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impl DispatchFromDyn for Cell and UnsafeCell

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This commit is contained in:
dimi 2022-05-24 23:56:19 +02:00
parent c8e6a9e8b6
commit a2d1cb2c22
2 changed files with 54 additions and 1 deletions
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33
library/core/src/cell.rs
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@ -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]>`
///
@ -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>,