// check-pass

// rust-lang/rust#72225: confusing diagnostics when calling FnMut through DerefMut.

use std::cell::RefCell;

struct S {
    f: Box<dyn FnMut()>
}

fn test(s: &RefCell<S>) {
    let mut guard = s.borrow_mut();
    (guard.f)();
}

fn main() {
    let s = RefCell::new(S {
        f: Box::new(|| ())
    });
    test(&s);
}