11.6

["Matthew Heaney" <matthew_heaney@acm.org>]

Suppose we have a bounded stack:

  type Stack_Type (Size : Positive) is limited private;

  procedure Push
    (Stack : in out Stack_Type;
     Item  : in Item_Type);

private

  type Stack_Type (Size : Positive) is
    limited record
      Top : Natural := 0;
      Items : Item_Array (1 .. Size);
    end record;

end Stacks;


Now consider an implementation of Push:

  procedure Push
    (Stack : in out Stack_Type;
     Item  : in     Item_Type) is

     subtype Top_Range is Positive range 1 .. Stack.Size;

     Top : Natural renames Stack.Top;
  begin
     Top := Top_Range'(Top + 1);    --???
     Stack.Items (Top) := Item;
  end Push;


Is it possible, because of 11.6 permissions, that the explicit range
check in the marked line can be optimized away?

Another question: if I compile this (or the instantiation?) with checks
off, then will that cause the explicit range check to be omitted?