I’ll blame CPU makers when you can name one CPU in current use that isn’t bog standard 2’s complement that wraps around by default.
About Zig, you probably meant implementation defined, or at the very worst unspecified. In C standard parlance those aren’t undefined at all. They can’t encrypt your hard drive just because you relied on them. Undefined behaviour however, can. And does, when UB happens to enable an arbitrary code execution vulnerability.
Zig does have modular `+%` and saturating `+|` operators, as well as `@addWithOverflow()`, though. You get to choose what happens on overflow; if you don't, the compiler gets to.
having overflow of a common loop type be undefined is extremely useful for optimization, since many kind of unrolling and vectorization approaches only work if you can assume the loop counter cannot wrap.
