rustc_ast/
visit.rs

1//! AST walker. Each overridden visit method has full control over what
2//! happens with its node, it can do its own traversal of the node's children,
3//! call `visit::walk_*` to apply the default traversal algorithm, or prevent
4//! deeper traversal by doing nothing.
5//!
6//! Note: it is an important invariant that the default visitor walks the body
7//! of a function in "execution order" (more concretely, reverse post-order
8//! with respect to the CFG implied by the AST), meaning that if AST node A may
9//! execute before AST node B, then A is visited first. The borrow checker in
10//! particular relies on this property.
11//!
12//! Note: walking an AST before macro expansion is probably a bad idea. For
13//! instance, a walker looking for item names in a module will miss all of
14//! those that are created by the expansion of a macro.
15
16pub use rustc_ast_ir::visit::VisitorResult;
17pub use rustc_ast_ir::{try_visit, visit_opt, walk_list, walk_visitable_list};
18use rustc_span::source_map::Spanned;
19use rustc_span::{Ident, Span, Symbol};
20use thin_vec::ThinVec;
21
22use crate::ast::*;
23use crate::tokenstream::DelimSpan;
24
25#[derive(Copy, Clone, Debug, PartialEq)]
26pub enum AssocCtxt {
27    Trait,
28    Impl { of_trait: bool },
29}
30
31#[derive(Copy, Clone, Debug, PartialEq)]
32pub enum FnCtxt {
33    Free,
34    Foreign,
35    Assoc(AssocCtxt),
36}
37
38#[derive(Copy, Clone, Debug)]
39pub enum BoundKind {
40    /// Trait bounds in generics bounds and type/trait alias.
41    /// E.g., `<T: Bound>`, `type A: Bound`, or `where T: Bound`.
42    Bound,
43
44    /// Trait bounds in `impl` type.
45    /// E.g., `type Foo = impl Bound1 + Bound2 + Bound3`.
46    Impl,
47
48    /// Trait bounds in trait object type.
49    /// E.g., `dyn Bound1 + Bound2 + Bound3`.
50    TraitObject,
51
52    /// Super traits of a trait.
53    /// E.g., `trait A: B`
54    SuperTraits,
55}
56impl BoundKind {
57    pub fn descr(self) -> &'static str {
58        match self {
59            BoundKind::Bound => "bounds",
60            BoundKind::Impl => "`impl Trait`",
61            BoundKind::TraitObject => "`dyn` trait object bounds",
62            BoundKind::SuperTraits => "supertrait bounds",
63        }
64    }
65}
66
67#[derive(Copy, Clone, Debug)]
68pub enum LifetimeCtxt {
69    /// Appears in a reference type.
70    Ref,
71    /// Appears as a bound on a type or another lifetime.
72    Bound,
73    /// Appears as a generic argument.
74    GenericArg,
75}
76
77pub(crate) trait Visitable<'a, V: Visitor<'a>> {
78    type Extra: Copy;
79
80    #[must_use]
81    fn visit(&'a self, visitor: &mut V, extra: Self::Extra) -> V::Result;
82}
83
84impl<'a, V: Visitor<'a>, T: ?Sized> Visitable<'a, V> for Box<T>
85where
86    T: Visitable<'a, V>,
87{
88    type Extra = T::Extra;
89    fn visit(&'a self, visitor: &mut V, extra: Self::Extra) -> V::Result {
90        (**self).visit(visitor, extra)
91    }
92}
93
94impl<'a, V: Visitor<'a>, T> Visitable<'a, V> for Option<T>
95where
96    T: Visitable<'a, V>,
97{
98    type Extra = T::Extra;
99    fn visit(&'a self, visitor: &mut V, extra: Self::Extra) -> V::Result {
100        if let Some(this) = self {
101            try_visit!(this.visit(visitor, extra));
102        }
103        V::Result::output()
104    }
105}
106
107impl<'a, V: Visitor<'a>, T> Visitable<'a, V> for Spanned<T>
108where
109    T: Visitable<'a, V>,
110{
111    type Extra = T::Extra;
112    fn visit(&'a self, visitor: &mut V, extra: Self::Extra) -> V::Result {
113        let Spanned { span: _, node } = self;
114        node.visit(visitor, extra)
115    }
116}
117
118impl<'a, V: Visitor<'a>, T> Visitable<'a, V> for [T]
119where
120    T: Visitable<'a, V>,
121{
122    type Extra = T::Extra;
123    fn visit(&'a self, visitor: &mut V, extra: Self::Extra) -> V::Result {
124        for item in self {
125            try_visit!(item.visit(visitor, extra));
126        }
127        V::Result::output()
128    }
129}
130
131impl<'a, V: Visitor<'a>, T> Visitable<'a, V> for Vec<T>
132where
133    T: Visitable<'a, V>,
134{
135    type Extra = T::Extra;
136    fn visit(&'a self, visitor: &mut V, extra: Self::Extra) -> V::Result {
137        for item in self {
138            try_visit!(item.visit(visitor, extra));
139        }
140        V::Result::output()
141    }
142}
143
144impl<'a, V: Visitor<'a>, T> Visitable<'a, V> for (T,)
145where
146    T: Visitable<'a, V>,
147{
148    type Extra = T::Extra;
149    fn visit(&'a self, visitor: &mut V, extra: Self::Extra) -> V::Result {
150        self.0.visit(visitor, extra)
151    }
152}
153
154impl<'a, V: Visitor<'a>, T1, T2> Visitable<'a, V> for (T1, T2)
155where
156    T1: Visitable<'a, V, Extra = ()>,
157    T2: Visitable<'a, V, Extra = ()>,
158{
159    type Extra = ();
160    fn visit(&'a self, visitor: &mut V, extra: Self::Extra) -> V::Result {
161        try_visit!(self.0.visit(visitor, extra));
162        try_visit!(self.1.visit(visitor, extra));
163        V::Result::output()
164    }
165}
166
167impl<'a, V: Visitor<'a>, T1, T2, T3> Visitable<'a, V> for (T1, T2, T3)
168where
169    T1: Visitable<'a, V, Extra = ()>,
170    T2: Visitable<'a, V, Extra = ()>,
171    T3: Visitable<'a, V, Extra = ()>,
172{
173    type Extra = ();
174    fn visit(&'a self, visitor: &mut V, extra: Self::Extra) -> V::Result {
175        try_visit!(self.0.visit(visitor, extra));
176        try_visit!(self.1.visit(visitor, extra));
177        try_visit!(self.2.visit(visitor, extra));
178        V::Result::output()
179    }
180}
181
182impl<'a, V: Visitor<'a>, T1, T2, T3, T4> Visitable<'a, V> for (T1, T2, T3, T4)
183where
184    T1: Visitable<'a, V, Extra = ()>,
185    T2: Visitable<'a, V, Extra = ()>,
186    T3: Visitable<'a, V, Extra = ()>,
187    T4: Visitable<'a, V, Extra = ()>,
188{
189    type Extra = ();
190    fn visit(&'a self, visitor: &mut V, extra: Self::Extra) -> V::Result {
191        try_visit!(self.0.visit(visitor, extra));
192        try_visit!(self.1.visit(visitor, extra));
193        try_visit!(self.2.visit(visitor, extra));
194        try_visit!(self.3.visit(visitor, extra));
195        V::Result::output()
196    }
197}
198
199pub(crate) trait Walkable<'a, V: Visitor<'a>> {
200    #[must_use]
201    fn walk_ref(&'a self, visitor: &mut V) -> V::Result;
202}
203
204macro_rules! visit_visitable {
205    ($visitor:expr, $($expr:expr),* $(,)?) => {{
206        $(try_visit!(Visitable::visit($expr, $visitor, ()));)*
207    }};
208}
209
210macro_rules! visit_visitable_with {
211    ($visitor:expr, $expr:expr, $extra:expr $(,)?) => {
212        try_visit!(Visitable::visit($expr, $visitor, $extra))
213    };
214}
215
216macro_rules! walk_walkable {
217    ($visitor:expr, $expr:expr, ) => {
218        Walkable::walk_ref($expr, $visitor)
219    };
220}
221
222macro_rules! impl_visitable {
223    (|&$lt:lifetime $self:ident: $self_ty:ty,
224      $vis:ident: &mut $vis_ty:ident,
225      $extra:ident: $extra_ty:ty| $block:block) => {
226        #[allow(unused_parens, non_local_definitions)]
227        impl<$lt, $vis_ty: Visitor<$lt>> Visitable<$lt, $vis_ty> for $self_ty {
228            type Extra = $extra_ty;
229            fn visit(&$lt $self, $vis: &mut $vis_ty, $extra: Self::Extra) -> V::Result {
230                $block
231            }
232        }
233    };
234}
235
236macro_rules! impl_walkable {
237    ($(<$K:ident: $Kb:ident>)? |&$lt:lifetime $self:ident: $self_ty:ty,
238      $vis:ident: &mut $vis_ty:ident| $block:block) => {
239        #[allow(unused_parens, non_local_definitions)]
240        impl<$($K: $Kb,)? $lt, $vis_ty: Visitor<$lt>> Walkable<$lt, $vis_ty> for $self_ty {
241            fn walk_ref(&$lt $self, $vis: &mut $vis_ty) -> V::Result {
242                $block
243            }
244        }
245    };
246}
247
248macro_rules! impl_visitable_noop {
249    (<$lt:lifetime> $($ty:ty,)*) => {
250        $(
251            impl_visitable!(|&$lt self: $ty, _vis: &mut V, _extra: ()| {
252                V::Result::output()
253            });
254        )*
255    };
256}
257
258macro_rules! impl_visitable_list {
259    (<$lt:lifetime> $($ty:ty,)*) => {
260        $(impl<$lt, V: Visitor<$lt>, T> Visitable<$lt, V> for $ty
261        where
262            &$lt $ty: IntoIterator<Item = &$lt T>,
263            T: $lt + Visitable<$lt, V>,
264        {
265            type Extra = <T as Visitable<$lt, V>>::Extra;
266
267            #[inline]
268            fn visit(&$lt self, visitor: &mut V, extra: Self::Extra) -> V::Result {
269                for i in self {
270                    try_visit!(i.visit(visitor, extra));
271                }
272                V::Result::output()
273            }
274        })*
275    };
276}
277
278macro_rules! impl_visitable_direct {
279    (<$lt:lifetime> $($ty:ty,)*) => {
280        $(impl_visitable!(
281            |&$lt self: $ty, visitor: &mut V, _extra: ()| {
282                Walkable::walk_ref(self, visitor)
283            }
284        );)*
285    };
286}
287
288macro_rules! impl_visitable_calling_walkable {
289    (<$lt:lifetime>
290        $( fn $method:ident($ty:ty $(, $extra_name:ident: $extra_ty:ty)?); )*
291    ) => {
292        $(fn $method(&mut self, node: &$lt $ty $(, $extra_name:$extra_ty)?) -> Self::Result {
293            impl_visitable!(|&$lt self: $ty, visitor: &mut V, extra: ($($extra_ty)?)| {
294                let ($($extra_name)?) = extra;
295                visitor.$method(self $(, $extra_name)?)
296            });
297            walk_walkable!(self, node, )
298        })*
299    };
300}
301
302macro_rules! define_named_walk {
303    ($Visitor:ident<$lt:lifetime>
304        $( pub fn $method:ident($ty:ty); )*
305    ) => {
306        $(pub fn $method<$lt, V: $Visitor<$lt>>(visitor: &mut V, node: &$lt $ty) -> V::Result {
307            walk_walkable!(visitor, node,)
308        })*
309    };
310}
311
312#[macro_export]
313macro_rules! common_visitor_and_walkers {
314    ($(($mut: ident))? $Visitor:ident$(<$lt:lifetime>)?) => {
315        $(${ignore($lt)}
316            #[derive(Copy, Clone)]
317        )?
318        #[derive(Debug)]
319        pub enum FnKind<'a> {
320            /// E.g., `fn foo()`, `fn foo(&self)`, or `extern "Abi" fn foo()`.
321            Fn(FnCtxt, &'a $($mut)? Visibility, &'a $($mut)? Fn),
322
323            /// E.g., `|x, y| body`.
324            Closure(&'a $($mut)? ClosureBinder, &'a $($mut)? Option<CoroutineKind>, &'a $($mut)? Box<FnDecl>, &'a $($mut)? Box<Expr>),
325        }
326
327        impl<'a> FnKind<'a> {
328            pub fn header(&'a $($mut)? self) -> Option<&'a $($mut)? FnHeader> {
329                match *self {
330                    FnKind::Fn(_, _, Fn { sig, .. }) => Some(&$($mut)? sig.header),
331                    FnKind::Closure(..) => None,
332                }
333            }
334
335            pub fn ident(&'a $($mut)? self) -> Option<&'a $($mut)? Ident> {
336                match self {
337                    FnKind::Fn(_, _, Fn { ident, .. }) => Some(ident),
338                    _ => None,
339                }
340            }
341
342            pub fn decl(&'a $($mut)? self) -> &'a $($mut)? FnDecl {
343                match self {
344                    FnKind::Fn(_, _, Fn { sig, .. }) => &$($mut)? sig.decl,
345                    FnKind::Closure(_, _, decl, _) => decl,
346                }
347            }
348
349            pub fn ctxt(&self) -> Option<FnCtxt> {
350                match self {
351                    FnKind::Fn(ctxt, ..) => Some(*ctxt),
352                    FnKind::Closure(..) => None,
353                }
354            }
355        }
356
357        // This macro generates `impl Visitable` and `impl MutVisitable` that do nothing.
358        impl_visitable_noop!(<$($lt)? $($mut)?>
359            AttrId,
360            bool,
361            rustc_span::ByteSymbol,
362            char,
363            crate::token::CommentKind,
364            crate::token::Delimiter,
365            crate::token::Lit,
366            crate::token::LitKind,
367            crate::tokenstream::LazyAttrTokenStream,
368            crate::tokenstream::TokenStream,
369            Movability,
370            Mutability,
371            Pinnedness,
372            Result<(), rustc_span::ErrorGuaranteed>,
373            rustc_data_structures::fx::FxHashMap<Symbol, usize>,
374            rustc_span::ErrorGuaranteed,
375            std::borrow::Cow<'_, str>,
376            Symbol,
377            u8,
378            usize,
379        );
380        // `Span` is only a no-op for the non-mutable visitor.
381        $(impl_visitable_noop!(<$lt> Span,);)?
382
383        // This macro generates `impl Visitable` and `impl MutVisitable` that simply iterate over
384        // their contents. We do not use a generic impl for `ThinVec` because we want to allow
385        // custom visits for the `MutVisitor`.
386        impl_visitable_list!(<$($lt)? $($mut)?>
387            ThinVec<AngleBracketedArg>,
388            ThinVec<Attribute>,
389            ThinVec<(Ident, Option<Ident>)>,
390            ThinVec<(NodeId, Path)>,
391            ThinVec<PathSegment>,
392            ThinVec<PreciseCapturingArg>,
393            ThinVec<Pat>,
394            ThinVec<Box<Ty>>,
395            ThinVec<TyPat>,
396        );
397
398        // This macro generates `impl Visitable` and `impl MutVisitable` that forward to `Walkable`
399        // or `MutWalkable`. By default, all types that do not have a custom visit method in the
400        // visitor should appear here.
401        impl_visitable_direct!(<$($lt)? $($mut)?>
402            AngleBracketedArg,
403            AngleBracketedArgs,
404            AsmMacro,
405            AssignOpKind,
406            AssocItemConstraintKind,
407            AttrArgs,
408            AttrItem,
409            AttrKind,
410            AttrStyle,
411            FnPtrTy,
412            BindingMode,
413            GenBlockKind,
414            RangeLimits,
415            UnsafeBinderCastKind,
416            BinOpKind,
417            BlockCheckMode,
418            BorrowKind,
419            BoundAsyncness,
420            BoundConstness,
421            BoundPolarity,
422            ByRef,
423            Closure,
424            Const,
425            ConstItem,
426            ConstItemRhs,
427            Defaultness,
428            Delegation,
429            DelegationMac,
430            DelimArgs,
431            DelimSpan,
432            EnumDef,
433            Extern,
434            ForLoopKind,
435            FormatArgPosition,
436            FormatArgsPiece,
437            FormatArgument,
438            FormatArgumentKind,
439            FormatArguments,
440            FormatPlaceholder,
441            GenericParamKind,
442            Impl,
443            ImplPolarity,
444            Inline,
445            InlineAsmOperand,
446            InlineAsmRegOrRegClass,
447            InlineAsmTemplatePiece,
448            IsAuto,
449            LocalKind,
450            MacCallStmt,
451            MacStmtStyle,
452            MatchKind,
453            MethodCall,
454            ModKind,
455            ModSpans,
456            MutTy,
457            NormalAttr,
458            Parens,
459            ParenthesizedArgs,
460            PatFieldsRest,
461            PatKind,
462            RangeEnd,
463            RangeSyntax,
464            Recovered,
465            Safety,
466            StaticItem,
467            StrLit,
468            StrStyle,
469            StructExpr,
470            StructRest,
471            Term,
472            Trait,
473            TraitBoundModifiers,
474            TraitObjectSyntax,
475            TyAlias,
476            TyKind,
477            TyPatKind,
478            UnOp,
479            UnsafeBinderTy,
480            UnsafeSource,
481            UseTreeKind,
482            VisibilityKind,
483            WhereBoundPredicate,
484            WhereClause,
485            WhereEqPredicate,
486            WhereRegionPredicate,
487            YieldKind,
488        );
489
490        /// Each method of this trait is a hook to be potentially
491        /// overridden. Each method's default implementation recursively visits
492        /// the substructure of the input via the corresponding `walk` method;
493        #[doc = concat!(" e.g., the `visit_item` method by default calls `visit"$(, "_", stringify!($mut))?, "::walk_item`.")]
494        ///
495        /// If you want to ensure that your code handles every variant
496        /// explicitly, you need to override each method. (And you also need
497        /// to monitor future changes to this trait in case a new method with a
498        /// new default implementation gets introduced.)
499        ///
500        /// Every `walk_*` method uses deconstruction to access fields of structs and
501        /// enums. This will result in a compile error if a field is added, which makes
502        /// it more likely the appropriate visit call will be added for it.
503        pub trait $Visitor<$($lt)?> : Sized $(${ignore($mut)} + MutVisitorResult<Result = ()>)? {
504            $(
505                ${ignore($lt)}
506                /// The result type of the `visit_*` methods. Can be either `()`,
507                /// or `ControlFlow<T>`.
508                type Result: VisitorResult = ();
509            )?
510
511            // Methods in this trait have one of three forms, with the last two forms
512            // only occurring on `MutVisitor`:
513            //
514            //   fn visit_t(&mut self, t: &mut T);                      // common
515            //   fn flat_map_t(&mut self, t: T) -> SmallVec<[T; 1]>;    // rare
516            //   fn filter_map_t(&mut self, t: T) -> Option<T>;         // rarest
517            //
518            // When writing these methods, it is better to use destructuring like this:
519            //
520            //   fn visit_abc(&mut self, ABC { a, b, c: _ }: &mut ABC) {
521            //       visit_a(a);
522            //       visit_b(b);
523            //   }
524            //
525            // than to use field access like this:
526            //
527            //   fn visit_abc(&mut self, abc: &mut ABC) {
528            //       visit_a(&mut abc.a);
529            //       visit_b(&mut abc.b);
530            //       // ignore abc.c
531            //   }
532            //
533            // As well as being more concise, the former is explicit about which fields
534            // are skipped. Furthermore, if a new field is added, the destructuring
535            // version will cause a compile error, which is good. In comparison, the
536            // field access version will continue working and it would be easy to
537            // forget to add handling for it.
538            fn visit_ident(&mut self, Ident { name: _, span }: &$($lt)? $($mut)? Ident) -> Self::Result {
539                impl_visitable!(|&$($lt)? $($mut)? self: Ident, visitor: &mut V, _extra: ()| {
540                    visitor.visit_ident(self)
541                });
542                visit_span(self, span)
543            }
544
545            // This macro defines a custom visit method for each listed type.
546            // It implements `impl Visitable` and `impl MutVisitable` to call those methods on the
547            // visitor.
548            impl_visitable_calling_walkable!(<$($lt)? $($mut)?>
549                fn visit_anon_const(AnonConst);
550                fn visit_arm(Arm);
551                //fn visit_assoc_item(AssocItem, _ctxt: AssocCtxt);
552                fn visit_assoc_item_constraint(AssocItemConstraint);
553                fn visit_attribute(Attribute);
554                fn visit_block(Block);
555                //fn visit_nested_use_tree((UseTree, NodeId));
556                fn visit_capture_by(CaptureBy);
557                fn visit_closure_binder(ClosureBinder);
558                fn visit_contract(FnContract);
559                fn visit_coroutine_kind(CoroutineKind);
560                fn visit_crate(Crate);
561                fn visit_expr(Expr);
562                fn visit_expr_field(ExprField);
563                fn visit_field_def(FieldDef);
564                fn visit_fn_decl(FnDecl);
565                fn visit_fn_header(FnHeader);
566                fn visit_fn_ret_ty(FnRetTy);
567                //fn visit_foreign_item(ForeignItem);
568                fn visit_foreign_mod(ForeignMod);
569                fn visit_format_args(FormatArgs);
570                fn visit_generic_arg(GenericArg);
571                fn visit_generic_args(GenericArgs);
572                fn visit_generic_param(GenericParam);
573                fn visit_generics(Generics);
574                fn visit_inline_asm(InlineAsm);
575                fn visit_inline_asm_sym(InlineAsmSym);
576                //fn visit_item(Item);
577                fn visit_label(Label);
578                fn visit_lifetime(Lifetime, _ctxt: LifetimeCtxt);
579                fn visit_local(Local);
580                fn visit_mac_call(MacCall);
581                fn visit_macro_def(MacroDef);
582                fn visit_param_bound(GenericBound, _ctxt: BoundKind);
583                fn visit_param(Param);
584                fn visit_pat_field(PatField);
585                fn visit_path(Path);
586                fn visit_path_segment(PathSegment);
587                fn visit_pat(Pat);
588                fn visit_poly_trait_ref(PolyTraitRef);
589                fn visit_precise_capturing_arg(PreciseCapturingArg);
590                fn visit_qself(QSelf);
591                fn visit_trait_ref(TraitRef);
592                fn visit_ty_pat(TyPat);
593                fn visit_ty(Ty);
594                fn visit_use_tree(UseTree);
595                fn visit_variant_data(VariantData);
596                fn visit_variant(Variant);
597                fn visit_vis(Visibility);
598                fn visit_where_predicate_kind(WherePredicateKind);
599                fn visit_where_predicate(WherePredicate);
600            );
601
602            // We want `Visitor` to take the `NodeId` by value.
603            fn visit_id(&mut self, _id: $(&$mut)? NodeId) -> Self::Result {
604                $(impl_visitable!(
605                    |&$lt self: NodeId, visitor: &mut V, _extra: ()| {
606                        visitor.visit_id(*self)
607                    }
608                );)?
609                $(impl_visitable!(
610                    |&$mut self: NodeId, visitor: &mut V, _extra: ()| {
611                        visitor.visit_id(self)
612                    }
613                );)?
614                Self::Result::output()
615            }
616
617            /// This method is a hack to workaround unstable of `stmt_expr_attributes`.
618            /// It can be removed once that feature is stabilized.
619            fn visit_method_receiver_expr(&mut self, ex: &$($lt)? $($mut)? Expr) -> Self::Result {
620                self.visit_expr(ex)
621            }
622
623            fn visit_item(&mut self, item: &$($lt)? $($mut)? Item) -> Self::Result {
624                impl_visitable!(|&$($lt)? $($mut)? self: Item, vis: &mut V, _extra: ()| {
625                    vis.visit_item(self)
626                });
627                walk_item(self, item)
628            }
629
630            fn visit_foreign_item(&mut self, item: &$($lt)? $($mut)? ForeignItem) -> Self::Result {
631                impl_visitable!(|&$($lt)? $($mut)? self: ForeignItem, vis: &mut V, _extra: ()| {
632                    vis.visit_foreign_item(self)
633                });
634                walk_item(self, item)
635            }
636
637            fn visit_assoc_item(&mut self, item: &$($lt)? $($mut)? AssocItem, ctxt: AssocCtxt) -> Self::Result {
638                impl_visitable!(|&$($lt)? $($mut)? self: AssocItem, vis: &mut V, ctxt: AssocCtxt| {
639                    vis.visit_assoc_item(self, ctxt)
640                });
641                walk_assoc_item(self, item, ctxt)
642            }
643
644            // for `MutVisitor`: `Span` and `NodeId` are mutated at the caller site.
645            fn visit_fn(
646                &mut self,
647                fk: FnKind<$($lt)? $(${ignore($mut)} '_)?>,
648                _: &AttrVec,
649                _: Span,
650                _: NodeId,
651            ) -> Self::Result {
652                walk_fn(self, fk)
653            }
654
655            // (non-mut) `Visitor`-only methods
656            $(
657                fn visit_stmt(&mut self, s: &$lt Stmt) -> Self::Result {
658                    walk_stmt(self, s)
659                }
660
661                fn visit_nested_use_tree(&mut self, use_tree: &$lt UseTree, id: NodeId) -> Self::Result {
662                    try_visit!(self.visit_id(id));
663                    self.visit_use_tree(use_tree)
664                }
665            )?
666
667            // `MutVisitor`-only methods
668            $(
669                // Span visiting is no longer used, but we keep it for now,
670                // in case it's needed for something like #127241.
671                #[inline]
672                fn visit_span(&mut self, _sp: &$mut Span) {
673                    impl_visitable!(|&mut self: Span, visitor: &mut V, _extra: ()| {
674                        visitor.visit_span(self)
675                    });
676                    // Do nothing.
677                }
678
679                fn flat_map_foreign_item(&mut self, ni: Box<ForeignItem>) -> SmallVec<[Box<ForeignItem>; 1]> {
680                    walk_flat_map_foreign_item(self, ni)
681                }
682
683                fn flat_map_item(&mut self, i: Box<Item>) -> SmallVec<[Box<Item>; 1]> {
684                    walk_flat_map_item(self, i)
685                }
686
687                fn flat_map_field_def(&mut self, fd: FieldDef) -> SmallVec<[FieldDef; 1]> {
688                    walk_flat_map_field_def(self, fd)
689                }
690
691                fn flat_map_assoc_item(
692                    &mut self,
693                    i: Box<AssocItem>,
694                    ctxt: AssocCtxt,
695                ) -> SmallVec<[Box<AssocItem>; 1]> {
696                    walk_flat_map_assoc_item(self, i, ctxt)
697                }
698
699                fn flat_map_stmt(&mut self, s: Stmt) -> SmallVec<[Stmt; 1]> {
700                    walk_flat_map_stmt(self, s)
701                }
702
703                fn flat_map_arm(&mut self, arm: Arm) -> SmallVec<[Arm; 1]> {
704                    walk_flat_map_arm(self, arm)
705                }
706
707                fn filter_map_expr(&mut self, e: Box<Expr>) -> Option<Box<Expr>> {
708                    walk_filter_map_expr(self, e)
709                }
710
711                fn flat_map_variant(&mut self, v: Variant) -> SmallVec<[Variant; 1]> {
712                    walk_flat_map_variant(self, v)
713                }
714
715                fn flat_map_param(&mut self, param: Param) -> SmallVec<[Param; 1]> {
716                    walk_flat_map_param(self, param)
717                }
718
719                fn flat_map_generic_param(&mut self, param: GenericParam) -> SmallVec<[GenericParam; 1]> {
720                    walk_flat_map_generic_param(self, param)
721                }
722
723                fn flat_map_expr_field(&mut self, f: ExprField) -> SmallVec<[ExprField; 1]> {
724                    walk_flat_map_expr_field(self, f)
725                }
726
727                fn flat_map_where_predicate(
728                    &mut self,
729                    where_predicate: WherePredicate,
730                ) -> SmallVec<[WherePredicate; 1]> {
731                    walk_flat_map_where_predicate(self, where_predicate)
732                }
733
734                fn flat_map_pat_field(&mut self, fp: PatField) -> SmallVec<[PatField; 1]> {
735                    walk_flat_map_pat_field(self, fp)
736                }
737            )?
738        }
739
740        pub trait WalkItemKind {
741            type Ctxt;
742            fn walk<$($lt,)? V: $Visitor$(<$lt>)?>(
743                &$($lt)? $($mut)? self,
744                attrs: &AttrVec,
745                span: Span,
746                id: NodeId,
747                visibility: &$($lt)? $($mut)? Visibility,
748                ctxt: Self::Ctxt,
749                vis: &mut V,
750            ) -> V::Result;
751        }
752
753        // this is only used by the MutVisitor. We include this symmetry here to make writing other functions easier
754        $(${ignore($lt)}
755            #[expect(unused, rustc::pass_by_value)]
756            #[inline]
757        )?
758        fn visit_span<$($lt,)? V: $Visitor$(<$lt>)?>(vis: &mut V, span: &$($lt)? $($mut)? Span) -> V::Result {
759            $(${ignore($mut)} vis.visit_span(span))?;
760            V::Result::output()
761        }
762
763        $(impl_visitable!(|&$lt self: ThinVec<(UseTree, NodeId)>, vis: &mut V, _extra: ()| {
764            for (nested_tree, nested_id) in self {
765                try_visit!(vis.visit_nested_use_tree(nested_tree, *nested_id));
766            }
767            V::Result::output()
768        });)?
769        $(impl_visitable_list!(<$mut> ThinVec<(UseTree, NodeId)>,);)?
770
771        fn walk_item_inner<$($lt,)? K: WalkItemKind, V: $Visitor$(<$lt>)?>(
772            visitor: &mut V,
773            item: &$($mut)? $($lt)? Item<K>,
774            ctxt: K::Ctxt,
775        ) -> V::Result {
776            let Item { attrs, id, kind, vis, span, tokens: _ } = item;
777            visit_visitable!($($mut)? visitor, id, attrs, vis);
778            try_visit!(kind.walk(attrs, *span, *id, vis, ctxt, visitor));
779            visit_visitable!($($mut)? visitor, span);
780            V::Result::output()
781        }
782
783        // Do not implement `Walkable`/`MutWalkable` for *Item to avoid confusion.
784        pub fn walk_item<$($lt,)? K: WalkItemKind<Ctxt = ()>, V: $Visitor$(<$lt>)?>(
785            visitor: &mut V,
786            item: &$($mut)? $($lt)? Item<K>,
787        ) -> V::Result {
788            walk_item_inner(visitor, item, ())
789        }
790
791        // Do not implement `Walkable`/`MutWalkable` for *Item to avoid confusion.
792        pub fn walk_assoc_item<$($lt,)? K: WalkItemKind<Ctxt = AssocCtxt>, V: $Visitor$(<$lt>)?>(
793            visitor: &mut V,
794            item: &$($mut)? $($lt)? Item<K>,
795            ctxt: AssocCtxt,
796        ) -> V::Result {
797            walk_item_inner(visitor, item, ctxt)
798        }
799
800        impl WalkItemKind for ItemKind {
801            type Ctxt = ();
802            fn walk<$($lt,)? V: $Visitor$(<$lt>)?>(
803                &$($lt)? $($mut)? self,
804                attrs: &AttrVec,
805                span: Span,
806                id: NodeId,
807                visibility: &$($lt)? $($mut)? Visibility,
808                _ctxt: Self::Ctxt,
809                vis: &mut V,
810            ) -> V::Result {
811                match self {
812                    ItemKind::Fn(func) => {
813                        let kind = FnKind::Fn(FnCtxt::Free, visibility, &$($mut)? *func);
814                        try_visit!(vis.visit_fn(kind, attrs, span, id));
815                    }
816                    ItemKind::ExternCrate(orig_name, ident) =>
817                        visit_visitable!($($mut)? vis, orig_name, ident),
818                    ItemKind::Use(use_tree) =>
819                        visit_visitable!($($mut)? vis, use_tree),
820                    ItemKind::Static(item) =>
821                        visit_visitable!($($mut)? vis, item),
822                    ItemKind::Const(item) =>
823                        visit_visitable!($($mut)? vis, item),
824                    ItemKind::Mod(safety, ident, mod_kind) =>
825                        visit_visitable!($($mut)? vis, safety, ident, mod_kind),
826                    ItemKind::ForeignMod(nm) =>
827                        visit_visitable!($($mut)? vis, nm),
828                    ItemKind::GlobalAsm(asm) =>
829                        visit_visitable!($($mut)? vis, asm),
830                    ItemKind::TyAlias(ty_alias) =>
831                        visit_visitable!($($mut)? vis, ty_alias),
832                    ItemKind::Enum(ident, generics, enum_definition) =>
833                        visit_visitable!($($mut)? vis, ident, generics, enum_definition),
834                    ItemKind::Struct(ident, generics, variant_data)
835                    | ItemKind::Union(ident, generics, variant_data) =>
836                        visit_visitable!($($mut)? vis, ident, generics, variant_data),
837                    ItemKind::Impl(impl_) =>
838                        visit_visitable!($($mut)? vis, impl_),
839                    ItemKind::Trait(trait_) =>
840                        visit_visitable!($($mut)? vis, trait_),
841                    ItemKind::TraitAlias(box TraitAlias { constness, ident, generics, bounds}) => {
842                        visit_visitable!($($mut)? vis, constness, ident, generics);
843                        visit_visitable_with!($($mut)? vis, bounds, BoundKind::Bound)
844                    }
845                    ItemKind::MacCall(m) =>
846                        visit_visitable!($($mut)? vis, m),
847                    ItemKind::MacroDef(ident, def) =>
848                        visit_visitable!($($mut)? vis, ident, def),
849                    ItemKind::Delegation(delegation) =>
850                        visit_visitable!($($mut)? vis, delegation),
851                    ItemKind::DelegationMac(dm) =>
852                        visit_visitable!($($mut)? vis, dm),
853                }
854                V::Result::output()
855            }
856        }
857
858        impl WalkItemKind for AssocItemKind {
859            type Ctxt = AssocCtxt;
860            fn walk<$($lt,)? V: $Visitor$(<$lt>)?>(
861                &$($lt)? $($mut)? self,
862                attrs: &AttrVec,
863                span: Span,
864                id: NodeId,
865                visibility: &$($lt)? $($mut)? Visibility,
866                ctxt: Self::Ctxt,
867                vis: &mut V,
868            ) -> V::Result {
869                match self {
870                    AssocItemKind::Const(item) =>
871                        visit_visitable!($($mut)? vis, item),
872                    AssocItemKind::Fn(func) => {
873                        let kind = FnKind::Fn(FnCtxt::Assoc(ctxt), visibility, &$($mut)? *func);
874                        try_visit!(vis.visit_fn(kind, attrs, span, id))
875                    }
876                    AssocItemKind::Type(alias) =>
877                        visit_visitable!($($mut)? vis, alias),
878                    AssocItemKind::MacCall(mac) =>
879                        visit_visitable!($($mut)? vis, mac),
880                    AssocItemKind::Delegation(delegation) =>
881                        visit_visitable!($($mut)? vis, delegation),
882                    AssocItemKind::DelegationMac(dm) =>
883                        visit_visitable!($($mut)? vis, dm),
884                }
885                V::Result::output()
886            }
887        }
888
889        impl WalkItemKind for ForeignItemKind {
890            type Ctxt = ();
891            fn walk<$($lt,)? V: $Visitor$(<$lt>)?>(
892                &$($lt)? $($mut)? self,
893                attrs: &AttrVec,
894                span: Span,
895                id: NodeId,
896                visibility: &$($lt)? $($mut)? Visibility,
897                _ctxt: Self::Ctxt,
898                vis: &mut V,
899            ) -> V::Result {
900                match self {
901                    ForeignItemKind::Static(item) =>
902                        visit_visitable!($($mut)? vis, item),
903                    ForeignItemKind::Fn(func) => {
904                        let kind = FnKind::Fn(FnCtxt::Foreign, visibility, &$($mut)?*func);
905                        try_visit!(vis.visit_fn(kind, attrs, span, id))
906                    }
907                    ForeignItemKind::TyAlias(alias) =>
908                        visit_visitable!($($mut)? vis, alias),
909                    ForeignItemKind::MacCall(mac) =>
910                        visit_visitable!($($mut)? vis, mac),
911                }
912                V::Result::output()
913            }
914        }
915
916        pub fn walk_fn<$($lt,)? V: $Visitor$(<$lt>)?>(vis: &mut V, kind: FnKind<$($lt)? $(${ignore($mut)} '_)?>) -> V::Result {
917            match kind {
918                FnKind::Fn(
919                    _ctxt,
920                    // Visibility is visited as a part of the item.
921                    _vis,
922                    Fn { defaultness, ident, sig, generics, contract, body, define_opaque },
923                ) => {
924                    let FnSig { header, decl, span } = sig;
925                    visit_visitable!($($mut)? vis,
926                        defaultness, ident, header, generics, decl,
927                        contract, body, span, define_opaque
928                    )
929                }
930                FnKind::Closure(binder, coroutine_kind, decl, body) =>
931                    visit_visitable!($($mut)? vis, binder, coroutine_kind, decl, body),
932            }
933            V::Result::output()
934        }
935
936        impl_walkable!(|&$($mut)? $($lt)? self: Impl, vis: &mut V| {
937            let Impl { generics, of_trait, self_ty, items, constness: _ } = self;
938            try_visit!(vis.visit_generics(generics));
939            if let Some(box of_trait) = of_trait {
940                let TraitImplHeader { defaultness, safety, polarity, trait_ref } = of_trait;
941                visit_visitable!($($mut)? vis, defaultness, safety, polarity, trait_ref);
942            }
943            try_visit!(vis.visit_ty(self_ty));
944            visit_visitable_with!($($mut)? vis, items, AssocCtxt::Impl { of_trait: of_trait.is_some() });
945            V::Result::output()
946        });
947
948        // Special case to call `visit_method_receiver_expr`.
949        impl_walkable!(|&$($mut)? $($lt)? self: MethodCall, vis: &mut V| {
950            let MethodCall { seg, receiver, args, span } = self;
951            try_visit!(vis.visit_method_receiver_expr(receiver));
952            visit_visitable!($($mut)? vis, seg, args, span);
953            V::Result::output()
954        });
955
956        impl_walkable!(|&$($mut)? $($lt)? self: Expr, vis: &mut V| {
957            let Expr { id, kind, span, attrs, tokens: _ } = self;
958            visit_visitable!($($mut)? vis, id, attrs);
959            match kind {
960                ExprKind::Array(exprs) =>
961                    visit_visitable!($($mut)? vis, exprs),
962                ExprKind::ConstBlock(anon_const) =>
963                    visit_visitable!($($mut)? vis, anon_const),
964                ExprKind::Repeat(element, count) =>
965                    visit_visitable!($($mut)? vis, element, count),
966                ExprKind::Struct(se) =>
967                    visit_visitable!($($mut)? vis, se),
968                ExprKind::Tup(exprs) =>
969                    visit_visitable!($($mut)? vis, exprs),
970                ExprKind::Call(callee_expression, arguments) =>
971                    visit_visitable!($($mut)? vis, callee_expression, arguments),
972                ExprKind::MethodCall(mc) =>
973                    visit_visitable!($($mut)? vis, mc),
974                ExprKind::Binary(op, lhs, rhs) =>
975                    visit_visitable!($($mut)? vis, op, lhs, rhs),
976                ExprKind::AddrOf(kind, mutbl, subexpression) =>
977                    visit_visitable!($($mut)? vis, kind, mutbl, subexpression),
978                ExprKind::Unary(op, subexpression) =>
979                    visit_visitable!($($mut)? vis, op, subexpression),
980                ExprKind::Cast(subexpression, typ) | ExprKind::Type(subexpression, typ) =>
981                    visit_visitable!($($mut)? vis, subexpression, typ),
982                ExprKind::Let(pat, expr, span, _recovered) =>
983                    visit_visitable!($($mut)? vis, pat, expr, span),
984                ExprKind::If(head_expression, if_block, optional_else) =>
985                    visit_visitable!($($mut)? vis, head_expression, if_block, optional_else),
986                ExprKind::While(subexpression, block, opt_label) =>
987                    visit_visitable!($($mut)? vis, subexpression, block, opt_label),
988                ExprKind::ForLoop { pat, iter, body, label, kind } =>
989                    visit_visitable!($($mut)? vis, pat, iter, body, label, kind),
990                ExprKind::Loop(block, opt_label, span) =>
991                    visit_visitable!($($mut)? vis, block, opt_label, span),
992                ExprKind::Match(subexpression, arms, kind) =>
993                    visit_visitable!($($mut)? vis, subexpression, arms, kind),
994                ExprKind::Closure(box Closure {
995                    binder,
996                    capture_clause,
997                    coroutine_kind,
998                    constness,
999                    movability,
1000                    fn_decl,
1001                    body,
1002                    fn_decl_span,
1003                    fn_arg_span,
1004                }) => {
1005                    visit_visitable!($($mut)? vis, constness, movability, capture_clause);
1006                    let kind = FnKind::Closure(binder, coroutine_kind, fn_decl, body);
1007                    try_visit!(vis.visit_fn(kind, attrs, *span, *id));
1008                    visit_visitable!($($mut)? vis, fn_decl_span, fn_arg_span);
1009                }
1010                ExprKind::Block(block, opt_label) =>
1011                    visit_visitable!($($mut)? vis, block, opt_label),
1012                ExprKind::Gen(capt, body, kind, decl_span) =>
1013                    visit_visitable!($($mut)? vis, capt, body, kind, decl_span),
1014                ExprKind::Await(expr, span) | ExprKind::Use(expr, span) =>
1015                    visit_visitable!($($mut)? vis, expr, span),
1016                ExprKind::Assign(lhs, rhs, span) =>
1017                    visit_visitable!($($mut)? vis, lhs, rhs, span),
1018                ExprKind::AssignOp(op, lhs, rhs) =>
1019                    visit_visitable!($($mut)? vis, op, lhs, rhs),
1020                ExprKind::Field(subexpression, ident) =>
1021                    visit_visitable!($($mut)? vis, subexpression, ident),
1022                ExprKind::Index(main_expression, index_expression, span) =>
1023                    visit_visitable!($($mut)? vis, main_expression, index_expression, span),
1024                ExprKind::Range(start, end, limit) =>
1025                    visit_visitable!($($mut)? vis, start, end, limit),
1026                ExprKind::Underscore => {}
1027                ExprKind::Path(maybe_qself, path) =>
1028                    visit_visitable!($($mut)? vis, maybe_qself, path),
1029                ExprKind::Break(opt_label, opt_expr) =>
1030                    visit_visitable!($($mut)? vis, opt_label, opt_expr),
1031                ExprKind::Continue(opt_label) =>
1032                    visit_visitable!($($mut)? vis, opt_label),
1033                ExprKind::Ret(optional_expression) | ExprKind::Yeet(optional_expression) =>
1034                    visit_visitable!($($mut)? vis, optional_expression),
1035                ExprKind::Become(expr) =>
1036                    visit_visitable!($($mut)? vis, expr),
1037                ExprKind::MacCall(mac) =>
1038                    visit_visitable!($($mut)? vis, mac),
1039                ExprKind::Paren(subexpression) =>
1040                    visit_visitable!($($mut)? vis, subexpression),
1041                ExprKind::InlineAsm(asm) =>
1042                    visit_visitable!($($mut)? vis, asm),
1043                ExprKind::FormatArgs(f) =>
1044                    visit_visitable!($($mut)? vis, f),
1045                ExprKind::OffsetOf(container, fields) =>
1046                    visit_visitable!($($mut)? vis, container, fields),
1047                ExprKind::Yield(kind) =>
1048                    visit_visitable!($($mut)? vis, kind),
1049                ExprKind::Try(subexpression) =>
1050                    visit_visitable!($($mut)? vis, subexpression),
1051                ExprKind::TryBlock(body) =>
1052                    visit_visitable!($($mut)? vis, body),
1053                ExprKind::Lit(token) =>
1054                    visit_visitable!($($mut)? vis, token),
1055                ExprKind::IncludedBytes(bytes) =>
1056                    visit_visitable!($($mut)? vis, bytes),
1057                ExprKind::UnsafeBinderCast(kind, expr, ty) =>
1058                    visit_visitable!($($mut)? vis, kind, expr, ty),
1059                ExprKind::Err(_guar) => {}
1060                ExprKind::Dummy => {}
1061            }
1062
1063            visit_span(vis, span)
1064        });
1065
1066        define_named_walk!($(($mut))? $Visitor$(<$lt>)?
1067            pub fn walk_anon_const(AnonConst);
1068            pub fn walk_arm(Arm);
1069            //pub fn walk_assoc_item(AssocItem, _ctxt: AssocCtxt);
1070            pub fn walk_assoc_item_constraint(AssocItemConstraint);
1071            pub fn walk_attribute(Attribute);
1072            pub fn walk_block(Block);
1073            //pub fn walk_nested_use_tree((UseTree, NodeId));
1074            pub fn walk_capture_by(CaptureBy);
1075            pub fn walk_closure_binder(ClosureBinder);
1076            pub fn walk_contract(FnContract);
1077            pub fn walk_coroutine_kind(CoroutineKind);
1078            pub fn walk_crate(Crate);
1079            pub fn walk_expr(Expr);
1080            pub fn walk_expr_field(ExprField);
1081            pub fn walk_field_def(FieldDef);
1082            pub fn walk_fn_decl(FnDecl);
1083            pub fn walk_fn_header(FnHeader);
1084            pub fn walk_fn_ret_ty(FnRetTy);
1085            //pub fn walk_foreign_item(ForeignItem);
1086            pub fn walk_foreign_mod(ForeignMod);
1087            pub fn walk_format_args(FormatArgs);
1088            pub fn walk_generic_arg(GenericArg);
1089            pub fn walk_generic_args(GenericArgs);
1090            pub fn walk_generic_param(GenericParam);
1091            pub fn walk_generics(Generics);
1092            pub fn walk_inline_asm(InlineAsm);
1093            pub fn walk_inline_asm_sym(InlineAsmSym);
1094            //pub fn walk_item(Item);
1095            pub fn walk_label(Label);
1096            pub fn walk_lifetime(Lifetime);
1097            pub fn walk_local(Local);
1098            pub fn walk_mac(MacCall);
1099            pub fn walk_macro_def(MacroDef);
1100            pub fn walk_param_bound(GenericBound);
1101            pub fn walk_param(Param);
1102            pub fn walk_pat_field(PatField);
1103            pub fn walk_path(Path);
1104            pub fn walk_path_segment(PathSegment);
1105            pub fn walk_pat(Pat);
1106            pub fn walk_poly_trait_ref(PolyTraitRef);
1107            pub fn walk_precise_capturing_arg(PreciseCapturingArg);
1108            pub fn walk_qself(QSelf);
1109            pub fn walk_trait_ref(TraitRef);
1110            pub fn walk_ty_pat(TyPat);
1111            pub fn walk_ty(Ty);
1112            pub fn walk_use_tree(UseTree);
1113            pub fn walk_variant_data(VariantData);
1114            pub fn walk_variant(Variant);
1115            pub fn walk_vis(Visibility);
1116            pub fn walk_where_predicate_kind(WherePredicateKind);
1117            pub fn walk_where_predicate(WherePredicate);
1118        );
1119    };
1120}
1121
1122common_visitor_and_walkers!(Visitor<'a>);
1123
1124macro_rules! generate_list_visit_fns {
1125    ($($name:ident, $Ty:ty, $visit_fn:ident$(, $param:ident: $ParamTy:ty)*;)+) => {
1126        $(
1127            #[allow(unused_parens)]
1128            impl<'a, V: Visitor<'a>> Visitable<'a, V> for ThinVec<$Ty> {
1129                type Extra = ($($ParamTy),*);
1130
1131                #[inline]
1132                fn visit(
1133                    &'a self,
1134                    visitor: &mut V,
1135                    ($($param),*): Self::Extra,
1136                ) -> V::Result {
1137                    $name(visitor, self $(, $param)*)
1138                }
1139            }
1140
1141            fn $name<'a, V: Visitor<'a>>(
1142                vis: &mut V,
1143                values: &'a ThinVec<$Ty>,
1144                $(
1145                    $param: $ParamTy,
1146                )*
1147            ) -> V::Result {
1148                walk_list!(vis, $visit_fn, values$(,$param)*);
1149                V::Result::output()
1150            }
1151        )+
1152    }
1153}
1154
1155generate_list_visit_fns! {
1156    visit_items, Box<Item>, visit_item;
1157    visit_foreign_items, Box<ForeignItem>, visit_foreign_item;
1158    visit_generic_params, GenericParam, visit_generic_param;
1159    visit_stmts, Stmt, visit_stmt;
1160    visit_exprs, Box<Expr>, visit_expr;
1161    visit_expr_fields, ExprField, visit_expr_field;
1162    visit_pat_fields, PatField, visit_pat_field;
1163    visit_variants, Variant, visit_variant;
1164    visit_assoc_items, Box<AssocItem>, visit_assoc_item, ctxt: AssocCtxt;
1165    visit_where_predicates, WherePredicate, visit_where_predicate;
1166    visit_params, Param, visit_param;
1167    visit_field_defs, FieldDef, visit_field_def;
1168    visit_arms, Arm, visit_arm;
1169}
1170
1171pub fn walk_stmt<'a, V: Visitor<'a>>(visitor: &mut V, statement: &'a Stmt) -> V::Result {
1172    let Stmt { id, kind, span: _ } = statement;
1173    try_visit!(visitor.visit_id(*id));
1174    match kind {
1175        StmtKind::Let(local) => try_visit!(visitor.visit_local(local)),
1176        StmtKind::Item(item) => try_visit!(visitor.visit_item(item)),
1177        StmtKind::Expr(expr) | StmtKind::Semi(expr) => try_visit!(visitor.visit_expr(expr)),
1178        StmtKind::Empty => {}
1179        StmtKind::MacCall(mac) => {
1180            let MacCallStmt { mac, attrs, style: _, tokens: _ } = &**mac;
1181            walk_list!(visitor, visit_attribute, attrs);
1182            try_visit!(visitor.visit_mac_call(mac));
1183        }
1184    }
1185    V::Result::output()
1186}
rustc_ast/visit.rs

rustc_ast/
visit.rs
