outer class inaccessible during initialization of inner class in Scala 2.13.0

[joschua-fink]

trait Foo {
  trait Bar {
    println(Foo.this)
  }
}

abstract class Foo1 extends Foo

object Foo2 extends Foo1 {
  new Bar {}
}

Foo2

In Scala 2.13.0 the example above unexpectely prints null. Making Foo1 a trait or Foo2 something else than an object solves the issue. The example works as expected in Scala 2.12.10.

[som-snytt]

Probably related to scala/scala#7270 from last fall, in RC1.

I don't do the crossword any more so maybe I'll find time to finally understand the conversations on that ticket.

The trait version that works

+       at Foo$Bar.$init$(t11736.scala:5)
+       at Foo2$$anon$1.<init>(t11736.scala:14)
+       at Foo2$.<clinit>(t11736.scala:14)

versus

        at Foo$Bar.$init$(t11736.scala:5)
        at Foo2$$anon$1.<init>(t11736.scala:12)
        at Foo2$.<init>(t11736.scala:12)
        at Foo2$.<clinit>(t11736.scala:11)

I don't quite have time tonight, it's a school night.

[SethTisue]

@retronym @lrytz interested in looking into this?

[som-snytt]

There is an elaborate before-and-after or he-said-she-said test at scala/scala#8425 where retronym lrytz will say it blows the complexity budget.

[lrytz]

The problem is that the first statement in object Foo2 is a new. The implementation fails to tell this apart from the super call, and puts it in the wrong place. The following works correctly (added a println):

trait Foo {
  trait Bar {
    println(Foo.this)
  }
}

abstract class Foo1 extends Foo

object Foo2 extends Foo1 {
  println("statement after the super call")
  new Bar {}
}

Foo2

Fix in scala/scala#8431.