Avoiding UB for performing the signed addition/subtraction/multiplication is trivial - just cast to unsigned, do the operation, cast back. In standard C23 or GN

Avoiding UB for performing the signed addition/subtraction/multiplication is trivial - just cast to unsigned, do the operation, cast back. In standard C23 or GNU C11, you can write a `make_unsigned` and `make_signed` macro using `typeof` and `_Generic`.