While there is no direct access to flags in standard C, you can nevertheless on gcc and clang compile with -ftrapv and get your signed integer arithmetic be overflow-checked. Or you can use __builtin_add_overflow & co and get access to the overflow flags that way. Rust debug builds trap on signed and unsigned integer overflow, and you can make release builds do so too.

While it'd be nice to have a formal proof that every single `a+b`, `a-b`, `a*b` in every codebase doesn't overflow, I'm sure you understand that that is rather impractical. (and really, it'd be nice! I've thought about having some compile-time-bounded-size integers where each addition increases the size, but multiplication is much less suitable for that, and it also means you can't have a loop adding to an accumulator. It's a rather non-trivial problem really - you might think that it'd be fine to have a loop over a list of objects and sum their sizes, but that can relatively easily overflow if the list references the same massive object many times, so can't even really abstract that)