Provide better error when creating a namespace object containing a reexported external namespace

src/Chunk.ts

@@ -247,7 +247,10 @@ export default class Chunk {
 		const tracedExports: { variable: Variable; module: Module | ExternalModule }[] = [];
 		for (const [index, exportName] of entryExportEntries) {
 			const traced = this.traceExport(exportName, this.entryModule);
-			if (traced.variable && !traced.variable.included && !traced.variable.isExternal) {
+			if (
+				!traced ||
+				(traced.variable && !traced.variable.included && !traced.variable.isExternal)
+			) {
 				continue;
 			}
 			tracedExports[index] = traced;
@@ -332,8 +335,8 @@ export default class Chunk {
 	): {
 		variable: Variable;
 		module: Module | ExternalModule;
-	} {
-		if (name === '*' || module instanceof ExternalModule) {
+	} | void {
+		if (name[0] === '*' || module instanceof ExternalModule) {
 			return { variable: module.traceExport(name), module };
 		}
 
@@ -365,11 +368,6 @@ export default class Chunk {
 			return;
 		}
 
-		// external star exports
-		if (name[0] === '*') {
-			return { variable: undefined, module: this.graph.moduleById.get(name.substr(1)) };
-		}
-
 		// resolve known star exports
 		for (let i = 0; i < module.exportAllModules.length; i++) {
 			const exportAllModule = module.exportAllModules[i];

src/ast/variables/NamespaceVariable.ts

@@ -11,17 +11,19 @@ export default class NamespaceVariable extends Variable {
 	// Not initialised during construction
 	originals: { [name: string]: Variable } = Object.create(null);
 	needsNamespaceBlock: boolean = false;
-	
+
 	// only to be used for chunk-to-chunk import tracing, use context for data manipulation
 	module: Module;
 	private referencedEarly: boolean = false;
 	private references: Identifier[] = [];
+	private containsExternalNamespace: boolean = false;
 
 	constructor(context: AstContext, module: Module) {
 		super(context.getModuleName());
 		this.context = context;
 		this.module = module;
 		for (const name of this.context.getExports().concat(this.context.getReexports())) {
+			if (name[0] === '*' && name.length > 1) this.containsExternalNamespace = true;
 			this.originals[name] = this.context.traceExport(name);
 		}
 	}
@@ -33,6 +35,16 @@ export default class NamespaceVariable extends Variable {
 
 	include() {
 		if (!this.included) {
+			if (this.containsExternalNamespace) {
+				this.context.error(
+					{
+						code: 'NAMESPACE_CANNOT_CONTAIN_EXTERNAL',
+						message: `Cannot create an explicit namespace object for module "${this.context.getModuleName()}" because it contains a reexported external namespace`,
+						id: this.module.id
+					},
+					undefined
+				);
+			}
 			this.context.includeNamespace();
 			this.included = true;
 			this.needsNamespaceBlock = true;

test/function/samples/internal-reexports-from-external/_config.js

@@ -0,0 +1,15 @@
+const path = require('path');
+
+module.exports = {
+	description:
+		'fails with a helpful error if creating a namespace object containing a reexported external namespace',
+	options: {
+		external: ['external']
+	},
+	error: {
+		code: 'NAMESPACE_CANNOT_CONTAIN_EXTERNAL',
+		message:
+			'Cannot create an explicit namespace object for module "reexport" because it contains a reexported external namespace',
+		id: path.join(__dirname, '/reexport.js')
+	}
+};

test/function/samples/internal-reexports-from-external/main.js

@@ -0,0 +1,3 @@
+import * as namespace from './reexport.js';
+
+console.log(namespace);

test/function/samples/internal-reexports-from-external/reexport.js

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