如何将Bootstrap的下拉菜单定位到浮动的右切换元素的右侧？

<div class="dropdown">
  <button class="btn btn-primary dropdown-toggle" type="button" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    切换
  </button>
  <div class="dropdown-menu dropdown-menu-right" aria-labelledby="dropdownMenuButton">
    <a class="dropdown-item" href="#">菜单项1</a>
    <a class="dropdown-item" href="#">菜单项2</a>
    <a class="dropdown-item" href="#">菜单项3</a>
  </div>
</div>

.float-right {
  float: right;
}

.dropdown-menu-right {
  right: 0;
}

.dropdown-menu-float-right {
  float: right;
}