[tialaramex]

People read the comment that you wrote, in which you, in typical "real programmer" fashion redefined the question so that it matched your preferred answer, by mentioning a flag that does not in fact, check for overflow and then clarifying that you've decided to check for undefined behaviour not for overflow.

[ saagarjha has since explained that in fact the UBSan does sanitize unsigned integer overflow (and several other things that aren't Undefined Behaviour) so this was wrong, left here for posterity ]

Machines are fine with the behaviour being whatever it is. But humans aren't and so the distant ancestor post says they liked the fact Zig has overflow checks in debug builds. So does Rust.

If you'd prefer to reject overflow entirely, it's prohibited in WUFFS. WUFFS doesn't need any runtime checks, since it is making all these decisions at compile time, but unlike Zig or indeed C it is not a general purpose language.

[saagarjha]

I would personally prefer a stronger invariant–overflows checked in release builds as well. Compile time checks are nice in the scenarios where you can make them work, of course, but not feasible for many applications.