 There is an issue if the operator exists only for type <code class="computeroutput"><span class="identifier">A</span></code> and <code class="computeroutput"><span class="identifier">B</span></code>
            is convertible to <code class="computeroutput"><span class="identifier">A</span></code>.
            In this case, the compiler will report an ambiguous overload.
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">A</span> <span class="special">{</span> <span cl