Reference non-trivial keys for rust

ref_key.rs

#[derive(Hash, Debug, PartialEq, Eq, Clone)]
struct KeyOwned {
    s1: String,
    s2: String,
}

#[derive(Hash, Debug, PartialEq, Eq)]
struct KeyRef<'a> {
    s1: &'a str,
    s2: &'a str,
}

impl hashbrown::Equivalent<KeyOwned> for KeyRef<'_> {
    fn equivalent(&self, key: &KeyOwned) -> bool {
        self.s1 == key.s1 && self.s2 == key.s2
    }
}

fn main() {
    let mut map: hashbrown::HashMap<KeyOwned, usize> = Default::default();
    map.insert(
        KeyOwned {
            s1: "Hello".into(),
            s2: "World".into(),
        },
        42,
    );
    map.insert(
        KeyOwned {
            s1: "Foo".into(),
            s2: "Bar".into(),
        }.into(),
        23,
    );

    dbg!(&map);

    let r = map.get(&KeyRef {
        s1: "Hello",
        s2: "World",
    }).unwrap();

    dbg!(r);
}