https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124070
--- Comment #7 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <[email protected]>: https://gcc.gnu.org/g:cb617bedc8fe8008980841e019f7bddd1cc296ee commit r16-7582-gcb617bedc8fe8008980841e019f7bddd1cc296ee Author: Jakub Jelinek <[email protected]> Date: Thu Feb 19 07:55:38 2026 +0100 c++: Fix up convert_nontype_argument [PR124070] Some of the following testcases are incorrectly accepted. The problem is in convert_nontype_argument. It just does maybe_constant_value earlier. Later on for integral/enum/floating point args it uses cxx_constant_value for complain & tf_error if not val_dep_p and expr is not a simple constant, similarly for class type it calls /* Replace the argument with a reference to the corresponding template parameter object. */ if (!val_dep_p) expr = create_template_parm_object (expr, complain); if (expr == error_mark_node) return NULL_TREE; etc. But for NULLPTR_TYPE_P and REFLECTION_TYPE_P cases (I bet Marek has based the latter on the former) it only verifies the type and not the actual expression. I think we need to do that, because if maybe_constant_value fails, it just returns the passed in argument and if nothing checks it, we accept whatever was there (and sometimes ICE later). The following patch implements that. 2026-02-19 Jakub Jelinek <[email protected]> PR c++/124070 * pt.cc (convert_nontype_argument): For NULLPTR_TYPE_P case if expr is not integer_zerop and is not val_dep_p try harder, for complain & tf_error use cxx_constant_value and return NULL_TREE for error_mark_node, without tf_error return NULL_TREE. Similarly for REFLECTION_TYPE_P case if expr is not REFLECT_EXPR and is not val_dep_p try harder like for NULLPTR_TYPE_P. * g++.dg/cpp26/pr124070.C: New test. * g++.dg/reflect/parameters_of4.C: Expect different diagnostics. * g++.dg/reflect/define_aggregate7.C: New test. * g++.dg/reflect/define_aggregate8.C: New test.
