Fixed bug mdev-4172.

This bug in the legacy code could manifest itself in queries with
semi-join materialized subqueries.
When a subquery is materialized all conditions that are imposed
only on the columns belonging to the tables from the subquery 
are taken into account.The code responsible for subquery optimizations
that employes subquery materialization  makes sure to remove these
conditions from the WHERE conditions of the query obtained after
it has transformed the original query into a query with a semi-join.
If the condition to be removed is an equality condition it could
be added to ON expressions and/or conditions from disjunctive branches
(parts of OR conditions) in an attempt to generate better access keys
to the tables of the query. Such equalities are supposed to be removed
later from all the formulas where they have been added to.
However, erroneously, this was not done in some cases when an ON
expression and/or a disjunctive part of the OR condition could
be converted into one multiple equality. As a result some equality
predicates over columns belonging to the tables of the materialized
subquery remained in the ON condition and/or the a disjunctive 
part of the OR condition, and the excuter later, when trying to
evaluate them, returned wrong answers as the values of the fields
from these equalities were not valid.  
This happened because any standalone multiple equality (a multiple
equality that are not ANDed with any other predicates) lacked
the information about equality predicates inherited from upper
levels (in particular, inherited from the WHERE condition).
The fix adds a reference to such information to any standalone
multiple equality. 

mysql-test/r/subselect_sj2_mat.result

@@ -1281,3 +1281,55 @@ g	y	y	y
 g	y	y	y
 DROP TABLE t1,t2,t3,t4;
 set optimizer_switch=@save_optimizer_switch;
+#
+# mdev-4172: LEFT JOIN with materialized multi-table IN subquery in WHERE
+#            and OR in ON condition
+#
+set @save_optimizer_switch=@@optimizer_switch;
+CREATE TABLE t1 (a1 int, c1 varchar(1));
+INSERT t1 VALUES (7,'v'), (3,'y');
+CREATE TABLE t2 (c2 varchar(1));
+INSERT INTO t2 VALUES ('y'), ('y');
+CREATE TABLE t3 (c3 varchar(1));
+INSERT INTO t3 VALUES
+('j'), ('v'), ('c'), ('m'), ('d'),
+('d'), ('y'), ('t'), ('d'), ('s');
+CREATE TABLE t4 (a4 int, c4 varchar(1));
+INSERT INTO t4 SELECT * FROM t1;
+set optimizer_switch='materialization=off';
+EXPLAIN EXTENDED
+SELECT * FROM t1 LEFT JOIN t2 ON (c2 = c1 OR c1 > 'z')
+WHERE c1 IN ( SELECT c4 FROM t3,t4 WHERE c3 = c4);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
+1	PRIMARY	t4	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Start temporary; Using join buffer (flat, BNL join)
+1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	10	100.00	Using where; End temporary; Using join buffer (flat, BNL join)
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Using join buffer (flat, BNL join)
+Warnings:
+Note	1003	select `test`.`t1`.`a1` AS `a1`,`test`.`t1`.`c1` AS `c1`,`test`.`t2`.`c2` AS `c2` from `test`.`t1` semi join (`test`.`t3` join `test`.`t4`) left join `test`.`t2` on(((`test`.`t2`.`c2` = `test`.`t1`.`c1`) or (`test`.`t1`.`c1` > 'z'))) where ((`test`.`t4`.`c4` = `test`.`t1`.`c1`) and (`test`.`t3`.`c3` = `test`.`t1`.`c1`))
+SELECT * FROM t1 LEFT JOIN t2 ON (c2 = c1 OR c1 > 'z')
+WHERE c1 IN ( SELECT c4 FROM t3,t4 WHERE c3 = c4);
+a1	c1	c2
+3	y	y
+3	y	y
+7	v	NULL
+set optimizer_switch='materialization=on';
+EXPLAIN EXTENDED
+SELECT * FROM t1 LEFT JOIN t2 ON (c2 = c1 OR c1 > 'z')
+WHERE c1 IN ( SELECT c4 FROM t3,t4 WHERE c3 = c4);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	4	func	1	100.00	
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where; Using join buffer (flat, BNL join)
+2	MATERIALIZED	t4	ALL	NULL	NULL	NULL	NULL	2	100.00	
+2	MATERIALIZED	t3	ALL	NULL	NULL	NULL	NULL	10	100.00	Using where; Using join buffer (flat, BNL join)
+Warnings:
+Note	1003	select `test`.`t1`.`a1` AS `a1`,`test`.`t1`.`c1` AS `c1`,`test`.`t2`.`c2` AS `c2` from `test`.`t1` semi join (`test`.`t3` join `test`.`t4`) left join `test`.`t2` on(((`test`.`t2`.`c2` = `test`.`t1`.`c1`) or (`test`.`t1`.`c1` > 'z'))) where (`test`.`t3`.`c3` = `test`.`t4`.`c4`)
+SELECT * FROM t1 LEFT JOIN t2 ON (c2 = c1 OR c1 > 'z')
+WHERE c1 IN ( SELECT c4 FROM t3,t4 WHERE c3 = c4);
+a1	c1	c2
+3	y	y
+3	y	y
+7	v	NULL
+DROP TABLE t1,t2,t3,t4;
+set optimizer_switch=@save_optimizer_switch;

mysql-test/r/view.result

@@ -1437,7 +1437,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 Warnings:
-Note	1003	select `test`.`t3`.`a` AS `a`,`test`.`t1`.`a` AS `a`,`test`.`t2`.`a` AS `b` from `test`.`t3` left join (`test`.`t1` left join (`test`.`t2`) on(((`test`.`t1`.`a` = `test`.`t3`.`a`) and (`test`.`t2`.`a` = `test`.`t3`.`a`)))) on((`test`.`t1`.`a` = `test`.`t3`.`a`)) where 1
+Note	1003	select `test`.`t3`.`a` AS `a`,`test`.`t1`.`a` AS `a`,`test`.`t2`.`a` AS `b` from `test`.`t3` left join (`test`.`t1` left join (`test`.`t2`) on((`test`.`t2`.`a` = `test`.`t3`.`a`))) on((`test`.`t1`.`a` = `test`.`t3`.`a`)) where 1
 prepare stmt1 from "select * from t3 left join v4 on (t3.a = v4.a);";
 execute stmt1;
 a	a	b

mysql-test/t/subselect_sj2_mat.test

@@ -177,3 +177,45 @@ SELECT * FROM t1 LEFT JOIN t2 ON ( b1 = a2 )
 DROP TABLE t1,t2,t3,t4;
 
 set optimizer_switch=@save_optimizer_switch;
+
+--echo #
+--echo # mdev-4172: LEFT JOIN with materialized multi-table IN subquery in WHERE
+--echo #            and OR in ON condition
+--echo #
+
+set @save_optimizer_switch=@@optimizer_switch;
+
+CREATE TABLE t1 (a1 int, c1 varchar(1));
+INSERT t1 VALUES (7,'v'), (3,'y');
+
+CREATE TABLE t2 (c2 varchar(1));
+INSERT INTO t2 VALUES ('y'), ('y');
+
+CREATE TABLE t3 (c3 varchar(1));
+INSERT INTO t3 VALUES
+  ('j'), ('v'), ('c'), ('m'), ('d'),
+  ('d'), ('y'), ('t'), ('d'), ('s');
+
+CREATE TABLE t4 (a4 int, c4 varchar(1));
+INSERT INTO t4 SELECT * FROM t1;
+
+set optimizer_switch='materialization=off';
+
+EXPLAIN EXTENDED
+SELECT * FROM t1 LEFT JOIN t2 ON (c2 = c1 OR c1 > 'z')
+  WHERE c1 IN ( SELECT c4 FROM t3,t4 WHERE c3 = c4);
+SELECT * FROM t1 LEFT JOIN t2 ON (c2 = c1 OR c1 > 'z')
+  WHERE c1 IN ( SELECT c4 FROM t3,t4 WHERE c3 = c4);
+
+set optimizer_switch='materialization=on';
+
+EXPLAIN EXTENDED
+SELECT * FROM t1 LEFT JOIN t2 ON (c2 = c1 OR c1 > 'z')
+  WHERE c1 IN ( SELECT c4 FROM t3,t4 WHERE c3 = c4);
+SELECT * FROM t1 LEFT JOIN t2 ON (c2 = c1 OR c1 > 'z')
+  WHERE c1 IN ( SELECT c4 FROM t3,t4 WHERE c3 = c4);
+
+DROP TABLE t1,t2,t3,t4;
+
+set optimizer_switch=@save_optimizer_switch;
+

sql/item_cmpfunc.cc

@@ -5458,6 +5458,7 @@ Item_equal::Item_equal(Item *f1, Item *f2, bool with_const_item)
   equal_items.push_back(f1);
   equal_items.push_back(f2);
   compare_as_dates= with_const_item && f2->cmp_type() == TIME_RESULT;
+  upper_levels= NULL;  
 }
 
 
@@ -5486,6 +5487,7 @@ Item_equal::Item_equal(Item_equal *item_equal)
   with_const= item_equal->with_const;
   compare_as_dates= item_equal->compare_as_dates;
   cond_false= item_equal->cond_false;
+  upper_levels= item_equal->upper_levels;
 }
 
 

sql/item_cmpfunc.h

@@ -1739,7 +1739,11 @@ class Item_equal: public Item_bool_func
     used in the original equality.
   */
   Item_field *context_field;
+
 public:
+
+  COND_EQUAL *upper_levels;       /* multiple equalities of upper and levels */
+
   inline Item_equal()
     : Item_bool_func(), with_const(FALSE), eval_item(0), cond_false(0),
       context_field(NULL)

sql/sql_select.cc

@@ -11438,6 +11438,7 @@ static COND *build_equal_items_for_cond(THD *thd, COND *cond,
           item_equal->update_used_tables();
           set_if_bigger(thd->lex->current_select->max_equal_elems,
                         item_equal->n_field_items());  
+          item_equal->upper_levels= inherited;
           return item_equal;
 	}
 
@@ -12121,6 +12122,7 @@ static COND* substitute_for_best_equal_field(JOIN_TAB *context_tab,
   {
     item_equal= (Item_equal *) cond;
     item_equal->sort(&compare_fields_by_table_order, table_join_idx);
+    cond_equal= item_equal->upper_levels;
     if (cond_equal && cond_equal->current_level.head() == item_equal)
       cond_equal= cond_equal->upper_levels;
     cond= eliminate_item_equal(0, cond_equal, item_equal);