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//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// UNSUPPORTED: c++98, c++03
// <tuple>
// template <class... Types> class tuple;
// template <class TupleLike>
// tuple(TupleLike&&);
// template <class Alloc, class TupleLike>
// tuple(std::allocator_arg_t, Alloc const&, TupleLike&&);
// Check that the tuple-like ctors are properly disabled when the UTypes...
// constructor should be selected. See PR22806.
#include <tuple>
#include <memory>
#include <cassert>
template <class Tp>
using uncvref_t = typename std::remove_cv<typename std::remove_reference<Tp>::type>::type;
template <class Tuple, class = uncvref_t<Tuple>>
struct IsTuple : std::false_type {};
template <class Tuple, class ...Args>
struct IsTuple<Tuple, std::tuple<Args...>> : std::true_type {};
struct ConstructibleFromTupleAndInt {
enum State { FromTuple, FromInt, Copied, Moved };
State state;
ConstructibleFromTupleAndInt(ConstructibleFromTupleAndInt const&) : state(Copied) {}
ConstructibleFromTupleAndInt(ConstructibleFromTupleAndInt &&) : state(Moved) {}
template <class Tuple, class = typename std::enable_if<IsTuple<Tuple>::value>::type>
explicit ConstructibleFromTupleAndInt(Tuple&&) : state(FromTuple) {}
explicit ConstructibleFromTupleAndInt(int) : state(FromInt) {}
};
struct ConvertibleFromTupleAndInt {
enum State { FromTuple, FromInt, Copied, Moved };
State state;
ConvertibleFromTupleAndInt(ConvertibleFromTupleAndInt const&) : state(Copied) {}
ConvertibleFromTupleAndInt(ConvertibleFromTupleAndInt &&) : state(Moved) {}
template <class Tuple, class = typename std::enable_if<IsTuple<Tuple>::value>::type>
ConvertibleFromTupleAndInt(Tuple&&) : state(FromTuple) {}
ConvertibleFromTupleAndInt(int) : state(FromInt) {}
};
struct ConstructibleFromInt {
enum State { FromInt, Copied, Moved };
State state;
ConstructibleFromInt(ConstructibleFromInt const&) : state(Copied) {}
ConstructibleFromInt(ConstructibleFromInt &&) : state(Moved) {}
explicit ConstructibleFromInt(int) : state(FromInt) {}
};
struct ConvertibleFromInt {
enum State { FromInt, Copied, Moved };
State state;
ConvertibleFromInt(ConvertibleFromInt const&) : state(Copied) {}
ConvertibleFromInt(ConvertibleFromInt &&) : state(Moved) {}
ConvertibleFromInt(int) : state(FromInt) {}
};
int main()
{
// Test for the creation of dangling references when a tuple is used to
// store a reference to another tuple as its only element.
// Ex std::tuple<std::tuple<int>&&>.
// In this case the constructors 1) 'tuple(UTypes&&...)'
// and 2) 'tuple(TupleLike&&)' need to be manually disambiguated because
// when both #1 and #2 participate in partial ordering #2 will always
// be chosen over #1.
// See PR22806 and LWG issue #2549 for more information.
// (https://bugs.llvm.org/show_bug.cgi?id=22806)
using T = std::tuple<int>;
std::allocator<int> A;
{ // rvalue reference
T t1(42);
std::tuple< T&& > t2(std::move(t1));
assert(&std::get<0>(t2) == &t1);
}
{ // const lvalue reference
T t1(42);
std::tuple< T const & > t2(t1);
assert(&std::get<0>(t2) == &t1);
std::tuple< T const & > t3(static_cast<T const&>(t1));
assert(&std::get<0>(t3) == &t1);
}
{ // lvalue reference
T t1(42);
std::tuple< T & > t2(t1);
assert(&std::get<0>(t2) == &t1);
}
{ // const rvalue reference
T t1(42);
std::tuple< T const && > t2(std::move(t1));
assert(&std::get<0>(t2) == &t1);
}
{ // rvalue reference via uses-allocator
T t1(42);
std::tuple< T&& > t2(std::allocator_arg, A, std::move(t1));
assert(&std::get<0>(t2) == &t1);
}
{ // const lvalue reference via uses-allocator
T t1(42);
std::tuple< T const & > t2(std::allocator_arg, A, t1);
assert(&std::get<0>(t2) == &t1);
std::tuple< T const & > t3(std::allocator_arg, A, static_cast<T const&>(t1));
assert(&std::get<0>(t3) == &t1);
}
{ // lvalue reference via uses-allocator
T t1(42);
std::tuple< T & > t2(std::allocator_arg, A, t1);
assert(&std::get<0>(t2) == &t1);
}
{ // const rvalue reference via uses-allocator
T const t1(42);
std::tuple< T const && > t2(std::allocator_arg, A, std::move(t1));
assert(&std::get<0>(t2) == &t1);
}
// Test constructing a 1-tuple of the form tuple<UDT> from another 1-tuple
// 'tuple<T>' where UDT *can* be constructed from 'tuple<T>'. In this case
// the 'tuple(UTypes...)' ctor should be chosen and 'UDT' constructed from
// 'tuple<T>'.
{
using VT = ConstructibleFromTupleAndInt;
std::tuple<int> t1(42);
std::tuple<VT> t2(t1);
assert(std::get<0>(t2).state == VT::FromTuple);
}
{
using VT = ConvertibleFromTupleAndInt;
std::tuple<int> t1(42);
std::tuple<VT> t2 = {t1};
assert(std::get<0>(t2).state == VT::FromTuple);
}
// Test constructing a 1-tuple of the form tuple<UDT> from another 1-tuple
// 'tuple<T>' where UDT cannot be constructed from 'tuple<T>' but can
// be constructed from 'T'. In this case the tuple-like ctor should be
// chosen and 'UDT' constructed from 'T'
{
using VT = ConstructibleFromInt;
std::tuple<int> t1(42);
std::tuple<VT> t2(t1);
assert(std::get<0>(t2).state == VT::FromInt);
}
{
using VT = ConvertibleFromInt;
std::tuple<int> t1(42);
std::tuple<VT> t2 = {t1};
assert(std::get<0>(t2).state == VT::FromInt);
}
}
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