Our codebase is full of this pattern and I love it. Every time I get clean up temporaries and expose an immutable variable outside of the setup, makes me way too happy.

A lot of the time it looks like this:

  let config = {
      let config = get_config_bytes();
      let mut config = Config::from(config);
      config.do_something_mut();
      config.do_another_mut();
      config
  };