[ci] Add /update command to update upstream_utils

[spacey-sooty]

No description provided.

[spacey-sooty]

💀 CI doesn't like me today, can I get gradle CI rerun please?

[calcmogul]

This command seems like a really inefficient workflow for contributors. With /format, the formatter is almost guaranteed to succeed. upstream_utils, on the other hand, often fails to apply patches and requires that they be manually rebased. It's not usually as simple as bumping the upstream tag and rerunning the script.

Something that would be kinda neat is an upstream_utils script subcommand that takes a new tag. It would try to apply the patches to the new tag, and if it failed, automatically fetch the old tag, apply the patches, then start an interactive rebase (git rebase -i) onto the new tag (git rebase sometimes includes commits it shouldn't because repos like LLVM use a separate branch for each release).

We could also make that subcommand automatically run git format-patch new_tag..HEAD --abbrev=40 --zero-commit --no-signature on success and move the generated .patch files into allwpilib.

[calcmogul]

This duplicates .github/workflows/upstream-utils.yml. Maybe you could dispatch to that workflow from here?

[Starlight220]

then start an interactive rebase (git rebase -i) onto the new tag

Do you intend for this to be interactive? Or mechanically editing the command list with something like sed?

[calcmogul]

User interaction with interactive rebase was intentional. I don't see a good way of automating it. You can have a script modify the command list, but I'm not sure if keeping the last N entries, where N is the number of patches, is sufficient.

[Starlight220]

Oh wait a moment

Git rebase has flags for this; I think this might work:

git rebase OLD_BASE HEAD --onto NEW_BASE

That should take the commit range OLD_BASE..HEAD (I keep forgetting if it includes OLD_BASE or not; if not then make it OLD_BASE^) and apply it on NEW_BASE.

I hope this is helpful

[calcmogul]

Yea, that's way easier.

[calcmogul]

OBE by #6829.