Right, the calling code needs to handle its own integer overflows, of course. And if your circular array has a size other than a power of 2 you can get only a partial enumeration in the cycle that includes overflow. Sure. But are you really indexing an array of unknown size with a uint8? It's really
impossible that there might be more than 255 things you
ever care about? No. Everyone who is using a uint8 to index arrays is either doing something extremely low-level and fiddly where abstractions like this simply don't apply, or they're idiots who are doing cargo-cult shotgun "optimization" because they don't know how to write code that works.
If you're indexing with a [u]int32 you need to worry about this once every 4 billion increments, and if an incomplete cycle is a show-stopper for you, you can compute a safe modulo yourself based on the size(s) of your circular array(s), but more likely you just need something else. But really, you don't care if your cache hiccups a little once every 4 billion caches.
You make a good point, of course, I'm just allergic to people poking holes in back-of-the-napkin explanations of things with the trite "but integers can overflow!" It's one of those most common well actuallys written on this site. Of course integers can overflow. They almost never do though, do they? And if they do, a test fails and you add a single line somewhere to fix it.
I really think the vast majority of programmers are too often thinking about bits when they should be thinking about math.