[libc++] Workaround broken support for C++17 in GCC 5

diff --git a/libcxx/include/variant b/libcxx/include/variant
index 0355723..5ea2cbd 100644 (file)
--- a/libcxx/include/variant
+++ b/libcxx/include/variant
@@ -227,7 +227,10 @@ public:
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 14
+// TODO: GCC 5 lies about its support for C++17 (it says it supports it but it
+//       really doesn't). That breaks variant, which uses some C++17 features.
+//       Remove this once we drop support for GCC 5.
+#if _LIBCPP_STD_VER > 14 && !(_GNUC_VER_NEW < 6000)
 
 _LIBCPP_NORETURN
 inline _LIBCPP_INLINE_VISIBILITY