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::{bug, lint, span_bug};
15 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
16 use rustc_errors::DiagnosticId;
17 use rustc_hir::def::Namespace::{self, *};
18 use rustc_hir::def::{self, CtorKind, DefKind, PartialRes, PerNS};
19 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
20 use rustc_hir::TraitCandidate;
21 use rustc_span::symbol::{kw, sym};
23 use smallvec::{smallvec, SmallVec};
26 use syntax::util::lev_distance::find_best_match_for_name;
27 use syntax::visit::{self, FnKind, Visitor};
28 use syntax::{unwrap_or, walk_list};
31 use std::collections::BTreeSet;
32 use std::mem::replace;
34 use rustc_error_codes::*;
38 type Res = def::Res<NodeId>;
40 type IdentMap<T> = FxHashMap<Ident, T>;
42 /// Map from the name in a pattern to its binding mode.
43 type BindingMap = IdentMap<BindingInfo>;
45 #[derive(Copy, Clone, Debug)]
48 binding_mode: BindingMode,
51 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
60 fn descr(self) -> &'static str {
62 PatternSource::Match => "match binding",
63 PatternSource::Let => "let binding",
64 PatternSource::For => "for binding",
65 PatternSource::FnParam => "function parameter",
70 /// Denotes whether the context for the set of already bound bindings is a `Product`
71 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
72 /// See those functions for more information.
75 /// A product pattern context, e.g., `Variant(a, b)`.
77 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
81 /// Does this the item (from the item rib scope) allow generic parameters?
82 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
83 crate enum HasGenericParams {
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.
106 ItemRibKind(HasGenericParams),
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,
124 // Whether this rib kind contains generic parameters, as opposed to local
126 crate fn contains_params(&self) -> bool {
128 NormalRibKind | FnItemRibKind | ConstantItemRibKind | ModuleRibKind(_)
129 | MacroDefinition(_) => false,
130 AssocItemRibKind | ItemRibKind(_) | ForwardTyParamBanRibKind => true,
135 /// A single local scope.
137 /// A rib represents a scope names can live in. Note that these appear in many places, not just
138 /// around braces. At any place where the list of accessible names (of the given namespace)
139 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
140 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
143 /// Different [rib kinds](enum.RibKind) are transparent for different names.
145 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
146 /// resolving, the name is looked up from inside out.
148 crate struct Rib<'a, R = Res> {
149 pub bindings: IdentMap<R>,
150 pub kind: RibKind<'a>,
153 impl<'a, R> Rib<'a, R> {
154 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
155 Rib { bindings: Default::default(), kind }
159 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
160 crate enum AliasPossibility {
165 #[derive(Copy, Clone, Debug)]
166 crate enum PathSource<'a> {
167 // Type paths `Path`.
169 // Trait paths in bounds or impls.
170 Trait(AliasPossibility),
171 // Expression paths `path`, with optional parent context.
172 Expr(Option<&'a Expr>),
173 // Paths in path patterns `Path`.
175 // Paths in struct expressions and patterns `Path { .. }`.
177 // Paths in tuple struct patterns `Path(..)`.
179 // `m::A::B` in `<T as m::A>::B::C`.
180 TraitItem(Namespace),
183 impl<'a> PathSource<'a> {
184 fn namespace(self) -> Namespace {
186 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
187 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct => ValueNS,
188 PathSource::TraitItem(ns) => ns,
192 fn defer_to_typeck(self) -> bool {
195 | PathSource::Expr(..)
198 | PathSource::TupleStruct => true,
199 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
203 fn descr_expected(self) -> &'static str {
205 PathSource::Type => "type",
206 PathSource::Trait(_) => "trait",
207 PathSource::Pat => "unit struct, unit variant or constant",
208 PathSource::Struct => "struct, variant or union type",
209 PathSource::TupleStruct => "tuple struct or tuple variant",
210 PathSource::TraitItem(ns) => match ns {
211 TypeNS => "associated type",
212 ValueNS => "method or associated constant",
213 MacroNS => bug!("associated macro"),
215 PathSource::Expr(parent) => match &parent.as_ref().map(|p| &p.kind) {
216 // "function" here means "anything callable" rather than `DefKind::Fn`,
217 // this is not precise but usually more helpful than just "value".
218 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
219 ExprKind::Path(_, path) => {
220 let mut msg = "function";
221 if let Some(segment) = path.segments.iter().last() {
222 if let Some(c) = segment.ident.to_string().chars().next() {
223 if c.is_uppercase() {
224 msg = "function, tuple struct or tuple variant";
237 crate fn is_expected(self, res: Res) -> bool {
239 PathSource::Type => match res {
240 Res::Def(DefKind::Struct, _)
241 | Res::Def(DefKind::Union, _)
242 | Res::Def(DefKind::Enum, _)
243 | Res::Def(DefKind::Trait, _)
244 | Res::Def(DefKind::TraitAlias, _)
245 | Res::Def(DefKind::TyAlias, _)
246 | Res::Def(DefKind::AssocTy, _)
248 | Res::Def(DefKind::TyParam, _)
250 | Res::Def(DefKind::OpaqueTy, _)
251 | Res::Def(DefKind::ForeignTy, _) => true,
254 PathSource::Trait(AliasPossibility::No) => match res {
255 Res::Def(DefKind::Trait, _) => true,
258 PathSource::Trait(AliasPossibility::Maybe) => match res {
259 Res::Def(DefKind::Trait, _) => true,
260 Res::Def(DefKind::TraitAlias, _) => true,
263 PathSource::Expr(..) => match res {
264 Res::Def(DefKind::Ctor(_, CtorKind::Const), _)
265 | Res::Def(DefKind::Ctor(_, CtorKind::Fn), _)
266 | Res::Def(DefKind::Const, _)
267 | Res::Def(DefKind::Static, _)
269 | Res::Def(DefKind::Fn, _)
270 | Res::Def(DefKind::Method, _)
271 | Res::Def(DefKind::AssocConst, _)
273 | Res::Def(DefKind::ConstParam, _) => true,
276 PathSource::Pat => match res {
277 Res::Def(DefKind::Ctor(_, CtorKind::Const), _)
278 | Res::Def(DefKind::Const, _)
279 | Res::Def(DefKind::AssocConst, _)
280 | Res::SelfCtor(..) => true,
283 PathSource::TupleStruct => match res {
284 Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) | Res::SelfCtor(..) => true,
287 PathSource::Struct => match res {
288 Res::Def(DefKind::Struct, _)
289 | Res::Def(DefKind::Union, _)
290 | Res::Def(DefKind::Variant, _)
291 | Res::Def(DefKind::TyAlias, _)
292 | Res::Def(DefKind::AssocTy, _)
293 | Res::SelfTy(..) => true,
296 PathSource::TraitItem(ns) => match res {
297 Res::Def(DefKind::AssocConst, _) | Res::Def(DefKind::Method, _)
302 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
308 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
309 use rustc_errors::error_code;
310 match (self, has_unexpected_resolution) {
311 (PathSource::Trait(_), true) => error_code!(E0404),
312 (PathSource::Trait(_), false) => error_code!(E0405),
313 (PathSource::Type, true) => error_code!(E0573),
314 (PathSource::Type, false) => error_code!(E0412),
315 (PathSource::Struct, true) => error_code!(E0574),
316 (PathSource::Struct, false) => error_code!(E0422),
317 (PathSource::Expr(..), true) => error_code!(E0423),
318 (PathSource::Expr(..), false) => error_code!(E0425),
319 (PathSource::Pat, true) | (PathSource::TupleStruct, true) => error_code!(E0532),
320 (PathSource::Pat, false) | (PathSource::TupleStruct, false) => error_code!(E0531),
321 (PathSource::TraitItem(..), true) => error_code!(E0575),
322 (PathSource::TraitItem(..), false) => error_code!(E0576),
328 struct DiagnosticMetadata {
329 /// The current trait's associated types' ident, used for diagnostic suggestions.
330 current_trait_assoc_types: Vec<Ident>,
332 /// The current self type if inside an impl (used for better errors).
333 current_self_type: Option<Ty>,
335 /// The current self item if inside an ADT (used for better errors).
336 current_self_item: Option<NodeId>,
338 /// The current enclosing function (used for better errors).
339 current_function: Option<Span>,
341 /// A list of labels as of yet unused. Labels will be removed from this map when
342 /// they are used (in a `break` or `continue` statement)
343 unused_labels: FxHashMap<NodeId, Span>,
345 /// Only used for better errors on `fn(): fn()`.
346 current_type_ascription: Vec<Span>,
348 /// Only used for better errors on `let <pat>: <expr, not type>;`.
349 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
352 struct LateResolutionVisitor<'a, 'b> {
353 r: &'b mut Resolver<'a>,
355 /// The module that represents the current item scope.
356 parent_scope: ParentScope<'a>,
358 /// The current set of local scopes for types and values.
359 /// FIXME #4948: Reuse ribs to avoid allocation.
360 ribs: PerNS<Vec<Rib<'a>>>,
362 /// The current set of local scopes, for labels.
363 label_ribs: Vec<Rib<'a, NodeId>>,
365 /// The trait that the current context can refer to.
366 current_trait_ref: Option<(Module<'a>, TraitRef)>,
368 /// Fields used to add information to diagnostic errors.
369 diagnostic_metadata: DiagnosticMetadata,
372 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
373 impl<'a, 'tcx> Visitor<'tcx> for LateResolutionVisitor<'a, '_> {
374 fn visit_item(&mut self, item: &'tcx Item) {
375 self.resolve_item(item);
377 fn visit_arm(&mut self, arm: &'tcx Arm) {
378 self.resolve_arm(arm);
380 fn visit_block(&mut self, block: &'tcx Block) {
381 self.resolve_block(block);
383 fn visit_anon_const(&mut self, constant: &'tcx AnonConst) {
384 debug!("visit_anon_const {:?}", constant);
385 self.with_constant_rib(|this| {
386 visit::walk_anon_const(this, constant);
389 fn visit_expr(&mut self, expr: &'tcx Expr) {
390 self.resolve_expr(expr, None);
392 fn visit_local(&mut self, local: &'tcx Local) {
393 let local_spans = match local.pat.kind {
394 // We check for this to avoid tuple struct fields.
395 PatKind::Wild => None,
398 local.ty.as_ref().map(|ty| ty.span),
399 local.init.as_ref().map(|init| init.span),
402 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
403 self.resolve_local(local);
404 self.diagnostic_metadata.current_let_binding = original;
406 fn visit_ty(&mut self, ty: &'tcx Ty) {
408 TyKind::Path(ref qself, ref path) => {
409 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
411 TyKind::ImplicitSelf => {
412 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
414 .resolve_ident_in_lexical_scope(self_ty, TypeNS, Some(ty.id), ty.span)
415 .map_or(Res::Err, |d| d.res());
416 self.r.record_partial_res(ty.id, PartialRes::new(res));
420 visit::walk_ty(self, ty);
422 fn visit_poly_trait_ref(&mut self, tref: &'tcx PolyTraitRef, m: &'tcx TraitBoundModifier) {
423 self.smart_resolve_path(
424 tref.trait_ref.ref_id,
426 &tref.trait_ref.path,
427 PathSource::Trait(AliasPossibility::Maybe),
429 visit::walk_poly_trait_ref(self, tref, m);
431 fn visit_foreign_item(&mut self, foreign_item: &'tcx ForeignItem) {
432 match foreign_item.kind {
433 ForeignItemKind::Fn(_, ref generics) => {
434 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
435 visit::walk_foreign_item(this, foreign_item);
438 ForeignItemKind::Static(..) => {
439 self.with_item_rib(HasGenericParams::No, |this| {
440 visit::walk_foreign_item(this, foreign_item);
443 ForeignItemKind::Ty | ForeignItemKind::Macro(..) => {
444 visit::walk_foreign_item(self, foreign_item);
448 fn visit_fn(&mut self, fn_kind: FnKind<'tcx>, declaration: &'tcx FnDecl, sp: Span, _: NodeId) {
449 let previous_value = replace(&mut self.diagnostic_metadata.current_function, Some(sp));
450 debug!("(resolving function) entering function");
451 let rib_kind = match fn_kind {
452 FnKind::ItemFn(..) => FnItemRibKind,
453 FnKind::Method(..) | FnKind::Closure(_) => NormalRibKind,
456 // Create a value rib for the function.
457 self.with_rib(ValueNS, rib_kind, |this| {
458 // Create a label rib for the function.
459 this.with_label_rib(rib_kind, |this| {
460 // Add each argument to the rib.
461 this.resolve_params(&declaration.inputs);
463 visit::walk_fn_ret_ty(this, &declaration.output);
465 // Resolve the function body, potentially inside the body of an async closure
467 FnKind::ItemFn(.., body) | FnKind::Method(.., body) => this.visit_block(body),
468 FnKind::Closure(body) => this.visit_expr(body),
471 debug!("(resolving function) leaving function");
474 self.diagnostic_metadata.current_function = previous_value;
477 fn visit_generics(&mut self, generics: &'tcx Generics) {
478 // For type parameter defaults, we have to ban access
479 // to following type parameters, as the InternalSubsts can only
480 // provide previous type parameters as they're built. We
481 // put all the parameters on the ban list and then remove
482 // them one by one as they are processed and become available.
483 let mut default_ban_rib = Rib::new(ForwardTyParamBanRibKind);
484 let mut found_default = false;
485 default_ban_rib.bindings.extend(generics.params.iter().filter_map(
486 |param| match param.kind {
487 GenericParamKind::Const { .. } | GenericParamKind::Lifetime { .. } => None,
488 GenericParamKind::Type { ref default, .. } => {
489 found_default |= default.is_some();
490 found_default.then_some((Ident::with_dummy_span(param.ident.name), Res::Err))
495 // rust-lang/rust#61631: The type `Self` is essentially
496 // another type parameter. For ADTs, we consider it
497 // well-defined only after all of the ADT type parameters have
498 // been provided. Therefore, we do not allow use of `Self`
499 // anywhere in ADT type parameter defaults.
501 // (We however cannot ban `Self` for defaults on *all* generic
502 // lists; e.g. trait generics can usefully refer to `Self`,
503 // such as in the case of `trait Add<Rhs = Self>`.)
504 if self.diagnostic_metadata.current_self_item.is_some() {
505 // (`Some` if + only if we are in ADT's generics.)
506 default_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
509 for param in &generics.params {
511 GenericParamKind::Lifetime { .. } => self.visit_generic_param(param),
512 GenericParamKind::Type { ref default, .. } => {
513 for bound in ¶m.bounds {
514 self.visit_param_bound(bound);
517 if let Some(ref ty) = default {
518 self.ribs[TypeNS].push(default_ban_rib);
520 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
523 // Allow all following defaults to refer to this type parameter.
524 default_ban_rib.bindings.remove(&Ident::with_dummy_span(param.ident.name));
526 GenericParamKind::Const { ref ty } => {
527 for bound in ¶m.bounds {
528 self.visit_param_bound(bound);
534 for p in &generics.where_clause.predicates {
535 self.visit_where_predicate(p);
539 fn visit_generic_arg(&mut self, arg: &'tcx GenericArg) {
540 debug!("visit_generic_arg({:?})", arg);
542 GenericArg::Type(ref ty) => {
543 // We parse const arguments as path types as we cannot distiguish them durring
544 // parsing. We try to resolve that ambiguity by attempting resolution the type
545 // namespace first, and if that fails we try again in the value namespace. If
546 // resolution in the value namespace succeeds, we have an generic const argument on
548 if let TyKind::Path(ref qself, ref path) = ty.kind {
549 // We cannot disambiguate multi-segment paths right now as that requires type
551 if path.segments.len() == 1 && path.segments[0].args.is_none() {
552 let mut check_ns = |ns| {
553 self.resolve_ident_in_lexical_scope(
554 path.segments[0].ident,
562 if !check_ns(TypeNS) && check_ns(ValueNS) {
563 // This must be equivalent to `visit_anon_const`, but we cannot call it
564 // directly due to visitor lifetimes so we have to copy-paste some code.
565 self.with_constant_rib(|this| {
566 this.smart_resolve_path(
570 PathSource::Expr(None),
573 if let Some(ref qself) = *qself {
574 this.visit_ty(&qself.ty);
576 this.visit_path(path, ty.id);
586 GenericArg::Lifetime(lt) => self.visit_lifetime(lt),
587 GenericArg::Const(ct) => self.visit_anon_const(ct),
592 impl<'a, 'b> LateResolutionVisitor<'a, '_> {
593 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b> {
594 // During late resolution we only track the module component of the parent scope,
595 // although it may be useful to track other components as well for diagnostics.
596 let graph_root = resolver.graph_root;
597 let parent_scope = ParentScope::module(graph_root);
598 let start_rib_kind = ModuleRibKind(graph_root);
599 LateResolutionVisitor {
603 value_ns: vec![Rib::new(start_rib_kind)],
604 type_ns: vec![Rib::new(start_rib_kind)],
605 macro_ns: vec![Rib::new(start_rib_kind)],
607 label_ribs: Vec::new(),
608 current_trait_ref: None,
609 diagnostic_metadata: DiagnosticMetadata::default(),
613 fn resolve_ident_in_lexical_scope(
617 record_used_id: Option<NodeId>,
619 ) -> Option<LexicalScopeBinding<'a>> {
620 self.r.resolve_ident_in_lexical_scope(
633 opt_ns: Option<Namespace>, // `None` indicates a module path in import
636 crate_lint: CrateLint,
637 ) -> PathResult<'a> {
638 self.r.resolve_path_with_ribs(
651 // We maintain a list of value ribs and type ribs.
653 // Simultaneously, we keep track of the current position in the module
654 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
655 // the value or type namespaces, we first look through all the ribs and
656 // then query the module graph. When we resolve a name in the module
657 // namespace, we can skip all the ribs (since nested modules are not
658 // allowed within blocks in Rust) and jump straight to the current module
661 // Named implementations are handled separately. When we find a method
662 // call, we consult the module node to find all of the implementations in
663 // scope. This information is lazily cached in the module node. We then
664 // generate a fake "implementation scope" containing all the
665 // implementations thus found, for compatibility with old resolve pass.
667 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
672 work: impl FnOnce(&mut Self) -> T,
674 self.ribs[ns].push(Rib::new(kind));
675 let ret = work(self);
680 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
681 let id = self.r.definitions.local_def_id(id);
682 let module = self.r.module_map.get(&id).cloned(); // clones a reference
683 if let Some(module) = module {
684 // Move down in the graph.
685 let orig_module = replace(&mut self.parent_scope.module, module);
686 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
687 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
689 this.parent_scope.module = orig_module;
698 /// Searches the current set of local scopes for labels. Returns the first non-`None` label that
699 /// is returned by the given predicate function
701 /// Stops after meeting a closure.
702 fn search_label<P, R>(&self, mut ident: Ident, pred: P) -> Option<R>
704 P: Fn(&Rib<'_, NodeId>, Ident) -> Option<R>,
706 for rib in self.label_ribs.iter().rev() {
709 // If an invocation of this macro created `ident`, give up on `ident`
710 // and switch to `ident`'s source from the macro definition.
711 MacroDefinition(def) => {
712 if def == self.r.macro_def(ident.span.ctxt()) {
713 ident.span.remove_mark();
717 // Do not resolve labels across function boundary
721 let r = pred(rib, ident);
729 fn resolve_adt(&mut self, item: &Item, generics: &Generics) {
730 debug!("resolve_adt");
731 self.with_current_self_item(item, |this| {
732 this.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
733 let item_def_id = this.r.definitions.local_def_id(item.id);
734 this.with_self_rib(Res::SelfTy(None, Some(item_def_id)), |this| {
735 visit::walk_item(this, item);
741 fn future_proof_import(&mut self, use_tree: &UseTree) {
742 let segments = &use_tree.prefix.segments;
743 if !segments.is_empty() {
744 let ident = segments[0].ident;
745 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
749 let nss = match use_tree.kind {
750 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
753 let report_error = |this: &Self, ns| {
754 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
755 this.r.session.span_err(ident.span, &format!("imports cannot refer to {}", what));
759 match self.resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span) {
760 Some(LexicalScopeBinding::Res(..)) => {
761 report_error(self, ns);
763 Some(LexicalScopeBinding::Item(binding)) => {
764 let orig_blacklisted_binding =
765 replace(&mut self.r.blacklisted_binding, Some(binding));
766 if let Some(LexicalScopeBinding::Res(..)) = self
767 .resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span)
769 report_error(self, ns);
771 self.r.blacklisted_binding = orig_blacklisted_binding;
776 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
777 for (use_tree, _) in use_trees {
778 self.future_proof_import(use_tree);
783 fn resolve_item(&mut self, item: &Item) {
784 let name = item.ident.name;
785 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
788 ItemKind::TyAlias(_, ref generics) | ItemKind::Fn(_, ref generics, _) => {
789 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
790 visit::walk_item(this, item)
794 ItemKind::Enum(_, ref generics)
795 | ItemKind::Struct(_, ref generics)
796 | ItemKind::Union(_, ref generics) => {
797 self.resolve_adt(item, generics);
800 ItemKind::Impl(.., ref generics, ref opt_trait_ref, ref self_type, ref impl_items) => {
801 self.resolve_implementation(
810 ItemKind::Trait(.., ref generics, ref bounds, ref trait_items) => {
811 // Create a new rib for the trait-wide type parameters.
812 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
813 let local_def_id = this.r.definitions.local_def_id(item.id);
814 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
815 this.visit_generics(generics);
816 walk_list!(this, visit_param_bound, bounds);
818 for trait_item in trait_items {
819 this.with_trait_items(trait_items, |this| {
820 this.with_generic_param_rib(
821 &trait_item.generics,
824 match trait_item.kind {
825 AssocItemKind::Const(ref ty, ref default) => {
828 // Only impose the restrictions of
829 // ConstRibKind for an actual constant
830 // expression in a provided default.
831 if let Some(ref expr) = *default {
832 this.with_constant_rib(|this| {
833 this.visit_expr(expr);
837 AssocItemKind::Fn(_, _) => {
838 visit::walk_trait_item(this, trait_item)
840 AssocItemKind::TyAlias(..) => {
841 visit::walk_trait_item(this, trait_item)
843 AssocItemKind::Macro(_) => {
844 panic!("unexpanded macro in resolve!")
855 ItemKind::TraitAlias(ref generics, ref bounds) => {
856 // Create a new rib for the trait-wide type parameters.
857 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
858 let local_def_id = this.r.definitions.local_def_id(item.id);
859 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
860 this.visit_generics(generics);
861 walk_list!(this, visit_param_bound, bounds);
866 ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
867 self.with_scope(item.id, |this| {
868 visit::walk_item(this, item);
872 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(ref ty, ref expr) => {
873 debug!("resolve_item ItemKind::Const");
874 self.with_item_rib(HasGenericParams::No, |this| {
876 this.with_constant_rib(|this| {
877 this.visit_expr(expr);
882 ItemKind::Use(ref use_tree) => {
883 self.future_proof_import(use_tree);
886 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) | ItemKind::GlobalAsm(..) => {
887 // do nothing, these are just around to be encoded
890 ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
894 fn with_generic_param_rib<'c, F>(&'c mut self, generics: &'c Generics, kind: RibKind<'a>, f: F)
896 F: FnOnce(&mut Self),
898 debug!("with_generic_param_rib");
899 let mut function_type_rib = Rib::new(kind);
900 let mut function_value_rib = Rib::new(kind);
901 let mut seen_bindings = FxHashMap::default();
903 // We also can't shadow bindings from the parent item
904 if let AssocItemRibKind = kind {
905 let mut add_bindings_for_ns = |ns| {
906 let parent_rib = self.ribs[ns]
908 .rfind(|r| if let ItemRibKind(_) = r.kind { true } else { false })
909 .expect("associated item outside of an item");
911 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
913 add_bindings_for_ns(ValueNS);
914 add_bindings_for_ns(TypeNS);
917 for param in &generics.params {
918 if let GenericParamKind::Lifetime { .. } = param.kind {
922 let def_kind = match param.kind {
923 GenericParamKind::Type { .. } => DefKind::TyParam,
924 GenericParamKind::Const { .. } => DefKind::ConstParam,
928 let ident = param.ident.modern();
929 debug!("with_generic_param_rib: {}", param.id);
931 if seen_bindings.contains_key(&ident) {
932 let span = seen_bindings.get(&ident).unwrap();
933 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, *span);
934 self.r.report_error(param.ident.span, err);
936 seen_bindings.entry(ident).or_insert(param.ident.span);
938 // Plain insert (no renaming).
939 let res = Res::Def(def_kind, self.r.definitions.local_def_id(param.id));
942 GenericParamKind::Type { .. } => {
943 function_type_rib.bindings.insert(ident, res);
944 self.r.record_partial_res(param.id, PartialRes::new(res));
946 GenericParamKind::Const { .. } => {
947 function_value_rib.bindings.insert(ident, res);
948 self.r.record_partial_res(param.id, PartialRes::new(res));
954 self.ribs[ValueNS].push(function_value_rib);
955 self.ribs[TypeNS].push(function_type_rib);
959 self.ribs[TypeNS].pop();
960 self.ribs[ValueNS].pop();
963 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
964 self.label_ribs.push(Rib::new(kind));
966 self.label_ribs.pop();
969 fn with_item_rib(&mut self, has_generic_params: HasGenericParams, f: impl FnOnce(&mut Self)) {
970 let kind = ItemRibKind(has_generic_params);
971 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
974 fn with_constant_rib(&mut self, f: impl FnOnce(&mut Self)) {
975 debug!("with_constant_rib");
976 self.with_rib(ValueNS, ConstantItemRibKind, |this| {
977 this.with_label_rib(ConstantItemRibKind, f);
981 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
982 // Handle nested impls (inside fn bodies)
984 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
985 let result = f(self);
986 self.diagnostic_metadata.current_self_type = previous_value;
990 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
992 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
993 let result = f(self);
994 self.diagnostic_metadata.current_self_item = previous_value;
998 /// When evaluating a `trait` use its associated types' idents for suggestionsa in E0412.
999 fn with_trait_items<T>(
1001 trait_items: &Vec<AssocItem>,
1002 f: impl FnOnce(&mut Self) -> T,
1004 let trait_assoc_types = replace(
1005 &mut self.diagnostic_metadata.current_trait_assoc_types,
1008 .filter_map(|item| match &item.kind {
1009 AssocItemKind::TyAlias(bounds, _) if bounds.len() == 0 => Some(item.ident),
1014 let result = f(self);
1015 self.diagnostic_metadata.current_trait_assoc_types = trait_assoc_types;
1019 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
1020 fn with_optional_trait_ref<T>(
1022 opt_trait_ref: Option<&TraitRef>,
1023 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
1025 let mut new_val = None;
1026 let mut new_id = None;
1027 if let Some(trait_ref) = opt_trait_ref {
1028 let path: Vec<_> = Segment::from_path(&trait_ref.path);
1030 .smart_resolve_path_fragment(
1034 trait_ref.path.span,
1035 PathSource::Trait(AliasPossibility::No),
1036 CrateLint::SimplePath(trait_ref.ref_id),
1039 if res != Res::Err {
1040 new_id = Some(res.def_id());
1041 let span = trait_ref.path.span;
1042 if let PathResult::Module(ModuleOrUniformRoot::Module(module)) = self.resolve_path(
1047 CrateLint::SimplePath(trait_ref.ref_id),
1049 new_val = Some((module, trait_ref.clone()));
1053 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1054 let result = f(self, new_id);
1055 self.current_trait_ref = original_trait_ref;
1059 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
1060 let mut self_type_rib = Rib::new(NormalRibKind);
1062 // Plain insert (no renaming, since types are not currently hygienic)
1063 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
1064 self.ribs[ns].push(self_type_rib);
1066 self.ribs[ns].pop();
1069 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
1070 self.with_self_rib_ns(TypeNS, self_res, f)
1073 fn resolve_implementation(
1075 generics: &Generics,
1076 opt_trait_reference: &Option<TraitRef>,
1079 impl_items: &[AssocItem],
1081 debug!("resolve_implementation");
1082 // If applicable, create a rib for the type parameters.
1083 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1084 // Dummy self type for better errors if `Self` is used in the trait path.
1085 this.with_self_rib(Res::SelfTy(None, None), |this| {
1086 // Resolve the trait reference, if necessary.
1087 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1088 let item_def_id = this.r.definitions.local_def_id(item_id);
1089 this.with_self_rib(Res::SelfTy(trait_id, Some(item_def_id)), |this| {
1090 if let Some(trait_ref) = opt_trait_reference.as_ref() {
1091 // Resolve type arguments in the trait path.
1092 visit::walk_trait_ref(this, trait_ref);
1094 // Resolve the self type.
1095 this.visit_ty(self_type);
1096 // Resolve the generic parameters.
1097 this.visit_generics(generics);
1098 // Resolve the items within the impl.
1099 this.with_current_self_type(self_type, |this| {
1100 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
1101 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
1102 for impl_item in impl_items {
1103 // We also need a new scope for the impl item type parameters.
1104 this.with_generic_param_rib(&impl_item.generics,
1107 use crate::ResolutionError::*;
1108 match impl_item.kind {
1109 AssocItemKind::Const(..) => {
1111 "resolve_implementation AssocItemKind::Const",
1113 // If this is a trait impl, ensure the const
1115 this.check_trait_item(
1119 |n, s| ConstNotMemberOfTrait(n, s),
1122 this.with_constant_rib(|this| {
1123 visit::walk_impl_item(this, impl_item)
1126 AssocItemKind::Fn(..) => {
1127 // If this is a trait impl, ensure the method
1129 this.check_trait_item(impl_item.ident,
1132 |n, s| MethodNotMemberOfTrait(n, s));
1134 visit::walk_impl_item(this, impl_item);
1136 AssocItemKind::TyAlias(_, _) => {
1137 // If this is a trait impl, ensure the type
1139 this.check_trait_item(impl_item.ident,
1142 |n, s| TypeNotMemberOfTrait(n, s));
1144 visit::walk_impl_item(this, impl_item);
1146 AssocItemKind::Macro(_) =>
1147 panic!("unexpanded macro in resolve!"),
1159 fn check_trait_item<F>(&mut self, ident: Ident, ns: Namespace, span: Span, err: F)
1161 F: FnOnce(Name, &str) -> ResolutionError<'_>,
1163 // If there is a TraitRef in scope for an impl, then the method must be in the
1165 if let Some((module, _)) = self.current_trait_ref {
1168 .resolve_ident_in_module(
1169 ModuleOrUniformRoot::Module(module),
1178 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
1179 self.r.report_error(span, err(ident.name, &path_names_to_string(path)));
1184 fn resolve_params(&mut self, params: &[Param]) {
1185 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1186 for Param { pat, ty, .. } in params {
1187 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1189 debug!("(resolving function / closure) recorded parameter");
1193 fn resolve_local(&mut self, local: &Local) {
1194 // Resolve the type.
1195 walk_list!(self, visit_ty, &local.ty);
1197 // Resolve the initializer.
1198 walk_list!(self, visit_expr, &local.init);
1200 // Resolve the pattern.
1201 self.resolve_pattern_top(&local.pat, PatternSource::Let);
1204 /// build a map from pattern identifiers to binding-info's.
1205 /// this is done hygienically. This could arise for a macro
1206 /// that expands into an or-pattern where one 'x' was from the
1207 /// user and one 'x' came from the macro.
1208 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1209 let mut binding_map = FxHashMap::default();
1211 pat.walk(&mut |pat| {
1213 PatKind::Ident(binding_mode, ident, ref sub_pat)
1214 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
1216 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
1218 PatKind::Or(ref ps) => {
1219 // Check the consistency of this or-pattern and
1220 // then add all bindings to the larger map.
1221 for bm in self.check_consistent_bindings(ps) {
1222 binding_map.extend(bm);
1235 fn is_base_res_local(&self, nid: NodeId) -> bool {
1236 match self.r.partial_res_map.get(&nid).map(|res| res.base_res()) {
1237 Some(Res::Local(..)) => true,
1242 /// Checks that all of the arms in an or-pattern have exactly the
1243 /// same set of bindings, with the same binding modes for each.
1244 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
1245 let mut missing_vars = FxHashMap::default();
1246 let mut inconsistent_vars = FxHashMap::default();
1248 // 1) Compute the binding maps of all arms.
1249 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
1251 // 2) Record any missing bindings or binding mode inconsistencies.
1252 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
1253 // Check against all arms except for the same pattern which is always self-consistent.
1257 .filter(|(_, pat)| pat.id != pat_outer.id)
1258 .flat_map(|(idx, _)| maps[idx].iter())
1259 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
1261 for (name, info, &binding_inner) in inners {
1264 // The inner binding is missing in the outer.
1266 missing_vars.entry(name).or_insert_with(|| BindingError {
1268 origin: BTreeSet::new(),
1269 target: BTreeSet::new(),
1270 could_be_path: name.as_str().starts_with(char::is_uppercase),
1272 binding_error.origin.insert(binding_inner.span);
1273 binding_error.target.insert(pat_outer.span);
1275 Some(binding_outer) => {
1276 if binding_outer.binding_mode != binding_inner.binding_mode {
1277 // The binding modes in the outer and inner bindings differ.
1280 .or_insert((binding_inner.span, binding_outer.span));
1287 // 3) Report all missing variables we found.
1288 let mut missing_vars = missing_vars.iter_mut().collect::<Vec<_>>();
1289 missing_vars.sort();
1290 for (name, mut v) in missing_vars {
1291 if inconsistent_vars.contains_key(name) {
1292 v.could_be_path = false;
1294 self.r.report_error(
1295 *v.origin.iter().next().unwrap(),
1296 ResolutionError::VariableNotBoundInPattern(v),
1300 // 4) Report all inconsistencies in binding modes we found.
1301 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
1302 inconsistent_vars.sort();
1303 for (name, v) in inconsistent_vars {
1304 self.r.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
1307 // 5) Finally bubble up all the binding maps.
1311 /// Check the consistency of the outermost or-patterns.
1312 fn check_consistent_bindings_top(&mut self, pat: &Pat) {
1313 pat.walk(&mut |pat| match pat.kind {
1314 PatKind::Or(ref ps) => {
1315 self.check_consistent_bindings(ps);
1322 fn resolve_arm(&mut self, arm: &Arm) {
1323 self.with_rib(ValueNS, NormalRibKind, |this| {
1324 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
1325 walk_list!(this, visit_expr, &arm.guard);
1326 this.visit_expr(&arm.body);
1330 /// Arising from `source`, resolve a top level pattern.
1331 fn resolve_pattern_top(&mut self, pat: &Pat, pat_src: PatternSource) {
1332 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1333 self.resolve_pattern(pat, pat_src, &mut bindings);
1339 pat_src: PatternSource,
1340 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1342 self.resolve_pattern_inner(pat, pat_src, bindings);
1343 // This has to happen *after* we determine which pat_idents are variants:
1344 self.check_consistent_bindings_top(pat);
1345 visit::walk_pat(self, pat);
1348 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
1352 /// A stack of sets of bindings accumulated.
1354 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
1355 /// be interpreted as re-binding an already bound binding. This results in an error.
1356 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
1357 /// in reusing this binding rather than creating a fresh one.
1359 /// When called at the top level, the stack must have a single element
1360 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
1361 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
1362 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
1363 /// When each `p_i` has been dealt with, the top set is merged with its parent.
1364 /// When a whole or-pattern has been dealt with, the thing happens.
1366 /// See the implementation and `fresh_binding` for more details.
1367 fn resolve_pattern_inner(
1370 pat_src: PatternSource,
1371 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1373 // Visit all direct subpatterns of this pattern.
1374 pat.walk(&mut |pat| {
1375 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
1377 PatKind::Ident(bmode, ident, ref sub) => {
1378 // First try to resolve the identifier as some existing entity,
1379 // then fall back to a fresh binding.
1380 let has_sub = sub.is_some();
1382 .try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub)
1383 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
1384 self.r.record_partial_res(pat.id, PartialRes::new(res));
1386 PatKind::TupleStruct(ref path, ..) => {
1387 self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);
1389 PatKind::Path(ref qself, ref path) => {
1390 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
1392 PatKind::Struct(ref path, ..) => {
1393 self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
1395 PatKind::Or(ref ps) => {
1396 // Add a new set of bindings to the stack. `Or` here records that when a
1397 // binding already exists in this set, it should not result in an error because
1398 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
1399 bindings.push((PatBoundCtx::Or, Default::default()));
1401 // Now we need to switch back to a product context so that each
1402 // part of the or-pattern internally rejects already bound names.
1403 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
1404 bindings.push((PatBoundCtx::Product, Default::default()));
1405 self.resolve_pattern_inner(p, pat_src, bindings);
1406 // Move up the non-overlapping bindings to the or-pattern.
1407 // Existing bindings just get "merged".
1408 let collected = bindings.pop().unwrap().1;
1409 bindings.last_mut().unwrap().1.extend(collected);
1411 // This or-pattern itself can itself be part of a product,
1412 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
1413 // Both cases bind `a` again in a product pattern and must be rejected.
1414 let collected = bindings.pop().unwrap().1;
1415 bindings.last_mut().unwrap().1.extend(collected);
1417 // Prevent visiting `ps` as we've already done so above.
1430 pat_src: PatternSource,
1431 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1433 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
1434 // (We must not add it if it's in the bindings map because that breaks the assumptions
1435 // later passes make about or-patterns.)
1436 let ident = ident.modern_and_legacy();
1438 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
1439 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
1440 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
1441 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
1442 // This is *required* for consistency which is checked later.
1443 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
1445 if already_bound_and {
1446 // Overlap in a product pattern somewhere; report an error.
1447 use ResolutionError::*;
1448 let error = match pat_src {
1449 // `fn f(a: u8, a: u8)`:
1450 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
1452 _ => IdentifierBoundMoreThanOnceInSamePattern,
1454 self.r.report_error(ident.span, error(&ident.as_str()));
1457 // Record as bound if it's valid:
1458 let ident_valid = ident.name != kw::Invalid;
1460 bindings.last_mut().unwrap().1.insert(ident);
1463 if already_bound_or {
1464 // `Variant1(a) | Variant2(a)`, ok
1465 // Reuse definition from the first `a`.
1466 self.innermost_rib_bindings(ValueNS)[&ident]
1468 let res = Res::Local(pat_id);
1470 // A completely fresh binding add to the set if it's valid.
1471 self.innermost_rib_bindings(ValueNS).insert(ident, res);
1477 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
1478 &mut self.ribs[ns].last_mut().unwrap().bindings
1481 fn try_resolve_as_non_binding(
1483 pat_src: PatternSource,
1490 self.resolve_ident_in_lexical_scope(ident, ValueNS, None, pat.span)?.item()?;
1491 let res = binding.res();
1493 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
1494 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
1495 // also be interpreted as a path to e.g. a constant, variant, etc.
1496 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
1499 Res::Def(DefKind::Ctor(_, CtorKind::Const), _) | Res::Def(DefKind::Const, _)
1500 if is_syntactic_ambiguity =>
1502 // Disambiguate in favor of a unit struct/variant or constant pattern.
1503 self.r.record_use(ident, ValueNS, binding, false);
1506 Res::Def(DefKind::Ctor(..), _)
1507 | Res::Def(DefKind::Const, _)
1508 | Res::Def(DefKind::Static, _) => {
1509 // This is unambiguously a fresh binding, either syntactically
1510 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
1511 // to something unusable as a pattern (e.g., constructor function),
1512 // but we still conservatively report an error, see
1513 // issues/33118#issuecomment-233962221 for one reason why.
1514 self.r.report_error(
1516 ResolutionError::BindingShadowsSomethingUnacceptable(
1524 Res::Def(DefKind::Fn, _) | Res::Err => {
1525 // These entities are explicitly allowed to be shadowed by fresh bindings.
1531 "unexpected resolution for an \
1532 identifier in pattern: {:?}",
1539 // High-level and context dependent path resolution routine.
1540 // Resolves the path and records the resolution into definition map.
1541 // If resolution fails tries several techniques to find likely
1542 // resolution candidates, suggest imports or other help, and report
1543 // errors in user friendly way.
1544 fn smart_resolve_path(
1547 qself: Option<&QSelf>,
1549 source: PathSource<'_>,
1551 self.smart_resolve_path_fragment(
1554 &Segment::from_path(path),
1557 CrateLint::SimplePath(id),
1561 fn smart_resolve_path_fragment(
1564 qself: Option<&QSelf>,
1567 source: PathSource<'_>,
1568 crate_lint: CrateLint,
1570 let ns = source.namespace();
1571 let is_expected = &|res| source.is_expected(res);
1573 let report_errors = |this: &mut Self, res: Option<Res>| {
1574 let (err, candidates) = this.smart_resolve_report_errors(path, span, source, res);
1575 let def_id = this.parent_scope.module.normal_ancestor_id;
1576 let node_id = this.r.definitions.as_local_node_id(def_id).unwrap();
1577 let better = res.is_some();
1578 this.r.use_injections.push(UseError { err, candidates, node_id, better });
1579 PartialRes::new(Res::Err)
1582 let partial_res = match self.resolve_qpath_anywhere(
1588 source.defer_to_typeck(),
1591 Some(partial_res) if partial_res.unresolved_segments() == 0 => {
1592 if is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err {
1595 report_errors(self, Some(partial_res.base_res()))
1598 Some(partial_res) if source.defer_to_typeck() => {
1599 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
1600 // or `<T>::A::B`. If `B` should be resolved in value namespace then
1601 // it needs to be added to the trait map.
1603 let item_name = path.last().unwrap().ident;
1604 let traits = self.get_traits_containing_item(item_name, ns);
1605 self.r.trait_map.insert(id, traits);
1608 let mut std_path = vec![Segment::from_ident(Ident::with_dummy_span(sym::std))];
1609 std_path.extend(path);
1610 if self.r.primitive_type_table.primitive_types.contains_key(&path[0].ident.name) {
1611 let cl = CrateLint::No;
1613 if let PathResult::Module(_) | PathResult::NonModule(_) =
1614 self.resolve_path(&std_path, ns, false, span, cl)
1616 // check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
1618 path.iter().last().map(|segment| segment.ident.span).unwrap_or(span);
1619 debug!("accessed item from `std` submodule as a bare type {:?}", std_path);
1620 let mut hm = self.r.session.confused_type_with_std_module.borrow_mut();
1621 hm.insert(item_span, span);
1622 // In some places (E0223) we only have access to the full path
1623 hm.insert(span, span);
1628 _ => report_errors(self, None),
1631 if let PathSource::TraitItem(..) = source {
1633 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
1634 self.r.record_partial_res(id, partial_res);
1639 fn self_type_is_available(&mut self, span: Span) -> bool {
1640 let binding = self.resolve_ident_in_lexical_scope(
1641 Ident::with_dummy_span(kw::SelfUpper),
1646 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1649 fn self_value_is_available(&mut self, self_span: Span, path_span: Span) -> bool {
1650 let ident = Ident::new(kw::SelfLower, self_span);
1651 let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, path_span);
1652 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1655 // Resolve in alternative namespaces if resolution in the primary namespace fails.
1656 fn resolve_qpath_anywhere(
1659 qself: Option<&QSelf>,
1661 primary_ns: Namespace,
1663 defer_to_typeck: bool,
1664 crate_lint: CrateLint,
1665 ) -> Option<PartialRes> {
1666 let mut fin_res = None;
1667 for (i, ns) in [primary_ns, TypeNS, ValueNS].iter().cloned().enumerate() {
1668 if i == 0 || ns != primary_ns {
1669 match self.resolve_qpath(id, qself, path, ns, span, crate_lint) {
1670 // If defer_to_typeck, then resolution > no resolution,
1671 // otherwise full resolution > partial resolution > no resolution.
1673 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
1675 return Some(partial_res);
1678 if fin_res.is_none() {
1679 fin_res = partial_res
1687 assert!(primary_ns != MacroNS);
1688 if qself.is_none() {
1689 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
1690 let path = Path { segments: path.iter().map(path_seg).collect(), span };
1691 if let Ok((_, res)) =
1692 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
1694 return Some(PartialRes::new(res));
1701 /// Handles paths that may refer to associated items.
1705 qself: Option<&QSelf>,
1709 crate_lint: CrateLint,
1710 ) -> Option<PartialRes> {
1712 "resolve_qpath(id={:?}, qself={:?}, path={:?}, ns={:?}, span={:?})",
1713 id, qself, path, ns, span,
1716 if let Some(qself) = qself {
1717 if qself.position == 0 {
1718 // This is a case like `<T>::B`, where there is no
1719 // trait to resolve. In that case, we leave the `B`
1720 // segment to be resolved by type-check.
1721 return Some(PartialRes::with_unresolved_segments(
1722 Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX)),
1727 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
1729 // Currently, `path` names the full item (`A::B::C`, in
1730 // our example). so we extract the prefix of that that is
1731 // the trait (the slice upto and including
1732 // `qself.position`). And then we recursively resolve that,
1733 // but with `qself` set to `None`.
1735 // However, setting `qself` to none (but not changing the
1736 // span) loses the information about where this path
1737 // *actually* appears, so for the purposes of the crate
1738 // lint we pass along information that this is the trait
1739 // name from a fully qualified path, and this also
1740 // contains the full span (the `CrateLint::QPathTrait`).
1741 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
1742 let partial_res = self.smart_resolve_path_fragment(
1745 &path[..=qself.position],
1747 PathSource::TraitItem(ns),
1748 CrateLint::QPathTrait { qpath_id: id, qpath_span: qself.path_span },
1751 // The remaining segments (the `C` in our example) will
1752 // have to be resolved by type-check, since that requires doing
1753 // trait resolution.
1754 return Some(PartialRes::with_unresolved_segments(
1755 partial_res.base_res(),
1756 partial_res.unresolved_segments() + path.len() - qself.position - 1,
1760 let result = match self.resolve_path(&path, Some(ns), true, span, crate_lint) {
1761 PathResult::NonModule(path_res) => path_res,
1762 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
1763 PartialRes::new(module.res().unwrap())
1765 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
1766 // don't report an error right away, but try to fallback to a primitive type.
1767 // So, we are still able to successfully resolve something like
1769 // use std::u8; // bring module u8 in scope
1770 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
1771 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
1772 // // not to non-existent std::u8::max_value
1775 // Such behavior is required for backward compatibility.
1776 // The same fallback is used when `a` resolves to nothing.
1777 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
1778 if (ns == TypeNS || path.len() > 1)
1781 .primitive_type_table
1783 .contains_key(&path[0].ident.name) =>
1785 let prim = self.r.primitive_type_table.primitive_types[&path[0].ident.name];
1786 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
1788 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
1789 PartialRes::new(module.res().unwrap())
1791 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
1792 self.r.report_error(span, ResolutionError::FailedToResolve { label, suggestion });
1793 PartialRes::new(Res::Err)
1795 PathResult::Module(..) | PathResult::Failed { .. } => return None,
1796 PathResult::Indeterminate => bug!("indetermined path result in resolve_qpath"),
1800 && result.base_res() != Res::Err
1801 && path[0].ident.name != kw::PathRoot
1802 && path[0].ident.name != kw::DollarCrate
1804 let unqualified_result = {
1805 match self.resolve_path(
1806 &[*path.last().unwrap()],
1812 PathResult::NonModule(path_res) => path_res.base_res(),
1813 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
1814 module.res().unwrap()
1816 _ => return Some(result),
1819 if result.base_res() == unqualified_result {
1820 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
1821 self.r.lint_buffer.buffer_lint(lint, id, span, "unnecessary qualification")
1828 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
1829 if let Some(label) = label {
1830 if label.ident.as_str().as_bytes()[1] != b'_' {
1831 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
1833 self.with_label_rib(NormalRibKind, |this| {
1834 let ident = label.ident.modern_and_legacy();
1835 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
1843 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &Block) {
1844 self.with_resolved_label(label, id, |this| this.visit_block(block));
1847 fn resolve_block(&mut self, block: &Block) {
1848 debug!("(resolving block) entering block");
1849 // Move down in the graph, if there's an anonymous module rooted here.
1850 let orig_module = self.parent_scope.module;
1851 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
1853 let mut num_macro_definition_ribs = 0;
1854 if let Some(anonymous_module) = anonymous_module {
1855 debug!("(resolving block) found anonymous module, moving down");
1856 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
1857 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
1858 self.parent_scope.module = anonymous_module;
1860 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
1863 // Descend into the block.
1864 for stmt in &block.stmts {
1865 if let StmtKind::Item(ref item) = stmt.kind {
1866 if let ItemKind::MacroDef(..) = item.kind {
1867 num_macro_definition_ribs += 1;
1868 let res = self.r.definitions.local_def_id(item.id);
1869 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
1870 self.label_ribs.push(Rib::new(MacroDefinition(res)));
1874 self.visit_stmt(stmt);
1878 self.parent_scope.module = orig_module;
1879 for _ in 0..num_macro_definition_ribs {
1880 self.ribs[ValueNS].pop();
1881 self.label_ribs.pop();
1883 self.ribs[ValueNS].pop();
1884 if anonymous_module.is_some() {
1885 self.ribs[TypeNS].pop();
1887 debug!("(resolving block) leaving block");
1890 fn resolve_expr(&mut self, expr: &Expr, parent: Option<&Expr>) {
1891 // First, record candidate traits for this expression if it could
1892 // result in the invocation of a method call.
1894 self.record_candidate_traits_for_expr_if_necessary(expr);
1896 // Next, resolve the node.
1898 ExprKind::Path(ref qself, ref path) => {
1899 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
1900 visit::walk_expr(self, expr);
1903 ExprKind::Struct(ref path, ..) => {
1904 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
1905 visit::walk_expr(self, expr);
1908 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
1909 let node_id = self.search_label(label.ident, |rib, ident| {
1910 rib.bindings.get(&ident.modern_and_legacy()).cloned()
1914 // Search again for close matches...
1915 // Picks the first label that is "close enough", which is not necessarily
1916 // the closest match
1917 let close_match = self.search_label(label.ident, |rib, ident| {
1918 let names = rib.bindings.iter().filter_map(|(id, _)| {
1919 if id.span.ctxt() == label.ident.span.ctxt() {
1925 find_best_match_for_name(names, &ident.as_str(), None)
1927 self.r.record_partial_res(expr.id, PartialRes::new(Res::Err));
1928 self.r.report_error(
1930 ResolutionError::UndeclaredLabel(&label.ident.as_str(), close_match),
1934 // Since this res is a label, it is never read.
1935 self.r.label_res_map.insert(expr.id, node_id);
1936 self.diagnostic_metadata.unused_labels.remove(&node_id);
1940 // visit `break` argument if any
1941 visit::walk_expr(self, expr);
1944 ExprKind::Let(ref pat, ref scrutinee) => {
1945 self.visit_expr(scrutinee);
1946 self.resolve_pattern_top(pat, PatternSource::Let);
1949 ExprKind::If(ref cond, ref then, ref opt_else) => {
1950 self.with_rib(ValueNS, NormalRibKind, |this| {
1951 this.visit_expr(cond);
1952 this.visit_block(then);
1954 opt_else.as_ref().map(|expr| self.visit_expr(expr));
1957 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
1959 ExprKind::While(ref cond, ref block, label) => {
1960 self.with_resolved_label(label, expr.id, |this| {
1961 this.with_rib(ValueNS, NormalRibKind, |this| {
1962 this.visit_expr(cond);
1963 this.visit_block(block);
1968 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
1969 self.visit_expr(iter_expr);
1970 self.with_rib(ValueNS, NormalRibKind, |this| {
1971 this.resolve_pattern_top(pat, PatternSource::For);
1972 this.resolve_labeled_block(label, expr.id, block);
1976 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
1978 // Equivalent to `visit::walk_expr` + passing some context to children.
1979 ExprKind::Field(ref subexpression, _) => {
1980 self.resolve_expr(subexpression, Some(expr));
1982 ExprKind::MethodCall(ref segment, ref arguments) => {
1983 let mut arguments = arguments.iter();
1984 self.resolve_expr(arguments.next().unwrap(), Some(expr));
1985 for argument in arguments {
1986 self.resolve_expr(argument, None);
1988 self.visit_path_segment(expr.span, segment);
1991 ExprKind::Call(ref callee, ref arguments) => {
1992 self.resolve_expr(callee, Some(expr));
1993 for argument in arguments {
1994 self.resolve_expr(argument, None);
1997 ExprKind::Type(ref type_expr, _) => {
1998 self.diagnostic_metadata.current_type_ascription.push(type_expr.span);
1999 visit::walk_expr(self, expr);
2000 self.diagnostic_metadata.current_type_ascription.pop();
2002 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
2003 // resolve the arguments within the proper scopes so that usages of them inside the
2004 // closure are detected as upvars rather than normal closure arg usages.
2005 ExprKind::Closure(_, IsAsync::Async { .. }, _, ref fn_decl, ref body, _span) => {
2006 self.with_rib(ValueNS, NormalRibKind, |this| {
2007 // Resolve arguments:
2008 this.resolve_params(&fn_decl.inputs);
2009 // No need to resolve return type --
2010 // the outer closure return type is `FunctionRetTy::Default`.
2012 // Now resolve the inner closure
2014 // No need to resolve arguments: the inner closure has none.
2015 // Resolve the return type:
2016 visit::walk_fn_ret_ty(this, &fn_decl.output);
2018 this.visit_expr(body);
2023 visit::walk_expr(self, expr);
2028 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
2030 ExprKind::Field(_, ident) => {
2031 // FIXME(#6890): Even though you can't treat a method like a
2032 // field, we need to add any trait methods we find that match
2033 // the field name so that we can do some nice error reporting
2034 // later on in typeck.
2035 let traits = self.get_traits_containing_item(ident, ValueNS);
2036 self.r.trait_map.insert(expr.id, traits);
2038 ExprKind::MethodCall(ref segment, ..) => {
2039 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
2040 let traits = self.get_traits_containing_item(segment.ident, ValueNS);
2041 self.r.trait_map.insert(expr.id, traits);
2049 fn get_traits_containing_item(
2053 ) -> Vec<TraitCandidate> {
2054 debug!("(getting traits containing item) looking for '{}'", ident.name);
2056 let mut found_traits = Vec::new();
2057 // Look for the current trait.
2058 if let Some((module, _)) = self.current_trait_ref {
2061 .resolve_ident_in_module(
2062 ModuleOrUniformRoot::Module(module),
2071 let def_id = module.def_id().unwrap();
2072 found_traits.push(TraitCandidate { def_id: def_id, import_ids: smallvec![] });
2076 ident.span = ident.span.modern();
2077 let mut search_module = self.parent_scope.module;
2079 self.get_traits_in_module_containing_item(ident, ns, search_module, &mut found_traits);
2081 unwrap_or!(self.r.hygienic_lexical_parent(search_module, &mut ident.span), break);
2084 if let Some(prelude) = self.r.prelude {
2085 if !search_module.no_implicit_prelude {
2086 self.get_traits_in_module_containing_item(ident, ns, prelude, &mut found_traits);
2093 fn get_traits_in_module_containing_item(
2098 found_traits: &mut Vec<TraitCandidate>,
2100 assert!(ns == TypeNS || ns == ValueNS);
2101 let mut traits = module.traits.borrow_mut();
2102 if traits.is_none() {
2103 let mut collected_traits = Vec::new();
2104 module.for_each_child(self.r, |_, name, ns, binding| {
2108 match binding.res() {
2109 Res::Def(DefKind::Trait, _) | Res::Def(DefKind::TraitAlias, _) => {
2110 collected_traits.push((name, binding))
2115 *traits = Some(collected_traits.into_boxed_slice());
2118 for &(trait_name, binding) in traits.as_ref().unwrap().iter() {
2119 // Traits have pseudo-modules that can be used to search for the given ident.
2120 if let Some(module) = binding.module() {
2121 let mut ident = ident;
2122 if ident.span.glob_adjust(module.expansion, binding.span).is_none() {
2127 .resolve_ident_in_module_unadjusted(
2128 ModuleOrUniformRoot::Module(module),
2137 let import_ids = self.find_transitive_imports(&binding.kind, trait_name);
2138 let trait_def_id = module.def_id().unwrap();
2139 found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids });
2141 } else if let Res::Def(DefKind::TraitAlias, _) = binding.res() {
2142 // For now, just treat all trait aliases as possible candidates, since we don't
2143 // know if the ident is somewhere in the transitive bounds.
2144 let import_ids = self.find_transitive_imports(&binding.kind, trait_name);
2145 let trait_def_id = binding.res().def_id();
2146 found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids });
2148 bug!("candidate is not trait or trait alias?")
2153 fn find_transitive_imports(
2155 mut kind: &NameBindingKind<'_>,
2157 ) -> SmallVec<[NodeId; 1]> {
2158 let mut import_ids = smallvec![];
2159 while let NameBindingKind::Import { directive, binding, .. } = kind {
2160 self.r.maybe_unused_trait_imports.insert(directive.id);
2161 self.r.add_to_glob_map(&directive, trait_name);
2162 import_ids.push(directive.id);
2163 kind = &binding.kind;
2169 impl<'a> Resolver<'a> {
2170 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
2171 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
2172 visit::walk_crate(&mut late_resolution_visitor, krate);
2173 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
2174 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");