Function diff_reversed

src/sort.c:2779–2783

   If REVERSED, do not simply negate DIFF as that can mishandle INT_MIN.  */

static int
diff_reversed (int diff, bool reversed)
{
  return reversed ? _GL_CMP (0, diff) : diff;
}

/* Compare two lines A and B trying every key in sequence until there
   are no more keys or a difference is found. */