Bug#29850: Wrong charset of GROUP_CONCAT result when the select employs

a temporary table.

The result string of the Item_func_group_concat wasn't initialized in the 
copying constructor of the Item_func_group_concat class. This led to a
wrong charset of GROUP_CONCAT result when the select employs a temporary
table.

The copying constructor of the Item_func_group_concat class now correctly
initializes the charset of the result string.


mysql-test/t/func_gconcat.test:
  Added a test case for the bug#29850: Wrong charset of the GROUP_CONCAT result
  when the select employs a temporary table.
mysql-test/r/func_gconcat.result:
  Added a test case for the bug#29850: Wrong charset of the GROUP_CONCAT result
  when the select employs a temporary table.
sql/item_sum.cc:
  Bug#29850: Wrong charset of GROUP_CONCAT result when the select employs
  a temporary table.
  The copying constructor of the Item_func_group_concat class now correctly
  initializes the charset of the result string.

1 files changed, 11 insertions, 0 deletions

diff --git a/mysql-test/t/func_gconcat.test b/mysql-test/t/func_gconcat.test
index 767df5ae233..ff3ba951870 100644
--- a/mysql-test/t/func_gconcat.test
+++ b/mysql-test/t/func_gconcat.test
@@ -551,4 +551,15 @@ SELECT LENGTH( GROUP_CONCAT( a ) ) FROM t3 WHERE b = 3;
 SET group_concat_max_len= DEFAULT;
 DROP TABLE t1, t2, t3;
 
+#
+# Bug#29850: Wrong charset of the GROUP_CONCAT result when the select employs
+#            a temporary table.
+#
+set names latin1;
+create table t1 (id int, name varchar(20)) DEFAULT CHARSET=utf8;
+insert into t1 (id, name) values (1, "óra");
+insert into t1 (id, name) values (2, "óra");
+select b.id, group_concat(b.name) from t1 a, t1 b group by b.id;
+drop table t1;
+
 --echo End of 5.0 tests