https://svn.boost.org/trac10/ticket/12155 <p> variant does not support a class derived from variant as one of its types. See the following example code: </p> <div class="wiki-code"><div class="code"><pre><span class="k">struct</span> <span class="n">A</span> <span class="p">{};</span> <span class="k">struct</span> <span class="n">B</span> <span class="p">{};</span> <span class="k">struct</span> <span class="n">C</span> <span class="p">{};</span> <span class="k">struct</span> <span class="nl">AB</span> <span class="p">:</span> <span class="n">boost</span><span class="o">::</span><span class="n">variant</span><span class="o">&lt;</span><span class="n">A</span><span class="p">,</span> <span class="n">B</span><span class="o">&gt;</span> <span class="p">{};</span> <span class="k">using</span> <span class="n">AB_C</span> <span class="o">=</span> <span class="n">boost</span><span class="o">::</span><span class="n">variant</span><span class="o">&lt;</span><span class="n">AB</span><span class="p">,</span> <span class="n">C</span><span class="o">&gt;</span><span class="p">;</span> <span class="kt">void</span> <span class="nf">foo</span><span class="p">()</span> <span class="p">{</span> <span class="n">AB</span> <span class="n">ab</span><span class="p">;</span> <span class="n">AB_C</span> <span class="n">ab_c</span><span class="p">{</span><span class="n">ab</span><span class="p">};</span> <span class="c1">// member function convert_construct is abiguous</span> <span class="p">}</span> </pre></div></div> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/12155 Trac 1.4.3 Antony Polukhin Mon, 30 May 2016 17:15:41 GMT https://svn.boost.org/trac10/ticket/12155#comment:1 https://svn.boost.org/trac10/ticket/12155#comment:1 <ul> <li><strong>owner</strong> changed from <span class="trac-author">ebf</span> to <span class="trac-author">Antony Polukhin</span> </li> <li><strong>status</strong> <span class="trac-field-old">new</span> → <span class="trac-field-new">assigned</span> </li> <li><strong>milestone</strong> <span class="trac-field-old">To Be Determined</span> → <span class="trac-field-new">Boost 1.62.0</span> </li> </ul> <p> Fixed in <a class="ext-link" href="https://github.com/boostorg/variant/commit/d23cdd3502b452231c6c6bc2f2d4298ca24b5650"><span class="icon">​</span>d23cdd35 develop</a>, will be merged to master branch as soon as the tests will cycle. </p> Ticket Antony Polukhin Sat, 29 Oct 2016 18:10:51 GMT https://svn.boost.org/trac10/ticket/12155#comment:2 https://svn.boost.org/trac10/ticket/12155#comment:2 <ul> <li><strong>status</strong> <span class="trac-field-old">assigned</span> → <span class="trac-field-new">closed</span> </li> <li><strong>resolution</strong> → <span class="trac-field-new">fixed</span> </li> </ul> Ticket