fix(common): properly get root nodes from embedded views with <ng-con…

…tent>

This commit fixes 2 separate issues related to root nodes retrieval from
embedded views with `<ng-content>`:

1) we did not account for the case where there were no projectable nodes
for a given `<ng-content>`;

2) we did not account for the case where projectable nodes for a given
`<ng-content>` were represented as an array of native nodes (happens in
the case of dynamically created components with projectable nodes);

Fixes angular#35967

packages/core/src/render3/component_ref.ts

@@ -199,7 +199,7 @@ export class ComponentFactory<T> extends viewEngine_ComponentFactory<T> {
         }
       }
 
-      tElementNode = getTNode(rootLView[TVIEW], 0) as TElementNode;
+      tElementNode = getTNode(rootTView, 0) as TElementNode;
 
       if (projectableNodes) {
         // projectable nodes can be passed as array of arrays or an array of iterables (ngUpgrade

packages/core/src/render3/view_ref.ts

@@ -335,11 +335,19 @@ function collectNativeNodes(
     } else if (tNodeType === TNodeType.Projection) {
       const componentView = lView[DECLARATION_COMPONENT_VIEW];
       const componentHost = componentView[T_HOST] as TElementNode;
-      const parentView = getLViewParent(componentView);
-      let firstProjectedNode: TNode|null =
-          (componentHost.projection as(TNode | null)[])[tNode.projection as number];
-      if (firstProjectedNode !== null && parentView !== null) {
-        collectNativeNodes(parentView[TVIEW], parentView, firstProjectedNode, result, true);
+      const projectionSlots = componentHost.projection;
+      const slotIdx = tNode.projection as number;
+
+      if (projectionSlots !== null && projectionSlots.length > slotIdx) {
+        const nodesInSlot = projectionSlots[slotIdx];
+        if (Array.isArray(nodesInSlot)) {
+          result.push(...nodesInSlot);
+        } else {
+          const parentView = getLViewParent(componentView);
+          if (parentView !== null) {
+            collectNativeNodes(parentView[TVIEW], parentView, nodesInSlot, result, true);
+          }
+        }
       }
     }
     tNode = isProjection ? tNode.projectionNext : tNode.next;

packages/core/test/acceptance/template_ref_spec.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {Component, TemplateRef, ViewChild, ViewContainerRef} from '@angular/core';
+import {Component, ComponentFactoryResolver, Injector, NgModule, TemplateRef, ViewChild, ViewContainerRef} from '@angular/core';
 import {TestBed} from '@angular/core/testing';
 import {expect} from '@angular/platform-browser/testing/src/matchers';
 import {ivyEnabled, onlyInIvy} from '@angular/private/testing';
@@ -182,5 +182,50 @@ describe('TemplateRef', () => {
         expect(rootNodes.length).toBe(7);
       }
     });
+
+    it('should return an empty array for an embedded view with projection and no projectable nodes',
+       () => {
+         const rootNodes =
+             getRootNodes(`<ng-template #templateRef><ng-content></ng-content></ng-template>`);
+         // VE will, incorrectly, return an additional comment node in this case
+         expect(rootNodes.length).toBe(ivyEnabled ? 0 : 1);
+       });
+
+    it('should return projectable nodes provided to a dynamically created component', () => {
+
+      @Component({
+        selector: 'dynamic',
+        template: '<ng-template #templateRef><ng-content></ng-content></ng-template>'
+      })
+      class DynamicCmp {
+        @ViewChild('templateRef', {static: true})
+        templateRef !: TemplateRef<any>;
+      }
+
+      @NgModule({
+        declarations: [DynamicCmp],
+        entryComponents: [DynamicCmp],
+      })
+      class WithDynamicCmpModule {
+      }
+
+      @Component({selector: 'test', template: ''})
+      class TestCmp {
+        constructor(public cfr: ComponentFactoryResolver) {}
+      }
+
+      TestBed.configureTestingModule({
+        declarations: [TestCmp],
+        imports: [WithDynamicCmpModule],
+      });
+      const fixture = TestBed.createComponent(TestCmp);
+      const dynamicCmptFactory = fixture.componentInstance.cfr.resolveComponentFactory(DynamicCmp);
+
+      const cmptRef =
+          dynamicCmptFactory.create(Injector.NULL, [[document.createTextNode('textNode')]]);
+      const viewRef = cmptRef.instance.templateRef.createEmbeddedView({});
+      // VE will, incorrectly, return an additional comment node in this case
+      expect(viewRef.rootNodes.length).toBe(ivyEnabled ? 1 : 2);
+    });
   });
 });