Bruno Kolenbrander

> I think it's a simpler API for users if PyO3 never adds an implicit default I'm generally against doing implicit things, so this sounds good. I've been mulling about...

> Although we agree it introduces a weird edge case, you could argue `#[cfg_attr]` not working _at all_ is also a weird edge case and definitely more annoying for users!...

> I wonder, to give us some control (and way to deprecate this when the language can do better), if we should gate this behavior behind an option? E.g. `#[pyclass(feature...

> Sorry i'm not following, but which is the solution you'd want? that either: - we merge this PR as is, no gating behind an option. - we don't merge...

> I still vouch in favour of including everybody as a co-author because i like these open-science kind of things where everybody is acknowledged, it's always nice to get some...

I have pyo3 as an optional dependency for this reason.