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.
+**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` IRC channel on `irc.mozilla.org` or meet us in `#wg-clippy` on [Discord](https://discord.gg/rust-lang).
+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 [Discord].
-All contributors are expected to follow the [Rust Code of Conduct](http://www.rust-lang.org/conduct.html).
+All contributors are expected to follow the [Rust Code of Conduct].
* [Getting started](#getting-started)
* [Finding something to fix/improve](#finding-something-to-fiximprove)
* [Writing code](#writing-code)
- * [Author lint](#author-lint)
- * [Documentation](#documentation)
- * [Running test suite](#running-test-suite)
- * [Running rustfmt](#running-rustfmt)
- * [Testing manually](#testing-manually)
- * [How Clippy works](#how-clippy-works)
- * [Fixing nightly build failures](#fixing-build-failures-caused-by-rust)
+* [How Clippy works](#how-clippy-works)
+* [Fixing nightly build failures](#fixing-build-failures-caused-by-rust)
* [Issue and PR Triage](#issue-and-pr-triage)
* [Bors and Homu](#bors-and-homu)
* [Contributions](#contributions)
+[Discord]: https://discord.gg/rust-lang
+[Rust Code of Conduct]: https://www.rust-lang.org/policies/code-of-conduct
+
## Getting started
High level approach:
1. Find something to fix/improve
2. Change code (likely some file in `clippy_lints/src/`)
-3. Run `cargo test` in the root directory and wiggle code until it passes
-4. Open a PR (also can be done between 2. and 3. if you run into problems)
+3. Follow the instructions in the [docs for writing lints](doc/adding_lints.md) such as running the `setup-toolchain.sh` script
+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 with a bug just ask @Manishearth, @llogiq, @mcarton or @oli-obk.
-Some issues are easier than others. The [`good first issue`](https://github.com/rust-lang/rust-clippy/labels/good%20first%20issue)
-label can be used to find the easy issues. If you want to work on an issue, please leave a comment
-so that we can assign it to you!
+Some issues are easier than others. The [`good first issue`] label can be used to find the easy issues.
+If you want to work on an issue, please leave a comment so that we can assign it to you!
+
+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`](https://github.com/rust-lang/rust-clippy/labels/T-AST) involve simple
-matching of the syntax tree structure, and are generally easier than
-[`T-middle`](https://github.com/rust-lang/rust-clippy/labels/T-middle) issues, which involve types
+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`](https://github.com/rust-lang/rust-clippy/labels/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 ast-json` on an
-example of the structure and compare with the
-[nodes in the AST docs](https://doc.rust-lang.org/nightly/nightly-rustc/syntax/ast). Usually
-the lint will end up to be a nested series of matches and ifs,
-[like so](https://github.com/rust-lang/rust-clippy/blob/de5ccdfab68a5e37689f3c950ed1532ba9d652a0/src/misc.rs#L34).
+[`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 ast-json` 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 [if_chain] macro, [like this][nest-less].
-[`E-medium`](https://github.com/rust-lang/rust-clippy/labels/E-medium) issues are generally
-pretty easy too, though it's recommended you work on an E-easy issue first. They are mostly classified
-as `E-medium`, since they might be somewhat involved code wise, but not difficult per-se.
+[`E-medium`] issues are generally pretty easy too, though it's recommended you work on an E-easy issue first.
+They are mostly classified as [`E-medium`], since they might be somewhat involved code wise,
+but not difficult per-se.
-[`T-middle`](https://github.com/rust-lang/rust-clippy/labels/T-middle) issues can
-be more involved and require verifying types. The
-[`ty`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc/ty) module contains a
+[`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%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/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/557f6848bd5b7183f55c1e1522a326e9e1df6030/clippy_lints/src/mem_forget.rs#L29-L43
+[if_chain]: https://docs.rs/if_chain/*/if_chain
+[nest-less]: https://github.com/rust-lang/rust-clippy/blob/557f6848bd5b7183f55c1e1522a326e9e1df6030/clippy_lints/src/bit_mask.rs#L124-L150
+
## Writing code
-[Llogiq's blog post on lints](https://llogiq.github.io/2015/06/04/workflows.html) is a nice primer
-to lint-writing, though it does get into advanced stuff. Most lints consist of an implementation of
-`LintPass` with one or more of its default methods overridden. See the existing lints for examples
-of this.
+Have a look at the [docs for writing lints][adding_lints] for more details. [Llogiq's blog post on lints]
+is also a nice primer to lint-writing, though it does get into advanced stuff and may be a bit outdated.
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 guaratees][rfc_stability] and
+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.
-### Author 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.
-
-First, create a new UI test file in the `tests/ui/` directory with the pattern you want to match:
-
-```rust
-// ./tests/ui/my_lint.rs
-fn main() {
- #[clippy::author]
- let arr: [i32; 1] = [7]; // Replace line with the code you want to match
-}
-```
-
-Now you run `TESTNAME=ui/my_lint cargo test --test compile-test` to produce
-a `.stdout` file with the generated code:
-
-```rust
-// ./tests/ui/my_lint.stdout
-
-if_chain! {
- if let ExprKind::Array(ref elements) = stmt.node;
- if elements.len() == 1;
- if let ExprKind::Lit(ref lit) = elements[0].node;
- if let LitKind::Int(7, _) = lit.node;
- then {
- // report your lint here
- }
-}
-```
-
-If the command was executed successfully, you can copy the code over to where you are implementing your lint.
-
-### Documentation
-
-Please document your lint with a doc comment akin to the following:
-
-```rust
-/// **What it does:** Checks for ... (describe what the lint matches).
-///
-/// **Why is this bad?** Supply the reason for linting the code.
-///
-/// **Known problems:** None. (Or describe where it could go wrong.)
-///
-/// **Example:**
-///
-/// ```rust
-/// // Bad
-/// Insert a short example of code that triggers the lint
-///
-/// // Good
-/// Insert a short example of improved code that doesn't trigger the lint
-/// ```
-```
-
-Once your lint is merged it will show up in the [lint list](https://rust-lang.github.io/rust-clippy/master/index.html)
-
-### Running test suite
-
-Use `cargo test` to run the whole testsuite.
-
-If you don't want to wait for all tests to finish, you can also execute a single test file by using `TESTNAME` to specify the test to run:
-
-```bash
-TESTNAME=ui/empty_line_after_outer_attr cargo test --test compile-test
-```
-
-Clippy uses UI tests. UI tests check that the output of the compiler is exactly as expected.
-Of course there's little sense in writing the output yourself or copying it around.
-Therefore you should use `tests/ui/update-all-references.sh` (after running
-`cargo test`) and check whether the output looks as you expect with `git diff`. Commit all
-`*.stderr` files, too.
-
-### Running rustfmt
-
-[Rustfmt](https://github.com/rust-lang/rustfmt) is a tool for formatting Rust code according
-to style guidelines. The code has to be formatted by `rustfmt` before a PR will be merged.
-
-It can be installed via `rustup`:
-```bash
-rustup component add rustfmt
-```
-
-Use `cargo fmt --all` to format the whole codebase.
-
-### Testing manually
-
-Manually testing against an example file is useful if you have added some
-`println!`s and 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.
-
-### How Clippy works
+[adding_lints]: https://github.com/rust-lang/rust-clippy/blob/master/doc/adding_lints.md
+[Llogiq's blog post on lints]: https://llogiq.github.io/2015/06/04/workflows.html
+[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
-Clippy is a [rustc compiler plugin][compiler_plugin]. The main entry point is at [`src/lib.rs`][main_entry]. In there, the lint registration is delegated to the [`clippy_lints`][lint_crate] crate.
+## How Clippy works
-[`clippy_lints/src/lib.rs`][lint_crate_entry] imports all the different lint modules and registers them with the rustc plugin registry. For example, the [`else_if_without_else`][else_if_without_else] lint is registered like this:
+[`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(reg: &mut rustc_plugin::Registry) {
+pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: &Conf) {
// ...
- reg.register_early_lint_pass(box else_if_without_else::ElseIfWithoutElse);
+ store.register_early_pass(|| box else_if_without_else::ElseIfWithoutElse);
// ...
- reg.register_lint_group("clippy::restriction", vec![
+ store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
// ...
- else_if_without_else::ELSE_IF_WITHOUT_ELSE,
+ LintId::of(&else_if_without_else::ELSE_IF_WITHOUT_ELSE),
// ...
]);
}
```
-The [`rustc_plugin::PluginRegistry`][plugin_registry] provides two methods to register lints: [register_early_lint_pass][reg_early_lint_pass] and [register_late_lint_pass][reg_late_lint_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 `util/dev update_lints` and you don't have to add anything by hand. When you are writing your own lint, you can use that script to save you some time.
+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, LintArray, LintPass};
+use rustc_lint::{EarlyLintPass, EarlyContext};
// ...
}
```
-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.
+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_lint_pass` function. Because the [actual lint logic][else_if_without_else] does not depend on any type information.
+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.
-### Fixing build failures caused by Rust
+[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
-Clippy will sometimes fail to build from source because building it depends on unstable internal Rust features. Most of the times we have to adapt to the changes and only very rarely there's an actual bug in Rust. Fixing build failures caused by Rust updates, can be a good way to learn about Rust internals.
+## Fixing build failures caused by Rust
-In order to find out why Clippy does not work properly with a new Rust commit, you can use the [rust-toolstate commit history][toolstate_commit_history].
-You will then have to look for the last commit that contains `test-pass -> build-fail` or `test-pass` -> `test-fail` for the `clippy-driver` component. [Here][toolstate_commit] is an example.
+Clippy will sometimes fail to build from source because building it depends on unstable internal Rust features. Most of
+the times we have to adapt to the changes and only very rarely there's an actual bug in Rust. Fixing build failures
+caused by Rust updates, can be a good way to learn about Rust internals.
-The commit message contains a link to the PR. The PRs are usually small enough to discover the breaking API change and if they are bigger, they likely include some discussion that may help you to fix Clippy.
+In order to find out why Clippy does not work properly with a new Rust commit, you can use the [rust-toolstate commit
+history][toolstate_commit_history]. You will then have to look for the last commit that contains
+`test-pass -> build-fail` or `test-pass -> test-fail` for the `clippy-driver` component.
+[Here][toolstate_commit] is an example.
+
+The commit message contains a link to the PR. The PRs are usually small enough to discover the breaking API change and
+if they are bigger, they likely include some discussion that may help you to fix Clippy.
To check if Clippy is available for a specific target platform, you can check
the [rustup component history][rustup_component_history].
you probably want to install the latest Rust from master locally and run Clippy
using that version of Rust.
-You can use [rustup-toolchain-install-master][rtim] to do that:
+You can set up the master toolchain by running `./setup-toolchain.sh`. That script will install
+[rustup-toolchain-install-master][rtim] and master toolchain, then run `rustup override set master`.
+After fixing the build failure on this repository, we can submit a pull request
+to [`rust-lang/rust`] to fix the toolstate.
+
+To submit a pull request, you should follow these steps:
+
+```bash
+# Assuming you already cloned the rust-lang/rust repo and you're in the correct directory
+git submodule update --remote src/tools/clippy
+cargo update -p clippy
+git add -u
+git commit -m "Update Clippy"
+./x.py test -i --stage 1 src/tools/clippy # This is optional and should succeed anyway
+# Open a PR in rust-lang/rust
```
-cargo install rustup-toolchain-install-master
-rustup-toolchain-install-master -n master --force
-rustup override set master
-cargo test
-```
+
+[rustup_component_history]: https://rust-lang.github.io/rustup-components-history
+[toolstate_commit_history]: https://github.com/rust-lang-nursery/rust-toolstate/commits/master
+[toolstate_commit]: https://github.com/rust-lang-nursery/rust-toolstate/commit/aad74d8294e198a7cf8ac81a91aebb7f3bbcf727
+[rtim]: https://github.com/kennytm/rustup-toolchain-install-master
+[`rust-lang/rust`]: https://github.com/rust-lang/rust
## Issue and PR triage
If you have @bors permissions, you can find an overview of the available
commands [here][homu_instructions].
+[triage]: https://forge.rust-lang.org/triage-procedure.html
+[l-crash]: https://github.com/rust-lang/rust-clippy/labels/L-crash%20%3Aboom%3A
+[l-bug]: https://github.com/rust-lang/rust-clippy/labels/L-bug%20%3Abeetle%3A
+[homu]: https://github.com/rust-lang/homu
+[homu_instructions]: https://buildbot2.rust-lang.org/homu/
+[homu_queue]: https://buildbot2.rust-lang.org/homu/queue/clippy
## Contributions
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](http://www.apache.org/licenses/LICENSE-2.0>)
-or the [MIT](http://opensource.org/licenses/MIT) 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 -->
-[main_entry]: https://github.com/rust-lang/rust-clippy/blob/c5b39a5917ffc0f1349b6e414fa3b874fdcf8429/src/lib.rs#L14
-[lint_crate]: https://github.com/rust-lang/rust-clippy/tree/c5b39a5917ffc0f1349b6e414fa3b874fdcf8429/clippy_lints/src
-[lint_crate_entry]: https://github.com/rust-lang/rust-clippy/blob/c5b39a5917ffc0f1349b6e414fa3b874fdcf8429/clippy_lints/src/lib.rs
-[else_if_without_else]: https://github.com/rust-lang/rust-clippy/blob/c5b39a5917ffc0f1349b6e414fa3b874fdcf8429/clippy_lints/src/else_if_without_else.rs
-[compiler_plugin]: https://doc.rust-lang.org/unstable-book/language-features/plugin.html#lint-plugins
-[plugin_registry]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_plugin/registry/struct.Registry.html
-[reg_early_lint_pass]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_plugin/registry/struct.Registry.html#method.register_early_lint_pass
-[reg_late_lint_pass]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_plugin/registry/struct.Registry.html#method.register_late_lint_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
-[toolstate_commit_history]: https://github.com/rust-lang-nursery/rust-toolstate/commits/master
-[toolstate_commit]: https://github.com/rust-lang-nursery/rust-toolstate/commit/6ce0459f6bfa7c528ae1886492a3e0b5ef0ee547
-[rtim]: https://github.com/kennytm/rustup-toolchain-install-master
-[rustup_component_history]: https://mexus.github.io/rustup-components-history
-[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
-[triage]: https://forge.rust-lang.org/triage-procedure.html
-[l-crash]: https://github.com/rust-lang/rust-clippy/labels/L-crash%20%3Aboom%3A
-[l-bug]: https://github.com/rust-lang/rust-clippy/labels/L-bug%20%3Abeetle%3A
-[homu]: https://github.com/servo/homu
-[homu_instructions]: https://buildbot2.rust-lang.org/homu/
-[homu_queue]: https://buildbot2.rust-lang.org/homu/queue/clippy
+[Apache-2.0]: https://www.apache.org/licenses/LICENSE-2.0
+[MIT]: https://opensource.org/licenses/MIT
projects / rust.git / blobdiff