use std::cmp::Ordering;
use std::collections::BTreeSet;

#[derive(Debug)]
pub(crate) enum Value {
    One,
    Two(i32),
}

impl Ord for Value {
    fn cmp(&self, other: &Value) -> Ordering {
        match (self, other) {
            (Value::One, Value::One) => Ordering::Equal,
            (Value::Two(x), Value::Two(y)) => x.cmp(y),
            _ => panic!("can't compare values {:?} and {:?}", self, other),
        }
    }
}

impl PartialOrd for Value {
    fn partial_cmp(&self, other: &Value) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl PartialEq for Value {
    fn eq(&self, other: &Value) -> bool {
        match (self, other) {
            (Value::One, Value::One) => true,
            (Value::Two(x), Value::Two(y)) => x == y,
            _ => panic!("can't compare values {:?} and {:?}", self, other),
        }
    }
}

impl Eq for Value {}

fn main() {
    let lhs = BTreeSet::from([Value::One]);
    let rhs = BTreeSet::from([Value::Two(1), Value::Two(2)]);
    let _ = lhs == rhs;
}