[Bug libstdc++/99277] C++2a synchronisation is inefficient in GCC 11

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99277

--- Comment #18 from Jonathan Wakely <redi at gcc dot gnu.org> ---
We have not committed to a stable ABI for C++20 yet.