te">&#8220;<span class="quote"><span class="emphasis"><em>In a future revision of C++, it might make sense to relax
      the restriction on instantiating standard library templates with incomplete
      types. Clearly, the general prohibition should stay in place - instantiating
      templates with incomplete types is a delicate business, and there are too many
      classes in the standard library where it would make no sense. But perhaps it
      should be relaxed on a case-by-case basis, and <code clas