1============================= 2Code Reviews with Phabricator 3============================= 4 5.. contents:: 6 :local: 7 8If you prefer to use a web user interface for code reviews, you can now submit 9your patches for Clang and LLVM at `LLVM's Phabricator`_ instance. 10 11While Phabricator is a useful tool for some, the relevant -commits mailing list 12is the system of record for all LLVM code review. The mailing list should be 13added as a subscriber on all reviews, and Phabricator users should be prepared 14to respond to free-form comments in mail sent to the commits list. 15 16Sign up 17------- 18 19To get started with Phabricator, navigate to `http://reviews.llvm.org`_ and 20click the power icon in the top right. You can register with a GitHub account, 21a Google account, or you can create your own profile. 22 23Make *sure* that the email address registered with Phabricator is subscribed 24to the relevant -commits mailing list. If you are not subscribed to the commit 25list, all mail sent by Phabricator on your behalf will be held for moderation. 26 27Note that if you use your Subversion user name as Phabricator user name, 28Phabricator will automatically connect your submits to your Phabricator user in 29the `Code Repository Browser`_. 30 31Requesting a review via the command line 32---------------------------------------- 33 34Phabricator has a tool called *Arcanist* to upload patches from 35the command line. To get you set up, follow the 36`Arcanist Quick Start`_ instructions. 37 38You can learn more about how to use arc to interact with 39Phabricator in the `Arcanist User Guide`_. 40 41Requesting a review via the web interface 42----------------------------------------- 43 44The tool to create and review patches in Phabricator is called 45*Differential*. 46 47Note that you can upload patches created through various diff tools, 48including git and svn. To make reviews easier, please always include 49**as much context as possible** with your diff! Don't worry, Phabricator 50will automatically send a diff with a smaller context in the review 51email, but having the full file in the web interface will help the 52reviewer understand your code. 53 54To get a full diff, use one of the following commands (or just use Arcanist 55to upload your patch): 56 57* ``git diff -U999999 other-branch`` 58* ``svn diff --diff-cmd=diff -x -U999999`` 59 60To upload a new patch: 61 62* Click *Differential*. 63* Click *+ Create Diff*. 64* Paste the text diff or browse to the patch file. Click *Create Diff*. 65* Leave the Repository field blank. 66* Leave the drop down on *Create a new Revision...* and click *Continue*. 67* Enter a descriptive title and summary. The title and summary are usually 68 in the form of a :ref:`commit message <commit messages>`. 69* Add reviewers and mailing 70 lists that you want to be included in the review. If your patch is 71 for LLVM, add llvm-commits as a Subscriber; if your patch is for Clang, 72 add cfe-commits. 73* Leave the Repository and Project fields blank. 74* Click *Save*. 75 76To submit an updated patch: 77 78* Click *Differential*. 79* Click *+ Create Diff*. 80* Paste the updated diff or browse to the updated patch file. Click *Create Diff*. 81* Select the review you want to from the *Attach To* dropdown and click 82 *Continue*. 83* Leave the Repository and Project fields blank. 84* Add comments about the changes in the new diff. Click *Save*. 85 86Reviewing code with Phabricator 87------------------------------- 88 89Phabricator allows you to add inline comments as well as overall comments 90to a revision. To add an inline comment, select the lines of code you want 91to comment on by clicking and dragging the line numbers in the diff pane. 92When you have added all your comments, scroll to the bottom of the page and 93click the Submit button. 94 95You can add overall comments in the text box at the bottom of the page. 96When you're done, click the Submit button. 97 98Phabricator has many useful features, for example allowing you to select 99diffs between different versions of the patch as it was reviewed in the 100*Revision Update History*. Most features are self descriptive - explore, and 101if you have a question, drop by on #llvm in IRC to get help. 102 103Note that as e-mail is the system of reference for code reviews, and some 104people prefer it over a web interface, we do not generate automated mail 105when a review changes state, for example by clicking "Accept Revision" in 106the web interface. Thus, please type LGTM into the comment box to accept 107a change from Phabricator. 108 109Committing a change 110------------------- 111 112Arcanist can manage the commit transparently. It will retrieve the description, 113reviewers, the ``Differential Revision``, etc from the review and commit it to the repository. 114 115:: 116 117 arc patch D<Revision> 118 arc commit --revision D<Revision> 119 120 121When committing an LLVM change that has been reviewed using 122Phabricator, the convention is for the commit message to end with the 123line: 124 125:: 126 127 Differential Revision: <URL> 128 129where ``<URL>`` is the URL for the code review, starting with 130``http://reviews.llvm.org/``. 131 132Note that Arcanist will add this automatically. 133 134This allows people reading the version history to see the review for 135context. This also allows Phabricator to detect the commit, close the 136review, and add a link from the review to the commit. 137 138Abandoning a change 139------------------- 140 141If you decide you should not commit the patch, you should explicitly abandon 142the review so that reviewers don't think it is still open. In the web UI, 143scroll to the bottom of the page where normally you would enter an overall 144comment. In the drop-down Action list, which defaults to "Comment," you should 145select "Abandon Revision" and then enter a comment explaining why. Click the 146Submit button to finish closing the review. 147 148Status 149------ 150 151Please let us know whether you like it and what could be improved! We're still 152working on setting up a bug tracker, but you can email klimek-at-google-dot-com 153and chandlerc-at-gmail-dot-com and CC the llvm-dev mailing list with questions 154until then. We also could use help implementing improvements. This sadly is 155really painful and hard because the Phabricator codebase is in PHP and not as 156testable as you might like. However, we've put exactly what we're deploying up 157on an `llvm-reviews GitHub project`_ where folks can hack on it and post pull 158requests. We're looking into what the right long-term hosting for this is, but 159note that it is a derivative of an existing open source project, and so not 160trivially a good fit for an official LLVM project. 161 162.. _LLVM's Phabricator: http://reviews.llvm.org 163.. _`http://reviews.llvm.org`: http://reviews.llvm.org 164.. _Code Repository Browser: http://reviews.llvm.org/diffusion/ 165.. _Arcanist Quick Start: https://secure.phabricator.com/book/phabricator/article/arcanist_quick_start/ 166.. _Arcanist User Guide: https://secure.phabricator.com/book/phabricator/article/arcanist/ 167.. _llvm-reviews GitHub project: https://github.com/r4nt/llvm-reviews/ 168