https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92268
--- Comment #9 from Jason Merrill <jason at gcc dot gnu.org> --- Author: jason Date: Thu Oct 31 02:01:16 2019 New Revision: 277654 URL: https://gcc.gnu.org/viewcvs?rev=277654&root=gcc&view=rev Log: PR c++/92268 - hard error satisfying return-type-requirement Previously we would put the template arguments for the concept-check in a TEMPLATE_ID and then also pass them to constraints_satisfied_p, which meant that we would try to normalize the concept-check with the fully instantiated arguments, leading to sadness. Simply not passing the args to constraints_satisfied_p fixes the problem. I also noticed that we weren't detecting substitution failure in the constraints, but were silently treating it as success. * constraint.cc (type_deducible_p): Check for substitution failure. (diagnose_compound_requirement): Adjust diagnostic. * pt.c (do_auto_deduction): Don't pass cargs to constraints_satisfied_p. Added: trunk/gcc/testsuite/g++.dg/cpp2a/concepts-return-req1.C Modified: trunk/gcc/cp/ChangeLog trunk/gcc/cp/constraint.cc trunk/gcc/cp/pt.c trunk/gcc/testsuite/g++.dg/concepts/diagnostic1.C trunk/gcc/testsuite/g++.dg/concepts/placeholder3.C trunk/gcc/testsuite/g++.dg/concepts/placeholder4.C trunk/gcc/testsuite/g++.dg/cpp2a/concepts-pr67178.C trunk/gcc/testsuite/g++.dg/cpp2a/concepts-requires6.C
