Inferring type of generic implicit parameter from return type

Question

Say I have a simple class like this

abstract class Foo {
  implicit val impInt: Int = 42
  def f[A]()(implicit a: A): A
  val f2: Int = f()
}

Answer 1

There must be something wrong with the way ordering instances are generated, as the code below works. I'd report a bug.

case object types {
  implicit def buh[X]: List[X] = List()
}
abstract class Foo {

  import types._

  def f[A]()(implicit l: List[A]): A
  val f2: Int = f()
}