`val`s in `final` classes don't get the same optimisation that `final val`s get

Compiler version

3.0.0

Minimized code

class Creature {
  val range: Int = 10
  println(range)
}

class Ant1 extends Creature {
  override final val range: Int = 2
}

final class Ant2 extends Creature {
  override val range: Int = 2
}

object Test extends App {
  new Ant1
  new Ant2
}

Output

2
0

Expectation

2
2

(Mentioned on the side in #12570.)

[nicolasstucki]

Does the behavior of the uninitialized field access have strict semantics, or is it an undefined behavior?

Is the behavior of uninitialized fields sound? Consider val x: 2 = 2, if accessed before initialization it could yield 0 which is unsound because 0 <:< 2 does not hold. Otherwise, 0 would need to be a bottom type of all numerical constants which would break all type-level numeric computations.

[nicolasstucki]

Good. Then it is ok to optimize them and therefore have fewer cases with uninitialized accesses that return unexpected values