From 9f0d24bb055e4e7d205397cd7052b088c9f06264 Mon Sep 17 00:00:00 2001
From: Christoph Purrer <chpurrer@meta.com>
Date: Tue, 12 Aug 2025 23:13:16 -0700
Subject: [PATCH] Enforce void return type for void return type in JS C++ TM
 spec (#53214)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/53214

Changelog: [General] [Fixed] Enforce void return type for void return type in JS C++ TM spec

Example if you have this spec
```
export interface Spec extends TurboModule {
  +foo: (bar: string) => void;
}
```
We must enforce in C++ that the return type is `void` as e.g.
```
  void foo(jsi::Runtime& rt, const std::string& bar);
```
Right now you can return any type in C++ such as `std::string` which does not make sense

Reviewed By: lenaic

Differential Revision: D79980538

fbshipit-source-id: 9b99ea6b1ac97d1e46cdb9952e83c445ec5503b7
---
 packages/react-native/ReactCommon/react/bridging/Class.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/packages/react-native/ReactCommon/react/bridging/Class.h b/packages/react-native/ReactCommon/react/bridging/Class.h
index 00495a2e140..90a10a00956 100644
--- a/packages/react-native/ReactCommon/react/bridging/Class.h
+++ b/packages/react-native/ReactCommon/react/bridging/Class.h
@@ -27,6 +27,11 @@ JSReturnT callFromJs(
       sizeof...(ArgsT) == sizeof...(JSArgsT), "Incorrect arguments length");
   static_assert(
       (supportsFromJs<ArgsT, JSArgsT> && ...), "Incompatible arguments");
+  if constexpr (std::is_void_v<JSReturnT>) {
+    static_assert(
+        std::is_void_v<ReturnT>,
+        "Method must return void when JSReturnT is void");
+  }
 
   if constexpr (std::is_void_v<JSReturnT>) {
     (instance->*method)(