[SR-3203] Never return function is not representable in ObjC

[rintaro]

Previous ID	SR-3203
Radar	None
Original Reporter	@rintaro
Type	Bug
Status	Resolved
Resolution	Done

Environment

Xcode Version 8.1 (8B62)
Apple Swift version 3.0.1 (swiftlang-800.0.58.6 clang-800.0.42.1)

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, 3.0Regression
Assignee	@slavapestov
Priority	Medium

md5: 60c1e6db25cf28a3cede4cc08fa409cd

Issue Description:

In Swift2.3,

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

was represented in Objective-C as

@interface Foo : NSObject
- (void)die;

In Swift3:

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

cannot be compiled as:

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 {
                      ^~~~~

[rintaro]

Compiling Swift 2.3 code results compiler crash.
025284bb

[rintaro]

CC: @slavapestov the original author of SE-0102 implementation.

[slavapestov]

#6545