message: also test Box<self> receiver
diff: @@ -5,12 +5,18 @@ fn ref_box_dyn() {
  trait Trait {
  fn method(&self);
  +
  + fn box_method(self: Box<Self>);
  }
  impl Trait for Struct {
  fn method(&self) {
  assert_eq!(self.0, 42);
  }
  +
  + fn box_method(self: Box<Self>) {
  + assert_eq!(self.0, 7);
  + }
  }
  struct Foo<T: ?Sized>(T);
  @@ -27,6 +33,9 @@ fn ref_box_dyn() {
  let y = &y;
  y.method();
  +
  + let y: Box<dyn Trait> = Box::new(Struct(7));
  + y.box_method();
  }
  