relates to:

• SR-7151 Generalize CaseIterable Synthesis for Availability
• SR-8634 Deprecation warning at declaration site in typed enum

Issue Description:

The following code compiles as expected:

enum TrafficLight {
    @available(*, unavailable) case red
    case green
    case yellow
}

But this code leads to a compiler error:

enum TrafficLight: String {
    @available(*, unavailable) case red
    case green
    case yellow
}

MyPlayground.playground:4:37: note: 'red' has been explicitly marked unavailable here  
@available(\*, unavailable) case red  
~~~~~~~~~~~~~~~~~~~~~~~~~ ^

Some initial investigation indicates the error is may be related to the synthesized RawRepresentable conformance tripping availability checking