[iOS] Library project generated for Turbo Module fails to build with React Native 0.77.0

[birdofpreyru]

Description

Linker reports duplicated symbols, in my current understanding they happen because of a name clash between the code generated by codegen for the library, and some similar code generated by codegen for the app itself (the screenshot is from a library I maintain, after resetting its scaffolding with the latest create-react-native-library version, and RN@0.77; but I got the same problem with just new project created by create-react-native-library, with no subsequent changes):

Packages

• create-react-native-library
• react-native-builder-bob

Selected options

N/A

Link to repro

https://github.com/birdofpreyru/react-native-fs/tree/dev-v2.31

Environment

N/A

[birdofpreyru]

Might be related to #754 — exploring my project I see that Codegen generates some .podspec file into android/generated path... so I guess, it might be also unnecessary generating some code intended only for the app into folders related to the library?

[elichai]

Same issue,
According to this: https://github.com/reactwg/react-native-new-architecture/blob/main/docs/turbo-modules.md#4-native-code
The library shouldn't provide any generated code according to:

Warning
The code generated by Codegen in this step should not be committed to the versioning system. React Native apps are able to generate the code when the app is built. This allows an app to ensure that all libraries have code generated for the correct version of React Native. It is also possible to include the codegen output into your library.

EDIT: I now found this: https://github.com/reactwg/react-native-new-architecture/blob/main/docs/codegen.md#including-generated-code-into-libraries so I'm no longer sure :)

[ospfranco]

I just created a new library and also faced duplicated symbols. I guess there is something about the template that breaks.

That being said I also faced an issue with included codegen code in the distribution

facebook/react-native-website#4460

This was also discussed internally in the react-native maintainer discord and indeed the documentation is not clear. Codegen code can break between versions, so builder-bob should not turn on this IMO.

In any case, if you guys have a workaround to get builder-bob working with the C++ template again let me know. Maybe it's just a case of downgrading to 0.76.6.

[elichai]

@ospfranco It seems that USE_FRAMEWORKS=dynamic bundle exec pod install solves it, not sure if it's the right solution but it does seems to solve it

[satya164]

We include codegen in the library by default according to React Native team's recommendation. Quoting Riccardo Cipolleschi:

Going forward, the suggested approach would be for libraries to run Codegen locally and the to ship the codegenerated files with the rest of the code in NPM. This ensure that the code that is generate is compatible with the specific version of the codegen used when developing the library and that there is no risk for ABI incompatibility.

Plus, the libraries becomes buildable independently from being deployed together with a React Native app.

We are also providing a new CLI command (npx react-native codegen ) to run codegen locally from libraries.

This approach also solve the double source-set issue we had for more than a year on Android and it simplifies the setup for apps and libraries, in theory

If this approach is now causing issues then I think it either needs to be fixed in React Native, or have an updated recommendation from RN team.

However by not including codegen files, there's always risk of getting different native code in the app than what you tested with.

[atlj]

Hey folks, it looks like the codegen cli now generates a pod target when we call it. And the pod target has some files that are also generated with the app's codegen that cause a duplication. I pinged the React Native team and they told that this was an unintentional break. This will be probably fixed with the newer versions of React Native. For now, I'm going to patch this on bob level.