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 The build system lives in [the `src/bootstrap` directory][bootstrap] in the
90 project root. Our build system is itself written in Rust and is based on Cargo
91 to actually build all the compiler's crates. If you have questions on the build
92 system internals, try asking in [`#rust-internals`][pound-rust-internals].
94 [bootstrap]: https://github.com/rust-lang/rust/tree/master/src/bootstrap/
98 Before you can start building the compiler you need to configure the build for
99 your system. In most cases, that will just mean using the defaults provided
100 for Rust. Configuring involves invoking the `configure` script in the project
107 There are large number of options accepted by this script to alter the
108 configuration used later in the build process. Some options to note:
110 - `--enable-debug` - Build a debug version of the compiler (disables optimizations,
111 which speeds up compilation of stage1 rustc)
112 - `--enable-optimize` - Enable optimizations (can be used with `--enable-debug`
113 to make a debug build with optimizations)
114 - `--disable-valgrind-rpass` - Don't run tests with valgrind
115 - `--enable-clang` - Prefer clang to gcc for building dependencies (e.g., LLVM)
116 - `--enable-ccache` - Invoke clang/gcc with ccache to re-use object files between builds
117 - `--enable-compiler-docs` - Build compiler documentation
119 To see a full list of options, run `./configure --help`.
123 Although the `./configure` script will generate a `Makefile`, this is actually
124 just a thin veneer over the actual build system driver, `x.py`. This file, at
125 the root of the repository, is used to build, test, and document various parts
126 of the compiler. You can execute it as:
132 On some systems you can also use the shorter version:
138 To learn more about the driver and top-level targets, you can execute:
144 The general format for the driver script is:
147 python x.py <command> [<directory>]
150 Some example commands are `build`, `test`, and `doc`. These will build, test,
151 and document the specified directory. The second argument, `<directory>`, is
152 optional and defaults to working over the entire compiler. If specified,
153 however, only that specific directory will be built. For example:
156 # build the entire compiler
159 # build all documentation
162 # run all test suites
165 # build only the standard library
166 python x.py build src/libstd
168 # test only one particular test suite
169 python x.py test src/test/rustdoc
171 # build only the stage0 libcore library
172 python x.py build src/libcore --stage 0
175 You can explore the build system throught the various `--help` pages for each
176 subcommand. For example to learn more about a command you can run:
179 python x.py build --help
182 To learn about all possible rules you can execute, run:
185 python x.py build --help --verbose
190 Some common invocations of `x.py` are:
192 - `x.py build --help` - show the help message and explain the subcommand
193 - `x.py build src/libtest --stage 1` - build up to (and including) the first
194 stage. For most cases we don't need to build the stage2 compiler, so we can
195 save time by not building it. The stage1 compiler is a fully functioning
196 compiler and (probably) will be enough to determine if your change works as
198 - `x.py build src/rustc --stage 1` - This will build just rustc, without libstd.
199 This is the fastest way to recompile after you changed only rustc source code.
200 Note however that the resulting rustc binary won't have a stdlib to link
201 against by default. You can build libstd once with `x.py build src/libstd`,
202 but it is only guaranteed to work if recompiled, so if there are any issues
204 - `x.py test` - build the full compiler & run all tests (takes a while). This
205 is what gets run by the continuous integration system against your pull
206 request. You should run this before submitting to make sure your tests pass
207 & everything builds in the correct manner.
208 - `x.py test src/libstd --stage 1` - test the standard library without
210 - `x.py test src/test/run-pass --test-args TESTNAME` - Run a matching set of
212 - `TESTNAME` should be a substring of the tests to match against e.g. it could
213 be the fully qualified test name, or just a part of it.
214 `TESTNAME=collections::hash::map::test_map::test_capacity_not_less_than_len`
215 or `TESTNAME=test_capacity_not_less_than_len`.
216 - `x.py test src/test/run-pass --stage 1 --test-args <substring-of-test-name>` -
217 Run a single rpass test with the stage1 compiler (this will be quicker than
218 running the command above as we only build the stage1 compiler, not the entire
219 thing). You can also leave off the directory argument to run all stage1 test
221 - `x.py test src/libcore --stage 1` - Run stage1 tests in `libcore`.
222 - `x.py test src/tools/tidy` - Check that the source code is in compliance with
223 Rust's style guidelines. There is no official document describing Rust's full
224 guidelines as of yet, but basic rules like 4 spaces for indentation and no
225 more than 99 characters in a single line should be kept in mind when writing
230 Pull requests are the primary mechanism we use to change Rust. GitHub itself
231 has some [great documentation][pull-requests] on using the Pull Request
232 feature. We use the 'fork and pull' model described there.
234 [pull-requests]: https://help.github.com/articles/using-pull-requests/
236 Please make pull requests against the `master` branch.
238 Compiling all of `make check` can take a while. When testing your pull request,
239 consider using one of the more specialized `make` targets to cut down on the
240 amount of time you have to wait. You need to have built the compiler at least
241 once before running these will work, but that’s only one full build rather than
244 $ python x.py test --stage 1
246 is one such example, which builds just `rustc`, and then runs the tests. If
247 you’re adding something to the standard library, try
249 $ python x.py test src/libstd --stage 1
251 Please make sure your pull request is in compliance with Rust's style
252 guidelines by running
254 $ python x.py test src/tools/tidy
256 Make this check before every pull request (and every new commit in a pull
257 request) ; you can add [git hooks](https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks)
258 before every push to make sure you never forget to make this check.
260 All pull requests are reviewed by another person. We have a bot,
261 @rust-highfive, that will automatically assign a random person to review your
264 If you want to request that a specific person reviews your pull request,
265 you can add an `r?` to the message. For example, Steve usually reviews
266 documentation changes. So if you were to make a documentation change, add
270 to the end of the message, and @rust-highfive will assign @steveklabnik instead
271 of a random person. This is entirely optional.
273 After someone has reviewed your pull request, they will leave an annotation
274 on the pull request with an `r+`. It will look something like this:
278 This tells @bors, our lovable integration bot, that your pull request has
279 been approved. The PR then enters the [merge queue][merge-queue], where @bors
280 will run all the tests on every platform we support. If it all works out,
281 @bors will merge your code into `master` and close the pull request.
283 [merge-queue]: https://buildbot.rust-lang.org/homu/queue/rust
285 Speaking of tests, Rust has a comprehensive test suite. More information about
287 [here](https://github.com/rust-lang/rust-wiki-backup/blob/master/Note-testsuite.md).
289 ## Writing Documentation
291 Documentation improvements are very welcome. The source of `doc.rust-lang.org`
292 is located in `src/doc` in the tree, and standard API documentation is generated
293 from the source code itself.
295 Documentation pull requests function in the same way as other pull requests,
296 though you may see a slightly different form of `r+`:
298 @bors: r+ 38fe8d2 rollup
300 That additional `rollup` tells @bors that this change is eligible for a 'rollup'.
301 To save @bors some work, and to get small changes through more quickly, when
302 @bors attempts to merge a commit that's rollup-eligible, it will also merge
303 the other rollup-eligible patches too, and they'll get tested and merged at
306 To find documentation-related issues, sort by the [A-docs label][adocs].
308 [adocs]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AA-docs
310 In many cases, you don't need a full `make doc`. You can use `rustdoc` directly
311 to check small fixes. For example, `rustdoc src/doc/reference.md` will render
312 reference to `doc/reference.html`. The CSS might be messed up, but you can
313 verify that the HTML is right.
317 Sometimes, an issue will stay open, even though the bug has been fixed. And
318 sometimes, the original bug may go stale because something has changed in the
321 It can be helpful to go through older bug reports and make sure that they are
322 still valid. Load up an older issue, double check that it's still true, and
323 leave a comment letting us know if it is or is not. The [least recently
324 updated sort][lru] is good for finding issues like this.
326 Contributors with sufficient permissions on the Rust repo can help by adding
327 labels to triage issues:
329 * Yellow, **A**-prefixed labels state which **area** of the project an issue
332 * Magenta, **B**-prefixed labels identify bugs which are **blockers**.
334 * Green, **E**-prefixed labels explain the level of **experience** necessary
337 * Red, **I**-prefixed labels indicate the **importance** of the issue. The
338 [I-nominated][inom] label indicates that an issue has been nominated for
339 prioritizing at the next triage meeting.
341 * Orange, **P**-prefixed labels indicate a bug's **priority**. These labels
342 are only assigned during triage meetings, and replace the [I-nominated][inom]
345 * Blue, **T**-prefixed bugs denote which **team** the issue belongs to.
347 * Dark blue, **beta-** labels track changes which need to be backported into
350 * The purple **metabug** label marks lists of bugs collected by other
353 If you're looking for somewhere to start, check out the [E-easy][eeasy] tag.
355 [inom]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AI-nominated
356 [eeasy]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AE-easy
357 [lru]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-asc
359 ## Out-of-tree Contributions
361 There are a number of other ways to contribute to Rust that don't deal with
364 Answer questions in [#rust][pound-rust], or on [users.rust-lang.org][users],
365 or on [StackOverflow][so].
367 Participate in the [RFC process](https://github.com/rust-lang/rfcs).
369 Find a [requested community library][community-library], build it, and publish
370 it to [Crates.io](http://crates.io). Easier said than done, but very, very
373 [pound-rust]: http://chat.mibbit.com/?server=irc.mozilla.org&channel=%23rust
374 [users]: https://users.rust-lang.org/
375 [so]: http://stackoverflow.com/questions/tagged/rust
376 [community-library]: https://github.com/rust-lang/rfcs/labels/A-community-library
378 ## Helpful Links and Information
380 For people new to Rust, and just starting to contribute, or even for
381 more seasoned developers, some useful places to look for information
384 * The [Rust Internals forum][rif], a place to ask questions and
385 discuss Rust's internals
386 * The [generated documentation for rust's compiler][gdfrustc]
387 * The [rust reference][rr], even though it doesn't specifically talk about Rust's internals, it's a great resource nonetheless
388 * Although out of date, [Tom Lee's great blog article][tlgba] is very helpful
389 * [rustaceans.org][ro] is helpful, but mostly dedicated to IRC
390 * The [Rust Compiler Testing Docs][rctd]
391 * For @bors, [this cheat sheet][cheatsheet] is helpful (Remember to replace `@homu` with `@bors` in the commands that you use.)
392 * **Google!** ([search only in Rust Documentation][gsearchdocs] to find types, traits, etc. quickly)
393 * Don't be afraid to ask! The Rust community is friendly and helpful.
395 [gdfrustc]: http://manishearth.github.io/rust-internals-docs/rustc/
396 [gsearchdocs]: https://www.google.com/search?q=site:doc.rust-lang.org+your+query+here
397 [rif]: http://internals.rust-lang.org
398 [rr]: https://doc.rust-lang.org/book/README.html
399 [tlgba]: http://tomlee.co/2014/04/a-more-detailed-tour-of-the-rust-compiler/
400 [ro]: http://www.rustaceans.org/
401 [rctd]: ./COMPILER_TESTS.md
402 [cheatsheet]: https://buildbot.rust-lang.org/homu/