compiler/rustc_ast/src/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
  16 use crate::{ast::*, StaticItem};
  17
  18 use rustc_span::symbol::Ident;
  19 use rustc_span::Span;
  20
  21 #[derive(Copy, Clone, Debug, PartialEq)]
  22 pub enum AssocCtxt {
  23     Trait,
  24     Impl,
  25 }
  26
  27 #[derive(Copy, Clone, Debug, PartialEq)]
  28 pub enum FnCtxt {
  29     Free,
  30     Foreign,
  31     Assoc(AssocCtxt),
  32 }
  33
  34 #[derive(Copy, Clone, Debug)]
  35 pub enum BoundKind {
  36     /// Trait bounds in generics bounds and type/trait alias.
  37     /// E.g., `<T: Bound>`, `type A: Bound`, or `where T: Bound`.
  38     Bound,
  39
  40     /// Trait bounds in `impl` type.
  41     /// E.g., `type Foo = impl Bound1 + Bound2 + Bound3`.
  42     Impl,
  43
  44     /// Trait bounds in trait object type.
  45     /// E.g., `dyn Bound1 + Bound2 + Bound3`.
  46     TraitObject,
  47
  48     /// Super traits of a trait.
  49     /// E.g., `trait A: B`
  50     SuperTraits,
  51 }
  52
  53 #[derive(Copy, Clone, Debug)]
  54 pub enum FnKind<'a> {
  55     /// E.g., `fn foo()`, `fn foo(&self)`, or `extern "Abi" fn foo()`.
  56     Fn(FnCtxt, Ident, &'a FnSig, &'a Visibility, &'a Generics, Option<&'a Block>),
  57
  58     /// E.g., `|x, y| body`.
  59     Closure(&'a ClosureBinder, &'a FnDecl, &'a Expr),
  60 }
  61
  62 impl<'a> FnKind<'a> {
  63     pub fn header(&self) -> Option<&'a FnHeader> {
  64         match *self {
  65             FnKind::Fn(_, _, sig, _, _, _) => Some(&sig.header),
  66             FnKind::Closure(_, _, _) => None,
  67         }
  68     }
  69
  70     pub fn ident(&self) -> Option<&Ident> {
  71         match self {
  72             FnKind::Fn(_, ident, ..) => Some(ident),
  73             _ => None,
  74         }
  75     }
  76
  77     pub fn decl(&self) -> &'a FnDecl {
  78         match self {
  79             FnKind::Fn(_, _, sig, _, _, _) => &sig.decl,
  80             FnKind::Closure(_, decl, _) => decl,
  81         }
  82     }
  83
  84     pub fn ctxt(&self) -> Option<FnCtxt> {
  85         match self {
  86             FnKind::Fn(ctxt, ..) => Some(*ctxt),
  87             FnKind::Closure(..) => None,
  88         }
  89     }
  90 }
  91
  92 #[derive(Copy, Clone, Debug)]
  93 pub enum LifetimeCtxt {
  94     /// Appears in a reference type.
  95     Ref,
  96     /// Appears as a bound on a type or another lifetime.
  97     Bound,
  98     /// Appears as a generic argument.
  99     GenericArg,
 100 }
 101
 102 /// Each method of the `Visitor` trait is a hook to be potentially
 103 /// overridden. Each method's default implementation recursively visits
 104 /// the substructure of the input via the corresponding `walk` method;
 105 /// e.g., the `visit_item` method by default calls `visit::walk_item`.
 106 ///
 107 /// If you want to ensure that your code handles every variant
 108 /// explicitly, you need to override each method. (And you also need
 109 /// to monitor future changes to `Visitor` in case a new method with a
 110 /// new default implementation gets introduced.)
 111 pub trait Visitor<'ast>: Sized {
 112     fn visit_ident(&mut self, _ident: Ident) {}
 113     fn visit_foreign_item(&mut self, i: &'ast ForeignItem) {
 114         walk_foreign_item(self, i)
 115     }
 116     fn visit_item(&mut self, i: &'ast Item) {
 117         walk_item(self, i)
 118     }
 119     fn visit_local(&mut self, l: &'ast Local) {
 120         walk_local(self, l)
 121     }
 122     fn visit_block(&mut self, b: &'ast Block) {
 123         walk_block(self, b)
 124     }
 125     fn visit_stmt(&mut self, s: &'ast Stmt) {
 126         walk_stmt(self, s)
 127     }
 128     fn visit_param(&mut self, param: &'ast Param) {
 129         walk_param(self, param)
 130     }
 131     fn visit_arm(&mut self, a: &'ast Arm) {
 132         walk_arm(self, a)
 133     }
 134     fn visit_pat(&mut self, p: &'ast Pat) {
 135         walk_pat(self, p)
 136     }
 137     fn visit_anon_const(&mut self, c: &'ast AnonConst) {
 138         walk_anon_const(self, c)
 139     }
 140     fn visit_expr(&mut self, ex: &'ast Expr) {
 141         walk_expr(self, ex)
 142     }
 143     /// This method is a hack to workaround unstable of `stmt_expr_attributes`.
 144     /// It can be removed once that feature is stabilized.
 145     fn visit_method_receiver_expr(&mut self, ex: &'ast Expr) {
 146         self.visit_expr(ex)
 147     }
 148     fn visit_expr_post(&mut self, _ex: &'ast Expr) {}
 149     fn visit_ty(&mut self, t: &'ast Ty) {
 150         walk_ty(self, t)
 151     }
 152     fn visit_generic_param(&mut self, param: &'ast GenericParam) {
 153         walk_generic_param(self, param)
 154     }
 155     fn visit_generics(&mut self, g: &'ast Generics) {
 156         walk_generics(self, g)
 157     }
 158     fn visit_closure_binder(&mut self, b: &'ast ClosureBinder) {
 159         walk_closure_binder(self, b)
 160     }
 161     fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
 162         walk_where_predicate(self, p)
 163     }
 164     fn visit_fn(&mut self, fk: FnKind<'ast>, _: Span, _: NodeId) {
 165         walk_fn(self, fk)
 166     }
 167     fn visit_assoc_item(&mut self, i: &'ast AssocItem, ctxt: AssocCtxt) {
 168         walk_assoc_item(self, i, ctxt)
 169     }
 170     fn visit_trait_ref(&mut self, t: &'ast TraitRef) {
 171         walk_trait_ref(self, t)
 172     }
 173     fn visit_param_bound(&mut self, bounds: &'ast GenericBound, _ctxt: BoundKind) {
 174         walk_param_bound(self, bounds)
 175     }
 176     fn visit_poly_trait_ref(&mut self, t: &'ast PolyTraitRef) {
 177         walk_poly_trait_ref(self, t)
 178     }
 179     fn visit_variant_data(&mut self, s: &'ast VariantData) {
 180         walk_struct_def(self, s)
 181     }
 182     fn visit_field_def(&mut self, s: &'ast FieldDef) {
 183         walk_field_def(self, s)
 184     }
 185     fn visit_enum_def(&mut self, enum_definition: &'ast EnumDef) {
 186         walk_enum_def(self, enum_definition)
 187     }
 188     fn visit_variant(&mut self, v: &'ast Variant) {
 189         walk_variant(self, v)
 190     }
 191     fn visit_variant_discr(&mut self, discr: &'ast AnonConst) {
 192         self.visit_anon_const(discr);
 193     }
 194     fn visit_label(&mut self, label: &'ast Label) {
 195         walk_label(self, label)
 196     }
 197     fn visit_lifetime(&mut self, lifetime: &'ast Lifetime, _: LifetimeCtxt) {
 198         walk_lifetime(self, lifetime)
 199     }
 200     fn visit_mac_call(&mut self, mac: &'ast MacCall) {
 201         walk_mac(self, mac)
 202     }
 203     fn visit_mac_def(&mut self, _mac: &'ast MacroDef, _id: NodeId) {
 204         // Nothing to do
 205     }
 206     fn visit_path(&mut self, path: &'ast Path, _id: NodeId) {
 207         walk_path(self, path)
 208     }
 209     fn visit_use_tree(&mut self, use_tree: &'ast UseTree, id: NodeId, _nested: bool) {
 210         walk_use_tree(self, use_tree, id)
 211     }
 212     fn visit_path_segment(&mut self, path_segment: &'ast PathSegment) {
 213         walk_path_segment(self, path_segment)
 214     }
 215     fn visit_generic_args(&mut self, generic_args: &'ast GenericArgs) {
 216         walk_generic_args(self, generic_args)
 217     }
 218     fn visit_generic_arg(&mut self, generic_arg: &'ast GenericArg) {
 219         walk_generic_arg(self, generic_arg)
 220     }
 221     fn visit_assoc_constraint(&mut self, constraint: &'ast AssocConstraint) {
 222         walk_assoc_constraint(self, constraint)
 223     }
 224     fn visit_attribute(&mut self, attr: &'ast Attribute) {
 225         walk_attribute(self, attr)
 226     }
 227     fn visit_vis(&mut self, vis: &'ast Visibility) {
 228         walk_vis(self, vis)
 229     }
 230     fn visit_fn_ret_ty(&mut self, ret_ty: &'ast FnRetTy) {
 231         walk_fn_ret_ty(self, ret_ty)
 232     }
 233     fn visit_fn_header(&mut self, _header: &'ast FnHeader) {
 234         // Nothing to do
 235     }
 236     fn visit_expr_field(&mut self, f: &'ast ExprField) {
 237         walk_expr_field(self, f)
 238     }
 239     fn visit_pat_field(&mut self, fp: &'ast PatField) {
 240         walk_pat_field(self, fp)
 241     }
 242     fn visit_crate(&mut self, krate: &'ast Crate) {
 243         walk_crate(self, krate)
 244     }
 245     fn visit_inline_asm(&mut self, asm: &'ast InlineAsm) {
 246         walk_inline_asm(self, asm)
 247     }
 248     fn visit_format_args(&mut self, fmt: &'ast FormatArgs) {
 249         walk_format_args(self, fmt)
 250     }
 251     fn visit_inline_asm_sym(&mut self, sym: &'ast InlineAsmSym) {
 252         walk_inline_asm_sym(self, sym)
 253     }
 254 }
 255
 256 #[macro_export]
 257 macro_rules! walk_list {
 258     ($visitor: expr, $method: ident, $list: expr $(, $($extra_args: expr),* )?) => {
 259         {
 260             #[allow(for_loops_over_fallibles)]
 261             for elem in $list {
 262                 $visitor.$method(elem $(, $($extra_args,)* )?)
 263             }
 264         }
 265     }
 266 }
 267
 268 pub fn walk_crate<'a, V: Visitor<'a>>(visitor: &mut V, krate: &'a Crate) {
 269     walk_list!(visitor, visit_item, &krate.items);
 270     walk_list!(visitor, visit_attribute, &krate.attrs);
 271 }
 272
 273 pub fn walk_local<'a, V: Visitor<'a>>(visitor: &mut V, local: &'a Local) {
 274     for attr in local.attrs.iter() {
 275         visitor.visit_attribute(attr);
 276     }
 277     visitor.visit_pat(&local.pat);
 278     walk_list!(visitor, visit_ty, &local.ty);
 279     if let Some((init, els)) = local.kind.init_else_opt() {
 280         visitor.visit_expr(init);
 281         walk_list!(visitor, visit_block, els);
 282     }
 283 }
 284
 285 pub fn walk_label<'a, V: Visitor<'a>>(visitor: &mut V, label: &'a Label) {
 286     visitor.visit_ident(label.ident);
 287 }
 288
 289 pub fn walk_lifetime<'a, V: Visitor<'a>>(visitor: &mut V, lifetime: &'a Lifetime) {
 290     visitor.visit_ident(lifetime.ident);
 291 }
 292
 293 pub fn walk_poly_trait_ref<'a, V>(visitor: &mut V, trait_ref: &'a PolyTraitRef)
 294 where
 295     V: Visitor<'a>,
 296 {
 297     walk_list!(visitor, visit_generic_param, &trait_ref.bound_generic_params);
 298     visitor.visit_trait_ref(&trait_ref.trait_ref);
 299 }
 300
 301 pub fn walk_trait_ref<'a, V: Visitor<'a>>(visitor: &mut V, trait_ref: &'a TraitRef) {
 302     visitor.visit_path(&trait_ref.path, trait_ref.ref_id)
 303 }
 304
 305 pub fn walk_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a Item) {
 306     visitor.visit_vis(&item.vis);
 307     visitor.visit_ident(item.ident);
 308     match &item.kind {
 309         ItemKind::ExternCrate(_) => {}
 310         ItemKind::Use(use_tree) => visitor.visit_use_tree(use_tree, item.id, false),
 311         ItemKind::Static(box StaticItem { ty, mutability: _, expr })
 312         | ItemKind::Const(box ConstItem { ty, expr, .. }) => {
 313             visitor.visit_ty(ty);
 314             walk_list!(visitor, visit_expr, expr);
 315         }
 316         ItemKind::Fn(box Fn { defaultness: _, generics, sig, body }) => {
 317             let kind =
 318                 FnKind::Fn(FnCtxt::Free, item.ident, sig, &item.vis, generics, body.as_deref());
 319             visitor.visit_fn(kind, item.span, item.id)
 320         }
 321         ItemKind::Mod(_unsafety, mod_kind) => match mod_kind {
 322             ModKind::Loaded(items, _inline, _inner_span) => {
 323                 walk_list!(visitor, visit_item, items)
 324             }
 325             ModKind::Unloaded => {}
 326         },
 327         ItemKind::ForeignMod(foreign_module) => {
 328             walk_list!(visitor, visit_foreign_item, &foreign_module.items);
 329         }
 330         ItemKind::GlobalAsm(asm) => visitor.visit_inline_asm(asm),
 331         ItemKind::TyAlias(box TyAlias { generics, bounds, ty, .. }) => {
 332             visitor.visit_generics(generics);
 333             walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
 334             walk_list!(visitor, visit_ty, ty);
 335         }
 336         ItemKind::Enum(enum_definition, generics) => {
 337             visitor.visit_generics(generics);
 338             visitor.visit_enum_def(enum_definition)
 339         }
 340         ItemKind::Impl(box Impl {
 341             defaultness: _,
 342             unsafety: _,
 343             generics,
 344             constness: _,
 345             polarity: _,
 346             of_trait,
 347             self_ty,
 348             items,
 349         }) => {
 350             visitor.visit_generics(generics);
 351             walk_list!(visitor, visit_trait_ref, of_trait);
 352             visitor.visit_ty(self_ty);
 353             walk_list!(visitor, visit_assoc_item, items, AssocCtxt::Impl);
 354         }
 355         ItemKind::Struct(struct_definition, generics)
 356         | ItemKind::Union(struct_definition, generics) => {
 357             visitor.visit_generics(generics);
 358             visitor.visit_variant_data(struct_definition);
 359         }
 360         ItemKind::Trait(box Trait { unsafety: _, is_auto: _, generics, bounds, items }) => {
 361             visitor.visit_generics(generics);
 362             walk_list!(visitor, visit_param_bound, bounds, BoundKind::SuperTraits);
 363             walk_list!(visitor, visit_assoc_item, items, AssocCtxt::Trait);
 364         }
 365         ItemKind::TraitAlias(generics, bounds) => {
 366             visitor.visit_generics(generics);
 367             walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
 368         }
 369         ItemKind::MacCall(mac) => visitor.visit_mac_call(mac),
 370         ItemKind::MacroDef(ts) => visitor.visit_mac_def(ts, item.id),
 371     }
 372     walk_list!(visitor, visit_attribute, &item.attrs);
 373 }
 374
 375 pub fn walk_enum_def<'a, V: Visitor<'a>>(visitor: &mut V, enum_definition: &'a EnumDef) {
 376     walk_list!(visitor, visit_variant, &enum_definition.variants);
 377 }
 378
 379 pub fn walk_variant<'a, V: Visitor<'a>>(visitor: &mut V, variant: &'a Variant)
 380 where
 381     V: Visitor<'a>,
 382 {
 383     visitor.visit_ident(variant.ident);
 384     visitor.visit_vis(&variant.vis);
 385     visitor.visit_variant_data(&variant.data);
 386     walk_list!(visitor, visit_variant_discr, &variant.disr_expr);
 387     walk_list!(visitor, visit_attribute, &variant.attrs);
 388 }
 389
 390 pub fn walk_expr_field<'a, V: Visitor<'a>>(visitor: &mut V, f: &'a ExprField) {
 391     visitor.visit_expr(&f.expr);
 392     visitor.visit_ident(f.ident);
 393     walk_list!(visitor, visit_attribute, f.attrs.iter());
 394 }
 395
 396 pub fn walk_pat_field<'a, V: Visitor<'a>>(visitor: &mut V, fp: &'a PatField) {
 397     visitor.visit_ident(fp.ident);
 398     visitor.visit_pat(&fp.pat);
 399     walk_list!(visitor, visit_attribute, fp.attrs.iter());
 400 }
 401
 402 pub fn walk_ty<'a, V: Visitor<'a>>(visitor: &mut V, typ: &'a Ty) {
 403     match &typ.kind {
 404         TyKind::Slice(ty) | TyKind::Paren(ty) => visitor.visit_ty(ty),
 405         TyKind::Ptr(mutable_type) => visitor.visit_ty(&mutable_type.ty),
 406         TyKind::Ref(opt_lifetime, mutable_type) => {
 407             walk_list!(visitor, visit_lifetime, opt_lifetime, LifetimeCtxt::Ref);
 408             visitor.visit_ty(&mutable_type.ty)
 409         }
 410         TyKind::Tup(tuple_element_types) => {
 411             walk_list!(visitor, visit_ty, tuple_element_types);
 412         }
 413         TyKind::BareFn(function_declaration) => {
 414             walk_list!(visitor, visit_generic_param, &function_declaration.generic_params);
 415             walk_fn_decl(visitor, &function_declaration.decl);
 416         }
 417         TyKind::Path(maybe_qself, path) => {
 418             if let Some(qself) = maybe_qself {
 419                 visitor.visit_ty(&qself.ty);
 420             }
 421             visitor.visit_path(path, typ.id);
 422         }
 423         TyKind::Array(ty, length) => {
 424             visitor.visit_ty(ty);
 425             visitor.visit_anon_const(length)
 426         }
 427         TyKind::TraitObject(bounds, ..) => {
 428             walk_list!(visitor, visit_param_bound, bounds, BoundKind::TraitObject);
 429         }
 430         TyKind::ImplTrait(_, bounds) => {
 431             walk_list!(visitor, visit_param_bound, bounds, BoundKind::Impl);
 432         }
 433         TyKind::Typeof(expression) => visitor.visit_anon_const(expression),
 434         TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err => {}
 435         TyKind::MacCall(mac) => visitor.visit_mac_call(mac),
 436         TyKind::Never | TyKind::CVarArgs => {}
 437     }
 438 }
 439
 440 pub fn walk_path<'a, V: Visitor<'a>>(visitor: &mut V, path: &'a Path) {
 441     for segment in &path.segments {
 442         visitor.visit_path_segment(segment);
 443     }
 444 }
 445
 446 pub fn walk_use_tree<'a, V: Visitor<'a>>(visitor: &mut V, use_tree: &'a UseTree, id: NodeId) {
 447     visitor.visit_path(&use_tree.prefix, id);
 448     match &use_tree.kind {
 449         UseTreeKind::Simple(rename) => {
 450             // The extra IDs are handled during HIR lowering.
 451             if let &Some(rename) = rename {
 452                 visitor.visit_ident(rename);
 453             }
 454         }
 455         UseTreeKind::Glob => {}
 456         UseTreeKind::Nested(use_trees) => {
 457             for &(ref nested_tree, nested_id) in use_trees {
 458                 visitor.visit_use_tree(nested_tree, nested_id, true);
 459             }
 460         }
 461     }
 462 }
 463
 464 pub fn walk_path_segment<'a, V: Visitor<'a>>(visitor: &mut V, segment: &'a PathSegment) {
 465     visitor.visit_ident(segment.ident);
 466     if let Some(args) = &segment.args {
 467         visitor.visit_generic_args(args);
 468     }
 469 }
 470
 471 pub fn walk_generic_args<'a, V>(visitor: &mut V, generic_args: &'a GenericArgs)
 472 where
 473     V: Visitor<'a>,
 474 {
 475     match generic_args {
 476         GenericArgs::AngleBracketed(data) => {
 477             for arg in &data.args {
 478                 match arg {
 479                     AngleBracketedArg::Arg(a) => visitor.visit_generic_arg(a),
 480                     AngleBracketedArg::Constraint(c) => visitor.visit_assoc_constraint(c),
 481                 }
 482             }
 483         }
 484         GenericArgs::Parenthesized(data) => {
 485             walk_list!(visitor, visit_ty, &data.inputs);
 486             walk_fn_ret_ty(visitor, &data.output);
 487         }
 488     }
 489 }
 490
 491 pub fn walk_generic_arg<'a, V>(visitor: &mut V, generic_arg: &'a GenericArg)
 492 where
 493     V: Visitor<'a>,
 494 {
 495     match generic_arg {
 496         GenericArg::Lifetime(lt) => visitor.visit_lifetime(lt, LifetimeCtxt::GenericArg),
 497         GenericArg::Type(ty) => visitor.visit_ty(ty),
 498         GenericArg::Const(ct) => visitor.visit_anon_const(ct),
 499     }
 500 }
 501
 502 pub fn walk_assoc_constraint<'a, V: Visitor<'a>>(visitor: &mut V, constraint: &'a AssocConstraint) {
 503     visitor.visit_ident(constraint.ident);
 504     if let Some(gen_args) = &constraint.gen_args {
 505         visitor.visit_generic_args(gen_args);
 506     }
 507     match &constraint.kind {
 508         AssocConstraintKind::Equality { term } => match term {
 509             Term::Ty(ty) => visitor.visit_ty(ty),
 510             Term::Const(c) => visitor.visit_anon_const(c),
 511         },
 512         AssocConstraintKind::Bound { bounds } => {
 513             walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
 514         }
 515     }
 516 }
 517
 518 pub fn walk_pat<'a, V: Visitor<'a>>(visitor: &mut V, pattern: &'a Pat) {
 519     match &pattern.kind {
 520         PatKind::TupleStruct(opt_qself, path, elems) => {
 521             if let Some(qself) = opt_qself {
 522                 visitor.visit_ty(&qself.ty);
 523             }
 524             visitor.visit_path(path, pattern.id);
 525             walk_list!(visitor, visit_pat, elems);
 526         }
 527         PatKind::Path(opt_qself, path) => {
 528             if let Some(qself) = opt_qself {
 529                 visitor.visit_ty(&qself.ty);
 530             }
 531             visitor.visit_path(path, pattern.id)
 532         }
 533         PatKind::Struct(opt_qself, path, fields, _) => {
 534             if let Some(qself) = opt_qself {
 535                 visitor.visit_ty(&qself.ty);
 536             }
 537             visitor.visit_path(path, pattern.id);
 538             walk_list!(visitor, visit_pat_field, fields);
 539         }
 540         PatKind::Box(subpattern) | PatKind::Ref(subpattern, _) | PatKind::Paren(subpattern) => {
 541             visitor.visit_pat(subpattern)
 542         }
 543         PatKind::Ident(_, ident, optional_subpattern) => {
 544             visitor.visit_ident(*ident);
 545             walk_list!(visitor, visit_pat, optional_subpattern);
 546         }
 547         PatKind::Lit(expression) => visitor.visit_expr(expression),
 548         PatKind::Range(lower_bound, upper_bound, _) => {
 549             walk_list!(visitor, visit_expr, lower_bound);
 550             walk_list!(visitor, visit_expr, upper_bound);
 551         }
 552         PatKind::Wild | PatKind::Rest => {}
 553         PatKind::Tuple(elems) | PatKind::Slice(elems) | PatKind::Or(elems) => {
 554             walk_list!(visitor, visit_pat, elems);
 555         }
 556         PatKind::MacCall(mac) => visitor.visit_mac_call(mac),
 557     }
 558 }
 559
 560 pub fn walk_foreign_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a ForeignItem) {
 561     let &Item { id, span, ident, ref vis, ref attrs, ref kind, tokens: _ } = item;
 562     visitor.visit_vis(vis);
 563     visitor.visit_ident(ident);
 564     walk_list!(visitor, visit_attribute, attrs);
 565     match kind {
 566         ForeignItemKind::Static(ty, _, expr) => {
 567             visitor.visit_ty(ty);
 568             walk_list!(visitor, visit_expr, expr);
 569         }
 570         ForeignItemKind::Fn(box Fn { defaultness: _, generics, sig, body }) => {
 571             let kind = FnKind::Fn(FnCtxt::Foreign, ident, sig, vis, generics, body.as_deref());
 572             visitor.visit_fn(kind, span, id);
 573         }
 574         ForeignItemKind::TyAlias(box TyAlias { generics, bounds, ty, .. }) => {
 575             visitor.visit_generics(generics);
 576             walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
 577             walk_list!(visitor, visit_ty, ty);
 578         }
 579         ForeignItemKind::MacCall(mac) => {
 580             visitor.visit_mac_call(mac);
 581         }
 582     }
 583 }
 584
 585 pub fn walk_param_bound<'a, V: Visitor<'a>>(visitor: &mut V, bound: &'a GenericBound) {
 586     match bound {
 587         GenericBound::Trait(typ, _modifier) => visitor.visit_poly_trait_ref(typ),
 588         GenericBound::Outlives(lifetime) => visitor.visit_lifetime(lifetime, LifetimeCtxt::Bound),
 589     }
 590 }
 591
 592 pub fn walk_generic_param<'a, V: Visitor<'a>>(visitor: &mut V, param: &'a GenericParam) {
 593     visitor.visit_ident(param.ident);
 594     walk_list!(visitor, visit_attribute, param.attrs.iter());
 595     walk_list!(visitor, visit_param_bound, &param.bounds, BoundKind::Bound);
 596     match &param.kind {
 597         GenericParamKind::Lifetime => (),
 598         GenericParamKind::Type { default } => walk_list!(visitor, visit_ty, default),
 599         GenericParamKind::Const { ty, default, .. } => {
 600             visitor.visit_ty(ty);
 601             if let Some(default) = default {
 602                 visitor.visit_anon_const(default);
 603             }
 604         }
 605     }
 606 }
 607
 608 pub fn walk_generics<'a, V: Visitor<'a>>(visitor: &mut V, generics: &'a Generics) {
 609     walk_list!(visitor, visit_generic_param, &generics.params);
 610     walk_list!(visitor, visit_where_predicate, &generics.where_clause.predicates);
 611 }
 612
 613 pub fn walk_closure_binder<'a, V: Visitor<'a>>(visitor: &mut V, binder: &'a ClosureBinder) {
 614     match binder {
 615         ClosureBinder::NotPresent => {}
 616         ClosureBinder::For { generic_params, span: _ } => {
 617             walk_list!(visitor, visit_generic_param, generic_params)
 618         }
 619     }
 620 }
 621
 622 pub fn walk_where_predicate<'a, V: Visitor<'a>>(visitor: &mut V, predicate: &'a WherePredicate) {
 623     match predicate {
 624         WherePredicate::BoundPredicate(WhereBoundPredicate {
 625             bounded_ty,
 626             bounds,
 627             bound_generic_params,
 628             ..
 629         }) => {
 630             visitor.visit_ty(bounded_ty);
 631             walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
 632             walk_list!(visitor, visit_generic_param, bound_generic_params);
 633         }
 634         WherePredicate::RegionPredicate(WhereRegionPredicate { lifetime, bounds, .. }) => {
 635             visitor.visit_lifetime(lifetime, LifetimeCtxt::Bound);
 636             walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
 637         }
 638         WherePredicate::EqPredicate(WhereEqPredicate { lhs_ty, rhs_ty, .. }) => {
 639             visitor.visit_ty(lhs_ty);
 640             visitor.visit_ty(rhs_ty);
 641         }
 642     }
 643 }
 644
 645 pub fn walk_fn_ret_ty<'a, V: Visitor<'a>>(visitor: &mut V, ret_ty: &'a FnRetTy) {
 646     if let FnRetTy::Ty(output_ty) = ret_ty {
 647         visitor.visit_ty(output_ty)
 648     }
 649 }
 650
 651 pub fn walk_fn_decl<'a, V: Visitor<'a>>(visitor: &mut V, function_declaration: &'a FnDecl) {
 652     for param in &function_declaration.inputs {
 653         visitor.visit_param(param);
 654     }
 655     visitor.visit_fn_ret_ty(&function_declaration.output);
 656 }
 657
 658 pub fn walk_fn<'a, V: Visitor<'a>>(visitor: &mut V, kind: FnKind<'a>) {
 659     match kind {
 660         FnKind::Fn(_, _, sig, _, generics, body) => {
 661             visitor.visit_generics(generics);
 662             visitor.visit_fn_header(&sig.header);
 663             walk_fn_decl(visitor, &sig.decl);
 664             walk_list!(visitor, visit_block, body);
 665         }
 666         FnKind::Closure(binder, decl, body) => {
 667             visitor.visit_closure_binder(binder);
 668             walk_fn_decl(visitor, decl);
 669             visitor.visit_expr(body);
 670         }
 671     }
 672 }
 673
 674 pub fn walk_assoc_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a AssocItem, ctxt: AssocCtxt) {
 675     let &Item { id, span, ident, ref vis, ref attrs, ref kind, tokens: _ } = item;
 676     visitor.visit_vis(vis);
 677     visitor.visit_ident(ident);
 678     walk_list!(visitor, visit_attribute, attrs);
 679     match kind {
 680         AssocItemKind::Const(box ConstItem { ty, expr, .. }) => {
 681             visitor.visit_ty(ty);
 682             walk_list!(visitor, visit_expr, expr);
 683         }
 684         AssocItemKind::Fn(box Fn { defaultness: _, generics, sig, body }) => {
 685             let kind = FnKind::Fn(FnCtxt::Assoc(ctxt), ident, sig, vis, generics, body.as_deref());
 686             visitor.visit_fn(kind, span, id);
 687         }
 688         AssocItemKind::Type(box TyAlias { generics, bounds, ty, .. }) => {
 689             visitor.visit_generics(generics);
 690             walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
 691             walk_list!(visitor, visit_ty, ty);
 692         }
 693         AssocItemKind::MacCall(mac) => {
 694             visitor.visit_mac_call(mac);
 695         }
 696     }
 697 }
 698
 699 pub fn walk_struct_def<'a, V: Visitor<'a>>(visitor: &mut V, struct_definition: &'a VariantData) {
 700     walk_list!(visitor, visit_field_def, struct_definition.fields());
 701 }
 702
 703 pub fn walk_field_def<'a, V: Visitor<'a>>(visitor: &mut V, field: &'a FieldDef) {
 704     visitor.visit_vis(&field.vis);
 705     if let Some(ident) = field.ident {
 706         visitor.visit_ident(ident);
 707     }
 708     visitor.visit_ty(&field.ty);
 709     walk_list!(visitor, visit_attribute, &field.attrs);
 710 }
 711
 712 pub fn walk_block<'a, V: Visitor<'a>>(visitor: &mut V, block: &'a Block) {
 713     walk_list!(visitor, visit_stmt, &block.stmts);
 714 }
 715
 716 pub fn walk_stmt<'a, V: Visitor<'a>>(visitor: &mut V, statement: &'a Stmt) {
 717     match &statement.kind {
 718         StmtKind::Local(local) => visitor.visit_local(local),
 719         StmtKind::Item(item) => visitor.visit_item(item),
 720         StmtKind::Expr(expr) | StmtKind::Semi(expr) => visitor.visit_expr(expr),
 721         StmtKind::Empty => {}
 722         StmtKind::MacCall(mac) => {
 723             let MacCallStmt { mac, attrs, style: _, tokens: _ } = &**mac;
 724             visitor.visit_mac_call(mac);
 725             for attr in attrs.iter() {
 726                 visitor.visit_attribute(attr);
 727             }
 728         }
 729     }
 730 }
 731
 732 pub fn walk_mac<'a, V: Visitor<'a>>(visitor: &mut V, mac: &'a MacCall) {
 733     visitor.visit_path(&mac.path, DUMMY_NODE_ID);
 734 }
 735
 736 pub fn walk_anon_const<'a, V: Visitor<'a>>(visitor: &mut V, constant: &'a AnonConst) {
 737     visitor.visit_expr(&constant.value);
 738 }
 739
 740 pub fn walk_inline_asm<'a, V: Visitor<'a>>(visitor: &mut V, asm: &'a InlineAsm) {
 741     for (op, _) in &asm.operands {
 742         match op {
 743             InlineAsmOperand::In { expr, .. }
 744             | InlineAsmOperand::Out { expr: Some(expr), .. }
 745             | InlineAsmOperand::InOut { expr, .. } => visitor.visit_expr(expr),
 746             InlineAsmOperand::Out { expr: None, .. } => {}
 747             InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
 748                 visitor.visit_expr(in_expr);
 749                 if let Some(out_expr) = out_expr {
 750                     visitor.visit_expr(out_expr);
 751                 }
 752             }
 753             InlineAsmOperand::Const { anon_const, .. } => visitor.visit_anon_const(anon_const),
 754             InlineAsmOperand::Sym { sym } => visitor.visit_inline_asm_sym(sym),
 755         }
 756     }
 757 }
 758
 759 pub fn walk_inline_asm_sym<'a, V: Visitor<'a>>(visitor: &mut V, sym: &'a InlineAsmSym) {
 760     if let Some(qself) = &sym.qself {
 761         visitor.visit_ty(&qself.ty);
 762     }
 763     visitor.visit_path(&sym.path, sym.id);
 764 }
 765
 766 pub fn walk_format_args<'a, V: Visitor<'a>>(visitor: &mut V, fmt: &'a FormatArgs) {
 767     for arg in fmt.arguments.all_args() {
 768         if let FormatArgumentKind::Named(name) = arg.kind {
 769             visitor.visit_ident(name);
 770         }
 771         visitor.visit_expr(&arg.expr);
 772     }
 773 }
 774
 775 pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
 776     walk_list!(visitor, visit_attribute, expression.attrs.iter());
 777
 778     match &expression.kind {
 779         ExprKind::Array(subexpressions) => {
 780             walk_list!(visitor, visit_expr, subexpressions);
 781         }
 782         ExprKind::ConstBlock(anon_const) => visitor.visit_anon_const(anon_const),
 783         ExprKind::Repeat(element, count) => {
 784             visitor.visit_expr(element);
 785             visitor.visit_anon_const(count)
 786         }
 787         ExprKind::Struct(se) => {
 788             if let Some(qself) = &se.qself {
 789                 visitor.visit_ty(&qself.ty);
 790             }
 791             visitor.visit_path(&se.path, expression.id);
 792             walk_list!(visitor, visit_expr_field, &se.fields);
 793             match &se.rest {
 794                 StructRest::Base(expr) => visitor.visit_expr(expr),
 795                 StructRest::Rest(_span) => {}
 796                 StructRest::None => {}
 797             }
 798         }
 799         ExprKind::Tup(subexpressions) => {
 800             walk_list!(visitor, visit_expr, subexpressions);
 801         }
 802         ExprKind::Call(callee_expression, arguments) => {
 803             visitor.visit_expr(callee_expression);
 804             walk_list!(visitor, visit_expr, arguments);
 805         }
 806         ExprKind::MethodCall(box MethodCall { seg, receiver, args, span: _ }) => {
 807             visitor.visit_path_segment(seg);
 808             visitor.visit_expr(receiver);
 809             walk_list!(visitor, visit_expr, args);
 810         }
 811         ExprKind::Binary(_, left_expression, right_expression) => {
 812             visitor.visit_expr(left_expression);
 813             visitor.visit_expr(right_expression)
 814         }
 815         ExprKind::AddrOf(_, _, subexpression) | ExprKind::Unary(_, subexpression) => {
 816             visitor.visit_expr(subexpression)
 817         }
 818         ExprKind::Cast(subexpression, typ) | ExprKind::Type(subexpression, typ) => {
 819             visitor.visit_expr(subexpression);
 820             visitor.visit_ty(typ)
 821         }
 822         ExprKind::Let(pat, expr, _) => {
 823             visitor.visit_pat(pat);
 824             visitor.visit_expr(expr);
 825         }
 826         ExprKind::If(head_expression, if_block, optional_else) => {
 827             visitor.visit_expr(head_expression);
 828             visitor.visit_block(if_block);
 829             walk_list!(visitor, visit_expr, optional_else);
 830         }
 831         ExprKind::While(subexpression, block, opt_label) => {
 832             walk_list!(visitor, visit_label, opt_label);
 833             visitor.visit_expr(subexpression);
 834             visitor.visit_block(block);
 835         }
 836         ExprKind::ForLoop(pattern, subexpression, block, opt_label) => {
 837             walk_list!(visitor, visit_label, opt_label);
 838             visitor.visit_pat(pattern);
 839             visitor.visit_expr(subexpression);
 840             visitor.visit_block(block);
 841         }
 842         ExprKind::Loop(block, opt_label, _) => {
 843             walk_list!(visitor, visit_label, opt_label);
 844             visitor.visit_block(block);
 845         }
 846         ExprKind::Match(subexpression, arms) => {
 847             visitor.visit_expr(subexpression);
 848             walk_list!(visitor, visit_arm, arms);
 849         }
 850         ExprKind::Closure(box Closure {
 851             binder,
 852             capture_clause: _,
 853             asyncness: _,
 854             constness: _,
 855             movability: _,
 856             fn_decl,
 857             body,
 858             fn_decl_span: _,
 859             fn_arg_span: _,
 860         }) => {
 861             visitor.visit_fn(FnKind::Closure(binder, fn_decl, body), expression.span, expression.id)
 862         }
 863         ExprKind::Block(block, opt_label) => {
 864             walk_list!(visitor, visit_label, opt_label);
 865             visitor.visit_block(block);
 866         }
 867         ExprKind::Async(_, body) => {
 868             visitor.visit_block(body);
 869         }
 870         ExprKind::Await(expr, _) => visitor.visit_expr(expr),
 871         ExprKind::Assign(lhs, rhs, _) => {
 872             visitor.visit_expr(lhs);
 873             visitor.visit_expr(rhs);
 874         }
 875         ExprKind::AssignOp(_, left_expression, right_expression) => {
 876             visitor.visit_expr(left_expression);
 877             visitor.visit_expr(right_expression);
 878         }
 879         ExprKind::Field(subexpression, ident) => {
 880             visitor.visit_expr(subexpression);
 881             visitor.visit_ident(*ident);
 882         }
 883         ExprKind::Index(main_expression, index_expression) => {
 884             visitor.visit_expr(main_expression);
 885             visitor.visit_expr(index_expression)
 886         }
 887         ExprKind::Range(start, end, _) => {
 888             walk_list!(visitor, visit_expr, start);
 889             walk_list!(visitor, visit_expr, end);
 890         }
 891         ExprKind::Underscore => {}
 892         ExprKind::Path(maybe_qself, path) => {
 893             if let Some(qself) = maybe_qself {
 894                 visitor.visit_ty(&qself.ty);
 895             }
 896             visitor.visit_path(path, expression.id)
 897         }
 898         ExprKind::Break(opt_label, opt_expr) => {
 899             walk_list!(visitor, visit_label, opt_label);
 900             walk_list!(visitor, visit_expr, opt_expr);
 901         }
 902         ExprKind::Continue(opt_label) => {
 903             walk_list!(visitor, visit_label, opt_label);
 904         }
 905         ExprKind::Ret(optional_expression) => {
 906             walk_list!(visitor, visit_expr, optional_expression);
 907         }
 908         ExprKind::Yeet(optional_expression) => {
 909             walk_list!(visitor, visit_expr, optional_expression);
 910         }
 911         ExprKind::Become(expr) => visitor.visit_expr(expr),
 912         ExprKind::MacCall(mac) => visitor.visit_mac_call(mac),
 913         ExprKind::Paren(subexpression) => visitor.visit_expr(subexpression),
 914         ExprKind::InlineAsm(asm) => visitor.visit_inline_asm(asm),
 915         ExprKind::FormatArgs(f) => visitor.visit_format_args(f),
 916         ExprKind::OffsetOf(container, fields) => {
 917             visitor.visit_ty(container);
 918             for &field in fields {
 919                 visitor.visit_ident(field);
 920             }
 921         }
 922         ExprKind::Yield(optional_expression) => {
 923             walk_list!(visitor, visit_expr, optional_expression);
 924         }
 925         ExprKind::Try(subexpression) => visitor.visit_expr(subexpression),
 926         ExprKind::TryBlock(body) => visitor.visit_block(body),
 927         ExprKind::Lit(_) | ExprKind::IncludedBytes(..) | ExprKind::Err => {}
 928     }
 929
 930     visitor.visit_expr_post(expression)
 931 }
 932
 933 pub fn walk_param<'a, V: Visitor<'a>>(visitor: &mut V, param: &'a Param) {
 934     walk_list!(visitor, visit_attribute, param.attrs.iter());
 935     visitor.visit_pat(&param.pat);
 936     visitor.visit_ty(&param.ty);
 937 }
 938
 939 pub fn walk_arm<'a, V: Visitor<'a>>(visitor: &mut V, arm: &'a Arm) {
 940     visitor.visit_pat(&arm.pat);
 941     walk_list!(visitor, visit_expr, &arm.guard);
 942     visitor.visit_expr(&arm.body);
 943     walk_list!(visitor, visit_attribute, &arm.attrs);
 944 }
 945
 946 pub fn walk_vis<'a, V: Visitor<'a>>(visitor: &mut V, vis: &'a Visibility) {
 947     if let VisibilityKind::Restricted { ref path, id, shorthand: _ } = vis.kind {
 948         visitor.visit_path(path, id);
 949     }
 950 }
 951
 952 pub fn walk_attribute<'a, V: Visitor<'a>>(visitor: &mut V, attr: &'a Attribute) {
 953     match &attr.kind {
 954         AttrKind::Normal(normal) => walk_attr_args(visitor, &normal.item.args),
 955         AttrKind::DocComment(..) => {}
 956     }
 957 }
 958
 959 pub fn walk_attr_args<'a, V: Visitor<'a>>(visitor: &mut V, args: &'a AttrArgs) {
 960     match args {
 961         AttrArgs::Empty => {}
 962         AttrArgs::Delimited(_) => {}
 963         AttrArgs::Eq(_eq_span, AttrArgsEq::Ast(expr)) => visitor.visit_expr(expr),
 964         AttrArgs::Eq(_, AttrArgsEq::Hir(lit)) => {
 965             unreachable!("in literal form when walking mac args eq: {:?}", lit)
 966         }
 967     }
 968 }