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    SubjectRe: [PATCH 4/5] rust: types: implement `ForeignOwnable` for the unit type
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    On Thu Jan 19, 2023 at 6:40 PM CET, Wedson Almeida Filho wrote:
    > 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>

    > ---
    > rust/kernel/types.rs | 13 +++++++++++++
    > 1 file changed, 13 insertions(+)
    >
    > diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
    > index e037c262f23e..8f80cffbff59 100644
    > --- a/rust/kernel/types.rs
    > +++ b/rust/kernel/types.rs
    > @@ -85,6 +85,19 @@ impl<T: 'static> ForeignOwnable for Box<T> {
    > }
    > }
    >
    > +impl ForeignOwnable for () {
    > + type Borrowed<'a> = ();
    > +
    > + fn into_foreign(self) -> *const core::ffi::c_void {
    > + // We use 1 to be different from a null pointer.
    > + 1usize as _
    > + }
    > +
    > + 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.
    > --
    > 2.34.1

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