S2.scala:12: error: method packageAbstract overrides nothing
  override private[b] def packageAbstract() = ()      // fail
                          ^
S2.scala:16: error: method packageConcrete overrides nothing
  override private[b] def packageConcrete() = ()      // fail
                          ^
S2.scala:36: error: method packageConcrete overrides nothing
  override protected[b] def packageConcrete() = ()    // fail
                            ^
S2.scala:47: error: method packageConcrete overrides nothing
  override private[a] def packageConcrete() = ()        // fail
                          ^
S2.scala:58: error: method packageConcrete overrides nothing
  override def packageConcrete() = ()   // fail
               ^
5 errors found