The `arbitrary_self_types` RFC [1] is accepted and the feature is being
worked on [2]. As part of the RFC, a new `Receiver` trait is to be added,
and it will be automatically implemented for all types that have `Deref`
implementation. This is different from the existing `Receiver` trait
that we use, which is a custom implementation that opts-in a type into
being used as receiver.

To prepare us for the change, remove the `Receiver` implementation and
the associated feature. To still allow `Arc` and others to be used as
method receivers, turn on `arbitrary_self_types` feature instead.

Cc: Adrian Taylor <ade@hohum.me.uk>
Link: https://github.com/rust-lang/rfcs/pull/3519 [1]
Link: https://github.com/rust-lang/rust/issues/44874 [2]
Signed-off-by: Gary Guo <gary@garyguo.net>
---
 rust/kernel/lib.rs      | 2 +-
 rust/kernel/list/arc.rs | 3 ---
 rust/kernel/sync/arc.rs | 6 ------
 scripts/Makefile.build  | 2 +-
 4 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index f10b06a78b9d5..35a65a085bce5 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -12,10 +12,10 @@
 //! do so first instead of bypassing this crate.
 
 #![no_std]
+#![feature(arbitrary_self_types)]
 #![feature(coerce_unsized)]
 #![feature(dispatch_from_dyn)]
 #![feature(new_uninit)]
-#![feature(receiver_trait)]
 #![feature(unsize)]
 
 // Ensure conditional compilation based on the kernel configuration works;
diff --git a/rust/kernel/list/arc.rs b/rust/kernel/list/arc.rs
index d801b9dc6291d..3483d8c232c4f 100644
--- a/rust/kernel/list/arc.rs
+++ b/rust/kernel/list/arc.rs
@@ -441,9 +441,6 @@ fn as_ref(&self) -> &Arc<T> {
     }
 }
 
-// This is to allow [`ListArc`] (and variants) to be used as the type of `self`.
-impl<T, const ID: u64> core::ops::Receiver for ListArc<T, ID> where T: ListArcSafe<ID> + ?Sized {}
-
 // This is to allow coercion from `ListArc<T>` to `ListArc<U>` if `T` can be converted to the
 // dynamically-sized type (DST) `U`.
 impl<T, U, const ID: u64> core::ops::CoerceUnsized<ListArc<U, ID>> for ListArc<T, ID>
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index 3021f30fd822f..28743a7c74a84 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -171,9 +171,6 @@ unsafe fn container_of(ptr: *const T) -> NonNull<ArcInner<T>> {
     }
 }
 
-// This is to allow [`Arc`] (and variants) to be used as the type of `self`.
-impl<T: ?Sized> core::ops::Receiver for Arc<T> {}
-
 // This is to allow coercion from `Arc<T>` to `Arc<U>` if `T` can be converted to the
 // dynamically-sized type (DST) `U`.
 impl<T: ?Sized + Unsize<U>, U: ?Sized> core::ops::CoerceUnsized<Arc<U>> for Arc<T> {}
@@ -480,9 +477,6 @@ pub struct ArcBorrow<'a, T: ?Sized + 'a> {
     _p: PhantomData<&'a ()>,
 }
 
-// This is to allow [`ArcBorrow`] (and variants) to be used as the type of `self`.
-impl<T: ?Sized> core::ops::Receiver for ArcBorrow<'_, T> {}
-
 // This is to allow `ArcBorrow<U>` to be dispatched on when `ArcBorrow<T>` can be coerced into
 // `ArcBorrow<U>`.
 impl<T: ?Sized + Unsize<U>, U: ?Sized> core::ops::DispatchFromDyn<ArcBorrow<'_, U>>
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 72b1232b1f7d9..56b8c72687255 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -263,7 +263,7 @@ $(obj)/%.lst: $(obj)/%.c FORCE
 # Compile Rust sources (.rs)
 # ---------------------------------------------------------------------------
 
-rust_allowed_features := new_uninit
+rust_allowed_features := arbitrary_self_types,new_uninit
 
 # `--out-dir` is required to avoid temporaries being created by `rustc` in the
 # current working directory, which may be not accessible in the out-of-tree

base-commit: 93dc3be19450447a3a7090bd1dfb9f3daac3e8d2
-- 
2.44.1

On Tue, Sep 10, 2024 at 2:09 PM Gary Guo <gary@garyguo.net> wrote:
>
> The `arbitrary_self_types` RFC [1] is accepted and the feature is being
> worked on [2]. As part of the RFC, a new `Receiver` trait is to be added,
> and it will be automatically implemented for all types that have `Deref`
> implementation. This is different from the existing `Receiver` trait
> that we use, which is a custom implementation that opts-in a type into
> being used as receiver.
>
> To prepare us for the change, remove the `Receiver` implementation and
> the associated feature. To still allow `Arc` and others to be used as
> method receivers, turn on `arbitrary_self_types` feature instead.
>
> Cc: Adrian Taylor <ade@hohum.me.uk>
> Link: https://github.com/rust-lang/rfcs/pull/3519 [1]
> Link: https://github.com/rust-lang/rust/issues/44874 [2]
> Signed-off-by: Gary Guo <gary@garyguo.net>

Please update the commit message to explain the compatibility
situation with various rustc releases.

Alice