#![allow(dead_code, deprecated, unused_variables, unused_mut)]
#![feature(cell_leak)]
use std::cell::{RefCell, RefMut};
fn main() {
    let cell = RefCell::new(0);
    let value = RefMut::leak(cell.borrow_mut());
    assert_eq!(* value, 0);
    *value = 1;
    assert!(cell.try_borrow_mut().is_err());
}