1 //! "Late resolution" is the pass that resolves most of names in a crate beside imports and macros.
2 //! It runs when the crate is fully expanded and its module structure is fully built.
3 //! So it just walks through the crate and resolves all the expressions, types, etc.
5 //! If you wonder why there's no `early.rs`, that's because it's split into three files -
6 //! `build_reduced_graph.rs`, `macros.rs` and `resolve_imports.rs`.
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};
15 use rustc::{bug, lint, span_bug};
16 use rustc::hir::def::{self, PartialRes, DefKind, CtorKind, PerNS};
17 use rustc::hir::def::Namespace::{self, *};
18 use rustc::hir::def_id::{DefId, CRATE_DEF_INDEX};
19 use rustc::hir::TraitCandidate;
20 use rustc::util::nodemap::{FxHashMap, FxHashSet};
21 use smallvec::{smallvec, SmallVec};
22 use syntax::{unwrap_or, walk_list};
25 use syntax::symbol::{kw, sym};
26 use syntax::util::lev_distance::find_best_match_for_name;
27 use syntax::visit::{self, Visitor, FnKind};
30 use std::collections::BTreeSet;
31 use std::mem::replace;
35 type Res = def::Res<NodeId>;
37 type IdentMap<T> = FxHashMap<Ident, T>;
39 /// Map from the name in a pattern to its binding mode.
40 type BindingMap = IdentMap<BindingInfo>;
42 #[derive(Copy, Clone, Debug)]
45 binding_mode: BindingMode,
48 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
57 fn descr(self) -> &'static str {
59 PatternSource::Match => "match binding",
60 PatternSource::Let => "let binding",
61 PatternSource::For => "for binding",
62 PatternSource::FnParam => "function parameter",
67 /// Denotes whether the context for the set of already bound bindings is a `Product`
68 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
69 /// See those functions for more information.
71 /// A product pattern context, e.g., `Variant(a, b)`.
73 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
77 /// Does this the item (from the item rib scope) allow generic parameters?
78 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
79 crate enum HasGenericParams { Yes, No }
81 /// The rib kind restricts certain accesses,
82 /// e.g. to a `Res::Local` of an outer item.
83 #[derive(Copy, Clone, Debug)]
84 crate enum RibKind<'a> {
85 /// No restriction needs to be applied.
88 /// We passed through an impl or trait and are now in one of its
89 /// methods or associated types. Allow references to ty params that impl or trait
90 /// binds. Disallow any other upvars (including other ty params that are
94 /// We passed through a function definition. Disallow upvars.
95 /// Permit only those const parameters that are specified in the function's generics.
98 /// We passed through an item scope. Disallow upvars.
99 ItemRibKind(HasGenericParams),
101 /// We're in a constant item. Can't refer to dynamic stuff.
104 /// We passed through a module.
105 ModuleRibKind(Module<'a>),
107 /// We passed through a `macro_rules!` statement
108 MacroDefinition(DefId),
110 /// All bindings in this rib are type parameters that can't be used
111 /// from the default of a type parameter because they're not declared
112 /// before said type parameter. Also see the `visit_generics` override.
113 ForwardTyParamBanRibKind,
117 // Whether this rib kind contains generic parameters, as opposed to local
119 crate fn contains_params(&self) -> bool {
123 | ConstantItemRibKind
125 | MacroDefinition(_) => false,
128 | 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> {
154 bindings: Default::default(),
160 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
161 crate enum AliasPossibility {
166 #[derive(Copy, Clone, Debug)]
167 crate enum PathSource<'a> {
168 // Type paths `Path`.
170 // Trait paths in bounds or impls.
171 Trait(AliasPossibility),
172 // Expression paths `path`, with optional parent context.
173 Expr(Option<&'a Expr>),
174 // Paths in path patterns `Path`.
176 // Paths in struct expressions and patterns `Path { .. }`.
178 // Paths in tuple struct patterns `Path(..)`.
180 // `m::A::B` in `<T as m::A>::B::C`.
181 TraitItem(Namespace),
184 impl<'a> PathSource<'a> {
185 fn namespace(self) -> Namespace {
187 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
188 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct => ValueNS,
189 PathSource::TraitItem(ns) => ns,
193 fn defer_to_typeck(self) -> bool {
195 PathSource::Type | PathSource::Expr(..) | PathSource::Pat |
196 PathSource::Struct | 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, _)) => {
217 match &call_expr.kind {
218 ExprKind::Path(_, path) => {
219 let mut msg = "function";
220 if let Some(segment) = path.segments.iter().last() {
221 if let Some(c) = segment.ident.to_string().chars().next() {
222 if c.is_uppercase() {
223 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, _) | Res::Def(DefKind::AssocConst, _) |
279 Res::SelfCtor(..) => true,
282 PathSource::TupleStruct => match res {
283 Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) | Res::SelfCtor(..) => true,
286 PathSource::Struct => match res {
287 Res::Def(DefKind::Struct, _)
288 | Res::Def(DefKind::Union, _)
289 | Res::Def(DefKind::Variant, _)
290 | Res::Def(DefKind::TyAlias, _)
291 | Res::Def(DefKind::AssocTy, _)
292 | Res::SelfTy(..) => true,
295 PathSource::TraitItem(ns) => match res {
296 Res::Def(DefKind::AssocConst, _)
297 | Res::Def(DefKind::Method, _) if ns == ValueNS => true,
298 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
304 fn error_code(self, has_unexpected_resolution: bool) -> &'static str {
305 syntax::diagnostic_used!(E0404);
306 syntax::diagnostic_used!(E0405);
307 syntax::diagnostic_used!(E0412);
308 syntax::diagnostic_used!(E0422);
309 syntax::diagnostic_used!(E0423);
310 syntax::diagnostic_used!(E0425);
311 syntax::diagnostic_used!(E0531);
312 syntax::diagnostic_used!(E0532);
313 syntax::diagnostic_used!(E0573);
314 syntax::diagnostic_used!(E0574);
315 syntax::diagnostic_used!(E0575);
316 syntax::diagnostic_used!(E0576);
317 match (self, has_unexpected_resolution) {
318 (PathSource::Trait(_), true) => "E0404",
319 (PathSource::Trait(_), false) => "E0405",
320 (PathSource::Type, true) => "E0573",
321 (PathSource::Type, false) => "E0412",
322 (PathSource::Struct, true) => "E0574",
323 (PathSource::Struct, false) => "E0422",
324 (PathSource::Expr(..), true) => "E0423",
325 (PathSource::Expr(..), false) => "E0425",
326 (PathSource::Pat, true) | (PathSource::TupleStruct, true) => "E0532",
327 (PathSource::Pat, false) | (PathSource::TupleStruct, false) => "E0531",
328 (PathSource::TraitItem(..), true) => "E0575",
329 (PathSource::TraitItem(..), false) => "E0576",
335 struct DiagnosticMetadata {
336 /// The current trait's associated types' ident, used for diagnostic suggestions.
337 current_trait_assoc_types: Vec<Ident>,
339 /// The current self type if inside an impl (used for better errors).
340 current_self_type: Option<Ty>,
342 /// The current self item if inside an ADT (used for better errors).
343 current_self_item: Option<NodeId>,
345 /// The current enclosing funciton (used for better errors).
346 current_function: Option<Span>,
348 /// A list of labels as of yet unused. Labels will be removed from this map when
349 /// they are used (in a `break` or `continue` statement)
350 unused_labels: FxHashMap<NodeId, Span>,
352 /// Only used for better errors on `fn(): fn()`.
353 current_type_ascription: Vec<Span>,
355 /// Only used for better errors on `let <pat>: <expr, not type>;`.
356 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
359 struct LateResolutionVisitor<'a, 'b> {
360 r: &'b mut Resolver<'a>,
362 /// The module that represents the current item scope.
363 parent_scope: ParentScope<'a>,
365 /// The current set of local scopes for types and values.
366 /// FIXME #4948: Reuse ribs to avoid allocation.
367 ribs: PerNS<Vec<Rib<'a>>>,
369 /// The current set of local scopes, for labels.
370 label_ribs: Vec<Rib<'a, NodeId>>,
372 /// The trait that the current context can refer to.
373 current_trait_ref: Option<(Module<'a>, TraitRef)>,
375 /// Fields used to add information to diagnostic errors.
376 diagnostic_metadata: DiagnosticMetadata,
379 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
380 impl<'a, 'tcx> Visitor<'tcx> for LateResolutionVisitor<'a, '_> {
381 fn visit_item(&mut self, item: &'tcx Item) {
382 self.resolve_item(item);
384 fn visit_arm(&mut self, arm: &'tcx Arm) {
385 self.resolve_arm(arm);
387 fn visit_block(&mut self, block: &'tcx Block) {
388 self.resolve_block(block);
390 fn visit_anon_const(&mut self, constant: &'tcx 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: &'tcx Expr) {
397 self.resolve_expr(expr, None);
399 fn visit_local(&mut self, local: &'tcx 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: &'tcx 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);
420 let res = self.resolve_ident_in_lexical_scope(self_ty, TypeNS, Some(ty.id), ty.span)
421 .map_or(Res::Err, |d| d.res());
422 self.r.record_partial_res(ty.id, PartialRes::new(res));
426 visit::walk_ty(self, ty);
428 fn visit_poly_trait_ref(&mut self,
429 tref: &'tcx PolyTraitRef,
430 m: &'tcx TraitBoundModifier) {
431 self.smart_resolve_path(tref.trait_ref.ref_id, None,
432 &tref.trait_ref.path, PathSource::Trait(AliasPossibility::Maybe));
433 visit::walk_poly_trait_ref(self, tref, m);
435 fn visit_foreign_item(&mut self, foreign_item: &'tcx ForeignItem) {
436 match foreign_item.kind {
437 ForeignItemKind::Fn(_, ref generics) => {
438 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
439 visit::walk_foreign_item(this, foreign_item);
442 ForeignItemKind::Static(..) => {
443 self.with_item_rib(HasGenericParams::No, |this| {
444 visit::walk_foreign_item(this, foreign_item);
447 ForeignItemKind::Ty | ForeignItemKind::Macro(..) => {
448 visit::walk_foreign_item(self, foreign_item);
452 fn visit_fn(&mut self, fn_kind: FnKind<'tcx>, declaration: &'tcx FnDecl, sp: Span, _: NodeId) {
453 let previous_value = replace(&mut self.diagnostic_metadata.current_function, Some(sp));
454 debug!("(resolving function) entering function");
455 let rib_kind = match fn_kind {
456 FnKind::ItemFn(..) => FnItemRibKind,
457 FnKind::Method(..) | FnKind::Closure(_) => NormalRibKind,
460 // Create a value rib for the function.
461 self.with_rib(ValueNS, rib_kind, |this| {
462 // Create a label rib for the function.
463 this.with_label_rib(rib_kind, |this| {
464 // Add each argument to the rib.
465 this.resolve_params(&declaration.inputs);
467 visit::walk_fn_ret_ty(this, &declaration.output);
469 // Resolve the function body, potentially inside the body of an async closure
471 FnKind::ItemFn(.., body) |
472 FnKind::Method(.., body) => this.visit_block(body),
473 FnKind::Closure(body) => this.visit_expr(body),
476 debug!("(resolving function) leaving function");
479 self.diagnostic_metadata.current_function = previous_value;
482 fn visit_generics(&mut self, generics: &'tcx Generics) {
483 // For type parameter defaults, we have to ban access
484 // to following type parameters, as the InternalSubsts can only
485 // provide previous type parameters as they're built. We
486 // put all the parameters on the ban list and then remove
487 // them one by one as they are processed and become available.
488 let mut default_ban_rib = Rib::new(ForwardTyParamBanRibKind);
489 let mut found_default = false;
490 default_ban_rib.bindings.extend(generics.params.iter()
491 .filter_map(|param| match param.kind {
492 GenericParamKind::Const { .. } |
493 GenericParamKind::Lifetime { .. } => None,
494 GenericParamKind::Type { ref default, .. } => {
495 found_default |= default.is_some();
497 Some((Ident::with_dummy_span(param.ident.name), Res::Err))
504 // rust-lang/rust#61631: The type `Self` is essentially
505 // another type parameter. For ADTs, we consider it
506 // well-defined only after all of the ADT type parameters have
507 // been provided. Therefore, we do not allow use of `Self`
508 // anywhere in ADT type parameter defaults.
510 // (We however cannot ban `Self` for defaults on *all* generic
511 // lists; e.g. trait generics can usefully refer to `Self`,
512 // such as in the case of `trait Add<Rhs = Self>`.)
513 if self.diagnostic_metadata.current_self_item.is_some() {
514 // (`Some` if + only if we are in ADT's generics.)
515 default_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
518 for param in &generics.params {
520 GenericParamKind::Lifetime { .. } => self.visit_generic_param(param),
521 GenericParamKind::Type { ref default, .. } => {
522 for bound in ¶m.bounds {
523 self.visit_param_bound(bound);
526 if let Some(ref ty) = default {
527 self.ribs[TypeNS].push(default_ban_rib);
529 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
532 // Allow all following defaults to refer to this type parameter.
533 default_ban_rib.bindings.remove(&Ident::with_dummy_span(param.ident.name));
535 GenericParamKind::Const { ref ty } => {
536 for bound in ¶m.bounds {
537 self.visit_param_bound(bound);
543 for p in &generics.where_clause.predicates {
544 self.visit_where_predicate(p);
549 impl<'a, 'b> LateResolutionVisitor<'a, '_> {
550 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b> {
551 // During late resolution we only track the module component of the parent scope,
552 // although it may be useful to track other components as well for diagnostics.
553 let graph_root = resolver.graph_root;
554 let parent_scope = ParentScope::module(graph_root);
555 let start_rib_kind = ModuleRibKind(graph_root);
556 LateResolutionVisitor {
560 value_ns: vec![Rib::new(start_rib_kind)],
561 type_ns: vec![Rib::new(start_rib_kind)],
562 macro_ns: vec![Rib::new(start_rib_kind)],
564 label_ribs: Vec::new(),
565 current_trait_ref: None,
566 diagnostic_metadata: DiagnosticMetadata::default(),
570 fn resolve_ident_in_lexical_scope(&mut self,
573 record_used_id: Option<NodeId>,
575 -> Option<LexicalScopeBinding<'a>> {
576 self.r.resolve_ident_in_lexical_scope(
577 ident, ns, &self.parent_scope, record_used_id, path_span, &self.ribs[ns]
584 opt_ns: Option<Namespace>, // `None` indicates a module path in import
587 crate_lint: CrateLint,
588 ) -> PathResult<'a> {
589 self.r.resolve_path_with_ribs(
590 path, opt_ns, &self.parent_scope, record_used, path_span, crate_lint, Some(&self.ribs)
596 // We maintain a list of value ribs and type ribs.
598 // Simultaneously, we keep track of the current position in the module
599 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
600 // the value or type namespaces, we first look through all the ribs and
601 // then query the module graph. When we resolve a name in the module
602 // namespace, we can skip all the ribs (since nested modules are not
603 // allowed within blocks in Rust) and jump straight to the current module
606 // Named implementations are handled separately. When we find a method
607 // call, we consult the module node to find all of the implementations in
608 // scope. This information is lazily cached in the module node. We then
609 // generate a fake "implementation scope" containing all the
610 // implementations thus found, for compatibility with old resolve pass.
612 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
617 work: impl FnOnce(&mut Self) -> T,
619 self.ribs[ns].push(Rib::new(kind));
620 let ret = work(self);
625 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
626 let id = self.r.definitions.local_def_id(id);
627 let module = self.r.module_map.get(&id).cloned(); // clones a reference
628 if let Some(module) = module {
629 // Move down in the graph.
630 let orig_module = replace(&mut self.parent_scope.module, module);
631 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
632 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
634 this.parent_scope.module = orig_module;
643 /// Searches the current set of local scopes for labels. Returns the first non-`None` label that
644 /// is returned by the given predicate function
646 /// Stops after meeting a closure.
647 fn search_label<P, R>(&self, mut ident: Ident, pred: P) -> Option<R>
648 where P: Fn(&Rib<'_, NodeId>, Ident) -> Option<R>
650 for rib in self.label_ribs.iter().rev() {
653 // If an invocation of this macro created `ident`, give up on `ident`
654 // and switch to `ident`'s source from the macro definition.
655 MacroDefinition(def) => {
656 if def == self.r.macro_def(ident.span.ctxt()) {
657 ident.span.remove_mark();
661 // Do not resolve labels across function boundary
665 let r = pred(rib, ident);
673 fn resolve_adt(&mut self, item: &Item, generics: &Generics) {
674 debug!("resolve_adt");
675 self.with_current_self_item(item, |this| {
676 this.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
677 let item_def_id = this.r.definitions.local_def_id(item.id);
678 this.with_self_rib(Res::SelfTy(None, Some(item_def_id)), |this| {
679 visit::walk_item(this, item);
685 fn future_proof_import(&mut self, use_tree: &UseTree) {
686 let segments = &use_tree.prefix.segments;
687 if !segments.is_empty() {
688 let ident = segments[0].ident;
689 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
693 let nss = match use_tree.kind {
694 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
697 let report_error = |this: &Self, ns| {
698 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
699 this.r.session.span_err(ident.span, &format!("imports cannot refer to {}", what));
703 match self.resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span) {
704 Some(LexicalScopeBinding::Res(..)) => {
705 report_error(self, ns);
707 Some(LexicalScopeBinding::Item(binding)) => {
708 let orig_blacklisted_binding =
709 replace(&mut self.r.blacklisted_binding, Some(binding));
710 if let Some(LexicalScopeBinding::Res(..)) =
711 self.resolve_ident_in_lexical_scope(ident, ns, None,
712 use_tree.prefix.span) {
713 report_error(self, ns);
715 self.r.blacklisted_binding = orig_blacklisted_binding;
720 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
721 for (use_tree, _) in use_trees {
722 self.future_proof_import(use_tree);
727 fn resolve_item(&mut self, item: &Item) {
728 let name = item.ident.name;
729 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
732 ItemKind::TyAlias(_, ref generics) |
733 ItemKind::OpaqueTy(_, ref generics) |
734 ItemKind::Fn(_, ref generics, _) => {
735 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes),
736 |this| visit::walk_item(this, item));
739 ItemKind::Enum(_, ref generics) |
740 ItemKind::Struct(_, ref generics) |
741 ItemKind::Union(_, ref generics) => {
742 self.resolve_adt(item, generics);
745 ItemKind::Impl(.., ref generics, ref opt_trait_ref, ref self_type, ref impl_items) =>
746 self.resolve_implementation(generics,
752 ItemKind::Trait(.., ref generics, ref bounds, ref trait_items) => {
753 // Create a new rib for the trait-wide type parameters.
754 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
755 let local_def_id = this.r.definitions.local_def_id(item.id);
756 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
757 this.visit_generics(generics);
758 walk_list!(this, visit_param_bound, bounds);
760 for trait_item in trait_items {
761 this.with_trait_items(trait_items, |this| {
762 this.with_generic_param_rib(&trait_item.generics, AssocItemRibKind,
764 match trait_item.kind {
765 TraitItemKind::Const(ref ty, ref default) => {
768 // Only impose the restrictions of
769 // ConstRibKind for an actual constant
770 // expression in a provided default.
771 if let Some(ref expr) = *default{
772 this.with_constant_rib(|this| {
773 this.visit_expr(expr);
777 TraitItemKind::Method(_, _) => {
778 visit::walk_trait_item(this, trait_item)
780 TraitItemKind::Type(..) => {
781 visit::walk_trait_item(this, trait_item)
783 TraitItemKind::Macro(_) => {
784 panic!("unexpanded macro in resolve!")
794 ItemKind::TraitAlias(ref generics, ref bounds) => {
795 // Create a new rib for the trait-wide type parameters.
796 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
797 let local_def_id = this.r.definitions.local_def_id(item.id);
798 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
799 this.visit_generics(generics);
800 walk_list!(this, visit_param_bound, bounds);
805 ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
806 self.with_scope(item.id, |this| {
807 visit::walk_item(this, item);
811 ItemKind::Static(ref ty, _, ref expr) |
812 ItemKind::Const(ref ty, ref expr) => {
813 debug!("resolve_item ItemKind::Const");
814 self.with_item_rib(HasGenericParams::No, |this| {
816 this.with_constant_rib(|this| {
817 this.visit_expr(expr);
822 ItemKind::Use(ref use_tree) => {
823 self.future_proof_import(use_tree);
826 ItemKind::ExternCrate(..) |
827 ItemKind::MacroDef(..) | ItemKind::GlobalAsm(..) => {
828 // do nothing, these are just around to be encoded
831 ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
835 fn with_generic_param_rib<'c, F>(&'c mut self, generics: &'c Generics, kind: RibKind<'a>, f: F)
836 where F: FnOnce(&mut Self)
838 debug!("with_generic_param_rib");
839 let mut function_type_rib = Rib::new(kind);
840 let mut function_value_rib = Rib::new(kind);
841 let mut seen_bindings = FxHashMap::default();
843 // We also can't shadow bindings from the parent item
844 if let AssocItemRibKind = kind {
845 let mut add_bindings_for_ns = |ns| {
846 let parent_rib = self.ribs[ns].iter()
847 .rfind(|r| if let ItemRibKind(_) = r.kind { true } else { false })
848 .expect("associated item outside of an item");
849 seen_bindings.extend(
850 parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)),
853 add_bindings_for_ns(ValueNS);
854 add_bindings_for_ns(TypeNS);
857 for param in &generics.params {
858 if let GenericParamKind::Lifetime { .. } = param.kind {
862 let def_kind = match param.kind {
863 GenericParamKind::Type { .. } => DefKind::TyParam,
864 GenericParamKind::Const { .. } => DefKind::ConstParam,
868 let ident = param.ident.modern();
869 debug!("with_generic_param_rib: {}", param.id);
871 if seen_bindings.contains_key(&ident) {
872 let span = seen_bindings.get(&ident).unwrap();
873 let err = ResolutionError::NameAlreadyUsedInParameterList(
877 self.r.report_error(param.ident.span, err);
879 seen_bindings.entry(ident).or_insert(param.ident.span);
881 // Plain insert (no renaming).
882 let res = Res::Def(def_kind, self.r.definitions.local_def_id(param.id));
885 GenericParamKind::Type { .. } => {
886 function_type_rib.bindings.insert(ident, res);
887 self.r.record_partial_res(param.id, PartialRes::new(res));
889 GenericParamKind::Const { .. } => {
890 function_value_rib.bindings.insert(ident, res);
891 self.r.record_partial_res(param.id, PartialRes::new(res));
897 self.ribs[ValueNS].push(function_value_rib);
898 self.ribs[TypeNS].push(function_type_rib);
902 self.ribs[TypeNS].pop();
903 self.ribs[ValueNS].pop();
906 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
907 self.label_ribs.push(Rib::new(kind));
909 self.label_ribs.pop();
912 fn with_item_rib(&mut self, has_generic_params: HasGenericParams, f: impl FnOnce(&mut Self)) {
913 let kind = ItemRibKind(has_generic_params);
914 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
917 fn with_constant_rib(&mut self, f: impl FnOnce(&mut Self)) {
918 debug!("with_constant_rib");
919 self.with_rib(ValueNS, ConstantItemRibKind, |this| {
920 this.with_label_rib(ConstantItemRibKind, f);
924 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
925 // Handle nested impls (inside fn bodies)
926 let previous_value = replace(
927 &mut self.diagnostic_metadata.current_self_type,
928 Some(self_type.clone()),
930 let result = f(self);
931 self.diagnostic_metadata.current_self_type = previous_value;
935 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
936 let previous_value = replace(
937 &mut self.diagnostic_metadata.current_self_item,
940 let result = f(self);
941 self.diagnostic_metadata.current_self_item = previous_value;
945 /// When evaluating a `trait` use its associated types' idents for suggestionsa in E0412.
946 fn with_trait_items<T>(
948 trait_items: &Vec<TraitItem>,
949 f: impl FnOnce(&mut Self) -> T,
951 let trait_assoc_types = replace(
952 &mut self.diagnostic_metadata.current_trait_assoc_types,
953 trait_items.iter().filter_map(|item| match &item.kind {
954 TraitItemKind::Type(bounds, _) if bounds.len() == 0 => Some(item.ident),
958 let result = f(self);
959 self.diagnostic_metadata.current_trait_assoc_types = trait_assoc_types;
963 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
964 fn with_optional_trait_ref<T>(
966 opt_trait_ref: Option<&TraitRef>,
967 f: impl FnOnce(&mut Self, Option<DefId>) -> T
969 let mut new_val = None;
970 let mut new_id = None;
971 if let Some(trait_ref) = opt_trait_ref {
972 let path: Vec<_> = Segment::from_path(&trait_ref.path);
973 let res = self.smart_resolve_path_fragment(
978 PathSource::Trait(AliasPossibility::No),
979 CrateLint::SimplePath(trait_ref.ref_id),
982 new_id = Some(res.def_id());
983 let span = trait_ref.path.span;
984 if let PathResult::Module(ModuleOrUniformRoot::Module(module)) =
990 CrateLint::SimplePath(trait_ref.ref_id),
993 new_val = Some((module, trait_ref.clone()));
997 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
998 let result = f(self, new_id);
999 self.current_trait_ref = original_trait_ref;
1003 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
1004 let mut self_type_rib = Rib::new(NormalRibKind);
1006 // Plain insert (no renaming, since types are not currently hygienic)
1007 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
1008 self.ribs[ns].push(self_type_rib);
1010 self.ribs[ns].pop();
1013 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
1014 self.with_self_rib_ns(TypeNS, self_res, f)
1017 fn resolve_implementation(&mut self,
1018 generics: &Generics,
1019 opt_trait_reference: &Option<TraitRef>,
1022 impl_items: &[ImplItem]) {
1023 debug!("resolve_implementation");
1024 // If applicable, create a rib for the type parameters.
1025 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1026 // Dummy self type for better errors if `Self` is used in the trait path.
1027 this.with_self_rib(Res::SelfTy(None, None), |this| {
1028 // Resolve the trait reference, if necessary.
1029 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1030 let item_def_id = this.r.definitions.local_def_id(item_id);
1031 this.with_self_rib(Res::SelfTy(trait_id, Some(item_def_id)), |this| {
1032 if let Some(trait_ref) = opt_trait_reference.as_ref() {
1033 // Resolve type arguments in the trait path.
1034 visit::walk_trait_ref(this, trait_ref);
1036 // Resolve the self type.
1037 this.visit_ty(self_type);
1038 // Resolve the generic parameters.
1039 this.visit_generics(generics);
1040 // Resolve the items within the impl.
1041 this.with_current_self_type(self_type, |this| {
1042 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
1043 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
1044 for impl_item in impl_items {
1045 // We also need a new scope for the impl item type parameters.
1046 this.with_generic_param_rib(&impl_item.generics,
1049 use crate::ResolutionError::*;
1050 match impl_item.kind {
1051 ImplItemKind::Const(..) => {
1053 "resolve_implementation ImplItemKind::Const",
1055 // If this is a trait impl, ensure the const
1057 this.check_trait_item(
1061 |n, s| ConstNotMemberOfTrait(n, s),
1064 this.with_constant_rib(|this| {
1065 visit::walk_impl_item(this, impl_item)
1068 ImplItemKind::Method(..) => {
1069 // If this is a trait impl, ensure the method
1071 this.check_trait_item(impl_item.ident,
1074 |n, s| MethodNotMemberOfTrait(n, s));
1076 visit::walk_impl_item(this, impl_item);
1078 ImplItemKind::TyAlias(ref ty) => {
1079 // If this is a trait impl, ensure the type
1081 this.check_trait_item(impl_item.ident,
1084 |n, s| TypeNotMemberOfTrait(n, s));
1088 ImplItemKind::OpaqueTy(ref bounds) => {
1089 // If this is a trait impl, ensure the type
1091 this.check_trait_item(impl_item.ident,
1094 |n, s| TypeNotMemberOfTrait(n, s));
1096 for bound in bounds {
1097 this.visit_param_bound(bound);
1100 ImplItemKind::Macro(_) =>
1101 panic!("unexpanded macro in resolve!"),
1113 fn check_trait_item<F>(&mut self, ident: Ident, ns: Namespace, span: Span, err: F)
1114 where F: FnOnce(Name, &str) -> ResolutionError<'_>
1116 // If there is a TraitRef in scope for an impl, then the method must be in the
1118 if let Some((module, _)) = self.current_trait_ref {
1119 if self.r.resolve_ident_in_module(
1120 ModuleOrUniformRoot::Module(module),
1127 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
1128 self.r.report_error(span, err(ident.name, &path_names_to_string(path)));
1133 fn resolve_params(&mut self, params: &[Param]) {
1134 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1135 for Param { pat, ty, .. } in params {
1136 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1138 debug!("(resolving function / closure) recorded parameter");
1142 fn resolve_local(&mut self, local: &Local) {
1143 // Resolve the type.
1144 walk_list!(self, visit_ty, &local.ty);
1146 // Resolve the initializer.
1147 walk_list!(self, visit_expr, &local.init);
1149 // Resolve the pattern.
1150 self.resolve_pattern_top(&local.pat, PatternSource::Let);
1153 /// build a map from pattern identifiers to binding-info's.
1154 /// this is done hygienically. This could arise for a macro
1155 /// that expands into an or-pattern where one 'x' was from the
1156 /// user and one 'x' came from the macro.
1157 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1158 let mut binding_map = FxHashMap::default();
1160 pat.walk(&mut |pat| {
1162 PatKind::Ident(binding_mode, ident, ref sub_pat)
1163 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
1165 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
1167 PatKind::Or(ref ps) => {
1168 // Check the consistency of this or-pattern and
1169 // then add all bindings to the larger map.
1170 for bm in self.check_consistent_bindings(ps) {
1171 binding_map.extend(bm);
1184 fn is_base_res_local(&self, nid: NodeId) -> bool {
1185 match self.r.partial_res_map.get(&nid).map(|res| res.base_res()) {
1186 Some(Res::Local(..)) => true,
1191 /// Checks that all of the arms in an or-pattern have exactly the
1192 /// same set of bindings, with the same binding modes for each.
1193 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
1194 let mut missing_vars = FxHashMap::default();
1195 let mut inconsistent_vars = FxHashMap::default();
1197 // 1) Compute the binding maps of all arms.
1198 let maps = pats.iter()
1199 .map(|pat| self.binding_mode_map(pat))
1200 .collect::<Vec<_>>();
1202 // 2) Record any missing bindings or binding mode inconsistencies.
1203 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
1204 // Check against all arms except for the same pattern which is always self-consistent.
1205 let inners = pats.iter().enumerate()
1206 .filter(|(_, pat)| pat.id != pat_outer.id)
1207 .flat_map(|(idx, _)| maps[idx].iter())
1208 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
1210 for (name, info, &binding_inner) in inners {
1212 None => { // The inner binding is missing in the outer.
1213 let binding_error = missing_vars
1215 .or_insert_with(|| BindingError {
1217 origin: BTreeSet::new(),
1218 target: BTreeSet::new(),
1219 could_be_path: name.as_str().starts_with(char::is_uppercase),
1221 binding_error.origin.insert(binding_inner.span);
1222 binding_error.target.insert(pat_outer.span);
1224 Some(binding_outer) => {
1225 if binding_outer.binding_mode != binding_inner.binding_mode {
1226 // The binding modes in the outer and inner bindings differ.
1229 .or_insert((binding_inner.span, binding_outer.span));
1236 // 3) Report all missing variables we found.
1237 let mut missing_vars = missing_vars.iter_mut().collect::<Vec<_>>();
1238 missing_vars.sort();
1239 for (name, mut v) in missing_vars {
1240 if inconsistent_vars.contains_key(name) {
1241 v.could_be_path = false;
1243 self.r.report_error(
1244 *v.origin.iter().next().unwrap(),
1245 ResolutionError::VariableNotBoundInPattern(v));
1248 // 4) Report all inconsistencies in binding modes we found.
1249 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
1250 inconsistent_vars.sort();
1251 for (name, v) in inconsistent_vars {
1252 self.r.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
1255 // 5) Finally bubble up all the binding maps.
1259 /// Check the consistency of the outermost or-patterns.
1260 fn check_consistent_bindings_top(&mut self, pat: &Pat) {
1261 pat.walk(&mut |pat| match pat.kind {
1262 PatKind::Or(ref ps) => {
1263 self.check_consistent_bindings(ps);
1270 fn resolve_arm(&mut self, arm: &Arm) {
1271 self.with_rib(ValueNS, NormalRibKind, |this| {
1272 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
1273 walk_list!(this, visit_expr, &arm.guard);
1274 this.visit_expr(&arm.body);
1278 /// Arising from `source`, resolve a top level pattern.
1279 fn resolve_pattern_top(&mut self, pat: &Pat, pat_src: PatternSource) {
1280 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1281 self.resolve_pattern(pat, pat_src, &mut bindings);
1287 pat_src: PatternSource,
1288 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1290 self.resolve_pattern_inner(pat, pat_src, bindings);
1291 // This has to happen *after* we determine which pat_idents are variants:
1292 self.check_consistent_bindings_top(pat);
1293 visit::walk_pat(self, pat);
1296 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
1300 /// A stack of sets of bindings accumulated.
1302 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
1303 /// be interpreted as re-binding an already bound binding. This results in an error.
1304 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
1305 /// in reusing this binding rather than creating a fresh one.
1307 /// When called at the top level, the stack must have a single element
1308 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
1309 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
1310 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
1311 /// When each `p_i` has been dealt with, the top set is merged with its parent.
1312 /// When a whole or-pattern has been dealt with, the thing happens.
1314 /// See the implementation and `fresh_binding` for more details.
1315 fn resolve_pattern_inner(
1318 pat_src: PatternSource,
1319 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1321 // Visit all direct subpatterns of this pattern.
1322 pat.walk(&mut |pat| {
1323 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
1325 PatKind::Ident(bmode, ident, ref sub) => {
1326 // First try to resolve the identifier as some existing entity,
1327 // then fall back to a fresh binding.
1328 let has_sub = sub.is_some();
1329 let res = self.try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub)
1330 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
1331 self.r.record_partial_res(pat.id, PartialRes::new(res));
1333 PatKind::TupleStruct(ref path, ..) => {
1334 self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);
1336 PatKind::Path(ref qself, ref path) => {
1337 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
1339 PatKind::Struct(ref path, ..) => {
1340 self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
1342 PatKind::Or(ref ps) => {
1343 // Add a new set of bindings to the stack. `Or` here records that when a
1344 // binding already exists in this set, it should not result in an error because
1345 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
1346 bindings.push((PatBoundCtx::Or, Default::default()));
1348 // Now we need to switch back to a product context so that each
1349 // part of the or-pattern internally rejects already bound names.
1350 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
1351 bindings.push((PatBoundCtx::Product, Default::default()));
1352 self.resolve_pattern_inner(p, pat_src, bindings);
1353 // Move up the non-overlapping bindings to the or-pattern.
1354 // Existing bindings just get "merged".
1355 let collected = bindings.pop().unwrap().1;
1356 bindings.last_mut().unwrap().1.extend(collected);
1358 // This or-pattern itself can itself be part of a product,
1359 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
1360 // Both cases bind `a` again in a product pattern and must be rejected.
1361 let collected = bindings.pop().unwrap().1;
1362 bindings.last_mut().unwrap().1.extend(collected);
1364 // Prevent visiting `ps` as we've already done so above.
1377 pat_src: PatternSource,
1378 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1380 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
1381 // (We must not add it if it's in the bindings map because that breaks the assumptions
1382 // later passes make about or-patterns.)
1383 let ident = ident.modern_and_legacy();
1385 // Walk outwards the stack of products / or-patterns and
1386 // find out if the identifier has been bound in any of these.
1387 let mut already_bound_and = false;
1388 let mut already_bound_or = false;
1389 for (is_sum, set) in bindings.iter_mut().rev() {
1390 match (is_sum, set.get(&ident).cloned()) {
1391 // Already bound in a product pattern, e.g. `(a, a)` which is not allowed.
1392 (PatBoundCtx::Product, Some(..)) => already_bound_and = true,
1393 // Already bound in an or-pattern, e.g. `V1(a) | V2(a)`.
1394 // This is *required* for consistency which is checked later.
1395 (PatBoundCtx::Or, Some(..)) => already_bound_or = true,
1396 // Not already bound here.
1401 if already_bound_and {
1402 // Overlap in a product pattern somewhere; report an error.
1403 use ResolutionError::*;
1404 let error = match pat_src {
1405 // `fn f(a: u8, a: u8)`:
1406 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
1408 _ => IdentifierBoundMoreThanOnceInSamePattern,
1410 self.r.report_error(ident.span, error(&ident.as_str()));
1413 // Record as bound if it's valid:
1414 let ident_valid = ident.name != kw::Invalid;
1416 bindings.last_mut().unwrap().1.insert(ident);
1419 if already_bound_or {
1420 // `Variant1(a) | Variant2(a)`, ok
1421 // Reuse definition from the first `a`.
1422 self.innermost_rib_bindings(ValueNS)[&ident]
1424 let res = Res::Local(pat_id);
1426 // A completely fresh binding add to the set if it's valid.
1427 self.innermost_rib_bindings(ValueNS).insert(ident, res);
1433 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
1434 &mut self.ribs[ns].last_mut().unwrap().bindings
1437 fn try_resolve_as_non_binding(
1439 pat_src: PatternSource,
1445 let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, pat.span)?.item()?;
1446 let res = binding.res();
1448 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
1449 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
1450 // also be interpreted as a path to e.g. a constant, variant, etc.
1451 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Immutable);
1454 Res::Def(DefKind::Ctor(_, CtorKind::Const), _) |
1455 Res::Def(DefKind::Const, _) if is_syntactic_ambiguity => {
1456 // Disambiguate in favor of a unit struct/variant or constant pattern.
1457 self.r.record_use(ident, ValueNS, binding, false);
1460 Res::Def(DefKind::Ctor(..), _)
1461 | Res::Def(DefKind::Const, _)
1462 | Res::Def(DefKind::Static, _) => {
1463 // This is unambiguously a fresh binding, either syntactically
1464 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
1465 // to something unusable as a pattern (e.g., constructor function),
1466 // but we still conservatively report an error, see
1467 // issues/33118#issuecomment-233962221 for one reason why.
1468 self.r.report_error(
1470 ResolutionError::BindingShadowsSomethingUnacceptable(
1478 Res::Def(DefKind::Fn, _) | Res::Err => {
1479 // These entities are explicitly allowed to be shadowed by fresh bindings.
1483 span_bug!(ident.span, "unexpected resolution for an \
1484 identifier in pattern: {:?}", res);
1489 // High-level and context dependent path resolution routine.
1490 // Resolves the path and records the resolution into definition map.
1491 // If resolution fails tries several techniques to find likely
1492 // resolution candidates, suggest imports or other help, and report
1493 // errors in user friendly way.
1494 fn smart_resolve_path(&mut self,
1496 qself: Option<&QSelf>,
1498 source: PathSource<'_>) {
1499 self.smart_resolve_path_fragment(
1502 &Segment::from_path(path),
1505 CrateLint::SimplePath(id),
1509 fn smart_resolve_path_fragment(&mut self,
1511 qself: Option<&QSelf>,
1514 source: PathSource<'_>,
1515 crate_lint: CrateLint)
1517 let ns = source.namespace();
1518 let is_expected = &|res| source.is_expected(res);
1520 let report_errors = |this: &mut Self, res: Option<Res>| {
1521 let (err, candidates) = this.smart_resolve_report_errors(path, span, source, res);
1522 let def_id = this.parent_scope.module.normal_ancestor_id;
1523 let node_id = this.r.definitions.as_local_node_id(def_id).unwrap();
1524 let better = res.is_some();
1525 this.r.use_injections.push(UseError { err, candidates, node_id, better });
1526 PartialRes::new(Res::Err)
1529 let partial_res = match self.resolve_qpath_anywhere(
1535 source.defer_to_typeck(),
1538 Some(partial_res) if partial_res.unresolved_segments() == 0 => {
1539 if is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err {
1542 // Add a temporary hack to smooth the transition to new struct ctor
1543 // visibility rules. See #38932 for more details.
1545 if let Res::Def(DefKind::Struct, def_id) = partial_res.base_res() {
1546 if let Some((ctor_res, ctor_vis))
1547 = self.r.struct_constructors.get(&def_id).cloned() {
1548 if is_expected(ctor_res) &&
1549 self.r.is_accessible_from(ctor_vis, self.parent_scope.module) {
1550 let lint = lint::builtin::LEGACY_CONSTRUCTOR_VISIBILITY;
1551 self.r.lint_buffer.buffer_lint(lint, id, span,
1552 "private struct constructors are not usable through \
1553 re-exports in outer modules",
1555 res = Some(PartialRes::new(ctor_res));
1560 res.unwrap_or_else(|| report_errors(self, Some(partial_res.base_res())))
1563 Some(partial_res) if source.defer_to_typeck() => {
1564 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
1565 // or `<T>::A::B`. If `B` should be resolved in value namespace then
1566 // it needs to be added to the trait map.
1568 let item_name = path.last().unwrap().ident;
1569 let traits = self.get_traits_containing_item(item_name, ns);
1570 self.r.trait_map.insert(id, traits);
1573 let mut std_path = vec![Segment::from_ident(Ident::with_dummy_span(sym::std))];
1574 std_path.extend(path);
1575 if self.r.primitive_type_table.primitive_types.contains_key(&path[0].ident.name) {
1576 let cl = CrateLint::No;
1578 if let PathResult::Module(_) | PathResult::NonModule(_) =
1579 self.resolve_path(&std_path, ns, false, span, cl) {
1580 // check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
1581 let item_span = path.iter().last().map(|segment| segment.ident.span)
1583 debug!("accessed item from `std` submodule as a bare type {:?}", std_path);
1584 let mut hm = self.r.session.confused_type_with_std_module.borrow_mut();
1585 hm.insert(item_span, span);
1586 // In some places (E0223) we only have access to the full path
1587 hm.insert(span, span);
1592 _ => report_errors(self, None)
1595 if let PathSource::TraitItem(..) = source {} else {
1596 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
1597 self.r.record_partial_res(id, partial_res);
1602 fn self_type_is_available(&mut self, span: Span) -> bool {
1603 let binding = self.resolve_ident_in_lexical_scope(
1604 Ident::with_dummy_span(kw::SelfUpper),
1609 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1612 fn self_value_is_available(&mut self, self_span: Span, path_span: Span) -> bool {
1613 let ident = Ident::new(kw::SelfLower, self_span);
1614 let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, path_span);
1615 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1618 // Resolve in alternative namespaces if resolution in the primary namespace fails.
1619 fn resolve_qpath_anywhere(
1622 qself: Option<&QSelf>,
1624 primary_ns: Namespace,
1626 defer_to_typeck: bool,
1627 crate_lint: CrateLint,
1628 ) -> Option<PartialRes> {
1629 let mut fin_res = None;
1630 for (i, ns) in [primary_ns, TypeNS, ValueNS].iter().cloned().enumerate() {
1631 if i == 0 || ns != primary_ns {
1632 match self.resolve_qpath(id, qself, path, ns, span, crate_lint) {
1633 // If defer_to_typeck, then resolution > no resolution,
1634 // otherwise full resolution > partial resolution > no resolution.
1635 Some(partial_res) if partial_res.unresolved_segments() == 0 ||
1637 return Some(partial_res),
1638 partial_res => if fin_res.is_none() { fin_res = partial_res },
1644 assert!(primary_ns != MacroNS);
1645 if qself.is_none() {
1646 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
1647 let path = Path { segments: path.iter().map(path_seg).collect(), span };
1648 if let Ok((_, res)) = self.r.resolve_macro_path(
1649 &path, None, &self.parent_scope, false, false
1651 return Some(PartialRes::new(res));
1658 /// Handles paths that may refer to associated items.
1662 qself: Option<&QSelf>,
1666 crate_lint: CrateLint,
1667 ) -> Option<PartialRes> {
1669 "resolve_qpath(id={:?}, qself={:?}, path={:?}, ns={:?}, span={:?})",
1677 if let Some(qself) = qself {
1678 if qself.position == 0 {
1679 // This is a case like `<T>::B`, where there is no
1680 // trait to resolve. In that case, we leave the `B`
1681 // segment to be resolved by type-check.
1682 return Some(PartialRes::with_unresolved_segments(
1683 Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX)), path.len()
1687 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
1689 // Currently, `path` names the full item (`A::B::C`, in
1690 // our example). so we extract the prefix of that that is
1691 // the trait (the slice upto and including
1692 // `qself.position`). And then we recursively resolve that,
1693 // but with `qself` set to `None`.
1695 // However, setting `qself` to none (but not changing the
1696 // span) loses the information about where this path
1697 // *actually* appears, so for the purposes of the crate
1698 // lint we pass along information that this is the trait
1699 // name from a fully qualified path, and this also
1700 // contains the full span (the `CrateLint::QPathTrait`).
1701 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
1702 let partial_res = self.smart_resolve_path_fragment(
1705 &path[..=qself.position],
1707 PathSource::TraitItem(ns),
1708 CrateLint::QPathTrait {
1710 qpath_span: qself.path_span,
1714 // The remaining segments (the `C` in our example) will
1715 // have to be resolved by type-check, since that requires doing
1716 // trait resolution.
1717 return Some(PartialRes::with_unresolved_segments(
1718 partial_res.base_res(),
1719 partial_res.unresolved_segments() + path.len() - qself.position - 1,
1723 let result = match self.resolve_path(&path, Some(ns), true, span, crate_lint) {
1724 PathResult::NonModule(path_res) => path_res,
1725 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
1726 PartialRes::new(module.res().unwrap())
1728 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
1729 // don't report an error right away, but try to fallback to a primitive type.
1730 // So, we are still able to successfully resolve something like
1732 // use std::u8; // bring module u8 in scope
1733 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
1734 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
1735 // // not to non-existent std::u8::max_value
1738 // Such behavior is required for backward compatibility.
1739 // The same fallback is used when `a` resolves to nothing.
1740 PathResult::Module(ModuleOrUniformRoot::Module(_)) |
1741 PathResult::Failed { .. }
1742 if (ns == TypeNS || path.len() > 1) &&
1743 self.r.primitive_type_table.primitive_types
1744 .contains_key(&path[0].ident.name) => {
1745 let prim = self.r.primitive_type_table.primitive_types[&path[0].ident.name];
1746 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
1748 PathResult::Module(ModuleOrUniformRoot::Module(module)) =>
1749 PartialRes::new(module.res().unwrap()),
1750 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
1751 self.r.report_error(span, ResolutionError::FailedToResolve { label, suggestion });
1752 PartialRes::new(Res::Err)
1754 PathResult::Module(..) | PathResult::Failed { .. } => return None,
1755 PathResult::Indeterminate => bug!("indetermined path result in resolve_qpath"),
1758 if path.len() > 1 && result.base_res() != Res::Err &&
1759 path[0].ident.name != kw::PathRoot &&
1760 path[0].ident.name != kw::DollarCrate {
1761 let unqualified_result = {
1762 match self.resolve_path(
1763 &[*path.last().unwrap()],
1769 PathResult::NonModule(path_res) => path_res.base_res(),
1770 PathResult::Module(ModuleOrUniformRoot::Module(module)) =>
1771 module.res().unwrap(),
1772 _ => return Some(result),
1775 if result.base_res() == unqualified_result {
1776 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
1777 self.r.lint_buffer.buffer_lint(lint, id, span, "unnecessary qualification")
1784 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
1785 if let Some(label) = label {
1786 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
1787 self.with_label_rib(NormalRibKind, |this| {
1788 let ident = label.ident.modern_and_legacy();
1789 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
1797 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &Block) {
1798 self.with_resolved_label(label, id, |this| this.visit_block(block));
1801 fn resolve_block(&mut self, block: &Block) {
1802 debug!("(resolving block) entering block");
1803 // Move down in the graph, if there's an anonymous module rooted here.
1804 let orig_module = self.parent_scope.module;
1805 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
1807 let mut num_macro_definition_ribs = 0;
1808 if let Some(anonymous_module) = anonymous_module {
1809 debug!("(resolving block) found anonymous module, moving down");
1810 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
1811 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
1812 self.parent_scope.module = anonymous_module;
1814 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
1817 // Descend into the block.
1818 for stmt in &block.stmts {
1819 if let StmtKind::Item(ref item) = stmt.kind {
1820 if let ItemKind::MacroDef(..) = item.kind {
1821 num_macro_definition_ribs += 1;
1822 let res = self.r.definitions.local_def_id(item.id);
1823 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
1824 self.label_ribs.push(Rib::new(MacroDefinition(res)));
1828 self.visit_stmt(stmt);
1832 self.parent_scope.module = orig_module;
1833 for _ in 0 .. num_macro_definition_ribs {
1834 self.ribs[ValueNS].pop();
1835 self.label_ribs.pop();
1837 self.ribs[ValueNS].pop();
1838 if anonymous_module.is_some() {
1839 self.ribs[TypeNS].pop();
1841 debug!("(resolving block) leaving block");
1844 fn resolve_expr(&mut self, expr: &Expr, parent: Option<&Expr>) {
1845 // First, record candidate traits for this expression if it could
1846 // result in the invocation of a method call.
1848 self.record_candidate_traits_for_expr_if_necessary(expr);
1850 // Next, resolve the node.
1852 ExprKind::Path(ref qself, ref path) => {
1853 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
1854 visit::walk_expr(self, expr);
1857 ExprKind::Struct(ref path, ..) => {
1858 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
1859 visit::walk_expr(self, expr);
1862 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
1863 let node_id = self.search_label(label.ident, |rib, ident| {
1864 rib.bindings.get(&ident.modern_and_legacy()).cloned()
1868 // Search again for close matches...
1869 // Picks the first label that is "close enough", which is not necessarily
1870 // the closest match
1871 let close_match = self.search_label(label.ident, |rib, ident| {
1872 let names = rib.bindings.iter().filter_map(|(id, _)| {
1873 if id.span.ctxt() == label.ident.span.ctxt() {
1879 find_best_match_for_name(names, &ident.as_str(), None)
1881 self.r.record_partial_res(expr.id, PartialRes::new(Res::Err));
1882 self.r.report_error(
1884 ResolutionError::UndeclaredLabel(&label.ident.as_str(), close_match),
1888 // Since this res is a label, it is never read.
1889 self.r.label_res_map.insert(expr.id, node_id);
1890 self.diagnostic_metadata.unused_labels.remove(&node_id);
1894 // visit `break` argument if any
1895 visit::walk_expr(self, expr);
1898 ExprKind::Let(ref pat, ref scrutinee) => {
1899 self.visit_expr(scrutinee);
1900 self.resolve_pattern_top(pat, PatternSource::Let);
1903 ExprKind::If(ref cond, ref then, ref opt_else) => {
1904 self.with_rib(ValueNS, NormalRibKind, |this| {
1905 this.visit_expr(cond);
1906 this.visit_block(then);
1908 opt_else.as_ref().map(|expr| self.visit_expr(expr));
1911 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
1913 ExprKind::While(ref cond, ref block, label) => {
1914 self.with_resolved_label(label, expr.id, |this| {
1915 this.with_rib(ValueNS, NormalRibKind, |this| {
1916 this.visit_expr(cond);
1917 this.visit_block(block);
1922 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
1923 self.visit_expr(iter_expr);
1924 self.with_rib(ValueNS, NormalRibKind, |this| {
1925 this.resolve_pattern_top(pat, PatternSource::For);
1926 this.resolve_labeled_block(label, expr.id, block);
1930 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
1932 // Equivalent to `visit::walk_expr` + passing some context to children.
1933 ExprKind::Field(ref subexpression, _) => {
1934 self.resolve_expr(subexpression, Some(expr));
1936 ExprKind::MethodCall(ref segment, ref arguments) => {
1937 let mut arguments = arguments.iter();
1938 self.resolve_expr(arguments.next().unwrap(), Some(expr));
1939 for argument in arguments {
1940 self.resolve_expr(argument, None);
1942 self.visit_path_segment(expr.span, segment);
1945 ExprKind::Call(ref callee, ref arguments) => {
1946 self.resolve_expr(callee, Some(expr));
1947 for argument in arguments {
1948 self.resolve_expr(argument, None);
1951 ExprKind::Type(ref type_expr, _) => {
1952 self.diagnostic_metadata.current_type_ascription.push(type_expr.span);
1953 visit::walk_expr(self, expr);
1954 self.diagnostic_metadata.current_type_ascription.pop();
1956 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
1957 // resolve the arguments within the proper scopes so that usages of them inside the
1958 // closure are detected as upvars rather than normal closure arg usages.
1959 ExprKind::Closure(_, IsAsync::Async { .. }, _, ref fn_decl, ref body, _span) => {
1960 self.with_rib(ValueNS, NormalRibKind, |this| {
1961 // Resolve arguments:
1962 this.resolve_params(&fn_decl.inputs);
1963 // No need to resolve return type --
1964 // the outer closure return type is `FunctionRetTy::Default`.
1966 // Now resolve the inner closure
1968 // No need to resolve arguments: the inner closure has none.
1969 // Resolve the return type:
1970 visit::walk_fn_ret_ty(this, &fn_decl.output);
1972 this.visit_expr(body);
1977 visit::walk_expr(self, expr);
1982 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
1984 ExprKind::Field(_, ident) => {
1985 // FIXME(#6890): Even though you can't treat a method like a
1986 // field, we need to add any trait methods we find that match
1987 // the field name so that we can do some nice error reporting
1988 // later on in typeck.
1989 let traits = self.get_traits_containing_item(ident, ValueNS);
1990 self.r.trait_map.insert(expr.id, traits);
1992 ExprKind::MethodCall(ref segment, ..) => {
1993 debug!("(recording candidate traits for expr) recording traits for {}",
1995 let traits = self.get_traits_containing_item(segment.ident, ValueNS);
1996 self.r.trait_map.insert(expr.id, traits);
2004 fn get_traits_containing_item(&mut self, mut ident: Ident, ns: Namespace)
2005 -> Vec<TraitCandidate> {
2006 debug!("(getting traits containing item) looking for '{}'", ident.name);
2008 let mut found_traits = Vec::new();
2009 // Look for the current trait.
2010 if let Some((module, _)) = self.current_trait_ref {
2011 if self.r.resolve_ident_in_module(
2012 ModuleOrUniformRoot::Module(module),
2019 let def_id = module.def_id().unwrap();
2020 found_traits.push(TraitCandidate { def_id: def_id, import_ids: smallvec![] });
2024 ident.span = ident.span.modern();
2025 let mut search_module = self.parent_scope.module;
2027 self.get_traits_in_module_containing_item(ident, ns, search_module, &mut found_traits);
2028 search_module = unwrap_or!(
2029 self.r.hygienic_lexical_parent(search_module, &mut ident.span), break
2033 if let Some(prelude) = self.r.prelude {
2034 if !search_module.no_implicit_prelude {
2035 self.get_traits_in_module_containing_item(ident, ns, prelude, &mut found_traits);
2042 fn get_traits_in_module_containing_item(&mut self,
2046 found_traits: &mut Vec<TraitCandidate>) {
2047 assert!(ns == TypeNS || ns == ValueNS);
2048 let mut traits = module.traits.borrow_mut();
2049 if traits.is_none() {
2050 let mut collected_traits = Vec::new();
2051 module.for_each_child(self.r, |_, name, ns, binding| {
2052 if ns != TypeNS { return }
2053 match binding.res() {
2054 Res::Def(DefKind::Trait, _) |
2055 Res::Def(DefKind::TraitAlias, _) => collected_traits.push((name, binding)),
2059 *traits = Some(collected_traits.into_boxed_slice());
2062 for &(trait_name, binding) in traits.as_ref().unwrap().iter() {
2063 // Traits have pseudo-modules that can be used to search for the given ident.
2064 if let Some(module) = binding.module() {
2065 let mut ident = ident;
2066 if ident.span.glob_adjust(
2072 if self.r.resolve_ident_in_module_unadjusted(
2073 ModuleOrUniformRoot::Module(module),
2080 let import_ids = self.find_transitive_imports(&binding.kind, trait_name);
2081 let trait_def_id = module.def_id().unwrap();
2082 found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids });
2084 } else if let Res::Def(DefKind::TraitAlias, _) = binding.res() {
2085 // For now, just treat all trait aliases as possible candidates, since we don't
2086 // know if the ident is somewhere in the transitive bounds.
2087 let import_ids = self.find_transitive_imports(&binding.kind, trait_name);
2088 let trait_def_id = binding.res().def_id();
2089 found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids });
2091 bug!("candidate is not trait or trait alias?")
2096 fn find_transitive_imports(&mut self, mut kind: &NameBindingKind<'_>,
2097 trait_name: Ident) -> SmallVec<[NodeId; 1]> {
2098 let mut import_ids = smallvec![];
2099 while let NameBindingKind::Import { directive, binding, .. } = kind {
2100 self.r.maybe_unused_trait_imports.insert(directive.id);
2101 self.r.add_to_glob_map(&directive, trait_name);
2102 import_ids.push(directive.id);
2103 kind = &binding.kind;
2109 impl<'a> Resolver<'a> {
2110 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
2111 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
2112 visit::walk_crate(&mut late_resolution_visitor, krate);
2113 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
2114 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");