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SubjectRe: [PATCH v2 4/5] rust: types: implement `ForeignOwnable` for the unit type
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Wedson Almeida Filho <wedsonaf@gmail.com> writes:

> This allows us to use the unit type `()` when we have no object whose
> ownership must be managed but one implementing the `ForeignOwnable`
> trait is needed.
>
> Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
> Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
> ---

Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>

> v1 -> v2: use `NonNull::dangling` to generate pointer
>
> rust/kernel/types.rs | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
> index 411655eca3e9..9d0fdbc55843 100644
> --- a/rust/kernel/types.rs
> +++ b/rust/kernel/types.rs
> @@ -85,6 +85,18 @@ impl<T: 'static> ForeignOwnable for Box<T> {
> }
> }
>
> +impl ForeignOwnable for () {
> + type Borrowed<'a> = ();
> +
> + fn into_foreign(self) -> *const core::ffi::c_void {
> + core::ptr::NonNull::dangling().as_ptr()
> + }
> +
> + unsafe fn borrow<'a>(_: *const core::ffi::c_void) -> Self::Borrowed<'a> {}
> +
> + unsafe fn from_foreign(_: *const core::ffi::c_void) -> Self {}
> +}
> +
> /// Runs a cleanup function/closure when dropped.
> ///
> /// The [`ScopeGuard::dismiss`] function prevents the cleanup function from running.

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