Re: [PATCH v10 1/2] rust: types: add `ForeignOwnable::PointedTo`

[Alice Ryhl]

On Wed, Nov 20, 2024 at 12:48 PM Tamir Duberstein <tamird@xxxxxxxxx> wrote:
>
> Allow implementors to specify the foreign pointer type; this exposes
> information about the pointed-to type such as its alignment.
>
> This requires the trait to be `unsafe` since it is now possible for
> implementors to break soundness by returning a misaligned pointer.
>
> Encoding the pointer type in the trait (and avoiding pointer casts)
> allows the compiler to check that implementors return the correct
> pointer type. This is preferable to directly encoding the alignment in
> the trait using a constant as the compiler would be unable to check it.
>
> Signed-off-by: Tamir Duberstein <tamird@xxxxxxxxx>

I'm not super convinced by this way forward. It introduces more casts
to/from c_void in code using it, and forces us to expose internal
types such as ArcInner. Does anyone else have thoughts on this?

Alice