From 6cfc9549269efc91f5063fb8d9df10bc66e64152 Mon Sep 17 00:00:00 2001
From: ItsRenji <ItsRenjiii@users.noreply.github.com>
Date: Sat, 7 Nov 2026 04:16:19 +0000
Subject: [PATCH] fix(commonjs): pass exports to the wrapper when only
 __esModule is defined on it

A top-level `Object.defineProperty(exports, '__esModule', ...)` is skipped
during analysis, so it did not mark `exports` as used. When the module was
wrapped for another reason (such as a `module` reference), the wrapper only
received `module`, and the kept `defineProperty` call referenced a free
`exports`. In ES output this throws `ReferenceError: exports is not defined`.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 packages/commonjs/src/transform-commonjs.js   |  9 ++++
 .../wrapped-define-compiled-esm/_config.js    |  4 ++
 .../wrapped-define-compiled-esm/dep.js        |  4 ++
 .../wrapped-define-compiled-esm/main.js       |  4 ++
 .../commonjs/test/snapshots/function.js.snap  | 45 +++++++++++++++++++
 5 files changed, 66 insertions(+)
 create mode 100644 packages/commonjs/test/fixtures/function/wrapped-define-compiled-esm/_config.js
 create mode 100644 packages/commonjs/test/fixtures/function/wrapped-define-compiled-esm/dep.js
 create mode 100644 packages/commonjs/test/fixtures/function/wrapped-define-compiled-esm/main.js

diff --git a/packages/commonjs/src/transform-commonjs.js b/packages/commonjs/src/transform-commonjs.js
index 2bc22ae88..e67758331 100644
--- a/packages/commonjs/src/transform-commonjs.js
+++ b/packages/commonjs/src/transform-commonjs.js
@@ -473,6 +473,15 @@ export default async function transformCommonjs(
   // We cannot wrap ES/mixed modules
   shouldWrap = !isEsModule && (shouldWrap || (uses.exports && moduleExportsAssignments.length > 0));
 
+  // Top-level `Object.defineProperty([module.]exports, '__esModule', ...)` calls
+  // were skipped above, so they did not mark `exports` or `module` as used. A
+  // wrapped module keeps them as they are, so the wrapper must provide that name.
+  if (shouldWrap) {
+    for (const { type } of topLevelDefineCompiledEsmExpressions) {
+      uses[type] = true;
+    }
+  }
+
   if (
     !(
       shouldWrap ||
diff --git a/packages/commonjs/test/fixtures/function/wrapped-define-compiled-esm/_config.js b/packages/commonjs/test/fixtures/function/wrapped-define-compiled-esm/_config.js
new file mode 100644
index 000000000..4b0fe5589
--- /dev/null
+++ b/packages/commonjs/test/fixtures/function/wrapped-define-compiled-esm/_config.js
@@ -0,0 +1,4 @@
+module.exports = {
+  description:
+    'passes exports to the wrapper when a wrapped module only uses it to define __esModule'
+};
diff --git a/packages/commonjs/test/fixtures/function/wrapped-define-compiled-esm/dep.js b/packages/commonjs/test/fixtures/function/wrapped-define-compiled-esm/dep.js
new file mode 100644
index 000000000..ff871a824
--- /dev/null
+++ b/packages/commonjs/test/fixtures/function/wrapped-define-compiled-esm/dep.js
@@ -0,0 +1,4 @@
+'use strict';
+
+Object.defineProperty(exports, '__esModule', { value: true });
+module.exports.type = typeof module.exports;
diff --git a/packages/commonjs/test/fixtures/function/wrapped-define-compiled-esm/main.js b/packages/commonjs/test/fixtures/function/wrapped-define-compiled-esm/main.js
new file mode 100644
index 000000000..f91d37972
--- /dev/null
+++ b/packages/commonjs/test/fixtures/function/wrapped-define-compiled-esm/main.js
@@ -0,0 +1,4 @@
+const dep = require('./dep.js');
+
+t.is(dep.__esModule, true);
+t.is(dep.type, 'object');
diff --git a/packages/commonjs/test/snapshots/function.js.snap b/packages/commonjs/test/snapshots/function.js.snap
index 1ecce0bb1..efa415f75 100644
--- a/packages/commonjs/test/snapshots/function.js.snap
+++ b/packages/commonjs/test/snapshots/function.js.snap
@@ -10974,3 +10974,48 @@ module.exports = main;
 ",
 }
 `;
+
+exports[`wrapped-define-compiled-esm 1`] = `
+{
+  "main.js": "'use strict';
+
+function getDefaultExportFromCjs (x) {
+	return x && x.__esModule && Object.prototype.hasOwnProperty.call(x, 'default') ? x['default'] : x;
+}
+
+var main$1 = {};
+
+var dep = {exports: {}};
+
+var hasRequiredDep;
+
+function requireDep () {
+	if (hasRequiredDep) return dep.exports;
+	hasRequiredDep = 1;
+	(function (module, exports) {
+
+		Object.defineProperty(exports, '__esModule', { value: true });
+		module.exports.type = 'object'; 
+	} (dep, dep.exports));
+	return dep.exports;
+}
+
+var hasRequiredMain;
+
+function requireMain () {
+	if (hasRequiredMain) return main$1;
+	hasRequiredMain = 1;
+	const dep = requireDep();
+
+	t.is(dep.__esModule, true);
+	t.is(dep.type, 'object');
+	return main$1;
+}
+
+var mainExports = requireMain();
+var main = /*@__PURE__*/getDefaultExportFromCjs(mainExports);
+
+module.exports = main;
+",
+}
+`;