(iOS) Codegen package isn't built while using old architecture

[Saadnajmi]

Description

When building RNTester on iOS with the old architecture, we skip a call to build_codegen, which will build the JS package at packages/react-native-codegen. This is needed for the Xcode Script phase Generate Specs. For some reason, this only happens on main and not 0.71-stable (where packages/react-native-codegen doesn't need to be built for some reason).

In React Native macOS, we fixed this by ensuring the ruby method build_codegen is called for both paper and fabric.

Version

nightly

Output of npx react-native info

System:
OS: macOS 13.2
CPU: (12) arm64 Apple M2 Max
Memory: 22.18 GB / 64.00 GB
Shell: 5.8.1 - /bin/zsh
Binaries:
Node: 18.14.0 - ~/.asdf/installs/nodejs/18.14.0/bin/node
Yarn: 1.22.19 - /usr/local/bin/yarn
npm: 9.3.1 - ~/.asdf/plugins/nodejs/shims/npm
Watchman: Not Found
Managers:
CocoaPods: 1.11.3 - /usr/local/bin/pod
SDKs:
iOS SDK:
Platforms: DriverKit 22.2, iOS 16.2, macOS 13.1, tvOS 16.1, watchOS 9.1
Android SDK: Not Found
IDEs:
Android Studio: 2022.1 AI-221.6008.13.2211.9514443
Xcode: 14.2/14C18 - /usr/bin/xcodebuild
Languages:
Java: Not Found
npmPackages:
@react-native-community/cli: Not Found
react: Not Found
react-native: Not Found
react-native-macos: Not Found
npmGlobalPackages:
react-native: Not Found

Steps to reproduce

1. Clone React Native
2. yarn install
3. cd packages/rn-tester
4. Modify Podfile to disable fabric (fabric_enabled = false)
5. bundle install && bundle exec pod install
6. xcodebuild -workspace RNTesterPods.xcworkspace -scheme RNTester -configuration debug -sdk iphonesimulator

• Or if you prefer, run yarn test-ios from the root of the repo. I'd disable xcpretty as it suppresses the error message.

Expected result: Build succeeds
Actual result: Build fails with error:

Error: Cannot find module '/Users/sanajmi/workspace/react-native/packages/react-native-codegen/lib/cli/combine/combine-js-to-schema-cli.js'

Snack, code example, screenshot, or link to a repository

N/A, since this is building React Native off of the public Github repo. The Repro steps above should suffice.