trait T {
    fn fn1(&self);
}

struct S {}

impl T for S {
    fn fn1(&self) {
        dbg!("test");
    }
}

struct TWrapper {
    x: Box<dyn T>
}

impl TWrapper {
    fn fn2(&self) {
        self.x.fn1();
    }
}

fn f(t: &mut impl T) {
    let tw = TWrapper {
        x: Box::new(t)
    };
    tw.fn2();
}

fn main() {
    let mut s = S{};
    f(&mut s);
}