Docs don't match type niche

[programmerjake]

Shouldn't the OptionFileHandle use *mut c_void and not NonNull, since null is a valid value?

https://github.com/sunfishcode/io-experiment/blob/41303e0015f8a751d3ec86c9105984a47f49d989/src/types.rs#L153-L166

[sunfishcode]

There are reasons to guess that CreateFile never returns NULL, even as a successful value. Unfortunately, I haven't found an authoritative statement on that anywhere yet. I'd be interested if anyone has more info on this.

It would be quite unfortunate here if NULL could be valid handle value, because that would mean there's no single value we can carve out as a niche for Option<OwnedHandle>.

[sunfishcode]

On further reflection, it seems best to change this to a RawHandle and just explicitly check for null in the TryFrom implementation. We still don't support null handles, but in the absence of a proper guarantee, at least now we'll panic if we ever get a null here, rather than executing UB. I've also now expanded the documentation to mention the expectation that the handle is non-null.

99c6332

[sunfishcode]

The documentation is now expanded to describe this, and the code is now changed to panic instead of doing UB if we ever get a null, so I think this issue is now fixed. Thanks for filing this!

[programmerjake]

Thanks! Sorry I couldn't find any decent references for null-ness.