Code shared from the Rust Playground

playground.rs

use core::pin::Pin;
use core::marker::PhantomPinned;

#[derive(Debug)]
struct Unm(i32, PhantomPinned);

fn foo() -> Pin<Box<Unm>> {
    Box::pin(Unm(1, PhantomPinned))
}

fn main() {
    let mut f = foo();
    
    //let u: &mut Unm = f.as_mut().get_mut();
    //Pin::into_inner(f);
    
    dbg![f];
}