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 [good first issue](../../labels/good%20first%20issue) or [complexity:low] issue. - Fix bugs found by [Clang](#clang-scan-build), [PVS](#pvs-studio) or [Coverity](#coverity). Reporting problems ------------------ - [Check the FAQ][wiki-faq]. - [Search existing issues][github-issues] (including closed!) - Update Neovim to the latest version to see if your problem persists. - Disable plugins incrementally, to narrow down the cause of the issue. - When reporting a crash, [include a stacktrace](https://github.com/neovim/neovim/wiki/FAQ#backtrace-linux). - Use [ASAN/UBSAN](#clang-sanitizers-asan-and-ubsan) to get detailed errors for segfaults and undefined behavior. - [Bisect][git-bisect] to the cause of a regression, if you are able. This is _extremely_ helpful. - Check `$NVIM_LOG_FILE`, if it exists. - Include `cmake --system-information` for build-related issues. Developer guidelines -------------------- - Read `:help dev` if you are working on Nvim core. - Read `:help dev-ui` if you are developing a UI. - Read `:help dev-api-client` if you are developing an API client. - Install `ninja` for faster builds of Nvim. ``` sudo apt-get install ninja-build make distclean make # Nvim build system uses ninja automatically, if available. ``` - [Improve documentation][wiki-contribute-help] Pull requests (PRs) --------------------- - To avoid duplicate work, create a `[WIP]` pull request as soon as possible. - Your PR must include **test coverage.** See [test/README.md][run-tests]. - Avoid cosmetic changes to unrelated files in the same commit. - Use a [feature branch][git-feature-branch] instead of the master branch. - Use a **rebase workflow** for small PRs. - After addressing review comments, it's fine to rebase and force-push. - Use a **merge workflow** for big, high-risk PRs. - Merge `master` into your PR when there are conflicts or when master introduces breaking changes. - Use the `ri` git alias: ``` [alias] ri = "!sh -c 't=\"${1:-master}\"; s=\"${2:-HEAD}\"; mb=\"$(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; test $# -gt 0 && shift; test $# -gt 0 && shift; git rebase --interactive \"$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). 1. `[RFC]` is assumed by default, **do not** put "RFC" in the PR title (it adds noise to merge commit messages). 2. Add `[WIP]` to the PR title if you are _not_ requesting feedback and the work is still in flux. 3. Add `[RDY]` to the PR title if you are _done_ and only waiting on merge. ### Commit messages Follow the [convential commits guidelines][conventional_commits] to *make reviews easier* and to make the VCS/git logs more valuable. The general structure of a commit message is as follows: ``` ([optional scope]): [optional body] [optional footer(s)] ``` - **Prefix the commit subject with a _type_:** `doc:`, `test:` `runtime:`, ... - Subject line for commits with only style/lint changes can be a single word: `style` or `lint`. - **Add the optional scope following if possible:** `(lsp)`, `(treesitter)`, `(multigrid)`, ... - Try to keep the first line under 72 characters. - A blank line must separate the subject from the description. - Breaking changes must be indicated at the very beginning of the footer or body section of a commit. A breaking change must consist of the uppercase text BREAKING CHANGE, followed by a colon, a space, and a description of what has changed about the API. - Check your commit message for spelling and grammatical mistakes. - Use the _imperative voice_: "Fix bug" rather than "Fixed bug" or "Fixes bug." ### Automated builds (CI) Each pull request must pass the automated builds on [Travis CI], [sourcehut] and [AppVeyor]. - CI builds are compiled with [`-Werror`][gcc-warnings], so compiler warnings will fail the build. - If any tests fail, the build will fail. See [test/README.md#running-tests][run-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` - To run Clang ASan/UBSan locally: `CC=clang make CMAKE_FLAGS="-DCLANG_ASAN_UBSAN=ON"` - The [lint](#lint) build checks modified lines _and their immediate neighbors_, to encourage incrementally updating the legacy style to meet our [style](#style). (See [#3174][3174] for background.) - CI for freebsd and openbsd runs on [sourcehut]. - To get a backtrace on freebsd (after connecting via ssh): ```sh sudo pkg install tmux # If you want tmux. lldb build/bin/nvim -c nvim.core # To get a full backtrace: # 1. Rebuild with debug info. rm -rf nvim.core build gmake CMAKE_BUILD_TYPE=RelWithDebInfo CMAKE_EXTRA_FLAGS="-DCI_BUILD=ON -DMIN_LOG_LEVEL=3" nvim # 2. Run the failing test to generate a new core file. TEST_FILE=test/functional/foo.lua gmake functionaltest lldb build/bin/nvim -c nvim.core ``` ### Clang scan-build View the [Clang report] to see potential bugs found by the Clang [scan-build](https://clang-analyzer.llvm.org/scan-build.html) analyzer. - Search the Neovim commit history to find examples: ``` git log --oneline --no-merges --grep clang ``` - To verify a fix locally, run `scan-build` like this: ``` rm -rf build/ scan-build --use-analyzer=/usr/bin/clang make ``` ### PVS-Studio View the [PVS report](https://neovim.io/doc/reports/pvs/PVS-studio.html.d/) to see potential bugs found by [PVS Studio](https://www.viva64.com/en/pvs-studio/). - Use this format for commit messages (where `{id}` is the PVS warning-id)): ``` PVS/V{id}: {description} ``` - Search the Neovim commit history to find examples: ``` git log --oneline --no-merges --grep PVS ``` - Try `./scripts/pvscheck.sh` to run PVS locally. ### Coverity [Coverity](https://scan.coverity.com/projects/neovim-neovim) runs against the master build. To view the defects, just request access; you will be approved. - Use this format for commit messages (where `{id}` is the CID (Coverity ID); ([example](https://github.com/neovim/neovim/pull/804))): ``` coverity/{id}: {description} ``` - Search the Neovim commit history to find examples: ``` git log --oneline --no-merges --grep coverity ``` ### Clang sanitizers (ASAN and UBSAN) ASAN/UBSAN can be used to detect memory errors and other common forms of undefined behavior at runtime in debug builds. To build neovim with sanitizers enabled, use ``` rm -rf build && CMAKE_EXTRA_FLAGS="-DCMAKE_C_COMPILER=clang -DCLANG_ASAN_UBSAN=1" make ``` When running neovim, use ``` UBSAN_OPTIONS=print_stacktrace=1 ASAN_OPTIONS=log_path=/tmp/nvim_asan nvim args... ``` If neovim exits unexpectedly, check `/tmp/nvim_asan.{PID}` (or your preferred `log_path`) for log files with error messages. Coding ------ ### Lint You can run the linter locally by: make lint The lint step downloads the [master error list] and excludes them, so only lint errors related to the local changes are reported. You can lint a single file (but this will _not_ exclude legacy errors): ./src/clint.py src/nvim/ops.c ### Style The repo includes a `.clang-format` config file which (mostly) matches the [style-guide]. You can use `clang-format` to format code with the `gq` operator in Nvim: if !empty(findfile('.clang-format', ';')) setlocal formatprg=clang-format\ -style=file endif ### Navigate - Use **[universal-ctags](https://github.com/universal-ctags/ctags).** ("Exuberant ctags", the typical `ctags` binary provided by your distro, is unmaintained and won't recognize many function signatures in Neovim source.) - Explore the source code [on the web](https://sourcegraph.com/github.com/neovim/neovim). Reviewing --------- To help review pull requests, start with [this checklist][review-checklist]. Reviewing can be done on GitHub, but you may find it easier to do locally. Using [`hub`][hub], you can create a new branch with the contents of a pull request, e.g. [#1820][1820]: hub checkout https://github.com/neovim/neovim/pull/1820 Use [`git log -p master..FETCH_HEAD`][git-history-filtering] 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. [gcc-warnings]: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html [git-bisect]: http://git-scm.com/book/en/v2/Git-Tools-Debugging-with-Git [git-feature-branch]: https://www.atlassian.com/git/tutorials/comparing-workflows [git-history-filtering]: https://www.atlassian.com/git/tutorials/git-log/filtering-the-commit-history [git-history-rewriting]: http://git-scm.com/book/en/v2/Git-Tools-Rewriting-History [git-rebasing]: http://git-scm.com/book/en/v2/Git-Branching-Rebasing [github-issues]: https://github.com/neovim/neovim/issues [1820]: https://github.com/neovim/neovim/pull/1820 [hub]: https://hub.github.com/ [conventional_commits]: https://www.conventionalcommits.org [style-guide]: http://neovim.io/develop/style-guide.xml [ASan]: http://clang.llvm.org/docs/AddressSanitizer.html [run-tests]: https://github.com/neovim/neovim/blob/master/test/README.md#running-tests [wiki-faq]: https://github.com/neovim/neovim/wiki/FAQ [review-checklist]: https://github.com/neovim/neovim/wiki/Code-review-checklist [3174]: https://github.com/neovim/neovim/issues/3174 [Travis CI]: https://travis-ci.org/neovim/neovim [sourcehut]: https://builds.sr.ht/~jmk [AppVeyor]: https://ci.appveyor.com/project/neovim/neovim [Merge a Vim patch]: https://github.com/neovim/neovim/wiki/Merging-patches-from-upstream-Vim [Clang report]: https://neovim.io/doc/reports/clang/ [complexity:low]: https://github.com/neovim/neovim/issues?q=is%3Aopen+is%3Aissue+label%3Acomplexity%3Alow [master error list]: https://raw.githubusercontent.com/neovim/doc/gh-pages/reports/clint/errors.json [wiki-contribute-help]: https://github.com/neovim/neovim/wiki/contribute-%3Ahelp