1 //! "Late resolution" is the pass that resolves most of names in a crate beside imports and macros.
2 //! It runs when the crate is fully expanded and its module structure is fully built.
3 //! So it just walks through the crate and resolves all the expressions, types, etc.
5 //! If you wonder why there's no `early.rs`, that's because it's split into three files -
6 //! `build_reduced_graph.rs`, `macros.rs` and `imports.rs`.
10 use crate::{path_names_to_string, BindingError, CrateLint, NameBinding, ToNameBinding};
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, ty};
25 use rustc_session::lint;
26 use rustc_span::source_map::{respan, Spanned};
27 use rustc_span::symbol::{kw, sym, Ident, Symbol};
28 use rustc_span::{Span, DUMMY_SP};
29 use smallvec::{smallvec, SmallVec};
32 use std::collections::{hash_map::Entry, BTreeSet};
33 use std::mem::{replace, take};
38 type Res = def::Res<NodeId>;
40 #[derive(Copy, Clone, Debug)]
43 binding_mode: BindingMode,
46 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
54 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
61 fn descr(self) -> &'static str {
63 PatternSource::Match => "match binding",
64 PatternSource::Let => "let binding",
65 PatternSource::For => "for binding",
66 PatternSource::FnParam => "function parameter",
71 /// Denotes whether the context for the set of already bound bindings is a `Product`
72 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
73 /// See those functions for more information.
76 /// A product pattern context, e.g., `Variant(a, b)`.
78 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
82 /// Does this the item (from the item rib scope) allow generic parameters?
83 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
84 crate enum HasGenericParams {
89 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
90 crate enum ConstantItemKind {
95 /// The rib kind restricts certain accesses,
96 /// e.g. to a `Res::Local` of an outer item.
97 #[derive(Copy, Clone, Debug)]
98 crate enum RibKind<'a> {
99 /// No restriction needs to be applied.
102 /// We passed through an impl or trait and are now in one of its
103 /// methods or associated types. Allow references to ty params that impl or trait
104 /// binds. Disallow any other upvars (including other ty params that are
108 /// We passed through a closure. Disallow labels.
109 ClosureOrAsyncRibKind,
111 /// We passed through a function definition. Disallow upvars.
112 /// Permit only those const parameters that are specified in the function's generics.
115 /// We passed through an item scope. Disallow upvars.
116 ItemRibKind(HasGenericParams),
118 /// We're in a constant item. Can't refer to dynamic stuff.
120 /// The `bool` indicates if this constant may reference generic parameters
121 /// and is used to only allow generic parameters to be used in trivial constant expressions.
122 ConstantItemRibKind(bool, Option<(Ident, ConstantItemKind)>),
124 /// We passed through a module.
125 ModuleRibKind(Module<'a>),
127 /// We passed through a `macro_rules!` statement
128 MacroDefinition(DefId),
130 /// All bindings in this rib are generic parameters that can't be used
131 /// from the default of a generic parameter because they're not declared
132 /// before said generic parameter. Also see the `visit_generics` override.
133 ForwardGenericParamBanRibKind,
135 /// We are inside of the type of a const parameter. Can't refer to any
141 /// Whether this rib kind contains generic parameters, as opposed to local
143 crate fn contains_params(&self) -> bool {
146 | ClosureOrAsyncRibKind
148 | ConstantItemRibKind(..)
151 | ConstParamTyRibKind => false,
152 AssocItemRibKind | ItemRibKind(_) | ForwardGenericParamBanRibKind => true,
157 /// A single local scope.
159 /// A rib represents a scope names can live in. Note that these appear in many places, not just
160 /// around braces. At any place where the list of accessible names (of the given namespace)
161 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
162 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
165 /// Different [rib kinds](enum.RibKind) are transparent for different names.
167 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
168 /// resolving, the name is looked up from inside out.
170 crate struct Rib<'a, R = &'a NameBinding<'a>> {
171 pub bindings: FxHashMap<Ident, R>,
172 pub kind: RibKind<'a>,
175 impl<'a, R> Rib<'a, R> {
176 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
177 Rib { bindings: Default::default(), kind }
181 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
182 crate enum AliasPossibility {
187 #[derive(Copy, Clone, Debug)]
188 crate enum PathSource<'a> {
189 // Type paths `Path`.
191 // Trait paths in bounds or impls.
192 Trait(AliasPossibility),
193 // Expression paths `path`, with optional parent context.
194 Expr(Option<&'a Expr>),
195 // Paths in path patterns `Path`.
197 // Paths in struct expressions and patterns `Path { .. }`.
199 // Paths in tuple struct patterns `Path(..)`.
200 TupleStruct(Span, &'a [Span]),
201 // `m::A::B` in `<T as m::A>::B::C`.
202 TraitItem(Namespace),
205 impl<'a> PathSource<'a> {
206 fn namespace(self) -> Namespace {
208 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
209 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
210 PathSource::TraitItem(ns) => ns,
214 fn defer_to_typeck(self) -> bool {
217 | PathSource::Expr(..)
220 | PathSource::TupleStruct(..) => true,
221 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
225 fn descr_expected(self) -> &'static str {
227 PathSource::Type => "type",
228 PathSource::Trait(_) => "trait",
229 PathSource::Pat => "unit struct, unit variant or constant",
230 PathSource::Struct => "struct, variant or union type",
231 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
232 PathSource::TraitItem(ns) => match ns {
233 TypeNS => "associated type",
234 ValueNS => "method or associated constant",
235 MacroNS => bug!("associated macro"),
237 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
238 // "function" here means "anything callable" rather than `DefKind::Fn`,
239 // this is not precise but usually more helpful than just "value".
240 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
241 // the case of `::some_crate()`
242 ExprKind::Path(_, path)
243 if path.segments.len() == 2
244 && path.segments[0].ident.name == kw::PathRoot =>
248 ExprKind::Path(_, path) => {
249 let mut msg = "function";
250 if let Some(segment) = path.segments.iter().last() {
251 if let Some(c) = segment.ident.to_string().chars().next() {
252 if c.is_uppercase() {
253 msg = "function, tuple struct or tuple variant";
266 fn is_call(self) -> bool {
267 matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
270 crate fn is_expected(self, res: Res) -> bool {
272 PathSource::Type => matches!(
279 | DefKind::TraitAlias
284 | DefKind::ForeignTy,
289 PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
290 PathSource::Trait(AliasPossibility::Maybe) => {
291 matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
293 PathSource::Expr(..) => matches!(
296 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
301 | DefKind::AssocConst
302 | DefKind::ConstParam,
307 PathSource::Pat => matches!(
310 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::AssocConst,
312 ) | Res::SelfCtor(..)
314 PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
315 PathSource::Struct => matches!(
326 PathSource::TraitItem(ns) => match res {
327 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
328 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
334 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
335 use rustc_errors::error_code;
336 match (self, has_unexpected_resolution) {
337 (PathSource::Trait(_), true) => error_code!(E0404),
338 (PathSource::Trait(_), false) => error_code!(E0405),
339 (PathSource::Type, true) => error_code!(E0573),
340 (PathSource::Type, false) => error_code!(E0412),
341 (PathSource::Struct, true) => error_code!(E0574),
342 (PathSource::Struct, false) => error_code!(E0422),
343 (PathSource::Expr(..), true) => error_code!(E0423),
344 (PathSource::Expr(..), false) => error_code!(E0425),
345 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
346 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
347 (PathSource::TraitItem(..), true) => error_code!(E0575),
348 (PathSource::TraitItem(..), false) => error_code!(E0576),
354 struct DiagnosticMetadata<'ast> {
355 /// The current trait's associated items' ident, used for diagnostic suggestions.
356 current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
358 /// The current self type if inside an impl (used for better errors).
359 current_self_type: Option<Ty>,
361 /// The current self item if inside an ADT (used for better errors).
362 current_self_item: Option<NodeId>,
364 /// The current trait (used to suggest).
365 current_item: Option<&'ast Item>,
367 /// When processing generics and encountering a type not found, suggest introducing a type
369 currently_processing_generics: bool,
371 /// The current enclosing (non-closure) function (used for better errors).
372 current_function: Option<(FnKind<'ast>, Span)>,
374 /// A list of labels as of yet unused. Labels will be removed from this map when
375 /// they are used (in a `break` or `continue` statement)
376 unused_labels: FxHashMap<NodeId, Span>,
378 /// Only used for better errors on `fn(): fn()`.
379 current_type_ascription: Vec<Span>,
381 /// Only used for better errors on `let x = { foo: bar };`.
382 /// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only
383 /// needed for cases where this parses as a correct type ascription.
384 current_block_could_be_bare_struct_literal: Option<Span>,
386 /// Only used for better errors on `let <pat>: <expr, not type>;`.
387 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
389 /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
390 in_if_condition: Option<&'ast Expr>,
392 /// If we are currently in a trait object definition. Used to point at the bounds when
393 /// encountering a struct or enum.
394 current_trait_object: Option<&'ast [ast::GenericBound]>,
396 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
397 current_where_predicate: Option<&'ast WherePredicate>,
400 struct LateResolutionVisitor<'a, 'b, 'ast> {
401 r: &'b mut Resolver<'a>,
403 /// The module that represents the current item scope.
404 parent_scope: ParentScope<'a>,
406 /// The current set of local scopes for types and values.
407 /// FIXME #4948: Reuse ribs to avoid allocation.
408 ribs: PerNS<Vec<Rib<'a>>>,
410 /// The current set of local scopes, for labels.
411 label_ribs: Vec<Rib<'a, NodeId>>,
413 /// The trait that the current context can refer to.
414 current_trait_ref: Option<(Module<'a>, TraitRef)>,
416 /// Fields used to add information to diagnostic errors.
417 diagnostic_metadata: DiagnosticMetadata<'ast>,
419 /// State used to know whether to ignore resolution errors for function bodies.
421 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
422 /// In most cases this will be `None`, in which case errors will always be reported.
423 /// If it is `true`, then it will be updated when entering a nested function or trait body.
427 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
428 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
429 fn visit_item(&mut self, item: &'ast Item) {
430 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
431 // Always report errors in items we just entered.
432 let old_ignore = replace(&mut self.in_func_body, false);
433 self.resolve_item(item);
434 self.in_func_body = old_ignore;
435 self.diagnostic_metadata.current_item = prev;
437 fn visit_arm(&mut self, arm: &'ast Arm) {
438 self.resolve_arm(arm);
440 fn visit_block(&mut self, block: &'ast Block) {
441 self.resolve_block(block);
443 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
444 // We deal with repeat expressions explicitly in `resolve_expr`.
445 self.resolve_anon_const(constant, IsRepeatExpr::No);
447 fn visit_expr(&mut self, expr: &'ast Expr) {
448 self.resolve_expr(expr, None);
450 fn visit_local(&mut self, local: &'ast Local) {
451 let local_spans = match local.pat.kind {
452 // We check for this to avoid tuple struct fields.
453 PatKind::Wild => None,
456 local.ty.as_ref().map(|ty| ty.span),
457 local.kind.init().map(|init| init.span),
460 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
461 self.resolve_local(local);
462 self.diagnostic_metadata.current_let_binding = original;
464 fn visit_ty(&mut self, ty: &'ast Ty) {
465 let prev = self.diagnostic_metadata.current_trait_object;
467 TyKind::Path(ref qself, ref path) => {
468 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
470 TyKind::ImplicitSelf => {
471 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
473 .resolve_ident_in_lexical_scope(self_ty, TypeNS, Some(ty.id), ty.span)
474 .map_or(Res::Err, |d| d.res());
475 self.r.record_partial_res(ty.id, PartialRes::new(res));
477 TyKind::TraitObject(ref bounds, ..) => {
478 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
482 visit::walk_ty(self, ty);
483 self.diagnostic_metadata.current_trait_object = prev;
485 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef, m: &'ast TraitBoundModifier) {
486 self.smart_resolve_path(
487 tref.trait_ref.ref_id,
489 &tref.trait_ref.path,
490 PathSource::Trait(AliasPossibility::Maybe),
492 visit::walk_poly_trait_ref(self, tref, m);
494 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
495 match foreign_item.kind {
496 ForeignItemKind::Fn(box FnKind(_, _, ref generics, _))
497 | ForeignItemKind::TyAlias(box TyAliasKind(_, ref generics, ..)) => {
498 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
499 visit::walk_foreign_item(this, foreign_item);
502 ForeignItemKind::Static(..) => {
503 self.with_item_rib(HasGenericParams::No, |this| {
504 visit::walk_foreign_item(this, foreign_item);
507 ForeignItemKind::MacCall(..) => {
508 visit::walk_foreign_item(self, foreign_item);
512 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, _: NodeId) {
513 let rib_kind = match fn_kind {
514 // Bail if there's no body.
515 FnKind::Fn(.., None) => return visit::walk_fn(self, fn_kind, sp),
516 FnKind::Fn(FnCtxt::Free | FnCtxt::Foreign, ..) => FnItemRibKind,
517 FnKind::Fn(FnCtxt::Assoc(_), ..) => NormalRibKind,
518 FnKind::Closure(..) => ClosureOrAsyncRibKind,
520 let previous_value = self.diagnostic_metadata.current_function;
521 if matches!(fn_kind, FnKind::Fn(..)) {
522 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
524 debug!("(resolving function) entering function");
525 let declaration = fn_kind.decl();
527 // Create a value rib for the function.
528 self.with_rib(ValueNS, rib_kind, |this| {
529 // Create a label rib for the function.
530 this.with_label_rib(rib_kind, |this| {
531 // Add each argument to the rib.
532 this.resolve_params(&declaration.inputs);
534 visit::walk_fn_ret_ty(this, &declaration.output);
536 // Ignore errors in function bodies if this is rustdoc
537 // Be sure not to set this until the function signature has been resolved.
538 let previous_state = replace(&mut this.in_func_body, true);
539 // Resolve the function body, potentially inside the body of an async closure
541 FnKind::Fn(.., body) => walk_list!(this, visit_block, body),
542 FnKind::Closure(_, body) => this.visit_expr(body),
545 debug!("(resolving function) leaving function");
546 this.in_func_body = previous_state;
549 self.diagnostic_metadata.current_function = previous_value;
552 fn visit_generics(&mut self, generics: &'ast Generics) {
553 // For type parameter defaults, we have to ban access
554 // to following type parameters, as the InternalSubsts can only
555 // provide previous type parameters as they're built. We
556 // put all the parameters on the ban list and then remove
557 // them one by one as they are processed and become available.
558 let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
559 let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
560 for param in generics.params.iter() {
562 GenericParamKind::Type { .. } => {
565 .insert(Ident::with_dummy_span(param.ident.name), self.r.dummy_binding);
567 GenericParamKind::Const { .. } => {
568 forward_const_ban_rib
570 .insert(Ident::with_dummy_span(param.ident.name), self.r.dummy_binding);
572 GenericParamKind::Lifetime => {}
576 // rust-lang/rust#61631: The type `Self` is essentially
577 // another type parameter. For ADTs, we consider it
578 // well-defined only after all of the ADT type parameters have
579 // been provided. Therefore, we do not allow use of `Self`
580 // anywhere in ADT type parameter defaults.
582 // (We however cannot ban `Self` for defaults on *all* generic
583 // lists; e.g. trait generics can usefully refer to `Self`,
584 // such as in the case of `trait Add<Rhs = Self>`.)
585 if self.diagnostic_metadata.current_self_item.is_some() {
586 // (`Some` if + only if we are in ADT's generics.)
589 .insert(Ident::with_dummy_span(kw::SelfUpper), self.r.dummy_binding);
592 for param in &generics.params {
594 GenericParamKind::Lifetime => self.visit_generic_param(param),
595 GenericParamKind::Type { ref default } => {
596 for bound in ¶m.bounds {
597 self.visit_param_bound(bound);
600 if let Some(ref ty) = default {
601 self.ribs[TypeNS].push(forward_ty_ban_rib);
602 self.ribs[ValueNS].push(forward_const_ban_rib);
604 forward_const_ban_rib = self.ribs[ValueNS].pop().unwrap();
605 forward_ty_ban_rib = self.ribs[TypeNS].pop().unwrap();
608 // Allow all following defaults to refer to this type parameter.
609 forward_ty_ban_rib.bindings.remove(&Ident::with_dummy_span(param.ident.name));
611 GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
612 // Const parameters can't have param bounds.
613 assert!(param.bounds.is_empty());
615 self.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
616 self.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
618 self.ribs[TypeNS].pop().unwrap();
619 self.ribs[ValueNS].pop().unwrap();
621 if let Some(ref expr) = default {
622 self.ribs[TypeNS].push(forward_ty_ban_rib);
623 self.ribs[ValueNS].push(forward_const_ban_rib);
624 self.visit_anon_const(expr);
625 forward_const_ban_rib = self.ribs[ValueNS].pop().unwrap();
626 forward_ty_ban_rib = self.ribs[TypeNS].pop().unwrap();
629 // Allow all following defaults to refer to this const parameter.
630 forward_const_ban_rib
632 .remove(&Ident::with_dummy_span(param.ident.name));
636 for p in &generics.where_clause.predicates {
637 self.visit_where_predicate(p);
641 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
642 debug!("visit_generic_arg({:?})", arg);
643 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
645 GenericArg::Type(ref ty) => {
646 // We parse const arguments as path types as we cannot distinguish them during
647 // parsing. We try to resolve that ambiguity by attempting resolution the type
648 // namespace first, and if that fails we try again in the value namespace. If
649 // resolution in the value namespace succeeds, we have an generic const argument on
651 if let TyKind::Path(ref qself, ref path) = ty.kind {
652 // We cannot disambiguate multi-segment paths right now as that requires type
654 if path.segments.len() == 1 && path.segments[0].args.is_none() {
655 let mut check_ns = |ns| {
656 self.resolve_ident_in_lexical_scope(
657 path.segments[0].ident,
664 if !check_ns(TypeNS) && check_ns(ValueNS) {
665 // This must be equivalent to `visit_anon_const`, but we cannot call it
666 // directly due to visitor lifetimes so we have to copy-paste some code.
668 // Note that we might not be inside of an repeat expression here,
669 // but considering that `IsRepeatExpr` is only relevant for
670 // non-trivial constants this is doesn't matter.
671 self.with_constant_rib(IsRepeatExpr::No, true, None, |this| {
672 this.smart_resolve_path(
676 PathSource::Expr(None),
679 if let Some(ref qself) = *qself {
680 this.visit_ty(&qself.ty);
682 this.visit_path(path, ty.id);
685 self.diagnostic_metadata.currently_processing_generics = prev;
693 GenericArg::Lifetime(lt) => self.visit_lifetime(lt),
694 GenericArg::Const(ct) => self.visit_anon_const(ct),
696 self.diagnostic_metadata.currently_processing_generics = prev;
699 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
700 debug!("visit_where_predicate {:?}", p);
702 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
703 visit::walk_where_predicate(self, p);
704 self.diagnostic_metadata.current_where_predicate = previous_value;
708 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
709 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
710 // During late resolution we only track the module component of the parent scope,
711 // although it may be useful to track other components as well for diagnostics.
712 let graph_root = resolver.graph_root;
713 let parent_scope = ParentScope::module(graph_root, resolver);
714 let start_rib_kind = ModuleRibKind(graph_root);
715 LateResolutionVisitor {
719 value_ns: vec![Rib::new(start_rib_kind)],
720 type_ns: vec![Rib::new(start_rib_kind)],
721 macro_ns: vec![Rib::new(start_rib_kind)],
723 label_ribs: Vec::new(),
724 current_trait_ref: None,
725 diagnostic_metadata: DiagnosticMetadata::default(),
726 // errors at module scope should always be reported
731 fn resolve_ident_in_lexical_scope(
735 record_used_id: Option<NodeId>,
737 ) -> Option<&'a NameBinding<'a>> {
739 .resolve_ident_in_lexical_scope(
753 opt_ns: Option<Namespace>, // `None` indicates a module path in import
756 crate_lint: CrateLint,
757 ) -> PathResult<'a> {
758 self.r.resolve_path_with_ribs(
771 // We maintain a list of value ribs and type ribs.
773 // Simultaneously, we keep track of the current position in the module
774 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
775 // the value or type namespaces, we first look through all the ribs and
776 // then query the module graph. When we resolve a name in the module
777 // namespace, we can skip all the ribs (since nested modules are not
778 // allowed within blocks in Rust) and jump straight to the current module
781 // Named implementations are handled separately. When we find a method
782 // call, we consult the module node to find all of the implementations in
783 // scope. This information is lazily cached in the module node. We then
784 // generate a fake "implementation scope" containing all the
785 // implementations thus found, for compatibility with old resolve pass.
787 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
792 work: impl FnOnce(&mut Self) -> T,
794 self.ribs[ns].push(Rib::new(kind));
795 let ret = work(self);
800 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
801 if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
802 // Move down in the graph.
803 let orig_module = replace(&mut self.parent_scope.module, module);
804 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
805 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
807 this.parent_scope.module = orig_module;
816 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
817 /// label and reports an error if the label is not found or is unreachable.
818 fn resolve_label(&self, mut label: Ident) -> Option<NodeId> {
819 let mut suggestion = None;
821 // Preserve the original span so that errors contain "in this macro invocation"
823 let original_span = label.span;
825 for i in (0..self.label_ribs.len()).rev() {
826 let rib = &self.label_ribs[i];
828 if let MacroDefinition(def) = rib.kind {
829 // If an invocation of this macro created `ident`, give up on `ident`
830 // and switch to `ident`'s source from the macro definition.
831 if def == self.r.macro_def(label.span.ctxt()) {
832 label.span.remove_mark();
836 let ident = label.normalize_to_macro_rules();
837 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
838 return if self.is_label_valid_from_rib(i) {
843 ResolutionError::UnreachableLabel {
845 definition_span: ident.span,
854 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
855 // the first such label that is encountered.
856 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
861 ResolutionError::UndeclaredLabel { name: label.name, suggestion },
866 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
867 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
868 let ribs = &self.label_ribs[rib_index + 1..];
872 NormalRibKind | MacroDefinition(..) => {
873 // Nothing to do. Continue.
877 | ClosureOrAsyncRibKind
880 | ConstantItemRibKind(..)
882 | ForwardGenericParamBanRibKind
883 | ConstParamTyRibKind => {
892 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
893 debug!("resolve_adt");
894 self.with_current_self_item(item, |this| {
895 this.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
896 let item_def_id = this.r.local_def_id(item.id).to_def_id();
897 this.with_self_rib(Res::SelfTy(None, Some((item_def_id, false))), |this| {
898 visit::walk_item(this, item);
904 fn future_proof_import(&mut self, use_tree: &UseTree) {
905 if !self.should_report_errs() {
909 let segments = &use_tree.prefix.segments;
910 if !segments.is_empty() {
911 let ident = segments[0].ident;
912 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
916 let nss = match use_tree.kind {
917 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
921 let from_ribs = |binding: &NameBinding<'_>| {
926 | Res::Def(DefKind::TyParam | DefKind::ConstParam, ..)
929 let report_error = |this: &Self, ns| {
930 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
931 let msg = format!("imports cannot refer to {what}");
932 this.r.session.span_err(ident.span, &msg);
936 if let Some(binding) =
937 self.resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span)
939 if from_ribs(binding) {
940 report_error(self, ns);
942 let orig_unusable_binding =
943 replace(&mut self.r.unusable_binding, Some(binding));
944 if let Some(binding) = self.resolve_ident_in_lexical_scope(
948 use_tree.prefix.span,
950 if from_ribs(binding) {
951 report_error(self, ns);
954 self.r.unusable_binding = orig_unusable_binding;
958 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
959 for (use_tree, _) in use_trees {
960 self.future_proof_import(use_tree);
965 fn resolve_item(&mut self, item: &'ast Item) {
966 let name = item.ident.name;
967 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
970 ItemKind::TyAlias(box TyAliasKind(_, ref generics, _, _))
971 | ItemKind::Fn(box FnKind(_, _, ref generics, _)) => {
972 self.compute_num_lifetime_params(item.id, generics);
973 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
974 visit::walk_item(this, item)
978 ItemKind::Enum(_, ref generics)
979 | ItemKind::Struct(_, ref generics)
980 | ItemKind::Union(_, ref generics) => {
981 self.compute_num_lifetime_params(item.id, generics);
982 self.resolve_adt(item, generics);
985 ItemKind::Impl(box ImplKind {
989 items: ref impl_items,
992 self.compute_num_lifetime_params(item.id, generics);
993 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
996 ItemKind::Trait(box TraitKind(.., ref generics, ref bounds, ref trait_items)) => {
997 self.compute_num_lifetime_params(item.id, generics);
998 // Create a new rib for the trait-wide type parameters.
999 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1000 let local_def_id = this.r.local_def_id(item.id).to_def_id();
1001 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
1002 this.visit_generics(generics);
1003 walk_list!(this, visit_param_bound, bounds);
1005 let walk_assoc_item = |this: &mut Self, generics, item| {
1006 this.with_generic_param_rib(generics, AssocItemRibKind, |this| {
1007 visit::walk_assoc_item(this, item, AssocCtxt::Trait)
1011 this.with_trait_items(trait_items, |this| {
1012 for item in trait_items {
1014 AssocItemKind::Const(_, ty, default) => {
1016 // Only impose the restrictions of `ConstRibKind` for an
1017 // actual constant expression in a provided default.
1018 if let Some(expr) = default {
1019 // We allow arbitrary const expressions inside of associated consts,
1020 // even if they are potentially not const evaluatable.
1022 // Type parameters can already be used and as associated consts are
1023 // not used as part of the type system, this is far less surprising.
1024 this.with_constant_rib(
1028 |this| this.visit_expr(expr),
1032 AssocItemKind::Fn(box FnKind(_, _, generics, _)) => {
1033 walk_assoc_item(this, generics, item);
1035 AssocItemKind::TyAlias(box TyAliasKind(_, generics, _, _)) => {
1036 walk_assoc_item(this, generics, item);
1038 AssocItemKind::MacCall(_) => {
1039 panic!("unexpanded macro in resolve!")
1048 ItemKind::TraitAlias(ref generics, ref bounds) => {
1049 self.compute_num_lifetime_params(item.id, generics);
1050 // Create a new rib for the trait-wide type parameters.
1051 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1052 let local_def_id = this.r.local_def_id(item.id).to_def_id();
1053 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
1054 this.visit_generics(generics);
1055 walk_list!(this, visit_param_bound, bounds);
1060 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
1061 self.with_scope(item.id, |this| {
1062 visit::walk_item(this, item);
1066 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
1067 self.with_item_rib(HasGenericParams::No, |this| {
1069 if let Some(expr) = expr {
1070 let constant_item_kind = match item.kind {
1071 ItemKind::Const(..) => ConstantItemKind::Const,
1072 ItemKind::Static(..) => ConstantItemKind::Static,
1073 _ => unreachable!(),
1075 // We already forbid generic params because of the above item rib,
1076 // so it doesn't matter whether this is a trivial constant.
1077 this.with_constant_rib(
1080 Some((item.ident, constant_item_kind)),
1081 |this| this.visit_expr(expr),
1087 ItemKind::Use(ref use_tree) => {
1088 self.future_proof_import(use_tree);
1091 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => {
1092 // do nothing, these are just around to be encoded
1095 ItemKind::GlobalAsm(_) => {
1096 visit::walk_item(self, item);
1099 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
1103 fn with_generic_param_rib<'c, F>(&'c mut self, generics: &'c Generics, kind: RibKind<'a>, f: F)
1105 F: FnOnce(&mut Self),
1107 debug!("with_generic_param_rib");
1108 let mut function_type_rib = Rib::new(kind);
1109 let mut function_value_rib = Rib::new(kind);
1110 let mut seen_bindings = FxHashMap::default();
1112 // We also can't shadow bindings from the parent item
1113 if let AssocItemRibKind = kind {
1114 let mut add_bindings_for_ns = |ns| {
1115 let parent_rib = self.ribs[ns]
1117 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
1118 .expect("associated item outside of an item");
1120 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
1122 add_bindings_for_ns(ValueNS);
1123 add_bindings_for_ns(TypeNS);
1126 for param in &generics.params {
1127 if let GenericParamKind::Lifetime { .. } = param.kind {
1131 let ident = param.ident.normalize_to_macros_2_0();
1132 debug!("with_generic_param_rib: {}", param.id);
1134 match seen_bindings.entry(ident) {
1135 Entry::Occupied(entry) => {
1136 let span = *entry.get();
1137 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
1138 self.report_error(param.ident.span, err);
1140 Entry::Vacant(entry) => {
1141 entry.insert(param.ident.span);
1145 // Plain insert (no renaming).
1146 let (rib, def_kind) = match param.kind {
1147 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
1148 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
1149 _ => unreachable!(),
1151 let res = Res::Def(def_kind, self.r.local_def_id(param.id).to_def_id());
1153 (res, ty::Visibility::Invisible, param.ident.span, self.parent_scope.expansion)
1154 .to_name_binding(self.r.arenas);
1156 self.r.record_partial_res(param.id, PartialRes::new(res));
1157 rib.bindings.insert(ident, binding);
1160 self.ribs[ValueNS].push(function_value_rib);
1161 self.ribs[TypeNS].push(function_type_rib);
1165 self.ribs[TypeNS].pop();
1166 self.ribs[ValueNS].pop();
1169 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
1170 self.label_ribs.push(Rib::new(kind));
1172 self.label_ribs.pop();
1175 fn with_item_rib(&mut self, has_generic_params: HasGenericParams, f: impl FnOnce(&mut Self)) {
1176 let kind = ItemRibKind(has_generic_params);
1177 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
1180 // HACK(min_const_generics,const_evaluatable_unchecked): We
1181 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
1182 // with a future compat lint for now. We do this by adding an
1183 // additional special case for repeat expressions.
1185 // Note that we intentionally still forbid `[0; N + 1]` during
1186 // name resolution so that we don't extend the future
1187 // compat lint to new cases.
1188 fn with_constant_rib(
1190 is_repeat: IsRepeatExpr,
1192 item: Option<(Ident, ConstantItemKind)>,
1193 f: impl FnOnce(&mut Self),
1195 debug!("with_constant_rib: is_repeat={:?} is_trivial={}", is_repeat, is_trivial);
1196 self.with_rib(ValueNS, ConstantItemRibKind(is_trivial, item), |this| {
1199 ConstantItemRibKind(is_repeat == IsRepeatExpr::Yes || is_trivial, item),
1201 this.with_label_rib(ConstantItemRibKind(is_trivial, item), f);
1207 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
1208 // Handle nested impls (inside fn bodies)
1209 let previous_value =
1210 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
1211 let result = f(self);
1212 self.diagnostic_metadata.current_self_type = previous_value;
1216 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
1217 let previous_value =
1218 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
1219 let result = f(self);
1220 self.diagnostic_metadata.current_self_item = previous_value;
1224 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
1225 fn with_trait_items<T>(
1227 trait_items: &'ast [P<AssocItem>],
1228 f: impl FnOnce(&mut Self) -> T,
1230 let trait_assoc_items =
1231 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
1232 let result = f(self);
1233 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
1237 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
1238 fn with_optional_trait_ref<T>(
1240 opt_trait_ref: Option<&TraitRef>,
1241 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
1243 let mut new_val = None;
1244 let mut new_id = None;
1245 if let Some(trait_ref) = opt_trait_ref {
1246 let path: Vec<_> = Segment::from_path(&trait_ref.path);
1247 let res = self.smart_resolve_path_fragment(
1251 trait_ref.path.span,
1252 PathSource::Trait(AliasPossibility::No),
1253 CrateLint::SimplePath(trait_ref.ref_id),
1255 let res = res.base_res();
1256 if res != Res::Err {
1257 new_id = Some(res.def_id());
1258 let span = trait_ref.path.span;
1259 if let PathResult::Module(ModuleOrUniformRoot::Module(module)) = self.resolve_path(
1264 CrateLint::SimplePath(trait_ref.ref_id),
1266 new_val = Some((module, trait_ref.clone()));
1270 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1271 let result = f(self, new_id);
1272 self.current_trait_ref = original_trait_ref;
1276 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
1277 let binding = (self_res, ty::Visibility::Invisible, DUMMY_SP, self.parent_scope.expansion)
1278 .to_name_binding(self.r.arenas);
1279 let mut self_type_rib = Rib::new(NormalRibKind);
1281 // Plain insert (no renaming, since types are not currently hygienic)
1282 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), binding);
1283 self.ribs[ns].push(self_type_rib);
1285 self.ribs[ns].pop();
1288 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
1289 self.with_self_rib_ns(TypeNS, self_res, f)
1292 fn resolve_implementation(
1294 generics: &'ast Generics,
1295 opt_trait_reference: &'ast Option<TraitRef>,
1296 self_type: &'ast Ty,
1298 impl_items: &'ast [P<AssocItem>],
1300 debug!("resolve_implementation");
1301 // If applicable, create a rib for the type parameters.
1302 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1303 // Dummy self type for better errors if `Self` is used in the trait path.
1304 this.with_self_rib(Res::SelfTy(None, None), |this| {
1305 // Resolve the trait reference, if necessary.
1306 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1307 let item_def_id = this.r.local_def_id(item_id);
1309 // Register the trait definitions from here.
1310 if let Some(trait_id) = trait_id {
1311 this.r.trait_impls.entry(trait_id).or_default().push(item_def_id);
1314 let item_def_id = item_def_id.to_def_id();
1315 this.with_self_rib(Res::SelfTy(trait_id, Some((item_def_id, false))), |this| {
1316 if let Some(trait_ref) = opt_trait_reference.as_ref() {
1317 // Resolve type arguments in the trait path.
1318 visit::walk_trait_ref(this, trait_ref);
1320 // Resolve the self type.
1321 this.visit_ty(self_type);
1322 // Resolve the generic parameters.
1323 this.visit_generics(generics);
1324 // Resolve the items within the impl.
1325 this.with_current_self_type(self_type, |this| {
1326 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
1327 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
1328 for item in impl_items {
1329 use crate::ResolutionError::*;
1331 AssocItemKind::Const(_default, _ty, _expr) => {
1332 debug!("resolve_implementation AssocItemKind::Const");
1333 // If this is a trait impl, ensure the const
1335 this.check_trait_item(
1340 |i, s, c| ConstNotMemberOfTrait(i, s, c),
1343 // We allow arbitrary const expressions inside of associated consts,
1344 // even if they are potentially not const evaluatable.
1346 // Type parameters can already be used and as associated consts are
1347 // not used as part of the type system, this is far less surprising.
1348 this.with_constant_rib(
1353 visit::walk_assoc_item(
1361 AssocItemKind::Fn(box FnKind(.., generics, _)) => {
1362 debug!("resolve_implementation AssocItemKind::Fn");
1363 // We also need a new scope for the impl item type parameters.
1364 this.with_generic_param_rib(
1368 // If this is a trait impl, ensure the method
1370 this.check_trait_item(
1375 |i, s, c| MethodNotMemberOfTrait(i, s, c),
1378 visit::walk_assoc_item(
1386 AssocItemKind::TyAlias(box TyAliasKind(
1392 debug!("resolve_implementation AssocItemKind::TyAlias");
1393 // We also need a new scope for the impl item type parameters.
1394 this.with_generic_param_rib(
1398 // If this is a trait impl, ensure the type
1400 this.check_trait_item(
1405 |i, s, c| TypeNotMemberOfTrait(i, s, c),
1408 visit::walk_assoc_item(
1416 AssocItemKind::MacCall(_) => {
1417 panic!("unexpanded macro in resolve!")
1429 fn check_trait_item<F>(
1432 kind: &AssocItemKind,
1437 F: FnOnce(Ident, &str, Option<Symbol>) -> ResolutionError<'_>,
1439 // If there is a TraitRef in scope for an impl, then the method must be in the
1441 if let Some((module, _)) = self.current_trait_ref {
1444 .resolve_ident_in_module(
1445 ModuleOrUniformRoot::Module(module),
1454 let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
1455 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
1456 self.report_error(span, err(ident, &path_names_to_string(path), candidate));
1461 fn resolve_params(&mut self, params: &'ast [Param]) {
1462 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1463 for Param { pat, ty, .. } in params {
1464 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1466 debug!("(resolving function / closure) recorded parameter");
1470 fn resolve_local(&mut self, local: &'ast Local) {
1471 debug!("resolving local ({:?})", local);
1472 // Resolve the type.
1473 walk_list!(self, visit_ty, &local.ty);
1475 // Resolve the initializer.
1476 if let Some((init, els)) = local.kind.init_else_opt() {
1477 self.visit_expr(init);
1479 // Resolve the `else` block
1480 if let Some(els) = els {
1481 self.visit_block(els);
1485 // Resolve the pattern.
1486 self.resolve_pattern_top(&local.pat, PatternSource::Let);
1489 /// build a map from pattern identifiers to binding-info's.
1490 /// this is done hygienically. This could arise for a macro
1491 /// that expands into an or-pattern where one 'x' was from the
1492 /// user and one 'x' came from the macro.
1493 fn binding_mode_map(&mut self, pat: &Pat) -> FxHashMap<Ident, BindingInfo> {
1494 let mut binding_map = FxHashMap::default();
1496 pat.walk(&mut |pat| {
1498 PatKind::Ident(binding_mode, ident, ref sub_pat)
1499 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
1501 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
1503 PatKind::Or(ref ps) => {
1504 // Check the consistency of this or-pattern and
1505 // then add all bindings to the larger map.
1506 for bm in self.check_consistent_bindings(ps) {
1507 binding_map.extend(bm);
1520 fn is_base_res_local(&self, nid: NodeId) -> bool {
1521 matches!(self.r.partial_res_map.get(&nid).map(|res| res.base_res()), Some(Res::Local(..)))
1524 /// Checks that all of the arms in an or-pattern have exactly the
1525 /// same set of bindings, with the same binding modes for each.
1526 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<FxHashMap<Ident, BindingInfo>> {
1527 let mut missing_vars = FxHashMap::default();
1528 let mut inconsistent_vars = FxHashMap::default();
1530 // 1) Compute the binding maps of all arms.
1531 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
1533 // 2) Record any missing bindings or binding mode inconsistencies.
1534 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
1535 // Check against all arms except for the same pattern which is always self-consistent.
1539 .filter(|(_, pat)| pat.id != pat_outer.id)
1540 .flat_map(|(idx, _)| maps[idx].iter())
1541 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
1543 for (name, info, &binding_inner) in inners {
1546 // The inner binding is missing in the outer.
1548 missing_vars.entry(name).or_insert_with(|| BindingError {
1550 origin: BTreeSet::new(),
1551 target: BTreeSet::new(),
1552 could_be_path: name.as_str().starts_with(char::is_uppercase),
1554 binding_error.origin.insert(binding_inner.span);
1555 binding_error.target.insert(pat_outer.span);
1557 Some(binding_outer) => {
1558 if binding_outer.binding_mode != binding_inner.binding_mode {
1559 // The binding modes in the outer and inner bindings differ.
1562 .or_insert((binding_inner.span, binding_outer.span));
1569 // 3) Report all missing variables we found.
1570 let mut missing_vars = missing_vars.iter_mut().collect::<Vec<_>>();
1571 missing_vars.sort_by_key(|(sym, _err)| sym.as_str());
1573 for (name, mut v) in missing_vars {
1574 if inconsistent_vars.contains_key(name) {
1575 v.could_be_path = false;
1578 *v.origin.iter().next().unwrap(),
1579 ResolutionError::VariableNotBoundInPattern(v),
1583 // 4) Report all inconsistencies in binding modes we found.
1584 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
1585 inconsistent_vars.sort();
1586 for (name, v) in inconsistent_vars {
1587 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
1590 // 5) Finally bubble up all the binding maps.
1594 /// Check the consistency of the outermost or-patterns.
1595 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
1596 pat.walk(&mut |pat| match pat.kind {
1597 PatKind::Or(ref ps) => {
1598 self.check_consistent_bindings(ps);
1605 fn resolve_arm(&mut self, arm: &'ast Arm) {
1606 self.with_rib(ValueNS, NormalRibKind, |this| {
1607 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
1608 walk_list!(this, visit_expr, &arm.guard);
1609 this.visit_expr(&arm.body);
1613 /// Arising from `source`, resolve a top level pattern.
1614 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
1615 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1616 self.resolve_pattern(pat, pat_src, &mut bindings);
1622 pat_src: PatternSource,
1623 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1625 self.resolve_pattern_inner(pat, pat_src, bindings);
1626 // This has to happen *after* we determine which pat_idents are variants:
1627 self.check_consistent_bindings_top(pat);
1628 visit::walk_pat(self, pat);
1631 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
1635 /// A stack of sets of bindings accumulated.
1637 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
1638 /// be interpreted as re-binding an already bound binding. This results in an error.
1639 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
1640 /// in reusing this binding rather than creating a fresh one.
1642 /// When called at the top level, the stack must have a single element
1643 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
1644 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
1645 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
1646 /// When each `p_i` has been dealt with, the top set is merged with its parent.
1647 /// When a whole or-pattern has been dealt with, the thing happens.
1649 /// See the implementation and `fresh_binding` for more details.
1650 fn resolve_pattern_inner(
1653 pat_src: PatternSource,
1654 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1656 // Visit all direct subpatterns of this pattern.
1657 pat.walk(&mut |pat| {
1658 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
1660 PatKind::Ident(bmode, ident, ref sub) => {
1661 // First try to resolve the identifier as some existing entity,
1662 // then fall back to a fresh binding.
1663 let has_sub = sub.is_some();
1665 .try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub)
1666 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
1667 self.r.record_partial_res(pat.id, PartialRes::new(res));
1669 PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
1670 self.smart_resolve_path(
1674 PathSource::TupleStruct(
1676 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
1680 PatKind::Path(ref qself, ref path) => {
1681 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
1683 PatKind::Struct(ref qself, ref path, ..) => {
1684 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Struct);
1686 PatKind::Or(ref ps) => {
1687 // Add a new set of bindings to the stack. `Or` here records that when a
1688 // binding already exists in this set, it should not result in an error because
1689 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
1690 bindings.push((PatBoundCtx::Or, Default::default()));
1692 // Now we need to switch back to a product context so that each
1693 // part of the or-pattern internally rejects already bound names.
1694 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
1695 bindings.push((PatBoundCtx::Product, Default::default()));
1696 self.resolve_pattern_inner(p, pat_src, bindings);
1697 // Move up the non-overlapping bindings to the or-pattern.
1698 // Existing bindings just get "merged".
1699 let collected = bindings.pop().unwrap().1;
1700 bindings.last_mut().unwrap().1.extend(collected);
1702 // This or-pattern itself can itself be part of a product,
1703 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
1704 // Both cases bind `a` again in a product pattern and must be rejected.
1705 let collected = bindings.pop().unwrap().1;
1706 bindings.last_mut().unwrap().1.extend(collected);
1708 // Prevent visiting `ps` as we've already done so above.
1721 pat_src: PatternSource,
1722 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1724 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
1725 // (We must not add it if it's in the bindings map because that breaks the assumptions
1726 // later passes make about or-patterns.)
1727 let ident = ident.normalize_to_macro_rules();
1729 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
1730 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
1731 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
1732 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
1733 // This is *required* for consistency which is checked later.
1734 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
1736 if already_bound_and {
1737 // Overlap in a product pattern somewhere; report an error.
1738 use ResolutionError::*;
1739 let error = match pat_src {
1740 // `fn f(a: u8, a: u8)`:
1741 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
1743 _ => IdentifierBoundMoreThanOnceInSamePattern,
1745 self.report_error(ident.span, error(ident.name));
1748 // Record as bound if it's valid:
1749 let ident_valid = ident.name != kw::Empty;
1751 bindings.last_mut().unwrap().1.insert(ident);
1754 if already_bound_or {
1755 // `Variant1(a) | Variant2(a)`, ok
1756 // Reuse definition from the first `a`.
1757 self.innermost_rib_bindings(ValueNS)[&ident].res()
1759 let res = Res::Local(pat_id);
1761 // A completely fresh binding add to the set if it's valid.
1763 (res, ty::Visibility::Invisible, ident.span, self.parent_scope.expansion)
1764 .to_name_binding(self.r.arenas);
1765 self.innermost_rib_bindings(ValueNS).insert(ident, binding);
1771 fn innermost_rib_bindings(
1774 ) -> &mut FxHashMap<Ident, &'a NameBinding<'a>> {
1775 &mut self.ribs[ns].last_mut().unwrap().bindings
1778 fn try_resolve_as_non_binding(
1780 pat_src: PatternSource,
1786 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
1787 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
1788 // also be interpreted as a path to e.g. a constant, variant, etc.
1789 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
1791 let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, pat.span)?;
1792 if is_syntactic_ambiguity && binding.is_ambiguity() {
1793 // For ambiguous bindings we don't know all their definitions and cannot check
1794 // whether they can be shadowed by fresh bindings or not, so force an error.
1795 // issues/33118#issuecomment-233962221 (see below) still applies here,
1796 // but we have to ignore it for backward compatibility.
1797 self.r.record_use(ident, binding, false);
1801 let res = binding.res();
1803 Res::SelfCtor(_) // See #70549.
1805 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
1807 ) if is_syntactic_ambiguity => {
1808 // Disambiguate in favor of a unit struct/variant or constant pattern.
1809 self.r.record_use(ident, binding, false);
1812 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static, _) => {
1813 // This is unambiguously a fresh binding, either syntactically
1814 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
1815 // to something unusable as a pattern (e.g., constructor function),
1816 // but we still conservatively report an error, see
1817 // issues/33118#issuecomment-233962221 for one reason why.
1820 ResolutionError::BindingShadowsSomethingUnacceptable {
1821 shadowing_binding_descr: pat_src.descr(),
1823 participle: if binding.is_import() { "imported" } else { "defined" },
1824 article: binding.res().article(),
1825 shadowed_binding_descr: binding.res().descr(),
1826 shadowed_binding_span: binding.span,
1831 Res::Def(DefKind::ConstParam, def_id) => {
1832 // Same as for DefKind::Const above, but here, `binding` is `None`, so we
1833 // have to construct the error differently
1836 ResolutionError::BindingShadowsSomethingUnacceptable {
1837 shadowing_binding_descr: pat_src.descr(),
1839 participle: "defined",
1840 article: res.article(),
1841 shadowed_binding_descr: res.descr(),
1842 shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"),
1847 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
1848 // These entities are explicitly allowed to be shadowed by fresh bindings.
1853 "unexpected resolution for an identifier in pattern: {:?}",
1859 // High-level and context dependent path resolution routine.
1860 // Resolves the path and records the resolution into definition map.
1861 // If resolution fails tries several techniques to find likely
1862 // resolution candidates, suggest imports or other help, and report
1863 // errors in user friendly way.
1864 fn smart_resolve_path(
1867 qself: Option<&QSelf>,
1869 source: PathSource<'ast>,
1871 self.smart_resolve_path_fragment(
1874 &Segment::from_path(path),
1877 CrateLint::SimplePath(id),
1881 fn smart_resolve_path_fragment(
1884 qself: Option<&QSelf>,
1887 source: PathSource<'ast>,
1888 crate_lint: CrateLint,
1891 "smart_resolve_path_fragment(id={:?}, qself={:?}, path={:?})",
1896 let ns = source.namespace();
1898 let report_errors = |this: &mut Self, res: Option<Res>| {
1899 if this.should_report_errs() {
1900 let (err, candidates) = this.smart_resolve_report_errors(path, span, source, res);
1902 let def_id = this.parent_scope.module.nearest_parent_mod();
1903 let instead = res.is_some();
1905 if res.is_none() { this.report_missing_type_error(path) } else { None };
1908 this.r.use_injections.push(UseError {
1917 PartialRes::new(Res::Err)
1920 // For paths originating from calls (like in `HashMap::new()`), tries
1921 // to enrich the plain `failed to resolve: ...` message with hints
1922 // about possible missing imports.
1924 // Similar thing, for types, happens in `report_errors` above.
1925 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
1926 if !source.is_call() {
1927 return Some(parent_err);
1930 // Before we start looking for candidates, we have to get our hands
1931 // on the type user is trying to perform invocation on; basically:
1932 // we're transforming `HashMap::new` into just `HashMap`.
1933 let path = match path.split_last() {
1934 Some((_, path)) if !path.is_empty() => path,
1935 _ => return Some(parent_err),
1938 let (mut err, candidates) =
1939 this.smart_resolve_report_errors(path, span, PathSource::Type, None);
1941 if candidates.is_empty() {
1943 return Some(parent_err);
1946 // There are two different error messages user might receive at
1948 // - E0412 cannot find type `{}` in this scope
1949 // - E0433 failed to resolve: use of undeclared type or module `{}`
1951 // The first one is emitted for paths in type-position, and the
1952 // latter one - for paths in expression-position.
1954 // Thus (since we're in expression-position at this point), not to
1955 // confuse the user, we want to keep the *message* from E0432 (so
1956 // `parent_err`), but we want *hints* from E0412 (so `err`).
1958 // And that's what happens below - we're just mixing both messages
1959 // into a single one.
1960 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
1962 parent_err.cancel();
1964 err.message = take(&mut parent_err.message);
1965 err.code = take(&mut parent_err.code);
1966 err.children = take(&mut parent_err.children);
1970 let def_id = this.parent_scope.module.nearest_parent_mod();
1972 if this.should_report_errs() {
1973 this.r.use_injections.push(UseError {
1984 // We don't return `Some(parent_err)` here, because the error will
1985 // be already printed as part of the `use` injections
1989 let partial_res = match self.resolve_qpath_anywhere(
1995 source.defer_to_typeck(),
1998 Ok(Some(partial_res)) if partial_res.unresolved_segments() == 0 => {
1999 if source.is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err
2003 report_errors(self, Some(partial_res.base_res()))
2007 Ok(Some(partial_res)) if source.defer_to_typeck() => {
2008 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
2009 // or `<T>::A::B`. If `B` should be resolved in value namespace then
2010 // it needs to be added to the trait map.
2012 let item_name = path.last().unwrap().ident;
2013 let traits = self.traits_in_scope(item_name, ns);
2014 self.r.trait_map.insert(id, traits);
2017 if PrimTy::from_name(path[0].ident.name).is_some() {
2018 let mut std_path = Vec::with_capacity(1 + path.len());
2020 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
2021 std_path.extend(path);
2022 if let PathResult::Module(_) | PathResult::NonModule(_) =
2023 self.resolve_path(&std_path, Some(ns), false, span, CrateLint::No)
2025 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
2027 path.iter().last().map_or(span, |segment| segment.ident.span);
2029 self.r.confused_type_with_std_module.insert(item_span, span);
2030 self.r.confused_type_with_std_module.insert(span, span);
2038 if let Some(err) = report_errors_for_call(self, err) {
2039 self.report_error(err.span, err.node);
2042 PartialRes::new(Res::Err)
2045 _ => report_errors(self, None),
2048 if !matches!(source, PathSource::TraitItem(..)) {
2049 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
2050 self.r.record_partial_res(id, partial_res);
2056 fn self_type_is_available(&mut self, span: Span) -> bool {
2057 let ident = Ident::with_dummy_span(kw::SelfUpper);
2058 self.resolve_ident_in_lexical_scope(ident, TypeNS, None, span)
2059 .map_or(false, |binding| binding.res() != Res::Err)
2062 fn self_value_is_available(&mut self, self_span: Span, path_span: Span) -> bool {
2063 let ident = Ident::new(kw::SelfLower, self_span);
2064 self.resolve_ident_in_lexical_scope(ident, ValueNS, None, path_span)
2065 .map_or(false, |binding| binding.res() != Res::Err)
2068 /// A wrapper around [`Resolver::report_error`].
2070 /// This doesn't emit errors for function bodies if this is rustdoc.
2071 fn report_error(&self, span: Span, resolution_error: ResolutionError<'_>) {
2072 if self.should_report_errs() {
2073 self.r.report_error(span, resolution_error);
2078 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
2079 fn should_report_errs(&self) -> bool {
2080 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
2083 // Resolve in alternative namespaces if resolution in the primary namespace fails.
2084 fn resolve_qpath_anywhere(
2087 qself: Option<&QSelf>,
2089 primary_ns: Namespace,
2091 defer_to_typeck: bool,
2092 crate_lint: CrateLint,
2093 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2094 let mut fin_res = None;
2096 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
2097 if i == 0 || ns != primary_ns {
2098 match self.resolve_qpath(id, qself, path, ns, span, crate_lint)? {
2100 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
2102 return Ok(Some(partial_res));
2105 if fin_res.is_none() {
2106 fin_res = partial_res;
2113 assert!(primary_ns != MacroNS);
2115 if qself.is_none() {
2116 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
2117 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
2118 if let Ok((_, res)) =
2119 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
2121 return Ok(Some(PartialRes::new(res)));
2128 /// Handles paths that may refer to associated items.
2132 qself: Option<&QSelf>,
2136 crate_lint: CrateLint,
2137 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2139 "resolve_qpath(id={:?}, qself={:?}, path={:?}, ns={:?}, span={:?})",
2140 id, qself, path, ns, span,
2143 if let Some(qself) = qself {
2144 if qself.position == 0 {
2145 // This is a case like `<T>::B`, where there is no
2146 // trait to resolve. In that case, we leave the `B`
2147 // segment to be resolved by type-check.
2148 return Ok(Some(PartialRes::with_unresolved_segments(
2149 Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX)),
2154 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
2156 // Currently, `path` names the full item (`A::B::C`, in
2157 // our example). so we extract the prefix of that that is
2158 // the trait (the slice upto and including
2159 // `qself.position`). And then we recursively resolve that,
2160 // but with `qself` set to `None`.
2162 // However, setting `qself` to none (but not changing the
2163 // span) loses the information about where this path
2164 // *actually* appears, so for the purposes of the crate
2165 // lint we pass along information that this is the trait
2166 // name from a fully qualified path, and this also
2167 // contains the full span (the `CrateLint::QPathTrait`).
2168 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2169 let partial_res = self.smart_resolve_path_fragment(
2172 &path[..=qself.position],
2174 PathSource::TraitItem(ns),
2175 CrateLint::QPathTrait { qpath_id: id, qpath_span: qself.path_span },
2178 // The remaining segments (the `C` in our example) will
2179 // have to be resolved by type-check, since that requires doing
2180 // trait resolution.
2181 return Ok(Some(PartialRes::with_unresolved_segments(
2182 partial_res.base_res(),
2183 partial_res.unresolved_segments() + path.len() - qself.position - 1,
2187 let result = match self.resolve_path(&path, Some(ns), true, span, crate_lint) {
2188 PathResult::NonModule(path_res) => path_res,
2189 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
2190 PartialRes::new(module.res().unwrap())
2192 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2193 // don't report an error right away, but try to fallback to a primitive type.
2194 // So, we are still able to successfully resolve something like
2196 // use std::u8; // bring module u8 in scope
2197 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2198 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
2199 // // not to non-existent std::u8::max_value
2202 // Such behavior is required for backward compatibility.
2203 // The same fallback is used when `a` resolves to nothing.
2204 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
2205 if (ns == TypeNS || path.len() > 1)
2206 && PrimTy::from_name(path[0].ident.name).is_some() =>
2208 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
2209 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
2211 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2212 PartialRes::new(module.res().unwrap())
2214 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
2215 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
2217 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
2218 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
2222 && result.base_res() != Res::Err
2223 && path[0].ident.name != kw::PathRoot
2224 && path[0].ident.name != kw::DollarCrate
2226 let unqualified_result = {
2227 match self.resolve_path(
2228 &[*path.last().unwrap()],
2234 PathResult::NonModule(path_res) => path_res.base_res(),
2235 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2236 module.res().unwrap()
2238 _ => return Ok(Some(result)),
2241 if result.base_res() == unqualified_result {
2242 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
2243 self.r.lint_buffer.buffer_lint(lint, id, span, "unnecessary qualification")
2250 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
2251 if let Some(label) = label {
2252 if label.ident.as_str().as_bytes()[1] != b'_' {
2253 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
2255 self.with_label_rib(NormalRibKind, |this| {
2256 let ident = label.ident.normalize_to_macro_rules();
2257 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
2265 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
2266 self.with_resolved_label(label, id, |this| this.visit_block(block));
2269 fn resolve_block(&mut self, block: &'ast Block) {
2270 debug!("(resolving block) entering block");
2271 // Move down in the graph, if there's an anonymous module rooted here.
2272 let orig_module = self.parent_scope.module;
2273 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
2275 let mut num_macro_definition_ribs = 0;
2276 if let Some(anonymous_module) = anonymous_module {
2277 debug!("(resolving block) found anonymous module, moving down");
2278 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2279 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2280 self.parent_scope.module = anonymous_module;
2282 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2285 let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
2286 if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
2287 (block.could_be_bare_literal, &block.stmts[..])
2289 if let ExprKind::Type(..) = expr.kind {
2290 self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
2294 // Descend into the block.
2295 for stmt in &block.stmts {
2296 if let StmtKind::Item(ref item) = stmt.kind {
2297 if let ItemKind::MacroDef(..) = item.kind {
2298 num_macro_definition_ribs += 1;
2299 let res = self.r.local_def_id(item.id).to_def_id();
2300 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
2301 self.label_ribs.push(Rib::new(MacroDefinition(res)));
2305 self.visit_stmt(stmt);
2307 self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
2310 self.parent_scope.module = orig_module;
2311 for _ in 0..num_macro_definition_ribs {
2312 self.ribs[ValueNS].pop();
2313 self.label_ribs.pop();
2315 self.ribs[ValueNS].pop();
2316 if anonymous_module.is_some() {
2317 self.ribs[TypeNS].pop();
2319 debug!("(resolving block) leaving block");
2322 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
2323 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
2324 self.with_constant_rib(
2326 constant.value.is_potential_trivial_const_param(),
2329 visit::walk_anon_const(this, constant);
2334 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
2335 // First, record candidate traits for this expression if it could
2336 // result in the invocation of a method call.
2338 self.record_candidate_traits_for_expr_if_necessary(expr);
2340 // Next, resolve the node.
2342 ExprKind::Path(ref qself, ref path) => {
2343 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
2344 visit::walk_expr(self, expr);
2347 ExprKind::Struct(ref se) => {
2348 self.smart_resolve_path(expr.id, se.qself.as_ref(), &se.path, PathSource::Struct);
2349 visit::walk_expr(self, expr);
2352 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
2353 if let Some(node_id) = self.resolve_label(label.ident) {
2354 // Since this res is a label, it is never read.
2355 self.r.label_res_map.insert(expr.id, node_id);
2356 self.diagnostic_metadata.unused_labels.remove(&node_id);
2359 // visit `break` argument if any
2360 visit::walk_expr(self, expr);
2363 ExprKind::Break(None, Some(ref e)) => {
2364 // We use this instead of `visit::walk_expr` to keep the parent expr around for
2365 // better diagnostics.
2366 self.resolve_expr(e, Some(&expr));
2369 ExprKind::Let(ref pat, ref scrutinee, _) => {
2370 self.visit_expr(scrutinee);
2371 self.resolve_pattern_top(pat, PatternSource::Let);
2374 ExprKind::If(ref cond, ref then, ref opt_else) => {
2375 self.with_rib(ValueNS, NormalRibKind, |this| {
2376 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
2377 this.visit_expr(cond);
2378 this.diagnostic_metadata.in_if_condition = old;
2379 this.visit_block(then);
2381 if let Some(expr) = opt_else {
2382 self.visit_expr(expr);
2386 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
2388 ExprKind::While(ref cond, ref block, label) => {
2389 self.with_resolved_label(label, expr.id, |this| {
2390 this.with_rib(ValueNS, NormalRibKind, |this| {
2391 this.visit_expr(cond);
2392 this.visit_block(block);
2397 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
2398 self.visit_expr(iter_expr);
2399 self.with_rib(ValueNS, NormalRibKind, |this| {
2400 this.resolve_pattern_top(pat, PatternSource::For);
2401 this.resolve_labeled_block(label, expr.id, block);
2405 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
2407 // Equivalent to `visit::walk_expr` + passing some context to children.
2408 ExprKind::Field(ref subexpression, _) => {
2409 self.resolve_expr(subexpression, Some(expr));
2411 ExprKind::MethodCall(ref segment, ref arguments, _) => {
2412 let mut arguments = arguments.iter();
2413 self.resolve_expr(arguments.next().unwrap(), Some(expr));
2414 for argument in arguments {
2415 self.resolve_expr(argument, None);
2417 self.visit_path_segment(expr.span, segment);
2420 ExprKind::Call(ref callee, ref arguments) => {
2421 self.resolve_expr(callee, Some(expr));
2422 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
2423 for (idx, argument) in arguments.iter().enumerate() {
2424 // Constant arguments need to be treated as AnonConst since
2425 // that is how they will be later lowered to HIR.
2426 if const_args.contains(&idx) {
2427 self.with_constant_rib(
2429 argument.is_potential_trivial_const_param(),
2432 this.resolve_expr(argument, None);
2436 self.resolve_expr(argument, None);
2440 ExprKind::Type(ref type_expr, ref ty) => {
2441 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
2442 // type ascription. Here we are trying to retrieve the span of the colon token as
2443 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
2444 // with `expr::Ty`, only in this case it will match the span from
2445 // `type_ascription_path_suggestions`.
2446 self.diagnostic_metadata
2447 .current_type_ascription
2448 .push(type_expr.span.between(ty.span));
2449 visit::walk_expr(self, expr);
2450 self.diagnostic_metadata.current_type_ascription.pop();
2452 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
2453 // resolve the arguments within the proper scopes so that usages of them inside the
2454 // closure are detected as upvars rather than normal closure arg usages.
2455 ExprKind::Closure(_, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
2456 self.with_rib(ValueNS, NormalRibKind, |this| {
2457 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
2458 // Resolve arguments:
2459 this.resolve_params(&fn_decl.inputs);
2460 // No need to resolve return type --
2461 // the outer closure return type is `FnRetTy::Default`.
2463 // Now resolve the inner closure
2465 // No need to resolve arguments: the inner closure has none.
2466 // Resolve the return type:
2467 visit::walk_fn_ret_ty(this, &fn_decl.output);
2469 this.visit_expr(body);
2474 ExprKind::Async(..) | ExprKind::Closure(..) => {
2475 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
2477 ExprKind::Repeat(ref elem, ref ct) => {
2478 self.visit_expr(elem);
2479 self.resolve_anon_const(ct, IsRepeatExpr::Yes);
2482 visit::walk_expr(self, expr);
2487 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
2489 ExprKind::Field(_, ident) => {
2490 // FIXME(#6890): Even though you can't treat a method like a
2491 // field, we need to add any trait methods we find that match
2492 // the field name so that we can do some nice error reporting
2493 // later on in typeck.
2494 let traits = self.traits_in_scope(ident, ValueNS);
2495 self.r.trait_map.insert(expr.id, traits);
2497 ExprKind::MethodCall(ref segment, ..) => {
2498 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
2499 let traits = self.traits_in_scope(segment.ident, ValueNS);
2500 self.r.trait_map.insert(expr.id, traits);
2508 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
2509 self.r.traits_in_scope(
2510 self.current_trait_ref.as_ref().map(|(module, _)| *module),
2513 Some((ident.name, ns)),
2517 fn compute_num_lifetime_params(&mut self, id: NodeId, generics: &Generics) {
2518 let def_id = self.r.local_def_id(id);
2519 let count = generics
2522 .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
2524 self.r.item_generics_num_lifetimes.insert(def_id, count);
2528 impl<'a> Resolver<'a> {
2529 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
2530 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
2531 visit::walk_crate(&mut late_resolution_visitor, krate);
2532 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
2533 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");