CAST function in PL/SQL

Question

Hello folks,
<br>
has anybody a reasonable explanation for this weird behaviour concerning the CAST function? <br>
I am using 9iR2. <br>
Following runs fine eventhough I would expect an error:
<p>
SQL> DECLARE
   i   INTEGER;
   x   VARCHAR2 (1) := 'x';
BEGIN
   i := CAST (1 AS x);
   DBMS_OUTPUT.put_line ('i=' || i);
END;
i=1
PL/SQL procedure successfully completed.<p>
BUT simply hardcoding the "datatype" raises an error:
<p>
SQL> DECLARE
   i   INTEGER;
   x   VARCHAR2 (1) := 'x';
BEGIN
   i := CAST (1 AS 'x');
   DBMS_OUTPUT.put_line ('i=' || i);
END;
Error at line 11
ORA-06550: line 5, column 20:
PLS-00103: Encountered the symbol "x" when expecting one of the following:
   <an identifier> <a double-quoted delimited-identifier> LONG_
   double ref char time timestamp interval date binary national
   character nchar
The symbol "<an identifier> was inserted before "x" to continue.<p>
Whats going on here?

Answer 1

It's trying to cast to x%type, which is DATE. But even if you replace it with DATE you get the same error.
  1  DECLARE
  2     i   DATE;
  3     x   DATE;
  4  BEGIN
  5     i := CAST (SYSDATE AS date);
  6* END;
cmsgpro_user@XOPDEV> /
   i := CAST (SYSDATE AS date);
ERROR at line 5:
ORA-06550: line 5, column 15:
PLS-00382: expression is of wrong type
ORA-06550: line 5, column 4:
PL/SQL: Statement ignored
cmsgpro_user@XOPDEV> ED
Wrote file afiedt.buf
  1  DECLARE
  2     i   DATE;
  3     x   DATE;
  4  BEGIN
  5     i := CAST (SYSDATE AS VARCHAR2);
  6* END;
cmsgpro_user@XOPDEV> /
PL/SQL procedure successfully completed.