On Fri Mar 7, 2025 at 5:41 PM CET, Tamir Duberstein wrote:
In Rust 1.51.0, Clippy introduced the `ignored_unit_patterns` lint [1]:
You link to the `ptr_as_ptr` lint though, is this a typo?
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>()` 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()`.
These all seem very nice, thanks! I think it would also be a good idea to enable `ptr_cast_constness` [1], since those are the other kind of `as` usage that we should be doing via `cast_mut`/`cast_const`.
There are still some legitimate uses of `as` casts, when unsizing values. I don't know if these two lints can trigger on those, it would be nice if they don't. So those should continue to use `as`, but other than that, there shouldn't be any `as` in our code :)
[1]: https://rust-lang.github.io/rust-clippy/master/index.html#ptr_cast_constness
(I will take a look at the patch itself a bit later)
--- Cheers, Benno
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
Makefile | 1 + rust/bindings/lib.rs | 1 + rust/kernel/alloc/allocator_test.rs | 2 +- rust/kernel/alloc/kvec.rs | 4 ++-- rust/kernel/device.rs | 5 +++-- rust/kernel/devres.rs | 2 +- rust/kernel/error.rs | 2 +- rust/kernel/fs/file.rs | 2 +- rust/kernel/kunit.rs | 15 +++++++-------- rust/kernel/lib.rs | 4 ++-- rust/kernel/list/impl_list_item_mod.rs | 2 +- rust/kernel/pci.rs | 2 +- rust/kernel/platform.rs | 4 +++- rust/kernel/print.rs | 11 +++++------ rust/kernel/seq_file.rs | 3 ++- rust/kernel/str.rs | 2 +- rust/kernel/sync/poll.rs | 2 +- rust/kernel/workqueue.rs | 10 +++++----- rust/uapi/lib.rs | 1 + 19 files changed, 40 insertions(+), 35 deletions(-)