e this workaround and must
    be a base class of their primary operand type. Those templates define
    operators which must be member functions, and the workaround needs the
    operators to be independent friend functions. The relevant templates
    are:</p>

    <ul>
      <li><code><a href=
      "#dereferenceable">dereferenceable&lt;&gt;</a></code></li>

      <li><code><a href="#indexable">indexable&lt;&gt;</a></code></li>

      <li>Any composite operator template that includes at least one of the
 