htforward to link C++03 and C++11 code together.
</p><p> Because <code class="classname">std::string</code> is used extensively
  throughout the library a number of other types are also defined twice,
  including the stringstream classes and several facets used by
  <code class="classname">std::locale</code>. The standard facets which are always
  installed in a locale may be present twice, with both ABIs, to ensure that
  code like
  <code class="code">std::use_facet&lt;std::time_get&lt;char&gt;&gt;(locale