Firefox Contributors' Quick Reference
=====================================

Some parts of this process, including cloning and compiling, can take a long time even on modern hardware.
If at any point you get stuck, please don't hesitate to ask at `https://chat.mozilla.org <https://chat.mozilla.org>`__
in the `#introduction <https://chat.mozilla.org/#/room/#introduction:mozilla.org>`__ channel.

Clone the sources
-----------------

You can use either mercurial or git. `Mercurial <https://www.mercurial-scm.org/downloads>`__ is the canonical version control system.

.. code-block:: shell

    $ hg clone https://hg.mozilla.org/mozilla-central/

For git, see the `git cinnabar documentation <https://github.com/glandium/git-cinnabar/wiki/Mozilla:-A-git-workflow-for-Gecko-development>`__

The clone can take from 40 minutes to two hours (depending on your connection) and
the repository should be less than 5GB (~ 20GB after the build).

If you have any network connection issues and cannot clone with command, try :ref:`Mercurial bundles <Mercurial bundles>`.

:ref:`More information <Mercurial Overview>`

Install dependencies (non-Windows)
----------------------------------

Firefox provides a mechanism to install all dependencies; in the source tree:

.. code-block:: shell

     $ ./mach bootstrap

The default options are recommended.
If you're not planning to write C++ or Rust code, select :ref:`Artifact Mode <Understanding Artifact Builds>`
and follow the instructions at the end of the bootstrap for creating a mozconfig file.

More information :ref:`for Linux <Building Firefox On Linux>` and :ref:`for MacOS <Building Firefox On MacOS>`

Windows dependencies
--------------------

#. You need 64-bit version of Windows 7 or later.
#. Download and install `Visual Studio Community Edition. <https://visualstudio.microsoft.com/downloads/>`__
#. Finally download the `MozillaBuild Package. <https://ftp.mozilla.org/pub/mozilla.org/mozilla/libraries/win32/MozillaBuildSetup-Latest.exe>`__ Installation directory should be:

    .. code-block:: shell

        $ c:\mozilla-build\

#. Before moving on to the next steps, make sure to fulfill the :ref:`Windows prerequisites <Building Firefox On Windows>`

.. note::

    All the commands of this tutorial must be run in the shell provided with the MozillaBuild Package (start-shell.bat)

:ref:`More information <Building Firefox On Windows>`

To build & run
--------------

Once all the dependencies have been installed, run:

.. code-block:: shell

     $ ./mach build

which will check for dependencies and start the build.
This will take a while; a few minutes to a few hours depending on your hardware.

.. note::

    The default build is a compiled build with optimizations. Check out the
    :ref:`mozconfig file documentation <Configuring Build Options>`
    to see other build options. If you don't plan to change C++ or Rust code,
    an :ref:`artifact build <Understanding Artifact Builds>` will be faster.

To run it:

.. code-block:: shell

     $ ./mach run

:ref:`More information about Linux <Building Firefox On Linux>` / :ref:`More information about MacOS <Building Firefox On MacOS>`


To write a patch
----------------

Make the changes you need in the codebase. You can look up UI text in `Searchfox <https://searchfox.org>`__ to find the right file.

Then:

.. code-block:: shell

    # Mercurial
    $ hg commit

    # Git
    $ git commit

.. _Commit message:

The commit message should look like:

.. code-block::

    Bug xxxx - Short description of your change. r?reviewer

    Optionally, a longer description of the change.

**Make sure you include the bug number and at least one reviewer (or reviewer group) in this format.**

To :ref:`find a reviewer or a review group <Getting reviews>`, the easiest way is to run
``hg log <modified-file>`` (or ``git log <modified-file>``, if
you're using git) on the relevant files, and look who usually is
reviewing the actual changes (ie not reformat, renaming of variables, etc).


To visualize your patch in the repository, run:

.. code-block:: shell

    # Mercurial
    $ hg wip

    # Git
    $ git show

:ref:`More information on how to work with stack of patches <Working with stack of patches Quick Reference>`

:ref:`More information <Mercurial Overview>`

To make sure the change follows the coding style
------------------------------------------------

To detect coding style violations, use mach lint:

.. code-block:: shell

    $ ./mach lint path/to/the/file/or/directory/you/changed

    # To get the autofix, add --fix:
    $ ./mach lint path/to/the/file/or/directory/you/changed --fix

:ref:`More information <Code quality>`

To test a change locally
------------------------

To run the tests, use mach test with the path. However, it isn’t
always easy to parse the results.

.. code-block:: shell

    $ ./mach test dom/serviceworkers

`More information <https://developer.mozilla.org/docs/Mozilla/QA/Automated_testing>`__

To test a change remotely
-------------------------

Running all the tests for Firefox takes a very long time and requires multiple
operating systems with various configurations. To build Firefox and run its
tests on continuous integration servers (CI), two commands are available:

.. code-block:: shell

    $ ./mach try chooser

To select jobs running a fuzzy search:

.. code-block:: shell

    $ ./mach try fuzzy

From `Treeherder <https://treeherder.mozilla.org/>`__ (our continuous integration system), it is also possible to attach new jobs. As every review has
a try CI run associated, it makes this work easier. See :ref:`attach-job-review` for
more information.

.. note::

    This requires `level 1 commit access <https://www.mozilla.org/about/governance/policies/commit/access-policy/>`__.

    You can ask your reviewer to submit the patch for you if you don't have that
    level of access.

:ref:`More information <Try Server>`


To submit a patch
-----------------

To submit a patch for review, we use a tool called `moz-phab <https://pypi.org/project/MozPhab/>`__.
To install it, run:

.. code-block:: shell

     $ ./mach install-moz-phab

Once you want to submit your patches (make sure you :ref:`use the right commit message <Commit message>`), run:

.. code-block:: shell

     $ moz-phab

It will publish all the currently applied patches to Phabricator and inform the reviewer.

If you wrote several patches on top of each other:

.. code-block:: shell

    $ moz-phab submit <first_revision>::<last_revision>

`More
information <https://moz-conduit.readthedocs.io/en/latest/phabricator-user.html>`__

To update a submitted patch
---------------------------

It is rare that a reviewer will accept the first version of patch. Moreover,
as the code review bot might suggest some improvements, changes to your patch
may be required.

Run:

.. code-block:: shell

   # Mercurial
   $ hg commit --amend

   # Git
   $ git commit --amend

After amending the patch, you will need to submit it using moz-phab again.

If you wrote many changes, you can squash or edit commits with the
command:

.. code-block:: shell

   # Mercurial
   $ hg histedit

   # Git
   $ git rebase -i

The submission step is the same as for the initial patch.

:ref:`More information on how to work with stack of patches <Working with stack of patches Quick Reference>`

Retrieve new changes from the repository
----------------------------------------

To pull changes from the repository, run:

.. code-block:: shell

   # Mercurial
   $ hg pull --rebase

   # Git
   $ git pull --rebase

To push a change in the code base
---------------------------------

Once the change has been accepted and you've fixed any remaining issues
the reviewer identified, add the *Check-in Needed* tag to the review
(use the *Edit Revision* option on the top right).

The landing procedure will automatically close the review and the bug.

:ref:`More information <How to submit a patch>`

Contributing to GeckoView
-------------------------

Note that the GeckoView setup and contribution processes are different from those of Firefox;
GeckoView setup and contribution docs live in `geckoview.dev <https://geckoview.dev>`__.

More documentation about contribution
-------------------------------------

https://developer.mozilla.org/docs/Mozilla/Developer_guide/Introduction

https://mozilla-version-control-tools.readthedocs.io/en/latest/devguide/contributing.html

https://moz-conduit.readthedocs.io/en/latest/phabricator-user.html