fixed bug #745

(resolving fields of reduced subselect)

mysql-test/r/subselect.result

@@ -1172,3 +1172,6 @@ a	b
 test	test
 test1	test1
 drop table if exists t1;
+(SELECT 1 as a) UNION (SELECT 1) ORDER BY (SELECT a+0);
+a
+1

mysql-test/t/subselect.test

@@ -763,3 +763,5 @@ CREATE TABLE `t1` (
 INSERT INTO t1 (id,pseudo,email) VALUES (1,'test','test'),(2,'test1','test1');
 SELECT pseudo as a, pseudo as b FROM t1 GROUP BY (SELECT a) ORDER BY (SELECT id*1);
 drop table if exists t1;
+
+(SELECT 1 as a) UNION (SELECT 1) ORDER BY (SELECT a+0);

sql/sql_union.cc

@@ -344,7 +344,8 @@ int st_select_lex_unit::exec()
       if (select_limit_cnt == HA_POS_ERROR)
 	thd->options&= ~OPTION_FOUND_ROWS;
       fake_select->ftfunc_list= &empty_list;
-
+      fake_select->table_list.link_in_list((byte *)&result_table_list,
+					   (byte **)&result_table_list.next);
       res= mysql_select(thd, &ref_pointer_array, &result_table_list,
 			0, item_list, NULL,
 			global_parameters->order_list.elements,