C++ TurboModule codegen names each method's invoker with a reserved identifier (__<method>) #59843

Description

The C++ spec header the codegen writes for a C++ TurboModule declares each method's static invoker as __<methodName> and registers it under that name in methodMap_. An identifier that starts with a double underscore is reserved to the implementation ([lex.name]/3, https://eel.is/c++draft/lex.name#3), so a library that compiles its own sources with clang's -Wreserved-identifier cannot include its own generated <Module>JSI.h under the -Werror React Native's build flags carry.

The names come from packages/react-native-codegen/src/generators/modules/GenerateModuleH.js on main (f480836):

• line 622: static jsi::Value __${prop.name}(jsi::Runtime &rt, TurboModule &turboModule, …)
• line 187: methodMap_["${methodName}"] = MethodMetadata {.argCount = ${paramCount}, .invoker = __${methodName}};

Expected: the generated header declares and registers each invoker under a name outside the reserved set, for example invoke_${prop.name}, with the methodMap_ key, the arity and the call into the module unchanged, so a header that compiles today still compiles.

Steps to reproduce

1. Clone the reproducer below. ReproducerApp/specs/NativeSample.ts is a TurboModule spec with one method, add(left: number, right: number): number.
2. Run its repro.sh in a node:24 container with clang:

   docker run --rm -v "$PWD:/repro:ro" node:24 bash -c \
     'apt-get update -qq && apt-get install -y -qq clang libboost-dev libdouble-conversion-dev libgoogle-glog-dev > /dev/null && bash /repro/repro.sh'

   It installs react-native@nightly, generates the spec with @react-native/codegen's combine-js-to-schema-cli.js and react-native/scripts/generate-specs-cli.js --platform ios --libraryType modules, and compiles the generated SampleJSI.h with clang++ -std=c++20 -fsyntax-only -Werror -Wreserved-identifier, reading ReactCommon and the folly, fmt and fast_float releases React Native pins as system headers.
3. Expected: the header compiles. Actual: clang refuses the generated invoker:

   ./out/SampleJSI.h:29:21: error: identifier '__add' is reserved because it starts with '__' [-Werror,-Wreserved-identifier]
   SUMMARY: react-native 0.90.0-nightly-20261107-3aed1720f's codegen names the module's invokers with reserved identifiers
   

   bash /repro/repro.sh 0.88.1 shows the same on the latest stable.

React Native Version

0.88.1

Affected Platforms

Build - Linux

Output of npx @react-native-community/cli info

System:
  OS: Linux 6.18 Debian GNU/Linux 12 (bookworm) 12 (bookworm)
  CPU: (24) x64 AMD Ryzen 9 9950X3D 16-Core Processor
  Memory: 120.26 GB / 125.63 GB
  Shell:
    version: 5.2.15
    path: /bin/bash
Binaries:
  Node:
    version: 24.22.2
    path: /usr/local/bin/node
  Yarn:
    version: 1.22.22
    path: /usr/local/bin/yarn
  npm:
    version: 11.19.1
    path: /usr/local/bin/npm
  Watchman: Not Found
SDKs:
  Android SDK: Not Found
IDEs:
  Android Studio: Not Found
Languages:
  Java: Not Found
  Ruby: Not Found
npmPackages:
  "@react-native-community/cli": Not Found
  react: Not Found
  react-native:
    installed: 0.90.0-nightly-20261107-3aed1720f
    wanted: ^0.90.0-nightly-20261107-3aed1720f
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: Not found
  newArchEnabled: Not found
iOS:
  hermesEnabled: Not found
  newArchEnabled: Not found

Stacktrace or Logs

== generate the module's C++ spec
generated out/SampleJSI.h
25:    methodMap_["add"] = MethodMetadata {.argCount = 2, .invoker = __add};
29:  static jsi::Value __add(jsi::Runtime &rt, TurboModule &turboModule, const jsi::Value* args, size_t count) {
== compile the spec with -Werror -Wreserved-identifier
./out/SampleJSI.h:29:21: error: identifier '__add' is reserved because it starts with '__' [-Werror,-Wreserved-identifier]
1 error generated.
SUMMARY: react-native 0.90.0-nightly-20261107-3aed1720f's codegen names the module's invokers with reserved identifiers

MANDATORY Reproducer

https://github.com/YevheniiKotyrlo/react-native-codegen-reserved-invoker-names

Screenshots and Videos

No response