style(all): replace #[allow] with #[expect] (#8930)

Replace `#[allow]` with `#[expect]` through the whole codebase.

This also surfaced many places where the `#[allow]` attributes were outdated/pointless and could be removed entirely.

Only places `#[allow]` remains are:

1. In generated code and macros, where lint errors may or may not be triggered depending on the generated code.
2. A few places where clippy malfunctions. These use e.g. `#[allow(unused, clippy::allow_attributes)]`.

apps/oxlint/src/command/lint.rs

@@ -191,7 +191,7 @@ pub struct OutputOptions {
 }
 
 /// Enable Plugins
-#[allow(clippy::struct_field_names)]
+#[expect(clippy::struct_field_names)]
 #[derive(Debug, Default, Clone, Bpaf)]
 pub struct EnablePlugins {
     /// Disable react plugin, which is turned on by default
@@ -270,7 +270,6 @@ pub struct EnablePlugins {
 /// changing default behavior if they're not explicitly passed by the user. This scheme is a bit
 /// convoluted, but needed due to architectural constraints imposed by `bpaf`.
 #[derive(Default, Debug, Clone, Copy, PartialEq, Eq)]
-#[allow(clippy::enum_variant_names)]
 pub enum OverrideToggle {
     /// Override the option to enabled
     Enable,
@@ -439,7 +438,7 @@ mod lint_options {
     }
 
     #[test]
-    #[allow(clippy::similar_names)]
+    #[expect(clippy::similar_names)]
     fn multiple_paths() {
         let temp_dir = tempfile::tempdir().expect("Could not create a temp dir");
         let file_foo = temp_dir.path().join("foo.js");

apps/oxlint/src/command/mod.rs

@@ -32,7 +32,7 @@ pub struct MiscOptions {
     pub print_config: bool,
 }
 
-#[allow(clippy::ptr_arg)]
+#[expect(clippy::ptr_arg)]
 fn validate_paths(paths: &Vec<PathBuf>) -> bool {
     if paths.is_empty() {
         true

apps/oxlint/src/output_formatter/json.rs

@@ -60,7 +60,6 @@ impl DiagnosticReporter for JsonReporter {
 }
 
 /// <https://github.com/fregante/eslint-formatters/tree/ae1fd9748596447d1fd09625c33d9e7ba9a3d06d/packages/eslint-formatter-json>
-#[allow(clippy::print_stdout)]
 fn format_json(diagnostics: &mut Vec<Error>) -> String {
     let handler = JSONReportHandler::new();
     let messages = diagnostics

apps/oxlint/src/result.rs

@@ -19,7 +19,6 @@ pub enum CliRunResult {
 }
 
 impl Termination for CliRunResult {
-    #[allow(clippy::print_stdout, clippy::print_stderr)]
     fn report(self) -> ExitCode {
         match self {
             Self::None

crates/oxc/examples/compiler.rs

@@ -1,4 +1,4 @@
-#![allow(clippy::print_stdout)]
+#![expect(clippy::print_stdout)]
 
 use std::{env, io, path::Path};
 

crates/oxc/src/compiler.rs

@@ -263,7 +263,6 @@ pub trait CompilerInterface {
         self.after_isolated_declarations(ret);
     }
 
-    #[allow(clippy::too_many_arguments)]
     fn transform<'a>(
         &self,
         options: &TransformOptions,

crates/oxc_allocator/src/boxed.rs

@@ -64,7 +64,7 @@ impl<T> Box<'_, T> {
     /// # SAFETY
     /// Safe to create, but must never be dereferenced, as does not point to a valid `T`.
     /// Only purpose is for mocking types without allocating for const assertions.
-    #[allow(unsafe_code, clippy::missing_safety_doc)]
+    #[expect(unsafe_code, clippy::missing_safety_doc)]
     pub const unsafe fn dangling() -> Self {
         const { Self::ASSERT_T_IS_NOT_DROP };
 

crates/oxc_allocator/src/convert.rs

@@ -1,4 +1,4 @@
-#![allow(clippy::inline_always)]
+#![expect(clippy::inline_always)]
 
 use crate::{Allocator, Box};
 

crates/oxc_ast/src/ast/js.rs

@@ -1,4 +1,4 @@
-#![allow(missing_docs)] // FIXME
+#![expect(missing_docs)] // FIXME
 
 // NB: `#[span]`, `#[scope(...)]`,`#[visit(...)]` and `#[generate_derive(...)]` do NOT do anything to the code.
 // They are purely markers for codegen used in `tasks/ast_tools` and `crates/oxc_traverse/scripts`. See docs in those crates.

crates/oxc_ast/src/ast/macros.rs

@@ -891,7 +891,6 @@ macro_rules! shared_enum_variants {
             #[inline]
             pub fn $as_child(&self) -> Option<&$child<'a>> {
                 if self.$is_child() {
-                    #[allow(unsafe_code)]
                     // SAFETY: Transmute is safe because discriminants + types are identical between
                     // `$parent` and `$child` for $child variants
                     Some(unsafe { &*std::ptr::from_ref(self).cast::<$child>() })
@@ -904,7 +903,6 @@ macro_rules! shared_enum_variants {
             #[inline]
             pub fn $as_child_mut(&mut self) -> Option<&mut $child<'a>> {
                 if self.$is_child() {
-                    #[allow(unsafe_code)]
                     // SAFETY: Transmute is safe because discriminants + types are identical between
                     // `$parent` and `$child` for $child variants
                     Some(unsafe { &mut *std::ptr::from_mut(self).cast::<$child>() })
@@ -966,7 +964,7 @@ pub(crate) use shared_enum_variants;
 /// <https://doc.rust-lang.org/std/mem/fn.discriminant.html>
 macro_rules! discriminant {
     ($ty:ident :: $variant:ident) => {{
-        #[allow(unsafe_code, clippy::undocumented_unsafe_blocks)]
+        #[expect(clippy::undocumented_unsafe_blocks)]
         unsafe {
             let t = std::mem::ManuallyDrop::new($ty::$variant(oxc_allocator::Box::dangling()));
             *(std::ptr::addr_of!(t).cast::<u8>())

crates/oxc_ast/src/ast/ts.rs

@@ -2,7 +2,7 @@
 //!
 //! - [AST Spec](https://github.com/typescript-eslint/typescript-eslint/tree/v8.9.0/packages/ast-spec)
 //! - [Archived TypeScript spec](https://github.com/microsoft/TypeScript/blob/3c99d50da5a579d9fa92d02664b1b66d4ff55944/doc/spec-ARCHIVED.md)
-#![allow(missing_docs)] // FIXME
+#![expect(missing_docs)] // FIXME
 
 // NB: `#[span]`, `#[scope(...)]`,`#[visit(...)]` and `#[generate_derive(...)]` do NOT do anything to the code.
 // They are purely markers for codegen used in `tasks/ast_tools` and `crates/oxc_traverse/scripts`. See docs in those crates.

crates/oxc_ast/src/ast_builder_impl.rs

@@ -1,9 +1,3 @@
-#![allow(
-    clippy::fn_params_excessive_bools,
-    clippy::must_use_candidate, // must_use_candidate is too annoying for this file
-    clippy::too_many_arguments,
-    clippy::unused_self,
-)]
 #![warn(missing_docs)]
 
 use std::{borrow::Cow, mem};
@@ -16,7 +10,6 @@ use crate::{ast::*, AstBuilder};
 
 /// Type that can be used in any AST builder method call which requires an `IntoIn<'a, Anything<'a>>`.
 /// Pass `NONE` instead of `None::<Anything<'a>>`.
-#[allow(clippy::upper_case_acronyms)]
 pub struct NONE;
 
 impl<'a, T> FromIn<'a, NONE> for Option<Box<'a, T>> {
@@ -105,7 +98,7 @@ impl<'a> AstBuilder<'a> {
     /// This method is completely unsound and should not be used.
     /// We need to remove all uses of it. Please don't add any more!
     /// <https://github.com/oxc-project/oxc/issues/3483>
-    #[allow(clippy::missing_safety_doc)]
+    #[expect(clippy::missing_safety_doc)]
     #[inline]
     pub unsafe fn copy<T>(self, src: &T) -> T {
         // SAFETY: Not safe (see above)

crates/oxc_ast/src/ast_impl/jsx.rs

@@ -34,7 +34,7 @@ impl<'a> JSXElementName<'a> {
         }
     }
 
-    #[allow(missing_docs)]
+    #[expect(missing_docs)]
     pub fn get_identifier_name(&self) -> Option<Atom<'a>> {
         match self {
             Self::Identifier(id) => Some(id.as_ref().name),

crates/oxc_ast/src/ast_impl/literal.rs

@@ -37,7 +37,7 @@ impl NumericLiteral<'_> {
     /// port from [closure compiler](https://github.com/google/closure-compiler/blob/a4c880032fba961f7a6c06ef99daa3641810bfdd/src/com/google/javascript/jscomp/base/JSCompDoubles.java#L113)
     ///
     /// <https://262.ecma-international.org/5.1/#sec-9.5>
-    #[allow(clippy::cast_possible_truncation)] // for `as i32`
+    #[expect(clippy::cast_possible_truncation)] // for `as i32`
     pub fn ecmascript_to_int32(num: f64) -> i32 {
         // Fast path for most common case. Also covers -0.0
         let int32_value = num as i32;

crates/oxc_ast/src/ast_kind_impl.rs

@@ -1,4 +1,4 @@
-#![allow(missing_docs)] // FIXME
+#![expect(missing_docs)] // FIXME
 use oxc_span::Atom;
 use oxc_syntax::scope::ScopeId;
 
@@ -172,7 +172,6 @@ impl<'a> AstKind<'a> {
 }
 
 impl AstKind<'_> {
-    #[allow(clippy::match_same_arms)]
     /// Get the AST kind name with minimal details. Particularly useful for
     /// when debugging an iteration over an AST.
     ///

crates/oxc_ast/src/generated/ast_builder.rs

@@ -3,7 +3,7 @@
 
 //! AST node factories
 
-#![allow(
+#![expect(
     clippy::default_trait_access,
     clippy::too_many_arguments,
     clippy::fn_params_excessive_bools

crates/oxc_ast/src/generated/ast_kind.rs

@@ -1,7 +1,7 @@
 // Auto-generated code, DO NOT EDIT DIRECTLY!
 // To edit this generated file you have to edit `tasks/ast_tools/src/generators/ast_kind.rs`
 
-#![allow(missing_docs)]
+#![expect(missing_docs)]
 // FIXME (in ast_tools/src/generators/ast_kind.rs)
 
 use std::ptr;

crates/oxc_ast/src/generated/derive_get_address.rs

@@ -1,7 +1,7 @@
 // Auto-generated code, DO NOT EDIT DIRECTLY!
 // To edit this generated file you have to edit `tasks/ast_tools/src/derives/get_address.rs`
 
-#![allow(clippy::match_same_arms)]
+#![expect(clippy::match_same_arms)]
 
 use oxc_allocator::{Address, GetAddress};
 

crates/oxc_ast/src/generated/derive_get_span.rs

@@ -1,7 +1,7 @@
 // Auto-generated code, DO NOT EDIT DIRECTLY!
 // To edit this generated file you have to edit `tasks/ast_tools/src/derives/get_span.rs`
 
-#![allow(clippy::match_same_arms)]
+#![expect(clippy::match_same_arms)]
 
 use oxc_span::{GetSpan, Span};
 

crates/oxc_ast/src/generated/derive_get_span_mut.rs

@@ -1,7 +1,7 @@
 // Auto-generated code, DO NOT EDIT DIRECTLY!
 // To edit this generated file you have to edit `tasks/ast_tools/src/derives/get_span.rs`
 
-#![allow(clippy::match_same_arms)]
+#![expect(clippy::match_same_arms)]
 
 use oxc_span::{GetSpanMut, Span};
 

crates/oxc_ast/src/generated/visit.rs

@@ -7,7 +7,7 @@
 //! * [visitor pattern](https://rust-unofficial.github.io/patterns/patterns/behavioural/visitor.html)
 //! * [rustc visitor](https://github.com/rust-lang/rust/blob/1.82.0/compiler/rustc_ast/src/visit.rs)
 
-#![allow(unused_variables, clippy::semicolon_if_nothing_returned)]
+#![expect(unused_variables, clippy::semicolon_if_nothing_returned)]
 
 use std::cell::Cell;
 

crates/oxc_ast/src/generated/visit_mut.rs

@@ -7,7 +7,7 @@
 //! * [visitor pattern](https://rust-unofficial.github.io/patterns/patterns/behavioural/visitor.html)
 //! * [rustc visitor](https://github.com/rust-lang/rust/blob/1.82.0/compiler/rustc_ast/src/visit.rs)
 
-#![allow(unused_variables, clippy::semicolon_if_nothing_returned)]
+#![expect(unused_variables, clippy::semicolon_if_nothing_returned)]
 
 use std::cell::Cell;
 

crates/oxc_ast/src/lib.rs

@@ -39,9 +39,6 @@
 //! [tsc]: <https://github.com/microsoft/TypeScript>
 //! [`Traverse`]: <https://github.com/oxc-project/oxc/tree/main/crates/oxc_traverse>
 
-// TODO: I'm not sure if it is a but or intentional but clippy needs this allowed both on this
-// module and the generated one.
-#![allow(clippy::self_named_module_files)]
 #![warn(missing_docs)]
 
 #[cfg(feature = "serialize")]
@@ -57,7 +54,7 @@ mod trivia;
 pub mod utf8_to_utf16;
 
 mod generated {
-    #![allow(missing_docs)]
+    #![expect(missing_docs)]
     #[cfg(debug_assertions)]
     pub mod assert_layouts;
     pub mod ast_builder;
@@ -75,7 +72,7 @@ mod generated {
 }
 
 pub mod visit {
-    #![allow(missing_docs)]
+    #![expect(missing_docs)]
     pub use crate::generated::{visit::*, visit_mut::*};
 }
 

crates/oxc_ast/src/trivia.rs

@@ -1,5 +1,5 @@
 //! Trivias such as comments and irregular whitespaces
-#![allow(missing_docs)] // FIXME
+#![expect(missing_docs)] // FIXME
 
 use std::{
     iter::FusedIterator,

crates/oxc_ast/src/utf8_to_utf16.rs

@@ -41,7 +41,7 @@ impl Utf8ToUtf16 {
         }
     }
 
-    #[allow(clippy::cast_possible_truncation)]
+    #[expect(clippy::cast_possible_truncation)]
     fn build_table(&mut self, source_text: &str) {
         // Translation from UTF-8 byte offset to UTF-16 char offset:
         //

crates/oxc_cfg/src/builder/context.rs

@@ -39,7 +39,7 @@ impl<'a> Ctx<'a> {
 }
 
 pub trait CtxCursor {
-    #![allow(clippy::return_self_not_must_use)]
+    #![expect(clippy::return_self_not_must_use)]
     /// Marks the break jump position in the current context.
     fn mark_break(self, jmp_pos: BlockNodeId) -> Self;
     /// Marks the continue jump position in the current context.
@@ -87,9 +87,9 @@ impl CtxCursor for QueryCtx<'_, '_> {
 impl<'a, 'c> QueryCtx<'a, 'c> {
     /// Creates a new `Ctx` with the given `CtxFlags` and returns a `RefCtxCursor` to it.
     #[inline]
-    #[allow(clippy::wrong_self_convention, clippy::new_ret_no_self)]
+    #[expect(clippy::wrong_self_convention, clippy::new_ret_no_self)]
     pub fn new(self, flags: CtxFlags) -> RefCtxCursor<'a, 'c> {
-        #![allow(unsafe_code)]
+        #![expect(unsafe_code)]
         self.0.ctx_stack.push(Ctx::new(self.1, flags));
         // SAFETY: we just pushed this `Ctx` into the stack.
         let ctx = unsafe { self.0.ctx_stack.last_mut().unwrap_unchecked() };

crates/oxc_cfg/src/lib.rs

@@ -32,7 +32,7 @@ pub type BlockNodeId = petgraph::stable_graph::NodeIndex;
 pub struct BasicBlockId(NonMaxU32);
 
 impl Idx for BasicBlockId {
-    #[allow(clippy::cast_possible_truncation)]
+    #[expect(clippy::cast_possible_truncation)]
     fn from_usize(idx: usize) -> Self {
         assert!(idx < u32::MAX as usize);
         // SAFETY: We just checked `idx` is valid for `NonMaxU32`

crates/oxc_cfg/src/visit.rs

@@ -71,15 +71,16 @@ macro_rules! try_control {
     };
     ($e:expr, $p:stmt, $q:stmt) => {
         match $e {
-            x =>
-            {
-                #[allow(clippy::redundant_else)]
-                if x.should_break() {
-                    return x;
-                } else if x.should_prune() {
-                    $p
-                } else {
-                    $q
+            x => {
+                #[allow(clippy::redundant_else, clippy::allow_attributes)]
+                {
+                    if x.should_break() {
+                        return x;
+                    } else if x.should_prune() {
+                        $p
+                    } else {
+                        $q
+                    }
                 }
             }
         }

crates/oxc_codegen/examples/codegen.rs

@@ -1,4 +1,4 @@
-#![allow(clippy::print_stdout)]
+#![expect(clippy::print_stdout)]
 use std::path::Path;
 
 use oxc_allocator::Allocator;

crates/oxc_codegen/examples/sourcemap.rs

@@ -1,4 +1,4 @@
-#![allow(clippy::print_stdout)]
+#![expect(clippy::print_stdout)]
 use std::{env, path::Path};
 
 use base64::{prelude::BASE64_STANDARD, Engine};

crates/oxc_codegen/src/code_buffer.rs

@@ -506,7 +506,7 @@ mod test {
     }
 
     #[test]
-    #[allow(clippy::byte_char_slices)]
+    #[expect(clippy::byte_char_slices)]
     fn print_ascii_byte() {
         let mut code = CodeBuffer::new();
         code.print_ascii_byte(b'f');
@@ -519,7 +519,7 @@ mod test {
     }
 
     #[test]
-    #[allow(clippy::byte_char_slices)]
+    #[expect(clippy::byte_char_slices)]
     fn print_byte_unchecked() {
         let mut code = CodeBuffer::new();
         // SAFETY: These bytes are all ASCII
@@ -535,7 +535,7 @@ mod test {
     }
 
     #[test]
-    #[allow(clippy::byte_char_slices)]
+    #[expect(clippy::byte_char_slices)]
     fn print_ascii_bytes() {
         let mut code = CodeBuffer::new();
         code.print_ascii_bytes([b'f', b'o', b'o']);

crates/oxc_codegen/src/context.rs

@@ -1,4 +1,4 @@
-#![allow(missing_docs)] // FIXME
+#![expect(missing_docs)] // FIXME
 use bitflags::bitflags;
 
 bitflags! {

crates/oxc_codegen/src/lib.rs

@@ -693,7 +693,7 @@ impl<'a> Codegen<'a> {
 
     // `get_minified_number` from terser
     // https://github.com/terser/terser/blob/c5315c3fd6321d6b2e076af35a70ef532f498505/lib/output.js#L2418
-    #[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss, clippy::cast_possible_wrap)]
+    #[expect(clippy::cast_possible_truncation, clippy::cast_sign_loss, clippy::cast_possible_wrap)]
     fn get_minified_number(num: f64, buffer: &mut ryu_js::Buffer) -> Cow<'_, str> {
         use cow_utils::CowUtils;