ -1100,7 +1150,8 @@ public:
   TemplateName RebuildTemplateName(CXXScopeSpec &SS,
                                    OverloadedOperatorKind Operator,
                                    SourceLocation NameLoc,
-                                   QualType ObjectType);
+                                   QualType ObjectType,
+                                   bool AllowInjectedClassName);
 
   /// \brief Build a new template name given a template template parameter pack
   /// and the
@@ -1312,16 +1363,28 @@ public:
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
-  StmtResult RebuildCoreturnStmt(SourceLocation CoreturnLoc, Expr *Result) {
-    return getSema().BuildCoreturnStmt(CoreturnLoc, Result);
+  StmtResult RebuildCoreturnStmt(SourceLocation CoreturnLoc, Expr *Result,
+                                 bool IsImplicit) {
+    return getSema().BuildCoreturnStmt(CoreturnLoc, Result, IsImplicit);
+  }
+
+  /// \brief Build a new co_await expression.
+  ///
+  /// By default, performs semantic analysis to build the new expression.
+  /// Subclasses may override this routine to provide different behavior.
+  ExprResult RebuildCoawaitExpr(SourceLocation CoawaitLoc, Expr *Result,
+                                bool IsImplicit) {
+    return getSema().BuildResolvedCoawaitExpr(CoawaitLoc, Result, IsImplicit);
   }
 
   /// \brief Build a new co_await expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
-  ExprResult RebuildCoawaitExpr(SourceLocation CoawaitLoc, Expr *Result) {
-    return getSema().BuildCoawaitExpr(CoawaitLoc, Result);
+  ExprResult RebuildDependentCoawaitExpr(SourceLocation CoawaitLoc,
+                                         Expr *Result,
+                                         UnresolvedLookupExpr *Lookup) {
+    return getSema().BuildUnresolvedCoawaitExpr(CoawaitLoc, Result, Lookup);
   }
 
   /// \brief Build a new co_yield expression.
@@ -1332,6 +1395,10 @@ public:
     return getSema().BuildCoyieldExpr(CoyieldLoc, Result);
   }
 
+  StmtResult RebuildCoroutineBodyStmt(CoroutineBodyStmt::CtorArgs Args) {
+    return getSema().BuildCoroutineBodyStmt(Args);
+  }
+
   /// \brief Build a new Objective-C \@try statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
@@ -3146,6 +3213,10 @@ private:
   TypeSourceInfo *TransformTSIInObjectScope(TypeLoc TL, QualType ObjectType,
                                             NamedDecl *FirstQualifierInScope,
                                             CXXScopeSpec &SS);
+
+  QualType TransformDependentNameType(TypeLocBuilder &TLB,
+                                      DependentNameTypeLoc TL,
+                                      bool DeducibleTSTContext);
 };
 
 template<typename Derived>
@@ -3563,6 +3634,19 @@ TreeTransform<Derived>
   case DeclarationName::CXXUsingDirective:
     return NameInfo;
 
+  case DeclarationName::CXXDeductionGuideName: {
+    TemplateDecl *OldTemplate = Name.getCXXDeductionGuideTemplate();
+    TemplateDecl *NewTemplate = cast_or_null<TemplateDecl>(
+        getDerived().TransformDecl(NameInfo.getLoc(), OldTemplate));
+    if (!NewTemplate)
+      return DeclarationNameInfo();
+
+    DeclarationNameInfo NewNameInfo(NameInfo);
+    NewNameInfo.setName(
+        SemaRef.Context.DeclarationNames.getCXXDeductionGuideName(NewTemplate));
+    return NewNameInfo;
+  }
+
   case DeclarationName::CXXConstructorName:
   case DeclarationName::CXXDestructorName:
   case DeclarationName::CXXConversionFunctionName: {
@@ -3602,7 +3686,8 @@ TreeTransform<Derived>::TransformTemplateName(CXXScopeSpec &SS,
                                               TemplateName Name,
                                               SourceLocation NameLoc,
                                               QualType ObjectType,
-                                              NamedDecl *FirstQualifierInScope) {
+                                              NamedDecl *FirstQualifierInScope,
+                                              bool AllowInjectedClassName) {
   if (QualifiedTemplateName *QTN = Name.getAsQualifiedTemplateName()) {
     TemplateDecl *Template = QTN->getTemplateDecl();
     assert(Template && "qualified template name must refer to a template");
@@ -3639,11 +3724,12 @@ TreeTransform<Derived>::TransformTemplateName(CXXScopeSpec &SS,
                                               *DTN->getIdentifier(),
                                               NameLoc,
                                               ObjectType,
-                                              FirstQualifierInScope);
+                                              FirstQualifierInScope,
+                                              AllowInjectedClassName);
     }
 
     return getDerived().RebuildTemplateName(SS, DTN->getOperator(), NameLoc,
-                                            ObjectType);
+                                            ObjectType, AllowInjectedClassName);
   }
 
   if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
@@ -3782,7 +3868,9 @@ bool TreeTransform<Derived>::TransformTemplateArgument(
   case TemplateArgument::Expression: {
     // Template argument expressions are constant expressions.
     EnterExpressionEvaluationContext Unevaluated(
-        getSema(), Uneval ? Sema::Unevaluated : Sema::ConstantEvaluated);
+        getSema(), Uneval
+                       ? Sema::ExpressionEvaluationContext::Unevaluated
+                       : Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
     Expr *InputExpr = Input.getSourceExpression();
     if (!InputExpr) InputExpr = Input.getArgument().getAsExpr();
@@ -4035,11 +4123,57 @@ TreeTransform<Derived>::TransformType(TypeLocBuilder &TLB, TypeLoc T) {
   llvm_unreachable("unhandled type loc!");
 }
 
-/// FIXME: By default, this routine adds type qualifiers only to types
-/// that can have qualifiers, and silently suppresses those qualifiers
-/// that are not permitted (e.g., qualifiers on reference or function
-/// types). This is the right thing for template instantiation, but
-/// probably not for other clients.
+template<typename Derived>
+QualType TreeTransform<Derived>::TransformTypeWithDeducedTST(QualType T) {
+  if (!isa<DependentNameType>(T))
+    return TransformType(T);
+
+  if (getDerived().AlreadyTransformed(T))
+    return T;
+  TypeSourceInfo *DI = getSema().Context.getTrivialTypeSourceInfo(T,
+                                                getDerived().getBaseLocation());
+  TypeSourceInfo *NewDI = getDerived().TransformTypeWithDeducedTST(DI);
+  return NewDI ? NewDI->getType() : QualType();
+}
+
+template<typename Derived>
+TypeSourceInfo *
+TreeTransform<Derived>::TransformTypeWithDeducedTST(TypeSourceInfo *DI) {
+  if (!isa<DependentNameType>(DI->getType()))
+    return TransformType(DI);
+
+  // Refine the base location to the type's location.
+  TemporaryBase Rebase(*this, DI->getTypeLoc().getBeginLoc(),
+                       getDerived().getBaseEntity());
+  if (getDerived().AlreadyTransformed(DI->getType()))
+    return DI;
+
+  TypeLocBuilder TLB;
+
+  TypeLoc TL = DI->getTypeLoc();
+  TLB.reserve(TL.getFullDataSize());
+
+  Qualifiers Quals;
+  auto QTL = TL.getAs<QualifiedTypeLoc>();
+  if (QTL)
+    TL = QTL.getUnqualifiedLoc();
+
+  auto DNTL = TL.castAs<DependentNameTypeLoc>();
+
+  QualType Result = getDerived().TransformDependentNameType(
+      TLB, DNTL, /*DeducedTSTContext*/true);
+  if (Result.isNull())
+    return nullptr;
+
+  if (QTL) {
+    Result = getDerived().RebuildQualifiedType(
+        Result, QTL.getBeginLoc(), QTL.getType().getLocalQualifiers());
+    TLB.TypeWasModifiedSafely(Result);
+  }
+
+  return TLB.getTypeSourceInfo(SemaRef.Context, Result);
+}
+
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformQualifiedType(TypeLocBuilder &TLB,
@@ -4050,64 +4184,71 @@ TreeTransform<Derived>::TransformQualifiedType(TypeLocBuilder &TLB,
   if (Result.isNull())
     return QualType();
 
-  // Silently suppress qualifiers if the result type can't be qualified.
-  // FIXME: this is the right thing for template instantiation, but
-  // probably not for other clients.
-  if (Result->isFunctionType() || Result->isReferenceType())
-    return Result;
+  Result = getDerived().RebuildQualifiedType(Result, T.getBeginLoc(), Quals);
+
+  // RebuildQualifiedType might have updated the type, but not in a way
+  // that invalidates the TypeLoc. (There's no location information for
+  // qualifiers.)
+  TLB.TypeWasModifiedSafely(Result);
+
+  return Result;
+}
+
+template<typename Derived>
+QualType TreeTransform<Derived>::RebuildQualifiedType(QualType T,
+                                                      SourceLocation Loc,
+                                                      Qualifiers Quals) {
+  // C++ [dcl.fct]p7:
+  //   [When] adding cv-qualifications on top of the function type [...] the
+  //   cv-qualifiers are ignored.
+  // C++ [dcl.ref]p1:
+  //   when the cv-qualifiers are introduced through the use of a typedef-name
+  //   or decltype-specifier [...] the cv-qualifiers are ignored.
+  // Note that [dcl.ref]p1 lists all cases in which cv-qualifiers can be
+  // applied to a reference type.
+  // FIXME: This removes all qualifiers, not just cv-qualifiers!
+  if (T->isFunctionType() || T->isReferenceType())
+    return T;
 
   // Suppress Objective-C lifetime qualifiers if they don't make sense for the
   // resulting type.
   if (Quals.hasObjCLifetime()) {
-    if (!Result->isObjCLifetimeType() && !Result->isDependentType())
+    if (!T->isObjCLifetimeType() && !T->isDependentType())
       Quals.removeObjCLifetime();
-    else if (Result.getObjCLifetime()) {
+    else if (T.getObjCLifetime()) {
       // Objective-C ARC:
       //   A lifetime qualifier applied to a substituted template parameter
       //   overrides the lifetime qualifier from the template argument.
       const AutoType *AutoTy;
       if (const SubstTemplateTypeParmType *SubstTypeParam
-                                = dyn_cast<SubstTemplateTypeParmType>(Result)) {
+                                = dyn_cast<SubstTemplateTypeParmType>(T)) {
         QualType Replacement = SubstTypeParam->getReplacementType();
         Qualifiers Qs = Replacement.getQualifiers();
         Qs.removeObjCLifetime();
-        Replacement
-          = SemaRef.Context.getQualifiedType(Replacement.getUnqualifiedType(),
-                                             Qs);
-        Result = SemaRef.Context.getSubstTemplateTypeParmType(
-                                        SubstTypeParam->getReplacedParameter(),
-                                                              Replacement);
-        TLB.TypeWasModifiedSafely(Result);
-      } else if ((AutoTy = dyn_cast<AutoType>(Result)) && AutoTy->isDeduced()) {
+        Replacement = SemaRef.Context.getQualifiedType(
+            Replacement.getUnqualifiedType(), Qs);
+        T = SemaRef.Context.getSubstTemplateTypeParmType(
+            SubstTypeParam->getReplacedParameter(), Replacement);
+      } else if ((AutoTy = dyn_cast<AutoType>(T)) && AutoTy->isDeduced()) {
         // 'auto' types behave the same way as template parameters.
         QualType Deduced = AutoTy->getDeducedType();
         Qualifiers Qs = Deduced.getQualifiers();
         Qs.removeObjCLifetime();
-        Deduced = SemaRef.Context.getQualifiedType(Deduced.getUnqualifiedType(),
-                                                   Qs);
-        Result = SemaRef.Context.getAutoType(Deduced, AutoTy->getKeyword(),
-                                AutoTy->isDependentType());
-        TLB.TypeWasModifiedSafely(Result);
+        Deduced =
+            SemaRef.Context.getQualifiedType(Deduced.getUnqualifiedType(), Qs);
+        T = SemaRef.Context.getAutoType(Deduced, AutoTy->getKeyword(),
+                                        AutoTy->isDependentType());
       } else {
         // Otherwise, complain about the addition of a qualifier to an
         // already-qualified type.
-        SourceRange R = T.getUnqualifiedLoc().getSourceRange();
-        SemaRef.Diag(R.getBegin(), diag::err_attr_objc_ownership_redundant)
-          << Result << R;
-
+        // FIXME: Why is this check not in Sema::BuildQualifiedType?
+        SemaRef.Diag(Loc, diag::err_attr_objc_ownership_redundant) << T;
         Quals.removeObjCLifetime();
       }
     }
   }
-  if (!Quals.empty()) {
-    Result = SemaRef.BuildQualifiedType(Result, T.getBeginLoc(), Quals);
-    // BuildQualifiedType might not add qualifiers if they are invalid.
-    if (Result.hasLocalQualifiers())
-      TLB.push<QualifiedTypeLoc>(Result);
-    // No location information to preserve.
-  }
 
-  return Result;
+  return SemaRef.BuildQualifiedType(T, Loc, Quals);
 }
 
 template<typename Derived>
@@ -4153,11 +4294,9 @@ TypeSourceInfo *TreeTransform<Derived>::TransformTSIInObjectScope(
     TemplateSpecializationTypeLoc SpecTL =
         TL.castAs<TemplateSpecializationTypeLoc>();
 
-    TemplateName Template
-    = getDerived().TransformTemplateName(SS,
-                                         SpecTL.getTypePtr()->getTemplateName(),
-                                         SpecTL.getTemplateNameLoc(),
-                                         ObjectType, UnqualLookup);
+    TemplateName Template = getDerived().TransformTemplateName(
+        SS, SpecTL.getTypePtr()->getTemplateName(), SpecTL.getTemplateNameLoc(),
+        ObjectType, UnqualLookup, /*AllowInjectedClassName*/true);
     if (Template.isNull())
       return nullptr;
 
@@ -4171,7 +4310,8 @@ TypeSourceInfo *TreeTransform<Derived>::TransformTSIInObjectScope(
       = getDerived().RebuildTemplateName(SS,
                                          *SpecTL.getTypePtr()->getIdentifier(),
                                          SpecTL.getTemplateNameLoc(),
-                                         ObjectType, UnqualLookup);
+                                         ObjectType, UnqualLookup,
+                                         /*AllowInjectedClassName*/true);
     if (Template.isNull())
       return nullptr;
 
@@ -4435,8 +4575,8 @@ TreeTransform<Derived>::TransformConstantArrayType(TypeLocBuilder &TLB,
 
   Expr *Size = TL.getSizeExpr();
   if (Size) {
-    EnterExpressionEvaluationContext Unevaluated(SemaRef,
-                                                 Sema::ConstantEvaluated);
+    EnterExpressionEvaluationContext Unevaluated(
+        SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
     Size = getDerived().TransformExpr(Size).template getAs<Expr>();
     Size = SemaRef.ActOnConstantExpression(Size).get();
   }
@@ -4482,8 +4622,15 @@ TreeTransform<Derived>::TransformVariableArrayType(TypeLocBuilder &TLB,
   if (ElementType.isNull())
     return QualType();
 
-  ExprResult SizeResult
-    = getDerived().TransformExpr(T->getSizeExpr());
+  ExprResult SizeResult;
+  {
+    EnterExpressionEvaluationContext Context(
+        SemaRef, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
+    SizeResult = getDerived().TransformExpr(T->getSizeExpr());
+  }
+  if (SizeResult.isInvalid())
+    return QualType();
+  SizeResult = SemaRef.ActOnFinishFullExpr(SizeResult.get());
   if (SizeResult.isInvalid())
     return QualType();
 
@@ -4522,8 +4669,8 @@ TreeTransform<Derived>::TransformDependentSizedArrayType(TypeLocBuilder &TLB,
     return QualType();
 
   // Array bounds are constant expressions.
-  EnterExpressionEvaluationContext Unevaluated(SemaRef,
-                                               Sema::ConstantEvaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   // Prefer the expression from the TypeLoc;  the other may have been uniqued.
   Expr *origSize = TL.getSizeExpr();
@@ -4572,8 +4719,8 @@ QualType TreeTransform<Derived>::TransformDependentSizedExtVectorType(
     return QualType();
 
   // Vector sizes are constant expressions.
-  EnterExpressionEvaluationContext Unevaluated(SemaRef,
-                                               Sema::ConstantEvaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   ExprResult Size = getDerived().TransformExpr(T->getSizeExpr());
   Size = SemaRef.ActOnConstantExpression(Size);
@@ -5040,8 +5187,8 @@ bool TreeTransform<Derived>::TransformExceptionSpec(
 
   // Instantiate a dynamic noexcept expression, if any.
   if (ESI.Type == EST_ComputedNoexcept) {
-    EnterExpressionEvaluationContext Unevaluated(getSema(),
-                                                 Sema::ConstantEvaluated);
+    EnterExpressionEvaluationContext Unevaluated(
+        getSema(), Sema::ExpressionEvaluationContext::ConstantEvaluated);
     ExprResult NoexceptExpr = getDerived().TransformExpr(ESI.NoexceptExpr);
     if (NoexceptExpr.isInvalid())
       return true;
@@ -5208,8 +5355,9 @@ template<typename Derived>
 QualType TreeTransform<Derived>::TransformTypeOfExprType(TypeLocBuilder &TLB,
                                                       TypeOfExprTypeLoc TL) {
   // typeof expressions are not potentially evaluated contexts
-  EnterExpressionEvaluationContext Unevaluated(SemaRef, Sema::Unevaluated,
-                                               Sema::ReuseLambdaContextDecl);
+  EnterExpressionEvaluationContext Unevaluated(
+      SemaRef, Sema::ExpressionEvaluationContext::Unevaluated,
+      Sema::ReuseLambdaContextDecl);
 
   ExprResult E = getDerived().TransformExpr(TL.getUnderlyingExpr());
   if (E.isInvalid())
@@ -5266,8 +5414,9 @@ QualType TreeTransform<Derived>::TransformDecltypeType(TypeLocBuilder &TLB,
   const DecltypeType *T = TL.getTypePtr();
 
   // decltype expressions are not potentially evaluated contexts
-  EnterExpressionEvaluationContext Unevaluated(SemaRef, Sema::Unevaluated,
-                                               nullptr, /*IsDecltype=*/ true);
+  EnterExpressionEvaluationContext Unevaluated(
+      SemaRef, Sema::ExpressionEvaluationContext::Unevaluated, nullptr,
+      /*IsDecltype=*/true);
 
   ExprResult E = getDerived().TransformExpr(T->getUnderlyingExpr());
   if (E.isInvalid())
@@ -5342,6 +5491,37 @@ QualType TreeTransform<Derived>::TransformAutoType(TypeLocBuilder &TLB,
 }
 
 template<typename Derived>
+QualType TreeTransform<Derived>::TransformDeducedTemplateSpecializationType(
+    TypeLocBuilder &TLB, DeducedTemplateSpecializationTypeLoc TL) {
+  const DeducedTemplateSpecializationType *T = TL.getTypePtr();
+
+  CXXScopeSpec SS;
+  TemplateName TemplateName = getDerived().TransformTemplateName(
+      SS, T->getTemplateName(), TL.getTemplateNameLoc());
+  if (TemplateName.isNull())
+    return QualType();
+
+  QualType OldDeduced = T->getDeducedType();
+  QualType NewDeduced;
+  if (!OldDeduced.isNull()) {
+    NewDeduced = getDerived().TransformType(OldDeduced);
+    if (NewDeduced.isNull())
+      return QualType();
+  }
+
+  QualType Result = getDerived().RebuildDeducedTemplateSpecializationType(
+      TemplateName, NewDeduced);
+  if (Result.isNull())
+    return QualType();
+
+  DeducedTemplateSpecializationTypeLoc NewTL =
+      TLB.push<DeducedTemplateSpecializationTypeLoc>(Result);
+  NewTL.setTemplateNameLoc(TL.getTemplateNameLoc());
+
+  return Result;
+}
+
+template<typename Derived>
 QualType TreeTransform<Derived>::TransformRecordType(TypeLocBuilder &TLB,
                                                      RecordTypeLoc TL) {
   const RecordType *T = TL.getTypePtr();
@@ -5811,8 +5991,14 @@ TreeTransform<Derived>::TransformParenType(TypeLocBuilder &TLB,
 }
 
 template<typename Derived>
-QualType TreeTransform<Derived>::TransformDependentNameType(TypeLocBuilder &TLB,
-                                                      DependentNameTypeLoc TL) {
+QualType TreeTransform<Derived>::TransformDependentNameType(
+    TypeLocBuilder &TLB, DependentNameTypeLoc TL) {
+  return TransformDependentNameType(TLB, TL, false);
+}
+
+template<typename Derived>
+QualType TreeTransform<Derived>::TransformDependentNameType(
+    TypeLocBuilder &TLB, DependentNameTypeLoc TL, bool DeducedTSTContext) {
   const DependentNameType *T = TL.getTypePtr();
 
   NestedNameSpecifierLoc QualifierLoc
@@ -5825,7 +6011,8 @@ QualType TreeTransform<Derived>::TransformDependentNameType(TypeLocBuilder &TLB,
                                             TL.getElaboratedKeywordLoc(),
                                             QualifierLoc,
                                             T->getIdentifier(),
-                                            TL.getNameLoc());
+                                            TL.getNameLoc(),
+                                            DeducedTSTContext);
   if (Result.isNull())
     return QualType();
 
@@ -5879,12 +6066,10 @@ TransformDependentTemplateSpecializationType(TypeLocBuilder &TLB,
                                               NewTemplateArgs))
     return QualType();
 
-  QualType Result
-    = getDerived().RebuildDependentTemplateSpecializationType(T->getKeyword(),
-                                                              QualifierLoc,
-                                                            T->getIdentifier(),
-                                                       TL.getTemplateNameLoc(),
-                                                            NewTemplateArgs);
+  QualType Result = getDerived().RebuildDependentTemplateSpecializationType(
+      T->getKeyword(), QualifierLoc, T->getIdentifier(),
+      TL.getTemplateNameLoc(), NewTemplateArgs,
+      /*AllowInjectedClassName*/ false);
   if (Result.isNull())
     return QualType();
 
@@ -6206,8 +6391,8 @@ StmtResult
 TreeTransform<Derived>::TransformCaseStmt(CaseStmt *S) {
   ExprResult LHS, RHS;
   {
-    EnterExpressionEvaluationContext Unevaluated(SemaRef,
-                                                 Sema::ConstantEvaluated);
+    EnterExpressionEvaluationContext Unevaluated(
+        SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
     // Transform the left-hand case value.
     LHS = getDerived().TransformExpr(S->getLHS());
@@ -6667,9 +6852,99 @@ TreeTransform<Derived>::TransformMSAsmStmt(MSAsmStmt *S) {
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformCoroutineBodyStmt(CoroutineBodyStmt *S) {
-  // The coroutine body should be re-formed by the caller if necessary.
-  // FIXME: The coroutine body is always rebuilt by ActOnFinishFunctionBody
-  return getDerived().TransformStmt(S->getBody());
+  auto *ScopeInfo = SemaRef.getCurFunction();
+  auto *FD = cast<FunctionDecl>(SemaRef.CurContext);
+  assert(FD && ScopeInfo && !ScopeInfo->CoroutinePromise &&
+         ScopeInfo->NeedsCoroutineSuspends &&
+         ScopeInfo->CoroutineSuspends.first == nullptr &&
+         ScopeInfo->CoroutineSuspends.second == nullptr &&
+         "expected clean scope info");
+
+  // Set that we have (possibly-invalid) suspend points before we do anything
+  // that may fail.
+  ScopeInfo->setNeedsCoroutineSuspends(false);
+
+  // The new CoroutinePromise object needs to be built and put into the current
+  // FunctionScopeInfo before any transformations or rebuilding occurs.
+  auto *Promise = SemaRef.buildCoroutinePromise(FD->getLocation());
+  if (!Promise)
+    return StmtError();
+  getDerived().transformedLocalDecl(S->getPromiseDecl(), Promise);
+  ScopeInfo->CoroutinePromise = Promise;
+
+  // Transform the implicit coroutine statements we built during the initial
+  // parse.
+  StmtResult InitSuspend = getDerived().TransformStmt(S->getInitSuspendStmt());
+  if (InitSuspend.isInvalid())
+    return StmtError();
+  StmtResult FinalSuspend =
+      getDerived().TransformStmt(S->getFinalSuspendStmt());
+  if (FinalSuspend.isInvalid())
+    return StmtError();
+  ScopeInfo->setCoroutineSuspends(InitSuspend.get(), FinalSuspend.get());
+  assert(isa<Expr>(InitSuspend.get()) && isa<Expr>(FinalSuspend.get()));
+
+  StmtResult BodyRes = getDerived().TransformStmt(S->getBody());
+  if (BodyRes.isInvalid())
+    return StmtError();
+
+  CoroutineStmtBuilder Builder(SemaRef, *FD, *ScopeInfo, BodyRes.get());
+  if (Builder.isInvalid())
+    return StmtError();
+
+  Expr *ReturnObject = S->getReturnValueInit();
+  assert(ReturnObject && "the return object is expected to be valid");
+  ExprResult Res = getDerived().TransformInitializer(ReturnObject,
+                                                     /*NoCopyInit*/ false);
+  if (Res.isInvalid())
+    return StmtError();
+  Builder.ReturnValue = Res.get();
+
+  if (S->hasDependentPromiseType()) {
+    assert(!Promise->getType()->isDependentType() &&
+           "the promise type must no longer be dependent");
+    assert(!S->getFallthroughHandler() && !S->getExceptionHandler() &&
+           !S->getReturnStmtOnAllocFailure() && !S->getDeallocate() &&
+           "these nodes should not have been built yet");
+    if (!Builder.buildDependentStatements())
+      return StmtError();
+  } else {
+    if (auto *OnFallthrough = S->getFallthroughHandler()) {
+      StmtResult Res = getDerived().TransformStmt(OnFallthrough);
+      if (Res.isInvalid())
+        return StmtError();
+      Builder.OnFallthrough = Res.get();
+    }
+
+    if (auto *OnException = S->getExceptionHandler()) {
+      StmtResult Res = getDerived().TransformStmt(OnException);
+      if (Res.isInvalid())
+        return StmtError();
+      Builder.OnException = Res.get();
+    }
+
+    if (auto *OnAllocFailure = S->getReturnStmtOnAllocFailure()) {
+      StmtResult Res = getDerived().TransformStmt(OnAllocFailure);
+      if (Res.isInvalid())
+        return StmtError();
+      Builder.ReturnStmtOnAllocFailure = Res.get();
+    }
+
+    // Transform any additional statements we may have already built
+    assert(S->getAllocate() && S->getDeallocate() &&
+           "allocation and deallocation calls must already be built");
+    ExprResult AllocRes = getDerived().TransformExpr(S->getAllocate());
+    if (AllocRes.isInvalid())
+      return StmtError();
+    Builder.Allocate = AllocRes.get();
+
+    ExprResult DeallocRes = getDerived().TransformExpr(S->getDeallocate());
+    if (DeallocRes.isInvalid())
+      return StmtError();
+    Builder.Deallocate = DeallocRes.get();
+  }
+
+  return getDerived().RebuildCoroutineBodyStmt(Builder);
 }
 
 template<typename Derived>
@@ -6682,7 +6957,8 @@ TreeTransform<Derived>::TransformCoreturnStmt(CoreturnStmt *S) {
 
   // Always rebuild; we don't know if this needs to be injected into a new
   // context or if the promise type has changed.
-  return getDerived().RebuildCoreturnStmt(S->getKeywordLoc(), Result.get());
+  return getDerived().RebuildCoreturnStmt(S->getKeywordLoc(), Result.get(),
+                                          S->isImplicit());
 }
 
 template<typename Derived>
@@ -6695,7 +6971,29 @@ TreeTransform<Derived>::TransformCoawaitExpr(CoawaitExpr *E) {
 
   // Always rebuild; we don't know if this needs to be injected into a new
   // context or if the promise type has changed.
-  return getDerived().RebuildCoawaitExpr(E->getKeywordLoc(), Result.get());
+  return getDerived().RebuildCoawaitExpr(E->getKeywordLoc(), Result.get(),
+                                         E->isImplicit());
+}
+
+template <typename Derived>
+ExprResult
+TreeTransform<Derived>::TransformDependentCoawaitExpr(DependentCoawaitExpr *E) {
+  ExprResult OperandResult = getDerived().TransformInitializer(E->getOperand(),
+                                                        /*NotCopyInit*/ false);
+  if (OperandResult.isInvalid())
+    return ExprError();
+
+  ExprResult LookupResult = getDerived().TransformUnresolvedLookupExpr(
+          E->getOperatorCoawaitLookup());
+
+  if (LookupResult.isInvalid())
+    return ExprError();
+
+  // Always rebuild; we don't know if this needs to be injected into a new
+  // context or if the promise type has changed.
+  return getDerived().RebuildDependentCoawaitExpr(
+      E->getKeywordLoc(), OperandResult.get(),
+      cast<UnresolvedLookupExpr>(LookupResult.get()));
 }
 
 template<typename Derived>
@@ -7239,8 +7537,12 @@ StmtResult TreeTransform<Derived>::TransformOMPExecutableDirective(
     StmtResult Body;
     {
       Sema::CompoundScopeRAII CompoundScope(getSema());
-      Body = getDerived().TransformStmt(
-          cast<CapturedStmt>(D->getAssociatedStmt())->getCapturedStmt());
+      int ThisCaptureLevel =
+          Sema::getOpenMPCaptureLevels(D->getDirectiveKind());
+      Stmt *CS = D->getAssociatedStmt();
+      while (--ThisCaptureLevel >= 0)
+        CS = cast<CapturedStmt>(CS)->getCapturedStmt();
+      Body = getDerived().TransformStmt(CS);
     }
     AssociatedStmt =
         getDerived().getSema().ActOnOpenMPRegionEnd(Body, TClauses);
@@ -8642,8 +8944,9 @@ TreeTransform<Derived>::TransformUnaryExprOrTypeTraitExpr(
   // C++0x [expr.sizeof]p1:
   //   The operand is either an expression, which is an unevaluated operand
   //   [...]
-  EnterExpressionEvaluationContext Unevaluated(SemaRef, Sema::Unevaluated,
-                                               Sema::ReuseLambdaContextDecl);
+  EnterExpressionEvaluationContext Unevaluated(
+      SemaRef, Sema::ExpressionEvaluationContext::Unevaluated,
+      Sema::ReuseLambdaContextDecl);
 
   // Try to recover if we have something like sizeof(T::X) where X is a type.
   // Notably, there must be *exactly* one set of parens if X is a type.
@@ -8855,7 +9158,7 @@ TreeTransform<Derived>::TransformBinaryOperator(BinaryOperator *E) {
     return E;
 
   Sema::FPContractStateRAII FPContractState(getSema());
-  getSema().FPFeatures.fp_contract = E->isFPContractable();
+  getSema().FPFeatures = E->getFPFeatures();
 
   return getDerived().RebuildBinaryOperator(E->getOperatorLoc(), E->getOpcode(),
                                             LHS.get(), RHS.get());
@@ -9335,7 +9638,7 @@ TreeTransform<Derived>::TransformCXXOperatorCallExpr(CXXOperatorCallExpr *E) {
     return SemaRef.MaybeBindToTemporary(E);
 
   Sema::FPContractStateRAII FPContractState(getSema());
-  getSema().FPFeatures.fp_contract = E->isFPContractable();
+  getSema().FPFeatures = E->getFPFeatures();
 
   return getDerived().RebuildCXXOperatorCallExpr(E->getOperator(),
                                                  E->getOperatorLoc(),
@@ -9435,7 +9738,8 @@ template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXFunctionalCastExpr(
                                                      CXXFunctionalCastExpr *E) {
-  TypeSourceInfo *Type = getDerived().TransformType(E->getTypeInfoAsWritten());
+  TypeSourceInfo *Type =
+      getDerived().TransformTypeWithDeducedTST(E->getTypeInfoAsWritten());
   if (!Type)
     return ExprError();
 
@@ -9478,8 +9782,9 @@ TreeTransform<Derived>::TransformCXXTypeidExpr(CXXTypeidExpr *E) {
   // after we perform semantic analysis.  We speculatively assume it is
   // unevaluated; it will get fixed later if the subexpression is in fact
   // potentially evaluated.
-  EnterExpressionEvaluationContext Unevaluated(SemaRef, Sema::Unevaluated,
-                                               Sema::ReuseLambdaContextDecl);
+  EnterExpressionEvaluationContext Unevaluated(
+      SemaRef, Sema::ExpressionEvaluationContext::Unevaluated,
+      Sema::ReuseLambdaContextDecl);
 
   ExprResult SubExpr = getDerived().TransformExpr(E->getExprOperand());
   if (SubExpr.isInvalid())
@@ -9514,7 +9819,8 @@ TreeTransform<Derived>::TransformCXXUuidofExpr(CXXUuidofExpr *E) {
                                              E->getLocEnd());
   }
 
-  EnterExpressionEvaluationContext Unevaluated(SemaRef, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
 
   ExprResult SubExpr = getDerived().TransformExpr(E->getExprOperand());
   if (SubExpr.isInvalid())
@@ -9624,8 +9930,8 @@ template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXNewExpr(CXXNewExpr *E) {
   // Transform the type that we're allocating
-  TypeSourceInfo *AllocTypeInfo
-    = getDerived().TransformType(E->getAllocatedTypeSourceInfo());
+  TypeSourceInfo *AllocTypeInfo =
+      getDerived().TransformTypeWithDeducedTST(E->getAllocatedTypeSourceInfo());
   if (!AllocTypeInfo)
     return ExprError();
 
@@ -10128,7 +10434,8 @@ TreeTransform<Derived>::TransformArrayTypeTraitExpr(ArrayTypeTraitExpr *E) {
 
   ExprResult SubExpr;
   {
-    EnterExpressionEvaluationContext Unevaluated(SemaRef, Sema::Unevaluated);
+    EnterExpressionEvaluationContext Unevaluated(
+        SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
     SubExpr = getDerived().TransformExpr(E->getDimensionExpression());
     if (SubExpr.isInvalid())
       return ExprError();
@@ -10149,7 +10456,8 @@ ExprResult
 TreeTransform<Derived>::TransformExpressionTraitExpr(ExpressionTraitExpr *E) {
   ExprResult SubExpr;
   {
-    EnterExpressionEvaluationContext Unevaluated(SemaRef, Sema::Unevaluated);
+    EnterExpressionEvaluationContext Unevaluated(
+        SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
     SubExpr = getDerived().TransformExpr(E->getQueriedExpression());
     if (SubExpr.isInvalid())
       return ExprError();
@@ -10336,7 +10644,8 @@ template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXTemporaryObjectExpr(
                                                     CXXTemporaryObjectExpr *E) {
-  TypeSourceInfo *T = getDerived().TransformType(E->getTypeSourceInfo());
+  TypeSourceInfo *T =
+      getDerived().TransformTypeWithDeducedTST(E->getTypeSourceInfo());
   if (!T)
     return ExprError();
 
@@ -10384,8 +10693,8 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) {
        C != CEnd; ++C) {
     if (!E->isInitCapture(C))
       continue;
-    EnterExpressionEvaluationContext EEEC(getSema(),
-                                          Sema::PotentiallyEvaluated);
+    EnterExpressionEvaluationContext EEEC(
+        getSema(), Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
     ExprResult NewExprInitResult = getDerived().TransformInitializer(
         C->getCapturedVar()->getInit(),
         C->getCapturedVar()->getInitStyle() == VarDecl::CallInit);
@@ -10461,7 +10770,8 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) {
     auto *P = NewCallOperator->getParamDecl(I);
     if (P->hasUninstantiatedDefaultArg()) {
       EnterExpressionEvaluationContext Eval(
-          getSema(), Sema::PotentiallyEvaluatedIfUsed, P);
+          getSema(),
+          Sema::ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed, P);
       ExprResult R = getDerived().TransformExpr(
           E->getCallOperator()->getParamDecl(I)->getDefaultArg());
       P->setDefaultArg(R.get());
@@ -10601,7 +10911,8 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) {
 
   // Enter a new evaluation context to insulate the lambda from any
   // cleanups from the enclosing full-expression.
-  getSema().PushExpressionEvaluationContext(Sema::PotentiallyEvaluated);
+  getSema().PushExpressionEvaluationContext(
+      Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
 
   // Instantiate the body of the lambda expression.
   StmtResult Body =
@@ -10633,7 +10944,8 @@ template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXUnresolvedConstructExpr(
                                                   CXXUnresolvedConstructExpr *E) {
-  TypeSourceInfo *T = getDerived().TransformType(E->getTypeSourceInfo());
+  TypeSourceInfo *T =
+      getDerived().TransformTypeWithDeducedTST(E->getTypeSourceInfo());
   if (!T)
     return ExprError();
 
@@ -10836,7 +11148,8 @@ TreeTransform<Derived>::TransformUnresolvedMemberExpr(UnresolvedMemberExpr *Old)
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXNoexceptExpr(CXXNoexceptExpr *E) {
-  EnterExpressionEvaluationContext Unevaluated(SemaRef, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
   ExprResult SubExpr = getDerived().TransformExpr(E->getOperand());
   if (SubExpr.isInvalid())
     return ExprError();
@@ -10869,7 +11182,8 @@ TreeTransform<Derived>::TransformSizeOfPackExpr(SizeOfPackExpr *E) {
   if (!E->isValueDependent())
     return E;
 
-  EnterExpressionEvaluationContext Unevaluated(getSema(), Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      getSema(), Sema::ExpressionEvaluationContext::Unevaluated);
 
   ArrayRef<TemplateArgument> PackArgs;
   TemplateArgument ArgStorage;
@@ -12018,7 +12332,8 @@ TreeTransform<Derived>::RebuildTemplateName(CXXScopeSpec &SS,
                                             const IdentifierInfo &Name,
                                             SourceLocation NameLoc,
                                             QualType ObjectType,
-                                            NamedDecl *FirstQualifierInScope) {
+                                            NamedDecl *FirstQualifierInScope,
+                                            bool AllowInjectedClassName) {
   UnqualifiedId TemplateName;
   TemplateName.setIdentifier(&Name, NameLoc);
   Sema::TemplateTy Template;
@@ -12027,7 +12342,7 @@ TreeTransform<Derived>::RebuildTemplateName(CXXScopeSpec &SS,
                                        SS, TemplateKWLoc, TemplateName,
                                        ParsedType::make(ObjectType),
                                        /*EnteringContext=*/false,
-                                       Template);
+                                       Template, AllowInjectedClassName);
   return Template.get();
 }
 
@@ -12036,7 +12351,8 @@ TemplateName
 TreeTransform<Derived>::RebuildTemplateName(CXXScopeSpec &SS,
                                             OverloadedOperatorKind Operator,
                                             SourceLocation NameLoc,
-                                            QualType ObjectType) {
+                                            QualType ObjectType,
+                                            bool AllowInjectedClassName) {
   UnqualifiedId Name;
   // FIXME: Bogus location information.
   SourceLocation SymbolLocations[3] = { NameLoc, NameLoc, NameLoc };
@@ -12047,7 +12363,7 @@ TreeTransform<Derived>::RebuildTemplateName(CXXScopeSpec &SS,
                                        SS, TemplateKWLoc, Name,
                                        ParsedType::make(ObjectType),
                                        /*EnteringContext=*/false,
-                                       Template);
+                                       Template, AllowInjectedClassName);
   return Template.get();
 }