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rust: pin-init: extend impl_zeroable_option macro to handle generics

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Improve impl_zeroable_option macro to handle generic impls for types
like `&T`, `&mut T`, `NonNull<T>`, and others (for which `Option<T>`
is guaranteed to be zeroable) with similar approach to
`impl_zeroable`.

Also, update old declarations to use generics e.g. `NonZeroU8` to
`NonZero<u8>`.

Signed-off-by: Mohamad Alsadhan <mo@sdhn.cc>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260428-pin-init-sync-v1-4-07f9bd3859fb@garyguo.net
Signed-off-by: Gary Guo <gary@garyguo.net>
This commit is contained in:
Mohamad Alsadhan
2026-04-28 14:10:53 +01:00
committed by Gary Guo
parent 04828a538d
commit de54c2cb05
1 changed files with 14 additions and 15 deletions
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29
rust/pin-init/src/lib.rs
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@@ -1633,16 +1633,6 @@ 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} $args);)*
@@ -1669,17 +1659,26 @@ unsafe impl<$ret, $($rest),*> ZeroableOption for $($prefix)* fn($($rest),*) -> $
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_zeroable_option {
($($int:ty),* $(,)?) => {
// SAFETY: Safety comment written in the macro invocation.
$(unsafe impl ZeroableOption for $int {})*
($($({$($generics:tt)*})? $t:ty, )*) => {
// SAFETY: Safety comments written in the macro invocation.
$(unsafe impl$($($generics)*)? ZeroableOption for $t {})*
};
}
impl_zeroable_option! {
// SAFETY: `Option<&T>` is part of the option layout optimization guarantee:
// <https://doc.rust-lang.org/stable/std/option/index.html#representation>.
{<T: ?Sized>} &T,
// SAFETY: `Option<&mut T>` is part of the option layout optimization guarantee:
// <https://doc.rust-lang.org/stable/std/option/index.html#representation>.
{<T: ?Sized>} &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>.
{<T: ?Sized>} NonNull<T>,
// 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,
NonZeroI8, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI128, NonZeroIsize,
NonZero<u8>, NonZero<u16>, NonZero<u32>, NonZero<u64>, NonZero<u128>, NonZero<usize>,
NonZero<i8>, NonZero<i16>, NonZero<i32>, NonZero<i64>, NonZero<i128>, NonZero<isize>,
}
/// This trait allows creating an instance of `Self` which contains exactly one