Soa<T> doesn't support Clone when T: Clone.

[PPakalns]

Soa array can not be cloned when data stored inside can be.

https://docs.rs/soa-rs/latest/src/soa_rs/soa.rs.html#685-708

If necessary, maybe Soa can implement Clone if all fields implement Clone.

This limitation makes Soa array hard to use. I would prefer slower operation that works so trait can be auto derived. If someone requires fast version, this could be added under fast_clone() or something like that, if that is the reason for the current limitation.

[tim-harding]

Unfortunately, this is not possible to implement safely, at least not that I know of. Previously, I had a WithRef trait that would let you do this, but #3 showed this was unsound. Maybe we could integrate with bytemuck to allow this when the struct is Copy + bytemuck::Pod so that we just need to copy the underlying allocation rather than individual entries.

[PPakalns]

If all field types implement Clone then shouldn't this be safe?

I can write logic without unsafe doing the following:

Just iterate through all array, clone all fields into new structure and push it into new Soa array.

If problem is due to breaking type invariants, maybe this logic can be exposed as custom derive (not auto implemented). So that soa_rs users should manually opt-in if fields can be cloned into new structure without breaking any invariants.

[tim-harding]

That could be possible. It would probably be something like SoaClone that you implement for MyType so that people could customize it. The Soa would then implement Clone when T::Ref implements SoaClone. That pattern could also be used for equality and such.

[tim-harding]

Okay, here is what I can do. ToOwned doesn't have the same issue as Clone because it takes a reference to an arbitrary borrow type. This is helpful because it works for getting owned data from borrows other than &T, which is exactly what we need to make this work. We can implement Borrow<TRef> for T by taking references to each of T's fields, and then we can implement ToOwned<Owned = T> for TRef by calling clone on each field of TRef, bounded by all field types implementing Clone.

Edit: This almost works, but unfortunately TRef has to be created on the stack and Borrow::borrow returns a reference, so it's not implementable.