Demonstrating a bug in json4s Reflector (or possibly just in Scala reflection) that produces a spurious IncompatibleClassChangeError when faced with locally declared case classes

reflectorbug.scala

import org.json4s._
import org.json4s.Extraction._
import org.scalatest.{Matchers, FlatSpec}
import org.json4s.native.Serialization
import org.json4s.native.Serialization._

/**
 * @version $Id$ $Rev$ $Date$
 */
class MyClass(v: String) {
  def myV = v
}

class MySerializer extends Serializer[MyClass] {
  def serialize(implicit format: Formats): PartialFunction[Any, JValue] = {
    case m: MyClass => decompose(m.myV)
  }

  /** Deserialization not supported */
  def deserialize(implicit format: Formats) = PartialFunction.empty
}

class MySerializerSpec extends FlatSpec with Matchers {

  implicit val formats = Serialization.formats(NoTypeHints) + new MySerializer

  "MySerializer" should "serialize case classes with MyClass values" in {
    case class Foo(bar: MyClass)

    val foo = Foo(new MyClass("baz"))

    val actual: String = write(foo)
    val expected: String = "{\"bar\":\"baz\"}"
    actual should be(expected)
  }
}