Avoid definining more GCC specific predefined macros in clang-cl

[majnemer]

I don't think that MSVC compat is the right predicate here, this has more to do with targeting the msvc environment.

[• ehsan]

So which flag should I use instead? Honestly these different flags confuse me and I'm not sure which one is supposed to be used for which purpose.

[triton]

In D4419#6, @ehsan wrote:

So which flag should I use instead? Honestly these different flags confuse me and I'm not sure which one is supposed to be used for which purpose.

Maybe you can use the "msvc" environment part of the triple for this.

[• ehsan]

Closed by commit rL212753 (authored by @ehsan).

lib/Frontend/InitPreprocessor.cpp

Builder.defineMacro("__VERSION__", "\"4.2.1 Compatible " +
                       Twine(getClangFullCPPVersion()) + "\"");
 
   // Initialize language-specific preprocessor defines.
 
   // Standard conforming mode?
   if (!LangOpts.GNUMode && !LangOpts.MSVCCompat)
     Builder.defineMacro("__STRICT_ANSI__");
 
-  if (LangOpts.CPlusPlus11)
+  if (!LangOpts.MSVCCompat && LangOpts.CPlusPlus11)
     Builder.defineMacro("__GXX_EXPERIMENTAL_CXX0X__");
 
   if (LangOpts.ObjC1) {
     if (LangOpts.ObjCRuntime.isNonFragile()) {
       Builder.defineMacro("__OBJC2__");
       
       if (LangOpts.ObjCExceptions)
         Builder.defineMacro("OBJC_ZEROCOST_EXCEPTIONS");
#undef TOSTR2
 
   if (LangOpts.Blocks) {
     Builder.defineMacro("__block", "__attribute__((__blocks__(byref)))");
     Builder.defineMacro("__BLOCKS__");
   }
 
   if (!LangOpts.MSVCCompat && LangOpts.CXXExceptions)
     Builder.defineMacro("__EXCEPTIONS");
-  if (LangOpts.RTTI)
+  if (!LangOpts.MSVCCompat && LangOpts.RTTI)
     Builder.defineMacro("__GXX_RTTI");
   if (LangOpts.SjLjExceptions)
     Builder.defineMacro("__USING_SJLJ_EXCEPTIONS__");
 
   if (LangOpts.Deprecated)
     Builder.defineMacro("__DEPRECATED");
 
-  if (LangOpts.CPlusPlus) {
+  if (!LangOpts.MSVCCompat && LangOpts.CPlusPlus) {
     Builder.defineMacro("__GNUG__", "4");
     Builder.defineMacro("__GXX_WEAK__");
     Builder.defineMacro("__private_extern__", "extern");
   }
 
   if (LangOpts.MicrosoftExt) {
     if (LangOpts.WChar) {
       // wchar_t supported as a keyword.
#undef TOSTR2
   if (const char *Prefix = TI.getUserLabelPrefix())
     Builder.defineMacro("__USER_LABEL_PREFIX__", Prefix);
 
   if (LangOpts.FastMath || LangOpts.FiniteMathOnly)
     Builder.defineMacro("__FINITE_MATH_ONLY__", "1");
   else
     Builder.defineMacro("__FINITE_MATH_ONLY__", "0");
 
+  if (!LangOpts.MSVCCompat) {
     if (LangOpts.GNUInline)
       Builder.defineMacro("__GNUC_GNU_INLINE__");
     else
       Builder.defineMacro("__GNUC_STDC_INLINE__");
 
     // The value written by __atomic_test_and_set.
     // FIXME: This is target-dependent.
     Builder.defineMacro("__GCC_ATOMIC_TEST_AND_SET_TRUEVAL", "1");
 
     // Used by libstdc++ to implement ATOMIC_<foo>_LOCK_FREE.
     unsigned InlineWidthBits = TI.getMaxAtomicInlineWidth();
 #define DEFINE_LOCK_FREE_MACRO(TYPE, Type) \
     Builder.defineMacro("__GCC_ATOMIC_" #TYPE "_LOCK_FREE", \
                         getLockFreeValue(TI.get##Type##Width(), \
                                          TI.get##Type##Align(), \
                                          InlineWidthBits));
     DEFINE_LOCK_FREE_MACRO(BOOL, Bool);
     DEFINE_LOCK_FREE_MACRO(CHAR, Char);
     DEFINE_LOCK_FREE_MACRO(CHAR16_T, Char16);
     DEFINE_LOCK_FREE_MACRO(CHAR32_T, Char32);
     DEFINE_LOCK_FREE_MACRO(WCHAR_T, WChar);
     DEFINE_LOCK_FREE_MACRO(SHORT, Short);
     DEFINE_LOCK_FREE_MACRO(INT, Int);
     DEFINE_LOCK_FREE_MACRO(LONG, Long);
     DEFINE_LOCK_FREE_MACRO(LLONG, LongLong);
     Builder.defineMacro("__GCC_ATOMIC_POINTER_LOCK_FREE",
                         getLockFreeValue(TI.getPointerWidth(0),
                                          TI.getPointerAlign(0),
                                          InlineWidthBits));
 #undef DEFINE_LOCK_FREE_MACRO
+  }
 
   if (LangOpts.NoInlineDefine)
     Builder.defineMacro("__NO_INLINE__");
 
   if (unsigned PICLevel = LangOpts.PICLevel) {
     Builder.defineMacro("__PIC__", Twine(PICLevel));
     Builder.defineMacro("__pic__", Twine(PICLevel));
   }

test/Preprocessor/predefined-macros.c

 // This test verifies that the correct macros are predefined.
 //
 // RUN: %clang_cc1 %s -E -dM -triple i686-pc-win32 -fms-extensions -fms-compatibility \
 // RUN:     -fmsc-version=1300 -o - | FileCheck %s --check-prefix=CHECK-MS
 // CHECK-MS: #define _INTEGRAL_MAX_BITS 64
 // CHECK-MS: #define _MSC_EXTENSIONS 1
 // CHECK-MS: #define _MSC_VER 1300
 // CHECK-MS: #define _M_IX86 600
 // CHECK-MS: #define _M_IX86_FP
 // CHECK-MS: #define _WIN32 1
-// CHECK-MS-NOT: #define __GNUC__
 // CHECK-MS-NOT: #define __STRICT_ANSI__
 // CHECK-MS-NOT: #define __i386__
 // CHECK-MS-NOT: #define __i486__
 // CHECK-MS-NOT: #define __i686__
 // CHECK-MS-NOT: #define __SSE__
+// CHECK-MS-NOT: GCC
+// CHECK-MS-NOT: GNU
+// CHECK-MS-NOT: GXX
 //
 // RUN: %clang_cc1 %s -E -dM -triple x86_64-pc-win32 -fms-extensions -fms-compatibility \
 // RUN:     -fmsc-version=1300 -o - | FileCheck %s --check-prefix=CHECK-MS64
 // CHECK-MS64: #define _INTEGRAL_MAX_BITS 64
 // CHECK-MS64: #define _MSC_EXTENSIONS 1
 // CHECK-MS64: #define _MSC_VER 1300
 // CHECK-MS64: #define _M_AMD64 1
 // CHECK-MS64: #define _M_X64 1
 // CHECK-MS64: #define _WIN64 1
-// CHECK-MS64-NOT: #define __GNUC__
 // CHECK-MS64-NOT: #define __STRICT_ANSI__
 // CHECK-MS64-NOT: #define __i486__
 // CHECK-MS64-NOT: #define __i686__
 // CHECK-MS64-NOT: #define __i386__
 // CHECK-MS64-NOT: #define __SSE__
 // CHECK-MS64-NOT: #define __x86_64__
 // CHECK-MS64-NOT: #define __amd64__
+// CHECK-MS64-NOT: GCC
+// CHECK-MS64-NOT: GNU
+// CHECK-MS64-NOT: GXX
 //
 // RUN: %clang_cc1 %s -E -dM -triple i686-pc-win32 -fms-compatibility \
 // RUN:     -o - | FileCheck %s --check-prefix=CHECK-MS-STDINT
 // CHECK-MS-STDINT-NOT:#define __INT16_MAX__ 32767
 // CHECK-MS-STDINT-NOT:#define __INT32_MAX__ 2147483647
 // CHECK-MS-STDINT-NOT:#define __INT64_MAX__ 9223372036854775807LL
 // CHECK-MS-STDINT-NOT:#define __INT8_MAX__ 127
 // CHECK-MS-STDINT-NOT:#define __INTPTR_MAX__ 2147483647