2 files changed, 25 insertions, 1 deletions
diff --git a/libcxx/test/std/strings/basic.string/traits_mismatch.fail.cpp b/libcxx/test/std/strings/basic.string/traits_mismatch.fail.cpp
new file mode 100644
index 00000000000..1d54238ae0c
--- /dev/null
+++ b/libcxx/test/std/strings/basic.string/traits_mismatch.fail.cpp
@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+//   The strings's value type must be the same as the traits's char_type
+
+#include <string>
+
+int main()
+{
+    std::basic_string<char, std::char_traits<wchar_t>> s;
+}
diff --git a/libcxx/test/std/strings/string.view/nothing_to_do.pass.cpp b/libcxx/test/std/strings/string.view/traits_mismatch.fail.cpp
index 353dd98f415..6cd15e6a67b 100644
--- a/libcxx/test/std/strings/string.view/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/strings/string.view/traits_mismatch.fail.cpp
@@ -7,6 +7,12 @@
 //
 //===----------------------------------------------------------------------===//
 
+// <string_view>
+//   The string_views's value type must be the same as the traits's char_type
+
 #include <string_view>
 
-int main () {}
+int main()
+{
+    std::basic_string_view<char, std::char_traits<wchar_t>> s;
+}