Well if we're not super worried about implementation difficulty right now:
* 1 and 4-7: Don't worry about where the pointer goes, as long as you treat it like an int in this function. If there are going to be warnings about improper pointers, they should be at the call sites.
* 2 If overflow will either trap, wrap, or behave like a bignum, then it's not the dangerous kind of UB, so no warning by default. Consider extending C so the coder can more easily control integer overflow.
* 3 Anything could race. Out of scope, don't worry about it.
* 1 and 4-7: Don't worry about where the pointer goes, as long as you treat it like an int in this function. If there are going to be warnings about improper pointers, they should be at the call sites.
* 2 If overflow will either trap, wrap, or behave like a bignum, then it's not the dangerous kind of UB, so no warning by default. Consider extending C so the coder can more easily control integer overflow.
* 3 Anything could race. Out of scope, don't worry about it.