Re: [PATCH v2 5/5] rust: enable `clippy::as_underscore` lint

[Benno Lossin <benno.lossin@proton.me>]

On Wed Mar 12, 2025 at 10:10 PM CET, Tamir Duberstein wrote:
> On Wed, Mar 12, 2025 at 5:04 PM Tamir Duberstein <tamird@gmail.com> wrote:
>>
>> On Wed, Mar 12, 2025 at 5:01 PM Benno Lossin <benno.lossin@proton.me> wrote:
>> > Always enable the features, we have `allow(stable_features)` for this
>> > reason (then you don't have to do this dance with checking if it's
>> > already stable or not :)
>>
>> It's not so simple. In rustc < 1.84.0 the lints *and* the strict
>> provenance APIs are behind `feature(strict_provenance)`. In rustc >=
>> 1.84.0 the lints are behind `feature(strict_provenance_lints)`. So you
>> need to read the config to learn that you need to enable
>> `feature(strict_provenance_lints)`.

I see... And `strict_provenance_lints` doesn't exist in <1.84? That's a
bit of a bummer...

But I guess we could have this config option (in `init/Kconfig`):

    config RUSTC_HAS_STRICT_PROVENANCE
	    def_bool RUSTC_VERSION >= 108400

and then do this in `lib.rs`:

    #![cfg_attr(CONFIG_RUSTC_HAS_STRICT_PROVENANCE, feature(strict_provenance_lints))]

> Actually this isn't even the only problem. It seems that
> `-Astable_features` doesn't affect features enabled on the command
> line at all:
>
> error[E0725]: the feature `strict_provenance` is not in the list of
> allowed features
>  --> <crate attribute>:1:9
>   |
> 1 | feature(strict_provenance)
>   |         ^^^^^^^^^^^^^^^^^

That's because you need to append the feature to `rust_allowed_features`
in `scripts/Makefile.build` (AFAIK).

---
Cheers,
Benno