 macro <code class="computeroutput"><span class="identifier">BOOST_MPL_ASSERT_MSG</span><span class="special">()</span></code> which essentially is a more powerful version
      of static_assert. Unfortunately under certain circumstances using this macro
      may lead to the aforementioned linker errors.
    </p>
<p>
      <a href="http://boost-spirit.com" target="_top">Spirit</a> allows you to define a
      preprocessor constant disabling the usage of <code class="computeroutput"><span class="identifier"