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use libc::c_int; use std::marker::PhantomData; /// A slot in a type's "extra data" structure. /// /// It is parameterized over the type containing the extra data as well as the /// type of the data in the slot. pub struct Index<T, U>(c_int, PhantomData<(T, U)>); impl<T, U> Copy for Index<T, U> {} impl<T, U> Clone for Index<T, U> { fn clone(&self) -> Index<T, U> { *self } } impl<T, U> Index<T, U> { /// Creates an `Index` from a raw integer index. /// /// # Safety /// /// The caller must ensure that the index correctly maps to a `U` value stored in a `T`. pub unsafe fn from_raw(idx: c_int) -> Index<T, U> { Index(idx, PhantomData) } #[allow(clippy::trivially_copy_pass_by_ref)] pub fn as_raw(&self) -> c_int { self.0 } }