neovim/CONTRIBUTING.md

Contributing to Neovim

Getting started

• Help us review open pull requests!
• Look for entry-level issues to work on.
  • Documentation improvements are also much appreciated.
• Look at Waffle to see who is working on what issues.
• If needed, refer to the wiki for guidance.

Reporting problems

Before reporting an issue, see the following wiki articles:

• Troubleshooting
• Frequently asked questions

If your issue isn't mentioned there:

• Verify that it hasn't already been reported.
• If not already running the latest version of Neovim, update to it to see if your problem persists.
• If you're experiencing compile or runtime warnings/failures, try searching for the error message(s) you received (if any) on Neovim's issue tracker.
  • For build issues, see Troubleshooting#build-issues.
  • For runtime issues, see Troubleshooting#runtime-issues. If your issue isn't mentioned there, try to reproduce your it using nvim with the smallest possible vimrc (or none at all via nvim -u NONE), to rule out bugs in plugins you're using. If you're using a plugin manager, comment out your plugins, then add them back in one by one.

Include as much detail as possible; we generally need to know:

• What operating system you're using.
• Which version of Neovim you're using. To get this, run nvim --version from a shell, or run :version from inside nvim.
• Whether the bug is present in Vim (not Neovim), and if so which version of Vim. It's fine to report Vim bugs on the Neovim bug tracker, but it saves everyone time if we know from the start that the bug is not a regression caused by Neovim.
• This isn't required, but what commit introduced the issue for you. You can use git bisect for this.

Submitting contributions

• Make it clear in the issue tracker what you are working on.
• Be descriptive in your pull request description: what is it for, why is it needed, etc.
• Do not make cosmetic changes to unrelated files in the same pull request. This creates noise, making reviews harder to do. If your text editor strips all trailing whitespace in a file when you edit it, disable it.

Tagging in the issue tracker

When submitting pull requests (commonly referred to as "PRs"), include one of the following tags prepended to the title:

• [WIP] - Work In Progress: the PR will change, so while there is no immediate need for review, the submitter still might appreciate it.
• [RFC] - Request For Comment: the PR needs reviewing and/or comments.
• [RDY] - Ready: the PR has been reviewed by at least one other person and has no outstanding issues.

Assuming the above criteria has been met, feel free to change your PR's tag yourself, as opposed to waiting for a contributor to do it for you.

Branching & history

• Do not work on your PR on the master branch, use a feature branch instead.
• Rebase your feature branch onto (upstream) master before opening the PR.
• Keep up to date with changes in (upstream) master so your PR is easy to merge.
• Try to actively tidy your history: combine related commits with interactive rebasing, separate monolithic commits, etc. If your PR is still [WIP], feel free to force-push to your feature branch to tidy your history.

For code pull requests

Testing

We are unlikely to merge your PR if the Travis build fails:

• Travis builds are compiled with the -Werror flag, so if your PR introduces any compiler warnings then the Travis build will fail.
• If any tests fail, the Travis build will fail. See Building Neovim#running-tests for information on running tests locally. Tests passing locally doesn't guarantee they'll pass in the Travis build, as different compilers and platforms will be used.
• Travis runs Valgrind for the GCC/Linux build, but you may also do so locally by running the following from a shell: VALGRIND=1 make test

Coding style

We have a style guide that all new code should follow. However, large portions of the existing Vim codebase violate it to some degree, and fixing them would increase merge conflicts and add noise to git blame.

Weigh those costs when making cosmetic changes. In general, avoid pull requests dominated by style changes, but feel free to fix up lines that you happen to be modifying anyway. Fix anything that looks outright barbarous, but otherwise prefer to leave things as they are.

For new code, run make lint (which runs clint.py) to detect style errors. Make sure that the file(s) you intend to be linted are not in clint-ignored-files.txt. It's not perfect, so some warnings may be false positives/negatives. To have clint.py ignore certain cases, put // NOLINT at the end of the line.

We also provide a configuration file for clang-format, which can be used to format code according to the style guidelines. Be aware that this formatting method might need user supervision. To have clang-format ignore certain line ranges, use the following special comments:

int formatted_code;
// clang-format off
    void    unformatted_code  ;
// clang-format on
    void formatted_code_again;

Commit guidelines

The purpose of these guidelines is to make reviews easier and make the VCS logs more valuable.

• Try to keep the first line under 72 characters.
• If necessary, include further description after a blank line.
  • Don't make the description too verbose by including obvious things, but don't spare clarifications for anything that may be not so obvious. Some commit messages are pages long, and that's fine if there's no better place for those comments to live.
  • Recommended: Prefix logically-related commits with a consistent identifier in each commit message. For already used identifiers, see the commit history for the respective file(s) you're editing. For example, the following commits are related by task (Introduce nvim namespace) and sub-task (Contrib YCM).
    Introduce nvim namespace: Contrib YCM: Fix style issues
Introduce nvim namespace: Contrib YCM: Fix build dir calculation
    • Sub-tasks can be activity-oriented (doing different things on the same area) or scope-oriented (doing the same thing in different areas).
  • Granularity helps, but it's conceptual size that matters, not extent size.
• Use the imperative voice: "Fix bug" rather than "Fixed bug" or "Fixes bug."

Reviewing pull requests

Using a checklist during reviews is highly recommended, so we provide one at the wiki. If you think it could be improved, feel free to edit it.

Reviewing can be done on GitHub, but you may find it easier to do locally. Using hub, you can do the following to create a new branch with the contents of a pull request, such as #1820:

hub checkout https://github.com/neovim/neovim/pull/1820

Use git log -p master..FETCH_HEAD to list all commits in the feature branch which aren't in the master branch; -p shows each commit's diff. To show the whole surrounding function of a change as context, use the -W argument as well.

You may find it easier to instead use an interactive program for code reviews, such as tig.