[RFC] libstdc++: Make --enable-libstdcxx-backtrace=auto default to yes

[Hans-Peter Nilsson]

> Date: Fri, 1 Sep 2023 12:16:40 +0100
> Reply-To: Jonathan Wakely <jwakely@redhat.com>
> 
> On Wed, 23 Aug 2023 at 17:03, Jonathan Wakely via Libstdc++
> <libstdc++@gcc.gnu.org> wrote:
> >
> > Any objections to this? It's a C++23 feture, so should be enabled by
> > default.
> 
> I've pushed this to trunk, so let's see what breaks!
> 
> 
> >
> > -- >8 --
> >
> > This causes libstdc++_libbacktrace.a to be built by default. This might
> > fail on some targets, in which case we can make the 'auto' choice expand
> > to either 'yes' or 'no' depending on the target.
> >
> > libstdc++-v3/ChangeLog:
> >
> >         * acinclude.m4 (GLIBCXX_ENABLE_BACKTRACE): Default to yes.
> >         * configure: Regenerate.

Incidentally, should check_effective_target_stacktrace in
libstdc++.exp also be adjusted to match; removing the
_GLIBCXX_HOSTED condition?

brgds, H-P