Demonstrate an incompatibility with clojure.java.classpath

[vemv]

Hi,

in a project of mine I found out that the presence of a recent cider-nrepl dependency would make c.j.classpath/classpath-directories return an empty seq.

Were you aware of that?

[vemv]

Repro'd successfully in JDK11 as expected. Let me know what you think.

Thanks!

[vemv]

As a workaround, consumers can invoke (classpath/system-classpath) and extract directories out of it, instead of invoking (classpath-directories) directly.

The former appears to be independent of classloader intricacies.

[bbatsov]

Yeah, it just parses an env variable (and it's the only thing that works on Java 9+).

[dpsutton]

I am using core.logic and adding the java.classpath dep there. cider-jack-in and classpath-directories is working for me. Are there more repro steps? Perhaps one of the lazily loaded middleware need to be loaded?

;; Connected to nREPL server - nrepl://localhost:39715
;; CIDER 0.25.0snapshot, nREPL 0.6.0
;; Clojure 1.10.1, Java 11.0.6
;;     Docs: (doc function-name)
;;           (find-doc part-of-name)
;;   Source: (source function-name)
;;  Javadoc: (javadoc java-object-or-class)
;;     Exit: <C-c C-q>
;;  Results: Stored in vars *1, *2, *3, an exception in *e;
;;  Startup: /usr/local/bin/clojure -Sdeps '{:deps {nrepl {:mvn/version "0.6.0"} cider/cider-nrepl {:mvn/version "0.24.0"}}}' -m nrepl.cmdline --middleware '["cider.nrepl/cider-middleware"]'
user> (require '[clojure.java.classpath :as cp])
nil
user> (cp/classpath-directories)
(#object[java.io.File 0x336cc394 "src/main/clojure"]
 #object[java.io.File 0x15fd6b0f "src/test/clojure"])

and also with lein in that project:

;; Connected to nREPL server - nrepl://localhost:36745
;; CIDER 0.25.0snapshot, nREPL 0.6.0
;; Clojure 1.10.1, Java 11.0.6
;;     Docs: (doc function-name)
;;           (find-doc part-of-name)
;;   Source: (source function-name)
;;  Javadoc: (javadoc java-object-or-class)
;;     Exit: <C-c C-q>
;;  Results: Stored in vars *1, *2, *3, an exception in *e;
;;  Startup: /home/dan/bin/lein update-in :dependencies conj \[nrepl\ \"0.6.0\"\] -- update-in :plugins conj \[cider/cider-nrepl\ \"0.24.0\"\] -- repl :headless :host localhost
user> (require '[clojure.java.classpath :as cp])
nil
user> (cp/classpath-directories)
(#object[java.io.File 0x38a82b21 "/home/dan/projects/clojure/core.logic/src/test/clojure"]
 #object[java.io.File 0x6f1913c9 "/home/dan/projects/clojure/core.logic/src/main/clojure"]
 #object[java.io.File 0x1307d144 "/home/dan/projects/clojure/core.logic/resources"]
 #object[java.io.File 0x49501a70 "/home/dan/projects/clojure/core.logic/target/classes"])

[dpsutton]

user> 
(doseq [[name p] @cider.nrepl/delayed-handlers]
  @p
  (println name ": nil? : " (nil? (seq (cp/classpath-directories)))))
handle-resource : nil? :  false
handle-profile : nil? :  false
handle-inspect : nil? :  false
handle-info : nil? :  false
handle-xref : nil? :  false
handle-version : nil? :  false
handle-trace : nil? :  false
handle-tracker : nil? :  false
handle-slurp : nil? :  false
handle-test : nil? :  false
handle-spec : nil? :  false
handle-apropos : nil? :  false
handle-format : nil? :  false
handle-undef : nil? :  false
handle-complete : nil? :  false
handle-clojuredocs : nil? :  false
handle-classpath : nil? :  false
handle-out : nil? :  false
handle-stacktrace : nil? :  false
handle-refresh : nil? :  false
handle-debug : nil? :  false
handle-content-type : nil? :  false
handle-ns : nil? :  false
handle-enlighten : nil? :  false
handle-macroexpand : nil? :  false
nil
user> (cp/classpath-directories)
(#object[java.io.File 0x11fd2e25 "/home/dan/projects/clojure/core.logic/src/test/clojure"]
 #object[java.io.File 0x584546ff "/home/dan/projects/clojure/core.logic/src/main/clojure"]
 #object[java.io.File 0x22347656 "/home/dan/projects/clojure/core.logic/resources"]
 #object[java.io.File 0x11754050 "/home/dan/projects/clojure/core.logic/target/classes"])
user> 

[vemv]

I rebased this PR against master (for checking if the issue would still be present), although the results are useless right now because master is also red

[bbatsov]

Yeah, the breakage is described here #678

It's something to do with piggieback, but I didn't have time to debug it in details.

[vemv]

Now that the master branch is green, I rebased this PR again.

Again it fails for the intended reason.

This would be a good issue to solve. It has an important impact because arbitrary third-party tools (notably tools.namespace (refresh)) can break in face of this - not always in an easily debuggable manner.

For example yesterday someone reported that edge case on Clojurians (Corretto + JDK11 + Ubuntu)

[vemv]

I recreated this more precisely in the actual repo originating the issue clojure-emacs/orchard#112