-# Contributing to Clippy
+# Contributing to Rust
-Hello fellow Rustacean! Great to see your interest in compiler internals and lints!
+Thank you for your interest in contributing to Rust! There are many ways to contribute
+and we appreciate all of them.
-**First**: if you're unsure or afraid of _anything_, just ask or submit the issue or pull request anyway. You won't be
-yelled at for giving it your best effort. The worst that can happen is that you'll be politely asked to change
-something. We appreciate any sort of contributions, and don't want a wall of rules to get in the way of that.
+The best way to get started is by asking for help in the [#new
+members](https://rust-lang.zulipchat.com/#narrow/stream/122652-new-members)
+Zulip stream. We have lots of docs below of how to get started on your own, but
+the Zulip stream is the best place to *ask* for help.
-Clippy welcomes contributions from everyone. There are many ways to contribute to Clippy and the following document
-explains how you can contribute and how to get started. If you have any questions about contributing or need help with
-anything, feel free to ask questions on issues or visit the `#clippy` on [Zulip].
+Documentation for contributing to Rust is located in the [Guide to Rustc Development](https://rustc-dev-guide.rust-lang.org/),
+commonly known as the [rustc-dev-guide]. Despite the name, this guide documents
+not just how to develop rustc (the Rust compiler), but also how to contribute to the standard library and rustdoc.
-All contributors are expected to follow the [Rust Code of Conduct].
+## About the [rustc-dev-guide]
-- [Contributing to Clippy](#contributing-to-clippy)
- - [Getting started](#getting-started)
- - [High level approach](#high-level-approach)
- - [Finding something to fix/improve](#finding-something-to-fiximprove)
- - [Writing code](#writing-code)
- - [Getting code-completion for rustc internals to work](#getting-code-completion-for-rustc-internals-to-work)
- - [IntelliJ Rust](#intellij-rust)
- - [Rust Analyzer](#rust-analyzer)
- - [How Clippy works](#how-clippy-works)
- - [Syncing changes between Clippy and `rust-lang/rust`](#syncing-changes-between-clippy-and-rust-langrust)
- - [Patching git-subtree to work with big repos](#patching-git-subtree-to-work-with-big-repos)
- - [Performing the sync from `rust-lang/rust` to Clippy](#performing-the-sync-from-rust-langrust-to-clippy)
- - [Performing the sync from Clippy to `rust-lang/rust`](#performing-the-sync-from-clippy-to-rust-langrust)
- - [Defining remotes](#defining-remotes)
- - [Issue and PR triage](#issue-and-pr-triage)
- - [Bors and Homu](#bors-and-homu)
- - [Contributions](#contributions)
+The [rustc-dev-guide] is meant to help document how rustc –the Rust compiler– works,
+as well as to help new contributors get involved in rustc development. It is recommend
+to read and understand the [rustc-dev-guide] before making a contribution. This guide
+talks about the different bots in the Rust ecosystem, the Rust development tools,
+bootstrapping, the compiler architecture, source code representation, and more.
-[Zulip]: https://rust-lang.zulipchat.com/#narrow/stream/clippy
-[Rust Code of Conduct]: https://www.rust-lang.org/policies/code-of-conduct
+## [Getting help](https://rustc-dev-guide.rust-lang.org/getting-started.html#asking-questions)
-## Getting started
+There are many ways you can get help when you're stuck. Rust has many platforms for this:
+[internals], [rust-zulip], and [rust-discord]. It is recommended to ask for help on
+the [rust-zulip], but any of these platforms are a great way to seek help and even
+find a mentor! You can learn more about asking questions and getting help in the
+[Asking Questions](https://rustc-dev-guide.rust-lang.org/getting-started.html#asking-questions) chapter of the [rustc-dev-guide].
-**Note: If this is your first time contributing to Clippy, you should
-first read the [Basics docs](doc/basics.md).**
+## Bug reports
-### High level approach
+Did a compiler error message tell you to come here? If you want to create an ICE report,
+refer to [this section][contributing-bug-reports] and [open an issue][issue template].
-1. Find something to fix/improve
-2. Change code (likely some file in `clippy_lints/src/`)
-3. Follow the instructions in the [Basics docs](doc/basics.md) to get set up
-4. Run `cargo test` in the root directory and wiggle code until it passes
-5. Open a PR (also can be done after 2. if you run into problems)
-
-### Finding something to fix/improve
-
-All issues on Clippy are mentored, if you want help simply ask @Manishearth, @flip1995, @phansch
-or @llogiq directly by mentioning them in the issue or over on [Zulip]. This list may be out of date.
-All currently active mentors can be found [here](https://github.com/rust-lang/highfive/blob/master/highfive/configs/rust-lang/rust-clippy.json#L3)
-
-Some issues are easier than others. The [`good-first-issue`] label can be used to find the easy
-issues. You can use `@rustbot claim` to assign the issue to yourself.
-
-There are also some abandoned PRs, marked with [`S-inactive-closed`].
-Pretty often these PRs are nearly completed and just need some extra steps
-(formatting, addressing review comments, ...) to be merged. If you want to
-complete such a PR, please leave a comment in the PR and open a new one based
-on it.
-
-Issues marked [`T-AST`] involve simple matching of the syntax tree structure,
-and are generally easier than [`T-middle`] issues, which involve types
-and resolved paths.
-
-[`T-AST`] issues will generally need you to match against a predefined syntax structure.
-To figure out how this syntax structure is encoded in the AST, it is recommended to run
-`rustc -Z unpretty=ast-tree` on an example of the structure and compare with the [nodes in the AST docs].
-Usually the lint will end up to be a nested series of matches and ifs, [like so][deep-nesting].
-But we can make it nest-less by using [let chains], [like this][nest-less].
-
-[`E-medium`] issues are generally pretty easy too, though it's recommended you work on an [`good-first-issue`]
-first. Sometimes they are only somewhat involved code wise, but not difficult per-se.
-Note that [`E-medium`] issues may require some knowledge of Clippy internals or some
-debugging to find the actual problem behind the issue.
-
-[`T-middle`] issues can be more involved and require verifying types. The [`ty`] module contains a
-lot of methods that are useful, though one of the most useful would be `expr_ty` (gives the type of
-an AST expression). `match_def_path()` in Clippy's `utils` module can also be useful.
-
-[`good-first-issue`]: https://github.com/rust-lang/rust-clippy/labels/good-first-issue
-[`S-inactive-closed`]: https://github.com/rust-lang/rust-clippy/pulls?q=is%3Aclosed+label%3AS-inactive-closed
-[`T-AST`]: https://github.com/rust-lang/rust-clippy/labels/T-AST
-[`T-middle`]: https://github.com/rust-lang/rust-clippy/labels/T-middle
-[`E-medium`]: https://github.com/rust-lang/rust-clippy/labels/E-medium
-[`ty`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty
-[nodes in the AST docs]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_ast/ast/
-[deep-nesting]: https://github.com/rust-lang/rust-clippy/blob/5e4f0922911536f80d9591180fa604229ac13939/clippy_lints/src/mem_forget.rs#L31-L45
-[let chains]: https://github.com/rust-lang/rust/pull/94927
-[nest-less]: https://github.com/rust-lang/rust-clippy/blob/5e4f0922911536f80d9591180fa604229ac13939/clippy_lints/src/bit_mask.rs#L133-L159
-
-## Writing code
-
-Have a look at the [docs for writing lints][adding_lints] for more details.
-
-If you want to add a new lint or change existing ones apart from bugfixing, it's
-also a good idea to give the [stability guarantees][rfc_stability] and
-[lint categories][rfc_lint_cats] sections of the [Clippy 1.0 RFC][clippy_rfc] a
-quick read.
-
-[adding_lints]: https://github.com/rust-lang/rust-clippy/blob/master/doc/adding_lints.md
-[clippy_rfc]: https://github.com/rust-lang/rfcs/blob/master/text/2476-clippy-uno.md
-[rfc_stability]: https://github.com/rust-lang/rfcs/blob/master/text/2476-clippy-uno.md#stability-guarantees
-[rfc_lint_cats]: https://github.com/rust-lang/rfcs/blob/master/text/2476-clippy-uno.md#lint-audit-and-categories
-
-## Getting code-completion for rustc internals to work
-
-### IntelliJ Rust
-Unfortunately, [`IntelliJ Rust`][IntelliJ_rust_homepage] does not (yet?) understand how Clippy uses compiler-internals
-using `extern crate` and it also needs to be able to read the source files of the rustc-compiler which are not
-available via a `rustup` component at the time of writing.
-To work around this, you need to have a copy of the [rustc-repo][rustc_repo] available which can be obtained via
-`git clone https://github.com/rust-lang/rust/`.
-Then you can run a `cargo dev` command to automatically make Clippy use the rustc-repo via path-dependencies
-which `IntelliJ Rust` will be able to understand.
-Run `cargo dev setup intellij --repo-path <repo-path>` where `<repo-path>` is a path to the rustc repo
-you just cloned.
-The command will add path-dependencies pointing towards rustc-crates inside the rustc repo to
-Clippy's `Cargo.toml`s and should allow `IntelliJ Rust` to understand most of the types that Clippy uses.
-Just make sure to remove the dependencies again before finally making a pull request!
-
-[rustc_repo]: https://github.com/rust-lang/rust/
-[IntelliJ_rust_homepage]: https://intellij-rust.github.io/
-
-### Rust Analyzer
-As of [#6869][6869], [`rust-analyzer`][ra_homepage] can understand that Clippy uses compiler-internals
-using `extern crate` when `package.metadata.rust-analyzer.rustc_private` is set to `true` in Clippy's `Cargo.toml.`
-You will require a `nightly` toolchain with the `rustc-dev` component installed.
-Make sure that in the `rust-analyzer` configuration, you set
-```
-{ "rust-analyzer.rustcSource": "discover" }
-```
-and
-```
-{ "rust-analyzer.updates.channel": "nightly" }
-```
-You should be able to see information on things like `Expr` or `EarlyContext` now if you hover them, also
-a lot more type hints.
-This will work with `rust-analyzer 2021-03-15` shipped in nightly `1.52.0-nightly (107896c32 2021-03-15)` or later.
-
-[ra_homepage]: https://rust-analyzer.github.io/
-[6869]: https://github.com/rust-lang/rust-clippy/pull/6869
-
-## How Clippy works
-
-[`clippy_lints/src/lib.rs`][lint_crate_entry] imports all the different lint modules and registers in the [`LintStore`].
-For example, the [`else_if_without_else`][else_if_without_else] lint is registered like this:
-
-```rust
-// ./clippy_lints/src/lib.rs
-
-// ...
-pub mod else_if_without_else;
-// ...
-
-pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: &Conf) {
- // ...
- store.register_early_pass(|| box else_if_without_else::ElseIfWithoutElse);
- // ...
-
- store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
- // ...
- LintId::of(&else_if_without_else::ELSE_IF_WITHOUT_ELSE),
- // ...
- ]);
-}
-```
-
-The [`rustc_lint::LintStore`][`LintStore`] provides two methods to register lints:
-[register_early_pass][reg_early_pass] and [register_late_pass][reg_late_pass]. Both take an object
-that implements an [`EarlyLintPass`][early_lint_pass] or [`LateLintPass`][late_lint_pass] respectively. This is done in
-every single lint. It's worth noting that the majority of `clippy_lints/src/lib.rs` is autogenerated by `cargo dev
-update_lints`. When you are writing your own lint, you can use that script to save you some time.
-
-```rust
-// ./clippy_lints/src/else_if_without_else.rs
-
-use rustc_lint::{EarlyLintPass, EarlyContext};
-
-// ...
-
-pub struct ElseIfWithoutElse;
-
-// ...
-
-impl EarlyLintPass for ElseIfWithoutElse {
- // ... the functions needed, to make the lint work
-}
-```
-
-The difference between `EarlyLintPass` and `LateLintPass` is that the methods of the `EarlyLintPass` trait only provide
-AST information. The methods of the `LateLintPass` trait are executed after type checking and contain type information
-via the `LateContext` parameter.
-
-That's why the `else_if_without_else` example uses the `register_early_pass` function. Because the
-[actual lint logic][else_if_without_else] does not depend on any type information.
-
-[lint_crate_entry]: https://github.com/rust-lang/rust-clippy/blob/master/clippy_lints/src/lib.rs
-[else_if_without_else]: https://github.com/rust-lang/rust-clippy/blob/4253aa7137cb7378acc96133c787e49a345c2b3c/clippy_lints/src/else_if_without_else.rs
-[`LintStore`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint/struct.LintStore.html
-[reg_early_pass]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint/struct.LintStore.html#method.register_early_pass
-[reg_late_pass]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint/struct.LintStore.html#method.register_late_pass
-[early_lint_pass]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint/trait.EarlyLintPass.html
-[late_lint_pass]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint/trait.LateLintPass.html
-
-## Syncing changes between Clippy and [`rust-lang/rust`]
-
-Clippy currently gets built with a pinned nightly version.
-
-In the `rust-lang/rust` repository, where rustc resides, there's a copy of Clippy
-that compiler hackers modify from time to time to adapt to changes in the unstable
-API of the compiler.
-
-We need to sync these changes back to this repository periodically, and the changes
-made to this repository in the meantime also need to be synced to the `rust-lang/rust` repository.
-
-To avoid flooding the `rust-lang/rust` PR queue, this two-way sync process is done
-in a bi-weekly basis if there's no urgent changes. This is done starting on the day of
-the Rust stable release and then every other week. That way we guarantee that we keep
-this repo up to date with the latest compiler API, and every feature in Clippy is available
-for 2 weeks in nightly, before it can get to beta. For reference, the first sync
-following this cadence was performed the 2020-08-27.
-
-This process is described in detail in the following sections. For general information
-about `subtree`s in the Rust repository see [Rust's `CONTRIBUTING.md`][subtree].
-
-### Patching git-subtree to work with big repos
-
-Currently, there's a bug in `git-subtree` that prevents it from working properly
-with the [`rust-lang/rust`] repo. There's an open PR to fix that, but it's stale.
-Before continuing with the following steps, we need to manually apply that fix to
-our local copy of `git-subtree`.
-
-You can get the patched version of `git-subtree` from [here][gitgitgadget-pr].
-Put this file under `/usr/lib/git-core` (taking a backup of the previous file)
-and make sure it has the proper permissions:
-
-```bash
-sudo cp --backup /path/to/patched/git-subtree.sh /usr/lib/git-core/git-subtree
-sudo chmod --reference=/usr/lib/git-core/git-subtree~ /usr/lib/git-core/git-subtree
-sudo chown --reference=/usr/lib/git-core/git-subtree~ /usr/lib/git-core/git-subtree
-```
-
-_Note:_ The first time running `git subtree push` a cache has to be built. This
-involves going through the complete Clippy history once. For this you have to
-increase the stack limit though, which you can do with `ulimit -s 60000`.
-Make sure to run the `ulimit` command from the same session you call git subtree.
-
-_Note:_ If you are a Debian user, `dash` is the shell used by default for scripts instead of `sh`.
-This shell has a hardcoded recursion limit set to 1000. In order to make this process work,
-you need to force the script to run `bash` instead. You can do this by editing the first
-line of the `git-subtree` script and changing `sh` to `bash`.
-
-### Performing the sync from [`rust-lang/rust`] to Clippy
-
-Here is a TL;DR version of the sync process (all of the following commands have
-to be run inside the `rust` directory):
-
-1. Clone the [`rust-lang/rust`] repository or make sure it is up to date.
-2. Checkout the commit from the latest available nightly. You can get it using `rustup check`.
-3. Sync the changes to the rust-copy of Clippy to your Clippy fork:
- ```bash
- # Make sure to change `your-github-name` to your github name in the following command. Also be
- # sure to either use a net-new branch, e.g. `sync-from-rust`, or delete the branch beforehand
- # because changes cannot be fast forwarded
- git subtree push -P src/tools/clippy git@github.com:your-github-name/rust-clippy sync-from-rust
- ```
-
- _Note:_ This will directly push to the remote repository. You can also push
- to your local copy by replacing the remote address with `/path/to/rust-clippy`
- directory.
-
- _Note:_ Most of the time you have to create a merge commit in the
- `rust-clippy` repo (this has to be done in the Clippy repo, not in the
- rust-copy of Clippy):
- ```bash
- git fetch origin && git fetch upstream
- git checkout sync-from-rust
- git merge upstream/master
- ```
-4. Open a PR to `rust-lang/rust-clippy` and wait for it to get merged (to
- accelerate the process ping the `@rust-lang/clippy` team in your PR and/or
- ~~annoy~~ ask them in the [Zulip] stream.)
-
-### Performing the sync from Clippy to [`rust-lang/rust`]
-
-All of the following commands have to be run inside the `rust` directory.
-
-1. Make sure Clippy itself is up-to-date by following the steps outlined in the previous
-section if necessary.
-
-2. Sync the `rust-lang/rust-clippy` master to the rust-copy of Clippy:
- ```bash
- git checkout -b sync-from-clippy
- git subtree pull -P src/tools/clippy https://github.com/rust-lang/rust-clippy master
- ```
-3. Open a PR to [`rust-lang/rust`]
-
-### Defining remotes
-
-You may want to define remotes, so you don't have to type out the remote
-addresses on every sync. You can do this with the following commands (these
-commands still have to be run inside the `rust` directory):
-
-```bash
-# Set clippy-upstream remote for pulls
-$ git remote add clippy-upstream https://github.com/rust-lang/rust-clippy
-# Make sure to not push to the upstream repo
-$ git remote set-url --push clippy-upstream DISABLED
-# Set clippy-origin remote to your fork for pushes
-$ git remote add clippy-origin git@github.com:your-github-name/rust-clippy
-# Set a local remote
-$ git remote add clippy-local /path/to/rust-clippy
-```
-
-You can then sync with the remote names from above, e.g.:
-
-```bash
-$ git subtree push -P src/tools/clippy clippy-local sync-from-rust
-```
-
-[gitgitgadget-pr]: https://github.com/gitgitgadget/git/pull/493
-[subtree]: https://rustc-dev-guide.rust-lang.org/contributing.html#external-dependencies-subtree
-[`rust-lang/rust`]: https://github.com/rust-lang/rust
-
-## Issue and PR triage
-
-Clippy is following the [Rust triage procedure][triage] for issues and pull
-requests.
-
-However, we are a smaller project with all contributors being volunteers
-currently. Between writing new lints, fixing issues, reviewing pull requests and
-responding to issues there may not always be enough time to stay on top of it
-all.
-
-Our highest priority is fixing [crashes][l-crash] and [bugs][l-bug], for example
-an ICE in a popular crate that many other crates depend on. We don't
-want Clippy to crash on your code and we want it to be as reliable as the
-suggestions from Rust compiler errors.
-
-We have prioritization labels and a sync-blocker label, which are described below.
-- [P-low][p-low]: Requires attention (fix/response/evaluation) by a team member but isn't urgent.
-- [P-medium][p-medium]: Should be addressed by a team member until the next sync.
-- [P-high][p-high]: Should be immediately addressed and will require an out-of-cycle sync or a backport.
-- [L-sync-blocker][l-sync-blocker]: An issue that "blocks" a sync.
-Or rather: before the sync this should be addressed,
-e.g. by removing a lint again, so it doesn't hit beta/stable.
-
-## Bors and Homu
-
-We use a bot powered by [Homu][homu] to help automate testing and landing of pull
-requests in Clippy. The bot's username is @bors.
-
-You can find the Clippy bors queue [here][homu_queue].
-
-If you have @bors permissions, you can find an overview of the available
-commands [here][homu_instructions].
-
-[triage]: https://forge.rust-lang.org/release/triage-procedure.html
-[l-crash]: https://github.com/rust-lang/rust-clippy/labels/L-crash
-[l-bug]: https://github.com/rust-lang/rust-clippy/labels/L-bug
-[p-low]: https://github.com/rust-lang/rust-clippy/labels/P-low
-[p-medium]: https://github.com/rust-lang/rust-clippy/labels/P-medium
-[p-high]: https://github.com/rust-lang/rust-clippy/labels/P-high
-[l-sync-blocker]: https://github.com/rust-lang/rust-clippy/labels/L-sync-blocker
-[homu]: https://github.com/rust-lang/homu
-[homu_instructions]: https://bors.rust-lang.org/
-[homu_queue]: https://bors.rust-lang.org/queue/clippy
-
-## Contributions
-
-Contributions to Clippy should be made in the form of GitHub pull requests. Each pull request will
-be reviewed by a core contributor (someone with permission to land patches) and either landed in the
-main tree or given feedback for changes that would be required.
-
-All code in this repository is under the [Apache-2.0] or the [MIT] license.
-
-<!-- adapted from https://github.com/servo/servo/blob/master/CONTRIBUTING.md -->
-
-[Apache-2.0]: https://www.apache.org/licenses/LICENSE-2.0
-[MIT]: https://opensource.org/licenses/MIT
+[Contributing to Rust]: https://rustc-dev-guide.rust-lang.org/contributing.html#contributing-to-rust
+[rustc-dev-guide]: https://rustc-dev-guide.rust-lang.org/
+[contributing-bug-reports]: https://rustc-dev-guide.rust-lang.org/contributing.html#bug-reports
+[issue template]: https://github.com/rust-lang/rust/issues/new/choose
+[internals]: https://internals.rust-lang.org
+[rust-discord]: http://discord.gg/rust-lang
+[rust-zulip]: https://rust-lang.zulipchat.com
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