lp:737104 Crash in DTCollation::set in 5.1-micro

and a different fix for lp:736370

cache temporal expression in Item_cache_int, not in Item_string.
invoke get_datetime_value() to create a correct Item_cache_int.
Implement Item_cache_int::clone, as it's a proper constant

1 files changed, 6 insertions, 0 deletions

diff --git a/sql/item.h b/sql/item.h
index af0f3d1c024..d45df4ebe53 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -3035,6 +3035,12 @@ public:
   my_decimal *val_decimal(my_decimal *);
   enum Item_result result_type() const { return INT_RESULT; }
   bool cache_value();
+  Item *clone_item()
+  {
+    Item_cache_int *item= new Item_cache_int(cached_field_type);
+    item->store(this, value);
+    return item;
+  }
 };