Use Hashable.hash(into:) over hashValue to silence the deprecation warnings

[ikesyo]

There are some remaining warnings, but this should be a good start.

[ikesyo]

@swift-ci Please test

[lorentey]

I have one major issue with NSObject's hashing, and lots of smaller nitpicks.

The NSObject issue isn't new with this PR, but since we're changing it, we might as well change it to something that's consistent with Apple's Foundation.

[lorentey]

For compatibility with the Foundation overlay on Cocoa platforms, we should not remove the existing hashValue definition, but we should make it public final instead of open. This also applies tohash(into:) -- it must also be declared public final. (See swiftlang/swift#20129)

The NSObject hashing interface is hash; subclasses must override that instead of hashValue or hash(into:). Sadly, this includes subclasses defined within this module -- I think there might be a couple of subclasses that do currently the wrong thing.

(On Darwin, NSObject.hashValue and hash(into:) are defined public because the enclosing module is small, and doesn't define subclasses. The appropriate qualifier in swift-corelibs-foundation is public final.)

[lorentey]

Thanks a lot for working on this!

The Foundation overlay on Apple platforms has not been updated yet, but there is no reason corelibs-Foundation can't do the transition first.

[ikesyo]

@lorentey Thanks for your review and the suggestions! I'll address those.

[ikesyo]

@swift-ci Please test

[parkera]

Thanks a lot for working on this!

The Foundation overlay on Apple platforms has not been updated yet, but there is no reason corelibs-Foundation can't do the transition first.

We're trying to keep these in sync as much as possible.

[lorentey]

I'll submit a PR to update the Foundation overlay soon -- it makes sense to hold this PR until then.

[ikesyo]

I'll submit a PR to update the Foundation overlay soon

@lorentey Is there any progress on the overlay? I'd like to merge this if it needs more time.

[lorentey]

Apologies for the delay. I split out your NSObject.hashValue commit into a separate PR -- #1850. I believe this can land immediately, pending review.

Switching to hash(into:) will need a bit of coordination; my PR for the overlays is still in progress.

[millenomi]

@swift-ci please test and merge