feat(ivy): first steps towards JIT compilation (#23833)

This commit adds a mechanism by which the @angular/core annotations
for @Component, @Injectable, and @NgModule become decorators which,
when executed at runtime, trigger just-in-time compilation of their
associated types. The activation of these decorators is configured
by the ivy_switch mechanism, ensuring that the Ivy JIT engine does
not get included in Angular bundles unless specifically requested.

PR Close #23833

packages/core/src/metadata/directives.ts

@@ -8,9 +8,9 @@
 
 import {ChangeDetectionStrategy} from '../change_detection/constants';
 import {Provider} from '../di';
+import {R3_COMPILE_COMPONENT} from '../ivy_switch';
 import {Type} from '../type';
 import {TypeDecorator, makeDecorator, makePropDecorator} from '../util/decorators';
-
 import {ViewEncapsulation} from './view';
 
 
@@ -754,7 +754,8 @@ export interface Component extends Directive {
  */
 export const Component: ComponentDecorator = makeDecorator(
     'Component', (c: Component = {}) => ({changeDetection: ChangeDetectionStrategy.Default, ...c}),
-    Directive);
+    Directive, undefined,
+    (type: Type<any>, meta: Component) => (R3_COMPILE_COMPONENT || (() => {}))(type, meta));
 
 /**
  * Type of the Pipe decorator / constructor function.

packages/core/src/metadata/ng_module.ts

@@ -9,9 +9,31 @@
 import {InjectorDef, InjectorType, defineInjector} from '../di/defs';
 import {convertInjectableProviderToFactory} from '../di/injectable';
 import {Provider} from '../di/provider';
+import {R3_COMPILE_NGMODULE} from '../ivy_switch';
 import {Type} from '../type';
 import {TypeDecorator, makeDecorator} from '../util/decorators';
 
+export interface NgModuleDef<T> {
+  type: T;
+  bootstrap: Type<any>[];
+  declarations: Type<any>[];
+  imports: Type<any>[];
+  exports: Type<any>[];
+
+  transitiveCompileScope: {directives: any[]; pipes: any[];}|undefined;
+}
+
+export function defineNgModule<T>(def: {type: T} & Partial<NgModuleDef<T>>): never {
+  const res: NgModuleDef<T> = {
+    type: def.type,
+    bootstrap: def.bootstrap || [],
+    declarations: def.declarations || [],
+    imports: def.imports || [],
+    exports: def.exports || [],
+    transitiveCompileScope: undefined,
+  };
+  return res as never;
+}
 
 /**
  * A wrapper around a module that also includes the providers.
@@ -187,6 +209,19 @@ export interface NgModule {
   id?: string;
 }
 
+function preR3NgModuleCompile(moduleType: InjectorType<any>, metadata: NgModule): void {
+  let imports = (metadata && metadata.imports) || [];
+  if (metadata && metadata.exports) {
+    imports = [...imports, metadata.exports];
+  }
+
+  moduleType.ngInjectorDef = defineInjector({
+    factory: convertInjectableProviderToFactory(moduleType, {useClass: moduleType}),
+    providers: metadata && metadata.providers,
+    imports: imports,
+  });
+}
+
 /**
  * NgModule decorator and metadata.
  *
@@ -195,15 +230,4 @@ export interface NgModule {
  */
 export const NgModule: NgModuleDecorator = makeDecorator(
     'NgModule', (ngModule: NgModule) => ngModule, undefined, undefined,
-    (moduleType: InjectorType<any>, metadata: NgModule) => {
-      let imports = (metadata && metadata.imports) || [];
-      if (metadata && metadata.exports) {
-        imports = [...imports, metadata.exports];
-      }
-
-      moduleType.ngInjectorDef = defineInjector({
-        factory: convertInjectableProviderToFactory(moduleType, {useClass: moduleType}),
-        providers: metadata && metadata.providers,
-        imports: imports,
-      });
-    });
+    (type: Type<any>, meta: NgModule) => (R3_COMPILE_NGMODULE || preR3NgModuleCompile)(type, meta));