https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108975
--- Comment #17 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:3d674e29d7f89bf93fcfcc963ff0248c6347586d commit r14-228-g3d674e29d7f89bf93fcfcc963ff0248c6347586d Author: Patrick Palka <ppa...@redhat.com> Date: Tue Apr 25 15:59:22 2023 -0400 c++: value dependence of by-ref lambda capture [PR108975] We are still ICEing on the generic lambda version of the testcase from this PR, even after r13-6743-g6f90de97634d6f, due to the by-ref capture of the constant local variable 'dim' being considered value-dependent when regenerating the lambda (at which point processing_template_decl is set since the lambda is generic), which prevents us from constant folding its uses. Later during prune_lambda_captures we end up not thoroughly walking the body of the lambda and overlook the (non-folded) uses of 'dim' within the array bound and using-decls. We could fix this by making prune_lambda_captures walk the body of the lambda more thoroughly so that it finds these uses of 'dim', but ideally we should be able to constant fold all uses of 'dim' ahead of time and prune the implicit capture after all. To that end this patch makes value_dependent_expression_p return false for such by-ref captures of constant local variables, allowing their uses to get constant folded ahead of time. It seems we just need to disable the predicate's conservative early exit for reference variables (added by r5-5022-g51d72abe5ea04e) when DECL_HAS_VALUE_EXPR_P. This effectively makes us treat by-value and by-ref captures more consistently when it comes to value dependence. PR c++/108975 gcc/cp/ChangeLog: * pt.cc (value_dependent_expression_p) <case VAR_DECL>: Suppress conservative early exit for reference variables when DECL_HAS_VALUE_EXPR_P. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/lambda/lambda-const11a.C: New test.
