Re: [PATCH 1/3] rust: sync: implement == operator for ARef

[Gary Guo <gary@garyguo.net>]

On 2026-02-19 13:52, Alice Ryhl wrote:
> Rust Binder wants to perform a comparison between ARef<Task> and &Task,
> so define the == operator for ARef<_> when compared with another 
> ARef<_>
> or just a reference. The operator is implemented in terms of the same
> operator applied to the inner type.
> 
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>

I suppose `PartialEq<U>` cannot be implemented due to trait coherence 
issue?

Reviewed-by: Gary Guo <gary@garyguo.net>

> ---
>  rust/kernel/sync/aref.rs | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/rust/kernel/sync/aref.rs b/rust/kernel/sync/aref.rs
> index 
> 0616c0353c2b3b4d8b3be6c4b8156995a2f1d504..f56598a847e949b497f4cf2a05a7298a58a0ccef 
> 100644
> --- a/rust/kernel/sync/aref.rs
> +++ b/rust/kernel/sync/aref.rs
> @@ -170,3 +170,26 @@ fn drop(&mut self) {
>          unsafe { T::dec_ref(self.ptr) };
>      }
>  }
> +
> +impl<T, U> PartialEq<ARef<U>> for ARef<T>
> +where
> +    T: AlwaysRefCounted + PartialEq<U>,
> +    U: AlwaysRefCounted,
> +{
> +    #[inline]
> +    fn eq(&self, other: &ARef<U>) -> bool {
> +        T::eq(&**self, &**other)
> +    }
> +}
> +
> +impl<T, U> PartialEq<&'_ U> for ARef<T>
> +where
> +    T: AlwaysRefCounted + PartialEq<U>,
> +{
> +    #[inline]
> +    fn eq(&self, other: &&U) -> bool {
> +        T::eq(&**self, other)
> +    }
> +}
> +
> +impl<T: AlwaysRefCounted + Eq> Eq for ARef<T> {}