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

[David Gow <david@davidgow.net>]

Le 24/02/2026 à 3:45 PM, 'Alexandre Courbot' via KUnit Development a écrit :
> 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>
> ---

Thanks. I think Alice's suggestion of adding a `let _ = args;` line, 
rather than disabling the unused_variables warning is probably the 
better way of handling this.

(That being said, those err() and info() functions probably need some 
reworking so that -- in the cases where it makes sense -- they call into 
the KUnit logging functions, not just printk.)

Cheers,
-- David

>   rust/kernel/kunit.rs | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
> index f93f24a60bdd..5da342f5c84a 100644
> --- a/rust/kernel/kunit.rs
> +++ b/rust/kernel/kunit.rs
> @@ -13,6 +13,8 @@
>   ///
>   /// Public but hidden since it should only be used from KUnit generated code.
>   #[doc(hidden)]
> +// `args` is unused if `CONFIG_PRINTK` is not set.
> +#[allow(unused_variables)]
>   pub fn err(args: fmt::Arguments<'_>) {
>       // SAFETY: The format string is null-terminated and the `%pA` specifier matches the argument we
>       // are passing.
> @@ -29,6 +31,8 @@ pub fn err(args: fmt::Arguments<'_>) {
>   ///
>   /// Public but hidden since it should only be used from KUnit generated code.
>   #[doc(hidden)]
> +// `args` is unused if `CONFIG_PRINTK` is not set.
> +#[allow(unused_variables)]
>   pub fn info(args: fmt::Arguments<'_>) {
>       // SAFETY: The format string is null-terminated and the `%pA` specifier matches the argument we
>       // are passing.
> 
> ---
> base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
> change-id: 20260224-unused_var_err-996d7ffa27c5
> 
> Best regards,