Fixed LP bug #804686.

The assert conditions in the functions Item_direct_ref_to_ident::transform
and Item_direct_ref_to_ident::compile could be not valid after constant
propagation when fields and field references may be substituted for constants.
Not only these invalid asserts have been removed, but the functions containing
them have been removed as well because now Item_ref::transform and 
Item_ref::compile can be used instead of them.

mysql-test/r/view.result

@@ -4246,3 +4246,34 @@ a	MIN(b)
 7	78
 DROP VIEW v1;
 DROP TABLE t1,t2;
+#
+# LP bug #804686: query over a derived table using a view 
+#                 with a degenerated where condition
+#
+CREATE TABLE t1 (a int, b int);
+INSERT INTO t1 VALUES (0,0), (1,0), (0,0), (1,1), (1,0);
+CREATE VIEW v1 AS SELECT a,b FROM t1;
+CREATE VIEW v2 AS SELECT a, MAX(b) AS b FROM t1 GROUP BY a;
+SELECT * FROM (SELECT b FROM v1 WHERE b = 0) t WHERE b<>0;
+b
+SELECT * FROM (SELECT b FROM v2 WHERE b = 0) t WHERE b<>0;
+b
+SELECT * FROM (SELECT b FROM v1 WHERE b = 0) t WHERE b;
+b
+SELECT * FROM (SELECT b FROM v2 WHERE b = 0) t WHERE b;
+b
+EXPLAIN EXTENDED
+SELECT * FROM (SELECT b FROM v1 WHERE b = 0) t WHERE b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+Warnings:
+Note	1003	select `test`.`t1`.`b` AS `b` from `test`.`t1` where 0
+EXPLAIN EXTENDED
+SELECT * FROM (SELECT b FROM v2 WHERE b = 0) t WHERE b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+3	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	5	100.00	Using temporary; Using filesort
+Warnings:
+Note	1003	select `v2`.`b` AS `b` from `test`.`v2` where 0
+DROP VIEW v1,v2;
+DROP TABLE t1;

mysql-test/t/view.test

@@ -4192,3 +4192,24 @@ SELECT a, MIN(b) FROM v1 GROUP BY a;
 DROP VIEW v1;
 DROP TABLE t1,t2;
 
+--echo #
+--echo # LP bug #804686: query over a derived table using a view 
+--echo #                 with a degenerated where condition
+--echo #
+
+CREATE TABLE t1 (a int, b int);
+INSERT INTO t1 VALUES (0,0), (1,0), (0,0), (1,1), (1,0);
+CREATE VIEW v1 AS SELECT a,b FROM t1;
+CREATE VIEW v2 AS SELECT a, MAX(b) AS b FROM t1 GROUP BY a;
+
+SELECT * FROM (SELECT b FROM v1 WHERE b = 0) t WHERE b<>0;
+SELECT * FROM (SELECT b FROM v2 WHERE b = 0) t WHERE b<>0;
+SELECT * FROM (SELECT b FROM v1 WHERE b = 0) t WHERE b;
+SELECT * FROM (SELECT b FROM v2 WHERE b = 0) t WHERE b;
+EXPLAIN EXTENDED
+SELECT * FROM (SELECT b FROM v1 WHERE b = 0) t WHERE b;
+EXPLAIN EXTENDED
+SELECT * FROM (SELECT b FROM v2 WHERE b = 0) t WHERE b;
+
+DROP VIEW v1,v2;
+DROP TABLE t1;

sql/item.cc

@@ -6883,40 +6883,6 @@ bool Item_direct_ref::get_date(MYSQL_TIME *ltime,uint fuzzydate)
 }
 
 
-Item* Item_direct_ref_to_ident::transform(Item_transformer transformer,
-                                          uchar *argument)
-{
-  DBUG_ASSERT(!current_thd->is_stmt_prepare());
-
-  Item *new_item= ident->transform(transformer, argument);
-  if (!new_item)
-    return 0;
-  DBUG_ASSERT(new_item->type() == FIELD_ITEM || new_item->type() == REF_ITEM);
-
-  if (ident != new_item)
-    current_thd->change_item_tree((Item**)&ident, new_item);
-  return (this->*transformer)(argument);
-}
-
-
-Item* Item_direct_ref_to_ident::compile(Item_analyzer analyzer, uchar **arg_p,
-                                        Item_transformer transformer,
-                                        uchar *arg_t)
-{
-  if (!(this->*analyzer)(arg_p))
-    return 0;
-
-  uchar *arg_v= *arg_p;
-  Item *new_item= ident->compile(analyzer, &arg_v, transformer, arg_t);
-  if (new_item && ident != new_item)
-  {
-    DBUG_ASSERT(new_item->type() == FIELD_ITEM || new_item->type() == REF_ITEM);
-    current_thd->change_item_tree((Item**)&ident, new_item);
-  }
-  return (this->*transformer)(arg_t);
-}
-
-
 Item_cache_wrapper::~Item_cache_wrapper()
 {
   DBUG_ASSERT(expr_cache == 0);

sql/item.h

@@ -2570,8 +2570,8 @@ public:
   Field *get_tmp_table_field()
   { return result_field ? result_field : (*ref)->get_tmp_table_field(); }
   Item *get_tmp_table_item(THD *thd);
-  inline table_map used_tables() const;		
-  inline void update_used_tables(); 
+  table_map used_tables() const;		
+  void update_used_tables(); 
   bool const_item() const 
   {
     return (*ref)->const_item();
@@ -2713,9 +2713,6 @@ public:
   virtual void print(String *str, enum_query_type query_type)
   { ident->print(str, query_type); }
 
-  virtual Item* transform(Item_transformer transformer, uchar *arg);
-  virtual Item* compile(Item_analyzer analyzer, uchar **arg_p,
-                        Item_transformer transformer, uchar *arg_t);
 };