2 use std::marker::PhantomPinned;
5 struct MyType<'a>(Cell<Option<&'a mut MyType<'a>>>, PhantomPinned);
7 impl<'a> Clone for &'a mut MyType<'a> {
9 fn clone(&self) -> &'a mut MyType<'a> {
10 self.0.replace(None).unwrap()
15 let mut unpinned = MyType(Cell::new(None), PhantomPinned);
16 let bad_addr = &unpinned as *const MyType<'_> as usize;
17 let mut p = Box::pin(MyType(Cell::new(Some(&mut unpinned)), PhantomPinned));
19 // p_mut1 is okay: it does not point to the bad_addr
20 let p_mut1: Pin<&mut MyType<'_>> = p.as_mut();
21 assert_ne!(bad_addr, &*p_mut1 as *const _ as usize);
23 // but p_mut2 does point to bad_addr! this is unsound
24 let p_mut2: Pin<&mut MyType<'_>> = p_mut1.clone();
25 assert_eq!(bad_addr, &*p_mut2 as *const _ as usize);