r198497 - Move MS predefined type_info out of InitializePredefinedMacros

[Alp Toker]

On 04/01/2014 19:09, David Majnemer wrote:
> Hi Alp,
>
> I am working on RTTI support, a prerequisite for proper EH.
>
> I'm not sure why we would want to move it from MicrosoftExt.  The way 
> I see it, we have MicrosoftMode for conforming extensions (__uuidof, 
> etc.) and MicrosoftExt for non-conforming extensions (extra 
> qualification on member functions, etc.).  This seems like a 
> non-conforming extension to me.

Thanks for the clarification David.

If it's the way you describe, that indicates a naming problem -- in all 
the other clang language standards 'Ext' and 'Mode' have opposite semantics.

For example, C++11 mode is the native setting, whereas C++11 extensions 
is the default setting plus C++11 language features as extensions with 
backward compatibility.

Extensions enable features without changing the core semantics, whereas 
a "mode" is potentially a whole different incompatible/vendor-specific 
language dialect.

In contrast, it appears that MicrosoftExt has become the native/MSVC 
mode whereas MicrosoftMode is now being used as a flag to add Microsoft 
extensions usable in conforming code.

A quick grep shows they're used interchangeably, depending on who wrote 
the code.

In practice it looks like comments and variable names already refer to 
MicrosoftExt as "Microsoft mode"...

lib/Basic/Builtins.cpp:         MSModeUnsupported = !LangOpts.MicrosoftExt

... and refer to MicrosoftMode as "Microsoft extensions" ...

lib/Sema/SemaDecl.cpp:        if (getLangOpts().MicrosoftMode)
lib/Sema/SemaDecl.cpp-          DiagID = diag::ext_ms_forward_ref_enum;

Did we just discover a case of unchecked confusion? :-)

Alp.


>
> On Saturday, January 4, 2014, Alp Toker wrote:
>
>     This is also a good starting point if anyone wants to work on MS
>     exception support.
>
>     However while making this change it occurred to me that this
>     should be moved from MicrosoftExt to MicrosoftMode -- thoughts?
>
>     Alp.
>
>
>     While making this change
>     On 04/01/2014 15:25, Alp Toker wrote:
>
>         Author: alp
>         Date: Sat Jan  4 09:25:02 2014
>         New Revision: 198497
>
>         URL: http://llvm.org/viewvc/llvm-project?rev=198497&view=rev
>         Log:
>         Move MS predefined type_info out of InitializePredefinedMacros
>
>         Instead of keeping it in amongst the macros, build the
>         declaration at Sema init
>         the same way we do with other predeclared and builtin types.
>
>         In practice this means the declaration is marked implicit and
>         therefore won't
>         show up as an unwanted user-declared type in tooling which has
>         been a
>         frequently reported issue (though I haven't been able to cook
>         up a test).
>
>         Modified:
>              cfe/trunk/lib/Frontend/InitPreprocessor.cpp
>              cfe/trunk/lib/Sema/Sema.cpp
>
>         Modified: cfe/trunk/lib/Frontend/InitPreprocessor.cpp
>         URL:
>         http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/InitPreprocessor.cpp?rev=198497&r1=198496&r2=198497&view=diff
>         ==============================================================================
>         --- cfe/trunk/lib/Frontend/InitPreprocessor.cpp (original)
>         +++ cfe/trunk/lib/Frontend/InitPreprocessor.cpp Sat Jan  4
>         09:25:02 2014
>         @@ -518,7 +518,6 @@ static void InitializePredefinedMacros(c
>               if (LangOpts.CPlusPlus) {
>                 // FIXME: Support Microsoft's __identifier extension
>         in the lexer.
>                 Builder.append("#define __identifier(x) x");
>         -      Builder.append("class type_info;");
>               }
>             }
>
>         Modified: cfe/trunk/lib/Sema/Sema.cpp
>         URL:
>         http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/Sema.cpp?rev=198497&r1=198496&r2=198497&view=diff
>         ==============================================================================
>         --- cfe/trunk/lib/Sema/Sema.cpp (original)
>         +++ cfe/trunk/lib/Sema/Sema.cpp Sat Jan  4 09:25:02 2014
>         @@ -178,6 +178,13 @@ void Sema::Initialize() {
>                 PushOnScopeChains(Context.getObjCProtocolDecl(), TUScope);
>             }
>           +  // Initialize Microsoft "predefined C++ types".
>         +  if (PP.getLangOpts().MicrosoftExt &&
>         PP.getLangOpts().CPlusPlus) {
>         +    if (IdResolver.begin(&Context.Idents.get("type_info")) ==
>         IdResolver.end())
>         +    
>          PushOnScopeChains(Context.buildImplicitRecord("type_info",
>         TTK_Class),
>         +                        TUScope);
>         +  }
>         +
>             // Initialize predefined OpenCL types.
>             if (PP.getLangOpts().OpenCL) {
>               addImplicitTypedef("image1d_t", Context.OCLImage1dTy);
>
>
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