Switch on implicitly unwrapped optional enum variable should not require a .none case

[ewegener1]

Description

When we switch on an implicitly unwrapped optional enum variable, a .none case should not be required because the enum variable should be unwrapped before the switch happens. Hence the .none case should not be reachable.

Reproduction

The following code does not compile. The compiler wants me to add a .none case when switching on an implicitly unwrapped optional variable.

import Foundation

enum SomeEnum {
    case someCase
}

class SomeClass {
    var implicityUnwrappedEnum: SomeEnum! // note the exclamation mark here

    func main() {
        switch implicityUnwrappedEnum {
        case .someCase:
            return
        }
    }
}

Error: switch must be exhaustive
Note: add missing case: '.none'

Expected behavior

The code below compiles without errors:

import Foundation

enum SomeEnum {
    case someCase
}

class SomeClass {
    var implicityUnwrappedEnum: SomeEnum!

    func main() {
        switch implicityUnwrappedEnum {
        case .someCase:
            return
        }
    }
}

Environment

5

Additional information

No response