Properly handle double reexports from external namespaces (#4159)

Author: lukastaegert

src/Module.ts

@@ -533,12 +533,15 @@ export default class Module {
 const foundNamespaceReexport =
 name in this.namespaceReexportsByName
 ? this.namespaceReexportsByName[name]
-: (this.namespaceReexportsByName[name] = this.getVariableFromNamespaceReexports(
+: this.getVariableFromNamespaceReexports(
 name,
 importerForSideEffects,
 searchedNamesAndModules,
 skipExternalNamespaceReexports
- ));
+ );
+if (!skipExternalNamespaceReexports) {
+this.namespaceReexportsByName[name] = foundNamespaceReexport;
+}
 if (foundNamespaceReexport) {
 return foundNamespaceReexport;
 }
@@ -1012,8 +1015,18 @@ export default class Module {
 skipExternalNamespaceReexports = false
 ): Variable | null {
 let foundSyntheticDeclaration: SyntheticNamedExportVariable | null = null;
-const skipExternalNamespaceValues = new Set([true, skipExternalNamespaceReexports]);
-for (const skipExternalNamespaces of skipExternalNamespaceValues) {
+const skipExternalNamespaceValues = [{ searchedNamesAndModules, skipExternalNamespaces: true }];
+if (!skipExternalNamespaceReexports) {
+const clonedSearchedNamesAndModules = new Map<string, Set<Module | ExternalModule>>();
+for (const [name, modules] of searchedNamesAndModules || []) {
+clonedSearchedNamesAndModules.set(name, new Set(modules));
+}
+skipExternalNamespaceValues.push({
+searchedNamesAndModules: clonedSearchedNamesAndModules,
+skipExternalNamespaces: false
+});
+}
+for (const { skipExternalNamespaces, searchedNamesAndModules } of skipExternalNamespaceValues) {
 const foundDeclarations = new Set<Variable>();
 for (const module of this.exportAllModules) {
 if (module instanceof Module || !skipExternalNamespaces) {

test/function/samples/double-namespace-reexport/_config.js

@@ -0,0 +1,17 @@
+const assert = require('assert');
+
+module.exports = {
+description: 'handles chained namespace reexports from externals',
+options: {
+external: 'external'
+},
+context: {
+require(id) {
+assert.strictEqual(id, 'external');
+return { foo: 42 };
+}
+},
+exports({ foo }) {
+assert.strictEqual(foo, 42);
+}
+};

test/function/samples/double-namespace-reexport/first.js

@@ -0,0 +1 @@
+export * from './second.js';

test/function/samples/double-namespace-reexport/main.js

@@ -0,0 +1 @@
+export { foo } from './first.js';

test/function/samples/double-namespace-reexport/second.js

@@ -0,0 +1 @@
+export * from 'external';