fix: hardcode immutableBinding to true for export default

xiaoxiaojx · xiaoxiaojx · commit 77b8e549aa6a · 2026-06-07T16:40:02.000+08:00
The default binding is always immutable per ES spec. Safety is
ensured by the isCircular === false check which requires
CircularModulesPlugin to have run.
diff --git a/lib/dependencies/HarmonyExportExpressionDependency.js b/lib/dependencies/HarmonyExportExpressionDependency.js
@@ -61,15 +61,12 @@ class HarmonyExportExpressionDependency extends NullDependency {
 			pureFunctions && pureFunctions.has(DEFAULT_EXPORT_NAME)
 		);
 
-		// Expression default (`export default expr`) generates a const binding;
-		// declaration default (`export default function/class`) is mutable.
-		const isImmutable = !this.declarationId;
 		return {
 			exports: [
 				{
 					name: DEFAULT_EXPORT_NAME,
 					isPure: isPure || undefined,
-					immutableBinding: isImmutable || undefined
+					immutableBinding: true
 				}
 			],
 			priority: 1,
