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[CLJ-702] case gives NPE when used with nil Created: 04/Jan/11  Updated: 25/Feb/11  Resolved: 25/Feb/11

Status: Closed
Project: Clojure
Component/s: None
Affects Version/s: Release 1.2
Fix Version/s: Release 1.3

Type: Defect Priority: Major
Reporter: Benjamin Teuber Assignee: Unassigned
Resolution: Completed Votes: 1
Labels: None

Attachments: GZip Archive 0702-fix-npe-in-nil-case-2.patch.gz     GZip Archive 0702-fix-npe-in-nil-case-3.patch.gz     Text File 0702-fix-npe-in-nil-case.patch    
Patch: Code and Test
Approval: Ok


This code gives a NullPointerException:

(case nil
nil "foo")

If fixing this is impossible for implementation reasons, at least the documentation and error messages should be improved.

Comment by Aaron Bedra [ 05/Jan/11 9:28 PM ]

What would be the desired fix look like for this? Should this be a documentation update or should this be updated to not produce an NPE?

Comment by a_strange_guy [ 06/Jan/11 4:23 PM ]

I think that the case macro should just generate a null check before calling hashcode on a value. The same way protocol functions automatically check for null before dispatching.

Comment by Rich Hickey [ 07/Jan/11 8:03 AM ]

First step in fixing a problem is to understand it. The exception is thrown during compilation and the stack trace points to c.l.Compiler$ObjExpression.constantType()

Comment by Aaron Bedra [ 07/Jan/11 9:31 AM ]

Thanks Rich. I will take this one and get a patch in hopefully today.

Comment by Aaron Bedra [ 07/Jan/11 2:17 PM ]

Rich, this seems to solve the issue demonstrated in this ticket. I don't have full context on all possible impact points here. Can you please take a look at this and let me know if I missed anything?

Comment by Rich Hickey [ 10/Jan/11 6:35 AM ]

looks ok at first glance

Comment by Stuart Sierra [ 21/Jan/11 1:44 PM ]

New patch 0702-fix-npe-in-nil-case-2.patch.gz adds a test.

Comment by Aaron Bedra [ 25/Jan/11 7:48 AM ]

Stuart, your patch replaces the original patch and the commit message doesn't reveal the intent of the fix. It also overwrites me as the original patch submitter.

Comment by Stuart Sierra [ 25/Jan/11 2:50 PM ]

Oops. Sorry. Will fix.

Comment by Stuart Halloway [ 28/Jan/11 10:23 AM ]

waiting on Stuart's patch tweak

Comment by Stuart Sierra [ 28/Jan/11 3:00 PM ]

Patch 0702-fix-npe-in-nil-case-3.patch.gz replaces previous patches, but preserves correct commit messages and authors.

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