e_base</span><span class="special">&lt;</span><span class="identifier">Tag</span><span class="special">&gt;;</span>
  <span class="keyword">friend</span> <span class="keyword">struct</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">wrapper_base</span><span class="special">&lt;</span><span class="identifier">Tag</span><span class="special">,</span> <span class="identifier">basic_message</span><span class="special">&lt;</span><span class="identifier">Tag</sp