[libcxx] r293439 - config: prevent the re-definition of a macro

[Saleem Abdulrasool via cfe-commits]

Author: compnerd
Date: Sun Jan 29 12:16:33 2017
New Revision: 293439

URL: http://llvm.org/viewvc/llvm-project?rev=293439&view=rev
Log:
config: prevent the re-definition of a macro

This causes unnecessary warnings when building with `cl`.  Newer
versions of the C standard permit the redefinition of the macro to the
same value (which is the case here), unfortunately, `cl` does not yet
implement this.  Add a check to prevent the redefinition.

Modified:
    libcxx/trunk/include/__config

Modified: libcxx/trunk/include/__config
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/__config?rev=293439&r1=293438&r2=293439&view=diff
==============================================================================
--- libcxx/trunk/include/__config (original)
+++ libcxx/trunk/include/__config Sun Jan 29 12:16:33 2017
@@ -12,8 +12,10 @@
 #define _LIBCPP_CONFIG
 
 #if defined(_MSC_VER) && !defined(__clang__)
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #define _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER
 #endif
+#endif
 
 #ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER
 #pragma GCC system_header