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@blasten You are welcome to take a look/try it out. But heads up, the robustness still needs a lot of work. This works nicely for apps that were generated with a previous stable version as the fallback base commit discovery isn't quite fully fleshed out yet.

cc @jmagman @hellohuanlin This should be in a working-enough state to try out. Best way to see how it works cleanly is to create a new project with an old version of flutter, then run the migrate tool on it.

I'd be interested in if there are any ios specific issues/files/edge cases that should be handled.

@jmagman I am seeing that the migration tool is finding merge conflicts when attempting to merge modern versions of ios/Runner.xcodeproj/project.pbxproj with old versions. This file seems to be a machine-handled file that is quite long and unwieldy. Fixing ~6 merge conflicts in this file does not seem like a good user experience.

Do you have any context on how this file changes over time, and the risk of breaking the file either due to a bad merge or it becoming outdated? Is it something we can choose to not handle and xcode will update it for us through context?

Here is an example conflicted file: https://gist.github.com/GaryQian/9313b4424b30ee0efe4e07464d2018c6

@jmagman I am seeing that the migration tool is finding merge conflicts when attempting to merge modern versions of ios/Runner.xcodeproj/project.pbxproj with old versions. This file seems to be a machine-handled file that is quite long and unwieldy. Fixing ~6 merge conflicts in this file does not seem like a good user experience.

Do you have any context on how this file changes over time, and the risk of breaking the file either due to a bad merge or it becoming outdated? Is it something we can choose to not handle and xcode will update it for us through context?

Here is an example conflicted file: https://gist.github.com/GaryQian/9313b4424b30ee0efe4e07464d2018c6

ios/Runner.xcodeproj/project.pbxproj is the Xcode project that defines how the app is compiled, scripts that call into Flutter, how plugins are embedded, user build settings like display name, signing details. The user could also add more complicated iOS features (extensions) like rich notification handling.
I wouldn't want users ever trying to handle merge conflicts in that file. We should either be confident we can change it for them:
https://github.com/flutter/flutter/blob/e028d0f046c20c61b7c7c8a23bc456f337410658/packages/flutter_tools/lib/src/ios/migrations/project_base_configuration_migration.dart
or the user should own that file and deal with changing it themselves.

Ok, thanks for the explanation/advice. I think for now, we can just skip that file and have the user own it.

Currently, I definitely cannot guarantee we can fully handle the file, and manually resolving conflicts in it sounds very risky indeed. I will do some testing to see if not migrating that file can cause iOS build issues.

Once you're satisfied with this change I recommend breaking this up into smaller reviews to get thorough feedback.

@GaryQian per this comment, it sounds like you're not really going to land this, but instead smaller incremental changes? Given this, I am going to mark this a draft so it doesn't show up in PR review. Feel free to mark ready for review if I am mistaken.

Yeah, feel free to mark as draft. Ive already broken this up, and am using this as a master reference

This pull request has been changed to a draft. The currently pending flutter-gold status will not be able to resolve until a new commit is pushed or the change is marked ready for review again.

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Superseded by #100284