https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115656
--- Comment #8 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Patrick Palka <ppa...@gcc.gnu.org>: https://gcc.gnu.org/g:2861eb34e30973cb991a7964af7cfeae014a98b0 commit r15-2230-g2861eb34e30973cb991a7964af7cfeae014a98b0 Author: Patrick Palka <ppa...@redhat.com> Date: Tue Jul 23 13:16:14 2024 -0400 c++: normalizing ttp constraints [PR115656] Here we normalize the constraint same_as<T, bool> for the first time during ttp coercion of B / UU, specifically constraint subsumption checking. During this normalization the set of in-scope template parameters i.e. current_template_parms is empty, which we rely on during normalization of the ttp constraints since we pass in_decl=NULL_TREE to norm_info. And this tricks the satisfaction cache into thinking that the satisfaction value of same_as<T, bool> is independent of its template parameters, and we incorrectly conflate the satisfaction value with T = bool vs T = long and accept the specialization A<long, B>. Since is_compatible_template_arg rewrites the ttp's constraints to be in terms of the argument template's parameters, and since it's the only caller of weakly_subsumes, the latter funcion can instead pass in_decl=tmpl to avoid relying on current_template_parms. This patch implements this, and in turns renames weakly_subsumes to ttp_subsumes to reflect that this predicate is now hardcoded for this one caller. PR c++/115656 gcc/cp/ChangeLog: * constraint.cc (weakly_subsumes): Pass in_decl=tmpl to get_normalized_constraints_from_info. Rename to ... (ttp_subsumes): ... this. * cp-tree.h (weakly_subsumes): Rename to ... (ttp_subsumes): ... this. * pt.cc (is_compatible_template_arg): Adjust after renaming. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/concepts-ttp7.C: New test. Reviewed-by: Jason Merrill <ja...@redhat.com>
