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Document `declare_lint_pass!`

This commit is contained in:
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
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
@ -147,22 +147,9 @@ lint pass:
// .. imports and lint declaration ..
#[derive(Copy, Clone)]
pub struct FooFunctionsPass;
declare_lint_pass!(FooFunctions => [FOO_FUNCTIONS]);
impl LintPass for FooFunctionsPass {
fn get_lints(&self) -> LintArray {
lint_array!(
FOO_FUNCTIONS,
)
}
fn name(&self) -> &'static str {
"FooFunctions"
}
}
impl EarlyLintPass for FooFunctionsPass {}
impl EarlyLintPass for FooFunctions {}
```
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`:
```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
@ -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
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
impl EarlyLintPass for FooFunctionsPass {
impl EarlyLintPass for FooFunctions {
fn check_fn(&mut self, cx: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: &FnDecl, span: Span, _: NodeId) {
// 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:
```rust
impl EarlyLintPass for Pass {
impl EarlyLintPass for FooFunctions {
fn check_fn(&mut self, cx: &EarlyContext<'_>, _: FnKind<'_>, _: &FnDecl, span: Span, _: NodeId) {
span_help_and_lint(
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:
```rust
impl EarlyLintPass for Pass {
impl EarlyLintPass for FooFunctions {
fn check_fn(&mut self, cx: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: &FnDecl, span: Span, _: NodeId) {
if is_foo_fn(fn_kind) {
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
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
pass.