(edited)

Biacco42

import Foundation import RxSwift class Hoge: NSObject {} extension Reactive where Base == Hoge { class Piyo {} var hoge: Observable<Int> { return Observable.create { observer in var piyo = Piyo() observer.onNext(42) return Disposables.create {} } } } let hoge = Hoge() hoge.rx.hoge.subscribe(onNext: { res in print(res) })

Version:

swift-4.1.1-RELEASE

Output:

42

Error:

/usercode/main.swift:10:17: warning: initialization of variable 'piyo' was never used; consider replacing with assignment to '_' or removing it var piyo = Piyo() ~~~~^~~~ _ /usercode/main.swift:19:14: warning: result of call to 'subscribe(onNext:onError:onCompleted:onDisposed:)' is unused hoge.rx.hoge.subscribe(onNext: { res in ^ ~~~~~~~~~~~~~~~~~