https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121575
--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:cc85998ba7984e43c1d89d47dfbfc219c142fddf commit r16-3429-gcc85998ba7984e43c1d89d47dfbfc219c142fddf Author: Jakub Jelinek <ja...@redhat.com> Date: Thu Aug 28 10:46:51 2025 +0200 c++: Fix ICE with parameter uses in expansion stmts [PR121575] The following testcase shows an ICE when a parameter of a non-template function is referenced in expansion stmt body. tsubst_expr in that case assumes that either the PARM_DECL has registered local specialization, or is this argument or it is in unevaluated context. Parameters are always defined outside of the expansion statement for-range-declaration or body, so for the instantiation of the body outside of templates should always map to themselves. It could be fixed by registering local self-specializations for all the function parameters, but just handling it in tsubst_expr seems to be easier and less costly. Some PARM_DECLs, e.g. from concepts, have NULL DECL_CONTEXT, those are handled like before (and assert it is unevaluated operand), for others this checks if the PARM_DECL is from a non-template and in that case it will just return t. 2025-08-28 Jakub Jelinek <ja...@redhat.com> Jason Merrill <ja...@redhat.com> PR c++/121575 * pt.cc (tsubst_expr) <case PARM_DECL>: If DECL_CONTEXT (t) isn't a template return t for PARM_DECLs without local specialization. * g++.dg/cpp26/expansion-stmt20.C: New test.
