#![allow(dead_code)]
#![allow(unused_variables)]
#![allow(unused_imports)]

trait Diff<'da> {
    type Target: 'da;
    fn diff(&'da self, other: &'da Self) -> Edit<'da, Self::Target>;
}

enum Edit<'da, T> {
    Copy,
    Change(&'da T),
}

struct A<'a>(&'a u32);

struct EditedA<'da, 'a>(Edit<'da, A<'a>>);

impl<'da, 'a> Diff<'da> for A<'a> {
    type Target = &'a u32;

    fn diff(&'da self, other: &'da Self) -> Edit<'da, Self::Target> {
        Edit::Change(&other.0)
    }
}

fn main() {
    A(&32).diff(&A(&22));
}