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emacs/m4/realloc.m4
2023-02-25 17:13:29 -08:00

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# realloc.m4 serial 27
dnl Copyright (C) 2007, 2009-2023 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
# This is adapted with modifications from upstream Autoconf here:
# https://git.savannah.gnu.org/cgit/autoconf.git/tree/lib/autoconf/functions.m4?id=v2.70#n1455
AC_DEFUN([_AC_FUNC_REALLOC_IF],
[
AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
AC_CACHE_CHECK([whether realloc (0, 0) returns nonnull],
[ac_cv_func_realloc_0_nonnull],
[AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[[#include <stdlib.h>
]],
[[void *p = realloc (0, 0);
int result = !p;
free (p);
return result;]])
],
[ac_cv_func_realloc_0_nonnull=yes],
[ac_cv_func_realloc_0_nonnull=no],
[case "$host_os" in
# Guess yes on platforms where we know the result.
*-gnu* | freebsd* | netbsd* | openbsd* | bitrig* \
| gnu* | *-musl* | midipix* | midnightbsd* \
| hpux* | solaris* | cygwin* | mingw* | msys* )
ac_cv_func_realloc_0_nonnull="guessing yes" ;;
# If we don't know, obey --enable-cross-guesses.
*) ac_cv_func_realloc_0_nonnull="$gl_cross_guess_normal" ;;
esac
])
])
AS_CASE([$ac_cv_func_realloc_0_nonnull], [*yes], [$1], [$2])
])# AC_FUNC_REALLOC
# gl_FUNC_REALLOC_GNU
# -------------------
# Replace realloc if it is not compatible with GNU libc.
AC_DEFUN([gl_FUNC_REALLOC_GNU],
[
AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
AC_REQUIRE([gl_FUNC_REALLOC_POSIX])
if test $REPLACE_REALLOC_FOR_REALLOC_GNU = 0; then
_AC_FUNC_REALLOC_IF([], [REPLACE_REALLOC_FOR_REALLOC_GNU=1])
fi
])# gl_FUNC_REALLOC_GNU
# gl_FUNC_REALLOC_POSIX
# ---------------------
# Test whether 'realloc' is POSIX compliant (sets errno to ENOMEM when it
# fails, and doesn't mess up with ptrdiff_t overflow),
# and replace realloc if it is not.
AC_DEFUN([gl_FUNC_REALLOC_POSIX],
[
AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
AC_REQUIRE([gl_FUNC_MALLOC_POSIX])
if test $REPLACE_MALLOC_FOR_MALLOC_POSIX = 1; then
REPLACE_REALLOC_FOR_REALLOC_POSIX=1
fi
])