2 files changed, 13 insertions, 0 deletions
diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
index f1a14544104..3ee9cd48b53 100644
--- a/clang/lib/Basic/Targets.cpp
+++ b/clang/lib/Basic/Targets.cpp
@@ -253,6 +253,11 @@ protected:
     Builder.defineMacro("__KPRINTF_ATTRIBUTE__");
     DefineStd(Builder, "unix", Opts);
     Builder.defineMacro("__ELF__");
+
+    // On FreeBSD, wchar_t contains the number of the code point as
+    // used by the character set of the locale. These character sets are
+    // not necessarily a superset of ASCII.
+    Builder.defineMacro("__STDC_MB_MIGHT_NEQ_WC__", "1");
   }
 public:
   FreeBSDTargetInfo(const llvm::Triple &Triple) : OSTargetInfo<Target>(Triple) {
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 8703a67a6f9..77cf3b38e6d 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -330,6 +330,14 @@ static void InitializeStandardPredefinedMacros(const TargetInfo &TI,
       Builder.defineMacro("__cplusplus", "199711L");
   }
 
+  // In C11 these are environment macros. In C++11 they are only defined
+  // as part of <cuchar>. To prevent breakage when mixing C and C++
+  // code, define these macros unconditionally. We can define them
+  // unconditionally, as Clang always uses UTF-16 and UTF-32 for 16-bit
+  // and 32-bit character literals.
+  Builder.defineMacro("__STDC_UTF_16__", "1");
+  Builder.defineMacro("__STDC_UTF_32__", "1");
+
   if (LangOpts.ObjC1)
     Builder.defineMacro("__OBJC__");