add file location info

Author: ratmice

lrpar/src/lib/ctbuilder.rs

@@ -1464,6 +1464,8 @@ where
                         } else {
                             let mut s = String::from("\n");
                             let rule_span = grm.rule_name_span(ref_ridx);
+                            s.push_str(&diag.file_location_msg("Error", Some(rule_span)));
+                            s.push_str("\n");
                             s.push_str(&diag.underline_span_with_text(
                                 rule_span,
                                 "Rule missing action type".to_string(),