src/tools/clippy/CONTRIBUTING.md - rust - Git at Google


            
            # Contributing to Clippy


            Hello fellow Rustacean! Great to see your interest in compiler internals and lints!


            **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.


            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].


            All contributors are expected to follow the [Rust Code of Conduct].


            - [Contributing to Clippy](#contributing-to-clippy)

            
              - [The Clippy book](#the-clippy-book)

            
              - [High level approach](#high-level-approach)

            
              - [Finding something to fix/improve](#finding-something-to-fiximprove)

            
              - [Getting code-completion for rustc internals to work](#getting-code-completion-for-rustc-internals-to-work)

            
                - [RustRover](#rustrover)

            
                - [Rust Analyzer](#rust-analyzer)

            
              - [How Clippy works](#how-clippy-works)

            
              - [Issue and PR triage](#issue-and-pr-triage)

            
              - [Contributions](#contributions)

            
              - [License](#license)


            [Zulip]: https://rust-lang.zulipchat.com/#narrow/stream/clippy

            
            [Rust Code of Conduct]: https://www.rust-lang.org/policies/code-of-conduct


            ## The Clippy book


            If you're new to Clippy and don't know where to start, the [Clippy book] includes

            
            a [developer guide] and is a good place to start your journey.


            [Clippy book]: https://doc.rust-lang.org/nightly/clippy/index.html

            
            [developer guide]: https://doc.rust-lang.org/nightly/clippy/development/index.html


            ## 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/rust-clippy/blob/master/triagebot.toml#L18)


            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).


            [`good first issue`]: https://github.com/rust-lang/rust-clippy/labels/good%20first%20issue

            
            [`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


            ### RustRover

            
            Unfortunately, [`RustRover`][RustRover_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 `RustRover` 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 `RustRover` 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/

            
            [RustRover_homepage]: https://www.jetbrains.com/rust/


            ### Rust Analyzer

            
            For [`rust-analyzer`][ra_homepage] to work correctly make sure that in the `rust-analyzer` configuration you set


            ```json

            
            { "rust-analyzer.rustc.source": "discover" }

            
            ```


            You should be able to see information on things like `Expr` or `EarlyContext` now if you hover them, also

            
            a lot more type hints.


            To have `rust-analyzer` also work in the `clippy_dev` and `lintcheck` crates, add the following configuration


            ```json

            
            {

            
                "rust-analyzer.linkedProjects": [

            
                    "./Cargo.toml",

            
                    "clippy_dev/Cargo.toml",

            
                    "lintcheck/Cargo.toml",

            
                ]

            
            }

            
            ```


            [ra_homepage]: https://rust-analyzer.github.io/


            ## 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_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {

            
                // ...

            
                store.register_early_pass(|| Box::new(else_if_without_else::ElseIfWithoutElse));

            
                // ...

            
            }

            
            ```


            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.


            To find things to fix, go to the [tracking issue][tracking_issue], find an issue that you like,

            
            and claim it with `@rustbot claim`.


            As a general metric and always taking into account your skill and knowledge level, you can use this guide:


            - 🟥 [ICEs][search_ice], these are compiler errors that causes Clippy to panic and crash. Usually involves high-level

            
            debugging, sometimes interacting directly with the upstream compiler. Difficult to fix but a great challenge that

            
            improves a lot developer workflows!


            - 🟧 [Suggestion causes bug][sugg_causes_bug], Clippy suggested code that changed logic in some silent way.

            
            Unacceptable, as this may have disastrous consequences. Easier to fix than ICEs


            - 🟨 [Suggestion causes error][sugg_causes_error], Clippy suggested code snippet that caused a compiler error

            
            when applied. We need to make sure that Clippy doesn't suggest using a variable twice at the same time or similar

            
            easy-to-happen occurrences.


            - 🟩 [False positives][false_positive], a lint should not have fired, the easiest of them all, as this is "just"

            
            identifying the root of a false positive and making an exception for those cases.


            Note that false negatives do not have priority unless the case is very clear, as they are a feature-request in a

            
            trench coat.


            [triage]: https://forge.rust-lang.org/release/triage-procedure.html

            
            [search_ice]: https://github.com/rust-lang/rust-clippy/issues?q=sort%3Aupdated-desc+state%3Aopen+label%3A%22I-ICE%22

            
            [sugg_causes_bug]: https://github.com/rust-lang/rust-clippy/issues?q=sort%3Aupdated-desc%20state%3Aopen%20label%3AI-suggestion-causes-bug

            
            [sugg_causes_error]: https://github.com/rust-lang/rust-clippy/issues?q=sort%3Aupdated-desc%20state%3Aopen%20label%3AI-suggestion-causes-error%20

            
            [false_positive]: https://github.com/rust-lang/rust-clippy/issues?q=sort%3Aupdated-desc%20state%3Aopen%20label%3AI-false-positive

            
            [tracking_issue]: https://github.com/rust-lang/rust-clippy/issues/15086


            ## 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 PRs should include a `changelog` entry with a short comment explaining the change. The rule of thumb is basically,

            
            "what do you believe is important from an outsider's perspective?" Often, PRs are only related to a single property of a

            
            lint, and then it's good to mention that one. Otherwise, it's better to include too much detail than too little.


            Clippy's [changelog] is created from these comments. Every release, someone gets all merge commits with a

            
            `changelog: XYZ` entry and combines them into the changelog. This is a manual process.


            Examples:

            
            - New lint

            
              ```

            
              changelog: new lint: [`missing_trait_methods`]

            
              ```

            
            - False positive fix

            
              ```

            
              changelog: Fix [`unused_peekable`] false positive when peeked in a closure or called as `f(&mut peekable)`

            
              ```

            
            - Purely internal change

            
              ```

            
              changelog: none

            
              ```


            Note this it is fine for a PR to include multiple `changelog` entries, e.g.:

            
            ```

            
            changelog: Something 1

            
            changelog: Something 2

            
            changelog: Something 3

            
            ```


            [changelog]: CHANGELOG.md


            ## License


            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 Clippy

	Hello fellow Rustacean! Great to see your interest in compiler internals and lints!

	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.

	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].

	All contributors are expected to follow the [Rust Code of Conduct].

	- [Contributing to Clippy](#contributing-to-clippy)
	- [The Clippy book](#the-clippy-book)
	- [High level approach](#high-level-approach)
	- [Finding something to fix/improve](#finding-something-to-fiximprove)
	- [Getting code-completion for rustc internals to work](#getting-code-completion-for-rustc-internals-to-work)
	- [RustRover](#rustrover)
	- [Rust Analyzer](#rust-analyzer)
	- [How Clippy works](#how-clippy-works)
	- [Issue and PR triage](#issue-and-pr-triage)
	- [Contributions](#contributions)
	- [License](#license)

	[Zulip]: https://rust-lang.zulipchat.com/#narrow/stream/clippy
	[Rust Code of Conduct]: https://www.rust-lang.org/policies/code-of-conduct

	## The Clippy book

	If you're new to Clippy and don't know where to start, the [Clippy book] includes
	a [developer guide] and is a good place to start your journey.

	[Clippy book]: https://doc.rust-lang.org/nightly/clippy/index.html
	[developer guide]: https://doc.rust-lang.org/nightly/clippy/development/index.html

	## 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/rust-clippy/blob/master/triagebot.toml#L18)

	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).

	[`good first issue`]: https://github.com/rust-lang/rust-clippy/labels/good%20first%20issue
	[`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

	### RustRover
	Unfortunately, [`RustRover`][RustRover_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 `RustRover` 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 `RustRover` 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/
	[RustRover_homepage]: https://www.jetbrains.com/rust/

	### Rust Analyzer
	For [`rust-analyzer`][ra_homepage] to work correctly make sure that in the `rust-analyzer` configuration you set

	```json
	{ "rust-analyzer.rustc.source": "discover" }
	```

	You should be able to see information on things like `Expr` or `EarlyContext` now if you hover them, also
	a lot more type hints.

	To have `rust-analyzer` also work in the `clippy_dev` and `lintcheck` crates, add the following configuration

	```json
	{
	"rust-analyzer.linkedProjects": [
	"./Cargo.toml",
	"clippy_dev/Cargo.toml",
	"lintcheck/Cargo.toml",
	]
	}
	```

	[ra_homepage]: https://rust-analyzer.github.io/

	## 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_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
	// ...
	store.register_early_pass(\|\| Box::new(else_if_without_else::ElseIfWithoutElse));
	// ...
	}
	```

	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.

	To find things to fix, go to the [tracking issue][tracking_issue], find an issue that you like,
	and claim it with `@rustbot claim`.

	As a general metric and always taking into account your skill and knowledge level, you can use this guide:

	- 🟥 [ICEs][search_ice], these are compiler errors that causes Clippy to panic and crash. Usually involves high-level
	debugging, sometimes interacting directly with the upstream compiler. Difficult to fix but a great challenge that
	improves a lot developer workflows!

	- 🟧 [Suggestion causes bug][sugg_causes_bug], Clippy suggested code that changed logic in some silent way.
	Unacceptable, as this may have disastrous consequences. Easier to fix than ICEs

	- 🟨 [Suggestion causes error][sugg_causes_error], Clippy suggested code snippet that caused a compiler error
	when applied. We need to make sure that Clippy doesn't suggest using a variable twice at the same time or similar
	easy-to-happen occurrences.

	- 🟩 [False positives][false_positive], a lint should not have fired, the easiest of them all, as this is "just"
	identifying the root of a false positive and making an exception for those cases.

	Note that false negatives do not have priority unless the case is very clear, as they are a feature-request in a
	trench coat.

	[triage]: https://forge.rust-lang.org/release/triage-procedure.html
	[search_ice]: https://github.com/rust-lang/rust-clippy/issues?q=sort%3Aupdated-desc+state%3Aopen+label%3A%22I-ICE%22
	[sugg_causes_bug]: https://github.com/rust-lang/rust-clippy/issues?q=sort%3Aupdated-desc%20state%3Aopen%20label%3AI-suggestion-causes-bug
	[sugg_causes_error]: https://github.com/rust-lang/rust-clippy/issues?q=sort%3Aupdated-desc%20state%3Aopen%20label%3AI-suggestion-causes-error%20
	[false_positive]: https://github.com/rust-lang/rust-clippy/issues?q=sort%3Aupdated-desc%20state%3Aopen%20label%3AI-false-positive
	[tracking_issue]: https://github.com/rust-lang/rust-clippy/issues/15086

	## 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 PRs should include a `changelog` entry with a short comment explaining the change. The rule of thumb is basically,
	"what do you believe is important from an outsider's perspective?" Often, PRs are only related to a single property of a
	lint, and then it's good to mention that one. Otherwise, it's better to include too much detail than too little.

	Clippy's [changelog] is created from these comments. Every release, someone gets all merge commits with a
	`changelog: XYZ` entry and combines them into the changelog. This is a manual process.

	Examples:
	- New lint
	```
	changelog: new lint: [`missing_trait_methods`]
	```
	- False positive fix
	```
	changelog: Fix [`unused_peekable`] false positive when peeked in a closure or called as `f(&mut peekable)`
	```
	- Purely internal change
	```
	changelog: none
	```

	Note this it is fine for a PR to include multiple `changelog` entries, e.g.:
	```
	changelog: Something 1
	changelog: Something 2
	changelog: Something 3
	```

	[changelog]: CHANGELOG.md

	## License

	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