1 files changed, 29 insertions, 0 deletions
diff --git a/test/libcxx/input.output/iostream.format/input.streams/traits_mismatch.fail.cpp b/test/libcxx/input.output/iostream.format/input.streams/traits_mismatch.fail.cpp
new file mode 100644
index 000000000000..a459ec4fb71b
--- /dev/null
+++ b/test/libcxx/input.output/iostream.format/input.streams/traits_mismatch.fail.cpp
@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <istream>
+
+// template <class charT, class traits = char_traits<charT> >
+// class basic_istream;
+
+// The char type of the stream and the char_type of the traits have to match
+
+#include <istream>
+#include <type_traits>
+#include <cassert>
+
+struct test_istream
+    : public std::basic_istream<char, std::char_traits<wchar_t> > {};
+
+
+int main()
+{
+//  expected-error-re@ios:* {{static_assert failed{{.*}} "traits_type::char_type must be the same type as CharT"}}
+}
+