Bug#32770: LAST_DAY() returns a DATE, but somehow internally keeps track of the TIME.

LAST_DAY() says it returns a DATE, not a DATETIME, but didn't zero the time fields.
Adapted from a patch kindly supplied by Claudio Cherubino.

mysql-test/r/func_time.result

@@ -1282,4 +1282,7 @@ DATE_ADD('20071108',       INTERVAL 1 DAY)
 select DATE_ADD(20071108,         INTERVAL 1 DAY);
 DATE_ADD(20071108,         INTERVAL 1 DAY)
 2007-11-09
+select LAST_DAY('2007-12-06 08:59:19.05') - INTERVAL 1 SECOND;
+LAST_DAY('2007-12-06 08:59:19.05') - INTERVAL 1 SECOND
+2007-12-30 23:59:59
 End of 5.0 tests

mysql-test/t/func_time.test

@@ -797,4 +797,11 @@ select DATE_ADD(20071108181000,   INTERVAL 1 DAY);
 select DATE_ADD('20071108',       INTERVAL 1 DAY);
 select DATE_ADD(20071108,         INTERVAL 1 DAY);
 
+#
+# Bug#32770: LAST_DAY() returns a DATE, but somehow internally keeps
+#            track of the TIME.
+#
+
+select LAST_DAY('2007-12-06 08:59:19.05') - INTERVAL 1 SECOND;
+
 --echo End of 5.0 tests

sql/item_timefunc.cc

@@ -3411,6 +3411,8 @@ bool Item_func_last_day::get_date(MYSQL_TIME *ltime, uint fuzzy_date)
   ltime->day= days_in_month[month_idx];
   if ( month_idx == 1 && calc_days_in_year(ltime->year) == 366)
     ltime->day= 29;
+  ltime->hour= ltime->minute= ltime->second= 0;
+  ltime->second_part= 0;
   ltime->time_type= MYSQL_TIMESTAMP_DATE;
   return 0;
 }