Contributing to V8

The information on this page explains how to contribute to V8. Be sure to read the whole thing before sending us a contribution.

Get the code #

See Checking out the V8 source code.

Before you contribute #

Ask on V8’s mailing list for guidance #

Before you start working on a larger V8 contribution, you should get in touch with us first through the V8 contributor mailing list so we can help out and possibly guide you. Coordinating up front makes it much easier to avoid frustration later on.

Sign the CLA #

Before we can use your code you have to sign the Google Individual Contributor License Agreement, which you can do online. This is mainly because you own the copyright to your changes, even after your contribution becomes part of our codebase, so we need your permission to use and distribute your code. We also need to be sure of various other things, for instance that you’ll tell us if you know that your code infringes on other people’s patents. You don’t have to do this until after you’ve submitted your code for review and a member has approved it, but you will have to do it before we can put your code into our codebase.

Contributions made by corporations are covered by a different agreement than the one above, the Software Grant and Corporate Contributor License Agreement.

Sign them online here.

Submit your code #

The source code of V8 follows the Google C++ Style Guide so you should familiarize yourself with those guidelines. Before submitting code you must pass all our tests, and have to successfully run the presubmit checks:

git cl presubmit

The presubmit script uses a linter from Google, It is part of depot_tools, and it must be in your PATH — so if you have depot_tools in your PATH, everything should just work.

Upload to V8’s codereview tool #

All submissions, including submissions by project members, require review. We use the same code-review tools and process as the Chromium project. In order to submit a patch, you need to get the depot_tools and follow these instructions on requesting a review (using your V8 workspace instead of a Chromium workspace).

Look out for breakage or regressions #

Once you have codereview approval, you can land your patch using the commit queue. It runs a bunch of tests and commits your patch if all tests pass. Once your change is committed, it is a good idea to watch the console until the bots turn green after your change, because the console runs a few more tests than the commit queue.