Re: [Ping][PATCH] libstdc++: Add missing functions to <cmath> [PR79700]

[Jonathan Wakely <jwakely@redhat.com>]

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On Wed, 17 May 2023 at 09:37, Nathaniel Shead wrote:

> Now that GCC13.1 is released is it ok to merge? Thanks!
>

Yes, I've been testing this locally, but I think it needs more work (sorry!)

Looking at it again, I'm not sure why I asked for the additional tests
because if they fail, it's a problem in libc, and there's nothing we can
actually do about it in libstdc++. We certainly do want std::expl(0.0L) to
return the same thing as std::exp(0.0L), but if it doesn't, we'll just have
a libstdc++ test failure caused by a bug in libc. But you wrote the test
now, so let's keep it. If we get failures for the test it will allow us to
inform the relevant libc maintainers that they have a bug.

Also, since you're contributing this under the DCO terms the new test
should not have the FSF copyright header, unless it's a derived work of an
existing test with that header (and in that case it should retain the dates
from the copied test). I don't actually bother putting the copyright and
license header on new tests these days. There's nothing in that test that
is novel or interesting, and I think it's arguably not useful or meaningful
to consider it copyrighted.

Finally, and most importantly, the new using-declarations in <cmath> are
not guarded by any autoconf macro. That will break targets without full C99
<math.h> support, e.g. djgpp declares acosf but not acosl, so the new
"using acosl;" would be a hard error as soon as <cmath> is included (and
might even prevent GCC building on that target). So I think we need a new
autoconf check for the existence of those functions. I'm in the process of
reworking the autoconf macros for <cmath> (due to PR 109818), which is why
I didn't address it for this patch yet.



>
> On Tue, Apr 18, 2023 at 6:48 PM Jonathan Wakely <jwakely@redhat.com>
> wrote:
> >
> > On Mon, 17 Apr 2023 at 09:11, Nathaniel Shead <nathanieloshead@gmail.com>
> wrote:
> > >
> > > Hi, just checking whether there were any issues with this patch?
> > > https://gcc.gnu.org/pipermail/gcc-patches/2023-February/612386.html
> > >
> > > Otherwise I assume it won't be in GCC13.
> >
> > That's right, it's too large and invasive a change to get into GCC 13
> > when only submitted in February, sorry. I'll merge it to trunk once
> > GCC 13.1 is released though.
> >
>
>