https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98122
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:43e84ce7d62be121445e17cc0ee009a81fb285d7 commit r11-5755-g43e84ce7d62be121445e17cc0ee009a81fb285d7 Author: Jakub Jelinek <ja...@redhat.com> Date: Sat Dec 5 01:30:08 2020 +0100 c++: Fix constexpr access to union member through pointer-to-member [PR98122] We currently incorrectly reject the first testcase, because cxx_fold_indirect_ref_1 doesn't attempt to handle UNION_TYPEs. As the second testcase shows, it isn't that easy, because I believe we need to take into account the active member and prefer that active member over other members, because if we pick a non-active one, we might reject valid programs. 2020-12-05 Jakub Jelinek <ja...@redhat.com> PR c++/98122 * constexpr.c (cxx_union_active_member): New function. (cxx_fold_indirect_ref_1): Add ctx argument, pass it through to recursive call. Handle UNION_TYPE. (cxx_fold_indirect_ref): Add ctx argument, pass it to recursive calls and cxx_fold_indirect_ref_1. (cxx_eval_indirect_ref): Adjust cxx_fold_indirect_ref calls. * g++.dg/cpp1y/constexpr-98122.C: New test. * g++.dg/cpp2a/constexpr-98122.C: New test.
