Re: [PATCH v2 2/5] rust: enable `clippy::ptr_as_ptr` lint

Tamir Duberstein
2025-03-12T15:19:33Z

On Wed, Mar 12, 2025 at 10:40 AM Benno Lossin <benno.lossin@proton.me> wrote:
>
> On Sun Mar 9, 2025 at 5:00 PM CET, Tamir Duberstein wrote:
> > In Rust 1.51.0, Clippy introduced the `ptr_as_ptr` lint [1]:
> >
> >> Though `as` casts between raw pointers are not terrible,
> >> `pointer::cast` is safer because it cannot accidentally change the
> >> pointer's mutability, nor cast the pointer to other types like `usize`.
> >
> > There are a few classes of changes required:
> > - Modules generated by bindgen are marked
> > `#[allow(clippy::ptr_as_ptr)]`.
> > - Inferred casts (` as _`) are replaced with `.cast()`.
> > - Ascribed casts (` as *... T`) are replaced with `.cast::<T>()`.
> > - Multistep casts from references (` as *const _ as *const T`) are
> > replaced with `let x: *const _ = &x;` and `.cast()` or `.cast::<T>()`
>
> Similarly to the other patch, this could be `let x = &raw x;`. (but it's
> fine to leave it as-is for now, we can also make that a
> good-first-issue.)

Yeah, same as the other patch; we can't directly do that here without
introducing some compiler infra or bumping MSRV.

> > according to the previous rules. The intermediate `let` binding is
> > required because `(x as *const _).cast::<T>()` results in inference
> > failure.
> > - Native literal C strings are replaced with `c_str!().as_char_ptr()`.
> >
> > Apply these changes and enable the lint -- no functional change
> > intended.
> >
> > Link: https://rust-lang.github.io/rust-clippy/master/index.html#ptr_as_ptr [1]
> > Signed-off-by: Tamir Duberstein <tamird@gmail.com>
>
> Reviewed-by: Benno Lossin <benno.lossin@proton.me>

Thanks!