feat(ios): add possibility to add arguments to hermes

[Thanaen]

Summary:

Today, someone who wants to use a third-party bundler (like rnx-kit's bundler, for example) can do so by exporting the "BUNDLE_COMMAND" variable in the "Bundle React Native code and images" phase in XCode.

This Pull Request would allow the user to customize the compilation step via hermes, by allowing him to add arguments.
This is already possible on Android, thanks to the "hermesFlag" property (addable in android/app/build.gradle).

In my case, this would allow me to add the "-w" flag to hermes so that the compilation emits less logs (which breaks the archiving when using rnx-kit as a bundler).

Linked issues:
microsoft/rnx-kit#2419
microsoft/rnx-kit#2424

Changelog:

[INTERNAL] [ADDED] - Add possibility to add arguments to hermes on XCode via HERMES_EXTRA_ARGS environment variable

Test Plan:

I tested locally my modification: the arguments added via the environment variable are well transmitted to Hermes, and the compilation always works when no argument is added, or when the variable is not exported in the bundle phase on XCode.

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[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	8,739,375	-6
android	hermes	armeabi-v7a	8,050,271	-3
android	hermes	x86	9,229,564	-5
android	hermes	x86_64	9,081,394	-3
android	jsc	arm64-v8a	9,302,720	-4
android	jsc	armeabi-v7a	8,491,195	-4
android	jsc	x86	9,363,975	-4
android	jsc	x86_64	9,619,915	-4

Base commit: 1671247
Branch: main

[NickGerleman]

Change makes sense to me but it looks like this ran into a merge conflict.

[cipolleschi]

Hi @Thanaen! Thanks for this contribution and for helping us keeping Android and iOS aligned.

Changes looks good to me, just a minor change to make our linters happy.

Out of curiosity, where did you set the -w flag? Did you manually update the Xcode script exporting the $HERMES_EXTRA_ARGS?

[cipolleschi]

Thanks for adding the quotes!

[cipolleschi]

could you also fix the merge conflicts, please? 🙏

[Thanaen]

I'll get the conflicts resolved as soon as possible! (I was able to add the suggested changes directly from the GitHub mobile app, but I can't resolve conflicts from the app!)

Out of curiosity, where did you set the -w flag? Did you manually update the Xcode script exporting the $HERMES_EXTRA_ARGS?

To test my modification, I directly modified the "Bundle React Native code" phase in XCode!
(By adding the line export HERMES_EXTRA_ARGS=-w)

Does everything look right to you for the commits and PR messages? I wasn't quite sure what wording to use, I based it on what I usually do!

[cipolleschi]

Everything is right to me. I was curious to understand your use case and how/where you intend export the variables specifically.
I hate that we have all those scripts in Xcode, I would love to move them somewhere else and, perhaps, rewrite them in a different language (maybe JS... Swift for iOS would be even better! :D). So, by knowing better your use case, I could have some more ideas! 😄

[Thanaen]

My use case is a bit particular: it's simply to solve a bug I encounter when trying to use rnx-kit as a bundler for my application.

When I set up rnx-bundle as a bundle command, I could not create archives of my application because of the problem described here: microsoft/rnx-kit#2424

We found that passing the "-w" parameter to Hermes solved this bug, but I did not find an easy way to pass this parameter to Hermes when archiving an iOS project.
Hence this new environment variable!

I hope I answer your question about my use case!

Maybe we could find a way to share this kind of settings in the future, so we don't have to configure these flags or the bundle command for Android and iOS!

[cipolleschi]

/rebase