[PATCH v4 2/6] rust: str: provide const fn as_bytes() for BStr

[Danilo Krummrich <dakr@xxxxxxxxxx>]

`BStr` already dereference to `&[u8]` through the `Deref` trait,
however, this can't be called from const context.

Hence, provide a separate const function for this.

This is used in subsequent nova-core patches.

Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
---
 rust/kernel/str.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 28e2201604d6..71e8a819016d 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -31,6 +31,12 @@ pub const fn from_bytes(bytes: &[u8]) -> &Self {
         // SAFETY: `BStr` is transparent to `[u8]`.
         unsafe { &*(bytes as *const [u8] as *const BStr) }
     }
+
+    /// Same as `self.deref()`, but works in const context.
+    #[inline]
+    pub const fn as_bytes(&self) -> &[u8] {
+        &self.0
+    }
 }
 
 impl fmt::Display for BStr {
-- 
2.48.1