Bug #27354 stored function in where condition was always treated as const

Possible problems: function call could be eliminated from where class and only
be evaluated once; function can be evaluated during table and item setup phase which could
cause side effects not to be registered in binlog.

Fixed with introducing func_item_sp::used_tables() returning the correct table_map constant.



mysql-test/r/sp.result:
  results changed
mysql-test/t/sp.test:
  regression test demonstrating that function's returns match where condition
  of the top-level query table.
sql/item_func.h:
  private used_tables() method returning the correct table_bit with meaning the item is not
  a constant

mysql-test/r/sp.result

@@ -5779,3 +5779,28 @@ SUM(f2)	bug25373(f1)
 DROP FUNCTION bug25373|
 DROP TABLE t3|
 drop table t1,t2;
+CREATE TABLE t1 (a int auto_increment primary key) engine=MyISAM;
+CREATE TABLE t2 (a int auto_increment primary key, b int) engine=innodb;
+set @a=0;
+CREATE function bug27354() RETURNS int deterministic
+begin
+insert into t1 values (null);
+set @a=@a+1;
+return @a;
+end|
+update t2 set b=1 where a=bug27354();
+select count(t_1.a),count(t_2.a) from t1 as t_1, t2 as t_2 /* must be 0,0 */;
+count(t_1.a)	count(t_2.a)
+0	0
+insert into t2 values (1,1),(2,2),(3,3);
+update t2 set b=-b where a=bug27354();
+select * from t2 /* must return 1,-1 ... */;
+a	b
+1	-1
+2	-2
+3	-3
+select count(*) from t1 /* must be 3 */;
+count(*)
+3
+drop table t1,t2;
+drop function   bug27354;

mysql-test/t/sp.test

@@ -6770,3 +6770,27 @@ DROP TABLE t3|
 # practical, or create table t3, t4 etc temporarily (and drop them).
 delimiter ;|
 drop table t1,t2;
+
+CREATE TABLE t1 (a int auto_increment primary key) engine=MyISAM;
+CREATE TABLE t2 (a int auto_increment primary key, b int) engine=innodb;
+set @a=0;
+
+delimiter |;
+CREATE function bug27354() RETURNS int deterministic
+begin
+insert into t1 values (null);
+set @a=@a+1;
+return @a;
+end|
+
+delimiter ;|
+update t2 set b=1 where a=bug27354();
+select count(t_1.a),count(t_2.a) from t1 as t_1, t2 as t_2 /* must be 0,0 */;
+insert into t2 values (1,1),(2,2),(3,3);
+update t2 set b=-b where a=bug27354();
+select * from t2 /* must return 1,-1 ... */;
+select count(*) from t1 /* must be 3 */;
+
+
+drop table t1,t2;
+drop function   bug27354;

sql/item_func.h

@@ -1411,7 +1411,7 @@ private:
   bool execute(Field **flp);
   bool execute_impl(THD *thd, Field *return_value_fld);
   Field *sp_result_field(void) const;
-
+  
 public:
 
   Item_func_sp(Name_resolution_context *context_arg, sp_name *name);
@@ -1422,6 +1422,8 @@ public:
   virtual ~Item_func_sp()
   {}
 
+  table_map used_tables() const { return RAND_TABLE_BIT; }
+
   void cleanup();
 
   const char *func_name() const;