https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89303
--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #8)
> (In reply to Richard Biener from comment #5)
> > GIMPLE at -O1 looks OK-ish - release on all paths:
>
> But release decrements the weak_count, and only calls _M_destroy() if the
> count reaches zero.
>
> The attachment in comment 7 removes all the atomics and still shows the same
> problem.
Compiling it with -DFIXME adds:
else __builtin_puts("null");
in _M_weak_release(), and that fixes it despite that else branch never actually
being taken. Just the presence of I/O appears to prevent that function being
misoptimized.
