[PATCH] rust: kunit: use C-string literals to clean warning

[Miguel Ojeda <ojeda@kernel.org>]

Starting with upstream Rust commit a5e3a3f9b6bd ("move
`manual_c_str_literals` to complexity"), to be released in Rust 1.83.0
[1], Clippy now warns on `manual_c_str_literals` by default, e.g.:

    error: manually constructing a nul-terminated string
      --> rust/kernel/kunit.rs:21:13
       |
    21 |             b"\x013%pA\0".as_ptr() as _,
       |             ^^^^^^^^^^^^^ help: use a `c""` literal: `c"\x013%pA"`
       |
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_c_str_literals
       = note: `-D clippy::manual-c-str-literals` implied by `-D warnings`
       = help: to override `-D warnings` add `#[allow(clippy::manual_c_str_literals)]`

Apply the suggestion to clean up the warnings.

Link: https://github.com/rust-lang/rust-clippy/pull/13263 [1]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
The cast could also be cleaned up, but that is already done in Gary's
FFI series, so I didn't include another patch.

C-string literals are available since Rust 1.77.0, which is higher than
our minimum version, but LTS kernels do not have Rust 1.77.0. But
perhaps for these is not a big deal, and we could also enable
`feature(c_str_literals)` instead.

 rust/kernel/kunit.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
index 0ba77276ae7e..824da0e9738a 100644
--- a/rust/kernel/kunit.rs
+++ b/rust/kernel/kunit.rs
@@ -18,7 +18,7 @@ pub fn err(args: fmt::Arguments<'_>) {
     #[cfg(CONFIG_PRINTK)]
     unsafe {
         bindings::_printk(
-            b"\x013%pA\0".as_ptr() as _,
+            c"\x013%pA".as_ptr() as _,
             &args as *const _ as *const c_void,
         );
     }
@@ -34,7 +34,7 @@ pub fn info(args: fmt::Arguments<'_>) {
     #[cfg(CONFIG_PRINTK)]
     unsafe {
         bindings::_printk(
-            b"\x016%pA\0".as_ptr() as _,
+            c"\x016%pA".as_ptr() as _,
             &args as *const _ as *const c_void,
         );
     }

base-commit: 570172569238c66a482ec3eb5d766cc9cf255f69
--
2.46.2