MDEV-21319 COUNT(*) returns 1, actual SELECT returns no result in 10.3.21, but 1 result in 10.1.41

Item_ref::val_(datetime|time)_packed() erroneously called
(*ref)->val_(datetime|time)_packed().

- Fixing to call (*ref)->val_(datetime|time)_packed_result().
- Backporting Item::val_(datetime|time)_packed_result() from 10.3.
- Fixing Item_field::get_date_result() to handle null_value in the same
  way how Item_field::get_date() does.

1 files changed, 7 insertions, 0 deletions

diff --git a/sql/item.h b/sql/item.h
index fb11064f122..bea09620ef8 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -1302,6 +1302,13 @@ public:
     uint fuzzydate= TIME_FUZZY_DATES | TIME_INVALID_DATES | TIME_TIME_ONLY;
     return get_date(&ltime, fuzzydate) ? 0 : pack_time(&ltime);
   }
+  longlong val_datetime_packed_result();
+  longlong val_time_packed_result()
+  {
+    MYSQL_TIME ltime;
+    uint fuzzydate= TIME_TIME_ONLY | TIME_INVALID_DATES | TIME_FUZZY_DATES;
+    return get_date_result(&ltime, fuzzydate) ? 0 : pack_time(&ltime);
+  }
   // Get a temporal value in packed DATE/DATETIME or TIME format
   longlong val_temporal_packed(enum_field_types f_type)
   {