Introduce _LIBCPP_STD_VER. This can be set by the client (or the clang driver). Or it will be defaulted. The default is 11 if -std= c++11 or eariler, else it will default to the current year modulo the century. We anticipate it defaulting to 14 for C++14 when the time comes. For now, post-C++11 libcxx implementations should protect themselves with #if _LIBCPP_STD_VER > 11.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@181347 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/__config b/include/__config
index 7923f2f..dcddae8 100644
--- a/include/__config
+++ b/include/__config
@@ -488,6 +488,14 @@
# endif
#endif
+#ifndef _LIBCPP_STD_VER
+# if __cplusplus <= 201103L
+# define _LIBCPP_STD_VER 11
+# else
+# define _LIBCPP_STD_VER 13 // current year, or date of c++14 ratification
+# endif
+#endif // _LIBCPP_STD_VER
+
#ifdef _LIBCPP_DEBUG2
# include <__debug>
#else