Should it be possible to use custom errors with FromPyObject?

[glevco]

Hi! Could we have a type Error on FromPyObject, so we can return non-PyErr errors from it? IntoPyObject has this, so I wonder whether there's any technical reason preventing this.

[birkenfeld]

I assume that would make it hard to decide what to do when FromPyObject is used behind the scenes in PyO3 generated code, eg to convert function arguments?

[Icxolu]

I would say the current state is mostly for historical reasons. Adding an associated Error type to FromPyObject also came up here #4390 (comment) in its rework. I think the conclusion from that was that we want to do it, but it will likely not make it in 0.24. Perhaps in 0.25, let's see.

[glevco]

Good to know this is on the radar, consider this an upvote on that feature request. I would be glad to help however I can.