bugfix: Item_cache_temporal::convert_to_basic_const_item assumed DATETIME

this is a 10.3 version of 1c6f6dc8

mysql-test/main/derived_cond_pushdown.result

@@ -11819,7 +11819,7 @@ EXPLAIN
             "access_type": "ALL",
             "rows": 3,
             "filtered": 100,
-            "attached_condition": "t1.i = TIMESTAMP'2007-05-28 00:00:00'"
+            "attached_condition": "t1.i = DATE'2007-05-28'"
           }
         }
       }

sql/item.cc

@@ -10168,17 +10168,32 @@ Item *Item_cache_temporal::convert_to_basic_const_item(THD *thd)
   Item *new_item;
   DBUG_ASSERT(value_cached || example != 0);
   if (null_value)
-    new_item= (Item*) new (thd->mem_root) Item_null(thd);
+    return new (thd->mem_root) Item_null(thd);
   else
-  {
-    MYSQL_TIME ltime;
-    unpack_time(val_datetime_packed(), &ltime, MYSQL_TIMESTAMP_DATETIME);
-    new_item= (Item*) new (thd->mem_root) Item_datetime_literal(thd, &ltime,
-                                                                decimals);
-  }
+    return make_literal(thd);
   return new_item;
 }
 
+Item *Item_cache_datetime::make_literal(THD *thd)
+{
+  MYSQL_TIME ltime;
+  unpack_time(val_datetime_packed(), &ltime, MYSQL_TIMESTAMP_DATETIME);
+  return new (thd->mem_root) Item_datetime_literal(thd, &ltime, decimals);
+}
+
+Item *Item_cache_date::make_literal(THD *thd)
+{
+  MYSQL_TIME ltime;
+  unpack_time(val_datetime_packed(), &ltime, MYSQL_TIMESTAMP_DATE);
+  return new (thd->mem_root) Item_date_literal(thd, &ltime);
+}
+
+Item *Item_cache_time::make_literal(THD *thd)
+{
+  MYSQL_TIME ltime;
+  unpack_time(val_time_packed(), &ltime, MYSQL_TIMESTAMP_TIME);
+  return new (thd->mem_root) Item_time_literal(thd, &ltime, decimals);
+}
 
 bool Item_cache_real::cache_value()
 {

sql/item.h

@@ -6169,6 +6169,7 @@ class Item_cache_temporal: public Item_cache_int
   */
   Item *clone_item(THD *thd);
   Item *convert_to_basic_const_item(THD *thd);
+  virtual Item *make_literal(THD *) =0;
 };
 
 
@@ -6180,6 +6181,7 @@ class Item_cache_time: public Item_cache_temporal
   bool cache_value();
   Item *get_copy(THD *thd)
   { return get_item_copy<Item_cache_time>(thd, this); }
+  Item *make_literal(THD *);
 };
 
 
@@ -6190,6 +6192,7 @@ class Item_cache_datetime: public Item_cache_temporal
    :Item_cache_temporal(thd, &type_handler_datetime2) { }
   Item *get_copy(THD *thd)
   { return get_item_copy<Item_cache_datetime>(thd, this); }
+  Item *make_literal(THD *);
 };
 
 
@@ -6200,6 +6203,7 @@ class Item_cache_date: public Item_cache_temporal
    :Item_cache_temporal(thd, &type_handler_newdate) { }
   Item *get_copy(THD *thd)
   { return get_item_copy<Item_cache_date>(thd, this); }
+  Item *make_literal(THD *);
 };