From 88622323dde3d9d6efd6f2efcfaa0bced5af94c3 Mon Sep 17 00:00:00 2001 From: Alexandre Courbot Date: Mon, 10 Nov 2025 22:34:16 +0900 Subject: rust: enable slice_flatten feature and provide it through an extension trait In Rust 1.80, the previously unstable `slice::flatten` family of methods have been stabilized and renamed to `slice::as_flattened`. This creates an issue as we want to use `as_flattened`, but need to support the MSRV (which at the moment is Rust 1.78) where it is named `flatten`. Solve this by enabling the `slice_flatten` feature, and providing an `as_flattened` implementation through an extension trait for compiler versions where it is not available. The trait is then exported from the prelude, making the `as_flattened` family of methods transparently available for all supported compiler versions. This extension trait can be removed once the MSRV passes 1.80. Suggested-by: Miguel Ojeda Link: https://lore.kernel.org/all/CANiq72kK4pG=O35NwxPNoTO17oRcg1yfGcvr3==Fi4edr+sfmw@mail.gmail.com/ Acked-by: Danilo Krummrich Acked-by: Miguel Ojeda Reviewed-by: Alice Ryhl Signed-off-by: Alexandre Courbot Message-ID: <20251110-gsp_boot-v9-8-8ae4058e3c0e@nvidia.com> Message-ID: <20251104-b4-as-flattened-v3-1-6cb9c26b45cd@nvidia.com> --- rust/kernel/slice.rs | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 rust/kernel/slice.rs (limited to 'rust/kernel/slice.rs') diff --git a/rust/kernel/slice.rs b/rust/kernel/slice.rs new file mode 100644 index 000000000000..6ca91a4fd1f2 --- /dev/null +++ b/rust/kernel/slice.rs @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Additional (and temporary) slice helpers. + +/// Extension trait providing a portable version of [`as_flattened`] and +/// [`as_flattened_mut`]. +/// +/// In Rust 1.80, the previously unstable `slice::flatten` family of methods +/// have been stabilized and renamed from `flatten` to `as_flattened`. +/// +/// This creates an issue for as long as the MSRV is < 1.80, as the same functionality is provided +/// by different methods depending on the compiler version. +/// +/// This extension trait solves this by abstracting `as_flatten` and calling the correct method +/// depending on the Rust version. +/// +/// This trait can be removed once the MSRV passes 1.80. +/// +/// [`as_flattened`]: slice::as_flattened +/// [`as_flattened_mut`]: slice::as_flattened_mut +#[cfg(not(CONFIG_RUSTC_HAS_SLICE_AS_FLATTENED))] +pub trait AsFlattened { + /// Takes a `&[[T; N]]` and flattens it to a `&[T]`. + /// + /// This is an portable layer on top of [`as_flattened`]; see its documentation for details. + /// + /// [`as_flattened`]: slice::as_flattened + fn as_flattened(&self) -> &[T]; + + /// Takes a `&mut [[T; N]]` and flattens it to a `&mut [T]`. + /// + /// This is an portable layer on top of [`as_flattened_mut`]; see its documentation for details. + /// + /// [`as_flattened_mut`]: slice::as_flattened_mut + fn as_flattened_mut(&mut self) -> &mut [T]; +} + +#[cfg(not(CONFIG_RUSTC_HAS_SLICE_AS_FLATTENED))] +impl AsFlattened for [[T; N]] { + #[allow(clippy::incompatible_msrv)] + fn as_flattened(&self) -> &[T] { + self.flatten() + } + + #[allow(clippy::incompatible_msrv)] + fn as_flattened_mut(&mut self) -> &mut [T] { + self.flatten_mut() + } +} -- cgit v1.2.3 From 57dc2ea0b7bdb828c5d966d9135c28fe854933a4 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Wed, 19 Nov 2025 19:51:25 +0100 Subject: rust: slice: fix broken intra-doc links In older versions of Rust, the compiler doesn't know about the newer `as_flattened*` methods, thus `rustdoc` complains about the intra-doc links, e.g. error: unresolved link to `slice::as_flattened` --> rust/kernel/slice.rs:19:23 | 19 | /// [`as_flattened`]: slice::as_flattened | ^^^^^^^^^^^^^^^^^^^ the primitive type `slice` has no associated item named `as_flattened` | = note: `-D rustdoc::broken-intra-doc-links` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(rustdoc::broken_intra_doc_links)]` Thus fix them by using an URL instead. Fixes: 88622323dde3 ("rust: enable slice_flatten feature and provide it through an extension trait") Signed-off-by: Miguel Ojeda Reviewed-by: Alexandre Courbot Reviewed-by: Alice Ryhl Link: https://patch.msgid.link/20251119185125.1411151-1-ojeda@kernel.org Signed-off-by: Alice Ryhl --- rust/kernel/slice.rs | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'rust/kernel/slice.rs') diff --git a/rust/kernel/slice.rs b/rust/kernel/slice.rs index 6ca91a4fd1f2..ca2cde135061 100644 --- a/rust/kernel/slice.rs +++ b/rust/kernel/slice.rs @@ -16,22 +16,22 @@ /// /// This trait can be removed once the MSRV passes 1.80. /// -/// [`as_flattened`]: slice::as_flattened -/// [`as_flattened_mut`]: slice::as_flattened_mut +/// [`as_flattened`]: https://doc.rust-lang.org/std/primitive.slice.html#method.as_flattened +/// [`as_flattened_mut`]: https://doc.rust-lang.org/std/primitive.slice.html#method.as_flattened_mut #[cfg(not(CONFIG_RUSTC_HAS_SLICE_AS_FLATTENED))] pub trait AsFlattened { /// Takes a `&[[T; N]]` and flattens it to a `&[T]`. /// /// This is an portable layer on top of [`as_flattened`]; see its documentation for details. /// - /// [`as_flattened`]: slice::as_flattened + /// [`as_flattened`]: https://doc.rust-lang.org/std/primitive.slice.html#method.as_flattened fn as_flattened(&self) -> &[T]; /// Takes a `&mut [[T; N]]` and flattens it to a `&mut [T]`. /// /// This is an portable layer on top of [`as_flattened_mut`]; see its documentation for details. /// - /// [`as_flattened_mut`]: slice::as_flattened_mut + /// [`as_flattened_mut`]: https://doc.rust-lang.org/std/primitive.slice.html#method.as_flattened_mut fn as_flattened_mut(&mut self) -> &mut [T]; } -- cgit v1.2.3