Showcase bug SI-3346 and applications to deep embeddings

Base.scala

//Paste this code on a fresh Scala console.
trait Exp[+T]
case class Const[T](t: T) extends Exp[T]
implicit def toExp[T](t: T): Exp[T] = Const(t)

case class Plus(x: Exp[Int], y: Exp[Int]) extends Exp[Int]

class IntOps(x: Exp[Int]) {
  def +(y: Exp[Int]) = Plus(x, y)
}

val x = toExp(1)

/*
 * Then paste either one of the below two files. Pasting both together will make the defined
 * conversions ambiguous
 */

FailedPimp.scala

//Alternative 1, does not work: https://issues.scala-lang.org/browse/SI-3346
implicit def intPimp[T](x: T)(implicit conv: T => Exp[Int]) = new IntOps(x)

1 + x
intPimp(x) + 1 //This line works.
x + 1 //Error!

SuccessfulPimp.scala

//Workaround
implicit def expIntPimp(x: Exp[Int]) = new IntOps(x)
implicit def intPimp(x: Int) = expIntPimp(x)

1 + x
x + 1