Bug#57512 str_to_date crash...

str_to_date function should only try to generate a warning for
invalid input strings, not when input value is NULL. In latter
case, val_str() of input argument will return a nil pointer.
Trying to generate a warning using this pointer lead to a
segmentation fault. Solution: Only generate warning when pointer
to input string is non-nil.

mysql-test/r/func_time.result

@@ -1327,3 +1327,12 @@ SELECT * FROM t1 WHERE date_date <= addtime(date_add("2000-1-1", INTERVAL "1:1:1
 date_date
 DROP TABLE t1;
 #
+# Bug#57512 str_to_date crash...
+#
+SELECT WEEK(STR_TO_DATE(NULL,0));
+WEEK(STR_TO_DATE(NULL,0))
+NULL
+SELECT SUBDATE(STR_TO_DATE(NULL,0), INTERVAL 1 HOUR);
+SUBDATE(STR_TO_DATE(NULL,0), INTERVAL 1 HOUR)
+NULL
+#

mysql-test/t/func_time.test

@@ -842,5 +842,13 @@ INSERT INTO t1 VALUES ('2008-01-03 00:00:00'), ('2008-01-03 00:00:00');
 SELECT * FROM t1 WHERE date_date >= subtime(now(), "00:30:00");
 SELECT * FROM t1 WHERE date_date <= addtime(date_add("2000-1-1", INTERVAL "1:1:1" HOUR_SECOND), "00:20:00");
 DROP TABLE t1;
+
+--echo #
+--echo # Bug#57512 str_to_date crash...
+--echo #
+
+SELECT WEEK(STR_TO_DATE(NULL,0));
+SELECT SUBDATE(STR_TO_DATE(NULL,0), INTERVAL 1 HOUR);
+
 --echo #
 

sql/item_timefunc.cc

@@ -3465,7 +3465,7 @@ bool Item_func_str_to_date::get_date(MYSQL_TIME *ltime, uint fuzzy_date)
   return 0;
 
 null_date:
-  if (fuzzy_date & TIME_NO_ZERO_DATE)
+  if (val && (fuzzy_date & TIME_NO_ZERO_DATE))
   {
     char buff[128];
     strmake(buff, val->ptr(), min(val->length(), sizeof(buff)-1));