5.0-bugteam->5.1-bugteam merge

mysql-test/r/union.result

@@ -1574,4 +1574,17 @@ SHOW FIELDS FROM t2;
 Field	Type	Null	Key	Default	Extra
 d	double(9,6)	YES		NULL	
 DROP TABLE t1, t2;
+CREATE TABLE t1(a INT);
+EXPLAIN EXTENDED
+SELECT a FROM t1
+UNION
+SELECT a FROM t1
+ORDER BY a;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	t1	system	NULL	NULL	NULL	NULL	0	0.00	const row not found
+2	UNION	t1	system	NULL	NULL	NULL	NULL	0	0.00	const row not found
+NULL	UNION RESULT	<union1,2>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	Using filesort
+Warnings:
+Note	1003	select '0' AS `a` from `test`.`t1` union select '0' AS `a` from `test`.`t1` order by `a`
+DROP TABLE t1;
 End of 5.0 tests

mysql-test/t/union.test

@@ -1089,4 +1089,16 @@ CREATE TABLE t2 AS SELECT d FROM t1 UNION SELECT d FROM t1;
 SHOW FIELDS FROM t2;
 DROP TABLE t1, t2;
 
+#
+# Bug#43612 crash with explain extended, union, order by
+#
+CREATE TABLE t1(a INT);
+EXPLAIN EXTENDED
+SELECT a FROM t1
+UNION
+SELECT a FROM t1
+ORDER BY a;
+DROP TABLE t1;
+
+
 --echo End of 5.0 tests

sql/sql_union.cc

@@ -653,10 +653,22 @@ bool st_select_lex_unit::cleanup()
       join->tables= 0;
     }
     error|= fake_select_lex->cleanup();
-    if (fake_select_lex->order_list.elements)
+    /*
+      There are two cases when we should clean order items:
+      1. UNION with SELECTs which all enclosed into braces
+        in this case global_parameters == fake_select_lex
+      2. UNION where last SELECT is not enclosed into braces
+        in this case global_parameters == 'last select'
+      So we should use global_parameters->order_list for
+      proper order list clean up.
+      Note: global_parameters and fake_select_lex are always
+            initialized for UNION
+    */
+    DBUG_ASSERT(global_parameters);
+    if (global_parameters->order_list.elements)
     {
       ORDER *ord;
-      for (ord= (ORDER*)fake_select_lex->order_list.first; ord; ord= ord->next)
+      for (ord= (ORDER*)global_parameters->order_list.first; ord; ord= ord->next)
         (*ord->item)->cleanup();
     }
   }