Bug #5228 ORDER BY CAST(enumcol) sorts incorrectly under certain conditions

mysql-test/r/cast.result

@@ -155,3 +155,26 @@ NULL
 select cast(NULL as BINARY);
 cast(NULL as BINARY)
 NULL
+CREATE TABLE t1 (a enum ('aac','aab','aaa') not null);
+INSERT INTO t1 VALUES ('aaa'),('aab'),('aac');
+SELECT a, CAST(a AS CHAR) FROM t1 ORDER BY CAST(a AS UNSIGNED) ;
+a	CAST(a AS CHAR)
+aac	aac
+aab	aab
+aaa	aaa
+SELECT a, CAST(a AS CHAR(3)) FROM t1 ORDER BY CAST(a AS CHAR(2)), a;
+a	CAST(a AS CHAR(3))
+aac	aac
+aab	aab
+aaa	aaa
+SELECT a, CAST(a AS UNSIGNED) FROM t1 ORDER BY CAST(a AS CHAR) ;
+a	CAST(a AS UNSIGNED)
+aaa	3
+aab	2
+aac	1
+SELECT a, CAST(a AS CHAR(2)) FROM t1 ORDER BY CAST(a AS CHAR(3)), a;
+a	CAST(a AS CHAR(2))
+aaa	aa
+aab	aa
+aac	aa
+DROP TABLE t1;

mysql-test/t/cast.test

@@ -95,3 +95,16 @@ select cast("2001-1-1" as datetime) = "2001-01-01 00:00:00";
 select cast("1:2:3" as TIME) = "1:02:03";
 select cast(NULL as DATE);
 select cast(NULL as BINARY);
+
+#
+# Bug #5228 ORDER BY CAST(enumcol) sorts incorrectly under certain conditions
+#
+CREATE TABLE t1 (a enum ('aac','aab','aaa') not null);
+INSERT INTO t1 VALUES ('aaa'),('aab'),('aac');
+# these two should be in enum order
+SELECT a, CAST(a AS CHAR) FROM t1 ORDER BY CAST(a AS UNSIGNED) ;
+SELECT a, CAST(a AS CHAR(3)) FROM t1 ORDER BY CAST(a AS CHAR(2)), a;
+# these two should be in alphabetic order
+SELECT a, CAST(a AS UNSIGNED) FROM t1 ORDER BY CAST(a AS CHAR) ;
+SELECT a, CAST(a AS CHAR(2)) FROM t1 ORDER BY CAST(a AS CHAR(3)), a;
+DROP TABLE t1;

sql/item_func.h

@@ -214,6 +214,7 @@ class Item_func_signed :public Item_int_func
 {
 public:
   Item_func_signed(Item *a) :Item_int_func(a) {}
+  const char *func_name() const { return "cast_as_signed"; }
   double val()
   {
     double tmp= args[0]->val();
@@ -236,6 +237,7 @@ class Item_func_unsigned :public Item_func_signed
 {
 public:
   Item_func_unsigned(Item *a) :Item_func_signed(a) {}
+  const char *func_name() const { return "cast_as_unsigned"; }
   void fix_length_and_dec()
   { max_length=args[0]->max_length; unsigned_flag=1; }
   void print(String *str);

sql/item_timefunc.cc

@@ -2059,6 +2059,24 @@ bool Item_extract::eq(const Item *item, bool binary_cmp) const
 }
 
 
+bool Item_char_typecast::eq(const Item *item, bool binary_cmp) const
+{
+  if (this == item)
+    return 1;
+  if (item->type() != FUNC_ITEM ||
+      func_name() != ((Item_func*)item)->func_name())
+    return 0;
+
+  Item_char_typecast *cast= (Item_char_typecast*)item;
+  if (cast_length != cast->cast_length ||
+      cast_cs     != cast->cast_cs)
+    return 0;
+
+  if (!args[0]->eq(cast->args[0], binary_cmp))
+      return 0;
+  return 1;
+}
+
 void Item_typecast::print(String *str)
 {
   str->append("cast(", 5);

sql/item_timefunc.h

@@ -683,6 +683,8 @@ class Item_char_typecast :public Item_typecast
 public:
   Item_char_typecast(Item *a, int length_arg, CHARSET_INFO *cs_arg)
     :Item_typecast(a), cast_length(length_arg), cast_cs(cs_arg) {}
+  bool eq(const Item *item, bool binary_cmp) const;
+  const char *func_name() const { return "cast_as_char"; }
   const char* cast_type() const { return "char"; };
   String *val_str(String *a);
   void fix_length_and_dec();
@@ -694,6 +696,7 @@ class Item_date_typecast :public Item_typecast_maybe_null
 {
 public:
   Item_date_typecast(Item *a) :Item_typecast_maybe_null(a) {}
+  const char *func_name() const { return "cast_as_date"; }
   String *val_str(String *str);
   bool get_date(TIME *ltime, uint fuzzy_date);
   const char *cast_type() const { return "date"; }
@@ -709,6 +712,7 @@ class Item_time_typecast :public Item_typecast_maybe_null
 {
 public:
   Item_time_typecast(Item *a) :Item_typecast_maybe_null(a) {}
+  const char *func_name() const { return "cast_as_time"; }
   String *val_str(String *str);
   bool get_time(TIME *ltime);
   const char *cast_type() const { return "time"; }
@@ -724,6 +728,7 @@ class Item_datetime_typecast :public Item_typecast_maybe_null
 {
 public:
   Item_datetime_typecast(Item *a) :Item_typecast_maybe_null(a) {}
+  const char *func_name() const { return "cast_as_datetime"; }
   String *val_str(String *str);
   const char *cast_type() const { return "datetime"; }
   enum_field_types field_type() const { return MYSQL_TYPE_DATETIME; }