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, Finalize, LexicalScopeBinding};
11 use crate::{Module, ModuleOrUniformRoot, ParentScope, PathResult};
12 use crate::{ResolutionError, Resolver, Segment, UseError};
14 use rustc_ast::ptr::P;
15 use rustc_ast::visit::{self, AssocCtxt, FnCtxt, FnKind, Visitor};
17 use rustc_ast_lowering::ResolverAstLowering;
18 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
19 use rustc_errors::DiagnosticId;
20 use rustc_hir::def::Namespace::{self, *};
21 use rustc_hir::def::{self, CtorKind, DefKind, PartialRes, PerNS};
22 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
23 use rustc_hir::{PrimTy, TraitCandidate};
24 use rustc_middle::{bug, span_bug};
25 use rustc_session::lint;
26 use rustc_span::symbol::{kw, sym, Ident, Symbol};
28 use smallvec::{smallvec, SmallVec};
30 use rustc_span::source_map::{respan, Spanned};
31 use std::collections::{hash_map::Entry, BTreeSet};
32 use std::mem::{replace, take};
38 type Res = def::Res<NodeId>;
40 type IdentMap<T> = FxHashMap<Ident, T>;
42 /// Map from the name in a pattern to its binding mode.
43 type BindingMap = IdentMap<BindingInfo>;
45 #[derive(Copy, Clone, Debug)]
48 binding_mode: BindingMode,
51 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
59 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
66 fn descr(self) -> &'static str {
68 PatternSource::Match => "match binding",
69 PatternSource::Let => "let binding",
70 PatternSource::For => "for binding",
71 PatternSource::FnParam => "function parameter",
76 /// Denotes whether the context for the set of already bound bindings is a `Product`
77 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
78 /// See those functions for more information.
81 /// A product pattern context, e.g., `Variant(a, b)`.
83 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
87 /// Does this the item (from the item rib scope) allow generic parameters?
88 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
89 crate enum HasGenericParams {
94 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
95 crate enum ConstantItemKind {
100 /// The rib kind restricts certain accesses,
101 /// e.g. to a `Res::Local` of an outer item.
102 #[derive(Copy, Clone, Debug)]
103 crate enum RibKind<'a> {
104 /// No restriction needs to be applied.
107 /// We passed through an impl or trait and are now in one of its
108 /// methods or associated types. Allow references to ty params that impl or trait
109 /// binds. Disallow any other upvars (including other ty params that are
113 /// We passed through a closure. Disallow labels.
114 ClosureOrAsyncRibKind,
116 /// We passed through a function definition. Disallow upvars.
117 /// Permit only those const parameters that are specified in the function's generics.
120 /// We passed through an item scope. Disallow upvars.
121 ItemRibKind(HasGenericParams),
123 /// We're in a constant item. Can't refer to dynamic stuff.
125 /// The `bool` indicates if this constant may reference generic parameters
126 /// and is used to only allow generic parameters to be used in trivial constant expressions.
127 ConstantItemRibKind(bool, Option<(Ident, ConstantItemKind)>),
129 /// We passed through a module.
130 ModuleRibKind(Module<'a>),
132 /// We passed through a `macro_rules!` statement
133 MacroDefinition(DefId),
135 /// All bindings in this rib are generic parameters that can't be used
136 /// from the default of a generic parameter because they're not declared
137 /// before said generic parameter. Also see the `visit_generics` override.
138 ForwardGenericParamBanRibKind,
140 /// We are inside of the type of a const parameter. Can't refer to any
146 /// Whether this rib kind contains generic parameters, as opposed to local
148 crate fn contains_params(&self) -> bool {
151 | ClosureOrAsyncRibKind
153 | ConstantItemRibKind(..)
156 | ConstParamTyRibKind => false,
157 AssocItemRibKind | ItemRibKind(_) | ForwardGenericParamBanRibKind => true,
162 /// A single local scope.
164 /// A rib represents a scope names can live in. Note that these appear in many places, not just
165 /// around braces. At any place where the list of accessible names (of the given namespace)
166 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
167 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
170 /// Different [rib kinds](enum.RibKind) are transparent for different names.
172 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
173 /// resolving, the name is looked up from inside out.
175 crate struct Rib<'a, R = Res> {
176 pub bindings: IdentMap<R>,
177 pub kind: RibKind<'a>,
180 impl<'a, R> Rib<'a, R> {
181 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
182 Rib { bindings: Default::default(), kind }
186 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
187 crate enum AliasPossibility {
192 #[derive(Copy, Clone, Debug)]
193 crate enum PathSource<'a> {
194 // Type paths `Path`.
196 // Trait paths in bounds or impls.
197 Trait(AliasPossibility),
198 // Expression paths `path`, with optional parent context.
199 Expr(Option<&'a Expr>),
200 // Paths in path patterns `Path`.
202 // Paths in struct expressions and patterns `Path { .. }`.
204 // Paths in tuple struct patterns `Path(..)`.
205 TupleStruct(Span, &'a [Span]),
206 // `m::A::B` in `<T as m::A>::B::C`.
207 TraitItem(Namespace),
210 impl<'a> PathSource<'a> {
211 fn namespace(self) -> Namespace {
213 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
214 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
215 PathSource::TraitItem(ns) => ns,
219 fn defer_to_typeck(self) -> bool {
222 | PathSource::Expr(..)
225 | PathSource::TupleStruct(..) => true,
226 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
230 fn descr_expected(self) -> &'static str {
232 PathSource::Type => "type",
233 PathSource::Trait(_) => "trait",
234 PathSource::Pat => "unit struct, unit variant or constant",
235 PathSource::Struct => "struct, variant or union type",
236 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
237 PathSource::TraitItem(ns) => match ns {
238 TypeNS => "associated type",
239 ValueNS => "method or associated constant",
240 MacroNS => bug!("associated macro"),
242 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
243 // "function" here means "anything callable" rather than `DefKind::Fn`,
244 // this is not precise but usually more helpful than just "value".
245 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
246 // the case of `::some_crate()`
247 ExprKind::Path(_, path)
248 if path.segments.len() == 2
249 && path.segments[0].ident.name == kw::PathRoot =>
253 ExprKind::Path(_, path) => {
254 let mut msg = "function";
255 if let Some(segment) = path.segments.iter().last() {
256 if let Some(c) = segment.ident.to_string().chars().next() {
257 if c.is_uppercase() {
258 msg = "function, tuple struct or tuple variant";
271 fn is_call(self) -> bool {
272 matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
275 crate fn is_expected(self, res: Res) -> bool {
277 PathSource::Type => matches!(
284 | DefKind::TraitAlias
289 | DefKind::ForeignTy,
294 PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
295 PathSource::Trait(AliasPossibility::Maybe) => {
296 matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
298 PathSource::Expr(..) => matches!(
301 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
306 | DefKind::AssocConst
307 | DefKind::ConstParam,
312 PathSource::Pat => matches!(
315 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::AssocConst,
317 ) | Res::SelfCtor(..)
319 PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
320 PathSource::Struct => matches!(
329 ) | Res::SelfTy { .. }
331 PathSource::TraitItem(ns) => match res {
332 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
333 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
339 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
340 use rustc_errors::error_code;
341 match (self, has_unexpected_resolution) {
342 (PathSource::Trait(_), true) => error_code!(E0404),
343 (PathSource::Trait(_), false) => error_code!(E0405),
344 (PathSource::Type, true) => error_code!(E0573),
345 (PathSource::Type, false) => error_code!(E0412),
346 (PathSource::Struct, true) => error_code!(E0574),
347 (PathSource::Struct, false) => error_code!(E0422),
348 (PathSource::Expr(..), true) => error_code!(E0423),
349 (PathSource::Expr(..), false) => error_code!(E0425),
350 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
351 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
352 (PathSource::TraitItem(..), true) => error_code!(E0575),
353 (PathSource::TraitItem(..), false) => error_code!(E0576),
359 struct DiagnosticMetadata<'ast> {
360 /// The current trait's associated items' ident, used for diagnostic suggestions.
361 current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
363 /// The current self type if inside an impl (used for better errors).
364 current_self_type: Option<Ty>,
366 /// The current self item if inside an ADT (used for better errors).
367 current_self_item: Option<NodeId>,
369 /// The current trait (used to suggest).
370 current_item: Option<&'ast Item>,
372 /// When processing generics and encountering a type not found, suggest introducing a type
374 currently_processing_generics: bool,
376 /// The current enclosing (non-closure) function (used for better errors).
377 current_function: Option<(FnKind<'ast>, Span)>,
379 /// A list of labels as of yet unused. Labels will be removed from this map when
380 /// they are used (in a `break` or `continue` statement)
381 unused_labels: FxHashMap<NodeId, Span>,
383 /// Only used for better errors on `fn(): fn()`.
384 current_type_ascription: Vec<Span>,
386 /// Only used for better errors on `let x = { foo: bar };`.
387 /// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only
388 /// needed for cases where this parses as a correct type ascription.
389 current_block_could_be_bare_struct_literal: Option<Span>,
391 /// Only used for better errors on `let <pat>: <expr, not type>;`.
392 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
394 /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
395 in_if_condition: Option<&'ast Expr>,
397 /// If we are currently in a trait object definition. Used to point at the bounds when
398 /// encountering a struct or enum.
399 current_trait_object: Option<&'ast [ast::GenericBound]>,
401 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
402 current_where_predicate: Option<&'ast WherePredicate>,
404 current_type_path: Option<&'ast Ty>,
407 struct LateResolutionVisitor<'a, 'b, 'ast> {
408 r: &'b mut Resolver<'a>,
410 /// The module that represents the current item scope.
411 parent_scope: ParentScope<'a>,
413 /// The current set of local scopes for types and values.
414 /// FIXME #4948: Reuse ribs to avoid allocation.
415 ribs: PerNS<Vec<Rib<'a>>>,
417 /// The current set of local scopes, for labels.
418 label_ribs: Vec<Rib<'a, NodeId>>,
420 /// The trait that the current context can refer to.
421 current_trait_ref: Option<(Module<'a>, TraitRef)>,
423 /// Fields used to add information to diagnostic errors.
424 diagnostic_metadata: DiagnosticMetadata<'ast>,
426 /// State used to know whether to ignore resolution errors for function bodies.
428 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
429 /// In most cases this will be `None`, in which case errors will always be reported.
430 /// If it is `true`, then it will be updated when entering a nested function or trait body.
434 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
435 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
436 fn visit_attribute(&mut self, _: &'ast Attribute) {
437 // We do not want to resolve expressions that appear in attributes,
438 // as they do not correspond to actual code.
440 fn visit_item(&mut self, item: &'ast Item) {
441 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
442 // Always report errors in items we just entered.
443 let old_ignore = replace(&mut self.in_func_body, false);
444 self.resolve_item(item);
445 self.in_func_body = old_ignore;
446 self.diagnostic_metadata.current_item = prev;
448 fn visit_arm(&mut self, arm: &'ast Arm) {
449 self.resolve_arm(arm);
451 fn visit_block(&mut self, block: &'ast Block) {
452 self.resolve_block(block);
454 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
455 // We deal with repeat expressions explicitly in `resolve_expr`.
456 self.resolve_anon_const(constant, IsRepeatExpr::No);
458 fn visit_expr(&mut self, expr: &'ast Expr) {
459 self.resolve_expr(expr, None);
461 fn visit_local(&mut self, local: &'ast Local) {
462 let local_spans = match local.pat.kind {
463 // We check for this to avoid tuple struct fields.
464 PatKind::Wild => None,
467 local.ty.as_ref().map(|ty| ty.span),
468 local.kind.init().map(|init| init.span),
471 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
472 self.resolve_local(local);
473 self.diagnostic_metadata.current_let_binding = original;
475 fn visit_ty(&mut self, ty: &'ast Ty) {
476 let prev = self.diagnostic_metadata.current_trait_object;
477 let prev_ty = self.diagnostic_metadata.current_type_path;
479 TyKind::Path(ref qself, ref path) => {
480 self.diagnostic_metadata.current_type_path = Some(ty);
481 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
483 TyKind::ImplicitSelf => {
484 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
486 .resolve_ident_in_lexical_scope(
489 Finalize::SimplePath(ty.id, ty.span),
491 .map_or(Res::Err, |d| d.res());
492 self.r.record_partial_res(ty.id, PartialRes::new(res));
494 TyKind::TraitObject(ref bounds, ..) => {
495 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
499 visit::walk_ty(self, ty);
500 self.diagnostic_metadata.current_trait_object = prev;
501 self.diagnostic_metadata.current_type_path = prev_ty;
503 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef, m: &'ast TraitBoundModifier) {
504 self.smart_resolve_path(
505 tref.trait_ref.ref_id,
507 &tref.trait_ref.path,
508 PathSource::Trait(AliasPossibility::Maybe),
510 visit::walk_poly_trait_ref(self, tref, m);
512 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
513 match foreign_item.kind {
514 ForeignItemKind::Fn(box Fn { ref generics, .. })
515 | ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
516 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
517 visit::walk_foreign_item(this, foreign_item);
520 ForeignItemKind::Static(..) => {
521 self.with_item_rib(HasGenericParams::No, |this| {
522 visit::walk_foreign_item(this, foreign_item);
525 ForeignItemKind::MacCall(..) => {
526 visit::walk_foreign_item(self, foreign_item);
530 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, _: NodeId) {
531 let rib_kind = match fn_kind {
532 // Bail if the function is foreign, and thus cannot validly have
533 // a body, or if there's no body for some other reason.
534 FnKind::Fn(FnCtxt::Foreign, _, sig, ..) | FnKind::Fn(_, _, sig, .., None) => {
535 // We don't need to deal with patterns in parameters, because
536 // they are not possible for foreign or bodiless functions.
537 self.visit_fn_header(&sig.header);
538 visit::walk_fn_decl(self, &sig.decl);
541 FnKind::Fn(FnCtxt::Free, ..) => FnItemRibKind,
542 FnKind::Fn(FnCtxt::Assoc(_), ..) => NormalRibKind,
543 FnKind::Closure(..) => ClosureOrAsyncRibKind,
545 let previous_value = self.diagnostic_metadata.current_function;
546 if matches!(fn_kind, FnKind::Fn(..)) {
547 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
549 debug!("(resolving function) entering function");
550 let declaration = fn_kind.decl();
552 // Create a value rib for the function.
553 self.with_rib(ValueNS, rib_kind, |this| {
554 // Create a label rib for the function.
555 this.with_label_rib(rib_kind, |this| {
556 // Add each argument to the rib.
557 this.resolve_params(&declaration.inputs);
559 visit::walk_fn_ret_ty(this, &declaration.output);
561 // Ignore errors in function bodies if this is rustdoc
562 // Be sure not to set this until the function signature has been resolved.
563 let previous_state = replace(&mut this.in_func_body, true);
564 // Resolve the function body, potentially inside the body of an async closure
566 FnKind::Fn(.., body) => walk_list!(this, visit_block, body),
567 FnKind::Closure(_, body) => this.visit_expr(body),
570 debug!("(resolving function) leaving function");
571 this.in_func_body = previous_state;
574 self.diagnostic_metadata.current_function = previous_value;
577 fn visit_generics(&mut self, generics: &'ast Generics) {
578 // For type parameter defaults, we have to ban access
579 // to following type parameters, as the InternalSubsts can only
580 // provide previous type parameters as they're built. We
581 // put all the parameters on the ban list and then remove
582 // them one by one as they are processed and become available.
583 let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
584 let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
585 for param in generics.params.iter() {
587 GenericParamKind::Type { .. } => {
590 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
592 GenericParamKind::Const { .. } => {
593 forward_const_ban_rib
595 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
597 GenericParamKind::Lifetime => {}
601 // rust-lang/rust#61631: The type `Self` is essentially
602 // another type parameter. For ADTs, we consider it
603 // well-defined only after all of the ADT type parameters have
604 // been provided. Therefore, we do not allow use of `Self`
605 // anywhere in ADT type parameter defaults.
607 // (We however cannot ban `Self` for defaults on *all* generic
608 // lists; e.g. trait generics can usefully refer to `Self`,
609 // such as in the case of `trait Add<Rhs = Self>`.)
610 if self.diagnostic_metadata.current_self_item.is_some() {
611 // (`Some` if + only if we are in ADT's generics.)
612 forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
615 for param in &generics.params {
617 GenericParamKind::Lifetime => self.visit_generic_param(param),
618 GenericParamKind::Type { ref default } => {
619 for bound in ¶m.bounds {
620 self.visit_param_bound(bound);
623 if let Some(ref ty) = default {
624 self.ribs[TypeNS].push(forward_ty_ban_rib);
625 self.ribs[ValueNS].push(forward_const_ban_rib);
627 forward_const_ban_rib = self.ribs[ValueNS].pop().unwrap();
628 forward_ty_ban_rib = self.ribs[TypeNS].pop().unwrap();
631 // Allow all following defaults to refer to this type parameter.
632 forward_ty_ban_rib.bindings.remove(&Ident::with_dummy_span(param.ident.name));
634 GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
635 // Const parameters can't have param bounds.
636 assert!(param.bounds.is_empty());
638 self.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
639 self.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
641 self.ribs[TypeNS].pop().unwrap();
642 self.ribs[ValueNS].pop().unwrap();
644 if let Some(ref expr) = default {
645 self.ribs[TypeNS].push(forward_ty_ban_rib);
646 self.ribs[ValueNS].push(forward_const_ban_rib);
647 self.visit_anon_const(expr);
648 forward_const_ban_rib = self.ribs[ValueNS].pop().unwrap();
649 forward_ty_ban_rib = self.ribs[TypeNS].pop().unwrap();
652 // Allow all following defaults to refer to this const parameter.
653 forward_const_ban_rib
655 .remove(&Ident::with_dummy_span(param.ident.name));
659 for p in &generics.where_clause.predicates {
660 self.visit_where_predicate(p);
664 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
665 debug!("visit_generic_arg({:?})", arg);
666 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
668 GenericArg::Type(ref ty) => {
669 // We parse const arguments as path types as we cannot distinguish them during
670 // parsing. We try to resolve that ambiguity by attempting resolution the type
671 // namespace first, and if that fails we try again in the value namespace. If
672 // resolution in the value namespace succeeds, we have an generic const argument on
674 if let TyKind::Path(ref qself, ref path) = ty.kind {
675 // We cannot disambiguate multi-segment paths right now as that requires type
677 if path.segments.len() == 1 && path.segments[0].args.is_none() {
678 let mut check_ns = |ns| {
679 self.resolve_ident_in_lexical_scope(
680 path.segments[0].ident,
686 if !check_ns(TypeNS) && check_ns(ValueNS) {
687 // This must be equivalent to `visit_anon_const`, but we cannot call it
688 // directly due to visitor lifetimes so we have to copy-paste some code.
690 // Note that we might not be inside of an repeat expression here,
691 // but considering that `IsRepeatExpr` is only relevant for
692 // non-trivial constants this is doesn't matter.
693 self.with_constant_rib(IsRepeatExpr::No, true, None, |this| {
694 this.smart_resolve_path(
698 PathSource::Expr(None),
701 if let Some(ref qself) = *qself {
702 this.visit_ty(&qself.ty);
704 this.visit_path(path, ty.id);
707 self.diagnostic_metadata.currently_processing_generics = prev;
715 GenericArg::Lifetime(lt) => self.visit_lifetime(lt),
716 GenericArg::Const(ct) => self.visit_anon_const(ct),
718 self.diagnostic_metadata.currently_processing_generics = prev;
721 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
722 debug!("visit_where_predicate {:?}", p);
724 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
725 visit::walk_where_predicate(self, p);
726 self.diagnostic_metadata.current_where_predicate = previous_value;
730 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
731 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
732 // During late resolution we only track the module component of the parent scope,
733 // although it may be useful to track other components as well for diagnostics.
734 let graph_root = resolver.graph_root;
735 let parent_scope = ParentScope::module(graph_root, resolver);
736 let start_rib_kind = ModuleRibKind(graph_root);
737 LateResolutionVisitor {
741 value_ns: vec![Rib::new(start_rib_kind)],
742 type_ns: vec![Rib::new(start_rib_kind)],
743 macro_ns: vec![Rib::new(start_rib_kind)],
745 label_ribs: Vec::new(),
746 current_trait_ref: None,
747 diagnostic_metadata: DiagnosticMetadata::default(),
748 // errors at module scope should always be reported
753 fn resolve_ident_in_lexical_scope(
758 ) -> Option<LexicalScopeBinding<'a>> {
759 self.r.resolve_ident_in_lexical_scope(
771 opt_ns: Option<Namespace>, // `None` indicates a module path in import
773 ) -> PathResult<'a> {
774 self.r.resolve_path_with_ribs(path, opt_ns, &self.parent_scope, finalize, Some(&self.ribs))
779 // We maintain a list of value ribs and type ribs.
781 // Simultaneously, we keep track of the current position in the module
782 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
783 // the value or type namespaces, we first look through all the ribs and
784 // then query the module graph. When we resolve a name in the module
785 // namespace, we can skip all the ribs (since nested modules are not
786 // allowed within blocks in Rust) and jump straight to the current module
789 // Named implementations are handled separately. When we find a method
790 // call, we consult the module node to find all of the implementations in
791 // scope. This information is lazily cached in the module node. We then
792 // generate a fake "implementation scope" containing all the
793 // implementations thus found, for compatibility with old resolve pass.
795 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
800 work: impl FnOnce(&mut Self) -> T,
802 self.ribs[ns].push(Rib::new(kind));
803 let ret = work(self);
808 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
809 if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
810 // Move down in the graph.
811 let orig_module = replace(&mut self.parent_scope.module, module);
812 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
813 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
815 this.parent_scope.module = orig_module;
824 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
825 /// label and reports an error if the label is not found or is unreachable.
826 fn resolve_label(&self, mut label: Ident) -> Option<NodeId> {
827 let mut suggestion = None;
829 // Preserve the original span so that errors contain "in this macro invocation"
831 let original_span = label.span;
833 for i in (0..self.label_ribs.len()).rev() {
834 let rib = &self.label_ribs[i];
836 if let MacroDefinition(def) = rib.kind {
837 // If an invocation of this macro created `ident`, give up on `ident`
838 // and switch to `ident`'s source from the macro definition.
839 if def == self.r.macro_def(label.span.ctxt()) {
840 label.span.remove_mark();
844 let ident = label.normalize_to_macro_rules();
845 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
846 return if self.is_label_valid_from_rib(i) {
851 ResolutionError::UnreachableLabel {
853 definition_span: ident.span,
862 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
863 // the first such label that is encountered.
864 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
869 ResolutionError::UndeclaredLabel { name: label.name, suggestion },
874 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
875 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
876 let ribs = &self.label_ribs[rib_index + 1..];
880 NormalRibKind | MacroDefinition(..) => {
881 // Nothing to do. Continue.
885 | ClosureOrAsyncRibKind
888 | ConstantItemRibKind(..)
890 | ForwardGenericParamBanRibKind
891 | ConstParamTyRibKind => {
900 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
901 debug!("resolve_adt");
902 self.with_current_self_item(item, |this| {
903 this.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
904 let item_def_id = this.r.local_def_id(item.id).to_def_id();
906 Res::SelfTy { trait_: None, alias_to: Some((item_def_id, false)) },
908 visit::walk_item(this, item);
915 fn future_proof_import(&mut self, use_tree: &UseTree) {
916 let segments = &use_tree.prefix.segments;
917 if !segments.is_empty() {
918 let ident = segments[0].ident;
919 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
923 let nss = match use_tree.kind {
924 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
927 let report_error = |this: &Self, ns| {
928 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
929 if this.should_report_errs() {
932 .span_err(ident.span, &format!("imports cannot refer to {}", what));
937 match self.resolve_ident_in_lexical_scope(ident, ns, Finalize::No) {
938 Some(LexicalScopeBinding::Res(..)) => {
939 report_error(self, ns);
941 Some(LexicalScopeBinding::Item(binding)) => {
942 let orig_unusable_binding =
943 replace(&mut self.r.unusable_binding, Some(binding));
944 if let Some(LexicalScopeBinding::Res(..)) =
945 self.resolve_ident_in_lexical_scope(ident, ns, Finalize::No)
947 report_error(self, ns);
949 self.r.unusable_binding = orig_unusable_binding;
954 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
955 for (use_tree, _) in use_trees {
956 self.future_proof_import(use_tree);
961 fn resolve_item(&mut self, item: &'ast Item) {
962 let name = item.ident.name;
963 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
966 ItemKind::TyAlias(box TyAlias { ref generics, .. })
967 | ItemKind::Fn(box Fn { ref generics, .. }) => {
968 self.compute_num_lifetime_params(item.id, generics);
969 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
970 visit::walk_item(this, item)
974 ItemKind::Enum(_, ref generics)
975 | ItemKind::Struct(_, ref generics)
976 | ItemKind::Union(_, ref generics) => {
977 self.compute_num_lifetime_params(item.id, generics);
978 self.resolve_adt(item, generics);
981 ItemKind::Impl(box Impl {
985 items: ref impl_items,
988 self.compute_num_lifetime_params(item.id, generics);
989 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
992 ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
993 self.compute_num_lifetime_params(item.id, generics);
994 // Create a new rib for the trait-wide type parameters.
995 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
996 let def = this.r.local_def_id(item.id).to_def_id();
997 this.with_self_rib(Res::SelfTy { trait_: Some(def), alias_to: None }, |this| {
998 this.visit_generics(generics);
999 walk_list!(this, visit_param_bound, bounds);
1001 let walk_assoc_item = |this: &mut Self, generics, item| {
1002 this.with_generic_param_rib(generics, AssocItemRibKind, |this| {
1003 visit::walk_assoc_item(this, item, AssocCtxt::Trait)
1007 this.with_trait_items(items, |this| {
1010 AssocItemKind::Const(_, ty, default) => {
1012 // Only impose the restrictions of `ConstRibKind` for an
1013 // actual constant expression in a provided default.
1014 if let Some(expr) = default {
1015 // We allow arbitrary const expressions inside of associated consts,
1016 // even if they are potentially not const evaluatable.
1018 // Type parameters can already be used and as associated consts are
1019 // not used as part of the type system, this is far less surprising.
1020 this.with_constant_rib(
1024 |this| this.visit_expr(expr),
1028 AssocItemKind::Fn(box Fn { generics, .. }) => {
1029 walk_assoc_item(this, generics, item);
1031 AssocItemKind::TyAlias(box TyAlias { generics, .. }) => {
1032 walk_assoc_item(this, generics, item);
1034 AssocItemKind::MacCall(_) => {
1035 panic!("unexpanded macro in resolve!")
1044 ItemKind::TraitAlias(ref generics, ref bounds) => {
1045 self.compute_num_lifetime_params(item.id, generics);
1046 // Create a new rib for the trait-wide type parameters.
1047 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1048 let def = this.r.local_def_id(item.id).to_def_id();
1049 this.with_self_rib(Res::SelfTy { trait_: Some(def), alias_to: None }, |this| {
1050 this.visit_generics(generics);
1051 walk_list!(this, visit_param_bound, bounds);
1056 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
1057 self.with_scope(item.id, |this| {
1058 visit::walk_item(this, item);
1062 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
1063 self.with_item_rib(HasGenericParams::No, |this| {
1065 if let Some(expr) = expr {
1066 let constant_item_kind = match item.kind {
1067 ItemKind::Const(..) => ConstantItemKind::Const,
1068 ItemKind::Static(..) => ConstantItemKind::Static,
1069 _ => unreachable!(),
1071 // We already forbid generic params because of the above item rib,
1072 // so it doesn't matter whether this is a trivial constant.
1073 this.with_constant_rib(
1076 Some((item.ident, constant_item_kind)),
1077 |this| this.visit_expr(expr),
1083 ItemKind::Use(ref use_tree) => {
1084 self.future_proof_import(use_tree);
1087 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => {
1088 // do nothing, these are just around to be encoded
1091 ItemKind::GlobalAsm(_) => {
1092 visit::walk_item(self, item);
1095 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
1099 fn with_generic_param_rib<'c, F>(&'c mut self, generics: &'c Generics, kind: RibKind<'a>, f: F)
1101 F: FnOnce(&mut Self),
1103 debug!("with_generic_param_rib");
1104 let mut function_type_rib = Rib::new(kind);
1105 let mut function_value_rib = Rib::new(kind);
1106 let mut seen_bindings = FxHashMap::default();
1108 // We also can't shadow bindings from the parent item
1109 if let AssocItemRibKind = kind {
1110 let mut add_bindings_for_ns = |ns| {
1111 let parent_rib = self.ribs[ns]
1113 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
1114 .expect("associated item outside of an item");
1116 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
1118 add_bindings_for_ns(ValueNS);
1119 add_bindings_for_ns(TypeNS);
1122 for param in &generics.params {
1123 if let GenericParamKind::Lifetime = param.kind {
1127 let ident = param.ident.normalize_to_macros_2_0();
1128 debug!("with_generic_param_rib: {}", param.id);
1130 match seen_bindings.entry(ident) {
1131 Entry::Occupied(entry) => {
1132 let span = *entry.get();
1133 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
1134 self.report_error(param.ident.span, err);
1136 Entry::Vacant(entry) => {
1137 entry.insert(param.ident.span);
1141 // Plain insert (no renaming).
1142 let (rib, def_kind) = match param.kind {
1143 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
1144 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
1145 _ => unreachable!(),
1147 let res = Res::Def(def_kind, self.r.local_def_id(param.id).to_def_id());
1148 self.r.record_partial_res(param.id, PartialRes::new(res));
1149 rib.bindings.insert(ident, res);
1152 self.ribs[ValueNS].push(function_value_rib);
1153 self.ribs[TypeNS].push(function_type_rib);
1157 self.ribs[TypeNS].pop();
1158 self.ribs[ValueNS].pop();
1161 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
1162 self.label_ribs.push(Rib::new(kind));
1164 self.label_ribs.pop();
1167 fn with_item_rib(&mut self, has_generic_params: HasGenericParams, f: impl FnOnce(&mut Self)) {
1168 let kind = ItemRibKind(has_generic_params);
1169 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
1172 // HACK(min_const_generics,const_evaluatable_unchecked): We
1173 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
1174 // with a future compat lint for now. We do this by adding an
1175 // additional special case for repeat expressions.
1177 // Note that we intentionally still forbid `[0; N + 1]` during
1178 // name resolution so that we don't extend the future
1179 // compat lint to new cases.
1180 fn with_constant_rib(
1182 is_repeat: IsRepeatExpr,
1184 item: Option<(Ident, ConstantItemKind)>,
1185 f: impl FnOnce(&mut Self),
1187 debug!("with_constant_rib: is_repeat={:?} is_trivial={}", is_repeat, is_trivial);
1188 self.with_rib(ValueNS, ConstantItemRibKind(is_trivial, item), |this| {
1191 ConstantItemRibKind(is_repeat == IsRepeatExpr::Yes || is_trivial, item),
1193 this.with_label_rib(ConstantItemRibKind(is_trivial, item), f);
1199 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
1200 // Handle nested impls (inside fn bodies)
1201 let previous_value =
1202 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
1203 let result = f(self);
1204 self.diagnostic_metadata.current_self_type = previous_value;
1208 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
1209 let previous_value =
1210 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
1211 let result = f(self);
1212 self.diagnostic_metadata.current_self_item = previous_value;
1216 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
1217 fn with_trait_items<T>(
1219 trait_items: &'ast [P<AssocItem>],
1220 f: impl FnOnce(&mut Self) -> T,
1222 let trait_assoc_items =
1223 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
1224 let result = f(self);
1225 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
1229 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
1230 fn with_optional_trait_ref<T>(
1232 opt_trait_ref: Option<&TraitRef>,
1233 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
1235 let mut new_val = None;
1236 let mut new_id = None;
1237 if let Some(trait_ref) = opt_trait_ref {
1238 let path: Vec<_> = Segment::from_path(&trait_ref.path);
1239 let res = self.smart_resolve_path_fragment(
1242 PathSource::Trait(AliasPossibility::No),
1243 Finalize::SimplePath(trait_ref.ref_id, trait_ref.path.span),
1245 if let Some(def_id) = res.base_res().opt_def_id() {
1246 new_id = Some(def_id);
1247 new_val = Some((self.r.expect_module(def_id), trait_ref.clone()));
1250 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1251 let result = f(self, new_id);
1252 self.current_trait_ref = original_trait_ref;
1256 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
1257 let mut self_type_rib = Rib::new(NormalRibKind);
1259 // Plain insert (no renaming, since types are not currently hygienic)
1260 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
1261 self.ribs[ns].push(self_type_rib);
1263 self.ribs[ns].pop();
1266 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
1267 self.with_self_rib_ns(TypeNS, self_res, f)
1270 fn resolve_implementation(
1272 generics: &'ast Generics,
1273 opt_trait_reference: &'ast Option<TraitRef>,
1274 self_type: &'ast Ty,
1276 impl_items: &'ast [P<AssocItem>],
1278 debug!("resolve_implementation");
1279 // If applicable, create a rib for the type parameters.
1280 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1281 // Dummy self type for better errors if `Self` is used in the trait path.
1282 this.with_self_rib(Res::SelfTy { trait_: None, alias_to: None }, |this| {
1283 // Resolve the trait reference, if necessary.
1284 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1285 let item_def_id = this.r.local_def_id(item_id);
1287 // Register the trait definitions from here.
1288 if let Some(trait_id) = trait_id {
1289 this.r.trait_impls.entry(trait_id).or_default().push(item_def_id);
1292 let item_def_id = item_def_id.to_def_id();
1294 Res::SelfTy { trait_: trait_id, alias_to: Some((item_def_id, false)) };
1295 this.with_self_rib(res, |this| {
1296 if let Some(trait_ref) = opt_trait_reference.as_ref() {
1297 // Resolve type arguments in the trait path.
1298 visit::walk_trait_ref(this, trait_ref);
1300 // Resolve the self type.
1301 this.visit_ty(self_type);
1302 // Resolve the generic parameters.
1303 this.visit_generics(generics);
1304 // Resolve the items within the impl.
1305 this.with_current_self_type(self_type, |this| {
1306 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
1307 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
1308 for item in impl_items {
1309 use crate::ResolutionError::*;
1311 AssocItemKind::Const(_default, _ty, _expr) => {
1312 debug!("resolve_implementation AssocItemKind::Const");
1313 // If this is a trait impl, ensure the const
1315 this.check_trait_item(
1321 |i, s, c| ConstNotMemberOfTrait(i, s, c),
1324 // We allow arbitrary const expressions inside of associated consts,
1325 // even if they are potentially not const evaluatable.
1327 // Type parameters can already be used and as associated consts are
1328 // not used as part of the type system, this is far less surprising.
1329 this.with_constant_rib(
1334 visit::walk_assoc_item(
1342 AssocItemKind::Fn(box Fn { generics, .. }) => {
1343 debug!("resolve_implementation AssocItemKind::Fn");
1344 // We also need a new scope for the impl item type parameters.
1345 this.with_generic_param_rib(
1349 // If this is a trait impl, ensure the method
1351 this.check_trait_item(
1357 |i, s, c| MethodNotMemberOfTrait(i, s, c),
1360 visit::walk_assoc_item(
1368 AssocItemKind::TyAlias(box TyAlias {
1371 debug!("resolve_implementation AssocItemKind::TyAlias");
1372 // We also need a new scope for the impl item type parameters.
1373 this.with_generic_param_rib(
1377 // If this is a trait impl, ensure the type
1379 this.check_trait_item(
1385 |i, s, c| TypeNotMemberOfTrait(i, s, c),
1388 visit::walk_assoc_item(
1396 AssocItemKind::MacCall(_) => {
1397 panic!("unexpanded macro in resolve!")
1409 fn check_trait_item<F>(
1413 kind: &AssocItemKind,
1418 F: FnOnce(Ident, &str, Option<Symbol>) -> ResolutionError<'_>,
1420 // If there is a TraitRef in scope for an impl, then the method must be in the trait.
1421 let Some((module, _)) = &self.current_trait_ref else { return; };
1422 ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
1423 let key = self.r.new_key(ident, ns);
1424 let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
1426 if binding.is_none() {
1427 // We could not find the trait item in the correct namespace.
1428 // Check the other namespace to report an error.
1434 let key = self.r.new_key(ident, ns);
1435 binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
1438 let Some(binding) = binding else {
1439 // We could not find the method: report an error.
1440 let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
1441 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
1442 self.report_error(span, err(ident, &path_names_to_string(path), candidate));
1446 let res = binding.res();
1447 let Res::Def(def_kind, _) = res else { bug!() };
1448 match (def_kind, kind) {
1449 (DefKind::AssocTy, AssocItemKind::TyAlias(..))
1450 | (DefKind::AssocFn, AssocItemKind::Fn(..))
1451 | (DefKind::AssocConst, AssocItemKind::Const(..)) => {
1452 self.r.record_partial_res(id, PartialRes::new(res));
1458 // The method kind does not correspond to what appeared in the trait, report.
1459 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
1460 let (code, kind) = match kind {
1461 AssocItemKind::Const(..) => (rustc_errors::error_code!(E0323), "const"),
1462 AssocItemKind::Fn(..) => (rustc_errors::error_code!(E0324), "method"),
1463 AssocItemKind::TyAlias(..) => (rustc_errors::error_code!(E0325), "type"),
1464 AssocItemKind::MacCall(..) => span_bug!(span, "unexpanded macro"),
1468 ResolutionError::TraitImplMismatch {
1472 trait_path: path_names_to_string(path),
1473 trait_item_span: binding.span,
1478 fn resolve_params(&mut self, params: &'ast [Param]) {
1479 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1480 for Param { pat, ty, .. } in params {
1481 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1483 debug!("(resolving function / closure) recorded parameter");
1487 fn resolve_local(&mut self, local: &'ast Local) {
1488 debug!("resolving local ({:?})", local);
1489 // Resolve the type.
1490 walk_list!(self, visit_ty, &local.ty);
1492 // Resolve the initializer.
1493 if let Some((init, els)) = local.kind.init_else_opt() {
1494 self.visit_expr(init);
1496 // Resolve the `else` block
1497 if let Some(els) = els {
1498 self.visit_block(els);
1502 // Resolve the pattern.
1503 self.resolve_pattern_top(&local.pat, PatternSource::Let);
1506 /// build a map from pattern identifiers to binding-info's.
1507 /// this is done hygienically. This could arise for a macro
1508 /// that expands into an or-pattern where one 'x' was from the
1509 /// user and one 'x' came from the macro.
1510 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1511 let mut binding_map = FxHashMap::default();
1513 pat.walk(&mut |pat| {
1515 PatKind::Ident(binding_mode, ident, ref sub_pat)
1516 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
1518 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
1520 PatKind::Or(ref ps) => {
1521 // Check the consistency of this or-pattern and
1522 // then add all bindings to the larger map.
1523 for bm in self.check_consistent_bindings(ps) {
1524 binding_map.extend(bm);
1537 fn is_base_res_local(&self, nid: NodeId) -> bool {
1538 matches!(self.r.partial_res_map.get(&nid).map(|res| res.base_res()), Some(Res::Local(..)))
1541 /// Checks that all of the arms in an or-pattern have exactly the
1542 /// same set of bindings, with the same binding modes for each.
1543 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
1544 let mut missing_vars = FxHashMap::default();
1545 let mut inconsistent_vars = FxHashMap::default();
1547 // 1) Compute the binding maps of all arms.
1548 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
1550 // 2) Record any missing bindings or binding mode inconsistencies.
1551 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
1552 // Check against all arms except for the same pattern which is always self-consistent.
1556 .filter(|(_, pat)| pat.id != pat_outer.id)
1557 .flat_map(|(idx, _)| maps[idx].iter())
1558 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
1560 for (name, info, &binding_inner) in inners {
1563 // The inner binding is missing in the outer.
1565 missing_vars.entry(name).or_insert_with(|| BindingError {
1567 origin: BTreeSet::new(),
1568 target: BTreeSet::new(),
1569 could_be_path: name.as_str().starts_with(char::is_uppercase),
1571 binding_error.origin.insert(binding_inner.span);
1572 binding_error.target.insert(pat_outer.span);
1574 Some(binding_outer) => {
1575 if binding_outer.binding_mode != binding_inner.binding_mode {
1576 // The binding modes in the outer and inner bindings differ.
1579 .or_insert((binding_inner.span, binding_outer.span));
1586 // 3) Report all missing variables we found.
1587 let mut missing_vars = missing_vars.iter_mut().collect::<Vec<_>>();
1588 missing_vars.sort_by_key(|(sym, _err)| sym.as_str());
1590 for (name, mut v) in missing_vars {
1591 if inconsistent_vars.contains_key(name) {
1592 v.could_be_path = false;
1595 *v.origin.iter().next().unwrap(),
1596 ResolutionError::VariableNotBoundInPattern(v),
1600 // 4) Report all inconsistencies in binding modes we found.
1601 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
1602 inconsistent_vars.sort();
1603 for (name, v) in inconsistent_vars {
1604 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
1607 // 5) Finally bubble up all the binding maps.
1611 /// Check the consistency of the outermost or-patterns.
1612 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
1613 pat.walk(&mut |pat| match pat.kind {
1614 PatKind::Or(ref ps) => {
1615 self.check_consistent_bindings(ps);
1622 fn resolve_arm(&mut self, arm: &'ast Arm) {
1623 self.with_rib(ValueNS, NormalRibKind, |this| {
1624 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
1625 walk_list!(this, visit_expr, &arm.guard);
1626 this.visit_expr(&arm.body);
1630 /// Arising from `source`, resolve a top level pattern.
1631 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
1632 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1633 self.resolve_pattern(pat, pat_src, &mut bindings);
1639 pat_src: PatternSource,
1640 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1642 // We walk the pattern before declaring the pattern's inner bindings,
1643 // so that we avoid resolving a literal expression to a binding defined
1645 visit::walk_pat(self, pat);
1646 self.resolve_pattern_inner(pat, pat_src, bindings);
1647 // This has to happen *after* we determine which pat_idents are variants:
1648 self.check_consistent_bindings_top(pat);
1651 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
1655 /// A stack of sets of bindings accumulated.
1657 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
1658 /// be interpreted as re-binding an already bound binding. This results in an error.
1659 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
1660 /// in reusing this binding rather than creating a fresh one.
1662 /// When called at the top level, the stack must have a single element
1663 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
1664 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
1665 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
1666 /// When each `p_i` has been dealt with, the top set is merged with its parent.
1667 /// When a whole or-pattern has been dealt with, the thing happens.
1669 /// See the implementation and `fresh_binding` for more details.
1670 fn resolve_pattern_inner(
1673 pat_src: PatternSource,
1674 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1676 // Visit all direct subpatterns of this pattern.
1677 pat.walk(&mut |pat| {
1678 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
1680 PatKind::Ident(bmode, ident, ref sub) => {
1681 // First try to resolve the identifier as some existing entity,
1682 // then fall back to a fresh binding.
1683 let has_sub = sub.is_some();
1685 .try_resolve_as_non_binding(pat_src, bmode, ident, has_sub)
1686 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
1687 self.r.record_partial_res(pat.id, PartialRes::new(res));
1688 self.r.record_pat_span(pat.id, pat.span);
1690 PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
1691 self.smart_resolve_path(
1695 PathSource::TupleStruct(
1697 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
1701 PatKind::Path(ref qself, ref path) => {
1702 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
1704 PatKind::Struct(ref qself, ref path, ..) => {
1705 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Struct);
1707 PatKind::Or(ref ps) => {
1708 // Add a new set of bindings to the stack. `Or` here records that when a
1709 // binding already exists in this set, it should not result in an error because
1710 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
1711 bindings.push((PatBoundCtx::Or, Default::default()));
1713 // Now we need to switch back to a product context so that each
1714 // part of the or-pattern internally rejects already bound names.
1715 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
1716 bindings.push((PatBoundCtx::Product, Default::default()));
1717 self.resolve_pattern_inner(p, pat_src, bindings);
1718 // Move up the non-overlapping bindings to the or-pattern.
1719 // Existing bindings just get "merged".
1720 let collected = bindings.pop().unwrap().1;
1721 bindings.last_mut().unwrap().1.extend(collected);
1723 // This or-pattern itself can itself be part of a product,
1724 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
1725 // Both cases bind `a` again in a product pattern and must be rejected.
1726 let collected = bindings.pop().unwrap().1;
1727 bindings.last_mut().unwrap().1.extend(collected);
1729 // Prevent visiting `ps` as we've already done so above.
1742 pat_src: PatternSource,
1743 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1745 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
1746 // (We must not add it if it's in the bindings map because that breaks the assumptions
1747 // later passes make about or-patterns.)
1748 let ident = ident.normalize_to_macro_rules();
1750 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
1751 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
1752 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
1753 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
1754 // This is *required* for consistency which is checked later.
1755 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
1757 if already_bound_and {
1758 // Overlap in a product pattern somewhere; report an error.
1759 use ResolutionError::*;
1760 let error = match pat_src {
1761 // `fn f(a: u8, a: u8)`:
1762 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
1764 _ => IdentifierBoundMoreThanOnceInSamePattern,
1766 self.report_error(ident.span, error(ident.name));
1769 // Record as bound if it's valid:
1770 let ident_valid = ident.name != kw::Empty;
1772 bindings.last_mut().unwrap().1.insert(ident);
1775 if already_bound_or {
1776 // `Variant1(a) | Variant2(a)`, ok
1777 // Reuse definition from the first `a`.
1778 self.innermost_rib_bindings(ValueNS)[&ident]
1780 let res = Res::Local(pat_id);
1782 // A completely fresh binding add to the set if it's valid.
1783 self.innermost_rib_bindings(ValueNS).insert(ident, res);
1789 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
1790 &mut self.ribs[ns].last_mut().unwrap().bindings
1793 fn try_resolve_as_non_binding(
1795 pat_src: PatternSource,
1800 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
1801 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
1802 // also be interpreted as a path to e.g. a constant, variant, etc.
1803 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
1805 let ls_binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, Finalize::No)?;
1806 let (res, binding) = match ls_binding {
1807 LexicalScopeBinding::Item(binding)
1808 if is_syntactic_ambiguity && binding.is_ambiguity() =>
1810 // For ambiguous bindings we don't know all their definitions and cannot check
1811 // whether they can be shadowed by fresh bindings or not, so force an error.
1812 // issues/33118#issuecomment-233962221 (see below) still applies here,
1813 // but we have to ignore it for backward compatibility.
1814 self.r.record_use(ident, binding, false);
1817 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
1818 LexicalScopeBinding::Res(res) => (res, None),
1822 Res::SelfCtor(_) // See #70549.
1824 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
1826 ) if is_syntactic_ambiguity => {
1827 // Disambiguate in favor of a unit struct/variant or constant pattern.
1828 if let Some(binding) = binding {
1829 self.r.record_use(ident, binding, false);
1833 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static(_), _) => {
1834 // This is unambiguously a fresh binding, either syntactically
1835 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
1836 // to something unusable as a pattern (e.g., constructor function),
1837 // but we still conservatively report an error, see
1838 // issues/33118#issuecomment-233962221 for one reason why.
1839 let binding = binding.expect("no binding for a ctor or static");
1842 ResolutionError::BindingShadowsSomethingUnacceptable {
1843 shadowing_binding_descr: pat_src.descr(),
1845 participle: if binding.is_import() { "imported" } else { "defined" },
1846 article: binding.res().article(),
1847 shadowed_binding_descr: binding.res().descr(),
1848 shadowed_binding_span: binding.span,
1853 Res::Def(DefKind::ConstParam, def_id) => {
1854 // Same as for DefKind::Const above, but here, `binding` is `None`, so we
1855 // have to construct the error differently
1858 ResolutionError::BindingShadowsSomethingUnacceptable {
1859 shadowing_binding_descr: pat_src.descr(),
1861 participle: "defined",
1862 article: res.article(),
1863 shadowed_binding_descr: res.descr(),
1864 shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"),
1869 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
1870 // These entities are explicitly allowed to be shadowed by fresh bindings.
1875 "unexpected resolution for an identifier in pattern: {:?}",
1881 // High-level and context dependent path resolution routine.
1882 // Resolves the path and records the resolution into definition map.
1883 // If resolution fails tries several techniques to find likely
1884 // resolution candidates, suggest imports or other help, and report
1885 // errors in user friendly way.
1886 fn smart_resolve_path(
1889 qself: Option<&QSelf>,
1891 source: PathSource<'ast>,
1893 self.smart_resolve_path_fragment(
1895 &Segment::from_path(path),
1897 Finalize::SimplePath(id, path.span),
1901 fn smart_resolve_path_fragment(
1903 qself: Option<&QSelf>,
1905 source: PathSource<'ast>,
1909 "smart_resolve_path_fragment(qself={:?}, path={:?}, finalize={:?})",
1914 let ns = source.namespace();
1916 let (id, path_span) =
1917 finalize.node_id_and_path_span().expect("unexpected speculative resolution");
1918 let report_errors = |this: &mut Self, res: Option<Res>| {
1919 if this.should_report_errs() {
1920 let (err, candidates) =
1921 this.smart_resolve_report_errors(path, path_span, source, res);
1923 let def_id = this.parent_scope.module.nearest_parent_mod();
1924 let instead = res.is_some();
1926 if res.is_none() { this.report_missing_type_error(path) } else { None };
1928 this.r.use_injections.push(UseError {
1937 PartialRes::new(Res::Err)
1940 // For paths originating from calls (like in `HashMap::new()`), tries
1941 // to enrich the plain `failed to resolve: ...` message with hints
1942 // about possible missing imports.
1944 // Similar thing, for types, happens in `report_errors` above.
1945 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
1946 if !source.is_call() {
1947 return Some(parent_err);
1950 // Before we start looking for candidates, we have to get our hands
1951 // on the type user is trying to perform invocation on; basically:
1952 // we're transforming `HashMap::new` into just `HashMap`.
1953 let path = match path.split_last() {
1954 Some((_, path)) if !path.is_empty() => path,
1955 _ => return Some(parent_err),
1958 let (mut err, candidates) =
1959 this.smart_resolve_report_errors(path, path_span, PathSource::Type, None);
1961 if candidates.is_empty() {
1963 return Some(parent_err);
1966 // There are two different error messages user might receive at
1968 // - E0412 cannot find type `{}` in this scope
1969 // - E0433 failed to resolve: use of undeclared type or module `{}`
1971 // The first one is emitted for paths in type-position, and the
1972 // latter one - for paths in expression-position.
1974 // Thus (since we're in expression-position at this point), not to
1975 // confuse the user, we want to keep the *message* from E0432 (so
1976 // `parent_err`), but we want *hints* from E0412 (so `err`).
1978 // And that's what happens below - we're just mixing both messages
1979 // into a single one.
1980 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
1982 err.message = take(&mut parent_err.message);
1983 err.code = take(&mut parent_err.code);
1984 err.children = take(&mut parent_err.children);
1986 parent_err.cancel();
1988 let def_id = this.parent_scope.module.nearest_parent_mod();
1990 if this.should_report_errs() {
1991 this.r.use_injections.push(UseError {
2002 // We don't return `Some(parent_err)` here, because the error will
2003 // be already printed as part of the `use` injections
2007 let partial_res = match self.resolve_qpath_anywhere(
2012 source.defer_to_typeck(),
2015 Ok(Some(partial_res)) if partial_res.unresolved_segments() == 0 => {
2016 if source.is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err
2020 report_errors(self, Some(partial_res.base_res()))
2024 Ok(Some(partial_res)) if source.defer_to_typeck() => {
2025 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
2026 // or `<T>::A::B`. If `B` should be resolved in value namespace then
2027 // it needs to be added to the trait map.
2029 let item_name = path.last().unwrap().ident;
2030 let traits = self.traits_in_scope(item_name, ns);
2031 self.r.trait_map.insert(id, traits);
2034 if PrimTy::from_name(path[0].ident.name).is_some() {
2035 let mut std_path = Vec::with_capacity(1 + path.len());
2037 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
2038 std_path.extend(path);
2039 if let PathResult::Module(_) | PathResult::NonModule(_) =
2040 self.resolve_path(&std_path, Some(ns), Finalize::No)
2042 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
2044 path.iter().last().map_or(path_span, |segment| segment.ident.span);
2046 self.r.confused_type_with_std_module.insert(item_span, path_span);
2047 self.r.confused_type_with_std_module.insert(path_span, path_span);
2055 if let Some(err) = report_errors_for_call(self, err) {
2056 self.report_error(err.span, err.node);
2059 PartialRes::new(Res::Err)
2062 _ => report_errors(self, None),
2065 if !matches!(source, PathSource::TraitItem(..)) {
2066 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
2067 self.r.record_partial_res(id, partial_res);
2073 fn self_type_is_available(&mut self) -> bool {
2074 let binding = self.resolve_ident_in_lexical_scope(
2075 Ident::with_dummy_span(kw::SelfUpper),
2079 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
2082 fn self_value_is_available(&mut self, self_span: Span) -> bool {
2083 let ident = Ident::new(kw::SelfLower, self_span);
2084 let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, Finalize::No);
2085 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
2088 /// A wrapper around [`Resolver::report_error`].
2090 /// This doesn't emit errors for function bodies if this is rustdoc.
2091 fn report_error(&self, span: Span, resolution_error: ResolutionError<'_>) {
2092 if self.should_report_errs() {
2093 self.r.report_error(span, resolution_error);
2098 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
2099 fn should_report_errs(&self) -> bool {
2100 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
2103 // Resolve in alternative namespaces if resolution in the primary namespace fails.
2104 fn resolve_qpath_anywhere(
2106 qself: Option<&QSelf>,
2108 primary_ns: Namespace,
2110 defer_to_typeck: bool,
2112 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2113 let mut fin_res = None;
2115 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
2116 if i == 0 || ns != primary_ns {
2117 match self.resolve_qpath(qself, path, ns, finalize)? {
2119 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
2121 return Ok(Some(partial_res));
2124 if fin_res.is_none() {
2125 fin_res = partial_res;
2132 assert!(primary_ns != MacroNS);
2134 if qself.is_none() {
2135 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
2136 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
2137 if let Ok((_, res)) =
2138 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
2140 return Ok(Some(PartialRes::new(res)));
2147 /// Handles paths that may refer to associated items.
2150 qself: Option<&QSelf>,
2154 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2156 "resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})",
2157 qself, path, ns, finalize,
2160 if let Some(qself) = qself {
2161 if qself.position == 0 {
2162 // This is a case like `<T>::B`, where there is no
2163 // trait to resolve. In that case, we leave the `B`
2164 // segment to be resolved by type-check.
2165 return Ok(Some(PartialRes::with_unresolved_segments(
2166 Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX)),
2171 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
2173 // Currently, `path` names the full item (`A::B::C`, in
2174 // our example). so we extract the prefix of that that is
2175 // the trait (the slice upto and including
2176 // `qself.position`). And then we recursively resolve that,
2177 // but with `qself` set to `None`.
2179 // However, setting `qself` to none (but not changing the
2180 // span) loses the information about where this path
2181 // *actually* appears, so for the purposes of the crate
2182 // lint we pass along information that this is the trait
2183 // name from a fully qualified path, and this also
2184 // contains the full span (the `Finalize::QPathTrait`).
2185 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2186 let partial_res = self.smart_resolve_path_fragment(
2188 &path[..=qself.position],
2189 PathSource::TraitItem(ns),
2190 finalize.node_id_and_path_span().map_or(Finalize::No, |(qpath_id, path_span)| {
2191 Finalize::QPathTrait { qpath_id, qpath_span: qself.path_span, path_span }
2195 // The remaining segments (the `C` in our example) will
2196 // have to be resolved by type-check, since that requires doing
2197 // trait resolution.
2198 return Ok(Some(PartialRes::with_unresolved_segments(
2199 partial_res.base_res(),
2200 partial_res.unresolved_segments() + path.len() - qself.position - 1,
2204 let result = match self.resolve_path(&path, Some(ns), finalize) {
2205 PathResult::NonModule(path_res) => path_res,
2206 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
2207 PartialRes::new(module.res().unwrap())
2209 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2210 // don't report an error right away, but try to fallback to a primitive type.
2211 // So, we are still able to successfully resolve something like
2213 // use std::u8; // bring module u8 in scope
2214 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2215 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
2216 // // not to non-existent std::u8::max_value
2219 // Such behavior is required for backward compatibility.
2220 // The same fallback is used when `a` resolves to nothing.
2221 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
2222 if (ns == TypeNS || path.len() > 1)
2223 && PrimTy::from_name(path[0].ident.name).is_some() =>
2225 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
2226 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
2228 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2229 PartialRes::new(module.res().unwrap())
2231 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
2232 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
2234 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
2235 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
2239 && result.base_res() != Res::Err
2240 && path[0].ident.name != kw::PathRoot
2241 && path[0].ident.name != kw::DollarCrate
2242 && let Some((id, path_span)) = finalize.node_id_and_path_span()
2244 let unqualified_result = {
2245 match self.resolve_path(&[*path.last().unwrap()], Some(ns), Finalize::No) {
2246 PathResult::NonModule(path_res) => path_res.base_res(),
2247 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2248 module.res().unwrap()
2250 _ => return Ok(Some(result)),
2253 if result.base_res() == unqualified_result {
2254 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
2255 self.r.lint_buffer.buffer_lint(lint, id, path_span, "unnecessary qualification")
2262 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
2263 if let Some(label) = label {
2264 if label.ident.as_str().as_bytes()[1] != b'_' {
2265 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
2267 self.with_label_rib(NormalRibKind, |this| {
2268 let ident = label.ident.normalize_to_macro_rules();
2269 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
2277 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
2278 self.with_resolved_label(label, id, |this| this.visit_block(block));
2281 fn resolve_block(&mut self, block: &'ast Block) {
2282 debug!("(resolving block) entering block");
2283 // Move down in the graph, if there's an anonymous module rooted here.
2284 let orig_module = self.parent_scope.module;
2285 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
2287 let mut num_macro_definition_ribs = 0;
2288 if let Some(anonymous_module) = anonymous_module {
2289 debug!("(resolving block) found anonymous module, moving down");
2290 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2291 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2292 self.parent_scope.module = anonymous_module;
2294 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2297 let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
2298 if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
2299 (block.could_be_bare_literal, &block.stmts[..])
2300 && let ExprKind::Type(..) = expr.kind
2302 self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
2305 // Descend into the block.
2306 for stmt in &block.stmts {
2307 if let StmtKind::Item(ref item) = stmt.kind
2308 && let ItemKind::MacroDef(..) = item.kind {
2309 num_macro_definition_ribs += 1;
2310 let res = self.r.local_def_id(item.id).to_def_id();
2311 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
2312 self.label_ribs.push(Rib::new(MacroDefinition(res)));
2315 self.visit_stmt(stmt);
2317 self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
2320 self.parent_scope.module = orig_module;
2321 for _ in 0..num_macro_definition_ribs {
2322 self.ribs[ValueNS].pop();
2323 self.label_ribs.pop();
2325 self.ribs[ValueNS].pop();
2326 if anonymous_module.is_some() {
2327 self.ribs[TypeNS].pop();
2329 debug!("(resolving block) leaving block");
2332 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
2333 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
2334 self.with_constant_rib(
2336 constant.value.is_potential_trivial_const_param(),
2339 visit::walk_anon_const(this, constant);
2344 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
2345 // First, record candidate traits for this expression if it could
2346 // result in the invocation of a method call.
2348 self.record_candidate_traits_for_expr_if_necessary(expr);
2350 // Next, resolve the node.
2352 ExprKind::Path(ref qself, ref path) => {
2353 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
2354 visit::walk_expr(self, expr);
2357 ExprKind::Struct(ref se) => {
2358 self.smart_resolve_path(expr.id, se.qself.as_ref(), &se.path, PathSource::Struct);
2359 visit::walk_expr(self, expr);
2362 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
2363 if let Some(node_id) = self.resolve_label(label.ident) {
2364 // Since this res is a label, it is never read.
2365 self.r.label_res_map.insert(expr.id, node_id);
2366 self.diagnostic_metadata.unused_labels.remove(&node_id);
2369 // visit `break` argument if any
2370 visit::walk_expr(self, expr);
2373 ExprKind::Break(None, Some(ref e)) => {
2374 // We use this instead of `visit::walk_expr` to keep the parent expr around for
2375 // better diagnostics.
2376 self.resolve_expr(e, Some(&expr));
2379 ExprKind::Let(ref pat, ref scrutinee, _) => {
2380 self.visit_expr(scrutinee);
2381 self.resolve_pattern_top(pat, PatternSource::Let);
2384 ExprKind::If(ref cond, ref then, ref opt_else) => {
2385 self.with_rib(ValueNS, NormalRibKind, |this| {
2386 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
2387 this.visit_expr(cond);
2388 this.diagnostic_metadata.in_if_condition = old;
2389 this.visit_block(then);
2391 if let Some(expr) = opt_else {
2392 self.visit_expr(expr);
2396 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
2398 ExprKind::While(ref cond, ref block, label) => {
2399 self.with_resolved_label(label, expr.id, |this| {
2400 this.with_rib(ValueNS, NormalRibKind, |this| {
2401 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
2402 this.visit_expr(cond);
2403 this.diagnostic_metadata.in_if_condition = old;
2404 this.visit_block(block);
2409 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
2410 self.visit_expr(iter_expr);
2411 self.with_rib(ValueNS, NormalRibKind, |this| {
2412 this.resolve_pattern_top(pat, PatternSource::For);
2413 this.resolve_labeled_block(label, expr.id, block);
2417 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
2419 // Equivalent to `visit::walk_expr` + passing some context to children.
2420 ExprKind::Field(ref subexpression, _) => {
2421 self.resolve_expr(subexpression, Some(expr));
2423 ExprKind::MethodCall(ref segment, ref arguments, _) => {
2424 let mut arguments = arguments.iter();
2425 self.resolve_expr(arguments.next().unwrap(), Some(expr));
2426 for argument in arguments {
2427 self.resolve_expr(argument, None);
2429 self.visit_path_segment(expr.span, segment);
2432 ExprKind::Call(ref callee, ref arguments) => {
2433 self.resolve_expr(callee, Some(expr));
2434 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
2435 for (idx, argument) in arguments.iter().enumerate() {
2436 // Constant arguments need to be treated as AnonConst since
2437 // that is how they will be later lowered to HIR.
2438 if const_args.contains(&idx) {
2439 self.with_constant_rib(
2441 argument.is_potential_trivial_const_param(),
2444 this.resolve_expr(argument, None);
2448 self.resolve_expr(argument, None);
2452 ExprKind::Type(ref type_expr, ref ty) => {
2453 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
2454 // type ascription. Here we are trying to retrieve the span of the colon token as
2455 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
2456 // with `expr::Ty`, only in this case it will match the span from
2457 // `type_ascription_path_suggestions`.
2458 self.diagnostic_metadata
2459 .current_type_ascription
2460 .push(type_expr.span.between(ty.span));
2461 visit::walk_expr(self, expr);
2462 self.diagnostic_metadata.current_type_ascription.pop();
2464 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
2465 // resolve the arguments within the proper scopes so that usages of them inside the
2466 // closure are detected as upvars rather than normal closure arg usages.
2467 ExprKind::Closure(_, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
2468 self.with_rib(ValueNS, NormalRibKind, |this| {
2469 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
2470 // Resolve arguments:
2471 this.resolve_params(&fn_decl.inputs);
2472 // No need to resolve return type --
2473 // the outer closure return type is `FnRetTy::Default`.
2475 // Now resolve the inner closure
2477 // No need to resolve arguments: the inner closure has none.
2478 // Resolve the return type:
2479 visit::walk_fn_ret_ty(this, &fn_decl.output);
2481 this.visit_expr(body);
2486 ExprKind::Async(..) | ExprKind::Closure(..) => {
2487 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
2489 ExprKind::Repeat(ref elem, ref ct) => {
2490 self.visit_expr(elem);
2491 self.resolve_anon_const(ct, IsRepeatExpr::Yes);
2493 ExprKind::Index(ref elem, ref idx) => {
2494 self.resolve_expr(elem, Some(expr));
2495 self.visit_expr(idx);
2498 visit::walk_expr(self, expr);
2503 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
2505 ExprKind::Field(_, ident) => {
2506 // FIXME(#6890): Even though you can't treat a method like a
2507 // field, we need to add any trait methods we find that match
2508 // the field name so that we can do some nice error reporting
2509 // later on in typeck.
2510 let traits = self.traits_in_scope(ident, ValueNS);
2511 self.r.trait_map.insert(expr.id, traits);
2513 ExprKind::MethodCall(ref segment, ..) => {
2514 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
2515 let traits = self.traits_in_scope(segment.ident, ValueNS);
2516 self.r.trait_map.insert(expr.id, traits);
2524 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
2525 self.r.traits_in_scope(
2526 self.current_trait_ref.as_ref().map(|(module, _)| *module),
2529 Some((ident.name, ns)),
2533 fn compute_num_lifetime_params(&mut self, id: NodeId, generics: &Generics) {
2534 let def_id = self.r.local_def_id(id);
2535 let count = generics
2538 .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
2540 self.r.item_generics_num_lifetimes.insert(def_id, count);
2544 impl<'a> Resolver<'a> {
2545 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
2546 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
2547 visit::walk_crate(&mut late_resolution_visitor, krate);
2548 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
2549 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");