Merging upstream version 1.69.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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>,