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

[David Nadlinger via Digitalmars-d-learn]

On Tuesday, 24 January 2017 at 11:49:59 UTC, Atila Neves wrote:
> But it's still annoying to have to do &array[0] just to pass it 
> to a C function, since `my_c_func(array.ptr)` isn't going to 
> screw up anything.

How do you know it does not screw up anything? Presumably, the 
function somehow accesses the object the pointer targets. How 
would this be @safe to call if the pointer were not 
dereferencable?

  — David