sequencer: introduce new commands to reset the revision

In the upcoming commits, we will teach the sequencer to rebase merges.
This will be done in a very different way from the unfortunate design of
`git rebase --preserve-merges` (which does not allow for reordering
commits, or changing the branch topology).

The main idea is to introduce new todo list commands, to support
labeling the current revision with a given name, resetting the current
revision to a previous state, and  merging labeled revisions.

This idea was developed in Git for Windows' Git garden shears (that are
used to maintain Git for Windows' "thicket of branches" on top of
upstream Git), and this patch is part of the effort to make it available
to a wider audience, as well as to make the entire process more robust
(by implementing it in a safe and portable language rather than a Unix
shell script).

This commit implements the commands to label, and to reset to, given
revisions. The syntax is:

	label <name>
	reset <name>

Internally, the `label <name>` command creates the ref
`refs/rewritten/<name>`. This makes it possible to work with the labeled
revisions interactively, or in a scripted fashion (e.g. via the todo
list command `exec`).

These temporary refs are removed upon sequencer_remove_state(), so that
even a `git rebase --abort` cleans them up.

We disallow '#' as label because that character will be used as separator
in the upcoming `merge` command.

Later in this patch series, we will mark the `refs/rewritten/` refs as
worktree-local, to allow for interactive rebases to be run in parallel in
worktrees linked to the same repository.

As typos happen, a failed `label` or `reset` command will be rescheduled
immediately. As the previous code to reschedule a command is embedded
deeply in the pick/fixup/squash code path, we simply duplicate the few
lines. This will allow us to extend the new code path easily for the
upcoming `merge` command.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2 files changed
tree: b94bbe6866673e8b8dcdce91e5a088de5e8db68f
  1. .github/
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  4. ci/
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  6. contrib/
  7. Documentation/
  8. ewah/
  9. git-gui/
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  79. config.c
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  135. generate-cmdlist.sh
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  147. git-instaweb.sh
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  155. git-quiltimport.sh
  156. git-rebase--am.sh
  157. git-rebase--interactive.sh
  158. git-rebase--merge.sh
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  165. git-stash.sh
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  284. quote.c
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  288. read-cache.c
  289. README.md
  290. ref-filter.c
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  292. reflog-walk.c
  293. reflog-walk.h
  294. refs.c
  295. refs.h
  296. remote-curl.c
  297. remote-testsvn.c
  298. remote.c
  299. remote.h
  300. replace-object.c
  301. repository.c
  302. repository.h
  303. rerere.c
  304. rerere.h
  305. resolve-undo.c
  306. resolve-undo.h
  307. revision.c
  308. revision.h
  309. run-command.c
  310. run-command.h
  311. send-pack.c
  312. send-pack.h
  313. sequencer.c
  314. sequencer.h
  315. server-info.c
  316. setup.c
  317. sh-i18n--envsubst.c
  318. sha1-array.c
  319. sha1-array.h
  320. sha1-file.c
  321. sha1-lookup.c
  322. sha1-lookup.h
  323. sha1-name.c
  324. sha1dc_git.c
  325. sha1dc_git.h
  326. shallow.c
  327. shell.c
  328. shortlog.h
  329. show-index.c
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  332. sigchain.c
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  334. split-index.c
  335. split-index.h
  336. strbuf.c
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  338. streaming.c
  339. streaming.h
  340. string-list.c
  341. string-list.h
  342. sub-process.c
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  344. submodule-config.c
  345. submodule-config.h
  346. submodule.c
  347. submodule.h
  348. symlinks.c
  349. tag.c
  350. tag.h
  351. tar.h
  352. tempfile.c
  353. tempfile.h
  354. thread-utils.c
  355. thread-utils.h
  356. tmp-objdir.c
  357. tmp-objdir.h
  358. trace.c
  359. trace.h
  360. trailer.c
  361. trailer.h
  362. transport-helper.c
  363. transport-internal.h
  364. transport.c
  365. transport.h
  366. tree-diff.c
  367. tree-walk.c
  368. tree-walk.h
  369. tree.c
  370. tree.h
  371. unicode-width.h
  372. unimplemented.sh
  373. unix-socket.c
  374. unix-socket.h
  375. unpack-trees.c
  376. unpack-trees.h
  377. upload-pack.c
  378. url.c
  379. url.h
  380. urlmatch.c
  381. urlmatch.h
  382. usage.c
  383. userdiff.c
  384. userdiff.h
  385. utf8.c
  386. utf8.h
  387. varint.c
  388. varint.h
  389. version.c
  390. version.h
  391. versioncmp.c
  392. walker.c
  393. walker.h
  394. wildmatch.c
  395. wildmatch.h
  396. worktree.c
  397. worktree.h
  398. wrap-for-bin.sh
  399. wrapper.c
  400. write-or-die.c
  401. ws.c
  402. wt-status.c
  403. wt-status.h
  404. xdiff-interface.c
  405. xdiff-interface.h
  406. zlib.c
README.md

Git - fast, scalable, distributed revision control system

Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.

Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.

Please read the file INSTALL for installation instructions.

Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.

See Documentation/gittutorial.txt to get started, then see Documentation/giteveryday.txt for a useful minimum set of commands, and Documentation/git-.txt for documentation of each command. If git has been correctly installed, then the tutorial can also be read with man gittutorial or git help tutorial, and the documentation of each command with man git-<commandname> or git help <commandname>.

CVS users may also want to read Documentation/gitcvs-migration.txt (man gitcvs-migration or git help cvs-migration if git is installed).

The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission). To subscribe to the list, send an email with just “subscribe git” in the body to majordomo@vger.kernel.org. The mailing list archives are available at https://public-inbox.org/git/, http://marc.info/?l=git and other archival sites.

The maintainer frequently sends the “What's cooking” reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.

The name “git” was given by Linus Torvalds when he wrote the very first version. He described the tool as “the stupid content tracker” and the name as (depending on your mood):

  • random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of “get” may or may not be relevant.
  • stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
  • “global information tracker”: you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
  • “goddamn idiotic truckload of sh*t”: when it breaks