Re: [PATCH] Add -D_FORTIFY_SOURCE=2 to CFLAGS if possible.

[Mike Frysinger <vapier at gentoo dot org>]

On 09 Feb 2017 21:13, Mark Wielaard wrote:
> +# See if we can add -D_FORTIFY_SOURCE=2. Don't do it if it is already
> +# (differently) defined or if it generates warnings/errors because we
> +# don't use the right optimisation level (string.h will warn about that).
> +AC_MSG_CHECKING([whether to add -D_FORTIFY_SOURCE=2 to CFLAGS])

-D flags should be in CPPFLAGS ...

> +case "$CFLAGS" in
> +  *-D_FORTIFY_SOURCE=2*)
> +    AC_MSG_RESULT([no, already there])
> +    ;;
> +  *)
> +    save_CFLAGS="$CFLAGS"
> +    CFLAGS="-D_FORTIFY_SOURCE=2 -Werror $CFLAGS"
> +    AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
> +      #include <string.h>
> +      int main() { return 0; }
> +    ]])], [ AC_MSG_RESULT([yes])
> +            CFLAGS="-D_FORTIFY_SOURCE=2 $save_CFLAGS" ],
> +          [ AC_MSG_RESULT([no])
> +            CFLAGS="$save_CFLAGS"])
> +  ;;

why not AC_PREPROC_IFELSE and check if _FORTIFY_SOURCE is defined ?
-mike

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