rust: kbuild: run Clippy for `rusttest` code

Running Clippy for `rusttest` code is useful to catch issues there too,
even if the code is not as critical. In the future, this code may also
run in kernelspace and could be copy-pasted. Thus it is useful to keep
it under the same standards. For instance, it will now make us add
`// SAFETY` comments.

It also makes everything more consistent.

Thus clean the few issues spotted by Clippy and start running it.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20241123180639.260191-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 0f2765463dc8..5dfddb0d41d9 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -522,6 +522,7 @@ macro_rules! c_str {
 }
 
 #[cfg(test)]
+#[expect(clippy::items_after_test_module)]
 mod tests {
     use super::*;
 
@@ -547,7 +548,7 @@ mod tests {
         })
     }
 
-    const ALL_ASCII_CHARS: &'static str =
+    const ALL_ASCII_CHARS: &str =
         "\\x01\\x02\\x03\\x04\\x05\\x06\\x07\\x08\\x09\\x0a\\x0b\\x0c\\x0d\\x0e\\x0f\
         \\x10\\x11\\x12\\x13\\x14\\x15\\x16\\x17\\x18\\x19\\x1a\\x1b\\x1c\\x1d\\x1e\\x1f \
         !\"#$%&'()*+,-./0123456789:;<=>?@\
@@ -581,6 +582,7 @@ mod tests {
     fn test_cstr_as_str_unchecked() {
         let good_bytes = b"\xf0\x9f\x90\xA7\0";
         let checked_cstr = CStr::from_bytes_with_nul(good_bytes).unwrap();
+        // SAFETY: The contents come from a string literal which contains valid UTF-8.
         let unchecked_str = unsafe { checked_cstr.as_str_unchecked() };
         assert_eq!(unchecked_str, "🐧");
     }