Predefine _M_IX86 in gcc

Hi,

I needed to use OpenGL/glut under MinGW. I grabbed glut-3.7.6, but
I needed to do some fixing, so that CALLBACK is defined properly
(below).
This is a fragment of glut.h.

#   if (defined(_M_MRX000) || defined(_M_IX86) || defined(_M_ALPHA) || \
  defined(_M_PPC)) && !defined(MIDL_PASS) || defined(__LCC__)
#    define CALLBACK __stdcall
#   else
#    define CALLBACK
#   endif

Adding "defined(__GCC__)" was a quick and effective fix for me. However,
I think that _M_IX86 should be predefined when compiling a Win32/Intel
program, regardless of the compiler used.

I don't think it is only a MSC thing; for instance, Borland C defines it,
too. I could have written to the glut maintainer to add "defined(__GCC__)"
after __LCC__ (well, I wrote him about another issue), but I think it is
gcc's job to predefine _M_IX86 instead.

The specification is here:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vccore98/HTML/_PREDIR_Predefined_Macros.asp

I believe it is easy to do this in the *cpp_cpucommon section in the
gcc specs, but even a simple default "-D_M_IX86=300" should be more
helpful than nothing.

**

BTW: I also think it would be a good idea to supply MinGW with glut.h,
since libglut32.a is already there. This is especially because the
original glut.h required mingw-specific tweaking such as:

/* MinGW-gcc requires GLUT_DISABLE_ATEXIT_HACK */
#ifdef __GNUC__
#define GLUT_DISABLE_ATEXIT_HACK
#endif

I don't know why this is necessary, perhaps it's because libglut32.a
that you supply does not export symbols such as __glutCreateMenuWithExit,
__glutCreateWindowWithExit, __glutCreateMenuWithExit

Beware: the code above is a quick fix of mine, so please disregard it.
I have no idea if this breaks on Cygwin. I am showing it only to prove
that setting up glut under mingw is not at all a clean task right now.

Anyway, the point is, it would be great (for me, at least) if glut.h
would be supplied with mingw. I can write a request on MinGW-users if
necessary.

**

Best regards,
Cosmin

PS: Please cc: to "cosmin-at-cs...", as I am not subscribed to the list.



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