1 # Basics for hacking on Clippy
3 This document explains the basics for hacking on Clippy. Besides others, this
4 includes how to set-up the development environment, how to build and how to test
5 Clippy. For a more in depth description on the codebase take a look at [Adding
6 Lints] or [Common Tools].
8 [Adding Lints]: https://github.com/rust-lang/rust-clippy/blob/master/doc/adding_lints.md
9 [Common Tools]: https://github.com/rust-lang/rust-clippy/blob/master/doc/common_tools_writing_lints.md
11 - [Basics for hacking on Clippy](#basics-for-hacking-on-clippy)
12 - [Get the code](#get-the-code)
14 - [Building and Testing](#building-and-testing)
15 - [`cargo dev`](#cargo-dev)
19 First, make sure you have checked out the latest version of Clippy. If this is
20 your first time working on Clippy, create a fork of the repository and clone it
21 afterwards with the following command:
24 git clone git@github.com:<your-username>/rust-clippy
27 If you've already cloned Clippy in the past, update it to the latest version:
30 # upstream has to be the remote of the rust-lang/rust-clippy repo
32 # make sure that you are on the master branch
34 # rebase your master branch on the upstream master
35 git rebase upstream/master
36 # push to the master branch of your fork
42 Next we need to setup the toolchain to compile Clippy. Since Clippy heavily
43 relies on compiler internals it is build with the latest rustc master. To get
44 this toolchain, you can just use the `setup-toolchain.sh` script or use
45 `rustup-toolchain-install-master`:
50 cargo install rustup-toolchain-install-master
51 # For better IDE integration also add `-c rustfmt -c rust-src` (optional)
52 rustup-toolchain-install-master -f -n master -c rustc-dev -c llvm-tools
53 rustup override set master
56 ## Building and Testing
58 Once the `master` toolchain is installed, you can build and test Clippy like
59 every other Rust project:
62 cargo build # builds Clippy
63 cargo test # tests Clippy
66 Since Clippy's test suite is pretty big, there are some commands that only run a
67 subset of Clippy's tests:
72 # only run UI tests starting with `test_`
73 TESTNAME="test_" cargo uitest
74 # only run dogfood tests
75 cargo test --test dogfood
78 If the output of a [UI test] differs from the expected output, you can update the
82 sh tests/ui/update-all-references.sh
85 For example, this is necessary, if you fix a typo in an error message of a lint
86 or if you modify a test file to add a test case.
88 _Note:_ This command may update more files than you intended. In that case only
89 commit the files you wanted to update.
91 [UI test]: https://rustc-dev-guide.rust-lang.org/tests/adding.html#guide-to-the-ui-tests
95 Clippy has some dev tools to make working on Clippy more convenient. These tools
96 can be accessed through the `cargo dev` command. Available tools are listed
97 below. To get more information about these commands, just call them with
101 # formats the whole Clippy codebase and all tests
103 # register or update lint names/groups/...
104 cargo dev update_lints
105 # create a new lint and register it
107 # (experimental) Setup Clippy to work with rust-analyzer