Re: alloca() warnings on freebsd

[Giorgos Keramidas <keramida@ceid.upatras.gr>]

On Mon, 09 Aug 2010 19:16:33 -0400, Dan Nicolaescu <dann@gnu.org> wrote:
> Giorgos Keramidas <keramida@ceid.upatras.gr> writes:
>> Some time during the recent past an alloca() prototype was introduced to
>> config.h that conflicts with the stdlib.h prototype of alloca() on my
>> FreeBSD laptop.
>>
>> The current check near line 1148 of config.in is:
>>
>>     #ifdef HAVE_ALLOCA_H
>>     # include <alloca.h>
>>     #elif defined __GNUC__
>>     # define alloca __builtin_alloca
>>     #elif defined _AIX
>>     # define alloca __alloca
>>     #else
>>     # include <stddef.h>
>>     # ifdef  __cplusplus
>>     extern "C"
>>     # endif
>>     void *alloca (size_t);
>>     #endif

> What we use now is a shorter version what the autoconf manual
> recommends.  Could you ask the autoconf guys about this, and post the
> solution here?  That would help fix the same problem for other
> programs, not only for emacs.

The manual version is indeed bogus.  It assumes that if __GNUC__ is
defined, then __builtin_alloca() is always ok.  I'll try to contact the
autoconf people.  In the meantime the patch seems to have fixed the
alloca() warnigns on FreeBSD.  I'll keep it in my personal patch queue:

  http://bitbucket.org/keramida/emacs-bsd-patches/src/tip/patch-alloca
  http://bitbucket.org/keramida/emacs-bsd-patches/src/tip/patch-alloca-regen

So when the autoconf people reply I'll followup with more details.

Thanks,
Giorgos