https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96159
Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords|ABI, wrong-code |documentation Ever confirmed|0 |1 Last reconfirmed| |2021-11-26 Status|UNCONFIRMED |NEW --- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> --- It assumes that because the purpose of those built-ins is to implement C _Atomic and C++ std::atomic. If you use those APIs the alignment is taken care of n by the implementation. If you use the low-level, non-portable APIs directly then you are responsible for getting it right. This is just a documentation bug.