check_subexp_matching_top
err = check_subexp_matching_top (mctx, &cur_state->nodes, 0);
static reg_errcode_t check_subexp_matching_top (re_match_context_t *mctx,
*err = check_subexp_matching_top (mctx, &next_state->nodes,
err = check_subexp_matching_top (mctx, new_dest_nodes,