cannam@154: # ===========================================================================
cannam@154: #   Modified from https://www.gnu.org/software/autoconf-archive/ax_add_fortify_source.html
cannam@154: # ===========================================================================
cannam@154: #
cannam@154: # SYNOPSIS
cannam@154: #
cannam@154: #   AX_ADD_FORTIFY_SOURCE
cannam@154: #
cannam@154: # DESCRIPTION
cannam@154: #
cannam@154: #   Check whether -D_FORTIFY_SOURCE=2 can be added to CFLAGS without macro
cannam@154: #   redefinition warnings. Some distributions (such as Gentoo Linux) enable
cannam@154: #   _FORTIFY_SOURCE globally in their compilers, leading to unnecessary
cannam@154: #   warnings in the form of
cannam@154: #
cannam@154: #     <command-line>:0:0: error: "_FORTIFY_SOURCE" redefined [-Werror]
cannam@154: #     <built-in>: note: this is the location of the previous definition
cannam@154: #
cannam@154: #   which is a problem if -Werror is enabled. This macro checks whether
cannam@154: #   _FORTIFY_SOURCE is already defined, and if not, adds -D_FORTIFY_SOURCE=2
cannam@154: #   to CFLAGS.
cannam@154: #
cannam@154: # LICENSE
cannam@154: #
cannam@154: #   Copyright (c) 2017 David Seifert <soap@gentoo.org>
cannam@154: #
cannam@154: #   Copying and distribution of this file, with or without modification, are
cannam@154: #   permitted in any medium without royalty provided the copyright notice
cannam@154: #   and this notice are preserved.  This file is offered as-is, without any
cannam@154: #   warranty.
cannam@154: 
cannam@154: #serial 1
cannam@154: 
cannam@154: AC_DEFUN([AX_ADD_FORTIFY_SOURCE],[
cannam@154:     AC_MSG_CHECKING([whether to add -D_FORTIFY_SOURCE=2 to CFLAGS])
cannam@154:     AC_LINK_IFELSE([
cannam@154:         AC_LANG_SOURCE(
cannam@154:             [[
cannam@154:                 int main() {
cannam@154:                 #ifndef _FORTIFY_SOURCE
cannam@154:                     return 0;
cannam@154:                 #else
cannam@154:                     this_is_an_error;
cannam@154:                 #endif
cannam@154:                 }
cannam@154:             ]]
cannam@154:         )], [
cannam@154:             AC_MSG_RESULT([yes])
cannam@154:             CFLAGS="$CFLAGS -D_FORTIFY_SOURCE=2"
cannam@154:         ], [
cannam@154:             AC_MSG_RESULT([no])
cannam@154:     ])
cannam@154: ])