That's not why it's ub. It's ub to allow compilers to optimize x*2/2 to just x. If you want overflow, you can use unsigned, which has been defined to follow 2's

That's not why it's ub. It's ub to allow compilers to optimize x*2/2 to just x. If you want overflow, you can use unsigned, which has been defined to follow 2's complement semantics for quite some time.