linux-kernel - [PATCH 5/7] rust: sync: allow type of `self` to be `ArcBorrow<T>`

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Date:   Wed, 28 Dec 2022 06:03:44 +0000
From:   Wedson Almeida Filho <wedsonaf@...il.com>
To:     rust-for-linux@...r.kernel.org
Cc:     Miguel Ojeda <ojeda@...nel.org>,
        Alex Gaynor <alex.gaynor@...il.com>,
        Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
        Björn Roy Baron <bjorn3_gh@...tonmail.com>,
        linux-kernel@...r.kernel.org,
        Wedson Almeida Filho <wedsonaf@...il.com>
Subject: [PATCH 5/7] rust: sync: allow type of `self` to be `ArcBorrow<T>`

This allows associated functions whose `self` argument has
`ArcBorrow<T>` as their type. This, in turn, allows callers to use the
dot syntax to make calls.

Signed-off-by: Wedson Almeida Filho <wedsonaf@...il.com>
---
 rust/kernel/sync/arc.rs | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index f68bfc02c81a..84f31c85a513 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -255,11 +255,34 @@ impl<T: ?Sized> Drop for Arc<T> {
 /// // Assert that both `obj` and `cloned` point to the same underlying object.
 /// assert!(core::ptr::eq(&*obj, &*cloned));
 /// ```
+///
+/// Using `ArcBorrow<T>` as the type of `self`:
+///
+/// ```
+/// use crate::sync::{Arc, ArcBorrow};
+///
+/// struct Example {
+///     a: u32,
+///     b: u32,
+/// }
+///
+/// impl Example {
+///     fn use_reference(self: ArcBorrow<'_, Self>) {
+///         // ...
+///     }
+/// }
+///
+/// let obj = Arc::try_new(Example { a: 10, b: 20 })?;
+/// obj.as_arc_borrow().use_reference();
+/// ```
 pub struct ArcBorrow<'a, T: ?Sized + 'a> {
     inner: NonNull<ArcInner<T>>,
     _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> {}
+
 impl<T: ?Sized> Clone for ArcBorrow<'_, T> {
     fn clone(&self) -> Self {
         *self
-- 
2.34.1