-## High level approach
-
-1. Find something to fix/improve
-2. Change code (likely some file in `clippy_lints/src/`)
-3. Follow the instructions in the [Basics docs](book/src/development/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 someone from the
-Clippy team directly by mentioning them in the issue or over on [Zulip]. All
-currently active team members 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
-
-## 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
-
-## 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