Merge branch 'sn/tutorial-status-output-example'
[git/git.git] / Documentation / SubmittingPatches
1 Here are some guidelines for people who want to contribute their code
2 to this software.
4 (0) Decide what to base your work on.
6 In general, always base your work on the oldest branch that your
7 change is relevant to.
9 - A bugfix should be based on 'maint' in general. If the bug is not
10 present in 'maint', base it on 'master'. For a bug that's not yet
11 in 'master', find the topic that introduces the regression, and
12 base your work on the tip of the topic.
14 - A new feature should be based on 'master' in general. If the new
15 feature depends on a topic that is in 'pu', but not in 'master',
16 base your work on the tip of that topic.
18 - Corrections and enhancements to a topic not yet in 'master' should
19 be based on the tip of that topic. If the topic has not been merged
20 to 'next', it's alright to add a note to squash minor corrections
21 into the series.
23 - In the exceptional case that a new feature depends on several topics
24 not in 'master', start working on 'next' or 'pu' privately and send
25 out patches for discussion. Before the final merge, you may have to
26 wait until some of the dependent topics graduate to 'master', and
27 rebase your work.
29 - Some parts of the system have dedicated maintainers with their own
30 repositories (see the section "Subsystems" below). Changes to
31 these parts should be based on their trees.
33 To find the tip of a topic branch, run "git log --first-parent
34 master..pu" and look for the merge commit. The second parent of this
35 commit is the tip of the topic branch.
37 (1) Make separate commits for logically separate changes.
39 Unless your patch is really trivial, you should not be sending
40 out a patch that was generated between your working tree and
41 your commit head. Instead, always make a commit with complete
42 commit message and generate a series of patches from your
43 repository. It is a good discipline.
45 Give an explanation for the change(s) that is detailed enough so
46 that people can judge if it is good thing to do, without reading
47 the actual patch text to determine how well the code does what
48 the explanation promises to do.
50 If your description starts to get too long, that's a sign that you
51 probably need to split up your commit to finer grained pieces.
52 That being said, patches which plainly describe the things that
53 help reviewers check the patch, and future maintainers understand
54 the code, are the most beautiful patches. Descriptions that summarise
55 the point in the subject well, and describe the motivation for the
56 change, the approach taken by the change, and if relevant how this
57 differs substantially from the prior version, are all good things
58 to have.
60 Make sure that you have tests for the bug you are fixing.
62 When adding a new feature, make sure that you have new tests to show
63 the feature triggers the new behaviour when it should, and to show the
64 feature does not trigger when it shouldn't. Also make sure that the
65 test suite passes after your commit. Do not forget to update the
66 documentation to describe the updated behaviour.
68 Speaking of the documentation, it is currently a liberal mixture of US
69 and UK English norms for spelling and grammar, which is somewhat
70 unfortunate. A huge patch that touches the files all over the place
71 only to correct the inconsistency is not welcome, though. Potential
72 clashes with other changes that can result from such a patch are not
73 worth it. We prefer to gradually reconcile the inconsistencies in
74 favor of US English, with small and easily digestible patches, as a
75 side effect of doing some other real work in the vicinity (e.g.
76 rewriting a paragraph for clarity, while turning en_UK spelling to
77 en_US). Obvious typographical fixes are much more welcomed ("teh ->
78 "the"), preferably submitted as independent patches separate from
79 other documentation changes.
81 Oh, another thing. We are picky about whitespaces. Make sure your
82 changes do not trigger errors with the sample pre-commit hook shipped
83 in templates/hooks--pre-commit. To help ensure this does not happen,
84 run git diff --check on your changes before you commit.
87 (2) Describe your changes well.
89 The first line of the commit message should be a short description (50
90 characters is the soft limit, see DISCUSSION in git-commit(1)), and
91 should skip the full stop. It is also conventional in most cases to
92 prefix the first line with "area: " where the area is a filename or
93 identifier for the general area of the code being modified, e.g.
95 . archive: ustar header checksum is computed unsigned
96 . git-cherry-pick.txt: clarify the use of revision range notation
98 If in doubt which identifier to use, run "git log --no-merges" on the
99 files you are modifying to see the current conventions.
101 The body should provide a meaningful commit message, which:
103 . explains the problem the change tries to solve, iow, what is wrong
104 with the current code without the change.
106 . justifies the way the change solves the problem, iow, why the
107 result with the change is better.
109 . alternate solutions considered but discarded, if any.
111 Describe your changes in imperative mood, e.g. "make xyzzy do frotz"
112 instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy
113 to do frotz", as if you are giving orders to the codebase to change
114 its behaviour. Try to make sure your explanation can be understood
115 without external resources. Instead of giving a URL to a mailing list
116 archive, summarize the relevant points of the discussion.
119 (3) Generate your patch using Git tools out of your commits.
121 Git based diff tools generate unidiff which is the preferred format.
123 You do not have to be afraid to use -M option to "git diff" or
124 "git format-patch", if your patch involves file renames. The
125 receiving end can handle them just fine.
127 Please make sure your patch does not add commented out debugging code,
128 or include any extra files which do not relate to what your patch
129 is trying to achieve. Make sure to review
130 your patch after generating it, to ensure accuracy. Before
131 sending out, please make sure it cleanly applies to the "master"
132 branch head. If you are preparing a work based on "next" branch,
133 that is fine, but please mark it as such.
136 (4) Sending your patches.
138 People on the Git mailing list need to be able to read and
139 comment on the changes you are submitting. It is important for
140 a developer to be able to "quote" your changes, using standard
141 e-mail tools, so that they may comment on specific portions of
142 your code. For this reason, each patch should be submitted
143 "inline" in a separate message.
145 Multiple related patches should be grouped into their own e-mail
146 thread to help readers find all parts of the series. To that end,
147 send them as replies to either an additional "cover letter" message
148 (see below), the first patch, or the respective preceding patch.
150 If your log message (including your name on the
151 Signed-off-by line) is not writable in ASCII, make sure that
152 you send off a message in the correct encoding.
154 WARNING: Be wary of your MUAs word-wrap
155 corrupting your patch. Do not cut-n-paste your patch; you can
156 lose tabs that way if you are not careful.
158 It is a common convention to prefix your subject line with
159 [PATCH]. This lets people easily distinguish patches from other
160 e-mail discussions. Use of additional markers after PATCH and
161 the closing bracket to mark the nature of the patch is also
162 encouraged. E.g. [PATCH/RFC] is often used when the patch is
163 not ready to be applied but it is for discussion, [PATCH v2],
164 [PATCH v3] etc. are often seen when you are sending an update to
165 what you have previously sent.
167 "git format-patch" command follows the best current practice to
168 format the body of an e-mail message. At the beginning of the
169 patch should come your commit message, ending with the
170 Signed-off-by: lines, and a line that consists of three dashes,
171 followed by the diffstat information and the patch itself. If
172 you are forwarding a patch from somebody else, optionally, at
173 the beginning of the e-mail message just before the commit
174 message starts, you can put a "From: " line to name that person.
176 You often want to add additional explanation about the patch,
177 other than the commit message itself. Place such "cover letter"
178 material between the three dash lines and the diffstat. Git-notes
179 can also be inserted using the `--notes` option.
181 Do not attach the patch as a MIME attachment, compressed or not.
182 Do not let your e-mail client send quoted-printable. Do not let
183 your e-mail client send format=flowed which would destroy
184 whitespaces in your patches. Many
185 popular e-mail applications will not always transmit a MIME
186 attachment as plain text, making it impossible to comment on
187 your code. A MIME attachment also takes a bit more time to
188 process. This does not decrease the likelihood of your
189 MIME-attached change being accepted, but it makes it more likely
190 that it will be postponed.
192 Exception: If your mailer is mangling patches then someone may ask
193 you to re-send them using MIME, that is OK.
195 Do not PGP sign your patch, at least for now. Most likely, your
196 maintainer or other people on the list would not have your PGP
197 key and would not bother obtaining it anyway. Your patch is not
198 judged by who you are; a good patch from an unknown origin has a
199 far better chance of being accepted than a patch from a known,
200 respected origin that is done poorly or does incorrect things.
202 If you really really really really want to do a PGP signed
203 patch, format it as "multipart/signed", not a text/plain message
204 that starts with '-----BEGIN PGP SIGNED MESSAGE-----'. That is
205 not a text/plain, it's something else.
207 Send your patch with "To:" set to the mailing list, with "cc:" listing
208 people who are involved in the area you are touching (the output from
209 "git blame $path" and "git shortlog --no-merges $path" would help to
210 identify them), to solicit comments and reviews.
212 After the list reached a consensus that it is a good idea to apply the
213 patch, re-send it with "To:" set to the maintainer [*1*] and "cc:" the
214 list [*2*] for inclusion.
216 Do not forget to add trailers such as "Acked-by:", "Reviewed-by:" and
217 "Tested-by:" lines as necessary to credit people who helped your
218 patch.
220 [Addresses]
221 *1* The current maintainer:
222 *2* The mailing list:
225 (5) Sign your work
227 To improve tracking of who did what, we've borrowed the
228 "sign-off" procedure from the Linux kernel project on patches
229 that are being emailed around. Although core Git is a lot
230 smaller project it is a good discipline to follow it.
232 The sign-off is a simple line at the end of the explanation for
233 the patch, which certifies that you wrote it or otherwise have
234 the right to pass it on as a open-source patch. The rules are
235 pretty simple: if you can certify the below:
237 Developer's Certificate of Origin 1.1
239 By making a contribution to this project, I certify that:
241 (a) The contribution was created in whole or in part by me and I
242 have the right to submit it under the open source license
243 indicated in the file; or
245 (b) The contribution is based upon previous work that, to the best
246 of my knowledge, is covered under an appropriate open source
247 license and I have the right under that license to submit that
248 work with modifications, whether created in whole or in part
249 by me, under the same open source license (unless I am
250 permitted to submit under a different license), as indicated
251 in the file; or
253 (c) The contribution was provided directly to me by some other
254 person who certified (a), (b) or (c) and I have not modified
255 it.
257 (d) I understand and agree that this project and the contribution
258 are public and that a record of the contribution (including all
259 personal information I submit with it, including my sign-off) is
260 maintained indefinitely and may be redistributed consistent with
261 this project or the open source license(s) involved.
263 then you just add a line saying
265 Signed-off-by: Random J Developer <>
267 This line can be automatically added by Git if you run the git-commit
268 command with the -s option.
270 Notice that you can place your own Signed-off-by: line when
271 forwarding somebody else's patch with the above rules for
272 D-C-O. Indeed you are encouraged to do so. Do not forget to
273 place an in-body "From: " line at the beginning to properly attribute
274 the change to its true author (see (2) above).
276 Also notice that a real name is used in the Signed-off-by: line. Please
277 don't hide your real name.
279 If you like, you can put extra tags at the end:
281 1. "Reported-by:" is used to credit someone who found the bug that
282 the patch attempts to fix.
283 2. "Acked-by:" says that the person who is more familiar with the area
284 the patch attempts to modify liked the patch.
285 3. "Reviewed-by:", unlike the other tags, can only be offered by the
286 reviewer and means that she is completely satisfied that the patch
287 is ready for application. It is usually offered only after a
288 detailed review.
289 4. "Tested-by:" is used to indicate that the person applied the patch
290 and found it to have the desired effect.
292 You can also create your own tag or use one that's in common usage
293 such as "Thanks-to:", "Based-on-patch-by:", or "Mentored-by:".
295 ------------------------------------------------
296 Subsystems with dedicated maintainers
298 Some parts of the system have dedicated maintainers with their own
299 repositories.
301 - git-gui/ comes from git-gui project, maintained by Pat Thoyts:
303 git://
305 - gitk-git/ comes from Paul Mackerras's gitk project:
307 git://
309 - po/ comes from the localization coordinator, Jiang Xin:
313 Patches to these parts should be based on their trees.
315 ------------------------------------------------
316 An ideal patch flow
318 Here is an ideal patch flow for this project the current maintainer
319 suggests to the contributors:
321 (0) You come up with an itch. You code it up.
323 (1) Send it to the list and cc people who may need to know about
324 the change.
326 The people who may need to know are the ones whose code you
327 are butchering. These people happen to be the ones who are
328 most likely to be knowledgeable enough to help you, but
329 they have no obligation to help you (i.e. you ask for help,
330 don't demand). "git log -p -- $area_you_are_modifying" would
331 help you find out who they are.
333 (2) You get comments and suggestions for improvements. You may
334 even get them in a "on top of your change" patch form.
336 (3) Polish, refine, and re-send to the list and the people who
337 spend their time to improve your patch. Go back to step (2).
339 (4) The list forms consensus that the last round of your patch is
340 good. Send it to the list and cc the maintainer.
342 (5) A topic branch is created with the patch and is merged to 'next',
343 and cooked further and eventually graduates to 'master'.
345 In any time between the (2)-(3) cycle, the maintainer may pick it up
346 from the list and queue it to 'pu', in order to make it easier for
347 people play with it without having to pick up and apply the patch to
348 their trees themselves.
350 ------------------------------------------------
351 Know the status of your patch after submission
353 * You can use Git itself to find out when your patch is merged in
354 master. 'git pull --rebase' will automatically skip already-applied
355 patches, and will let you know. This works only if you rebase on top
356 of the branch in which your patch has been merged (i.e. it will not
357 tell you if your patch is merged in pu if you rebase on top of
358 master).
360 * Read the Git mailing list, the maintainer regularly posts messages
361 entitled "What's cooking in git.git" and "What's in git.git" giving
362 the status of various proposed changes.
364 ------------------------------------------------
365 MUA specific hints
367 Some of patches I receive or pick up from the list share common
368 patterns of breakage. Please make sure your MUA is set up
369 properly not to corrupt whitespaces.
371 See the DISCUSSION section of git-format-patch(1) for hints on
372 checking your patch by mailing it to yourself and applying with
373 git-am(1).
375 While you are at it, check the resulting commit log message from
376 a trial run of applying the patch. If what is in the resulting
377 commit is not exactly what you would want to see, it is very
378 likely that your maintainer would end up hand editing the log
379 message when he applies your patch. Things like "Hi, this is my
380 first patch.\n", if you really want to put in the patch e-mail,
381 should come after the three-dash line that signals the end of the
382 commit message.
385 Pine
386 ----
388 (Johannes Schindelin)
390 I don't know how many people still use pine, but for those poor
391 souls it may be good to mention that the quell-flowed-text is
392 needed for recent versions.
394 ... the "no-strip-whitespace-before-send" option, too. AFAIK it
395 was introduced in 4.60.
397 (Linus Torvalds)
399 And 4.58 needs at least this.
401 ---
402 diff-tree 8326dd8350be64ac7fc805f6563a1d61ad10d32c (from e886a61f76edf5410573e92e38ce22974f9c40f1)
403 Author: Linus Torvalds <>
404 Date: Mon Aug 15 17:23:51 2005 -0700
406 Fix pine whitespace-corruption bug
408 There's no excuse for unconditionally removing whitespace from
409 the pico buffers on close.
411 diff --git a/pico/pico.c b/pico/pico.c
412 --- a/pico/pico.c
413 +++ b/pico/pico.c
414 @@ -219,7 +219,9 @@ PICO *pm;
415 switch(pico_all_done){ /* prepare for/handle final events */
416 case COMP_EXIT : /* already confirmed */
417 packheader();
418 +#if 0
419 stripwhitespace();
420 +#endif
421 c |= COMP_EXIT;
422 break;
425 (Daniel Barkalow)
427 > A patch to SubmittingPatches, MUA specific help section for
428 > users of Pine 4.63 would be very much appreciated.
430 Ah, it looks like a recent version changed the default behavior to do the
431 right thing, and inverted the sense of the configuration option. (Either
432 that or Gentoo did it.) So you need to set the
433 "no-strip-whitespace-before-send" option, unless the option you have is
434 "strip-whitespace-before-send", in which case you should avoid checking
435 it.
438 Thunderbird, KMail, GMail
439 -------------------------
441 See the MUA-SPECIFIC HINTS section of git-format-patch(1).
443 Gnus
444 ----
446 '|' in the *Summary* buffer can be used to pipe the current
447 message to an external program, and this is a handy way to drive
448 "git am". However, if the message is MIME encoded, what is
449 piped into the program is the representation you see in your
450 *Article* buffer after unwrapping MIME. This is often not what
451 you would want for two reasons. It tends to screw up non ASCII
452 characters (most notably in people's names), and also
453 whitespaces (fatal in patches). Running 'C-u g' to display the
454 message in raw form before using '|' to run the pipe can work
455 this problem around.