IllegalAccessException on startup when using App, implicit function, anonymous function, and either multiple assignment or a nested block

[scabug]

I have a simple application:

object Test extends App {
  implicit def t2mapper[X, X0 <: X, X1 <: X](t: (X0, X1)) = new {
    def map[R](f: X => R) = (f(t._1), f(t._2))
  }
  println("Hello!")
  val (foo, bar) = (1, 2) map (_ * 2)
  println((foo, bar))
}

(The t2mapper is from Stack Overflow: [http://stackoverflow.com/a/4022510/319931].)

The code compiles fine:

$ scalac -version
Scala compiler version 2.9.1 -- Copyright 2002-2011, LAMP/EPFL
$ scalac -unchecked Test.scala
$ 

but when run, it throws an IllegalAccessError (before Hello! gets printed):

$ java -version
java version "1.6.0_24"
OpenJDK Runtime Environment (IcedTea6 1.11.1) (6b24-1.11.1-4ubuntu3)
OpenJDK Server VM (build 20.0-b12, mixed mode)
$ scala Test
java.lang.IllegalAccessError: tried to access field Test$.reflParams$Cache1 from class Test$delayedInit$body
        at Test$delayedInit$body.<clinit>(Test.scala:6)
        at Test$.<init>(Test.scala:1)
        at Test$.<clinit>(Test.scala)
        at Test.main(Test.scala)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:616)
        at scala.tools.nsc.util.ScalaClassLoader$$anonfun$run$1.apply(ScalaClassLoader.scala:78)
        at scala.tools.nsc.util.ScalaClassLoader$class.asContext(ScalaClassLoader.scala:24)
        at scala.tools.nsc.util.ScalaClassLoader$URLClassLoader.asContext(ScalaClassLoader.scala:88)
        at scala.tools.nsc.util.ScalaClassLoader$class.run(ScalaClassLoader.scala:78)
        at scala.tools.nsc.util.ScalaClassLoader$URLClassLoader.run(ScalaClassLoader.scala:101)
        at scala.tools.nsc.ObjectRunner$.run(ObjectRunner.scala:33)
        at scala.tools.nsc.ObjectRunner$.runAndCatch(ObjectRunner.scala:40)
        at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:56)
        at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:80)
        at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:89)
        at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)

Note that with the last two lines replaced with

{code}...
println((1, 2) map (_ * 2))
{code}

or

{code}...
val (foo, bar) = (2, 4)
println((foo, bar))
{code}

or

{code}...
val intermediate = (1, 2) map (_ * 2)
val (foo, bar) = intermediate
println((foo, bar))
{code}

it prints (2,4) as expected. But when wrapped in a block

{code}...
{
val intermediate = (1, 2) map (_ * 2)
val (foo, bar) = intermediate
println((foo, bar))
}
{code}

or

{code}...
private val blah = {
val intermediate = (1, 2) map (_ * 2)
val (foo, bar) = intermediate
println((foo, bar))
}
{code}

it throws the exception.

Related

I described the issue at [http://stackoverflow.com/questions/11302291/why-does-this-scala-code-throw-illegalaccesserror-at-runtime]; reported here too since it seemed to be a compiler bug.

Possibly related to [#SI-5251].

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-6019?orig=1
Reporter: Mechanical snail (mechanicalsnail)
Affected Versions: 2.9.1, 2.9.2
Duplicates #5565

[scabug]

@paulp said:
Duplicate of #5565. Workaround is to skip App and write a main method.