swift - 神秘的 "Will never be executed"警告

Question

我试图在这里理解“永远不会被执行”警告:

protocol FatalErrorReporterInterface {

    func fail(_ message: String) -> Never

}

final class FatalErrorReporter: FatalErrorReporterInterface {

    // This line emits "Will never be executed" warning
    func fail(_ message: String) -> Never {
        fatalError(message)
    }

}

又一个编译器错误？

Answer 1

Jordan Rose 在 Swift Evolution 邮件列表中回复:

Sure looks like one to me. In particular, it looks like SR-2729.

(I suspect this is because calling the method through the protocol generates a bit of wrapper code that then calls the original method; that wrapper code doesn’t have a location of its own.)

Sorry for the trouble, Jordan

链接:

https://bugs.swift.org/browse/SR-2729