the specific way to accomplish this is touchy.
see <https://github.com/EmbarkStudios/rust-gpu/issues/312#issuecomment-738824131>:
> So I'd say placing any of the spirv_std::storage_class types into an aggregate (including capturing it in a closure) is unsupported for now
in our specific case, we can't return a tuple where one element is a `&`
to a spirv Input, and another element is a `&mut` to a spirv Output.
when we have a struct, it can enclose either ONLY inputs,
or ONLY outputs -- not a mix.
i'm not 100% on how the Serialized stuff works, since it appears to
violate that. i guess that's exactly what this ArrayHandle stuff
achieves though.
colin
ebd2762d7a