Clojure Q&A - Recent questions tagged asm

Why does Clojure generate too many .class files?

Sun, 04 Sep 2022 21:27:27 +0000

It turns out Clojure creates a class file per function. As a result, you get too many .class files.

My question is, why does it generate that many .class files instead of creating a class per namespace and having all functions inside that .class file?

At least for AOT compilation, that'd be great merging those .class files? I'd like to know the technical reason behind it.

ArrayIndexOutOfBoundsException in clojure.asm.Frame

Tue, 08 Feb 2022 13:37:27 +0000

Hey all :)

Have hit what I think is a compiler bug this morning, wondering whether it's one I should submit to JIRA?

Here's what I believe to be a minimal repro:

(defprotocol P
  (^double p1 [p a])
  (^double p2 [p a]))

(let [p (reify P)]
  (min 0.0
       (case :p1
         :p1 (p1 p :foo)
         :p2 (p2 p :foo))))

Error:

1. Caused by java.lang.ArrayIndexOutOfBoundsException
   Index -1 out of bounds for length 0

                Frame.java: 1262  clojure.asm.Frame/merge
                Frame.java: 1238  clojure.asm.Frame/merge
         MethodWriter.java: 1604  clojure.asm.MethodWriter/computeAllFrames
         MethodWriter.java: 1540  clojure.asm.MethodWriter/visitMaxs

... (have a fuller trace I can send, or the above code snippet should work at a REPL)

Any of the following make this error go away

removing the type hinting
adding a nil default to the case
making the protocol functions normal type-hinted defns
raising the case out of the min (removing the min)

I've managed to refactor the original code to work around the issue, but please do let me know if I should raise a JIRA ticket.

Cheers,

James

Recommended workflow to work on Clojure sources

Tue, 26 Oct 2021 02:14:01 +0000

Hello all,

Is there a recommended way to work on the Clojure sources, both the java and the clj files?

For example, I'd like to be able to put a breakpoint in my ide (Intellij Idea) to see how certain parts of the compiler or the core libraries work.

Thanks

"file does not contain class clojure.asm.Symbol" warning when clojure-sources is in the classpath

Mon, 28 Dec 2020 16:40:24 +0000

I have .m2/repository/org/clojure/clojure/1.10.1/clojure-1.10.1-sources.jar in the classpath, which I do in order to enable (custom) IDE tooling.

Doing so causes the following warning when launching lein repl:

/Users/vemv/.m2/repository/org/clojure/clojure/1.10.1/clojure-1.10.1-sources.jar(clojure/asm/SymbolTable.java):49: error: cannot access Symbol
  private static class Entry extends Symbol {
                                     ^
  bad source file: /Users/vemv/.m2/repository/org/clojure/clojure/1.10.1/clojure-1.10.1-sources.jar(clojure/asm/Symbol.java)
    file does not contain class clojure.asm.Symbol
    Please remove or make sure it appears in the correct subdirectory of the sourcepath.

In contrast, no other "sources" .jar causes any warning. I can have up to hundreds of such "sources" jars.

Perhaps this file has some minor/vestigial issue, such as something related to privacy modifiers, package structure, etc?

If it was harmless to do, this would seem nice to fix particularly when a single class in a single lib is the only instance of this issue (vs. hundreds of other .jars)

As a reference, I also found another person encountering the same issue: https://clojurians-log.clojureverse.org/clojure/2019-06-23/1561323947.040200

By the way, while this might look as a javac byproduct, I'm almost positively sure lein repl is not implicitly invoking javac. Documentation states so: https://github.com/technomancy/leiningen/blob/0f456829a8b21335aa86390f3ee3d0dcc68410d6/doc/MIXED_PROJECTS.md#java-source-compilation

I'm using JDK8.