MDEV-23351 Rounding functions return wrong data types for DATE input

Fixing ROUND(date,0), TRUNCATE(date,x), FLOOR(date), CEILING(date)
to return the `int(8) unsigned` data type.

Details:
1. Cleanup: moving virtual implementations
   - Type_handler_temporal_result::Item_func_int_val_fix_length_and_dec()
   - Type_handler_temporal_result::Item_func_round_fix_length_and_dec()
   to Type_handler_date_common. Other temporal data type handlers
   override these methods anyway. So they were only DATE specific.
   This change makes the code clearer.
2. Backporting DTCollation_numeric from 10.5, to reuse the code easier.
3. Adding the `preferred_attrs` argument to Item_func_round::fix_arg_int(). Now
   Type_handler_xxx::Item_func_round_val_fix_length_and_dec() work as follows:
   - The INT-alike and YEAR handlers copy preferred_attrs from args[0].
   - The DATE handler passes explicit attributes, to get `int(8) unsigned`.
   - The hex hybrid handler passes NULL, so fix_arg_int() calculates attributes.
4. Type_handler_date_common::Item_func_int_val_fix_length_and_dec()
   now sets the type handler and attributes to get `int(8) unsigned`.

1 files changed, 14 insertions, 0 deletions

diff --git a/mysql-test/main/type_date.result b/mysql-test/main/type_date.result
index 616ba0a4529..f40a27e5f5c 100644
--- a/mysql-test/main/type_date.result
+++ b/mysql-test/main/type_date.result
@@ -1089,5 +1089,19 @@ CAST(1012.5 AS DATE) * 1.0
 Warnings:
 Note	1292	Truncated incorrect date value: '1012.5'
 #
+# MDEV-23351 Rounding functions return wrong data types for DATE input
+#
+CREATE TABLE t1 (a date);
+CREATE TABLE t2 AS SELECT FLOOR(a), CEIL(a),ROUND(a),TRUNCATE(a,0) FROM t1;
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `FLOOR(a)` int(8) unsigned DEFAULT NULL,
+  `CEIL(a)` int(8) unsigned DEFAULT NULL,
+  `ROUND(a)` int(8) unsigned DEFAULT NULL,
+  `TRUNCATE(a,0)` int(8) unsigned DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t2,t1;
+#
 # End of 10.4 tests
 #