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, AssocCtxt, FnCtxt, FnKind, Visitor};
28 use syntax::{unwrap_or, walk_list};
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, PartialEq, Eq, Debug)]
58 fn descr(self) -> &'static str {
60 PatternSource::Match => "match binding",
61 PatternSource::Let => "let binding",
62 PatternSource::For => "for binding",
63 PatternSource::FnParam => "function parameter",
68 /// Denotes whether the context for the set of already bound bindings is a `Product`
69 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
70 /// See those functions for more information.
73 /// A product pattern context, e.g., `Variant(a, b)`.
75 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
79 /// Does this the item (from the item rib scope) allow generic parameters?
80 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
81 crate enum HasGenericParams {
86 /// The rib kind restricts certain accesses,
87 /// e.g. to a `Res::Local` of an outer item.
88 #[derive(Copy, Clone, Debug)]
89 crate enum RibKind<'a> {
90 /// No restriction needs to be applied.
93 /// We passed through an impl or trait and are now in one of its
94 /// methods or associated types. Allow references to ty params that impl or trait
95 /// binds. Disallow any other upvars (including other ty params that are
99 /// We passed through a function definition. Disallow upvars.
100 /// Permit only those const parameters that are specified in the function's generics.
103 /// We passed through an item scope. Disallow upvars.
104 ItemRibKind(HasGenericParams),
106 /// We're in a constant item. Can't refer to dynamic stuff.
109 /// We passed through a module.
110 ModuleRibKind(Module<'a>),
112 /// We passed through a `macro_rules!` statement
113 MacroDefinition(DefId),
115 /// All bindings in this rib are type parameters that can't be used
116 /// from the default of a type parameter because they're not declared
117 /// before said type parameter. Also see the `visit_generics` override.
118 ForwardTyParamBanRibKind,
122 // Whether this rib kind contains generic parameters, as opposed to local
124 crate fn contains_params(&self) -> bool {
126 NormalRibKind | FnItemRibKind | ConstantItemRibKind | ModuleRibKind(_)
127 | MacroDefinition(_) => false,
128 AssocItemRibKind | ItemRibKind(_) | ForwardTyParamBanRibKind => true,
133 /// A single local scope.
135 /// A rib represents a scope names can live in. Note that these appear in many places, not just
136 /// around braces. At any place where the list of accessible names (of the given namespace)
137 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
138 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
141 /// Different [rib kinds](enum.RibKind) are transparent for different names.
143 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
144 /// resolving, the name is looked up from inside out.
146 crate struct Rib<'a, R = Res> {
147 pub bindings: IdentMap<R>,
148 pub kind: RibKind<'a>,
151 impl<'a, R> Rib<'a, R> {
152 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
153 Rib { bindings: Default::default(), kind }
157 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
158 crate enum AliasPossibility {
163 #[derive(Copy, Clone, Debug)]
164 crate enum PathSource<'a> {
165 // Type paths `Path`.
167 // Trait paths in bounds or impls.
168 Trait(AliasPossibility),
169 // Expression paths `path`, with optional parent context.
170 Expr(Option<&'a Expr>),
171 // Paths in path patterns `Path`.
173 // Paths in struct expressions and patterns `Path { .. }`.
175 // Paths in tuple struct patterns `Path(..)`.
177 // `m::A::B` in `<T as m::A>::B::C`.
178 TraitItem(Namespace),
181 impl<'a> PathSource<'a> {
182 fn namespace(self) -> Namespace {
184 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
185 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct => ValueNS,
186 PathSource::TraitItem(ns) => ns,
190 fn defer_to_typeck(self) -> bool {
193 | PathSource::Expr(..)
196 | PathSource::TupleStruct => true,
197 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
201 fn descr_expected(self) -> &'static str {
203 PathSource::Type => "type",
204 PathSource::Trait(_) => "trait",
205 PathSource::Pat => "unit struct, unit variant or constant",
206 PathSource::Struct => "struct, variant or union type",
207 PathSource::TupleStruct => "tuple struct or tuple variant",
208 PathSource::TraitItem(ns) => match ns {
209 TypeNS => "associated type",
210 ValueNS => "method or associated constant",
211 MacroNS => bug!("associated macro"),
213 PathSource::Expr(parent) => match &parent.as_ref().map(|p| &p.kind) {
214 // "function" here means "anything callable" rather than `DefKind::Fn`,
215 // this is not precise but usually more helpful than just "value".
216 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
217 ExprKind::Path(_, path) => {
218 let mut msg = "function";
219 if let Some(segment) = path.segments.iter().last() {
220 if let Some(c) = segment.ident.to_string().chars().next() {
221 if c.is_uppercase() {
222 msg = "function, tuple struct or tuple variant";
235 crate fn is_expected(self, res: Res) -> bool {
237 PathSource::Type => match res {
238 Res::Def(DefKind::Struct, _)
239 | Res::Def(DefKind::Union, _)
240 | Res::Def(DefKind::Enum, _)
241 | Res::Def(DefKind::Trait, _)
242 | Res::Def(DefKind::TraitAlias, _)
243 | Res::Def(DefKind::TyAlias, _)
244 | Res::Def(DefKind::AssocTy, _)
246 | Res::Def(DefKind::TyParam, _)
248 | Res::Def(DefKind::OpaqueTy, _)
249 | Res::Def(DefKind::ForeignTy, _) => true,
252 PathSource::Trait(AliasPossibility::No) => match res {
253 Res::Def(DefKind::Trait, _) => true,
256 PathSource::Trait(AliasPossibility::Maybe) => match res {
257 Res::Def(DefKind::Trait, _) => true,
258 Res::Def(DefKind::TraitAlias, _) => true,
261 PathSource::Expr(..) => match res {
262 Res::Def(DefKind::Ctor(_, CtorKind::Const), _)
263 | Res::Def(DefKind::Ctor(_, CtorKind::Fn), _)
264 | Res::Def(DefKind::Const, _)
265 | Res::Def(DefKind::Static, _)
267 | Res::Def(DefKind::Fn, _)
268 | Res::Def(DefKind::Method, _)
269 | Res::Def(DefKind::AssocConst, _)
271 | Res::Def(DefKind::ConstParam, _) => true,
274 PathSource::Pat => match res {
275 Res::Def(DefKind::Ctor(_, CtorKind::Const), _)
276 | Res::Def(DefKind::Const, _)
277 | Res::Def(DefKind::AssocConst, _)
278 | Res::SelfCtor(..) => true,
281 PathSource::TupleStruct => match res {
282 Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) | Res::SelfCtor(..) => true,
285 PathSource::Struct => match res {
286 Res::Def(DefKind::Struct, _)
287 | Res::Def(DefKind::Union, _)
288 | Res::Def(DefKind::Variant, _)
289 | Res::Def(DefKind::TyAlias, _)
290 | Res::Def(DefKind::AssocTy, _)
291 | Res::SelfTy(..) => true,
294 PathSource::TraitItem(ns) => match res {
295 Res::Def(DefKind::AssocConst, _) | Res::Def(DefKind::Method, _)
300 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
306 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
307 use rustc_errors::error_code;
308 match (self, has_unexpected_resolution) {
309 (PathSource::Trait(_), true) => error_code!(E0404),
310 (PathSource::Trait(_), false) => error_code!(E0405),
311 (PathSource::Type, true) => error_code!(E0573),
312 (PathSource::Type, false) => error_code!(E0412),
313 (PathSource::Struct, true) => error_code!(E0574),
314 (PathSource::Struct, false) => error_code!(E0422),
315 (PathSource::Expr(..), true) => error_code!(E0423),
316 (PathSource::Expr(..), false) => error_code!(E0425),
317 (PathSource::Pat, true) | (PathSource::TupleStruct, true) => error_code!(E0532),
318 (PathSource::Pat, false) | (PathSource::TupleStruct, false) => error_code!(E0531),
319 (PathSource::TraitItem(..), true) => error_code!(E0575),
320 (PathSource::TraitItem(..), false) => error_code!(E0576),
326 struct DiagnosticMetadata<'ast> {
327 /// The current trait's associated types' ident, used for diagnostic suggestions.
328 current_trait_assoc_types: Vec<Ident>,
330 /// The current self type if inside an impl (used for better errors).
331 current_self_type: Option<Ty>,
333 /// The current self item if inside an ADT (used for better errors).
334 current_self_item: Option<NodeId>,
336 /// The current trait (used to suggest).
337 current_item: Option<&'ast Item>,
339 /// When processing generics and encountering a type not found, suggest introducing a type
341 currently_processing_generics: bool,
343 /// The current enclosing function (used for better errors).
344 current_function: Option<Span>,
346 /// A list of labels as of yet unused. Labels will be removed from this map when
347 /// they are used (in a `break` or `continue` statement)
348 unused_labels: FxHashMap<NodeId, Span>,
350 /// Only used for better errors on `fn(): fn()`.
351 current_type_ascription: Vec<Span>,
353 /// Only used for better errors on `let <pat>: <expr, not type>;`.
354 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
357 struct LateResolutionVisitor<'a, 'b, 'ast> {
358 r: &'b mut Resolver<'a>,
360 /// The module that represents the current item scope.
361 parent_scope: ParentScope<'a>,
363 /// The current set of local scopes for types and values.
364 /// FIXME #4948: Reuse ribs to avoid allocation.
365 ribs: PerNS<Vec<Rib<'a>>>,
367 /// The current set of local scopes, for labels.
368 label_ribs: Vec<Rib<'a, NodeId>>,
370 /// The trait that the current context can refer to.
371 current_trait_ref: Option<(Module<'a>, TraitRef)>,
373 /// Fields used to add information to diagnostic errors.
374 diagnostic_metadata: DiagnosticMetadata<'ast>,
377 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
378 impl<'a, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
379 fn visit_item(&mut self, item: &'ast Item) {
380 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
381 self.resolve_item(item);
382 self.diagnostic_metadata.current_item = prev;
384 fn visit_arm(&mut self, arm: &'ast Arm) {
385 self.resolve_arm(arm);
387 fn visit_block(&mut self, block: &'ast Block) {
388 self.resolve_block(block);
390 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
391 debug!("visit_anon_const {:?}", constant);
392 self.with_constant_rib(|this| {
393 visit::walk_anon_const(this, constant);
396 fn visit_expr(&mut self, expr: &'ast Expr) {
397 self.resolve_expr(expr, None);
399 fn visit_local(&mut self, local: &'ast Local) {
400 let local_spans = match local.pat.kind {
401 // We check for this to avoid tuple struct fields.
402 PatKind::Wild => None,
405 local.ty.as_ref().map(|ty| ty.span),
406 local.init.as_ref().map(|init| init.span),
409 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
410 self.resolve_local(local);
411 self.diagnostic_metadata.current_let_binding = original;
413 fn visit_ty(&mut self, ty: &'ast Ty) {
415 TyKind::Path(ref qself, ref path) => {
416 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
418 TyKind::ImplicitSelf => {
419 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
421 .resolve_ident_in_lexical_scope(self_ty, TypeNS, Some(ty.id), ty.span)
422 .map_or(Res::Err, |d| d.res());
423 self.r.record_partial_res(ty.id, PartialRes::new(res));
427 visit::walk_ty(self, ty);
429 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef, m: &'ast TraitBoundModifier) {
430 self.smart_resolve_path(
431 tref.trait_ref.ref_id,
433 &tref.trait_ref.path,
434 PathSource::Trait(AliasPossibility::Maybe),
436 visit::walk_poly_trait_ref(self, tref, m);
438 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
439 match foreign_item.kind {
440 ForeignItemKind::Fn(_, ref generics, _)
441 | ForeignItemKind::TyAlias(ref generics, ..) => {
442 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
443 visit::walk_foreign_item(this, foreign_item);
446 ForeignItemKind::Const(..) | ForeignItemKind::Static(..) => {
447 self.with_item_rib(HasGenericParams::No, |this| {
448 visit::walk_foreign_item(this, foreign_item);
451 ForeignItemKind::Macro(..) => {
452 visit::walk_foreign_item(self, foreign_item);
456 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, _: NodeId) {
457 let rib_kind = match fn_kind {
458 FnKind::Fn(FnCtxt::Foreign, ..) => return visit::walk_fn(self, fn_kind, sp),
459 FnKind::Fn(FnCtxt::Free, ..) => FnItemRibKind,
460 FnKind::Fn(FnCtxt::Assoc(_), ..) | FnKind::Closure(..) => NormalRibKind,
462 let previous_value = replace(&mut self.diagnostic_metadata.current_function, Some(sp));
463 debug!("(resolving function) entering function");
464 let declaration = fn_kind.decl();
466 // Create a value rib for the function.
467 self.with_rib(ValueNS, rib_kind, |this| {
468 // Create a label rib for the function.
469 this.with_label_rib(rib_kind, |this| {
470 // Add each argument to the rib.
471 this.resolve_params(&declaration.inputs);
473 visit::walk_fn_ret_ty(this, &declaration.output);
475 // Resolve the function body, potentially inside the body of an async closure
477 FnKind::Fn(.., body) => walk_list!(this, visit_block, body),
478 FnKind::Closure(_, body) => this.visit_expr(body),
481 debug!("(resolving function) leaving function");
484 self.diagnostic_metadata.current_function = previous_value;
487 fn visit_generics(&mut self, generics: &'ast Generics) {
488 // For type parameter defaults, we have to ban access
489 // to following type parameters, as the InternalSubsts can only
490 // provide previous type parameters as they're built. We
491 // put all the parameters on the ban list and then remove
492 // them one by one as they are processed and become available.
493 let mut default_ban_rib = Rib::new(ForwardTyParamBanRibKind);
494 let mut found_default = false;
495 default_ban_rib.bindings.extend(generics.params.iter().filter_map(
496 |param| match param.kind {
497 GenericParamKind::Const { .. } | GenericParamKind::Lifetime { .. } => None,
498 GenericParamKind::Type { ref default, .. } => {
499 found_default |= default.is_some();
500 found_default.then_some((Ident::with_dummy_span(param.ident.name), Res::Err))
505 // rust-lang/rust#61631: The type `Self` is essentially
506 // another type parameter. For ADTs, we consider it
507 // well-defined only after all of the ADT type parameters have
508 // been provided. Therefore, we do not allow use of `Self`
509 // anywhere in ADT type parameter defaults.
511 // (We however cannot ban `Self` for defaults on *all* generic
512 // lists; e.g. trait generics can usefully refer to `Self`,
513 // such as in the case of `trait Add<Rhs = Self>`.)
514 if self.diagnostic_metadata.current_self_item.is_some() {
515 // (`Some` if + only if we are in ADT's generics.)
516 default_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
519 for param in &generics.params {
521 GenericParamKind::Lifetime { .. } => self.visit_generic_param(param),
522 GenericParamKind::Type { ref default, .. } => {
523 for bound in ¶m.bounds {
524 self.visit_param_bound(bound);
527 if let Some(ref ty) = default {
528 self.ribs[TypeNS].push(default_ban_rib);
530 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
533 // Allow all following defaults to refer to this type parameter.
534 default_ban_rib.bindings.remove(&Ident::with_dummy_span(param.ident.name));
536 GenericParamKind::Const { ref ty } => {
537 for bound in ¶m.bounds {
538 self.visit_param_bound(bound);
544 for p in &generics.where_clause.predicates {
545 self.visit_where_predicate(p);
549 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
550 debug!("visit_generic_arg({:?})", arg);
551 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
553 GenericArg::Type(ref ty) => {
554 // We parse const arguments as path types as we cannot distiguish them during
555 // parsing. We try to resolve that ambiguity by attempting resolution the type
556 // namespace first, and if that fails we try again in the value namespace. If
557 // resolution in the value namespace succeeds, we have an generic const argument on
559 if let TyKind::Path(ref qself, ref path) = ty.kind {
560 // We cannot disambiguate multi-segment paths right now as that requires type
562 if path.segments.len() == 1 && path.segments[0].args.is_none() {
563 let mut check_ns = |ns| {
564 self.resolve_ident_in_lexical_scope(
565 path.segments[0].ident,
572 if !check_ns(TypeNS) && check_ns(ValueNS) {
573 // This must be equivalent to `visit_anon_const`, but we cannot call it
574 // directly due to visitor lifetimes so we have to copy-paste some code.
575 self.with_constant_rib(|this| {
576 this.smart_resolve_path(
580 PathSource::Expr(None),
583 if let Some(ref qself) = *qself {
584 this.visit_ty(&qself.ty);
586 this.visit_path(path, ty.id);
589 self.diagnostic_metadata.currently_processing_generics = prev;
597 GenericArg::Lifetime(lt) => self.visit_lifetime(lt),
598 GenericArg::Const(ct) => self.visit_anon_const(ct),
600 self.diagnostic_metadata.currently_processing_generics = prev;
604 impl<'a, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
605 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
606 // During late resolution we only track the module component of the parent scope,
607 // although it may be useful to track other components as well for diagnostics.
608 let graph_root = resolver.graph_root;
609 let parent_scope = ParentScope::module(graph_root);
610 let start_rib_kind = ModuleRibKind(graph_root);
611 LateResolutionVisitor {
615 value_ns: vec![Rib::new(start_rib_kind)],
616 type_ns: vec![Rib::new(start_rib_kind)],
617 macro_ns: vec![Rib::new(start_rib_kind)],
619 label_ribs: Vec::new(),
620 current_trait_ref: None,
621 diagnostic_metadata: DiagnosticMetadata::default(),
625 fn resolve_ident_in_lexical_scope(
629 record_used_id: Option<NodeId>,
631 ) -> Option<LexicalScopeBinding<'a>> {
632 self.r.resolve_ident_in_lexical_scope(
645 opt_ns: Option<Namespace>, // `None` indicates a module path in import
648 crate_lint: CrateLint,
649 ) -> PathResult<'a> {
650 self.r.resolve_path_with_ribs(
663 // We maintain a list of value ribs and type ribs.
665 // Simultaneously, we keep track of the current position in the module
666 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
667 // the value or type namespaces, we first look through all the ribs and
668 // then query the module graph. When we resolve a name in the module
669 // namespace, we can skip all the ribs (since nested modules are not
670 // allowed within blocks in Rust) and jump straight to the current module
673 // Named implementations are handled separately. When we find a method
674 // call, we consult the module node to find all of the implementations in
675 // scope. This information is lazily cached in the module node. We then
676 // generate a fake "implementation scope" containing all the
677 // implementations thus found, for compatibility with old resolve pass.
679 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
684 work: impl FnOnce(&mut Self) -> T,
686 self.ribs[ns].push(Rib::new(kind));
687 let ret = work(self);
692 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
693 let id = self.r.definitions.local_def_id(id);
694 let module = self.r.module_map.get(&id).cloned(); // clones a reference
695 if let Some(module) = module {
696 // Move down in the graph.
697 let orig_module = replace(&mut self.parent_scope.module, module);
698 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
699 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
701 this.parent_scope.module = orig_module;
710 /// Searches the current set of local scopes for labels. Returns the first non-`None` label that
711 /// is returned by the given predicate function
713 /// Stops after meeting a closure.
714 fn search_label<P, R>(&self, mut ident: Ident, pred: P) -> Option<R>
716 P: Fn(&Rib<'_, NodeId>, Ident) -> Option<R>,
718 for rib in self.label_ribs.iter().rev() {
721 // If an invocation of this macro created `ident`, give up on `ident`
722 // and switch to `ident`'s source from the macro definition.
723 MacroDefinition(def) => {
724 if def == self.r.macro_def(ident.span.ctxt()) {
725 ident.span.remove_mark();
729 // Do not resolve labels across function boundary
733 let r = pred(rib, ident);
741 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
742 debug!("resolve_adt");
743 self.with_current_self_item(item, |this| {
744 this.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
745 let item_def_id = this.r.definitions.local_def_id(item.id);
746 this.with_self_rib(Res::SelfTy(None, Some(item_def_id)), |this| {
747 visit::walk_item(this, item);
753 fn future_proof_import(&mut self, use_tree: &UseTree) {
754 let segments = &use_tree.prefix.segments;
755 if !segments.is_empty() {
756 let ident = segments[0].ident;
757 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
761 let nss = match use_tree.kind {
762 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
765 let report_error = |this: &Self, ns| {
766 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
767 this.r.session.span_err(ident.span, &format!("imports cannot refer to {}", what));
771 match self.resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span) {
772 Some(LexicalScopeBinding::Res(..)) => {
773 report_error(self, ns);
775 Some(LexicalScopeBinding::Item(binding)) => {
776 let orig_blacklisted_binding =
777 replace(&mut self.r.blacklisted_binding, Some(binding));
778 if let Some(LexicalScopeBinding::Res(..)) = self
779 .resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span)
781 report_error(self, ns);
783 self.r.blacklisted_binding = orig_blacklisted_binding;
788 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
789 for (use_tree, _) in use_trees {
790 self.future_proof_import(use_tree);
795 fn resolve_item(&mut self, item: &'ast Item) {
796 let name = item.ident.name;
797 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
800 ItemKind::TyAlias(_, ref generics) | ItemKind::Fn(_, ref generics, _) => {
801 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
802 visit::walk_item(this, item)
806 ItemKind::Enum(_, ref generics)
807 | ItemKind::Struct(_, ref generics)
808 | ItemKind::Union(_, ref generics) => {
809 self.resolve_adt(item, generics);
816 items: ref impl_items,
819 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
822 ItemKind::Trait(.., ref generics, ref bounds, ref trait_items) => {
823 // Create a new rib for the trait-wide type parameters.
824 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
825 let local_def_id = this.r.definitions.local_def_id(item.id);
826 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
827 this.visit_generics(generics);
828 walk_list!(this, visit_param_bound, bounds);
830 let walk_assoc_item = |this: &mut Self, generics, item| {
831 this.with_generic_param_rib(generics, AssocItemRibKind, |this| {
832 visit::walk_assoc_item(this, item, AssocCtxt::Trait)
836 for item in trait_items {
837 this.with_trait_items(trait_items, |this| {
839 AssocItemKind::Static(ty, _, default)
840 | AssocItemKind::Const(ty, default) => {
842 // Only impose the restrictions of `ConstRibKind` for an
843 // actual constant expression in a provided default.
844 if let Some(expr) = default {
845 this.with_constant_rib(|this| this.visit_expr(expr));
848 AssocItemKind::Fn(_, generics, _) => {
849 walk_assoc_item(this, generics, item);
851 AssocItemKind::TyAlias(generics, _, _) => {
852 walk_assoc_item(this, generics, item);
854 AssocItemKind::Macro(_) => {
855 panic!("unexpanded macro in resolve!")
864 ItemKind::TraitAlias(ref generics, ref bounds) => {
865 // Create a new rib for the trait-wide type parameters.
866 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
867 let local_def_id = this.r.definitions.local_def_id(item.id);
868 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
869 this.visit_generics(generics);
870 walk_list!(this, visit_param_bound, bounds);
875 ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
876 self.with_scope(item.id, |this| {
877 visit::walk_item(this, item);
881 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(ref ty, ref expr) => {
882 debug!("resolve_item ItemKind::Const");
883 self.with_item_rib(HasGenericParams::No, |this| {
885 if let Some(expr) = expr {
886 this.with_constant_rib(|this| this.visit_expr(expr));
891 ItemKind::Use(ref use_tree) => {
892 self.future_proof_import(use_tree);
895 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) | ItemKind::GlobalAsm(..) => {
896 // do nothing, these are just around to be encoded
899 ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
903 fn with_generic_param_rib<'c, F>(&'c mut self, generics: &'c Generics, kind: RibKind<'a>, f: F)
905 F: FnOnce(&mut Self),
907 debug!("with_generic_param_rib");
908 let mut function_type_rib = Rib::new(kind);
909 let mut function_value_rib = Rib::new(kind);
910 let mut seen_bindings = FxHashMap::default();
912 // We also can't shadow bindings from the parent item
913 if let AssocItemRibKind = kind {
914 let mut add_bindings_for_ns = |ns| {
915 let parent_rib = self.ribs[ns]
917 .rfind(|r| if let ItemRibKind(_) = r.kind { true } else { false })
918 .expect("associated item outside of an item");
920 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
922 add_bindings_for_ns(ValueNS);
923 add_bindings_for_ns(TypeNS);
926 for param in &generics.params {
927 if let GenericParamKind::Lifetime { .. } = param.kind {
931 let def_kind = match param.kind {
932 GenericParamKind::Type { .. } => DefKind::TyParam,
933 GenericParamKind::Const { .. } => DefKind::ConstParam,
937 let ident = param.ident.modern();
938 debug!("with_generic_param_rib: {}", param.id);
940 if seen_bindings.contains_key(&ident) {
941 let span = seen_bindings.get(&ident).unwrap();
942 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, *span);
943 self.r.report_error(param.ident.span, err);
945 seen_bindings.entry(ident).or_insert(param.ident.span);
947 // Plain insert (no renaming).
948 let res = Res::Def(def_kind, self.r.definitions.local_def_id(param.id));
951 GenericParamKind::Type { .. } => {
952 function_type_rib.bindings.insert(ident, res);
953 self.r.record_partial_res(param.id, PartialRes::new(res));
955 GenericParamKind::Const { .. } => {
956 function_value_rib.bindings.insert(ident, res);
957 self.r.record_partial_res(param.id, PartialRes::new(res));
963 self.ribs[ValueNS].push(function_value_rib);
964 self.ribs[TypeNS].push(function_type_rib);
968 self.ribs[TypeNS].pop();
969 self.ribs[ValueNS].pop();
972 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
973 self.label_ribs.push(Rib::new(kind));
975 self.label_ribs.pop();
978 fn with_item_rib(&mut self, has_generic_params: HasGenericParams, f: impl FnOnce(&mut Self)) {
979 let kind = ItemRibKind(has_generic_params);
980 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
983 fn with_constant_rib(&mut self, f: impl FnOnce(&mut Self)) {
984 debug!("with_constant_rib");
985 self.with_rib(ValueNS, ConstantItemRibKind, |this| {
986 this.with_label_rib(ConstantItemRibKind, f);
990 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
991 // Handle nested impls (inside fn bodies)
993 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
994 let result = f(self);
995 self.diagnostic_metadata.current_self_type = previous_value;
999 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
1000 let previous_value =
1001 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
1002 let result = f(self);
1003 self.diagnostic_metadata.current_self_item = previous_value;
1007 /// When evaluating a `trait` use its associated types' idents for suggestionsa in E0412.
1008 fn with_trait_items<T>(
1010 trait_items: &Vec<P<AssocItem>>,
1011 f: impl FnOnce(&mut Self) -> T,
1013 let trait_assoc_types = replace(
1014 &mut self.diagnostic_metadata.current_trait_assoc_types,
1017 .filter_map(|item| match &item.kind {
1018 AssocItemKind::TyAlias(_, bounds, _) if bounds.len() == 0 => Some(item.ident),
1023 let result = f(self);
1024 self.diagnostic_metadata.current_trait_assoc_types = trait_assoc_types;
1028 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
1029 fn with_optional_trait_ref<T>(
1031 opt_trait_ref: Option<&TraitRef>,
1032 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
1034 let mut new_val = None;
1035 let mut new_id = None;
1036 if let Some(trait_ref) = opt_trait_ref {
1037 let path: Vec<_> = Segment::from_path(&trait_ref.path);
1038 let res = self.smart_resolve_path_fragment(
1042 trait_ref.path.span,
1043 PathSource::Trait(AliasPossibility::No),
1044 CrateLint::SimplePath(trait_ref.ref_id),
1046 let res = res.base_res();
1047 if res != Res::Err {
1048 new_id = Some(res.def_id());
1049 let span = trait_ref.path.span;
1050 if let PathResult::Module(ModuleOrUniformRoot::Module(module)) = self.resolve_path(
1055 CrateLint::SimplePath(trait_ref.ref_id),
1057 new_val = Some((module, trait_ref.clone()));
1061 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1062 let result = f(self, new_id);
1063 self.current_trait_ref = original_trait_ref;
1067 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
1068 let mut self_type_rib = Rib::new(NormalRibKind);
1070 // Plain insert (no renaming, since types are not currently hygienic)
1071 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
1072 self.ribs[ns].push(self_type_rib);
1074 self.ribs[ns].pop();
1077 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
1078 self.with_self_rib_ns(TypeNS, self_res, f)
1081 fn resolve_implementation(
1083 generics: &'ast Generics,
1084 opt_trait_reference: &'ast Option<TraitRef>,
1085 self_type: &'ast Ty,
1087 impl_items: &'ast [P<AssocItem>],
1089 debug!("resolve_implementation");
1090 // If applicable, create a rib for the type parameters.
1091 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1092 // Dummy self type for better errors if `Self` is used in the trait path.
1093 this.with_self_rib(Res::SelfTy(None, None), |this| {
1094 // Resolve the trait reference, if necessary.
1095 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1096 let item_def_id = this.r.definitions.local_def_id(item_id);
1097 this.with_self_rib(Res::SelfTy(trait_id, Some(item_def_id)), |this| {
1098 if let Some(trait_ref) = opt_trait_reference.as_ref() {
1099 // Resolve type arguments in the trait path.
1100 visit::walk_trait_ref(this, trait_ref);
1102 // Resolve the self type.
1103 this.visit_ty(self_type);
1104 // Resolve the generic parameters.
1105 this.visit_generics(generics);
1106 // Resolve the items within the impl.
1107 this.with_current_self_type(self_type, |this| {
1108 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
1109 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
1110 for item in impl_items {
1111 use crate::ResolutionError::*;
1113 AssocItemKind::Static(..) | AssocItemKind::Const(..) => {
1114 debug!("resolve_implementation AssocItemKind::Const",);
1115 // If this is a trait impl, ensure the const
1117 this.check_trait_item(
1121 |n, s| ConstNotMemberOfTrait(n, s),
1124 this.with_constant_rib(|this| {
1125 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
1128 AssocItemKind::Fn(_, generics, _) => {
1129 // We also need a new scope for the impl item type parameters.
1130 this.with_generic_param_rib(
1134 // If this is a trait impl, ensure the method
1136 this.check_trait_item(
1140 |n, s| MethodNotMemberOfTrait(n, s),
1143 visit::walk_assoc_item(
1151 AssocItemKind::TyAlias(generics, _, _) => {
1152 // We also need a new scope for the impl item type parameters.
1153 this.with_generic_param_rib(
1157 // If this is a trait impl, ensure the type
1159 this.check_trait_item(
1163 |n, s| TypeNotMemberOfTrait(n, s),
1166 visit::walk_assoc_item(
1174 AssocItemKind::Macro(_) => {
1175 panic!("unexpanded macro in resolve!")
1187 fn check_trait_item<F>(&mut self, ident: Ident, ns: Namespace, span: Span, err: F)
1189 F: FnOnce(Name, &str) -> ResolutionError<'_>,
1191 // If there is a TraitRef in scope for an impl, then the method must be in the
1193 if let Some((module, _)) = self.current_trait_ref {
1196 .resolve_ident_in_module(
1197 ModuleOrUniformRoot::Module(module),
1206 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
1207 self.r.report_error(span, err(ident.name, &path_names_to_string(path)));
1212 fn resolve_params(&mut self, params: &'ast [Param]) {
1213 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1214 for Param { pat, ty, .. } in params {
1215 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1217 debug!("(resolving function / closure) recorded parameter");
1221 fn resolve_local(&mut self, local: &'ast Local) {
1222 // Resolve the type.
1223 walk_list!(self, visit_ty, &local.ty);
1225 // Resolve the initializer.
1226 walk_list!(self, visit_expr, &local.init);
1228 // Resolve the pattern.
1229 self.resolve_pattern_top(&local.pat, PatternSource::Let);
1232 /// build a map from pattern identifiers to binding-info's.
1233 /// this is done hygienically. This could arise for a macro
1234 /// that expands into an or-pattern where one 'x' was from the
1235 /// user and one 'x' came from the macro.
1236 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1237 let mut binding_map = FxHashMap::default();
1239 pat.walk(&mut |pat| {
1241 PatKind::Ident(binding_mode, ident, ref sub_pat)
1242 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
1244 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
1246 PatKind::Or(ref ps) => {
1247 // Check the consistency of this or-pattern and
1248 // then add all bindings to the larger map.
1249 for bm in self.check_consistent_bindings(ps) {
1250 binding_map.extend(bm);
1263 fn is_base_res_local(&self, nid: NodeId) -> bool {
1264 match self.r.partial_res_map.get(&nid).map(|res| res.base_res()) {
1265 Some(Res::Local(..)) => true,
1270 /// Checks that all of the arms in an or-pattern have exactly the
1271 /// same set of bindings, with the same binding modes for each.
1272 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
1273 let mut missing_vars = FxHashMap::default();
1274 let mut inconsistent_vars = FxHashMap::default();
1276 // 1) Compute the binding maps of all arms.
1277 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
1279 // 2) Record any missing bindings or binding mode inconsistencies.
1280 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
1281 // Check against all arms except for the same pattern which is always self-consistent.
1285 .filter(|(_, pat)| pat.id != pat_outer.id)
1286 .flat_map(|(idx, _)| maps[idx].iter())
1287 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
1289 for (name, info, &binding_inner) in inners {
1292 // The inner binding is missing in the outer.
1294 missing_vars.entry(name).or_insert_with(|| BindingError {
1296 origin: BTreeSet::new(),
1297 target: BTreeSet::new(),
1298 could_be_path: name.as_str().starts_with(char::is_uppercase),
1300 binding_error.origin.insert(binding_inner.span);
1301 binding_error.target.insert(pat_outer.span);
1303 Some(binding_outer) => {
1304 if binding_outer.binding_mode != binding_inner.binding_mode {
1305 // The binding modes in the outer and inner bindings differ.
1308 .or_insert((binding_inner.span, binding_outer.span));
1315 // 3) Report all missing variables we found.
1316 let mut missing_vars = missing_vars.iter_mut().collect::<Vec<_>>();
1317 missing_vars.sort();
1318 for (name, mut v) in missing_vars {
1319 if inconsistent_vars.contains_key(name) {
1320 v.could_be_path = false;
1322 self.r.report_error(
1323 *v.origin.iter().next().unwrap(),
1324 ResolutionError::VariableNotBoundInPattern(v),
1328 // 4) Report all inconsistencies in binding modes we found.
1329 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
1330 inconsistent_vars.sort();
1331 for (name, v) in inconsistent_vars {
1332 self.r.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
1335 // 5) Finally bubble up all the binding maps.
1339 /// Check the consistency of the outermost or-patterns.
1340 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
1341 pat.walk(&mut |pat| match pat.kind {
1342 PatKind::Or(ref ps) => {
1343 self.check_consistent_bindings(ps);
1350 fn resolve_arm(&mut self, arm: &'ast Arm) {
1351 self.with_rib(ValueNS, NormalRibKind, |this| {
1352 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
1353 walk_list!(this, visit_expr, &arm.guard);
1354 this.visit_expr(&arm.body);
1358 /// Arising from `source`, resolve a top level pattern.
1359 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
1360 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1361 self.resolve_pattern(pat, pat_src, &mut bindings);
1367 pat_src: PatternSource,
1368 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1370 self.resolve_pattern_inner(pat, pat_src, bindings);
1371 // This has to happen *after* we determine which pat_idents are variants:
1372 self.check_consistent_bindings_top(pat);
1373 visit::walk_pat(self, pat);
1376 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
1380 /// A stack of sets of bindings accumulated.
1382 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
1383 /// be interpreted as re-binding an already bound binding. This results in an error.
1384 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
1385 /// in reusing this binding rather than creating a fresh one.
1387 /// When called at the top level, the stack must have a single element
1388 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
1389 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
1390 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
1391 /// When each `p_i` has been dealt with, the top set is merged with its parent.
1392 /// When a whole or-pattern has been dealt with, the thing happens.
1394 /// See the implementation and `fresh_binding` for more details.
1395 fn resolve_pattern_inner(
1398 pat_src: PatternSource,
1399 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1401 // Visit all direct subpatterns of this pattern.
1402 pat.walk(&mut |pat| {
1403 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
1405 PatKind::Ident(bmode, ident, ref sub) => {
1406 // First try to resolve the identifier as some existing entity,
1407 // then fall back to a fresh binding.
1408 let has_sub = sub.is_some();
1410 .try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub)
1411 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
1412 self.r.record_partial_res(pat.id, PartialRes::new(res));
1414 PatKind::TupleStruct(ref path, ..) => {
1415 self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);
1417 PatKind::Path(ref qself, ref path) => {
1418 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
1420 PatKind::Struct(ref path, ..) => {
1421 self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
1423 PatKind::Or(ref ps) => {
1424 // Add a new set of bindings to the stack. `Or` here records that when a
1425 // binding already exists in this set, it should not result in an error because
1426 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
1427 bindings.push((PatBoundCtx::Or, Default::default()));
1429 // Now we need to switch back to a product context so that each
1430 // part of the or-pattern internally rejects already bound names.
1431 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
1432 bindings.push((PatBoundCtx::Product, Default::default()));
1433 self.resolve_pattern_inner(p, pat_src, bindings);
1434 // Move up the non-overlapping bindings to the or-pattern.
1435 // Existing bindings just get "merged".
1436 let collected = bindings.pop().unwrap().1;
1437 bindings.last_mut().unwrap().1.extend(collected);
1439 // This or-pattern itself can itself be part of a product,
1440 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
1441 // Both cases bind `a` again in a product pattern and must be rejected.
1442 let collected = bindings.pop().unwrap().1;
1443 bindings.last_mut().unwrap().1.extend(collected);
1445 // Prevent visiting `ps` as we've already done so above.
1458 pat_src: PatternSource,
1459 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1461 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
1462 // (We must not add it if it's in the bindings map because that breaks the assumptions
1463 // later passes make about or-patterns.)
1464 let ident = ident.modern_and_legacy();
1466 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
1467 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
1468 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
1469 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
1470 // This is *required* for consistency which is checked later.
1471 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
1473 if already_bound_and {
1474 // Overlap in a product pattern somewhere; report an error.
1475 use ResolutionError::*;
1476 let error = match pat_src {
1477 // `fn f(a: u8, a: u8)`:
1478 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
1480 _ => IdentifierBoundMoreThanOnceInSamePattern,
1482 self.r.report_error(ident.span, error(&ident.as_str()));
1485 // Record as bound if it's valid:
1486 let ident_valid = ident.name != kw::Invalid;
1488 bindings.last_mut().unwrap().1.insert(ident);
1491 if already_bound_or {
1492 // `Variant1(a) | Variant2(a)`, ok
1493 // Reuse definition from the first `a`.
1494 self.innermost_rib_bindings(ValueNS)[&ident]
1496 let res = Res::Local(pat_id);
1498 // A completely fresh binding add to the set if it's valid.
1499 self.innermost_rib_bindings(ValueNS).insert(ident, res);
1505 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
1506 &mut self.ribs[ns].last_mut().unwrap().bindings
1509 fn try_resolve_as_non_binding(
1511 pat_src: PatternSource,
1518 self.resolve_ident_in_lexical_scope(ident, ValueNS, None, pat.span)?.item()?;
1519 let res = binding.res();
1521 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
1522 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
1523 // also be interpreted as a path to e.g. a constant, variant, etc.
1524 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
1527 Res::Def(DefKind::Ctor(_, CtorKind::Const), _) | Res::Def(DefKind::Const, _)
1528 if is_syntactic_ambiguity =>
1530 // Disambiguate in favor of a unit struct/variant or constant pattern.
1531 self.r.record_use(ident, ValueNS, binding, false);
1534 Res::Def(DefKind::Ctor(..), _)
1535 | Res::Def(DefKind::Const, _)
1536 | Res::Def(DefKind::Static, _) => {
1537 // This is unambiguously a fresh binding, either syntactically
1538 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
1539 // to something unusable as a pattern (e.g., constructor function),
1540 // but we still conservatively report an error, see
1541 // issues/33118#issuecomment-233962221 for one reason why.
1542 self.r.report_error(
1544 ResolutionError::BindingShadowsSomethingUnacceptable(
1552 Res::Def(DefKind::Fn, _) | Res::Err => {
1553 // These entities are explicitly allowed to be shadowed by fresh bindings.
1559 "unexpected resolution for an \
1560 identifier in pattern: {:?}",
1567 // High-level and context dependent path resolution routine.
1568 // Resolves the path and records the resolution into definition map.
1569 // If resolution fails tries several techniques to find likely
1570 // resolution candidates, suggest imports or other help, and report
1571 // errors in user friendly way.
1572 fn smart_resolve_path(
1575 qself: Option<&QSelf>,
1577 source: PathSource<'ast>,
1579 self.smart_resolve_path_fragment(
1582 &Segment::from_path(path),
1585 CrateLint::SimplePath(id),
1589 fn smart_resolve_path_fragment(
1592 qself: Option<&QSelf>,
1595 source: PathSource<'ast>,
1596 crate_lint: CrateLint,
1598 let ns = source.namespace();
1599 let is_expected = &|res| source.is_expected(res);
1601 let report_errors = |this: &mut Self, res: Option<Res>| {
1602 let (err, candidates) = this.smart_resolve_report_errors(path, span, source, res);
1603 let def_id = this.parent_scope.module.normal_ancestor_id;
1604 let node_id = this.r.definitions.as_local_node_id(def_id).unwrap();
1605 let better = res.is_some();
1607 if res.is_none() { this.report_missing_type_error(path) } else { None };
1608 this.r.use_injections.push(UseError { err, candidates, node_id, better, suggestion });
1609 PartialRes::new(Res::Err)
1612 let partial_res = match self.resolve_qpath_anywhere(
1618 source.defer_to_typeck(),
1621 Some(partial_res) if partial_res.unresolved_segments() == 0 => {
1622 if is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err {
1625 report_errors(self, Some(partial_res.base_res()))
1628 Some(partial_res) if source.defer_to_typeck() => {
1629 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
1630 // or `<T>::A::B`. If `B` should be resolved in value namespace then
1631 // it needs to be added to the trait map.
1633 let item_name = path.last().unwrap().ident;
1634 let traits = self.get_traits_containing_item(item_name, ns);
1635 self.r.trait_map.insert(id, traits);
1638 let mut std_path = vec![Segment::from_ident(Ident::with_dummy_span(sym::std))];
1639 std_path.extend(path);
1640 if self.r.primitive_type_table.primitive_types.contains_key(&path[0].ident.name) {
1641 let cl = CrateLint::No;
1643 if let PathResult::Module(_) | PathResult::NonModule(_) =
1644 self.resolve_path(&std_path, ns, false, span, cl)
1646 // check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
1648 path.iter().last().map(|segment| segment.ident.span).unwrap_or(span);
1649 debug!("accessed item from `std` submodule as a bare type {:?}", std_path);
1650 let mut hm = self.r.session.confused_type_with_std_module.borrow_mut();
1651 hm.insert(item_span, span);
1652 // In some places (E0223) we only have access to the full path
1653 hm.insert(span, span);
1658 _ => report_errors(self, None),
1661 if let PathSource::TraitItem(..) = source {
1663 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
1664 self.r.record_partial_res(id, partial_res);
1669 fn self_type_is_available(&mut self, span: Span) -> bool {
1670 let binding = self.resolve_ident_in_lexical_scope(
1671 Ident::with_dummy_span(kw::SelfUpper),
1676 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1679 fn self_value_is_available(&mut self, self_span: Span, path_span: Span) -> bool {
1680 let ident = Ident::new(kw::SelfLower, self_span);
1681 let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, path_span);
1682 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1685 // Resolve in alternative namespaces if resolution in the primary namespace fails.
1686 fn resolve_qpath_anywhere(
1689 qself: Option<&QSelf>,
1691 primary_ns: Namespace,
1693 defer_to_typeck: bool,
1694 crate_lint: CrateLint,
1695 ) -> Option<PartialRes> {
1696 let mut fin_res = None;
1697 for (i, ns) in [primary_ns, TypeNS, ValueNS].iter().cloned().enumerate() {
1698 if i == 0 || ns != primary_ns {
1699 match self.resolve_qpath(id, qself, path, ns, span, crate_lint) {
1700 // If defer_to_typeck, then resolution > no resolution,
1701 // otherwise full resolution > partial resolution > no resolution.
1703 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
1705 return Some(partial_res);
1708 if fin_res.is_none() {
1709 fin_res = partial_res
1717 assert!(primary_ns != MacroNS);
1718 if qself.is_none() {
1719 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
1720 let path = Path { segments: path.iter().map(path_seg).collect(), span };
1721 if let Ok((_, res)) =
1722 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
1724 return Some(PartialRes::new(res));
1731 /// Handles paths that may refer to associated items.
1735 qself: Option<&QSelf>,
1739 crate_lint: CrateLint,
1740 ) -> Option<PartialRes> {
1742 "resolve_qpath(id={:?}, qself={:?}, path={:?}, ns={:?}, span={:?})",
1743 id, qself, path, ns, span,
1746 if let Some(qself) = qself {
1747 if qself.position == 0 {
1748 // This is a case like `<T>::B`, where there is no
1749 // trait to resolve. In that case, we leave the `B`
1750 // segment to be resolved by type-check.
1751 return Some(PartialRes::with_unresolved_segments(
1752 Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX)),
1757 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
1759 // Currently, `path` names the full item (`A::B::C`, in
1760 // our example). so we extract the prefix of that that is
1761 // the trait (the slice upto and including
1762 // `qself.position`). And then we recursively resolve that,
1763 // but with `qself` set to `None`.
1765 // However, setting `qself` to none (but not changing the
1766 // span) loses the information about where this path
1767 // *actually* appears, so for the purposes of the crate
1768 // lint we pass along information that this is the trait
1769 // name from a fully qualified path, and this also
1770 // contains the full span (the `CrateLint::QPathTrait`).
1771 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
1772 let partial_res = self.smart_resolve_path_fragment(
1775 &path[..=qself.position],
1777 PathSource::TraitItem(ns),
1778 CrateLint::QPathTrait { qpath_id: id, qpath_span: qself.path_span },
1781 // The remaining segments (the `C` in our example) will
1782 // have to be resolved by type-check, since that requires doing
1783 // trait resolution.
1784 return Some(PartialRes::with_unresolved_segments(
1785 partial_res.base_res(),
1786 partial_res.unresolved_segments() + path.len() - qself.position - 1,
1790 let result = match self.resolve_path(&path, Some(ns), true, span, crate_lint) {
1791 PathResult::NonModule(path_res) => path_res,
1792 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
1793 PartialRes::new(module.res().unwrap())
1795 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
1796 // don't report an error right away, but try to fallback to a primitive type.
1797 // So, we are still able to successfully resolve something like
1799 // use std::u8; // bring module u8 in scope
1800 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
1801 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
1802 // // not to non-existent std::u8::max_value
1805 // Such behavior is required for backward compatibility.
1806 // The same fallback is used when `a` resolves to nothing.
1807 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
1808 if (ns == TypeNS || path.len() > 1)
1811 .primitive_type_table
1813 .contains_key(&path[0].ident.name) =>
1815 let prim = self.r.primitive_type_table.primitive_types[&path[0].ident.name];
1816 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
1818 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
1819 PartialRes::new(module.res().unwrap())
1821 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
1822 self.r.report_error(span, ResolutionError::FailedToResolve { label, suggestion });
1823 PartialRes::new(Res::Err)
1825 PathResult::Module(..) | PathResult::Failed { .. } => return None,
1826 PathResult::Indeterminate => bug!("indetermined path result in resolve_qpath"),
1830 && result.base_res() != Res::Err
1831 && path[0].ident.name != kw::PathRoot
1832 && path[0].ident.name != kw::DollarCrate
1834 let unqualified_result = {
1835 match self.resolve_path(
1836 &[*path.last().unwrap()],
1842 PathResult::NonModule(path_res) => path_res.base_res(),
1843 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
1844 module.res().unwrap()
1846 _ => return Some(result),
1849 if result.base_res() == unqualified_result {
1850 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
1851 self.r.lint_buffer.buffer_lint(lint, id, span, "unnecessary qualification")
1858 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
1859 if let Some(label) = label {
1860 if label.ident.as_str().as_bytes()[1] != b'_' {
1861 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
1863 self.with_label_rib(NormalRibKind, |this| {
1864 let ident = label.ident.modern_and_legacy();
1865 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
1873 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
1874 self.with_resolved_label(label, id, |this| this.visit_block(block));
1877 fn resolve_block(&mut self, block: &'ast Block) {
1878 debug!("(resolving block) entering block");
1879 // Move down in the graph, if there's an anonymous module rooted here.
1880 let orig_module = self.parent_scope.module;
1881 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
1883 let mut num_macro_definition_ribs = 0;
1884 if let Some(anonymous_module) = anonymous_module {
1885 debug!("(resolving block) found anonymous module, moving down");
1886 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
1887 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
1888 self.parent_scope.module = anonymous_module;
1890 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
1893 // Descend into the block.
1894 for stmt in &block.stmts {
1895 if let StmtKind::Item(ref item) = stmt.kind {
1896 if let ItemKind::MacroDef(..) = item.kind {
1897 num_macro_definition_ribs += 1;
1898 let res = self.r.definitions.local_def_id(item.id);
1899 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
1900 self.label_ribs.push(Rib::new(MacroDefinition(res)));
1904 self.visit_stmt(stmt);
1908 self.parent_scope.module = orig_module;
1909 for _ in 0..num_macro_definition_ribs {
1910 self.ribs[ValueNS].pop();
1911 self.label_ribs.pop();
1913 self.ribs[ValueNS].pop();
1914 if anonymous_module.is_some() {
1915 self.ribs[TypeNS].pop();
1917 debug!("(resolving block) leaving block");
1920 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
1921 // First, record candidate traits for this expression if it could
1922 // result in the invocation of a method call.
1924 self.record_candidate_traits_for_expr_if_necessary(expr);
1926 // Next, resolve the node.
1928 ExprKind::Path(ref qself, ref path) => {
1929 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
1930 visit::walk_expr(self, expr);
1933 ExprKind::Struct(ref path, ..) => {
1934 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
1935 visit::walk_expr(self, expr);
1938 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
1939 let node_id = self.search_label(label.ident, |rib, ident| {
1940 rib.bindings.get(&ident.modern_and_legacy()).cloned()
1944 // Search again for close matches...
1945 // Picks the first label that is "close enough", which is not necessarily
1946 // the closest match
1947 let close_match = self.search_label(label.ident, |rib, ident| {
1948 let names = rib.bindings.iter().filter_map(|(id, _)| {
1949 if id.span.ctxt() == label.ident.span.ctxt() {
1955 find_best_match_for_name(names, &ident.as_str(), None)
1957 self.r.record_partial_res(expr.id, PartialRes::new(Res::Err));
1958 self.r.report_error(
1960 ResolutionError::UndeclaredLabel(&label.ident.as_str(), close_match),
1964 // Since this res is a label, it is never read.
1965 self.r.label_res_map.insert(expr.id, node_id);
1966 self.diagnostic_metadata.unused_labels.remove(&node_id);
1970 // visit `break` argument if any
1971 visit::walk_expr(self, expr);
1974 ExprKind::Let(ref pat, ref scrutinee) => {
1975 self.visit_expr(scrutinee);
1976 self.resolve_pattern_top(pat, PatternSource::Let);
1979 ExprKind::If(ref cond, ref then, ref opt_else) => {
1980 self.with_rib(ValueNS, NormalRibKind, |this| {
1981 this.visit_expr(cond);
1982 this.visit_block(then);
1984 opt_else.as_ref().map(|expr| self.visit_expr(expr));
1987 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
1989 ExprKind::While(ref cond, ref block, label) => {
1990 self.with_resolved_label(label, expr.id, |this| {
1991 this.with_rib(ValueNS, NormalRibKind, |this| {
1992 this.visit_expr(cond);
1993 this.visit_block(block);
1998 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
1999 self.visit_expr(iter_expr);
2000 self.with_rib(ValueNS, NormalRibKind, |this| {
2001 this.resolve_pattern_top(pat, PatternSource::For);
2002 this.resolve_labeled_block(label, expr.id, block);
2006 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
2008 // Equivalent to `visit::walk_expr` + passing some context to children.
2009 ExprKind::Field(ref subexpression, _) => {
2010 self.resolve_expr(subexpression, Some(expr));
2012 ExprKind::MethodCall(ref segment, ref arguments) => {
2013 let mut arguments = arguments.iter();
2014 self.resolve_expr(arguments.next().unwrap(), Some(expr));
2015 for argument in arguments {
2016 self.resolve_expr(argument, None);
2018 self.visit_path_segment(expr.span, segment);
2021 ExprKind::Call(ref callee, ref arguments) => {
2022 self.resolve_expr(callee, Some(expr));
2023 for argument in arguments {
2024 self.resolve_expr(argument, None);
2027 ExprKind::Type(ref type_expr, _) => {
2028 self.diagnostic_metadata.current_type_ascription.push(type_expr.span);
2029 visit::walk_expr(self, expr);
2030 self.diagnostic_metadata.current_type_ascription.pop();
2032 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
2033 // resolve the arguments within the proper scopes so that usages of them inside the
2034 // closure are detected as upvars rather than normal closure arg usages.
2035 ExprKind::Closure(_, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
2036 self.with_rib(ValueNS, NormalRibKind, |this| {
2037 // Resolve arguments:
2038 this.resolve_params(&fn_decl.inputs);
2039 // No need to resolve return type --
2040 // the outer closure return type is `FunctionRetTy::Default`.
2042 // Now resolve the inner closure
2044 // No need to resolve arguments: the inner closure has none.
2045 // Resolve the return type:
2046 visit::walk_fn_ret_ty(this, &fn_decl.output);
2048 this.visit_expr(body);
2053 visit::walk_expr(self, expr);
2058 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
2060 ExprKind::Field(_, ident) => {
2061 // FIXME(#6890): Even though you can't treat a method like a
2062 // field, we need to add any trait methods we find that match
2063 // the field name so that we can do some nice error reporting
2064 // later on in typeck.
2065 let traits = self.get_traits_containing_item(ident, ValueNS);
2066 self.r.trait_map.insert(expr.id, traits);
2068 ExprKind::MethodCall(ref segment, ..) => {
2069 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
2070 let traits = self.get_traits_containing_item(segment.ident, ValueNS);
2071 self.r.trait_map.insert(expr.id, traits);
2079 fn get_traits_containing_item(
2083 ) -> Vec<TraitCandidate<NodeId>> {
2084 debug!("(getting traits containing item) looking for '{}'", ident.name);
2086 let mut found_traits = Vec::new();
2087 // Look for the current trait.
2088 if let Some((module, _)) = self.current_trait_ref {
2091 .resolve_ident_in_module(
2092 ModuleOrUniformRoot::Module(module),
2101 let def_id = module.def_id().unwrap();
2102 found_traits.push(TraitCandidate { def_id: def_id, import_ids: smallvec![] });
2106 ident.span = ident.span.modern();
2107 let mut search_module = self.parent_scope.module;
2109 self.get_traits_in_module_containing_item(ident, ns, search_module, &mut found_traits);
2111 unwrap_or!(self.r.hygienic_lexical_parent(search_module, &mut ident.span), break);
2114 if let Some(prelude) = self.r.prelude {
2115 if !search_module.no_implicit_prelude {
2116 self.get_traits_in_module_containing_item(ident, ns, prelude, &mut found_traits);
2123 fn get_traits_in_module_containing_item(
2128 found_traits: &mut Vec<TraitCandidate<NodeId>>,
2130 assert!(ns == TypeNS || ns == ValueNS);
2131 let mut traits = module.traits.borrow_mut();
2132 if traits.is_none() {
2133 let mut collected_traits = Vec::new();
2134 module.for_each_child(self.r, |_, name, ns, binding| {
2138 match binding.res() {
2139 Res::Def(DefKind::Trait, _) | Res::Def(DefKind::TraitAlias, _) => {
2140 collected_traits.push((name, binding))
2145 *traits = Some(collected_traits.into_boxed_slice());
2148 for &(trait_name, binding) in traits.as_ref().unwrap().iter() {
2149 // Traits have pseudo-modules that can be used to search for the given ident.
2150 if let Some(module) = binding.module() {
2151 let mut ident = ident;
2152 if ident.span.glob_adjust(module.expansion, binding.span).is_none() {
2157 .resolve_ident_in_module_unadjusted(
2158 ModuleOrUniformRoot::Module(module),
2167 let import_ids = self.find_transitive_imports(&binding.kind, trait_name);
2168 let trait_def_id = module.def_id().unwrap();
2169 found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids });
2171 } else if let Res::Def(DefKind::TraitAlias, _) = binding.res() {
2172 // For now, just treat all trait aliases as possible candidates, since we don't
2173 // know if the ident is somewhere in the transitive bounds.
2174 let import_ids = self.find_transitive_imports(&binding.kind, trait_name);
2175 let trait_def_id = binding.res().def_id();
2176 found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids });
2178 bug!("candidate is not trait or trait alias?")
2183 fn find_transitive_imports(
2185 mut kind: &NameBindingKind<'_>,
2187 ) -> SmallVec<[NodeId; 1]> {
2188 let mut import_ids = smallvec![];
2189 while let NameBindingKind::Import { directive, binding, .. } = kind {
2190 self.r.maybe_unused_trait_imports.insert(directive.id);
2191 self.r.add_to_glob_map(&directive, trait_name);
2192 import_ids.push(directive.id);
2193 kind = &binding.kind;
2199 impl<'a> Resolver<'a> {
2200 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
2201 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
2202 visit::walk_crate(&mut late_resolution_visitor, krate);
2203 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
2204 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");