#![feature(never_type)]

use std::mem::{size_of};

#[derive(Debug, Copy, Clone)]
enum Singleton { Zero }

#[derive(Debug, Copy, Clone)]
enum Empty {}

fn main() {
    let singleton_box = Box::new(Singleton::Zero);
    let never_box = unsafe { std::mem::transmute::<Box<()>, Box<Empty>>(Box::new(())) };
    let bang_box = unsafe { std::mem::transmute::<Box<()>, Box<!>>(Box::new(())) };
    println!("size_of::<()> = {}", size_of::<()>());
    println!("size_of::<Singleton> = {}", size_of::<Singleton>());
    println!("size_of::<Empty> = {}", size_of::<Empty>());
    println!("size_of::<!> = {}", size_of::<!>());
    println!("value of Box<Singleton> = {:?}", singleton_box);
    println!("value of Box<Never> = {:?}", never_box);
    println!("value of Box<!> = {:?}", bang_box);
}