case OP_CONST:
  sv = cSVOPo_sv;
  if (cSVOPo->op_private & OPpCONST_STRICT)
    no_bareword_allowed(o);
  else {
    if (ckWARN(WARN_VOID)) {
      useless = "a constant";
      /* don't warn on optimised away booleans, eg
       * use constant Foo, 5; Foo || print; */
      if (cSVOPo->op_private & OPpCONST_SHORTCIRCUIT)
        useless = 0;
      /* the constants 0 and 1 are permitted as they are
         conventionally used as dummies in constructs like
           1 while some_condition_with_side_effects;  */
      else if (SvNIOK(sv) &&
        (SvNV(sv) == 0.0 || SvNV(sv) == 1.0))
        useless = 0;