Check whether -D_FORTIFY_SOURCE=2 can be added to CPPFLAGS without macro redefinition warnings, other cpp warnings or linker. 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 CPPFLAGS.
Newer mingw-w64 msys2 package comes with a bug in headers-git-18.104.22.16846.d200317d-1. It broke -D_FORTIFY_SOURCE support, and would need -lssp or -fstack-protector. See https://github.com/msys2/MINGW-packages/issues/5803. Try to actually link it.
Download the latest version of ax_add_fortify_source.m4 or browse the macro’s revision history.
Copyright © 2017 David Seifert email@example.com
Copyright © 2019 Reini Urban firstname.lastname@example.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.