3 Thank you for your interest in contributing to Rust! There are many ways to
4 contribute, and we appreciate all of them. This document is a bit long, so here's
5 links to the major sections:
7 * [Feature Requests](#feature-requests)
8 * [Bug Reports](#bug-reports)
9 * [The Build System](#the-build-system)
10 * [Pull Requests](#pull-requests)
11 * [Writing Documentation](#writing-documentation)
12 * [Issue Triage](#issue-triage)
13 * [Out-of-tree Contributions](#out-of-tree-contributions)
14 * [Helpful Links and Information](#helpful-links-and-information)
16 If you have questions, please make a post on [internals.rust-lang.org][internals] or
17 hop on [#rust-internals][pound-rust-internals].
19 As a reminder, all contributors are expected to follow our [Code of Conduct][coc].
21 [pound-rust-internals]: http://chat.mibbit.com/?server=irc.mozilla.org&channel=%23rust-internals
22 [internals]: https://internals.rust-lang.org
23 [coc]: https://www.rust-lang.org/conduct.html
27 To request a change to the way that the Rust language works, please open an
28 issue in the [RFCs repository](https://github.com/rust-lang/rfcs/issues/new)
29 rather than this one. New features and other significant language changes
30 must go through the RFC process.
34 While bugs are unfortunate, they're a reality in software. We can't fix what we
35 don't know about, so please report liberally. If you're not sure if something
36 is a bug or not, feel free to file a bug anyway.
38 **If you believe reporting your bug publicly represents a security risk to Rust users,
39 please follow our [instructions for reporting security vulnerabilities](https://www.rust-lang.org/security.html)**.
41 If you have the chance, before reporting a bug, please [search existing
42 issues](https://github.com/rust-lang/rust/search?q=&type=Issues&utf8=%E2%9C%93),
43 as it's possible that someone else has already reported your error. This doesn't
44 always work, and sometimes it's hard to know what to search for, so consider this
45 extra credit. We won't mind if you accidentally file a duplicate report.
47 Opening an issue is as easy as following [this
48 link](https://github.com/rust-lang/rust/issues/new) and filling out the fields.
49 Here's a template that you can use to file a bug, though it's not necessary to
52 <short summary of the bug>
56 <code sample that causes the bug>
58 I expected to see this happen: <explanation>
60 Instead, this happened: <explanation>
64 `rustc --version --verbose`:
68 All three components are important: what you did, what you expected, what
69 happened instead. Please include the output of `rustc --version --verbose`,
70 which includes important information about what platform you're on, what
71 version of Rust you're using, etc.
73 Sometimes, a backtrace is helpful, and so including that is nice. To get
74 a backtrace, set the `RUST_BACKTRACE` environment variable to a value
75 other than `0`. The easiest way
76 to do this is to invoke `rustc` like this:
79 $ RUST_BACKTRACE=1 rustc ...
84 Rust's build system allows you to bootstrap the compiler, run tests &
85 benchmarks, generate documentation, install a fresh build of Rust, and more.
86 It's your best friend when working on Rust, allowing you to compile & test
87 your contributions before submission.
89 All the configuration for the build system lives in [the `mk` directory][mkdir]
90 in the project root. It can be hard to follow in places, as it uses some
91 advanced Make features which make for some challenging reading. If you have
92 questions on the build system internals, try asking in
93 [`#rust-internals`][pound-rust-internals].
95 [mkdir]: https://github.com/rust-lang/rust/tree/master/mk/
99 Before you can start building the compiler you need to configure the build for
100 your system. In most cases, that will just mean using the defaults provided
101 for Rust. Configuring involves invoking the `configure` script in the project
108 There are large number of options accepted by this script to alter the
109 configuration used later in the build process. Some options to note:
111 - `--enable-debug` - Build a debug version of the compiler (disables optimizations,
112 which speeds up compilation of stage1 rustc)
113 - `--enable-optimize` - Enable optimizations (can be used with `--enable-debug`
114 to make a debug build with optimizations)
115 - `--disable-valgrind-rpass` - Don't run tests with valgrind
116 - `--enable-clang` - Prefer clang to gcc for building dependencies (e.g., LLVM)
117 - `--enable-ccache` - Invoke clang/gcc with ccache to re-use object files between builds
118 - `--enable-compiler-docs` - Build compiler documentation
120 To see a full list of options, run `./configure --help`.
124 Some common make targets are:
126 - `make tips` - show useful targets, variables and other tips for working with
128 - `make rustc-stage1` - build up to (and including) the first stage. For most
129 cases we don't need to build the stage2 compiler, so we can save time by not
130 building it. The stage1 compiler is a fully functioning compiler and
131 (probably) will be enough to determine if your change works as expected.
132 - `make $host/stage1/bin/rustc` - Where $host is a target triple like x86_64-unknown-linux-gnu.
133 This will build just rustc, without libstd. This is the fastest way to recompile after
134 you changed only rustc source code. Note however that the resulting rustc binary
135 won't have a stdlib to link against by default. You can build libstd once with
136 `make rustc-stage1`, rustc will pick it up afterwards. libstd is only guaranteed to
137 work if recompiled, so if there are any issues recompile it.
138 - `make check` - build the full compiler & run all tests (takes a while). This
139 is what gets run by the continuous integration system against your pull
140 request. You should run this before submitting to make sure your tests pass
141 & everything builds in the correct manner.
142 - `make check-stage1-std NO_REBUILD=1` - test the standard library without
143 rebuilding the entire compiler
144 - `make check TESTNAME=<substring-of-test-name>` - Run a matching set of tests.
145 - `TESTNAME` should be a substring of the tests to match against e.g. it could
146 be the fully qualified test name, or just a part of it.
147 `TESTNAME=collections::hash::map::test_map::test_capacity_not_less_than_len`
148 or `TESTNAME=test_capacity_not_less_than_len`.
149 - `make check-stage1-rpass TESTNAME=<substring-of-test-name>` - Run a single
150 rpass test with the stage1 compiler (this will be quicker than running the
151 command above as we only build the stage1 compiler, not the entire thing).
152 You can also leave off the `-rpass` to run all stage1 test types.
153 - `make check-stage1-coretest` - Run stage1 tests in `libcore`.
154 - `make tidy` - Check that the source code is in compliance with Rust's style
155 guidelines. There is no official document describing Rust's full guidelines
156 as of yet, but basic rules like 4 spaces for indentation and no more than 99
157 characters in a single line should be kept in mind when writing code.
161 Pull requests are the primary mechanism we use to change Rust. GitHub itself
162 has some [great documentation][pull-requests] on using the Pull Request
163 feature. We use the 'fork and pull' model described there.
165 [pull-requests]: https://help.github.com/articles/using-pull-requests/
167 Please make pull requests against the `master` branch.
169 Compiling all of `make check` can take a while. When testing your pull request,
170 consider using one of the more specialized `make` targets to cut down on the
171 amount of time you have to wait. You need to have built the compiler at least
172 once before running these will work, but that’s only one full build rather than
175 $ make -j8 rustc-stage1 && make check-stage1
177 is one such example, which builds just `rustc`, and then runs the tests. If
178 you’re adding something to the standard library, try
180 $ make -j8 check-stage1-std NO_REBUILD=1
182 This will not rebuild the compiler, but will run the tests.
184 Please make sure your pull request is in compliance with Rust's style
185 guidelines by running
189 Make this check before every pull request (and every new commit in a pull
190 request) ; you can add [git hooks](https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks)
191 before every push to make sure you never forget to make this check.
193 All pull requests are reviewed by another person. We have a bot,
194 @rust-highfive, that will automatically assign a random person to review your
197 If you want to request that a specific person reviews your pull request,
198 you can add an `r?` to the message. For example, Steve usually reviews
199 documentation changes. So if you were to make a documentation change, add
203 to the end of the message, and @rust-highfive will assign @steveklabnik instead
204 of a random person. This is entirely optional.
206 After someone has reviewed your pull request, they will leave an annotation
207 on the pull request with an `r+`. It will look something like this:
211 This tells @bors, our lovable integration bot, that your pull request has
212 been approved. The PR then enters the [merge queue][merge-queue], where @bors
213 will run all the tests on every platform we support. If it all works out,
214 @bors will merge your code into `master` and close the pull request.
216 [merge-queue]: http://buildbot.rust-lang.org/homu/queue/rust
218 Speaking of tests, Rust has a comprehensive test suite. More information about
220 [here](https://github.com/rust-lang/rust-wiki-backup/blob/master/Note-testsuite.md).
222 ## Writing Documentation
224 Documentation improvements are very welcome. The source of `doc.rust-lang.org`
225 is located in `src/doc` in the tree, and standard API documentation is generated
226 from the source code itself.
228 Documentation pull requests function in the same way as other pull requests,
229 though you may see a slightly different form of `r+`:
231 @bors: r+ 38fe8d2 rollup
233 That additional `rollup` tells @bors that this change is eligible for a 'rollup'.
234 To save @bors some work, and to get small changes through more quickly, when
235 @bors attempts to merge a commit that's rollup-eligible, it will also merge
236 the other rollup-eligible patches too, and they'll get tested and merged at
239 To find documentation-related issues, sort by the [A-docs label][adocs].
241 [adocs]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AA-docs
243 In many cases, you don't need a full `make doc`. You can use `rustdoc` directly
244 to check small fixes. For example, `rustdoc src/doc/reference.md` will render
245 reference to `doc/reference.html`. The CSS might be messed up, but you can
246 verify that the HTML is right.
250 Sometimes, an issue will stay open, even though the bug has been fixed. And
251 sometimes, the original bug may go stale because something has changed in the
254 It can be helpful to go through older bug reports and make sure that they are
255 still valid. Load up an older issue, double check that it's still true, and
256 leave a comment letting us know if it is or is not. The [least recently
257 updated sort][lru] is good for finding issues like this.
259 Contributors with sufficient permissions on the Rust repo can help by adding
260 labels to triage issues:
262 * Yellow, **A**-prefixed labels state which **area** of the project an issue
265 * Magenta, **B**-prefixed labels identify bugs which are **blockers**.
267 * Green, **E**-prefixed labels explain the level of **experience** necessary
270 * Red, **I**-prefixed labels indicate the **importance** of the issue. The
271 [I-nominated][inom] label indicates that an issue has been nominated for
272 prioritizing at the next triage meeting.
274 * Orange, **P**-prefixed labels indicate a bug's **priority**. These labels
275 are only assigned during triage meetings, and replace the [I-nominated][inom]
278 * Blue, **T**-prefixed bugs denote which **team** the issue belongs to.
280 * Dark blue, **beta-** labels track changes which need to be backported into
283 * The purple **metabug** label marks lists of bugs collected by other
286 If you're looking for somewhere to start, check out the [E-easy][eeasy] tag.
288 [inom]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AI-nominated
289 [eeasy]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AE-easy
290 [lru]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-asc
292 ## Out-of-tree Contributions
294 There are a number of other ways to contribute to Rust that don't deal with
297 Answer questions in [#rust][pound-rust], or on [users.rust-lang.org][users],
298 or on [StackOverflow][so].
300 Participate in the [RFC process](https://github.com/rust-lang/rfcs).
302 Find a [requested community library][community-library], build it, and publish
303 it to [Crates.io](http://crates.io). Easier said than done, but very, very
306 [pound-rust]: http://chat.mibbit.com/?server=irc.mozilla.org&channel=%23rust
307 [users]: https://users.rust-lang.org/
308 [so]: http://stackoverflow.com/questions/tagged/rust
309 [community-library]: https://github.com/rust-lang/rfcs/labels/A-community-library
311 ## Helpful Links and Information
313 For people new to Rust, and just starting to contribute, or even for
314 more seasoned developers, some useful places to look for information
317 * The [Rust Internals forum][rif], a place to ask questions and
318 discuss Rust's internals
319 * The [generated documentation for rust's compiler][gdfrustc]
320 * The [rust reference][rr], even though it doesn't specifically talk about Rust's internals, it's a great resource nonetheless
321 * Although out of date, [Tom Lee's great blog article][tlgba] is very helpful
322 * [rustaceans.org][ro] is helpful, but mostly dedicated to IRC
323 * The [Rust Compiler Testing Docs][rctd]
324 * For @bors, [this cheat sheet][cheatsheet] is helpful (Remember to replace `@homu` with `@bors` in the commands that you use.)
325 * **Google!** ([search only in Rust Documentation][gsearchdocs] to find types, traits, etc. quickly)
326 * Don't be afraid to ask! The Rust community is friendly and helpful.
328 [gdfrustc]: http://manishearth.github.io/rust-internals-docs/rustc/
329 [gsearchdocs]: https://www.google.com/search?q=site:doc.rust-lang.org+your+query+here
330 [rif]: http://internals.rust-lang.org
331 [rr]: https://doc.rust-lang.org/book/README.html
332 [tlgba]: http://tomlee.co/2014/04/a-more-detailed-tour-of-the-rust-compiler/
333 [ro]: http://www.rustaceans.org/
334 [rctd]: ./COMPILER_TESTS.md
335 [cheatsheet]: http://buildbot.rust-lang.org/homu/