https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102984
--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to Jonathan Wakely from comment #5) > This is probably the _Temporary_value helper used by std::vector. Nope, that uses a correctly-aligned buffer. The misaligned object is the default-initialized rvalue created here: locks.push_back(spinlock()); There is nothing libstdc++ can do here, that misaligned object is created by the compiler before any libstdc++ sees it. However, I'm unable to reproduce this with 11.1 or any other version.