ref: 4923e0b8fa44d5b3118f0837be12d406202106f7
dir: /m4/ax_add_fortify_source.m4/
# ===========================================================================
# Modified from https://www.gnu.org/software/autoconf-archive/ax_add_fortify_source.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_ADD_FORTIFY_SOURCE
#
# DESCRIPTION
#
# Check whether -D_FORTIFY_SOURCE=2 can be added to CFLAGS without macro
# redefinition warnings. Some distributions (such as Gentoo Linux) enable
# _FORTIFY_SOURCE globally in their compilers, leading to unnecessary
# warnings in the form of
#
# <command-line>:0:0: error: "_FORTIFY_SOURCE" redefined [-Werror]
# <built-in>: note: this is the location of the previous definition
#
# which is a problem if -Werror is enabled. This macro checks whether
# _FORTIFY_SOURCE is already defined, and if not, adds -D_FORTIFY_SOURCE=2
# to CFLAGS.
#
# LICENSE
#
# Copyright (c) 2017 David Seifert <soap@gentoo.org>
#
# Copying and distribution of this file, with or without modification, are
# permitted in any medium without royalty provided the copyright notice
# and this notice are preserved. This file is offered as-is, without any
# warranty.
#serial 1
AC_DEFUN([AX_ADD_FORTIFY_SOURCE],[
AC_MSG_CHECKING([whether to add -D_FORTIFY_SOURCE=2 to CFLAGS])
AC_LINK_IFELSE([
AC_LANG_SOURCE(
[[
int main() {
#ifndef _FORTIFY_SOURCE
return 0;
#else
this_is_an_error;
#endif
}
]]
)], [
AC_MSG_RESULT([yes])
CFLAGS="$CFLAGS -D_FORTIFY_SOURCE=2"
], [
AC_MSG_RESULT([no])
])
])