Summary:
Ref T13098. Depends on D19675. This change is headed to the `untamed-wilds` branch.
This change prevents `arc` from running `arc diff`, so I'm copy/pasting it.
This change also completely breaks `arc`, but I'm just generally trying to do this rewrite step-by-step so we have at least a bit of context to refer to in the future.
The major change here is to turn both `arc` and `phage` into scripts which start an `ArcanistRuntime`. This runtime then decides which workflows (like "diff", "patch", or "remote") are available based on `$argv[0]`. This turns `arc` into more of a CLI tools platform: we can build `phage` on it, third parties can build `my-companion-tool-thing`, etc. But all the different entry points can share a lot of infrastructure like: `help`, `alias`, shell-complete, configuration, Conduit, prompting, `--trace`, extension infrastructure, and so on.
`ArcanistRuntime` is roughly a slightly more modern version of `scripts/arcanist.php`. That will be removed eventually, but not everything has ported yet.
Test Plan: This code basically doesn't run yet, although the next patch runs at least a little bit.
Reviewers: amckinley
Reviewed By: amckinley
Maniphest Tasks: T13098
Differential Revision: https://secure.phabricator.com/D19677
