Can assumeSafeAppend() grab more and more capacity?

[Jesse Phillips via Digitalmars-d-learn]

On Monday, 5 June 2017 at 23:17:46 UTC, Ali Çehreli wrote:
>     auto a = [ 1, 2, 3, 4 ];
>     auto b = a;
>
> Both of those slices have non-zero capacity yet one of them 
> will be the lucky one to grab it. Such semantic issues make me 
> unhappy. :-/
>
> Ali

You have to remember that slices don't own their memory. So while 
capacity show a guaranteed reserved memory, it is reserved for 
the dynamic array the slice has a window into.

Remove probably shouldn't try to reclaim capacity, while it is 
destructive for any other slice, it shouldn't make string 
appending also destructive.

untested:

      auto a = [ 1, 2, 3, 4 ];
      auto b = a[$-1, $];
      a.remove(2);
      assert(b == [4]);
      a ~= 6;
      assert(b == [4]);