You could use &[T] -> std::span<const T> and &mut [T] -> std::span<T>.

Yeah this is the main thing holding me back at the moment myself, I have code I'd like to port to use cxx, but it involves passing around slices/vectors frequently.

I started looking into what an implementation would take, and I don't think it would be too difficult to get something working, but unfortunately I can't spare the time at the moment, so I'll have to revisit in a few weeks and see if things are still in limbo.

RE: std::span - it is only in C 20, so I don't think it's the best option in the near term (though it could be conditionally enabled if available). I'd think something akin to the way &str is handled would apply here. As long as the C implementation provides the iterator traits, it wouldn't make much of a difference in ergonomics.

I made an attempt at some progress here: #117

&[u8] support was released in cxx 0.2.9, &mut [u8] in 1.0.3, and &[T] / &mut [T] for T!=u8 in 1.0.5, so we should be all done here!