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Re: alloca.h example in the manual
From: |
Eric Blake |
Subject: |
Re: alloca.h example in the manual |
Date: |
Tue, 07 Sep 2010 14:51:23 -0600 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.8) Gecko/20100806 Fedora/3.1.2-1.fc13 Mnenhy/0.8.3 Thunderbird/3.1.2 |
On 09/07/2010 12:55 PM, Giorgos Keramidas wrote:
Hi all,
The Autoconf manual (section 5.5.2, "Particular Function Checks")
recommends the following check for source files that use the alloca()
function:
Which version of the manual are you looking at? This issue was recently
reported; are there still issues beyond what was mentioned in this thread?
http://lists.gnu.org/archive/html/bug-autoconf/2010-08/msg00035.html
In particular, could you demonstrate an actual sample program and
compiler output that backs up your point, as requested in:
http://lists.gnu.org/archive/html/bug-autoconf/2010-08/msg00042.html
The modified version shown below declares a prototype of alloca() only
when HAVE_ALLOCA is unset/undefined regardless of what HAVE_ALLOCA_H is
set to:
#ifdef HAVE_ALLOCA_H
# include<alloca.h>
#elif !defined(HAVE_ALLOCA)
# if 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
#endif
Then again, since AC_FUNC_ALLOCA does indeed set HAVE_ALLOCA via
AC_DEFINE, your patch proposal probably makes sense.
--
Eric Blake address@hidden +1-801-349-2682
Libvirt virtualization library http://libvirt.org