https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100101
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> --- In particular it is the TYPENAME_TYPE type seen in bar's noexcept expression. Does find_typenames_r ever want to walk into expressions? I.e. couldn't the fix be if (EXPR_P (*tp)) *walk_subtrees = 0; ?