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 `resolve_imports.rs`.
8 use GenericParameters::*;
11 use crate::{path_names_to_string, BindingError, CrateLint, LexicalScopeBinding};
12 use crate::{Module, ModuleOrUniformRoot, NameBindingKind, ParentScope, PathResult};
13 use crate::{ResolutionError, Resolver, Segment, UseError};
16 use rustc::{bug, lint, span_bug};
17 use rustc::hir::def::{self, PartialRes, DefKind, CtorKind, PerNS};
18 use rustc::hir::def::Namespace::{self, *};
19 use rustc::hir::def_id::{DefId, CRATE_DEF_INDEX};
20 use rustc::hir::TraitCandidate;
21 use rustc::util::nodemap::{FxHashMap, FxHashSet};
22 use smallvec::{smallvec, SmallVec};
23 use syntax::{unwrap_or, walk_list};
26 use syntax::symbol::{kw, sym};
27 use syntax::util::lev_distance::find_best_match_for_name;
28 use syntax::visit::{self, Visitor, FnKind};
31 use std::collections::BTreeSet;
32 use std::mem::replace;
36 type Res = def::Res<NodeId>;
38 type IdentMap<T> = FxHashMap<Ident, T>;
40 /// Map from the name in a pattern to its binding mode.
41 type BindingMap = IdentMap<BindingInfo>;
43 #[derive(Copy, Clone, Debug)]
46 binding_mode: BindingMode,
49 #[derive(Copy, Clone)]
50 enum GenericParameters<'a, 'b> {
52 HasGenericParams(// Type parameters.
55 // The kind of the rib used for type parameters.
59 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
68 fn descr(self) -> &'static str {
70 PatternSource::Match => "match binding",
71 PatternSource::Let => "let binding",
72 PatternSource::For => "for binding",
73 PatternSource::FnParam => "function parameter",
78 /// Denotes whether the context for the set of already bound bindings is a `Product`
79 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
80 /// See those functions for more information.
82 /// A product pattern context, e.g., `Variant(a, b)`.
84 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
88 /// The rib kind restricts certain accesses,
89 /// e.g. to a `Res::Local` of an outer item.
90 #[derive(Copy, Clone, Debug)]
91 crate enum RibKind<'a> {
92 /// No restriction needs to be applied.
95 /// We passed through an impl or trait and are now in one of its
96 /// methods or associated types. Allow references to ty params that impl or trait
97 /// binds. Disallow any other upvars (including other ty params that are
101 /// We passed through a function definition. Disallow upvars.
102 /// Permit only those const parameters that are specified in the function's generics.
105 /// We passed through an item scope. Disallow upvars.
108 /// We're in a constant item. Can't refer to dynamic stuff.
111 /// We passed through a module.
112 ModuleRibKind(Module<'a>),
114 /// We passed through a `macro_rules!` statement
115 MacroDefinition(DefId),
117 /// All bindings in this rib are type parameters that can't be used
118 /// from the default of a type parameter because they're not declared
119 /// before said type parameter. Also see the `visit_generics` override.
120 ForwardTyParamBanRibKind,
122 /// We forbid the use of type parameters as the types of const parameters.
123 TyParamAsConstParamTy,
127 // Whether this rib kind contains generic parameters, as opposed to local
129 crate fn contains_params(&self) -> bool {
133 | ConstantItemRibKind
135 | MacroDefinition(_) => false,
138 | ForwardTyParamBanRibKind
139 | TyParamAsConstParamTy => true,
144 /// A single local scope.
146 /// A rib represents a scope names can live in. Note that these appear in many places, not just
147 /// around braces. At any place where the list of accessible names (of the given namespace)
148 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
149 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
152 /// Different [rib kinds](enum.RibKind) are transparent for different names.
154 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
155 /// resolving, the name is looked up from inside out.
157 crate struct Rib<'a, R = Res> {
158 pub bindings: IdentMap<R>,
159 pub kind: RibKind<'a>,
162 impl<'a, R> Rib<'a, R> {
163 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
165 bindings: Default::default(),
171 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
172 crate enum AliasPossibility {
177 #[derive(Copy, Clone, Debug)]
178 crate enum PathSource<'a> {
179 // Type paths `Path`.
181 // Trait paths in bounds or impls.
182 Trait(AliasPossibility),
183 // Expression paths `path`, with optional parent context.
184 Expr(Option<&'a Expr>),
185 // Paths in path patterns `Path`.
187 // Paths in struct expressions and patterns `Path { .. }`.
189 // Paths in tuple struct patterns `Path(..)`.
191 // `m::A::B` in `<T as m::A>::B::C`.
192 TraitItem(Namespace),
195 impl<'a> PathSource<'a> {
196 fn namespace(self) -> Namespace {
198 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
199 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct => ValueNS,
200 PathSource::TraitItem(ns) => ns,
204 fn defer_to_typeck(self) -> bool {
206 PathSource::Type | PathSource::Expr(..) | PathSource::Pat |
207 PathSource::Struct | PathSource::TupleStruct => true,
208 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
212 fn descr_expected(self) -> &'static str {
214 PathSource::Type => "type",
215 PathSource::Trait(_) => "trait",
216 PathSource::Pat => "unit struct/variant or constant",
217 PathSource::Struct => "struct, variant or union type",
218 PathSource::TupleStruct => "tuple struct/variant",
219 PathSource::TraitItem(ns) => match ns {
220 TypeNS => "associated type",
221 ValueNS => "method or associated constant",
222 MacroNS => bug!("associated macro"),
224 PathSource::Expr(parent) => match parent.map(|p| &p.node) {
225 // "function" here means "anything callable" rather than `DefKind::Fn`,
226 // this is not precise but usually more helpful than just "value".
227 Some(&ExprKind::Call(..)) => "function",
233 crate fn is_expected(self, res: Res) -> bool {
235 PathSource::Type => match res {
236 Res::Def(DefKind::Struct, _)
237 | Res::Def(DefKind::Union, _)
238 | Res::Def(DefKind::Enum, _)
239 | Res::Def(DefKind::Trait, _)
240 | Res::Def(DefKind::TraitAlias, _)
241 | Res::Def(DefKind::TyAlias, _)
242 | Res::Def(DefKind::AssocTy, _)
244 | Res::Def(DefKind::TyParam, _)
246 | Res::Def(DefKind::OpaqueTy, _)
247 | Res::Def(DefKind::ForeignTy, _) => true,
250 PathSource::Trait(AliasPossibility::No) => match res {
251 Res::Def(DefKind::Trait, _) => true,
254 PathSource::Trait(AliasPossibility::Maybe) => match res {
255 Res::Def(DefKind::Trait, _) => true,
256 Res::Def(DefKind::TraitAlias, _) => true,
259 PathSource::Expr(..) => match res {
260 Res::Def(DefKind::Ctor(_, CtorKind::Const), _)
261 | Res::Def(DefKind::Ctor(_, CtorKind::Fn), _)
262 | Res::Def(DefKind::Const, _)
263 | Res::Def(DefKind::Static, _)
265 | Res::Def(DefKind::Fn, _)
266 | Res::Def(DefKind::Method, _)
267 | Res::Def(DefKind::AssocConst, _)
269 | Res::Def(DefKind::ConstParam, _) => true,
272 PathSource::Pat => match res {
273 Res::Def(DefKind::Ctor(_, CtorKind::Const), _) |
274 Res::Def(DefKind::Const, _) | Res::Def(DefKind::AssocConst, _) |
275 Res::SelfCtor(..) => true,
278 PathSource::TupleStruct => match res {
279 Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) | Res::SelfCtor(..) => true,
282 PathSource::Struct => match res {
283 Res::Def(DefKind::Struct, _)
284 | Res::Def(DefKind::Union, _)
285 | Res::Def(DefKind::Variant, _)
286 | Res::Def(DefKind::TyAlias, _)
287 | Res::Def(DefKind::AssocTy, _)
288 | Res::SelfTy(..) => true,
291 PathSource::TraitItem(ns) => match res {
292 Res::Def(DefKind::AssocConst, _)
293 | Res::Def(DefKind::Method, _) if ns == ValueNS => true,
294 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
300 fn error_code(self, has_unexpected_resolution: bool) -> &'static str {
301 syntax::diagnostic_used!(E0404);
302 syntax::diagnostic_used!(E0405);
303 syntax::diagnostic_used!(E0412);
304 syntax::diagnostic_used!(E0422);
305 syntax::diagnostic_used!(E0423);
306 syntax::diagnostic_used!(E0425);
307 syntax::diagnostic_used!(E0531);
308 syntax::diagnostic_used!(E0532);
309 syntax::diagnostic_used!(E0573);
310 syntax::diagnostic_used!(E0574);
311 syntax::diagnostic_used!(E0575);
312 syntax::diagnostic_used!(E0576);
313 match (self, has_unexpected_resolution) {
314 (PathSource::Trait(_), true) => "E0404",
315 (PathSource::Trait(_), false) => "E0405",
316 (PathSource::Type, true) => "E0573",
317 (PathSource::Type, false) => "E0412",
318 (PathSource::Struct, true) => "E0574",
319 (PathSource::Struct, false) => "E0422",
320 (PathSource::Expr(..), true) => "E0423",
321 (PathSource::Expr(..), false) => "E0425",
322 (PathSource::Pat, true) | (PathSource::TupleStruct, true) => "E0532",
323 (PathSource::Pat, false) | (PathSource::TupleStruct, false) => "E0531",
324 (PathSource::TraitItem(..), true) => "E0575",
325 (PathSource::TraitItem(..), false) => "E0576",
330 struct LateResolutionVisitor<'a, 'b> {
331 r: &'b mut Resolver<'a>,
333 /// The module that represents the current item scope.
334 parent_scope: ParentScope<'a>,
336 /// The current set of local scopes for types and values.
337 /// FIXME #4948: Reuse ribs to avoid allocation.
338 ribs: PerNS<Vec<Rib<'a>>>,
340 /// The current set of local scopes, for labels.
341 label_ribs: Vec<Rib<'a, NodeId>>,
343 /// The trait that the current context can refer to.
344 current_trait_ref: Option<(Module<'a>, TraitRef)>,
346 /// The current trait's associated types' ident, used for diagnostic suggestions.
347 current_trait_assoc_types: Vec<Ident>,
349 /// The current self type if inside an impl (used for better errors).
350 current_self_type: Option<Ty>,
352 /// The current self item if inside an ADT (used for better errors).
353 current_self_item: Option<NodeId>,
355 /// A list of labels as of yet unused. Labels will be removed from this map when
356 /// they are used (in a `break` or `continue` statement)
357 unused_labels: FxHashMap<NodeId, Span>,
359 /// Only used for better errors on `fn(): fn()`.
360 current_type_ascription: Vec<Span>,
363 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
364 impl<'a, 'tcx> Visitor<'tcx> for LateResolutionVisitor<'a, '_> {
365 fn visit_item(&mut self, item: &'tcx Item) {
366 self.resolve_item(item);
368 fn visit_arm(&mut self, arm: &'tcx Arm) {
369 self.resolve_arm(arm);
371 fn visit_block(&mut self, block: &'tcx Block) {
372 self.resolve_block(block);
374 fn visit_anon_const(&mut self, constant: &'tcx AnonConst) {
375 debug!("visit_anon_const {:?}", constant);
376 self.with_constant_rib(|this| {
377 visit::walk_anon_const(this, constant);
380 fn visit_expr(&mut self, expr: &'tcx Expr) {
381 self.resolve_expr(expr, None);
383 fn visit_local(&mut self, local: &'tcx Local) {
384 self.resolve_local(local);
386 fn visit_ty(&mut self, ty: &'tcx Ty) {
388 TyKind::Path(ref qself, ref path) => {
389 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
391 TyKind::ImplicitSelf => {
392 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
393 let res = self.resolve_ident_in_lexical_scope(self_ty, TypeNS, Some(ty.id), ty.span)
394 .map_or(Res::Err, |d| d.res());
395 self.r.record_partial_res(ty.id, PartialRes::new(res));
399 visit::walk_ty(self, ty);
401 fn visit_poly_trait_ref(&mut self,
402 tref: &'tcx PolyTraitRef,
403 m: &'tcx TraitBoundModifier) {
404 self.smart_resolve_path(tref.trait_ref.ref_id, None,
405 &tref.trait_ref.path, PathSource::Trait(AliasPossibility::Maybe));
406 visit::walk_poly_trait_ref(self, tref, m);
408 fn visit_foreign_item(&mut self, foreign_item: &'tcx ForeignItem) {
409 let generic_params = match foreign_item.node {
410 ForeignItemKind::Fn(_, ref generics) => {
411 HasGenericParams(generics, ItemRibKind)
413 ForeignItemKind::Static(..) => NoGenericParams,
414 ForeignItemKind::Ty => NoGenericParams,
415 ForeignItemKind::Macro(..) => NoGenericParams,
417 self.with_generic_param_rib(generic_params, |this| {
418 visit::walk_foreign_item(this, foreign_item);
421 fn visit_fn(&mut self, fn_kind: FnKind<'tcx>, declaration: &'tcx FnDecl, _: Span, _: NodeId) {
422 debug!("(resolving function) entering function");
423 let rib_kind = match fn_kind {
424 FnKind::ItemFn(..) => FnItemRibKind,
425 FnKind::Method(..) | FnKind::Closure(_) => NormalRibKind,
428 // Create a value rib for the function.
429 self.with_rib(ValueNS, rib_kind, |this| {
430 // Create a label rib for the function.
431 this.with_label_rib(rib_kind, |this| {
432 // Add each argument to the rib.
433 this.resolve_params(&declaration.inputs);
435 visit::walk_fn_ret_ty(this, &declaration.output);
437 // Resolve the function body, potentially inside the body of an async closure
439 FnKind::ItemFn(.., body) |
440 FnKind::Method(.., body) => this.visit_block(body),
441 FnKind::Closure(body) => this.visit_expr(body),
444 debug!("(resolving function) leaving function");
449 fn visit_generics(&mut self, generics: &'tcx Generics) {
450 // For type parameter defaults, we have to ban access
451 // to following type parameters, as the InternalSubsts can only
452 // provide previous type parameters as they're built. We
453 // put all the parameters on the ban list and then remove
454 // them one by one as they are processed and become available.
455 let mut default_ban_rib = Rib::new(ForwardTyParamBanRibKind);
456 let mut found_default = false;
457 default_ban_rib.bindings.extend(generics.params.iter()
458 .filter_map(|param| match param.kind {
459 GenericParamKind::Const { .. } |
460 GenericParamKind::Lifetime { .. } => None,
461 GenericParamKind::Type { ref default, .. } => {
462 found_default |= default.is_some();
464 Some((Ident::with_dummy_span(param.ident.name), Res::Err))
471 // We also ban access to type parameters for use as the types of const parameters.
472 let mut const_ty_param_ban_rib = Rib::new(TyParamAsConstParamTy);
473 const_ty_param_ban_rib.bindings.extend(generics.params.iter()
475 if let GenericParamKind::Type { .. } = param.kind {
481 .map(|param| (Ident::with_dummy_span(param.ident.name), Res::Err)));
483 for param in &generics.params {
485 GenericParamKind::Lifetime { .. } => self.visit_generic_param(param),
486 GenericParamKind::Type { ref default, .. } => {
487 for bound in ¶m.bounds {
488 self.visit_param_bound(bound);
491 if let Some(ref ty) = default {
492 self.ribs[TypeNS].push(default_ban_rib);
494 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
497 // Allow all following defaults to refer to this type parameter.
498 default_ban_rib.bindings.remove(&Ident::with_dummy_span(param.ident.name));
500 GenericParamKind::Const { ref ty } => {
501 self.ribs[TypeNS].push(const_ty_param_ban_rib);
503 for bound in ¶m.bounds {
504 self.visit_param_bound(bound);
509 const_ty_param_ban_rib = self.ribs[TypeNS].pop().unwrap();
513 for p in &generics.where_clause.predicates {
514 self.visit_where_predicate(p);
519 impl<'a, 'b> LateResolutionVisitor<'a, '_> {
520 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b> {
521 // During late resolution we only track the module component of the parent scope,
522 // although it may be useful to track other components as well for diagnostics.
523 let graph_root = resolver.graph_root;
524 let parent_scope = ParentScope::module(graph_root);
525 let start_rib_kind = ModuleRibKind(graph_root);
526 LateResolutionVisitor {
530 value_ns: vec![Rib::new(start_rib_kind)],
531 type_ns: vec![Rib::new(start_rib_kind)],
532 macro_ns: vec![Rib::new(start_rib_kind)],
534 label_ribs: Vec::new(),
535 current_trait_ref: None,
536 current_trait_assoc_types: Vec::new(),
537 current_self_type: None,
538 current_self_item: None,
539 unused_labels: Default::default(),
540 current_type_ascription: Vec::new(),
544 fn resolve_ident_in_lexical_scope(&mut self,
547 record_used_id: Option<NodeId>,
549 -> Option<LexicalScopeBinding<'a>> {
550 self.r.resolve_ident_in_lexical_scope(
551 ident, ns, &self.parent_scope, record_used_id, path_span, &self.ribs[ns]
558 opt_ns: Option<Namespace>, // `None` indicates a module path in import
561 crate_lint: CrateLint,
562 ) -> PathResult<'a> {
563 self.r.resolve_path_with_ribs(
564 path, opt_ns, &self.parent_scope, record_used, path_span, crate_lint, Some(&self.ribs)
570 // We maintain a list of value ribs and type ribs.
572 // Simultaneously, we keep track of the current position in the module
573 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
574 // the value or type namespaces, we first look through all the ribs and
575 // then query the module graph. When we resolve a name in the module
576 // namespace, we can skip all the ribs (since nested modules are not
577 // allowed within blocks in Rust) and jump straight to the current module
580 // Named implementations are handled separately. When we find a method
581 // call, we consult the module node to find all of the implementations in
582 // scope. This information is lazily cached in the module node. We then
583 // generate a fake "implementation scope" containing all the
584 // implementations thus found, for compatibility with old resolve pass.
586 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
591 work: impl FnOnce(&mut Self) -> T,
593 self.ribs[ns].push(Rib::new(kind));
594 let ret = work(self);
599 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
600 let id = self.r.definitions.local_def_id(id);
601 let module = self.r.module_map.get(&id).cloned(); // clones a reference
602 if let Some(module) = module {
603 // Move down in the graph.
604 let orig_module = replace(&mut self.parent_scope.module, module);
605 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
606 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
608 this.parent_scope.module = orig_module;
617 /// Searches the current set of local scopes for labels. Returns the first non-`None` label that
618 /// is returned by the given predicate function
620 /// Stops after meeting a closure.
621 fn search_label<P, R>(&self, mut ident: Ident, pred: P) -> Option<R>
622 where P: Fn(&Rib<'_, NodeId>, Ident) -> Option<R>
624 for rib in self.label_ribs.iter().rev() {
627 // If an invocation of this macro created `ident`, give up on `ident`
628 // and switch to `ident`'s source from the macro definition.
629 MacroDefinition(def) => {
630 if def == self.r.macro_def(ident.span.ctxt()) {
631 ident.span.remove_mark();
635 // Do not resolve labels across function boundary
639 let r = pred(rib, ident);
647 fn resolve_adt(&mut self, item: &Item, generics: &Generics) {
648 debug!("resolve_adt");
649 self.with_current_self_item(item, |this| {
650 this.with_generic_param_rib(HasGenericParams(generics, ItemRibKind), |this| {
651 let item_def_id = this.r.definitions.local_def_id(item.id);
652 this.with_self_rib(Res::SelfTy(None, Some(item_def_id)), |this| {
653 visit::walk_item(this, item);
659 fn future_proof_import(&mut self, use_tree: &UseTree) {
660 let segments = &use_tree.prefix.segments;
661 if !segments.is_empty() {
662 let ident = segments[0].ident;
663 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
667 let nss = match use_tree.kind {
668 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
671 let report_error = |this: &Self, ns| {
672 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
673 this.r.session.span_err(ident.span, &format!("imports cannot refer to {}", what));
677 match self.resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span) {
678 Some(LexicalScopeBinding::Res(..)) => {
679 report_error(self, ns);
681 Some(LexicalScopeBinding::Item(binding)) => {
682 let orig_blacklisted_binding =
683 replace(&mut self.r.blacklisted_binding, Some(binding));
684 if let Some(LexicalScopeBinding::Res(..)) =
685 self.resolve_ident_in_lexical_scope(ident, ns, None,
686 use_tree.prefix.span) {
687 report_error(self, ns);
689 self.r.blacklisted_binding = orig_blacklisted_binding;
694 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
695 for (use_tree, _) in use_trees {
696 self.future_proof_import(use_tree);
701 fn resolve_item(&mut self, item: &Item) {
702 let name = item.ident.name;
703 debug!("(resolving item) resolving {} ({:?})", name, item.node);
706 ItemKind::TyAlias(_, ref generics) |
707 ItemKind::OpaqueTy(_, ref generics) |
708 ItemKind::Fn(_, _, ref generics, _) => {
709 self.with_generic_param_rib(
710 HasGenericParams(generics, ItemRibKind),
711 |this| visit::walk_item(this, item)
715 ItemKind::Enum(_, ref generics) |
716 ItemKind::Struct(_, ref generics) |
717 ItemKind::Union(_, ref generics) => {
718 self.resolve_adt(item, generics);
721 ItemKind::Impl(.., ref generics, ref opt_trait_ref, ref self_type, ref impl_items) =>
722 self.resolve_implementation(generics,
728 ItemKind::Trait(.., ref generics, ref bounds, ref trait_items) => {
729 // Create a new rib for the trait-wide type parameters.
730 self.with_generic_param_rib(HasGenericParams(generics, ItemRibKind), |this| {
731 let local_def_id = this.r.definitions.local_def_id(item.id);
732 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
733 this.visit_generics(generics);
734 walk_list!(this, visit_param_bound, bounds);
736 for trait_item in trait_items {
737 this.with_trait_items(trait_items, |this| {
738 let generic_params = HasGenericParams(
739 &trait_item.generics,
742 this.with_generic_param_rib(generic_params, |this| {
743 match trait_item.node {
744 TraitItemKind::Const(ref ty, ref default) => {
747 // Only impose the restrictions of
748 // ConstRibKind for an actual constant
749 // expression in a provided default.
750 if let Some(ref expr) = *default{
751 this.with_constant_rib(|this| {
752 this.visit_expr(expr);
756 TraitItemKind::Method(_, _) => {
757 visit::walk_trait_item(this, trait_item)
759 TraitItemKind::Type(..) => {
760 visit::walk_trait_item(this, trait_item)
762 TraitItemKind::Macro(_) => {
763 panic!("unexpanded macro in resolve!")
773 ItemKind::TraitAlias(ref generics, ref bounds) => {
774 // Create a new rib for the trait-wide type parameters.
775 self.with_generic_param_rib(HasGenericParams(generics, ItemRibKind), |this| {
776 let local_def_id = this.r.definitions.local_def_id(item.id);
777 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
778 this.visit_generics(generics);
779 walk_list!(this, visit_param_bound, bounds);
784 ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
785 self.with_scope(item.id, |this| {
786 visit::walk_item(this, item);
790 ItemKind::Static(ref ty, _, ref expr) |
791 ItemKind::Const(ref ty, ref expr) => {
792 debug!("resolve_item ItemKind::Const");
793 self.with_item_rib(|this| {
795 this.with_constant_rib(|this| {
796 this.visit_expr(expr);
801 ItemKind::Use(ref use_tree) => {
802 self.future_proof_import(use_tree);
805 ItemKind::ExternCrate(..) |
806 ItemKind::MacroDef(..) | ItemKind::GlobalAsm(..) => {
807 // do nothing, these are just around to be encoded
810 ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
814 fn with_generic_param_rib<'c, F>(&'c mut self, generic_params: GenericParameters<'a, 'c>, f: F)
815 where F: FnOnce(&mut Self)
817 debug!("with_generic_param_rib");
818 match generic_params {
819 HasGenericParams(generics, rib_kind) => {
820 let mut function_type_rib = Rib::new(rib_kind);
821 let mut function_value_rib = Rib::new(rib_kind);
822 let mut seen_bindings = FxHashMap::default();
823 // We also can't shadow bindings from the parent item
824 if let AssocItemRibKind = rib_kind {
825 let mut add_bindings_for_ns = |ns| {
826 let parent_rib = self.ribs[ns].iter()
827 .rfind(|rib| if let ItemRibKind = rib.kind { true } else { false })
828 .expect("associated item outside of an item");
829 seen_bindings.extend(
830 parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)),
833 add_bindings_for_ns(ValueNS);
834 add_bindings_for_ns(TypeNS);
836 for param in &generics.params {
838 GenericParamKind::Lifetime { .. } => {}
839 GenericParamKind::Type { .. } => {
840 let ident = param.ident.modern();
841 debug!("with_generic_param_rib: {}", param.id);
843 if seen_bindings.contains_key(&ident) {
844 let span = seen_bindings.get(&ident).unwrap();
845 let err = ResolutionError::NameAlreadyUsedInParameterList(
849 self.r.report_error(param.ident.span, err);
851 seen_bindings.entry(ident).or_insert(param.ident.span);
853 // Plain insert (no renaming).
856 self.r.definitions.local_def_id(param.id),
858 function_type_rib.bindings.insert(ident, res);
859 self.r.record_partial_res(param.id, PartialRes::new(res));
861 GenericParamKind::Const { .. } => {
862 let ident = param.ident.modern();
863 debug!("with_generic_param_rib: {}", param.id);
865 if seen_bindings.contains_key(&ident) {
866 let span = seen_bindings.get(&ident).unwrap();
867 let err = ResolutionError::NameAlreadyUsedInParameterList(
871 self.r.report_error(param.ident.span, err);
873 seen_bindings.entry(ident).or_insert(param.ident.span);
877 self.r.definitions.local_def_id(param.id),
879 function_value_rib.bindings.insert(ident, res);
880 self.r.record_partial_res(param.id, PartialRes::new(res));
884 self.ribs[ValueNS].push(function_value_rib);
885 self.ribs[TypeNS].push(function_type_rib);
895 if let HasGenericParams(..) = generic_params {
896 self.ribs[TypeNS].pop();
897 self.ribs[ValueNS].pop();
901 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
902 self.label_ribs.push(Rib::new(kind));
904 self.label_ribs.pop();
907 fn with_item_rib(&mut self, f: impl FnOnce(&mut Self)) {
908 self.with_rib(ValueNS, ItemRibKind, |this| this.with_rib(TypeNS, ItemRibKind, f))
911 fn with_constant_rib(&mut self, f: impl FnOnce(&mut Self)) {
912 debug!("with_constant_rib");
913 self.with_rib(ValueNS, ConstantItemRibKind, |this| {
914 this.with_label_rib(ConstantItemRibKind, f);
918 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
919 // Handle nested impls (inside fn bodies)
920 let previous_value = replace(&mut self.current_self_type, Some(self_type.clone()));
921 let result = f(self);
922 self.current_self_type = previous_value;
926 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
927 let previous_value = replace(&mut self.current_self_item, Some(self_item.id));
928 let result = f(self);
929 self.current_self_item = previous_value;
933 /// When evaluating a `trait` use its associated types' idents for suggestionsa in E0412.
934 fn with_trait_items<T>(
936 trait_items: &Vec<TraitItem>,
937 f: impl FnOnce(&mut Self) -> T,
939 let trait_assoc_types = replace(
940 &mut self.current_trait_assoc_types,
941 trait_items.iter().filter_map(|item| match &item.node {
942 TraitItemKind::Type(bounds, _) if bounds.len() == 0 => Some(item.ident),
946 let result = f(self);
947 self.current_trait_assoc_types = trait_assoc_types;
951 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
952 fn with_optional_trait_ref<T>(
954 opt_trait_ref: Option<&TraitRef>,
955 f: impl FnOnce(&mut Self, Option<DefId>) -> T
957 let mut new_val = None;
958 let mut new_id = None;
959 if let Some(trait_ref) = opt_trait_ref {
960 let path: Vec<_> = Segment::from_path(&trait_ref.path);
961 let res = self.smart_resolve_path_fragment(
966 PathSource::Trait(AliasPossibility::No),
967 CrateLint::SimplePath(trait_ref.ref_id),
970 new_id = Some(res.def_id());
971 let span = trait_ref.path.span;
972 if let PathResult::Module(ModuleOrUniformRoot::Module(module)) =
978 CrateLint::SimplePath(trait_ref.ref_id),
981 new_val = Some((module, trait_ref.clone()));
985 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
986 let result = f(self, new_id);
987 self.current_trait_ref = original_trait_ref;
991 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
992 let mut self_type_rib = Rib::new(NormalRibKind);
994 // Plain insert (no renaming, since types are not currently hygienic)
995 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
996 self.ribs[ns].push(self_type_rib);
1001 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
1002 self.with_self_rib_ns(TypeNS, self_res, f)
1005 fn resolve_implementation(&mut self,
1006 generics: &Generics,
1007 opt_trait_reference: &Option<TraitRef>,
1010 impl_items: &[ImplItem]) {
1011 debug!("resolve_implementation");
1012 // If applicable, create a rib for the type parameters.
1013 self.with_generic_param_rib(HasGenericParams(generics, ItemRibKind), |this| {
1014 // Dummy self type for better errors if `Self` is used in the trait path.
1015 this.with_self_rib(Res::SelfTy(None, None), |this| {
1016 // Resolve the trait reference, if necessary.
1017 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1018 let item_def_id = this.r.definitions.local_def_id(item_id);
1019 this.with_self_rib(Res::SelfTy(trait_id, Some(item_def_id)), |this| {
1020 if let Some(trait_ref) = opt_trait_reference.as_ref() {
1021 // Resolve type arguments in the trait path.
1022 visit::walk_trait_ref(this, trait_ref);
1024 // Resolve the self type.
1025 this.visit_ty(self_type);
1026 // Resolve the generic parameters.
1027 this.visit_generics(generics);
1028 // Resolve the items within the impl.
1029 this.with_current_self_type(self_type, |this| {
1030 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
1031 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
1032 for impl_item in impl_items {
1033 // We also need a new scope for the impl item type parameters.
1034 let generic_params = HasGenericParams(&impl_item.generics,
1036 this.with_generic_param_rib(generic_params, |this| {
1037 use crate::ResolutionError::*;
1038 match impl_item.node {
1039 ImplItemKind::Const(..) => {
1041 "resolve_implementation ImplItemKind::Const",
1043 // If this is a trait impl, ensure the const
1045 this.check_trait_item(
1049 |n, s| ConstNotMemberOfTrait(n, s),
1052 this.with_constant_rib(|this| {
1053 visit::walk_impl_item(this, impl_item)
1056 ImplItemKind::Method(..) => {
1057 // If this is a trait impl, ensure the method
1059 this.check_trait_item(impl_item.ident,
1062 |n, s| MethodNotMemberOfTrait(n, s));
1064 visit::walk_impl_item(this, impl_item);
1066 ImplItemKind::TyAlias(ref ty) => {
1067 // If this is a trait impl, ensure the type
1069 this.check_trait_item(impl_item.ident,
1072 |n, s| TypeNotMemberOfTrait(n, s));
1076 ImplItemKind::OpaqueTy(ref bounds) => {
1077 // If this is a trait impl, ensure the type
1079 this.check_trait_item(impl_item.ident,
1082 |n, s| TypeNotMemberOfTrait(n, s));
1084 for bound in bounds {
1085 this.visit_param_bound(bound);
1088 ImplItemKind::Macro(_) =>
1089 panic!("unexpanded macro in resolve!"),
1101 fn check_trait_item<F>(&mut self, ident: Ident, ns: Namespace, span: Span, err: F)
1102 where F: FnOnce(Name, &str) -> ResolutionError<'_>
1104 // If there is a TraitRef in scope for an impl, then the method must be in the
1106 if let Some((module, _)) = self.current_trait_ref {
1107 if self.r.resolve_ident_in_module(
1108 ModuleOrUniformRoot::Module(module),
1115 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
1116 self.r.report_error(span, err(ident.name, &path_names_to_string(path)));
1121 fn resolve_params(&mut self, params: &[Param]) {
1122 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1123 for Param { pat, ty, .. } in params {
1124 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1126 debug!("(resolving function / closure) recorded parameter");
1130 fn resolve_local(&mut self, local: &Local) {
1131 // Resolve the type.
1132 walk_list!(self, visit_ty, &local.ty);
1134 // Resolve the initializer.
1135 walk_list!(self, visit_expr, &local.init);
1137 // Resolve the pattern.
1138 self.resolve_pattern_top(&local.pat, PatternSource::Let);
1141 /// build a map from pattern identifiers to binding-info's.
1142 /// this is done hygienically. This could arise for a macro
1143 /// that expands into an or-pattern where one 'x' was from the
1144 /// user and one 'x' came from the macro.
1145 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1146 let mut binding_map = FxHashMap::default();
1148 pat.walk(&mut |pat| {
1150 PatKind::Ident(binding_mode, ident, ref sub_pat)
1151 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
1153 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
1155 PatKind::Or(ref ps) => {
1156 // Check the consistency of this or-pattern and
1157 // then add all bindings to the larger map.
1158 for bm in self.check_consistent_bindings(ps) {
1159 binding_map.extend(bm);
1172 fn is_base_res_local(&self, nid: NodeId) -> bool {
1173 match self.r.partial_res_map.get(&nid).map(|res| res.base_res()) {
1174 Some(Res::Local(..)) => true,
1179 /// Checks that all of the arms in an or-pattern have exactly the
1180 /// same set of bindings, with the same binding modes for each.
1181 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
1182 let mut missing_vars = FxHashMap::default();
1183 let mut inconsistent_vars = FxHashMap::default();
1185 // 1) Compute the binding maps of all arms.
1186 let maps = pats.iter()
1187 .map(|pat| self.binding_mode_map(pat))
1188 .collect::<Vec<_>>();
1190 // 2) Record any missing bindings or binding mode inconsistencies.
1191 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
1192 // Check against all arms except for the same pattern which is always self-consistent.
1193 let inners = pats.iter().enumerate()
1194 .filter(|(_, pat)| pat.id != pat_outer.id)
1195 .flat_map(|(idx, _)| maps[idx].iter())
1196 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
1198 for (name, info, &binding_inner) in inners {
1200 None => { // The inner binding is missing in the outer.
1201 let binding_error = missing_vars
1203 .or_insert_with(|| BindingError {
1205 origin: BTreeSet::new(),
1206 target: BTreeSet::new(),
1207 could_be_path: name.as_str().starts_with(char::is_uppercase),
1209 binding_error.origin.insert(binding_inner.span);
1210 binding_error.target.insert(pat_outer.span);
1212 Some(binding_outer) => {
1213 if binding_outer.binding_mode != binding_inner.binding_mode {
1214 // The binding modes in the outer and inner bindings differ.
1217 .or_insert((binding_inner.span, binding_outer.span));
1224 // 3) Report all missing variables we found.
1225 let mut missing_vars = missing_vars.iter_mut().collect::<Vec<_>>();
1226 missing_vars.sort();
1227 for (name, mut v) in missing_vars {
1228 if inconsistent_vars.contains_key(name) {
1229 v.could_be_path = false;
1231 self.r.report_error(
1232 *v.origin.iter().next().unwrap(),
1233 ResolutionError::VariableNotBoundInPattern(v));
1236 // 4) Report all inconsistencies in binding modes we found.
1237 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
1238 inconsistent_vars.sort();
1239 for (name, v) in inconsistent_vars {
1240 self.r.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
1243 // 5) Finally bubble up all the binding maps.
1247 /// Check the consistency of the outermost or-patterns.
1248 fn check_consistent_bindings_top(&mut self, pat: &Pat) {
1249 pat.walk(&mut |pat| match pat.node {
1250 PatKind::Or(ref ps) => {
1251 self.check_consistent_bindings(ps);
1258 fn resolve_arm(&mut self, arm: &Arm) {
1259 self.with_rib(ValueNS, NormalRibKind, |this| {
1260 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
1261 walk_list!(this, visit_expr, &arm.guard);
1262 this.visit_expr(&arm.body);
1266 /// Arising from `source`, resolve a top level pattern.
1267 fn resolve_pattern_top(&mut self, pat: &Pat, pat_src: PatternSource) {
1268 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1269 self.resolve_pattern(pat, pat_src, &mut bindings);
1275 pat_src: PatternSource,
1276 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1278 self.resolve_pattern_inner(pat, pat_src, bindings);
1279 // This has to happen *after* we determine which pat_idents are variants:
1280 self.check_consistent_bindings_top(pat);
1281 visit::walk_pat(self, pat);
1284 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
1288 /// A stack of sets of bindings accumulated.
1290 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
1291 /// be interpreted as re-binding an already bound binding. This results in an error.
1292 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
1293 /// in reusing this binding rather than creating a fresh one.
1295 /// When called at the top level, the stack must have a single element
1296 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
1297 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
1298 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
1299 /// When each `p_i` has been dealt with, the top set is merged with its parent.
1300 /// When a whole or-pattern has been dealt with, the thing happens.
1302 /// See the implementation and `fresh_binding` for more details.
1303 fn resolve_pattern_inner(
1306 pat_src: PatternSource,
1307 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1309 // Visit all direct subpatterns of this pattern.
1310 pat.walk(&mut |pat| {
1311 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.node);
1313 PatKind::Ident(bmode, ident, ref sub) => {
1314 // First try to resolve the identifier as some existing entity,
1315 // then fall back to a fresh binding.
1316 let has_sub = sub.is_some();
1317 let res = self.try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub)
1318 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
1319 self.r.record_partial_res(pat.id, PartialRes::new(res));
1321 PatKind::TupleStruct(ref path, ..) => {
1322 self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);
1324 PatKind::Path(ref qself, ref path) => {
1325 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
1327 PatKind::Struct(ref path, ..) => {
1328 self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
1330 PatKind::Or(ref ps) => {
1331 // Add a new set of bindings to the stack. `Or` here records that when a
1332 // binding already exists in this set, it should not result in an error because
1333 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
1334 bindings.push((PatBoundCtx::Or, Default::default()));
1336 // Now we need to switch back to a product context so that each
1337 // part of the or-pattern internally rejects already bound names.
1338 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
1339 bindings.push((PatBoundCtx::Product, Default::default()));
1340 self.resolve_pattern_inner(p, pat_src, bindings);
1341 // Move up the non-overlapping bindings to the or-pattern.
1342 // Existing bindings just get "merged".
1343 let collected = bindings.pop().unwrap().1;
1344 bindings.last_mut().unwrap().1.extend(collected);
1346 // This or-pattern itself can itself be part of a product,
1347 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
1348 // Both cases bind `a` again in a product pattern and must be rejected.
1349 let collected = bindings.pop().unwrap().1;
1350 bindings.last_mut().unwrap().1.extend(collected);
1352 // Prevent visiting `ps` as we've already done so above.
1365 pat_src: PatternSource,
1366 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1368 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
1369 // (We must not add it if it's in the bindings map because that breaks the assumptions
1370 // later passes make about or-patterns.)
1371 let ident = ident.modern_and_legacy();
1373 // Walk outwards the stack of products / or-patterns and
1374 // find out if the identifier has been bound in any of these.
1375 let mut already_bound_and = false;
1376 let mut already_bound_or = false;
1377 for (is_sum, set) in bindings.iter_mut().rev() {
1378 match (is_sum, set.get(&ident).cloned()) {
1379 // Already bound in a product pattern, e.g. `(a, a)` which is not allowed.
1380 (PatBoundCtx::Product, Some(..)) => already_bound_and = true,
1381 // Already bound in an or-pattern, e.g. `V1(a) | V2(a)`.
1382 // This is *required* for consistency which is checked later.
1383 (PatBoundCtx::Or, Some(..)) => already_bound_or = true,
1384 // Not already bound here.
1389 if already_bound_and {
1390 // Overlap in a product pattern somewhere; report an error.
1391 use ResolutionError::*;
1392 let error = match pat_src {
1393 // `fn f(a: u8, a: u8)`:
1394 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
1396 _ => IdentifierBoundMoreThanOnceInSamePattern,
1398 self.r.report_error(ident.span, error(&ident.as_str()));
1401 // Record as bound if it's valid:
1402 let ident_valid = ident.name != kw::Invalid;
1404 bindings.last_mut().unwrap().1.insert(ident);
1407 if already_bound_or {
1408 // `Variant1(a) | Variant2(a)`, ok
1409 // Reuse definition from the first `a`.
1410 self.innermost_rib_bindings(ValueNS)[&ident]
1412 let res = Res::Local(pat_id);
1414 // A completely fresh binding add to the set if it's valid.
1415 self.innermost_rib_bindings(ValueNS).insert(ident, res);
1421 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
1422 &mut self.ribs[ns].last_mut().unwrap().bindings
1425 fn try_resolve_as_non_binding(
1427 pat_src: PatternSource,
1433 let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, pat.span)?.item()?;
1434 let res = binding.res();
1436 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
1437 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
1438 // also be interpreted as a path to e.g. a constant, variant, etc.
1439 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Immutable);
1442 Res::Def(DefKind::Ctor(_, CtorKind::Const), _) |
1443 Res::Def(DefKind::Const, _) if is_syntactic_ambiguity => {
1444 // Disambiguate in favor of a unit struct/variant or constant pattern.
1445 self.r.record_use(ident, ValueNS, binding, false);
1448 Res::Def(DefKind::Ctor(..), _)
1449 | Res::Def(DefKind::Const, _)
1450 | Res::Def(DefKind::Static, _) => {
1451 // This is unambiguously a fresh binding, either syntactically
1452 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
1453 // to something unusable as a pattern (e.g., constructor function),
1454 // but we still conservatively report an error, see
1455 // issues/33118#issuecomment-233962221 for one reason why.
1456 self.r.report_error(
1458 ResolutionError::BindingShadowsSomethingUnacceptable(
1466 Res::Def(DefKind::Fn, _) | Res::Err => {
1467 // These entities are explicitly allowed to be shadowed by fresh bindings.
1471 span_bug!(ident.span, "unexpected resolution for an \
1472 identifier in pattern: {:?}", res);
1477 // High-level and context dependent path resolution routine.
1478 // Resolves the path and records the resolution into definition map.
1479 // If resolution fails tries several techniques to find likely
1480 // resolution candidates, suggest imports or other help, and report
1481 // errors in user friendly way.
1482 fn smart_resolve_path(&mut self,
1484 qself: Option<&QSelf>,
1486 source: PathSource<'_>) {
1487 self.smart_resolve_path_fragment(
1490 &Segment::from_path(path),
1493 CrateLint::SimplePath(id),
1497 fn smart_resolve_path_fragment(&mut self,
1499 qself: Option<&QSelf>,
1502 source: PathSource<'_>,
1503 crate_lint: CrateLint)
1505 let ns = source.namespace();
1506 let is_expected = &|res| source.is_expected(res);
1508 let report_errors = |this: &mut Self, res: Option<Res>| {
1509 let (err, candidates) = this.smart_resolve_report_errors(path, span, source, res);
1510 let def_id = this.parent_scope.module.normal_ancestor_id;
1511 let node_id = this.r.definitions.as_local_node_id(def_id).unwrap();
1512 let better = res.is_some();
1513 this.r.use_injections.push(UseError { err, candidates, node_id, better });
1514 PartialRes::new(Res::Err)
1517 let partial_res = match self.resolve_qpath_anywhere(
1523 source.defer_to_typeck(),
1526 Some(partial_res) if partial_res.unresolved_segments() == 0 => {
1527 if is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err {
1530 // Add a temporary hack to smooth the transition to new struct ctor
1531 // visibility rules. See #38932 for more details.
1533 if let Res::Def(DefKind::Struct, def_id) = partial_res.base_res() {
1534 if let Some((ctor_res, ctor_vis))
1535 = self.r.struct_constructors.get(&def_id).cloned() {
1536 if is_expected(ctor_res) &&
1537 self.r.is_accessible_from(ctor_vis, self.parent_scope.module) {
1538 let lint = lint::builtin::LEGACY_CONSTRUCTOR_VISIBILITY;
1539 self.r.session.buffer_lint(lint, id, span,
1540 "private struct constructors are not usable through \
1541 re-exports in outer modules",
1543 res = Some(PartialRes::new(ctor_res));
1548 res.unwrap_or_else(|| report_errors(self, Some(partial_res.base_res())))
1551 Some(partial_res) if source.defer_to_typeck() => {
1552 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
1553 // or `<T>::A::B`. If `B` should be resolved in value namespace then
1554 // it needs to be added to the trait map.
1556 let item_name = path.last().unwrap().ident;
1557 let traits = self.get_traits_containing_item(item_name, ns);
1558 self.r.trait_map.insert(id, traits);
1561 let mut std_path = vec![Segment::from_ident(Ident::with_dummy_span(sym::std))];
1562 std_path.extend(path);
1563 if self.r.primitive_type_table.primitive_types.contains_key(&path[0].ident.name) {
1564 let cl = CrateLint::No;
1566 if let PathResult::Module(_) | PathResult::NonModule(_) =
1567 self.resolve_path(&std_path, ns, false, span, cl) {
1568 // check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
1569 let item_span = path.iter().last().map(|segment| segment.ident.span)
1571 debug!("accessed item from `std` submodule as a bare type {:?}", std_path);
1572 let mut hm = self.r.session.confused_type_with_std_module.borrow_mut();
1573 hm.insert(item_span, span);
1574 // In some places (E0223) we only have access to the full path
1575 hm.insert(span, span);
1580 _ => report_errors(self, None)
1583 if let PathSource::TraitItem(..) = source {} else {
1584 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
1585 self.r.record_partial_res(id, partial_res);
1590 fn self_type_is_available(&mut self, span: Span) -> bool {
1591 let binding = self.resolve_ident_in_lexical_scope(
1592 Ident::with_dummy_span(kw::SelfUpper),
1597 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1600 fn self_value_is_available(&mut self, self_span: Span, path_span: Span) -> bool {
1601 let ident = Ident::new(kw::SelfLower, self_span);
1602 let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, path_span);
1603 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1606 // Resolve in alternative namespaces if resolution in the primary namespace fails.
1607 fn resolve_qpath_anywhere(
1610 qself: Option<&QSelf>,
1612 primary_ns: Namespace,
1614 defer_to_typeck: bool,
1615 crate_lint: CrateLint,
1616 ) -> Option<PartialRes> {
1617 let mut fin_res = None;
1618 for (i, ns) in [primary_ns, TypeNS, ValueNS].iter().cloned().enumerate() {
1619 if i == 0 || ns != primary_ns {
1620 match self.resolve_qpath(id, qself, path, ns, span, crate_lint) {
1621 // If defer_to_typeck, then resolution > no resolution,
1622 // otherwise full resolution > partial resolution > no resolution.
1623 Some(partial_res) if partial_res.unresolved_segments() == 0 ||
1625 return Some(partial_res),
1626 partial_res => if fin_res.is_none() { fin_res = partial_res },
1632 assert!(primary_ns != MacroNS);
1633 if qself.is_none() {
1634 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
1635 let path = Path { segments: path.iter().map(path_seg).collect(), span };
1636 if let Ok((_, res)) = self.r.resolve_macro_path(
1637 &path, None, &self.parent_scope, false, false
1639 return Some(PartialRes::new(res));
1646 /// Handles paths that may refer to associated items.
1650 qself: Option<&QSelf>,
1654 crate_lint: CrateLint,
1655 ) -> Option<PartialRes> {
1657 "resolve_qpath(id={:?}, qself={:?}, path={:?}, ns={:?}, span={:?})",
1665 if let Some(qself) = qself {
1666 if qself.position == 0 {
1667 // This is a case like `<T>::B`, where there is no
1668 // trait to resolve. In that case, we leave the `B`
1669 // segment to be resolved by type-check.
1670 return Some(PartialRes::with_unresolved_segments(
1671 Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX)), path.len()
1675 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
1677 // Currently, `path` names the full item (`A::B::C`, in
1678 // our example). so we extract the prefix of that that is
1679 // the trait (the slice upto and including
1680 // `qself.position`). And then we recursively resolve that,
1681 // but with `qself` set to `None`.
1683 // However, setting `qself` to none (but not changing the
1684 // span) loses the information about where this path
1685 // *actually* appears, so for the purposes of the crate
1686 // lint we pass along information that this is the trait
1687 // name from a fully qualified path, and this also
1688 // contains the full span (the `CrateLint::QPathTrait`).
1689 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
1690 let partial_res = self.smart_resolve_path_fragment(
1693 &path[..=qself.position],
1695 PathSource::TraitItem(ns),
1696 CrateLint::QPathTrait {
1698 qpath_span: qself.path_span,
1702 // The remaining segments (the `C` in our example) will
1703 // have to be resolved by type-check, since that requires doing
1704 // trait resolution.
1705 return Some(PartialRes::with_unresolved_segments(
1706 partial_res.base_res(),
1707 partial_res.unresolved_segments() + path.len() - qself.position - 1,
1711 let result = match self.resolve_path(&path, Some(ns), true, span, crate_lint) {
1712 PathResult::NonModule(path_res) => path_res,
1713 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
1714 PartialRes::new(module.res().unwrap())
1716 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
1717 // don't report an error right away, but try to fallback to a primitive type.
1718 // So, we are still able to successfully resolve something like
1720 // use std::u8; // bring module u8 in scope
1721 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
1722 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
1723 // // not to non-existent std::u8::max_value
1726 // Such behavior is required for backward compatibility.
1727 // The same fallback is used when `a` resolves to nothing.
1728 PathResult::Module(ModuleOrUniformRoot::Module(_)) |
1729 PathResult::Failed { .. }
1730 if (ns == TypeNS || path.len() > 1) &&
1731 self.r.primitive_type_table.primitive_types
1732 .contains_key(&path[0].ident.name) => {
1733 let prim = self.r.primitive_type_table.primitive_types[&path[0].ident.name];
1734 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
1736 PathResult::Module(ModuleOrUniformRoot::Module(module)) =>
1737 PartialRes::new(module.res().unwrap()),
1738 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
1739 self.r.report_error(span, ResolutionError::FailedToResolve { label, suggestion });
1740 PartialRes::new(Res::Err)
1742 PathResult::Module(..) | PathResult::Failed { .. } => return None,
1743 PathResult::Indeterminate => bug!("indetermined path result in resolve_qpath"),
1746 if path.len() > 1 && result.base_res() != Res::Err &&
1747 path[0].ident.name != kw::PathRoot &&
1748 path[0].ident.name != kw::DollarCrate {
1749 let unqualified_result = {
1750 match self.resolve_path(
1751 &[*path.last().unwrap()],
1757 PathResult::NonModule(path_res) => path_res.base_res(),
1758 PathResult::Module(ModuleOrUniformRoot::Module(module)) =>
1759 module.res().unwrap(),
1760 _ => return Some(result),
1763 if result.base_res() == unqualified_result {
1764 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
1765 self.r.session.buffer_lint(lint, id, span, "unnecessary qualification")
1772 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
1773 if let Some(label) = label {
1774 self.unused_labels.insert(id, label.ident.span);
1775 self.with_label_rib(NormalRibKind, |this| {
1776 let ident = label.ident.modern_and_legacy();
1777 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
1785 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &Block) {
1786 self.with_resolved_label(label, id, |this| this.visit_block(block));
1789 fn resolve_block(&mut self, block: &Block) {
1790 debug!("(resolving block) entering block");
1791 // Move down in the graph, if there's an anonymous module rooted here.
1792 let orig_module = self.parent_scope.module;
1793 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
1795 let mut num_macro_definition_ribs = 0;
1796 if let Some(anonymous_module) = anonymous_module {
1797 debug!("(resolving block) found anonymous module, moving down");
1798 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
1799 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
1800 self.parent_scope.module = anonymous_module;
1802 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
1805 // Descend into the block.
1806 for stmt in &block.stmts {
1807 if let StmtKind::Item(ref item) = stmt.node {
1808 if let ItemKind::MacroDef(..) = item.node {
1809 num_macro_definition_ribs += 1;
1810 let res = self.r.definitions.local_def_id(item.id);
1811 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
1812 self.label_ribs.push(Rib::new(MacroDefinition(res)));
1816 self.visit_stmt(stmt);
1820 self.parent_scope.module = orig_module;
1821 for _ in 0 .. num_macro_definition_ribs {
1822 self.ribs[ValueNS].pop();
1823 self.label_ribs.pop();
1825 self.ribs[ValueNS].pop();
1826 if anonymous_module.is_some() {
1827 self.ribs[TypeNS].pop();
1829 debug!("(resolving block) leaving block");
1832 fn resolve_expr(&mut self, expr: &Expr, parent: Option<&Expr>) {
1833 // First, record candidate traits for this expression if it could
1834 // result in the invocation of a method call.
1836 self.record_candidate_traits_for_expr_if_necessary(expr);
1838 // Next, resolve the node.
1840 ExprKind::Path(ref qself, ref path) => {
1841 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
1842 visit::walk_expr(self, expr);
1845 ExprKind::Struct(ref path, ..) => {
1846 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
1847 visit::walk_expr(self, expr);
1850 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
1851 let node_id = self.search_label(label.ident, |rib, ident| {
1852 rib.bindings.get(&ident.modern_and_legacy()).cloned()
1856 // Search again for close matches...
1857 // Picks the first label that is "close enough", which is not necessarily
1858 // the closest match
1859 let close_match = self.search_label(label.ident, |rib, ident| {
1860 let names = rib.bindings.iter().filter_map(|(id, _)| {
1861 if id.span.ctxt() == label.ident.span.ctxt() {
1867 find_best_match_for_name(names, &*ident.as_str(), None)
1869 self.r.record_partial_res(expr.id, PartialRes::new(Res::Err));
1870 self.r.report_error(
1872 ResolutionError::UndeclaredLabel(&label.ident.as_str(), close_match),
1876 // Since this res is a label, it is never read.
1877 self.r.label_res_map.insert(expr.id, node_id);
1878 self.unused_labels.remove(&node_id);
1882 // visit `break` argument if any
1883 visit::walk_expr(self, expr);
1886 ExprKind::Let(ref pat, ref scrutinee) => {
1887 self.visit_expr(scrutinee);
1888 self.resolve_pattern_top(pat, PatternSource::Let);
1891 ExprKind::If(ref cond, ref then, ref opt_else) => {
1892 self.with_rib(ValueNS, NormalRibKind, |this| {
1893 this.visit_expr(cond);
1894 this.visit_block(then);
1896 opt_else.as_ref().map(|expr| self.visit_expr(expr));
1899 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
1901 ExprKind::While(ref cond, ref block, label) => {
1902 self.with_resolved_label(label, expr.id, |this| {
1903 this.with_rib(ValueNS, NormalRibKind, |this| {
1904 this.visit_expr(cond);
1905 this.visit_block(block);
1910 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
1911 self.visit_expr(iter_expr);
1912 self.with_rib(ValueNS, NormalRibKind, |this| {
1913 this.resolve_pattern_top(pat, PatternSource::For);
1914 this.resolve_labeled_block(label, expr.id, block);
1918 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
1920 // Equivalent to `visit::walk_expr` + passing some context to children.
1921 ExprKind::Field(ref subexpression, _) => {
1922 self.resolve_expr(subexpression, Some(expr));
1924 ExprKind::MethodCall(ref segment, ref arguments) => {
1925 let mut arguments = arguments.iter();
1926 self.resolve_expr(arguments.next().unwrap(), Some(expr));
1927 for argument in arguments {
1928 self.resolve_expr(argument, None);
1930 self.visit_path_segment(expr.span, segment);
1933 ExprKind::Call(ref callee, ref arguments) => {
1934 self.resolve_expr(callee, Some(expr));
1935 for argument in arguments {
1936 self.resolve_expr(argument, None);
1939 ExprKind::Type(ref type_expr, _) => {
1940 self.current_type_ascription.push(type_expr.span);
1941 visit::walk_expr(self, expr);
1942 self.current_type_ascription.pop();
1944 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
1945 // resolve the arguments within the proper scopes so that usages of them inside the
1946 // closure are detected as upvars rather than normal closure arg usages.
1947 ExprKind::Closure(_, IsAsync::Async { .. }, _, ref fn_decl, ref body, _span) => {
1948 self.with_rib(ValueNS, NormalRibKind, |this| {
1949 // Resolve arguments:
1950 this.resolve_params(&fn_decl.inputs);
1951 // No need to resolve return type --
1952 // the outer closure return type is `FunctionRetTy::Default`.
1954 // Now resolve the inner closure
1956 // No need to resolve arguments: the inner closure has none.
1957 // Resolve the return type:
1958 visit::walk_fn_ret_ty(this, &fn_decl.output);
1960 this.visit_expr(body);
1965 visit::walk_expr(self, expr);
1970 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
1972 ExprKind::Field(_, ident) => {
1973 // FIXME(#6890): Even though you can't treat a method like a
1974 // field, we need to add any trait methods we find that match
1975 // the field name so that we can do some nice error reporting
1976 // later on in typeck.
1977 let traits = self.get_traits_containing_item(ident, ValueNS);
1978 self.r.trait_map.insert(expr.id, traits);
1980 ExprKind::MethodCall(ref segment, ..) => {
1981 debug!("(recording candidate traits for expr) recording traits for {}",
1983 let traits = self.get_traits_containing_item(segment.ident, ValueNS);
1984 self.r.trait_map.insert(expr.id, traits);
1992 fn get_traits_containing_item(&mut self, mut ident: Ident, ns: Namespace)
1993 -> Vec<TraitCandidate> {
1994 debug!("(getting traits containing item) looking for '{}'", ident.name);
1996 let mut found_traits = Vec::new();
1997 // Look for the current trait.
1998 if let Some((module, _)) = self.current_trait_ref {
1999 if self.r.resolve_ident_in_module(
2000 ModuleOrUniformRoot::Module(module),
2007 let def_id = module.def_id().unwrap();
2008 found_traits.push(TraitCandidate { def_id: def_id, import_ids: smallvec![] });
2012 ident.span = ident.span.modern();
2013 let mut search_module = self.parent_scope.module;
2015 self.get_traits_in_module_containing_item(ident, ns, search_module, &mut found_traits);
2016 search_module = unwrap_or!(
2017 self.r.hygienic_lexical_parent(search_module, &mut ident.span), break
2021 if let Some(prelude) = self.r.prelude {
2022 if !search_module.no_implicit_prelude {
2023 self.get_traits_in_module_containing_item(ident, ns, prelude, &mut found_traits);
2030 fn get_traits_in_module_containing_item(&mut self,
2034 found_traits: &mut Vec<TraitCandidate>) {
2035 assert!(ns == TypeNS || ns == ValueNS);
2036 let mut traits = module.traits.borrow_mut();
2037 if traits.is_none() {
2038 let mut collected_traits = Vec::new();
2039 module.for_each_child(self.r, |_, name, ns, binding| {
2040 if ns != TypeNS { return }
2041 match binding.res() {
2042 Res::Def(DefKind::Trait, _) |
2043 Res::Def(DefKind::TraitAlias, _) => collected_traits.push((name, binding)),
2047 *traits = Some(collected_traits.into_boxed_slice());
2050 for &(trait_name, binding) in traits.as_ref().unwrap().iter() {
2051 // Traits have pseudo-modules that can be used to search for the given ident.
2052 if let Some(module) = binding.module() {
2053 let mut ident = ident;
2054 if ident.span.glob_adjust(
2060 if self.r.resolve_ident_in_module_unadjusted(
2061 ModuleOrUniformRoot::Module(module),
2068 let import_ids = self.find_transitive_imports(&binding.kind, trait_name);
2069 let trait_def_id = module.def_id().unwrap();
2070 found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids });
2072 } else if let Res::Def(DefKind::TraitAlias, _) = binding.res() {
2073 // For now, just treat all trait aliases as possible candidates, since we don't
2074 // know if the ident is somewhere in the transitive bounds.
2075 let import_ids = self.find_transitive_imports(&binding.kind, trait_name);
2076 let trait_def_id = binding.res().def_id();
2077 found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids });
2079 bug!("candidate is not trait or trait alias?")
2084 fn find_transitive_imports(&mut self, mut kind: &NameBindingKind<'_>,
2085 trait_name: Ident) -> SmallVec<[NodeId; 1]> {
2086 let mut import_ids = smallvec![];
2087 while let NameBindingKind::Import { directive, binding, .. } = kind {
2088 self.r.maybe_unused_trait_imports.insert(directive.id);
2089 self.r.add_to_glob_map(&directive, trait_name);
2090 import_ids.push(directive.id);
2091 kind = &binding.kind;
2097 impl<'a> Resolver<'a> {
2098 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
2099 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
2100 visit::walk_crate(&mut late_resolution_visitor, krate);
2101 for (id, span) in late_resolution_visitor.unused_labels.iter() {
2102 self.session.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");