[cfe-dev] math.h on Windows

[John Thompson]

 Doug,


> _Complex is currently a keyword in every mode. We could make it only be a
> keyword in C99 or GNU mode, then make sure that neither of these modes is
> turned on by default when Clang is built with VC++. That probably makes
> sense, since VC++ doesn't support C99 or many GNU extensions anyway.
>
> We can always force tests into specific modes (turning off Microsoft
> extensions, turning on GNU extensions or C99, whatever), rather than trying
> to work around problems that are unlikely to show up in code that compiles
> with VC++.


How would you collectively force the tests?

I'm kinda feeling that since we're down to just 21 failing tests,
and _Complex isn't a problem with VC 9.0, we could probably punt on it for
now, and see how it goes with the rest of the tests.  But let me know if you
want me to persue this.



> What is the actual issue with the redefinition of wchar_t? Are they
> creating a typedef of wchar_t in their headers? Does the VC++ compiler
> implicitly define _WCHAR_T_DEFINED?
>

This occurs in a few headers:

#ifndef _WCHAR_T_DEFINED
typedef unsigned short wchar_t;
#define _WCHAR_T_DEFINED
#endif

The enclosed wchar_t_fix2.patch seems to fix both the wchar_t issue, and
another one I ran into with VC++ headers.  I was side-tracked a bit with
errors on wchar_t I didn't understand, until I realized that wchar_t was
only a C++ keyword.

I also ran into some new errors with the VC 9.0 headers on some #pragma's.
Defining _CRT_SECURE_CPP_OVERLOAD_SECURE_NAMES avoids them, though it's a
bit of a hack.  This symbol prevents the definition of some macros, some of
which have errors, for example on __pragma statements like this:

__pragma(warning(push))

This is a Microsoft extension not currently supported, right?  It seems kind
of useful for macros.

You mentioned that the Targets.cpp was probably not the right place for the
defines, so I moved them to InitPreprocessor.cpp.  Is this the right place?

Also, could someone look at the enclosed patch for stdint.h?  This also
fixes some failing tests, since VC++ doesn't have stdint.h.  Who is point on
this?

I can check in the patches you approve.

-John
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