On Windows the function template `template <class T> void test()` has the same mangled name when instantiated with the distinct types `void()` and `void() noexcept`. When this occurs Clang emits an error. This error was causing two type-traits tests to fail. However this can be worked around by using class templates instead of function templates, which is what this patch does to fix the errors. git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@302380 91177308-0d34-0410-b5e6-96231b3b80d8