These tests PASS on libstdc++ and MSVC.
//
//===----------------------------------------------------------------------===//
//
-// XFAIL: *
+// XFAIL: libc++
// <cuchar>
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03, c++11, c++14
-// XFAIL: c++17, c++2a
+// XFAIL: libc++
// <functional>
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03, c++11, c++14
-// XFAIL: c++17, c++2a
+// XFAIL: libc++
// <functional>
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03, c++11, c++14
-// XFAIL: c++17, c++2a
+// XFAIL: libc++
// <functional>
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03, c++11, c++14
-// XFAIL: c++17, c++2a
+// XFAIL: libc++
// <functional>
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03, c++11, c++14
-// XFAIL: c++17, c++2a
+// XFAIL: libc++
// <functional>
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03, c++11, c++14
-// XFAIL: c++17, c++2a
+// XFAIL: libc++
// <functional>
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03, c++11, c++14
-// XFAIL: c++17, c++2a
+// XFAIL: libc++
// <functional>
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03, c++11, c++14
-// XFAIL: c++17, c++2a
+// XFAIL: libc++
// <functional>