[Bug libstdc++/99356] Recursive std::shared_future:s with std::launch::deferred sporadically deadlock

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99356

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This is probably due to PR 97949 again, because shared_future uses call_once
internally.