feat(ivy): give shim generation its own compiler options (#33256)

As a hack to get the Ivy compiler ngtsc off the ground, the existing
'allowEmptyCodegenFiles' option was used to control generation of ngfactory
and ngsummary shims during compilation. This option was selected since it's
enabled in google3 but never enabled in external projects.

As ngtsc is now mature and the role shims play in compilation is now better
understood across the ecosystem, this commit introduces two new compiler
options to control shim generation:

* generateNgFactoryShims controls the generation of .ngfactory shims.
* generateNgSummaryShims controls the generation of .ngsummary shims.

The 'allowEmptyCodegenFiles' option is still honored if either of the above
flags are not set explicitly.

PR Close #33256

packages/compiler-cli/src/ngtsc/program.ts

@@ -83,7 +83,15 @@ export class NgtscProgram implements api.Program {
     this.rootDirs = getRootDirs(host, options);
     this.closureCompilerEnabled = !!options.annotateForClosureCompiler;
     this.resourceManager = new HostResourceLoader(host, options);
-    const shouldGenerateShims = options.allowEmptyCodegenFiles || false;
+    // TODO(alxhub): remove the fallback to allowEmptyCodegenFiles after verifying that the rest of
+    // our build tooling is no longer relying on it.
+    const allowEmptyCodegenFiles = options.allowEmptyCodegenFiles || false;
+    const shouldGenerateFactoryShims = options.generateNgFactoryShims !== undefined ?
+        options.generateNgFactoryShims :
+        allowEmptyCodegenFiles;
+    const shouldGenerateSummaryShims = options.generateNgSummaryShims !== undefined ?
+        options.generateNgSummaryShims :
+        allowEmptyCodegenFiles;
     const normalizedRootNames = rootNames.map(n => absoluteFrom(n));
     if (host.fileNameToModuleName !== undefined) {
       this.fileToModuleHost = host as FileToModuleHost;
@@ -91,10 +99,14 @@ export class NgtscProgram implements api.Program {
     let rootFiles = [...rootNames];
 
     const generators: ShimGenerator[] = [];
-    if (shouldGenerateShims) {
+    let summaryGenerator: SummaryGenerator|null = null;
+    if (shouldGenerateSummaryShims) {
       // Summary generation.
-      const summaryGenerator = SummaryGenerator.forRootFiles(normalizedRootNames);
+      summaryGenerator = SummaryGenerator.forRootFiles(normalizedRootNames);
+      generators.push(summaryGenerator);
+    }
 
+    if (shouldGenerateFactoryShims) {
       // Factory generation.
       const factoryGenerator = FactoryGenerator.forRootFiles(normalizedRootNames);
       const factoryFileMap = factoryGenerator.factoryFileMap;
@@ -107,8 +119,14 @@ export class NgtscProgram implements api.Program {
       });
 
       const factoryFileNames = Array.from(factoryFileMap.keys());
-      rootFiles.push(...factoryFileNames, ...summaryGenerator.getSummaryFileNames());
-      generators.push(summaryGenerator, factoryGenerator);
+      rootFiles.push(...factoryFileNames);
+      generators.push(factoryGenerator);
+    }
+
+    // Done separately to preserve the order of factory files before summary files in rootFiles.
+    // TODO(alxhub): validate that this is necessary.
+    if (shouldGenerateSummaryShims) {
+      rootFiles.push(...summaryGenerator !.getSummaryFileNames());
     }
 
     this.typeCheckFilePath = typeCheckFilePath(this.rootDirs);

packages/compiler-cli/src/transformers/api.ts

@@ -196,6 +196,23 @@ export interface CompilerOptions extends ts.CompilerOptions {
    */
   enableResourceInlining?: boolean;
 
+  /**
+   * Controls whether ngtsc will emit `.ngfactory.js` shims for each compiled `.ts` file.
+   *
+   * These shims support legacy imports from `ngfactory` files, by exporting a factory shim
+   * for each component or NgModule in the original `.ts` file.
+   */
+  generateNgFactoryShims?: boolean;
+
+  /**
+   * Controls whether ngtsc will emit `.ngsummary.js` shims for each compiled `.ts` file.
+   *
+   * These shims support legacy imports from `ngsummary` files, by exporting an empty object
+   * for each NgModule in the original `.ts` file. The only purpose of summaries is to feed them to
+   * `TestBed`, which is a no-op in Ivy.
+   */
+  generateNgSummaryShims?: boolean;
+
   /**
    * Tells the compiler to generate definitions using the Render3 style code generation.
    * This option defaults to `true`.