src/tools/miri/tests/compile-fail/memleak_rc.rs

//error-pattern: the evaluated program leaked memory

use std::rc::Rc;
use std::cell::RefCell;

struct Dummy(Rc<RefCell<Option<Dummy>>>);

fn main() {
    let x = Dummy(Rc::new(RefCell::new(None)));
    let y = Dummy(x.0.clone());
    *x.0.borrow_mut() = Some(y);
}