https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121351
--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-15 branch has been updated by Patrick Palka <ppa...@gcc.gnu.org>: https://gcc.gnu.org/g:9faa21a4de2b88366e363b6817ee751ea8d13f53 commit r15-10209-g9faa21a4de2b88366e363b6817ee751ea8d13f53 Author: Patrick Palka <ppa...@redhat.com> Date: Mon Aug 4 16:51:00 2025 -0400 c++: constrained memfn vs corresponding using [PR121351] The b.f(42) calls in the below testcases started to get rejected as ambiguous after r15-3740 which corrected our inheritedness tiebreaker to only apply to constructors (and not all member functions) as per CWG2273. But arguably these calls should still be valid regardless of the tiebreaker because B::f corresponds to and therefore hides A::f, so there should only be a single candidate in the first place. This doesn't happen because when determining correspondence we compare the members' uninstantiated constraints instead of their partially substituted constraints as in other declaration matching situations. It doesn't really make sense to compare uninstantiated constraints from two different template contexts. This patch fixes this by substituting in outer template arguments before comparing constraints of two potentially corresponding member functions. PR c++/121351 PR c++/119859 gcc/cp/ChangeLog: * class.cc (add_method): Substitute outer template arguments into constraints before comparing them if the declarations are from different classes. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/concepts-using5.C: New test. * g++.dg/cpp2a/concepts-using5a.C: New test. Reviewed-by: Jason Merrill <ja...@redhat.com> (cherry picked from commit b9f1cc4e119da9205cb8438f0132c62a19afe4ae)
