Implementing a method with wrong number of type parameters leads to runtime AbstractMethodError

[panacekcz]

This code compiles, but fails at runtime, as long as the numbers of type parameters of the two a methods differ.

trait P[A]{
  def a[T]: A
}
class C extends P[Int]{
  def a = 1
}
object O{
  def main(args: Array[String]) = {
    val p: P[Int] = new C
    println(p.a)
  }
}

Output:

Exception in thread "main" java.lang.AbstractMethodError: C.a()Ljava/lang/Object;
	at O$.main(AME.scala:10)
	at O.main(AME.scala)