From 7466889ddb0ac99d03d9397d5321818ac7eb0394 Mon Sep 17 00:00:00 2001
From: Lukas Taegert-Atkinson <lukas.taegert-atkinson@tngtech.com>
Date: Sat, 22 Jan 2022 06:59:19 +0100
Subject: [PATCH] Make export information available after loading, detect
 reexports

---
 src/Module.ts                                 |  5 ++-
 .../samples/has-default-export/_config.js     | 45 +++++++++++++++++++
 .../samples/has-default-export/direct.js      |  1 +
 .../samples/has-default-export/indirect.js    |  2 +
 .../samples/has-default-export/main.js        |  9 ++++
 .../samples/has-default-export/other.js       |  2 +
 .../samples/has-default-export/reexport1.js   |  1 +
 .../samples/has-default-export/reexport2.js   |  1 +
 .../samples/preload-module/_config.js         |  2 +-
 9 files changed, 65 insertions(+), 3 deletions(-)
 create mode 100644 test/function/samples/has-default-export/_config.js
 create mode 100644 test/function/samples/has-default-export/direct.js
 create mode 100644 test/function/samples/has-default-export/indirect.js
 create mode 100644 test/function/samples/has-default-export/main.js
 create mode 100644 test/function/samples/has-default-export/other.js
 create mode 100644 test/function/samples/has-default-export/reexport1.js
 create mode 100644 test/function/samples/has-default-export/reexport2.js

diff --git a/src/Module.ts b/src/Module.ts
index c0f9aac2122..93db11d47d6 100644
--- a/src/Module.ts
+++ b/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,
diff --git a/test/function/samples/has-default-export/_config.js b/test/function/samples/has-default-export/_config.js
new file mode 100644
index 00000000000..daea5948706
--- /dev/null
+++ b/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}`);
+				}
+			}
+		]
+	}
+};
diff --git a/test/function/samples/has-default-export/direct.js b/test/function/samples/has-default-export/direct.js
new file mode 100644
index 00000000000..f2f6d5c381b
--- /dev/null
+++ b/test/function/samples/has-default-export/direct.js
@@ -0,0 +1 @@
+export default 'direct';
diff --git a/test/function/samples/has-default-export/indirect.js b/test/function/samples/has-default-export/indirect.js
new file mode 100644
index 00000000000..28786796a99
--- /dev/null
+++ b/test/function/samples/has-default-export/indirect.js
@@ -0,0 +1,2 @@
+const indirect = 'indirect';
+export { indirect as default };
diff --git a/test/function/samples/has-default-export/main.js b/test/function/samples/has-default-export/main.js
new file mode 100644
index 00000000000..28d6ee09c9c
--- /dev/null
+++ b/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');
diff --git a/test/function/samples/has-default-export/other.js b/test/function/samples/has-default-export/other.js
new file mode 100644
index 00000000000..a99ac05aa02
--- /dev/null
+++ b/test/function/samples/has-default-export/other.js
@@ -0,0 +1,2 @@
+export default 'default';
+export const foo = 'foo';
diff --git a/test/function/samples/has-default-export/reexport1.js b/test/function/samples/has-default-export/reexport1.js
new file mode 100644
index 00000000000..b98cf73cdb9
--- /dev/null
+++ b/test/function/samples/has-default-export/reexport1.js
@@ -0,0 +1 @@
+export { default } from './other.js';
diff --git a/test/function/samples/has-default-export/reexport2.js b/test/function/samples/has-default-export/reexport2.js
new file mode 100644
index 00000000000..08facccd528
--- /dev/null
+++ b/test/function/samples/has-default-export/reexport2.js
@@ -0,0 +1 @@
+export { foo as default } from './other.js';
diff --git a/test/function/samples/preload-module/_config.js b/test/function/samples/preload-module/_config.js
index 4454921c9d6..51ec568846e 100644
--- a/test/function/samples/preload-module/_config.js
+++ b/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,