この変更は4.1 には入らないと思います。 https://github.com/apple/swift-source-compat-suite/pull/131 実際互換性問題出てますね。

XFAIL GRDB until extension for constrainted typealiases is possible by airspeedswift · Pull Request #131 · apple/swift-source-compat-suite

apple/swift#13342 uses conditional conformance to make Range a Collection when its Bound is Strideable. For compatibility, CountableRange is still available as a type alias. There is one source com...