https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82193
--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Just a quick note p1787 (https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p1787r6.html) moves around the place where it says no diagnostic is required but the effect is the same. it is now in [class.member.lookup]/7 (note in the draft C++23 standard it is /6). But GCC is still doing a valid diagnostic because of this. That is the standard didn't change in this area, just changed where the wording was.
