title: overloading std::to_string and std::to_chars for a custom type?
body: <p>I have an arithmetic custom type with a <code>to_string()</code> member. I'm thinking about overloading <code>std::to_string</code> in the <code>std</code> namespace for the type, but would this count as namespace pollution?</p>
  
  <p>EDIT:
  I'm thinking about this, so that this expression SFINAE would work for the type:
  <code>-&gt; decltype(std::to_string(std::declval&lt;T&gt;()), void(0))</code></p>