CONTRIBUTING.md

   1 # Contributing to Cargo
   2
   3 Thank you for your interest in contributing to Cargo! Good places to
   4 start are this document, [ARCHITECTURE.md](ARCHITECTURE.md), which
   5 describes the high-level structure of Cargo and [E-easy] bugs on the
   6 issue tracker.
   7
   8 If you have a general question about Cargo or it's internals, feel free to ask
   9 on [IRC].
  10
  11 ## Code of Conduct
  12
  13 All contributors are expected to follow our [Code of Conduct].
  14
  15 ## Bug reports
  16
  17 We can't fix what we don't know about, so please report problems liberally. This
  18 includes problems with understanding the documentation, unhelpful error messages
  19 and unexpected behavior.
  20
  21 **If you think that you have identified an issue with Cargo that might compromise
  22 its users' security, please do not open a public issue on GitHub. Instead,
  23 we ask you to refer to Rust's [security policy].**
  24
  25 Opening an issue is as easy as following [this link][new-issues] and filling out
  26 the fields. Here's a template that you can use to file an issue, though it's not
  27 necessary to use it exactly:
  28
  29     <short summary of the problem>
  30
  31     I tried this: <minimal example that causes the problem>
  32
  33     I expected to see this happen: <explanation>
  34
  35     Instead, this happened: <explanation>
  36
  37     I'm using <output of `cargo --version`>
  38
  39 All three components are important: what you did, what you expected, what
  40 happened instead. Please use https://gist.github.com/ if your examples run long.
  41
  42
  43 ## Feature requests
  44
  45 Cargo follows the general Rust model of evolution. All major features go through
  46 an RFC process. Therefore, before opening a feature request issue create a
  47 Pre-RFC thread on the [internals][irlo] forum to get preliminary feedback.
  48 Implementing a feature as a [custom subcommand][subcommands] is encouraged as it
  49 helps demonstrate the demand for the functionality and is a great way to deliver
  50 a working solution faster as it can iterate outside of cargo's release cadence.
  51
  52 ## Working on issues
  53
  54 If you're looking for somewhere to start, check out the [E-easy][E-Easy] and
  55 [E-mentor][E-mentor] tags.
  56
  57 Feel free to ask for guidelines on how to tackle a problem on [IRC] or open a
  58 [new issue][new-issues]. This is especially important if you want to add new
  59 features to Cargo or make large changes to the already existing code-base.
  60 Cargo's core developers will do their best to provide help.
  61
  62 If you start working on an already-filed issue, post a comment on this issue to
  63 let people know that somebody is working it. Feel free to ask for comments if
  64 you are unsure about the solution you would like to submit.
  65
  66 While Cargo does make use of some Rust-features available only through the
  67 `nightly` toolchain, it must compile on stable Rust. Code added to Cargo
  68 is encouraged to make use of the latest stable features of the language and
  69 `stdlib`.
  70
  71 We use the "fork and pull" model [described here][development-models], where
  72 contributors push changes to their personal fork and create pull requests to
  73 bring those changes into the source repository. This process is partly
  74 automated: Pull requests are made against Cargo's master-branch, tested and
  75 reviewed. Once a change is approved to be merged, a friendly bot merges the
  76 changes into an internal branch, runs the full test-suite on that branch
  77 and only then merges into master. This ensures that Cargo's master branch
  78 passes the test-suite at all times.
  79
  80 Your basic steps to get going:
  81
  82 * Fork Cargo and create a branch from master for the issue you are working on.
  83 * Please adhere to the code style that you see around the location you are
  84 working on.
  85 * [Commit as you go][githelp].
  86 * Include tests that cover all non-trivial code. The existing tests
  87 in `test/` provide templates on how to test Cargo's behavior in a
  88 sandbox-environment. The internal module `testsuite/support` provides a vast amount
  89 of helpers to minimize boilerplate.  See [`testsuite/support/mod.rs`] for an
  90 introduction to writing tests.
  91 * Make sure `cargo test` passes. If you do not have the cross-compilers
  92 installed locally, install them using the instructions returned by
  93 `cargo test cross_compile::cross_tests` (twice, with `--toolchain nightly`
  94 added to get the nightly cross target too); alternatively just
  95 ignore the cross-compile test failures or disable them by
  96 using `CFG_DISABLE_CROSS_TESTS=1 cargo test`. Note that some tests are enabled
  97 only on `nightly` toolchain. If you can, test both toolchains.
  98 * All code changes are expected to comply with the formatting suggested by `rustfmt`.
  99 You can use `rustup component add --toolchain nightly rustfmt-preview` to install `rustfmt` and use
 100 `rustfmt +nightly --unstable-features --skip-children` on the changed files to automatically format your code.
 101 * Push your commits to GitHub and create a pull request against Cargo's
 102 `master` branch.
 103
 104 ## Pull requests
 105
 106 After the pull request is made, a friendly bot will automatically assign a
 107 reviewer; the review-process will make sure that the proposed changes are
 108 sound. Please give the assigned reviewer sufficient time, especially during
 109 weekends. If you don't get a reply, you may poke the core developers on [IRC].
 110
 111 A merge of Cargo's master-branch and your changes is immediately queued
 112 to be tested after the pull request is made. In case unforeseen
 113 problems are discovered during this step (e.g. a failure on a platform you
 114 originally did not develop on), you may ask for guidance. Push additional
 115 commits to your branch to tackle these problems.
 116
 117 The reviewer might point out changes deemed necessary. Please add them as
 118 extra commits; this ensures that the reviewer can see what has changed since
 119 the code was previously reviewed. Large or tricky changes may require several
 120 passes of review and changes.
 121
 122 Once the reviewer approves your pull request, a friendly bot picks it up
 123 and [merges][mergequeue] it into Cargo's `master` branch.
 124
 125 ## Contributing to the documentation
 126
 127 To contribute to the documentation, all you need to do is change the markdown
 128 files in the `src/doc` directory. To view the rendered version of changes you
 129 have made locally, make sure you have `mdbook` installed and run:
 130
 131 ```sh
 132 cd src/doc
 133 mdbook build
 134 open book/index.html
 135 ```
 136
 137 To install `mdbook` run `cargo install mdbook`.
 138
 139
 140 ## Issue Triage
 141
 142 Sometimes an issue will stay open, even though the bug has been fixed. And
 143 sometimes, the original bug may go stale because something has changed in the
 144 meantime.
 145
 146 It can be helpful to go through older bug reports and make sure that they are
 147 still valid. Load up an older issue, double check that it's still true, and
 148 leave a comment letting us know if it is or is not. The [least recently
 149 updated sort][lru] is good for finding issues like this.
 150
 151 Contributors with sufficient permissions on the Rust-repository can help by
 152 adding labels to triage issues:
 153
 154 * Yellow, **A**-prefixed labels state which **area** of the project an issue
 155   relates to.
 156
 157 * Magenta, **B**-prefixed labels identify bugs which are **blockers**.
 158
 159 * Light purple, **C**-prefixed labels represent the **category** of an issue.
 160   In particular, **C-feature-request** marks *proposals* for new features. If
 161   an issue is **C-feature-request**, but is not **Feature accepted** or **I-nominated**,
 162   then it was not thoroughly discussed, and might need some additional design
 163   or perhaps should be implemented as an external subcommand first. Ping
 164   @rust-lang/cargo if you want to send a PR for such issue.
 165
 166 * Dark purple, **Command**-prefixed labels mean the issue has to do with a
 167   specific cargo command.
 168
 169 * Green, **E**-prefixed labels explain the level of **experience** or
 170   **effort** necessary to fix the issue. [**E-mentor**][E-mentor] issues also
 171   have some instructions on how to get started.
 172
 173 * Red, **I**-prefixed labels indicate the **importance** of the issue. The
 174   **[I-nominated][]** label indicates that an issue has been nominated for
 175   prioritizing at the next triage meeting.
 176
 177 * Purple gray, **O**-prefixed labels are the **operating system** or platform
 178   that this issue is specific to.
 179
 180 * Orange, **P**-prefixed labels indicate a bug's **priority**. These labels
 181   are only assigned during triage meetings and replace the **[I-nominated][]**
 182   label.
 183
 184 * The light orange **relnotes** label marks issues that should be documented in
 185   the release notes of the next release.
 186
 187
 188 [githelp]: https://dont-be-afraid-to-commit.readthedocs.io/en/latest/git/commandlinegit.html
 189 [development-models]: https://help.github.com/articles/about-collaborative-development-models/
 190 [gist]: https://gist.github.com/
 191 [new-issues]: https://github.com/rust-lang/cargo/issues/new
 192 [mergequeue]: https://buildbot2.rust-lang.org/homu/queue/cargo
 193 [security policy]: https://www.rust-lang.org/security.html
 194 [lru]: https://github.com/rust-lang/cargo/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-asc
 195 [E-easy]: https://github.com/rust-lang/cargo/labels/E-easy
 196 [E-mentor]: https://github.com/rust-lang/cargo/labels/E-mentor
 197 [I-nominated]: https://github.com/rust-lang/cargo/labels/I-nominated
 198 [Code of Conduct]: https://www.rust-lang.org/conduct.html
 199 [IRC]: https://kiwiirc.com/client/irc.mozilla.org/cargo
 200 [`testsuite/support/mod.rs`]: https://github.com/rust-lang/cargo/blob/master/tests/testsuite/support/mod.rs
 201 [irlo]: https://internals.rust-lang.org/
 202 [subcommands]: https://doc.rust-lang.org/cargo/reference/external-tools.html#custom-subcommands