Re: [PATCH] stdio-common: tests: don't double-define _FORTIFY_SOURCE

[Siddhesh Poyarekar <siddhesh@gotplt.org>]

On 2023-02-21 04:27, Sam James via Libc-alpha wrote:
> Exactly the same as 35bcb08eaa953c9b8bef6ab2486dc4361e1f26c0.
> 
> If using -D_FORITFY_SOURCE=3 (in my case, I've patched GCC to add
> =3 instead of =2 (we've done =2 for years in Gentoo)), building
> glibc tests will fail on tst-bz11319-fortify2 like:
> ```
> <command-line>: error: "_FORTIFY_SOURCE" redefined [-Werror]
> <built-in>: note: this is the location of the previous definition
> cc1: all warnings being treated as errors
> ```
> 
> It's just because we're always setting -D_FORTIFY_SOURCE=2
> rather than unsetting it first. If F_S is already 2, it's harmless,
> but if it's another value (say, 1, or 3), the compiler will bawk.
> 
> (I'm not aware of a reason this couldn't be tested with =3,
> but the toolchain support is limited for that (too new), and we want
> to run the tests everywhere possible.)
> 
> As Siddhesh noted previously, we could implement some fallback
> logic to determine the maximal F_S value supported by the toolchain,
> which is a bit easier now that autoconf-archive has been updated for F_S=3
> (https://github.com/autoconf-archive/autoconf-archive/pull/269), but let's
> revisit this if it continues to crop up.
> 
> Signed-off-by: Sam James <sam@gentoo.org>
> ---
>   stdio-common/Makefile | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

Sam, if you're going to post patches regularly enough, please consider 
asking for write access.  You could add me as a sponsor.

https://sourceware.org/cgi-bin/pdw/ps_form.cgi

Thanks,
Sid

> 
> diff --git a/stdio-common/Makefile b/stdio-common/Makefile
> index 92a3499a94..abb398fdb7 100644
> --- a/stdio-common/Makefile
> +++ b/stdio-common/Makefile
> @@ -436,7 +436,7 @@ CFLAGS-tst-gets.c += -Wno-deprecated-declarations
>   
>   # BZ #11319 was first fixed for regular vdprintf, then reopened because
>   # the fortified version had the same bug.
> -CFLAGS-tst-bz11319-fortify2.c += -D_FORTIFY_SOURCE=2
> +CFLAGS-tst-bz11319-fortify2.c += -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2
>   
>   CFLAGS-tst-memstream-string.c += -fno-builtin-fprintf
>