Re: [PATCH 4/6] rust: binder: enable `clippy::ref_as_ptr` lint

[Alice Ryhl <aliceryhl@google.com>]

On Fri, May 22, 2026 at 07:12:49PM +0200, Tamir Duberstein wrote:
> In Rust 1.78.0, Clippy introduced the `ref_as_ptr` lint [1]:
> 
> > Using `as` casts may result in silently changing mutability or type.
> 
> While this does not eliminate unchecked `as` conversions, it makes such
> conversions easier to scrutinize. It also has the slight benefit of
> removing a degree of freedom on which to bikeshed. Thus apply the changes
> and enable the lint in the Binder Rust driver -- no functional change
> intended.
> 
> Link: https://rust-lang.github.io/rust-clippy/master/index.html#ref_as_ptr [1]
> Signed-off-by: Tamir Duberstein <tamird@kernel.org>
> ---
>  drivers/android/binder/node.rs             | 2 +-
>  drivers/android/binder/page_range.rs       | 4 ++--
>  drivers/android/binder/rust_binder_main.rs | 2 +-
>  drivers/android/binder/trace.rs            | 2 +-
>  4 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/android/binder/node.rs b/drivers/android/binder/node.rs
> index d710940c3c8f..a4a3ddda6ac9 100644
> --- a/drivers/android/binder/node.rs
> +++ b/drivers/android/binder/node.rs
> @@ -321,7 +321,7 @@ pub(crate) unsafe fn remove_node_info(
>      /// An id that is unique across all binder nodes on the system. Used as the key in the
>      /// `by_node` map.
>      pub(crate) fn global_id(&self) -> usize {
> -        (self as *const Node).addr()
> +        core::ptr::from_ref(self).addr()

Can we please import core::ptr?

>      }
>  
>      pub(crate) fn get_id(&self) -> (u64, u64) {
> diff --git a/drivers/android/binder/page_range.rs b/drivers/android/binder/page_range.rs
> index 927b0802e80d..93e79c08b89a 100644
> --- a/drivers/android/binder/page_range.rs
> +++ b/drivers/android/binder/page_range.rs
> @@ -312,7 +312,7 @@ pub(crate) fn register_with_vma(&self, vma: &virt::VmaNew) -> Result<usize> {
>  
>          // SAFETY: This just initializes the pages array.
>          unsafe {
> -            let self_ptr = self as *const ShrinkablePageRange;
> +            let self_ptr = core::ptr::from_ref(self);
>              for i in 0..num_pages {
>                  let info = pages.as_mut_ptr().add(i);
>                  (&raw mut (*info).range).write(self_ptr);
> @@ -593,7 +593,7 @@ pub(crate) unsafe fn write<T: ?Sized>(&self, offset: usize, obj: &T) -> Result {
>          unsafe {
>              self.iterate(offset, size_of_val(obj), |page, offset, to_copy| {
>                  // SAFETY: The sum of `offset` and `to_copy` is bounded by the size of T.
> -                let obj_ptr = (obj as *const T).cast::<u8>().add(obj_offset);
> +                let obj_ptr = core::ptr::from_ref(obj).cast::<u8>().add(obj_offset);
>                  // SAFETY: We have a reference to the object, so the pointer is valid.
>                  page.write_raw(obj_ptr, offset, to_copy)?;
>                  obj_offset += to_copy;
> diff --git a/drivers/android/binder/rust_binder_main.rs b/drivers/android/binder/rust_binder_main.rs
> index fa28697982d3..88da29413e16 100644
> --- a/drivers/android/binder/rust_binder_main.rs
> +++ b/drivers/android/binder/rust_binder_main.rs
> @@ -6,7 +6,7 @@
>  
>  #![crate_name = "rust_binder"]
>  #![recursion_limit = "256"]
> -#![allow(clippy::as_underscore, clippy::ref_as_ptr, clippy::cast_lossless)]
> +#![allow(clippy::as_underscore, clippy::cast_lossless)]
>  
>  use kernel::{
>      bindings::{self, seq_file},
> diff --git a/drivers/android/binder/trace.rs b/drivers/android/binder/trace.rs
> index 5539672d7285..b6cae57801fc 100644
> --- a/drivers/android/binder/trace.rs
> +++ b/drivers/android/binder/trace.rs
> @@ -26,7 +26,7 @@
>  
>  #[inline]
>  fn raw_transaction(t: &Transaction) -> rust_binder_transaction {
> -    t as *const Transaction as rust_binder_transaction
> +    core::ptr::from_ref(t).cast_mut().cast()

This just removes the type annotations I had. I'm not sure it's
cleaner.

Alice

>  }
>  
>  #[inline]
> 
> -- 
> 2.54.0
>