builder > A.scala B.scala
compiling Set(A.scala, B.scala)
Changes: Map()
builder > A.scala
compiling Set(A.scala)
Changes: Map(trait A -> List(Changed(Definition(A.S))[type S changed from A.this.S to A.this.S flags: ]))
invalidate B.scala because inherited method changed [Changed(Definition(A.S))[type S changed from A.this.S to A.this.S flags: ]]
compiling Set(B.scala)
B.scala:3: error: type mismatch;
 found   : B.this.S
    (which expands to)  Long
 required: Int
  def y: Int = x
               ^