use std::fmt::Display;

trait Displayable {
    fn display(self) -> Box<dyn Display>;
}

impl<T: Display> Displayable for (T, Option<&'static T>) {
    fn display(self) -> Box<dyn Display> {
        Box::new(self.0)
    }
}

fn extend_lt<T, U>(val: T) -> Box<dyn Display>
where
    (T, Option<U>): Displayable,
{
    Displayable::display((val, None))
}

fn main() {
    // The type parameter `U = &'static &'temporary str` is ill-formed
    // because it does not enforce `'temporary: 'static` ...
    let val = extend_lt(&String::from("blah blah blah"));
    println!("{}", val);
}