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Subject[PATCH 4/5] rust: types: implement `ForeignOwnable` for the unit type
Date
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>
---
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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