[PATCH 6.12 197/265] rust: kunit: fix warning when !CONFIG_PRINTK

Greg Kroah-Hartman
2026-03-12T20:24:38Z

From: Alexandre Courbot <acourbot@nvidia.com>

[ Upstream commit 7dd34dfc8dfa92a7244242098110388367996ac3 ]

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 adding a no-op assignment using `args` when `CONFIG_PRINTK`
is not set.

Fixes: a66d733da801 ("rust: support running Rust documentation tests as KUnit ones")
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: David Gow <david@davidgow.net>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
rust/kernel/kunit.rs | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
index 824da0e9738a0..7b38fca9f2429 100644
--- a/rust/kernel/kunit.rs
+++ b/rust/kernel/kunit.rs
@@ -13,6 +13,10 @@
/// Public but hidden since it should only be used from KUnit generated code.
#[doc(hidden)]
pub fn err(args: fmt::Arguments<'_>) {
+ // `args` is unused if `CONFIG_PRINTK` is not set - this avoids a build-time warning.
+ #[cfg(not(CONFIG_PRINTK))]
+ let _ = args;
+
// SAFETY: The format string is null-terminated and the `%pA` specifier matches the argument we
// are passing.
#[cfg(CONFIG_PRINTK)]
@@ -29,6 +33,10 @@ pub fn err(args: fmt::Arguments<'_>) {
/// Public but hidden since it should only be used from KUnit generated code.
#[doc(hidden)]
pub fn info(args: fmt::Arguments<'_>) {
+ // `args` is unused if `CONFIG_PRINTK` is not set - this avoids a build-time warning.
+ #[cfg(not(CONFIG_PRINTK))]
+ let _ = args;
+
// SAFETY: The format string is null-terminated and the `%pA` specifier matches the argument we
// are passing.
#[cfg(CONFIG_PRINTK)]
--
2.51.0