Bug 28902 - Add warning for downcasting to subclass in a superclass
Summary: Add warning for downcasting to subclass in a superclass
Status: CLOSED WONTFIX
Alias: None
Product: JDT
Classification: Eclipse Project
Component: Core (show other bugs)
Version: 2.1   Edit
Hardware: All All
: P3 enhancement (vote)
Target Milestone: 3.0 M5   Edit
Assignee: JDT-Core-Inbox CLA
QA Contact:
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2002-12-29 12:07 EST by Max Rydahl Andersen CLA
Modified: 2009-08-30 02:19 EDT (History)
0 users

See Also:

Attachments
Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description Max Rydahl Andersen CLA 2002-12-29 12:07:21 EST 
Just came to think of this "common beginner" codeing error which would be nice 
to have an warning/error for.




Example (derived from real wildlife code):




abstract class Base {


   ...


 


   doSomething(Base b) {


      SubBase x = (SubBase)b;  <= NOT GOOD! Needs a warning/error!


      <do something with x>


   }


}




class SubBase extends Base {




}




It is totally legit code, but people doing it should be informed about their 
"ignorance" :)
Comment 1 Dirk Baeumer CLA 2002-12-31 10:05:52 EST 
No clear if this should be covered by a compiler or by some sort of code 
convention checking tool. Moving to core for commenting (IMO this shouldn't be 
covered by the compiler).
Comment 2 Philipe Mulet CLA 2003-01-08 05:57:29 EST 
I am not a big fan either of having this one reported by the compiler (even 
optionally). 

May reconsider post 2.1 if more votes are added.
Comment 3 Max Rydahl Andersen CLA 2003-01-08 06:27:24 EST 
Ok :)




(but just curious - what is the difference between this warning and e.g. a 
warning against x = x; - isn't both just a BAD thing ?)
Comment 4 Philipe Mulet CLA 2003-10-30 04:43:44 EST 
Closing since support for unnecessary cast/instanceof got added a while ago in 
3.0 stream.
Comment 5 Denis Roy CLA 2009-08-30 02:19:28 EDT 
As of now 'LATER' and 'REMIND' resolutions are no longer supported.
Please reopen this bug if it is still valid for you.