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[CLJ-1093] Empty PersistentCollections get incorrectly evaluated as their generic clojure counterpart Created: 24/Oct/12  Updated: 06/Oct/14

Status: Reopened
Project: Clojure
Component/s: None
Affects Version/s: Release 1.4, Release 1.5
Fix Version/s: Release 1.8

Type: Defect Priority: Major
Reporter: Nicola Mometto Assignee: Unassigned
Resolution: Unresolved Votes: 5
Labels: collections, compiler

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

user> (defrecord x [])
user> #user.x[]   ;; expect: #user.x{}
user> #user.x{}   ;; expect: #user.x{}
user> #clojure.lang.PersistentTreeMap[]
user> (class *1)  ;; expect: clojure.lang.PersistentTreeMap

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.
Since EmptyExpr is a compiler optimization that applies only to some concrete clojure collections, making EmptyExpr dispatch on concrete types rather than on generic interfaces makes the compiler behave as expected

Patch: 0001-CLJ-1093-v2.patch

Screened by:

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=> #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=> #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[])

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
(quote (1 {1 2, 3 4}))
user=> (class (second (second x)))
user=> (eval x)
(1 {1 2, 3 4})
user=> (class (second (eval x)))

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

Comment by Alex Miller [ 24/Apr/14 4:44 PM ]

In the change for ObjectExpr.emitValue() where you've added PersistentArrayMap to the PersistentHashMap case, should the IPersistentVector case below that be PersistentVector instead, otherwise it would snare a custom IPersistentVector that's not a PersistentVector, right?

This line: "else if(form instanceof ISeq)" at the end of the Compiler diff has different leading tabs which makes the diff slightly more confusing than it could be.

Would be nice to add a test for the sorted map case in the description.

Marking incomplete to address some of these.

Comment by Alex Miller [ 13/May/14 10:43 PM ]


Comment by Nicola Mometto [ 14/May/14 4:24 AM ]

Attached patch 0001-CLJ-1093-fix-empty-collection-literal-evaluation.patch which implements your suggestions.

replacing IPersistentVector with PersistentVector in ObjectExpr.emitValue() exposes a print-dup limitation: it expects every IPersistentCollection to have a static "create" method.

This required special casing for MapEntry and APersistentVector$SubVector

Comment by Nicola Mometto [ 16/May/14 3:57 PM ]

I updated the patch adding print-dups for APersistentVector$SubVec and other IPersistentVectors rather than special casing them in the compiler

Comment by Alex Miller [ 23/May/14 4:21 PM ]

All of the checks on concrete classes in the Compiler parts of this patch don't sit well with me. I understand how you got to this point and I don't have an alternate recommendation (yet) but all of that just feels like the wrong direction.

We want to be built on abstractions such that internal collections are not special; they should conform to the same expectations as an external collection and both should follow the same paths in the compiler - needing to check for those types is a flag for me that something is amiss.

I am marking Incomplete for now based on these thoughts.

Comment by Nicola Mometto [ 06/Jul/14 10:01 AM ]

I've been thinking for a while about this issue and I've come to the conclusion that in my later patches I've been trying to incorporate fixes for 3 different albeit related issues:

1- Clojure transforms all empty IPersistentCollections in their generic Clojure counterpart

user> (defrecord x [])
user> #user.x[]   ;; expected: #user.x{}
user> #user.x{}   ;; expected: #user.x{}
user> #clojure.lang.PersistentTreeMap[]
user> (class *1)  ;; expected: clojure.lang.PersistentTreeMap

2- Clojure transforms all the literals of collections implementing the Clojure interfaces (IPersistentList, IPersistentVector ..) that are NOT defined with deftype or defrecord, to their
generic Clojure counterpart

user=> (class (eval (sorted-map 1 1)))
clojure.lang.PersistentArrayMap ;; expected: clojure.lang.PersistentTreeMap

3- print-dup is broken for some Clojure persistent collections

user=> (print-dup (subvec [1] 0) *out*)
#=(clojure.lang.APersistentVector$SubVector/create [1])
user=> #=(clojure.lang.APersistentVector$SubVector/create [1])
IllegalArgumentException No matching method found: create  clojure.lang.Reflector.invokeMatchingMethod (Reflector.java:53)

I'll keep this ticket regarding issue #1 and open two other tickets for issue #2 and #3

Comment by Nicola Mometto [ 06/Jul/14 10:15 AM ]

I've attached a new patch fixing only this issue, the approach is explained in the description

Comment by Nicola Mometto [ 12/Sep/14 5:45 PM ]

0001-CLJ-1093-v2.patch is an updated patch that correctly handles metadata evaluation semantics on empty literals and adds some tests for it

[CLJ-1172] Cross-linking between clojure.lang.Compiler and clojure.lang.RT Created: 28/Feb/13  Updated: 21/Jun/13

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

Type: Defect Priority: Minor
Reporter: Yegor Bugayenko Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: None

version 1.5.0-RC17


This is my code (an example):

import clojure.lang.Compiler;
import clojure.lang.RT;
import clojure.lang.Var;

Compiler.load("(+ 5 %)");
Var foo = RT.var("bar", "foo");
Object result = foo.invoke(10);
assert result.toString().equals("15");

This is what I'm getting:

	at clojure.lang.Compiler.<clinit>(Compiler.java:47)
	at foo.main(Main.java:75)
Caused by: java.lang.NullPointerException
	at clojure.lang.RT.baseLoader(RT.java:2043)
	at clojure.lang.RT.load(RT.java:417)
	at clojure.lang.RT.load(RT.java:411)
	at clojure.lang.RT.doInit(RT.java:447)
	at clojure.lang.RT.<clinit>(RT.java:329)
	... 36 more

The same code worked just fine with version 1.4. Looks like Compiler is using RT and RT is using Compiler, both statically.

Comment by Yegor Bugayenko [ 04/Mar/13 11:40 AM ]

I cross-posted this question to SO: http://stackoverflow.com/questions/15207596

Comment by Yegor Bugayenko [ 05/Mar/13 12:04 AM ]

calling RT.init() before Compiler.load() solves the problem

Comment by Andy Fingerhut [ 05/Mar/13 4:17 AM ]

Yegor, do you consider it OK to close this ticket as not being a problem, or at least one with a reasonable workaround?

Comment by Yegor Bugayenko [ 05/Mar/13 1:11 PM ]

Yes, of course. Let's close it.

Comment by Andy Fingerhut [ 05/Mar/13 6:14 PM ]

Ticket submitter agrees that this is not an issue, or that there is a reasonable workaround.

Comment by Andy Fingerhut [ 13/Mar/13 12:58 AM ]

This issue came up again on the Clojure group. https://groups.google.com/forum/?hl=en_US&fromgroups=#!topic/clojure/2xdLNMb9yyQ

I did some testing, and the issue did not exist in Clojure 1.5.0-RC3 and before, and it has existed since 1.5.0-RC4. There was only one commit between those two points:


Maybe this new behavior is an intended consequence of that change. I don't know. In any case, it seems like perhaps the "No need to call RT.init() anymore" message might be outdated?

Comment by Andy Fingerhut [ 13/Mar/13 12:59 AM ]

Reopening since it came up again, and there is some more info known about the issue. I'll let someone who knows more about the issue decide whether to close it.

Comment by Edward [ 23/Mar/13 10:31 AM ]

Doing this RT.load("clojure/core"); at the top works avoids the message from RT.init()

Comment by Jean Niklas L'orange [ 21/Jun/13 10:36 AM ]

It seems like RT.load("clojure/core") does not hide the message anymore - at least not from 1.5.1.

[CLJ-1401] CompilerException / IllegalStateException when reloading namespaces Created: 10/Apr/14  Updated: 12/Apr/14

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

Type: Defect Priority: Minor
Reporter: Mike Anderson Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: compiler, errormsgs

user> (ns op)
op> (defn * [a b] (clojure.core/* a b))
WARNING: * already refers to: #'clojure.core/* in namespace: op, being replaced by: #'op/*
op> (ns use-op (:require [op :refer :all]))
WARNING: * already refers to: #'clojure.core/* in namespace: use-op, being replaced by: #'op/*
use-op> (ns use-op (:require [op :refer :all]))
IllegalStateException * already refers to: #'op/* in namespace: use-op  clojure.lang.Namespace.warnOrFailOnReplace (Namespace.java:88)
use-op> (clojure.repl/pst *e)
IllegalStateException * already refers to: #'op/* in namespace: use-op
	clojure.lang.Namespace.warnOrFailOnReplace (Namespace.java:88)
	clojure.lang.Namespace.reference (Namespace.java:110)
	clojure.lang.Namespace.refer (Namespace.java:168)
	clojure.core/refer (core.clj:3920)
	use-op/eval2402/loading--4958--auto----2403 (NO_SOURCE_FILE:1)
	use-op/eval2402 (NO_SOURCE_FILE:1)
	clojure.lang.Compiler.eval (Compiler.java:6703)
	clojure.lang.Compiler.eval (Compiler.java:6692)
	clojure.lang.Compiler.eval (Compiler.java:6666)
	clojure.core/eval (core.clj:2927)
	clojure.main/repl/read-eval-print--6625/fn--6628 (main.clj:239)
	clojure.main/repl/read-eval-print--6625 (main.clj:239)

I would expect (at worst) a similar warning to the initial namespace loading, rather than an exception here.

Comment by Alex Miller [ 11/Apr/14 8:26 AM ]

Could you put together a better reproducible test case for this that does not depend on core.matrix? Also, please include the (pst *e) when it occurs.

Comment by Andy Fingerhut [ 11/Apr/14 10:19 AM ]

I have tried the smallest possible Leiningen project I could think of that would cause the warnings about redefinitions, to see if I could get the exception to occur. 'lein new try1' to create the skeleton project, then edit src/try1/core.clj to contain only the following function definitions:

(defn merge
  "This definition of merge replaces clojure.core/merge"
  [x y]
  (- x y))

(defn *
  [x y]
  (* x y))

Then start a REPL with 'lein repl', and I see this behavior:

user=> (require '[try1.core :as c])
WARNING: merge already refers to: #'clojure.core/merge in namespace: try1.core, being replaced by: #'try1.core/merge
WARNING: * already refers to: #'clojure.core/* in namespace: try1.core, being replaced by: #'try1.core/*
user=> (require '[try1.core :as c] )
user=> (require '[try1.core :as c] :reload)
WARNING: merge already refers to: #'clojure.core/merge in namespace: try1.core, being replaced by: #'try1.core/merge
WARNING: * already refers to: #'clojure.core/* in namespace: try1.core, being replaced by: #'try1.core/*

Ths all looks like behavior as I would expect, and I did not see the exception that Mike reports.

It seems that either Ctrl+Alt+L in Counterclockwise does something different than (require ... :reload), or there is something different about Mike's namespace in addition to redefining names in clojure.core that is causing the problem.

Comment by Alex Miller [ 11/Apr/14 11:17 AM ]

Marking this as NR for now - would be happy to see it reopened with an easily reproducible test case.

Comment by Mike Anderson [ 12/Apr/14 12:41 AM ]

To reproduce:

(ns op)
(defn * [a b] (clojure.core/* a b)) ;; gives warning
(ns use-op (:require [op :refer :all])) ;; gives warning
(ns use-op (:require [op :refer :all])) ;; gives error!

I believe Counterclockwise is simply loading the namespace again with CTRL-Alt+L, which is causing the ns form to be re-executed.

The docstring implies that ns can be used multiple times ("Sets ns to the namespace named by name (unevaluated), creating it if needed") so I would certainly expect multiple invocations of ns to be a no-op

[CLJ-1368] Document usage for case with non-readable constants Created: 02/Mar/14  Updated: 02/Mar/14

Status: Reopened
Project: Clojure
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Enhancement Priority: Minor
Reporter: Herwig Hochleitner Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: docs, interop



It is pretty obscure how to get constant-time dispatch for e.g. Enums, even if user knows about case.


The possibility to dispatch to arbitrary constants with case, by wrapper macro, should be documented.


  • Should it warn against doing that with unstable values?
  • Should it mention anything else than java Enums?

Case Techniques

Case is documented for accepting all readable forms as test-constants. However, it can also be made to use any compile-time-known constants as test-constants, by wrapping it in another macro.

Sometimes this is appropriate, e.g. when dispatching on a java Enum.
Other times, less so, e.g. when dispatching on objects whose hash changes when the vm is restarted (breaks AOT).


This technique is an application of a more general technique: Passing non-literals to a macro from another macro.
Are there other macros that have use cases like this?



Comment by Herwig Hochleitner [ 02/Mar/14 11:25 AM ]

This is a duplicate of http://dev.clojure.org/jira/browse/CLJ-1367

Actually, it's an alternate solution

[CLJ-1099] better error message when passing non-seq to seq Created: 01/Nov/12  Updated: 09/Apr/14

Status: Reopened
Project: Clojure
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Enhancement Priority: Minor
Reporter: Stuart Halloway Assignee: Unassigned
Resolution: Unresolved Votes: 1
Labels: None

Attachments: Text File better-error-message-for-seq.patch    
Patch: Code
Approval: Vetted


Design discussion here.

This patch improves Clojure's error message for a single common error: passing a non-seq where a seq is neede. More importantly, it is intended as a prototype for other similar improvements in the future.

Error message before:

(cons 1 2)
=> IllegalArgumentException Don't know how to create ISeq from: java.lang.Long

Error message after:

user=> (cons 1 2)
ExceptionInfo Don't know how to create ISeq from: java.lang.Long
user=> (ex-data *e)
{:instance 2}

Patch: better-error-message-for-seq.patch
NOTE: This patch was reverted as it affected the inlining of RT.seqFrom().

Comment by Michael Klishin [ 12/Nov/12 10:34 AM ]

Wouldn't it be better to make it read "Don't know how to create ISeq from: 2 (java.lang.Long)"? How many beginners will figure
out ex-data exists and how to use it?

Comment by Stuart Halloway [ 12/Apr/13 11:36 AM ]

Hi Michael,

ex-info messages should not, in general, pr-str things into their bodies. This raises the question of print-length and print-level in a place where the user doesn't have good control, while the whole point of ex-info is to be in the data business, not the string business. Users can control printing from ex-data any way they like.

There are two possible ways to make beginners aware of ex-data: Tell them about it in one (or a few places) in docs, or in an infinite number of places saying "This would have been useful here, but we didn't use it because you might not know about it." I prefer the former.

That said, I think it would be great to increase the visibility of ex-info and ex-data early on in documentation for beginners, and to make sure that things like exception printing in logs are flexible enough not to lose the benefits of ex-info.

Comment by Andy Fingerhut [ 25/Mar/14 5:14 PM ]

Just a comment that this fix was committed before release 1.6.0, and then reverted very shortly before release 1.6.0. I believe the reason for reverting was due to concerns that this change made performance about 5% slower in some relatively common cases, with a suspicion that it could have affected inlining of the seqFrom method.

Not sure whether the ticket should be reopened or not.

[CLJ-1161] sources jar has bad versions.properties resource Created: 11/Feb/13  Updated: 06/Oct/14

Status: Reopened
Project: Clojure
Component/s: None
Affects Version/s: Release 1.4, Release 1.5
Fix Version/s: Release 1.8

Type: Defect Priority: Minor
Reporter: Steve Miner Assignee: Stuart Halloway
Resolution: Unresolved Votes: 0
Labels: None

Attachments: Text File 0001-CLJ-1161-Remove-version.properties-from-sources-JAR.patch    
Patch: Code
Approval: Incomplete


The "sources" jar (at least since Clojure 1.4 and including 1.5 RC) has a bad version.properties file in it. The resource clojure/version.properties is literally:


The regular Clojure jar has the correct version string in that resource.

I came across a problem when I was experimenting with the sources jar (as used by IDEs). I naively added the sources jar to my classpath, and Clojure died on start up. The bad clojure/versions.properties file was found first, which led to a parse error as the clojure version was being set.

Solution: patch leaves version.properties file out of sources JAR, where it causes problems for tools.

Comment by Steve Miner [ 11/Feb/13 10:04 AM ]

Notes from the dev mailing list:

The "sources" JAR is generated by another Maven plugin, configured here:

The simplest solution might be to just exclude the file from the sources jar. It looks like maven-source-plugin has an excludes option which would do the trick:


Comment by Jeff Valk [ 21/Apr/14 8:20 AM ]

This issue is marked closed, but I'm still seeing it: the clojure-1.6.0-sources.jar, clojure-1.5.1-sources.jar, etc on Maven Central still contain the bad version.properties files. More specifically, it looks like the fix has been applied to builds in the SNAPSHOTS repository, but not to RELEASES.

Fix applied: https://oss.sonatype.org/content/repositories/snapshots/org/clojure/clojure/
Not fixed: https://oss.sonatype.org/content/repositories/releases/org/clojure/clojure/

Comment by Alex Miller [ 24/Apr/14 4:15 PM ]

Not sure what's needed here, but marking incomplete.

Comment by Jeff Valk [ 25/Apr/14 11:13 AM ]

Would a fix for this update existing sources jars (1.5.1, 1.6.0, etc) on Central? Or would any fix have to wait on the next Clojure release?

Comment by Alex Miller [ 25/Apr/14 12:37 PM ]

For all the same reasons that mutable state is undesirable, changing an existing release jar in the central Maven repository is also undesirable. While it's not technically impossible, we will not update existing releases and this will need to wait for the next. I've looked at this problem a little and I do not yet know enough to know how to fix it or why it even varies between snapshot and release. Help welcome!

In which tool do you see a resulting problem from this?

Comment by Jeff Valk [ 25/Apr/14 11:56 PM ]

Despite the way I phrased the question, I'd hoped that would be the answer. It's the right policy.

Unfortunately, this issue leaves the released sources jars essentially unusable from a tools standpoint. CIDER now has source code navigation from stacktraces – you can jump into both Clojure and Java function definitions from the error/trace. For the latter, the sources jar (for Clojure or any other Java library) needs to be on the classpath as a dev dependency. There's more host interop support in the works for CIDER too ("embrace the host platform"), but not being able to add a dependency on a stable Clojure sources jar presents a wrinkle.

Are the official Clojure releases built by Hudson? The Hudson build right before the 1.6.0 release (#532) and the one right after (#534) both show the exclusion fix, as does the git clojure-1.6.0 tag, which when I check out and build from source, is fine. The Hudson builds with release tags (e.g. 1.6 = #533, 1.6-RC1 = #512, etc), though, don't show any artifacts other than a pom.xml. This would seem to make it rather hard to audit builds...am I missing something?

[CLJ-1371] divide(Object, Object) with (NaN, 0) does not return NaN Created: 07/Mar/14  Updated: 07/Mar/14

Status: Reopened
Project: Clojure
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Defect Priority: Trivial
Reporter: Yongqian Li Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: math


user=> (def x Double/NaN)
user=> (/ x 0)

ArithmeticException Divide by zero clojure.lang.Numbers.divide (Numbers.java:156)
user=> (/ Double/NaN 0)

Comment by Alex Miller [ 07/Mar/14 7:50 AM ]

As per the Java Language Specification (http://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.2.4),

"All numeric operations with NaN as an operand produce NaN as a result."

Comment by Yongqian Li [ 07/Mar/14 7:54 AM ]

But in the first example it produces an ArithmeticException.

Comment by Alex Miller [ 07/Mar/14 9:27 AM ]

Ah, I see the question now.

Here we are dividing a double by a long. In the first case, this is parsed as divide(Object, long) which then calls divide(Object, Object), which throws ArithmeticException if the second arg is 0 (regardless of the first arg).

In the second case it's parsed as divide(double, long) which just relies on Java to properly upcast the primitive long to a double to do the divide.

Note that making this call with 2 doubles does return NaN:

user=> (def x Double/NaN)
user=> (/ x 0.0)

or type hinting x to a double works as well:

user=> (def x Double/NaN)
user=> (/ ^double x 0.0)

I think one option to "fix" this behavior would be to add checks in divide(Object, Object) to check whether x is NaN and instead return NaN.

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