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
102 To change configuration, you must copy the file `src/bootstrap/config.toml.example`
103 to `config.toml` in the directory from which you will be running the build, and
104 change the settings provided.
106 There are large number of options provided in this config file that will alter the
107 configuration used in the build process. Some options to note:
110 - `ccache = true` - Use ccache when building llvm
113 - `compiler-docs = true` - Build compiler documentation
116 - `debuginfo = true` - Build a compiler with debuginfo
117 - `optimize = false` - Disable optimizations to speed up compilation of stage1 rust
119 For more options, the `config.toml` file contains commented out defaults, with
120 descriptions of what each option will do.
122 Note: Previously the `./configure` script was used to configure this
123 project. It can still be used, but it's recommended to use a `config.toml`
124 file. If you still have a `config.mk` file in your directory - from
125 `./configure` - you may need to delete it for `config.toml` to work.
129 The build system uses the `x.py` script to control the build process. This script
130 is used to build, test, and document various parts of the compiler. You can
137 On some systems you can also use the shorter version:
143 To learn more about the driver and top-level targets, you can execute:
149 The general format for the driver script is:
152 python x.py <command> [<directory>]
155 Some example commands are `build`, `test`, and `doc`. These will build, test,
156 and document the specified directory. The second argument, `<directory>`, is
157 optional and defaults to working over the entire compiler. If specified,
158 however, only that specific directory will be built. For example:
161 # build the entire compiler
164 # build all documentation
167 # run all test suites
170 # build only the standard library
171 python x.py build src/libstd
173 # test only one particular test suite
174 python x.py test src/test/rustdoc
176 # build only the stage0 libcore library
177 python x.py build src/libcore --stage 0
180 You can explore the build system throught the various `--help` pages for each
181 subcommand. For example to learn more about a command you can run:
184 python x.py build --help
187 To learn about all possible rules you can execute, run:
190 python x.py build --help --verbose
193 Note: Previously `./configure` and `make` were used to build this project.
194 They are still available, but `x.py` is the recommended build system.
198 Some common invocations of `x.py` are:
200 - `x.py build --help` - show the help message and explain the subcommand
201 - `x.py build src/libtest --stage 1` - build up to (and including) the first
202 stage. For most cases we don't need to build the stage2 compiler, so we can
203 save time by not building it. The stage1 compiler is a fully functioning
204 compiler and (probably) will be enough to determine if your change works as
206 - `x.py build src/rustc --stage 1` - This will build just rustc, without libstd.
207 This is the fastest way to recompile after you changed only rustc source code.
208 Note however that the resulting rustc binary won't have a stdlib to link
209 against by default. You can build libstd once with `x.py build src/libstd`,
210 but it is only guaranteed to work if recompiled, so if there are any issues
212 - `x.py test` - build the full compiler & run all tests (takes a while). This
213 is what gets run by the continuous integration system against your pull
214 request. You should run this before submitting to make sure your tests pass
215 & everything builds in the correct manner.
216 - `x.py test src/libstd --stage 1` - test the standard library without
218 - `x.py test src/test/run-pass --test-args TESTNAME` - Run a matching set of
220 - `TESTNAME` should be a substring of the tests to match against e.g. it could
221 be the fully qualified test name, or just a part of it.
222 `TESTNAME=collections::hash::map::test_map::test_capacity_not_less_than_len`
223 or `TESTNAME=test_capacity_not_less_than_len`.
224 - `x.py test src/test/run-pass --stage 1 --test-args <substring-of-test-name>` -
225 Run a single rpass test with the stage1 compiler (this will be quicker than
226 running the command above as we only build the stage1 compiler, not the entire
227 thing). You can also leave off the directory argument to run all stage1 test
229 - `x.py test src/libcore --stage 1` - Run stage1 tests in `libcore`.
230 - `x.py test src/tools/tidy` - Check that the source code is in compliance with
231 Rust's style guidelines. There is no official document describing Rust's full
232 guidelines as of yet, but basic rules like 4 spaces for indentation and no
233 more than 99 characters in a single line should be kept in mind when writing
238 Pull requests are the primary mechanism we use to change Rust. GitHub itself
239 has some [great documentation][pull-requests] on using the Pull Request
240 feature. We use the 'fork and pull' model described there.
242 [pull-requests]: https://help.github.com/articles/using-pull-requests/
244 Please make pull requests against the `master` branch.
246 Compiling all of `./x.py test` can take a while. When testing your pull request,
247 consider using one of the more specialized `./x.py` targets to cut down on the
248 amount of time you have to wait. You need to have built the compiler at least
249 once before running these will work, but that’s only one full build rather than
252 $ python x.py test --stage 1
254 is one such example, which builds just `rustc`, and then runs the tests. If
255 you’re adding something to the standard library, try
257 $ python x.py test src/libstd --stage 1
259 Please make sure your pull request is in compliance with Rust's style
260 guidelines by running
262 $ python x.py test src/tools/tidy
264 Make this check before every pull request (and every new commit in a pull
265 request) ; you can add [git hooks](https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks)
266 before every push to make sure you never forget to make this check.
268 All pull requests are reviewed by another person. We have a bot,
269 @rust-highfive, that will automatically assign a random person to review your
272 If you want to request that a specific person reviews your pull request,
273 you can add an `r?` to the message. For example, Steve usually reviews
274 documentation changes. So if you were to make a documentation change, add
278 to the end of the message, and @rust-highfive will assign @steveklabnik instead
279 of a random person. This is entirely optional.
281 After someone has reviewed your pull request, they will leave an annotation
282 on the pull request with an `r+`. It will look something like this:
286 This tells @bors, our lovable integration bot, that your pull request has
287 been approved. The PR then enters the [merge queue][merge-queue], where @bors
288 will run all the tests on every platform we support. If it all works out,
289 @bors will merge your code into `master` and close the pull request.
291 [merge-queue]: https://buildbot.rust-lang.org/homu/queue/rust
293 Speaking of tests, Rust has a comprehensive test suite. More information about
295 [here](https://github.com/rust-lang/rust-wiki-backup/blob/master/Note-testsuite.md).
297 ## Writing Documentation
299 Documentation improvements are very welcome. The source of `doc.rust-lang.org`
300 is located in `src/doc` in the tree, and standard API documentation is generated
301 from the source code itself.
303 Documentation pull requests function in the same way as other pull requests,
304 though you may see a slightly different form of `r+`:
306 @bors: r+ 38fe8d2 rollup
308 That additional `rollup` tells @bors that this change is eligible for a 'rollup'.
309 To save @bors some work, and to get small changes through more quickly, when
310 @bors attempts to merge a commit that's rollup-eligible, it will also merge
311 the other rollup-eligible patches too, and they'll get tested and merged at
314 To find documentation-related issues, sort by the [T-doc label][tdoc].
316 [tdoc]: https://github.com/rust-lang/rust/issues?q=is%3Aopen%20is%3Aissue%20label%3AT-doc
318 You can find documentation style guidelines in [RFC 1574][rfc1574].
320 [rfc1574]: https://github.com/rust-lang/rfcs/blob/master/text/1574-more-api-documentation-conventions.md#appendix-a-full-conventions-text
322 In many cases, you don't need a full `./x.py doc`. You can use `rustdoc` directly
323 to check small fixes. For example, `rustdoc src/doc/reference.md` will render
324 reference to `doc/reference.html`. The CSS might be messed up, but you can
325 verify that the HTML is right.
329 Sometimes, an issue will stay open, even though the bug has been fixed. And
330 sometimes, the original bug may go stale because something has changed in the
333 It can be helpful to go through older bug reports and make sure that they are
334 still valid. Load up an older issue, double check that it's still true, and
335 leave a comment letting us know if it is or is not. The [least recently
336 updated sort][lru] is good for finding issues like this.
338 Contributors with sufficient permissions on the Rust repo can help by adding
339 labels to triage issues:
341 * Yellow, **A**-prefixed labels state which **area** of the project an issue
344 * Magenta, **B**-prefixed labels identify bugs which are **blockers**.
346 * Green, **E**-prefixed labels explain the level of **experience** necessary
349 * Red, **I**-prefixed labels indicate the **importance** of the issue. The
350 [I-nominated][inom] label indicates that an issue has been nominated for
351 prioritizing at the next triage meeting.
353 * Orange, **P**-prefixed labels indicate a bug's **priority**. These labels
354 are only assigned during triage meetings, and replace the [I-nominated][inom]
357 * Blue, **T**-prefixed bugs denote which **team** the issue belongs to.
359 * Dark blue, **beta-** labels track changes which need to be backported into
362 * The purple **metabug** label marks lists of bugs collected by other
365 If you're looking for somewhere to start, check out the [E-easy][eeasy] tag.
367 [inom]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AI-nominated
368 [eeasy]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AE-easy
369 [lru]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-asc
371 ## Out-of-tree Contributions
373 There are a number of other ways to contribute to Rust that don't deal with
376 Answer questions in [#rust][pound-rust], or on [users.rust-lang.org][users],
377 or on [StackOverflow][so].
379 Participate in the [RFC process](https://github.com/rust-lang/rfcs).
381 Find a [requested community library][community-library], build it, and publish
382 it to [Crates.io](http://crates.io). Easier said than done, but very, very
385 [pound-rust]: http://chat.mibbit.com/?server=irc.mozilla.org&channel=%23rust
386 [users]: https://users.rust-lang.org/
387 [so]: http://stackoverflow.com/questions/tagged/rust
388 [community-library]: https://github.com/rust-lang/rfcs/labels/A-community-library
390 ## Helpful Links and Information
392 For people new to Rust, and just starting to contribute, or even for
393 more seasoned developers, some useful places to look for information
396 * The [Rust Internals forum][rif], a place to ask questions and
397 discuss Rust's internals
398 * The [generated documentation for rust's compiler][gdfrustc]
399 * The [rust reference][rr], even though it doesn't specifically talk about Rust's internals, it's a great resource nonetheless
400 * Although out of date, [Tom Lee's great blog article][tlgba] is very helpful
401 * [rustaceans.org][ro] is helpful, but mostly dedicated to IRC
402 * The [Rust Compiler Testing Docs][rctd]
403 * For @bors, [this cheat sheet][cheatsheet] is helpful (Remember to replace `@homu` with `@bors` in the commands that you use.)
404 * **Google!** ([search only in Rust Documentation][gsearchdocs] to find types, traits, etc. quickly)
405 * Don't be afraid to ask! The Rust community is friendly and helpful.
407 [gdfrustc]: http://manishearth.github.io/rust-internals-docs/rustc/
408 [gsearchdocs]: https://www.google.com/search?q=site:doc.rust-lang.org+your+query+here
409 [rif]: http://internals.rust-lang.org
410 [rr]: https://doc.rust-lang.org/book/README.html
411 [tlgba]: http://tomlee.co/2014/04/a-more-detailed-tour-of-the-rust-compiler/
412 [ro]: http://www.rustaceans.org/
413 [rctd]: ./src/test/COMPILER_TESTS.md
414 [cheatsheet]: https://buildbot.rust-lang.org/homu/