Ah, that makes sense.

I think we should consider deprecating/removing `Unique`. I added it back when I was working on the Rust-for-GPU prototype as a way of letting OpenCL kernels written in Rust work with vectors natively. This required some nasty code, most of which won't work under modern Rust. Unless we have another user of `Unique`, I'm fine with removing it.  We can add something new if we need it in the future.

That said, kernels written in OpenCL C may still want to use non-homogeneous buffers. I guess we could still treat them as `u8` slices though.