rust: kbuild: remove feature(...)s that are now stable

Now that the Rust minimum version is 1.85.0, there is no need to enable
certain features that are stable.

Thus clean them up.

Reviewed-by: Tamir Duberstein <tamird@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260405235309.418950-13-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

rust/Makefile

@@ -86,10 +86,8 @@ proc_macro2-cfgs := \
     wrap_proc_macro \
     $(if $(call rustc-min-version,108800),proc_macro_span_file proc_macro_span_location)
 
-# Stable since Rust 1.79.0: `feature(proc_macro_byte_character,proc_macro_c_str_literals)`.
 proc_macro2-flags := \
     --cap-lints=allow \
-    -Zcrate-attr='feature(proc_macro_byte_character,proc_macro_c_str_literals)' \
     $(call cfgs-to-flags,$(proc_macro2-cfgs))
 
 quote-cfgs := \

rust/kernel/lib.rs

@@ -16,27 +16,6 @@
 // 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(generic_nonzero)]
-#![feature(inline_const)]
-#![feature(pointer_is_aligned)]
-//
-// Stable since Rust 1.80.0.
-#![feature(slice_flatten)]
-//
-// Stable since Rust 1.81.0.
-#![feature(lint_reasons)]
-//
-// Stable since Rust 1.82.0.
-#![feature(raw_ref_op)]
-//
-// Stable since Rust 1.83.0.
-#![feature(const_maybe_uninit_as_mut_ptr)]
-#![feature(const_mut_refs)]
-#![feature(const_option)]
-#![feature(const_ptr_write)]
-#![feature(const_refs_to_cell)]
-//
 // Expected to become stable.
 #![feature(arbitrary_self_types)]
 #![feature(derive_coerce_pointee)]

scripts/Makefile.build

@@ -310,17 +310,13 @@ $(obj)/%.lst: $(obj)/%.c FORCE
 
 # The features in this list are the ones allowed for non-`rust/` code.
 #
-#   - Stable since Rust 1.79.0: `feature(inline_const)`.
-#   - Stable since Rust 1.81.0: `feature(lint_reasons)`.
-#   - Stable since Rust 1.82.0: `feature(asm_const)`,
-#     `feature(offset_of_nested)`, `feature(raw_ref_op)`.
 #   - Stable since Rust 1.87.0: `feature(asm_goto)`.
 #   - Expected to become stable: `feature(arbitrary_self_types)`.
 #   - To be determined: `feature(used_with_arg)`.
 #
 # 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,inline_const,lint_reasons,offset_of_nested,raw_ref_op,used_with_arg
+rust_allowed_features := arbitrary_self_types,asm_goto,used_with_arg
 
 # `--out-dir` is required to avoid temporaries being created by `rustc` in the
 # current working directory, which may be not accessible in the out-of-tree