This is an area of Switch statement analysis I really want to be able to cover at some point. I just have no idea how to efficiently represent this for the different kinds of integers Swift supports. It seems like we need some kind of bounded Index Set type for this.

Quoting @jckarter from an earlier bug:

Unfortunately, integer operations like '...' and '<' are just plain functions to Swift, so it'd be difficult to do this kind of analysis. Even with special case understanding of integer intervals, I think there are still cases in the full generality of pattern matching for which exhaustiveness matching would be undecidable. We may eventually be able to handle some cases, but there will always be special cases involved in doing so.

We're unlikely to special-case this given that matching the entire integer space is not a very common thing to do.

It's maybe more likely with smaller types like Int8/Int16, or with enums that are `Comparable`.

I don't know why we closed this. It's a worthy enhancement to exhaustiveness checking if done in an (albeit) limited way.