GitHub stacked-PR builder for those who miss Gerrit

See --help for more.

Etymology

_{(Note: Early versions of this project were named gd)}

The c refers to two things:

• The tool is based around the Gerrit concept of a "change".
• The stack of PRs can instead be thought of as a "chain". "Stack" is just the de-facto consensus term.

The gh is for "GitHub", specifically the gh tool that cgh wraps.

Alternatives

spr

A very compelling alternative to cgh is https://github.com/ejoffe/spr which differs in a few ways:

• spr will modify your local branches by default for logically non-destructive operations (i.e. when you try to update the remote)
• spr won't use Gerrit Change-Id:, and is very particular about the format of its ID; cgh allows any string and uses the Change-Id: trailer
• spr does not seem to have a dry-run option, so modifications aren't foreseeable
• spr doesn't produce an "interdiff" when force-pushing to give the reviewer context for the edits to the change
• spr installs itself as a git subcommand (this is really just an aesthetic quibble, but I don't think it is primarily a git tool, it is a GitHub tool, and exists only to patch a deficiency in GitHub as a service)
• spr warns you to only close/merge PRs through it, rather than just diagnosing when e.g. a PR would be created for a change which already has a merged PR
• spr uses YAML for configuration, cgh uses TOML
• spr is noisy by default, cgh is quiet by default
• spr seems slightly less aggressive with parallelizing operations
• spr is written in Go, cgh is written in Rust

In the end most of these are fairly aesthetic and minor, but rather than try to hack on spr I opted to start over and make the exact tool I wanted. YMMV

gherrit

A tool with a very similar core philosophy, https://github.com/joshlf/gherrit seems to differ primarily in the UX and the structure of remote branches:

• Goes to greater lengths to reproduce the git push-based workflow of Gerrit proper. This involves intercepting the push through hooks.
• Retains more "phantom branches" on the remote to facilitate diffs and retain comments (if I understand it correctly).
• Also includes GH actions to keep the stack tidy and ready to merge. I don't fully understand how this works yet.

maiao

I haven't actually used https://github.com/adevinta/maiao but came across it since writing cgh. The biggest issue I see immediately is that it modifies local refs to do fixups and rebases.

graphite

I have had only negative experiences with https://graphite.dev/ and in particular my issues are:

• Modifies local refs, and inserts itself into your workflow before you even consider creating PRs
• Requires a third-party service
• Is terribly slow (on top of the already slow GH API)
• Is closed-source