Sendable in Foundation

[hborla (Holly Borla)]

@KeithBauerANZ

There's no warning for creating a non-Sendable subclass of a Sendable class, though.

There is now: [Concurrency] Warn if implied `@unchecked Sendable` conformances are not re-stated. by hborla · Pull Request #71866 · apple/swift · GitHub

[nh7a]

Then, I wonder why UserDefaults is still not Sendable...

@available(*, unavailable)
extension UserDefaults : @unchecked Sendable {
}