From a6007cf555e5946bcbfafe93a6468c329078acd8 Mon Sep 17 00:00:00 2001
From: Miguel Ojeda <ojeda@kernel.org>
Date: Mon, 31 Mar 2025 22:17:33 +0200
Subject: [PATCH 1/2] alloc: restrict `impl ZeroableOption` for `Box` to `T:
 Sized`

Similar to what was done for `Zeroable<NonNull<T>>` in commit 9caa3507c926
("last docs changes and zeroable unsized pointer fixes"), the latest Rust
documentation [1] says it guarantees that `transmute::<_, Option<T>>([0u8;
size_of::<T>()])` is sound and produces `Option::<T>::None` only in some
cases. In particular, it says:

    `Box<U>` (specifically, only `Box<U, Global>`) when `U: Sized`

Thus restrict the `impl` to `Sized`, and use similar wording as in that
commit too.

Link: https://doc.rust-lang.org/stable/std/option/index.html#representation [1]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 src/alloc.rs | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/alloc.rs b/src/alloc.rs
index e16baa3b..5017f574 100644
--- a/src/alloc.rs
+++ b/src/alloc.rs
@@ -17,11 +17,9 @@ use crate::{
 
 pub extern crate alloc;
 
-// SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee).
-//
-// In this case we are allowed to use `T: ?Sized`, since all zeros is the `None` variant and there
-// is no problem with a VTABLE pointer being null.
-unsafe impl<T: ?Sized> ZeroableOption for Box<T> {}
+// SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee:
+// <https://doc.rust-lang.org/stable/std/option/index.html#representation>).
+unsafe impl<T> ZeroableOption for Box<T> {}
 
 /// Smart pointer that can initialize memory in-place.
 pub trait InPlaceInit<T>: Sized {

From dd230d61bf0538281072fbff4bb71efc58f3420c Mon Sep 17 00:00:00 2001
From: Miguel Ojeda <ojeda@kernel.org>
Date: Tue, 1 Apr 2025 21:56:27 +0200
Subject: [PATCH 2/2] Use Markdown autolinks in Rust comments

It allows, for instance, kitty to pick it up as links properly [1].

Suggested-by: Benno Lossin <benno.lossin@proton.me>
Link: https://github.com/Rust-for-Linux/pin-init/pull/32#discussion_r2023103712 [1]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 examples/pthread_mutex.rs | 2 +-
 src/lib.rs                | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/examples/pthread_mutex.rs b/examples/pthread_mutex.rs
index 9164298c..5ac22f18 100644
--- a/examples/pthread_mutex.rs
+++ b/examples/pthread_mutex.rs
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: Apache-2.0 OR MIT
 
-// inspired by https://github.com/nbdd0121/pin-init/blob/trunk/examples/pthread_mutex.rs
+// inspired by <https://github.com/nbdd0121/pin-init/blob/trunk/examples/pthread_mutex.rs>
 #![allow(clippy::undocumented_unsafe_blocks)]
 #![cfg_attr(feature = "alloc", feature(allocator_api))]
 #[cfg(not(windows))]
diff --git a/src/lib.rs b/src/lib.rs
index 05c44514..0806c689 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1447,7 +1447,7 @@ impl_zeroable! {
     {<T: ?Sized + Zeroable>} UnsafeCell<T>,
 
     // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee:
-    // https://doc.rust-lang.org/stable/std/option/index.html#representation).
+    // <https://doc.rust-lang.org/stable/std/option/index.html#representation>).
     Option<NonZeroU8>, Option<NonZeroU16>, Option<NonZeroU32>, Option<NonZeroU64>,
     Option<NonZeroU128>, Option<NonZeroUsize>,
     Option<NonZeroI8>, Option<NonZeroI16>, Option<NonZeroI32>, Option<NonZeroI64>,