amazing.scala

trait Show[A]

// These formulations all compile.
class A {
  implicit def z1[A]: Show[A] = null
  def f[A](implicit z: Show[A]): String = null

  f
  f[Int]
  f[Int](implicitly)
  f(implicitly[Show[Int]])
}

// f(implicitly) requires that we mask out three implicit values, otherwise e.g.
// a.scala:23: error: ambiguous implicit values:
//  both value StringCanBuildFrom in object Predef of type => scala.collection.generic.CanBuildFrom[String,Char,String]
//  and method $conforms in object Predef of type [A]=> <:<[A,A]
//  match expected type T
//   f(implicitly)
//     ^
// one error found
class B {
  val fallbackStringCanBuildFrom = null
  val StringCanBuildFrom = null
  val $conforms = null

  implicit def z1[A]: Show[A] = null
  def f[A](implicit z: Show[A]): String = null

  f(implicitly)
}