fix: correctly wraps the default export from a CommonJS module when i…

…t is a class

Fixes https://github.com/vitejs/vite/issues/10853

Since rollup@3c00191
the namespace became callable when requiring ESM with function default,
but it isn't newable, leading to errors when the function is actually a
class.

packages/commonjs/src/helpers.js

@@ -37,7 +37,13 @@ export function getDefaultExportFromNamespaceIfNotNamed (n) {
 export function getAugmentedNamespace(n) {
   var f = n.default;
 	if (typeof f == "function") {
-		var a = function () {
+		var a = function a () {
+			if (this instanceof a) {
+				var args = [null];
+				args.push.apply(args, arguments);
+				var Ctor = Function.bind.apply(f, args);
+				return new Ctor();
+			}
 			return f.apply(this, arguments);
 		};
 		a.prototype = f.prototype;

packages/commonjs/test/fixtures/samples/es-module-with-class-as-default-export/main.js

@@ -0,0 +1,3 @@
+const Foo = require('./other.js');
+
+new Foo(1, 2)

packages/commonjs/test/fixtures/samples/es-module-with-class-as-default-export/other.js

@@ -0,0 +1,7 @@
+export default class Foo {
+  constructor(...args) {
+    if (args.length !== 2) {
+      throw new Error(`new Foo(...) requires exactly 2 arguments, received ${args.length}`);
+    }
+  }
+}

packages/commonjs/test/test.js

@@ -445,6 +445,15 @@ test('prefers to set name using directory for index files', async (t) => {
   t.not(code.indexOf('var nonIndex'), -1, 'contains nonIndex');
 });
 
+test('correctly wraps the default export from a CommonJS module when it is a class', async (t) => {
+  const bundle = await rollup({
+    input: 'fixtures/samples/es-module-with-class-as-default-export/main.js',
+    plugins: [commonjs()]
+  });
+  const result = await executeBundle(bundle, t);
+  t.is(result.error, undefined);
+});
+
 test('does not warn even if the ES module does not export "default"', async (t) => {
   const warns = [];
   await rollup({