warning: pointer not aligned at address

[Andrew Edwards via Digitalmars-d-learn]

Conveniently the site is down immediately after I posted that so 
here is the code to which I was referring:

import std.stdio, std.algorithm, std.range;

enum DoorState : bool { closed, open }
alias Doors = DoorState[];

Doors flipUnoptimized(Doors doors) pure nothrow {
     doors[] = DoorState.closed;

     foreach (immutable i; 0 .. doors.length)
         for (ulong j = i; j < doors.length; j += i + 1)
             if (doors[j] == DoorState.open)
                 doors[j] = DoorState.closed;
             else
                 doors[j] = DoorState.open;
     return doors;
}

Doors flipOptimized(Doors doors) pure nothrow {
     doors[] = DoorState.closed;
     for (int i = 1; i ^^ 2 <= doors.length; i++)
         doors[i ^^ 2 - 1] = DoorState.open;
     return doors;
}

void main() {
     auto doors = new Doors(100);

     foreach (const open; [doors.dup.flipUnoptimized,
                           doors.dup.flipOptimized])
         iota(1, open.length + 1).filter!(i => open[i - 
1]).writeln;
}