title: std::map::clear and elements' destructors
body: <p>Does destructor get called on <code>std::map</code> elements when <code>std::map::clear</code> is used? </p>
  
  <p>I tried to debug for <code>std::map&lt;string,string&gt;</code> but could not see <code>std::string</code> destructor getting invoked. Can any one please help my understanding?</p>
  
  <p>Documentation states it gets called, but I could not notice it.</p>