[PATCH 3/4] rust: alloc: implement `Borrow` and `BorrowMut` for `KBox`

[Alexandre Courbot <acourbot@nvidia.com>]

Implement these two common traits, which allow generic types to store
either an owned value or a reference to it, leveraging the `Deref`
implementation.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
 rust/kernel/alloc/kbox.rs | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs
index c386ff771d506a2eb4c211a93ea9b59bc04c93f5..73e66b4118b723a5e54de53144e4c1884098342f 100644
--- a/rust/kernel/alloc/kbox.rs
+++ b/rust/kernel/alloc/kbox.rs
@@ -6,6 +6,7 @@
 use super::allocator::{KVmalloc, Kmalloc, Vmalloc};
 use super::{AllocError, Allocator, Flags};
 use core::alloc::Layout;
+use core::borrow::{Borrow, BorrowMut};
 use core::fmt;
 use core::marker::PhantomData;
 use core::mem::ManuallyDrop;
@@ -499,6 +500,26 @@ fn deref_mut(&mut self) -> &mut T {
     }
 }
 
+impl<T, A> Borrow<T> for Box<T, A>
+where
+    T: ?Sized,
+    A: Allocator,
+{
+    fn borrow(&self) -> &T {
+        self.deref()
+    }
+}
+
+impl<T, A> BorrowMut<T> for Box<T, A>
+where
+    T: ?Sized,
+    A: Allocator,
+{
+    fn borrow_mut(&mut self) -> &mut T {
+        self.deref_mut()
+    }
+}
+
 impl<T, A> fmt::Display for Box<T, A>
 where
     T: ?Sized + fmt::Display,

-- 
2.49.0