[PATCH] libstdc++: Make forward_list::sort exception-safe [PR124051]

[Jonathan Wakely]

On Sun, 16 Aug 2026 at 20:43 +0000, Odysseas Georgoudis wrote:
>If a comparison called by forward_list::sort throws, the current
>implementation can leave the list corrupted, which may cause a later
>crash.
>
>This patch restores valid links before allowing the same exception to
>continue.  The element order remains unspecified, as permitted by the
>standard, while iterators and references remain valid.
>
>Tested on x86_64-pc-linux-gnu.
>
>Thanks,
>Odysseas

Thanks for the patch to fix this.

Have you tested whether this affects performance of the sort function?
I hope it doesn't make much difference.

Please don't attach patches as application/octet-stream - patches are
plain text, not binary data. It makes it hard to review the patch by
replying inline.

Please read
https://gcc.gnu.org/onlinedocs/libstdc++/manual/test.html#test.new_tests
and adjust the new test accordingly. Based on the copyright notice in
the test, it seems likely this was produced with the assistance of an
LLM, is that correct?