Bugfix for lounchpad bug#608834 (608824, 609045, 609052).

Added get_tmp_table_item() to cache wrapper as it has all not simple Items (Item_func, Item_field, Item_subquery).

mysql-test/r/subquery_cache.result:
  Tests for bugs fixed.
mysql-test/t/subquery_cache.test:
  Tests for bugs fixed.
sql/item.cc:
  Added get_tmp_table_item() to cache wrapper as it has all not simple Items (Item_func, Item_field, Item_subquery).
sql/item.h:
  Added get_tmp_table_item() to cache wrapper as it has all not simple Items (Item_func, Item_field, Item_subquery).

sql/item.cc

@@ -6966,6 +6966,14 @@ int Item_cache_wrapper::save_in_field(Field *to, bool no_conversions)
 }
 
 
+Item* Item_cache_wrapper::get_tmp_table_item(THD *thd_arg)
+{
+  if (!orig_item->with_sum_func && !orig_item->const_item())
+    return new Item_field(result_field);
+  return copy_or_same(thd_arg);
+}
+
+
 /**
   Prepare referenced field then call usual Item_direct_ref::fix_fields .
 

sql/item.h

@@ -2624,6 +2624,7 @@ class Item_cache_wrapper :public Item_result_field
   {
     save_val(result_field);
   }
+  Item* get_tmp_table_item(THD *thd_arg);
 
   /* Following methods make this item transparent as much as possible */