1 //! "Late resolution" is the pass that resolves most of names in a crate beside imports and macros.
2 //! It runs when the crate is fully expanded and its module structure is fully built.
3 //! So it just walks through the crate and resolves all the expressions, types, etc.
5 //! If you wonder why there's no `early.rs`, that's because it's split into three files -
6 //! `build_reduced_graph.rs`, `macros.rs` and `imports.rs`.
10 use crate::{path_names_to_string, BindingError, CrateLint, LexicalScopeBinding};
11 use crate::{Module, ModuleOrUniformRoot, NameBindingKind, ParentScope, PathResult};
12 use crate::{ResolutionError, Resolver, Segment, UseError};
14 use rustc_ast::ast::*;
15 use rustc_ast::ptr::P;
16 use rustc_ast::util::lev_distance::find_best_match_for_name;
17 use rustc_ast::visit::{self, AssocCtxt, FnCtxt, FnKind, Visitor};
18 use rustc_ast::{unwrap_or, walk_list};
19 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
20 use rustc_errors::DiagnosticId;
21 use rustc_hir::def::Namespace::{self, *};
22 use rustc_hir::def::{self, CtorKind, DefKind, PartialRes, PerNS};
23 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
24 use rustc_hir::TraitCandidate;
25 use rustc_middle::{bug, span_bug};
26 use rustc_session::lint;
27 use rustc_span::symbol::{kw, sym, Ident, Symbol};
29 use smallvec::{smallvec, SmallVec};
32 use rustc_span::source_map::{respan, Spanned};
33 use std::collections::BTreeSet;
34 use std::mem::{replace, take};
39 type Res = def::Res<NodeId>;
41 type IdentMap<T> = FxHashMap<Ident, T>;
43 /// Map from the name in a pattern to its binding mode.
44 type BindingMap = IdentMap<BindingInfo>;
46 #[derive(Copy, Clone, Debug)]
49 binding_mode: BindingMode,
52 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
61 fn descr(self) -> &'static str {
63 PatternSource::Match => "match binding",
64 PatternSource::Let => "let binding",
65 PatternSource::For => "for binding",
66 PatternSource::FnParam => "function parameter",
71 /// Denotes whether the context for the set of already bound bindings is a `Product`
72 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
73 /// See those functions for more information.
76 /// A product pattern context, e.g., `Variant(a, b)`.
78 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
82 /// Does this the item (from the item rib scope) allow generic parameters?
83 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
84 crate enum HasGenericParams {
89 /// The rib kind restricts certain accesses,
90 /// e.g. to a `Res::Local` of an outer item.
91 #[derive(Copy, Clone, Debug)]
92 crate enum RibKind<'a> {
93 /// No restriction needs to be applied.
96 /// We passed through an impl or trait and are now in one of its
97 /// methods or associated types. Allow references to ty params that impl or trait
98 /// binds. Disallow any other upvars (including other ty params that are
102 /// We passed through a function definition. Disallow upvars.
103 /// Permit only those const parameters that are specified in the function's generics.
106 /// We passed through an item scope. Disallow upvars.
107 ItemRibKind(HasGenericParams),
109 /// We're in a constant item. Can't refer to dynamic stuff.
112 /// We passed through a module.
113 ModuleRibKind(Module<'a>),
115 /// We passed through a `macro_rules!` statement
116 MacroDefinition(DefId),
118 /// All bindings in this rib are type parameters that can't be used
119 /// from the default of a type parameter because they're not declared
120 /// before said type parameter. Also see the `visit_generics` override.
121 ForwardTyParamBanRibKind,
125 // Whether this rib kind contains generic parameters, as opposed to local
127 crate fn contains_params(&self) -> bool {
129 NormalRibKind | FnItemRibKind | ConstantItemRibKind | ModuleRibKind(_)
130 | MacroDefinition(_) => false,
131 AssocItemRibKind | ItemRibKind(_) | ForwardTyParamBanRibKind => true,
136 /// A single local scope.
138 /// A rib represents a scope names can live in. Note that these appear in many places, not just
139 /// around braces. At any place where the list of accessible names (of the given namespace)
140 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
141 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
144 /// Different [rib kinds](enum.RibKind) are transparent for different names.
146 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
147 /// resolving, the name is looked up from inside out.
149 crate struct Rib<'a, R = Res> {
150 pub bindings: IdentMap<R>,
151 pub kind: RibKind<'a>,
154 impl<'a, R> Rib<'a, R> {
155 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
156 Rib { bindings: Default::default(), kind }
160 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
161 crate enum AliasPossibility {
166 #[derive(Copy, Clone, Debug)]
167 crate enum PathSource<'a> {
168 // Type paths `Path`.
170 // Trait paths in bounds or impls.
171 Trait(AliasPossibility),
172 // Expression paths `path`, with optional parent context.
173 Expr(Option<&'a Expr>),
174 // Paths in path patterns `Path`.
176 // Paths in struct expressions and patterns `Path { .. }`.
178 // Paths in tuple struct patterns `Path(..)`.
180 // `m::A::B` in `<T as m::A>::B::C`.
181 TraitItem(Namespace),
184 impl<'a> PathSource<'a> {
185 fn namespace(self) -> Namespace {
187 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
188 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct => ValueNS,
189 PathSource::TraitItem(ns) => ns,
193 fn defer_to_typeck(self) -> bool {
196 | PathSource::Expr(..)
199 | PathSource::TupleStruct => true,
200 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
204 fn descr_expected(self) -> &'static str {
206 PathSource::Type => "type",
207 PathSource::Trait(_) => "trait",
208 PathSource::Pat => "unit struct, unit variant or constant",
209 PathSource::Struct => "struct, variant or union type",
210 PathSource::TupleStruct => "tuple struct or tuple variant",
211 PathSource::TraitItem(ns) => match ns {
212 TypeNS => "associated type",
213 ValueNS => "method or associated constant",
214 MacroNS => bug!("associated macro"),
216 PathSource::Expr(parent) => match &parent.as_ref().map(|p| &p.kind) {
217 // "function" here means "anything callable" rather than `DefKind::Fn`,
218 // this is not precise but usually more helpful than just "value".
219 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
220 ExprKind::Path(_, path) => {
221 let mut msg = "function";
222 if let Some(segment) = path.segments.iter().last() {
223 if let Some(c) = segment.ident.to_string().chars().next() {
224 if c.is_uppercase() {
225 msg = "function, tuple struct or tuple variant";
238 fn is_call(self) -> bool {
240 PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })) => true,
245 crate fn is_expected(self, res: Res) -> bool {
247 PathSource::Type => match res {
253 | DefKind::TraitAlias
258 | DefKind::ForeignTy,
262 | Res::SelfTy(..) => true,
265 PathSource::Trait(AliasPossibility::No) => match res {
266 Res::Def(DefKind::Trait, _) => true,
269 PathSource::Trait(AliasPossibility::Maybe) => match res {
270 Res::Def(DefKind::Trait | DefKind::TraitAlias, _) => true,
273 PathSource::Expr(..) => match res {
275 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
280 | DefKind::AssocConst
281 | DefKind::ConstParam,
285 | Res::SelfCtor(..) => true,
288 PathSource::Pat => match res {
290 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::AssocConst,
293 | Res::SelfCtor(..) => true,
296 PathSource::TupleStruct => match res {
297 Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) | Res::SelfCtor(..) => true,
300 PathSource::Struct => match res {
309 | Res::SelfTy(..) => true,
312 PathSource::TraitItem(ns) => match res {
313 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
314 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
320 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
321 use rustc_errors::error_code;
322 match (self, has_unexpected_resolution) {
323 (PathSource::Trait(_), true) => error_code!(E0404),
324 (PathSource::Trait(_), false) => error_code!(E0405),
325 (PathSource::Type, true) => error_code!(E0573),
326 (PathSource::Type, false) => error_code!(E0412),
327 (PathSource::Struct, true) => error_code!(E0574),
328 (PathSource::Struct, false) => error_code!(E0422),
329 (PathSource::Expr(..), true) => error_code!(E0423),
330 (PathSource::Expr(..), false) => error_code!(E0425),
331 (PathSource::Pat | PathSource::TupleStruct, true) => error_code!(E0532),
332 (PathSource::Pat | PathSource::TupleStruct, false) => error_code!(E0531),
333 (PathSource::TraitItem(..), true) => error_code!(E0575),
334 (PathSource::TraitItem(..), false) => error_code!(E0576),
340 struct DiagnosticMetadata<'ast> {
341 /// The current trait's associated types' ident, used for diagnostic suggestions.
342 current_trait_assoc_types: Vec<Ident>,
344 /// The current self type if inside an impl (used for better errors).
345 current_self_type: Option<Ty>,
347 /// The current self item if inside an ADT (used for better errors).
348 current_self_item: Option<NodeId>,
350 /// The current trait (used to suggest).
351 current_item: Option<&'ast Item>,
353 /// When processing generics and encountering a type not found, suggest introducing a type
355 currently_processing_generics: bool,
357 /// The current enclosing function (used for better errors).
358 current_function: Option<(FnKind<'ast>, Span)>,
360 /// A list of labels as of yet unused. Labels will be removed from this map when
361 /// they are used (in a `break` or `continue` statement)
362 unused_labels: FxHashMap<NodeId, Span>,
364 /// Only used for better errors on `fn(): fn()`.
365 current_type_ascription: Vec<Span>,
367 /// Only used for better errors on `let <pat>: <expr, not type>;`.
368 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
371 struct LateResolutionVisitor<'a, 'b, 'ast> {
372 r: &'b mut Resolver<'a>,
374 /// The module that represents the current item scope.
375 parent_scope: ParentScope<'a>,
377 /// The current set of local scopes for types and values.
378 /// FIXME #4948: Reuse ribs to avoid allocation.
379 ribs: PerNS<Vec<Rib<'a>>>,
381 /// The current set of local scopes, for labels.
382 label_ribs: Vec<Rib<'a, NodeId>>,
384 /// The trait that the current context can refer to.
385 current_trait_ref: Option<(Module<'a>, TraitRef)>,
387 /// Fields used to add information to diagnostic errors.
388 diagnostic_metadata: DiagnosticMetadata<'ast>,
391 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
392 impl<'a, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
393 fn visit_item(&mut self, item: &'ast Item) {
394 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
395 self.resolve_item(item);
396 self.diagnostic_metadata.current_item = prev;
398 fn visit_arm(&mut self, arm: &'ast Arm) {
399 self.resolve_arm(arm);
401 fn visit_block(&mut self, block: &'ast Block) {
402 self.resolve_block(block);
404 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
405 debug!("visit_anon_const {:?}", constant);
406 self.with_constant_rib(|this| {
407 visit::walk_anon_const(this, constant);
410 fn visit_expr(&mut self, expr: &'ast Expr) {
411 self.resolve_expr(expr, None);
413 fn visit_local(&mut self, local: &'ast Local) {
414 let local_spans = match local.pat.kind {
415 // We check for this to avoid tuple struct fields.
416 PatKind::Wild => None,
419 local.ty.as_ref().map(|ty| ty.span),
420 local.init.as_ref().map(|init| init.span),
423 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
424 self.resolve_local(local);
425 self.diagnostic_metadata.current_let_binding = original;
427 fn visit_ty(&mut self, ty: &'ast Ty) {
429 TyKind::Path(ref qself, ref path) => {
430 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
432 TyKind::ImplicitSelf => {
433 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
435 .resolve_ident_in_lexical_scope(self_ty, TypeNS, Some(ty.id), ty.span)
436 .map_or(Res::Err, |d| d.res());
437 self.r.record_partial_res(ty.id, PartialRes::new(res));
441 visit::walk_ty(self, ty);
443 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef, m: &'ast TraitBoundModifier) {
444 self.smart_resolve_path(
445 tref.trait_ref.ref_id,
447 &tref.trait_ref.path,
448 PathSource::Trait(AliasPossibility::Maybe),
450 visit::walk_poly_trait_ref(self, tref, m);
452 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
453 match foreign_item.kind {
454 ForeignItemKind::Fn(_, _, ref generics, _)
455 | ForeignItemKind::TyAlias(_, ref generics, ..) => {
456 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
457 visit::walk_foreign_item(this, foreign_item);
460 ForeignItemKind::Static(..) => {
461 self.with_item_rib(HasGenericParams::No, |this| {
462 visit::walk_foreign_item(this, foreign_item);
465 ForeignItemKind::MacCall(..) => {
466 visit::walk_foreign_item(self, foreign_item);
470 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, _: NodeId) {
471 let rib_kind = match fn_kind {
472 // Bail if there's no body.
473 FnKind::Fn(.., None) => return visit::walk_fn(self, fn_kind, sp),
474 FnKind::Fn(FnCtxt::Free | FnCtxt::Foreign, ..) => FnItemRibKind,
475 FnKind::Fn(FnCtxt::Assoc(_), ..) | FnKind::Closure(..) => NormalRibKind,
478 replace(&mut self.diagnostic_metadata.current_function, Some((fn_kind, sp)));
479 debug!("(resolving function) entering function");
480 let declaration = fn_kind.decl();
482 // Create a value rib for the function.
483 self.with_rib(ValueNS, rib_kind, |this| {
484 // Create a label rib for the function.
485 this.with_label_rib(rib_kind, |this| {
486 // Add each argument to the rib.
487 this.resolve_params(&declaration.inputs);
489 visit::walk_fn_ret_ty(this, &declaration.output);
491 // Resolve the function body, potentially inside the body of an async closure
493 FnKind::Fn(.., body) => walk_list!(this, visit_block, body),
494 FnKind::Closure(_, body) => this.visit_expr(body),
497 debug!("(resolving function) leaving function");
500 self.diagnostic_metadata.current_function = previous_value;
503 fn visit_generics(&mut self, generics: &'ast Generics) {
504 // For type parameter defaults, we have to ban access
505 // to following type parameters, as the InternalSubsts can only
506 // provide previous type parameters as they're built. We
507 // put all the parameters on the ban list and then remove
508 // them one by one as they are processed and become available.
509 let mut default_ban_rib = Rib::new(ForwardTyParamBanRibKind);
510 let mut found_default = false;
511 default_ban_rib.bindings.extend(generics.params.iter().filter_map(
512 |param| match param.kind {
513 GenericParamKind::Const { .. } | GenericParamKind::Lifetime { .. } => None,
514 GenericParamKind::Type { ref default, .. } => {
515 found_default |= default.is_some();
516 found_default.then_some((Ident::with_dummy_span(param.ident.name), Res::Err))
521 // rust-lang/rust#61631: The type `Self` is essentially
522 // another type parameter. For ADTs, we consider it
523 // well-defined only after all of the ADT type parameters have
524 // been provided. Therefore, we do not allow use of `Self`
525 // anywhere in ADT type parameter defaults.
527 // (We however cannot ban `Self` for defaults on *all* generic
528 // lists; e.g. trait generics can usefully refer to `Self`,
529 // such as in the case of `trait Add<Rhs = Self>`.)
530 if self.diagnostic_metadata.current_self_item.is_some() {
531 // (`Some` if + only if we are in ADT's generics.)
532 default_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
535 for param in &generics.params {
537 GenericParamKind::Lifetime { .. } => self.visit_generic_param(param),
538 GenericParamKind::Type { ref default, .. } => {
539 for bound in ¶m.bounds {
540 self.visit_param_bound(bound);
543 if let Some(ref ty) = default {
544 self.ribs[TypeNS].push(default_ban_rib);
546 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
549 // Allow all following defaults to refer to this type parameter.
550 default_ban_rib.bindings.remove(&Ident::with_dummy_span(param.ident.name));
552 GenericParamKind::Const { ref ty } => {
553 for bound in ¶m.bounds {
554 self.visit_param_bound(bound);
560 for p in &generics.where_clause.predicates {
561 self.visit_where_predicate(p);
565 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
566 debug!("visit_generic_arg({:?})", arg);
567 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
569 GenericArg::Type(ref ty) => {
570 // We parse const arguments as path types as we cannot distinguish them during
571 // parsing. We try to resolve that ambiguity by attempting resolution the type
572 // namespace first, and if that fails we try again in the value namespace. If
573 // resolution in the value namespace succeeds, we have an generic const argument on
575 if let TyKind::Path(ref qself, ref path) = ty.kind {
576 // We cannot disambiguate multi-segment paths right now as that requires type
578 if path.segments.len() == 1 && path.segments[0].args.is_none() {
579 let mut check_ns = |ns| {
580 self.resolve_ident_in_lexical_scope(
581 path.segments[0].ident,
588 if !check_ns(TypeNS) && check_ns(ValueNS) {
589 // This must be equivalent to `visit_anon_const`, but we cannot call it
590 // directly due to visitor lifetimes so we have to copy-paste some code.
591 self.with_constant_rib(|this| {
592 this.smart_resolve_path(
596 PathSource::Expr(None),
599 if let Some(ref qself) = *qself {
600 this.visit_ty(&qself.ty);
602 this.visit_path(path, ty.id);
605 self.diagnostic_metadata.currently_processing_generics = prev;
613 GenericArg::Lifetime(lt) => self.visit_lifetime(lt),
614 GenericArg::Const(ct) => self.visit_anon_const(ct),
616 self.diagnostic_metadata.currently_processing_generics = prev;
620 impl<'a, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
621 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
622 // During late resolution we only track the module component of the parent scope,
623 // although it may be useful to track other components as well for diagnostics.
624 let graph_root = resolver.graph_root;
625 let parent_scope = ParentScope::module(graph_root);
626 let start_rib_kind = ModuleRibKind(graph_root);
627 LateResolutionVisitor {
631 value_ns: vec![Rib::new(start_rib_kind)],
632 type_ns: vec![Rib::new(start_rib_kind)],
633 macro_ns: vec![Rib::new(start_rib_kind)],
635 label_ribs: Vec::new(),
636 current_trait_ref: None,
637 diagnostic_metadata: DiagnosticMetadata::default(),
641 fn resolve_ident_in_lexical_scope(
645 record_used_id: Option<NodeId>,
647 ) -> Option<LexicalScopeBinding<'a>> {
648 self.r.resolve_ident_in_lexical_scope(
661 opt_ns: Option<Namespace>, // `None` indicates a module path in import
664 crate_lint: CrateLint,
665 ) -> PathResult<'a> {
666 self.r.resolve_path_with_ribs(
679 // We maintain a list of value ribs and type ribs.
681 // Simultaneously, we keep track of the current position in the module
682 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
683 // the value or type namespaces, we first look through all the ribs and
684 // then query the module graph. When we resolve a name in the module
685 // namespace, we can skip all the ribs (since nested modules are not
686 // allowed within blocks in Rust) and jump straight to the current module
689 // Named implementations are handled separately. When we find a method
690 // call, we consult the module node to find all of the implementations in
691 // scope. This information is lazily cached in the module node. We then
692 // generate a fake "implementation scope" containing all the
693 // implementations thus found, for compatibility with old resolve pass.
695 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
700 work: impl FnOnce(&mut Self) -> T,
702 self.ribs[ns].push(Rib::new(kind));
703 let ret = work(self);
708 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
709 let id = self.r.definitions.local_def_id(id);
710 let module = self.r.module_map.get(&id).cloned(); // clones a reference
711 if let Some(module) = module {
712 // Move down in the graph.
713 let orig_module = replace(&mut self.parent_scope.module, module);
714 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
715 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
717 this.parent_scope.module = orig_module;
726 /// Searches the current set of local scopes for labels. Returns the first non-`None` label that
727 /// is returned by the given predicate function
729 /// Stops after meeting a closure.
730 fn search_label<P, R>(&self, mut ident: Ident, pred: P) -> Option<R>
732 P: Fn(&Rib<'_, NodeId>, Ident) -> Option<R>,
734 for rib in self.label_ribs.iter().rev() {
737 // If an invocation of this macro created `ident`, give up on `ident`
738 // and switch to `ident`'s source from the macro definition.
739 MacroDefinition(def) => {
740 if def == self.r.macro_def(ident.span.ctxt()) {
741 ident.span.remove_mark();
745 // Do not resolve labels across function boundary
749 let r = pred(rib, ident);
757 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
758 debug!("resolve_adt");
759 self.with_current_self_item(item, |this| {
760 this.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
761 let item_def_id = this.r.definitions.local_def_id(item.id).to_def_id();
762 this.with_self_rib(Res::SelfTy(None, Some(item_def_id)), |this| {
763 visit::walk_item(this, item);
769 fn future_proof_import(&mut self, use_tree: &UseTree) {
770 let segments = &use_tree.prefix.segments;
771 if !segments.is_empty() {
772 let ident = segments[0].ident;
773 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
777 let nss = match use_tree.kind {
778 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
781 let report_error = |this: &Self, ns| {
782 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
783 this.r.session.span_err(ident.span, &format!("imports cannot refer to {}", what));
787 match self.resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span) {
788 Some(LexicalScopeBinding::Res(..)) => {
789 report_error(self, ns);
791 Some(LexicalScopeBinding::Item(binding)) => {
792 let orig_blacklisted_binding =
793 replace(&mut self.r.blacklisted_binding, Some(binding));
794 if let Some(LexicalScopeBinding::Res(..)) = self
795 .resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span)
797 report_error(self, ns);
799 self.r.blacklisted_binding = orig_blacklisted_binding;
804 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
805 for (use_tree, _) in use_trees {
806 self.future_proof_import(use_tree);
811 fn resolve_item(&mut self, item: &'ast Item) {
812 let name = item.ident.name;
813 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
816 ItemKind::TyAlias(_, ref generics, _, _) | ItemKind::Fn(_, _, ref generics, _) => {
817 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
818 visit::walk_item(this, item)
822 ItemKind::Enum(_, ref generics)
823 | ItemKind::Struct(_, ref generics)
824 | ItemKind::Union(_, ref generics) => {
825 self.resolve_adt(item, generics);
832 items: ref impl_items,
835 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
838 ItemKind::Trait(.., ref generics, ref bounds, ref trait_items) => {
839 // Create a new rib for the trait-wide type parameters.
840 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
841 let local_def_id = this.r.definitions.local_def_id(item.id).to_def_id();
842 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
843 this.visit_generics(generics);
844 walk_list!(this, visit_param_bound, bounds);
846 let walk_assoc_item = |this: &mut Self, generics, item| {
847 this.with_generic_param_rib(generics, AssocItemRibKind, |this| {
848 visit::walk_assoc_item(this, item, AssocCtxt::Trait)
852 for item in trait_items {
853 this.with_trait_items(trait_items, |this| {
855 AssocItemKind::Const(_, ty, default) => {
857 // Only impose the restrictions of `ConstRibKind` for an
858 // actual constant expression in a provided default.
859 if let Some(expr) = default {
860 this.with_constant_rib(|this| this.visit_expr(expr));
863 AssocItemKind::Fn(_, _, generics, _) => {
864 walk_assoc_item(this, generics, item);
866 AssocItemKind::TyAlias(_, generics, _, _) => {
867 walk_assoc_item(this, generics, item);
869 AssocItemKind::MacCall(_) => {
870 panic!("unexpanded macro in resolve!")
879 ItemKind::TraitAlias(ref generics, ref bounds) => {
880 // Create a new rib for the trait-wide type parameters.
881 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
882 let local_def_id = this.r.definitions.local_def_id(item.id).to_def_id();
883 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
884 this.visit_generics(generics);
885 walk_list!(this, visit_param_bound, bounds);
890 ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
891 self.with_scope(item.id, |this| {
892 visit::walk_item(this, item);
896 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
897 debug!("resolve_item ItemKind::Const");
898 self.with_item_rib(HasGenericParams::No, |this| {
900 if let Some(expr) = expr {
901 this.with_constant_rib(|this| this.visit_expr(expr));
906 ItemKind::Use(ref use_tree) => {
907 self.future_proof_import(use_tree);
910 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) | ItemKind::GlobalAsm(..) => {
911 // do nothing, these are just around to be encoded
914 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
918 fn with_generic_param_rib<'c, F>(&'c mut self, generics: &'c Generics, kind: RibKind<'a>, f: F)
920 F: FnOnce(&mut Self),
922 debug!("with_generic_param_rib");
923 let mut function_type_rib = Rib::new(kind);
924 let mut function_value_rib = Rib::new(kind);
925 let mut seen_bindings = FxHashMap::default();
927 // We also can't shadow bindings from the parent item
928 if let AssocItemRibKind = kind {
929 let mut add_bindings_for_ns = |ns| {
930 let parent_rib = self.ribs[ns]
932 .rfind(|r| if let ItemRibKind(_) = r.kind { true } else { false })
933 .expect("associated item outside of an item");
935 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
937 add_bindings_for_ns(ValueNS);
938 add_bindings_for_ns(TypeNS);
941 for param in &generics.params {
942 if let GenericParamKind::Lifetime { .. } = param.kind {
946 let def_kind = match param.kind {
947 GenericParamKind::Type { .. } => DefKind::TyParam,
948 GenericParamKind::Const { .. } => DefKind::ConstParam,
952 let ident = param.ident.normalize_to_macros_2_0();
953 debug!("with_generic_param_rib: {}", param.id);
955 if seen_bindings.contains_key(&ident) {
956 let span = seen_bindings.get(&ident).unwrap();
957 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, *span);
958 self.r.report_error(param.ident.span, err);
960 seen_bindings.entry(ident).or_insert(param.ident.span);
962 // Plain insert (no renaming).
963 let res = Res::Def(def_kind, self.r.definitions.local_def_id(param.id).to_def_id());
966 GenericParamKind::Type { .. } => {
967 function_type_rib.bindings.insert(ident, res);
968 self.r.record_partial_res(param.id, PartialRes::new(res));
970 GenericParamKind::Const { .. } => {
971 function_value_rib.bindings.insert(ident, res);
972 self.r.record_partial_res(param.id, PartialRes::new(res));
978 self.ribs[ValueNS].push(function_value_rib);
979 self.ribs[TypeNS].push(function_type_rib);
983 self.ribs[TypeNS].pop();
984 self.ribs[ValueNS].pop();
987 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
988 self.label_ribs.push(Rib::new(kind));
990 self.label_ribs.pop();
993 fn with_item_rib(&mut self, has_generic_params: HasGenericParams, f: impl FnOnce(&mut Self)) {
994 let kind = ItemRibKind(has_generic_params);
995 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
998 fn with_constant_rib(&mut self, f: impl FnOnce(&mut Self)) {
999 debug!("with_constant_rib");
1000 self.with_rib(ValueNS, ConstantItemRibKind, |this| {
1001 this.with_label_rib(ConstantItemRibKind, f);
1005 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
1006 // Handle nested impls (inside fn bodies)
1007 let previous_value =
1008 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
1009 let result = f(self);
1010 self.diagnostic_metadata.current_self_type = previous_value;
1014 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
1015 let previous_value =
1016 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
1017 let result = f(self);
1018 self.diagnostic_metadata.current_self_item = previous_value;
1022 /// When evaluating a `trait` use its associated types' idents for suggestionsa in E0412.
1023 fn with_trait_items<T>(
1025 trait_items: &Vec<P<AssocItem>>,
1026 f: impl FnOnce(&mut Self) -> T,
1028 let trait_assoc_types = replace(
1029 &mut self.diagnostic_metadata.current_trait_assoc_types,
1032 .filter_map(|item| match &item.kind {
1033 AssocItemKind::TyAlias(_, _, bounds, _) if bounds.is_empty() => {
1040 let result = f(self);
1041 self.diagnostic_metadata.current_trait_assoc_types = trait_assoc_types;
1045 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
1046 fn with_optional_trait_ref<T>(
1048 opt_trait_ref: Option<&TraitRef>,
1049 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
1051 let mut new_val = None;
1052 let mut new_id = None;
1053 if let Some(trait_ref) = opt_trait_ref {
1054 let path: Vec<_> = Segment::from_path(&trait_ref.path);
1055 let res = self.smart_resolve_path_fragment(
1059 trait_ref.path.span,
1060 PathSource::Trait(AliasPossibility::No),
1061 CrateLint::SimplePath(trait_ref.ref_id),
1063 let res = res.base_res();
1064 if res != Res::Err {
1065 new_id = Some(res.def_id());
1066 let span = trait_ref.path.span;
1067 if let PathResult::Module(ModuleOrUniformRoot::Module(module)) = self.resolve_path(
1072 CrateLint::SimplePath(trait_ref.ref_id),
1074 new_val = Some((module, trait_ref.clone()));
1078 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1079 let result = f(self, new_id);
1080 self.current_trait_ref = original_trait_ref;
1084 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
1085 let mut self_type_rib = Rib::new(NormalRibKind);
1087 // Plain insert (no renaming, since types are not currently hygienic)
1088 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
1089 self.ribs[ns].push(self_type_rib);
1091 self.ribs[ns].pop();
1094 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
1095 self.with_self_rib_ns(TypeNS, self_res, f)
1098 fn resolve_implementation(
1100 generics: &'ast Generics,
1101 opt_trait_reference: &'ast Option<TraitRef>,
1102 self_type: &'ast Ty,
1104 impl_items: &'ast [P<AssocItem>],
1106 debug!("resolve_implementation");
1107 // If applicable, create a rib for the type parameters.
1108 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1109 // Dummy self type for better errors if `Self` is used in the trait path.
1110 this.with_self_rib(Res::SelfTy(None, None), |this| {
1111 // Resolve the trait reference, if necessary.
1112 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1113 let item_def_id = this.r.definitions.local_def_id(item_id).to_def_id();
1114 this.with_self_rib(Res::SelfTy(trait_id, Some(item_def_id)), |this| {
1115 if let Some(trait_ref) = opt_trait_reference.as_ref() {
1116 // Resolve type arguments in the trait path.
1117 visit::walk_trait_ref(this, trait_ref);
1119 // Resolve the self type.
1120 this.visit_ty(self_type);
1121 // Resolve the generic parameters.
1122 this.visit_generics(generics);
1123 // Resolve the items within the impl.
1124 this.with_current_self_type(self_type, |this| {
1125 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
1126 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
1127 for item in impl_items {
1128 use crate::ResolutionError::*;
1130 AssocItemKind::Const(..) => {
1131 debug!("resolve_implementation AssocItemKind::Const",);
1132 // If this is a trait impl, ensure the const
1134 this.check_trait_item(
1138 |n, s| ConstNotMemberOfTrait(n, s),
1141 this.with_constant_rib(|this| {
1142 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
1145 AssocItemKind::Fn(_, _, generics, _) => {
1146 // We also need a new scope for the impl item type parameters.
1147 this.with_generic_param_rib(
1151 // If this is a trait impl, ensure the method
1153 this.check_trait_item(
1157 |n, s| MethodNotMemberOfTrait(n, s),
1160 visit::walk_assoc_item(
1168 AssocItemKind::TyAlias(_, generics, _, _) => {
1169 // We also need a new scope for the impl item type parameters.
1170 this.with_generic_param_rib(
1174 // If this is a trait impl, ensure the type
1176 this.check_trait_item(
1180 |n, s| TypeNotMemberOfTrait(n, s),
1183 visit::walk_assoc_item(
1191 AssocItemKind::MacCall(_) => {
1192 panic!("unexpanded macro in resolve!")
1204 fn check_trait_item<F>(&mut self, ident: Ident, ns: Namespace, span: Span, err: F)
1206 F: FnOnce(Symbol, &str) -> ResolutionError<'_>,
1208 // If there is a TraitRef in scope for an impl, then the method must be in the
1210 if let Some((module, _)) = self.current_trait_ref {
1213 .resolve_ident_in_module(
1214 ModuleOrUniformRoot::Module(module),
1223 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
1224 self.r.report_error(span, err(ident.name, &path_names_to_string(path)));
1229 fn resolve_params(&mut self, params: &'ast [Param]) {
1230 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1231 for Param { pat, ty, .. } in params {
1232 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1234 debug!("(resolving function / closure) recorded parameter");
1238 fn resolve_local(&mut self, local: &'ast Local) {
1239 // Resolve the type.
1240 walk_list!(self, visit_ty, &local.ty);
1242 // Resolve the initializer.
1243 walk_list!(self, visit_expr, &local.init);
1245 // Resolve the pattern.
1246 self.resolve_pattern_top(&local.pat, PatternSource::Let);
1249 /// build a map from pattern identifiers to binding-info's.
1250 /// this is done hygienically. This could arise for a macro
1251 /// that expands into an or-pattern where one 'x' was from the
1252 /// user and one 'x' came from the macro.
1253 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1254 let mut binding_map = FxHashMap::default();
1256 pat.walk(&mut |pat| {
1258 PatKind::Ident(binding_mode, ident, ref sub_pat)
1259 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
1261 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
1263 PatKind::Or(ref ps) => {
1264 // Check the consistency of this or-pattern and
1265 // then add all bindings to the larger map.
1266 for bm in self.check_consistent_bindings(ps) {
1267 binding_map.extend(bm);
1280 fn is_base_res_local(&self, nid: NodeId) -> bool {
1281 match self.r.partial_res_map.get(&nid).map(|res| res.base_res()) {
1282 Some(Res::Local(..)) => true,
1287 /// Checks that all of the arms in an or-pattern have exactly the
1288 /// same set of bindings, with the same binding modes for each.
1289 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
1290 let mut missing_vars = FxHashMap::default();
1291 let mut inconsistent_vars = FxHashMap::default();
1293 // 1) Compute the binding maps of all arms.
1294 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
1296 // 2) Record any missing bindings or binding mode inconsistencies.
1297 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
1298 // Check against all arms except for the same pattern which is always self-consistent.
1302 .filter(|(_, pat)| pat.id != pat_outer.id)
1303 .flat_map(|(idx, _)| maps[idx].iter())
1304 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
1306 for (name, info, &binding_inner) in inners {
1309 // The inner binding is missing in the outer.
1311 missing_vars.entry(name).or_insert_with(|| BindingError {
1313 origin: BTreeSet::new(),
1314 target: BTreeSet::new(),
1315 could_be_path: name.as_str().starts_with(char::is_uppercase),
1317 binding_error.origin.insert(binding_inner.span);
1318 binding_error.target.insert(pat_outer.span);
1320 Some(binding_outer) => {
1321 if binding_outer.binding_mode != binding_inner.binding_mode {
1322 // The binding modes in the outer and inner bindings differ.
1325 .or_insert((binding_inner.span, binding_outer.span));
1332 // 3) Report all missing variables we found.
1333 let mut missing_vars = missing_vars.iter_mut().collect::<Vec<_>>();
1334 missing_vars.sort_by_key(|(sym, _err)| sym.as_str());
1336 for (name, mut v) in missing_vars {
1337 if inconsistent_vars.contains_key(name) {
1338 v.could_be_path = false;
1340 self.r.report_error(
1341 *v.origin.iter().next().unwrap(),
1342 ResolutionError::VariableNotBoundInPattern(v),
1346 // 4) Report all inconsistencies in binding modes we found.
1347 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
1348 inconsistent_vars.sort();
1349 for (name, v) in inconsistent_vars {
1350 self.r.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
1353 // 5) Finally bubble up all the binding maps.
1357 /// Check the consistency of the outermost or-patterns.
1358 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
1359 pat.walk(&mut |pat| match pat.kind {
1360 PatKind::Or(ref ps) => {
1361 self.check_consistent_bindings(ps);
1368 fn resolve_arm(&mut self, arm: &'ast Arm) {
1369 self.with_rib(ValueNS, NormalRibKind, |this| {
1370 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
1371 walk_list!(this, visit_expr, &arm.guard);
1372 this.visit_expr(&arm.body);
1376 /// Arising from `source`, resolve a top level pattern.
1377 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
1378 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1379 self.resolve_pattern(pat, pat_src, &mut bindings);
1385 pat_src: PatternSource,
1386 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1388 self.resolve_pattern_inner(pat, pat_src, bindings);
1389 // This has to happen *after* we determine which pat_idents are variants:
1390 self.check_consistent_bindings_top(pat);
1391 visit::walk_pat(self, pat);
1394 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
1398 /// A stack of sets of bindings accumulated.
1400 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
1401 /// be interpreted as re-binding an already bound binding. This results in an error.
1402 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
1403 /// in reusing this binding rather than creating a fresh one.
1405 /// When called at the top level, the stack must have a single element
1406 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
1407 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
1408 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
1409 /// When each `p_i` has been dealt with, the top set is merged with its parent.
1410 /// When a whole or-pattern has been dealt with, the thing happens.
1412 /// See the implementation and `fresh_binding` for more details.
1413 fn resolve_pattern_inner(
1416 pat_src: PatternSource,
1417 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1419 // Visit all direct subpatterns of this pattern.
1420 pat.walk(&mut |pat| {
1421 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
1423 PatKind::Ident(bmode, ident, ref sub) => {
1424 // First try to resolve the identifier as some existing entity,
1425 // then fall back to a fresh binding.
1426 let has_sub = sub.is_some();
1428 .try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub)
1429 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
1430 self.r.record_partial_res(pat.id, PartialRes::new(res));
1432 PatKind::TupleStruct(ref path, ..) => {
1433 self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);
1435 PatKind::Path(ref qself, ref path) => {
1436 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
1438 PatKind::Struct(ref path, ..) => {
1439 self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
1441 PatKind::Or(ref ps) => {
1442 // Add a new set of bindings to the stack. `Or` here records that when a
1443 // binding already exists in this set, it should not result in an error because
1444 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
1445 bindings.push((PatBoundCtx::Or, Default::default()));
1447 // Now we need to switch back to a product context so that each
1448 // part of the or-pattern internally rejects already bound names.
1449 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
1450 bindings.push((PatBoundCtx::Product, Default::default()));
1451 self.resolve_pattern_inner(p, pat_src, bindings);
1452 // Move up the non-overlapping bindings to the or-pattern.
1453 // Existing bindings just get "merged".
1454 let collected = bindings.pop().unwrap().1;
1455 bindings.last_mut().unwrap().1.extend(collected);
1457 // This or-pattern itself can itself be part of a product,
1458 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
1459 // Both cases bind `a` again in a product pattern and must be rejected.
1460 let collected = bindings.pop().unwrap().1;
1461 bindings.last_mut().unwrap().1.extend(collected);
1463 // Prevent visiting `ps` as we've already done so above.
1476 pat_src: PatternSource,
1477 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1479 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
1480 // (We must not add it if it's in the bindings map because that breaks the assumptions
1481 // later passes make about or-patterns.)
1482 let ident = ident.normalize_to_macro_rules();
1484 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
1485 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
1486 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
1487 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
1488 // This is *required* for consistency which is checked later.
1489 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
1491 if already_bound_and {
1492 // Overlap in a product pattern somewhere; report an error.
1493 use ResolutionError::*;
1494 let error = match pat_src {
1495 // `fn f(a: u8, a: u8)`:
1496 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
1498 _ => IdentifierBoundMoreThanOnceInSamePattern,
1500 self.r.report_error(ident.span, error(&ident.as_str()));
1503 // Record as bound if it's valid:
1504 let ident_valid = ident.name != kw::Invalid;
1506 bindings.last_mut().unwrap().1.insert(ident);
1509 if already_bound_or {
1510 // `Variant1(a) | Variant2(a)`, ok
1511 // Reuse definition from the first `a`.
1512 self.innermost_rib_bindings(ValueNS)[&ident]
1514 let res = Res::Local(pat_id);
1516 // A completely fresh binding add to the set if it's valid.
1517 self.innermost_rib_bindings(ValueNS).insert(ident, res);
1523 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
1524 &mut self.ribs[ns].last_mut().unwrap().bindings
1527 fn try_resolve_as_non_binding(
1529 pat_src: PatternSource,
1535 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
1536 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
1537 // also be interpreted as a path to e.g. a constant, variant, etc.
1538 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
1540 let ls_binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, pat.span)?;
1541 let (res, binding) = match ls_binding {
1542 LexicalScopeBinding::Item(binding)
1543 if is_syntactic_ambiguity && binding.is_ambiguity() =>
1545 // For ambiguous bindings we don't know all their definitions and cannot check
1546 // whether they can be shadowed by fresh bindings or not, so force an error.
1547 // issues/33118#issuecomment-233962221 (see below) still applies here,
1548 // but we have to ignore it for backward compatibility.
1549 self.r.record_use(ident, ValueNS, binding, false);
1552 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
1553 LexicalScopeBinding::Res(res) => (res, None),
1557 Res::SelfCtor(_) // See #70549.
1559 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
1561 ) if is_syntactic_ambiguity => {
1562 // Disambiguate in favor of a unit struct/variant or constant pattern.
1563 if let Some(binding) = binding {
1564 self.r.record_use(ident, ValueNS, binding, false);
1568 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static, _) => {
1569 // This is unambiguously a fresh binding, either syntactically
1570 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
1571 // to something unusable as a pattern (e.g., constructor function),
1572 // but we still conservatively report an error, see
1573 // issues/33118#issuecomment-233962221 for one reason why.
1574 self.r.report_error(
1576 ResolutionError::BindingShadowsSomethingUnacceptable(
1579 binding.expect("no binding for a ctor or static"),
1584 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
1585 // These entities are explicitly allowed to be shadowed by fresh bindings.
1590 "unexpected resolution for an identifier in pattern: {:?}",
1596 // High-level and context dependent path resolution routine.
1597 // Resolves the path and records the resolution into definition map.
1598 // If resolution fails tries several techniques to find likely
1599 // resolution candidates, suggest imports or other help, and report
1600 // errors in user friendly way.
1601 fn smart_resolve_path(
1604 qself: Option<&QSelf>,
1606 source: PathSource<'ast>,
1608 self.smart_resolve_path_fragment(
1611 &Segment::from_path(path),
1614 CrateLint::SimplePath(id),
1618 fn smart_resolve_path_fragment(
1621 qself: Option<&QSelf>,
1624 source: PathSource<'ast>,
1625 crate_lint: CrateLint,
1627 let ns = source.namespace();
1628 let is_expected = &|res| source.is_expected(res);
1630 let report_errors = |this: &mut Self, res: Option<Res>| {
1631 let (err, candidates) = this.smart_resolve_report_errors(path, span, source, res);
1633 let def_id = this.parent_scope.module.normal_ancestor_id;
1634 let instead = res.is_some();
1636 if res.is_none() { this.report_missing_type_error(path) } else { None };
1638 this.r.use_injections.push(UseError { err, candidates, def_id, instead, suggestion });
1640 PartialRes::new(Res::Err)
1643 // For paths originating from calls (like in `HashMap::new()`), tries
1644 // to enrich the plain `failed to resolve: ...` message with hints
1645 // about possible missing imports.
1647 // Similar thing, for types, happens in `report_errors` above.
1648 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
1649 if !source.is_call() {
1650 return Some(parent_err);
1653 // Before we start looking for candidates, we have to get our hands
1654 // on the type user is trying to perform invocation on; basically:
1655 // we're transforming `HashMap::new` into just `HashMap`
1656 let path = if let Some((_, path)) = path.split_last() {
1659 return Some(parent_err);
1662 let (mut err, candidates) =
1663 this.smart_resolve_report_errors(path, span, PathSource::Type, None);
1665 if candidates.is_empty() {
1667 return Some(parent_err);
1670 // There are two different error messages user might receive at
1672 // - E0412 cannot find type `{}` in this scope
1673 // - E0433 failed to resolve: use of undeclared type or module `{}`
1675 // The first one is emitted for paths in type-position, and the
1676 // latter one - for paths in expression-position.
1678 // Thus (since we're in expression-position at this point), not to
1679 // confuse the user, we want to keep the *message* from E0432 (so
1680 // `parent_err`), but we want *hints* from E0412 (so `err`).
1682 // And that's what happens below - we're just mixing both messages
1683 // into a single one.
1684 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
1686 parent_err.cancel();
1688 err.message = take(&mut parent_err.message);
1689 err.code = take(&mut parent_err.code);
1690 err.children = take(&mut parent_err.children);
1694 let def_id = this.parent_scope.module.normal_ancestor_id;
1696 this.r.use_injections.push(UseError {
1704 // We don't return `Some(parent_err)` here, because the error will
1705 // be already printed as part of the `use` injections
1709 let partial_res = match self.resolve_qpath_anywhere(
1715 source.defer_to_typeck(),
1718 Ok(Some(partial_res)) if partial_res.unresolved_segments() == 0 => {
1719 if is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err {
1722 report_errors(self, Some(partial_res.base_res()))
1726 Ok(Some(partial_res)) if source.defer_to_typeck() => {
1727 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
1728 // or `<T>::A::B`. If `B` should be resolved in value namespace then
1729 // it needs to be added to the trait map.
1731 let item_name = path.last().unwrap().ident;
1732 let traits = self.get_traits_containing_item(item_name, ns);
1733 self.r.trait_map.insert(id, traits);
1736 let mut std_path = vec![Segment::from_ident(Ident::with_dummy_span(sym::std))];
1738 std_path.extend(path);
1740 if self.r.primitive_type_table.primitive_types.contains_key(&path[0].ident.name) {
1741 if let PathResult::Module(_) | PathResult::NonModule(_) =
1742 self.resolve_path(&std_path, Some(ns), false, span, CrateLint::No)
1744 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
1746 path.iter().last().map(|segment| segment.ident.span).unwrap_or(span);
1748 let mut hm = self.r.session.confused_type_with_std_module.borrow_mut();
1749 hm.insert(item_span, span);
1750 hm.insert(span, span);
1758 if let Some(err) = report_errors_for_call(self, err) {
1759 self.r.report_error(err.span, err.node);
1762 PartialRes::new(Res::Err)
1765 _ => report_errors(self, None),
1768 if let PathSource::TraitItem(..) = source {
1770 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
1771 self.r.record_partial_res(id, partial_res);
1777 fn self_type_is_available(&mut self, span: Span) -> bool {
1778 let binding = self.resolve_ident_in_lexical_scope(
1779 Ident::with_dummy_span(kw::SelfUpper),
1784 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1787 fn self_value_is_available(&mut self, self_span: Span, path_span: Span) -> bool {
1788 let ident = Ident::new(kw::SelfLower, self_span);
1789 let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, path_span);
1790 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1793 // Resolve in alternative namespaces if resolution in the primary namespace fails.
1794 fn resolve_qpath_anywhere(
1797 qself: Option<&QSelf>,
1799 primary_ns: Namespace,
1801 defer_to_typeck: bool,
1802 crate_lint: CrateLint,
1803 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
1804 let mut fin_res = None;
1806 for (i, ns) in [primary_ns, TypeNS, ValueNS].iter().cloned().enumerate() {
1807 if i == 0 || ns != primary_ns {
1808 match self.resolve_qpath(id, qself, path, ns, span, crate_lint)? {
1810 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
1812 return Ok(Some(partial_res));
1815 if fin_res.is_none() {
1816 fin_res = partial_res
1823 assert!(primary_ns != MacroNS);
1825 if qself.is_none() {
1826 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
1827 let path = Path { segments: path.iter().map(path_seg).collect(), span };
1828 if let Ok((_, res)) =
1829 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
1831 return Ok(Some(PartialRes::new(res)));
1838 /// Handles paths that may refer to associated items.
1842 qself: Option<&QSelf>,
1846 crate_lint: CrateLint,
1847 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
1849 "resolve_qpath(id={:?}, qself={:?}, path={:?}, ns={:?}, span={:?})",
1850 id, qself, path, ns, span,
1853 if let Some(qself) = qself {
1854 if qself.position == 0 {
1855 // This is a case like `<T>::B`, where there is no
1856 // trait to resolve. In that case, we leave the `B`
1857 // segment to be resolved by type-check.
1858 return Ok(Some(PartialRes::with_unresolved_segments(
1859 Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX)),
1864 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
1866 // Currently, `path` names the full item (`A::B::C`, in
1867 // our example). so we extract the prefix of that that is
1868 // the trait (the slice upto and including
1869 // `qself.position`). And then we recursively resolve that,
1870 // but with `qself` set to `None`.
1872 // However, setting `qself` to none (but not changing the
1873 // span) loses the information about where this path
1874 // *actually* appears, so for the purposes of the crate
1875 // lint we pass along information that this is the trait
1876 // name from a fully qualified path, and this also
1877 // contains the full span (the `CrateLint::QPathTrait`).
1878 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
1879 let partial_res = self.smart_resolve_path_fragment(
1882 &path[..=qself.position],
1884 PathSource::TraitItem(ns),
1885 CrateLint::QPathTrait { qpath_id: id, qpath_span: qself.path_span },
1888 // The remaining segments (the `C` in our example) will
1889 // have to be resolved by type-check, since that requires doing
1890 // trait resolution.
1891 return Ok(Some(PartialRes::with_unresolved_segments(
1892 partial_res.base_res(),
1893 partial_res.unresolved_segments() + path.len() - qself.position - 1,
1897 let result = match self.resolve_path(&path, Some(ns), true, span, crate_lint) {
1898 PathResult::NonModule(path_res) => path_res,
1899 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
1900 PartialRes::new(module.res().unwrap())
1902 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
1903 // don't report an error right away, but try to fallback to a primitive type.
1904 // So, we are still able to successfully resolve something like
1906 // use std::u8; // bring module u8 in scope
1907 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
1908 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
1909 // // not to non-existent std::u8::max_value
1912 // Such behavior is required for backward compatibility.
1913 // The same fallback is used when `a` resolves to nothing.
1914 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
1915 if (ns == TypeNS || path.len() > 1)
1918 .primitive_type_table
1920 .contains_key(&path[0].ident.name) =>
1922 let prim = self.r.primitive_type_table.primitive_types[&path[0].ident.name];
1923 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
1925 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
1926 PartialRes::new(module.res().unwrap())
1928 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
1929 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
1931 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
1932 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
1936 && result.base_res() != Res::Err
1937 && path[0].ident.name != kw::PathRoot
1938 && path[0].ident.name != kw::DollarCrate
1940 let unqualified_result = {
1941 match self.resolve_path(
1942 &[*path.last().unwrap()],
1948 PathResult::NonModule(path_res) => path_res.base_res(),
1949 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
1950 module.res().unwrap()
1952 _ => return Ok(Some(result)),
1955 if result.base_res() == unqualified_result {
1956 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
1957 self.r.lint_buffer.buffer_lint(lint, id, span, "unnecessary qualification")
1964 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
1965 if let Some(label) = label {
1966 if label.ident.as_str().as_bytes()[1] != b'_' {
1967 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
1969 self.with_label_rib(NormalRibKind, |this| {
1970 let ident = label.ident.normalize_to_macro_rules();
1971 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
1979 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
1980 self.with_resolved_label(label, id, |this| this.visit_block(block));
1983 fn resolve_block(&mut self, block: &'ast Block) {
1984 debug!("(resolving block) entering block");
1985 // Move down in the graph, if there's an anonymous module rooted here.
1986 let orig_module = self.parent_scope.module;
1987 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
1989 let mut num_macro_definition_ribs = 0;
1990 if let Some(anonymous_module) = anonymous_module {
1991 debug!("(resolving block) found anonymous module, moving down");
1992 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
1993 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
1994 self.parent_scope.module = anonymous_module;
1996 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
1999 // Descend into the block.
2000 for stmt in &block.stmts {
2001 if let StmtKind::Item(ref item) = stmt.kind {
2002 if let ItemKind::MacroDef(..) = item.kind {
2003 num_macro_definition_ribs += 1;
2004 let res = self.r.definitions.local_def_id(item.id).to_def_id();
2005 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
2006 self.label_ribs.push(Rib::new(MacroDefinition(res)));
2010 self.visit_stmt(stmt);
2014 self.parent_scope.module = orig_module;
2015 for _ in 0..num_macro_definition_ribs {
2016 self.ribs[ValueNS].pop();
2017 self.label_ribs.pop();
2019 self.ribs[ValueNS].pop();
2020 if anonymous_module.is_some() {
2021 self.ribs[TypeNS].pop();
2023 debug!("(resolving block) leaving block");
2026 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
2027 // First, record candidate traits for this expression if it could
2028 // result in the invocation of a method call.
2030 self.record_candidate_traits_for_expr_if_necessary(expr);
2032 // Next, resolve the node.
2034 ExprKind::Path(ref qself, ref path) => {
2035 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
2036 visit::walk_expr(self, expr);
2039 ExprKind::Struct(ref path, ..) => {
2040 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
2041 visit::walk_expr(self, expr);
2044 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
2045 let node_id = self.search_label(label.ident, |rib, ident| {
2046 rib.bindings.get(&ident.normalize_to_macro_rules()).cloned()
2050 // Search again for close matches...
2051 // Picks the first label that is "close enough", which is not necessarily
2052 // the closest match
2053 let close_match = self.search_label(label.ident, |rib, ident| {
2054 let names = rib.bindings.iter().filter_map(|(id, _)| {
2055 if id.span.ctxt() == label.ident.span.ctxt() {
2061 find_best_match_for_name(names, &ident.as_str(), None)
2063 self.r.record_partial_res(expr.id, PartialRes::new(Res::Err));
2064 self.r.report_error(
2066 ResolutionError::UndeclaredLabel(&label.ident.as_str(), close_match),
2070 // Since this res is a label, it is never read.
2071 self.r.label_res_map.insert(expr.id, node_id);
2072 self.diagnostic_metadata.unused_labels.remove(&node_id);
2076 // visit `break` argument if any
2077 visit::walk_expr(self, expr);
2080 ExprKind::Let(ref pat, ref scrutinee) => {
2081 self.visit_expr(scrutinee);
2082 self.resolve_pattern_top(pat, PatternSource::Let);
2085 ExprKind::If(ref cond, ref then, ref opt_else) => {
2086 self.with_rib(ValueNS, NormalRibKind, |this| {
2087 this.visit_expr(cond);
2088 this.visit_block(then);
2090 if let Some(expr) = opt_else {
2091 self.visit_expr(expr);
2095 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
2097 ExprKind::While(ref cond, ref block, label) => {
2098 self.with_resolved_label(label, expr.id, |this| {
2099 this.with_rib(ValueNS, NormalRibKind, |this| {
2100 this.visit_expr(cond);
2101 this.visit_block(block);
2106 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
2107 self.visit_expr(iter_expr);
2108 self.with_rib(ValueNS, NormalRibKind, |this| {
2109 this.resolve_pattern_top(pat, PatternSource::For);
2110 this.resolve_labeled_block(label, expr.id, block);
2114 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
2116 // Equivalent to `visit::walk_expr` + passing some context to children.
2117 ExprKind::Field(ref subexpression, _) => {
2118 self.resolve_expr(subexpression, Some(expr));
2120 ExprKind::MethodCall(ref segment, ref arguments) => {
2121 let mut arguments = arguments.iter();
2122 self.resolve_expr(arguments.next().unwrap(), Some(expr));
2123 for argument in arguments {
2124 self.resolve_expr(argument, None);
2126 self.visit_path_segment(expr.span, segment);
2129 ExprKind::Call(ref callee, ref arguments) => {
2130 self.resolve_expr(callee, Some(expr));
2131 for argument in arguments {
2132 self.resolve_expr(argument, None);
2135 ExprKind::Type(ref type_expr, _) => {
2136 self.diagnostic_metadata.current_type_ascription.push(type_expr.span);
2137 visit::walk_expr(self, expr);
2138 self.diagnostic_metadata.current_type_ascription.pop();
2140 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
2141 // resolve the arguments within the proper scopes so that usages of them inside the
2142 // closure are detected as upvars rather than normal closure arg usages.
2143 ExprKind::Closure(_, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
2144 self.with_rib(ValueNS, NormalRibKind, |this| {
2145 // Resolve arguments:
2146 this.resolve_params(&fn_decl.inputs);
2147 // No need to resolve return type --
2148 // the outer closure return type is `FnRetTy::Default`.
2150 // Now resolve the inner closure
2152 // No need to resolve arguments: the inner closure has none.
2153 // Resolve the return type:
2154 visit::walk_fn_ret_ty(this, &fn_decl.output);
2156 this.visit_expr(body);
2161 visit::walk_expr(self, expr);
2166 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
2168 ExprKind::Field(_, ident) => {
2169 // FIXME(#6890): Even though you can't treat a method like a
2170 // field, we need to add any trait methods we find that match
2171 // the field name so that we can do some nice error reporting
2172 // later on in typeck.
2173 let traits = self.get_traits_containing_item(ident, ValueNS);
2174 self.r.trait_map.insert(expr.id, traits);
2176 ExprKind::MethodCall(ref segment, ..) => {
2177 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
2178 let traits = self.get_traits_containing_item(segment.ident, ValueNS);
2179 self.r.trait_map.insert(expr.id, traits);
2187 fn get_traits_containing_item(
2191 ) -> Vec<TraitCandidate<NodeId>> {
2192 debug!("(getting traits containing item) looking for '{}'", ident.name);
2194 let mut found_traits = Vec::new();
2195 // Look for the current trait.
2196 if let Some((module, _)) = self.current_trait_ref {
2199 .resolve_ident_in_module(
2200 ModuleOrUniformRoot::Module(module),
2209 let def_id = module.def_id().unwrap();
2210 found_traits.push(TraitCandidate { def_id, import_ids: smallvec![] });
2214 ident.span = ident.span.normalize_to_macros_2_0();
2215 let mut search_module = self.parent_scope.module;
2217 self.get_traits_in_module_containing_item(ident, ns, search_module, &mut found_traits);
2219 unwrap_or!(self.r.hygienic_lexical_parent(search_module, &mut ident.span), break);
2222 if let Some(prelude) = self.r.prelude {
2223 if !search_module.no_implicit_prelude {
2224 self.get_traits_in_module_containing_item(ident, ns, prelude, &mut found_traits);
2231 fn get_traits_in_module_containing_item(
2236 found_traits: &mut Vec<TraitCandidate<NodeId>>,
2238 assert!(ns == TypeNS || ns == ValueNS);
2239 let mut traits = module.traits.borrow_mut();
2240 if traits.is_none() {
2241 let mut collected_traits = Vec::new();
2242 module.for_each_child(self.r, |_, name, ns, binding| {
2246 match binding.res() {
2247 Res::Def(DefKind::Trait | DefKind::TraitAlias, _) => {
2248 collected_traits.push((name, binding))
2253 *traits = Some(collected_traits.into_boxed_slice());
2256 for &(trait_name, binding) in traits.as_ref().unwrap().iter() {
2257 // Traits have pseudo-modules that can be used to search for the given ident.
2258 if let Some(module) = binding.module() {
2259 let mut ident = ident;
2260 if ident.span.glob_adjust(module.expansion, binding.span).is_none() {
2265 .resolve_ident_in_module_unadjusted(
2266 ModuleOrUniformRoot::Module(module),
2275 let import_ids = self.find_transitive_imports(&binding.kind, trait_name);
2276 let trait_def_id = module.def_id().unwrap();
2277 found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids });
2279 } else if let Res::Def(DefKind::TraitAlias, _) = binding.res() {
2280 // For now, just treat all trait aliases as possible candidates, since we don't
2281 // know if the ident is somewhere in the transitive bounds.
2282 let import_ids = self.find_transitive_imports(&binding.kind, trait_name);
2283 let trait_def_id = binding.res().def_id();
2284 found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids });
2286 bug!("candidate is not trait or trait alias?")
2291 fn find_transitive_imports(
2293 mut kind: &NameBindingKind<'_>,
2295 ) -> SmallVec<[NodeId; 1]> {
2296 let mut import_ids = smallvec![];
2297 while let NameBindingKind::Import { import, binding, .. } = kind {
2298 let id = self.r.definitions.local_def_id(import.id);
2299 self.r.maybe_unused_trait_imports.insert(id);
2300 self.r.add_to_glob_map(&import, trait_name);
2301 import_ids.push(import.id);
2302 kind = &binding.kind;
2308 impl<'a> Resolver<'a> {
2309 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
2310 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
2311 visit::walk_crate(&mut late_resolution_visitor, krate);
2312 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
2313 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");