#![allow(unused_variables)]
#![feature(allocator_api)]
fn main() {
    use std::sync::Arc;
    use std::alloc::System;
    let x = Arc::new_in("hello".to_owned(), System);
    let (x_ptr, alloc) = Arc::into_raw_with_allocator(x);
    unsafe {
        let x = Arc::from_raw_in(x_ptr, System);
        assert_eq!(&* x, "hello");
    }
}