Re: [PATCH v3 01/11] ldbl-128ibm-compat: Fix selection of GNU and ISO C99 scanf

[Paul E Murphy <murphyp at linux dot ibm dot com>]

On 12/9/19 10:49 AM, Zack Weinberg wrote:
> On Mon, Dec 9, 2019 at 11:46 AM Paul E Murphy <murphyp@linux.ibm.com> wrote:
> > On 12/3/19 11:05 AM, Gabriel F. T. Gomes wrote:
> > > From: "Gabriel F. T. Gomes" <gabrielftg@linux.ibm.com>
> > >
> > > New since v2.
> > >
> > > -- 8< --
> > > Since commit
> > >
> > > commit 03992356e6fedc5a5e9d32df96c1a2c79ea28a8f
> > > Author: Zack Weinberg <zackw@panix.com>
> > > Date:   Sat Feb 10 11:58:35 2018 -0500
> > >
> > >       Use C99-compliant scanf under _GNU_SOURCE with modern compilers.
> > >
> > > the selection of the GNU versions of scanf functions requires both
> > > _GNU_SOURCE and -std=c89.  This patch changes the tests in
> > > ldbl-128ibm-compat so that they actually test the GNU versions (without
> > > this change, the redirection to the ISO C99 version always happens, so
> > > GNU versions of the new implementation (e.g. __scanfieee128) were left
> > > untested).
> >
> > Good catch Zach, thanks.
>
> Credit is actually due to Gabriel; if I understand correctly, I
> _introduced_ a bug here!
>
> zw

I stand corrected.  I wonder how frail some of these tests might become 
as they age.  Is framework available today to verify tests are linking 
against the desired variants of a symbol?