60     pub unsafe trait Project<Src: ?Sized, Dst: ?Sized> {
61         /// Projects a pointer from `Src` to `Dst`.
72         /// `src`'s referent, and has the same provenance as `src`.
73         fn project(src: PtrInner<'_, Src>) -> *mut Dst;  in project()
83     pub unsafe trait Cast<Src: ?Sized, Dst: ?Sized>: Project<Src, Dst> {}
90     pub unsafe trait CastExact<Src: ?Sized, Dst: ?Sized>: Cast<Src, Dst> {}
102         fn project(src: PtrInner<'_, T>) -> *mut T {  in project()
103             src.as_ptr()  in project()
119     /// guarantee that `Dst` is no larger than `Src`. Thus, `CastSized` has a
120     /// sound implementation of [`Project`] for all `Src` and `Dst` – the caller
121     /// may pass any `Src` and `Dst` without being responsible for soundness.
125     // SAFETY: By the `static_assert!`, `Dst` is no larger than `Src`,
128     unsafe impl<Src, Dst> Project<Src, Dst> for CastSized {
130         fn project(src: PtrInner<'_, Src>) -> *mut Dst {  in project()
131             static_assert!(Src, Dst => mem::size_of::<Src>() >= mem::size_of::<Dst>());  in project()
132             src.as_ptr().cast::<Dst>()  in project()
137     unsafe impl<Src, Dst> Cast<Src, Dst> for CastSized {}
145     /// guarantee that `Dst` has the same size as `Src`. Thus, `CastSizedExact`
146     /// has a sound implementation of [`Project`] for all `Src` and `Dst` – the
147     /// caller may pass any `Src` and `Dst` without being responsible for
152     // SAFETY: By the `static_assert!`, `Dst` has the same size as `Src`,
155     unsafe impl<Src, Dst> Project<Src, Dst> for CastSizedExact {
157         fn project(src: PtrInner<'_, Src>) -> *mut Dst {  in project()
158             static_assert!(Src, Dst => mem::size_of::<Src>() == mem::size_of::<Dst>());  in project()
159             src.as_ptr().cast::<Dst>()  in project()
164     unsafe impl<Src, Dst> Cast<Src, Dst> for CastSizedExact {}
168     unsafe impl<Src, Dst> CastExact<Src, Dst> for CastSizedExact {}
177     /// `CastUnsized` has a sound implementation of [`Project`] for all `Src`
178     /// and `Dst` – the caller may pass any `Src` and `Dst` without being
183     // SAFETY: By the `static_assert!`, `Src` and `Dst` are either:
186     //   and with align_of::<Src>() == align_of::<Dst>(). These ensure that any
187     //   given pointer metadata encodes the same size for both `Src` and `Dst`
190     unsafe impl<Src, Dst> Project<Src, Dst> for CastUnsized
192         Src: ?Sized + KnownLayout,
193         Dst: ?Sized + KnownLayout<PointerMetadata = Src::PointerMetadata>,
196         fn project(src: PtrInner<'_, Src>) -> *mut Dst {  in project()
199             static_assert!(Src: ?Sized + KnownLayout, Dst: ?Sized + KnownLayout => {  in project()
200                 let src = <Src as KnownLayout>::LAYOUT;  in project()  localVariable
202                 match (src.size_info, dst.size_info) {  in project()
207 …) => src.align.get() == dst.align.get() && src_offset == dst_offset && src_elem_size == dst_elem_s…  in project()
212             let metadata = Src::pointer_to_metadata(src.as_ptr());  in project()
213             Dst::raw_from_ptr_len(src.as_non_null().cast::<u8>(), metadata).as_ptr()  in project()
218     unsafe impl<Src, Dst> Cast<Src, Dst> for CastUnsized
220         Src: ?Sized + KnownLayout,
221         Dst: ?Sized + KnownLayout<PointerMetadata = Src::PointerMetadata>,
225     // SAFETY: By the `static_assert!` in `Project::project`, `Src` and `Dst`
230     //   same size for both `Src` and `Dst` (note that the alignment is required
232     unsafe impl<Src, Dst> CastExact<Src, Dst> for CastUnsized
234         Src: ?Sized + KnownLayout,
235         Dst: ?Sized + KnownLayout<PointerMetadata = Src::PointerMetadata>,
257         fn project(src: PtrInner<'_, T>) -> *mut T::Type {  in project()
258             T::project(src)  in project()
365     // SAFETY: `project` constructs a pointer with the same address as `src`
366     // and with a referent of the same size as `*src`. It does this using
370     // Technically, this proof assumes that `*src` is contiguous (the same is
374         fn project(src: PtrInner<'_, T>) -> *mut [u8] {  in project()
375             let bytes = match T::size_of_val_raw(src.as_non_null()) {  in project()
379                 // `usize`. By invariant on `PtrInner`, `src` refers to a range  in project()
385             core::ptr::slice_from_raw_parts_mut(src.as_ptr().cast::<u8>(), bytes)  in project()
403         fn project(src: PtrInner<'_, T>) -> *mut () {  in project()
404             src.as_ptr().cast::<()>()  in project()