src/libsyntax/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::*;
  17 use crate::token::Token;
  18 use crate::tokenstream::{TokenStream, TokenTree};
  19
  20 use rustc_span::Span;
  21
  22 #[derive(Copy, Clone)]
  23 pub enum FnKind<'a> {
  24     /// E.g., `fn foo()` or `extern "Abi" fn foo()`.
  25     ItemFn(Ident, &'a FnHeader, &'a Visibility, &'a Block),
  26
  27     /// E.g., `fn foo(&self)`.
  28     Method(Ident, &'a FnSig, &'a Visibility, &'a Block),
  29
  30     /// E.g., `|x, y| body`.
  31     Closure(&'a Expr),
  32 }
  33
  34 impl<'a> FnKind<'a> {
  35     pub fn header(&self) -> Option<&'a FnHeader> {
  36         match *self {
  37             FnKind::ItemFn(_, header, _, _) => Some(header),
  38             FnKind::Method(_, sig, _, _) => Some(&sig.header),
  39             FnKind::Closure(_) => None,
  40         }
  41     }
  42 }
  43
  44 /// Each method of the `Visitor` trait is a hook to be potentially
  45 /// overridden. Each method's default implementation recursively visits
  46 /// the substructure of the input via the corresponding `walk` method;
  47 /// e.g., the `visit_mod` method by default calls `visit::walk_mod`.
  48 ///
  49 /// If you want to ensure that your code handles every variant
  50 /// explicitly, you need to override each method. (And you also need
  51 /// to monitor future changes to `Visitor` in case a new method with a
  52 /// new default implementation gets introduced.)
  53 pub trait Visitor<'ast>: Sized {
  54     fn visit_name(&mut self, _span: Span, _name: Name) {
  55         // Nothing to do.
  56     }
  57     fn visit_ident(&mut self, ident: Ident) {
  58         walk_ident(self, ident);
  59     }
  60     fn visit_mod(&mut self, m: &'ast Mod, _s: Span, _attrs: &[Attribute], _n: NodeId) {
  61         walk_mod(self, m);
  62     }
  63     fn visit_foreign_item(&mut self, i: &'ast ForeignItem) {
  64         walk_foreign_item(self, i)
  65     }
  66     fn visit_global_asm(&mut self, ga: &'ast GlobalAsm) {
  67         walk_global_asm(self, ga)
  68     }
  69     fn visit_item(&mut self, i: &'ast Item) {
  70         walk_item(self, i)
  71     }
  72     fn visit_local(&mut self, l: &'ast Local) {
  73         walk_local(self, l)
  74     }
  75     fn visit_block(&mut self, b: &'ast Block) {
  76         walk_block(self, b)
  77     }
  78     fn visit_stmt(&mut self, s: &'ast Stmt) {
  79         walk_stmt(self, s)
  80     }
  81     fn visit_param(&mut self, param: &'ast Param) {
  82         walk_param(self, param)
  83     }
  84     fn visit_arm(&mut self, a: &'ast Arm) {
  85         walk_arm(self, a)
  86     }
  87     fn visit_pat(&mut self, p: &'ast Pat) {
  88         walk_pat(self, p)
  89     }
  90     fn visit_anon_const(&mut self, c: &'ast AnonConst) {
  91         walk_anon_const(self, c)
  92     }
  93     fn visit_expr(&mut self, ex: &'ast Expr) {
  94         walk_expr(self, ex)
  95     }
  96     fn visit_expr_post(&mut self, _ex: &'ast Expr) {}
  97     fn visit_ty(&mut self, t: &'ast Ty) {
  98         walk_ty(self, t)
  99     }
 100     fn visit_generic_param(&mut self, param: &'ast GenericParam) {
 101         walk_generic_param(self, param)
 102     }
 103     fn visit_generics(&mut self, g: &'ast Generics) {
 104         walk_generics(self, g)
 105     }
 106     fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
 107         walk_where_predicate(self, p)
 108     }
 109     fn visit_fn(&mut self, fk: FnKind<'ast>, fd: &'ast FnDecl, s: Span, _: NodeId) {
 110         walk_fn(self, fk, fd, s)
 111     }
 112     fn visit_trait_item(&mut self, i: &'ast AssocItem) {
 113         walk_trait_item(self, i)
 114     }
 115     fn visit_impl_item(&mut self, i: &'ast AssocItem) {
 116         walk_impl_item(self, i)
 117     }
 118     fn visit_assoc_item(&mut self, i: &'ast AssocItem) {
 119         walk_assoc_item(self, i)
 120     }
 121     fn visit_trait_ref(&mut self, t: &'ast TraitRef) {
 122         walk_trait_ref(self, t)
 123     }
 124     fn visit_param_bound(&mut self, bounds: &'ast GenericBound) {
 125         walk_param_bound(self, bounds)
 126     }
 127     fn visit_poly_trait_ref(&mut self, t: &'ast PolyTraitRef, m: &'ast TraitBoundModifier) {
 128         walk_poly_trait_ref(self, t, m)
 129     }
 130     fn visit_variant_data(&mut self, s: &'ast VariantData) {
 131         walk_struct_def(self, s)
 132     }
 133     fn visit_struct_field(&mut self, s: &'ast StructField) {
 134         walk_struct_field(self, s)
 135     }
 136     fn visit_enum_def(
 137         &mut self,
 138         enum_definition: &'ast EnumDef,
 139         generics: &'ast Generics,
 140         item_id: NodeId,
 141         _: Span,
 142     ) {
 143         walk_enum_def(self, enum_definition, generics, item_id)
 144     }
 145     fn visit_variant(&mut self, v: &'ast Variant) {
 146         walk_variant(self, v)
 147     }
 148     fn visit_label(&mut self, label: &'ast Label) {
 149         walk_label(self, label)
 150     }
 151     fn visit_lifetime(&mut self, lifetime: &'ast Lifetime) {
 152         walk_lifetime(self, lifetime)
 153     }
 154     fn visit_mac(&mut self, _mac: &'ast Mac) {
 155         panic!("visit_mac disabled by default");
 156         // N.B., see note about macros above.
 157         // if you really want a visitor that
 158         // works on macros, use this
 159         // definition in your trait impl:
 160         // visit::walk_mac(self, _mac)
 161     }
 162     fn visit_mac_def(&mut self, _mac: &'ast MacroDef, _id: NodeId) {
 163         // Nothing to do
 164     }
 165     fn visit_path(&mut self, path: &'ast Path, _id: NodeId) {
 166         walk_path(self, path)
 167     }
 168     fn visit_use_tree(&mut self, use_tree: &'ast UseTree, id: NodeId, _nested: bool) {
 169         walk_use_tree(self, use_tree, id)
 170     }
 171     fn visit_path_segment(&mut self, path_span: Span, path_segment: &'ast PathSegment) {
 172         walk_path_segment(self, path_span, path_segment)
 173     }
 174     fn visit_generic_args(&mut self, path_span: Span, generic_args: &'ast GenericArgs) {
 175         walk_generic_args(self, path_span, generic_args)
 176     }
 177     fn visit_generic_arg(&mut self, generic_arg: &'ast GenericArg) {
 178         match generic_arg {
 179             GenericArg::Lifetime(lt) => self.visit_lifetime(lt),
 180             GenericArg::Type(ty) => self.visit_ty(ty),
 181             GenericArg::Const(ct) => self.visit_anon_const(ct),
 182         }
 183     }
 184     fn visit_assoc_ty_constraint(&mut self, constraint: &'ast AssocTyConstraint) {
 185         walk_assoc_ty_constraint(self, constraint)
 186     }
 187     fn visit_attribute(&mut self, attr: &'ast Attribute) {
 188         walk_attribute(self, attr)
 189     }
 190     fn visit_tt(&mut self, tt: TokenTree) {
 191         walk_tt(self, tt)
 192     }
 193     fn visit_tts(&mut self, tts: TokenStream) {
 194         walk_tts(self, tts)
 195     }
 196     fn visit_token(&mut self, _t: Token) {}
 197     // FIXME: add `visit_interpolated` and `walk_interpolated`
 198     fn visit_vis(&mut self, vis: &'ast Visibility) {
 199         walk_vis(self, vis)
 200     }
 201     fn visit_fn_ret_ty(&mut self, ret_ty: &'ast FunctionRetTy) {
 202         walk_fn_ret_ty(self, ret_ty)
 203     }
 204     fn visit_fn_header(&mut self, _header: &'ast FnHeader) {
 205         // Nothing to do
 206     }
 207     fn visit_field(&mut self, f: &'ast Field) {
 208         walk_field(self, f)
 209     }
 210     fn visit_field_pattern(&mut self, fp: &'ast FieldPat) {
 211         walk_field_pattern(self, fp)
 212     }
 213 }
 214
 215 #[macro_export]
 216 macro_rules! walk_list {
 217     ($visitor: expr, $method: ident, $list: expr) => {
 218         for elem in $list {
 219             $visitor.$method(elem)
 220         }
 221     };
 222     ($visitor: expr, $method: ident, $list: expr, $($extra_args: expr),*) => {
 223         for elem in $list {
 224             $visitor.$method(elem, $($extra_args,)*)
 225         }
 226     }
 227 }
 228
 229 pub fn walk_ident<'a, V: Visitor<'a>>(visitor: &mut V, ident: Ident) {
 230     visitor.visit_name(ident.span, ident.name);
 231 }
 232
 233 pub fn walk_crate<'a, V: Visitor<'a>>(visitor: &mut V, krate: &'a Crate) {
 234     visitor.visit_mod(&krate.module, krate.span, &krate.attrs, CRATE_NODE_ID);
 235     walk_list!(visitor, visit_attribute, &krate.attrs);
 236 }
 237
 238 pub fn walk_mod<'a, V: Visitor<'a>>(visitor: &mut V, module: &'a Mod) {
 239     walk_list!(visitor, visit_item, &module.items);
 240 }
 241
 242 pub fn walk_local<'a, V: Visitor<'a>>(visitor: &mut V, local: &'a Local) {
 243     for attr in local.attrs.iter() {
 244         visitor.visit_attribute(attr);
 245     }
 246     visitor.visit_pat(&local.pat);
 247     walk_list!(visitor, visit_ty, &local.ty);
 248     walk_list!(visitor, visit_expr, &local.init);
 249 }
 250
 251 pub fn walk_label<'a, V: Visitor<'a>>(visitor: &mut V, label: &'a Label) {
 252     visitor.visit_ident(label.ident);
 253 }
 254
 255 pub fn walk_lifetime<'a, V: Visitor<'a>>(visitor: &mut V, lifetime: &'a Lifetime) {
 256     visitor.visit_ident(lifetime.ident);
 257 }
 258
 259 pub fn walk_poly_trait_ref<'a, V>(
 260     visitor: &mut V,
 261     trait_ref: &'a PolyTraitRef,
 262     _: &TraitBoundModifier,
 263 ) where
 264     V: Visitor<'a>,
 265 {
 266     walk_list!(visitor, visit_generic_param, &trait_ref.bound_generic_params);
 267     visitor.visit_trait_ref(&trait_ref.trait_ref);
 268 }
 269
 270 pub fn walk_trait_ref<'a, V: Visitor<'a>>(visitor: &mut V, trait_ref: &'a TraitRef) {
 271     visitor.visit_path(&trait_ref.path, trait_ref.ref_id)
 272 }
 273
 274 pub fn walk_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a Item) {
 275     visitor.visit_vis(&item.vis);
 276     visitor.visit_ident(item.ident);
 277     match item.kind {
 278         ItemKind::ExternCrate(orig_name) => {
 279             if let Some(orig_name) = orig_name {
 280                 visitor.visit_name(item.span, orig_name);
 281             }
 282         }
 283         ItemKind::Use(ref use_tree) => visitor.visit_use_tree(use_tree, item.id, false),
 284         ItemKind::Static(ref typ, _, ref expr) | ItemKind::Const(ref typ, ref expr) => {
 285             visitor.visit_ty(typ);
 286             visitor.visit_expr(expr);
 287         }
 288         ItemKind::Fn(ref sig, ref generics, ref body) => {
 289             visitor.visit_generics(generics);
 290             visitor.visit_fn_header(&sig.header);
 291             visitor.visit_fn(
 292                 FnKind::ItemFn(item.ident, &sig.header, &item.vis, body),
 293                 &sig.decl,
 294                 item.span,
 295                 item.id,
 296             )
 297         }
 298         ItemKind::Mod(ref module) => visitor.visit_mod(module, item.span, &item.attrs, item.id),
 299         ItemKind::ForeignMod(ref foreign_module) => {
 300             walk_list!(visitor, visit_foreign_item, &foreign_module.items);
 301         }
 302         ItemKind::GlobalAsm(ref ga) => visitor.visit_global_asm(ga),
 303         ItemKind::TyAlias(ref typ, ref generics) => {
 304             visitor.visit_ty(typ);
 305             visitor.visit_generics(generics)
 306         }
 307         ItemKind::Enum(ref enum_definition, ref generics) => {
 308             visitor.visit_generics(generics);
 309             visitor.visit_enum_def(enum_definition, generics, item.id, item.span)
 310         }
 311         ItemKind::Impl {
 312             unsafety: _,
 313             polarity: _,
 314             defaultness: _,
 315             constness: _,
 316             ref generics,
 317             ref of_trait,
 318             ref self_ty,
 319             ref items,
 320         } => {
 321             visitor.visit_generics(generics);
 322             walk_list!(visitor, visit_trait_ref, of_trait);
 323             visitor.visit_ty(self_ty);
 324             walk_list!(visitor, visit_impl_item, items);
 325         }
 326         ItemKind::Struct(ref struct_definition, ref generics)
 327         | ItemKind::Union(ref struct_definition, ref generics) => {
 328             visitor.visit_generics(generics);
 329             visitor.visit_variant_data(struct_definition);
 330         }
 331         ItemKind::Trait(.., ref generics, ref bounds, ref methods) => {
 332             visitor.visit_generics(generics);
 333             walk_list!(visitor, visit_param_bound, bounds);
 334             walk_list!(visitor, visit_trait_item, methods);
 335         }
 336         ItemKind::TraitAlias(ref generics, ref bounds) => {
 337             visitor.visit_generics(generics);
 338             walk_list!(visitor, visit_param_bound, bounds);
 339         }
 340         ItemKind::Mac(ref mac) => visitor.visit_mac(mac),
 341         ItemKind::MacroDef(ref ts) => visitor.visit_mac_def(ts, item.id),
 342     }
 343     walk_list!(visitor, visit_attribute, &item.attrs);
 344 }
 345
 346 pub fn walk_enum_def<'a, V: Visitor<'a>>(
 347     visitor: &mut V,
 348     enum_definition: &'a EnumDef,
 349     _: &'a Generics,
 350     _: NodeId,
 351 ) {
 352     walk_list!(visitor, visit_variant, &enum_definition.variants);
 353 }
 354
 355 pub fn walk_variant<'a, V: Visitor<'a>>(visitor: &mut V, variant: &'a Variant)
 356 where
 357     V: Visitor<'a>,
 358 {
 359     visitor.visit_ident(variant.ident);
 360     visitor.visit_vis(&variant.vis);
 361     visitor.visit_variant_data(&variant.data);
 362     walk_list!(visitor, visit_anon_const, &variant.disr_expr);
 363     walk_list!(visitor, visit_attribute, &variant.attrs);
 364 }
 365
 366 pub fn walk_field<'a, V: Visitor<'a>>(visitor: &mut V, f: &'a Field) {
 367     visitor.visit_expr(&f.expr);
 368     visitor.visit_ident(f.ident);
 369     walk_list!(visitor, visit_attribute, f.attrs.iter());
 370 }
 371
 372 pub fn walk_field_pattern<'a, V: Visitor<'a>>(visitor: &mut V, fp: &'a FieldPat) {
 373     visitor.visit_ident(fp.ident);
 374     visitor.visit_pat(&fp.pat);
 375     walk_list!(visitor, visit_attribute, fp.attrs.iter());
 376 }
 377
 378 pub fn walk_ty<'a, V: Visitor<'a>>(visitor: &mut V, typ: &'a Ty) {
 379     match typ.kind {
 380         TyKind::Slice(ref ty) | TyKind::Paren(ref ty) => visitor.visit_ty(ty),
 381         TyKind::Ptr(ref mutable_type) => visitor.visit_ty(&mutable_type.ty),
 382         TyKind::Rptr(ref opt_lifetime, ref mutable_type) => {
 383             walk_list!(visitor, visit_lifetime, opt_lifetime);
 384             visitor.visit_ty(&mutable_type.ty)
 385         }
 386         TyKind::Tup(ref tuple_element_types) => {
 387             walk_list!(visitor, visit_ty, tuple_element_types);
 388         }
 389         TyKind::BareFn(ref function_declaration) => {
 390             walk_list!(visitor, visit_generic_param, &function_declaration.generic_params);
 391             walk_fn_decl(visitor, &function_declaration.decl);
 392         }
 393         TyKind::Path(ref maybe_qself, ref path) => {
 394             if let Some(ref qself) = *maybe_qself {
 395                 visitor.visit_ty(&qself.ty);
 396             }
 397             visitor.visit_path(path, typ.id);
 398         }
 399         TyKind::Array(ref ty, ref length) => {
 400             visitor.visit_ty(ty);
 401             visitor.visit_anon_const(length)
 402         }
 403         TyKind::TraitObject(ref bounds, ..) | TyKind::ImplTrait(_, ref bounds) => {
 404             walk_list!(visitor, visit_param_bound, bounds);
 405         }
 406         TyKind::Typeof(ref expression) => visitor.visit_anon_const(expression),
 407         TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err => {}
 408         TyKind::Mac(ref mac) => visitor.visit_mac(mac),
 409         TyKind::Never | TyKind::CVarArgs => {}
 410     }
 411 }
 412
 413 pub fn walk_path<'a, V: Visitor<'a>>(visitor: &mut V, path: &'a Path) {
 414     for segment in &path.segments {
 415         visitor.visit_path_segment(path.span, segment);
 416     }
 417 }
 418
 419 pub fn walk_use_tree<'a, V: Visitor<'a>>(visitor: &mut V, use_tree: &'a UseTree, id: NodeId) {
 420     visitor.visit_path(&use_tree.prefix, id);
 421     match use_tree.kind {
 422         UseTreeKind::Simple(rename, ..) => {
 423             // The extra IDs are handled during HIR lowering.
 424             if let Some(rename) = rename {
 425                 visitor.visit_ident(rename);
 426             }
 427         }
 428         UseTreeKind::Glob => {}
 429         UseTreeKind::Nested(ref use_trees) => {
 430             for &(ref nested_tree, nested_id) in use_trees {
 431                 visitor.visit_use_tree(nested_tree, nested_id, true);
 432             }
 433         }
 434     }
 435 }
 436
 437 pub fn walk_path_segment<'a, V: Visitor<'a>>(
 438     visitor: &mut V,
 439     path_span: Span,
 440     segment: &'a PathSegment,
 441 ) {
 442     visitor.visit_ident(segment.ident);
 443     if let Some(ref args) = segment.args {
 444         visitor.visit_generic_args(path_span, args);
 445     }
 446 }
 447
 448 pub fn walk_generic_args<'a, V>(visitor: &mut V, _path_span: Span, generic_args: &'a GenericArgs)
 449 where
 450     V: Visitor<'a>,
 451 {
 452     match *generic_args {
 453         GenericArgs::AngleBracketed(ref data) => {
 454             walk_list!(visitor, visit_generic_arg, &data.args);
 455             walk_list!(visitor, visit_assoc_ty_constraint, &data.constraints);
 456         }
 457         GenericArgs::Parenthesized(ref data) => {
 458             walk_list!(visitor, visit_ty, &data.inputs);
 459             walk_fn_ret_ty(visitor, &data.output);
 460         }
 461     }
 462 }
 463
 464 pub fn walk_assoc_ty_constraint<'a, V: Visitor<'a>>(
 465     visitor: &mut V,
 466     constraint: &'a AssocTyConstraint,
 467 ) {
 468     visitor.visit_ident(constraint.ident);
 469     match constraint.kind {
 470         AssocTyConstraintKind::Equality { ref ty } => {
 471             visitor.visit_ty(ty);
 472         }
 473         AssocTyConstraintKind::Bound { ref bounds } => {
 474             walk_list!(visitor, visit_param_bound, bounds);
 475         }
 476     }
 477 }
 478
 479 pub fn walk_pat<'a, V: Visitor<'a>>(visitor: &mut V, pattern: &'a Pat) {
 480     match pattern.kind {
 481         PatKind::TupleStruct(ref path, ref elems) => {
 482             visitor.visit_path(path, pattern.id);
 483             walk_list!(visitor, visit_pat, elems);
 484         }
 485         PatKind::Path(ref opt_qself, ref path) => {
 486             if let Some(ref qself) = *opt_qself {
 487                 visitor.visit_ty(&qself.ty);
 488             }
 489             visitor.visit_path(path, pattern.id)
 490         }
 491         PatKind::Struct(ref path, ref fields, _) => {
 492             visitor.visit_path(path, pattern.id);
 493             walk_list!(visitor, visit_field_pattern, fields);
 494         }
 495         PatKind::Box(ref subpattern)
 496         | PatKind::Ref(ref subpattern, _)
 497         | PatKind::Paren(ref subpattern) => visitor.visit_pat(subpattern),
 498         PatKind::Ident(_, ident, ref optional_subpattern) => {
 499             visitor.visit_ident(ident);
 500             walk_list!(visitor, visit_pat, optional_subpattern);
 501         }
 502         PatKind::Lit(ref expression) => visitor.visit_expr(expression),
 503         PatKind::Range(ref lower_bound, ref upper_bound, _) => {
 504             walk_list!(visitor, visit_expr, lower_bound);
 505             walk_list!(visitor, visit_expr, upper_bound);
 506         }
 507         PatKind::Wild | PatKind::Rest => {}
 508         PatKind::Tuple(ref elems) | PatKind::Slice(ref elems) | PatKind::Or(ref elems) => {
 509             walk_list!(visitor, visit_pat, elems);
 510         }
 511         PatKind::Mac(ref mac) => visitor.visit_mac(mac),
 512     }
 513 }
 514
 515 pub fn walk_foreign_item<'a, V: Visitor<'a>>(visitor: &mut V, foreign_item: &'a ForeignItem) {
 516     visitor.visit_vis(&foreign_item.vis);
 517     visitor.visit_ident(foreign_item.ident);
 518
 519     match foreign_item.kind {
 520         ForeignItemKind::Fn(ref function_declaration, ref generics) => {
 521             walk_fn_decl(visitor, function_declaration);
 522             visitor.visit_generics(generics)
 523         }
 524         ForeignItemKind::Static(ref typ, _) => visitor.visit_ty(typ),
 525         ForeignItemKind::Ty => (),
 526         ForeignItemKind::Macro(ref mac) => visitor.visit_mac(mac),
 527     }
 528
 529     walk_list!(visitor, visit_attribute, &foreign_item.attrs);
 530 }
 531
 532 pub fn walk_global_asm<'a, V: Visitor<'a>>(_: &mut V, _: &'a GlobalAsm) {
 533     // Empty!
 534 }
 535
 536 pub fn walk_param_bound<'a, V: Visitor<'a>>(visitor: &mut V, bound: &'a GenericBound) {
 537     match *bound {
 538         GenericBound::Trait(ref typ, ref modifier) => visitor.visit_poly_trait_ref(typ, modifier),
 539         GenericBound::Outlives(ref lifetime) => visitor.visit_lifetime(lifetime),
 540     }
 541 }
 542
 543 pub fn walk_generic_param<'a, V: Visitor<'a>>(visitor: &mut V, param: &'a GenericParam) {
 544     visitor.visit_ident(param.ident);
 545     walk_list!(visitor, visit_attribute, param.attrs.iter());
 546     walk_list!(visitor, visit_param_bound, &param.bounds);
 547     match param.kind {
 548         GenericParamKind::Lifetime => (),
 549         GenericParamKind::Type { ref default } => walk_list!(visitor, visit_ty, default),
 550         GenericParamKind::Const { ref ty, .. } => visitor.visit_ty(ty),
 551     }
 552 }
 553
 554 pub fn walk_generics<'a, V: Visitor<'a>>(visitor: &mut V, generics: &'a Generics) {
 555     walk_list!(visitor, visit_generic_param, &generics.params);
 556     walk_list!(visitor, visit_where_predicate, &generics.where_clause.predicates);
 557 }
 558
 559 pub fn walk_where_predicate<'a, V: Visitor<'a>>(visitor: &mut V, predicate: &'a WherePredicate) {
 560     match *predicate {
 561         WherePredicate::BoundPredicate(WhereBoundPredicate {
 562             ref bounded_ty,
 563             ref bounds,
 564             ref bound_generic_params,
 565             ..
 566         }) => {
 567             visitor.visit_ty(bounded_ty);
 568             walk_list!(visitor, visit_param_bound, bounds);
 569             walk_list!(visitor, visit_generic_param, bound_generic_params);
 570         }
 571         WherePredicate::RegionPredicate(WhereRegionPredicate {
 572             ref lifetime, ref bounds, ..
 573         }) => {
 574             visitor.visit_lifetime(lifetime);
 575             walk_list!(visitor, visit_param_bound, bounds);
 576         }
 577         WherePredicate::EqPredicate(WhereEqPredicate { ref lhs_ty, ref rhs_ty, .. }) => {
 578             visitor.visit_ty(lhs_ty);
 579             visitor.visit_ty(rhs_ty);
 580         }
 581     }
 582 }
 583
 584 pub fn walk_fn_ret_ty<'a, V: Visitor<'a>>(visitor: &mut V, ret_ty: &'a FunctionRetTy) {
 585     if let FunctionRetTy::Ty(ref output_ty) = *ret_ty {
 586         visitor.visit_ty(output_ty)
 587     }
 588 }
 589
 590 pub fn walk_fn_decl<'a, V: Visitor<'a>>(visitor: &mut V, function_declaration: &'a FnDecl) {
 591     for param in &function_declaration.inputs {
 592         visitor.visit_param(param);
 593     }
 594     visitor.visit_fn_ret_ty(&function_declaration.output);
 595 }
 596
 597 pub fn walk_fn<'a, V>(visitor: &mut V, kind: FnKind<'a>, declaration: &'a FnDecl, _span: Span)
 598 where
 599     V: Visitor<'a>,
 600 {
 601     match kind {
 602         FnKind::ItemFn(_, header, _, body) => {
 603             visitor.visit_fn_header(header);
 604             walk_fn_decl(visitor, declaration);
 605             visitor.visit_block(body);
 606         }
 607         FnKind::Method(_, sig, _, body) => {
 608             visitor.visit_fn_header(&sig.header);
 609             walk_fn_decl(visitor, declaration);
 610             visitor.visit_block(body);
 611         }
 612         FnKind::Closure(body) => {
 613             walk_fn_decl(visitor, declaration);
 614             visitor.visit_expr(body);
 615         }
 616     }
 617 }
 618
 619 pub fn walk_impl_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a AssocItem) {
 620     visitor.visit_assoc_item(item);
 621 }
 622
 623 pub fn walk_trait_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a AssocItem) {
 624     visitor.visit_assoc_item(item);
 625 }
 626
 627 pub fn walk_assoc_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a AssocItem) {
 628     visitor.visit_vis(&item.vis);
 629     visitor.visit_ident(item.ident);
 630     walk_list!(visitor, visit_attribute, &item.attrs);
 631     visitor.visit_generics(&item.generics);
 632     match item.kind {
 633         AssocItemKind::Const(ref ty, ref expr) => {
 634             visitor.visit_ty(ty);
 635             walk_list!(visitor, visit_expr, expr);
 636         }
 637         AssocItemKind::Fn(ref sig, None) => {
 638             visitor.visit_fn_header(&sig.header);
 639             walk_fn_decl(visitor, &sig.decl);
 640         }
 641         AssocItemKind::Fn(ref sig, Some(ref body)) => {
 642             visitor.visit_fn(
 643                 FnKind::Method(item.ident, sig, &item.vis, body),
 644                 &sig.decl,
 645                 item.span,
 646                 item.id,
 647             );
 648         }
 649         AssocItemKind::TyAlias(ref bounds, ref ty) => {
 650             walk_list!(visitor, visit_param_bound, bounds);
 651             walk_list!(visitor, visit_ty, ty);
 652         }
 653         AssocItemKind::Macro(ref mac) => {
 654             visitor.visit_mac(mac);
 655         }
 656     }
 657 }
 658
 659 pub fn walk_struct_def<'a, V: Visitor<'a>>(visitor: &mut V, struct_definition: &'a VariantData) {
 660     walk_list!(visitor, visit_struct_field, struct_definition.fields());
 661 }
 662
 663 pub fn walk_struct_field<'a, V: Visitor<'a>>(visitor: &mut V, struct_field: &'a StructField) {
 664     visitor.visit_vis(&struct_field.vis);
 665     if let Some(ident) = struct_field.ident {
 666         visitor.visit_ident(ident);
 667     }
 668     visitor.visit_ty(&struct_field.ty);
 669     walk_list!(visitor, visit_attribute, &struct_field.attrs);
 670 }
 671
 672 pub fn walk_block<'a, V: Visitor<'a>>(visitor: &mut V, block: &'a Block) {
 673     walk_list!(visitor, visit_stmt, &block.stmts);
 674 }
 675
 676 pub fn walk_stmt<'a, V: Visitor<'a>>(visitor: &mut V, statement: &'a Stmt) {
 677     match statement.kind {
 678         StmtKind::Local(ref local) => visitor.visit_local(local),
 679         StmtKind::Item(ref item) => visitor.visit_item(item),
 680         StmtKind::Expr(ref expression) | StmtKind::Semi(ref expression) => {
 681             visitor.visit_expr(expression)
 682         }
 683         StmtKind::Mac(ref mac) => {
 684             let (ref mac, _, ref attrs) = **mac;
 685             visitor.visit_mac(mac);
 686             for attr in attrs.iter() {
 687                 visitor.visit_attribute(attr);
 688             }
 689         }
 690     }
 691 }
 692
 693 pub fn walk_mac<'a, V: Visitor<'a>>(visitor: &mut V, mac: &'a Mac) {
 694     visitor.visit_path(&mac.path, DUMMY_NODE_ID);
 695 }
 696
 697 pub fn walk_anon_const<'a, V: Visitor<'a>>(visitor: &mut V, constant: &'a AnonConst) {
 698     visitor.visit_expr(&constant.value);
 699 }
 700
 701 pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
 702     walk_list!(visitor, visit_attribute, expression.attrs.iter());
 703
 704     match expression.kind {
 705         ExprKind::Box(ref subexpression) => visitor.visit_expr(subexpression),
 706         ExprKind::Array(ref subexpressions) => {
 707             walk_list!(visitor, visit_expr, subexpressions);
 708         }
 709         ExprKind::Repeat(ref element, ref count) => {
 710             visitor.visit_expr(element);
 711             visitor.visit_anon_const(count)
 712         }
 713         ExprKind::Struct(ref path, ref fields, ref optional_base) => {
 714             visitor.visit_path(path, expression.id);
 715             walk_list!(visitor, visit_field, fields);
 716             walk_list!(visitor, visit_expr, optional_base);
 717         }
 718         ExprKind::Tup(ref subexpressions) => {
 719             walk_list!(visitor, visit_expr, subexpressions);
 720         }
 721         ExprKind::Call(ref callee_expression, ref arguments) => {
 722             visitor.visit_expr(callee_expression);
 723             walk_list!(visitor, visit_expr, arguments);
 724         }
 725         ExprKind::MethodCall(ref segment, ref arguments) => {
 726             visitor.visit_path_segment(expression.span, segment);
 727             walk_list!(visitor, visit_expr, arguments);
 728         }
 729         ExprKind::Binary(_, ref left_expression, ref right_expression) => {
 730             visitor.visit_expr(left_expression);
 731             visitor.visit_expr(right_expression)
 732         }
 733         ExprKind::AddrOf(_, _, ref subexpression) | ExprKind::Unary(_, ref subexpression) => {
 734             visitor.visit_expr(subexpression)
 735         }
 736         ExprKind::Cast(ref subexpression, ref typ) | ExprKind::Type(ref subexpression, ref typ) => {
 737             visitor.visit_expr(subexpression);
 738             visitor.visit_ty(typ)
 739         }
 740         ExprKind::Let(ref pat, ref scrutinee) => {
 741             visitor.visit_pat(pat);
 742             visitor.visit_expr(scrutinee);
 743         }
 744         ExprKind::If(ref head_expression, ref if_block, ref optional_else) => {
 745             visitor.visit_expr(head_expression);
 746             visitor.visit_block(if_block);
 747             walk_list!(visitor, visit_expr, optional_else);
 748         }
 749         ExprKind::While(ref subexpression, ref block, ref opt_label) => {
 750             walk_list!(visitor, visit_label, opt_label);
 751             visitor.visit_expr(subexpression);
 752             visitor.visit_block(block);
 753         }
 754         ExprKind::ForLoop(ref pattern, ref subexpression, ref block, ref opt_label) => {
 755             walk_list!(visitor, visit_label, opt_label);
 756             visitor.visit_pat(pattern);
 757             visitor.visit_expr(subexpression);
 758             visitor.visit_block(block);
 759         }
 760         ExprKind::Loop(ref block, ref opt_label) => {
 761             walk_list!(visitor, visit_label, opt_label);
 762             visitor.visit_block(block);
 763         }
 764         ExprKind::Match(ref subexpression, ref arms) => {
 765             visitor.visit_expr(subexpression);
 766             walk_list!(visitor, visit_arm, arms);
 767         }
 768         ExprKind::Closure(_, _, _, ref function_declaration, ref body, _decl_span) => visitor
 769             .visit_fn(FnKind::Closure(body), function_declaration, expression.span, expression.id),
 770         ExprKind::Block(ref block, ref opt_label) => {
 771             walk_list!(visitor, visit_label, opt_label);
 772             visitor.visit_block(block);
 773         }
 774         ExprKind::Async(_, _, ref body) => {
 775             visitor.visit_block(body);
 776         }
 777         ExprKind::Await(ref expr) => visitor.visit_expr(expr),
 778         ExprKind::Assign(ref lhs, ref rhs, _) => {
 779             visitor.visit_expr(lhs);
 780             visitor.visit_expr(rhs);
 781         }
 782         ExprKind::AssignOp(_, ref left_expression, ref right_expression) => {
 783             visitor.visit_expr(left_expression);
 784             visitor.visit_expr(right_expression);
 785         }
 786         ExprKind::Field(ref subexpression, ident) => {
 787             visitor.visit_expr(subexpression);
 788             visitor.visit_ident(ident);
 789         }
 790         ExprKind::Index(ref main_expression, ref index_expression) => {
 791             visitor.visit_expr(main_expression);
 792             visitor.visit_expr(index_expression)
 793         }
 794         ExprKind::Range(ref start, ref end, _) => {
 795             walk_list!(visitor, visit_expr, start);
 796             walk_list!(visitor, visit_expr, end);
 797         }
 798         ExprKind::Path(ref maybe_qself, ref path) => {
 799             if let Some(ref qself) = *maybe_qself {
 800                 visitor.visit_ty(&qself.ty);
 801             }
 802             visitor.visit_path(path, expression.id)
 803         }
 804         ExprKind::Break(ref opt_label, ref opt_expr) => {
 805             walk_list!(visitor, visit_label, opt_label);
 806             walk_list!(visitor, visit_expr, opt_expr);
 807         }
 808         ExprKind::Continue(ref opt_label) => {
 809             walk_list!(visitor, visit_label, opt_label);
 810         }
 811         ExprKind::Ret(ref optional_expression) => {
 812             walk_list!(visitor, visit_expr, optional_expression);
 813         }
 814         ExprKind::Mac(ref mac) => visitor.visit_mac(mac),
 815         ExprKind::Paren(ref subexpression) => visitor.visit_expr(subexpression),
 816         ExprKind::InlineAsm(ref ia) => {
 817             for &(_, ref input) in &ia.inputs {
 818                 visitor.visit_expr(input)
 819             }
 820             for output in &ia.outputs {
 821                 visitor.visit_expr(&output.expr)
 822             }
 823         }
 824         ExprKind::Yield(ref optional_expression) => {
 825             walk_list!(visitor, visit_expr, optional_expression);
 826         }
 827         ExprKind::Try(ref subexpression) => visitor.visit_expr(subexpression),
 828         ExprKind::TryBlock(ref body) => visitor.visit_block(body),
 829         ExprKind::Lit(_) | ExprKind::Err => {}
 830     }
 831
 832     visitor.visit_expr_post(expression)
 833 }
 834
 835 pub fn walk_param<'a, V: Visitor<'a>>(visitor: &mut V, param: &'a Param) {
 836     walk_list!(visitor, visit_attribute, param.attrs.iter());
 837     visitor.visit_pat(&param.pat);
 838     visitor.visit_ty(&param.ty);
 839 }
 840
 841 pub fn walk_arm<'a, V: Visitor<'a>>(visitor: &mut V, arm: &'a Arm) {
 842     visitor.visit_pat(&arm.pat);
 843     walk_list!(visitor, visit_expr, &arm.guard);
 844     visitor.visit_expr(&arm.body);
 845     walk_list!(visitor, visit_attribute, &arm.attrs);
 846 }
 847
 848 pub fn walk_vis<'a, V: Visitor<'a>>(visitor: &mut V, vis: &'a Visibility) {
 849     if let VisibilityKind::Restricted { ref path, id } = vis.node {
 850         visitor.visit_path(path, id);
 851     }
 852 }
 853
 854 pub fn walk_attribute<'a, V: Visitor<'a>>(visitor: &mut V, attr: &'a Attribute) {
 855     match attr.kind {
 856         AttrKind::Normal(ref item) => walk_mac_args(visitor, &item.args),
 857         AttrKind::DocComment(_) => {}
 858     }
 859 }
 860
 861 pub fn walk_mac_args<'a, V: Visitor<'a>>(visitor: &mut V, args: &'a MacArgs) {
 862     match args {
 863         MacArgs::Empty => {}
 864         MacArgs::Delimited(_dspan, _delim, tokens) => visitor.visit_tts(tokens.clone()),
 865         MacArgs::Eq(_eq_span, tokens) => visitor.visit_tts(tokens.clone()),
 866     }
 867 }
 868
 869 pub fn walk_tt<'a, V: Visitor<'a>>(visitor: &mut V, tt: TokenTree) {
 870     match tt {
 871         TokenTree::Token(token) => visitor.visit_token(token),
 872         TokenTree::Delimited(_, _, tts) => visitor.visit_tts(tts),
 873     }
 874 }
 875
 876 pub fn walk_tts<'a, V: Visitor<'a>>(visitor: &mut V, tts: TokenStream) {
 877     for tt in tts.trees() {
 878         visitor.visit_tt(tt);
 879     }
 880 }