rustc_ast/
mut_visit.rs

1//! A `MutVisitor` represents an AST modification; it accepts an AST piece and
2//! mutates it in place. So, for instance, macro expansion is a `MutVisitor`
3//! that walks over an AST and modifies it.
4//!
5//! Note: using a `MutVisitor` (other than the `MacroExpander` `MutVisitor`) on
6//! an AST before macro expansion is probably a bad idea. For instance,
7//! a `MutVisitor` renaming item names in a module will miss all of those
8//! that are created by the expansion of a macro.
9
10use std::ops::DerefMut;
11use std::panic;
12
13use rustc_data_structures::flat_map_in_place::FlatMapInPlace;
14use rustc_data_structures::stack::ensure_sufficient_stack;
15use rustc_span::source_map::Spanned;
16use rustc_span::{Ident, Span};
17use smallvec::{Array, SmallVec, smallvec};
18use thin_vec::ThinVec;
19
20use crate::ast::*;
21use crate::ptr::P;
22use crate::tokenstream::*;
23use crate::visit::{AssocCtxt, BoundKind, FnCtxt, try_visit, visit_opt, walk_list};
24
25pub trait ExpectOne<A: Array> {
26    fn expect_one(self, err: &'static str) -> A::Item;
27}
28
29impl<A: Array> ExpectOne<A> for SmallVec<A> {
30    fn expect_one(self, err: &'static str) -> A::Item {
31        assert!(self.len() == 1, "{}", err);
32        self.into_iter().next().unwrap()
33    }
34}
35
36pub trait MutVisitor: Sized {
37    // Methods in this trait have one of three forms:
38    //
39    //   fn visit_t(&mut self, t: &mut T);                      // common
40    //   fn flat_map_t(&mut self, t: T) -> SmallVec<[T; 1]>;    // rare
41    //   fn filter_map_t(&mut self, t: T) -> Option<T>;         // rarest
42    //
43    // When writing these methods, it is better to use destructuring like this:
44    //
45    //   fn visit_abc(&mut self, ABC { a, b, c: _ }: &mut ABC) {
46    //       visit_a(a);
47    //       visit_b(b);
48    //   }
49    //
50    // than to use field access like this:
51    //
52    //   fn visit_abc(&mut self, abc: &mut ABC) {
53    //       visit_a(&mut abc.a);
54    //       visit_b(&mut abc.b);
55    //       // ignore abc.c
56    //   }
57    //
58    // As well as being more concise, the former is explicit about which fields
59    // are skipped. Furthermore, if a new field is added, the destructuring
60    // version will cause a compile error, which is good. In comparison, the
61    // field access version will continue working and it would be easy to
62    // forget to add handling for it.
63
64    fn visit_crate(&mut self, c: &mut Crate) {
65        walk_crate(self, c)
66    }
67
68    fn visit_meta_list_item(&mut self, list_item: &mut MetaItemInner) {
69        walk_meta_list_item(self, list_item);
70    }
71
72    fn visit_meta_item(&mut self, meta_item: &mut MetaItem) {
73        walk_meta_item(self, meta_item);
74    }
75
76    fn visit_use_tree(&mut self, use_tree: &mut UseTree) {
77        walk_use_tree(self, use_tree);
78    }
79
80    fn visit_foreign_item(&mut self, ni: &mut ForeignItem) {
81        walk_item(self, ni);
82    }
83
84    fn flat_map_foreign_item(&mut self, ni: P<ForeignItem>) -> SmallVec<[P<ForeignItem>; 1]> {
85        walk_flat_map_foreign_item(self, ni)
86    }
87
88    fn visit_item(&mut self, i: &mut Item) {
89        walk_item(self, i);
90    }
91
92    fn flat_map_item(&mut self, i: P<Item>) -> SmallVec<[P<Item>; 1]> {
93        walk_flat_map_item(self, i)
94    }
95
96    fn visit_fn_header(&mut self, header: &mut FnHeader) {
97        walk_fn_header(self, header);
98    }
99
100    fn visit_field_def(&mut self, fd: &mut FieldDef) {
101        walk_field_def(self, fd);
102    }
103
104    fn flat_map_field_def(&mut self, fd: FieldDef) -> SmallVec<[FieldDef; 1]> {
105        walk_flat_map_field_def(self, fd)
106    }
107
108    fn visit_assoc_item(&mut self, i: &mut AssocItem, ctxt: AssocCtxt) {
109        walk_assoc_item(self, i, ctxt)
110    }
111
112    fn flat_map_assoc_item(
113        &mut self,
114        i: P<AssocItem>,
115        ctxt: AssocCtxt,
116    ) -> SmallVec<[P<AssocItem>; 1]> {
117        walk_flat_map_assoc_item(self, i, ctxt)
118    }
119
120    fn visit_contract(&mut self, c: &mut FnContract) {
121        walk_contract(self, c);
122    }
123
124    fn visit_fn_decl(&mut self, d: &mut FnDecl) {
125        walk_fn_decl(self, d);
126    }
127
128    /// `Span` and `NodeId` are mutated at the caller site.
129    fn visit_fn(&mut self, fk: FnKind<'_>, _: Span, _: NodeId) {
130        walk_fn(self, fk)
131    }
132
133    fn visit_coroutine_kind(&mut self, a: &mut CoroutineKind) {
134        walk_coroutine_kind(self, a);
135    }
136
137    fn visit_closure_binder(&mut self, b: &mut ClosureBinder) {
138        walk_closure_binder(self, b);
139    }
140
141    fn visit_block(&mut self, b: &mut Block) {
142        walk_block(self, b);
143    }
144
145    fn flat_map_stmt(&mut self, s: Stmt) -> SmallVec<[Stmt; 1]> {
146        walk_flat_map_stmt(self, s)
147    }
148
149    fn visit_arm(&mut self, arm: &mut Arm) {
150        walk_arm(self, arm);
151    }
152
153    fn flat_map_arm(&mut self, arm: Arm) -> SmallVec<[Arm; 1]> {
154        walk_flat_map_arm(self, arm)
155    }
156
157    fn visit_pat(&mut self, p: &mut P<Pat>) {
158        walk_pat(self, p);
159    }
160
161    fn visit_anon_const(&mut self, c: &mut AnonConst) {
162        walk_anon_const(self, c);
163    }
164
165    fn visit_expr(&mut self, e: &mut P<Expr>) {
166        walk_expr(self, e);
167    }
168
169    /// This method is a hack to workaround unstable of `stmt_expr_attributes`.
170    /// It can be removed once that feature is stabilized.
171    fn visit_method_receiver_expr(&mut self, ex: &mut P<Expr>) {
172        self.visit_expr(ex)
173    }
174
175    fn filter_map_expr(&mut self, e: P<Expr>) -> Option<P<Expr>> {
176        walk_filter_map_expr(self, e)
177    }
178
179    fn visit_generic_arg(&mut self, arg: &mut GenericArg) {
180        walk_generic_arg(self, arg);
181    }
182
183    fn visit_ty(&mut self, t: &mut P<Ty>) {
184        walk_ty(self, t);
185    }
186
187    fn visit_ty_pat(&mut self, t: &mut TyPat) {
188        walk_ty_pat(self, t);
189    }
190
191    fn visit_lifetime(&mut self, l: &mut Lifetime) {
192        walk_lifetime(self, l);
193    }
194
195    fn visit_assoc_item_constraint(&mut self, c: &mut AssocItemConstraint) {
196        walk_assoc_item_constraint(self, c);
197    }
198
199    fn visit_foreign_mod(&mut self, nm: &mut ForeignMod) {
200        walk_foreign_mod(self, nm);
201    }
202
203    fn visit_variant(&mut self, v: &mut Variant) {
204        walk_variant(self, v);
205    }
206
207    fn flat_map_variant(&mut self, v: Variant) -> SmallVec<[Variant; 1]> {
208        walk_flat_map_variant(self, v)
209    }
210
211    fn visit_ident(&mut self, i: &mut Ident) {
212        walk_ident(self, i);
213    }
214
215    fn visit_modifiers(&mut self, m: &mut TraitBoundModifiers) {
216        walk_modifiers(self, m);
217    }
218
219    fn visit_path(&mut self, p: &mut Path) {
220        walk_path(self, p);
221    }
222
223    fn visit_path_segment(&mut self, p: &mut PathSegment) {
224        walk_path_segment(self, p)
225    }
226
227    fn visit_qself(&mut self, qs: &mut Option<P<QSelf>>) {
228        walk_qself(self, qs);
229    }
230
231    fn visit_generic_args(&mut self, p: &mut GenericArgs) {
232        walk_generic_args(self, p);
233    }
234
235    fn visit_angle_bracketed_parameter_data(&mut self, p: &mut AngleBracketedArgs) {
236        walk_angle_bracketed_parameter_data(self, p);
237    }
238
239    fn visit_parenthesized_parameter_data(&mut self, p: &mut ParenthesizedArgs) {
240        walk_parenthesized_parameter_data(self, p);
241    }
242
243    fn visit_local(&mut self, l: &mut Local) {
244        walk_local(self, l);
245    }
246
247    fn visit_mac_call(&mut self, mac: &mut MacCall) {
248        walk_mac(self, mac);
249    }
250
251    fn visit_macro_def(&mut self, def: &mut MacroDef) {
252        walk_macro_def(self, def);
253    }
254
255    fn visit_label(&mut self, label: &mut Label) {
256        walk_label(self, label);
257    }
258
259    fn visit_attribute(&mut self, at: &mut Attribute) {
260        walk_attribute(self, at);
261    }
262
263    fn visit_param(&mut self, param: &mut Param) {
264        walk_param(self, param);
265    }
266
267    fn flat_map_param(&mut self, param: Param) -> SmallVec<[Param; 1]> {
268        walk_flat_map_param(self, param)
269    }
270
271    fn visit_generics(&mut self, generics: &mut Generics) {
272        walk_generics(self, generics);
273    }
274
275    fn visit_trait_ref(&mut self, tr: &mut TraitRef) {
276        walk_trait_ref(self, tr);
277    }
278
279    fn visit_poly_trait_ref(&mut self, p: &mut PolyTraitRef) {
280        walk_poly_trait_ref(self, p);
281    }
282
283    fn visit_variant_data(&mut self, vdata: &mut VariantData) {
284        walk_variant_data(self, vdata);
285    }
286
287    fn visit_generic_param(&mut self, param: &mut GenericParam) {
288        walk_generic_param(self, param)
289    }
290
291    fn flat_map_generic_param(&mut self, param: GenericParam) -> SmallVec<[GenericParam; 1]> {
292        walk_flat_map_generic_param(self, param)
293    }
294
295    fn visit_param_bound(&mut self, tpb: &mut GenericBound, _ctxt: BoundKind) {
296        walk_param_bound(self, tpb);
297    }
298
299    fn visit_precise_capturing_arg(&mut self, arg: &mut PreciseCapturingArg) {
300        walk_precise_capturing_arg(self, arg);
301    }
302
303    fn visit_expr_field(&mut self, f: &mut ExprField) {
304        walk_expr_field(self, f);
305    }
306
307    fn flat_map_expr_field(&mut self, f: ExprField) -> SmallVec<[ExprField; 1]> {
308        walk_flat_map_expr_field(self, f)
309    }
310
311    fn visit_where_clause(&mut self, where_clause: &mut WhereClause) {
312        walk_where_clause(self, where_clause);
313    }
314
315    fn flat_map_where_predicate(
316        &mut self,
317        where_predicate: WherePredicate,
318    ) -> SmallVec<[WherePredicate; 1]> {
319        walk_flat_map_where_predicate(self, where_predicate)
320    }
321
322    fn visit_where_predicate_kind(&mut self, kind: &mut WherePredicateKind) {
323        walk_where_predicate_kind(self, kind)
324    }
325
326    fn visit_vis(&mut self, vis: &mut Visibility) {
327        walk_vis(self, vis);
328    }
329
330    fn visit_id(&mut self, _id: &mut NodeId) {
331        // Do nothing.
332    }
333
334    // Span visiting is no longer used, but we keep it for now,
335    // in case it's needed for something like #127241.
336    fn visit_span(&mut self, _sp: &mut Span) {
337        // Do nothing.
338    }
339
340    fn visit_pat_field(&mut self, fp: &mut PatField) {
341        walk_pat_field(self, fp)
342    }
343
344    fn flat_map_pat_field(&mut self, fp: PatField) -> SmallVec<[PatField; 1]> {
345        walk_flat_map_pat_field(self, fp)
346    }
347
348    fn visit_inline_asm(&mut self, asm: &mut InlineAsm) {
349        walk_inline_asm(self, asm)
350    }
351
352    fn visit_inline_asm_sym(&mut self, sym: &mut InlineAsmSym) {
353        walk_inline_asm_sym(self, sym)
354    }
355
356    fn visit_format_args(&mut self, fmt: &mut FormatArgs) {
357        walk_format_args(self, fmt)
358    }
359
360    fn visit_capture_by(&mut self, capture_by: &mut CaptureBy) {
361        walk_capture_by(self, capture_by)
362    }
363
364    fn visit_fn_ret_ty(&mut self, fn_ret_ty: &mut FnRetTy) {
365        walk_fn_ret_ty(self, fn_ret_ty)
366    }
367}
368
369super::common_visitor_and_walkers!((mut) MutVisitor);
370
371#[inline]
372fn visit_vec<T, F>(elems: &mut Vec<T>, mut visit_elem: F)
373where
374    F: FnMut(&mut T),
375{
376    for elem in elems {
377        visit_elem(elem);
378    }
379}
380
381#[inline]
382fn visit_thin_vec<T, F>(elems: &mut ThinVec<T>, mut visit_elem: F)
383where
384    F: FnMut(&mut T),
385{
386    for elem in elems {
387        visit_elem(elem);
388    }
389}
390
391#[inline]
392fn visit_opt<T, F>(opt: &mut Option<T>, mut visit_elem: F)
393where
394    F: FnMut(&mut T),
395{
396    if let Some(elem) = opt {
397        visit_elem(elem);
398    }
399}
400
401fn visit_attrs<T: MutVisitor>(vis: &mut T, attrs: &mut AttrVec) {
402    for attr in attrs.iter_mut() {
403        vis.visit_attribute(attr);
404    }
405}
406
407#[allow(unused)]
408fn visit_exprs<T: MutVisitor>(vis: &mut T, exprs: &mut Vec<P<Expr>>) {
409    exprs.flat_map_in_place(|expr| vis.filter_map_expr(expr))
410}
411
412fn visit_thin_exprs<T: MutVisitor>(vis: &mut T, exprs: &mut ThinVec<P<Expr>>) {
413    exprs.flat_map_in_place(|expr| vis.filter_map_expr(expr))
414}
415
416fn visit_attr_args<T: MutVisitor>(vis: &mut T, args: &mut AttrArgs) {
417    match args {
418        AttrArgs::Empty => {}
419        AttrArgs::Delimited(args) => visit_delim_args(vis, args),
420        AttrArgs::Eq { eq_span, expr } => {
421            vis.visit_expr(expr);
422            vis.visit_span(eq_span);
423        }
424    }
425}
426
427fn visit_delim_args<T: MutVisitor>(vis: &mut T, args: &mut DelimArgs) {
428    let DelimArgs { dspan, delim: _, tokens: _ } = args;
429    let DelimSpan { open, close } = dspan;
430    vis.visit_span(open);
431    vis.visit_span(close);
432}
433
434pub fn walk_pat_field<T: MutVisitor>(vis: &mut T, fp: &mut PatField) {
435    let PatField { attrs, id, ident, is_placeholder: _, is_shorthand: _, pat, span } = fp;
436    vis.visit_id(id);
437    visit_attrs(vis, attrs);
438    vis.visit_ident(ident);
439    vis.visit_pat(pat);
440    vis.visit_span(span);
441}
442
443pub fn walk_flat_map_pat_field<T: MutVisitor>(
444    vis: &mut T,
445    mut fp: PatField,
446) -> SmallVec<[PatField; 1]> {
447    vis.visit_pat_field(&mut fp);
448    smallvec![fp]
449}
450
451fn walk_use_tree<T: MutVisitor>(vis: &mut T, use_tree: &mut UseTree) {
452    let UseTree { prefix, kind, span } = use_tree;
453    vis.visit_path(prefix);
454    match kind {
455        UseTreeKind::Simple(rename) => visit_opt(rename, |rename| vis.visit_ident(rename)),
456        UseTreeKind::Nested { items, span } => {
457            for (tree, id) in items {
458                vis.visit_id(id);
459                vis.visit_use_tree(tree);
460            }
461            vis.visit_span(span);
462        }
463        UseTreeKind::Glob => {}
464    }
465    vis.visit_span(span);
466}
467
468pub fn walk_arm<T: MutVisitor>(vis: &mut T, arm: &mut Arm) {
469    let Arm { attrs, pat, guard, body, span, id, is_placeholder: _ } = arm;
470    vis.visit_id(id);
471    visit_attrs(vis, attrs);
472    vis.visit_pat(pat);
473    visit_opt(guard, |guard| vis.visit_expr(guard));
474    visit_opt(body, |body| vis.visit_expr(body));
475    vis.visit_span(span);
476}
477
478pub fn walk_flat_map_arm<T: MutVisitor>(vis: &mut T, mut arm: Arm) -> SmallVec<[Arm; 1]> {
479    vis.visit_arm(&mut arm);
480    smallvec![arm]
481}
482
483fn walk_assoc_item_constraint<T: MutVisitor>(
484    vis: &mut T,
485    AssocItemConstraint { id, ident, gen_args, kind, span }: &mut AssocItemConstraint,
486) {
487    vis.visit_id(id);
488    vis.visit_ident(ident);
489    if let Some(gen_args) = gen_args {
490        vis.visit_generic_args(gen_args);
491    }
492    match kind {
493        AssocItemConstraintKind::Equality { term } => match term {
494            Term::Ty(ty) => vis.visit_ty(ty),
495            Term::Const(c) => vis.visit_anon_const(c),
496        },
497        AssocItemConstraintKind::Bound { bounds } => visit_bounds(vis, bounds, BoundKind::Bound),
498    }
499    vis.visit_span(span);
500}
501
502pub fn walk_ty<T: MutVisitor>(vis: &mut T, ty: &mut Ty) {
503    let Ty { id, kind, span, tokens: _ } = ty;
504    vis.visit_id(id);
505    match kind {
506        TyKind::Err(_guar) => {}
507        TyKind::Infer | TyKind::ImplicitSelf | TyKind::Dummy | TyKind::Never | TyKind::CVarArgs => {
508        }
509        TyKind::Slice(ty) => vis.visit_ty(ty),
510        TyKind::Ptr(MutTy { ty, mutbl: _ }) => vis.visit_ty(ty),
511        TyKind::Ref(lt, MutTy { ty, mutbl: _ }) | TyKind::PinnedRef(lt, MutTy { ty, mutbl: _ }) => {
512            visit_opt(lt, |lt| vis.visit_lifetime(lt));
513            vis.visit_ty(ty);
514        }
515        TyKind::BareFn(bft) => {
516            let BareFnTy { safety, ext: _, generic_params, decl, decl_span } = bft.deref_mut();
517            visit_safety(vis, safety);
518            generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
519            vis.visit_fn_decl(decl);
520            vis.visit_span(decl_span);
521        }
522        TyKind::UnsafeBinder(binder) => {
523            let UnsafeBinderTy { generic_params, inner_ty } = binder.deref_mut();
524            generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
525            vis.visit_ty(inner_ty);
526        }
527        TyKind::Tup(tys) => visit_thin_vec(tys, |ty| vis.visit_ty(ty)),
528        TyKind::Paren(ty) => vis.visit_ty(ty),
529        TyKind::Pat(ty, pat) => {
530            vis.visit_ty(ty);
531            vis.visit_ty_pat(pat);
532        }
533        TyKind::Path(qself, path) => {
534            vis.visit_qself(qself);
535            vis.visit_path(path);
536        }
537        TyKind::Array(ty, length) => {
538            vis.visit_ty(ty);
539            vis.visit_anon_const(length);
540        }
541        TyKind::Typeof(expr) => vis.visit_anon_const(expr),
542        TyKind::TraitObject(bounds, _syntax) => {
543            visit_vec(bounds, |bound| vis.visit_param_bound(bound, BoundKind::TraitObject))
544        }
545        TyKind::ImplTrait(id, bounds) => {
546            vis.visit_id(id);
547            visit_vec(bounds, |bound| vis.visit_param_bound(bound, BoundKind::Impl));
548        }
549        TyKind::MacCall(mac) => vis.visit_mac_call(mac),
550    }
551    vis.visit_span(span);
552}
553
554pub fn walk_ty_pat<T: MutVisitor>(vis: &mut T, ty: &mut TyPat) {
555    let TyPat { id, kind, span, tokens: _ } = ty;
556    vis.visit_id(id);
557    match kind {
558        TyPatKind::Range(start, end, _include_end) => {
559            visit_opt(start, |c| vis.visit_anon_const(c));
560            visit_opt(end, |c| vis.visit_anon_const(c));
561        }
562        TyPatKind::Or(variants) => visit_thin_vec(variants, |p| vis.visit_ty_pat(p)),
563        TyPatKind::Err(_) => {}
564    }
565    vis.visit_span(span);
566}
567
568pub fn walk_variant<T: MutVisitor>(visitor: &mut T, variant: &mut Variant) {
569    let Variant { ident, vis, attrs, id, data, disr_expr, span, is_placeholder: _ } = variant;
570    visitor.visit_id(id);
571    visit_attrs(visitor, attrs);
572    visitor.visit_vis(vis);
573    visitor.visit_ident(ident);
574    visitor.visit_variant_data(data);
575    visit_opt(disr_expr, |disr_expr| visitor.visit_anon_const(disr_expr));
576    visitor.visit_span(span);
577}
578
579pub fn walk_flat_map_variant<T: MutVisitor>(
580    vis: &mut T,
581    mut variant: Variant,
582) -> SmallVec<[Variant; 1]> {
583    vis.visit_variant(&mut variant);
584    smallvec![variant]
585}
586
587fn walk_ident<T: MutVisitor>(vis: &mut T, Ident { name: _, span }: &mut Ident) {
588    vis.visit_span(span);
589}
590
591fn walk_path_segment<T: MutVisitor>(vis: &mut T, segment: &mut PathSegment) {
592    let PathSegment { ident, id, args } = segment;
593    vis.visit_id(id);
594    vis.visit_ident(ident);
595    visit_opt(args, |args| vis.visit_generic_args(args));
596}
597
598fn walk_path<T: MutVisitor>(vis: &mut T, Path { segments, span, tokens: _ }: &mut Path) {
599    for segment in segments {
600        vis.visit_path_segment(segment);
601    }
602    vis.visit_span(span);
603}
604
605fn walk_qself<T: MutVisitor>(vis: &mut T, qself: &mut Option<P<QSelf>>) {
606    visit_opt(qself, |qself| {
607        let QSelf { ty, path_span, position: _ } = &mut **qself;
608        vis.visit_ty(ty);
609        vis.visit_span(path_span);
610    })
611}
612
613fn walk_generic_args<T: MutVisitor>(vis: &mut T, generic_args: &mut GenericArgs) {
614    match generic_args {
615        GenericArgs::AngleBracketed(data) => vis.visit_angle_bracketed_parameter_data(data),
616        GenericArgs::Parenthesized(data) => vis.visit_parenthesized_parameter_data(data),
617        GenericArgs::ParenthesizedElided(span) => vis.visit_span(span),
618    }
619}
620
621fn walk_generic_arg<T: MutVisitor>(vis: &mut T, arg: &mut GenericArg) {
622    match arg {
623        GenericArg::Lifetime(lt) => vis.visit_lifetime(lt),
624        GenericArg::Type(ty) => vis.visit_ty(ty),
625        GenericArg::Const(ct) => vis.visit_anon_const(ct),
626    }
627}
628
629fn walk_angle_bracketed_parameter_data<T: MutVisitor>(vis: &mut T, data: &mut AngleBracketedArgs) {
630    let AngleBracketedArgs { args, span } = data;
631    visit_thin_vec(args, |arg| match arg {
632        AngleBracketedArg::Arg(arg) => vis.visit_generic_arg(arg),
633        AngleBracketedArg::Constraint(constraint) => vis.visit_assoc_item_constraint(constraint),
634    });
635    vis.visit_span(span);
636}
637
638fn walk_parenthesized_parameter_data<T: MutVisitor>(vis: &mut T, args: &mut ParenthesizedArgs) {
639    let ParenthesizedArgs { inputs, output, span, inputs_span } = args;
640    visit_thin_vec(inputs, |input| vis.visit_ty(input));
641    vis.visit_fn_ret_ty(output);
642    vis.visit_span(span);
643    vis.visit_span(inputs_span);
644}
645
646fn walk_local<T: MutVisitor>(vis: &mut T, local: &mut Local) {
647    let Local { id, super_, pat, ty, kind, span, colon_sp, attrs, tokens: _ } = local;
648    visit_opt(super_, |sp| vis.visit_span(sp));
649    vis.visit_id(id);
650    visit_attrs(vis, attrs);
651    vis.visit_pat(pat);
652    visit_opt(ty, |ty| vis.visit_ty(ty));
653    match kind {
654        LocalKind::Decl => {}
655        LocalKind::Init(init) => {
656            vis.visit_expr(init);
657        }
658        LocalKind::InitElse(init, els) => {
659            vis.visit_expr(init);
660            vis.visit_block(els);
661        }
662    }
663    visit_opt(colon_sp, |sp| vis.visit_span(sp));
664    vis.visit_span(span);
665}
666
667fn walk_attribute<T: MutVisitor>(vis: &mut T, attr: &mut Attribute) {
668    let Attribute { kind, id: _, style: _, span } = attr;
669    match kind {
670        AttrKind::Normal(normal) => {
671            let NormalAttr { item: AttrItem { unsafety: _, path, args, tokens: _ }, tokens: _ } =
672                &mut **normal;
673            vis.visit_path(path);
674            visit_attr_args(vis, args);
675        }
676        AttrKind::DocComment(_kind, _sym) => {}
677    }
678    vis.visit_span(span);
679}
680
681fn walk_mac<T: MutVisitor>(vis: &mut T, mac: &mut MacCall) {
682    let MacCall { path, args } = mac;
683    vis.visit_path(path);
684    visit_delim_args(vis, args);
685}
686
687fn walk_macro_def<T: MutVisitor>(vis: &mut T, macro_def: &mut MacroDef) {
688    let MacroDef { body, macro_rules: _ } = macro_def;
689    visit_delim_args(vis, body);
690}
691
692fn walk_meta_list_item<T: MutVisitor>(vis: &mut T, li: &mut MetaItemInner) {
693    match li {
694        MetaItemInner::MetaItem(mi) => vis.visit_meta_item(mi),
695        MetaItemInner::Lit(_lit) => {}
696    }
697}
698
699fn walk_meta_item<T: MutVisitor>(vis: &mut T, mi: &mut MetaItem) {
700    let MetaItem { unsafety: _, path: _, kind, span } = mi;
701    match kind {
702        MetaItemKind::Word => {}
703        MetaItemKind::List(mis) => visit_thin_vec(mis, |mi| vis.visit_meta_list_item(mi)),
704        MetaItemKind::NameValue(_s) => {}
705    }
706    vis.visit_span(span);
707}
708
709pub fn walk_param<T: MutVisitor>(vis: &mut T, param: &mut Param) {
710    let Param { attrs, id, pat, span, ty, is_placeholder: _ } = param;
711    vis.visit_id(id);
712    visit_attrs(vis, attrs);
713    vis.visit_pat(pat);
714    vis.visit_ty(ty);
715    vis.visit_span(span);
716}
717
718pub fn walk_flat_map_param<T: MutVisitor>(vis: &mut T, mut param: Param) -> SmallVec<[Param; 1]> {
719    vis.visit_param(&mut param);
720    smallvec![param]
721}
722
723fn walk_closure_binder<T: MutVisitor>(vis: &mut T, binder: &mut ClosureBinder) {
724    match binder {
725        ClosureBinder::NotPresent => {}
726        ClosureBinder::For { span: _, generic_params } => {
727            generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
728        }
729    }
730}
731
732fn walk_coroutine_kind<T: MutVisitor>(vis: &mut T, coroutine_kind: &mut CoroutineKind) {
733    match coroutine_kind {
734        CoroutineKind::Async { span, closure_id, return_impl_trait_id }
735        | CoroutineKind::Gen { span, closure_id, return_impl_trait_id }
736        | CoroutineKind::AsyncGen { span, closure_id, return_impl_trait_id } => {
737            vis.visit_id(closure_id);
738            vis.visit_id(return_impl_trait_id);
739            vis.visit_span(span);
740        }
741    }
742}
743
744fn walk_fn<T: MutVisitor>(vis: &mut T, kind: FnKind<'_>) {
745    match kind {
746        FnKind::Fn(
747            _ctxt,
748            _vis,
749            Fn {
750                defaultness,
751                ident,
752                generics,
753                contract,
754                body,
755                sig: FnSig { header, decl, span },
756                define_opaque,
757            },
758        ) => {
759            // Visibility is visited as a part of the item.
760            visit_defaultness(vis, defaultness);
761            vis.visit_ident(ident);
762            vis.visit_fn_header(header);
763            vis.visit_generics(generics);
764            vis.visit_fn_decl(decl);
765            if let Some(contract) = contract {
766                vis.visit_contract(contract);
767            }
768            if let Some(body) = body {
769                vis.visit_block(body);
770            }
771            vis.visit_span(span);
772
773            walk_define_opaques(vis, define_opaque);
774        }
775        FnKind::Closure(binder, coroutine_kind, decl, body) => {
776            vis.visit_closure_binder(binder);
777            coroutine_kind.as_mut().map(|coroutine_kind| vis.visit_coroutine_kind(coroutine_kind));
778            vis.visit_fn_decl(decl);
779            vis.visit_expr(body);
780        }
781    }
782}
783
784fn walk_contract<T: MutVisitor>(vis: &mut T, contract: &mut FnContract) {
785    let FnContract { requires, ensures } = contract;
786    if let Some(pred) = requires {
787        vis.visit_expr(pred);
788    }
789    if let Some(pred) = ensures {
790        vis.visit_expr(pred);
791    }
792}
793
794fn walk_fn_decl<T: MutVisitor>(vis: &mut T, decl: &mut FnDecl) {
795    let FnDecl { inputs, output } = decl;
796    inputs.flat_map_in_place(|param| vis.flat_map_param(param));
797    vis.visit_fn_ret_ty(output);
798}
799
800fn walk_fn_ret_ty<T: MutVisitor>(vis: &mut T, fn_ret_ty: &mut FnRetTy) {
801    match fn_ret_ty {
802        FnRetTy::Default(span) => vis.visit_span(span),
803        FnRetTy::Ty(ty) => vis.visit_ty(ty),
804    }
805}
806
807fn walk_param_bound<T: MutVisitor>(vis: &mut T, pb: &mut GenericBound) {
808    match pb {
809        GenericBound::Trait(trait_ref) => vis.visit_poly_trait_ref(trait_ref),
810        GenericBound::Outlives(lifetime) => walk_lifetime(vis, lifetime),
811        GenericBound::Use(args, span) => {
812            for arg in args {
813                vis.visit_precise_capturing_arg(arg);
814            }
815            vis.visit_span(span);
816        }
817    }
818}
819
820fn walk_precise_capturing_arg<T: MutVisitor>(vis: &mut T, arg: &mut PreciseCapturingArg) {
821    match arg {
822        PreciseCapturingArg::Lifetime(lt) => {
823            vis.visit_lifetime(lt);
824        }
825        PreciseCapturingArg::Arg(path, id) => {
826            vis.visit_id(id);
827            vis.visit_path(path);
828        }
829    }
830}
831
832pub fn walk_generic_param<T: MutVisitor>(vis: &mut T, param: &mut GenericParam) {
833    let GenericParam { id, ident, attrs, bounds, kind, colon_span, is_placeholder: _ } = param;
834    vis.visit_id(id);
835    visit_attrs(vis, attrs);
836    vis.visit_ident(ident);
837    visit_vec(bounds, |bound| vis.visit_param_bound(bound, BoundKind::Bound));
838    match kind {
839        GenericParamKind::Lifetime => {}
840        GenericParamKind::Type { default } => {
841            visit_opt(default, |default| vis.visit_ty(default));
842        }
843        GenericParamKind::Const { ty, kw_span: _, default } => {
844            vis.visit_ty(ty);
845            visit_opt(default, |default| vis.visit_anon_const(default));
846        }
847    }
848    if let Some(colon_span) = colon_span {
849        vis.visit_span(colon_span);
850    }
851}
852
853pub fn walk_flat_map_generic_param<T: MutVisitor>(
854    vis: &mut T,
855    mut param: GenericParam,
856) -> SmallVec<[GenericParam; 1]> {
857    vis.visit_generic_param(&mut param);
858    smallvec![param]
859}
860
861fn walk_generics<T: MutVisitor>(vis: &mut T, generics: &mut Generics) {
862    let Generics { params, where_clause, span } = generics;
863    params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
864    vis.visit_where_clause(where_clause);
865    vis.visit_span(span);
866}
867
868fn walk_ty_alias_where_clauses<T: MutVisitor>(vis: &mut T, tawcs: &mut TyAliasWhereClauses) {
869    let TyAliasWhereClauses { before, after, split: _ } = tawcs;
870    let TyAliasWhereClause { has_where_token: _, span: span_before } = before;
871    let TyAliasWhereClause { has_where_token: _, span: span_after } = after;
872    vis.visit_span(span_before);
873    vis.visit_span(span_after);
874}
875
876fn walk_where_clause<T: MutVisitor>(vis: &mut T, wc: &mut WhereClause) {
877    let WhereClause { has_where_token: _, predicates, span } = wc;
878    predicates.flat_map_in_place(|predicate| vis.flat_map_where_predicate(predicate));
879    vis.visit_span(span);
880}
881
882pub fn walk_flat_map_where_predicate<T: MutVisitor>(
883    vis: &mut T,
884    mut pred: WherePredicate,
885) -> SmallVec<[WherePredicate; 1]> {
886    let WherePredicate { attrs, kind, id, span, is_placeholder: _ } = &mut pred;
887    vis.visit_id(id);
888    visit_attrs(vis, attrs);
889    vis.visit_where_predicate_kind(kind);
890    vis.visit_span(span);
891    smallvec![pred]
892}
893
894pub fn walk_where_predicate_kind<T: MutVisitor>(vis: &mut T, kind: &mut WherePredicateKind) {
895    match kind {
896        WherePredicateKind::BoundPredicate(bp) => {
897            let WhereBoundPredicate { bound_generic_params, bounded_ty, bounds } = bp;
898            bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
899            vis.visit_ty(bounded_ty);
900            visit_vec(bounds, |bound| vis.visit_param_bound(bound, BoundKind::Bound));
901        }
902        WherePredicateKind::RegionPredicate(rp) => {
903            let WhereRegionPredicate { lifetime, bounds } = rp;
904            vis.visit_lifetime(lifetime);
905            visit_vec(bounds, |bound| vis.visit_param_bound(bound, BoundKind::Bound));
906        }
907        WherePredicateKind::EqPredicate(ep) => {
908            let WhereEqPredicate { lhs_ty, rhs_ty } = ep;
909            vis.visit_ty(lhs_ty);
910            vis.visit_ty(rhs_ty);
911        }
912    }
913}
914
915fn walk_variant_data<T: MutVisitor>(vis: &mut T, vdata: &mut VariantData) {
916    match vdata {
917        VariantData::Struct { fields, recovered: _ } => {
918            fields.flat_map_in_place(|field| vis.flat_map_field_def(field));
919        }
920        VariantData::Tuple(fields, id) => {
921            vis.visit_id(id);
922            fields.flat_map_in_place(|field| vis.flat_map_field_def(field));
923        }
924        VariantData::Unit(id) => vis.visit_id(id),
925    }
926}
927
928fn walk_trait_ref<T: MutVisitor>(vis: &mut T, TraitRef { path, ref_id }: &mut TraitRef) {
929    vis.visit_id(ref_id);
930    vis.visit_path(path);
931}
932
933fn walk_poly_trait_ref<T: MutVisitor>(vis: &mut T, p: &mut PolyTraitRef) {
934    let PolyTraitRef { bound_generic_params, modifiers, trait_ref, span } = p;
935    vis.visit_modifiers(modifiers);
936    bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
937    vis.visit_trait_ref(trait_ref);
938    vis.visit_span(span);
939}
940
941fn walk_modifiers<V: MutVisitor>(vis: &mut V, m: &mut TraitBoundModifiers) {
942    let TraitBoundModifiers { constness, asyncness, polarity } = m;
943    match constness {
944        BoundConstness::Never => {}
945        BoundConstness::Always(span) | BoundConstness::Maybe(span) => vis.visit_span(span),
946    }
947    match asyncness {
948        BoundAsyncness::Normal => {}
949        BoundAsyncness::Async(span) => vis.visit_span(span),
950    }
951    match polarity {
952        BoundPolarity::Positive => {}
953        BoundPolarity::Negative(span) | BoundPolarity::Maybe(span) => vis.visit_span(span),
954    }
955}
956
957pub fn walk_field_def<T: MutVisitor>(visitor: &mut T, fd: &mut FieldDef) {
958    let FieldDef { span, ident, vis, id, ty, attrs, is_placeholder: _, safety, default } = fd;
959    visitor.visit_id(id);
960    visit_attrs(visitor, attrs);
961    visitor.visit_vis(vis);
962    visit_safety(visitor, safety);
963    visit_opt(ident, |ident| visitor.visit_ident(ident));
964    visitor.visit_ty(ty);
965    visit_opt(default, |default| visitor.visit_anon_const(default));
966    visitor.visit_span(span);
967}
968
969pub fn walk_flat_map_field_def<T: MutVisitor>(
970    vis: &mut T,
971    mut fd: FieldDef,
972) -> SmallVec<[FieldDef; 1]> {
973    vis.visit_field_def(&mut fd);
974    smallvec![fd]
975}
976
977pub fn walk_expr_field<T: MutVisitor>(vis: &mut T, f: &mut ExprField) {
978    let ExprField { ident, expr, span, is_shorthand: _, attrs, id, is_placeholder: _ } = f;
979    vis.visit_id(id);
980    visit_attrs(vis, attrs);
981    vis.visit_ident(ident);
982    vis.visit_expr(expr);
983    vis.visit_span(span);
984}
985
986pub fn walk_flat_map_expr_field<T: MutVisitor>(
987    vis: &mut T,
988    mut f: ExprField,
989) -> SmallVec<[ExprField; 1]> {
990    vis.visit_expr_field(&mut f);
991    smallvec![f]
992}
993
994pub fn walk_block<T: MutVisitor>(vis: &mut T, block: &mut Block) {
995    let Block { id, stmts, rules: _, span, tokens: _ } = block;
996    vis.visit_id(id);
997    stmts.flat_map_in_place(|stmt| vis.flat_map_stmt(stmt));
998    vis.visit_span(span);
999}
1000
1001pub fn walk_item_kind<K: WalkItemKind>(
1002    kind: &mut K,
1003    span: Span,
1004    id: NodeId,
1005    visibility: &mut Visibility,
1006    ctxt: K::Ctxt,
1007    vis: &mut impl MutVisitor,
1008) {
1009    kind.walk(span, id, visibility, ctxt, vis)
1010}
1011
1012pub fn walk_crate<T: MutVisitor>(vis: &mut T, krate: &mut Crate) {
1013    let Crate { attrs, items, spans, id, is_placeholder: _ } = krate;
1014    vis.visit_id(id);
1015    visit_attrs(vis, attrs);
1016    items.flat_map_in_place(|item| vis.flat_map_item(item));
1017    let ModSpans { inner_span, inject_use_span } = spans;
1018    vis.visit_span(inner_span);
1019    vis.visit_span(inject_use_span);
1020}
1021
1022pub fn walk_flat_map_item(vis: &mut impl MutVisitor, mut item: P<Item>) -> SmallVec<[P<Item>; 1]> {
1023    vis.visit_item(&mut item);
1024    smallvec![item]
1025}
1026
1027pub fn walk_flat_map_foreign_item(
1028    vis: &mut impl MutVisitor,
1029    mut item: P<ForeignItem>,
1030) -> SmallVec<[P<ForeignItem>; 1]> {
1031    vis.visit_foreign_item(&mut item);
1032    smallvec![item]
1033}
1034
1035pub fn walk_flat_map_assoc_item(
1036    vis: &mut impl MutVisitor,
1037    mut item: P<AssocItem>,
1038    ctxt: AssocCtxt,
1039) -> SmallVec<[P<AssocItem>; 1]> {
1040    vis.visit_assoc_item(&mut item, ctxt);
1041    smallvec![item]
1042}
1043
1044pub fn walk_pat<T: MutVisitor>(vis: &mut T, pat: &mut Pat) {
1045    let Pat { id, kind, span, tokens: _ } = pat;
1046    vis.visit_id(id);
1047    match kind {
1048        PatKind::Err(_guar) => {}
1049        PatKind::Missing | PatKind::Wild | PatKind::Rest | PatKind::Never => {}
1050        PatKind::Ident(_binding_mode, ident, sub) => {
1051            vis.visit_ident(ident);
1052            visit_opt(sub, |sub| vis.visit_pat(sub));
1053        }
1054        PatKind::Expr(e) => vis.visit_expr(e),
1055        PatKind::TupleStruct(qself, path, elems) => {
1056            vis.visit_qself(qself);
1057            vis.visit_path(path);
1058            visit_thin_vec(elems, |elem| vis.visit_pat(elem));
1059        }
1060        PatKind::Path(qself, path) => {
1061            vis.visit_qself(qself);
1062            vis.visit_path(path);
1063        }
1064        PatKind::Struct(qself, path, fields, _etc) => {
1065            vis.visit_qself(qself);
1066            vis.visit_path(path);
1067            fields.flat_map_in_place(|field| vis.flat_map_pat_field(field));
1068        }
1069        PatKind::Box(inner) => vis.visit_pat(inner),
1070        PatKind::Deref(inner) => vis.visit_pat(inner),
1071        PatKind::Ref(inner, _mutbl) => vis.visit_pat(inner),
1072        PatKind::Range(e1, e2, Spanned { span: _, node: _ }) => {
1073            visit_opt(e1, |e| vis.visit_expr(e));
1074            visit_opt(e2, |e| vis.visit_expr(e));
1075            vis.visit_span(span);
1076        }
1077        PatKind::Guard(p, e) => {
1078            vis.visit_pat(p);
1079            vis.visit_expr(e);
1080        }
1081        PatKind::Tuple(elems) | PatKind::Slice(elems) | PatKind::Or(elems) => {
1082            visit_thin_vec(elems, |elem| vis.visit_pat(elem))
1083        }
1084        PatKind::Paren(inner) => vis.visit_pat(inner),
1085        PatKind::MacCall(mac) => vis.visit_mac_call(mac),
1086    }
1087    vis.visit_span(span);
1088}
1089
1090fn walk_anon_const<T: MutVisitor>(vis: &mut T, AnonConst { id, value }: &mut AnonConst) {
1091    vis.visit_id(id);
1092    vis.visit_expr(value);
1093}
1094
1095fn walk_inline_asm<T: MutVisitor>(vis: &mut T, asm: &mut InlineAsm) {
1096    // FIXME: Visit spans inside all this currently ignored stuff.
1097    let InlineAsm {
1098        asm_macro: _,
1099        template: _,
1100        template_strs: _,
1101        operands,
1102        clobber_abis: _,
1103        options: _,
1104        line_spans: _,
1105    } = asm;
1106    for (op, span) in operands {
1107        match op {
1108            InlineAsmOperand::In { expr, reg: _ }
1109            | InlineAsmOperand::Out { expr: Some(expr), reg: _, late: _ }
1110            | InlineAsmOperand::InOut { expr, reg: _, late: _ } => vis.visit_expr(expr),
1111            InlineAsmOperand::Out { expr: None, reg: _, late: _ } => {}
1112            InlineAsmOperand::SplitInOut { in_expr, out_expr, reg: _, late: _ } => {
1113                vis.visit_expr(in_expr);
1114                if let Some(out_expr) = out_expr {
1115                    vis.visit_expr(out_expr);
1116                }
1117            }
1118            InlineAsmOperand::Const { anon_const } => vis.visit_anon_const(anon_const),
1119            InlineAsmOperand::Sym { sym } => vis.visit_inline_asm_sym(sym),
1120            InlineAsmOperand::Label { block } => vis.visit_block(block),
1121        }
1122        vis.visit_span(span);
1123    }
1124}
1125
1126fn walk_inline_asm_sym<T: MutVisitor>(
1127    vis: &mut T,
1128    InlineAsmSym { id, qself, path }: &mut InlineAsmSym,
1129) {
1130    vis.visit_id(id);
1131    vis.visit_qself(qself);
1132    vis.visit_path(path);
1133}
1134
1135fn walk_format_args<T: MutVisitor>(vis: &mut T, fmt: &mut FormatArgs) {
1136    // FIXME: visit the template exhaustively.
1137    let FormatArgs { span, template: _, arguments, uncooked_fmt_str: _ } = fmt;
1138    for FormatArgument { kind, expr } in arguments.all_args_mut() {
1139        match kind {
1140            FormatArgumentKind::Named(ident) | FormatArgumentKind::Captured(ident) => {
1141                vis.visit_ident(ident)
1142            }
1143            FormatArgumentKind::Normal => {}
1144        }
1145        vis.visit_expr(expr);
1146    }
1147    vis.visit_span(span);
1148}
1149
1150pub fn walk_expr<T: MutVisitor>(vis: &mut T, Expr { kind, id, span, attrs, tokens: _ }: &mut Expr) {
1151    vis.visit_id(id);
1152    visit_attrs(vis, attrs);
1153    match kind {
1154        ExprKind::Array(exprs) => visit_thin_exprs(vis, exprs),
1155        ExprKind::ConstBlock(anon_const) => {
1156            vis.visit_anon_const(anon_const);
1157        }
1158        ExprKind::Repeat(expr, count) => {
1159            vis.visit_expr(expr);
1160            vis.visit_anon_const(count);
1161        }
1162        ExprKind::Tup(exprs) => visit_thin_exprs(vis, exprs),
1163        ExprKind::Call(f, args) => {
1164            vis.visit_expr(f);
1165            visit_thin_exprs(vis, args);
1166        }
1167        ExprKind::MethodCall(box MethodCall {
1168            seg: PathSegment { ident, id, args: seg_args },
1169            receiver,
1170            args: call_args,
1171            span,
1172        }) => {
1173            vis.visit_method_receiver_expr(receiver);
1174            vis.visit_id(id);
1175            vis.visit_ident(ident);
1176            visit_opt(seg_args, |args| vis.visit_generic_args(args));
1177            visit_thin_exprs(vis, call_args);
1178            vis.visit_span(span);
1179        }
1180        ExprKind::Binary(binop, lhs, rhs) => {
1181            vis.visit_expr(lhs);
1182            vis.visit_expr(rhs);
1183            vis.visit_span(&mut binop.span);
1184        }
1185        ExprKind::Unary(_unop, ohs) => vis.visit_expr(ohs),
1186        ExprKind::Cast(expr, ty) => {
1187            vis.visit_expr(expr);
1188            vis.visit_ty(ty);
1189        }
1190        ExprKind::Type(expr, ty) => {
1191            vis.visit_expr(expr);
1192            vis.visit_ty(ty);
1193        }
1194        ExprKind::AddrOf(_kind, _mut, ohs) => vis.visit_expr(ohs),
1195        ExprKind::Let(pat, scrutinee, span, _recovered) => {
1196            vis.visit_pat(pat);
1197            vis.visit_expr(scrutinee);
1198            vis.visit_span(span);
1199        }
1200        ExprKind::If(cond, tr, fl) => {
1201            vis.visit_expr(cond);
1202            vis.visit_block(tr);
1203            visit_opt(fl, |fl| ensure_sufficient_stack(|| vis.visit_expr(fl)));
1204        }
1205        ExprKind::While(cond, body, label) => {
1206            visit_opt(label, |label| vis.visit_label(label));
1207            vis.visit_expr(cond);
1208            vis.visit_block(body);
1209        }
1210        ExprKind::ForLoop { pat, iter, body, label, kind: _ } => {
1211            visit_opt(label, |label| vis.visit_label(label));
1212            vis.visit_pat(pat);
1213            vis.visit_expr(iter);
1214            vis.visit_block(body);
1215        }
1216        ExprKind::Loop(body, label, span) => {
1217            visit_opt(label, |label| vis.visit_label(label));
1218            vis.visit_block(body);
1219            vis.visit_span(span);
1220        }
1221        ExprKind::Match(expr, arms, _kind) => {
1222            vis.visit_expr(expr);
1223            arms.flat_map_in_place(|arm| vis.flat_map_arm(arm));
1224        }
1225        ExprKind::Closure(box Closure {
1226            binder,
1227            capture_clause,
1228            constness,
1229            coroutine_kind,
1230            movability: _,
1231            fn_decl,
1232            body,
1233            fn_decl_span,
1234            fn_arg_span,
1235        }) => {
1236            visit_constness(vis, constness);
1237            vis.visit_capture_by(capture_clause);
1238            vis.visit_fn(FnKind::Closure(binder, coroutine_kind, fn_decl, body), *span, *id);
1239            vis.visit_span(fn_decl_span);
1240            vis.visit_span(fn_arg_span);
1241        }
1242        ExprKind::Block(blk, label) => {
1243            visit_opt(label, |label| vis.visit_label(label));
1244            vis.visit_block(blk);
1245        }
1246        ExprKind::Gen(_capture_by, body, _kind, decl_span) => {
1247            vis.visit_block(body);
1248            vis.visit_span(decl_span);
1249        }
1250        ExprKind::Await(expr, await_kw_span) => {
1251            vis.visit_expr(expr);
1252            vis.visit_span(await_kw_span);
1253        }
1254        ExprKind::Use(expr, use_kw_span) => {
1255            vis.visit_expr(expr);
1256            vis.visit_span(use_kw_span);
1257        }
1258        ExprKind::Assign(el, er, span) => {
1259            vis.visit_expr(el);
1260            vis.visit_expr(er);
1261            vis.visit_span(span);
1262        }
1263        ExprKind::AssignOp(_op, el, er) => {
1264            vis.visit_expr(el);
1265            vis.visit_expr(er);
1266        }
1267        ExprKind::Field(el, ident) => {
1268            vis.visit_expr(el);
1269            vis.visit_ident(ident);
1270        }
1271        ExprKind::Index(el, er, brackets_span) => {
1272            vis.visit_expr(el);
1273            vis.visit_expr(er);
1274            vis.visit_span(brackets_span);
1275        }
1276        ExprKind::Range(e1, e2, _lim) => {
1277            visit_opt(e1, |e1| vis.visit_expr(e1));
1278            visit_opt(e2, |e2| vis.visit_expr(e2));
1279        }
1280        ExprKind::Underscore => {}
1281        ExprKind::Path(qself, path) => {
1282            vis.visit_qself(qself);
1283            vis.visit_path(path);
1284        }
1285        ExprKind::Break(label, expr) => {
1286            visit_opt(label, |label| vis.visit_label(label));
1287            visit_opt(expr, |expr| vis.visit_expr(expr));
1288        }
1289        ExprKind::Continue(label) => {
1290            visit_opt(label, |label| vis.visit_label(label));
1291        }
1292        ExprKind::Ret(expr) => {
1293            visit_opt(expr, |expr| vis.visit_expr(expr));
1294        }
1295        ExprKind::Yeet(expr) => {
1296            visit_opt(expr, |expr| vis.visit_expr(expr));
1297        }
1298        ExprKind::Become(expr) => vis.visit_expr(expr),
1299        ExprKind::InlineAsm(asm) => vis.visit_inline_asm(asm),
1300        ExprKind::FormatArgs(fmt) => vis.visit_format_args(fmt),
1301        ExprKind::OffsetOf(container, fields) => {
1302            vis.visit_ty(container);
1303            for field in fields.iter_mut() {
1304                vis.visit_ident(field);
1305            }
1306        }
1307        ExprKind::MacCall(mac) => vis.visit_mac_call(mac),
1308        ExprKind::Struct(se) => {
1309            let StructExpr { qself, path, fields, rest } = se.deref_mut();
1310            vis.visit_qself(qself);
1311            vis.visit_path(path);
1312            fields.flat_map_in_place(|field| vis.flat_map_expr_field(field));
1313            match rest {
1314                StructRest::Base(expr) => vis.visit_expr(expr),
1315                StructRest::Rest(_span) => {}
1316                StructRest::None => {}
1317            }
1318        }
1319        ExprKind::Paren(expr) => {
1320            vis.visit_expr(expr);
1321        }
1322        ExprKind::Yield(kind) => {
1323            let expr = kind.expr_mut();
1324            if let Some(expr) = expr {
1325                vis.visit_expr(expr);
1326            }
1327        }
1328        ExprKind::Try(expr) => vis.visit_expr(expr),
1329        ExprKind::TryBlock(body) => vis.visit_block(body),
1330        ExprKind::Lit(_token) => {}
1331        ExprKind::IncludedBytes(_bytes) => {}
1332        ExprKind::UnsafeBinderCast(_kind, expr, ty) => {
1333            vis.visit_expr(expr);
1334            if let Some(ty) = ty {
1335                vis.visit_ty(ty);
1336            }
1337        }
1338        ExprKind::Err(_guar) => {}
1339        ExprKind::Dummy => {}
1340    }
1341    vis.visit_span(span);
1342}
1343
1344pub fn walk_filter_map_expr<T: MutVisitor>(vis: &mut T, mut e: P<Expr>) -> Option<P<Expr>> {
1345    vis.visit_expr(&mut e);
1346    Some(e)
1347}
1348
1349pub fn walk_flat_map_stmt<T: MutVisitor>(
1350    vis: &mut T,
1351    Stmt { kind, span, mut id }: Stmt,
1352) -> SmallVec<[Stmt; 1]> {
1353    vis.visit_id(&mut id);
1354    let mut stmts: SmallVec<[Stmt; 1]> = walk_flat_map_stmt_kind(vis, kind)
1355        .into_iter()
1356        .map(|kind| Stmt { id, kind, span })
1357        .collect();
1358    match &mut stmts[..] {
1359        [] => {}
1360        [stmt] => vis.visit_span(&mut stmt.span),
1361        _ => panic!(
1362            "cloning statement `NodeId`s is prohibited by default, \
1363             the visitor should implement custom statement visiting"
1364        ),
1365    }
1366    stmts
1367}
1368
1369fn walk_flat_map_stmt_kind<T: MutVisitor>(vis: &mut T, kind: StmtKind) -> SmallVec<[StmtKind; 1]> {
1370    match kind {
1371        StmtKind::Let(mut local) => smallvec![StmtKind::Let({
1372            vis.visit_local(&mut local);
1373            local
1374        })],
1375        StmtKind::Item(item) => vis.flat_map_item(item).into_iter().map(StmtKind::Item).collect(),
1376        StmtKind::Expr(expr) => vis.filter_map_expr(expr).into_iter().map(StmtKind::Expr).collect(),
1377        StmtKind::Semi(expr) => vis.filter_map_expr(expr).into_iter().map(StmtKind::Semi).collect(),
1378        StmtKind::Empty => smallvec![StmtKind::Empty],
1379        StmtKind::MacCall(mut mac) => {
1380            let MacCallStmt { mac: mac_, style: _, attrs, tokens: _ } = mac.deref_mut();
1381            visit_attrs(vis, attrs);
1382            vis.visit_mac_call(mac_);
1383            smallvec![StmtKind::MacCall(mac)]
1384        }
1385    }
1386}
1387
1388fn walk_vis<T: MutVisitor>(vis: &mut T, visibility: &mut Visibility) {
1389    let Visibility { kind, span, tokens: _ } = visibility;
1390    match kind {
1391        VisibilityKind::Public | VisibilityKind::Inherited => {}
1392        VisibilityKind::Restricted { path, id, shorthand: _ } => {
1393            vis.visit_id(id);
1394            vis.visit_path(path);
1395        }
1396    }
1397    vis.visit_span(span);
1398}
1399
1400fn walk_capture_by<T: MutVisitor>(vis: &mut T, capture_by: &mut CaptureBy) {
1401    match capture_by {
1402        CaptureBy::Ref => {}
1403        CaptureBy::Value { move_kw } => {
1404            vis.visit_span(move_kw);
1405        }
1406        CaptureBy::Use { use_kw } => {
1407            vis.visit_span(use_kw);
1408        }
1409    }
1410}
1411
1412#[derive(Debug)]
1413pub enum FnKind<'a> {
1414    /// E.g., `fn foo()`, `fn foo(&self)`, or `extern "Abi" fn foo()`.
1415    Fn(FnCtxt, &'a mut Visibility, &'a mut Fn),
1416
1417    /// E.g., `|x, y| body`.
1418    Closure(
1419        &'a mut ClosureBinder,
1420        &'a mut Option<CoroutineKind>,
1421        &'a mut P<FnDecl>,
1422        &'a mut P<Expr>,
1423    ),
1424}