https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105233
--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Sure, but while for alignas it is the standard that makes it clear, for the attributes it is up to us to decide what to do. Jason said he'd like for GCC 13 us to try making all attribute arguments manifestly const eval and see how far we get with that. As for your #c9 testcase, there is an easy workaround, just add a constexpr var (or static data member etc.) with the value, that will make it clearly manifestly constant evaluated and will work even with older compilers.
