title: Are exception descriptions from exception::what() standarized for standard exceptions?
body: <p>For standardized exceptions like <code>std::bad_alloc</code>, is the string returned by <code>exception::what()</code> expected to be the same across compilers?</p>
  
  <p>For example, several compilers I've worked with all return <code>bad allocation</code> for <code>bad_alloc::what()</code>.  Is there some reason a more descriptive string such as <code>Memory allocation failure</code> isn't returned? </p>