freshlybakedca.ke
Git fork
1My First Contribution to the Git Project
2========================================
3:sectanchors:
4
5[[summary]]
6== Summary
7
8This is a tutorial demonstrating the end-to-end workflow of creating a change to
9the Git tree, sending it for review, and making changes based on comments.
10
11[[prerequisites]]
12=== Prerequisites
13
14This tutorial assumes you're already fairly familiar with using Git to manage
15source code. The Git workflow steps will largely remain unexplained.
16
17[[related-reading]]
18=== Related Reading
19
20This tutorial aims to summarize the following documents, but the reader may find
21useful additional context:
22
23- `Documentation/SubmittingPatches`
24- `Documentation/howto/new-command.adoc`
25
26[[getting-help]]
27=== Getting Help
28
29If you get stuck, you can seek help in the following places.
30
31==== git@vger.kernel.org
32
33This is the main Git project mailing list where code reviews, version
34announcements, design discussions, and more take place. Those interested in
35contributing are welcome to post questions here. The Git list requires
36plain-text-only emails and prefers inline and bottom-posting when replying to
37mail; you will be CC'd in all replies to you. Optionally, you can subscribe to
38the list by sending an email to <git+subscribe@vger.kernel.org>
39(see https://subspace.kernel.org/subscribing.html for details).
40The https://lore.kernel.org/git[archive] of this mailing list is
41available to view in a browser.
42
43==== https://web.libera.chat/#git-devel[#git-devel] on Libera Chat
44
45This IRC channel is for conversations between Git contributors. If someone is
46currently online and knows the answer to your question, you can receive help
47in real time. Otherwise, you can read the
48https://colabti.org/irclogger/irclogger_logs/git-devel[scrollback] to see
49whether someone answered you. IRC does not allow offline private messaging, so
50if you try to private message someone and then log out of IRC, they cannot
51respond to you. It's better to ask your questions in the channel so that you
52can be answered if you disconnect and so that others can learn from the
53conversation.
54
55==== https://discord.gg/GRFVkzgxRd[#discord] on Discord
56This is an unofficial Git Discord server for everyone, from people just
57starting out with Git to those who develop it. It's a great place to ask
58questions, share tips, and connect with the broader Git community in real time.
59
60The server has channels for general discussions and specific channels for those
61who use Git and those who develop it. The server's search functionality also
62allows you to find previous conversations and answers to common questions.
63
64[[getting-started]]
65== Getting Started
66
67[[cloning]]
68=== Clone the Git Repository
69
70Git is mirrored in a number of locations. Clone the repository from one of them;
71https://git-scm.com/downloads suggests one of the best places to clone from is
72the mirror on GitHub.
73
74----
75$ git clone https://github.com/git/git git
76$ cd git
77----
78
79[[dependencies]]
80=== Installing Dependencies
81
82To build Git from source, you need to have a handful of dependencies installed
83on your system. For a hint of what's needed, you can take a look at
84`INSTALL`, paying close attention to the section about Git's dependencies on
85external programs and libraries. That document mentions a way to "test-drive"
86our freshly built Git without installing; that's the method we'll be using in
87this tutorial.
88
89Make sure that your environment has everything you need by building your brand
90new clone of Git from the above step:
91
92----
93$ make
94----
95
96NOTE: The Git build is parallelizable. `-j#` is not included above but you can
97use it as you prefer, here and elsewhere.
98
99[[identify-problem]]
100=== Identify Problem to Solve
101
102////
103Use + to indicate fixed-width here; couldn't get ` to work nicely with the
104quotes around "Pony Saying 'Um, Hello'".
105////
106In this tutorial, we will add a new command, +git psuh+, short for ``Pony Saying
107`Um, Hello''' - a feature which has gone unimplemented despite a high frequency
108of invocation during users' typical daily workflow.
109
110(We've seen some other effort in this space with the implementation of popular
111commands such as `sl`.)
112
113[[setup-workspace]]
114=== Set Up Your Workspace
115
116Let's start by making a development branch to work on our changes. Per
117`Documentation/SubmittingPatches`, since a brand new command is a new feature,
118it's fine to base your work on `master`. However, in the future for bugfixes,
119etc., you should check that document and base it on the appropriate branch.
120
121For the purposes of this document, we will base all our work on the `master`
122branch of the upstream project. Create the `psuh` branch you will use for
123development like so:
124
125----
126$ git checkout -b psuh origin/master
127----
128
129We'll make a number of commits here in order to demonstrate how to send a topic
130with multiple patches up for review simultaneously.
131
132[[code-it-up]]
133== Code It Up!
134
135NOTE: A reference implementation can be found at
136https://github.com/nasamuffin/git/tree/psuh.
137
138[[add-new-command]]
139=== Adding a New Command
140
141Lots of the subcommands are written as builtins, which means they are
142implemented in C and compiled into the main `git` executable. Implementing the
143very simple `psuh` command as a built-in will demonstrate the structure of the
144codebase, the internal API, and the process of working together as a contributor
145with the reviewers and maintainer to integrate this change into the system.
146
147Built-in subcommands are typically implemented in a function named "cmd_"
148followed by the name of the subcommand, in a source file named after the
149subcommand and contained within `builtin/`. So it makes sense to implement your
150command in `builtin/psuh.c`. Create that file, and within it, write the entry
151point for your command in a function matching the style and signature:
152
153----
154int cmd_psuh(int argc UNUSED, const char **argv UNUSED,
155 const char *prefix UNUSED, struct repository *repo UNUSED)
156----
157
158A few things to note:
159
160* A subcommand implementation takes its command line arguments
161 in `int argc` + `const char **argv`, like `main()` would.
162
163* It also takes two extra parameters, `prefix` and `repo`. What
164 they mean will not be discussed until much later.
165
166* Because this first example will not use any of the parameters,
167 your compiler will give warnings on unused parameters. As the
168 list of these four parameters is mandated by the API to add
169 new built-in commands, you cannot omit them. Instead, you add
170 `UNUSED` to each of them to tell the compiler that you *know*
171 you are not (yet) using it.
172
173We'll also need to add the declaration of psuh; open up `builtin.h`, find the
174declaration for `cmd_pull`, and add a new line for `psuh` immediately before it,
175in order to keep the declarations alphabetically sorted:
176
177----
178int cmd_psuh(int argc, const char **argv, const char *prefix, struct repository *repo);
179----
180
181Be sure to `#include "builtin.h"` in your `psuh.c`. You'll also need to
182`#include "gettext.h"` to use functions related to printing output text.
183
184Go ahead and add some throwaway printf to the `cmd_psuh` function. This is a
185decent starting point as we can now add build rules and register the command.
186
187NOTE: Your throwaway text, as well as much of the text you will be adding over
188the course of this tutorial, is user-facing. That means it needs to be
189localizable. Take a look at `po/README` under "Marking strings for translation".
190Throughout the tutorial, we will mark strings for translation as necessary; you
191should also do so when writing your user-facing commands in the future.
192
193----
194int cmd_psuh(int argc UNUSED, const char **argv UNUSED,
195 const char *prefix UNUSED, struct repository *repo UNUSED)
196{
197 printf(_("Pony saying hello goes here.\n"));
198 return 0;
199}
200----
201
202Let's try to build it. Open `Makefile`, find where `builtin/pull.o` is added
203to `BUILTIN_OBJS`, and add `builtin/psuh.o` in the same way next to it in
204alphabetical order. Once you've done so, move to the top-level directory and
205build simply with `make`. Also add the `DEVELOPER=1` variable to turn on
206some additional warnings:
207
208----
209$ echo DEVELOPER=1 >config.mak
210$ make
211----
212
213NOTE: When you are developing the Git project, it's preferred that you use the
214`DEVELOPER` flag; if there's some reason it doesn't work for you, you can turn
215it off, but it's a good idea to mention the problem to the mailing list.
216
217Great, now your new command builds happily on its own. But nobody invokes it.
218Let's change that.
219
220The list of commands lives in `git.c`. We can register a new command by adding
221a `cmd_struct` to the `commands[]` array. `struct cmd_struct` takes a string
222with the command name, a function pointer to the command implementation, and a
223setup option flag. For now, let's keep mimicking `push`. Find the line where
224`cmd_push` is registered, copy it, and modify it for `cmd_psuh`, placing the new
225line in alphabetical order (immediately before `cmd_pull`).
226
227The options are documented in `builtin.h` under "Adding a new built-in." Since
228we hope to print some data about the user's current workspace context later,
229we need a Git directory, so choose `RUN_SETUP` as your only option.
230
231Go ahead and build again. You should see a clean build, so let's kick the tires
232and see if it works. There's a binary you can use to test with in the
233`bin-wrappers` directory.
234
235----
236$ ./bin-wrappers/git psuh
237----
238
239Check it out! You've got a command! Nice work! Let's commit this.
240
241`git status` reveals modified `Makefile`, `builtin.h`, and `git.c` as well as
242untracked `builtin/psuh.c` and `git-psuh`. First, let's take care of the binary,
243which should be ignored. Open `.gitignore` in your editor, find `/git-pull`, and
244add an entry for your new command in alphabetical order:
245
246----
247...
248/git-prune-packed
249/git-psuh
250/git-pull
251/git-push
252/git-quiltimport
253/git-range-diff
254...
255----
256
257Checking `git status` again should show that `git-psuh` has been removed from
258the untracked list and `.gitignore` has been added to the modified list. Now we
259can stage and commit:
260
261----
262$ git add Makefile builtin.h builtin/psuh.c git.c .gitignore
263$ git commit -s
264----
265
266You will be presented with your editor in order to write a commit message. Start
267the commit with a 50-column or less subject line, including the name of the
268component you're working on, followed by a blank line (always required) and then
269the body of your commit message, which should provide the bulk of the context.
270Remember to be explicit and provide the "Why" of your change, especially if it
271couldn't easily be understood from your diff. When editing your commit message,
272don't remove the `Signed-off-by` trailer which was added by `-s` above.
273
274----
275psuh: add a built-in by popular demand
276
277Internal metrics indicate this is a command many users expect to be
278present. So here's an implementation to help drive customer
279satisfaction and engagement: a pony which doubtfully greets the user,
280or, a Pony Saying "Um, Hello" (PSUH).
281
282This commit message is intentionally formatted to 72 columns per line,
283starts with a single line as "commit message subject" that is written as
284if to command the codebase to do something (add this, teach a command
285that). The body of the message is designed to add information about the
286commit that is not readily deduced from reading the associated diff,
287such as answering the question "why?".
288
289Signed-off-by: A U Thor <author@example.com>
290----
291
292Go ahead and inspect your new commit with `git show`. "psuh:" indicates you
293have modified mainly the `psuh` command. The subject line gives readers an idea
294of what you've changed. The sign-off line (`-s`) indicates that you agree to
295the Developer's Certificate of Origin 1.1 (see the
296`Documentation/SubmittingPatches` +++[[dco]]+++ header).
297
298For the remainder of the tutorial, the subject line only will be listed for the
299sake of brevity. However, fully-fleshed example commit messages are available
300on the reference implementation linked at the top of this document.
301
302[[implementation]]
303=== Implementation
304
305It's probably useful to do at least something besides printing out a string.
306Let's start by having a look at everything we get.
307
308Modify your `cmd_psuh` implementation to dump the args you're passed,
309keeping existing `printf()` calls in place; because the args are now
310used, remove the `UNUSED` macro from them:
311
312----
313 int i;
314
315 ...
316
317 printf(Q_("Your args (there is %d):\n",
318 "Your args (there are %d):\n",
319 argc),
320 argc);
321 for (i = 0; i < argc; i++)
322 printf("%d: %s\n", i, argv[i]);
323
324 printf(_("Your current working directory:\n<top-level>%s%s\n"),
325 prefix ? "/" : "", prefix ? prefix : "");
326
327----
328
329Build and try it. As you may expect, there's pretty much just whatever we give
330on the command line, including the name of our command. (If `prefix` is empty
331for you, try `cd Documentation/ && ../bin-wrappers/git psuh`). That's not so
332helpful. So what other context can we get?
333
334Add a line to `#include "config.h"` and `#include "repository.h"`.
335Then, add the following bits to the function body:
336function body:
337
338----
339 const char *cfg_name;
340
341...
342
343 repo_config(repo, git_default_config, NULL);
344 if (repo_config_get_string_tmp(repo, "user.name", &cfg_name))
345 printf(_("No name is found in config\n"));
346 else
347 printf(_("Your name: %s\n"), cfg_name);
348----
349
350`repo_config()` will grab the configuration from config files known to Git and
351apply standard precedence rules. `repo_config_get_string_tmp()` will look up
352a specific key ("user.name") and give you the value. There are a number of
353single-key lookup functions like this one; you can see them all (and more info
354about how to use `repo_config()`) in `Documentation/technical/api-config.adoc`.
355
356You should see that the name printed matches the one you see when you run:
357
358----
359$ git config --get user.name
360----
361
362Great! Now we know how to check for values in the Git config. Let's commit this
363too, so we don't lose our progress.
364
365----
366$ git add builtin/psuh.c
367$ git commit -sm "psuh: show parameters & config opts"
368----
369
370NOTE: Again, the above is for sake of brevity in this tutorial. In a real change
371you should not use `-m` but instead use the editor to write a meaningful
372message.
373
374Still, it'd be nice to know what the user's working context is like. Let's see
375if we can print the name of the user's current branch. We can mimic the
376`git status` implementation; the printer is located in `wt-status.c` and we can
377see that the branch is held in a `struct wt_status`.
378
379`wt_status_print()` gets invoked by `cmd_status()` in `builtin/commit.c`.
380Looking at that implementation we see the status config being populated like so:
381
382----
383status_init_config(&s, git_status_config);
384----
385
386But as we drill down, we can find that `status_init_config()` wraps a call
387to `repo_config()`. Let's modify the code we wrote in the previous commit.
388
389Be sure to include the header to allow you to use `struct wt_status`:
390
391----
392#include "wt-status.h"
393----
394
395Then modify your `cmd_psuh` implementation to declare your `struct wt_status`,
396prepare it, and print its contents:
397
398----
399 struct wt_status status;
400
401...
402
403 wt_status_prepare(repo, &status);
404 repo_config(repo, git_default_config, &status);
405
406...
407
408 printf(_("Your current branch: %s\n"), status.branch);
409----
410
411Run it again. Check it out - here's the (verbose) name of your current branch!
412
413Let's commit this as well.
414
415----
416$ git add builtin/psuh.c
417$ git commit -sm "psuh: print the current branch"
418----
419
420Now let's see if we can get some info about a specific commit.
421
422Luckily, there are some helpers for us here. `commit.h` has a function called
423`lookup_commit_reference_by_name` to which we can simply provide a hardcoded
424string; `pretty.h` has an extremely handy `pp_commit_easy()` call which doesn't
425require a full format object to be passed.
426
427Add the following includes:
428
429----
430#include "commit.h"
431#include "pretty.h"
432----
433
434Then, add the following lines within your implementation of `cmd_psuh()` near
435the declarations and the logic, respectively.
436
437----
438 struct commit *c = NULL;
439 struct strbuf commitline = STRBUF_INIT;
440
441...
442
443 c = lookup_commit_reference_by_name("origin/master");
444
445 if (c != NULL) {
446 pp_commit_easy(CMIT_FMT_ONELINE, c, &commitline);
447 printf(_("Current commit: %s\n"), commitline.buf);
448 }
449----
450
451The `struct strbuf` provides some safety belts to your basic `char*`, one of
452which is a length member to prevent buffer overruns. It needs to be initialized
453nicely with `STRBUF_INIT`. Keep it in mind when you need to pass around `char*`.
454
455`lookup_commit_reference_by_name` resolves the name you pass it, so you can play
456with the value there and see what kind of things you can come up with.
457
458`pp_commit_easy` is a convenience wrapper in `pretty.h` that takes a single
459format enum shorthand, rather than an entire format struct. It then
460pretty-prints the commit according to that shorthand. These are similar to the
461formats available with `--pretty=FOO` in many Git commands.
462
463Build it and run, and if you're using the same name in the example, you should
464see the subject line of the most recent commit in `origin/master` that you know
465about. Neat! Let's commit that as well.
466
467----
468$ git add builtin/psuh.c
469$ git commit -sm "psuh: display the top of origin/master"
470----
471
472[[add-documentation]]
473=== Adding Documentation
474
475Awesome! You've got a fantastic new command that you're ready to share with the
476community. But hang on just a minute - this isn't very user-friendly. Run the
477following:
478
479----
480$ ./bin-wrappers/git help psuh
481----
482
483Your new command is undocumented! Let's fix that.
484
485Take a look at `Documentation/git-*.adoc`. These are the manpages for the
486subcommands that Git knows about. You can open these up and take a look to get
487acquainted with the format, but then go ahead and make a new file
488`Documentation/git-psuh.adoc`. Like with most of the documentation in the Git
489project, help pages are written with AsciiDoc (see CodingGuidelines, "Writing
490Documentation" section). Use the following template to fill out your own
491manpage:
492
493// Surprisingly difficult to embed AsciiDoc source within AsciiDoc.
494[listing]
495....
496git-psuh(1)
497===========
498
499NAME
500----
501git-psuh - Delight users' typo with a shy horse
502
503
504SYNOPSIS
505--------
506[verse]
507'git-psuh [<arg>...]'
508
509DESCRIPTION
510-----------
511...
512
513OPTIONS[[OPTIONS]]
514------------------
515...
516
517OUTPUT
518------
519...
520
521GIT
522---
523Part of the linkgit:git[1] suite
524....
525
526The most important pieces of this to note are the file header, underlined by =,
527the NAME section, and the SYNOPSIS, which would normally contain the grammar if
528your command took arguments. Try to use well-established manpage headers so your
529documentation is consistent with other Git and UNIX manpages; this makes life
530easier for your user, who can skip to the section they know contains the
531information they need.
532
533NOTE: Before trying to build the docs, make sure you have the package `asciidoc`
534installed.
535
536Now that you've written your manpage, you'll need to build it explicitly. We
537convert your AsciiDoc to troff which is man-readable like so:
538
539----
540$ make all doc
541$ man Documentation/git-psuh.1
542----
543
544or
545
546----
547$ make -C Documentation/ git-psuh.1
548$ man Documentation/git-psuh.1
549----
550
551While this isn't as satisfying as running through `git help`, you can at least
552check that your help page looks right.
553
554You can also check that the documentation coverage is good (that is, the project
555sees that your command has been implemented as well as documented) by running
556`make check-docs` from the top-level.
557
558Go ahead and commit your new documentation change.
559
560[[add-usage]]
561=== Adding Usage Text
562
563Try and run `./bin-wrappers/git psuh -h`. Your command should crash at the end.
564That's because `-h` is a special case which your command should handle by
565printing usage.
566
567Take a look at `Documentation/technical/api-parse-options.adoc`. This is a handy
568tool for pulling out options you need to be able to handle, and it takes a
569usage string.
570
571In order to use it, we'll need to prepare a NULL-terminated array of usage
572strings and a `builtin_psuh_options` array.
573
574Add a line to `#include "parse-options.h"`.
575
576At global scope, add your array of usage strings:
577
578----
579static const char * const psuh_usage[] = {
580 N_("git psuh [<arg>...]"),
581 NULL,
582};
583----
584
585Then, within your `cmd_psuh()` implementation, we can declare and populate our
586`option` struct. Ours is pretty boring but you can add more to it if you want to
587explore `parse_options()` in more detail:
588
589----
590 struct option options[] = {
591 OPT_END()
592 };
593----
594
595Finally, before you print your args and prefix, add the call to
596`parse-options()`:
597
598----
599 argc = parse_options(argc, argv, prefix, options, psuh_usage, 0);
600----
601
602This call will modify your `argv` parameter. It will strip the options you
603specified in `options` from `argv` and the locations pointed to from `options`
604entries will be updated. Be sure to replace your `argc` with the result from
605`parse_options()`, or you will be confused if you try to parse `argv` later.
606
607It's worth noting the special argument `--`. As you may be aware, many Unix
608commands use `--` to indicate "end of named parameters" - all parameters after
609the `--` are interpreted merely as positional arguments. (This can be handy if
610you want to pass as a parameter something which would usually be interpreted as
611a flag.) `parse_options()` will terminate parsing when it reaches `--` and give
612you the rest of the options afterwards, untouched.
613
614Now that you have a usage hint, you can teach Git how to show it in the general
615command list shown by `git help git` or `git help -a`, which is generated from
616`command-list.txt`. Find the line for 'git-pull' so you can add your 'git-psuh'
617line above it in alphabetical order. Now, we can add some attributes about the
618command which impacts where it shows up in the aforementioned help commands. The
619top of `command-list.txt` shares some information about what each attribute
620means; in those help pages, the commands are sorted according to these
621attributes. `git psuh` is user-facing, or porcelain - so we will mark it as
622"mainporcelain". For "mainporcelain" commands, the comments at the top of
623`command-list.txt` indicate we can also optionally add an attribute from another
624list; since `git psuh` shows some information about the user's workspace but
625doesn't modify anything, let's mark it as "info". Make sure to keep your
626attributes in the same style as the rest of `command-list.txt` using spaces to
627align and delineate them:
628
629----
630git-prune-packed plumbingmanipulators
631git-psuh mainporcelain info
632git-pull mainporcelain remote
633git-push mainporcelain remote
634----
635
636Build again. Now, when you run with `-h`, you should see your usage printed and
637your command terminated before anything else interesting happens. Great!
638
639Go ahead and commit this one, too.
640
641[[testing]]
642== Testing
643
644It's important to test your code - even for a little toy command like this one.
645Moreover, your patch won't be accepted into the Git tree without tests. Your
646tests should:
647
648* Illustrate the current behavior of the feature
649* Prove the current behavior matches the expected behavior
650* Ensure the externally-visible behavior isn't broken in later changes
651
652So let's write some tests.
653
654Related reading: `t/README`
655
656[[overview-test-structure]]
657=== Overview of Testing Structure
658
659The tests in Git live in `t/` and are named with a 4-digit decimal number using
660the schema shown in the Naming Tests section of `t/README`.
661
662[[write-new-test]]
663=== Writing Your Test
664
665Since this a toy command, let's go ahead and name the test with t9999. However,
666as many of the family/subcmd combinations are full, best practice seems to be
667to find a command close enough to the one you've added and share its naming
668space.
669
670Create a new file `t/t9999-psuh-tutorial.sh`. Begin with the header as so (see
671"Writing Tests" and "Source 'test-lib.sh'" in `t/README`):
672
673----
674#!/bin/sh
675
676test_description='git-psuh test
677
678This test runs git-psuh and makes sure it does not crash.'
679
680. ./test-lib.sh
681----
682
683Tests are framed inside of a `test_expect_success` in order to output TAP
684formatted results. Let's make sure that `git psuh` doesn't exit poorly and does
685mention the right animal somewhere:
686
687----
688test_expect_success 'runs correctly with no args and good output' '
689 git psuh >actual &&
690 grep Pony actual
691'
692----
693
694Indicate that you've run everything you wanted by adding the following at the
695bottom of your script:
696
697----
698test_done
699----
700
701Make sure you mark your test script executable:
702
703----
704$ chmod +x t/t9999-psuh-tutorial.sh
705----
706
707You can get an idea of whether you created your new test script successfully
708by running `make -C t test-lint`, which will check for things like test number
709uniqueness, executable bit, and so on.
710
711[[local-test]]
712=== Running Locally
713
714Let's try and run locally:
715
716----
717$ make
718$ cd t/ && prove t9999-psuh-tutorial.sh
719----
720
721You can run the full test suite and ensure `git-psuh` didn't break anything:
722
723----
724$ cd t/
725$ prove -j$(nproc) --shuffle t[0-9]*.sh
726----
727
728NOTE: You can also do this with `make test` or use any testing harness which can
729speak TAP. `prove` can run concurrently. `shuffle` randomizes the order the
730tests are run in, which makes them resilient against unwanted inter-test
731dependencies. `prove` also makes the output nicer.
732
733Go ahead and commit this change, as well.
734
735[[ready-to-share]]
736== Getting Ready to Share: Anatomy of a Patch Series
737
738You may have noticed already that the Git project performs its code reviews via
739emailed patches, which are then applied by the maintainer when they are ready
740and approved by the community. The Git project does not accept contributions from
741pull requests, and the patches emailed for review need to be formatted a
742specific way.
743
744:patch-series: https://lore.kernel.org/git/pull.1218.git.git.1645209647.gitgitgadget@gmail.com/
745:lore: https://lore.kernel.org/git/
746
747Before taking a look at how to convert your commits into emailed patches,
748let's analyze what the end result, a "patch series", looks like. Here is an
749{patch-series}[example] of the summary view for a patch series on the web interface of
750the {lore}[Git mailing list archive]:
751
752----
7532022-02-18 18:40 [PATCH 0/3] libify reflog John Cai via GitGitGadget
7542022-02-18 18:40 ` [PATCH 1/3] reflog: libify delete reflog function and helpers John Cai via GitGitGadget
7552022-02-18 19:10 ` Ævar Arnfjörð Bjarmason [this message]
7562022-02-18 19:39 ` Taylor Blau
7572022-02-18 19:48 ` Ævar Arnfjörð Bjarmason
7582022-02-18 19:35 ` Taylor Blau
7592022-02-21 1:43 ` John Cai
7602022-02-21 1:50 ` Taylor Blau
7612022-02-23 19:50 ` John Cai
7622022-02-18 20:00 ` // other replies elided
7632022-02-18 18:40 ` [PATCH 2/3] reflog: call reflog_delete from reflog.c John Cai via GitGitGadget
7642022-02-18 19:15 ` Ævar Arnfjörð Bjarmason
7652022-02-18 20:26 ` Junio C Hamano
7662022-02-18 18:40 ` [PATCH 3/3] stash: call reflog_delete from reflog.c John Cai via GitGitGadget
7672022-02-18 19:20 ` Ævar Arnfjörð Bjarmason
7682022-02-19 0:21 ` Taylor Blau
7692022-02-22 2:36 ` John Cai
7702022-02-22 10:51 ` Ævar Arnfjörð Bjarmason
7712022-02-18 19:29 ` [PATCH 0/3] libify reflog Ævar Arnfjörð Bjarmason
7722022-02-22 18:30 ` [PATCH v2 0/3] libify reflog John Cai via GitGitGadget
7732022-02-22 18:30 ` [PATCH v2 1/3] stash: add test to ensure reflog --rewrite --updatref behavior John Cai via GitGitGadget
7742022-02-23 8:54 ` Ævar Arnfjörð Bjarmason
7752022-02-23 21:27 ` Junio C Hamano
776// continued
777----
778
779We can note a few things:
780
781- Each commit is sent as a separate email, with the commit message title as
782 subject, prefixed with "[PATCH _i_/_n_]" for the _i_-th commit of an
783 _n_-commit series.
784- Each patch is sent as a reply to an introductory email called the _cover
785 letter_ of the series, prefixed "[PATCH 0/_n_]".
786- Subsequent iterations of the patch series are labelled "PATCH v2", "PATCH
787 v3", etc. in place of "PATCH". For example, "[PATCH v2 1/3]" would be the first of
788 three patches in the second iteration. Each iteration is sent with a new cover
789 letter (like "[PATCH v2 0/3]" above), itself a reply to the cover letter of the
790 previous iteration (more on that below).
791
792NOTE: A single-patch topic is sent with "[PATCH]", "[PATCH v2]", etc. without
793_i_/_n_ numbering (in the above thread overview, no single-patch topic appears,
794though).
795
796[[cover-letter]]
797=== The cover letter
798
799In addition to an email per patch, the Git community also expects your patches
800to come with a cover letter. This is an important component of change
801submission as it explains to the community from a high level what you're trying
802to do, and why, in a way that's more apparent than just looking at your
803patches.
804
805The title of your cover letter should be something which succinctly covers the
806purpose of your entire topic branch. It's often in the imperative mood, just
807like our commit message titles. Here is how we'll title our series:
808
809---
810Add the 'psuh' command
811---
812
813The body of the cover letter is used to give additional context to reviewers.
814Be sure to explain anything your patches don't make clear on their own, but
815remember that since the cover letter is not recorded in the commit history,
816anything that might be useful to future readers of the repository's history
817should also be in your commit messages.
818
819Here's an example body for `psuh`:
820
821----
822Our internal metrics indicate widespread interest in the command
823git-psuh - that is, many users are trying to use it, but finding it is
824unavailable, using some unknown workaround instead.
825
826The following handful of patches add the psuh command and implement some
827handy features on top of it.
828
829This patchset is part of the MyFirstContribution tutorial and should not
830be merged.
831----
832
833At this point the tutorial diverges, in order to demonstrate two
834different methods of formatting your patchset and getting it reviewed.
835
836The first method to be covered is GitGitGadget, which is useful for those
837already familiar with GitHub's common pull request workflow. This method
838requires a GitHub account.
839
840The second method to be covered is `git send-email`, which can give slightly
841more fine-grained control over the emails to be sent. This method requires some
842setup which can change depending on your system and will not be covered in this
843tutorial.
844
845Regardless of which method you choose, your engagement with reviewers will be
846the same; the review process will be covered after the sections on GitGitGadget
847and `git send-email`.
848
849[[howto-ggg]]
850== Sending Patches via GitGitGadget
851
852One option for sending patches is to follow a typical pull request workflow and
853send your patches out via GitGitGadget. GitGitGadget is a tool created by
854Johannes Schindelin to make life as a Git contributor easier for those used to
855the GitHub PR workflow. It allows contributors to open pull requests against its
856mirror of the Git project, and does some magic to turn the PR into a set of
857emails and send them out for you. It also runs the Git continuous integration
858suite for you. It's documented at https://gitgitgadget.github.io/.
859
860[[create-fork]]
861=== Forking `git/git` on GitHub
862
863Before you can send your patch off to be reviewed using GitGitGadget, you will
864need to fork the Git project and upload your changes. First thing - make sure
865you have a GitHub account.
866
867Head to the https://github.com/git/git[GitHub mirror] and look for the Fork
868button. Place your fork wherever you deem appropriate and create it.
869
870[[upload-to-fork]]
871=== Uploading to Your Own Fork
872
873To upload your branch to your own fork, you'll need to add the new fork as a
874remote. You can use `git remote -v` to show the remotes you have added already.
875From your new fork's page on GitHub, you can press "Clone or download" to get
876the URL; then you need to run the following to add, replacing your own URL and
877remote name for the examples provided:
878
879----
880$ git remote add remotename git@github.com:remotename/git.git
881----
882
883or to use the HTTPS URL:
884
885----
886$ git remote add remotename https://github.com/remotename/git/.git
887----
888
889Run `git remote -v` again and you should see the new remote showing up.
890`git fetch remotename` (with the real name of your remote replaced) in order to
891get ready to push.
892
893Next, double-check that you've been doing all your development in a new branch
894by running `git branch`. If you didn't, now is a good time to move your new
895commits to their own branch.
896
897As mentioned briefly at the beginning of this document, we are basing our work
898on `master`, so go ahead and update as shown below, or using your preferred
899workflow.
900
901----
902$ git checkout master
903$ git pull -r
904$ git rebase master psuh
905----
906
907Finally, you're ready to push your new topic branch! (Due to our branch and
908command name choices, be careful when you type the command below.)
909
910----
911$ git push remotename psuh
912----
913
914Now you should be able to go and check out your newly created branch on GitHub.
915
916[[send-pr-ggg]]
917=== Sending a PR to GitGitGadget
918
919In order to have your code tested and formatted for review, you need to start by
920opening a Pull Request against either `gitgitgadget/git` or `git/git`. Head to
921https://github.com/gitgitgadget/git or https://github.com/git/git and open a PR
922either with the "New pull request" button or the convenient "Compare & pull
923request" button that may appear with the name of your newly pushed branch.
924
925The differences between using `gitgitgadget/git` and `git/git` as your base can
926be found [here](https://gitgitgadget.github.io/#should-i-use-gitgitgadget-on-gitgitgadgets-git-fork-or-on-gits-github-mirror)
927
928Review the PR's title and description, as they're used by GitGitGadget
929respectively as the subject and body of the cover letter for your change. Refer
930to <<cover-letter,"The cover letter">> above for advice on how to title your
931submission and what content to include in the description.
932
933NOTE: For single-patch contributions, your commit message should already be
934meaningful and explain at a high level the purpose (what is happening and why)
935of your patch, so you usually do not need any additional context. In that case,
936remove the PR description that GitHub automatically generates from your commit
937message (your PR description should be empty). If you do need to supply even
938more context, you can do so in that space and it will be appended to the email
939that GitGitGadget will send, between the three-dash line and the diffstat
940(see <<single-patch,Bonus Chapter: One-Patch Changes>> for how this looks once
941submitted).
942
943When you're happy, submit your pull request.
944
945[[run-ci-ggg]]
946=== Running CI and Getting Ready to Send
947
948If it's your first time using GitGitGadget (which is likely, as you're using
949this tutorial) then someone will need to give you permission to use the tool.
950As mentioned in the GitGitGadget documentation, you just need someone who
951already uses it to comment on your PR with `/allow <username>`. GitGitGadget
952will automatically run your PRs through the CI even without the permission given
953but you will not be able to `/submit` your changes until someone allows you to
954use the tool.
955
956NOTE: You can typically find someone who can `/allow` you on GitGitGadget by
957either examining recent pull requests where someone has been granted `/allow`
958(https://github.com/gitgitgadget/git/pulls?utf8=%E2%9C%93&q=is%3Apr+is%3Aopen+%22%2Fallow%22[Search:
959is:pr is:open "/allow"]), in which case both the author and the person who
960granted the `/allow` can now `/allow` you, or by inquiring on the
961https://web.libera.chat/#git-devel[#git-devel] IRC channel on Libera Chat
962linking your pull request and asking for someone to `/allow` you.
963
964If the CI fails, you can update your changes with `git rebase -i` and push your
965branch again:
966
967----
968$ git push -f remotename psuh
969----
970
971In fact, you should continue to make changes this way up until the point when
972your patch is accepted into `next`.
973
974////
975TODO https://github.com/gitgitgadget/gitgitgadget/issues/83
976It'd be nice to be able to verify that the patch looks good before sending it
977to everyone on Git mailing list.
978[[check-work-ggg]]
979=== Check Your Work
980////
981
982[[send-mail-ggg]]
983=== Sending Your Patches
984
985Now that your CI is passing and someone has granted you permission to use
986GitGitGadget with the `/allow` command, sending out for review is as simple as
987commenting on your PR with `/submit`.
988
989[[responding-ggg]]
990=== Updating With Comments
991
992Skip ahead to <<reviewing,Responding to Reviews>> for information on how to
993reply to review comments you will receive on the mailing list.
994
995Once you have your branch again in the shape you want following all review
996comments, you can submit again:
997
998----
999$ git push -f remotename psuh
1000----
1001
1002Next, go look at your pull request against GitGitGadget; you should see the CI
1003has been kicked off again. Now while the CI is running is a good time for you
1004to modify your description at the top of the pull request thread; it will be
1005used again as the cover letter. You should use this space to describe what
1006has changed since your previous version, so that your reviewers have some idea
1007of what they're looking at. When the CI is done running, you can comment once
1008more with `/submit` - GitGitGadget will automatically add a v2 mark to your
1009changes.
1010
1011[[howto-git-send-email]]
1012== Sending Patches with `git send-email`
1013
1014If you don't want to use GitGitGadget, you can also use Git itself to mail your
1015patches. Some benefits of using Git this way include finer grained control of
1016subject line (for example, being able to use the tag [RFC PATCH] in the subject)
1017and being able to send a ``dry run'' mail to yourself to ensure it all looks
1018good before going out to the list.
1019
1020[[setup-git-send-email]]
1021=== Prerequisite: Setting Up `git send-email`
1022
1023Configuration for `send-email` can vary based on your operating system and email
1024provider, and so will not be covered in this tutorial, beyond stating that in
1025many distributions of Linux, `git-send-email` is not packaged alongside the
1026typical `git` install. You may need to install this additional package; there
1027are a number of resources online to help you do so. You will also need to
1028determine the right way to configure it to use your SMTP server; again, as this
1029configuration can change significantly based on your system and email setup, it
1030is out of scope for the context of this tutorial.
1031
1032[[format-patch]]
1033=== Preparing Initial Patchset
1034
1035Sending emails with Git is a two-part process; before you can prepare the emails
1036themselves, you'll need to prepare the patches. Luckily, this is pretty simple:
1037
1038----
1039$ git format-patch --cover-letter -o psuh/ --base=auto psuh@{u}..psuh
1040----
1041
1042 . The `--cover-letter` option tells `format-patch` to create a
1043 cover letter template for you. You will need to fill in the
1044 template before you're ready to send - but for now, the template
1045 will be next to your other patches.
1046
1047 . The `-o psuh/` option tells `format-patch` to place the patch
1048 files into a directory. This is useful because `git send-email`
1049 can take a directory and send out all the patches from there.
1050
1051 . The `--base=auto` option tells the command to record the "base
1052 commit", on which the recipient is expected to apply the patch
1053 series. The `auto` value will cause `format-patch` to compute
1054 the base commit automatically, which is the merge base of tip
1055 commit of the remote-tracking branch and the specified revision
1056 range.
1057
1058 . The `psuh@{u}..psuh` option tells `format-patch` to generate
1059 patches for the commits you created on the `psuh` branch since it
1060 forked from its upstream (which is `origin/master` if you
1061 followed the example in the "Set up your workspace" section). If
1062 you are already on the `psuh` branch, you can just say `@{u}`,
1063 which means "commits on the current branch since it forked from
1064 its upstream", which is the same thing.
1065
1066The command will make one patch file per commit. After you
1067run, you can go have a look at each of the patches with your favorite text
1068editor and make sure everything looks alright; however, it's not recommended to
1069make code fixups via the patch file. It's a better idea to make the change the
1070normal way using `git rebase -i` or by adding a new commit than by modifying a
1071patch.
1072
1073NOTE: Optionally, you can also use the `--rfc` flag to prefix your patch subject
1074with ``[RFC PATCH]'' instead of ``[PATCH]''. RFC stands for ``request for
1075comments'' and indicates that while your code isn't quite ready for submission,
1076you'd like to begin the code review process. This can also be used when your
1077patch is a proposal, but you aren't sure whether the community wants to solve
1078the problem with that approach or not - to conduct a sort of design review. You
1079may also see on the list patches marked ``WIP'' - this means they are incomplete
1080but want reviewers to look at what they have so far. You can add this flag with
1081`--subject-prefix=WIP`.
1082
1083Check and make sure that your patches and cover letter template exist in the
1084directory you specified - you're nearly ready to send out your review!
1085
1086[[preparing-cover-letter]]
1087=== Preparing Email
1088
1089Since you invoked `format-patch` with `--cover-letter`, you've already got a
1090cover letter template ready. Open it up in your favorite editor.
1091
1092You should see a number of headers present already. Check that your `From:`
1093header is correct. Then modify your `Subject:` (see <<cover-letter,above>> for
1094how to choose good title for your patch series):
1095
1096----
1097Subject: [PATCH 0/7] Add the 'psuh' command
1098----
1099
1100Make sure you retain the ``[PATCH 0/X]'' part; that's what indicates to the Git
1101community that this email is the beginning of a patch series, and many
1102reviewers filter their email for this type of flag.
1103
1104You'll need to add some extra parameters when you invoke `git send-email` to add
1105the cover letter.
1106
1107Next you'll have to fill out the body of your cover letter. Again, see
1108<<cover-letter,above>> for what content to include.
1109
1110The template created by `git format-patch --cover-letter` includes a diffstat.
1111This gives reviewers a summary of what they're in for when reviewing your topic.
1112The one generated for `psuh` from the sample implementation looks like this:
1113
1114----
1115 Documentation/git-psuh.adoc | 40 +++++++++++++++++++++
1116 Makefile | 1 +
1117 builtin.h | 1 +
1118 builtin/psuh.c | 73 ++++++++++++++++++++++++++++++++++++++
1119 git.c | 1 +
1120 t/t9999-psuh-tutorial.sh | 12 +++++++
1121 6 files changed, 128 insertions(+)
1122 create mode 100644 Documentation/git-psuh.adoc
1123 create mode 100644 builtin/psuh.c
1124 create mode 100755 t/t9999-psuh-tutorial.sh
1125----
1126
1127Finally, the letter will include the version of Git used to generate the
1128patches. You can leave that string alone.
1129
1130[[sending-git-send-email]]
1131=== Sending Email
1132
1133At this point you should have a directory `psuh/` which is filled with your
1134patches and a cover letter. Time to mail it out! You can send it like this:
1135
1136----
1137$ git send-email --to=target@example.com psuh/*.patch
1138----
1139
1140NOTE: Check `git help send-email` for some other options which you may find
1141valuable, such as changing the Reply-to address or adding more CC and BCC lines.
1142
1143:contrib-scripts: footnoteref:[contrib-scripts,Scripts under `contrib/` are +
1144not part of the core `git` binary and must be called directly. Clone the Git +
1145codebase and run `perl contrib/contacts/git-contacts`.]
1146
1147NOTE: If you're not sure whom to CC, running `contrib/contacts/git-contacts` can
1148list potential reviewers. In addition, you can do `git send-email
1149--cc-cmd='perl contrib/contacts/git-contacts' feature/*.patch`{contrib-scripts} to
1150automatically pass this list of emails to `send-email`.
1151
1152NOTE: When you are sending a real patch, it will go to git@vger.kernel.org - but
1153please don't send your patchset from the tutorial to the real mailing list! For
1154now, you can send it to yourself, to make sure you understand how it will look.
1155
1156After you run the command above, you will be presented with an interactive
1157prompt for each patch that's about to go out. This gives you one last chance to
1158edit or quit sending something (but again, don't edit code this way). Once you
1159press `y` or `a` at these prompts your emails will be sent! Congratulations!
1160
1161Awesome, now the community will drop everything and review your changes. (Just
1162kidding - be patient!)
1163
1164[[v2-git-send-email]]
1165=== Sending v2
1166
1167This section will focus on how to send a v2 of your patchset. To learn what
1168should go into v2, skip ahead to <<reviewing,Responding to Reviews>> for
1169information on how to handle comments from reviewers.
1170
1171We'll reuse our `psuh` topic branch for v2. Before we make any changes, we'll
1172mark the tip of our v1 branch for easy reference:
1173
1174----
1175$ git checkout psuh
1176$ git branch psuh-v1
1177----
1178
1179Refine your patch series by using `git rebase -i` to adjust commits based upon
1180reviewer comments. Once the patch series is ready for submission, generate your
1181patches again, but with some new flags:
1182
1183----
1184$ git format-patch -v2 --cover-letter -o psuh/ --range-diff master..psuh-v1 master..
1185----
1186
1187The `--range-diff master..psuh-v1` parameter tells `format-patch` to include a
1188range-diff between `psuh-v1` and `psuh` in the cover letter (see
1189linkgit:git-range-diff[1]). This helps tell reviewers about the differences
1190between your v1 and v2 patches.
1191
1192The `-v2` parameter tells `format-patch` to output your patches
1193as version "2". For instance, you may notice that your v2 patches are
1194all named like `v2-000n-my-commit-subject.patch`. `-v2` will also format
1195your patches by prefixing them with "[PATCH v2]" instead of "[PATCH]",
1196and your range-diff will be prefaced with "Range-diff against v1".
1197
1198After you run this command, `format-patch` will output the patches to the `psuh/`
1199directory, alongside the v1 patches. Using a single directory makes it easy to
1200refer to the old v1 patches while proofreading the v2 patches, but you will need
1201to be careful to send out only the v2 patches. We will use a pattern like
1202`psuh/v2-*.patch` (not `psuh/*.patch`, which would match v1 and v2 patches).
1203
1204Edit your cover letter again. Now is a good time to mention what's different
1205between your last version and now, if it's something significant. You do not
1206need the exact same body in your second cover letter; focus on explaining to
1207reviewers the changes you've made that may not be as visible.
1208
1209You will also need to go and find the Message-ID of your previous cover letter.
1210You can either note it when you send the first series, from the output of `git
1211send-email`, or you can look it up on the
1212https://lore.kernel.org/git[mailing list]. Find your cover letter in the
1213archives, click on it, then click "permalink" or "raw" to reveal the Message-ID
1214header. It should match:
1215
1216----
1217Message-ID: <foo.12345.author@example.com>
1218----
1219
1220Your Message-ID is `<foo.12345.author@example.com>`. This example will be used
1221below as well; make sure to replace it with the correct Message-ID for your
1222**previous cover letter** - that is, if you're sending v2, use the Message-ID
1223from v1; if you're sending v3, use the Message-ID from v2.
1224
1225While you're looking at the email, you should also note who is CC'd, as it's
1226common practice in the mailing list to keep all CCs on a thread. You can add
1227these CC lines directly to your cover letter with a line like so in the header
1228(before the Subject line):
1229
1230----
1231CC: author@example.com, Othe R <other@example.com>
1232----
1233
1234Now send the emails again, paying close attention to which messages you pass in
1235to the command:
1236
1237----
1238$ git send-email --to=target@example.com
1239 --in-reply-to="<foo.12345.author@example.com>"
1240 psuh/v2-*.patch
1241----
1242
1243[[single-patch]]
1244=== Bonus Chapter: One-Patch Changes
1245
1246In some cases, your very small change may consist of only one patch. When that
1247happens, you only need to send one email. Your commit message should already be
1248meaningful and explain at a high level the purpose (what is happening and why)
1249of your patch, but if you need to supply even more context, you can do so below
1250the `---` in your patch. Take the example below, which was generated with `git
1251format-patch` on a single commit, and then edited to add the content between
1252the `---` and the diffstat.
1253
1254----
1255From 1345bbb3f7ac74abde040c12e737204689a72723 Mon Sep 17 00:00:00 2001
1256From: A U Thor <author@example.com>
1257Date: Thu, 18 Apr 2019 15:11:02 -0700
1258Subject: [PATCH] README: change the grammar
1259
1260I think it looks better this way. This part of the commit message will
1261end up in the commit-log.
1262
1263Signed-off-by: A U Thor <author@example.com>
1264---
1265Let's have a wild discussion about grammar on the mailing list. This
1266part of my email will never end up in the commit log. Here is where I
1267can add additional context to the mailing list about my intent, outside
1268of the context of the commit log. This section was added after `git
1269format-patch` was run, by editing the patch file in a text editor.
1270
1271 README.md | 2 +-
1272 1 file changed, 1 insertion(+), 1 deletion(-)
1273
1274diff --git a/README.md b/README.md
1275index 88f126184c..38da593a60 100644
1276--- a/README.md
1277+++ b/README.md
1278@@ -3,7 +3,7 @@
1279 Git - fast, scalable, distributed revision control system
1280 =========================================================
1281
1282-Git is a fast, scalable, distributed revision control system with an
1283+Git is a fast, scalable, and distributed revision control system with an
1284 unusually rich command set that provides both high-level operations
1285 and full access to internals.
1286
1287--
12882.21.0.392.gf8f6787159e-goog
1289----
1290
1291[[now-what]]
1292== My Patch Got Emailed - Now What?
1293
1294Please give reviewers enough time to process your initial patch before
1295sending an updated version. That is, resist the temptation to send a new
1296version immediately, because others may have already started reviewing
1297your initial version.
1298
1299While waiting for review comments, you may find mistakes in your initial
1300patch, or perhaps realize a different and better way to achieve the goal
1301of the patch. In this case you may communicate your findings to other
1302reviewers as follows:
1303
1304 - If the mistakes you found are minor, send a reply to your patch as if
1305 you were a reviewer and mention that you will fix them in an
1306 updated version.
1307
1308 - On the other hand, if you think you want to change the course so
1309 drastically that reviews on the initial patch would be a waste of
1310 time (for everyone involved), retract the patch immediately with
1311 a reply like "I am working on a much better approach, so please
1312 ignore this patch and wait for the updated version."
1313
1314Now, the above is a good practice if you sent your initial patch
1315prematurely without polish. But a better approach of course is to avoid
1316sending your patch prematurely in the first place.
1317
1318Please be considerate of the time needed by reviewers to examine each
1319new version of your patch. Rather than seeing the initial version right
1320now (followed by several "oops, I like this version better than the
1321previous one" patches over 2 days), reviewers would strongly prefer if a
1322single polished version came 2 days later instead, and that version with
1323fewer mistakes were the only one they would need to review.
1324
1325
1326[[reviewing]]
1327=== Responding to Reviews
1328
1329After a few days, you will hopefully receive a reply to your patchset with some
1330comments. Woohoo! Now you can get back to work.
1331
1332It's good manners to reply to each comment, notifying the reviewer that you have
1333made the change suggested, feel the original is better, or that the comment
1334inspired you to do something a new way which is superior to both the original
1335and the suggested change. This way reviewers don't need to inspect your v2 to
1336figure out whether you implemented their comment or not.
1337
1338Reviewers may ask you about what you wrote in the patchset, either in
1339the proposed commit log message or in the changes themselves. You
1340should answer these questions in your response messages, but often the
1341reason why reviewers asked these questions to understand what you meant
1342to write is because your patchset needed clarification to be understood.
1343
1344Do not be satisfied by just answering their questions in your response
1345and hear them say that they now understand what you wanted to say.
1346Update your patches to clarify the points reviewers had trouble with,
1347and prepare your v2; the words you used to explain your v1 to answer
1348reviewers' questions may be useful thing to use. Your goal is to make
1349your v2 clear enough so that it becomes unnecessary for you to give the
1350same explanation to the next person who reads it.
1351
1352If you are going to push back on a comment, be polite and explain why you feel
1353your original is better; be prepared that the reviewer may still disagree with
1354you, and the rest of the community may weigh in on one side or the other. As
1355with all code reviews, it's important to keep an open mind to doing something a
1356different way than you originally planned; other reviewers have a different
1357perspective on the project than you do, and may be thinking of a valid side
1358effect which had not occurred to you. It is always okay to ask for clarification
1359if you aren't sure why a change was suggested, or what the reviewer is asking
1360you to do.
1361
1362Make sure your email client has a plaintext email mode and it is turned on; the
1363Git list rejects HTML email. Please also follow the mailing list etiquette
1364outlined in the
1365https://kernel.googlesource.com/pub/scm/git/git/+/todo/MaintNotes[Maintainer's
1366Note], which are similar to etiquette rules in most open source communities
1367surrounding bottom-posting and inline replies.
1368
1369When you're making changes to your code, it is cleanest - that is, the resulting
1370commits are easiest to look at - if you use `git rebase -i` (interactive
1371rebase). Take a look at this
1372https://www.oreilly.com/library/view/git-pocket-guide/9781449327507/ch10.html[overview]
1373from O'Reilly. The general idea is to modify each commit which requires changes;
1374this way, instead of having a patch A with a mistake, a patch B which was fine
1375and required no upstream reviews in v1, and a patch C which fixes patch A for
1376v2, you can just ship a v2 with a correct patch A and correct patch B. This is
1377changing history, but since it's local history which you haven't shared with
1378anyone, that is okay for now! (Later, it may not make sense to do this; take a
1379look at the section below this one for some context.)
1380
1381[[after-approval]]
1382=== After Review Approval
1383
1384The Git project has four integration branches: `seen`, `next`, `master`, and
1385`maint`. Your change will be placed into `seen` fairly early on by the maintainer
1386while it is still in the review process; from there, when it is ready for wider
1387testing, it will be merged into `next`. Plenty of early testers use `next` and
1388may report issues. Eventually, changes in `next` will make it to `master`,
1389which is typically considered stable. Finally, when a new release is cut,
1390`maint` is used to base bugfixes onto. As mentioned at the beginning of this
1391document, you can read `Documents/SubmittingPatches` for some more info about
1392the use of the various integration branches.
1393
1394Back to now: your code has been lauded by the upstream reviewers. It is perfect.
1395It is ready to be accepted. You don't need to do anything else; the maintainer
1396will merge your topic branch to `next` and life is good.
1397
1398However, if you discover it isn't so perfect after this point, you may need to
1399take some special steps depending on where you are in the process.
1400
1401If the maintainer has announced in the "What's cooking in git.git" email that
1402your topic is marked for `next` - that is, that they plan to merge it to `next`
1403but have not yet done so - you should send an email asking the maintainer to
1404wait a little longer: "I've sent v4 of my series and you marked it for `next`,
1405but I need to change this and that - please wait for v5 before you merge it."
1406
1407If the topic has already been merged to `next`, rather than modifying your
1408patches with `git rebase -i`, you should make further changes incrementally -
1409that is, with another commit, based on top of the maintainer's topic branch as
1410detailed in https://github.com/gitster/git. Your work is still in the same topic
1411but is now incremental, rather than a wholesale rewrite of the topic branch.
1412
1413The topic branches in the maintainer's GitHub are mirrored in GitGitGadget, so
1414if you're sending your reviews out that way, you should be sure to open your PR
1415against the appropriate GitGitGadget/Git branch.
1416
1417If you're using `git send-email`, you can use it the same way as before, but you
1418should generate your diffs from `<topic>..<mybranch>` and base your work on
1419`<topic>` instead of `master`.