- Overview
- Ways to contribute
- How to become a contributor to Carbon
- Style
- License
- Workflow
- Acknowledgements
Thank you for your interest in contributing to Carbon! There are many ways to contribute, and we appreciate all of them. If you have questions, please feel free to ask on Discord or GitHub.
Everyone who contributes to Carbon is expected to:
- Read and follow the Code of Conduct. We expect everyone in our community to be welcoming, helpful, and respectful.
- Ensure you have signed the Contributor License Agreement (CLA). We need this to cover some legal bases.
We also encourage anyone interested in contributing to check out all the information here in our contributing guide, especially the guidelines and philosophy for contributions
If you're looking for a quick way to contribute, commenting on proposals is a way to provide proposal authors with a breadth of feedback. The "leads questions" label has questions the community is looking for a decision on. The list of open proposals will have more mature proposals that are nearing a decision. For more about the difference, see the evolution process.
When giving feedback, please keep comments positive and constructive. Our goal is to use community discussion to improve proposals and assist authors.
If you have ideas for Carbon, we encourage you to discuss it with the community, and potentially prepare a proposal for it. Ultimately, any changes or improvements to Carbon will need to turn into a proposal and go through our evolution process.
If you do start working on a proposal, keep in mind that this requires a time investment to discuss the idea with the community, get it reviewed, and eventually implemented. A good starting point is to read through the evolution process. We encourage discussing the idea early, before even writing a proposal, and the process explains how to do that.
Eventually, we will also be working toward a reference implementation of Carbon, and are very interested in folks joining in to help us with it.
As Carbon's design and eventually implementation begin to take shape, we'll inevitably end up with plenty of bugs. Helping us triage, analyze, and address them is always a great way to get involved. See open issues on GitHub.
Some issues have been marked as "good first issues". These are intended to be a good place to start contributing.
We'd love to accept your documentation, pull requests, and comments! Before we can accept them, we need you to cover some legal bases.
Please fill out either the individual or corporate CLA.
- If you are an individual contributing to spec discussions or writing original source code and you're sure you own the intellectual property, then you'll need to sign an individual CLA.
- If you work for a company that wants to allow you to contribute your work, then you'll need to sign a corporate CLA.
Follow either of the two links above to access the appropriate CLA and instructions for how to sign and return it. Once we receive it, we'll be able to accept your documents, comments and pull requests.
NOTE: Only original content from you and other people who have signed the CLA can be accepted as Carbon contributions: this covers GitHub (including both code and discussion), Google Docs, and Discord.
Initially, Carbon is bootstrapping using Google's CLA. We are planning to create an open source foundation and transfer all Carbon-related rights to it; our goal is for the foundation setup to be similar to other open source projects, such as LLVM or Kubernetes.
We use a few systems for collaboration which contributors should be aware of.
Before using these systems, everyone must sign the CLA. They are all governed by the Code of Conduct.
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The GitHub carbon-language organization is used for our repositories.
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Discord is used for chat.
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A shared Google Drive is used for all of our Google Docs, particularly proposal drafts.
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Google Calendar is used for meeting invites and project reminders. Contributors may add calendar entries for meetings added to discuss details. Standard entries are:
- The weekly sync, where contributors are welcome.
- Open discussions, which are unstructured meeting slots used for discussing proposals, tooling, and other Carbon topics based on who attends.
Our collaboration systems are all viewable publicly, and most can be joined without particular requests. However, some require extra permissions, such as editing Google Docs, joining meetings, or some details of the proposal process.
When requesting any of the following access, please provide a reason for the access. All requests require a signed CLA.
- Google Docs/Calendar commenter access:
join group
- Grants commenter access to Carbon Language documents, as well as the ability to view Calendar events.
- Google Docs/Calendar contributor access:
join group
- Grants edit access to Carbon Language documents, as well as the ability to edit Calendar events.
- GitHub Label/project contributor access:
ask on #access-requests
- Don't forget to mention your GitHub username.
- Used by the proposal process.
If you simply want to chime in on GitHub or Discord, none of this is needed. If you're interested in joining meetings, ask for commenter access. If you're trying to write proposals, both types of contributor access will help.
Please see our contribution tool documentation for information on setting up a git client for Carbon development, as well as helpful tooling that will ease the contribution process. For example, pre-commit is used to simplify code review.
All documents and pull requests must be consistent with the guidelines and follow the Carbon documentation and coding styles.
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For both documentation and code:
- When the Carbon team accepts new documentation or features, to Carbon, by default they take on the maintenance burden. This means they'll weigh the benefit of each contribution against the cost of maintaining it.
- The appropriate style is applied.
- The license is present in all contributions.
- Code review is used to improve the
correctness, clarity, and consistency of all contributions.
- Please avoid rebasing PRs after receiving comments; it can break viewing of the comments in files.
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For documentation:
- All documentation is written for clarity and readability. Beyond fixing spelling and grammar, this also means content is worded to be accessible to a broad audience.
- Substantive changes to Carbon follow the evolution process. Pull requests are only sent after the documentation changes have been accepted by the reviewing team.
- Typos or other minor fixes that don't change the meaning of a document do not need formal review, and are often handled directly as a pull request.
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For code:
- New features should have a documented design that has been approved through the evolution process. This includes modifications to preexisting designs.
- Bug fixes and mechanical improvements don't need this.
- All new features include unit tests, as they help to (a) document and validate concrete usage of the feature and its edge cases, and (b) guard against future breaking changes to lower the maintenance cost.
- Bug fixes also generally include unit tests, because the presence of bugs usually indicates insufficient test coverage.
- Unit tests must pass with the changes.
- If some tests fail for unrelated reasons, we wait until they're fixed. It helps to contribute a fix!
- Code changes should be made with API compatibility and evolvability in mind.
- Keep in mind that code contribution guidelines are incomplete while we start work on Carbon, and may change later.
Changes to Carbon documentation follow the Google developer documentation style guide.
Markdown files should additionally use Prettier for formatting.
Other style points to be aware of are:
- Whereas the Google developer documentation style guide
says to use an em dash
(
text—text), we are using a double-hyphen with surrounding spaces (text -- text). We are doing this because we frequently read Markdown with fixed-width fonts where em dashes are not clearly visible. - Prefer the term "developers" when talking about people who would write Carbon code. We expect the Carbon's community to include people who think of themselves using many titles, including software developers, software engineers, systems engineers, reliability engineers, data scientists, computer scientists, programmers, and coders. We're using "developers" to succinctly cover the variety of titles.
If you're not sure what style to use, please ask on Discord or GitHub.
A license is required at the top of all documents and files.
Google Docs all use this template. It puts the license at the top of every page if printed.
Markdown files always have at the top:
# DOC TITLE
<!--
Part of the Carbon Language project, under the Apache License v2.0 with LLVM
Exceptions. See /LICENSE for license information.
SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-->
For example, see the top of CONTRIBUTING.md's raw content.
Every file type uses a variation on the same license text ("Apache-2.0 WITH LLVM-exception") with similar formatting. If you're not sure what text to use, please ask on Discord or GitHub.
Carbon repositories all follow a common pull-request workflow for landing changes. It is a trunk-based development model that emphasizes small, incremental changes and preserves a simple linear history.
Carbon's Contributing guidelines are based on TensorFlow and Flutter guidelines. Many thanks to these communities for their help in providing a basis.