Bug #30981 CHAR(0x41 USING ucs2) doesn't add leading zero

Description:
CHAR(0x41 USING ucs2)  doesn't add leading zero and returns a wrong ucs2 string.

How to repeat:
mysql> select hex(char(0x41 using ucs2));
+----------------------------+
| hex(char(0x41 using ucs2)) |
+----------------------------+
| 41                         |
+----------------------------+
1 row in set, 1 warning (0.00 sec)

The expected result is 0041.

Note, a hex literal with character set introducer works fine:

mysql> select hex(_ucs2 0x41);
+-----------------+
| hex(_ucs2 0x41) |
+-----------------+
| 0041            |
+-----------------+
1 row in set (0.00 sec)

Suggested fix:
Fix CHAR(..USING..) to pad leading zero, like a literal with introducer does.

Thank you for the bug report.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/35292

ChangeSet@1.2536, 2007-10-10 19:55:01+05:00, gluh@mysql.com +9 -0
  Bug#30981 CHAR(0x41 USING ucs2) doesn't add leading zero
  Bug#30982 CHAR(..USING..) can return a not-well-formed string
  Bug#30986 Character set introducer followed by a HEX string can return bad result
  check_well_formed_result moved to Item
  fixed Item_func_char::val_str for proper ucs symbols converting
  added check for well formed strings for correct conversion of constants with underscore carset

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/35327

ChangeSet@1.2536, 2007-10-11 13:46:50+05:00, gluh@mysql.com +9 -0
  Bug#30981 CHAR(0x41 USING ucs2) doesn't add leading zero
  Bug#30982 CHAR(..USING..) can return a not-well-formed string
  Bug#30986 Character set introducer followed by a HEX string can return bad result
  check_well_formed_result moved to Item from Item_str_func
  fixed Item_func_char::val_str for proper ucs symbols converting
  added check for well formed strings for correct conversion of constants with underscore
  charset

Ok to push

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/35339

ChangeSet@1.2537, 2007-10-11 16:07:10+05:00, gluh@mysql.com +9 -0
  Bug#30981 CHAR(0x41 USING ucs2) doesn't add leading zero
  Bug#30982 CHAR(..USING..) can return a not-well-formed string
  Bug#30986 Character set introducer followed by a HEX string can return bad result
  check_well_formed_result moved to Item from Item_str_func
  fixed Item_func_char::val_str for proper ucs symbols converting
  added check for well formed strings for correct conversion of constants with underscore
  charset

Pushed into 5.0.52

Pushed into 5.1.23-beta

Pushed into 6.0.4-alpha

Noted in 5.0.52, 5.1.23, 6.0.4 changelogs.

The result from CHAR(str USING ucs2) did not add a leading 0x00 byte
for input strings with an odd number of bytes.