decltype - "the only context in which a variable defined as a reference is not treated as a synonym for the object to which it refers"?
<p>I'm reading C++ Primer, 5th Ed., where on p. 71 they first give this code example:</p>

<pre><code>const int ci = 0, &amp;cj = ci;
decltype(ci) x = 0;
decltype(cj) y = x;
decltype(cj) z; //error
</code></pre>

<p>Then they say:</p>

<blockquote>
  <p>It is worth noting that <code>decltype</code> is the only context in which a variable defined as a reference is not treated as a synonym for the object to which it refers.</p>
</blockquote>

<p>What do they mean by this? I don't get it. The <code>y</code> there refers to <code>x</code>. So what's the catch?</p>
