Looking at this from a Rusty point of view, ownership rules make this possible. When this function creates but button, it owns it. To mutate it (addLabel/setAlignment/sizeToFit), it has to own it. But for it to continue to exist after the function returns, something else has to own it. Therefore, Window::addSubview has to take ownership of the button, and so, has to come last:

  fn make_button(window: &mut Window) {
      let mut button = Button::create();
      button.set_label("test");
      button.set_alignment(Alignment::TopLeft);
      button.size_to_fit();
      window.add_subview(button);
  }

(complete toy example at https://play.rust-lang.org/?gist=cb1db59a3ee1f4bad0a5472267c... )

In that situation, the button's destructor absolutely could delete itself.