MDEV-11162 Assertion `num_records == m_idx_array.size()' failed in Fi…

…lesort_buffer::alloc_sort_buffer(uint, uint)

When JOIN::destroy() is called for a JOIN object that has
   - join->tmp_join != NULL
   - also has join->table[0]->sort

then the latter was not cleaned up.
This could cause a memory leak and/or asserts in the subsequent queries.

Fixed by adding a cleanup call.

mysql-test/r/group_by_innodb.result

@@ -123,4 +123,11 @@ id	xtext	optionen
 2	number	22,25
 1	select	Kabel mit Stecker 5-polig,Kabel ohne Stecker
 DROP TABLE t1, t2;
+CREATE TABLE t1 (i INT) ENGINE=InnoDB;
+SELECT ( SELECT DISTINCT GROUP_CONCAT(SLEEP(0)) FROM t1 GROUP BY i );
+( SELECT DISTINCT GROUP_CONCAT(SLEEP(0)) FROM t1 GROUP BY i )
+NULL
+SELECT i FROM t1 order by i LIMIT 1;
+i
+DROP TABLE t1;
 # End of tests

mysql-test/t/group_by_innodb.test

@@ -125,4 +125,14 @@ ORDER BY id DESC;
 
 DROP TABLE t1, t2;
 
+--echo #
+--echo # MDEV-11162: Assertion `num_records == m_idx_array.size()' failed in Filesort_buffer::alloc_sort_buffer(uint, uint)
+--echo #
+
+CREATE TABLE t1 (i INT) ENGINE=InnoDB;
+SELECT ( SELECT DISTINCT GROUP_CONCAT(SLEEP(0)) FROM t1 GROUP BY i );
+SELECT i FROM t1 order by i LIMIT 1;
+DROP TABLE t1;
+
 --echo # End of tests
+

sql/sql_select.cc

@@ -3144,6 +3144,7 @@ JOIN::destroy()
     */
     tmp_table_param.cleanup();
     tmp_join->tmp_table_param.copy_field= 0;
+    cleanup(1);
     DBUG_RETURN(tmp_join->destroy());
   }
   cond_equal= 0;