Re: [PATCH] rust: kunit: fix warning when !CONFIG_PRINTK

[Alice Ryhl <aliceryhl@google.com>]

On Tue, Feb 24, 2026 at 07:49:45AM +0000, Alice Ryhl wrote:
> On Tue, Feb 24, 2026 at 04:45:30PM +0900, Alexandre Courbot wrote:
> > If `CONFIG_PRINTK` is not set, then the following warnings are issued
> > during build:
> > 
> >   warning: unused variable: `args`
> >     --> ../rust/kernel/kunit.rs:16:12
> >     |
> >   16 | pub fn err(args: fmt::Arguments<'_>) {
> >     |            ^^^^ help: if this is intentional, prefix it with an underscore: `_args`
> >     |
> >     = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
> > 
> >   warning: unused variable: `args`
> >     --> ../rust/kernel/kunit.rs:32:13
> >     |
> >   32 | pub fn info(args: fmt::Arguments<'_>) {
> >     |             ^^^^ help: if this is intentional, prefix it with an underscore: `_args`
> > 
> > Fix this by allowing unused variables on these methods for this
> > (arguably rare) case.
> > 
> > Fixes: a66d733da801 ("rust: support running Rust documentation tests as KUnit ones")
> > Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
> 
> I think this would be a better fix:
> 
> diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
> index f93f24a60bdd..dbf3c62ffa09 100644
> --- a/rust/kernel/kunit.rs
> +++ b/rust/kernel/kunit.rs
> @@ -23,6 +23,9 @@ pub fn err(args: fmt::Arguments<'_>) {
>              core::ptr::from_ref(&args).cast::<c_void>(),
>          );
>      }
> +
> +    #[cfg(not(CONFIG_PRINTK))]
> +    let _ = args;

Or if a bare _ doesn't work, then:

	let _unused = args;

matching tracepoint.rs

Alice