src/tools/clippy/doc/basics.md

   1 # Basics for hacking on Clippy
   2
   3 This document explains the basics for hacking on Clippy. Besides others, this
   4 includes how to build and test Clippy. For a more in depth description on
   5 the codebase take a look at [Adding Lints] or [Common Tools].
   6
   7 [Adding Lints]: https://github.com/rust-lang/rust-clippy/blob/master/doc/adding_lints.md
   8 [Common Tools]: https://github.com/rust-lang/rust-clippy/blob/master/doc/common_tools_writing_lints.md
   9
  10 - [Basics for hacking on Clippy](#basics-for-hacking-on-clippy)
  11   - [Get the Code](#get-the-code)
  12   - [Building and Testing](#building-and-testing)
  13   - [`cargo dev`](#cargo-dev)
  14   - [lintcheck](#lintcheck)
  15   - [PR](#pr)
  16   - [Common Abbreviations](#common-abbreviations)
  17   - [Install from source](#install-from-source)
  18
  19 ## Get the Code
  20
  21 First, make sure you have checked out the latest version of Clippy. If this is
  22 your first time working on Clippy, create a fork of the repository and clone it
  23 afterwards with the following command:
  24
  25 ```bash
  26 git clone git@github.com:<your-username>/rust-clippy
  27 ```
  28
  29 If you've already cloned Clippy in the past, update it to the latest version:
  30
  31 ```bash
  32 # If the upstream remote has not been added yet
  33 git remote add upstream https://github.com/rust-lang/rust-clippy
  34 # upstream has to be the remote of the rust-lang/rust-clippy repo
  35 git fetch upstream
  36 # make sure that you are on the master branch
  37 git checkout master
  38 # rebase your master branch on the upstream master
  39 git rebase upstream/master
  40 # push to the master branch of your fork
  41 git push
  42 ```
  43
  44 ## Building and Testing
  45
  46 You can build and test Clippy like every other Rust project:
  47
  48 ```bash
  49 cargo build  # builds Clippy
  50 cargo test   # tests Clippy
  51 ```
  52
  53 Since Clippy's test suite is pretty big, there are some commands that only run a
  54 subset of Clippy's tests:
  55
  56 ```bash
  57 # only run UI tests
  58 cargo uitest
  59 # only run UI tests starting with `test_`
  60 TESTNAME="test_" cargo uitest
  61 # only run dogfood tests
  62 cargo test --test dogfood
  63 ```
  64
  65 If the output of a [UI test] differs from the expected output, you can update the
  66 reference file with:
  67
  68 ```bash
  69 cargo dev bless
  70 ```
  71
  72 For example, this is necessary, if you fix a typo in an error message of a lint
  73 or if you modify a test file to add a test case.
  74
  75 _Note:_ This command may update more files than you intended. In that case only
  76 commit the files you wanted to update.
  77
  78 [UI test]: https://rustc-dev-guide.rust-lang.org/tests/adding.html#guide-to-the-ui-tests
  79
  80 ## `cargo dev`
  81
  82 Clippy has some dev tools to make working on Clippy more convenient. These tools
  83 can be accessed through the `cargo dev` command. Available tools are listed
  84 below. To get more information about these commands, just call them with
  85 `--help`.
  86
  87 ```bash
  88 # formats the whole Clippy codebase and all tests
  89 cargo dev fmt
  90 # register or update lint names/groups/...
  91 cargo dev update_lints
  92 # create a new lint and register it
  93 cargo dev new_lint
  94 # automatically formatting all code before each commit
  95 cargo dev setup git-hook
  96 # (experimental) Setup Clippy to work with IntelliJ-Rust
  97 cargo dev setup intellij
  98 ```
  99
 100 ## lintcheck
 101 `cargo lintcheck` will build and run clippy on a fixed set of crates and generate a log of the results.
 102 You can `git diff` the updated log against its previous version and
 103 see what impact your lint made on a small set of crates.
 104 If you add a new lint, please audit the resulting warnings and make sure
 105 there are no false positives and that the suggestions are valid.
 106
 107 Refer to the tools [README] for more details.
 108
 109 [README]: https://github.com/rust-lang/rust-clippy/blob/master/lintcheck/README.md
 110 ## PR
 111
 112 We follow a rustc no merge-commit policy.
 113 See <https://rustc-dev-guide.rust-lang.org/contributing.html#opening-a-pr>.
 114
 115 ## Common Abbreviations
 116
 117 | Abbreviation | Meaning                                |
 118 | ------------ | -------------------------------------- |
 119 | UB           | Undefined Behavior                     |
 120 | FP           | False Positive                         |
 121 | FN           | False Negative                         |
 122 | ICE          | Internal Compiler Error                |
 123 | AST          | Abstract Syntax Tree                   |
 124 | MIR          | Mid-Level Intermediate Representation  |
 125 | HIR          | High-Level Intermediate Representation |
 126 | TCX          | Type context                           |
 127
 128 This is a concise list of abbreviations that can come up during Clippy development. An extensive
 129 general list can be found in the [rustc-dev-guide glossary][glossary]. Always feel free to ask if
 130 an abbreviation or meaning is unclear to you.
 131
 132 ## Install from source
 133
 134 If you are hacking on Clippy and want to install it from source, do the following:
 135
 136 First, take note of the toolchain [override](https://rust-lang.github.io/rustup/overrides.html) in `/rust-toolchain`.
 137 We will use this override to install Clippy into the right toolchain.
 138
 139 > Tip: You can view the active toolchain for the current directory with `rustup show active-toolchain`.
 140
 141 From the Clippy project root, run the following command to build the Clippy binaries and copy them into the
 142 toolchain directory. This will override the currently installed Clippy component.
 143
 144 ```terminal
 145 cargo build --release --bin cargo-clippy --bin clippy-driver -Zunstable-options --out-dir "$(rustc --print=sysroot)/bin"
 146 ```
 147
 148 Now you may run `cargo clippy` in any project, using the toolchain where you just installed Clippy.
 149
 150 ```terminal
 151 cd my-project
 152 cargo +nightly-2021-07-01 clippy
 153 ```
 154
 155 ...or `clippy-driver`
 156
 157 ```terminal
 158 clippy-driver +nightly-2021-07-01 <filename>
 159 ```
 160
 161 If you need to restore the default Clippy installation, run the following (from the Clippy project root).
 162
 163 ```terminal
 164 rustup component remove clippy
 165 rustup component add clippy
 166 ```
 167
 168 > **DO NOT** install using `cargo install --path . --force` since this will overwrite rustup
 169 [proxies](https://rust-lang.github.io/rustup/concepts/proxies.html). That is, `~/.cargo/bin/cargo-clippy` and
 170 `~/.cargo/bin/clippy-driver` should be hard or soft links to `~/.cargo/bin/rustup`. You can repair these by running
 171 `rustup update`.
 172
 173 [glossary]: https://rustc-dev-guide.rust-lang.org/appendix/glossary.html