Why is &array[0] @safer than array.ptr?

[David Nadlinger via Digitalmars-d-learn]

On Wednesday, 25 January 2017 at 22:54:32 UTC, Adam D. Ruppe 
wrote:
> On Wednesday, 25 January 2017 at 22:46:10 UTC, David Nadlinger 
> wrote:
>> This is because every pointer in SafeD is dereferencable.
>
> But null pointers are allowed in SafeD and arr.ptr is either 
> arr[0] or null....

This is a fallacy:

---
@safe: // Deprecated, though.

ubyte oops(ubyte[] b) {
     return *b.ptr;
}

void main() {
     oops(new ubyte[0]);
     // - or -
     auto b = new ubyte[42];
     oops(b[$ .. $]);
}
---

  — David