title: AngularJS inner ng-repeat not processing $index.$parent in function argument
body: <p>Could someone more experienced than I explain to me why this compiles:</p>
  
  <pre><code>    &lt;li class="btn dropdown top-stack breadcrumb-btn" ng-repeat="nodeName in selectedNodeNames"&gt;
          &lt;a class="dropdown-toggle btn-anchor"&gt;{{nodeName}}&lt;/a&gt;
          &lt;ul class="dropdown-menu"&gt;
              &lt;li ng-class="activeState($parent.$index,$index)" ng-repeat="node in selectedNodeAtLevel($index).children"&gt;
                  &lt;a ng-click="tabSelect($parent.$index,$index)"&gt;{{getIndexString(node)}}&lt;/a&gt;
              &lt;/li&gt;
          &lt;/ul&gt;
      &lt;/li&gt;
  </code></pre>
  
  <p>And the inner ng-repeat in this doesn't?</p>
  
  <pre><code>    &lt;li class="btn dropdown top-stack breadcrumb-btn" ng-repeat="nodeName in selectedNodeNames"&gt;
          &lt;a class="dropdown-toggle btn-anchor"&gt;{{nodeName}}&lt;/a&gt;
          &lt;ul class="dropdown-menu"&gt;
              &lt;li ng-class="activeState($parent.$index,$index)" ng-repeat="node in selectedNodeAtLevel($parent.$index).children"&gt;
                  &lt;a ng-click="tabSelect($parent.$index,$index)"&gt;{{getIndexString(node)}}&lt;/a&gt;
              &lt;/li&gt;
          &lt;/ul&gt;
      &lt;/li&gt;
  </code></pre>
  
  <p>Note that I am calling the selectedNodeAtLevel() function with $parent.$index, rather than just $index.  Why will it compile for the one and not the other?  And what can I do to achieve the same effect?</p>
  
  <p>(By "compile" I mean that it does not generate any HTML, just a commented-out copy of the offending line)</p>
  
  <p>Thanks for your patience!</p>