ClassNotFoundException: scala.Function1$mcLL$sp - scala

Question

Hope someone can help me :)
I'm playing around with Rowz which I'm busy changing to use the newest Scala and Sbt (to help me evaluate Rowz in my environment and also just as a learning exercise). Now I'm getting the following error which I'm struggling to resolve:
Starting rowz (it's kinda quiet at the moment)
Exception in thread "main" java.lang.NoClassDefFoundError: scala/Function1$mcLL$sp
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:787)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:447)
at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
at Evaluator__92455c9cf893b1375b64dc2cae2905dd9718fe77_409351476$$anon$2$$anon$11.<init>((inline):48)
at Evaluator__92455c9cf893b1375b64dc2cae2905dd9718fe77_409351476$$anon$2.<init>((inline):48)
at Evaluator__92455c9cf893b1375b64dc2cae2905dd9718fe77_409351476.apply((inline):38)
at Evaluator__92455c9cf893b1375b64dc2cae2905dd9718fe77_409351476.apply((inline):1)
at com.twitter.util.Eval.applyProcessed(Eval.scala:197)
at com.twitter.util.Eval.applyProcessed(Eval.scala:189)
at com.twitter.util.Eval.apply(Eval.scala:135)
at com.twitter.util.Eval.apply(Eval.scala:169)
at com.twitter.rowz.Main$.main(Main.scala:16)
at com.twitter.rowz.Main.main(Main.scala)
Caused by: java.lang.ClassNotFoundException: scala.Function1$mcLL$sp
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
... 22 more
Any ideas?
I'm using the latest Scala (currently 2.10.1) and Sbt (currently 0.12.3)
The stacktrace mentions Twitter's util-eval project. I have the latest version. In my Sbt file:
libraryDependencies += "com.twitter" %% "util-eval" % "[6.2.4,)"
And this then retrieves:
/lib_managed/jars/com.twitter/util-core_2.10/util-core_2.10-6.3.0.jar
/lib_managed/jars/com.twitter/util-eval_2.10/util-eval_2.10-6.3.0.jar
/lib_managed/jars/org.scala-lang/scala-reflect/scala-reflect-2.10.1.jar
The file in question: Eval class on Twitter's github
As the latter is subject to change the code in question is as follows with the error occurring on the last line:
**
* same as apply[T], but does not run preprocessors.
*/
def applyProcessed[T](className: String, code: String, resetState: Boolean): T = {
val cls = compiler(wrapCodeInClass(className, code), className, resetState)
cls.getConstructor().newInstance().asInstanceOf[() => Any].apply().asInstanceOf[T]
}
Any insights appreciated.

Answer 1

Grepping the scala-library jar, it seems that Function1$mcLL$sp existed in 2.8.2, and disappeared 2.9.x.
It is an internal class representing Function1 with the apply method specialized for long.
More importantly, this means you have some code that was compiled against 2.8.x in your dependencies.
You should go through all your dependencies and make sure they all target 2.10.x.

Answer 2

Do not use specialization. It's broken. I have seen these kind of errors repeatedly, after I already published libraries that were successfully compiled with specialization (which is enabled by default).
Until specialization is thoroughly fixed, I recommend to compile all projects with
-no-specialization