Ensure reexported namespaces do not prevent creation of default export helpers (#5466)

* Add test

* Use better variable name

* Ensure reexported namespaces do not prevent creation of default export helpers

Author: lukastaegert

src/Chunk.ts

@@ -908,9 +908,14 @@ export default class Chunk {
 								deconflictedDefault.add(chunk);
 							}
 						} else if (
-							variable.name === '*' &&
-							namespaceInteropHelpersByInteropType[interop(module.id)]
+							variable.isNamespace &&
+							namespaceInteropHelpersByInteropType[interop(module.id)] &&
+							(this.imports.has(variable) ||
+								!this.exportNamesByVariable.get(variable)?.every(name => name.startsWith('*')))
 						) {
+							// We only need to deconflict it if the namespace is actually
+							// created as a variable, i.e. because it is used internally or
+							// because it is reexported as an object
 							deconflictedNamespace.add(chunk);
 						}
 					}
@@ -1139,30 +1144,34 @@ export default class Chunk {
 		const reexportSpecifiers = this.getReexportSpecifiers();
 		const renderedDependencies = new Map<Chunk | ExternalChunk, ChunkDependency>();
 		const fileName = this.getFileName();
-		for (const dep of this.dependencies) {
-			const imports = importSpecifiers.get(dep) || null;
-			const reexports = reexportSpecifiers.get(dep) || null;
-			const namedExportsMode = dep instanceof ExternalChunk || dep.exportMode !== 'default';
-			const importPath = dep.getImportPath(fileName);
-
-			renderedDependencies.set(dep, {
-				attributes: dep instanceof ExternalChunk ? dep.getImportAttributes(this.snippets) : null,
-				defaultVariableName: dep.defaultVariableName,
+		for (const dependency of this.dependencies) {
+			const imports = importSpecifiers.get(dependency) || null;
+			const reexports = reexportSpecifiers.get(dependency) || null;
+			const namedExportsMode =
+				dependency instanceof ExternalChunk || dependency.exportMode !== 'default';
+			const importPath = dependency.getImportPath(fileName);
+
+			renderedDependencies.set(dependency, {
+				attributes:
+					dependency instanceof ExternalChunk
+						? dependency.getImportAttributes(this.snippets)
+						: null,
+				defaultVariableName: dependency.defaultVariableName,
 				globalName:
-					dep instanceof ExternalChunk &&
+					dependency instanceof ExternalChunk &&
 					(this.outputOptions.format === 'umd' || this.outputOptions.format === 'iife') &&
 					getGlobalName(
-						dep,
+						dependency,
 						this.outputOptions.globals,
 						(imports || reexports) !== null,
 						this.inputOptions.onLog
 					),
 				importPath,
 				imports,
-				isChunk: dep instanceof Chunk,
-				name: dep.variableName,
+				isChunk: dependency instanceof Chunk,
+				name: dependency.variableName,
 				namedExportsMode,
-				namespaceVariableName: dep.namespaceVariableName,
+				namespaceVariableName: dependency.namespaceVariableName,
 				reexports
 			});
 		}

test/function/samples/external-namespace-and-default-reexport-compat/_config.js

@@ -0,0 +1,27 @@
+const assert = require('node:assert');
+
+module.exports = defineTest({
+	description: 'reexports both a namespace and the default export when using compat interop',
+	options: {
+		external: true,
+		output: { exports: 'named', interop: 'compat' }
+	},
+	context: {
+		require: id => {
+			if (id === 'external') {
+				return {
+					__esModule: true,
+					default: 'default',
+					foo: 'foo'
+				};
+			}
+			throw new Error(`Cannot find module ${id}`);
+		}
+	},
+	exports(exports) {
+		assert.deepStrictEqual(exports, {
+			default: 'default',
+			foo: 'foo'
+		});
+	}
+});

test/function/samples/external-namespace-and-default-reexport-compat/main.js

@@ -0,0 +1,2 @@
+export * from "external";
+export { default } from "external";

test/function/samples/external-namespace-and-default-reexport-compat2/_config.js

@@ -0,0 +1,33 @@
+const assert = require('node:assert');
+
+module.exports = defineTest({
+	description:
+		'reexports both a namespace, the namespace as a name and the default export when using compat interop',
+	options: {
+		external: true,
+		output: { exports: 'named', interop: 'compat' }
+	},
+	context: {
+		require: id => {
+			if (id === 'external') {
+				return {
+					__esModule: true,
+					default: 'default',
+					foo: 'foo'
+				};
+			}
+			throw new Error(`Cannot find module ${id}`);
+		}
+	},
+	exports(exports) {
+		assert.deepStrictEqual(exports, {
+			default: 'default',
+			foo: 'foo',
+			external: {
+				__esModule: true,
+				default: 'default',
+				foo: 'foo'
+			}
+		});
+	}
+});

test/function/samples/external-namespace-and-default-reexport-compat2/main.js

@@ -0,0 +1,3 @@
+export * from "external";
+export * as external from 'external';
+export { default } from "external";

test/function/samples/external-namespace-and-default-reexport-compat3/_config.js

@@ -0,0 +1,34 @@
+const assert = require('node:assert');
+
+module.exports = defineTest({
+	description: 'reexports both a namespace and the default export when using compat interop',
+	options: {
+		external: true,
+		output: { exports: 'named', interop: 'compat' }
+	},
+	context: {
+		require: id => {
+			if (id === 'external') {
+				return {
+					__esModule: true,
+					default: 'default',
+					foo: 'foo'
+				};
+			}
+			throw new Error(`Cannot find module ${id}`);
+		}
+	},
+	exports(exports) {
+		assert.deepStrictEqual(exports, {
+			default: 'default',
+			foo: 'foo',
+			wrappedExternal: {
+				external: {
+					__esModule: true,
+					default: 'default',
+					foo: 'foo'
+				}
+			}
+		});
+	}
+});

test/function/samples/external-namespace-and-default-reexport-compat3/main.js

@@ -0,0 +1,5 @@
+export * from 'external';
+import * as external from "external";
+
+export const wrappedExternal = { external };
+export { default } from 'external';