What are the rules for function pointers and member function pointers to Standard functions?
<p>What are the existing rules for taking function pointers or member function pointers to Standard functions? For example, something like</p>

<pre><code>auto p = &amp;std::string::size;
</code></pre>

<p>Is this legal? Would it be more or less legal if I explicitly requested the correct type, so it would function even if there was an additional implementation-added overload of <code>std::string::size</code>?</p>
