Only add export setter for non-esm exports

packages/core/integration-tests/test/integration/scope-hoisting/commonjs/mutated-exports-mixed-module/index.js

@@ -0,0 +1,6 @@
+const value = require('./value');
+value.cjs = value.cjs + ' mutated';
+value.esm = value.esm + ' mutated';
+
+
+output = [value.cjs, value.esm, value];

packages/core/integration-tests/test/integration/scope-hoisting/commonjs/mutated-exports-mixed-module/value.js

@@ -0,0 +1,3 @@
+export const esm = 'ESM';
+
+module.exports.cjs = 'CJS'

packages/core/integration-tests/test/scope-hoisting.js

@@ -4183,6 +4183,21 @@ describe('scope hoisting', function () {
       assert.deepEqual(await run(b), 4);
     });
 
+    it('supports mutations of the cjs exports by the importer from a mixed module', async function () {
+      let b = await bundle(
+        path.join(
+          __dirname,
+          '/integration/scope-hoisting/commonjs/mutated-exports-mixed-module/index.js',
+        ),
+      );
+
+      assert.deepEqual(await run(b), [
+        'CJS mutated',
+        'ESM',
+        {cjs: 'CJS mutated', esm: 'ESM'},
+      ]);
+    });
+
     it.skip('supports require.resolve calls for excluded modules', async function () {
       let b = await bundle(
         path.join(

packages/packagers/js/src/ScopeHoistingPackager.js

@@ -1096,9 +1096,11 @@ ${code}
           .map(exp => {
             let resolved = this.getSymbolResolution(asset, asset, exp);
             let get = this.buildFunctionExpression([], resolved);
-            let set = asset.meta.hasCJSExports
-              ? ', ' + this.buildFunctionExpression(['v'], `${resolved} = v`)
-              : '';
+            let isEsmExport = !!asset.symbols.get(exp)?.meta?.isEsm;
+            let set =
+              !isEsmExport && asset.meta.hasCJSExports
+                ? ', ' + this.buildFunctionExpression(['v'], `${resolved} = v`)
+                : '';
             return `$parcel$export($${assetId}$exports, ${JSON.stringify(
               exp,
             )}, ${get}${set});`;