#![allow(unused_variables)]
#![feature(allocator_api)]
fn main() {
    use std::sync::{Arc, Weak};
    use std::alloc::System;
    let strong = Arc::new_in("hello".to_owned(), System);
    let weak = Arc::downgrade(&strong);
    let (raw, alloc) = weak.into_raw_with_allocator();
    assert_eq!(1, Arc::weak_count(& strong));
    assert_eq!("hello", unsafe { &* raw });
    drop(unsafe { Weak::from_raw_in(raw, alloc) });
    assert_eq!(0, Arc::weak_count(& strong));
}