Re: [PATCH RFC] c++: use __cxa_call_terminate for MUST_NOT_THROW [PR97720]

[Jakub Jelinek <jakub@redhat.com>]

On Fri, Jun 09, 2023 at 11:02:48AM +0200, Richard Biener via Gcc-patches wrote:
> > Currently both gcc-13 and trunk are at the same library version,
> > libstdc++.so.6.0.32
> >
> > But with this addition to trunk we need to bump that .32 to .33, meaning
> > that gcc-13 and trunk diverge. If we want to backport any new symbols from
> > trunk to gcc-13 that gets trickier once they've diverged.
> 
> But if you backport any new used symbol you have to bump the version
> anyway.  So why not bump now (on trunk)?

We've already done that in 13.1.1.  So, before 13.2 is released, we can add
further symbols to the GLIBCXX_3.4.32 symbol version.
Though, I don't see a problem bumping libstdc++ to libstdc++.so.6.0.33
on the trunk now and put __cxa_call_terminate to GLIBCXX_3.4.33.
The ABI on the trunk is certainly not stable at this point.
If we come up with a need to introduce another symbol to 13.2, we can just
add it to GLIBCXX_3.4.32 on the trunk and then backport that change to the
branch.  If nothing in 13 will use the new symbol, seems like a waste to add
it to libstdc++.so.6.0.32.

> > If we added __cxa_call_terminate to gcc-13, making it another new addition
> > to libstdc++.so.6.0.32, then it would simplify a few things.
> >
> > In theory it could be a problem for distros already shipping gcc-13.1.1
> > with that new libstdc++.so.6.0.32 version, but since the
> > __cxa_call_terminate symbol won't actually be used by the gcc-13.1.1
> > compilers, I don't think it will be a problem.

	Jakub