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[CLJ-1335] PersistentList$EmptyList and empty LazySeq still returns old value for hasheq Created: 30/Jan/14  Updated: 14/Feb/14  Resolved: 14/Feb/14

Status: Closed
Project: Clojure
Component/s: None
Affects Version/s: Release 1.6
Fix Version/s: Release 1.6

Type: Defect Priority: Blocker
Reporter: Andy Fingerhut Assignee: Unassigned
Resolution: Completed Votes: 0
Labels: None

Attachments: File clj-1335-v1.diff     Text File clj-1335-v2.patch    
Patch: Code and Test
Approval: Ok


After late Jan 2014 changes to hash functions, PersistentList$EmptyList and (lazy-seq) were left behind:

user=> (= '() (lazy-seq) [])
user=> (map hash ['() (lazy-seq) []])
(1 1 -2017569654)
user=> (map class ['() (lazy-seq) []])
(clojure.lang.PersistentList$EmptyList clojure.lang.LazySeq clojure.lang.PersistentVector)

PersistentQueue/EMPTY was updated, so should not need any change.

Solution: Update LazySeq.hasheq() and make EmptyList implement IHashEq. EmptyList now creates a static constant for the hash value of an empty ordered collection and returns the constant for hasheq. An alternative would be to have Murmur3 have this constant instead.

Patch: clj-1335-v2.patch
Depends on: CLJ-1338, CLJ-1339, CLJ-1331 (must be applied first)


Comment by Andy Fingerhut [ 30/Jan/14 6:33 PM ]

Patch clj-1335-v1.diff adds tests that assume the patch clj-1331-v1.diff on ticket CLJ-1331 have already been committed. If it is desired to combine these into one patch, or commit this one without that one, I can eliminate that dependency.

Makes PersistentList$EmptyList implement IHashEq interface with a straightforward implementation of hasheq(), comments out empty LazySeq special case check that caused it to return old hash value, and fixes a NullPointerException for primitive vectors discovered by the new tests added.

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