From 783c119768c14e1349c49c599410b7e0e60e0c4e Mon Sep 17 00:00:00 2001 From: Philipp Krones Date: Wed, 16 Aug 2023 14:36:09 +0200 Subject: [PATCH] Address review comments and formatting --- book/src/development/defining_lints.md | 94 ++++++++++++++------------ 1 file changed, 50 insertions(+), 44 deletions(-) diff --git a/book/src/development/defining_lints.md b/book/src/development/defining_lints.md index 14854233850..7c4aa5d4523 100644 --- a/book/src/development/defining_lints.md +++ b/book/src/development/defining_lints.md @@ -2,15 +2,15 @@ The first step in the journey of a new lint is the definition and registration of the lint in Clippy's codebase. -We can use the Clippy dev tools to handle this step since setting up the +We can use the Clippy dev tools to handle this step since setting up the lint involves some boilerplate code. #### Lint types A lint type is the category of items and expressions in which your lint focuses on. -As of the writing of this documentation update, there are 12 groups (a.k.a. _types_) -of lints besides the numerous standalone lints living under `clippy_lints/src/`: +As of the writing of this documentation update, there are 12 _types_ of lints +besides the numerous standalone lints living under `clippy_lints/src/`: - `cargo` - `casts` @@ -25,33 +25,35 @@ of lints besides the numerous standalone lints living under `clippy_lints/src/`: - `unit_types` - `utils / internal` (Clippy internal lints) -These types group together lints that share some common behaviors. -For instance, `functions` groups together lints -that deal with some aspects of function calls in Rust. +These types group together lints that share some common behaviors. For instance, +`functions` groups together lints that deal with some aspects of functions in +Rust, like definitions, signatures and attributes. For more information, feel free to compare the lint files under any category -with [All Clippy lints][all_lints] or -ask one of the maintainers. +with [All Clippy lints][all_lints] or ask one of the maintainers. ## Lint name -A good lint name is important, make sure to check the [lint naming guidelines][lint_naming]. Don't worry, if -the lint name doesn't fit, a Clippy team member will alert you in the PR process. +A good lint name is important, make sure to check the [lint naming +guidelines][lint_naming]. Don't worry, if the lint name doesn't fit, a Clippy +team member will alert you in the PR process. --- -We'll name our example lint that detects functions named "foo" `foo_functions`. Check the -[lint naming guidelines][lint_naming] to see why this name makes sense. +We'll name our example lint that detects functions named "foo" `foo_functions`. +Check the [lint naming guidelines][lint_naming] to see why this name makes +sense. ## Add and Register the Lint -Now that a name is chosen, we shall register `foo_functions` as a lint to the codebase. -There are two ways to register a lint. +Now that a name is chosen, we shall register `foo_functions` as a lint to the +codebase. There are two ways to register a lint. ### Standalone -If you believe that this new lint is a standalone lint (that doesn't belong to any specific [type](#lint-types) like `functions` or `loops`), you can run the following -command in your Clippy project: +If you believe that this new lint is a standalone lint (that doesn't belong to +any specific [type](#lint-types) like `functions` or `loops`), you can run the +following command in your Clippy project: ```sh $ cargo dev new_lint --name=lint_name --pass=late --category=pedantic @@ -59,13 +61,16 @@ $ cargo dev new_lint --name=lint_name --pass=late --category=pedantic There are two things to note here: -1. We set `--pass=late` in this command to do a late lint pass. The alternative -is an `early` lint pass. We will discuss this difference in a later chapter. - -2. If not provided, the `category` of this new lint will default to `nursery`. +1. `--pass`: We set `--pass=late` in this command to do a late lint pass. The + alternative is an `early` lint pass. We will discuss this difference in a + later chapter. + +2. `--category`: If not provided, the `category` of this new lint will default + to `nursery`. -The `cargo dev new_lint` command will create a new file: `clippy_lints/src/foo_functions.rs` -as well as [register the lint](#lint-registration). +The `cargo dev new_lint` command will create a new file: +`clippy_lints/src/foo_functions.rs` as well as [register the +lint](#lint-registration). Overall, you should notice that the following files are modified or created: @@ -115,7 +120,6 @@ call your lint from within the type's lint pass, found in `clippy_lints/src/{typ A _type_ is just the name of a directory in `clippy_lints/src`, like `functions` in the example command. Clippy groups together some lints that share common behaviors, so if your lint falls into one, it would be best to add it to that type. -Read more about [lint types](#lint-types) below. Overall, you should notice that the following files are modified or created: @@ -138,24 +142,25 @@ Untracked files: ## The `define_clippy_lints` macro -After `cargo dev new_lint`, you should see a macro with the name `define_clippy_lints`. It will be in the same file -if you defined a standalone lint, and it will be in `mod.rs` if you defined a type-specific lint. +After `cargo dev new_lint`, you should see a macro with the name +`define_clippy_lints`. It will be in the same file if you defined a standalone +lint, and it will be in `mod.rs` if you defined a type-specific lint. The macro looks something like this: ```rust declare_clippy_lint! { - /// ### What it does + /// ### What it does + /// + /// // Describe here what does the lint do. + /// + /// Triggers when detects... /// - /// // Describe here what does the lint do. - /// - /// Triggers when detects... - /// /// ### Why is this bad? - /// - /// // Describe why this pattern would be bad - /// - /// It can lead to... + /// + /// // Describe why this pattern would be bad + /// + /// It can lead to... /// /// ### Example /// ```rust @@ -174,25 +179,26 @@ declare_clippy_lint! { ## Lint registration -If we run the `cargo dev new_lint` command for a new lint, -the lint will be automatically registered and there is nothing more to do. +If we run the `cargo dev new_lint` command for a new lint, the lint will be +automatically registered and there is nothing more to do. -However, sometimes we might want to declare a new lint by hand. -In this case, we'd use `cargo dev update_lints` command afterwards. +However, sometimes we might want to declare a new lint by hand. In this case, +we'd use `cargo dev update_lints` command afterwards. When a lint is manually declared, we might need to register the lint pass manually in the `register_plugins` function in `clippy_lints/src/lib.rs`: ```rust -store.register_late_pass(|| Box::new(foo_functions::FooFunctions)); +store.register_late_pass(|_| Box::new(foo_functions::FooFunctions)); ``` -As you might have guessed, where there's something late, there is something early: -in Clippy there is a `register_early_pass` method as well. -More on early vs. late passes in a later chapter. +As you might have guessed, where there's something late, there is something +early: in Clippy there is a `register_early_pass` method as well. More on early +vs. late passes in a later chapter. + -Without a call to one of `register_early_pass` or `register_late_pass`, -the lint pass in question will not be run. +Without a call to one of `register_early_pass` or `register_late_pass`, the lint +pass in question will not be run. [all_lints]: https://rust-lang.github.io/rust-clippy/master/