static L<RuleFailInfo> nlLogic_ruleFails(NLLogicChecker_v2 c, L<IfThen> rules) {
  new L<RuleFailInfo> out;
  for (IfThen rule : unnull(rules)) {
    new NLLogicChecker_v2.Matching m;
    Pair<Int, Exp> p = nlLogic_checkFirstConditions2(c, rule, m);
    if (p.b != null)
      out.add(RuleFailInfo(rule, p.a, m.matches, p.b);
  }
  ret out;
}