From 37b76883d8e9f7a6cb85c12d1eb76702a53726af Mon Sep 17 00:00:00 2001
From: Perryvw <perryvw@users.noreply.github.com>
Date: Sat, 24 May 2025 16:04:49 +0200
Subject: [PATCH] Fix decorator on class exported from namespace

---
 src/transformation/utils/export.ts         |  8 ++++++++
 src/transformation/visitors/class/index.ts |  4 ++--
 test/unit/classes/decorators.spec.ts       | 24 +++++++++++++++++++++-
 3 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/src/transformation/utils/export.ts b/src/transformation/utils/export.ts
index fa1c03649..f0ef437e5 100644
--- a/src/transformation/utils/export.ts
+++ b/src/transformation/utils/export.ts
@@ -20,6 +20,14 @@ export function hasExportModifier(node: ts.Node): boolean {
     );
 }
 
+export function shouldBeExported(node: ts.Node): boolean {
+    if (hasExportModifier(node)) {
+        // Don't export if we're inside a namespace (module declaration)
+        return ts.findAncestor(node, ts.isModuleDeclaration) === undefined;
+    }
+    return false;
+}
+
 export const createDefaultExportStringLiteral = (original?: ts.Node): lua.StringLiteral =>
     lua.createStringLiteral("default", original);
 
diff --git a/src/transformation/visitors/class/index.ts b/src/transformation/visitors/class/index.ts
index 0edfce050..d4633995e 100644
--- a/src/transformation/visitors/class/index.ts
+++ b/src/transformation/visitors/class/index.ts
@@ -5,8 +5,8 @@ import {
     createDefaultExportExpression,
     createExportedIdentifier,
     hasDefaultExportModifier,
-    hasExportModifier,
     isSymbolExported,
+    shouldBeExported,
 } from "../../utils/export";
 import { createSelfIdentifier } from "../../utils/lua-ast";
 import { createSafeName, isUnsafeName } from "../../utils/safe-names";
@@ -214,7 +214,7 @@ function transformClassLikeDeclaration(
         const decoratingStatement = lua.createAssignmentStatement(localClassName, decoratingExpression);
         result.push(decoratingStatement);
 
-        if (hasExportModifier(classDeclaration)) {
+        if (shouldBeExported(classDeclaration)) {
             const exportExpression = hasDefaultExportModifier(classDeclaration)
                 ? createDefaultExportExpression(classDeclaration)
                 : createExportedIdentifier(context, className);
diff --git a/test/unit/classes/decorators.spec.ts b/test/unit/classes/decorators.spec.ts
index 1923f8b2b..4782746be 100644
--- a/test/unit/classes/decorators.spec.ts
+++ b/test/unit/classes/decorators.spec.ts
@@ -138,7 +138,7 @@ test("Exported class decorator", () => {
 });
 
 // https://github.com/TypeScriptToLua/TypeScriptToLua/issues/1149
-test("exported class with decorator", () => {
+test("exported class with decorator (#1149)", () => {
     util.testModule`
         import { MyClass } from "./other";
         const inst = new MyClass();
@@ -164,6 +164,28 @@ test("exported class with decorator", () => {
         .expectToEqual({ result: "overridden" });
 });
 
+// https://github.com/TypeScriptToLua/TypeScriptToLua/issues/1634
+test("namespaced exported class with decorator (#1634)", () => {
+    util.testModule`
+        function myDecorator(target: {new(): any}, context: ClassDecoratorContext) {
+            return class extends target {
+                foo() {
+                    return "overridden";
+                }
+            }
+        }
+
+        namespace ns {
+            @myDecorator
+            export class MyClass {
+                foo() {
+                    return "foo";
+                }
+            }
+        }
+    `.expectNoExecutionError();
+});
+
 test("default exported class with decorator", () => {
     util.testModule`
         import MyClass from "./other";