`git status` porcelain output should include remote details

[shiftkey]

This isn't a defect but is instead an opportunity to improve Git for scripting scenarios.

In Git 2.16 git for-each-ref learned about how to list upstream and push information - for when a local branch is tracking a remote branch:

git/Documentation/RelNotes/2.16.0.txt

Lines 50 to 53 in 52015aa

	* The "--format=..." option "git for-each-ref" takes learned to show
	the name of the 'remote' repository and the ref at the remote side
	that is affected for 'upstream' and 'push' via "%(push:remotename)"
	and friends.

An example of this:

$ git for-each-ref --format="'%(refname)' -> '%(upstream:remotename) %(upstream:lstrip=3)'" refs/heads/
'refs/heads/add-permissions-hash-for-repository' -> ' '
'refs/heads/add-support-for-previewing-svgs' -> ' '
'refs/heads/another-minification-bug' -> 'origin another-minification-bug'
'refs/heads/b-b-b-banner' -> 'origin b-b-b-banner'
'refs/heads/beta-link-to-release-notes-works' -> ' '
'refs/heads/buffer-rule' -> ' '
'refs/heads/bump-for-new-git-lfs' -> 'origin bump-for-new-git-lfs'
'refs/heads/catch-errors-betterer' -> 'origin catch-errors-betterer'
'refs/heads/config-shows-untracked-files' -> ' '
'refs/heads/contributor-stats' -> 'origin contributor-stats'
'refs/heads/database-field-naming' -> 'origin database-field-naming'
'refs/heads/defer-remote-detection-to-dialog' -> 'origin defer-remote-detection-to-dialog'
'refs/heads/detect-bare-repository' -> ' '
'refs/heads/docs-about-labels' -> ' '
'refs/heads/document-discard-changes' -> 'origin document-discard-changes'
'refs/heads/drop-back-to-classic-api' -> 'origin drop-back-to-classic-api'
'refs/heads/dynamically-stylable-svg' -> 'OiYouYeahYou dynamically-stylable-svg'
'refs/heads/encodings-as-a-first-class-thing' -> ' '
'refs/heads/experimental-ssh-setup' -> 'origin experimental-ssh-setup'
'refs/heads/extract-settings-into-own-store' -> ' '
...

This means we can handle scenarios where users have a / in their remote name - it's not something that users often do, but it's something that we should be able to handle when working with Git repositories.

One place related to this is git status - it has a way to emit the ahead/behind information for-free alongside seeing what's changed in your directory:

$ git status --porcelain=2 --branch
# branch.oid 2b111155914cb44824b39ee197deed23bb825a1a
# branch.head master
# branch.upstream origin/master
# branch.ab +0 -0

It'd be nice to be able to emit these new values from (I talked about this with @dscho a while ago and he indicated this should be a new version of the porcelain format for backwards compatibility reasons):

$ git status --porcelain=3 --branch
# branch.oid 2b111155914cb44824b39ee197deed23bb825a1a
# branch.head master
# upstream.remote origin
# upstream.branch master
# branch.ab +0 -0

[nocnokneo]

label:enhancement?

[dscho]

@shiftkey do you have any cycles to spare to work on this? I could assist, but sadly I won't find the time to work on this any time soon...

[shiftkey]

@dscho no problem. I've been mulling this over again recently to take it further than just adding upstream.remote, and I need to do a brain dump of that and the motivations behind it. Maybe next month I'll have some time to spike getting this working.

[dscho]

@shiftkey we could also just add it to the ideas for Outreachy/Google Summer of Code...

[dscho]

https://git.github.io/SoC-2019-Microprojects/ (or better https://github.com/git/git.github.io/blob/master/SoC-2019-Ideas.md#summer-of-code-main-project-ideas) or https://git.wiki.kernel.org/index.php/SmallProjectsIdeas

[shiftkey]

@dscho my elevator pitch:

git status provides some human-friendly context that isn't easily accessible to tools that prefer the porcelain output. One example is when the repository is in the middle of a rebase and the user needs to resolve conflicts:

$ git status
rebase in progress; onto 191dbf5
You are currently rebasing branch '2-simple-rebase-conflict-target-branch' on '191dbf5'.
 (fix conflicts and then run "git rebase --continue")
 (use "git rebase --skip" to skip this patch)
 (use "git rebase --abort" to check out the original branch)

Unmerged paths:
 (use "git reset HEAD <file>..." to unstage)
 (use "git add <file>..." to mark resolution)

  both added:      2-simple-rebase-conflict/LICENSE.md

no changes added to commit (use "git add" and/or "git commit -a")

versus the output with --porcelain and --branch:

$ git status --porcelain=2 --branch
# branch.oid 191dbf58f8b005cb36517b4c89198e58176e7b9b
# branch.head (detached)
u AA N... 000000 100644 100644 100644 0000000000000000000000000000000000000000 92e1d113360ed6e6c50b7187fd4be008ee855f48 a612ad9813b006ce81d1ee438dd784da99a54007 2-simple-rebase-conflict/LICENSE.md

In particular the details in the header of the rebase details

rebase in progress; onto 191dbf5
You are currently rebasing branch '2-simple-rebase-conflict-target-branch' on '191dbf5'.

One can cobble together these pieces if you know where to look inside .git but this feels like a more natural fit for the porcelain of Git

I haven't thought much about what this would look like, but I'm happy to ponder on this more and submit it wherever you think fits best.

[dscho]

@shiftkey why not just add that elevator pitch? It might be a good idea for the person who picks up that project to decide upon the details of the implementation.

[dscho]

In the meantime, somebody gave me the idea to open up https://github.com/gitgitgadget/git/issues for ideas like this (in particular non-Windows-specific ones). It does seem as if volunteers show up occasionally, plucking off some tickets here and there.

@shiftkey how about closing this here ticket and opening a fresh one over there, leading with your elevator pitch?

[dscho]

Closing this as stale.