MDEV-12514 Split Item_temporal_func::fix_length_and_dec() + MDEV-12515

This patch implements MDEV-12514 according to the task descriptions.
It automatically fixes:
MDEV-12515 Wrong value when storing DATE_ADD() and ADDTIME() to a numeric field

Additionally:

a. Moves Item_func::set_attributes_temporal() to
   Type_str_attributes::fix_attributes_temporal(),
  which is a more proper place and name for it.

b. Continues replacing calls for:
     set_handler_by_field_type(MYSQL_TYPE_XXX)
   to corresponding:
     set_handler(&type_handler_xxx)
   which is faster.
   Note, we should eventually get rid of almost all set_handler_by_field_type().

c. Makes type_handler_string, type_handler_time2, type_handler_newdate,
   type_handler_datetime2 public.
   (all built-in handlers will become public eventually)

d. Removing Item_temporal_func::sql_mode, as it was not used.

1 files changed, 32 insertions, 0 deletions

diff --git a/mysql-test/t/func_time.test b/mysql-test/t/func_time.test
index 6e0169d97ca..e8d1d4e79e3 100644
--- a/mysql-test/t/func_time.test
+++ b/mysql-test/t/func_time.test
@@ -1817,3 +1817,35 @@ DROP TABLE t1,t2;
 --echo #
 --echo # End of 10.1 tests
 --echo #
+
+
+--echo #
+--echo # Start of 10.3 tests
+--echo #
+
+--echo #
+--echo #  MDEV-12515 Wrong value when storing DATE_ADD() and ADDTIME() to a numeric field
+--echo #
+
+SET sql_mode='';
+
+CREATE TABLE t1 AS SELECT
+  DATE_ADD('2001-01-01',INTERVAL 1 DAY) AS c1,
+  ADDTIME('10:20:30',1) AS c2;
+SHOW CREATE TABLE t1;
+SELECT * FROM t1;
+DROP TABLE t1;
+
+CREATE TABLE t2 (c INT);
+INSERT INTO t2 SELECT DATE_ADD('2001-01-01',INTERVAL 1 DAY);
+INSERT INTO t2 VALUES ('2001-01-02');
+SELECT * FROM t2;
+DROP TABLE t2;
+
+CREATE TABLE t2 (a INT);
+INSERT INTO t2 VALUES (ADDTIME('10:20:30',1));
+INSERT INTO t2 VALUES ('10:20:31');
+SELECT * FROM t2;
+DROP TABLE t2;
+
+SET sql_mode=DEFAULT;