b2/lang.y (part): show part ID in error message

b2/lang.y

@@ -426,7 +426,8 @@ part:
 		{
 			$$ = part_add($1, $2);
 			if ($$->param)
-				yyerror("parameters already defined");
+				yyerrorf("%s %s parameters already defined",
+				    $1, $2);
 			$$->param = $3;
 		}
 	;