#![allow(unused_variables)]
#![feature(get_mut_unchecked)]
fn main() {
    use std::rc::Rc;
    let mut five = Rc::<u32>::new_uninit();
    Rc::get_mut(&mut five).unwrap().write(5);
    let five = unsafe { five.assume_init() };
    assert_eq!(* five, 5)
}