rebase (interactive-backend): make --keep-empty the default

Different rebase backends have different treatment for commits which
start empty (i.e. have no changes relative to their parent), and the
--keep-empty option was added at some point to allow adjusting behavior.
The handling of commits which start empty is actually quite similar to
commit b00bf1c9a8dd (git-rebase: make --allow-empty-message the default,
2018-06-27), which pointed out that the behavior for various backends is
often more happenstance than design.  The specific change made in that
commit is actually quite relevant as well and much of the logic there
directly applies here.

It makes a lot of sense in 'git commit' to error out on the creation of
empty commits, unless an override flag is provided.  However, once
someone determines that there is a rare case that merits using the
manual override to create such a commit, it is somewhere between
annoying and harmful to have to take extra steps to keep such
intentional commits around.  Granted, empty commits are quite rare,
which is why handling of them doesn't get considered much and folks tend
to defer to existing (accidental) behavior and assume there was a reason
for it, leading them to just add flags (--keep-empty in this case) that
allow them to override the bad defaults.  Fix the interactive backend so
that --keep-empty is the default, much like we did with
--allow-empty-message.  The am backend should also be fixed to have
--keep-empty semantics for commits that start empty, but that is not
included in this patch other than a testcase documenting the failure.

Note that there was one test in t3421 which appears to have been written
expecting --keep-empty to not be the default as correct behavior.  This
test was introduced in commit 00b8be5a4d38 ("add tests for rebasing of
empty commits", 2013-06-06), which was part of a series focusing on
rebase topology and which had an interesting original cover letter at
https://lore.kernel.org/git/1347949878-12578-1-git-send-email-martinvonz@gmail.com/
which noted
    Your input especially appreciated on whether you agree with the
    intent of the test cases.
and then went into a long example about how one of the many tests added
had several questions about whether it was correct.  As such, I believe
most the tests in that series were about testing rebase topology with as
many different flags as possible and were not trying to state in general
how those flags should behave otherwise.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
9 files changed
tree: d3bc7c9e24f36fce1f3a0e1b36f38708fe2993e3
  1. .github/
  2. block-sha1/
  3. builtin/
  4. ci/
  5. compat/
  6. contrib/
  7. Documentation/
  8. ewah/
  9. git-gui/
  10. gitk-git/
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  81. color.c
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  87. commit-graph.c
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  126. detect-compiler
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  128. diff-lib.c
  129. diff-no-index.c
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  132. diffcore-break.c
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  135. diffcore-pickaxe.c
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  142. editor.c
  143. entry.c
  144. environment.c
  145. exec-cmd.c
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  147. fast-import.c
  148. fetch-negotiator.c
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  150. fetch-pack.c
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  153. fsck.c
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  155. fsmonitor.c
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  157. fuzz-commit-graph.c
  158. fuzz-pack-headers.c
  159. fuzz-pack-idx.c
  160. generate-cmdlist.sh
  161. gettext.c
  162. gettext.h
  163. git-add--interactive.perl
  164. git-archimport.perl
  165. git-bisect.sh
  166. git-compat-util.h
  167. git-cvsexportcommit.perl
  168. git-cvsimport.perl
  169. git-cvsserver.perl
  170. git-difftool--helper.sh
  171. git-filter-branch.sh
  172. git-instaweb.sh
  173. git-legacy-stash.sh
  174. git-merge-octopus.sh
  175. git-merge-one-file.sh
  176. git-merge-resolve.sh
  177. git-mergetool--lib.sh
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  179. git-p4.py
  180. git-parse-remote.sh
  181. git-quiltimport.sh
  182. git-rebase--preserve-merges.sh
  183. git-request-pull.sh
  184. git-send-email.perl
  185. git-sh-i18n.sh
  186. git-sh-setup.sh
  187. git-submodule.sh
  188. git-svn.perl
  189. GIT-VERSION-GEN
  190. git-web--browse.sh
  191. git.c
  192. git.rc
  193. gpg-interface.c
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  211. ident.c
  212. imap-send.c
  213. INSTALL
  214. interdiff.c
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  216. iterator.h
  217. json-writer.c
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  240. lockfile.c
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  242. log-tree.c
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  244. ls-refs.c
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  246. mailinfo.c
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  250. Makefile
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  252. mem-pool.c
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  254. merge-blobs.c
  255. merge-blobs.h
  256. merge-recursive.c
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  261. midx.c
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  263. name-hash.c
  264. notes-cache.c
  265. notes-cache.h
  266. notes-merge.c
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  268. notes-utils.c
  269. notes-utils.h
  270. notes.c
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  272. object-store.h
  273. object.c
  274. object.h
  275. oidmap.c
  276. oidmap.h
  277. oidset.c
  278. oidset.h
  279. pack-bitmap-write.c
  280. pack-bitmap.c
  281. pack-bitmap.h
  282. pack-check.c
  283. pack-objects.c
  284. pack-objects.h
  285. pack-revindex.c
  286. pack-revindex.h
  287. pack-write.c
  288. pack.h
  289. packfile.c
  290. packfile.h
  291. pager.c
  292. parse-options-cb.c
  293. parse-options.c
  294. parse-options.h
  295. patch-delta.c
  296. patch-ids.c
  297. patch-ids.h
  298. path.c
  299. path.h
  300. pathspec.c
  301. pathspec.h
  302. pkt-line.c
  303. pkt-line.h
  304. preload-index.c
  305. pretty.c
  306. pretty.h
  307. prio-queue.c
  308. prio-queue.h
  309. progress.c
  310. progress.h
  311. promisor-remote.c
  312. promisor-remote.h
  313. prompt.c
  314. prompt.h
  315. protocol.c
  316. protocol.h
  317. quote.c
  318. quote.h
  319. range-diff.c
  320. range-diff.h
  321. reachable.c
  322. reachable.h
  323. read-cache.c
  324. README.md
  325. rebase-interactive.c
  326. rebase-interactive.h
  327. ref-filter.c
  328. ref-filter.h
  329. reflog-walk.c
  330. reflog-walk.h
  331. refs.c
  332. refs.h
  333. refspec.c
  334. refspec.h
  335. remote-curl.c
  336. remote-testsvn.c
  337. remote.c
  338. remote.h
  339. replace-object.c
  340. replace-object.h
  341. repo-settings.c
  342. repository.c
  343. repository.h
  344. rerere.c
  345. rerere.h
  346. resolve-undo.c
  347. resolve-undo.h
  348. revision.c
  349. revision.h
  350. run-command.c
  351. run-command.h
  352. send-pack.c
  353. send-pack.h
  354. sequencer.c
  355. sequencer.h
  356. serve.c
  357. serve.h
  358. server-info.c
  359. setup.c
  360. sh-i18n--envsubst.c
  361. sha1-array.c
  362. sha1-array.h
  363. sha1-file.c
  364. sha1-lookup.c
  365. sha1-lookup.h
  366. sha1-name.c
  367. sha1dc_git.c
  368. sha1dc_git.h
  369. shallow.c
  370. shell.c
  371. shortlog.h
  372. sideband.c
  373. sideband.h
  374. sigchain.c
  375. sigchain.h
  376. split-index.c
  377. split-index.h
  378. stable-qsort.c
  379. strbuf.c
  380. strbuf.h
  381. streaming.c
  382. streaming.h
  383. string-list.c
  384. string-list.h
  385. sub-process.c
  386. sub-process.h
  387. submodule-config.c
  388. submodule-config.h
  389. submodule.c
  390. submodule.h
  391. symlinks.c
  392. tag.c
  393. tag.h
  394. tar.h
  395. tempfile.c
  396. tempfile.h
  397. thread-utils.c
  398. thread-utils.h
  399. tmp-objdir.c
  400. tmp-objdir.h
  401. trace.c
  402. trace.h
  403. trace2.c
  404. trace2.h
  405. trailer.c
  406. trailer.h
  407. transport-helper.c
  408. transport-internal.h
  409. transport.c
  410. transport.h
  411. tree-diff.c
  412. tree-walk.c
  413. tree-walk.h
  414. tree.c
  415. tree.h
  416. unicode-width.h
  417. unimplemented.sh
  418. unix-socket.c
  419. unix-socket.h
  420. unpack-trees.c
  421. unpack-trees.h
  422. upload-pack.c
  423. upload-pack.h
  424. url.c
  425. url.h
  426. urlmatch.c
  427. urlmatch.h
  428. usage.c
  429. userdiff.c
  430. userdiff.h
  431. utf8.c
  432. utf8.h
  433. varint.c
  434. varint.h
  435. version.c
  436. version.h
  437. versioncmp.c
  438. walker.c
  439. walker.h
  440. wildmatch.c
  441. wildmatch.h
  442. worktree.c
  443. worktree.h
  444. wrap-for-bin.sh
  445. wrapper.c
  446. write-or-die.c
  447. ws.c
  448. wt-status.c
  449. wt-status.h
  450. xdiff-interface.c
  451. xdiff-interface.h
  452. zlib.c
README.md

Build Status

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-<commandname>.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://lore.kernel.org/git/, http://marc.info/?l=git and other archival sites.

Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.

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