<div dir="ltr">I don&#39;t see it in P0096R5, although <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0426r1.html">http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0426r1.html</a> recommended it.<div><br></div><div>It seems to be useful to know whether you can use char_traits&lt;char&gt;::length() in a constexpr function, or whether you need to write your own.</div><div><br></div><div><br></div></div>