> From: Paul Smith <psm...@gnu.org> > Cc: bug-make@gnu.org > Date: Mon, 12 Jul 2010 09:19:42 -0400 > > On Mon, 2010-07-12 at 10:20 +0300, Eli Zaretskii wrote: > > > This change: > > > > > > 2009-10-03 Paul Smith <psm...@gnu.org> > > > > > > * make.h: Include <alloca.h> even on systems where __GNUC__ is > > > defined. Not sure why it was done the other way. > > > Requested by David Boyce <d...@boyski.com>. > > > > > > Causes multiple warnings on systems that use GCC, but do not use glibc > > > (glibc has the alloca.h header, which makes it skip all this fragment): > > > > > > on Windows: > > > In file included from arscan.c:19: > > > make.h:39: warning: conflicting types for built-in function 'alloca' > > > > > > on DOS: > > > In file included from make.h:202, > > > from ar.c:19: > > > d:/usr/djgpp/include/stdlib.h:85: error: conflicting types for > > > 'alloca' > > > make.h:39: error: previous declaration of 'alloca' was here > > > > > > I think that having a declaration for `alloca' in make.h is a bad > > > idea, because there's no way we can guess the right way of declaring > > > it. > > > > > > What was the motivation for David's request? > > I poked around but I can't remember and I don't have any email related > to it.
Too bad. But since we have David here (CC'ed), maybe he remembers his motivation? > > > I suggest the following patch, which should DTRT on GNU/Linux and on > > > other platforms alike: > > > > > > 2010-07-09 Eli Zaretskii <e...@gnu.org> > > > > > > * make.h (alloca) [!__GNUC__]: Don't define prototype. > > > > > > --- make.h~0 2010-07-01 11:43:31.000000000 +0300 > > > +++ make.h 2010-07-09 12:02:02.034125000 +0300 > > > @@ -35,8 +35,10 @@ > > > # ifdef _AIX > > > #pragma alloca > > > # else > > > -# ifndef alloca /* predefined by HP cc +Olibcalls */ > > > +# ifndef __GNUC__ > > > +# ifndef alloca /* predefined by HP cc +Olibcalls */ > > > char *alloca (); > > > +# endif > > > # endif > > > # endif > > > #endif > > To be honest I'm a little lost as to what the problem is or why this > fixes it The problem is that GCC has alloca as a built-in. On GNU/Linux, glibc comes with a alloca.h header whose definition of alloca matches the built-in. But on systems that don't use glibc, the system headers don't have a prototype for alloca, and the one provided by make.h has a 99.9% chance of being in conflict with the GCC built-in. We could try to second-guess GCC, but it's not needed: a built-in function does not need to be declared. So it's much easier to not define a prototype when GCC is in use then define it correctly for every possible version of GCC. > but if it works I'm OK with it. Thanks, I will commit that change, unless David objects. > Is this the right return type though? Wouldn't it be void*? I have no idea. You will see that I didn't touch that line in the patch, precisely because I don't know what is correct and for which platform(s). _______________________________________________ Bug-make mailing list Bug-make@gnu.org http://lists.gnu.org/mailman/listinfo/bug-make
