diff --git a/CHANGELOG.md b/CHANGELOG.md index da7042f44400a..c090a844858b5 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -4382,6 +4382,7 @@ Released 2018-09-13 [`absurd_extreme_comparisons`]: https://rust-lang.github.io/rust-clippy/master/index.html#absurd_extreme_comparisons [`alloc_instead_of_core`]: https://rust-lang.github.io/rust-clippy/master/index.html#alloc_instead_of_core +[`allow_attributes`]: https://rust-lang.github.io/rust-clippy/master/index.html#allow_attributes [`allow_attributes_without_reason`]: https://rust-lang.github.io/rust-clippy/master/index.html#allow_attributes_without_reason [`almost_complete_letter_range`]: https://rust-lang.github.io/rust-clippy/master/index.html#almost_complete_letter_range [`almost_complete_range`]: https://rust-lang.github.io/rust-clippy/master/index.html#almost_complete_range diff --git a/clippy_lints/src/allow_attributes.rs b/clippy_lints/src/allow_attributes.rs new file mode 100644 index 0000000000000..15d46e954a9a5 --- /dev/null +++ b/clippy_lints/src/allow_attributes.rs @@ -0,0 +1,71 @@ +use ast::AttrStyle; +use clippy_utils::diagnostics::span_lint_and_sugg; +use rustc_ast as ast; +use rustc_errors::Applicability; +use rustc_lint::{LateContext, LateLintPass}; +use rustc_session::{declare_lint_pass, declare_tool_lint}; + +declare_clippy_lint! { + /// Detects uses of the `#[allow]` attribute and suggests replacing it with + /// the `#[expect]` (See [RFC 2383](https://rust-lang.github.io/rfcs/2383-lint-reasons.html)) + /// + /// The expect attribute is still unstable and requires the `lint_reasons` + /// on nightly. It can be enabled by adding `#![feature(lint_reasons)]` to + /// the crate root. + /// + /// This lint only warns outer attributes (`#[allow]`), as inner attributes + /// (`#![allow]`) are usually used to enable or disable lints on a global scale. + /// + /// ### Why is this bad? + /// + /// `#[expect]` attributes suppress the lint emission, but emit a warning, if + /// the expectation is unfulfilled. This can be useful to be notified when the + /// lint is no longer triggered. + /// + /// ### Example + /// ```rust,ignore + /// #[allow(unused_mut)] + /// fn foo() -> usize { + /// let mut a = Vec::new(); + /// a.len() + /// } + /// ``` + /// Use instead: + /// ```rust,ignore + /// #![feature(lint_reasons)] + /// #[expect(unused_mut)] + /// fn foo() -> usize { + /// let mut a = Vec::new(); + /// a.len() + /// } + /// ``` + #[clippy::version = "1.69.0"] + pub ALLOW_ATTRIBUTES, + restriction, + "`#[allow]` will not trigger if a warning isn't found. `#[expect]` triggers if there are no warnings." +} + +declare_lint_pass!(AllowAttribute => [ALLOW_ATTRIBUTES]); + +impl LateLintPass<'_> for AllowAttribute { + // Separate each crate's features. + fn check_attribute(&mut self, cx: &LateContext<'_>, attr: &ast::Attribute) { + if_chain! { + if cx.tcx.features().lint_reasons; + if let AttrStyle::Outer = attr.style; + if let Some(ident) = attr.ident(); + if ident.name == rustc_span::symbol::sym::allow; + then { + span_lint_and_sugg( + cx, + ALLOW_ATTRIBUTES, + ident.span, + "#[allow] attribute found", + "replace it with", + "expect".into(), + Applicability::MachineApplicable, + ); + } + } + } +} diff --git a/clippy_lints/src/declared_lints.rs b/clippy_lints/src/declared_lints.rs index cc6024b87cdae..25f159734903a 100644 --- a/clippy_lints/src/declared_lints.rs +++ b/clippy_lints/src/declared_lints.rs @@ -35,6 +35,7 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[ crate::utils::internal_lints::produce_ice::PRODUCE_ICE_INFO, #[cfg(feature = "internal")] crate::utils::internal_lints::unnecessary_def_path::UNNECESSARY_DEF_PATH_INFO, + crate::allow_attributes::ALLOW_ATTRIBUTES_INFO, crate::almost_complete_range::ALMOST_COMPLETE_RANGE_INFO, crate::approx_const::APPROX_CONSTANT_INFO, crate::as_conversions::AS_CONVERSIONS_INFO, diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs index bde84686cc1b9..4bb0e2ec96ca1 100644 --- a/clippy_lints/src/lib.rs +++ b/clippy_lints/src/lib.rs @@ -67,6 +67,7 @@ mod declared_lints; mod renamed_lints; // begin lints modules, do not remove this comment, it’s used in `update_lints` +mod allow_attributes; mod almost_complete_range; mod approx_const; mod as_conversions; @@ -934,6 +935,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: store.register_late_pass(|_| Box::new(missing_assert_message::MissingAssertMessage)); store.register_early_pass(|| Box::new(redundant_async_block::RedundantAsyncBlock)); store.register_late_pass(|_| Box::new(let_with_type_underscore::UnderscoreTyped)); + store.register_late_pass(|_| Box::new(allow_attributes::AllowAttribute)); // add lints here, do not remove this comment, it's used in `new_lint` } diff --git a/tests/ui/allow_attributes.fixed b/tests/ui/allow_attributes.fixed new file mode 100644 index 0000000000000..b8dd0619e6d00 --- /dev/null +++ b/tests/ui/allow_attributes.fixed @@ -0,0 +1,25 @@ +// run-rustfix +#![allow(unused)] +#![warn(clippy::allow_attributes)] +#![feature(lint_reasons)] + +fn main() {} + +// Using clippy::needless_borrow just as a placeholder, it isn't relevant. + +// Should lint +#[expect(dead_code)] +struct T1; + +struct T2; // Should not lint +#[deny(clippy::needless_borrow)] // Should not lint +struct T3; +#[warn(clippy::needless_borrow)] // Should not lint +struct T4; +// `panic = "unwind"` should always be true +#[cfg_attr(panic = "unwind", expect(dead_code))] +struct CfgT; + +fn ignore_inner_attr() { + #![allow(unused)] // Should not lint +} diff --git a/tests/ui/allow_attributes.rs b/tests/ui/allow_attributes.rs new file mode 100644 index 0000000000000..295f560906a78 --- /dev/null +++ b/tests/ui/allow_attributes.rs @@ -0,0 +1,25 @@ +// run-rustfix +#![allow(unused)] +#![warn(clippy::allow_attributes)] +#![feature(lint_reasons)] + +fn main() {} + +// Using clippy::needless_borrow just as a placeholder, it isn't relevant. + +// Should lint +#[allow(dead_code)] +struct T1; + +struct T2; // Should not lint +#[deny(clippy::needless_borrow)] // Should not lint +struct T3; +#[warn(clippy::needless_borrow)] // Should not lint +struct T4; +// `panic = "unwind"` should always be true +#[cfg_attr(panic = "unwind", allow(dead_code))] +struct CfgT; + +fn ignore_inner_attr() { + #![allow(unused)] // Should not lint +} diff --git a/tests/ui/allow_attributes.stderr b/tests/ui/allow_attributes.stderr new file mode 100644 index 0000000000000..681837e9ed770 --- /dev/null +++ b/tests/ui/allow_attributes.stderr @@ -0,0 +1,16 @@ +error: #[allow] attribute found + --> $DIR/allow_attributes.rs:11:3 + | +LL | #[allow(dead_code)] + | ^^^^^ help: replace it with: `expect` + | + = note: `-D clippy::allow-attributes` implied by `-D warnings` + +error: #[allow] attribute found + --> $DIR/allow_attributes.rs:20:30 + | +LL | #[cfg_attr(panic = "unwind", allow(dead_code))] + | ^^^^^ help: replace it with: `expect` + +error: aborting due to 2 previous errors +