Bug#46362: Endpoint should be set to false for TO_DAYS(DATE)

There were a problem since pruning uses the field
for comparison (while evaluate_join_record uses longlong),
resulting in pruning failures when comparing DATE to DATETIME.

Fix was to always comparing DATE vs DATETIME as DATETIME,
by adding ' 00:00:00' to the DATE string.

And adding optimization for comparing with 23:59:59, so that
DATETIME_col > '2001-02-03 23:59:59' ->
TO_DAYS(DATETIME_col) > TO_DAYS('2001-02-03 23:59:59') instead
of '>='.

mysql-test/r/partition_pruning.result:
  Bug#46362: Endpoint should be set to false for TO_DAYS(DATE)
  
  Updated result-file
mysql-test/t/partition_pruning.test:
  Bug#46362: Endpoint should be set to false for TO_DAYS(DATE)
  
  Added testcases.
sql-common/my_time.c:
  Bug#46362: Endpoint should be set to false for TO_DAYS(DATE)
  
  removed duplicate assignment.
sql/item.cc:
  Bug#46362: Endpoint should be set to false for TO_DAYS(DATE)
  
  Changed field_is_equal_to_item into field_cmp_to_item, to
  better handling DATE vs DATETIME comparision.
sql/item.h:
  Bug#46362: Endpoint should be set to false for TO_DAYS(DATE)
  
  Updated comment
sql/item_timefunc.cc:
  Bug#46362: Endpoint should be set to false for TO_DAYS(DATE)
  
  Added optimization (pruning) of DATETIME where time-part is
  23:59:59
sql/opt_range.cc:
  Bug#46362: Endpoint should be set to false for TO_DAYS(DATE)
  
  Using the new stored_field_cmp_to_item for better pruning.

1 files changed, 7 insertions, 3 deletions

diff --git a/sql/item_timefunc.cc b/sql/item_timefunc.cc
index d79b0b02998..eebede32f8d 100644
--- a/sql/item_timefunc.cc
+++ b/sql/item_timefunc.cc
@@ -991,15 +991,19 @@ longlong Item_func_to_days::val_int_endpoint(bool left_endp, bool *incl_endp)
     point to day bound ("strictly less" comparison stays intact):
 
       col < '2007-09-15 00:00:00'  -> TO_DAYS(col) <  TO_DAYS('2007-09-15')
+      col > '2007-09-15 23:59:59'  -> TO_DAYS(col) >  TO_DAYS('2007-09-15')
 
     which is different from the general case ("strictly less" changes to
     "less or equal"):
 
       col < '2007-09-15 12:34:56'  -> TO_DAYS(col) <= TO_DAYS('2007-09-15')
   */
-  if (!left_endp && !(ltime.hour || ltime.minute || ltime.second ||
-                      ltime.second_part))
-    ; /* do nothing */
+  if ((!left_endp && !(ltime.hour || ltime.minute || ltime.second ||
+                       ltime.second_part)) ||
+       (left_endp && ltime.hour == 23 && ltime.minute == 59 &&
+        ltime.second == 59))
+    /* do nothing */
+    ;
   else
     *incl_endp= TRUE;
   return res;