diff options
Diffstat (limited to 'src/liballoc')
| -rw-r--r-- | src/liballoc/rc.rs | 2 | ||||
| -rw-r--r-- | src/liballoc/sync.rs | 2 |
2 files changed, 4 insertions, 0 deletions
diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs index a9aa822173f..9d608c886b8 100644 --- a/src/liballoc/rc.rs +++ b/src/liballoc/rc.rs @@ -441,6 +441,8 @@ impl<T> Rc<[T]> { #[unstable(feature = "new_uninit", issue = "63291")] pub fn new_uninit_slice(len: usize) -> Rc<[mem::MaybeUninit<T>]> { let data_layout = Layout::array::<mem::MaybeUninit<T>>(len).unwrap(); + // This relies on `value` being the last field of `RcBox` in memory, + // so that the layout of `RcBox<T>` is the same as that of `RcBox<()>` followed by `T`. let (layout, offset) = Layout::new::<RcBox<()>>().extend(data_layout).unwrap(); unsafe { let allocated_ptr = Global.alloc(layout) diff --git a/src/liballoc/sync.rs b/src/liballoc/sync.rs index 50fd9850893..1bd177be0d5 100644 --- a/src/liballoc/sync.rs +++ b/src/liballoc/sync.rs @@ -425,6 +425,8 @@ impl<T> Arc<[T]> { #[unstable(feature = "new_uninit", issue = "63291")] pub fn new_uninit_slice(len: usize) -> Arc<[mem::MaybeUninit<T>]> { let data_layout = Layout::array::<mem::MaybeUninit<T>>(len).unwrap(); + // This relies on `value` being the last field of `RcBox` in memory, + // so that the layout of `RcBox<T>` is the same as that of `RcBox<()>` followed by `T`. let (layout, offset) = Layout::new::<ArcInner<()>>().extend(data_layout).unwrap(); unsafe { let allocated_ptr = Global.alloc(layout) |