title: Numeric literal operator error
body: <p>Why does this code:</p>
  
  <pre><code>constexpr float operator "" _deg(long double d) {
      // returns radians
      return d*3.1415926535/180;
  }
  
  static const float ANGLES[] = {-20_deg, -10_deg, 0_deg, 10_deg, 20_deg};
  </code></pre>
  
  <p>Produce 5 of these errors:</p>
  
  <blockquote>
    <p>error: unable to find numeric literal operator 'operator"" _deg'</p>
  </blockquote>
  
  <p>I am using GCC 4.7.3. (<code>arm-none-eabi-g++</code>, with the <code>-std=c++0x</code> flag).</p>