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

5 files changed, 12 insertions, 1 deletions

diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
index 1fe6ece42d9..9768d67930f 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -44,6 +44,7 @@
 LANGOPT(C99               , 1, 0, "C99")
 LANGOPT(C1X               , 1, 0, "C1X")
 LANGOPT(Microsoft         , 1, 0, "Microsoft extensions")
+LANGOPT(MicrosoftMode     , 1, 0, "Microsoft compatibility mode")
 LANGOPT(Borland           , 1, 0, "Borland extensions")
 LANGOPT(CPlusPlus         , 1, 0, "C++")
 LANGOPT(CPlusPlus0x       , 1, 0, "C++0x")
diff --git a/clang/include/clang/Driver/CC1Options.td b/clang/include/clang/Driver/CC1Options.td
index 356a76e1e77..ba9469a9494 100644
--- a/clang/include/clang/Driver/CC1Options.td
+++ b/clang/include/clang/Driver/CC1Options.td
@@ -472,7 +472,9 @@ def stdlib_EQ : Joined<"-stdlib=">,
 def fmath_errno : Flag<"-fmath-errno">,
   HelpText<"Require math functions to indicate errors by setting errno">;
 def fms_extensions : Flag<"-fms-extensions">,
-  HelpText<"Accept some non-standard constructs used in Microsoft header files ">;
+  HelpText<"Accept some non-standard constructs supported by the Microsoft compiler">;
+def fms_compatibility : Flag<"-fms-compatibility">,
+  HelpText<"Enable Microsoft compatibility mode">;
 def fmsc_version : Joined<"-fmsc-version=">,
   HelpText<"Version of the Microsoft C/C++ compiler to report in _MSC_VER (0 = don't define it (default))">;
 def fborland_extensions : Flag<"-fborland-extensions">,
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index d9f34f55aca..3f48b96d758 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -340,6 +340,7 @@ def fmath_errno : Flag<"-fmath-errno">, Group<f_Group>;
 def fmerge_all_constants : Flag<"-fmerge-all-constants">, Group<f_Group>;
 def fmessage_length_EQ : Joined<"-fmessage-length=">, Group<f_Group>;
 def fms_extensions : Flag<"-fms-extensions">, Group<f_Group>;
+def fms_compatibility : Flag<"-fms-compatibility">, Group<f_Group>;
 def fmsc_version : Joined<"-fmsc-version=">, Group<f_Group>;
 def fdelayed_template_parsing : Flag<"-fdelayed-template-parsing">, Group<f_Group>;
 def fmodule_cache_path : Separate<"-fmodule-cache-path">, Group<i_Group>, 
@@ -382,6 +383,7 @@ def fno_lax_vector_conversions : Flag<"-fno-lax-vector-conversions">, Group<f_Gr
 def fno_math_errno : Flag<"-fno-math-errno">, Group<f_Group>;
 def fno_merge_all_constants : Flag<"-fno-merge-all-constants">, Group<f_Group>;
 def fno_ms_extensions : Flag<"-fno-ms-extensions">, Group<f_Group>;
+def fno_ms_compatibility : Flag<"-fno-ms-compatibility">, Group<f_Group>;
 def fno_delayed_template_parsing : Flag<"-fno-delayed-template-parsing">, Group<f_Group>;
 def fno_objc_default_synthesize_properties 
   : Flag<"-fno-objc-default-synthesize-properties">, Group<f_Group>;
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);