-## Adding a new lint
+# Adding a new lint
You are probably here because you want to add a new lint to Clippy. If this is
the first time you're contributing to Clippy, this document guides you through
- [Lint passes](#lint-passes)
- [Emitting a lint](#emitting-a-lint)
- [Adding the lint logic](#adding-the-lint-logic)
+ - [Specifying the lint's minimum supported Rust version (MSRV)](#specifying-the-lints-minimum-supported-rust-version-msrv)
- [Author lint](#author-lint)
- [Documentation](#documentation)
- [Running rustfmt](#running-rustfmt)
- [Debugging](#debugging)
- [PR Checklist](#pr-checklist)
+ - [Adding configuration to a lint](#adding-configuration-to-a-lint)
- [Cheatsheet](#cheatsheet)
-### Setup
+## Setup
-When working on Clippy, you will need the current git master version of rustc,
-which can change rapidly. Make sure you're working near rust-clippy's master,
-and use the `setup-toolchain.sh` script to configure the appropriate toolchain
-for the Clippy directory.
+See the [Basics](basics.md#get-the-code) documentation.
-### Getting Started
+## Getting Started
There is a bit of boilerplate code that needs to be set up when creating a new
lint. Fortunately, you can use the clippy dev tools to handle this for you. We
are naming our new lint `foo_functions` (lints are generally written in snake
case), and we don't need type information so it will have an early pass type
-(more on this later on). To get started on this lint you can run
-`cargo dev new_lint --name=foo_functions --pass=early --category=pedantic`
-(category will default to nursery if not provided). This command will create
-two files: `tests/ui/foo_functions.rs` and `clippy_lints/src/foo_functions.rs`,
-as well as run `cargo dev update_lints` to register the new lint. Next, we'll
-open up these files and add our lint!
+(more on this later on). If you're not sure if the name you chose fits the lint,
+take a look at our [lint naming guidelines][lint_naming]. To get started on this
+lint you can run `cargo dev new_lint --name=foo_functions --pass=early
+--category=pedantic` (category will default to nursery if not provided). This
+command will create two files: `tests/ui/foo_functions.rs` and
+`clippy_lints/src/foo_functions.rs`, as well as run `cargo dev update_lints` to
+register the new lint. For cargo lints, two project hierarchies (fail/pass) will
+be created by default under `tests/ui-cargo`.
-### Testing
+Next, we'll open up these files and add our lint!
+
+## Testing
Let's write some tests first that we can execute while we iterate on our lint.
let a = A;
a.foo();
}
-
```
-Now we can run the test with `TESTNAME=foo_functions cargo uitest`.
-Currently this test will fail. If you go through the output you will see that we
-are told that `clippy::foo_functions` is an unknown lint, which is expected.
+Now we can run the test with `TESTNAME=foo_functions cargo uitest`,
+currently this test is meaningless though.
While we are working on implementing our lint, we can keep running the UI
test. That allows us to check if the output is turning into what we want.
Once we are satisfied with the output, we need to run
-`tests/ui/update-all-references.sh` to update the `.stderr` file for our lint.
+`cargo dev bless` to update the `.stderr` file for our lint.
Please note that, we should run `TESTNAME=foo_functions cargo uitest`
-every time before running `tests/ui/update-all-references.sh`.
+every time before running `cargo dev bless`.
Running `TESTNAME=foo_functions cargo uitest` should pass then. When we commit
-our lint, we need to commit the generated `.stderr` files, too.
+our lint, we need to commit the generated `.stderr` files, too. In general, you
+should only commit files changed by `cargo dev bless` for the
+specific lint you are creating/editing. Note that if the generated files are
+empty, they should be removed.
+
+Note that you can run multiple test files by specifying a comma separated list:
+`TESTNAME=foo_functions,test2,test3`.
+
+### Cargo lints
+
+For cargo lints, the process of testing differs in that we are interested in
+the `Cargo.toml` manifest file. We also need a minimal crate associated
+with that manifest.
+
+If our new lint is named e.g. `foo_categories`, after running `cargo dev new_lint`
+we will find by default two new crates, each with its manifest file:
+
+* `tests/ui-cargo/foo_categories/fail/Cargo.toml`: this file should cause the new lint to raise an error.
+* `tests/ui-cargo/foo_categories/pass/Cargo.toml`: this file should not trigger the lint.
+
+If you need more cases, you can copy one of those crates (under `foo_categories`) and rename it.
+
+The process of generating the `.stderr` file is the same, and prepending the `TESTNAME`
+variable to `cargo uitest` works too.
-### Rustfix tests
+## Rustfix tests
If the lint you are working on is making use of structured suggestions, the
test file should include a `// run-rustfix` comment at the top. This will
-additionally run [rustfix](https://github.com/rust-lang-nursery/rustfix) for
-that test. Rustfix will apply the suggestions from the lint to the code of the
-test file and compare that to the contents of a `.fixed` file.
+additionally run [rustfix] for that test. Rustfix will apply the suggestions
+from the lint to the code of the test file and compare that to the contents of
+a `.fixed` file.
-Use `tests/ui/update-all-references.sh` to automatically generate the
+Use `cargo dev bless` to automatically generate the
`.fixed` file after running the tests.
-### Edition 2018 tests
+[rustfix]: https://github.com/rust-lang/rustfix
+
+## Edition 2018 tests
Some features require the 2018 edition to work (e.g. `async_await`), but
compile-test tests run on the 2015 edition by default. To change this behavior
-add `// compile-flags: --edition 2018` at the top of the test file.
+add `// edition:2018` at the top of the test file (note that it's space-sensitive).
-### Testing manually
+## Testing manually
Manually testing against an example file can be useful if you have added some
`println!`s and the test suite output becomes unreadable. To try Clippy with
-your local modifications, run `env CLIPPY_TESTS=true cargo run --bin
-clippy-driver -- -L ./target/debug input.rs` from the working copy root.
+your local modifications, run
-With tests in place, let's have a look at implementing our lint now.
+```
+env __CLIPPY_INTERNAL_TESTS=true cargo run --bin clippy-driver -- -L ./target/debug input.rs
+```
-### Lint declaration
+from the working copy root. With tests in place, let's have a look at
+implementing our lint now.
+
+## Lint declaration
Let's start by opening the new file created in the `clippy_lints` crate
at `clippy_lints/src/foo_functions.rs`. That's the crate where all the
```rust
use rustc_lint::{EarlyLintPass, EarlyContext};
use rustc_session::{declare_lint_pass, declare_tool_lint};
-use syntax::ast::*;
+use rustc_ast::ast::*;
```
The next step is to update the lint declaration. Lints are declared using the
```
* The section of lines prefixed with `///` constitutes the lint documentation
-section. This is the default documentation style and will be displayed at
-https://rust-lang.github.io/rust-clippy/master/index.html.
-* `FOO_FUNCTIONS` is the name of our lint. Be sure to follow the [lint naming
-guidelines][lint_naming] here when naming your lint. In short, the name should
-state the thing that is being checked for and read well when used with
-`allow`/`warn`/`deny`.
+ section. This is the default documentation style and will be displayed
+ [like this][example_lint_page]. To render and open this documentation locally
+ in a browser, run `cargo dev serve`.
+* `FOO_FUNCTIONS` is the name of our lint. Be sure to follow the
+ [lint naming guidelines][lint_naming] here when naming your lint.
+ In short, the name should state the thing that is being checked for and
+ read well when used with `allow`/`warn`/`deny`.
* `pedantic` sets the lint level to `Allow`.
The exact mapping can be found [here][category_level_mapping]
* The last part should be a text that explains what exactly is wrong with the
impl EarlyLintPass for FooFunctions {}
```
-Don't worry about the `name` method here. As long as it includes the name of the
-lint pass it should be fine.
-
-The new lint automation runs `update_lints`, which automates some things, but it
-doesn't automate everything. We will have to register our lint pass manually in
-the `register_plugins` function in `clippy_lints/src/lib.rs`:
+Normally after declaring the lint, we have to run `cargo dev update_lints`,
+which updates some files, so Clippy knows about the new lint. Since we used
+`cargo dev new_lint ...` to generate the lint declaration, this was done
+automatically. While `update_lints` automates most of the things, it doesn't
+automate everything. We will have to register our lint pass manually in the
+`register_plugins` function in `clippy_lints/src/lib.rs`:
```rust
-reg.register_early_lint_pass(box foo_functions::FooFunctions);
+store.register_early_pass(|| box foo_functions::FooFunctions);
```
-This should fix the `unknown clippy lint: clippy::foo_functions` error that we
-saw when we executed our tests the first time. The next decision we have to make
-is which lint pass our lint is going to need.
+As one may expect, there is a corresponding `register_late_pass` method
+available as well. Without a call to one of `register_early_pass` or
+`register_late_pass`, the lint pass in question will not be run.
-### Lint passes
+One reason that `cargo dev` does not automate this step is that multiple lints
+can use the same lint pass, so registering the lint pass may already be done
+when adding a new lint. Another reason that this step is not automated is that
+the order that the passes are registered determines the order the passes
+actually run, which in turn affects the order that any emitted lints are output
+in.
+
+[declare_clippy_lint]: https://github.com/rust-lang/rust-clippy/blob/557f6848bd5b7183f55c1e1522a326e9e1df6030/clippy_lints/src/lib.rs#L60
+[example_lint_page]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure
+[lint_naming]: https://rust-lang.github.io/rfcs/0344-conventions-galore.html#lints
+[category_level_mapping]: https://github.com/rust-lang/rust-clippy/blob/557f6848bd5b7183f55c1e1522a326e9e1df6030/clippy_lints/src/lib.rs#L110
+
+## Lint passes
Writing a lint that only checks for the name of a function means that we only
have to deal with the AST and don't have to deal with the type system at all.
`--pass=early` when running the new lint automation and all the imports were
added accordingly.
-### Emitting a lint
+[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
+
+## Emitting a lint
With UI tests and the lint declaration in place, we can start working on the
implementation of the lint logic.
```rust
impl EarlyLintPass for FooFunctions {
- fn check_fn(&mut self, cx: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: &FnDecl, span: Span, _: NodeId) {
+ fn check_fn(&mut self, cx: &EarlyContext<'_>, fn_kind: FnKind<'_>, span: Span, _: NodeId) {
// TODO: Emit lint here
}
}
Depending on how complex we want our lint message to be, we can choose from a
variety of lint emission functions. They can all be found in
-[`clippy_lints/src/utils/diagnostics.rs`][diagnostics].
+[`clippy_utils/src/diagnostics.rs`][diagnostics].
`span_lint_and_help` seems most appropriate in this case. It allows us to
provide an extra help message and we can't really suggest a better name
```rust
impl EarlyLintPass for FooFunctions {
- fn check_fn(&mut self, cx: &EarlyContext<'_>, _: FnKind<'_>, _: &FnDecl, span: Span, _: NodeId) {
+ fn check_fn(&mut self, cx: &EarlyContext<'_>, fn_kind: FnKind<'_>, span: Span, _: NodeId) {
span_lint_and_help(
cx,
FOO_FUNCTIONS,
span,
"function named `foo`",
+ None,
"consider using a more meaningful name"
);
}
Running our UI test should now produce output that contains the lint message.
-### Adding the lint logic
+According to [the rustc-dev-guide], the text should be matter of fact and avoid
+capitalization and periods, unless multiple sentences are needed.
+When code or an identifier must appear in a message or label, it should be
+surrounded with single grave accents \`.
+
+[check_fn]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint/trait.EarlyLintPass.html#method.check_fn
+[diagnostics]: https://github.com/rust-lang/rust-clippy/blob/master/clippy_utils/src/diagnostics.rs
+[the rustc-dev-guide]: https://rustc-dev-guide.rust-lang.org/diagnostics.html
+
+## Adding the lint logic
Writing the logic for your lint will most likely be different from our example,
so this section is kept rather short.
Using the [`check_fn`][check_fn] method gives us access to [`FnKind`][fn_kind]
-that has two relevant variants for us `FnKind::ItemFn` and `FnKind::Method`.
-Both provide access to the name of the function/method via an [`Ident`][ident].
+that has the [`FnKind::Fn`] variant. It provides access to the name of the
+function/method via an [`Ident`][ident].
With that we can expand our `check_fn` method to:
```rust
impl EarlyLintPass for FooFunctions {
- fn check_fn(&mut self, cx: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: &FnDecl, span: Span, _: NodeId) {
+ fn check_fn(&mut self, cx: &EarlyContext<'_>, fn_kind: FnKind<'_>, span: Span, _: NodeId) {
if is_foo_fn(fn_kind) {
span_lint_and_help(
cx,
FOO_FUNCTIONS,
span,
"function named `foo`",
+ None,
"consider using a more meaningful name"
);
}
fn is_foo_fn(fn_kind: FnKind<'_>) -> bool {
match fn_kind {
- FnKind::ItemFn(ident, ..) | FnKind::Method(ident, ..) => {
- ident.name == "foo"
- },
+ FnKind::Fn(_, ident, ..) => {
+ // check if `fn` name is `foo`
+ ident.name.as_str() == "foo"
+ }
+ // ignore closures
FnKind::Closure(..) => false
}
}
Now we should also run the full test suite with `cargo test`. At this point
running `cargo test` should produce the expected output. Remember to run
-`tests/ui/update-all-references.sh` to update the `.stderr` file.
+`cargo dev bless` to update the `.stderr` file.
`cargo test` (as opposed to `cargo uitest`) will also ensure that our lint
implementation is not violating any Clippy lints itself.
That should be it for the lint implementation. Running `cargo test` should now
pass.
-### Author lint
+[fn_kind]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_ast/visit/enum.FnKind.html
+[`FnKind::Fn`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_ast/visit/enum.FnKind.html#variant.Fn
+[ident]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/symbol/struct.Ident.html
+
+## Specifying the lint's minimum supported Rust version (MSRV)
+
+Projects supporting older versions of Rust would need to disable a lint if it
+targets features present in later versions. Support for this can be added by
+specifying an MSRV in your lint like so,
+
+```rust
+const MANUAL_STRIP_MSRV: RustcVersion = RustcVersion::new(1, 45, 0);
+```
+
+The project's MSRV will also have to be an attribute in the lint so you'll have
+to add a struct and constructor for your lint. The project's MSRV needs to be
+passed when the lint is registered in `lib.rs`
+
+```rust
+pub struct ManualStrip {
+ msrv: Option<RustcVersion>,
+}
+
+impl ManualStrip {
+ #[must_use]
+ pub fn new(msrv: Option<RustcVersion>) -> Self {
+ Self { msrv }
+ }
+}
+```
+
+The project's MSRV can then be matched against the lint's `msrv` in the LintPass
+using the `meets_msrv` utility function.
+
+``` rust
+if !meets_msrv(self.msrv.as_ref(), &MANUAL_STRIP_MSRV) {
+ return;
+}
+```
+
+The project's MSRV can also be specified as an inner attribute, which overrides
+the value from `clippy.toml`. This can be accounted for using the
+`extract_msrv_attr!(LintContext)` macro and passing
+`LateContext`/`EarlyContext`.
+
+```rust
+impl<'tcx> LateLintPass<'tcx> for ManualStrip {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+ ...
+ }
+ extract_msrv_attr!(LateContext);
+}
+```
+
+Once the `msrv` is added to the lint, a relevant test case should be added to
+`tests/ui/min_rust_version_attr.rs` which verifies that the lint isn't emitted
+if the project's MSRV is lower.
+
+As a last step, the lint should be added to the lint documentation. This is done
+in `clippy_lints/src/utils/conf.rs`:
+
+```rust
+define_Conf! {
+ /// Lint: LIST, OF, LINTS, <THE_NEWLY_ADDED_LINT>. The minimum rust version that the project supports
+ (msrv, "msrv": Option<String>, None),
+ ...
+}
+```
+
+## Author lint
If you have trouble implementing your lint, there is also the internal `author`
lint to generate Clippy code that detects the offending pattern. It does not
work for all of the Rust syntax, but can give a good starting point.
-The quickest way to use it, is the [Rust playground: play.rust-lang.org][Play].
+The quickest way to use it, is the
+[Rust playground: play.rust-lang.org][author_example].
Put the code you want to lint into the editor and add the `#[clippy::author]`
attribute above the item. Then run Clippy via `Tools -> Clippy` and you should
see the generated code in the output below.
If the command was executed successfully, you can copy the code over to where
you are implementing your lint.
-### Documentation
+[author_example]: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=9a12cb60e5c6ad4e3003ac6d5e63cf55
+
+## Documentation
The final thing before submitting our PR is to add some documentation to our
lint declaration.
Once your lint is merged, this documentation will show up in the [lint
list][lint_list].
-### Running rustfmt
+[lint_list]: https://rust-lang.github.io/rust-clippy/master/index.html
+
+## Running rustfmt
-[Rustfmt](https://github.com/rust-lang/rustfmt) is a tool for formatting Rust
-code according to style guidelines. Your code has to be formatted by `rustfmt`
-before a PR can be merged. Clippy uses nightly `rustfmt` in the CI.
+[Rustfmt] is a tool for formatting Rust code according to style guidelines.
+Your code has to be formatted by `rustfmt` before a PR can be merged.
+Clippy uses nightly `rustfmt` in the CI.
It can be installed via `rustup`:
Use `cargo dev fmt` to format the whole codebase. Make sure that `rustfmt` is
installed for the nightly toolchain.
-### Debugging
+[Rustfmt]: https://github.com/rust-lang/rustfmt
-If you want to debug parts of your lint implementation, you can use the `dbg!`
+## Debugging
+
+If you want to debug parts of your lint implementation, you can use the [`dbg!`]
macro anywhere in your code. Running the tests should then include the debug
output in the `stdout` part.
-### PR Checklist
+[`dbg!`]: https://doc.rust-lang.org/std/macro.dbg.html
+
+## PR Checklist
Before submitting your PR make sure you followed all of the basic requirements:
<!-- Sync this with `.github/PULL_REQUEST_TEMPLATE` -->
-- [ ] Followed [lint naming conventions][lint_naming]
-- [ ] Added passing UI tests (including committed `.stderr` file)
-- [ ] `cargo test` passes locally
-- [ ] Executed `cargo dev update_lints`
-- [ ] Added lint documentation
-- [ ] Run `cargo dev fmt`
+- \[ ] Followed [lint naming conventions][lint_naming]
+- \[ ] Added passing UI tests (including committed `.stderr` file)
+- \[ ] `cargo test` passes locally
+- \[ ] Executed `cargo dev update_lints`
+- \[ ] Added lint documentation
+- \[ ] Run `cargo dev fmt`
+
+## Adding configuration to a lint
+
+Clippy supports the configuration of lints values using a `clippy.toml` file in the workspace
+directory. Adding a configuration to a lint can be useful for thresholds or to constrain some
+behavior that can be seen as a false positive for some users. Adding a configuration is done
+in the following steps:
+
+1. Adding a new configuration entry to [clippy_utils::conf](/clippy_utils/src/conf.rs)
+ like this:
+ ```rust
+ /// Lint: LINT_NAME. <The configuration field doc comment>
+ (configuration_ident, "configuration_value": Type, DefaultValue),
+ ```
+ The configuration value and identifier should usually be the same. The doc comment will be
+ automatically added to the lint documentation.
+2. Adding the configuration value to the lint impl struct:
+ 1. This first requires the definition of a lint impl struct. Lint impl structs are usually
+ generated with the `declare_lint_pass!` macro. This struct needs to be defined manually
+ to add some kind of metadata to it:
+ ```rust
+ // Generated struct definition
+ declare_lint_pass!(StructName => [
+ LINT_NAME
+ ]);
+
+ // New manual definition struct
+ #[derive(Copy, Clone)]
+ pub struct StructName {}
+
+ impl_lint_pass!(StructName => [
+ LINT_NAME
+ ]);
+ ```
+
+ 2. Next add the configuration value and a corresponding creation method like this:
+ ```rust
+ #[derive(Copy, Clone)]
+ pub struct StructName {
+ configuration_ident: Type,
+ }
+
+ // ...
+
+ impl StructName {
+ pub fn new(configuration_ident: Type) -> Self {
+ Self {
+ configuration_ident,
+ }
+ }
+ }
+ ```
+3. Passing the configuration value to the lint impl struct:
+
+ First find the struct construction in the [clippy_lints lib file](/clippy_lints/src/lib.rs).
+ The configuration value is now cloned or copied into a local value that is then passed to the
+ impl struct like this:
+ ```rust
+ // Default generated registration:
+ store.register_*_pass(|| box module::StructName);
+
+ // New registration with configuration value
+ let configuration_ident = conf.configuration_ident.clone();
+ store.register_*_pass(move || box module::StructName::new(configuration_ident));
+ ```
+
+ Congratulations the work is almost done. The configuration value can now be accessed
+ in the linting code via `self.configuration_ident`.
-### Cheatsheet
+4. Adding tests:
+ 1. The default configured value can be tested like any normal lint in [`tests/ui`](/tests/ui).
+ 2. The configuration itself will be tested separately in [`tests/ui-toml`](/tests/ui-toml).
+ Simply add a new subfolder with a fitting name. This folder contains a `clippy.toml` file
+ with the configuration value and a rust file that should be linted by Clippy. The test can
+ otherwise be written as usual.
+
+## Cheatsheet
Here are some pointers to things you are likely going to need for every lint:
* [`from_expansion`][from_expansion] and [`in_external_macro`][in_external_macro]
* [`Span`][span]
* [`Applicability`][applicability]
-* [The rustc guide][rustc_guide] explains a lot of internal compiler concepts
+* [Common tools for writing lints](common_tools_writing_lints.md) helps with common operations
+* [The rustc-dev-guide][rustc-dev-guide] explains a lot of internal compiler concepts
* [The nightly rustc docs][nightly_docs] which has been linked to throughout
this guide
For `EarlyLintPass` lints:
* [`EarlyLintPass`][early_lint_pass]
-* [`syntax::ast`][ast]
+* [`rustc_ast::ast`][ast]
For `LateLintPass` lints:
* [`LateLintPass`][late_lint_pass]
* [`Ty::TyKind`][ty]
-
While most of Clippy's lint utils are documented, most of rustc's internals lack
documentation currently. This is unfortunate, but in most cases you can probably
get away with copying things from existing similar lints. If you are stuck,
-don't hesitate to ask on Discord, IRC or in the issue/PR.
+don't hesitate to ask on [Zulip] or in the issue/PR.
-[lint_list]: https://rust-lang.github.io/rust-clippy/master/index.html
-[lint_naming]: https://rust-lang.github.io/rfcs/0344-conventions-galore.html#lints
-[category_level_mapping]: https://github.com/rust-lang/rust-clippy/blob/bd23cb89ec0ea63403a17d3fc5e50c88e38dd54f/clippy_lints/src/lib.rs#L43
-[declare_clippy_lint]: https://github.com/rust-lang/rust-clippy/blob/a71acac1da7eaf667ab90a1d65d10e5cc4b80191/clippy_lints/src/lib.rs#L39
-[compilation_stages]: https://rust-lang.github.io/rustc-guide/high-level-overview.html#the-main-stages-of-compilation
-[check_fn]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/lint/trait.EarlyLintPass.html#method.check_fn
-[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
-[fn_kind]: https://doc.rust-lang.org/nightly/nightly-rustc/syntax/visit/enum.FnKind.html
-[diagnostics]: https://github.com/rust-lang/rust-clippy/blob/master/clippy_lints/src/utils/diagnostics.rs
-[utils]: https://github.com/rust-lang/rust-clippy/blob/master/clippy_lints/src/utils/mod.rs
-[ident]: https://doc.rust-lang.org/nightly/nightly-rustc/syntax/source_map/symbol/struct.Ident.html
-[span]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/struct.Span.html
-[applicability]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_errors/enum.Applicability.html
+[utils]: https://github.com/rust-lang/rust-clippy/blob/master/clippy_utils/src/lib.rs
[if_chain]: https://docs.rs/if_chain/*/if_chain/
-[ty]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/ty/sty/index.html
-[ast]: https://doc.rust-lang.org/nightly/nightly-rustc/syntax/ast/index.html
[from_expansion]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/struct.Span.html#method.from_expansion
-[in_external_macro]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/lint/fn.in_external_macro.html
-[play]: https://play.rust-lang.org
-[author_example]: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=f093b986e80ad62f3b67a1f24f5e66e2
-[rustc_guide]: https://rust-lang.github.io/rustc-guide/
-[nightly_docs]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/
+[in_external_macro]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/lint/fn.in_external_macro.html
+[span]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/struct.Span.html
+[applicability]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_errors/enum.Applicability.html
+[rustc-dev-guide]: https://rustc-dev-guide.rust-lang.org/
+[nightly_docs]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/
+[ast]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_ast/ast/index.html
+[ty]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/sty/index.html
+[Zulip]: https://rust-lang.zulipchat.com/#narrow/stream/clippy