manual merge

mysql-test/r/func_gconcat.result

@@ -978,4 +978,21 @@ GROUP BY t1.a
 1
 1
 DROP TABLE t1, t2;
+CREATE TABLE t1 (f1 INT);
+INSERT INTO t1 VALUES (),();
+EXPLAIN EXTENDED SELECT 1 FROM
+(SELECT DISTINCT GROUP_CONCAT(td.f1) FROM t1,t1 AS td GROUP BY td.f1) AS d,t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	<derived2>	system	NULL	NULL	NULL	NULL	1	100.00	
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
+2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using temporary; Using filesort; Distinct
+2	DERIVED	td	ALL	NULL	NULL	NULL	NULL	2	100.00	Distinct; Using join buffer
+Warnings:
+Note	1003	select 1 AS `1` from (select distinct group_concat(`test`.`td`.`f1` separator ',') AS `GROUP_CONCAT(td.f1)` from `test`.`t1` join `test`.`t1` `td` group by `test`.`td`.`f1`) `d` join `test`.`t1`
+SELECT 1 FROM
+(SELECT DISTINCT GROUP_CONCAT(td.f1) FROM t1,t1 AS td GROUP BY td.f1) AS d,t1;
+1
+1
+1
+DROP TABLE t1;
 End of 5.0 tests

mysql-test/t/func_gconcat.test

@@ -693,4 +693,19 @@ SELECT 1 FROM t1 WHERE t1.a NOT IN
 
 DROP TABLE t1, t2;
 
+#
+# Bug #49487: crash with explain extended and group_concat in a derived table
+#
+
+CREATE TABLE t1 (f1 INT);
+INSERT INTO t1 VALUES (),();
+
+EXPLAIN EXTENDED SELECT 1 FROM
+ (SELECT DISTINCT GROUP_CONCAT(td.f1) FROM t1,t1 AS td GROUP BY td.f1) AS d,t1;
+
+SELECT 1 FROM
+ (SELECT DISTINCT GROUP_CONCAT(td.f1) FROM t1,t1 AS td GROUP BY td.f1) AS d,t1;
+
+DROP TABLE t1;
+
 --echo End of 5.0 tests

sql/item_sum.cc

@@ -3402,6 +3402,8 @@ String* Item_func_group_concat::val_str(String* str)
 
 void Item_func_group_concat::print(String *str, enum_query_type query_type)
 {
+  /* orig_args is not filled with valid values until fix_fields() */
+  Item **pargs= fixed ? orig_args : args;
   str->append(STRING_WITH_LEN("group_concat("));
   if (distinct)
     str->append(STRING_WITH_LEN("distinct "));
@@ -3409,7 +3411,7 @@ void Item_func_group_concat::print(String *str, enum_query_type query_type)
   {
     if (i)
       str->append(',');
-    args[i]->print(str, query_type);
+    pargs[i]->print(str, query_type);
   }
   if (arg_count_order)
   {