rust: pin-init: cleanup `Zeroable` and `ZeroableOptions`

Place definitions and implementations (incl. macro invocations) of
the `Zeroable` trait first in the relevant section of `src/lib.rs`,
followed by the ZeroableOption trait and its implementations.

Rename `impl_non_zero_int_zeroable_option` to `impl_zeroable_option`
for consistency.

This commit should not introduce any functional changes.

Signed-off-by: Mohamad Alsadhan <mo@sdhn.cc>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260428-pin-init-sync-v1-3-07f9bd3859fb@garyguo.net
Signed-off-by: Gary Guo <gary@garyguo.net>

diff --git a/rust/pin-init/src/lib.rs b/rust/pin-init/src/lib.rs
index 4f50994bd2687ec787fe3c5c5c63a08bec9e2627..e34c9bdb88c39ea5d28de29846208b9337a00f84 100644 (file)
--- a/rust/pin-init/src/lib.rs
+++ b/rust/pin-init/src/lib.rs
@@ -1517,27 +1517,6 @@ pub unsafe trait Zeroable {
     }
 }
 
-/// Marker trait for types that allow `Option<Self>` to be set to all zeroes in order to write
-/// `None` to that location.
-///
-/// # Safety
-///
-/// The implementer needs to ensure that `unsafe impl Zeroable for Option<Self> {}` is sound.
-pub unsafe trait ZeroableOption {}
-
-// SAFETY: by the safety requirement of `ZeroableOption`, this is valid.
-unsafe impl<T: ZeroableOption> Zeroable for Option<T> {}
-
-// SAFETY: `Option<&T>` is part of the option layout optimization guarantee:
-// <https://doc.rust-lang.org/stable/std/option/index.html#representation>.
-unsafe impl<T> ZeroableOption for &T {}
-// SAFETY: `Option<&mut T>` is part of the option layout optimization guarantee:
-// <https://doc.rust-lang.org/stable/std/option/index.html#representation>.
-unsafe impl<T> ZeroableOption for &mut T {}
-// SAFETY: `Option<NonNull<T>>` is part of the option layout optimization guarantee:
-// <https://doc.rust-lang.org/stable/std/option/index.html#representation>.
-unsafe impl<T> ZeroableOption for NonNull<T> {}
-
 /// Create an initializer for a zeroed `T`.
 ///
 /// The returned initializer will write `0x00` to every byte of the given `slot`.
@@ -1643,6 +1622,27 @@ macro_rules! impl_tuple_zeroable {
 
 impl_tuple_zeroable!(A, B, C, D, E, F, G, H, I, J);
 
+/// Marker trait for types that allow `Option<Self>` to be set to all zeroes in order to write
+/// `None` to that location.
+///
+/// # Safety
+///
+/// The implementer needs to ensure that `unsafe impl Zeroable for Option<Self> {}` is sound.
+pub unsafe trait ZeroableOption {}
+
+// SAFETY: by the safety requirement of `ZeroableOption`, this is valid.
+unsafe impl<T: ZeroableOption> Zeroable for Option<T> {}
+
+// SAFETY: `Option<&T>` is part of the option layout optimization guarantee:
+// <https://doc.rust-lang.org/stable/std/option/index.html#representation>.
+unsafe impl<T> ZeroableOption for &T {}
+// SAFETY: `Option<&mut T>` is part of the option layout optimization guarantee:
+// <https://doc.rust-lang.org/stable/std/option/index.html#representation>.
+unsafe impl<T> ZeroableOption for &mut T {}
+// SAFETY: `Option<NonNull<T>>` is part of the option layout optimization guarantee:
+// <https://doc.rust-lang.org/stable/std/option/index.html#representation>.
+unsafe impl<T> ZeroableOption for NonNull<T> {}
+
 macro_rules! impl_fn_zeroable_option {
     ([$($abi:literal),* $(,)?] $args:tt) => {
         $(impl_fn_zeroable_option!({extern $abi} $args);)*
@@ -1668,14 +1668,14 @@ macro_rules! impl_fn_zeroable_option {
 
 impl_fn_zeroable_option!(["Rust", "C"] { A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U });
 
-macro_rules! impl_non_zero_int_zeroable_option {
+macro_rules! impl_zeroable_option {
     ($($int:ty),* $(,)?) => {
         // SAFETY: Safety comment written in the macro invocation.
         $(unsafe impl ZeroableOption for $int {})*
     };
 }
 
-impl_non_zero_int_zeroable_option! {
+impl_zeroable_option! {
     // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee:
     // <https://doc.rust-lang.org/stable/std/option/index.html#representation>).
     NonZeroU8, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU128, NonZeroUsize,