Saturday, December 10, 2011

clj-json breaks when running 'lein javac'

I'm working on a potential patch to Mark McGranaghan's excellent clj-json library for converting Clojure data to JSON. Unfortunately, I can't test my changes right now, because of an incompatibility between Leiningen version 1.6.2 and clj-json version 0.4.3, which causes lein javac to throw an exception.

It looks like clj-json has a dev dependency on an old version of a lein-javac plugin for Leiningen, which itself depends on ant-launcher version 1.6.5. It also looks like modern lein is smart enough to use its built-in javac task in preference to the old plugin, but it gets tripped up on the old version of ant-launcher.jar. The specific exception is:
Exception in thread "main" java.lang.NoSuchMethodError: \;)\
Ljava/lang/String; (NO_SOURCE_FILE:0)

I've submitted an issue on the clj-json project, but for now a simple workaround is to delete the dev dependency from clj-json's project.clj file, remove everything from its lib/ directory, and run lein deps to refresh dependencies.

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