2 [contributing-to-rust]: #contributing-to-rust
4 Thank you for your interest in contributing to Rust! There are many ways to
5 contribute, and we appreciate all of them. This document is a bit long, so here's
6 links to the major sections:
8 * [Feature Requests](#feature-requests)
9 * [Bug Reports](#bug-reports)
10 * [The Build System](#the-build-system)
11 * [Pull Requests](#pull-requests)
12 * [Writing Documentation](#writing-documentation)
13 * [Issue Triage](#issue-triage)
14 * [Out-of-tree Contributions](#out-of-tree-contributions)
15 * [Helpful Links and Information](#helpful-links-and-information)
17 If you have questions, please make a post on [internals.rust-lang.org][internals] or
18 hop on [#rust-internals][pound-rust-internals].
20 As a reminder, all contributors are expected to follow our [Code of Conduct][coc].
22 [pound-rust-internals]: https://chat.mibbit.com/?server=irc.mozilla.org&channel=%23rust-internals
23 [internals]: https://internals.rust-lang.org
24 [coc]: https://www.rust-lang.org/conduct.html
27 [feature-requests]: #feature-requests
29 To request a change to the way the Rust language works, please head over
30 to the [RFCs repository](https://github.com/rust-lang/rfcs) and view the
31 [README](https://github.com/rust-lang/rfcs/blob/master/README.md)
35 [bug-reports]: #bug-reports
37 While bugs are unfortunate, they're a reality in software. We can't fix what we
38 don't know about, so please report liberally. If you're not sure if something
39 is a bug or not, feel free to file a bug anyway.
41 **If you believe reporting your bug publicly represents a security risk to Rust users,
42 please follow our [instructions for reporting security vulnerabilities](https://www.rust-lang.org/security.html)**.
44 If you have the chance, before reporting a bug, please [search existing
45 issues](https://github.com/rust-lang/rust/search?q=&type=Issues&utf8=%E2%9C%93),
46 as it's possible that someone else has already reported your error. This doesn't
47 always work, and sometimes it's hard to know what to search for, so consider this
48 extra credit. We won't mind if you accidentally file a duplicate report.
50 Similarly, to help others who encountered the bug find your issue,
51 consider filing an issue with a descriptive title, which contains information that might be unique to it.
52 This can be the language or compiler feature used, the conditions that trigger the bug,
53 or part of the error message if there is any.
54 An example could be: **"impossible case reached" on lifetime inference for impl Trait in return position**.
56 Opening an issue is as easy as following [this
57 link](https://github.com/rust-lang/rust/issues/new) and filling out the fields.
58 Here's a template that you can use to file a bug, though it's not necessary to
61 <short summary of the bug>
65 <code sample that causes the bug>
67 I expected to see this happen: <explanation>
69 Instead, this happened: <explanation>
73 `rustc --version --verbose`:
77 All three components are important: what you did, what you expected, what
78 happened instead. Please include the output of `rustc --version --verbose`,
79 which includes important information about what platform you're on, what
80 version of Rust you're using, etc.
82 Sometimes, a backtrace is helpful, and so including that is nice. To get
83 a backtrace, set the `RUST_BACKTRACE` environment variable to a value
84 other than `0`. The easiest way
85 to do this is to invoke `rustc` like this:
88 $ RUST_BACKTRACE=1 rustc ...
92 [the-build-system]: #the-build-system
94 Rust's build system allows you to bootstrap the compiler, run tests &
95 benchmarks, generate documentation, install a fresh build of Rust, and more.
96 It's your best friend when working on Rust, allowing you to compile & test
97 your contributions before submission.
99 The build system lives in [the `src/bootstrap` directory][bootstrap] in the
100 project root. Our build system is itself written in Rust and is based on Cargo
101 to actually build all the compiler's crates. If you have questions on the build
102 system internals, try asking in [`#rust-internals`][pound-rust-internals].
104 [bootstrap]: https://github.com/rust-lang/rust/tree/master/src/bootstrap/
107 [configuration]: #configuration
109 Before you can start building the compiler you need to configure the build for
110 your system. In most cases, that will just mean using the defaults provided
113 To change configuration, you must copy the file `config.toml.example`
114 to `config.toml` in the directory from which you will be running the build, and
115 change the settings provided.
117 There are large number of options provided in this config file that will alter the
118 configuration used in the build process. Some options to note:
121 - `assertions = true` = This enables LLVM assertions, which makes LLVM misuse cause an assertion failure instead of weird misbehavior. This also slows down the compiler's runtime by ~20%.
122 - `ccache = true` - Use ccache when building llvm
125 - `compiler-docs = true` - Build compiler documentation
128 - `debuginfo = true` - Build a compiler with debuginfo. Makes building rustc slower, but then you can use a debugger to debug `rustc`.
129 - `debuginfo-lines = true` - An alternative to `debuginfo = true` that doesn't let you use a debugger, but doesn't make building rustc slower and still gives you line numbers in backtraces.
130 - `debuginfo-tools = true` - Build the extended tools with debuginfo.
131 - `debug-assertions = true` - Makes the log output of `debug!` work.
132 - `optimize = false` - Disable optimizations to speed up compilation of stage1 rust, but makes the stage1 compiler x100 slower.
134 For more options, the `config.toml` file contains commented out defaults, with
135 descriptions of what each option will do.
137 Note: Previously the `./configure` script was used to configure this
138 project. It can still be used, but it's recommended to use a `config.toml`
139 file. If you still have a `config.mk` file in your directory - from
140 `./configure` - you may need to delete it for `config.toml` to work.
143 [building]: #building
145 A default configuration requires around 3.5 GB of disk space, whereas building a debug configuration may require more than 30 GB.
148 - [build dependencies](README.md#building-from-source)
149 - `gdb` 6.2.0 minimum, 7.1 or later recommended for test builds
151 The build system uses the `x.py` script to control the build process. This script
152 is used to build, test, and document various parts of the compiler. You can
159 On some systems you can also use the shorter version:
165 To learn more about the driver and top-level targets, you can execute:
171 The general format for the driver script is:
174 python x.py <command> [<directory>]
177 Some example commands are `build`, `test`, and `doc`. These will build, test,
178 and document the specified directory. The second argument, `<directory>`, is
179 optional and defaults to working over the entire compiler. If specified,
180 however, only that specific directory will be built. For example:
183 # build the entire compiler
186 # build all documentation
189 # run all test suites
192 # build only the standard library
193 python x.py build src/libstd
195 # test only one particular test suite
196 python x.py test src/test/rustdoc
198 # build only the stage0 libcore library
199 python x.py build src/libcore --stage 0
202 You can explore the build system through the various `--help` pages for each
203 subcommand. For example to learn more about a command you can run:
206 python x.py build --help
209 To learn about all possible rules you can execute, run:
212 python x.py build --help --verbose
215 Note: Previously `./configure` and `make` were used to build this project.
216 They are still available, but `x.py` is the recommended build system.
219 [useful-commands]: #useful-commands
221 Some common invocations of `x.py` are:
223 - `x.py build --help` - show the help message and explain the subcommand
224 - `x.py build src/libtest --stage 1` - build up to (and including) the first
225 stage. For most cases we don't need to build the stage2 compiler, so we can
226 save time by not building it. The stage1 compiler is a fully functioning
227 compiler and (probably) will be enough to determine if your change works as
229 - `x.py build src/rustc --stage 1` - This will build just rustc, without libstd.
230 This is the fastest way to recompile after you changed only rustc source code.
231 Note however that the resulting rustc binary won't have a stdlib to link
232 against by default. You can build libstd once with `x.py build src/libstd`,
233 but it is only guaranteed to work if recompiled, so if there are any issues
235 - `x.py test` - build the full compiler & run all tests (takes a while). This
236 is what gets run by the continuous integration system against your pull
237 request. You should run this before submitting to make sure your tests pass
238 & everything builds in the correct manner.
239 - `x.py test src/libstd --stage 1` - test the standard library without
241 - `x.py test src/test/run-pass --test-args TESTNAME` - Run a matching set of
243 - `TESTNAME` should be a substring of the tests to match against e.g. it could
244 be the fully qualified test name, or just a part of it.
245 `TESTNAME=collections::hash::map::test_map::test_capacity_not_less_than_len`
246 or `TESTNAME=test_capacity_not_less_than_len`.
247 - `x.py test src/test/run-pass --stage 1 --test-args <substring-of-test-name>` -
248 Run a single rpass test with the stage1 compiler (this will be quicker than
249 running the command above as we only build the stage1 compiler, not the entire
250 thing). You can also leave off the directory argument to run all stage1 test
252 - `x.py test src/libcore --stage 1` - Run stage1 tests in `libcore`.
253 - `x.py test src/tools/tidy` - Check that the source code is in compliance with
254 Rust's style guidelines. There is no official document describing Rust's full
255 guidelines as of yet, but basic rules like 4 spaces for indentation and no
256 more than 99 characters in a single line should be kept in mind when writing
259 ### Using your local build
260 [using-local-build]: #using-local-build
262 If you use Rustup to manage your rust install, it has a feature called ["custom
263 toolchains"][toolchain-link] that you can use to access your newly-built compiler
264 without having to install it to your system or user PATH. If you've run `python
265 x.py build`, then you can add your custom rustc to a new toolchain like this:
267 [toolchain-link]: https://github.com/rust-lang-nursery/rustup.rs#working-with-custom-toolchains-and-local-builds
270 rustup toolchain link <name> build/<host-triple>/stage2
273 Where `<host-triple>` is the build triple for the host (the triple of your
274 computer, by default), and `<name>` is the name for your custom toolchain. (If you
275 added `--stage 1` to your build command, the compiler will be in the `stage1`
276 folder instead.) You'll only need to do this once - it will automatically point
277 to the latest build you've done.
279 Once this is set up, you can use your custom toolchain just like any other. For
280 example, if you've named your toolchain `local`, running `cargo +local build` will
281 compile a project with your custom rustc, setting `rustup override set local` will
282 override the toolchain for your current directory, and `cargo +local doc` will use
283 your custom rustc and rustdoc to generate docs. (If you do this with a `--stage 1`
284 build, you'll need to build rustdoc specially, since it's not normally built in
285 stage 1. `python x.py build --stage 1 src/libstd src/tools/rustdoc` will build
286 rustdoc and libstd, which will allow rustdoc to be run with that toolchain.)
288 ### Out-of-tree builds
289 [out-of-tree-builds]: #out-of-tree-builds
291 Rust's `x.py` script fully supports out-of-tree builds - it looks for
292 the Rust source code from the directory `x.py` was found in, but it
293 reads the `config.toml` configuration file from the directory it's
294 run in, and places all build artifacts within a subdirectory named `build`.
296 This means that if you want to do an out-of-tree build, you can just do it:
299 $ cp ~/my-config.toml config.toml # Or fill in config.toml otherwise
300 $ path/to/rust/x.py build
302 $ # This will use the Rust source code in `path/to/rust`, but build
303 $ # artifacts will now be in ./build
306 It's absolutely fine to have multiple build directories with different
307 `config.toml` configurations using the same code.
310 [pull-requests]: #pull-requests
312 Pull requests are the primary mechanism we use to change Rust. GitHub itself
313 has some [great documentation][about-pull-requests] on using the Pull Request feature.
314 We use the "fork and pull" model [described here][development-models], where
315 contributors push changes to their personal fork and create pull requests to
316 bring those changes into the source repository.
318 [about-pull-requests]: https://help.github.com/articles/about-pull-requests/
319 [development-models]: https://help.github.com/articles/about-collaborative-development-models/
321 Please make pull requests against the `master` branch.
323 Compiling all of `./x.py test` can take a while. When testing your pull request,
324 consider using one of the more specialized `./x.py` targets to cut down on the
325 amount of time you have to wait. You need to have built the compiler at least
326 once before running these will work, but that’s only one full build rather than
329 $ python x.py test --stage 1
331 is one such example, which builds just `rustc`, and then runs the tests. If
332 you’re adding something to the standard library, try
334 $ python x.py test src/libstd --stage 1
336 Please make sure your pull request is in compliance with Rust's style
337 guidelines by running
339 $ python x.py test src/tools/tidy
341 Make this check before every pull request (and every new commit in a pull
342 request) ; you can add [git hooks](https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks)
343 before every push to make sure you never forget to make this check.
345 All pull requests are reviewed by another person. We have a bot,
346 @rust-highfive, that will automatically assign a random person to review your
349 If you want to request that a specific person reviews your pull request,
350 you can add an `r?` to the message. For example, Steve usually reviews
351 documentation changes. So if you were to make a documentation change, add
355 to the end of the message, and @rust-highfive will assign @steveklabnik instead
356 of a random person. This is entirely optional.
358 After someone has reviewed your pull request, they will leave an annotation
359 on the pull request with an `r+`. It will look something like this:
363 This tells @bors, our lovable integration bot, that your pull request has
364 been approved. The PR then enters the [merge queue][merge-queue], where @bors
365 will run all the tests on every platform we support. If it all works out,
366 @bors will merge your code into `master` and close the pull request.
368 [merge-queue]: https://buildbot2.rust-lang.org/homu/queue/rust
370 Speaking of tests, Rust has a comprehensive test suite. More information about
371 it can be found [here][rctd].
373 ### External Dependencies
374 [external-dependencies]: #external-dependencies
376 Currently building Rust will also build the following external projects:
378 * [clippy](https://github.com/rust-lang-nursery/rust-clippy)
379 * [miri](https://github.com/solson/miri)
380 * [rustfmt](https://github.com/rust-lang-nursery/rustfmt)
381 * [rls](https://github.com/rust-lang-nursery/rls/)
383 We allow breakage of these tools in the nightly channel. Maintainers of these
384 projects will be notified of the breakages and should fix them as soon as
387 After the external is fixed, one could add the changes with
390 git add path/to/submodule
393 outside the submodule.
395 In order to prepare your tool-fixing PR, you can run the build locally by doing
396 `./x.py build src/tools/TOOL`. If you will be editing the sources
397 there, you may wish to set `submodules = false` in the `config.toml`
398 to prevent `x.py` from resetting to the original branch.
400 Breakage is not allowed in the beta and stable channels, and must be addressed
401 before the PR is merged.
403 #### Breaking Tools Built With The Compiler
404 [breaking-tools-built-with-the-compiler]: #breaking-tools-built-with-the-compiler
406 Rust's build system builds a number of tools that make use of the
407 internals of the compiler. This includes
408 [Clippy](https://github.com/rust-lang-nursery/rust-clippy),
409 [RLS](https://github.com/rust-lang-nursery/rls) and
410 [rustfmt](https://github.com/rust-lang-nursery/rustfmt). If these tools
411 break because of your changes, you may run into a sort of "chicken and egg"
412 problem. These tools rely on the latest compiler to be built so you can't update
413 them to reflect your changes to the compiler until those changes are merged into
414 the compiler. At the same time, you can't get your changes merged into the compiler
415 because the rust-lang/rust build won't pass until those tools build and pass their
418 That means that, in the default state, you can't update the compiler without first
419 fixing rustfmt, rls and the other tools that the compiler builds.
421 Luckily, a feature was [added to Rust's build](https://github.com/rust-lang/rust/issues/45861)
422 to make all of this easy to handle. The idea is that we allow these tools to be "broken",
423 so that the rust-lang/rust build passes without trying to build them, then land the change
424 in the compiler, wait for a nightly, and go update the tools that you broke. Once you're done
425 and the tools are working again, you go back in the compiler and update the tools
426 so they can be distributed again.
428 This should avoid a bunch of synchronization dances and is also much easier on contributors as
429 there's no need to block on rls/rustfmt/other tools changes going upstream.
431 Here are those same steps in detail:
433 1. (optional) First, if it doesn't exist already, create a `config.toml` by copying
434 `config.toml.example` in the root directory of the Rust repository.
435 Set `submodules = false` in the `[build]` section. This will prevent `x.py`
436 from resetting to the original branch after you make your changes. If you
437 need to [update any submodules to their latest versions][updating-submodules],
438 see the section of this file about that for more information.
439 2. (optional) Run `./x.py test src/tools/rustfmt` (substituting the submodule
440 that broke for `rustfmt`). Fix any errors in the submodule (and possibly others).
441 3. (optional) Make commits for your changes and send them to upstream repositories as a PR.
442 4. (optional) Maintainers of these submodules will **not** merge the PR. The PR can't be
443 merged because CI will be broken. You'll want to write a message on the PR referencing
444 your change, and how the PR should be merged once your change makes it into a nightly.
445 5. Wait for your PR to merge.
446 6. Wait for a nightly
447 7. (optional) Help land your PR on the upstream repository now that your changes are in nightly.
448 8. (optional) Send a PR to rust-lang/rust updating the submodule.
450 #### Updating submodules
451 [updating-submodules]: #updating-submodules
453 These instructions are specific to updating `rustfmt`, however they may apply
454 to the other submodules as well. Please help by improving these instructions
455 if you find any discrepancies or special cases that need to be addressed.
457 To update the `rustfmt` submodule, start by running the appropriate
458 [`git submodule` command](https://git-scm.com/book/en/v2/Git-Tools-Submodules).
459 For example, to update to the latest commit on the remote master branch,
462 git submodule update --remote src/tools/rustfmt
464 If you run `./x.py build` now, and you are lucky, it may just work. If you see
465 an error message about patches that did not resolve to any crates, you will need
466 to complete a few more steps which are outlined with their rationale below.
468 *(This error may change in the future to include more information.)*
470 error: failed to resolve patches for `https://github.com/rust-lang-nursery/rustfmt`
473 patch for `rustfmt-nightly` in `https://github.com/rust-lang-nursery/rustfmt` did not resolve to any crates
474 failed to run: ~/rust/build/x86_64-unknown-linux-gnu/stage0/bin/cargo build --manifest-path ~/rust/src/bootstrap/Cargo.toml
477 If you haven't used the `[patch]`
478 section of `Cargo.toml` before, there is [some relevant documentation about it
479 in the cargo docs](http://doc.crates.io/manifest.html#the-patch-section). In
480 addition to that, you should read the
481 [Overriding dependencies](http://doc.crates.io/specifying-dependencies.html#overriding-dependencies)
482 section of the documentation as well.
484 Specifically, the following [section in Overriding dependencies](http://doc.crates.io/specifying-dependencies.html#testing-a-bugfix) reveals what the problem is:
486 > Next up we need to ensure that our lock file is updated to use this new version of uuid so our project uses the locally checked out copy instead of one from crates.io. The way [patch] works is that it'll load the dependency at ../path/to/uuid and then whenever crates.io is queried for versions of uuid it'll also return the local version.
488 > This means that the version number of the local checkout is significant and will affect whether the patch is used. Our manifest declared uuid = "1.0" which means we'll only resolve to >= 1.0.0, < 2.0.0, and Cargo's greedy resolution algorithm also means that we'll resolve to the maximum version within that range. Typically this doesn't matter as the version of the git repository will already be greater or match the maximum version published on crates.io, but it's important to keep this in mind!
490 This says that when we updated the submodule, the version number in our
491 `src/tools/rustfmt/Cargo.toml` changed. The new version is different from
492 the version in `Cargo.lock`, so the build can no longer continue.
494 To resolve this, we need to update `Cargo.lock`. Luckily, cargo provides a
495 command to do this easily.
498 $ cargo update -p rustfmt-nightly
501 This should change the version listed in `Cargo.lock` to the new version you updated
502 the submodule to. Running `./x.py build` should work now.
504 ## Writing Documentation
505 [writing-documentation]: #writing-documentation
507 Documentation improvements are very welcome. The source of `doc.rust-lang.org`
508 is located in `src/doc` in the tree, and standard API documentation is generated
509 from the source code itself.
511 Documentation pull requests function in the same way as other pull requests,
512 though you may see a slightly different form of `r+`:
514 @bors: r+ 38fe8d2 rollup
516 That additional `rollup` tells @bors that this change is eligible for a 'rollup'.
517 To save @bors some work, and to get small changes through more quickly, when
518 @bors attempts to merge a commit that's rollup-eligible, it will also merge
519 the other rollup-eligible patches too, and they'll get tested and merged at
522 To find documentation-related issues, sort by the [T-doc label][tdoc].
524 [tdoc]: https://github.com/rust-lang/rust/issues?q=is%3Aopen%20is%3Aissue%20label%3AT-doc
526 You can find documentation style guidelines in [RFC 1574][rfc1574].
528 [rfc1574]: https://github.com/rust-lang/rfcs/blob/master/text/1574-more-api-documentation-conventions.md#appendix-a-full-conventions-text
530 In many cases, you don't need a full `./x.py doc`. You can use `rustdoc` directly
531 to check small fixes. For example, `rustdoc src/doc/reference.md` will render
532 reference to `doc/reference.html`. The CSS might be messed up, but you can
533 verify that the HTML is right.
536 [issue-triage]: #issue-triage
538 Sometimes, an issue will stay open, even though the bug has been fixed. And
539 sometimes, the original bug may go stale because something has changed in the
542 It can be helpful to go through older bug reports and make sure that they are
543 still valid. Load up an older issue, double check that it's still true, and
544 leave a comment letting us know if it is or is not. The [least recently
545 updated sort][lru] is good for finding issues like this.
547 Contributors with sufficient permissions on the Rust repo can help by adding
548 labels to triage issues:
550 * Yellow, **A**-prefixed labels state which **area** of the project an issue
553 * Magenta, **B**-prefixed labels identify bugs which are **blockers**.
555 * Dark blue, **beta-** labels track changes which need to be backported into
558 * Light purple, **C**-prefixed labels represent the **category** of an issue.
560 * Green, **E**-prefixed labels explain the level of **experience** necessary
563 * The dark blue **final-comment-period** label marks bugs that are using the
564 RFC signoff functionality of [rfcbot][rfcbot] and are currently in the final
567 * Red, **I**-prefixed labels indicate the **importance** of the issue. The
568 [I-nominated][inom] label indicates that an issue has been nominated for
569 prioritizing at the next triage meeting.
571 * The purple **metabug** label marks lists of bugs collected by other
574 * Purple gray, **O**-prefixed labels are the **operating system** or platform
575 that this issue is specific to.
577 * Orange, **P**-prefixed labels indicate a bug's **priority**. These labels
578 are only assigned during triage meetings, and replace the [I-nominated][inom]
581 * The gray **proposed-final-comment-period** label marks bugs that are using
582 the RFC signoff functionality of [rfcbot][rfcbot] and are currently awaiting
583 signoff of all team members in order to enter the final comment period.
585 * Pink, **regression**-prefixed labels track regressions from stable to the
588 * The light orange **relnotes** label marks issues that should be documented in
589 the release notes of the next release.
591 * Gray, **S**-prefixed labels are used for tracking the **status** of pull
594 * Blue, **T**-prefixed bugs denote which **team** the issue belongs to.
596 If you're looking for somewhere to start, check out the [E-easy][eeasy] tag.
598 [inom]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AI-nominated
599 [eeasy]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AE-easy
600 [lru]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-asc
601 [rfcbot]: https://github.com/anp/rfcbot-rs/
603 ## Out-of-tree Contributions
604 [out-of-tree-contributions]: #out-of-tree-contributions
606 There are a number of other ways to contribute to Rust that don't deal with
609 Answer questions in [#rust][pound-rust], or on [users.rust-lang.org][users],
610 or on [StackOverflow][so].
612 Participate in the [RFC process](https://github.com/rust-lang/rfcs).
614 Find a [requested community library][community-library], build it, and publish
615 it to [Crates.io](http://crates.io). Easier said than done, but very, very
618 [pound-rust]: http://chat.mibbit.com/?server=irc.mozilla.org&channel=%23rust
619 [users]: https://users.rust-lang.org/
620 [so]: http://stackoverflow.com/questions/tagged/rust
621 [community-library]: https://github.com/rust-lang/rfcs/labels/A-community-library
623 ## Helpful Links and Information
624 [helpful-info]: #helpful-info
626 For people new to Rust, and just starting to contribute, or even for
627 more seasoned developers, some useful places to look for information
630 * The [rustc guide] contains information about how various parts of the compiler work
631 * [Rust Forge][rustforge] contains additional documentation, including write-ups of how to achieve common tasks
632 * The [Rust Internals forum][rif], a place to ask questions and
633 discuss Rust's internals
634 * The [generated documentation for rust's compiler][gdfrustc]
635 * The [rust reference][rr], even though it doesn't specifically talk about Rust's internals, it's a great resource nonetheless
636 * Although out of date, [Tom Lee's great blog article][tlgba] is very helpful
637 * [rustaceans.org][ro] is helpful, but mostly dedicated to IRC
638 * The [Rust Compiler Testing Docs][rctd]
639 * For @bors, [this cheat sheet][cheatsheet] is helpful (Remember to replace `@homu` with `@bors` in the commands that you use.)
640 * **Google!** ([search only in Rust Documentation][gsearchdocs] to find types, traits, etc. quickly)
641 * Don't be afraid to ask! The Rust community is friendly and helpful.
643 [rustc guide]: https://rust-lang.github.io/rustc-guide/about-this-guide.html
644 [gdfrustc]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/
645 [gsearchdocs]: https://www.google.com/search?q=site:doc.rust-lang.org+your+query+here
646 [rif]: http://internals.rust-lang.org
647 [rr]: https://doc.rust-lang.org/book/README.html
648 [rustforge]: https://forge.rust-lang.org/
649 [tlgba]: http://tomlee.co/2014/04/a-more-detailed-tour-of-the-rust-compiler/
650 [ro]: http://www.rustaceans.org/
651 [rctd]: https://rust-lang.github.io/rustc-guide/tests/intro.html
652 [cheatsheet]: https://buildbot2.rust-lang.org/homu/