Expo Android app fails building: `src/react-native` directory missing in host package

[kraenhansen]

The src/react-native directory is expected by codegen which is failing the build of an example app using the host package at v0.2.0.

Either we'd just add that directory as an empty directory or we should update the react-native.config.js file to point to another directory or disable codegen all together, since we're not actively using it as part of implementing the host's TurboModule.

> expo run:android

› Building app...
Configuration on demand is an incubating feature.

> Configure project :
[ExpoRootProject] Using the following versions:
  - buildTools:  35.0.0
  - minSdk:      24
  - compileSdk:  35
  - targetSdk:   35
  - ndk:         27.1.12297006
  - kotlin:      2.0.21
  - ksp:         2.0.21-1.0.28

> Configure project :expo

Using expo modules
  - expo-constants (17.1.7)
  - expo-modules-core (2.4.2)
  - [📦] expo-asset (11.1.7)
  - [📦] expo-file-system (18.1.11)
  - [📦] expo-font (13.3.2)
  - [📦] expo-keep-awake (14.1.4)


> Task :react-native-node-api:generateCodegenSchemaFromJavaScript FAILED
node:fs:1716
  const stats = binding.lstat(
                        ^

Error: ENOENT: no such file or directory, lstat '/Users/kraen.hansen/Repositories/node-api-example-lib/example-app/node_modules/react-native-node-api/src/react-native'
    at Object.lstatSync (node:fs:1716:25)
    at /Users/kraen.hansen/Repositories/node-api-example-lib/example-app/node_modules/react-native/node_modules/@react-native/codegen/lib/cli/combine/combine-js-to-schema.js:108:15
    at Array.flatMap (<anonymous>)
    at expandDirectoriesIntoFiles (/Users/kraen.hansen/Repositories/node-api-example-lib/example-app/node_modules/react-native/node_modules/@react-native/codegen/lib/cli/combine/combine-js-to-schema.js:107:6)
    at combineSchemasInFileList (/Users/kraen.hansen/Repositories/node-api-example-lib/example-app/node_modules/react-native/node_modules/@react-native/codegen/lib/cli/combine/combine-js-to-schema.js:123:28)
    at combineSchemasInFileListAndWriteToFile (/Users/kraen.hansen/Repositories/node-api-example-lib/example-app/node_modules/react-native/node_modules/@react-native/codegen/lib/cli/combine/combine-js-to-schema.js:142:20)
    at Object.<anonymous> (/Users/kraen.hansen/Repositories/node-api-example-lib/example-app/node_modules/react-native/node_modules/@react-native/codegen/lib/cli/combine/combine-js-to-schema-cli.js:82:1)
    at Module._compile (node:internal/modules/cjs/loader:1730:14)
    at Object..js (node:internal/modules/cjs/loader:1895:10)
    at Module.load (node:internal/modules/cjs/loader:1465:32) {
  errno: -2,
  code: 'ENOENT',
  syscall: 'lstat',
  path: '/Users/kraen.hansen/Repositories/node-api-example-lib/example-app/node_modules/react-native-node-api/src/react-native'
}

Node.js v22.15.1

[Incubating] Problems report is available at: file:///Users/kraen.hansen/Repositories/node-api-example-lib/example-app/android/build/reports/problems/problems-report.html

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':react-native-node-api:generateCodegenSchemaFromJavaScript'.
> Process 'command 'node'' finished with non-zero exit value 1

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.

Deprecated Gradle features were used in this build, making it incompatible with Gradle 9.0.

You can use '--warning-mode all' to show the individual deprecation warnings and determine if they come from your own scripts or plugins.

For more on this, please refer to https://docs.gradle.org/8.13/userguide/command_line_interface.html#sec:command_line_warnings in the Gradle documentation.

BUILD FAILED in 2s
40 actionable tasks: 6 executed, 34 up-to-date
Error: /Users/kraen.hansen/Repositories/node-api-example-lib/example-app/android/gradlew app:assembleDebug -x lint -x test --configure-on-demand --build-cache -PreactNativeDevServerPort=8081 -PreactNativeArchitectures=arm64-v8a exited with non-zero code: 1
Error: /Users/kraen.hansen/Repositories/node-api-example-lib/example-app/android/gradlew app:assembleDebug -x lint -x test --configure-on-demand --build-cache -PreactNativeDevServerPort=8081 -PreactNativeArchitectures=arm64-v8a exited with non-zero code: 1
    at ChildProcess.completionListener (/Users/kraen.hansen/Repositories/node-api-example-lib/example-app/node_modules/@expo/spawn-async/src/spawnAsync.ts:67:13)
    at Object.onceWrapper (node:events:633:26)
    at ChildProcess.emit (node:events:518:28)
    at maybeClose (node:internal/child_process:1101:16)
    at Process.ChildProcess._handle.onexit (node:internal/child_process:304:5)
    ...
    at spawnAsync (/Users/kraen.hansen/Repositories/node-api-example-lib/example-app/node_modules/@expo/spawn-async/src/spawnAsync.ts:28:21)
    at spawnGradleAsync (/Users/kraen.hansen/Repositories/node-api-example-lib/example-app/node_modules/@expo/cli/src/start/platforms/android/gradle.ts:134:28)
    at assembleAsync (/Users/kraen.hansen/Repositories/node-api-example-lib/example-app/node_modules/@expo/cli/src/start/platforms/android/gradle.ts:83:16)
    at runAndroidAsync (/Users/kraen.hansen/Repositories/node-api-example-lib/example-app/node_modules/@expo/cli/src/run/android/runAndroidAsync.ts:62:24)

[shirakaba]

For my own convenience, the src/react-native path is configured via the jsSrcsDir property defined in react-native-node-api/packages/host/package.json.

I have generally avoided working with codegen, so am not overly familiar with it. I looked into mentions of jsSrcsDir to see how codegen CLI tools handle it:

• In react-native/scripts/codegen:
  • https://github.com/facebook/react-native/blob/7725a0aee35ca3f4ac1932fae970d1f13f70c881/packages/react-native/scripts/codegen/generate-artifacts-executor/generateReactCodegenPodspec.js#L47-L50
  • https://github.com/facebook/react-native/blob/7725a0aee35ca3f4ac1932fae970d1f13f70c881/packages/react-native/scripts/codegen/generate-artifacts-executor/generateSchemaInfos.js#L30-L33
• In @react-native/gradle-plugin: https://github.com/facebook/react-native/blob/7725a0aee35ca3f4ac1932fae970d1f13f70c881/packages/gradle-plugin/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/ReactPlugin.kt#L163-L170
• In expo-modules-autolinking: https://github.com/expo/expo/blob/main/packages/expo-modules-autolinking/src/reactNativeConfig/androidResolver.ts#L204-L206

I notice in particular that, in generateReactCodegenPodspec.js (linked above) that if jsSrcsDir is left undefined, then the podspec will just assume an empty array of files, which sounds like exactly what we want. So how about we just omit the jsSrcsDir property from react-native-node-api/packages/host/package.json altogether?

[shirakaba]

Although I may be speaking too soon. Although react-native/scripts/codegen's generateReactCodegenPodspec.js handles a missing jsSrcsDir field elegantly, I see that expo-modules-autolinking's androidResolver.ts falls back to globbing all files under the package root, which seems like a disaster waiting to happen. I haven't looked closely at the other implementations, but that one should be reason enough.

So I'd say it'd be better to point it at some guaranteed-to-exist empty directory than omit the field altogether.

[kraenhansen]

Sounds like a fine workaround for the time being 👍 Perhaps we should file an upstream issue as well?

[kraenhansen]

I tried to omit the codegenConfig from the Host package entirely:

react-native-node-api/packages/host/package.json

Line 100 in 8dac805

"codegenConfig": {

The iOS app builds fine but the issue persists on Android.