[coroutines] libcxx, noop_coroutine, make bots even more happy

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@329245 91177308-0d34-0410-b5e6-96231b3b80d8

include/experimental/coroutine

@@ -278,9 +278,9 @@ public:
   _LIBCPP_CONSTEXPR explicit operator bool() const _NOEXCEPT { return true; }
   _LIBCPP_CONSTEXPR bool done() const _NOEXCEPT { return false; }
 
-  _LIBCPP_CONSTEXPR void operator()() const _NOEXCEPT {}
-  _LIBCPP_CONSTEXPR void resume() const _NOEXCEPT {}
-  _LIBCPP_CONSTEXPR void destroy() const _NOEXCEPT {}
+  _LIBCPP_CONSTEXPR_AFTER_CXX17 void operator()() const _NOEXCEPT {}
+  _LIBCPP_CONSTEXPR_AFTER_CXX17 void resume() const _NOEXCEPT {}
+  _LIBCPP_CONSTEXPR_AFTER_CXX17 void destroy() const _NOEXCEPT {}
 
 private:
   friend coroutine_handle<noop_coroutine_promise> noop_coroutine() _NOEXCEPT;

test/std/experimental/language.support/support.coroutines/coroutine.handle/coroutine.handle.noop/noop_coroutine.pass.cpp

@@ -9,7 +9,6 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++98, c++03, c++11
-// XFAIL: clang-5, clang-6
 // UNSUPPORTED: ubsan
 
 // <experimental/coroutine>