https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116455
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |INVALID Status|UNCONFIRMED |RESOLVED --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Libc++ does not define it as constexpr either. https://github.com/llvm/llvm-project/blob/8e0b9c85924ca22a65d57988ea2c5c22a5181ed9/libcxx/include/__coroutine/noop_coroutine_handle.h#L91 So yes gcc is following the standard.