open interface First {
  public open fun foo() : Int
}

open interface Second : First {
  public open fun bar() : Int
}

class Impl : Second {
  public override fun foo() = 1
  public override fun bar() = 2
}

class Test(s : Second) : Second by s {}

fun box() : String {
    var t = Test(Impl())
    if (t.foo() != 1)
        return "Fail #1"
    if (t.bar() != 2)
        return "Fail #2"
    if (t !is First)
        return "Fail #3"
    if (t !is Second)
        return "Fail #4"

    return "OK"
}
