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

[Kagamin via Digitalmars-d-learn]

On Tuesday, 24 January 2017 at 12:01:35 UTC, Jonathan M Davis 
wrote:
> So, while it makes sense to say that .ptr can't be used in 
> @safe code, it really doesn't make sense to suggest &arr[0] as 
> an alternative.

When you ensure pointers point to existing data, you can 
dereference them in safe code, otherwise you can't.