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Codegen variable naming can result in incorrect code #53839
Description
Description
type MyEventType = {
type: string;
payload: {
message: string;
}
};
export interface NativeProps extends ViewProps {
onPressed?: CodegenTypes.BubblingEventHandler<MyEventType> | null;
}codegen generates such a code not the payload variable gets shadowed. And the bug is in the line: payload.setProperty(runtime, "payload", payload);
void SimpleViewEventEmitter::onPressed(OnPressed event) const {
dispatchEvent("pressed", [event=std::move(event)](jsi::Runtime &runtime) {
auto payload = jsi::Object(runtime);
payload.setProperty(runtime, "type", event.type);
{
auto payload = jsi::Object(runtime);
payload.setProperty(runtime, "message", event.payload.message);
payload.setProperty(runtime, "payload", payload);
}
return payload;
});
}See
https://github.com/mfazekas/codegen-variable-naming-bug
Steps to reproduce
check out https://github.com/mfazekas/codegen-variable-naming-bug
cd ReproducerApp/ios
pod install
cat build/generated/ios/react/renderer/components/AppSpec/EventEmitters.cpp
React Native Version
0.81.4
Affected Platforms
Other (please specify)
Areas
Codegen
Output of npx @react-native-community/cli info
info Fetching system and libraries information...
System:
OS: macOS 15.6
CPU: (12) arm64 Apple M2 Max
Memory: 125.66 MB / 32.00 GB
Shell:
version: "5.9"
path: /bin/zsh
Binaries:
Node:
version: 22.16.0
path: ~/.nvm/versions/node/v22.16.0/bin/node
Yarn:
version: 1.22.21
path: ~/.local/bin/yarn
npm:
version: 11.5.2
path: ~/.nvm/versions/node/v22.16.0/bin/npm
Watchman:
version: 2025.06.30.00
path: /opt/homebrew/bin/watchman
Managers:
CocoaPods:
version: 1.16.2
path: /Users/boga/.rbenv/shims/pod
SDKs:
iOS SDK:
Platforms:
- DriverKit 24.5
- iOS 18.5
- macOS 15.5
- tvOS 18.5
- visionOS 2.5
- watchOS 11.5
Android SDK: Not Found
IDEs:
Android Studio: 2025.1 AI-251.26094.121.2513.14007798
Xcode:
version: 16.4/16F6
path: /usr/bin/xcodebuild
Languages:
Java:
version: 20.0.1
path: /usr/bin/javac
Ruby:
version: 2.7.8
path: /Users/boga/.rbenv/shims/ruby
npmPackages:
"@react-native-community/cli": Not Found
react: Not Found
react-native: Not Found
react-native-macos: Not Found
npmGlobalPackages:
"*react-native*": Not Found
Android:
hermesEnabled: true
newArchEnabled: true
iOS:
hermesEnabled: true
newArchEnabled: true
Stacktrace or Logs
n/a
MANDATORY Reproducer
https://github.com/mfazekas/codegen-variable-naming-bug
Screenshots and Videos
No response
Activity
mfazekas commentedon Sep 18, 2025
In this case the use of
payloadwas a curlpit.But we can have the same issue with
Possible solutions:
payload_1, etc.Possible workarounds:
Relevant code:
https://github.com/facebook/react-native/blob/6ef351b3cea4103c72eb4657aebb5a7a8f1232e7/packages/react-native-codegen/src/generators/components/GenerateEventEmitterCpp.js#L379-L386
https://github.com/facebook/react-native/blob/6ef351b3cea4103c72eb4657aebb5a7a8f1232e7/packages/react-native-codegen/src/generators/components/GenerateEventEmitterCpp.js#L113-L137
cortinico commentedon Sep 18, 2025
This feels like the correct solution IMHO. Could you send us a PR + make sure the code is documented to explain why variables are renamed
react-native-bot commentedon Mar 19, 2026
This issue is stale because it has been open for 180 days with no activity. It will be closed in 7 days unless you comment on it or remove the "Stale" label.
react-native-bot commentedon Sep 18, 2026
This issue is stale because it has been open 180 days with no activity. Remove stale label or comment or this will be closed in 7 days.
react-native-bot commentedon Sep 25, 2026
This issue was closed because it has been stalled for 7 days with no activity.