refactor($compile): allow transclude data to be GCed after a non-cloning transclusion

Author: jbedard

src/ng/compile.js

@@ -2205,6 +2205,10 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
         // This is the function that is injected as `$transclude`.
         // Note: all arguments are optional!
         function controllersBoundTransclude(scope, cloneAttachFn, futureParentElement, slotName) {
+          if (!boundTranscludeFn) {
+            throw $compileMinErr('multitransclude', 'This element has already been transcluded.');
+          }
+
           var transcludeControllers;
           // No scope passed in:
           if (!isScope(scope)) {
@@ -2221,16 +2225,21 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
             futureParentElement = hasElementTranscludeDirective ? $element.parent() : $element;
           }
           if (slotName) {
-            var slotTranscludeFn = boundTranscludeFn.$$slots[slotName];
-            if (!slotTranscludeFn) {
+            boundTranscludeFn = boundTranscludeFn.$$slots[slotName];
+            if (!boundTranscludeFn) {
               throw $compileMinErr('noslot',
                'No parent directive that requires a transclusion with slot name "{0}". ' +
                'Element: {1}',
                slotName, startingTag($element));
             }
-            return slotTranscludeFn(scope, cloneAttachFn, transcludeControllers, futureParentElement, scopeToChild);
           }
-          return boundTranscludeFn(scope, cloneAttachFn, transcludeControllers, futureParentElement, scopeToChild);
+
+          var res = boundTranscludeFn(scope, cloneAttachFn, transcludeControllers, futureParentElement, scopeToChild);
+          //Clear references not required if this transcluded the original nodes
+          if (!cloneAttachFn) {
+            boundTranscludeFn = scopeToChild = elementControllers = $element = null;
+          }
+          return res;
         }
       }
     }

test/ng/compileSpec.js

@@ -6015,6 +6015,24 @@ describe('$compile', function() {
       });
 
 
+      it('should throw if a transcluded node is transcluded again', function() {
+        module(function() {
+          directive('trans', valueFn({
+            transclude: true,
+            link: function(scope, element, attr, ctrl, $transclude) {
+              $transclude();
+              $transclude();
+            }
+          }));
+        });
+        inject(function($rootScope, $compile) {
+          expect(function() {
+            $compile('<trans></trans>')($rootScope);
+          }).toThrowMinErr('$compile', 'multitransclude', 'This element has already been transcluded.');
+        });
+      });
+
+
       it('should not leak if two "element" transclusions are on the same element (with debug info)', function() {
         if (jQuery) {
           // jQuery 2.x doesn't expose the cache storage.