use std::marker::PhantomData;

#[derive(Debug)]
enum ONE{}
#[derive(Debug)]
enum TWO{}

#[derive(Debug)]
struct X<R> {
  i: i32,
  _state: PhantomData<R>
}

fn g<R>() -> X<R> {
  return X{
    i: 42,
    _state: PhantomData
  };
}

fn into_one() -> X<ONE> {
    println!("Returning a ONE");
    g()
}

fn into_two() -> X<TWO> {
    println!("Returning a TWO");
    g()
}

fn main() {
    let a: X<ONE> = g();
    let b: X<TWO> = g();
    let c: X<ONE> = into_one();
    let d: X<TWO> = into_two();
    println!("{:#?} {:#?} {:#?} {:#?}", a, b, c, d);
}