static int[] indicesOfIC_array(L<S> l, S a) {
  new IntBuffer buf;
  for (int i = 0; i < l(l); i++)
    if (eqic(l.get(i), a))
      buf.add(i);
  ret buf.toArray();
}

static <A> int[] indicesOfIC_array(S s, S x) {
  int i = -1;
  new IntBuffer buf;
  while ((i = indexOfIC(s, x, i+1)) >= 0)
    buf.add(i);
  ret buf.toArray();
}

Began life as a copy of #1017912