Fixed bug #16016: MIN/MAX optimization was not applied to views.

mysql-test/r/view.result:
  Added a test case for bug #16016.
mysql-test/t/view.test:
  Added a test case for bug #16016.
sql/opt_sum.cc:
  Fixed bug #16016: MIN/MAX optimization was not applied to views.
  The fix employs the standard way of handling direct references to view fields.

mysql-test/r/view.result

@@ -2475,3 +2475,32 @@ alias1	alias2
 5	5
 drop view v2, v1;
 drop table t1;
+CREATE TABLE t1 (a int PRIMARY KEY, b int);
+INSERT INTO t1 VALUES (2,20), (3,10), (1,10), (0,30), (5,10);
+CREATE VIEW v1 AS SELECT * FROM t1;
+SELECT MAX(a) FROM t1;
+MAX(a)
+5
+SELECT MAX(a) FROM v1;
+MAX(a)
+5
+EXPLAIN SELECT MAX(a) FROM t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
+EXPLAIN SELECT MAX(a) FROM v1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
+SELECT MIN(a) FROM t1;
+MIN(a)
+0
+SELECT MIN(a) FROM v1;
+MIN(a)
+0
+EXPLAIN SELECT MIN(a) FROM t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
+EXPLAIN SELECT MIN(a) FROM v1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
+DROP VIEW v1;
+DROP TABLE t1;

mysql-test/t/view.test

@@ -2339,3 +2339,27 @@ order by v2.receipt_id;
 
 drop view v2, v1;
 drop table t1;
+
+#
+# Bug#16016: MIN/MAX optimization for views
+#
+
+CREATE TABLE t1 (a int PRIMARY KEY, b int);
+INSERT INTO t1 VALUES (2,20), (3,10), (1,10), (0,30), (5,10);
+
+CREATE VIEW v1 AS SELECT * FROM t1;
+
+SELECT MAX(a) FROM t1;
+SELECT MAX(a) FROM v1;
+
+EXPLAIN SELECT MAX(a) FROM t1;
+EXPLAIN SELECT MAX(a) FROM v1;
+
+SELECT MIN(a) FROM t1;
+SELECT MIN(a) FROM v1;
+
+EXPLAIN SELECT MIN(a) FROM t1;
+EXPLAIN SELECT MIN(a) FROM v1;
+
+DROP VIEW v1;
+DROP TABLE t1;

sql/opt_sum.cc

@@ -180,14 +180,14 @@ int opt_sum_query(TABLE_LIST *tables, List<Item> &all_fields,COND *conds)
           indexes to find the key.
         */
         Item *expr=item_sum->args[0];
-        if (expr->type() == Item::FIELD_ITEM)
+        if (expr->real_item()->type() == Item::FIELD_ITEM)
         {
           byte key_buff[MAX_KEY_LENGTH];
           TABLE_REF ref;
           uint range_fl, prefix_len;
 
           ref.key_buff= key_buff;
-          Item_field *item_field= ((Item_field*) expr);
+          Item_field *item_field= (Item_field*) (expr->real_item());
           TABLE *table= item_field->field->table;
 
           /* 
@@ -267,14 +267,14 @@ int opt_sum_query(TABLE_LIST *tables, List<Item> &all_fields,COND *conds)
           indexes to find the key.
         */
         Item *expr=item_sum->args[0];
-        if (expr->type() == Item::FIELD_ITEM)
+        if (expr->real_item()->type() == Item::FIELD_ITEM)
         {
           byte key_buff[MAX_KEY_LENGTH];
           TABLE_REF ref;
-	      uint range_fl, prefix_len;
+          uint range_fl, prefix_len;
 
           ref.key_buff= key_buff;
-	      Item_field *item_field= ((Item_field*) expr);
+          Item_field *item_field= (Item_field*) (expr->real_item());
           TABLE *table= item_field->field->table;
 
           /*