From b4f07baf81c121093aa8e62b2ac5e2e9b8cbe9fd Mon Sep 17 00:00:00 2001
From: Semih Buyukgungor <buyukgungorsemih@gmail.com>
Date: Mon, 4 Nov 2024 14:01:45 +0300
Subject: [PATCH] Update unsafe trait example to zerocopy version 0.8 (#2434)

Zerocopy crate version 0.8 introduced changes to its API, which caused
the example code to break.
https://github.com/google/zerocopy/discussions/1680
> AsBytes ->
[IntoBytes](https://docs.rs/zerocopy/0.8.*/zerocopy/trait.IntoBytes.html)

---------

Co-authored-by: Martin Geisler <martin@geisler.net>
---
 src/unsafe-rust/unsafe-traits.md | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/src/unsafe-rust/unsafe-traits.md b/src/unsafe-rust/unsafe-traits.md
index f2ccdd2a..ba279b13 100644
--- a/src/unsafe-rust/unsafe-traits.md
+++ b/src/unsafe-rust/unsafe-traits.md
@@ -8,28 +8,23 @@ Like with functions, you can mark a trait as `unsafe` if the implementation must
 guarantee particular conditions to avoid undefined behaviour.
 
 For example, the `zerocopy` crate has an unsafe trait that looks
-[something like this](https://docs.rs/zerocopy/latest/zerocopy/trait.AsBytes.html):
+[something like this](https://docs.rs/zerocopy/latest/zerocopy/trait.IntoBytes.html):
 
 ```rust,editable
-use std::mem::size_of_val;
-use std::slice;
+use std::{mem, slice};
 
 /// ...
 /// # Safety
 /// The type must have a defined representation and no padding.
-pub unsafe trait AsBytes {
+pub unsafe trait IntoBytes {
     fn as_bytes(&self) -> &[u8] {
-        unsafe {
-            slice::from_raw_parts(
-                self as *const Self as *const u8,
-                size_of_val(self),
-            )
-        }
+        let len = mem::size_of_val(self);
+        unsafe { slice::from_raw_parts((&raw const self).cast::<u8>(), len) }
     }
 }
 
 // SAFETY: `u32` has a defined representation and no padding.
-unsafe impl AsBytes for u32 {}
+unsafe impl IntoBytes for u32 {}
 ```
 
 <details>
@@ -37,7 +32,7 @@ unsafe impl AsBytes for u32 {}
 There should be a `# Safety` section on the Rustdoc for the trait explaining the
 requirements for the trait to be safely implemented.
 
-The actual safety section for `AsBytes` is rather longer and more complicated.
+The actual safety section for `IntoBytes` is rather longer and more complicated.
 
 The built-in `Send` and `Sync` traits are unsafe.