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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 <ojeda@kernel.org> Link: https://lore.kernel.org/all/CANiq72kK4pG=O35NwxPNoTO17oRcg1yfGcvr3==Fi4edr+sfmw@mail.gmail.com/ Acked-by: Danilo Krummrich <dakr@kernel.org> Acked-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com> Message-ID: <20251110-gsp_boot-v9-8-8ae4058e3c0e@nvidia.com> Message-ID: <20251104-b4-as-flattened-v3-1-6cb9c26b45cd@nvidia.com>
50 lines
1.7 KiB
Rust
50 lines
1.7 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
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//! Additional (and temporary) slice helpers.
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/// Extension trait providing a portable version of [`as_flattened`] and
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/// [`as_flattened_mut`].
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///
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/// In Rust 1.80, the previously unstable `slice::flatten` family of methods
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/// have been stabilized and renamed from `flatten` to `as_flattened`.
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///
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/// This creates an issue for as long as the MSRV is < 1.80, as the same functionality is provided
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/// by different methods depending on the compiler version.
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///
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/// This extension trait solves this by abstracting `as_flatten` and calling the correct method
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/// depending on the Rust version.
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///
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/// This trait can be removed once the MSRV passes 1.80.
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///
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/// [`as_flattened`]: slice::as_flattened
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/// [`as_flattened_mut`]: slice::as_flattened_mut
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#[cfg(not(CONFIG_RUSTC_HAS_SLICE_AS_FLATTENED))]
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pub trait AsFlattened<T> {
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/// Takes a `&[[T; N]]` and flattens it to a `&[T]`.
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///
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/// This is an portable layer on top of [`as_flattened`]; see its documentation for details.
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///
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/// [`as_flattened`]: slice::as_flattened
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fn as_flattened(&self) -> &[T];
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/// Takes a `&mut [[T; N]]` and flattens it to a `&mut [T]`.
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///
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/// This is an portable layer on top of [`as_flattened_mut`]; see its documentation for details.
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///
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/// [`as_flattened_mut`]: slice::as_flattened_mut
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fn as_flattened_mut(&mut self) -> &mut [T];
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}
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#[cfg(not(CONFIG_RUSTC_HAS_SLICE_AS_FLATTENED))]
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impl<T, const N: usize> AsFlattened<T> for [[T; N]] {
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#[allow(clippy::incompatible_msrv)]
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fn as_flattened(&self) -> &[T] {
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self.flatten()
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}
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#[allow(clippy::incompatible_msrv)]
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fn as_flattened_mut(&mut self) -> &mut [T] {
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self.flatten_mut()
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}
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}
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