Codegen for Android does not output flat struct for rn-gradle-plugin

[ospfranco]

Description

I'm trying to write a CPP Turbo Module. I have the following config that generates the files under android/generated:

However, when I try to build my app, I get the following error:

Which then throws the following error:

You can see the folder structure under android/generated does not match. Am I doing something wrong?

Packages

• [X] create-react-native-library
• [ ] react-native-builder-bob

Selected options

C++ Turbo Module with Vanilla app

Link to repro

-

Environment

System:
  OS: macOS 15.0
  CPU: (11) arm64 Apple M3 Pro
  Memory: 919.00 MB / 36.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 18.20.2
    path: ~/.local/share/mise/installs/node/18/bin/node
  Yarn:
    version: 3.6.1
    path: ~/.local/share/mise/installs/node/18/bin/yarn
  npm:
    version: 10.5.0
    path: ~/.local/share/mise/installs/node/18/bin/npm
  Watchman:
    version: 2024.06.24.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods:
    version: 1.15.2
    path: /Users/osp/.local/share/mise/installs/ruby/3/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 24.0
      - iOS 18.0
      - macOS 15.0
      - tvOS 18.0
      - visionOS 2.0
      - watchOS 11.0
  Android SDK:
    API Levels:
      - "33"
      - "34"
    Build Tools:
      - 30.0.3
      - 33.0.0
      - 33.0.1
      - 34.0.0
      - 35.0.0
    System Images:
      - android-33 | Google Play ARM 64 v8a
    Android NDK: 26.1.10909125
IDEs:
  Android Studio: 2024.1 AI-241.19072.14.2412.12360217
  Xcode:
    version: 16.0/16A242d
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.11
    path: /usr/bin/javac
  Ruby:
    version: 3.3.1
    path: /Users/osp/.local/share/mise/installs/ruby/3/bin/ruby
npmPackages:
  "@react-native-community/cli": Not Found
  react:
    installed: 18.3.1
    wanted: 18.3.1
  react-native:
    installed: 0.75.2
    wanted: 0.75.2
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: Not found
  newArchEnabled: Not found
iOS:
  hermesEnabled: Not found
  newArchEnabled: Not found

[okwasniewski]

Hey, outputDir is not specific to bob (PR introducing it: https://github.com/facebook/react-native/pull/41782), so if you are running into issues you should probably open a PR in React Native repository.

[ospfranco]

Thanks for taking a look @okwasniewski!

Yeah, after looking at the code I realized it comes from RN itself, just thought maybe bob modified the generation process further (other than patching the package). If it's not I will go spelunking myself.

Another question, what does the following object do in the package.json?

  "create-react-native-library": {
    "type": "module-new",
    "languages": "cpp",
    "version": "0.41.1"
  }

It is important somehow?

[ospfranco]

Also, as a side note, this is not properly implemented in bob I believe. Pure RN allows to nos specify the path, but the patchCodegen.js script fails if no output path is specified, maybe this is messing up the generation for my use case.

[okwasniewski]

Yeah, after looking at the code I realized it comes from RN itself, just thought maybe bob modified the generation process further (other than patching the package). If it's not I will go spelunking myself.

I will cc @atlj because I don't have inside knowledge about this.

Another question, what does the following object do in the package.json?

  "create-react-native-library": {
    "type": "module-new",
    "languages": "cpp",
    "version": "0.41.1"
  }

This was introduced by @atlj here: https://github.com/callstack/react-native-builder-bob/pull/551

It's going to be used in the future for a library upgrade helper 👀

[ospfranco]

ok, I understand, thanks for clarifying. Can you give me a hand and tell me what does:

npx bob build --target codegen

do? Like, what's exactly is it calling. From what I can see in the filesystem bob is a binary of some sorts but it would be good which command it calls so I know how the codegen is being generated, much appreciated!

[ospfranco]

Hmm I just re-generated my sources and everything is compiling just fine, weird. I will close this for now, re-open if necessary.