Fix #492. Traits that require an outer pointer are not SAMs.

[DarkDimius]

No description provided.

[smarter]

Should be T.F2 instead of F2, or add import T._

[DarkDimius]

@smarter please review. Does this unblock you?

[smarter]

It should yes, though I have a fix/workaround to avoid test failures on #411 I'll push soon.

[smarter]

LGTM but this does not prevent all the "fake" SAMs, as noted in #492 (comment)

trait X {
  def foo(): Int = 3
}

trait FakeSAM extends X {
  def apply(x: Int): Int
  override def foo(): Int = super.foo()
  // Get extra abstract method "private def super$foo(): Int"
}

And

trait FakeSAM2 {
  def apply(x: Int): Int
  val dummy: Int = 3
  // the val becomes:
  // <accessor> def dummy(): Int <--- extra abstract method
  // protected def initial$dummy(): Int = 3
}

I don't actually require this to be merged for #411 as I can easily avoid the test failure, so don't feel forced to merge it now.

[DarkDimius]

I am aware of super-calls. But I do not want to make changes to handling of super-accessors before the refactoring is merged. I'll make it in a saparate PR later.

[DarkDimius]

Second example is not a SAM - SAMs cannot have fields.

[smarter]

That's not a requirement of https://docs.oracle.com/javase/8/docs/api/java/lang/FunctionalInterface.html, static fields are allowed.

[DarkDimius]

there's no such thing as static field in scala.
The only static thing that exists in scala is forwarders.

[odersky]

LGTM also