fixed bugs 442/443 (reduced subselect in ORDER/GROUP clauses)

mysql-test/r/subselect.result:
  test of reduced subselects in ORDER/GROUP
mysql-test/t/subselect.test:
  test of reduced subselects in ORDER/GROUP
sql/sql_select.cc:
  added reassigning temporary variable

mysql-test/r/subselect.result

@@ -1126,3 +1126,20 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ref	salary	salary	5	const	1	Using where
 2	SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
 drop table t1;
+(SELECT 1 as a) UNION (SELECT 1) ORDER BY (SELECT a+0);
+a
+1
+CREATE TABLE `t1` (
+`id` mediumint(8) unsigned NOT NULL auto_increment,
+`pseudo` varchar(35) NOT NULL default '',
+`email` varchar(60) NOT NULL default '',
+PRIMARY KEY  (`id`),
+UNIQUE KEY `email` (`email`),
+UNIQUE KEY `pseudo` (`pseudo`),
+) TYPE=MyISAM CHARSET=latin1 PACK_KEYS=1 ROW_FORMAT=DYNAMIC;
+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);
+a	b
+test	test
+test1	test1
+drop table if exists t1;

mysql-test/t/subselect.test

@@ -714,3 +714,20 @@ create table t1 (id int not null auto_increment primary key, salary int, key(sal
 insert into t1 (salary) values (100),(1000),(10000),(10),(500),(5000),(50000);
 explain SELECT id FROM t1 where salary = (SELECT MAX(salary) FROM t1);
 drop table t1;
+
+#
+# reduced subselect in ORDER BY & GROUP BY clauses
+#
+(SELECT 1 as a) UNION (SELECT 1) ORDER BY (SELECT a+0);
+
+CREATE TABLE `t1` (
+  `id` mediumint(8) unsigned NOT NULL auto_increment,
+  `pseudo` varchar(35) NOT NULL default '',
+  `email` varchar(60) NOT NULL default '',
+  PRIMARY KEY  (`id`),
+  UNIQUE KEY `email` (`email`),
+  UNIQUE KEY `pseudo` (`pseudo`),
+) TYPE=MyISAM CHARSET=latin1 PACK_KEYS=1 ROW_FORMAT=DYNAMIC;
+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;

sql/sql_select.cc

@@ -7167,9 +7167,11 @@ find_order_in_list(THD *thd, Item **ref_pointer_array,
   }
   order->in_field_list=0;
   Item *it= *order->item;
-  if (it->fix_fields(thd, tables, order->item) || it->check_cols(1) ||
+  if (it->fix_fields(thd, tables, order->item) ||
+      //'it' ressigned because fix_field can change it
+      (it= *order->item), it->check_cols(1) ||
       thd->is_fatal_error)
-    return 1;					// Wrong field
+    return 1;					// Wrong field 
   uint el= all_fields.elements;
   all_fields.push_front(it);		        // Add new field to field list
   ref_pointer_array[el]= it;