[PATCH 0/6] Importing and exporting stashes to refs

Stashes are currently stored using the reflog in a given repository. This is an interesting and novel way to handle them, but there is no way to easily move a stash across machines. For example, stashes cannot be bundled, pushed, or fetched.

This is suboptimal for a lot of reasons. First, there is a recent push towards ephemeral development environments, but many users make heavy use of their stashes and wish to persist them long term[0]. Additionally, it would be convenient to share a snapshot of in-progress work with a colleague or a collaborator on a project. And finally, many users wish to sync their in-progress state across machines, and we currently have no good way to do so, so they often do dangerous things like using cloud syncing services for their repositories.

Let's solve this problem by allowing users to import and export stashes to a chain of commits. The commits used in a stash export are nearly identical to those used in the stashes, with one notable change: the first parent of a stash is a pointer to the previous stash, or an empty commit if there is no previous stash. All of the other parents used in the stash commit are present following it in their normal order.

This allows users to write their exported stashes to a single ref and then push that ref to a remote or to bundle it for easy transport, and then fetch it on the receiving side. It also permits saving the index and even untracked files and syncing them across machines, unlike temporary commits.

We intentionally attempt to exactly round-trip commits between stashes, although we don't do so for the exported data due to the base commit not having identical timestamps. Preserving the commits exactly lets us more efficiently test our code and it also permits users to more easily determine if they have the same data.

The tooling here is intentionally plumbing. It's designed to be simple and functional and get the basic job done. If we want additional features, we can add them in the future, but this should be a simple, basic feature set that can support additional uses.

[0] For example, the present author has 124 stash entries in his repository for this project.

brian m. carlson (6):
  builtin/stash: factor out generic function to look up stash info
  builtin/stash: fill in all commit data
  object-name: make get_oid quietly return an error
  builtin/stash: provide a way to export stashes to a ref
  builtin/stash: provide a way to import stashes from a ref
  doc: add stash export and import to docs

 Documentation/git-stash.txt |  27 +++
 builtin/stash.c             | 359 +++++++++++++++++++++++++++++++++---
 cache.h                     |  21 ++-
 object-name.c               |   6 +-
 t/t3903-stash.sh            |  52 ++++++
 5 files changed, 431 insertions(+), 34 deletions(-)