https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93862
--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> --- I have a patch but both (2) and (3) are invalid, see <https://gcc.gnu.org/ml/gcc-patches/2019-10/msg00433.html>. (icc also rejects it.)