[swift-corelibs-dev] Migrate corelibs-foundation to the newest APIs

As you know, currently, as of the 03-24 DEVELOPMENT snapshot, the function signatures for Foundation has diverged. This has caused us to create platform specific calls to the NSString, NSDate, NSCache, etc. classes. For instance,

Re: [swift-corelibs-dev] Migrate corelibs-foundation to the newest APIs

Hi Robert, This is something we really do need some help with. Our goal is to have the Linux version match the Darwin version exactly. There is also a PR up to change some of the results of the automatic renaming by the importer, here: https://github.com/apple/swift/pull/2093

Re: [swift-corelibs-dev] Foundation and explicit pointer nullability (CI edition)

Final update: we decided it was cleaner to just update Foundation now rather than building with a separate branch and having to work out those dependencies, so essentially nothing will change. The pull request has been landed but is still planned to have a full post-commit review at a later date

Re: [swift-corelibs-dev] Migrate corelibs-foundation to the newest APIs

I noticed the folks at IBM were also doing platform checks when using the corelibs-xctest APIs. I created https://bugs.swift.org/browse/SR-1215 to track the issue. corelibs-xctest is small enough that we may want to consider providing *both* Swift 2.2 and Swift 3 APIs, perhaps behind a `#if swift(