At least in JVM land, it's pretty easy to thwart that optimization. Particularly if the condition is on a mutable yet unchanged in the loop value.

For example:

    var map = new HashMap<String, String>();
    map.put("foo", "bar");
    for (var i : items) {
      if ("bar".equals(map.get("foo")) {
        doStuff(i);
      }
    }