ded for <a class="el" href="classipc_1_1session_1_1Session__base_1_1Graceful__finisher.html#af441f45ce1ed7b890c3ab77d959f8830" title="The reason Graceful_finisher exists, this method must be called at the start of *_session_impl dtor; ...">on_dtor_start()</a> to <code>return</code>? One, A dtor has to have started &ndash; but that's true by the contract of when the method is called; two, B dtor has to have started. How do we get informed of the latter? Answer: B sends a special message along the <a class="e