[BUGFIX] Ensure QP definitions interop with tracked props

This PR ensures that QPs can autotrack getters/setters and tracked
props. It includes a couple of manual flushes of async observers in
order to support legacy sync behaviors of QPs.

packages/@ember/-internals/metal/lib/observer.ts

@@ -162,7 +162,7 @@ export function revalidateObservers(target: object) {
 
 let lastKnownRevision = 0;
 
-export function flushAsyncObservers() {
+export function flushAsyncObservers(shouldSchedule = true) {
   if (lastKnownRevision === value(CURRENT_TAG)) {
     return;
   }
@@ -179,14 +179,20 @@ export function flushAsyncObservers() {
 
     activeObservers.forEach((observer, eventName) => {
       if (!validate(observer.tag, observer.lastRevision)) {
-        schedule('actions', () => {
+        let sendObserver = () => {
           try {
             sendEvent(target, eventName, [target, observer.path]);
           } finally {
             observer.tag = combine(getChainTagsForKey(target, observer.path));
             observer.lastRevision = value(observer.tag);
           }
-        });
+        };
+
+        if (shouldSchedule) {
+          schedule('actions', sendObserver);
+        } else {
+          sendObserver();
+        }
       }
     });
   });

packages/@ember/-internals/routing/lib/system/route.ts

@@ -1,7 +1,10 @@
 import { OwnedTemplate, TemplateFactory } from '@ember/-internals/glimmer';
 import {
+  addObserver,
   computed,
   defineProperty,
+  descriptorForProperty,
+  flushAsyncObservers,
   get,
   getProperties,
   isEmpty,
@@ -17,9 +20,12 @@ import {
   setFrameworkClass,
   typeOf,
 } from '@ember/-internals/runtime';
+import { lookupDescriptor } from '@ember/-internals/utils';
+import { EMBER_METAL_TRACKED_PROPERTIES } from '@ember/canary-features';
 import Controller from '@ember/controller';
 import { assert, deprecate, info, isTesting } from '@ember/debug';
 import { ROUTER_EVENTS } from '@ember/deprecated-features';
+import { dependentKeyCompat } from '@ember/object/compat';
 import { assign } from '@ember/polyfills';
 import { once } from '@ember/runloop';
 import { classify } from '@ember/string';
@@ -941,6 +947,12 @@ class Route extends EmberObject implements IRoute {
     if (this._environment.options.shouldRender) {
       this.renderTemplate(controller, context);
     }
+
+    // Setup can cause changes to QPs which need to be propogated immediately in
+    // some situations. Eventually, we should work on making these async somehow.
+    if (EMBER_METAL_TRACKED_PROPERTIES) {
+      flushAsyncObservers(false);
+    }
   }
 
   /*
@@ -2005,7 +2017,22 @@ function mergeEachQueryParams(controllerQP: {}, routeQP: {}) {
 
 function addQueryParamsObservers(controller: any, propNames: string[]) {
   propNames.forEach(prop => {
-    controller.addObserver(`${prop}.[]`, controller, controller._qpChanged);
+    if (descriptorForProperty(controller, prop) === undefined) {
+      let desc = lookupDescriptor(controller, prop);
+
+      if (desc !== null && (typeof desc.get === 'function' || typeof desc.set === 'function')) {
+        defineProperty(
+          controller,
+          prop,
+          dependentKeyCompat({
+            get: desc.get,
+            set: desc.set,
+          })
+        );
+      }
+    }
+
+    addObserver(controller, `${prop}.[]`, controller, controller._qpChanged, false);
   });
 }
 
@@ -2495,6 +2522,7 @@ Route.reopen(ActionHandler, Evented, {
       let router = this._router;
       let qpMeta = router._queryParamsFor(routeInfos);
       let changes = router._qpUpdates;
+      let qpUpdated = false;
       let replaceUrl;
 
       stashParamNames(router, routeInfos);
@@ -2543,6 +2571,8 @@ Route.reopen(ActionHandler, Evented, {
           }
 
           set(controller, qp.prop, value);
+
+          qpUpdated = true;
         }
 
         // Stash current serialized value of controller.
@@ -2558,6 +2588,12 @@ Route.reopen(ActionHandler, Evented, {
         }
       }
 
+      // Some QPs have been updated, and those changes need to be propogated
+      // immediately. Eventually, we should work on making this async somehow.
+      if (EMBER_METAL_TRACKED_PROPERTIES && qpUpdated === true) {
+        flushAsyncObservers(false);
+      }
+
       if (replaceUrl) {
         transition.method('replace');
       }

packages/ember/tests/routing/query_params_test.js

@@ -3,7 +3,7 @@ import { dasherize } from '@ember/string';
 import { RSVP, Object as EmberObject, A as emberA } from '@ember/-internals/runtime';
 import { run } from '@ember/runloop';
 import { peekMeta } from '@ember/-internals/meta';
-import { get, computed } from '@ember/-internals/metal';
+import { get, computed, tracked } from '@ember/-internals/metal';
 import { Route } from '@ember/-internals/routing';
 import { PARAMS_SYMBOL } from 'router_js';
 
@@ -1581,5 +1581,71 @@ moduleFor(
       let controller = this.getController('constructor');
       assert.equal(get(controller, 'foo'), '999');
     }
+
+    async ['@test Single query params defined with tracked properties can be on the controller and reflected in the url'](
+      assert
+    ) {
+      assert.expect(3);
+
+      this.router.map(function() {
+        this.route('home', { path: '/' });
+      });
+
+      this.add(
+        `controller:home`,
+        Controller.extend({
+          queryParams: ['foo'],
+          foo: tracked(),
+        })
+      );
+
+      await this.visitAndAssert('/');
+      let controller = this.getController('home');
+
+      controller.foo = '456';
+      await runLoopSettled();
+      this.assertCurrentPath('/?foo=456');
+
+      controller.foo = '987';
+      await runLoopSettled();
+      this.assertCurrentPath('/?foo=987');
+    }
+
+    async ['@test Single query params defined with native getters and tracked properties can be on the controller and reflected in the url'](
+      assert
+    ) {
+      assert.expect(3);
+
+      this.router.map(function() {
+        this.route('home', { path: '/' });
+      });
+
+      this.add(
+        `controller:home`,
+        Controller.extend({
+          queryParams: ['foo'],
+          get foo() {
+            return this.bar;
+          },
+
+          set foo(value) {
+            this.bar = value;
+          },
+
+          bar: tracked(),
+        })
+      );
+
+      await this.visitAndAssert('/');
+      let controller = this.getController('home');
+
+      controller.bar = '456';
+      await runLoopSettled();
+      this.assertCurrentPath('/?foo=456');
+
+      controller.bar = '987';
+      await runLoopSettled();
+      this.assertCurrentPath('/?foo=987');
+    }
   }
 );