1 files changed, 49 insertions, 0 deletions
diff --git a/rust/kernel/slice.rs b/rust/kernel/slice.rs
new file mode 100644
index 000000000000..ca2cde135061
--- /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`]: 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<T> {
+    /// 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`]: 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`]: https://doc.rust-lang.org/std/primitive.slice.html#method.as_flattened_mut
+    fn as_flattened_mut(&mut self) -> &mut [T];
+}
+
+#[cfg(not(CONFIG_RUSTC_HAS_SLICE_AS_FLATTENED))]
+impl<T, const N: usize> AsFlattened<T> 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()
+    }
+}