For C at least, the spec says that unsigned addition is modulo 2^64 (or 32 or 16 or whatever) so, imagine you had an 8 bit unsigned, 128+128 gives you 0. Divided by 2 is 0. That’s the right answer by the language specification. The trick is to get 128.
If it is used and there's no way around it, then show a compilation warning that there might be overflow. If it can be resolved without being directly used, then it should be optimized away.
