-Copyright (C) 2006-2014 Free Software Foundation, Inc.
-See end for license conditions.
+This file contains information on Emacs developer processes.
+For information on contributing to Emacs as a non-developer, see
+(info "(emacs)Contributing") or
+http://www.gnu.org/software/emacs/manual/html_node/emacs/Contributing.html
- Contributing to Emacs
+* Information for Emacs Developers.
-Emacs is a collaborative project and we encourage contributions from
-anyone and everyone. If you want to contribute in the way that will
-help us most, we recommend (1) fixing reported bugs and (2)
-implementing the feature ideas in etc/TODO. However, if you think of
-new features to add, please suggest them too -- we might like your
-idea. Porting to new platforms is also useful, when there is a new
-platform, but that is not common nowadays.
-
-For documentation on Emacs (to understand how to implement your
-desired change), refer to:
-
-- the Emacs Manual
- http://www.gnu.org/software/emacs/manual/emacs.html
- (info "(Emacs)Top")
-
-- the Emacs Lisp Reference Manual
- http://www.gnu.org/software/emacs/manual/elisp.html
- (info "(elisp)Top")
-
-- http://www.gnu.org/software/emacs
-
-- http://www.emacswiki.org/
-
-There are many ways to contribute to Emacs:
-
-- implement a new feature, and submit a patch (see "Submitting
- Patches" below).
-
-- answer questions on the Emacs user mailing list
- https://lists.gnu.org/mailman/listinfo/help-gnu-emacs
-
-- write documentation, either on the wiki, or in the Emacs source
- repository (see "Submitting Patches" below)
-
-- find and report bugs; use M-x report-emacs-bug
-
-- check if existing bug reports are fixed in newer versions of Emacs
- http://debbugs.gnu.org/cgi/pkgreport.cgi?which=pkg&data=emacs
-
-- develop a package that works with Emacs, and publish it on your own
- or in Gnu ELPA (see admin/notes/elpa).
-
-Here are some style and legal conventions for contributors to Emacs:
-
-
-* Coding Standards
-
-Contributed code should follow the GNU Coding Standards
-(http://www.gnu.org/prep/standards/ - may also be available in info on
-your system).
-
-If it doesn't, we'll need to find someone to fix the code before we
-can use it.
-
-Emacs has additional style and coding conventions:
-
-- the "Tips" Appendix in the Emacs Lisp Reference
- http://www.gnu.org/software/emacs/manual/html_node/elisp/Tips.html
- (info "(elisp)Tips").
-
-- Avoid using `defadvice' or `eval-after-load' for Lisp code to be
- included in Emacs.
-
-- Remove all trailing whitespace in all source and text files.
-
-- Emacs has no convention on whether to use tabs in source code;
- please don't change whitespace in the files you edit.
-
-- Use ?\s instead of ? in Lisp code for a space character.
-
-* Copyright Assignment
-
-The FSF (Free Software Foundation) is the copyright holder for GNU Emacs.
-The FSF is a nonprofit with a worldwide mission to promote computer
-user freedom and to defend the rights of all free software users.
-For general information, see the website http://www.fsf.org/ .
-
-Generally speaking, for non-trivial contributions to GNU Emacs we
-require that the copyright be assigned to the FSF. For the reasons
-behind this, see: http://www.gnu.org/licenses/why-assign.html .
-
-Copyright assignment is a simple process. Residents of some countries
-can do it entirely electronically. We can help you get started, and
-answer any questions you may have (or point you to the people with the
-answers), at the emacs-devel@gnu.org mailing list.
-
-(Please note: general discussion about why some GNU projects ask
-for a copyright assignment is off-topic for emacs-devel.
-See gnu-misc-discuss instead.)
-
-A copyright disclaimer is also a possibility, but we prefer an assignment.
-Note that the disclaimer, like an assignment, involves you sending
-signed paperwork to the FSF (simply saying "this is in the public domain"
-is not enough). Also, a disclaimer cannot be applied to future work, it
-has to be repeated each time you want to send something new.
-
-We can accept small changes (roughly, fewer than 15 lines) without
-an assignment. This is a cumulative limit (e.g. three separate 5 line
-patches) over all your contributions.
-
-* Getting the Source Code
-
-The current working version of the Emacs source code is stored in a
-git repository on the Savannah web site
-(http://savannah.gnu.org/projects/emacs). It is important to write
-your patch based on the current working version. If you start from an
-older version, your patch may be outdated (so that maintainers will
-have a hard time applying it), or changes in Emacs may have made your
-patch unnecessary.
-
-After you have downloaded the repository source, you should read the file
-INSTALL.REPO for build instructions (they differ to some extent from a
-normal build).
-
-* Submitting Patches
-
-Every patch must have several pieces of information before we
-can properly evaluate it.
-
-When you have all these pieces, bundle them up in a mail message and
-send it to the developers. Sending it to bug-gnu-emacs@gnu.org
-(which is the bug/feature list) is recommended, because that list
-is coupled to a tracking system that makes it easier to locate patches.
-If your patch is not complete and you think it needs more discussion,
-you might want to send it to emacs-devel@gnu.org instead. If you
-revise your patch, send it as a followup to the initial topic.
-
-** Description
-
-For bug fixes, a description of the bug and how your patch fixes it.
-
-For new features, a description of the feature and your implementation.
+An "Emacs Developer" is someone who contributes a lot of code or
+documentation to the Emacs repository. Generally, they have write
+access to the Emacs git repository on Savannah
+https://savannah.gnu.org/git/?group=emacs.
-** ChangeLog
+** Write access to the Emacs repository.
-A ChangeLog entry as plaintext (separate from the patch).
+Once you become a frequent contributor to Emacs, we can consider
+giving you write access to the version-control repository. Request
+access on the emacs-devel@gnu.org mailing list. Also, be sure to
+subscribe to the emacs-devel@gnu.org mailing list and include the
+"emacs-announce" topic, so that you get the announcements about
+feature freeze and other important events.
-See the existing ChangeLog files for format and content. Note that,
-unlike some other projects, we do require ChangeLogs for
-documentation, i.e. Texinfo files.
+** Using the Emacs repository
-Ref: "Change Log Concepts" node of the GNU Coding Standards Info
-Manual, for how to write good log entries.
-http://www.gnu.org/prep/standards/html_node/Change-Log-Concepts.html
+Emacs uses Git for the source code repository.
-When using git, commit messages should use ChangeLog format, with a
-single short line explaining the change, then an empty line, then
-unindented ChangeLog entries. (Essentially, a commit message should
-be a duplicate of what the patch adds to the ChangeLog files. We are
-planning to automate this better, to avoid the duplication.) You can
-use the Emacs functions log-edit-add-to-changelog or
-log-edit-insert-changelog to ease this process.
+See http://www.emacswiki.org/emacs/GitQuickStartForEmacsDevs to get
+started, and http://www.emacswiki.org/emacs/GitForEmacsDevs for more
+advanced information.
-** The patch itself.
+Alternately, see admin/notes/git-workflow.
-If you are accessing the Emacs repository, make sure your copy is
-up-to-date (e.g. with 'git pull'). You can commit your changes
-to a private branch and generate a patch from the master version
-by using
- git format-patch master
-Or you can leave your changes uncommitted and use
- git diff
-With no repository, you can use
- diff -u OLD NEW
+If committing changes written by someone else, make the commit in
+their name, not yours. Git distinguishes between the author
+and the committer; use the --author option on the commit command to
+specify the actual author; the committer defaults to you.
-** Mail format.
+** Commit messages
-We prefer to get the patches as plain text, either inline (be careful
-your mail client does not change line breaks) or as MIME attachments.
+Emacs development no longer stores descriptions of new changes in
+ChangeLog files. Instead, a single ChangeLog file is generated from
+the commit messages when a release is prepared. So changes you commit
+should not touch any of the ChangeLog files in the repository, but
+instead should contain the log entries in the commit message. Here is
+an example of a commit message (indented):
-** Please reread your patch before submitting it.
+ Deactivate shifted region
-** Do not mix changes.
+ Do not silently extend a region that is not highlighted;
+ this can happen after a shift (Bug#19003).
+ * doc/emacs/mark.texi (Shift Selection): Document the change.
+ * lisp/window.el (handle-select-window):
+ * src/frame.c (Fhandle_switch_frame, Fselected_frame):
+ Deactivate the mark.
-If you send several unrelated changes together, we will ask you to
-separate them so we can consider each of the changes by itself.
+Below are some rules and recommendations for formatting commit
+messages:
-** Do not make formatting changes.
+- Start with a single unindented summary line explaining the change;
+ do not end this line with a period. If that line starts with a
+ semi-colon and a space "; ", the log message will be ignored when
+ generating the ChangeLog file. Use this for minor commits that do
+ not need separate ChangeLog entries, such as changes in etc/NEWS.
-Making cosmetic formatting changes (indentation, etc) makes it harder
-to see what you have really changed.
+- After the summary line, there should be an empty line, then
+ unindented ChangeLog entries.
+- Limit lines in commit messages to 78 characters, unless they consist
+ of a single word of at most 140 characters; this is enforced by a
+ commit hook. It's nicer to limit the summary line to 50 characters;
+ this isn't enforced. If the change can't be summarized so briefly,
+ add a paragraph after the empty line and before the individual file
+ descriptions.
-* Supplemental information for Emacs Developers.
+- If only a single file is changed, the summary line can be the normal
+ file first line (starting with the asterisk). Then there is no
+ individual files section.
-An "Emacs Developer" is someone who contributes a lot of code or
-documentation to the Emacs repository.
+- If the commit has more than one author, the commit message should
+ contain separate lines to mention the other authors, like the
+ following:
-** Write access to the Emacs repository.
+ Co-authored-by: Joe Schmoe <j.schmoe@example.org>
-Once you become a frequent contributor to Emacs, we can consider
-giving you write access to the version-control repository. Request
-access on the emacs-devel@gnu.org mailing list.
+- If the commit is a tiny change that is exempt from copyright paperwork,
+ the commit message should contain a separate line like the following:
-** Using the Emacs repository
+ Copyright-paperwork-exempt: yes
-Emacs uses git for the source code repository.
+- The commit message should contain "Bug#NNNNN" if it is related to
+ bug number NNNNN in the debbugs database. This string is often
+ parenthesized, as in "(Bug#19003)".
-See http://www.emacswiki.org/emacs/GitQuickStartForEmacsDevs to get
-started, and http://www.emacswiki.org/emacs/GitForEmacsDevs for more
-advanced information.
+- Commit messages should contain only printable UTF-8 characters.
-Alternately, see admin/notes/git-workflow.
+- Commit messages should not contain the "Signed-off-by:" lines that
+ are used in some other projects.
-If committing changes written by someone else, make the ChangeLog
-entry in their name, not yours. git distinguishes between the author
-and the committer; use the --author option on the commit command to
-specify the actual author; the committer defaults to you.
+- Any lines of the commit message that start with "; " are omitted
+ from the generated ChangeLog.
-** Changelog notes
+- Explaining the rationale for a design choice is best done in comments
+ in the source code. However, sometimes it is useful to describe just
+ the rationale for a change; that can be done in the commit message
+ between the summary line and the file entries.
- Emacs generally follows the GNU coding standards when it comes to
ChangeLogs:
- http://www.gnu.org/prep/standards/html_node/Change-Logs.html . One
- exception is that we still sometimes quote `like-this' (as the
- standards used to recommend) rather than 'like-this' (as they do
- now), because `...' is so widely used elsewhere in Emacs.
+ http://www.gnu.org/prep/standards/html_node/Change-Logs.html or
+ "(info (standards)Change Logs"). One exception is that we still
+ sometimes quote `like-this' (as the standards used to recommend)
+ rather than 'like-this' (as they do now), because `...' is so widely
+ used elsewhere in Emacs.
+
+- Some of the rules in the GNU coding standards section 5.2
+ "Commenting Your Work" also apply to ChangeLog entries: they must be
+ in English, and be complete sentences starting with a capital and
+ ending with a period (except the summary line should not end in a
+ period).
+
+ They are preserved indefinitely, and have a reasonable chance of
+ being read in the future, so it's better that they have good
+ presentation.
-- There are multiple ChangeLogs in the emacs source; roughly one per
- high-level directory. The ChangeLog entry for a commit belongs in the
- lowest ChangeLog that is higher than or at the same level as any file
- changed by the commit.
+- Use the present tense; describe "what the change does", not "what
+ the change did".
- Preferred form for several entries with the same content:
- * help.el (view-lossage):
- * kmacro.el (kmacro-edit-lossage):
- * edmacro.el (edit-kbd-macro): Fix docstring, lossage is now 300 keys.
+ * lisp/help.el (view-lossage):
+ * lisp/kmacro.el (kmacro-edit-lossage):
+ * lisp/edmacro.el (edit-kbd-macro): Fix docstring, lossage is now 300.
(Rather than anything involving "ditto" and suchlike.)
-- In ChangeLog files, there is no standard or recommended way to
- identify revisions.
+- There is no standard or recommended way to identify revisions in
+ ChangeLog entries. Using Git SHA1 values limits the usability of
+ the references to Git, and will become much less useful if Emacs
+ switches to a different VCS. So we recommend against that.
One way to identify revisions is by quoting their summary line.
Another is with an action stamp - an RFC3339 date followed by !
followed by the committer's email - for example,
- "2014-01-16T05:43:35Z!esr@thyrsus.com". Often, "my previous commit"
+ "2014-01-16T05:43:35Z!esr@thyrsus.com". Often, "my previous commit"
will suffice.
-- There is no need to make separate change log entries for files such
- as NEWS, MAINTAINERS, and FOR-RELEASE, or to indicate regeneration
- of files such as 'configure'. "There is no need" means you don't
- have to, but you can if you want to.
+- There is no need to mention files such as NEWS and MAINTAINERS, or
+ to indicate regeneration of files such as 'configure', in the
+ ChangeLog entry. "There is no need" means you don't have to, but
+ you can if you want to.
+
+** Generating ChangeLog entries
+
+- You can use various Emacs functions to ease the process of writing
+ ChangeLog entries; see (info "(emacs)Change Log Commands") or
+ http://www.gnu.org/software/emacs/manual/html_node/emacs/Change-Log-Commands.html.
+
+- If you use Emacs VC, one way to format ChangeLog entries is to create
+ a top-level ChangeLog file manually, and update it with 'C-x 4 a' as
+ usual. Do not register the ChangeLog file under git; instead, use
+ 'C-c C-a' to insert its contents into into your *vc-log* buffer.
+ Or if 'log-edit-hook' includes 'log-edit-insert-changelog' (which it
+ does by default), they will be filled in for you automatically.
-** branches
+- Alternatively, you can use the vc-dwim command to maintain commit
+ messages. When you create a source directory, run the shell command
+ 'git-changelog-symlink-init' to create a symbolic link from
+ ChangeLog to .git/c/ChangeLog. Edit this ChangeLog via its symlink
+ with Emacs commands like 'C-x 4 a', and commit the change using the
+ shell command 'vc-dwim --commit'. Type 'vc-dwim --help' for more.
+
+** Branches
Development normally takes places on the trunk.
Sometimes specialized features are developed on separate branches
Development is discussed on the emacs-devel mailing list.
-Sometime before the release of a new major version of Emacs a "feature
-freeze" is imposed on the trunk, to prepare for creating a release
-branch. No new features may be added to the trunk after this point,
-until the release branch is created. This freeze is announced on the
-emacs-devel mailing list, and not anywhere else.
-
The trunk branch is named "master" in git; release branches are named
"emacs-nn" where "nn" is the major version.
-You must follow emacs-devel to know exactly what kinds of changes are
-allowed on what branch at any time. Announcements about the freeze
-(and other important events) will contain "ANNOUNCE" in the subject.
-
If you are fixing a bug that exists in the current release, be sure to
commit it to the release branch; it will be merged to the master
branch later.
However, if you know that the change will be difficult to merge to the
trunk (eg because the trunk code has changed a lot), you can apply the
-change to both trunk and branch yourself. Indicate in the release
-branch commit log that there is no need to merge the commit to the
-trunk; start the commit message with "Backport:". gitmerge.el will
-then exclude that commit from the merge to trunk.
+change to both trunk and branch yourself. It could also happen that a
+change is cherry-picked from master to the release branch, and so
+doesn't need to be merged back. In these cases, indicate in the
+release branch commit log that there is no need to merge the commit to
+the trunk; start the commit message with "Backport:". gitmerge.el
+will then exclude that commit from the merge to trunk.
** Other process information
-See all the files in admin/notes/* . In particular, see
-admin/notes/newfile, see admin/notes/repo.
-
** Emacs Mailing lists.
Discussion about Emacs development takes place on emacs-devel@gnu.org.
You can subscribe to the mailing lists, or see the list archives,
by following links from http://savannah.gnu.org/mail/?group=emacs .
+To email a patch you can use a shell command like 'git format-patch -1'
+to create a file, and then attach the file to your email. This nicely
+packages the patch's commit message and changes. To send just one
+such patch without additional remarks, you can use a command like
+'git send-email --to=bug-gnu-emacs@gnu.org 0001-DESCRIPTION.patch'.
+
+** Issue tracker (a.k.a. "bug tracker")
+
+The Emacs issue tracker is at http://debbugs.gnu.org/. The form
+presented by that page allows to view bug reports and search the
+database for bugs matching several criteria. Messages posted to the
+bug-gnu-emacs@gnu.org mailing list, mentioned above, are recorded by
+the tracker with the corresponding bugs/issues.
+
+GNU ELPA has a 'debbugs' package that allows accessing the tracker
+database from Emacs.
+
** Document your changes.
Any change that matters to end-users should have an entry in etc/NEWS.
-Think about whether your change requires updating the documentation
-(both manuals and doc-strings). If you know it does not, mark the NEWS
-entry with "---". If you know that *all* the necessary documentation
-updates have been made, mark the entry with "+++". Otherwise do not mark it.
+Doc-strings should be updated together with the code.
+
+Think about whether your change requires updating the manuals. If you
+know it does not, mark the NEWS entry with "---". If you know
+that *all* the necessary documentation updates have been made, mark
+the entry with "+++". Otherwise do not mark it.
+
+Please see (info "(elisp)Documentation Tips") or
+https://www.gnu.org/software/emacs/manual/html_node/elisp/Documentation-Tips.html
+for more specific tips on Emacs's doc style. Use 'checkdoc' to check
+for documentation errors before submitting a patch.
+
+** Test your changes.
+
+Please test your changes before committing them or sending them to the
+list. If possible, add a new test along with any bug fix or new
+functionality you commit (of course, some changes cannot be easily
+tested).
+
+Emacs uses ERT, Emacs Lisp Regression Testing, for testing. See (info
+"(ert)") or https://www.gnu.org/software/emacs/manual/html_node/ert/
+for more information on writing and running tests.
+
+To run tests on the entire Emacs tree, run "make check" from the
+top-level directory. Most tests are in the directory
+"test/automated". From the "test/automated" directory, run "make
+<filename>" to run the tests for <filename>.el(c). See
+"test/automated/Makefile" for more information.
** Understanding Emacs Internals.
The best way to understand Emacs Internals is to read the code,
but the nodes "Tips" and "GNU Emacs Internals" in the Appendix
-of the Emacs Lisp Reference Manual may also help.
+of the Emacs Lisp Reference Manual may also help. Some source files,
+such as xdisp.c, have large commentaries describing the design and
+implementation in more detail.
The file etc/DEBUG describes how to debug Emacs bugs.
+*** Non-ASCII characters in Emacs files
+
+If you introduce non-ASCII characters into Emacs source files, it is a
+good idea to add a 'coding' cookie to the file to state its encoding.
+Please use the UTF-8 encoding unless it cannot do the job for some
+good reason. As of Emacs 24.4, it is no longer necessary to have
+explicit 'coding' cookies in *.el files if they are encoded in UTF-8,
+but other files need them even if encoded in UTF-8. However, if
+an *.el file is intended for use with older Emacs versions (e.g. if
+it's also distributed via ELPA), having an explicit encoding
+specification is still a good idea.
+
+*** Useful files in the admin/ directory
+
+See all the files in admin/notes/* . In particular, see
+admin/notes/newfile, see admin/notes/repo.
+
+The file admin/MAINTAINERS records the areas of interest of frequent
+Emacs contributors. If you are making changes in one of the files
+mentioned there, it is a good idea to consult the person who expressed
+an interest in that file, and/or get his/her feedback for the changes.
+If you are a frequent contributor and have interest in maintaining
+specific files, please record those interests in that file, so that
+others could be aware of that.
+
+*** git vs rename
+
+Git does not explicitly represent a file renaming; it uses a percent
+changed heuristic to deduce that a file was renamed. So if you are
+planning to make extensive changes to a file after renaming it (or
+moving it to another directory), you should:
+
+- create a feature branch
+
+- commit the rename without any changes
+
+- make other changes
+
+- merge the feature branch to trunk, _not_ squashing the commits into
+ one. The commit message on this merge should summarize the renames
+ and all the changes.
+
\f
This file is part of GNU Emacs.