Make export information available after loading, detect reexports

src/Module.ts

@@ -278,10 +278,11 @@ export default class Module {
 				return module.dynamicImporters.sort();
 			},
 			get hasDefaultExport() {
-				if (module.graph.phase !== BuildPhase.GENERATE) {
+				// This information is only valid after parsing
+				if (!module.ast) {
 					return null;
 				}
-				return 'default' in module.exports;
+				return 'default' in module.exports || 'default' in module.reexportDescriptions;
 			},
 			hasModuleSideEffects,
 			id,

test/function/samples/has-default-export/_config.js

@@ -0,0 +1,45 @@
+const assert = require('assert');
+const path = require('path');
+
+module.exports = {
+	description: 'reports if a module has a default export',
+	options: {
+		plugins: [
+			{
+				async buildStart() {
+					const ID_MAIN = path.join(__dirname, 'main.js');
+					const loadMain = this.load({ id: ID_MAIN });
+					assert.strictEqual(this.getModuleInfo(ID_MAIN).hasDefaultExport, null);
+					assert.strictEqual((await loadMain).hasDefaultExport, false);
+
+					assert.strictEqual(
+						(await this.load({ id: path.join(__dirname, 'direct.js') })).hasDefaultExport,
+						true,
+						'direct'
+					);
+					assert.strictEqual(
+						(await this.load({ id: path.join(__dirname, 'indirect.js') })).hasDefaultExport,
+						true,
+						'indirect'
+					);
+					assert.strictEqual(
+						(await this.load({ id: path.join(__dirname, 'reexport1.js') })).hasDefaultExport,
+						true,
+						'reexport'
+					);
+					assert.strictEqual(
+						(await this.load({ id: path.join(__dirname, 'reexport2.js') })).hasDefaultExport,
+						true,
+						'renamed reexport'
+					);
+				},
+				load(id) {
+					assert.strictEqual(this.getModuleInfo(id).hasDefaultExport, null, `load ${id}`);
+				},
+				transform(code, id) {
+					assert.strictEqual(this.getModuleInfo(id).hasDefaultExport, null, `transform ${id}`);
+				}
+			}
+		]
+	}
+};

test/function/samples/has-default-export/direct.js

@@ -0,0 +1 @@
+export default 'direct';

test/function/samples/has-default-export/indirect.js

@@ -0,0 +1,2 @@
+const indirect = 'indirect';
+export { indirect as default };

test/function/samples/has-default-export/main.js

@@ -0,0 +1,9 @@
+import direct from './direct.js';
+import indirect from './indirect.js';
+import reexport1 from './reexport1.js';
+import reexport2 from './reexport2.js';
+
+assert.strictEqual(direct, 'direct');
+assert.strictEqual(indirect, 'indirect');
+assert.strictEqual(reexport1, 'default');
+assert.strictEqual(reexport2, 'foo');

test/function/samples/has-default-export/other.js

@@ -0,0 +1,2 @@
+export default 'default';
+export const foo = 'foo';

test/function/samples/has-default-export/reexport1.js

@@ -0,0 +1 @@
+export { default } from './other.js';

test/function/samples/has-default-export/reexport2.js

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

test/function/samples/preload-module/_config.js

@@ -33,7 +33,7 @@ module.exports = {
 						assert.deepStrictEqual(moduleInfo, {
 							code: "import './dep';\nassert.ok(true);\n",
 							dynamicImporters: [],
-							hasDefaultExport: null,
+							hasDefaultExport: false,
 							dynamicallyImportedIdResolutions: [],
 							dynamicallyImportedIds: [],
 							hasModuleSideEffects: true,