title: Constant as rvalue in C++(11)
body: <p>Why <code>const int</code> is <strong>not</strong> an R-value in C++(11)? I thought that R-value was 'anything' which cannot be on the left hand side and constants fulfil that. This code fails:</p>
  
  <pre><code>int f(int &amp;&amp; x) { return 100; }
  
  void g() {
    const int x = 1;
    f(x);
  }
  
  error: invalid initialization of reference of type ‘int&amp;&amp;’ from expression
  of type ‘const int’
  </code></pre>