From: Miguel Ojeda Date: Thu, 27 Mar 2025 21:13:02 +0000 (+0100) Subject: rust: clarify the language unstable features in use X-Git-Tag: v6.16-rc1~45^2~39 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b9b701fce49a448b1e046f7cda592fec2958e5cd;p=thirdparty%2Fkernel%2Fstable.git rust: clarify the language unstable features in use We track the details of which Rust features we use at our usual "live list" [1] (and its sub-lists), but in light of a discussion in the LWN article [2], it would help to clarify it in the source code. In particular, we are very close to rely only on stable Rust language-wise -- essentially only two language features remain (including the `kernel` crate). Thus add some details in both the feature list of the `kernel` crate as well as the list of allowed features. This does not over every single feature, and there are quite a few non-language features that we use too. To have the full picture, please refer to [1]. Link: https://github.com/Rust-for-Linux/linux/issues/2 [1] Link: https://lwn.net/Articles/1015409/ [2] Suggested-by: Andreas Hindborg Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250327211302.286313-1-ojeda@kernel.org [ Improved comments with suggestions from the list. - Miguel ] Signed-off-by: Miguel Ojeda --- diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index de07aadd1ff5f..28007be98fbad 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -12,20 +12,34 @@ //! do so first instead of bypassing this crate. #![no_std] -#![feature(arbitrary_self_types)] -#![cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, feature(derive_coerce_pointee))] -#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(coerce_unsized))] -#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(dispatch_from_dyn))] -#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(unsize))] +// +// Please see https://github.com/Rust-for-Linux/linux/issues/2 for details on +// the unstable features in use. +// +// Stable since Rust 1.79.0. #![feature(inline_const)] +// +// Stable since Rust 1.81.0. #![feature(lint_reasons)] -// Stable in Rust 1.82 +// +// Stable since Rust 1.82.0. #![feature(raw_ref_op)] -// Stable in Rust 1.83 +// +// Stable since Rust 1.83.0. #![feature(const_maybe_uninit_as_mut_ptr)] #![feature(const_mut_refs)] #![feature(const_ptr_write)] #![feature(const_refs_to_cell)] +// +// Expected to become stable. +#![feature(arbitrary_self_types)] +// +// `feature(derive_coerce_pointee)` is expected to become stable. Before Rust +// 1.84.0, it did not exist, so enable the predecessor features. +#![cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, feature(derive_coerce_pointee))] +#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(coerce_unsized))] +#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(dispatch_from_dyn))] +#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(unsize))] // Ensure conditional compilation based on the kernel configuration works; // otherwise we may silently break things like initcall handling. diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 13dcd86e74ca8..da2d720c964a8 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -222,6 +222,15 @@ $(obj)/%.lst: $(obj)/%.c FORCE # Compile Rust sources (.rs) # --------------------------------------------------------------------------- +# The features in this list are the ones allowed for non-`rust/` code. +# +# - Stable since Rust 1.81.0: `feature(lint_reasons)`. +# - Stable since Rust 1.82.0: `feature(asm_const)`, `feature(raw_ref_op)`. +# - Stable since Rust 1.87.0: `feature(asm_goto)`. +# - Expected to become stable: `feature(arbitrary_self_types)`. +# +# Please see https://github.com/Rust-for-Linux/linux/issues/2 for details on +# the unstable features in use. rust_allowed_features := asm_const,asm_goto,arbitrary_self_types,lint_reasons,raw_ref_op # `--out-dir` is required to avoid temporaries being created by `rustc` in the