feat(bazel): ng_module produces bundle index (#22176)

It creates the bundle index .d.ts and .metadata.json files.
The names are based on the ng_module target.

PR Close #22176

packages/compiler-cli/src/metadata/bundle_index_main.ts

@@ -0,0 +1,43 @@
+#!/usr/bin/env node
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+// Must be imported first, because Angular decorators throw on load.
+import 'reflect-metadata';
+
+import * as ts from 'typescript';
+import * as path from 'path';
+import {readCommandLineAndConfiguration} from '../main';
+import {createBundleIndexHost} from './bundle_index_host';
+import * as ng from '../transformers/entry_points';
+
+export function main(args: string[], consoleError: (s: string) => void = console.error): number {
+  const {options, rootNames} = readCommandLineAndConfiguration(args);
+  const host = ng.createCompilerHost({options});
+  const {host: bundleHost, indexName, errors} = createBundleIndexHost(options, rootNames, host);
+  if (!indexName) {
+    console.error('Did not find an index.ts in the top-level of the package.');
+    return 1;
+  }
+  // The index file is synthetic, so we have to add it to the program after parsing the tsconfig
+  rootNames.push(indexName);
+  const program = ts.createProgram(rootNames, options, bundleHost);
+  const indexSourceFile = program.getSourceFile(indexName);
+  if (!indexSourceFile) {
+    console.error(`${indexSourceFile} is not in the program. Please file a bug.`);
+    return 1;
+  }
+  program.emit(indexSourceFile);
+  return 0;
+}
+
+// CLI entry point
+if (require.main === module) {
+  const args = process.argv.slice(2);
+  process.exitCode = main(args);
+}

packages/compiler-cli/src/metadata/bundler.ts

@@ -597,6 +597,7 @@ export class CompilerHostAdapter implements MetadataBundlerHost {
   constructor(private host: ts.CompilerHost) {}
 
   getMetadataFor(fileName: string): ModuleMetadata|undefined {
+    if (!this.host.fileExists(fileName + '.ts')) return undefined;
     const sourceFile = this.host.getSourceFile(fileName + '.ts', ts.ScriptTarget.Latest);
     return sourceFile && this.collector.getMetadata(sourceFile);
   }