`Sendable` annotations are not available

[MaxDesiatov]

It looks like none of the Sendable annotations have been ported over [from Darwin Foundation].

Originally posted by @0xTim in #4619 (comment)

[dnadoba]

Just run into that too
Date on Darwin is Sendable but corelibs Foundation Date is not.

[dnadoba]

Nothing is marked Sendable except CloseMode https://github.com/apple/swift-corelibs-foundation/search?q=Sendable

[parkera]

Fixed by #5000