Copyright (C) 2006-2014 Free Software Foundation, Inc.
See end for license conditions.


			Contributing to Emacs

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.

** ChangeLog

A ChangeLog entry as plaintext (separate from the patch).

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.

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

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.

** The patch itself.

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

** Mail format.

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.

** Please reread your patch before submitting it.

** Do not mix changes.

If you send several unrelated changes together, we will ask you to
separate them so we can consider each of the changes by itself.

** Do not make formatting changes.

Making cosmetic formatting changes (indentation, etc) makes it harder
to see what you have really changed.


* Supplemental information for Emacs Developers.

An "Emacs Developer" is someone who contributes a lot of code or
documentation to the Emacs repository.

** Write access to the Emacs repository.

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.

** Using the Emacs repository

Emacs uses git for the source code repository.

See http://www.emacswiki.org/emacs/GitQuickStartForEmacsDevs to get
started, and http://www.emacswiki.org/emacs/GitForEmacsDevs for more
advanced information.

Alternately, see admin/notes/git-workflow.

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.

** Changelog notes

- 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.

- 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.

- 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.

  (Rather than anything involving "ditto" and suchlike.)

- In ChangeLog files, there is no standard or recommended way to
  identify revisions.

  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"
  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.

** branches

Development normally takes places on the trunk.
Sometimes specialized features are developed on separate branches
before possibly being merged to the trunk.

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.


** 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.

Bug reports and fixes, feature requests and implementations should be
sent to bug-gnu-emacs@gnu.org, the bug/feature list.  This is coupled
to the tracker at http://debbugs.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 .

** 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.

** 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.

The file etc/DEBUG describes how to debug Emacs bugs.


\f
This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
\f
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