https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68908
--- Comment #13 from Martin Sebor <msebor at gcc dot gnu.org> --- (In reply to Marek Polacek from comment #10) C doesn't allow the atomic_fetch_xxx operations to be used with the atomic_bool type (it says they're "not applicable" without spelling what that means, but that will be the subject of a future defect; IMO, it should be a constraint and require an error). If GCC accepts it, it should be changed to either reject it or at least issue a warning.