uncheckedStable.scala

scala> import annotation.unchecked.uncheckedStable
import annotation.unchecked.uncheckedStable

scala> class A { class B }
defined class A

scala> @uncheckedStable var a = new A
a: A = A@6885f3f7

scala> println(new a.B)
$line24.$read$$iw$$iw$A$B@38d308e7



scala> object O { @uncheckedStable def N = None }
defined object O

scala> def m(a: Any) = a match { case O.N => "rien" }
m: (a: Any)String

scala> m(None)
res2: String = rien