Fixed Bug#3115. CAST AS DATE with malformed string returns NULL but IS NULL

is false.

BitKeeper/etc/logging_ok

@@ -59,6 +59,7 @@ jani@rhols221.arenanet.fi
 jani@ua126d19.elisa.omakaista.fi
 jani@ua141d10.elisa.omakaista.fi
 jani@ua167d18.elisa.omakaista.fi
+jani@ua72d24.elisa.omakaista.fi
 jcole@abel.spaceapes.com
 jcole@main.burghcom.com
 jcole@mugatu.spaceapes.com

mysql-test/r/create.result

@@ -104,9 +104,9 @@ drop table t2;
 create table t2 select CAST("2001-12-29" AS DATE) as d, CAST("20:45:11" AS TIME) as t, CAST("2001-12-29  20:45:11" AS DATETIME) as dt;
 describe t2;
 Field	Type	Null	Key	Default	Extra
-d	date			0000-00-00	
-t	time			00:00:00	
-dt	datetime			0000-00-00 00:00:00	
+d	date	YES		NULL	
+t	time	YES		NULL	
+dt	datetime	YES		NULL	
 drop table t1,t2;
 create table t1 (a tinyint);
 create table t2 (a int) select * from t1;
@@ -396,12 +396,12 @@ Field	Type	Null	Key	Default	Extra
 a	int(11)	YES		NULL	
 b	bigint(11)			0	
 c	bigint(10)			0	
-d	date			0000-00-00	
+d	date	YES		NULL	
 e	char(1)				
-f	datetime			0000-00-00 00:00:00	
-g	time			00:00:00	
+f	datetime	YES		NULL	
+g	time	YES		NULL	
 h	longblob				
-dd	time			00:00:00	
+dd	time	YES		NULL	
 select * from t2;
 a	b	c	d	e	f	g	h	dd
 1	-7	7	2000-01-01	b	2000-01-01 00:00:00	05:04:03	yet another binary data	02:00:00

mysql-test/r/func_sapdb.result

@@ -159,14 +159,14 @@ time("1997-12-31 23:59:59.000001") as f9;
 describe t1;
 Field	Type	Null	Key	Default	Extra
 f1	date			0000-00-00	
-f2	datetime			0000-00-00 00:00:00	
-f3	time			00:00:00	
+f2	datetime	YES		NULL	
+f3	time	YES		NULL	
 f4	time			00:00:00	
 f5	time			00:00:00	
 f6	time			00:00:00	
-f7	datetime			0000-00-00 00:00:00	
-f8	date			0000-00-00	
-f9	time			00:00:00	
+f7	datetime	YES		NULL	
+f8	date	YES		NULL	
+f9	time	YES		NULL	
 select * from t1;
 f1	f2	f3	f4	f5	f6	f7	f8	f9
 1997-01-01	1998-01-02 01:01:00	49:01:01	46:58:57	-23:59:59	10:11:12	2001-12-01 01:01:01	1997-12-31	23:59:59

sql/item_timefunc.h

@@ -610,6 +610,19 @@ public:
 };
 
 
+class Item_typecast_maybe_null :public Item_typecast
+{
+public:
+  Item_typecast_maybe_null(Item *a) :Item_typecast(a) {}
+  void fix_length_and_dec()
+  {
+    collation.set(&my_charset_bin);
+    max_length=args[0]->max_length;
+    maybe_null= 1;
+  }
+};
+
+
 class Item_char_typecast :public Item_typecast
 {
   int cast_length;
@@ -626,10 +639,10 @@ public:
 };
 
 
-class Item_date_typecast :public Item_typecast
+class Item_date_typecast :public Item_typecast_maybe_null
 {
 public:
-  Item_date_typecast(Item *a) :Item_typecast(a) {}
+  Item_date_typecast(Item *a) :Item_typecast_maybe_null(a) {}
   String *val_str(String *str);
   bool get_date(TIME *ltime, uint fuzzy_date);
   const char *cast_type() const { return "date"; }
@@ -641,10 +654,10 @@ public:
 };
 
 
-class Item_time_typecast :public Item_typecast
+class Item_time_typecast :public Item_typecast_maybe_null
 {
 public:
-  Item_time_typecast(Item *a) :Item_typecast(a) {}
+  Item_time_typecast(Item *a) :Item_typecast_maybe_null(a) {}
   String *val_str(String *str);
   bool get_time(TIME *ltime);
   const char *cast_type() const { return "time"; }
@@ -656,10 +669,10 @@ public:
 };
 
 
-class Item_datetime_typecast :public Item_typecast
+class Item_datetime_typecast :public Item_typecast_maybe_null
 {
 public:
-  Item_datetime_typecast(Item *a) :Item_typecast(a) {}
+  Item_datetime_typecast(Item *a) :Item_typecast_maybe_null(a) {}
   String *val_str(String *str);
   const char *cast_type() const { return "datetime"; }
   enum_field_types field_type() const { return MYSQL_TYPE_DATETIME; }