Re: [PATCH v1] tools build: Fix feature test for rust compiler

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Wed, Feb 11, 2026 at 10:58:01AM +0100, Dmitrii Dolgov wrote:
> Currently a dummy rust code is compiled to detect if the rust feature
> could be enabled. It turns out that in this case rust emits a dependency
> file without any external references:
> 
>     /perf/feature/test-rust.d: test-rust.rs
> 
>     /perf/feature/test-rust.bin: test-rust.rs
> 
>     test-rust.rs:
> 
> This can lead to a situation, when rustc was removed after a successful build,
> but the build process still thinks it's there and the feature is enabled on
> subsequent runs.
> 
> Instead simply check the compiler presence to detect the feature, as
> suggested by Arnaldo Carvalho de Melo. This way no actual test-rust.bin
> will be created, meaning the feature check will not be cached and always
> performed. That's exactly what we want, and the overhead of doing this
> every time is minimal.
> 
> Tested with multiple rounds of install/remove of the rust package.

Yeah, seems to work, applied.

- Arnaldo