Re: documentation of AC_FUNC_ALLOCA and mingw-w64 compilers

[Vincent Torri]

On Sun, 22 Jan 2012, Paul Eggert wrote:

> On 01/22/2012 12:45 PM, Vincent Torri wrote:
> > and there was a redefinition because stdlib.h is included just above,
> > and stdlib.h includes malloc.h. And with mingw-w64 compilers, malloc.h already 
> > defines alloca.
>
> Is this the stdlib.h that comes with mingw-w64?  Can you
> show the code that does that inclusion?  Is it a simple
>
> #include <malloc.h>
>
> or is it protected by an #if or #ifdef?

stdlib.h :

#ifndef _INC_STDLIB
#define _INC_STDLIB

/* content of stdlib.h */

#include <sec_api/stdlib_s.h>
#include <malloc.h>

#endif

that is, it's included just before the final #endif

>  Also, how does
> malloc.h define alloca?   Presumably it does not look like
> this:
>
> #define alloca __builtin_alloca
>
> so what does it look like?  And is it defined unconditionally,
> or is it protected by an #if?

in malloc.h:

#ifdef __GNUC__
#undef _alloca
#define _alloca(x) __builtin_alloca((x))
#else
  void *__cdecl _alloca(size_t _Size) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
#endif

Vincent Torri