mp;</span><span class=identifier>employee</span><span class=special>::</span><span class=identifier>salary</span><span class=special>&gt;</span>
    <span class=special>&gt;</span>
  <span class=special>&gt;</span>
<span class=special>&gt;</span> <span class=identifier>employee_set</span><span class=special>;</span>
</pre></blockquote>

<p>
The problem here is that the type of <code>&amp;employee::salary</code>, which is
<a href="https://en.cppreference.com/w/cpp/language/member_functions#const-.2C_volatile