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Document declare_lint_pass!

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Matthew Kraai 2019-04-07 23:40:59 -07:00
parent ce87051779
commit 24bb63383a
1 changed files with 8 additions and 31 deletions
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39
doc/adding_lints.md
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@ -116,7 +116,7 @@ where all the lint code is. We are going to call the file
```rust ```rust
use rustc::lint::{LintArray, LintPass, EarlyLintPass}; use rustc::lint::{LintArray, LintPass, EarlyLintPass};
use rustc::{declare_tool_lint, lint_array}; use rustc::{declare_lint_pass, declare_tool_lint};
``` ```
The next step is to provide a lint declaration. Lints are declared using the The next step is to provide a lint declaration. Lints are declared using the
@ -147,22 +147,9 @@ lint pass:
// .. imports and lint declaration .. // .. imports and lint declaration ..
#[derive(Copy, Clone)] declare_lint_pass!(FooFunctions => [FOO_FUNCTIONS]);
pub struct FooFunctionsPass;
impl LintPass for FooFunctionsPass { impl EarlyLintPass for FooFunctions {}
fn get_lints(&self) -> LintArray {
lint_array!(
FOO_FUNCTIONS,
)
}
fn name(&self) -> &'static str {
"FooFunctions"
}
}
impl EarlyLintPass for FooFunctionsPass {}
``` ```
Don't worry about the `name` method here. As long as it includes the name of the Don't worry about the `name` method here. As long as it includes the name of the
@ -176,7 +163,7 @@ will have to register our lint pass manually in the `register_plugins` function
in `clippy_lints/src/lib.rs`: in `clippy_lints/src/lib.rs`:
```rust ```rust
reg.register_early_lint_pass(box foo_functions::FooFunctionsPass); reg.register_early_lint_pass(box foo_functions::FooFunctions);
``` ```
This should fix the `unknown clippy lint: clippy::foo_functions` error that we This should fix the `unknown clippy lint: clippy::foo_functions` error that we
@ -211,10 +198,10 @@ use rustc::{declare_tool_lint, lint_array};
With UI tests and the lint declaration in place, we can start working on the With UI tests and the lint declaration in place, we can start working on the
implementation of the lint logic. implementation of the lint logic.
Let's start by implementing the `EarlyLintPass` for our `FooFunctionsPass`: Let's start by implementing the `EarlyLintPass` for our `FooFunctions`:
```rust ```rust
impl EarlyLintPass for FooFunctionsPass { 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<'_>, _: &FnDecl, span: Span, _: NodeId) {
// TODO: Emit lint here // TODO: Emit lint here
} }
@ -236,7 +223,7 @@ provide an extra help message and we can't really suggest a better name
automatically. This is how it looks: automatically. This is how it looks:
```rust ```rust
impl EarlyLintPass for Pass { impl EarlyLintPass for FooFunctions {
fn check_fn(&mut self, cx: &EarlyContext<'_>, _: FnKind<'_>, _: &FnDecl, span: Span, _: NodeId) { fn check_fn(&mut self, cx: &EarlyContext<'_>, _: FnKind<'_>, _: &FnDecl, span: Span, _: NodeId) {
span_help_and_lint( span_help_and_lint(
cx, cx,
@ -263,7 +250,7 @@ Both provide access to the name of the function/method via an [`Ident`][ident].
With that we can expand our `check_fn` method to: With that we can expand our `check_fn` method to:
```rust ```rust
impl EarlyLintPass for Pass { 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<'_>, _: &FnDecl, span: Span, _: NodeId) {
if is_foo_fn(fn_kind) { if is_foo_fn(fn_kind) {
span_help_and_lint( span_help_and_lint(
@ -304,16 +291,6 @@ running `cargo test` should produce the expected output. Remember to run
`cargo test` (as opposed to `cargo uitest`) will also ensure that our lint `cargo test` (as opposed to `cargo uitest`) will also ensure that our lint
implementation is not violating any Clippy lints itself. implementation is not violating any Clippy lints itself.
If you are still following the example, you will see that `FooFunctionsPass`
violates a Clippy lint. So we are going to rename that struct to just `Pass`:
```rust
#[derive(Copy, Clone)]
pub struct Pass;
impl LintPass for Pass { /* .. */ }
```
That should be it for the lint implementation. Running `cargo test` should now That should be it for the lint implementation. Running `cargo test` should now
pass. pass.