Stupid PLW-07202 warning

Question

Hi,
I get a stupid bunch of warning when compiling this under 11.1.0.7:
create table test ( t varchar2(50) );
create or replace procedure test_warn as
    BEGIN
        INSERT INTO test (t)
             SELECT  substr('blah', 1, 2)
                       FROM dual;
  END;
SP2-0804: Procedure created with compilation warnings
show errors
Errors for PROCEDURE TEST_WARN:
LINE/COL ERROR
6/37     PLW-07202: bind type would result in conversion away from column type
6/40     PLW-07202: bind type would result in conversion away from column typeThe locations point to the "1" and "2" parameters in substr(). WTF???
Thanks,
Chris

Answer 1

What is the database trying to warn me from precisely?Looks like Bug 5983734: SPURIOUS PLW-07202, which still holds in 11gR2:
SQL> select * from v$version where rownum = 1
BANNER                                                                         
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production         
1 row selected.
SQL> alter session set plsql_warnings='enable:all'
Session altered.
SQL> create table t (a varchar2(40))
Table created.
SQL> alter system flush shared_pool
System altered.
SQL> create or replace procedure p as
begin
insert into t values (substr('abc',1,2));
end;
Procedure created.
SQL> show err
Errors for PROCEDURE P
LINE/COL ERROR                                                           
3/37     PLW-07202: bind type would result in conversion away from column
         type                                                            
3/39     PLW-07202: bind type would result in conversion away from column
         type                                                            
1/1      PLW-05018: unit P omitted optional AUTHID clause; default value D
         EFINER used                                                     
SQL> exec p
PL/SQL procedure successfully completed.
SQL> select  sql_text from v$sql
where   lower(sql_text) not like '%v$sql$'
and     lower(sql_text) like 'insert into t values%'
SQL_TEXT                                                                       
INSERT INTO T VALUES (SUBSTR('abc',1,2))                                       
1 row selected.
/* no binding takes place at all, so a message about binding seems non-sensical. */
SQL> alter system flush shared_pool
System altered.
SQL> create or replace procedure p as
s varchar2(3) := 'abc';
s1 int := 1;
s2 int := 1;
begin
insert into t values (substr(s, s1, s2));
end;
Procedure created.
SQL> show err
Errors for PROCEDURE P
LINE/COL ERROR                                                           
6/34     PLW-07202: bind type would result in conversion away from column
         type                                                            
6/38     PLW-07202: bind type would result in conversion away from column
         type                                                            
1/1      PLW-05018: unit P omitted optional AUTHID clause; default value D
         EFINER used                                                     
SQL> exec p
PL/SQL procedure successfully completed.
SQL> select  sql_text from v$sql
where   lower(sql_text) not like '%v$sql$'
and     lower(sql_text) like 'insert into t values%'
SQL_TEXT                                                                       
INSERT INTO T VALUES (SUBSTR(:B3 , :B2 , :B1 ))                                
1 row selected.
But (1) the datatypes of the PL/SQL variables that are bound are exactly
right for Substr(). And (2), the binding occurs in an expression that's that
right-hand-side for "set <column> =" so there's possibility of an index
being in use.
*/