Use internal module namespace in externs type annotations.

PiperOrigin-RevId: 573179784

Author: tsjs-language-eng

src/externs.ts

@@ -165,9 +165,6 @@ export function generateExterns(
   const isDts = isDtsFileName(sourceFile.fileName);
   const isExternalModule = ts.isExternalModule(sourceFile);
 
-  const mtt =
-      new ModuleTypeTranslator(sourceFile, typeChecker, host, diagnostics, /*isForExterns*/ true);
-
   // .d.ts files declare symbols. The code below translates these into a form understood by Closure
   // Compiler, converting the type syntax, but also converting symbol names into a form accessible
   // to Closure Compiler.
@@ -206,6 +203,10 @@ export function generateExterns(
     rootNamespace = rootNamespace + '_';
   }
 
+  const mtt = new ModuleTypeTranslator(
+      sourceFile, typeChecker, host, diagnostics, /*isForExterns*/ true,
+      /*useInternalNamespaceForExterns=*/ hasExportEquals);
+
   for (const stmt of sourceFile.statements) {
     // Always collect alises for imported symbols.
     importsVisitor(stmt);

src/module_type_translator.ts

@@ -105,6 +105,7 @@ export class ModuleTypeTranslator {
       private readonly host: AnnotatorHost&googmodule.GoogModuleProcessorHost,
       private readonly diagnostics: ts.Diagnostic[],
       private readonly isForExterns: boolean,
+      private readonly useInternalNamespaceForExterns = false,
   ) {
     // TODO: remove once AnnotatorHost.typeBlackListPaths is removed.
     this.host.unknownTypesPaths =
@@ -165,6 +166,8 @@ export class ModuleTypeTranslator {
         this.symbolToNameCache,
         (sym: ts.Symbol) => void this.ensureSymbolDeclared(sym));
     translator.isForExterns = this.isForExterns;
+    translator.useInternalNamespaceForExterns =
+        this.useInternalNamespaceForExterns;
     translator.warn = msg => void this.debugWarn(context, msg);
     return translator;
   }

src/type_translator.ts

@@ -252,6 +252,13 @@ export class TypeTranslator {
    */
   isForExterns = false;
 
+  /**
+   * Whether use internal namespace (with underscore) for the externs types.
+   * It is set when the declaration file has an export equals ("export = Foo;")
+   * statement.
+   */
+  useInternalNamespaceForExterns = false;
+
   /**
    * When translating the type of an 'extends' clause, e.g. Y in
    *   class X extends Y<T> { ... }
@@ -419,6 +426,11 @@ export class TypeTranslator {
       context = '';
     }
     const mangled = moduleNameAsIdentifier(this.host, fileName, context);
+    if (this.isForExterns && this.useInternalNamespaceForExterns &&
+        !ambientModuleDeclaration &&
+        isDeclaredInSameFile(this.node, declarations[0])) {
+      return mangled + '_.';
+    }
     return mangled + '.';
   }
 

test_files/augment/externs.js

@@ -6,7 +6,7 @@
 // Generated from: test_files/augment/angular/index.d.ts
 /** @const */
 var test_files$augment$angular$index_ = {};
-/** @type {!test_files$augment$angular$index.angular.IAngularStatic} */
+/** @type {!test_files$augment$angular$index_.angular.IAngularStatic} */
 test_files$augment$angular$index_.angular;
 /** @const */
 test_files$augment$angular$index_.angular = {};

test_files/declare_export_dts/externs.js

@@ -59,9 +59,9 @@ test_files$declare_export_dts$relative_ambient_external_module.user;
 // Generated from: test_files/declare_export_dts/declare_export_var.d.ts
 /** @const */
 var test_files$declare_export_dts$declare_export_var_ = {};
-/** @type {!test_files$declare_export_dts$declare_export_var.namespaceInDtsModule.InterfaceNestedInModuleScopedNamespace} */
+/** @type {!test_files$declare_export_dts$declare_export_var_.namespaceInDtsModule.InterfaceNestedInModuleScopedNamespace} */
 test_files$declare_export_dts$declare_export_var_.variableDeclaredInDtsModule;
-/** @type {!test_files$declare_export_dts$declare_export_var.namespaceInDtsModule.InterfaceNestedInModuleScopedNamespace} */
+/** @type {!test_files$declare_export_dts$declare_export_var_.namespaceInDtsModule.InterfaceNestedInModuleScopedNamespace} */
 var variableDeclaredInDtsModule;
 /** @const */
 test_files$declare_export_dts$declare_export_var_.namespaceInDtsModule = {};

test_files/import_equals/externs.js

@@ -53,7 +53,7 @@ test_files$import_equals$import_equals_module_.namespaceInModule = {};
  * @struct
  */
 test_files$import_equals$import_equals_module_.namespaceInModule.InNamespace = function() {};
-/** @type {!test_files$import_equals$import_equals_module.namespaceInModule.InNamespace} */
+/** @type {!test_files$import_equals$import_equals_module_.namespaceInModule.InNamespace} */
 test_files$import_equals$import_equals_module_.namespaceInModule.myVar;
 /** @type {!test_files$import_equals$exporter.Exported.Nested} */
 test_files$import_equals$import_equals_module_.namespaceInModule.otherVar;