As per discussion with Doug Gregor on the IRC channel, introduce a new compiler switch: -fms-compatility.

Microsoft specific tweaking will now fall into 2 categories:

    - fms-extension: Microsoft specific extensions that should never change the meaning of an otherwise well formed code. Currently map to LangOptions::Microsoft. (To be clearer, I am planning to change the name to LangOptions::MicrosoftExt).

    - fms-compatibility: Really a MSVC emulation mode. Map to LangOptions::MicrosoftMode. Can change the meaning of an otherwise standard conformant program.

llvm-svn: 139978

2 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index e8c8df5b8f3..4d4abff6399 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -1785,6 +1785,11 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                    getToolChain().getTriple().getOS() == llvm::Triple::Win32))
     CmdArgs.push_back("-fms-extensions");
 
+  // -fms-compatibility=0 is default.
+  if (Args.hasFlag(options::OPT_fms_compatibility, options::OPT_fno_ms_compatibility,
+                   getToolChain().getTriple().getOS() == llvm::Triple::Win32))
+    CmdArgs.push_back("-fms-compatibility");
+
   // -fmsc-version=1300 is default.
   if (Args.hasFlag(options::OPT_fms_extensions, options::OPT_fno_ms_extensions,
                    getToolChain().getTriple().getOS() == llvm::Triple::Win32) ||
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 582fceff696..5f4310a086d 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1655,6 +1655,7 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
                                    Opts.DollarIdents);
   Opts.PascalStrings = Args.hasArg(OPT_fpascal_strings);
   Opts.Microsoft = Args.hasArg(OPT_fms_extensions);
+  Opts.MicrosoftMode = Args.hasArg(OPT_fms_compatibility);
   Opts.MSCVersion = Args.getLastArgIntValue(OPT_fmsc_version, 0, Diags);
   Opts.Borland = Args.hasArg(OPT_fborland_extensions);
   Opts.WritableStrings = Args.hasArg(OPT_fwritable_strings);