feat(bazel): prefix private-export (barred-latin-o) symbols (#23007)

This allows a bundle index to be re-exported by a higher-level module without fear of collisions.
Under bazel, we always set the prefix to be underscore-joined workspace, package, label

PR Close #23007

packages/bazel/src/ng_module.bzl

@@ -280,6 +280,7 @@ def _write_bundle_index(ctx):
   tsconfig = dict(tsc_wrapped_tsconfig(ctx, ctx.files.srcs, ctx.files.srcs), **{
     "angularCompilerOptions": {
       "flatModuleOutFile": flat_module_out_file,
+      "flatModulePrivateSymbolPrefix": "_".join([ctx.workspace_name] + ctx.label.package.split("/") + [ctx.label.name, ""]),
     },
   })
   if not ctx.attr.module_name:

packages/compiler-cli/integrationtest/bazel/ng_module/spec.js

@@ -15,7 +15,8 @@ describe('flat module index', () => {
           require.resolve(`${PKG}/flat_module_filename.metadata.json`), {encoding: 'utf-8'});
       expect(metadata).toContain('"__symbolic":"module"');
       expect(metadata).toContain('"__symbolic":"reference","module":"@angular/core"');
-      expect(metadata).toContain('"origins":{"Child":"./child","ɵa":"./parent"}');
+      expect(metadata).toContain(
+          '"origins":{"Child":"./child","ɵangular_packages_compiler_cli_integrationtest_bazel_ng_module_test_module_a":"./parent"}');
       expect(metadata).toContain('"importAs":"some_npm_module"');
     });
   });
@@ -25,7 +26,8 @@ describe('flat module index', () => {
           fs.readFileSync(require.resolve(`${PKG}/flat_module_filename.d.ts`), {encoding: 'utf-8'});
 
       expect(dts).toContain('export * from \'./index\';');
-      expect(dts).toContain('export { Parent as ɵa } from \'./parent\';');
+      expect(dts).toContain(
+          'export { Parent as ɵangular_packages_compiler_cli_integrationtest_bazel_ng_module_test_module_a } from \'./parent\';');
     });
   });
 });

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

@@ -77,8 +77,9 @@ export function createBundleIndexHost<H extends ts.CompilerHost>(
   }
   const file = files[0];
   const indexModule = file.replace(/\.ts$/, '');
-  const bundler =
-      new MetadataBundler(indexModule, ngOptions.flatModuleId, new CompilerHostAdapter(host));
+  const bundler = new MetadataBundler(
+      indexModule, ngOptions.flatModuleId, new CompilerHostAdapter(host),
+      ngOptions.flatModulePrivateSymbolPrefix);
   const metadataBundle = bundler.getMetadataBundle();
   const metadata = JSON.stringify(metadataBundle.metadata);
   const name =

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

@@ -83,11 +83,14 @@ export class MetadataBundler {
   private metadataCache = new Map<string, ModuleMetadata|undefined>();
   private exports = new Map<string, Symbol[]>();
   private rootModule: string;
+  private privateSymbolPrefix: string;
   private exported: Set<Symbol>;
 
   constructor(
-      private root: string, private importAs: string|undefined, private host: MetadataBundlerHost) {
+      private root: string, private importAs: string|undefined, private host: MetadataBundlerHost,
+      privateSymbolPrefix?: string) {
     this.rootModule = `./${path.basename(root)}`;
+    this.privateSymbolPrefix = (privateSymbolPrefix || '').replace(/\W/g, '_');
   }
 
   getMetadataBundle(): BundledModule {
@@ -244,7 +247,7 @@ export class MetadataBundler {
     const exportedNames = new Set(exportedSymbols.map(s => s.name));
     let privateName = 0;
 
-    function newPrivateName(): string {
+    function newPrivateName(prefix: string): string {
       while (true) {
         let digits: string[] = [];
         let index = privateName++;
@@ -253,8 +256,7 @@ export class MetadataBundler {
           digits.unshift(base[index % base.length]);
           index = Math.floor(index / base.length);
         }
-        digits.unshift('\u0275');
-        const result = digits.join('');
+        const result = `\u0275${prefix}${digits.join('')}`;
         if (!exportedNames.has(result)) return result;
       }
     }
@@ -267,7 +269,7 @@ export class MetadataBundler {
         let name = symbol.name;
         const identifier = `${symbol.declaration!.module}:${symbol.declaration !.name}`;
         if (symbol.isPrivate && !symbol.privateName) {
-          name = newPrivateName();
+          name = newPrivateName(this.privateSymbolPrefix);
           symbol.privateName = name;
         }
         if (symbolsMap.has(identifier)) {

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

@@ -99,6 +99,10 @@ export interface CompilerOptions extends ts.CompilerOptions {
   // meaningful when `flatModuleOutFile` is also supplied. It is otherwise ignored.
   flatModuleId?: string;
 
+  // A prefix to insert in generated private symbols, e.g. for "my_prefix_" we
+  // would generate private symbols named like `ɵmy_prefix_a`.
+  flatModulePrivateSymbolPrefix?: string;
+
   // Whether to generate code for library code.
   // If true, produce .ngfactory.ts and .ngstyle.ts files for .d.ts inputs.
   // Default is true.

packages/compiler-cli/test/metadata/bundler_spec.ts

@@ -19,10 +19,10 @@ describe('metadata bundler', () => {
 
   it('should be able to bundle a simple library', () => {
     const host = new MockStringBundlerHost('/', SIMPLE_LIBRARY);
-    const bundler = new MetadataBundler('/lib/index', undefined, host);
+    const bundler = new MetadataBundler('/lib/index', undefined, host, 'prfx_');
     const result = bundler.getMetadataBundle();
     expect(Object.keys(result.metadata.metadata).sort()).toEqual([
-      'ONE_CLASSES', 'One', 'OneMore', 'TWO_CLASSES', 'Two', 'TwoMore', 'ɵa', 'ɵb'
+      'ONE_CLASSES', 'One', 'OneMore', 'TWO_CLASSES', 'Two', 'TwoMore', 'ɵprfx_a', 'ɵprfx_b'
     ]);
 
     const originalOne = './src/one';
@@ -34,11 +34,11 @@ describe('metadata bundler', () => {
           {name: 'ONE_CLASSES', value: originalOne}, {name: 'One', value: originalOne},
           {name: 'OneMore', value: originalOne}, {name: 'TWO_CLASSES', value: originalTwo},
           {name: 'Two', value: originalTwo}, {name: 'TwoMore', value: originalTwo},
-          {name: 'ɵa', value: originalOne}, {name: 'ɵb', value: originalTwo}
+          {name: 'ɵprfx_a', value: originalOne}, {name: 'ɵprfx_b', value: originalTwo}
         ]);
     expect(result.privates).toEqual([
-      {privateName: 'ɵa', name: 'PrivateOne', module: originalOne},
-      {privateName: 'ɵb', name: 'PrivateTwo', module: originalTwo}
+      {privateName: 'ɵprfx_a', name: 'PrivateOne', module: originalOne},
+      {privateName: 'ɵprfx_b', name: 'PrivateTwo', module: originalTwo}
     ]);
   });