> If their pointer subtraction uses similar semantics, there might be issues if they want to compare pointers from different allocation objects, are worried abo

> If their pointer subtraction uses similar semantics, there might be issues if they want to compare pointers from different allocation objects, are worried about 32-bit or 16-bit platforms, or maybe even consider the performance concerns too worrisome. Any of these type of issue would equally invalidate using unsafe{} to cast the pointer to a reference, which is what non_null! does.