extension Never: Error {}
struct SomeError: Error {}

func throwButNoReturn() throws -> Never { throw SomeError() }

_ = try? throwButNoReturn()

// UNEXPECTED: warning: will never be executed
print("made it!")

do {
    try throwButNoReturn()
}
// EXPECTING: warning: will never be executed
catch is Never {
    fatalError("never")
}

enum Action {
// EXPECTING: error: Never cannot be used as an associated value in an enum
    case youDown(Never)
    case giveYouUp(Never)
}

func goingTo() -> Action { exit(EXIT_SUCCESS) }

switch goingTo() {
case let .youDown(x):
    break
// UNEXPECTED: error: Switch must be exhaustive, consider adding a default clause
// If Never is allowed in an enum then those cases cannot be reached
}

// EXPECTING: warning: will never be executed
exit(EXIT_SUCCESS)
// CORRECT: warning: will never be executed
exit(EXIT_FAILURE)