Detect relaxed constexpr rules for gcc versions
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@250802 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/__config b/include/__config
index bc01805..b7e3532 100644
--- a/include/__config
+++ b/include/__config
@@ -451,8 +451,11 @@
#define _LIBCPP_HAS_NO_CONSTEXPR
#endif
-// No version of GCC supports relaxed constexpr rules
+// Determine if GCC supports relaxed constexpr
+#if !defined(__cpp_constexpr) || __cpp_constexpr < 201304L
#define _LIBCPP_HAS_NO_CXX14_CONSTEXPR
+#endif
+
// GCC 5 will support variable templates
#define _LIBCPP_HAS_NO_VARIABLE_TEMPLATES