20 lines
654 B
Rust
20 lines
654 B
Rust
|
#![feature(weak_into_raw)]
|
||
|
|
|
||
|
|
use std::rc::{Rc, Weak};
|
||
|
|
use std::ptr;
|
||
|
|
|
||
|
|
/// Taken from the `Weak::as_raw` doctest.
|
||
|
|
fn main() {
|
||
|
|
let strong = Rc::new(Box::new(42));
|
||
|
|
let weak = Rc::downgrade(&strong);
|
||
|
|
// Both point to the same object
|
||
|
|
assert!(ptr::eq(&*strong, Weak::as_raw(&weak)));
|
||
|
|
// The strong here keeps it alive, so we can still access the object.
|
||
|
|
assert_eq!(42, **unsafe { &*Weak::as_raw(&weak) });
|
||
|
|
|
||
|
|
drop(strong);
|
||
|
|
// But not any more. We can do Weak::as_raw(&weak), but accessing the pointer would lead to
|
||
|
|
// undefined behaviour.
|
||
|
|
assert_eq!(42, **unsafe { &*Weak::as_raw(&weak) }); //~ ERROR dangling pointer
|
||
|
|
}
|