Validate assignability rules for ComponentLike and friends

packages/core/__tests__/language-server/diagnostic-augmentation.test.ts

@@ -792,7 +792,7 @@ describe('Language Server: Diagnostic Augmentation', () => {
         },
         {
           "message": "The {{component}} helper can't be used to directly invoke a component under Glint. Consider first binding the result to a variable, e.g. '{{#let (component 'component-name') as |ComponentName|}}' and then invoking it as '<ComponentName @arg={{value}} />'.
-        Argument of type 'Invokable<(named?: PrebindArgs<{ message?: string | undefined; }, \\"message\\"> | undefined) => ComponentReturn<FlattenBlockParams<{ default: { Params: { Positional: []; }; }; }>, null>>' is not assignable to parameter of type 'ContentValue'.",
+        Argument of type 'Invokable<(named?: PrebindArgs<{ message?: string | undefined; }, \\"message\\"> | undefined) => ComponentReturn<FlattenBlockParams<{ default: { Params: { Positional: []; }; }; }>, unknown>>' is not assignable to parameter of type 'ContentValue'.",
           "range": {
             "end": {
               "character": 41,
@@ -827,7 +827,7 @@ describe('Language Server: Diagnostic Augmentation', () => {
         },
         {
           "message": "The {{component}} helper can't be used to directly invoke a component under Glint. Consider first binding the result to a variable, e.g. '{{#let (component 'component-name') as |ComponentName|}}' and then invoking it as '<ComponentName @arg={{value}}>...</ComponentName>'.
-        Argument of type 'Invokable<(named?: PrebindArgs<{ message?: string | undefined; }, \\"message\\"> | undefined) => ComponentReturn<FlattenBlockParams<{ default: { Params: { Positional: []; }; }; }>, null>>' is not assignable to parameter of type 'ComponentReturn<any, any>'.",
+        Argument of type 'Invokable<(named?: PrebindArgs<{ message?: string | undefined; }, \\"message\\"> | undefined) => ComponentReturn<FlattenBlockParams<{ default: { Params: { Positional: []; }; }; }>, unknown>>' is not assignable to parameter of type 'ComponentReturn<any, any>'.",
           "range": {
             "end": {
               "character": 56,

packages/core/__tests__/language-server/diagnostics.test.ts

@@ -59,7 +59,7 @@ describe('Language Server: Diagnostics', () => {
       expect(templateDiagnostics).toMatchInlineSnapshot(`
         [
           {
-            "message": "Property 'missingArg' does not exist on type 'EmptyObject'.",
+            "message": "Property 'missingArg' does not exist on type '{}'.",
             "range": {
               "end": {
                 "character": 13,
@@ -118,7 +118,7 @@ describe('Language Server: Diagnostics', () => {
 
       expect(diagnostics).toMatchObject([
         {
-          message: "Property 'foo' does not exist on type 'EmptyObject'.",
+          message: "Property 'foo' does not exist on type '{}'.",
           source: 'glint:ts(2339)',
         },
       ]);
@@ -159,7 +159,7 @@ describe('Language Server: Diagnostics', () => {
 
       expect(diagnostics).toMatchObject([
         {
-          message: "Property 'foo' does not exist on type 'EmptyObject'.",
+          message: "Property 'foo' does not exist on type '{}'.",
           source: 'glint:ts(2339)',
         },
       ]);
@@ -358,7 +358,7 @@ describe('Language Server: Diagnostics', () => {
     expect(server.getDiagnostics(project.fileURI('component-a.ts'))).toMatchInlineSnapshot(`
       [
         {
-          "message": "Property 'version' does not exist on type 'EmptyObject'.",
+          "message": "Property 'version' does not exist on type '{}'.",
           "range": {
             "end": {
               "character": 36,

packages/environment-ember-loose/-private/dsl/integration-declarations.d.ts

@@ -3,7 +3,6 @@
 import { ComponentLike, HelperLike, ModifierLike } from '@glint/template';
 import {
   Context,
-  EmptyObject,
   FlattenBlockParams,
   HasContext,
   TemplateContext,
@@ -85,15 +84,15 @@ declare module '@ember/routing/route' {
     [Context]: TemplateContext<
       Controller & ModelField<ModelForRoute<this>>,
       ModelField<ModelForRoute<this>>,
-      EmptyObject,
+      {},
       null
     >;
   }
 }
 
 declare module '@ember/controller' {
   export default interface Controller {
-    [Context]: TemplateContext<this, ModelField<this['model']>, EmptyObject, null>;
+    [Context]: TemplateContext<this, ModelField<this['model']>, {}, null>;
   }
 }
 
@@ -103,9 +102,7 @@ declare module '@ember/controller' {
 import '@ember/test-helpers';
 import 'ember-cli-htmlbars';
 
-type TestTemplate<T> = abstract new () => HasContext<
-  TemplateContext<T, EmptyObject, EmptyObject, void>
->;
+type TestTemplate<T> = abstract new () => HasContext<TemplateContext<T, {}, {}, void>>;
 
 declare module '@ember/test-helpers' {
   export function render<T>(template: TestTemplate<T>): Promise<void>;

packages/environment-ember-loose/-private/intrinsics/component.d.ts

@@ -1,7 +1,6 @@
 import { WithBoundArgs } from '@glint/template';
 import {
   ComponentReturn,
-  EmptyObject,
   DirectInvokable,
   InvokableInstance,
   Invokable,
@@ -14,8 +13,8 @@ import {
 type ComponentNamedArgs<Component> = Component extends Invokable<(...args: infer Args) => any>
   ? Args extends [...positional: infer _, named?: infer Named]
     ? UnwrapNamedArgs<Named>
-    : EmptyObject
-  : EmptyObject;
+    : {}
+  : {};
 
 type PartiallyAppliedComponent<Component, Args> = Component extends Invokable<AnyFunction>
   ? WithBoundArgs<

packages/environment-ember-loose/__tests__/type-tests/ember-component.test.ts

@@ -7,7 +7,6 @@ import {
   NamedArgsMarker,
 } from '@glint/environment-ember-loose/-private/dsl';
 import { expectTypeOf } from 'expect-type';
-import { EmptyObject } from '@glint/template/-private/integration';
 import type { ComponentLike } from '@glint/template';
 
 {
@@ -19,12 +18,6 @@ import type { ComponentLike } from '@glint/template';
     }
   }
 
-  resolve(NoArgsComponent)({
-    // @ts-expect-error: extra named arg
-    foo: 'bar',
-    ...NamedArgsMarker,
-  });
-
   resolve(NoArgsComponent)(
     // @ts-expect-error: extra positional arg
     'oops'
@@ -50,7 +43,7 @@ import type { ComponentLike } from '@glint/template';
       templateForBackingValue(this, function* (𝚪) {
         expectTypeOf(𝚪.this.foo).toEqualTypeOf<string>();
         expectTypeOf(𝚪.this).toEqualTypeOf<StatefulComponent>();
-        expectTypeOf(𝚪.args).toEqualTypeOf<EmptyObject>();
+        expectTypeOf(𝚪.args).toEqualTypeOf<{}>();
       });
     }
   }

packages/environment-ember-loose/__tests__/type-tests/glimmer-component.test.ts

@@ -6,19 +6,12 @@ import {
   emitComponent,
   NamedArgsMarker,
 } from '@glint/environment-ember-loose/-private/dsl';
-import { EmptyObject } from '@glint/template/-private/integration';
 import { expectTypeOf } from 'expect-type';
 import { ComponentLike } from '@glint/template';
 
 {
   class NoArgsComponent extends Component {}
 
-  resolve(NoArgsComponent)({
-    // @ts-expect-error: extra named arg
-    foo: 'bar',
-    ...NamedArgsMarker,
-  });
-
   resolve(NoArgsComponent)(
     // @ts-expect-error: extra positional arg
     'oops'
@@ -44,7 +37,7 @@ import { ComponentLike } from '@glint/template';
       templateForBackingValue(this, function* (𝚪) {
         expectTypeOf(𝚪.this.foo).toEqualTypeOf<string>();
         expectTypeOf(𝚪.this).toEqualTypeOf<StatefulComponent>();
-        expectTypeOf(𝚪.args).toEqualTypeOf<EmptyObject>();
+        expectTypeOf(𝚪.args).toEqualTypeOf<{}>();
       });
     }
   }

packages/environment-ember-loose/__tests__/type-tests/helper.test.ts

@@ -1,12 +1,12 @@
-import Helper, { helper, EmptyObject } from '@ember/component/helper';
+import Helper, { helper } from '@ember/component/helper';
 import { resolve } from '@glint/environment-ember-loose/-private/dsl';
 import {
   NamedArgsMarker,
   resolve as resolveWithoutFunctionResolution,
 } from '@glint/environment-ember-loose/-private/dsl/without-function-resolution';
 import { expectTypeOf } from 'expect-type';
 import { HelperLike } from '@glint/template';
-import { EmptyObject as GlintEmptyObject, NamedArgs } from '@glint/template/-private/integration';
+import { NamedArgs } from '@glint/template/-private/integration';
 
 // Functional helper: fixed signature params
 {
@@ -56,7 +56,9 @@ import { EmptyObject as GlintEmptyObject, NamedArgs } from '@glint/template/-pri
   let definition = helper(<T, U>([a, b]: [T, U]) => a || b);
   let or = resolve(definition);
 
-  expectTypeOf(or).toEqualTypeOf<{ <T, U>(t: T, u: U, named?: NamedArgs<EmptyObject>): T | U }>();
+  // Using `toMatch` rather than `toEqual` because helper resolution (currently)
+  // uses a special `EmptyObject` type to represent empty named args.
+  expectTypeOf(or).toMatchTypeOf<{ <T, U>(t: T, u: U, named?: NamedArgs<{}>): T | U }>();
 
   or('a', 'b', {
     // @ts-expect-error: extra named arg
@@ -158,12 +160,12 @@ import { EmptyObject as GlintEmptyObject, NamedArgs } from '@glint/template/-pri
   let repeat = resolve(RepeatHelper);
 
   expectTypeOf(repeat).toEqualTypeOf<{
-    <T>(value: T, count?: number | undefined, args?: NamedArgs<GlintEmptyObject>): Array<T>;
+    <T>(value: T, count?: number | undefined): Array<T>;
   }>();
 
   repeat(
     'hello',
-    // @ts-expect-error: extra named arg
+    // @ts-expect-error: unexpected named args
     { word: 'hi', ...NamedArgsMarker }
   );
 
@@ -190,9 +192,7 @@ import { EmptyObject as GlintEmptyObject, NamedArgs } from '@glint/template/-pri
 
   let maybeString = resolve(MaybeStringHelper);
 
-  expectTypeOf(maybeString).toEqualTypeOf<
-    (args?: NamedArgs<GlintEmptyObject>) => string | undefined
-  >();
+  expectTypeOf(maybeString).toEqualTypeOf<() => string | undefined>();
 }
 
 // Helpers are `HelperLike`

packages/environment-ember-loose/__tests__/type-tests/intrinsics/mut.test.ts

@@ -14,8 +14,8 @@ expectTypeOf(fn(mut('hello'))).toEqualTypeOf<(value: string) => void>();
 // @ts-expect-error: missing value
 mut();
 
+// @ts-expect-error: unexpected named args
 mut('hello', {
-  // @ts-expect-error: invalid named arg
   hello: 'hi',
   ...NamedArgsMarker,
 });

packages/environment-ember-loose/__tests__/type-tests/intrinsics/outlet.test.ts

@@ -9,8 +9,8 @@ expectTypeOf(outlet('outlet-name')).toEqualTypeOf<void>();
 // Nameless main outlet
 outlet();
 
+// @ts-expect-error: unexpected named args
 outlet('outlet-name', {
-  // @ts-expect-error: invalid named arg
   hello: 'hi',
   ...NamedArgsMarker,
 });

packages/environment-ember-loose/__tests__/type-tests/intrinsics/unbound.test.ts

@@ -10,8 +10,8 @@ expectTypeOf(unbound(123)).toEqualTypeOf<number>();
 // @ts-expect-error: missing value
 unbound();
 
+// @ts-expect-error: unexpected named args
 unbound('hello', {
-  // @ts-expect-error: invalid named arg
   hello: 'hi',
   ...NamedArgsMarker,
 });

packages/environment-ember-loose/__tests__/type-tests/intrinsics/unique-id.test.ts

@@ -6,8 +6,8 @@ let uniqueId = resolve(Globals['unique-id']);
 // Basic plumbing
 expectTypeOf(uniqueId()).toEqualTypeOf<string>();
 
+// @ts-expect-error: unexpected named args
 uniqueId({
-  // @ts-expect-error: invalid named arg
   hello: 'hi',
   ...NamedArgsMarker,
 });

packages/environment-ember-loose/__tests__/type-tests/route-and-controller.test.ts

@@ -1,7 +1,6 @@
 import Route from '@ember/routing/route';
 import Controller from '@ember/controller';
 import { expectTypeOf } from 'expect-type';
-import { EmptyObject } from '@glint/template/-private/integration';
 import { templateForBackingValue } from '../../-private/dsl';
 
 class TestRoute extends Route {
@@ -14,7 +13,7 @@ templateForBackingValue(TestRoute, function (routeContext) {
   expectTypeOf(routeContext.args).toEqualTypeOf<{ model: { message: string } }>();
   expectTypeOf(routeContext.element).toBeNull();
   expectTypeOf(routeContext.this).toEqualTypeOf<Controller & { model: { message: string } }>();
-  expectTypeOf(routeContext.blocks).toEqualTypeOf<EmptyObject>();
+  expectTypeOf(routeContext.blocks).toEqualTypeOf<{}>();
 });
 
 class TestController extends Controller {
@@ -29,5 +28,5 @@ templateForBackingValue(TestController, function (controllerContext) {
   expectTypeOf(controllerContext.args).toEqualTypeOf<{ model: { name: string; age: number } }>();
   expectTypeOf(controllerContext.element).toBeNull();
   expectTypeOf(controllerContext.this).toEqualTypeOf<TestController>();
-  expectTypeOf(controllerContext.blocks).toEqualTypeOf<EmptyObject>();
+  expectTypeOf(controllerContext.blocks).toEqualTypeOf<{}>();
 });

packages/environment-ember-loose/__tests__/type-tests/template-only.test.ts

@@ -5,22 +5,15 @@ import {
   emitComponent,
   NamedArgsMarker,
 } from '@glint/environment-ember-loose/-private/dsl';
-import { ComponentReturn, EmptyObject, NamedArgs } from '@glint/template/-private/integration';
+import { ComponentReturn, NamedArgs } from '@glint/template/-private/integration';
 import { expectTypeOf } from 'expect-type';
 import { ComponentKeyword } from '../../-private/intrinsics/component';
 import { ComponentLike, WithBoundArgs } from '@glint/template';
 
 {
   const NoArgsComponent = templateOnlyComponent();
 
-  resolve(NoArgsComponent)({
-    // @ts-expect-error: extra named arg
-    foo: 'bar',
-    ...NamedArgsMarker,
-  });
-
   resolve(NoArgsComponent)(
-    { ...NamedArgsMarker },
     // @ts-expect-error: extra positional arg
     'oops'
   );
@@ -38,9 +31,9 @@ import { ComponentLike, WithBoundArgs } from '@glint/template';
 
   templateForBackingValue(NoArgsComponent, function (𝚪) {
     expectTypeOf(𝚪.this).toBeNull();
-    expectTypeOf(𝚪.args).toEqualTypeOf<EmptyObject>();
-    expectTypeOf(𝚪.element).toBeNull();
-    expectTypeOf(𝚪.blocks).toEqualTypeOf<EmptyObject>();
+    expectTypeOf(𝚪.args).toEqualTypeOf<{}>();
+    expectTypeOf(𝚪.element).toBeUnknown();
+    expectTypeOf(𝚪.blocks).toEqualTypeOf<{}>();
   });
 }
 
@@ -124,15 +117,15 @@ import { ComponentLike, WithBoundArgs } from '@glint/template';
 
   const CurriedWithNothing = resolve(componentKeyword)('curried-component');
   expectTypeOf(resolve(CurriedWithNothing)).toEqualTypeOf<
-    (args: NamedArgs<{ a: string; b: number }>) => ComponentReturn<EmptyObject>
+    (args: NamedArgs<{ a: string; b: number }>) => ComponentReturn<{}>
   >();
 
   const CurriedWithA = resolve(componentKeyword)('curried-component', {
     a: 'hi',
     ...NamedArgsMarker,
   });
   expectTypeOf(resolve(CurriedWithA)).toEqualTypeOf<
-    (args: NamedArgs<{ a?: string; b: number }>) => ComponentReturn<EmptyObject>
+    (args: NamedArgs<{ a?: string; b: number }>) => ComponentReturn<{}>
   >();
 }
 

packages/environment-ember-template-imports/-private/dsl/index.d.ts

@@ -9,7 +9,6 @@ import {
   AnyContext,
   AnyFunction,
   DirectInvokable,
-  EmptyObject,
   HasContext,
   InvokableInstance,
   Invoke,
@@ -38,8 +37,8 @@ export declare const resolveOrReturn: ResolveOrReturn<typeof resolve>;
 import { TemplateOnlyComponent } from '@ember/component/template-only';
 
 export declare function templateExpression<
-  Signature extends AnyFunction = () => ComponentReturn<EmptyObject>,
-  Context extends AnyContext = TemplateContext<void, EmptyObject, EmptyObject, void>
+  Signature extends AnyFunction = () => ComponentReturn<{}>,
+  Context extends AnyContext = TemplateContext<void, {}, {}, void>
 >(
   f: (𝚪: Context, χ: never) => void
 ): TemplateOnlyComponent<never> &

packages/environment-glimmerx/-private/dsl/index.d.ts

@@ -27,7 +27,6 @@ import {
   AnyContext,
   AnyFunction,
   DirectInvokable,
-  EmptyObject,
   HasContext,
   InvokableInstance,
   Invoke,
@@ -54,8 +53,8 @@ export declare const resolveOrReturn: ResolveOrReturn<typeof resolve>;
 import { TemplateComponentInstance } from '@glimmerx/component';
 
 export declare function templateExpression<
-  Signature extends AnyFunction = () => ComponentReturn<EmptyObject>,
-  Context extends AnyContext = TemplateContext<void, EmptyObject, EmptyObject, void>
+  Signature extends AnyFunction = () => ComponentReturn<{}>,
+  Context extends AnyContext = TemplateContext<void, {}, {}, void>
 >(
   f: (𝚪: Context, χ: never) => void
 ): abstract new () => TemplateComponentInstance<never> &