crates/bytemuck/src/zeroable_in_option.rs

use super::*;

// Note(Lokathor): This is the neat part!!
unsafe impl<T: ZeroableInOption> Zeroable for Option<T> {}

/// Trait for types which are [Zeroable](Zeroable) when wrapped in
/// [Option](core::option::Option).
///
/// ## Safety
///
/// * `Option<YourType>` must uphold the same invariants as
///   [Zeroable](Zeroable).
pub unsafe trait ZeroableInOption: Sized {}

unsafe impl ZeroableInOption for NonZeroI8 {}
unsafe impl ZeroableInOption for NonZeroI16 {}
unsafe impl ZeroableInOption for NonZeroI32 {}
unsafe impl ZeroableInOption for NonZeroI64 {}
unsafe impl ZeroableInOption for NonZeroI128 {}
unsafe impl ZeroableInOption for NonZeroIsize {}
unsafe impl ZeroableInOption for NonZeroU8 {}
unsafe impl ZeroableInOption for NonZeroU16 {}
unsafe impl ZeroableInOption for NonZeroU32 {}
unsafe impl ZeroableInOption for NonZeroU64 {}
unsafe impl ZeroableInOption for NonZeroU128 {}
unsafe impl ZeroableInOption for NonZeroUsize {}

// Note: this does not create NULL vtable because we get `None` anyway.
unsafe impl<T: ?Sized> ZeroableInOption for NonNull<T> {}
unsafe impl<T: ?Sized> ZeroableInOption for &'_ T {}
unsafe impl<T: ?Sized> ZeroableInOption for &'_ mut T {}

#[cfg(feature = "extern_crate_alloc")]
#[cfg_attr(feature = "nightly_docs", doc(cfg(feature = "extern_crate_alloc")))]
unsafe impl<T: ?Sized> ZeroableInOption for alloc::boxed::Box<T> {}