Merge branch 'jc/maint-fnmatch-old-style-definition' into maint
[git/git.git] / Documentation / SubmittingPatches
1 Checklist (and a short version for the impatient):
2
3 Commits:
4
5 - make commits of logical units
6 - check for unnecessary whitespace with "git diff --check"
7 before committing
8 - do not check in commented out code or unneeded files
9 - the first line of the commit message should be a short
10 description (50 characters is the soft limit, see DISCUSSION
11 in git-commit(1)), and should skip the full stop
12 - it is also conventional in most cases to prefix the
13 first line with "area: " where the area is a filename
14 or identifier for the general area of the code being
15 modified, e.g.
16 . archive: ustar header checksum is computed unsigned
17 . git-cherry-pick.txt: clarify the use of revision range notation
18 (if in doubt which identifier to use, run "git log --no-merges"
19 on the files you are modifying to see the current conventions)
20 - the body should provide a meaningful commit message, which:
21 . explains the problem the change tries to solve, iow, what
22 is wrong with the current code without the change.
23 . justifies the way the change solves the problem, iow, why
24 the result with the change is better.
25 . alternate solutions considered but discarded, if any.
26 - describe changes in imperative mood, e.g. "make xyzzy do frotz"
27 instead of "[This patch] makes xyzzy do frotz" or "[I] changed
28 xyzzy to do frotz", as if you are giving orders to the codebase
29 to change its behaviour.
30 - try to make sure your explanation can be understood without
31 external resources. Instead of giving a URL to a mailing list
32 archive, summarize the relevant points of the discussion.
33 - add a "Signed-off-by: Your Name <you@example.com>" line to the
34 commit message (or just use the option "-s" when committing)
35 to confirm that you agree to the Developer's Certificate of Origin
36 - make sure that you have tests for the bug you are fixing
37 - make sure that the test suite passes after your commit
38
39 Patch:
40
41 - use "git format-patch -M" to create the patch
42 - do not PGP sign your patch
43 - do not attach your patch, but read in the mail
44 body, unless you cannot teach your mailer to
45 leave the formatting of the patch alone.
46 - be careful doing cut & paste into your mailer, not to
47 corrupt whitespaces.
48 - provide additional information (which is unsuitable for
49 the commit message) between the "---" and the diffstat
50 - if you change, add, or remove a command line option or
51 make some other user interface change, the associated
52 documentation should be updated as well.
53 - if your name is not writable in ASCII, make sure that
54 you send off a message in the correct encoding.
55 - send the patch to the list (git@vger.kernel.org) and the
56 maintainer (gitster@pobox.com) if (and only if) the patch
57 is ready for inclusion. If you use git-send-email(1),
58 please test it first by sending email to yourself.
59 - see below for instructions specific to your mailer
60
61 Long version:
62
63 I started reading over the SubmittingPatches document for Linux
64 kernel, primarily because I wanted to have a document similar to
65 it for the core GIT to make sure people understand what they are
66 doing when they write "Signed-off-by" line.
67
68 But the patch submission requirements are a lot more relaxed
69 here on the technical/contents front, because the core GIT is
70 thousand times smaller ;-). So here is only the relevant bits.
71
72 (0) Decide what to base your work on.
73
74 In general, always base your work on the oldest branch that your
75 change is relevant to.
76
77 - A bugfix should be based on 'maint' in general. If the bug is not
78 present in 'maint', base it on 'master'. For a bug that's not yet
79 in 'master', find the topic that introduces the regression, and
80 base your work on the tip of the topic.
81
82 - A new feature should be based on 'master' in general. If the new
83 feature depends on a topic that is in 'pu', but not in 'master',
84 base your work on the tip of that topic.
85
86 - Corrections and enhancements to a topic not yet in 'master' should
87 be based on the tip of that topic. If the topic has not been merged
88 to 'next', it's alright to add a note to squash minor corrections
89 into the series.
90
91 - In the exceptional case that a new feature depends on several topics
92 not in 'master', start working on 'next' or 'pu' privately and send
93 out patches for discussion. Before the final merge, you may have to
94 wait until some of the dependent topics graduate to 'master', and
95 rebase your work.
96
97 To find the tip of a topic branch, run "git log --first-parent
98 master..pu" and look for the merge commit. The second parent of this
99 commit is the tip of the topic branch.
100
101 (1) Make separate commits for logically separate changes.
102
103 Unless your patch is really trivial, you should not be sending
104 out a patch that was generated between your working tree and
105 your commit head. Instead, always make a commit with complete
106 commit message and generate a series of patches from your
107 repository. It is a good discipline.
108
109 Give an explanation for the change(s) that is detailed enough so
110 that people can judge if it is good thing to do, without reading
111 the actual patch text to determine how well the code does what
112 the explanation promises to do.
113
114 If your description starts to get too long, that's a sign that you
115 probably need to split up your commit to finer grained pieces.
116 That being said, patches which plainly describe the things that
117 help reviewers check the patch, and future maintainers understand
118 the code, are the most beautiful patches. Descriptions that summarise
119 the point in the subject well, and describe the motivation for the
120 change, the approach taken by the change, and if relevant how this
121 differs substantially from the prior version, are all good things
122 to have.
123
124 Oh, another thing. I am picky about whitespaces. Make sure your
125 changes do not trigger errors with the sample pre-commit hook shipped
126 in templates/hooks--pre-commit. To help ensure this does not happen,
127 run git diff --check on your changes before you commit.
128
129
130 (2) Generate your patch using git tools out of your commits.
131
132 git based diff tools generate unidiff which is the preferred format.
133
134 You do not have to be afraid to use -M option to "git diff" or
135 "git format-patch", if your patch involves file renames. The
136 receiving end can handle them just fine.
137
138 Please make sure your patch does not include any extra files
139 which do not belong in a patch submission. Make sure to review
140 your patch after generating it, to ensure accuracy. Before
141 sending out, please make sure it cleanly applies to the "master"
142 branch head. If you are preparing a work based on "next" branch,
143 that is fine, but please mark it as such.
144
145
146 (3) Sending your patches.
147
148 People on the git mailing list need to be able to read and
149 comment on the changes you are submitting. It is important for
150 a developer to be able to "quote" your changes, using standard
151 e-mail tools, so that they may comment on specific portions of
152 your code. For this reason, all patches should be submitted
153 "inline". WARNING: Be wary of your MUAs word-wrap
154 corrupting your patch. Do not cut-n-paste your patch; you can
155 lose tabs that way if you are not careful.
156
157 It is a common convention to prefix your subject line with
158 [PATCH]. This lets people easily distinguish patches from other
159 e-mail discussions. Use of additional markers after PATCH and
160 the closing bracket to mark the nature of the patch is also
161 encouraged. E.g. [PATCH/RFC] is often used when the patch is
162 not ready to be applied but it is for discussion, [PATCH v2],
163 [PATCH v3] etc. are often seen when you are sending an update to
164 what you have previously sent.
165
166 "git format-patch" command follows the best current practice to
167 format the body of an e-mail message. At the beginning of the
168 patch should come your commit message, ending with the
169 Signed-off-by: lines, and a line that consists of three dashes,
170 followed by the diffstat information and the patch itself. If
171 you are forwarding a patch from somebody else, optionally, at
172 the beginning of the e-mail message just before the commit
173 message starts, you can put a "From: " line to name that person.
174
175 You often want to add additional explanation about the patch,
176 other than the commit message itself. Place such "cover letter"
177 material between the three dash lines and the diffstat. Git-notes
178 can also be inserted using the `--notes` option.
179
180 Do not attach the patch as a MIME attachment, compressed or not.
181 Do not let your e-mail client send quoted-printable. Do not let
182 your e-mail client send format=flowed which would destroy
183 whitespaces in your patches. Many
184 popular e-mail applications will not always transmit a MIME
185 attachment as plain text, making it impossible to comment on
186 your code. A MIME attachment also takes a bit more time to
187 process. This does not decrease the likelihood of your
188 MIME-attached change being accepted, but it makes it more likely
189 that it will be postponed.
190
191 Exception: If your mailer is mangling patches then someone may ask
192 you to re-send them using MIME, that is OK.
193
194 Do not PGP sign your patch, at least for now. Most likely, your
195 maintainer or other people on the list would not have your PGP
196 key and would not bother obtaining it anyway. Your patch is not
197 judged by who you are; a good patch from an unknown origin has a
198 far better chance of being accepted than a patch from a known,
199 respected origin that is done poorly or does incorrect things.
200
201 If you really really really really want to do a PGP signed
202 patch, format it as "multipart/signed", not a text/plain message
203 that starts with '-----BEGIN PGP SIGNED MESSAGE-----'. That is
204 not a text/plain, it's something else.
205
206 Unless your patch is a very trivial and an obviously correct one,
207 first send it 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. After the list
211 reached a consensus that it is a good idea to apply the patch, re-send
212 it with "To:" set to the maintainer and optionally "cc:" the list for
213 inclusion. Do not forget to add trailers such as "Acked-by:",
214 "Reviewed-by:" and "Tested-by:" after your "Signed-off-by:" line as
215 necessary.
216
217
218 (4) Sign your work
219
220 To improve tracking of who did what, we've borrowed the
221 "sign-off" procedure from the Linux kernel project on patches
222 that are being emailed around. Although core GIT is a lot
223 smaller project it is a good discipline to follow it.
224
225 The sign-off is a simple line at the end of the explanation for
226 the patch, which certifies that you wrote it or otherwise have
227 the right to pass it on as a open-source patch. The rules are
228 pretty simple: if you can certify the below:
229
230 Developer's Certificate of Origin 1.1
231
232 By making a contribution to this project, I certify that:
233
234 (a) The contribution was created in whole or in part by me and I
235 have the right to submit it under the open source license
236 indicated in the file; or
237
238 (b) The contribution is based upon previous work that, to the best
239 of my knowledge, is covered under an appropriate open source
240 license and I have the right under that license to submit that
241 work with modifications, whether created in whole or in part
242 by me, under the same open source license (unless I am
243 permitted to submit under a different license), as indicated
244 in the file; or
245
246 (c) The contribution was provided directly to me by some other
247 person who certified (a), (b) or (c) and I have not modified
248 it.
249
250 (d) I understand and agree that this project and the contribution
251 are public and that a record of the contribution (including all
252 personal information I submit with it, including my sign-off) is
253 maintained indefinitely and may be redistributed consistent with
254 this project or the open source license(s) involved.
255
256 then you just add a line saying
257
258 Signed-off-by: Random J Developer <random@developer.example.org>
259
260 This line can be automatically added by git if you run the git-commit
261 command with the -s option.
262
263 Notice that you can place your own Signed-off-by: line when
264 forwarding somebody else's patch with the above rules for
265 D-C-O. Indeed you are encouraged to do so. Do not forget to
266 place an in-body "From: " line at the beginning to properly attribute
267 the change to its true author (see (2) above).
268
269 Also notice that a real name is used in the Signed-off-by: line. Please
270 don't hide your real name.
271
272 If you like, you can put extra tags at the end:
273
274 1. "Reported-by:" is used to credit someone who found the bug that
275 the patch attempts to fix.
276 2. "Acked-by:" says that the person who is more familiar with the area
277 the patch attempts to modify liked the patch.
278 3. "Reviewed-by:", unlike the other tags, can only be offered by the
279 reviewer and means that she is completely satisfied that the patch
280 is ready for application. It is usually offered only after a
281 detailed review.
282 4. "Tested-by:" is used to indicate that the person applied the patch
283 and found it to have the desired effect.
284
285 You can also create your own tag or use one that's in common usage
286 such as "Thanks-to:", "Based-on-patch-by:", or "Mentored-by:".
287
288 ------------------------------------------------
289 An ideal patch flow
290
291 Here is an ideal patch flow for this project the current maintainer
292 suggests to the contributors:
293
294 (0) You come up with an itch. You code it up.
295
296 (1) Send it to the list and cc people who may need to know about
297 the change.
298
299 The people who may need to know are the ones whose code you
300 are butchering. These people happen to be the ones who are
301 most likely to be knowledgeable enough to help you, but
302 they have no obligation to help you (i.e. you ask for help,
303 don't demand). "git log -p -- $area_you_are_modifying" would
304 help you find out who they are.
305
306 (2) You get comments and suggestions for improvements. You may
307 even get them in a "on top of your change" patch form.
308
309 (3) Polish, refine, and re-send to the list and the people who
310 spend their time to improve your patch. Go back to step (2).
311
312 (4) The list forms consensus that the last round of your patch is
313 good. Send it to the list and cc the maintainer.
314
315 (5) A topic branch is created with the patch and is merged to 'next',
316 and cooked further and eventually graduates to 'master'.
317
318 In any time between the (2)-(3) cycle, the maintainer may pick it up
319 from the list and queue it to 'pu', in order to make it easier for
320 people play with it without having to pick up and apply the patch to
321 their trees themselves.
322
323 ------------------------------------------------
324 Know the status of your patch after submission
325
326 * You can use Git itself to find out when your patch is merged in
327 master. 'git pull --rebase' will automatically skip already-applied
328 patches, and will let you know. This works only if you rebase on top
329 of the branch in which your patch has been merged (i.e. it will not
330 tell you if your patch is merged in pu if you rebase on top of
331 master).
332
333 * Read the git mailing list, the maintainer regularly posts messages
334 entitled "What's cooking in git.git" and "What's in git.git" giving
335 the status of various proposed changes.
336
337 ------------------------------------------------
338 MUA specific hints
339
340 Some of patches I receive or pick up from the list share common
341 patterns of breakage. Please make sure your MUA is set up
342 properly not to corrupt whitespaces.
343
344 See the DISCUSSION section of git-format-patch(1) for hints on
345 checking your patch by mailing it to yourself and applying with
346 git-am(1).
347
348 While you are at it, check the resulting commit log message from
349 a trial run of applying the patch. If what is in the resulting
350 commit is not exactly what you would want to see, it is very
351 likely that your maintainer would end up hand editing the log
352 message when he applies your patch. Things like "Hi, this is my
353 first patch.\n", if you really want to put in the patch e-mail,
354 should come after the three-dash line that signals the end of the
355 commit message.
356
357
358 Pine
359 ----
360
361 (Johannes Schindelin)
362
363 I don't know how many people still use pine, but for those poor
364 souls it may be good to mention that the quell-flowed-text is
365 needed for recent versions.
366
367 ... the "no-strip-whitespace-before-send" option, too. AFAIK it
368 was introduced in 4.60.
369
370 (Linus Torvalds)
371
372 And 4.58 needs at least this.
373
374 ---
375 diff-tree 8326dd8350be64ac7fc805f6563a1d61ad10d32c (from e886a61f76edf5410573e92e38ce22974f9c40f1)
376 Author: Linus Torvalds <torvalds@g5.osdl.org>
377 Date: Mon Aug 15 17:23:51 2005 -0700
378
379 Fix pine whitespace-corruption bug
380
381 There's no excuse for unconditionally removing whitespace from
382 the pico buffers on close.
383
384 diff --git a/pico/pico.c b/pico/pico.c
385 --- a/pico/pico.c
386 +++ b/pico/pico.c
387 @@ -219,7 +219,9 @@ PICO *pm;
388 switch(pico_all_done){ /* prepare for/handle final events */
389 case COMP_EXIT : /* already confirmed */
390 packheader();
391 +#if 0
392 stripwhitespace();
393 +#endif
394 c |= COMP_EXIT;
395 break;
396
397
398 (Daniel Barkalow)
399
400 > A patch to SubmittingPatches, MUA specific help section for
401 > users of Pine 4.63 would be very much appreciated.
402
403 Ah, it looks like a recent version changed the default behavior to do the
404 right thing, and inverted the sense of the configuration option. (Either
405 that or Gentoo did it.) So you need to set the
406 "no-strip-whitespace-before-send" option, unless the option you have is
407 "strip-whitespace-before-send", in which case you should avoid checking
408 it.
409
410
411 Thunderbird, KMail, GMail
412 -------------------------
413
414 See the MUA-SPECIFIC HINTS section of git-format-patch(1).
415
416 Gnus
417 ----
418
419 '|' in the *Summary* buffer can be used to pipe the current
420 message to an external program, and this is a handy way to drive
421 "git am". However, if the message is MIME encoded, what is
422 piped into the program is the representation you see in your
423 *Article* buffer after unwrapping MIME. This is often not what
424 you would want for two reasons. It tends to screw up non ASCII
425 characters (most notably in people's names), and also
426 whitespaces (fatal in patches). Running 'C-u g' to display the
427 message in raw form before using '|' to run the pipe can work
428 this problem around.