[PATCH] rust: soc: silence clippy warning with rustc >= 1.88

[Alexandre Courbot]

The `clippy::unwrap_or_default` warning triggers on
`rust/kernel/soc.rs` since rustc 1.88:

    warning: use of `unwrap_or` to construct default value
      --> ../rust/kernel/soc.rs:66:10
      |
   66 |         .unwrap_or(core::ptr::null())
      |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `unwrap_or_default()`
      |
      = help: for further information visit https://rust-lang.github.io/rust-clippy/rust-1.96.0/index.html#unwrap_or_default
      = note: `-W clippy::unwrap-or-default` implied by `-W clippy::all`
      = help: to override `-W clippy::all` add `#[allow(clippy::unwrap_or_default)]`

Since our current MSRV is 1.85, we cannot fix the warning as
recommended, so allow the lint on the `cstring_to_c` function instead.

Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
---
 rust/kernel/soc.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/rust/kernel/soc.rs b/rust/kernel/soc.rs
index 0d6a36c83cb6..7998962560f8 100644
--- a/rust/kernel/soc.rs
+++ b/rust/kernel/soc.rs
@@ -60,6 +60,9 @@ struct BuiltAttributes {
     inner: Opaque<bindings::soc_device_attribute>,
 }
 
+// `unwrap_or_default()` on a raw pointer requires `Default for *const T`, which is stable since
+// Rust 1.88. Remove when the MSRV allows it.
+#[allow(clippy::unwrap_or_default)]
 fn cstring_to_c(mcs: &Option<CString>) -> *const kernel::ffi::c_char {
     mcs.as_ref()
         .map(|cs| cs.as_char_ptr())

---
base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482
change-id: 20260707-soc_unwrap_or-ed37e674a759

Best regards,
--  
Alexandre Courbot <acourbot@xxxxxxxxxx>