bug#28571: 25.3; Compile error on macOS Sierra

[Alan Third <alan@idiocy.org>]

On Sun, Sep 24, 2017 at 11:23:47AM +0000, Philipp Stephani wrote:
> Alan Third <alan@idiocy.org> schrieb am So., 24. Sep. 2017 um 13:07 Uhr:
> 
> > On Sun, Sep 24, 2017 at 07:49:55AM +0000, Philipp Stephani wrote:
> > > So I think the functions are there, but the compilation
> > > shouldn't use them since they would make the binary incompatible
> > > with old versions of macOS.
> >
> > I agree. I’ve attached a patch that should sort it.
> >
> 
> Thanks, the patch works, but you also need to #undef HAVE_UTIMENSAT.
> However, I'm wondering whether that's the right way to solve it. It
> means we're making some of the checks manual that have previously
> been automated, which implies that we need to recheck in the future
> whether the checks are still appropriate etc. Wouldn't it be better
> to modify configure.ac so that it doesn't detect these functions as
> present in the first place if we don't want to use them?

I can’t alter the checks directly as they’re part of gnulib (I think).
We’d have to suppress them. But that would be done by putting in a
simple check, ‘is this macOS? If yes, don’t use these functions’,
which is, IMO, no different than what the patch does.

We could get the gnulib people to fix them, but even then we’d still
want to just suppress them as we don’t want to use these functions on
macOS even if they are available due to cross‐version concerns.

If you just think the logic should be in configure.ac rather than
conf_post.h, then I think we might need to get help with how to
suppress or ignore the checks. Unless you know how.
-- 
Alan Third