Bug#21555: incorrect behavior with INSERT ... ON DUPL KEY UPDATE and VALUES

 VALUES() was considered a constant. This caused replacing 
 (or pre-calculating) it using uninitialized values before the actual
 execution takes place.
 Mark it as a non-constant (still not dependent of tables) to prevent
 the pre-calculation.

mysql-test/r/insert_update.result

@@ -63,9 +63,9 @@ Warnings:
 Note	1003	select test.t1.a AS `a`,test.t1.b AS `b`,test.t1.c AS `c`,values(test.t1.a) AS `VALUES(a)` from test.t1
 explain extended select * from t1 where values(a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	5	Using where
 Warnings:
-Note	1003	select test.t1.a AS `a`,test.t1.b AS `b`,test.t1.c AS `c` from test.t1
+Note	1003	select test.t1.a AS `a`,test.t1.b AS `b`,test.t1.c AS `c` from test.t1 where values(test.t1.a)
 DROP TABLE t1;
 create table t1(a int primary key, b int);
 insert into t1 values(1,1),(2,2),(3,3),(4,4),(5,5);
@@ -197,3 +197,25 @@ PRIMARY KEY  (a)
 ) ENGINE=MyISAM;
 INSERT INTO t1 ( a ) SELECT 0 ON DUPLICATE KEY UPDATE a = a + VALUES (a) ;
 DROP TABLE t1;
+CREATE TABLE t1
+(
+a   BIGINT UNSIGNED,
+b   BIGINT UNSIGNED,
+PRIMARY KEY (a)
+);
+INSERT INTO t1 VALUES (45, 1) ON DUPLICATE KEY UPDATE b =
+IF(VALUES(b) > t1.b, VALUES(b), t1.b);
+SELECT * FROM t1;
+a	b
+45	1
+INSERT INTO t1 VALUES (45, 2) ON DUPLICATE KEY UPDATE b =
+IF(VALUES(b) > t1.b, VALUES(b), t1.b);
+SELECT * FROM t1;
+a	b
+45	2
+INSERT INTO t1 VALUES (45, 1) ON DUPLICATE KEY UPDATE b = 
+IF(VALUES(b) > t1.b, VALUES(b), t1.b);
+SELECT * FROM t1;
+a	b
+45	2
+DROP TABLE t1;

mysql-test/t/insert_update.test

@@ -115,4 +115,27 @@ INSERT INTO t1 ( a ) SELECT 0 ON DUPLICATE KEY UPDATE a = a + VALUES (a) ;
 
 DROP TABLE t1;
 
+#
+# Bug#21555: incorrect behavior with INSERT ... ON DUPL KEY UPDATE and VALUES
+#
+
+
 # End of 4.1 tests
+CREATE TABLE t1
+(
+  a   BIGINT UNSIGNED,
+  b   BIGINT UNSIGNED,
+  PRIMARY KEY (a)
+);
+
+INSERT INTO t1 VALUES (45, 1) ON DUPLICATE KEY UPDATE b =
+  IF(VALUES(b) > t1.b, VALUES(b), t1.b);
+SELECT * FROM t1;
+INSERT INTO t1 VALUES (45, 2) ON DUPLICATE KEY UPDATE b =
+  IF(VALUES(b) > t1.b, VALUES(b), t1.b);
+SELECT * FROM t1;
+INSERT INTO t1 VALUES (45, 1) ON DUPLICATE KEY UPDATE b = 
+  IF(VALUES(b) > t1.b, VALUES(b), t1.b);
+SELECT * FROM t1;
+
+DROP TABLE t1;

sql/item.h

@@ -1241,7 +1241,11 @@ class Item_insert_value : public Item_field
   {
     return Item_field::save_in_field(field_arg, no_conversions);
   }
-  table_map used_tables() const { return (table_map)0L; }
+  /* 
+   We use RAND_TABLE_BIT to prevent Item_insert_value from
+   being treated as a constant and precalculated before execution
+  */
+  table_map used_tables() const { return RAND_TABLE_BIT; }
 
   bool walk(Item_processor processor, byte *args)
   {