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[CLJ-1093] Empty PersistentCollections get incorrectly evaluated as their generic clojure counterpart Created: 24/Oct/12  Updated: 18/Apr/14

Status: Reopened
Project: Clojure
Component/s: None
Affects Version/s: Release 1.4, Release 1.5
Fix Version/s: Release 1.7

Type: Defect Priority: Minor
Reporter: Nicola Mometto Assignee: Timothy Baldridge
Resolution: Unresolved Votes: 2
Labels: None

Attachments: Text File 0001-CLJ-1093-fix-empty-records-literal-v2.patch     Text File clj-1093-fix-empty-record-literal-patch-v2.txt    
Patch: Code and Test
Approval: Vetted

 Description   
user> (defrecord x [])
user.x
user> #user.x[]
{}
user> #user.x{}
{}
user> #clojure.lang.PersistentTreeMap[]
{}
user> (class *1)
clojure.lang.PersistentArrayMap

Cause: Compiler's ConstantExpr parser returns an EmptyExpr for all empty persistent collections, even if they are of types other than the core collections (for example: records, sorted collections, custom collections). EmptyExpr reports its java class as one the classes - IPersistentList/IPersistentVector/IPersistentMap/IPersistentSet rather than the original type.

Proposed: If one of the Persistent* classes, then create EmptyExpr as before, otherwise retain the ConstantExpression of the original collection.

Patch: 0001-CLJ-1093-fix-empty-records-literal-v2.patch

Screened by:



 Comments   
Comment by Timothy Baldridge [ 27/Nov/12 11:41 AM ]

Unable to reproduce this bug on latest version of master. Most likely fixed by some of the recent changes to data literal readers.

Marking Not-Approved.

Comment by Timothy Baldridge [ 27/Nov/12 11:41 AM ]

Could not reproduce in master.

Comment by Nicola Mometto [ 01/Mar/13 1:23 PM ]

I just checked, and the problem still exists for records with no arguments:

Clojure 1.6.0-master-SNAPSHOT
user=> (defrecord a [])
user.a
user=> #user.a[]
{}

Admittedly it's an edge case and I see little usage for no-arguments records, but I think it should be addressed aswell since the current behaviour is not what one would expect

Comment by Herwig Hochleitner [ 02/Mar/13 8:14 AM ]

Got the following REPL interaction:

% java -jar ~/.m2/repository/org/clojure/clojure/1.5.0/clojure-1.5.0.jar
user=> (defrecord a [])
user.a
user=> (a.)
#user.a{}
user=> #user.a{}
{}
#user.a[]
{}

This should be reopened or declined for another reason than reproducability.

Comment by Nicola Mometto [ 10/Mar/13 2:18 PM ]

I'm reopening this since the bug is still there.

Comment by Andy Fingerhut [ 13/Mar/13 2:04 PM ]

Patch clj-1093-fix-empty-record-literal-patch-v2.txt dated Mar 13, 2013 is identical to Bronsa's patch 001-fix-empty-record-literal.patch dated Oct 24, 2012, except that it applies cleanly to latest master. I'm not sure why the older patch doesn't but git doesn't like something about it.

Comment by Nicola Mometto [ 26/Jun/13 8:06 PM ]

Patch 0001-CLJ-1093-fix-empty-records-literal-v2.patch solves more issues than the previous patch that was not evident to me at the time.

Only collections that are either PersistentList or PersistentVector or PersistentHash[Map|Set] or PersistentArrayMap can now be EmptyExpr.
This is because we don't want every IPersistentCollection to be emitted as a generic one eg.

user=> (class #clojure.lang.PersistentTreeMap[])
clojure.lang.PersistentArrayMap

Incidentally, this patch also solves CLJ-1187
This patch should be preferred over the one on CLJ-1187 since it's more general

Comment by Jozef Wagner [ 09/Aug/13 2:08 AM ]

Maybe this is related:

user=> (def x `(quote ~(list 1 (clojure.lang.PersistentTreeMap/create (seq [1 2 3 4])))))
#'user/x
user=> x
(quote (1 {1 2, 3 4}))
user=> (class (second (second x)))
clojure.lang.PersistentTreeMap
user=> (eval x)
(1 {1 2, 3 4})
user=> (class (second (eval x)))
clojure.lang.PersistentArrayMap

Even if the collection is not evaluated, it is still converted to the generic clojure counterpart.

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