Implement a __WCHAR_UNSIGNED__ macro and use it to include WCHAR_MIN and

WCHAR_MAX in limits.h, thus solving the problem where the system header
thinks it knows better.

llvm-svn: 135455

clang/lib/Frontend/InitPreprocessor.cpp

@@ -554,6 +554,9 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
   if (!TargetInfo::isTypeSigned(TI.getWIntType()))
     Builder.defineMacro("__WINT_UNSIGNED__");
 
+  if (!TargetInfo::isTypeSigned(TI.getWCharType()))
+    Builder.defineMacro("__WCHAR_UNSIGNED__");
+
   // Define exact-width integer types for stdint.h
   Builder.defineMacro("__INT" + llvm::Twine(TI.getCharWidth()) + "_TYPE__",
                       "char");