<select class="form-control" name="{{ widget.name }}"{% include "django/forms/widgets/attrs.html" %}>{% for group_name, group_choices, group_index in widget.optgroups %}{% if group_name %}

  <optgroup label="{{ group_name }}">{% endif %}{% for option in group_choices %}

  {% include option.template_name with widget=option %}{% endfor %}{% if group_name %}

  </optgroup>{% endif %}{% endfor %}

</select>