fix(core): don’t throw if queries change during change detection.

Throwing on query changes would be a breaking change compared to v2.
Also discovers a bug with querying manually projected content, see #15117.

Related to #14748
Closes #14925

packages/core/src/view/view.ts

@@ -318,12 +318,10 @@ function createViewNodes(view: ViewData) {
 export function checkNoChangesView(view: ViewData) {
   Services.updateDirectives(view, CheckType.CheckNoChanges);
   execEmbeddedViewsAction(view, ViewAction.CheckNoChanges);
-  execQueriesAction(
-      view, NodeFlags.TypeContentQuery, NodeFlags.DynamicQuery, CheckType.CheckNoChanges);
   Services.updateRenderer(view, CheckType.CheckNoChanges);
   execComponentViewsAction(view, ViewAction.CheckNoChanges);
-  execQueriesAction(
+  // Note: We don't check queries for changes as we didn't do this in v2.x.
-      view, NodeFlags.TypeViewQuery, NodeFlags.DynamicQuery, CheckType.CheckNoChanges);
+  // TODO(tbosch): investigate if we can enable the check again in v5.x with a nicer error message.
 }
 
 export function checkAndUpdateView(view: ViewData) {

packages/core/test/linker/query_integration_spec.ts

@@ -536,6 +536,29 @@ export function main() {
         expect(q.query.length).toBe(0);
       });
 
+      it('should not throw if a content template is queried and created in the view during change detection',
+         () => {
+           @Component(
+               {selector: 'auto-projecting', template: '<div *ngIf="true; then: content"></div>'})
+           class AutoProjecting {
+             @ContentChild(TemplateRef)
+             content: TemplateRef<any>;
+
+             @ContentChildren(TextDirective)
+             query: QueryList<TextDirective>;
+           }
+
+           TestBed.configureTestingModule({declarations: [AutoProjecting]});
+           const template =
+               '<auto-projecting #q><ng-template><div text="1"></div></ng-template></auto-projecting>';
+           const view = createTestCmpAndDetectChanges(MyComp0, template);
+
+           const q = view.debugElement.children[0].references['q'];
+           // This should be 1, but due to
+           // https://github.com/angular/angular/issues/15117 this is 0.
+           expect(q.query.length).toBe(0);
+         });
+
     });
   });
 }

packages/core/test/view/query_spec.ts

@@ -369,37 +369,6 @@ export function main() {
     });
 
     describe('general binding behavior', () => {
-      it('should checkNoChanges', () => {
-        const {view} = createAndGetRootNodes(compViewDef([
-          elementDef(NodeFlags.None, null, null, 3, 'div'),
-          ...contentQueryProviders(),
-          anchorDef(NodeFlags.EmbeddedViews, null, null, 0, null, embeddedViewDef([
-                      elementDef(NodeFlags.None, null, null, 1, 'div'),
-                      aServiceProvider(),
-                    ])),
-        ]));
-
-        Services.checkAndUpdateView(view);
-        Services.checkNoChangesView(view);
-
-        const childView = Services.createEmbeddedView(view, view.def.nodes[3]);
-        attachEmbeddedView(view, asElementData(view, 3), 0, childView);
-
-        let err: any;
-        try {
-          Services.checkNoChangesView(view);
-        } catch (e) {
-          err = e;
-        }
-        expect(err).toBeTruthy();
-        expect(err.message)
-            .toBe(
-                `ExpressionChangedAfterItHasBeenCheckedError: Expression has changed after it was checked. Previous value: 'Query 1 not dirty'. Current value: 'Query 1 dirty'.`);
-        const debugCtx = getDebugContext(err);
-        expect(debugCtx.view).toBe(view);
-        expect(debugCtx.nodeIndex).toBe(2);
-      });
-
       it('should report debug info on binding errors', () => {
         class QueryService {
           set a(value: any) { throw new Error('Test'); }