of libstdc++, not just certain versions of GCC. The original macros
broke when using Clang + libstdc++4.9 sadly.
Sadly, testing for versions of libstdc++ has been extremely problematic
in the past, so I'm just narrowing this down to Windows and when using
libc++ as that seems at least very unlikely to keep build bots broken.
llvm-svn: 336174
IsTriviallyMoveConstructible,
"Mismatch in expected trivial move construction!");
-#if __clang__ || _MSC_VER || __GNUC__ > 5
+#if defined(_LIBCPP_VERSION) || defined(_MSC_VER)
// On compilers with support for the standard traits, make sure they agree.
static_assert(std::is_trivially_copy_constructible<T>::value ==
IsTriviallyCopyConstructible,