src/third_party/v8/test/mjsunit/regress/regress-crbug-548580.js

// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

function store(v) {
  var re = /(?=[d#.])/;
  re.a = v;
  return re;
}

var re1 = store(undefined);
var re2 = store(42);

assertEquals(re1.a, undefined);
assertEquals(re2.a, 42);