https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97093
--- Comment #2 from CVS 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:904ac8577521b8152b97e9b549c1a1ca569a3d1f commit r11-5798-g904ac8577521b8152b97e9b549c1a1ca569a3d1f Author: Patrick Palka <ppa...@redhat.com> Date: Sat Dec 5 13:47:22 2020 -0500 c++: Distinguish unsatisfaction vs errors during satisfaction [PR97093] During satisfaction, the flag info.noisy() controls three things: whether to diagnose ill-formed satisfaction (such as the satisfaction value of an atom being non-bool or non-constant); whether to diagnose unsatisfaction; and whether to bypass the satisfaction cache. The flag turns out to be too coarse however, because in some cases we want to diagnose ill-formed satisfaction (and bypass the satisfaction cache) but not diagnose unsatisfaction, for instance when replaying an erroneous satisfaction result from constraint_satisfaction_value, evaluate_concept_check and tsubst_nested_requirement. And when noisily evaluating a disjunction, we want to first evaluate its branches noisily (bypassing the satisfaction cache) but suppress unsatisfaction diagnostics. We currently work around this by instead first evaluating each branch quietly, but that means the recursive calls to satisfy_atom will use the satisfaction cache. To fix this, this patch adds the info.diagnose_unsatisfaction_p() flag, which refines the info.noisy() flag as part of a new sat_info class that derives from subst_info. During satisfaction, info.noisy() now controls whether to diagnose ill-formed satisfaction, and info.diagnose_unsatisfaction_p() controls whether to additionally diagnose unsatisfaction. This enables us to address the above two issues straightforwardly. Incidentally, the change to satisfy_disjunction suppresses the ICE in the PR97093 testcase because we no longer insert atoms into the satisfaction cache that have been incorrectly re-normalized in diagnose_nested_requirement (after losing the necessary template context). But the underlying re-normalization issue remains, and will be fixed in a subsequent patch. gcc/cp/ChangeLog: PR c++/97093 * constraint.cc (struct sat_info): Define. (tsubst_nested_requirement): Pass a sat_info object to satisfy_constraint. (satisfy_constraint_r): Take a sat_info argument instead of subst_info. (satisfy_conjunction): Likewise. (satisfy_disjunction): Likewise. Instead of first evaluating each branch quietly, evaluate each branch only with unsatisfaction diagnostics disabled. Exit early if evaluation of a branch returns error_mark_node. (satisfy_atom): Take a sat_info argument instead of subst_info. Fix a comment. Check diagnose_unsatisfaction_p() instead of noisy() before replaying a substitution failure. (satisfy_constraint): Take a sat_info argument instead of subst_info. (satisfy_associated_constraints): Likewise. (satisfy_constraint_expression): Likewise. (satisfy_declaration_constraints): Likewise. (constraint_satisfaction_value): Likewise and adjust accordingly. Fix formatting. (constraints_satisfied_p): Pass a sat_info object to constraint_satisfaction_value. (evaluate_concept_check): Pass a sat_info object to satisfy_constraint_expression. (diagnose_nested_requirement): Likewise. (diagnose_constraints): Pass an appropriate sat_info object to constraint_satisfaction_value. gcc/testsuite/ChangeLog: PR c++/97093 * g++.dg/concepts/pr94252.C: Verify we no longer issue a spurious unsatisfaction note when diagnosing ill-formed satisfaction. * g++.dg/cpp2a/concepts-requires18.C: No longer expect a spurious unsatisfaction diagnostic when evaluating the nested-requirement subst<void&> of a requires-expression that appears outside of a template. * g++.dg/cpp2a/concepts-requires21.C: Verify we no longer issue a spurious unsatisfaction note when evaluating a nested-requirement of a requires-expression that appears outside of a template. * g++.dg/cpp2a/concepts-nonbool3.C: New test. * g++.dg/cpp2a/concepts-pr97093.C: New test.
