title: `.' cannot appear in a constant-expression
body: <p>I'm getting the following error:</p>
  
  <pre><code>`.' cannot appear in a constant-expression
  </code></pre>
  
  <p>for this function (line 4):</p>
  
  <pre><code>    bool Covers(const Region&lt;C,V,D&gt;&amp; other) const {
          const Region&amp; me = *this;
          for (unsigned d = 0; d &lt; D; d++) {
              if (me[d].min &gt; other[d].min || me[d].max &lt; other[d].max) {
                  return false;
              }
          }
  </code></pre>
  
  <p>can anyone explain the problem please?</p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>the definition of Region is:</p>
  
  <pre><code>template &lt;typename C, typename V, unsigned D&gt;
  class Region : public boost::array&lt;Detail::Range&lt;C&gt;,D&gt;
  </code></pre>
  
  <p>when <code>Range</code> has a <code>min</code> and <code>max</code> variables.</p>