Fixed LP bug #806510.

The bug was caused by an incorrect code of the function
Item_direct_view_ref::replace_equal_field introduced in the
patch for bugs 717577, 724942. The function erroneously
returned the wrapped field instead of the Item_direct_view_ref
object itself in the cases when no replacement happened.

The bug masked two other minor bugs that could result in not
quite correct output of the EXPLAIN command for some queries.
They were fixed in the patch as well.
 

mysql-test/r/derived_view.result

@@ -848,3 +848,55 @@ Warnings:
 Note	1003	select `test`.`t3`.`b` AS `b`,`test`.`t1`.`a` AS `a` from `test`.`t3` left join (`test`.`t2` join `test`.`t1`) on((`test`.`t3`.`a` <> 0)) where ((`test`.`t1`.`a` = `test`.`t1`.`a`) or (`test`.`t3`.`b` <> 0))
 DROP VIEW v1;
 DROP TABLE t1,t2,t3;
+#
+# LP bug #806510: subquery with outer reference
+#                 to a derived_table/view                    
+#
+CREATE TABLE t1 (a int) ;
+INSERT INTO t1 VALUES (4), (NULL);
+CREATE TABLE t2 (a int) ;
+INSERT INTO t2 VALUES (8), (0);
+CREATE TABLE t3 (a int, b int) ;
+INSERT INTO t3 VALUES (7,8);
+CREATE VIEW v1 AS SELECT * FROM t1;
+SELECT * FROM  t1 t
+WHERE EXISTS (SELECT t3.a FROM t3, t2
+WHERE t2.a = t3.b AND t.a != 0);
+a
+4
+EXPLAIN
+SELECT * FROM  t1 t
+WHERE EXISTS (SELECT t3.a FROM t3, t2
+WHERE t2.a = t3.b AND t.a != 0);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t	ALL	NULL	NULL	NULL	NULL	2	Using where
+2	DEPENDENT SUBQUERY	t3	system	NULL	NULL	NULL	NULL	1	
+2	DEPENDENT SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	2	Using where
+SELECT * FROM (SELECT * FROM t1) t
+WHERE EXISTS (SELECT t3.a FROM t3, t2
+WHERE t2.a = t3.b AND t.a != 0);
+a
+4
+EXPLAIN
+SELECT * FROM (SELECT * FROM t1) t
+WHERE EXISTS (SELECT t3.a FROM t3, t2
+WHERE t2.a = t3.b AND t.a != 0);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	Using where
+3	DEPENDENT SUBQUERY	t3	system	NULL	NULL	NULL	NULL	1	
+3	DEPENDENT SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	2	Using where
+SELECT * FROM v1 t
+WHERE EXISTS (SELECT t3.a FROM t3, t2
+WHERE t2.a = t3.b AND t.a != 0);
+a
+4
+EXPLAIN
+SELECT * FROM v1 t
+WHERE EXISTS (SELECT t3.a FROM t3, t2
+WHERE t2.a = t3.b AND t.a != 0);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	Using where
+2	DEPENDENT SUBQUERY	t3	system	NULL	NULL	NULL	NULL	1	
+2	DEPENDENT SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	2	Using where
+DROP VIEW v1;
+DROP TABLE t1,t2,t3;

mysql-test/r/join_cache.result

@@ -3033,7 +3033,7 @@ t6.formattypeid IN (2) AND (t3.formatid IN (31, 8, 76)) AND
 t1.metaid = t2.metaid AND t1.affiliateid = '2';
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t6	system	PRIMARY	NULL	NULL	NULL	1	
-1	SIMPLE	t1	ref	t1_affiliateid,t1_metaid	t1_affiliateid	4	const	1	Using index condition
+1	SIMPLE	t1	ref	t1_affiliateid,t1_metaid	t1_affiliateid	4	const	1	
 1	SIMPLE	t4	ref	PRIMARY,t4_formatclassid,t4_formats_idx	t4_formats_idx	1	const	1	Using index condition; Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan
 1	SIMPLE	t5	eq_ref	PRIMARY,t5_formattypeid	PRIMARY	4	test.t4.formatclassid	1	Using where; Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan
 1	SIMPLE	t2	eq_ref	PRIMARY	PRIMARY	4	test.t1.metaid	1	Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan

mysql-test/t/derived_view.test

@@ -460,3 +460,46 @@ SELECT t3.b, v1.a
 
 DROP VIEW v1;
 DROP TABLE t1,t2,t3;
+
+--echo #
+--echo # LP bug #806510: subquery with outer reference
+--echo #                 to a derived_table/view                    
+--echo #
+
+CREATE TABLE t1 (a int) ;
+INSERT INTO t1 VALUES (4), (NULL);
+
+CREATE TABLE t2 (a int) ;
+INSERT INTO t2 VALUES (8), (0);
+
+CREATE TABLE t3 (a int, b int) ;
+INSERT INTO t3 VALUES (7,8);
+
+CREATE VIEW v1 AS SELECT * FROM t1;
+
+SELECT * FROM  t1 t
+  WHERE EXISTS (SELECT t3.a FROM t3, t2
+                  WHERE t2.a = t3.b AND t.a != 0);
+EXPLAIN
+SELECT * FROM  t1 t
+  WHERE EXISTS (SELECT t3.a FROM t3, t2
+                  WHERE t2.a = t3.b AND t.a != 0);
+
+SELECT * FROM (SELECT * FROM t1) t
+  WHERE EXISTS (SELECT t3.a FROM t3, t2
+                  WHERE t2.a = t3.b AND t.a != 0);
+EXPLAIN
+SELECT * FROM (SELECT * FROM t1) t
+  WHERE EXISTS (SELECT t3.a FROM t3, t2
+                  WHERE t2.a = t3.b AND t.a != 0);
+
+SELECT * FROM v1 t
+  WHERE EXISTS (SELECT t3.a FROM t3, t2
+                  WHERE t2.a = t3.b AND t.a != 0);
+EXPLAIN
+SELECT * FROM v1 t
+  WHERE EXISTS (SELECT t3.a FROM t3, t2
+                  WHERE t2.a = t3.b AND t.a != 0);
+
+DROP VIEW v1;
+DROP TABLE t1,t2,t3;

sql/item.cc

@@ -7527,7 +7527,7 @@ Item *Item_direct_view_ref::replace_equal_field(uchar *arg)
   field_item->set_item_equal(item_equal);
   Item *item= field_item->replace_equal_field(arg);
   field_item->set_item_equal(0);
-  return item;
+  return item != field_item ? item : this;
 }
 
 

sql/sql_select.cc

@@ -7383,7 +7383,7 @@ get_store_key(THD *thd, KEYUSE *keyuse, table_map used_tables,
 			       maybe_null ? key_buff : 0,
 			       key_part->length,
 			       ((Item_field*) keyuse->val->real_item())->field,
-			       keyuse->val->full_name());
+			       keyuse->val->real_item()->full_name());
   return new store_key_item(thd,
 			    key_part->field,
 			    key_buff + maybe_null,
@@ -16512,7 +16512,8 @@ bool test_if_ref(Item *root_cond, Item_field *left_item,Item *right_item)
     }
 
     Item *ref_item=part_of_refkey(field->table,field);
-    if (ref_item && ref_item->eq(right_item,1))
+    if (ref_item && (ref_item->eq(right_item,1) || 
+		     ref_item->real_item()->eq(right_item,1)))
     {
       right_item= right_item->real_item();
       if (right_item->type() == Item::FIELD_ITEM)