can we un-deprecate .ptr on arrays in @safe code? cf issue 18529

[Seb]

On Tuesday, 27 February 2018 at 11:33:04 UTC, Simen Kjærås wrote:
> That only checks if the first element is the same. For a full 
> 'is slice' check you'd need something like this:
>
>     assert(a.ptr <= b.ptr && b.ptr + b.length <= a.ptr + 
> a.length);
>
> // Or:
>
>     auto c = b.ptr - a.ptr;
>     assert(c >= 0 && c + b.length <= a.length);
>
> And trust me, the compiler complains about both of these. 
> Possibly rightfully in the first example, but the latter never 
> does anything scary with the given pointers.
>
> --
>   Simen

aka isSliceOf -> https://github.com/dlang/phobos/pull/6147