[NullVoxPopuli-ai-agent]

Merge #21726 first. This PR sits on top of it. Review only the last commit, ccc024be55.

With EMBER_DROP_CLASSIC_FEATURES=true, Route from @ember/routing/route no longer extends EmberObject or the ActionHandler mixin. It extends a private plain base class, which extends no other class.

import Route from '@ember/routing/route';
import { service } from '@ember/service';

export default class PostsRoute extends Route {
  @service store;

  queryParams = {
    page: { refreshModel: true },
  };

  constructor(owner) {
    super(owner);
    this.cache = new Map();
  }

  model({ page }) {
    return this.store.query('post', { page });
  }

  willDestroy() {
    super.willDestroy(...arguments);
    this.cache.clear();
  }
}

Behavior with the flag

• The owner passes itself to the constructor. getOwner(this) and @service work in the constructor.
• Model hooks, queryParams, @action handlers and send work as before.
• willDestroy() stays the teardown hook. It runs once, when the owner is destroyed or when route.destroy() is called. isDestroyed(route) is then true.
• init, get, set, extend, reopen, isDestroying and isDestroyed do not exist on the class.
• A static create stays, because the container creates every instance through it. A route without an owner is allowed, as on the classic class.

Without the flag, Route does not change. A cast keeps the published type as the classic class, so apps get no new type errors.

Design

The class body is the same in both modes. Only the base class changes with the flag. Two parts of the classic class needed a plain equivalent:

Classic part	With the flag
Route.reopen({...}) sets queryParams, templateName, controllerName, send and actions	The same object goes on Route.prototype
send asserts on this.isDestroying and this.isDestroyed	send uses isDestroying() and isDestroyed() from @glimmer/destroyable, in both modes

The @computed getters _qp and _store and the get() calls in the class body work on plain objects, so they did not change.

The flag build does not merge queryParams across subclasses. The merge comes from Route.extend(), which does not exist with the flag. A native subclass field replaces the queryParams of its parent in both modes.

The plain base has a destroy() method, which calls the destroy function of @glimmer/destroyable, and an empty willDestroy() method. If an instance overrides willDestroy, the constructor registers it as a destructor. Route overrides willDestroy to tear down its views, so that teardown also runs in the flag build.

Tests

Change	Why
New @ember/routing/tests/system/route_drop_classic_features_test.js	Checks the plain base: no EmberObject, owner in the constructor, willDestroy on both destroy paths, the view teardown of Route, and a route with a model hook and query params in an application. Registers only with the flag.
New ember/tests/without-EMBER_DROP_CLASSIC_FEATURES/route_test.js	Checks the classic API in builds without the flag: the EmberObject base, init, properties from create, the queryParams merge of Route.extend, get/set, willDestroy, the destroy flags, and this._super in a hook. Registers only without the flag.
init() to constructor(owner) in Route subclasses of six test files	Works on both base classes
this._super(...arguments) to super.setupController(...arguments)	Works on both base classes
The route unit tests set properties after create(), read with get(), and destroy with the destroy function	Works on both base classes
The test of the queryParams array assertion skips with the flag	The assertion comes from the merge of Route.extend()

Checks

Mode	Result
Default	9241 tests, 0 failures
ALL_DEPRECATIONS_ENABLED=true	9241 tests, 0 failures
OVERRIDE_DEPRECATION_VERSION=15.0.0	8264 tests, 0 failures
Production build	9078 tests, 0 failures
EMBER_DROP_CLASSIC_FEATURES=true	9240 tests, 0 failures

The type checks of the internals and the published types pass, with and without stable decorators. eslint, prettier and the docs check pass.

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