use std::marker::PhantomData;

// SAFETY invariant: the pointer is valid as &'a i32
#[derive(Clone, Copy)]
pub struct MyRef<'a>((*const i32, PhantomData<&'a ()>));
// Note: This needs to be a tuple nested inside, since CoerceShared currently requires exactly 1 field

impl<'a> MyRef<'a> {
    pub fn new(r: &'a i32) -> Self {
        MyRef((r, PhantomData))
    }

    pub fn to_ref(self) -> &'a i32 {
        unsafe { &*self.0.0 }
    }
}

#![feature(reborrow)]

use std::marker::{CoerceShared, PhantomData, Reborrow};
use std::ptr;

use dep::MyRef;

#[expect(dead_code)]
struct MyMut<'a>((*const i32, PhantomData<&'a ()>));
impl Reborrow for MyMut<'_> {}
impl<'a> CoerceShared<MyRef<'a>> for MyMut<'a> {}

fn main() {
    let my_mut = MyMut((ptr::null(), PhantomData));
    let my_ref: MyRef<'_> = my_mut;
    println!("{}", my_ref.to_ref());
}