use std::cell::Cell;

#[derive(Debug)]
struct NonCopyBool(bool);

fn main() {
    let flag = Cell::new(NonCopyBool(false));

    let c1 = || flag.set(NonCopyBool(true));

    let c2 = || println!("{:?}", flag.replace(NonCopyBool(false)));

    c1();
    c2();
}