> That is integer arithmetic, not pointer arithmetic.

Yeah, but I did say: "which operation could any C compiler disallow in practice: converting from pointer to integer, arithmetic on integers, or converting from integer to pointer?"

If C/C++ compilers keep breaking pointer arithmetic in the game of exploiting undefined behavior for optimizations, people are going to start doing pointer arithmetic with integers when they need it. And they do need it sometimes, for debuggers, profilers, memory checkers, JITs, garbage collectors, shared memory, and so on.