Non-terminating compilation in Java(gist.github.com)

  trait Pong[T] {}

  class Ping[T] extends Pong[Pong[X forSome { type X >: Ping[Ping[T]]}]] {
    def Ping() {
      val Ping : Pong[X forSome { type X >: Ping[Long]}] = new Ping[Long]();
    }
  }

  Test.scala:3: error: illegal cyclic reference involving class Ping
  class Ping[T] extends Pong[Pong[X forSome { type X >: Ping[Ping[T]]}]] {
                                                   ^
  Test.scala:5: error: type mismatch;
   found   : Ping[Long]
   required: Pong[X forSome { type X >: Ping[Long] }]
  Note: Long <: X forSome { type X >: Ping[Long] }, but trait Pong is invariant in type T.
  You may wish to define T as +T instead. (SLS 4.5)
      val Ping : Pong[X forSome { type X >: Ping[Long]}] = new Ping[Long]();

    (defmacro get-stuck (x) 
        (labels ((infinite () (infinite))) 
            (infinite) x))
    (get-stuck 3)

  class compilehang {
    public static void main(String[] args) {
      double d = 2.2250738585072012e-308;
      System.out.println("Value: " + d);
    }
  }