Define _GNU_SOURCE in C++ mode so that clang works with GNU libstdc++.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@80289 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Frontend/InitPreprocessor.cpp b/lib/Frontend/InitPreprocessor.cpp
index 466cbafff663e3f9c0b72f51c595eb3c62e1b42e..555054772d0bfb1bbff2b6f228549ae01209c2cb 100644 (file)
--- a/lib/Frontend/InitPreprocessor.cpp
+++ b/lib/Frontend/InitPreprocessor.cpp
@@ -313,6 +313,8 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
       //   C++ translation unit.
       DefineBuiltinMacro(Buf, "__cplusplus=199711L");
     DefineBuiltinMacro(Buf, "__private_extern__=extern");
+    // Ugly hack to work with GNU libstdc++.
+    DefineBuiltinMacro(Buf, "_GNU_SOURCE=1");
   }
   
   // Filter out some microsoft extensions when trying to parse in ms-compat