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Diffstat (limited to 'Documentation/SubmittingPatches')
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diff --git a/Documentation/SubmittingPatches b/Documentation/SubmittingPatches index e409022..c647c7e 100644 --- a/Documentation/SubmittingPatches +++ b/Documentation/SubmittingPatches @@ -3,43 +3,101 @@ Submitting Patches == Guidelines -Here are some guidelines for people who want to contribute their code to this -software. There is also a link:MyFirstContribution.html[step-by-step tutorial] +Here are some guidelines for contributing back to this +project. There is also a link:MyFirstContribution.html[step-by-step tutorial] available which covers many of these same guidelines. -[[base-branch]] -=== Decide what to base your work on. - -In general, always base your work on the oldest branch that your -change is relevant to. - -* A bugfix should be based on `maint` in general. If the bug is not - present in `maint`, base it on `master`. For a bug that's not yet - in `master`, find the topic that introduces the regression, and - base your work on the tip of the topic. - -* A new feature should be based on `master` in general. If the new - feature depends on a topic that is in `seen`, but not in `master`, - base your work on the tip of that topic. - -* Corrections and enhancements to a topic not yet in `master` should - be based on the tip of that topic. If the topic has not been merged - to `next`, it's alright to add a note to squash minor corrections - into the series. - -* In the exceptional case that a new feature depends on several topics - not in `master`, start working on `next` or `seen` privately and send - out patches for discussion. Before the final merge, you may have to - wait until some of the dependent topics graduate to `master`, and - rebase your work. - -* Some parts of the system have dedicated maintainers with their own - repositories (see the section "Subsystems" below). Changes to - these parts should be based on their trees. - -To find the tip of a topic branch, run `git log --first-parent -master..seen` and look for the merge commit. The second parent of this -commit is the tip of the topic branch. +[[choose-starting-point]] +=== Choose a starting point. + +As a preliminary step, you must first choose a starting point for your +work. Typically this means choosing a branch, although technically +speaking it is actually a particular commit (typically the HEAD, or tip, +of the branch). + +There are several important branches to be aware of. Namely, there are +four integration branches as discussed in linkgit:gitworkflows[7]: + +* maint +* master +* next +* seen + +The branches lower on the list are typically descendants of the ones +that come before it. For example, `maint` is an "older" branch than +`master` because `master` usually has patches (commits) on top of +`maint`. + +There are also "topic" branches, which contain work from other +contributors. Topic branches are created by the Git maintainer (in +their fork) to organize the current set of incoming contributions on +the mailing list, and are itemized in the regular "What's cooking in +git.git" announcements. To find the tip of a topic branch, run `git log +--first-parent master..seen` and look for the merge commit. The second +parent of this commit is the tip of the topic branch. + +There is one guiding principle for choosing the right starting point: in +general, always base your work on the oldest integration branch that +your change is relevant to (see "Merge upwards" in +linkgit:gitworkflows[7]). What this principle means is that for the +vast majority of cases, the starting point for new work should be the +latest HEAD commit of `maint` or `master` based on the following cases: + +* If you are fixing bugs in the released version, use `maint` as the + starting point (which may mean you have to fix things without using + new API features on the cutting edge that recently appeared in + `master` but were not available in the released version). + +* Otherwise (such as if you are adding new features) use `master`. + + +NOTE: In exceptional cases, a bug that was introduced in an old +version may have to be fixed for users of releases that are much older +than the recent releases. `git describe --contains X` may describe +`X` as `v2.30.0-rc2-gXXXXXX` for the commit `X` that introduced the +bug, and the bug may be so high-impact that we may need to issue a new +maintenance release for Git 2.30.x series, when "Git 2.41.0" is the +current release. In such a case, you may want to use the tip of the +maintenance branch for the 2.30.x series, which may be available in the +`maint-2.30` branch in https://github.com/gitster/git[the maintainer's +"broken out" repo]. + +This also means that `next` or `seen` are inappropriate starting points +for your work, if you want your work to have a realistic chance of +graduating to `master`. They are simply not designed to be used as a +base for new work; they are only there to make sure that topics in +flight work well together. This is why both `next` and `seen` are +frequently re-integrated with incoming patches on the mailing list and +force-pushed to replace previous versions of themselves. A topic that is +literally built on top of `next` cannot be merged to `master` without +dragging in all the other topics in `next`, some of which may not be +ready. + +For example, if you are making tree-wide changes, while somebody else is +also making their own tree-wide changes, your work may have severe +overlap with the other person's work. This situation may tempt you to +use `next` as your starting point (because it would have the other +person's work included in it), but doing so would mean you'll not only +depend on the other person's work, but all the other random things from +other contributors that are already integrated into `next`. And as soon +as `next` is updated with a new version, all of your work will need to +be rebased anyway in order for them to be cleanly applied by the +maintainer. + +Under truly exceptional circumstances where you absolutely must depend +on a select few topic branches that are already in `next` but not in +`master`, you may want to create your own custom base-branch by forking +`master` and merging the required topic branches into it. You could then +work on top of this base-branch. But keep in mind that this base-branch +would only be known privately to you. So when you are ready to send +your patches to the list, be sure to communicate how you created it in +your cover letter. This critical piece of information would allow +others to recreate your base-branch on their end in order for them to +try out your work. + +Finally, note that some parts of the system have dedicated maintainers +with their own separate source code repositories (see the section +"Subsystems" below). [[separate-commits]] === Make separate commits for logically separate changes. @@ -71,8 +129,13 @@ Make sure that you have tests for the bug you are fixing. See [[tests]] When adding a new feature, make sure that you have new tests to show the feature triggers the new behavior when it should, and to show the -feature does not trigger when it shouldn't. After any code change, make -sure that the entire test suite passes. +feature does not trigger when it shouldn't. After any code change, +make sure that the entire test suite passes. When fixing a bug, make +sure you have new tests that break if somebody else breaks what you +fixed by accident to avoid regression. Also, try merging your work to +'next' and 'seen' and make sure the tests still pass; topics by others +that are still in flight may have unexpected interactions with what +you are trying to do in your topic. Pushing to a fork of https://github.com/git/git will use their CI integration to test your changes on Linux, Mac and Windows. See the @@ -103,6 +166,35 @@ run `git diff --check` on your changes before you commit. [[describe-changes]] === Describe your changes well. +The log message that explains your changes is just as important as the +changes themselves. Your code may be clearly written with in-code +comment to sufficiently explain how it works with the surrounding +code, but those who need to fix or enhance your code in the future +will need to know _why_ your code does what it does, for a few +reasons: + +. Your code may be doing something differently from what you wanted it + to do. Writing down what you actually wanted to achieve will help + them fix your code and make it do what it should have been doing + (also, you often discover your own bugs yourself, while writing the + log message to summarize the thought behind it). + +. Your code may be doing things that were only necessary for your + immediate needs (e.g. "do X to directories" without implementing or + even designing what is to be done on files). Writing down why you + excluded what the code does not do will help guide future developers. + Writing down "we do X to directories, because directories have + characteristic Y" would help them infer "oh, files also have the same + characteristic Y, so perhaps doing X to them would also make sense?". + Saying "we don't do the same X to files, because ..." will help them + decide if the reasoning is sound (in which case they do not waste + time extending your code to cover files), or reason differently (in + which case, they can explain why they extend your code to cover + files, too). + +The goal of your log message is to convey the _why_ behind your +change to help future developers. + The first line of the commit message should be a short description (50 characters is the soft limit, see DISCUSSION in linkgit:git-commit[1]), and should skip the full stop. It is also conventional in most cases to @@ -117,7 +209,9 @@ files you are modifying to see the current conventions. [[summary-section]] The title sentence after the "area:" prefix omits the full stop at the -end, and its first word is not capitalized unless there is a reason to +end, and its first word is not capitalized (the omission +of capitalization applies only to the word after the "area:" +prefix of the title) unless there is a reason to capitalize it other than because it is the first word in the sentence. E.g. "doc: clarify...", not "doc: Clarify...", or "githooks.txt: improve...", not "githooks.txt: Improve...". But "refs: HEAD is also @@ -135,6 +229,13 @@ The body should provide a meaningful commit message, which: . alternate solutions considered but discarded, if any. +[[present-tense]] +The problem statement that describes the status quo is written in the +present tense. Write "The code does X when it is given input Y", +instead of "The code used to do Y when given input X". You do not +have to say "Currently"---the status quo in the problem statement is +about the code _without_ your change, by project convention. + [[imperative-mood]] Describe your changes in imperative mood, e.g. "make xyzzy do frotz" instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy @@ -144,15 +245,28 @@ without external resources. Instead of giving a URL to a mailing list archive, summarize the relevant points of the discussion. [[commit-reference]] -If you want to reference a previous commit in the history of a stable -branch, use the format "abbreviated hash (subject, date)", like this: + +There are a few reasons why you may want to refer to another commit in +the "more stable" part of the history (i.e. on branches like `maint`, +`master`, and `next`): + +. A commit that introduced the root cause of a bug you are fixing. + +. A commit that introduced a feature that you are enhancing. + +. A commit that conflicts with your work when you made a trial merge + of your work into `next` and `seen` for testing. + +When you reference a commit on a more stable branch (like `master`, +`maint` and `next`), use the format "abbreviated hash (subject, +date)", like this: .... Commit f86a374 (pack-bitmap.c: fix a memleak, 2015-03-30) noticed that ... .... -The "Copy commit summary" command of gitk can be used to obtain this +The "Copy commit reference" command of gitk can be used to obtain this format (with the subject enclosed in a pair of double-quotes), or this invocation of `git show`: @@ -241,9 +355,21 @@ If you like, you can put extra tags at the end: patch after a detailed analysis. . `Tested-by:` is used to indicate that the person applied the patch and found it to have the desired effect. - -You can also create your own tag or use one that's in common usage -such as "Thanks-to:", "Based-on-patch-by:", or "Mentored-by:". +. `Co-authored-by:` is used to indicate that people exchanged drafts + of a patch before submitting it. +. `Helped-by:` is used to credit someone who suggested ideas for + changes without providing the precise changes in patch form. +. `Mentored-by:` is used to credit someone with helping develop a + patch as part of a mentorship program (e.g., GSoC or Outreachy). +. `Suggested-by:` is used to credit someone with suggesting the idea + for a patch. + +While you can also create your own trailer if the situation warrants it, we +encourage you to instead use one of the common trailers in this project +highlighted above. + +Only capitalize the very first letter of tags, i.e. favor +"Signed-off-by" over "Signed-Off-By" and "Acked-by:" over "Acked-By". [[git-tools]] === Generate your patch using Git tools out of your commits. @@ -259,9 +385,14 @@ Please make sure your patch does not add commented out debugging code, or include any extra files which do not relate to what your patch is trying to achieve. Make sure to review your patch after generating it, to ensure accuracy. Before -sending out, please make sure it cleanly applies to the `master` -branch head. If you are preparing a work based on "next" branch, -that is fine, but please mark it as such. +sending out, please make sure it cleanly applies to the starting point you +have chosen in the "Choose a starting point" section. + +NOTE: From the perspective of those reviewing your patch, the `master` +branch is the default expected starting point. So if you have chosen a +different starting point, please communicate this choice in your cover +letter. + [[send-patches]] === Sending your patches. @@ -274,8 +405,8 @@ mailing list{security-ml}, instead of the public mailing list. Learn to use format-patch and send-email if possible. These commands are optimized for the workflow of sending patches, avoiding many ways -your existing e-mail client that is optimized for "multipart/*" mime -type e-mails to corrupt and render your patches unusable. +your existing e-mail client (often optimized for "multipart/*" MIME +type e-mails) might render your patches unusable. People on the Git mailing list need to be able to read and comment on the changes you are submitting. It is important for @@ -328,6 +459,18 @@ an explanation of changes between each iteration can be kept in Git-notes and inserted automatically following the three-dash line via `git format-patch --notes`. +[[the-topic-summary]] +*This is EXPERIMENTAL*. + +When sending a topic, you can propose a one-paragraph summary that +should appear in the "What's cooking" report when it is picked up to +explain the topic. If you choose to do so, please write a 2-5 line +paragraph that will fit well in our release notes (see many bulleted +entries in the Documentation/RelNotes/* files for examples), and make +it the first paragraph of the cover letter. For a single-patch +series, use the space between the three-dash line and the diffstat, as +described earlier. + [[attachment]] Do not attach the patch as a MIME attachment, compressed or not. Do not let your e-mail client send quoted-printable. Do not let @@ -365,7 +508,10 @@ Security mailing list{security-ml-ref}. Send your patch with "To:" set to the mailing list, with "cc:" listing people who are involved in the area you are touching (the `git contacts` command in `contrib/contacts/` can help to -identify them), to solicit comments and reviews. +identify them), to solicit comments and reviews. Also, when you made +trial merges of your topic to `next` and `seen`, you may have noticed +work by others conflicting with your changes. There is a good possibility +that these people may know the area you are touching well. :current-maintainer: footnote:[The current maintainer: gitster@pobox.com] :git-ml: footnote:[The mailing list: git@vger.kernel.org] @@ -391,7 +537,10 @@ repositories. - `gitk-git/` comes from Paul Mackerras's gitk project: - git://ozlabs.org/~paulus/gitk + git://git.ozlabs.org/~paulus/gitk + + Those who are interested in improving gitk can volunteer to help Paul + maintain it, cf. <YntxL/fTplFm8lr6@cleo>. - `po/` comes from the localization coordinator, Jiang Xin: @@ -431,7 +580,7 @@ help you find out who they are. In any time between the (2)-(3) cycle, the maintainer may pick it up from the list and queue it to `seen`, in order to make it easier for -people play with it without having to pick up and apply the patch to +people to play with it without having to pick up and apply the patch to their trees themselves. [[patch-status]] @@ -445,10 +594,10 @@ their trees themselves. master). * Read the Git mailing list, the maintainer regularly posts messages - entitled "What's cooking in git.git" and "What's in git.git" giving + entitled "What's cooking in git.git" giving the status of various proposed changes. -== GitHub CI[[GHCI]]] +== GitHub CI[[GHCI]] With an account at GitHub, you can use GitHub CI to test your changes on Linux, Mac and Windows. See @@ -463,13 +612,14 @@ Follow these steps for the initial setup: After the initial setup, CI will run whenever you push new changes to your fork of Git on GitHub. You can monitor the test state of all your -branches here: https://github.com/<Your GitHub handle>/git/actions/workflows/main.yml +branches here: `https://github.com/<Your GitHub handle>/git/actions/workflows/main.yml` -If a branch did not pass all test cases then it is marked with a red -cross. In that case you can click on the failing job and navigate to -"ci/run-build-and-tests.sh" and/or "ci/print-test-failures.sh". You -can also download "Artifacts" which are tarred (or zipped) archives -with test data relevant for debugging. +If a branch does not pass all test cases then it will be marked with a +red +x+, instead of a green check. In that case, you can click on the +failing job and navigate to "ci/run-build-and-tests.sh" and/or +"ci/print-test-failures.sh". You can also download "Artifacts" which +are zip archives containing tarred (or zipped) archives with test data +relevant for debugging. Then fix the problem and push your fix to your GitHub fork. This will trigger a new CI build to ensure all tests pass. @@ -477,7 +627,7 @@ trigger a new CI build to ensure all tests pass. [[mua]] == MUA specific hints -Some of patches I receive or pick up from the list share common +Some of the patches I receive or pick up from the list share common patterns of breakage. Please make sure your MUA is set up properly not to corrupt whitespaces. @@ -561,7 +711,7 @@ message to an external program, and this is a handy way to drive `git am`. However, if the message is MIME encoded, what is piped into the program is the representation you see in your `*Article*` buffer after unwrapping MIME. This is often not what -you would want for two reasons. It tends to screw up non ASCII +you would want for two reasons. It tends to screw up non-ASCII characters (most notably in people's names), and also whitespaces (fatal in patches). Running "C-u g" to display the message in raw form before using "|" to run the pipe can work |