Unsoundness with refined SAM

[panacekcz]

When instantiating SAMs, type refinement is not checked, allowing contradicting types.

This compiles but fails at runtime:

trait SAM {
  type T >: Int
  def apply(x: Int): Int
  def t: T = 1
}

object O{
  def main(a:Array[String])={
    val fn: SAM {type T = String} = (i:Int) => i
    def cce: String = fn.t 
    println(cce)
  }
}

Output:

Exception in thread "main" java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String
	at O$.cce$1(SamUnsound.scala:10)
	at O$.main(SamUnsound.scala:11)
	at O.main(SamUnsound.scala)

[Blaisorblade]

Thanks for the catch!