diff options
Diffstat (limited to 'library/core/src/cell.rs')
| -rw-r--r-- | library/core/src/cell.rs | 35 |
1 files changed, 33 insertions, 2 deletions
diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs index 129213fde..897d03595 100644 --- a/library/core/src/cell.rs +++ b/library/core/src/cell.rs @@ -196,7 +196,7 @@ use crate::cmp::Ordering; use crate::fmt::{self, Debug, Display}; use crate::marker::{PhantomData, Unsize}; use crate::mem; -use crate::ops::{CoerceUnsized, Deref, DerefMut}; +use crate::ops::{CoerceUnsized, Deref, DerefMut, DispatchFromDyn}; use crate::ptr::{self, NonNull}; mod lazy; @@ -571,6 +571,16 @@ impl<T: Default> Cell<T> { #[unstable(feature = "coerce_unsized", issue = "18598")] impl<T: CoerceUnsized<U>, U> CoerceUnsized<Cell<U>> for Cell<T> {} +// Allow types that wrap `Cell` to also implement `DispatchFromDyn` +// and become object safe method receivers. +// Note that currently `Cell` itself cannot be a method receiver +// because it does not implement Deref. +// In other words: +// `self: Cell<&Self>` won't work +// `self: CellWrapper<Self>` becomes possible +#[unstable(feature = "dispatch_from_dyn", issue = "none")] +impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<Cell<U>> for Cell<T> {} + impl<T> Cell<[T]> { /// Returns a `&[Cell<T>]` from a `&Cell<[T]>` /// @@ -622,7 +632,7 @@ pub struct RefCell<T: ?Sized> { // Stores the location of the earliest currently active borrow. // This gets updated whenever we go from having zero borrows // to having a single borrow. When a borrow occurs, this gets included - // in the generated `BorrowError/`BorrowMutError` + // in the generated `BorrowError`/`BorrowMutError` #[cfg(feature = "debug_refcell")] borrowed_at: Cell<Option<&'static crate::panic::Location<'static>>>, value: UnsafeCell<T>, @@ -2078,6 +2088,16 @@ impl<T> const From<T> for UnsafeCell<T> { #[unstable(feature = "coerce_unsized", issue = "18598")] impl<T: CoerceUnsized<U>, U> CoerceUnsized<UnsafeCell<U>> for UnsafeCell<T> {} +// Allow types that wrap `UnsafeCell` to also implement `DispatchFromDyn` +// and become object safe method receivers. +// Note that currently `UnsafeCell` itself cannot be a method receiver +// because it does not implement Deref. +// In other words: +// `self: UnsafeCell<&Self>` won't work +// `self: UnsafeCellWrapper<Self>` becomes possible +#[unstable(feature = "dispatch_from_dyn", issue = "none")] +impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<UnsafeCell<U>> for UnsafeCell<T> {} + /// [`UnsafeCell`], but [`Sync`]. /// /// This is just an `UnsafeCell`, except it implements `Sync` @@ -2169,6 +2189,17 @@ impl<T> const From<T> for SyncUnsafeCell<T> { //#[unstable(feature = "sync_unsafe_cell", issue = "95439")] impl<T: CoerceUnsized<U>, U> CoerceUnsized<SyncUnsafeCell<U>> for SyncUnsafeCell<T> {} +// Allow types that wrap `SyncUnsafeCell` to also implement `DispatchFromDyn` +// and become object safe method receivers. +// Note that currently `SyncUnsafeCell` itself cannot be a method receiver +// because it does not implement Deref. +// In other words: +// `self: SyncUnsafeCell<&Self>` won't work +// `self: SyncUnsafeCellWrapper<Self>` becomes possible +#[unstable(feature = "dispatch_from_dyn", issue = "none")] +//#[unstable(feature = "sync_unsafe_cell", issue = "95439")] +impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<SyncUnsafeCell<U>> for SyncUnsafeCell<T> {} + #[allow(unused)] fn assert_coerce_unsized( a: UnsafeCell<&i32>, |