Resolve improper ctype lint affecting RustSlice
diff --git a/src/rust_slice.rs b/src/rust_slice.rs
index 4b6b12b..b7b82e4 100644
--- a/src/rust_slice.rs
+++ b/src/rust_slice.rs
@@ -1,10 +1,11 @@
-use core::mem;
+use core::mem::{self, MaybeUninit};
use core::ptr::{self, NonNull};
use core::slice;
+// ABI compatible with C++ rust::Slice<T> (not necessarily &[T]).
#[repr(C)]
pub struct RustSlice {
- repr: NonNull<[()]>,
+ repr: [MaybeUninit<usize>; mem::size_of::<NonNull<[()]>>() / mem::size_of::<usize>()],
}
impl RustSlice {
@@ -37,25 +38,27 @@
// https://doc.rust-lang.org/nightly/std/ptr/struct.NonNull.html#method.from_raw_parts
// https://github.com/rust-lang/rust/issues/81513
let ptr = ptr::slice_from_raw_parts_mut(ptr.as_ptr().cast(), len);
- RustSlice {
- repr: unsafe { NonNull::new_unchecked(ptr) },
- }
+ unsafe { mem::transmute::<NonNull<[()]>, RustSlice>(NonNull::new_unchecked(ptr)) }
}
pub(crate) fn as_ptr<T>(&self) -> NonNull<T> {
- self.repr.cast()
+ let rust_slice = RustSlice { repr: self.repr };
+ let repr = unsafe { mem::transmute::<RustSlice, NonNull<[()]>>(rust_slice) };
+ repr.cast()
}
pub(crate) fn len(&self) -> usize {
- // TODO: use self.repr.len() when stable.
+ let rust_slice = RustSlice { repr: self.repr };
+ let repr = unsafe { mem::transmute::<RustSlice, NonNull<[()]>>(rust_slice) };
+ // TODO: use repr.len() when stable.
// https://doc.rust-lang.org/nightly/std/ptr/struct.NonNull.html#method.len
// https://github.com/rust-lang/rust/issues/71146
- let slice = unsafe { self.repr.as_ref() };
- slice.len()
+ unsafe { repr.as_ref() }.len()
}
}
+const_assert_eq!(mem::size_of::<NonNull<[()]>>(), mem::size_of::<RustSlice>());
const_assert_eq!(
- mem::size_of::<Option<RustSlice>>(),
- mem::size_of::<RustSlice>(),
+ mem::align_of::<NonNull<[()]>>(),
+ mem::align_of::<RustSlice>(),
);