Support __wchar_t in -fms-extensions and -fms-compatibility modes.

MSVC provides __wchar_t, either as an alias for the built-in wchar_t
type, or as a separate type depending on language (C vs C++) and flags
(-fno-wchar).

In -fms-extensions, Clang will simply accept __wchar_t as an alias for
whatever type is used for wide character literals. In -fms-compatibility, we
try to mimic MSVC's behavior by always making __wchar_t a builtin type.

This fixes PR15815.

llvm-svn: 181004

2 files changed, 4 insertions, 3 deletions

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 5e9a87c58a7..f4e53e61058 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -897,12 +897,13 @@ void ASTContext::InitBuiltinTypes(const TargetInfo &Target) {
   InitBuiltinType(Int128Ty,            BuiltinType::Int128);
   InitBuiltinType(UnsignedInt128Ty,    BuiltinType::UInt128);
 
-  if (LangOpts.CPlusPlus && LangOpts.WChar) { // C++ 3.9.1p5
+  if ((LangOpts.CPlusPlus && LangOpts.WChar) || LangOpts.MicrosoftMode) {
+    // C++ 3.9.1p5 or -fms-compatibility.
     if (TargetInfo::isTypeSigned(Target.getWCharType()))
       InitBuiltinType(WCharTy,           BuiltinType::WChar_S);
     else  // -fshort-wchar makes wchar_t be unsigned.
       InitBuiltinType(WCharTy,           BuiltinType::WChar_U);
-  } else // C99 (or C++ using -fno-wchar)
+  } else // C99 (or C++ using -fno-wchar) in non-MicrosoftMode.
     WCharTy = getFromTargetType(Target.getWCharType());
 
   WIntTy = getFromTargetType(Target.getWIntType());
diff --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
index fa16facb634..a1f0b08494b 100644
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -1521,7 +1521,7 @@ StringRef BuiltinType::getName(const PrintingPolicy &Policy) const {
   case Double:            return "double";
   case LongDouble:        return "long double";
   case WChar_S:
-  case WChar_U:           return "wchar_t";
+  case WChar_U:           return Policy.MSWChar ? "__wchar_t" : "wchar_t";
   case Char16:            return "char16_t";
   case Char32:            return "char32_t";
   case NullPtr:           return "nullptr_t";