On Thu Feb 19, 2026 at 5:55 AM JST, Joel Fernandes wrote:
> +/// Create a C doubly-circular linked list interface `CList` from a raw
> `list_head` pointer.
> +///
> +/// This macro creates a `CList<T, OFFSET>` that can iterate over items of
> type `$rust_type`
> +/// linked via the `$field` field in the underlying C struct `$c_type`.
> +///
> +/// # Arguments
> +///
> +/// - `$head`: Raw pointer to the sentinel `list_head` object (`*mut
> bindings::list_head`).
> +/// - `$rust_type`: Each item's rust wrapper type.
> +/// - `$c_type`: Each item's C struct type that contains the embedded
> `list_head`.
> +/// - `$field`: The name of the `list_head` field within the C struct.
> +///
> +/// # Safety
> +///
> +/// This is an unsafe macro. The caller must ensure:
> +///
> +/// - `$head` is a valid, initialized sentinel `list_head` pointing to a
> list that remains
> +/// unmodified for the lifetime of the rust `CList`.
> +/// - The list contains items of type `$c_type` linked via an embedded
> `$field`.
> +/// - `$rust_type` is `#[repr(transparent)]` over `$c_type` or has
> compatible layout.
> +///
> +/// # Examples
> +///
> +/// Refer to the examples in this module's documentation.
> +#[macro_export]
> +macro_rules! clist_create {
> + ($head:expr, $rust_type:ty, $c_type:ty, $($field:tt).+) => {{
> + // Compile-time check that field path is a list_head.
> + let _: fn(*const $c_type) -> *const $crate::bindings::list_head =
> + |p| &raw const (*p).$($field).+;
> +
> + // Calculate offset and create `CList`.
> + const OFFSET: usize = ::core::mem::offset_of!($c_type, $($field).+);
> + $crate::ffi::clist::CList::<$rust_type, OFFSET>::from_raw($head)
> + }};
> +}
This uses offset_of! in a way that requires the offset_of_nested
feature, so it doesn't build in rust 1.78.0. The feature is already
added to rust_allowed_features, so I think it's ok to add
#![feature(offset_of_nested)].
