[PATCH v2 32/33] rust: kbuild: support global per-version flags

[Nicolas Schier]

On Mon, Apr 06, 2026 at 01:53:08AM +0200, Miguel Ojeda wrote:
> Sometimes it is useful to gate global Rust flags per compiler version.
> For instance, we may want to disable a lint that has false positives in
> a single version [1].
> 
> We already had helpers like `rustc-min-version` for that, which we use
> elsewhere, but we cannot currently use them for `rust_common_flags`,
> which contains the global flags for all Rust code (kernel and host),
> because `rustc-min-version` depends on `CONFIG_RUSTC_VERSION`, which
> does not exist when `rust_common_flags` is defined.
> 
> Thus, to support that, introduce `rust_common_flags_per_version`,
> defined after the `include/config/auto.conf` inclusion (where
> `CONFIG_RUSTC_VERSION` becomes available), and append it to
> `rust_common_flags`, `KBUILD_HOSTRUSTFLAGS` and `KBUILD_RUSTFLAGS`.
> 
> In addition, move the expansion of `HOSTRUSTFLAGS` to the same place,
> so that users can also override per-version flags [2].
> 
> Link: https://lore.kernel.org/rust-for-linux/CANiq72mWdFU11GcCZRchzhy0Gi1QZShvZtyRkHV2O+WA2uTdVQ@mail.gmail.com/ [1]
> Link: https://lore.kernel.org/rust-for-linux/CANiq72mTaA2tjhkLKf0-2hrrrt9rxWPgy6SfNSbponbGOegQvA@mail.gmail.com/ [2]
> Link: https://patch.msgid.link/20260307170929.153892-1-ojeda@kernel.org
> Signed-off-by: Miguel Ojeda <ojeda at kernel.org>
> ---
>  Makefile | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 

Acked-by: Nicolas Schier <nsc at kernel.org>

-- 
Nicolas