Stream.property(forKey:) and Stream.setProperty(_:forKey:) have different signatures on macOS and Linux

[alanfalloon]

The Stream.property(forKey:) and Stream.setProperty(_:forKey:) methods have the following signatures on macOS:

func property(forKey: Stream.PropertyKey) -> Any?
func setProperty(
    _ property: Any?,
    forKey key: Stream.PropertyKey
) -> Bool

However, on Linux the signature appears to be:

func property(forKey: Stream.PropertyKey) -> AnyObject?
func setProperty(
    _ property: AnyObject?,
    forKey key: Stream.PropertyKey
) -> Bool

I.e. they accept and return AnyObject? instead of Any?.

I discovered this when trying to make an InputStream subclass that works in macOS and Linux on Swift 5.9

Swift version 5.9-dev (LLVM 4f65c75dc0fa855, Swift 174828b01c4e250)
Target: x86_64-unknown-linux-gnu