Possible scala compiler bug

broken.scala

/*
 * If I remove the definition of unused (or make it private[this]),
 * then it fails to compile with:
 *
 *     $ ./bin/scala -version
 *     Scala code runner version 2.9.2 -- Copyright 2002-2011, LAMP/EPFL
 *
 *     $ ./bin/scala ~/broken.scala
 *     /Users/jhoyt/broken.scala:18: error: not found: value i
 *       val x = (f: Foo, i: Int) => f.copy(x = i)
 *                                              ^
 *     one error found
 */

object Broken {
  case class Foo(x: Int)

  private val unused = Foo(1).copy(x = 2)

  val x = (f: Foo, i: Int) => f.copy(x = i)
}