explain extended SELECT *

FROM (SELECT  date('2018-01-01') AS DAT

UNION ALL

SELECT  date('2018-01-01') AS DAT) AS t

WHERE t.DAT BETWEEN date ('2017-01-01') AND date ('2019-01-01');

id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra

1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where

2	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE

3	UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE

Warnings:

Note	1003	select `t`.`DAT` AS `DAT` from (select cast('2018-01-01' as date) AS `DAT` union all select cast('2018-01-01' as date) AS `DAT`) `t` where `t`.`DAT` between <cache>(cast('2017-01-01' as date)) and <cache>(cast('2019-01-01' as date))

explain extended SELECT *

FROM (SELECT  date('2018-01-01') AS d) AS t

WHERE t.d BETWEEN date ('2017-01-01') AND date ('2019-01-01');

id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra

1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables

2	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE

Warnings:

Note	1003	select NULL AS `d` from (select cast('2018-01-01' as date) AS `d`) `t` where 0

explain extended SELECT *

FROM (SELECT  date('2018-01-01') AS DAT

UNION ALL

SELECT  date('2018-01-01') AS DAT) AS t

WHERE t.DAT BETWEEN date ('2017-01-01') AND date ('2019-01-01');

id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra

1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where

2	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used

3	UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used

Warnings:

Note	1003	select `t`.`DAT` AS `DAT` from (select cast('2018-01-01' as date) AS `DAT` union all select cast('2018-01-01' as date) AS `DAT`) `t` where `t`.`DAT` between <cache>(cast('2017-01-01' as date)) and <cache>(cast('2019-01-01' as date))

explain extended SELECT *

FROM (SELECT  date('2018-01-01') AS d) AS t

WHERE t.d BETWEEN date ('2017-01-01') AND date ('2019-01-01');

id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra

1	PRIMARY	<derived2>	system	NULL	NULL	NULL	NULL	1	100.00	

2	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used

Warnings:

Note	1003	select '2018-01-01' AS `d` from dual where 1

SELECT * FROM (SELECT date('2018-01-01') AS d) AS t WHERE t.d BETWEEN date ('2017-01-01') AND date ('2019-01-01');

diff --git a/sql/item.cc b/sql/item.cc

index 007b4f4..5fc68e4 100644

--- a/sql/item.cc

+++ b/sql/item.cc

@@ -9862,7 +9862,7 @@ Item *Item_cache_temporal::convert_to_basic_const_item(THD *thd)

 {

   Item *new_item;

   DBUG_ASSERT(value_cached || example != 0);

-  if (null_value)

+  if (!has_value())

     new_item= (Item*) new (thd->mem_root) Item_null(thd);

   else

   {