[BUGFIX release] Fix types for getOwner and GlimmerComponent

type-tests/preview/@ember/owner-tests.ts

@@ -6,7 +6,11 @@ import Owner, {
   Resolver,
   KnownForTypeResult,
 } from '@ember/owner';
+import Component from '@glimmer/component';
 import { expectTypeOf } from 'expect-type';
+// TODO: once we move the runtime export to `@ember/owner`, update this import
+// as well. (That's why it's tested in this module!)
+import { getOwner } from '@ember/application';
 
 // Just a class we can construct in the Factory and FactoryManager tests
 declare class ConstructThis {
@@ -143,6 +147,30 @@ typedStrings.map((aString) => owner.lookup(aString));
 const aConstName = 'type:name';
 expectTypeOf(owner.lookup(aConstName)).toBeUnknown();
 
+// Check handling with Glimmer components carrying a Signature: they should
+// properly resolve to `Owner`, *not* `Owner | undefined`.
+interface Sig<T> {
+  Args: {
+    name: string;
+    age: number;
+    extra: T;
+  };
+  Element: HTMLParagraphElement;
+  Blocks: {
+    default: [greeting: string];
+    extra: [T];
+  };
+}
+
+class ExampleComponent<T> extends Component<Sig<T>> {
+  checkThis() {
+    expectTypeOf(getOwner(this)).toEqualTypeOf<Owner>();
+  }
+}
+
+declare let example: ExampleComponent<string>;
+expectTypeOf(getOwner(example)).toEqualTypeOf<Owner>();
+
 // ----- Minimal further coverage for POJOs ----- //
 // `Factory` and `FactoryManager` don't have to deal in actual classes. :sigh:
 const Creatable = {

types/preview/@ember/application/index.d.ts

@@ -122,15 +122,29 @@ declare module '@ember/application' {
   // whenever we add new base classes to the framework. For example, if we
   // introduce a standalone `Service` or `Route` base class which *does not*
   // extend from `EmberObject`, it will need to be added here.
-  type FrameworkObject = EmberObject | GlimmerComponent;
+  //
+  // NOTE: we use `any` here because we need to make sure *not* to fix the
+  // actual GlimmerComponent type; using `unknown` or `{}` or `never` (the
+  // obvious alternatives here) results in a version which is too narrow, such
+  // that any subclass which applies a signature does not get resolved by the
+  // definition of `getOwner()` below.
+  type KnownFrameworkObject = EmberObject | GlimmerComponent<any>;
 
   /**
    * Framework objects in an Ember application (components, services, routes, etc.)
    * are created via a factory and dependency injection system. Each of these
    * objects is the responsibility of an "owner", which handled its
    * instantiation and manages its lifetime.
    */
-  export function getOwner(object: FrameworkObject): Owner;
+  // SAFETY: this first overload is, strictly speaking, *unsafe*. It is possible
+  // to do `let x = EmberObject.create(); getOwner(x);` and the result will *not*
+  // be `Owner` but instead `undefined`. However, that's quite unusual at this
+  // point, and more to the point we cannot actually distinguish a `Service`
+  // subclass from `EmberObject` at this point: `Service` subclasses `EmberObject`
+  // and adds nothing to it. Accordingly, if we want to catch `Service`s with this
+  // (and `getOwner(this)` for some service will definitely be defined!), it has
+  // to be this way. :sigh:
+  export function getOwner(object: KnownFrameworkObject): Owner;
   export function getOwner(object: unknown): Owner | undefined;
   /**
    * `setOwner` forces a new owner on a given object instance. This is primarily