t6443c.scala:16: error: double definition:
method foo:(d: B.D)(a: Any)(d2: d.type)Unit and
method foo:(d: B.D)(a: Any, d2: d.type)Unit at line 11
have same type after erasure: (d: B.D, a: Object, d2: B.D)Unit
  def foo(d: D)(a: Any)(d2: d.type): Unit = ()
      ^
one error found