is duplicated by:

• SR-1313 Switch statement exhaustiveness not inferred with wildcards and enums
• SR-4890 Exhaustive switch not treated as exhaustive
• SR-4891 Exhaustive switch statement on two optionals is flagged as non-exhaustive
• SR-2221 Compiler should be able to prove coverage for element-wise tuple match in switch

relates to:

• SR-4822 Exhaustive switch not recognized as such

Issue Description:

The compiler fails to see that this is an exhaustive switch statement:

enum MyEnum {
    case A, B
}
let (e, f) = (MyEnum.A, MyEnum.B)

switch (e, f) {
case (_, .B) : break
case (.B, _) : break
case (.A, .A): break
}

It accepts the following as exhaustive, but fails to warn that the last case will never be executed:

switch (e, f) {
case (_, .B) : break
case (.B, _) : break
case (.A, .A): break
case (.A, .B): break
}

It does not accept the following as exhaustive (same as the one above, except (.A, .A) is now the first case):

switch (e, f) {
case (.A, .A): break
case (_, .B) : break
case (.B, _) : break
case (.A, .B): break
}