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