Add Josh sync scripts

[Kobzol]

This pretty much 1:1 mirrors the sync scripts of rustc-dev-guide. If you want, I can also setup a CI bot (similar to rdg or miri) that will attempt to create PRs with pull synces once every few days, and post to Zulip if there is a merge conflict.

[rustbot]

r? @Amanieu

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[Kobzol]

r? @RalfJung

[rustbot]

Failed to set assignee to RalfJung: invalid assignee

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[tgross35]

I have a couple changes from the RDG version in https://github.com/rust-lang/compiler-builtins/tree/674910e0fa6f0fb2cc055f4f7051ff0eb53c7735/crates/josh-sync that might be worth picking up here. The biggest thing is dropping clap since that adds 30 extra deps to the lockfile, bit of overkill for parsing two possible commands. (anyhow and xshell are dropped too , but those are lighter weight to start).

Also just updating the commit messages to crosslink the original ref (e.g. rust-lang/compiler-builtins@6e475af). You can figure this out from the rust-version file but it's nice to have it show up in the log of anything that got touched in the sync. Similar for the PR message (will probably add an option to just open a PR via gh at some point to avoid percent encoding something more detailed).

[Kobzol]

My original plan was to create a separate repo that would contain the josh sync scripts, and they could be reused for all subtrees, either as a library or as a binary that could be cargo install-ed. Now that we have probably all of the submodules that we wanted to have as subtrees (maybe with the exception of Cargo), I wonder if it would maybe be better to create this repo, to avoid having N separate copies of these scripts scattered across various repositories 🤔

[RalfJung]

Yeah, that sounds like a good idea.

I'd prefer not to have to install gh on my machine if that's an option. :)

[Kobzol]

This script doesn't use gh (haven't looked at Trevor's script yet). Ideally it should install everything on its own, i.e. download and run josh and then just do operations using the git binary.

[tgross35]

Oh, yeah, mine only needs josh+git as well (only the deps and commit messages are different). I was just thinking a "would you like to open a PR via gh? Y/N" option alternative to the link.

[RalfJung]

If it generates the link it might as well open it then rather than relying on gh. ;)

[Amanieu]

My original plan was to create a separate repo that would contain the josh sync scripts, and they could be reused for all subtrees, either as a library or as a binary that could be cargo install-ed. Now that we have probably all of the submodules that we wanted to have as subtrees (maybe with the exception of Cargo), I wonder if it would maybe be better to create this repo, to avoid having N separate copies of these scripts scattered across various repositories 🤔

Would it make sense to centralize all the sync scripts in rust-lang/rust since this is where all the repos are synced as sub-trees?

[Kobzol]

Would it make sense to centralize all the sync scripts in rust-lang/rust since this is where all the repos are synced as sub-trees?

I was thinking about that, but I'm not sure it's that useful, because both pulls and pushes are invoked from the subtree repo, not from the rust-lang/rust repo.