use std::rc::Rc;
use std::collections::HashMap;

struct Message<'a> {
    user: &'a User,
    text: String,
    // timestamp, etc.
}

struct User {
    // Actually a VecDeque, but Vec for simplicity
    messages: Vec<Rc<Message<'static>>>,
    username: String,
    // other info
}

struct Context {
    messages: Vec<Rc<Message<'static>>>,
    users: HashMap<String, User>,
}

// Both Context and User outlive Messages
// Both Context and User have references to Messages
// Context outlives Users (Here, by owning User)

// No matter who owns what (Context directly owns Messages/etc) the same sort of issues arise

fn main() {}