check of item name presence in find_item_in_list (Bug #3752)

mysql-test/r/func_gconcat.result:
  test of Bug #3752
mysql-test/t/func_gconcat.test:
  test of Bug #3752
sql/sql_base.cc:
  check of item name presence in find_item_in_list

mysql-test/r/func_gconcat.result

@@ -301,3 +301,12 @@ a	c	grp
 2	4	4
 1	2	5
 drop table t1,t2;
+CREATE TABLE t1 ( a int );
+CREATE TABLE t2 ( a int );
+INSERT INTO t1 VALUES (1), (2);
+INSERT INTO t2 VALUES (1), (2);
+SELECT GROUP_CONCAT(t1.a*t2.a ORDER BY t1.a) FROM t1, t2 GROUP BY t1.a;
+GROUP_CONCAT(t1.a*t2.a ORDER BY t1.a)
+2,1
+4,2
+DROP TABLE t1, t2;

mysql-test/t/func_gconcat.test

@@ -179,3 +179,13 @@ select group_concat(c order by (select mid(group_concat(c order by a),1,5) from
 
 select a,c,(select group_concat(c order by a) from t2 where a=t1.a) as grp from t1 order by grp;
 drop table t1,t2;
+
+#
+# group_concat of expression with GROUP BY and external GROUP BY
+#
+CREATE TABLE t1 ( a int );
+CREATE TABLE t2 ( a int );
+INSERT INTO t1 VALUES (1), (2);
+INSERT INTO t2 VALUES (1), (2);
+SELECT GROUP_CONCAT(t1.a*t2.a ORDER BY t1.a) FROM t1, t2 GROUP BY t1.a;
+DROP TABLE t1, t2;

sql/sql_base.cc

@@ -2096,7 +2096,14 @@ find_item_in_list(Item *find, List<Item> &items, uint *counter,
     if (field_name && item->type() == Item::FIELD_ITEM)
     {
       Item_field *item_field= (Item_field*) item;
-      if (!my_strcasecmp(system_charset_info, item_field->name, field_name))
+      /*
+	In case of group_concat() with ORDER BY condition in the QUERY
+	item_field can be field of temporary table without item name 
+	(if this field created from expression argument of group_concat()),
+	=> we have to check presence of name before compare
+      */ 
+      if (item_field->name &&
+	  !my_strcasecmp(system_charset_info, item_field->name, field_name))
       {
 	if (!table_name)
 	{