2 Checks for casts of function pointers to something other than usize
5 Casting a function pointer to anything other than usize/isize is not portable across
6 architectures, because you end up losing bits if the target type is too small or end up with a
7 bunch of extra bits that waste space and add more instructions to the final binary than
8 strictly necessary for the problem
10 Casting to isize also doesn't make sense since there are no signed addresses.