class Foo: NSObject {
    @objc @noreturn func die() {
        fatalError("die")
    }
}

@interface Foo : NSObject
- (void)die;

class Foo: NSObject {
    @objc func die() -> Never {
        fatalError("die")
    }
}

test.swift:4:14: error: method cannot be marked @objc because its result type cannot be represented in Objective-C
  @objc func die() -> Never {
             ^
test.swift:4:23: note: non-'@objc' enums cannot be represented in Objective-C
  @objc func die() -> Never {
                      ^~~~~