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

[Alice Ryhl <aliceryhl@google.com>]

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;
 }
 
 /// Prints a KUnit info-level message.
@@ -39,6 +42,9 @@ pub fn info(args: fmt::Arguments<'_>) {
             core::ptr::from_ref(&args).cast::<c_void>(),
         );
     }
+
+    #[cfg(not(CONFIG_PRINTK))]
+    let _ = args;
 }
 
 /// Asserts that a boolean expression is `true` at runtime.