SE-0269: Increase availability of implicit self in @escaping closures when reference cycles are unlikely to occur – https://github.com/apple/swift-evolution/blob/master/proposals/0269-implicit-self-explicit-capture.md
SE-0110: Distinguish between single-tuple and multiple-argument function types – https://github.com/apple/swift-evolution/blob/master/proposals/0110-distingish-single-tuple-arg.md