$outer of trait not implemented if the class doesn't need $outer

[liufengyun]

Following code runs in Scalac, but failed to run in Dotty. Inspecting the generated code shows that the $outer for A.Inner is not implemented in the top-leve class Inner.

class A {
  val a = "a"
  trait Inner {
    def f = println(a)
    def h = 3
  }
}

class Inner extends O.a.Inner

object O {
  val a = new A

  def main(args: Array[String]): Unit = {
    (new Inner).f
  }
}

A fix is in order, will push soon.

[liufengyun]

Fixing the above issue expose another issue about $outer.

We should generate an $outer for the anonymous class new Inner2 {}, as Inner requires an outer. But currently we don't. The latest commit 72bbc30 fix this problem.

trait A {
  val a = "a"
  trait Inner {
    def f = println(a)
    def h = 3
  }
}

trait B extends A {
  trait Inner2 extends Inner
  new Inner2 {}
}