title: XCode 6: Unable to create watchpoint
body: <p>I am trying to watch the following variable </p>
  
  <pre><code>vector&lt;Vec3f&gt; lines[2];
  </code></pre>
  
  <p>in XCode (where <code>Vec3f</code> is an OpenCV datatype, a vector of 3 floats).
  But when I right-click the variable in Variable View and choose <code>Watch "lines"</code>, I am being yelled at by XCode:</p>
  
  <blockquote>
    <p>error: Watchpoint creation failed (addr=0x16fd92d48, size=48, variable
    expression='lines'). error: watch size of 48 is not supported</p>
  </blockquote>
  
  <p>This seems to happen with other variables of type <code>vector&lt;T&gt;</code> as well, but only if it is a local variable. I can watch the <code>vector</code> passed in as a method parameter just fine.</p>
  
  <pre><code>double computeReprojectionError(vector&lt;Point2f&gt;&amp; imgpts1, vector&lt;Point2f&gt;&amp;   imgpts2, Mat&amp; inlier_mask, const Mat&amp; F)
  {
                                                // ^ I can watch this guy
      vector&lt;Vec3f&gt; lines[2]; // &lt;- I cannot watch this guy (size 48)
  
      vector&lt;Point2f&gt; imgpts1_copy(npt), // &lt;- I cannot watch this guy (size 24)
      imgpts2_copy(npt);
  
  ...
  </code></pre>
  
  <p>I googled the error with no success. Can somebody shed light on the matter?</p>