[PATCH] Use C99-compliant scanf under _GNU_SOURCE with C99/C++11 and higher.

[Zack Weinberg]

On Mon, Dec 17, 2018 at 11:56 AM Andreas Schwab <schwab@suse.de> wrote:
> On Dez 17 2018, Zack Weinberg <zackw@panix.com> wrote:
>
> > On a related note, the interaction of the C99/not-C99 scanf redirect
> > with the __LDBL_COMPAT scanf redirect was complicated, confusing,
> > and possibly wrong.  The __ldbl_is_dbl cleanup (thanks to Gabriel
> > Gomes for finishing that for me) has made it less complicated, but
> > I'm still not 100% sure it's correct, and I do not have access to
> > physical hardware for which __LDBL_COMPAT is relevant, so my ability
> > to test it is limited.  Careful review (you'll want to read all of
> > libio/bits/stdio-ldbl.h to understand what's going on, not just
> > the diff) and maybe even some volunteer testing would be appreciated.
>
> I have started a test build of your branch in
> <https://build.opensuse.org/package/show/home:Andreas_Schwab:glibc:test/glibc>.
>
> [  881s] In file included from <command-line>:
> [  881s] ../sysdeps/ieee754/ldbl-opt/nldbl-sscanf.c:17:23: error: '_IO_sscanf' aliased to undefined symbol 'sscanf'
> [  881s]  strong_alias (sscanf, _IO_sscanf)
> [  881s]                        ^~~~~~~~~~

Argh.  I will throw the patch at my local build-many-glibcs setup and
hopefully that will let me reproduce this problem and fix it.  Thanks.

zw