fix: Correctly assign the hermes-engine pod tag when installing pods from a different folder

[gvarandas]

Summary:

This PR aims to fix an issue where installing iOS pods from a different directory causes the hermes-engine :tag: not to be properly resolved.

Ever since #37148 was merged, the setup_hermes script tries to resolve the node_modules/react-native/sdks/.hermesversion file and use its content to generate the pod tag, in order to verify when it changes over time.
This works perfectly when installing pods within the ios folder, as the react_native_path should point to the correct relative folder (../node_modules/react-native by default).

However, when installing pods from a different directory (the project root, for example) and leveraging the --project-directory flag, the file fails to resolve, as the current working directory is considered when resolving the .hermesversion file.

Quick Example:

• react_native_path: ../node_modules/react-native (the default config)

Installing pods from the ios folder:

• cd ios
• bundle exec pod install
• hermestag_file resolved path: $project_root/node_modules/react-native ✅
• hermes-engine :tag:: hermes-2023-03-20-RNv0.72.0-49794cfc7c81fb8f69fd60c3bbf85a7480cc5a77 ✅

Installing pods from the $project_root folder

• bundle exec pod install --project-directory=ios
• hermestag_file resolved path: $parent_folder/$project_root/node_modules/react-native ❌
• hermes-engine :tag:: '' ❌

The fix

Turns out that the same file had a resolved reference to the react-native folder, assigned to the react_native_dir variable:

react_native_dir = Pod::Config.instance.installation_root.join(react_native_path)

By resolving the .hermesversion using that folder, we guarantee that the relative path will always reference the directory where the Podfile is defined, which is the expected behaviour.

Changelog:

Test Plan:

• Init a new react-native repo
• Remove the generated Podfile.lock file
• Navigate to the project root folder
• bundle exec pod install -project-directory=ios
• Check that the hermes-engine entry has a properly populated :tag: attribute:

Before:

hermes-engine:
    :podspec: "../node_modules/react-native/sdks/hermes-engine/hermes-engine.podspec"
    :tag: ''

After:

hermes-engine:
    :podspec: "../node_modules/react-native/sdks/hermes-engine/hermes-engine.podspec"
    :tag: hermes-2023-03-20-RNv0.72.0-49794cfc7c81fb8f69fd60c3bbf85a7480cc5a77

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	8,894,300	-1
android	hermes	armeabi-v7a	7,942,875	+3
android	hermes	x86	9,292,201	-1
android	hermes	x86_64	9,193,733	-3
android	jsc	arm64-v8a	9,480,955	-1
android	jsc	armeabi-v7a	8,422,521	+0
android	jsc	x86	9,464,983	-2
android	jsc	x86_64	9,779,239	-2

Base commit: 1f24750
Branch: main

[cipolleschi]

Love it! Thanks @gvarandas for this fix!

[facebook-github-bot]

@cipolleschi has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@cipolleschi merged this pull request in 08688d3.