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coreutils/m4/free.m4
2003-11-05 22:47:37 +00:00

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# Check whether free (NULL) is supposed to work.
# Copyright (C) 2003 Free Software Foundation, Inc.
# This file is free software, distributed under the terms of the GNU
# General Public License. As a special exception to the GNU General
# Public License, this file may be distributed as part of a program
# that contains a configuration script generated by Autoconf, under
# the same distribution terms as the rest of that program.
# Written by Paul Eggert.
# We can't test for free (NULL) even at runtime, since it might
# happen to "work" for our test program, but not in general. So, be
# conservative and use feature tests for relatively modern hosts,
# where free (NULL) is known to work. This costs a bit of
# performance on some older hosts, but we can fix that later if
# needed.
AC_DEFUN([gl_FUNC_FREE],
[
AC_CHECK_HEADERS_ONCE(unistd.h)
AC_CACHE_CHECK([whether free (NULL) is known to work],
[gl_cv_func_free],
[AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM(
[[@%:@if HAVE_UNISTD_H
@%:@include <unistd.h>
@%:@endif]],
[[@%:@if _POSIX_VERSION < 199009L && \
(defined unix || defined _unix || defined _unix_ \
|| defined __unix || defined __unix__)
@%:@error "'free (NULL)' is not known to work"
@%:@endif]])],
[gl_cv_func_free=yes],
[gl_cv_func_free=no])])
if test $gl_cv_func_free = yes; then
AC_LIBOBJ(free)
AC_DEFINE(free, rpl_free,
[Define to rpl_free if the replacement function should be used.])
fi
])
# Prerequisites of lib/free.c.
AC_DEFUN([gl_PREREQ_FREE], [:])