neovim/CONTRIBUTING.md

Contributing to Neovim

Getting started

If you want to help but don't know where to start, here are some low-risk/isolated tasks:

• Merge a Vim patch.
• Try a complexity:low issue.
• Fix clang-scan, coverity, and PVS warnings.

Developer guidelines

• Nvim developers should read :help dev-help.
• External UI developers should read :help dev-ui.

Reporting problems

• Check the FAQ.
• Search existing issues (including closed!)
• Update Neovim to the latest version to see if your problem persists.
• If you're using a plugin manager, comment out your plugins, then add them back in one by one, to narrow down the cause of the issue.
• Crash reports which include a stacktrace are 10x more valuable.
• Bisecting to the cause of a regression often leads to an immediate fix.

Pull requests ("PRs")

• To avoid duplicate work, create a [WIP] pull request as soon as possible.
• Avoid cosmetic changes to unrelated files in the same commit: noise makes reviews take longer.
• Use a feature branch instead of the master branch.
• Use a rebase workflow for small PRs.
  • After addressing review comments, it's fine to rebase and force-push.
• Use a merge workflow for big, high-risk PRs.
  • Merge master into your PR when there are conflicts or when master introduces breaking changes.
  • Use the ri git alias:

    [alias]
    ri = "!sh -c 't=\"${1:-master}\" ; s=\"${2:-HEAD}\" ; if git merge-base --is-ancestor \"$t\" \"$s\" ; then o=\"$t\" ; else mb=\"$(git merge-base \"$t\" \"$s\")\" ; if test \"x$mb\" = x ; then o=\"$t\" ; else lm=\"$(git log -n1 --merges \"$t..$s\" --pretty=%H)\" ; if test \"x$lm\" = x ; then o=\"$mb\" ; else o=\"$lm\" ; fi ; fi ; fi ; [ $# -gt 0 ] && shift ; [ $# -gt 0 ] && shift ; git rebase --interactive \"$o\" \"$@\"' -"
    

    This avoids unnecessary rebases yet still allows you to combine related commits, separate monolithic commits, etc.
  • Do not edit commits that come before the merge commit.
• During a squash/fixup, use exec make -C build unittest between each pick/edit/reword.

Stages: WIP, RFC, RDY

Pull requests have three stages: [WIP] (Work In Progress), [RFC] (Request For Comment) and [RDY] (Ready).

• Untagged PRs are assumed to be [RFC], i.e. you are requesting a review.
• Prepend [WIP] to the PR title if you are not requesting feedback and the work is still in flux.
• Prepend [RDY] to the PR title if you are done with the PR and are only waiting on it to be merged.

For example, a typical workflow is:

1. You open a [WIP] PR where the work is not ready for feedback, you just want to let others know what you are doing.
2. Once the PR is ready for review, you replace [WIP] in the title with [RFC]. You may add fix up commits to address issues that come up during review.
3. Once the PR is ready for merging, you rebase/squash your work appropriately and then replace [RFC] in the title with [RDY].

Commit messages

Follow commit message hygiene to make reviews easier and to make the VCS/git logs more valuable.

• Try to keep the first line under 72 characters.
• Prefix the commit subject with a scope: doc:, test:, foo.c:, runtime:, ...
  • For commits that contain only style/lint changes, a single-word subject line is preferred: style or lint.
• A blank line must separate the subject from the description.
• Use the imperative voice: "Fix bug" rather than "Fixed bug" or "Fixes bug."

Automated builds (CI)

Each pull request must pass the automated builds (travis CI and quickbuild).

• CI builds are compiled with -Werror, so if your PR introduces any compiler warnings, the build will fail.
• If any tests fail, the build will fail. See Building Neovim#running-tests to run tests locally. Passing locally doesn't guarantee passing the CI build, because of the different compilers and platforms tested against.
• CI runs ASan and other analyzers. To run valgrind locally: VALGRIND=1 make test
• The lint build (#3174) checks modified lines and their immediate neighbors. This is to encourage incrementally updating the legacy style to meet our style guidelines.
  • A single word (lint or style) is sufficient as the subject line of a commit that contains only style changes.
• How to investigate QuickBuild failures

QuickBuild uses this invocation:

mkdir -p build/${params.get("buildType")} \
&& cd build/${params.get("buildType")} \
&& cmake -G "Unix Makefiles" -DBUSTED_OUTPUT_TYPE=TAP -DCMAKE_BUILD_TYPE=${params.get("buildType")}
-DTRAVIS_CI_BUILD=ON ../.. && ${node.getAttribute("make", "make")}
VERBOSE=1 nvim unittest-prereqs functionaltest-prereqs

Coverity

Coverity runs against the master build. If you want to view the defects, just request access at the Contributor level. An Admin will grant you permission.

Use this commit-message format for coverity fixes:

coverity/<id>: <description of what fixed the defect>

where <id> is the Coverity ID (CID). For example see #804.

PVS-Studio

Run scripts/pvscheck.sh to check the codebase with PVS Studio.

Reviewing

To help review pull requests, start with this checklist.

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