Merge epotemkin@bk-internal.mysql.com:/home/bk/mysql-5.0-opt

into  sunlight.local:/local_work/16861-bug-5.0-mysql

mysql-test/r/user_var.result

@@ -292,3 +292,12 @@ SELECT @a;
 @a
 18446744071710965857
 drop table bigfailure;
+create table t1(f1 int, f2 int);
+insert into t1 values (1,2),(2,3),(3,1);
+select @var:=f2 from t1 group by f1 order by f2 desc limit 1;
+@var:=f2
+3
+select @var;
+@var
+3
+drop table t1;

mysql-test/t/user_var.test

@@ -202,3 +202,13 @@ SET @a := (select * from bigfailure where afield = (SELECT afield FROM bigfailur
 SELECT @a;
 
 drop table bigfailure;
+
+#
+# Bug#16861: User defined variable can have a wrong value if a tmp table was
+#            used.
+#
+create table t1(f1 int, f2 int);
+insert into t1 values (1,2),(2,3),(3,1);
+select @var:=f2 from t1 group by f1 order by f2 desc limit 1;
+select @var;
+drop table t1;

sql/item_func.cc

@@ -548,7 +548,7 @@ void Item_func::signal_divide_by_null()
 
 Item *Item_func::get_tmp_table_item(THD *thd)
 {
-  if (!with_sum_func && !const_item())
+  if (!with_sum_func && !const_item() && functype() != SUSERVAR_FUNC)
     return new Item_field(result_field);
   return copy_or_same(thd);
 }
@@ -3719,30 +3719,38 @@ my_decimal *user_var_entry::val_decimal(my_bool *null_value, my_decimal *val)
 */
 
 bool
-Item_func_set_user_var::check()
+Item_func_set_user_var::check(bool use_result_field)
 {
   DBUG_ENTER("Item_func_set_user_var::check");
+  if (use_result_field)
+    DBUG_ASSERT(result_field);
 
   switch (cached_result_type) {
   case REAL_RESULT:
   {
-    save_result.vreal= args[0]->val_real();
+    save_result.vreal= use_result_field ? result_field->val_real() :
+                        args[0]->val_real();
     break;
   }
   case INT_RESULT:
   {
-    save_result.vint= args[0]->val_int();
-    unsigned_flag= args[0]->unsigned_flag;
+    save_result.vint= use_result_field ? result_field->val_int() :
+                       args[0]->val_int();
+    unsigned_flag= use_result_field ? ((Field_num*)result_field)->unsigned_flag:
+                    args[0]->unsigned_flag;
     break;
   }
   case STRING_RESULT:
   {
-    save_result.vstr= args[0]->val_str(&value);
+    save_result.vstr= use_result_field ? result_field->val_str(&value) :
+                       args[0]->val_str(&value);
     break;
   }
   case DECIMAL_RESULT:
   {
-    save_result.vdec= args[0]->val_decimal(&decimal_buff);
+    save_result.vdec= use_result_field ?
+                       result_field->val_decimal(&decimal_buff) :
+                       args[0]->val_decimal(&decimal_buff);
     break;
   }
   case ROW_RESULT:
@@ -3828,7 +3836,7 @@ Item_func_set_user_var::update()
 double Item_func_set_user_var::val_real()
 {
   DBUG_ASSERT(fixed == 1);
-  check();
+  check(0);
   update();					// Store expression
   return entry->val_real(&null_value);
 }
@@ -3836,7 +3844,7 @@ double Item_func_set_user_var::val_real()
 longlong Item_func_set_user_var::val_int()
 {
   DBUG_ASSERT(fixed == 1);
-  check();
+  check(0);
   update();					// Store expression
   return entry->val_int(&null_value);
 }
@@ -3844,7 +3852,7 @@ longlong Item_func_set_user_var::val_int()
 String *Item_func_set_user_var::val_str(String *str)
 {
   DBUG_ASSERT(fixed == 1);
-  check();
+  check(0);
   update();					// Store expression
   return entry->val_str(&null_value, str, decimals);
 }
@@ -3853,7 +3861,7 @@ String *Item_func_set_user_var::val_str(String *str)
 my_decimal *Item_func_set_user_var::val_decimal(my_decimal *val)
 {
   DBUG_ASSERT(fixed == 1);
-  check();
+  check(0);
   update();					// Store expression
   return entry->val_decimal(&null_value, val);
 }
@@ -3878,6 +3886,16 @@ void Item_func_set_user_var::print_as_stmt(String *str)
   str->append(')');
 }
 
+bool Item_func_set_user_var::send(Protocol *protocol, String *str_arg)
+{
+  if (result_field)
+  {
+    check(1);
+    update();
+    return protocol->store(result_field);
+  }
+  return Item::send(protocol, str_arg);
+}
 
 String *
 Item_func_get_user_var::val_str(String *str)
@@ -4143,7 +4161,7 @@ bool Item_func_get_user_var::set_value(THD *thd,
     Item_func_set_user_var is not fixed after construction, call
     fix_fields().
   */
-  return (!suv || suv->fix_fields(thd, it) || suv->check() || suv->update());
+  return (!suv || suv->fix_fields(thd, it) || suv->check(0) || suv->update());
 }
 
 

sql/item_func.h

@@ -54,7 +54,7 @@ class Item_func :public Item_result_field
 		  SP_POINTN,SP_GEOMETRYN,SP_INTERIORRINGN,
                   NOT_FUNC, NOT_ALL_FUNC,
                   NOW_FUNC, TRIG_COND_FUNC,
-                  GUSERVAR_FUNC, COLLATE_FUNC,
+                  SUSERVAR_FUNC, GUSERVAR_FUNC, COLLATE_FUNC,
                   EXTRACT_FUNC, CHAR_TYPECAST_FUNC, FUNC_SP, UDF_FUNC };
   enum optimize_type { OPTIMIZE_NONE,OPTIMIZE_KEY,OPTIMIZE_OP, OPTIMIZE_NULL,
                        OPTIMIZE_EQUAL };
@@ -1167,13 +1167,15 @@ class Item_func_set_user_var :public Item_func
   Item_func_set_user_var(LEX_STRING a,Item *b)
     :Item_func(b), cached_result_type(INT_RESULT), name(a)
   {}
+  enum Functype functype() const { return SUSERVAR_FUNC; }
   double val_real();
   longlong val_int();
   String *val_str(String *str);
   my_decimal *val_decimal(my_decimal *);
   bool update_hash(void *ptr, uint length, enum Item_result type,
   		   CHARSET_INFO *cs, Derivation dv, bool unsigned_arg= 0);
-  bool check();
+  bool send(Protocol *protocol, String *str_arg);
+  bool check(bool use_result_field);
   bool update();
   enum Item_result result_type () const { return cached_result_type; }
   bool fix_fields(THD *thd, Item **ref);

sql/set_var.cc

@@ -3252,7 +3252,7 @@ int set_var_user::check(THD *thd)
     0 can be passed as last argument (reference on item)
   */
   return (user_var_item->fix_fields(thd, (Item**) 0) ||
-	  user_var_item->check()) ? -1 : 0;
+	  user_var_item->check(0)) ? -1 : 0;
 }
 
 

sql/sql_class.cc

@@ -1883,7 +1883,7 @@ bool select_dumpvar::send_data(List<Item> &items)
     {
       if ((xx=li++))
       {
-        xx->check();
+        xx->check(0);
 	xx->update();
       }
     }

sql/sql_select.cc

@@ -13388,7 +13388,9 @@ change_to_use_tmp_fields(THD *thd, Item **ref_pointer_array,
   {
     Field *field;
     
-    if (item->with_sum_func && item->type() != Item::SUM_FUNC_ITEM)
+    if ((item->with_sum_func && item->type() != Item::SUM_FUNC_ITEM) ||
+        (item->type() == Item::FUNC_ITEM &&
+         ((Item_func*)item)->functype() == Item_func::SUSERVAR_FUNC))
       item_field= item;
     else
     {