fixed memory leak in group_concat function (BUG#796)

fixed test func_gconcat to be repeatable independent of presend tables and avoid removing user tables

mysql-test/r/func_gconcat.result

-drop table if exists t1;
-Warnings:
-Note	1051	Unknown table 't1'
+drop table if exists t1, t2;
 create table t1 (grp int, a bigint unsigned, c char(10) not null, d char(10) not null);
 insert into t1 values (1,1,"a","a");
 insert into t1 values (2,2,"b","a");
@@ -155,28 +153,22 @@ show warnings;
 Level	Code	Message
 Warning	1258	1 line(s) was(were) cut by group_concat()
 set group_concat_max_len = 1024;
-drop table if exists T_URL;
-Warnings:
-Note	1051	Unknown table 'T_URL'
-create table T_URL ( URL_ID int(11), URL varchar(80));
-drop table if exists T_REQUEST;
-Warnings:
-Note	1051	Unknown table 'T_REQUEST'
-create table T_REQUEST ( REQ_ID int(11), URL_ID int(11));
-insert into T_URL values (4,'www.host.com'), (5,'www.google.com'),(5,'www.help.com');
-insert into T_REQUEST values (1,4), (5,4), (5,5);
-select REQ_ID, Group_Concat(URL) as URL from T_URL, T_REQUEST where 
-T_REQUEST.URL_ID = T_URL.URL_ID group by REQ_ID;
-REQ_ID	URL
-1	X
-5	X,X,X
-drop table T_URL;
-drop table T_REQUEST;
 select group_concat(sum(a)) from t1 group by grp;
 ERROR HY000: Invalid use of group function
 select grp,group_concat(c order by 2) from t1 group by grp;
 ERROR 42S22: Unknown column '2' in 'group statement'
 drop table t1;
+create table t1 ( URL_ID int(11), URL varchar(80));
+create table t2 ( REQ_ID int(11), URL_ID int(11));
+insert into t1 values (4,'www.host.com'), (5,'www.google.com'),(5,'www.help.com');
+insert into t2 values (1,4), (5,4), (5,5);
+select REQ_ID, Group_Concat(URL) as URL from t1, t2 where 
+t2.URL_ID = t1.URL_ID group by REQ_ID;
+REQ_ID	URL
+1	X
+5	X,X,X
+drop table t1;
+drop table t2;
 create table t1 (id int, name varchar(16));
 insert into t1 values (1,'longername'),(1,'evenlongername');
 select ifnull(group_concat(concat(t1.id, ':', t1.name)), 'shortname') as 'without distinct: how it should be' from t1;

mysql-test/t/func_gconcat.test

 #
 # simple test of group_concat function
 #
+--disable_warnings
+drop table if exists t1, t2;
+--enable_warnings
 
-drop table if exists t1;
 create table t1 (grp int, a bigint unsigned, c char(10) not null, d char(10) not null);
 insert into t1 values (1,1,"a","a");
 insert into t1 values (2,2,"b","a");
@@ -70,21 +72,6 @@ select grp,group_concat(c) from t1 group by grp;
 show warnings;
 set group_concat_max_len = 1024;
 
-# Test variable length
-
-drop table if exists T_URL;
-create table T_URL ( URL_ID int(11), URL varchar(80));
-drop table if exists T_REQUEST;
-create table T_REQUEST ( REQ_ID int(11), URL_ID int(11));
-insert into T_URL values (4,'www.host.com'), (5,'www.google.com'),(5,'www.help.com');
-insert into T_REQUEST values (1,4), (5,4), (5,5);
-# Make this order independent
---replace_result www.help.com X www.host.com X www.google.com X
-select REQ_ID, Group_Concat(URL) as URL from T_URL, T_REQUEST where 
-T_REQUEST.URL_ID = T_URL.URL_ID group by REQ_ID;
-drop table T_URL;
-drop table T_REQUEST;
-
 # Test errors
 
 --error 1111
@@ -94,6 +81,19 @@ select grp,group_concat(c order by 2) from t1 group by grp;
 
 drop table t1;
 
+# Test variable length
+
+create table t1 ( URL_ID int(11), URL varchar(80));
+create table t2 ( REQ_ID int(11), URL_ID int(11));
+insert into t1 values (4,'www.host.com'), (5,'www.google.com'),(5,'www.help.com');
+insert into t2 values (1,4), (5,4), (5,5);
+# Make this order independent
+--replace_result www.help.com X www.host.com X www.google.com X
+select REQ_ID, Group_Concat(URL) as URL from t1, t2 where 
+t2.URL_ID = t1.URL_ID group by REQ_ID;
+drop table t1;
+drop table t2;
+
 create table t1 (id int, name varchar(16));
 insert into t1 values (1,'longername'),(1,'evenlongername');
 select ifnull(group_concat(concat(t1.id, ':', t1.name)), 'shortname') as 'without distinct: how it should be' from t1;

sql/item_sum.cc

@@ -1788,11 +1788,12 @@ Item_func_group_concat::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 
 bool Item_func_group_concat::setup(THD *thd)
 {
+  DBUG_ENTER("Item_func_group_concat::setup");
   List<Item> list;
   SELECT_LEX *select_lex= thd->lex.current_select->select_lex();
 
   if (select_lex->linkage == GLOBAL_OPTIONS_TYPE)
-    return 1;
+    DBUG_RETURN(1);
   /*
     all not constant fields are push to list and create temp table
   */ 
@@ -1801,7 +1802,7 @@ bool Item_func_group_concat::setup(THD *thd)
   {
     Item *item= args[i];
     if (list.push_back(item))
-      return 1;
+      DBUG_RETURN(1);
     if (item->const_item())
     {
       (void) item->val_int();
@@ -1810,7 +1811,7 @@ bool Item_func_group_concat::setup(THD *thd)
     }
   }
   if (always_null)
-    return 0;
+    DBUG_RETURN(0);
         
   List<Item> all_fields(list);
   if (arg_count_order) 
@@ -1821,13 +1822,18 @@ bool Item_func_group_concat::setup(THD *thd)
   }
   
   count_field_types(tmp_table_param,all_fields,0);
+  if (table)
+  {
+    free_tmp_table(thd, table);
+    tmp_table_param->cleanup();
+  }
   /*
     We have to create a temporary table for that we get descriptions of fields 
     (types, sizes and so on).
   */
   if (!(table=create_tmp_table(thd, tmp_table_param, all_fields, 0,
-        0, 0, 0,select_lex->options | thd->options)))
-    return 1;
+			       0, 0, 0,select_lex->options | thd->options)))
+    DBUG_RETURN(1);
   table->file->extra(HA_EXTRA_NO_ROWS);
   table->no_rows= 1;
 
@@ -1886,7 +1892,7 @@ bool Item_func_group_concat::setup(THD *thd)
     original->table= table;
     original->tree_mode= tree_mode;
   }
-  return 0;
+  DBUG_RETURN(0);
 }
 
 /* This is used by rollup to create a separate usable copy of the function */