feat(compiler-cli): no longer re-export external symbols by default (#28633)

With #28594 we refactored the `@angular/compiler` slightly to
allow opting out from external symbol re-exports which are
enabled by default.

Since symbol re-exports only benefit projects which have a
very strict dependency enforcement, external symbols should
not be re-exported by default as this could grow the size of
factory files and cause unexpected behavior with Angular's
AOT symbol resolving (e.g. see: #25644).

Note that the common strict dependency enforcement for source
files does still work with external symbol re-exports disabled,
but there are also strict dependency checks that enforce strict
module dependencies also for _generated files_ (such as the
ngfactory files). This is how Google3 manages it's dependencies
and therefore external symbol re-exports need to be enabled within
Google3.

Also "ngtsc" also does not provide any way of using external symbol
re-exports, so this means that with this change, NGC can partially
match the behavior of "ngtsc" then (unless explicitly opted-out).

As mentioned before, internally at Google symbol re-exports need to
be still enabled, so the `ng_module` Bazel rule will enable the symbol
re-exports by default when running within Blaze.

Fixes #25644.

PR Close #28633

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

@@ -199,6 +199,15 @@ export interface CompilerOptions extends ts.CompilerOptions {
 
   /** @internal */
   collectAllErrors?: boolean;
+
+  /**
+   * Whether NGC should generate re-exports for external symbols which are referenced
+   * in Angular metadata (e.g. @Component, @Inject, @ViewChild). This can be enabled in
+   * order to avoid dynamically generated module dependencies which can break strict
+   * dependency enforcements. This is not enabled by default.
+   * Read more about this here: https://github.com/angular/angular/issues/25644.
+   */
+  createExternalSymbolFactoryReexports?: boolean;
 }
 
 export interface CompilerHost extends ts.CompilerHost {

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

@@ -942,6 +942,7 @@ function getAotCompilerOptions(options: CompilerOptions): AotCompilerOptions {
     fullTemplateTypeCheck: options.fullTemplateTypeCheck,
     allowEmptyCodegenFiles: options.allowEmptyCodegenFiles,
     enableIvy: options.enableIvy,
+    createExternalSymbolFactoryReexports: options.createExternalSymbolFactoryReexports,
   };
 }