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, 18 insertions, 7 deletions

diff --git a/sql/sql_type.cc b/sql/sql_type.cc
index ee25a6c4fc5..8757d2fef59 100644
--- a/sql/sql_type.cc
+++ b/sql/sql_type.cc
@@ -23,6 +23,12 @@
 #include "log.h"
 #include "tztime.h"
 
+const DTCollation &DTCollation_numeric::singleton()
+{
+  static const DTCollation_numeric tmp;
+  return tmp;
+}
+
 Type_handler_row         type_handler_row;
 
 Type_handler_null        type_handler_null;
@@ -5659,7 +5665,7 @@ bool Type_handler_row::
 bool Type_handler_int_result::
        Item_func_round_fix_length_and_dec(Item_func_round *item) const
 {
-  item->fix_arg_int(this);
+  item->fix_arg_int(this, item->arguments()[0]);
   return false;
 }
 
@@ -5667,7 +5673,7 @@ bool Type_handler_int_result::
 bool Type_handler_year::
        Item_func_round_fix_length_and_dec(Item_func_round *item) const
 {
-  item->fix_arg_int(&type_handler_long); // 10.5 merge: fix to type_handler_ulong
+  item->fix_arg_int(&type_handler_long, item->arguments()[0]); // 10.5 merge: fix to type_handler_ulong
   return false;
 }
 
@@ -5675,7 +5681,7 @@ bool Type_handler_year::
 bool Type_handler_hex_hybrid::
        Item_func_round_fix_length_and_dec(Item_func_round *item) const
 {
-  item->fix_arg_int(NULL);
+  item->fix_arg_int(NULL, NULL);
   return false;
 }
 
@@ -5713,10 +5719,12 @@ bool Type_handler_decimal_result::
 }
 
 
-bool Type_handler_temporal_result::
+bool Type_handler_date_common::
        Item_func_round_fix_length_and_dec(Item_func_round *item) const
 {
-  item->fix_arg_double();
+  static const Type_std_attributes attr(8, 0/*dec*/, true/*unsigned*/,
+                                        DTCollation_numeric::singleton());
+  item->fix_arg_int(&type_handler_long, &attr); // 10.5 merge: fix to *_ulong
   return false;
 }
 
@@ -5831,10 +5839,13 @@ bool Type_handler_decimal_result::
 }
 
 
-bool Type_handler_temporal_result::
+bool Type_handler_date_common::
        Item_func_int_val_fix_length_and_dec(Item_func_int_val *item) const
 {
-  item->fix_length_and_dec_int_or_decimal();
+  static const Type_std_attributes attr(8, 0/*dec*/, true/*unsigned*/,
+                                        DTCollation_numeric::singleton());
+  item->Type_std_attributes::set(attr);
+  item->set_handler(&type_handler_long); // 10.5 merge: fix to *_ulong
   return false;
 }