1 //! "Late resolution" is the pass that resolves most of names in a crate beside imports and macros.
2 //! It runs when the crate is fully expanded and its module structure is fully built.
3 //! So it just walks through the crate and resolves all the expressions, types, etc.
5 //! If you wonder why there's no `early.rs`, that's because it's split into three files -
6 //! `build_reduced_graph.rs`, `macros.rs` and `imports.rs`.
10 use crate::{path_names_to_string, BindingError, CrateLint, LexicalScopeBinding};
11 use crate::{Module, ModuleOrUniformRoot, 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::{unwrap_or, walk_list};
18 use rustc_ast_lowering::ResolverAstLowering;
19 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
20 use rustc_errors::DiagnosticId;
21 use rustc_hir::def::Namespace::{self, *};
22 use rustc_hir::def::{self, CtorKind, DefKind, PartialRes, PerNS};
23 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
24 use rustc_hir::TraitCandidate;
25 use rustc_middle::{bug, span_bug};
26 use rustc_session::lint;
27 use rustc_span::symbol::{kw, sym, Ident, Symbol};
29 use smallvec::{smallvec, SmallVec};
31 use rustc_span::source_map::{respan, Spanned};
32 use std::collections::BTreeSet;
33 use std::mem::{replace, take};
39 type Res = def::Res<NodeId>;
41 type IdentMap<T> = FxHashMap<Ident, T>;
43 /// Map from the name in a pattern to its binding mode.
44 type BindingMap = IdentMap<BindingInfo>;
46 #[derive(Copy, Clone, Debug)]
49 binding_mode: BindingMode,
52 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
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 /// The rib kind restricts certain accesses,
90 /// e.g. to a `Res::Local` of an outer item.
91 #[derive(Copy, Clone, Debug)]
92 crate enum RibKind<'a> {
93 /// No restriction needs to be applied.
96 /// We passed through an impl or trait and are now in one of its
97 /// methods or associated types. Allow references to ty params that impl or trait
98 /// binds. Disallow any other upvars (including other ty params that are
102 /// We passed through a closure. Disallow labels.
103 ClosureOrAsyncRibKind,
105 /// We passed through a function definition. Disallow upvars.
106 /// Permit only those const parameters that are specified in the function's generics.
109 /// We passed through an item scope. Disallow upvars.
110 ItemRibKind(HasGenericParams),
112 /// We're in a constant item. Can't refer to dynamic stuff.
114 /// The `bool` indicates if this constant may reference generic parameters
115 /// and is used to only allow generic parameters to be used in trivial constant expressions.
116 ConstantItemRibKind(bool),
118 /// We passed through a module.
119 ModuleRibKind(Module<'a>),
121 /// We passed through a `macro_rules!` statement
122 MacroDefinition(DefId),
124 /// All bindings in this rib are type parameters that can't be used
125 /// from the default of a type parameter because they're not declared
126 /// before said type parameter. Also see the `visit_generics` override.
127 ForwardTyParamBanRibKind,
129 /// We are inside of the type of a const parameter. Can't refer to any
135 /// Whether this rib kind contains generic parameters, as opposed to local
137 crate fn contains_params(&self) -> bool {
140 | ClosureOrAsyncRibKind
142 | ConstantItemRibKind(_)
145 | ConstParamTyRibKind => false,
146 AssocItemRibKind | ItemRibKind(_) | ForwardTyParamBanRibKind => true,
151 /// A single local scope.
153 /// A rib represents a scope names can live in. Note that these appear in many places, not just
154 /// around braces. At any place where the list of accessible names (of the given namespace)
155 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
156 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
159 /// Different [rib kinds](enum.RibKind) are transparent for different names.
161 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
162 /// resolving, the name is looked up from inside out.
164 crate struct Rib<'a, R = Res> {
165 pub bindings: IdentMap<R>,
166 pub kind: RibKind<'a>,
169 impl<'a, R> Rib<'a, R> {
170 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
171 Rib { bindings: Default::default(), kind }
175 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
176 crate enum AliasPossibility {
181 #[derive(Copy, Clone, Debug)]
182 crate enum PathSource<'a> {
183 // Type paths `Path`.
185 // Trait paths in bounds or impls.
186 Trait(AliasPossibility),
187 // Expression paths `path`, with optional parent context.
188 Expr(Option<&'a Expr>),
189 // Paths in path patterns `Path`.
191 // Paths in struct expressions and patterns `Path { .. }`.
193 // Paths in tuple struct patterns `Path(..)`.
194 TupleStruct(Span, &'a [Span]),
195 // `m::A::B` in `<T as m::A>::B::C`.
196 TraitItem(Namespace),
199 impl<'a> PathSource<'a> {
200 fn namespace(self) -> Namespace {
202 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
203 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
204 PathSource::TraitItem(ns) => ns,
208 fn defer_to_typeck(self) -> bool {
211 | PathSource::Expr(..)
214 | PathSource::TupleStruct(..) => true,
215 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
219 fn descr_expected(self) -> &'static str {
221 PathSource::Type => "type",
222 PathSource::Trait(_) => "trait",
223 PathSource::Pat => "unit struct, unit variant or constant",
224 PathSource::Struct => "struct, variant or union type",
225 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
226 PathSource::TraitItem(ns) => match ns {
227 TypeNS => "associated type",
228 ValueNS => "method or associated constant",
229 MacroNS => bug!("associated macro"),
231 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
232 // "function" here means "anything callable" rather than `DefKind::Fn`,
233 // this is not precise but usually more helpful than just "value".
234 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
235 ExprKind::Path(_, path) => {
236 let mut msg = "function";
237 if let Some(segment) = path.segments.iter().last() {
238 if let Some(c) = segment.ident.to_string().chars().next() {
239 if c.is_uppercase() {
240 msg = "function, tuple struct or tuple variant";
253 fn is_call(self) -> bool {
255 PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })) => true,
260 crate fn is_expected(self, res: Res) -> bool {
262 PathSource::Type => match res {
268 | DefKind::TraitAlias
273 | DefKind::ForeignTy,
277 | Res::SelfTy(..) => true,
280 PathSource::Trait(AliasPossibility::No) => match res {
281 Res::Def(DefKind::Trait, _) => true,
284 PathSource::Trait(AliasPossibility::Maybe) => match res {
285 Res::Def(DefKind::Trait | DefKind::TraitAlias, _) => true,
288 PathSource::Expr(..) => match res {
290 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
295 | DefKind::AssocConst
296 | DefKind::ConstParam,
300 | Res::SelfCtor(..) => true,
303 PathSource::Pat => match res {
305 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::AssocConst,
308 | Res::SelfCtor(..) => true,
311 PathSource::TupleStruct(..) => match res {
312 Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) | Res::SelfCtor(..) => true,
315 PathSource::Struct => match res {
324 | Res::SelfTy(..) => true,
327 PathSource::TraitItem(ns) => match res {
328 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
329 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
335 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
336 use rustc_errors::error_code;
337 match (self, has_unexpected_resolution) {
338 (PathSource::Trait(_), true) => error_code!(E0404),
339 (PathSource::Trait(_), false) => error_code!(E0405),
340 (PathSource::Type, true) => error_code!(E0573),
341 (PathSource::Type, false) => error_code!(E0412),
342 (PathSource::Struct, true) => error_code!(E0574),
343 (PathSource::Struct, false) => error_code!(E0422),
344 (PathSource::Expr(..), true) => error_code!(E0423),
345 (PathSource::Expr(..), false) => error_code!(E0425),
346 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
347 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
348 (PathSource::TraitItem(..), true) => error_code!(E0575),
349 (PathSource::TraitItem(..), false) => error_code!(E0576),
355 struct DiagnosticMetadata<'ast> {
356 /// The current trait's associated types' ident, used for diagnostic suggestions.
357 current_trait_assoc_types: Vec<Ident>,
359 /// The current self type if inside an impl (used for better errors).
360 current_self_type: Option<Ty>,
362 /// The current self item if inside an ADT (used for better errors).
363 current_self_item: Option<NodeId>,
365 /// The current trait (used to suggest).
366 current_item: Option<&'ast Item>,
368 /// When processing generics and encountering a type not found, suggest introducing a type
370 currently_processing_generics: bool,
372 /// The current enclosing (non-closure) function (used for better errors).
373 current_function: Option<(FnKind<'ast>, Span)>,
375 /// A list of labels as of yet unused. Labels will be removed from this map when
376 /// they are used (in a `break` or `continue` statement)
377 unused_labels: FxHashMap<NodeId, Span>,
379 /// Only used for better errors on `fn(): fn()`.
380 current_type_ascription: Vec<Span>,
382 /// Only used for better errors on `let <pat>: <expr, not type>;`.
383 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
385 /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
386 in_if_condition: Option<&'ast Expr>,
388 /// If we are currently in a trait object definition. Used to point at the bounds when
389 /// encountering a struct or enum.
390 current_trait_object: Option<&'ast [ast::GenericBound]>,
392 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
393 current_where_predicate: Option<&'ast WherePredicate>,
396 struct LateResolutionVisitor<'a, 'b, 'ast> {
397 r: &'b mut Resolver<'a>,
399 /// The module that represents the current item scope.
400 parent_scope: ParentScope<'a>,
402 /// The current set of local scopes for types and values.
403 /// FIXME #4948: Reuse ribs to avoid allocation.
404 ribs: PerNS<Vec<Rib<'a>>>,
406 /// The current set of local scopes, for labels.
407 label_ribs: Vec<Rib<'a, NodeId>>,
409 /// The trait that the current context can refer to.
410 current_trait_ref: Option<(Module<'a>, TraitRef)>,
412 /// Fields used to add information to diagnostic errors.
413 diagnostic_metadata: DiagnosticMetadata<'ast>,
415 /// State used to know whether to ignore resolution errors for function bodies.
417 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
418 /// In most cases this will be `None`, in which case errors will always be reported.
419 /// If it is `true`, then it will be updated when entering a nested function or trait body.
423 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
424 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
425 fn visit_item(&mut self, item: &'ast Item) {
426 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
427 // Always report errors in items we just entered.
428 let old_ignore = replace(&mut self.in_func_body, false);
429 self.resolve_item(item);
430 self.in_func_body = old_ignore;
431 self.diagnostic_metadata.current_item = prev;
433 fn visit_arm(&mut self, arm: &'ast Arm) {
434 self.resolve_arm(arm);
436 fn visit_block(&mut self, block: &'ast Block) {
437 self.resolve_block(block);
439 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
440 debug!("visit_anon_const {:?}", constant);
441 self.with_constant_rib(constant.value.is_potential_trivial_const_param(), |this| {
442 visit::walk_anon_const(this, constant);
445 fn visit_expr(&mut self, expr: &'ast Expr) {
446 self.resolve_expr(expr, None);
448 fn visit_local(&mut self, local: &'ast Local) {
449 let local_spans = match local.pat.kind {
450 // We check for this to avoid tuple struct fields.
451 PatKind::Wild => None,
454 local.ty.as_ref().map(|ty| ty.span),
455 local.init.as_ref().map(|init| init.span),
458 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
459 self.resolve_local(local);
460 self.diagnostic_metadata.current_let_binding = original;
462 fn visit_ty(&mut self, ty: &'ast Ty) {
463 let prev = self.diagnostic_metadata.current_trait_object;
465 TyKind::Path(ref qself, ref path) => {
466 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
468 TyKind::ImplicitSelf => {
469 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
471 .resolve_ident_in_lexical_scope(self_ty, TypeNS, Some(ty.id), ty.span)
472 .map_or(Res::Err, |d| d.res());
473 self.r.record_partial_res(ty.id, PartialRes::new(res));
475 TyKind::TraitObject(ref bounds, ..) => {
476 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
480 visit::walk_ty(self, ty);
481 self.diagnostic_metadata.current_trait_object = prev;
483 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef, m: &'ast TraitBoundModifier) {
484 self.smart_resolve_path(
485 tref.trait_ref.ref_id,
487 &tref.trait_ref.path,
488 PathSource::Trait(AliasPossibility::Maybe),
490 visit::walk_poly_trait_ref(self, tref, m);
492 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
493 match foreign_item.kind {
494 ForeignItemKind::Fn(_, _, ref generics, _)
495 | ForeignItemKind::TyAlias(_, ref generics, ..) => {
496 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
497 visit::walk_foreign_item(this, foreign_item);
500 ForeignItemKind::Static(..) => {
501 self.with_item_rib(HasGenericParams::No, |this| {
502 visit::walk_foreign_item(this, foreign_item);
505 ForeignItemKind::MacCall(..) => {
506 visit::walk_foreign_item(self, foreign_item);
510 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, _: NodeId) {
511 let rib_kind = match fn_kind {
512 // Bail if there's no body.
513 FnKind::Fn(.., None) => return visit::walk_fn(self, fn_kind, sp),
514 FnKind::Fn(FnCtxt::Free | FnCtxt::Foreign, ..) => FnItemRibKind,
515 FnKind::Fn(FnCtxt::Assoc(_), ..) => NormalRibKind,
516 FnKind::Closure(..) => ClosureOrAsyncRibKind,
518 let previous_value = self.diagnostic_metadata.current_function;
519 if matches!(fn_kind, FnKind::Fn(..)) {
520 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
522 debug!("(resolving function) entering function");
523 let declaration = fn_kind.decl();
525 // Create a value rib for the function.
526 self.with_rib(ValueNS, rib_kind, |this| {
527 // Create a label rib for the function.
528 this.with_label_rib(rib_kind, |this| {
529 // Add each argument to the rib.
530 this.resolve_params(&declaration.inputs);
532 visit::walk_fn_ret_ty(this, &declaration.output);
534 // Ignore errors in function bodies if this is rustdoc
535 // Be sure not to set this until the function signature has been resolved.
536 let previous_state = replace(&mut this.in_func_body, true);
537 // Resolve the function body, potentially inside the body of an async closure
539 FnKind::Fn(.., body) => walk_list!(this, visit_block, body),
540 FnKind::Closure(_, body) => this.visit_expr(body),
543 debug!("(resolving function) leaving function");
544 this.in_func_body = previous_state;
547 self.diagnostic_metadata.current_function = previous_value;
550 fn visit_generics(&mut self, generics: &'ast Generics) {
551 // For type parameter defaults, we have to ban access
552 // to following type parameters, as the InternalSubsts can only
553 // provide previous type parameters as they're built. We
554 // put all the parameters on the ban list and then remove
555 // them one by one as they are processed and become available.
556 let mut default_ban_rib = Rib::new(ForwardTyParamBanRibKind);
557 let mut found_default = false;
558 default_ban_rib.bindings.extend(generics.params.iter().filter_map(
559 |param| match param.kind {
560 GenericParamKind::Const { .. } | GenericParamKind::Lifetime { .. } => None,
561 GenericParamKind::Type { ref default, .. } => {
562 found_default |= default.is_some();
563 found_default.then_some((Ident::with_dummy_span(param.ident.name), Res::Err))
568 // rust-lang/rust#61631: The type `Self` is essentially
569 // another type parameter. For ADTs, we consider it
570 // well-defined only after all of the ADT type parameters have
571 // been provided. Therefore, we do not allow use of `Self`
572 // anywhere in ADT type parameter defaults.
574 // (We however cannot ban `Self` for defaults on *all* generic
575 // lists; e.g. trait generics can usefully refer to `Self`,
576 // such as in the case of `trait Add<Rhs = Self>`.)
577 if self.diagnostic_metadata.current_self_item.is_some() {
578 // (`Some` if + only if we are in ADT's generics.)
579 default_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
582 for param in &generics.params {
584 GenericParamKind::Lifetime => self.visit_generic_param(param),
585 GenericParamKind::Type { ref default } => {
586 for bound in ¶m.bounds {
587 self.visit_param_bound(bound);
590 if let Some(ref ty) = default {
591 self.ribs[TypeNS].push(default_ban_rib);
592 self.with_rib(ValueNS, ForwardTyParamBanRibKind, |this| {
593 // HACK: We use an empty `ForwardTyParamBanRibKind` here which
594 // is only used to forbid the use of const parameters inside of
597 // While the rib name doesn't really fit here, it does allow us to use the same
598 // code for both const and type parameters.
601 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
604 // Allow all following defaults to refer to this type parameter.
605 default_ban_rib.bindings.remove(&Ident::with_dummy_span(param.ident.name));
607 GenericParamKind::Const { ref ty, kw_span: _ } => {
608 for bound in ¶m.bounds {
609 self.visit_param_bound(bound);
611 self.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
612 self.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
614 self.ribs[TypeNS].pop().unwrap();
615 self.ribs[ValueNS].pop().unwrap();
619 for p in &generics.where_clause.predicates {
620 self.visit_where_predicate(p);
624 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
625 debug!("visit_generic_arg({:?})", arg);
626 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
628 GenericArg::Type(ref ty) => {
629 // We parse const arguments as path types as we cannot distinguish them during
630 // parsing. We try to resolve that ambiguity by attempting resolution the type
631 // namespace first, and if that fails we try again in the value namespace. If
632 // resolution in the value namespace succeeds, we have an generic const argument on
634 if let TyKind::Path(ref qself, ref path) = ty.kind {
635 // We cannot disambiguate multi-segment paths right now as that requires type
637 if path.segments.len() == 1 && path.segments[0].args.is_none() {
638 let mut check_ns = |ns| {
639 self.resolve_ident_in_lexical_scope(
640 path.segments[0].ident,
647 if !check_ns(TypeNS) && check_ns(ValueNS) {
648 // This must be equivalent to `visit_anon_const`, but we cannot call it
649 // directly due to visitor lifetimes so we have to copy-paste some code.
650 self.with_constant_rib(true, |this| {
651 this.smart_resolve_path(
655 PathSource::Expr(None),
658 if let Some(ref qself) = *qself {
659 this.visit_ty(&qself.ty);
661 this.visit_path(path, ty.id);
664 self.diagnostic_metadata.currently_processing_generics = prev;
672 GenericArg::Lifetime(lt) => self.visit_lifetime(lt),
673 GenericArg::Const(ct) => self.visit_anon_const(ct),
675 self.diagnostic_metadata.currently_processing_generics = prev;
678 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
679 debug!("visit_where_predicate {:?}", p);
681 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
682 visit::walk_where_predicate(self, p);
683 self.diagnostic_metadata.current_where_predicate = previous_value;
687 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
688 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
689 // During late resolution we only track the module component of the parent scope,
690 // although it may be useful to track other components as well for diagnostics.
691 let graph_root = resolver.graph_root;
692 let parent_scope = ParentScope::module(graph_root);
693 let start_rib_kind = ModuleRibKind(graph_root);
694 LateResolutionVisitor {
698 value_ns: vec![Rib::new(start_rib_kind)],
699 type_ns: vec![Rib::new(start_rib_kind)],
700 macro_ns: vec![Rib::new(start_rib_kind)],
702 label_ribs: Vec::new(),
703 current_trait_ref: None,
704 diagnostic_metadata: DiagnosticMetadata::default(),
705 // errors at module scope should always be reported
710 fn resolve_ident_in_lexical_scope(
714 record_used_id: Option<NodeId>,
716 ) -> Option<LexicalScopeBinding<'a>> {
717 self.r.resolve_ident_in_lexical_scope(
730 opt_ns: Option<Namespace>, // `None` indicates a module path in import
733 crate_lint: CrateLint,
734 ) -> PathResult<'a> {
735 self.r.resolve_path_with_ribs(
748 // We maintain a list of value ribs and type ribs.
750 // Simultaneously, we keep track of the current position in the module
751 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
752 // the value or type namespaces, we first look through all the ribs and
753 // then query the module graph. When we resolve a name in the module
754 // namespace, we can skip all the ribs (since nested modules are not
755 // allowed within blocks in Rust) and jump straight to the current module
758 // Named implementations are handled separately. When we find a method
759 // call, we consult the module node to find all of the implementations in
760 // scope. This information is lazily cached in the module node. We then
761 // generate a fake "implementation scope" containing all the
762 // implementations thus found, for compatibility with old resolve pass.
764 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
769 work: impl FnOnce(&mut Self) -> T,
771 self.ribs[ns].push(Rib::new(kind));
772 let ret = work(self);
777 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
778 let id = self.r.local_def_id(id);
779 let module = self.r.module_map.get(&id).cloned(); // clones a reference
780 if let Some(module) = module {
781 // Move down in the graph.
782 let orig_module = replace(&mut self.parent_scope.module, module);
783 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
784 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
786 this.parent_scope.module = orig_module;
795 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
796 /// label and reports an error if the label is not found or is unreachable.
797 fn resolve_label(&self, mut label: Ident) -> Option<NodeId> {
798 let mut suggestion = None;
800 // Preserve the original span so that errors contain "in this macro invocation"
802 let original_span = label.span;
804 for i in (0..self.label_ribs.len()).rev() {
805 let rib = &self.label_ribs[i];
807 if let MacroDefinition(def) = rib.kind {
808 // If an invocation of this macro created `ident`, give up on `ident`
809 // and switch to `ident`'s source from the macro definition.
810 if def == self.r.macro_def(label.span.ctxt()) {
811 label.span.remove_mark();
815 let ident = label.normalize_to_macro_rules();
816 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
817 return if self.is_label_valid_from_rib(i) {
822 ResolutionError::UnreachableLabel {
824 definition_span: ident.span,
833 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
834 // the first such label that is encountered.
835 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
840 ResolutionError::UndeclaredLabel { name: label.name, suggestion },
845 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
846 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
847 let ribs = &self.label_ribs[rib_index + 1..];
851 NormalRibKind | MacroDefinition(..) => {
852 // Nothing to do. Continue.
856 | ClosureOrAsyncRibKind
859 | ConstantItemRibKind(_)
861 | ForwardTyParamBanRibKind
862 | ConstParamTyRibKind => {
871 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
872 debug!("resolve_adt");
873 self.with_current_self_item(item, |this| {
874 this.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
875 let item_def_id = this.r.local_def_id(item.id).to_def_id();
876 this.with_self_rib(Res::SelfTy(None, Some((item_def_id, false))), |this| {
877 visit::walk_item(this, item);
883 fn future_proof_import(&mut self, use_tree: &UseTree) {
884 let segments = &use_tree.prefix.segments;
885 if !segments.is_empty() {
886 let ident = segments[0].ident;
887 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
891 let nss = match use_tree.kind {
892 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
895 let report_error = |this: &Self, ns| {
896 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
897 if this.should_report_errs() {
900 .span_err(ident.span, &format!("imports cannot refer to {}", what));
905 match self.resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span) {
906 Some(LexicalScopeBinding::Res(..)) => {
907 report_error(self, ns);
909 Some(LexicalScopeBinding::Item(binding)) => {
910 let orig_unusable_binding =
911 replace(&mut self.r.unusable_binding, Some(binding));
912 if let Some(LexicalScopeBinding::Res(..)) = self
913 .resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span)
915 report_error(self, ns);
917 self.r.unusable_binding = orig_unusable_binding;
922 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
923 for (use_tree, _) in use_trees {
924 self.future_proof_import(use_tree);
929 fn resolve_item(&mut self, item: &'ast Item) {
930 let name = item.ident.name;
931 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
934 ItemKind::TyAlias(_, ref generics, _, _) | ItemKind::Fn(_, _, ref generics, _) => {
935 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
936 visit::walk_item(this, item)
940 ItemKind::Enum(_, ref generics)
941 | ItemKind::Struct(_, ref generics)
942 | ItemKind::Union(_, ref generics) => {
943 self.resolve_adt(item, generics);
950 items: ref impl_items,
953 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
956 ItemKind::Trait(.., ref generics, ref bounds, ref trait_items) => {
957 // Create a new rib for the trait-wide type parameters.
958 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
959 let local_def_id = this.r.local_def_id(item.id).to_def_id();
960 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
961 this.visit_generics(generics);
962 walk_list!(this, visit_param_bound, bounds);
964 let walk_assoc_item = |this: &mut Self, generics, item| {
965 this.with_generic_param_rib(generics, AssocItemRibKind, |this| {
966 visit::walk_assoc_item(this, item, AssocCtxt::Trait)
970 for item in trait_items {
971 this.with_trait_items(trait_items, |this| {
973 AssocItemKind::Const(_, ty, default) => {
975 // Only impose the restrictions of `ConstRibKind` for an
976 // actual constant expression in a provided default.
977 if let Some(expr) = default {
978 // We allow arbitrary const expressions inside of associated consts,
979 // even if they are potentially not const evaluatable.
981 // Type parameters can already be used and as associated consts are
982 // not used as part of the type system, this is far less surprising.
983 this.with_constant_rib(true, |this| {
984 this.visit_expr(expr)
988 AssocItemKind::Fn(_, _, generics, _) => {
989 walk_assoc_item(this, generics, item);
991 AssocItemKind::TyAlias(_, generics, _, _) => {
992 walk_assoc_item(this, generics, item);
994 AssocItemKind::MacCall(_) => {
995 panic!("unexpanded macro in resolve!")
1004 ItemKind::TraitAlias(ref generics, ref bounds) => {
1005 // Create a new rib for the trait-wide type parameters.
1006 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1007 let local_def_id = this.r.local_def_id(item.id).to_def_id();
1008 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
1009 this.visit_generics(generics);
1010 walk_list!(this, visit_param_bound, bounds);
1015 ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
1016 self.with_scope(item.id, |this| {
1017 visit::walk_item(this, item);
1021 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
1022 debug!("resolve_item ItemKind::Const");
1023 self.with_item_rib(HasGenericParams::No, |this| {
1025 if let Some(expr) = expr {
1026 this.with_constant_rib(expr.is_potential_trivial_const_param(), |this| {
1027 this.visit_expr(expr)
1033 ItemKind::Use(ref use_tree) => {
1034 self.future_proof_import(use_tree);
1037 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) | ItemKind::GlobalAsm(..) => {
1038 // do nothing, these are just around to be encoded
1041 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
1045 fn with_generic_param_rib<'c, F>(&'c mut self, generics: &'c Generics, kind: RibKind<'a>, f: F)
1047 F: FnOnce(&mut Self),
1049 debug!("with_generic_param_rib");
1050 let mut function_type_rib = Rib::new(kind);
1051 let mut function_value_rib = Rib::new(kind);
1052 let mut seen_bindings = FxHashMap::default();
1054 // We also can't shadow bindings from the parent item
1055 if let AssocItemRibKind = kind {
1056 let mut add_bindings_for_ns = |ns| {
1057 let parent_rib = self.ribs[ns]
1059 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
1060 .expect("associated item outside of an item");
1062 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
1064 add_bindings_for_ns(ValueNS);
1065 add_bindings_for_ns(TypeNS);
1068 for param in &generics.params {
1069 if let GenericParamKind::Lifetime { .. } = param.kind {
1073 let def_kind = match param.kind {
1074 GenericParamKind::Type { .. } => DefKind::TyParam,
1075 GenericParamKind::Const { .. } => DefKind::ConstParam,
1076 _ => unreachable!(),
1079 let ident = param.ident.normalize_to_macros_2_0();
1080 debug!("with_generic_param_rib: {}", param.id);
1082 if seen_bindings.contains_key(&ident) {
1083 let span = seen_bindings.get(&ident).unwrap();
1084 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, *span);
1085 self.report_error(param.ident.span, err);
1087 seen_bindings.entry(ident).or_insert(param.ident.span);
1089 // Plain insert (no renaming).
1090 let res = Res::Def(def_kind, self.r.local_def_id(param.id).to_def_id());
1093 GenericParamKind::Type { .. } => {
1094 function_type_rib.bindings.insert(ident, res);
1095 self.r.record_partial_res(param.id, PartialRes::new(res));
1097 GenericParamKind::Const { .. } => {
1098 function_value_rib.bindings.insert(ident, res);
1099 self.r.record_partial_res(param.id, PartialRes::new(res));
1101 _ => unreachable!(),
1105 self.ribs[ValueNS].push(function_value_rib);
1106 self.ribs[TypeNS].push(function_type_rib);
1110 self.ribs[TypeNS].pop();
1111 self.ribs[ValueNS].pop();
1114 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
1115 self.label_ribs.push(Rib::new(kind));
1117 self.label_ribs.pop();
1120 fn with_item_rib(&mut self, has_generic_params: HasGenericParams, f: impl FnOnce(&mut Self)) {
1121 let kind = ItemRibKind(has_generic_params);
1122 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
1125 fn with_constant_rib(&mut self, trivial: bool, f: impl FnOnce(&mut Self)) {
1126 debug!("with_constant_rib");
1127 self.with_rib(ValueNS, ConstantItemRibKind(trivial), |this| {
1128 this.with_rib(TypeNS, ConstantItemRibKind(trivial), |this| {
1129 this.with_label_rib(ConstantItemRibKind(trivial), f);
1134 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
1135 // Handle nested impls (inside fn bodies)
1136 let previous_value =
1137 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
1138 let result = f(self);
1139 self.diagnostic_metadata.current_self_type = previous_value;
1143 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
1144 let previous_value =
1145 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
1146 let result = f(self);
1147 self.diagnostic_metadata.current_self_item = previous_value;
1151 /// When evaluating a `trait` use its associated types' idents for suggestionsa in E0412.
1152 fn with_trait_items<T>(
1154 trait_items: &Vec<P<AssocItem>>,
1155 f: impl FnOnce(&mut Self) -> T,
1157 let trait_assoc_types = replace(
1158 &mut self.diagnostic_metadata.current_trait_assoc_types,
1161 .filter_map(|item| match &item.kind {
1162 AssocItemKind::TyAlias(_, _, bounds, _) if bounds.is_empty() => {
1169 let result = f(self);
1170 self.diagnostic_metadata.current_trait_assoc_types = trait_assoc_types;
1174 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
1175 fn with_optional_trait_ref<T>(
1177 opt_trait_ref: Option<&TraitRef>,
1178 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
1180 let mut new_val = None;
1181 let mut new_id = None;
1182 if let Some(trait_ref) = opt_trait_ref {
1183 let path: Vec<_> = Segment::from_path(&trait_ref.path);
1184 let res = self.smart_resolve_path_fragment(
1188 trait_ref.path.span,
1189 PathSource::Trait(AliasPossibility::No),
1190 CrateLint::SimplePath(trait_ref.ref_id),
1192 let res = res.base_res();
1193 if res != Res::Err {
1194 new_id = Some(res.def_id());
1195 let span = trait_ref.path.span;
1196 if let PathResult::Module(ModuleOrUniformRoot::Module(module)) = self.resolve_path(
1201 CrateLint::SimplePath(trait_ref.ref_id),
1203 new_val = Some((module, trait_ref.clone()));
1207 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1208 let result = f(self, new_id);
1209 self.current_trait_ref = original_trait_ref;
1213 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
1214 let mut self_type_rib = Rib::new(NormalRibKind);
1216 // Plain insert (no renaming, since types are not currently hygienic)
1217 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
1218 self.ribs[ns].push(self_type_rib);
1220 self.ribs[ns].pop();
1223 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
1224 self.with_self_rib_ns(TypeNS, self_res, f)
1227 fn resolve_implementation(
1229 generics: &'ast Generics,
1230 opt_trait_reference: &'ast Option<TraitRef>,
1231 self_type: &'ast Ty,
1233 impl_items: &'ast [P<AssocItem>],
1235 debug!("resolve_implementation");
1236 // If applicable, create a rib for the type parameters.
1237 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1238 // Dummy self type for better errors if `Self` is used in the trait path.
1239 this.with_self_rib(Res::SelfTy(None, None), |this| {
1240 // Resolve the trait reference, if necessary.
1241 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1242 let item_def_id = this.r.local_def_id(item_id).to_def_id();
1243 this.with_self_rib(Res::SelfTy(trait_id, Some((item_def_id, false))), |this| {
1244 if let Some(trait_ref) = opt_trait_reference.as_ref() {
1245 // Resolve type arguments in the trait path.
1246 visit::walk_trait_ref(this, trait_ref);
1248 // Resolve the self type.
1249 this.visit_ty(self_type);
1250 // Resolve the generic parameters.
1251 this.visit_generics(generics);
1252 // Resolve the items within the impl.
1253 this.with_current_self_type(self_type, |this| {
1254 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
1255 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
1256 for item in impl_items {
1257 use crate::ResolutionError::*;
1259 AssocItemKind::Const(_default, _ty, _expr) => {
1260 debug!("resolve_implementation AssocItemKind::Const",);
1261 // If this is a trait impl, ensure the const
1263 this.check_trait_item(
1267 |n, s| ConstNotMemberOfTrait(n, s),
1270 // We allow arbitrary const expressions inside of associated consts,
1271 // even if they are potentially not const evaluatable.
1273 // Type parameters can already be used and as associated consts are
1274 // not used as part of the type system, this is far less surprising.
1275 this.with_constant_rib(true, |this| {
1276 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
1279 AssocItemKind::Fn(_, _, generics, _) => {
1280 // We also need a new scope for the impl item type parameters.
1281 this.with_generic_param_rib(
1285 // If this is a trait impl, ensure the method
1287 this.check_trait_item(
1291 |n, s| MethodNotMemberOfTrait(n, s),
1294 visit::walk_assoc_item(
1302 AssocItemKind::TyAlias(_, generics, _, _) => {
1303 // We also need a new scope for the impl item type parameters.
1304 this.with_generic_param_rib(
1308 // If this is a trait impl, ensure the type
1310 this.check_trait_item(
1314 |n, s| TypeNotMemberOfTrait(n, s),
1317 visit::walk_assoc_item(
1325 AssocItemKind::MacCall(_) => {
1326 panic!("unexpanded macro in resolve!")
1338 fn check_trait_item<F>(&mut self, ident: Ident, ns: Namespace, span: Span, err: F)
1340 F: FnOnce(Symbol, &str) -> ResolutionError<'_>,
1342 // If there is a TraitRef in scope for an impl, then the method must be in the
1344 if let Some((module, _)) = self.current_trait_ref {
1347 .resolve_ident_in_module(
1348 ModuleOrUniformRoot::Module(module),
1357 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
1358 self.report_error(span, err(ident.name, &path_names_to_string(path)));
1363 fn resolve_params(&mut self, params: &'ast [Param]) {
1364 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1365 for Param { pat, ty, .. } in params {
1366 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1368 debug!("(resolving function / closure) recorded parameter");
1372 fn resolve_local(&mut self, local: &'ast Local) {
1373 debug!("resolving local ({:?})", local);
1374 // Resolve the type.
1375 walk_list!(self, visit_ty, &local.ty);
1377 // Resolve the initializer.
1378 walk_list!(self, visit_expr, &local.init);
1380 // Resolve the pattern.
1381 self.resolve_pattern_top(&local.pat, PatternSource::Let);
1384 /// build a map from pattern identifiers to binding-info's.
1385 /// this is done hygienically. This could arise for a macro
1386 /// that expands into an or-pattern where one 'x' was from the
1387 /// user and one 'x' came from the macro.
1388 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1389 let mut binding_map = FxHashMap::default();
1391 pat.walk(&mut |pat| {
1393 PatKind::Ident(binding_mode, ident, ref sub_pat)
1394 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
1396 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
1398 PatKind::Or(ref ps) => {
1399 // Check the consistency of this or-pattern and
1400 // then add all bindings to the larger map.
1401 for bm in self.check_consistent_bindings(ps) {
1402 binding_map.extend(bm);
1415 fn is_base_res_local(&self, nid: NodeId) -> bool {
1416 match self.r.partial_res_map.get(&nid).map(|res| res.base_res()) {
1417 Some(Res::Local(..)) => true,
1422 /// Checks that all of the arms in an or-pattern have exactly the
1423 /// same set of bindings, with the same binding modes for each.
1424 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
1425 let mut missing_vars = FxHashMap::default();
1426 let mut inconsistent_vars = FxHashMap::default();
1428 // 1) Compute the binding maps of all arms.
1429 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
1431 // 2) Record any missing bindings or binding mode inconsistencies.
1432 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
1433 // Check against all arms except for the same pattern which is always self-consistent.
1437 .filter(|(_, pat)| pat.id != pat_outer.id)
1438 .flat_map(|(idx, _)| maps[idx].iter())
1439 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
1441 for (name, info, &binding_inner) in inners {
1444 // The inner binding is missing in the outer.
1446 missing_vars.entry(name).or_insert_with(|| BindingError {
1448 origin: BTreeSet::new(),
1449 target: BTreeSet::new(),
1450 could_be_path: name.as_str().starts_with(char::is_uppercase),
1452 binding_error.origin.insert(binding_inner.span);
1453 binding_error.target.insert(pat_outer.span);
1455 Some(binding_outer) => {
1456 if binding_outer.binding_mode != binding_inner.binding_mode {
1457 // The binding modes in the outer and inner bindings differ.
1460 .or_insert((binding_inner.span, binding_outer.span));
1467 // 3) Report all missing variables we found.
1468 let mut missing_vars = missing_vars.iter_mut().collect::<Vec<_>>();
1469 missing_vars.sort_by_key(|(sym, _err)| sym.as_str());
1471 for (name, mut v) in missing_vars {
1472 if inconsistent_vars.contains_key(name) {
1473 v.could_be_path = false;
1476 *v.origin.iter().next().unwrap(),
1477 ResolutionError::VariableNotBoundInPattern(v),
1481 // 4) Report all inconsistencies in binding modes we found.
1482 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
1483 inconsistent_vars.sort();
1484 for (name, v) in inconsistent_vars {
1485 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
1488 // 5) Finally bubble up all the binding maps.
1492 /// Check the consistency of the outermost or-patterns.
1493 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
1494 pat.walk(&mut |pat| match pat.kind {
1495 PatKind::Or(ref ps) => {
1496 self.check_consistent_bindings(ps);
1503 fn resolve_arm(&mut self, arm: &'ast Arm) {
1504 self.with_rib(ValueNS, NormalRibKind, |this| {
1505 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
1506 walk_list!(this, visit_expr, &arm.guard);
1507 this.visit_expr(&arm.body);
1511 /// Arising from `source`, resolve a top level pattern.
1512 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
1513 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1514 self.resolve_pattern(pat, pat_src, &mut bindings);
1520 pat_src: PatternSource,
1521 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1523 self.resolve_pattern_inner(pat, pat_src, bindings);
1524 // This has to happen *after* we determine which pat_idents are variants:
1525 self.check_consistent_bindings_top(pat);
1526 visit::walk_pat(self, pat);
1529 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
1533 /// A stack of sets of bindings accumulated.
1535 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
1536 /// be interpreted as re-binding an already bound binding. This results in an error.
1537 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
1538 /// in reusing this binding rather than creating a fresh one.
1540 /// When called at the top level, the stack must have a single element
1541 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
1542 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
1543 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
1544 /// When each `p_i` has been dealt with, the top set is merged with its parent.
1545 /// When a whole or-pattern has been dealt with, the thing happens.
1547 /// See the implementation and `fresh_binding` for more details.
1548 fn resolve_pattern_inner(
1551 pat_src: PatternSource,
1552 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1554 // Visit all direct subpatterns of this pattern.
1555 pat.walk(&mut |pat| {
1556 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
1558 PatKind::Ident(bmode, ident, ref sub) => {
1559 // First try to resolve the identifier as some existing entity,
1560 // then fall back to a fresh binding.
1561 let has_sub = sub.is_some();
1563 .try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub)
1564 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
1565 self.r.record_partial_res(pat.id, PartialRes::new(res));
1567 PatKind::TupleStruct(ref path, ref sub_patterns) => {
1568 self.smart_resolve_path(
1572 PathSource::TupleStruct(
1574 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
1578 PatKind::Path(ref qself, ref path) => {
1579 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
1581 PatKind::Struct(ref path, ..) => {
1582 self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
1584 PatKind::Or(ref ps) => {
1585 // Add a new set of bindings to the stack. `Or` here records that when a
1586 // binding already exists in this set, it should not result in an error because
1587 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
1588 bindings.push((PatBoundCtx::Or, Default::default()));
1590 // Now we need to switch back to a product context so that each
1591 // part of the or-pattern internally rejects already bound names.
1592 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
1593 bindings.push((PatBoundCtx::Product, Default::default()));
1594 self.resolve_pattern_inner(p, pat_src, bindings);
1595 // Move up the non-overlapping bindings to the or-pattern.
1596 // Existing bindings just get "merged".
1597 let collected = bindings.pop().unwrap().1;
1598 bindings.last_mut().unwrap().1.extend(collected);
1600 // This or-pattern itself can itself be part of a product,
1601 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
1602 // Both cases bind `a` again in a product pattern and must be rejected.
1603 let collected = bindings.pop().unwrap().1;
1604 bindings.last_mut().unwrap().1.extend(collected);
1606 // Prevent visiting `ps` as we've already done so above.
1619 pat_src: PatternSource,
1620 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1622 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
1623 // (We must not add it if it's in the bindings map because that breaks the assumptions
1624 // later passes make about or-patterns.)
1625 let ident = ident.normalize_to_macro_rules();
1627 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
1628 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
1629 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
1630 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
1631 // This is *required* for consistency which is checked later.
1632 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
1634 if already_bound_and {
1635 // Overlap in a product pattern somewhere; report an error.
1636 use ResolutionError::*;
1637 let error = match pat_src {
1638 // `fn f(a: u8, a: u8)`:
1639 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
1641 _ => IdentifierBoundMoreThanOnceInSamePattern,
1643 self.report_error(ident.span, error(ident.name));
1646 // Record as bound if it's valid:
1647 let ident_valid = ident.name != kw::Invalid;
1649 bindings.last_mut().unwrap().1.insert(ident);
1652 if already_bound_or {
1653 // `Variant1(a) | Variant2(a)`, ok
1654 // Reuse definition from the first `a`.
1655 self.innermost_rib_bindings(ValueNS)[&ident]
1657 let res = Res::Local(pat_id);
1659 // A completely fresh binding add to the set if it's valid.
1660 self.innermost_rib_bindings(ValueNS).insert(ident, res);
1666 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
1667 &mut self.ribs[ns].last_mut().unwrap().bindings
1670 fn try_resolve_as_non_binding(
1672 pat_src: PatternSource,
1678 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
1679 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
1680 // also be interpreted as a path to e.g. a constant, variant, etc.
1681 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
1683 let ls_binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, pat.span)?;
1684 let (res, binding) = match ls_binding {
1685 LexicalScopeBinding::Item(binding)
1686 if is_syntactic_ambiguity && binding.is_ambiguity() =>
1688 // For ambiguous bindings we don't know all their definitions and cannot check
1689 // whether they can be shadowed by fresh bindings or not, so force an error.
1690 // issues/33118#issuecomment-233962221 (see below) still applies here,
1691 // but we have to ignore it for backward compatibility.
1692 self.r.record_use(ident, ValueNS, binding, false);
1695 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
1696 LexicalScopeBinding::Res(res) => (res, None),
1700 Res::SelfCtor(_) // See #70549.
1702 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
1704 ) if is_syntactic_ambiguity => {
1705 // Disambiguate in favor of a unit struct/variant or constant pattern.
1706 if let Some(binding) = binding {
1707 self.r.record_use(ident, ValueNS, binding, false);
1711 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static, _) => {
1712 // This is unambiguously a fresh binding, either syntactically
1713 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
1714 // to something unusable as a pattern (e.g., constructor function),
1715 // but we still conservatively report an error, see
1716 // issues/33118#issuecomment-233962221 for one reason why.
1719 ResolutionError::BindingShadowsSomethingUnacceptable(
1722 binding.expect("no binding for a ctor or static"),
1727 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
1728 // These entities are explicitly allowed to be shadowed by fresh bindings.
1733 "unexpected resolution for an identifier in pattern: {:?}",
1739 // High-level and context dependent path resolution routine.
1740 // Resolves the path and records the resolution into definition map.
1741 // If resolution fails tries several techniques to find likely
1742 // resolution candidates, suggest imports or other help, and report
1743 // errors in user friendly way.
1744 fn smart_resolve_path(
1747 qself: Option<&QSelf>,
1749 source: PathSource<'ast>,
1751 self.smart_resolve_path_fragment(
1754 &Segment::from_path(path),
1757 CrateLint::SimplePath(id),
1761 fn smart_resolve_path_fragment(
1764 qself: Option<&QSelf>,
1767 source: PathSource<'ast>,
1768 crate_lint: CrateLint,
1771 "smart_resolve_path_fragment(id={:?},qself={:?},path={:?}",
1776 let ns = source.namespace();
1777 let is_expected = &|res| source.is_expected(res);
1779 let report_errors = |this: &mut Self, res: Option<Res>| {
1780 if this.should_report_errs() {
1781 let (err, candidates) = this.smart_resolve_report_errors(path, span, source, res);
1783 let def_id = this.parent_scope.module.normal_ancestor_id;
1784 let instead = res.is_some();
1786 if res.is_none() { this.report_missing_type_error(path) } else { None };
1788 this.r.use_injections.push(UseError {
1797 PartialRes::new(Res::Err)
1800 // For paths originating from calls (like in `HashMap::new()`), tries
1801 // to enrich the plain `failed to resolve: ...` message with hints
1802 // about possible missing imports.
1804 // Similar thing, for types, happens in `report_errors` above.
1805 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
1806 if !source.is_call() {
1807 return Some(parent_err);
1810 // Before we start looking for candidates, we have to get our hands
1811 // on the type user is trying to perform invocation on; basically:
1812 // we're transforming `HashMap::new` into just `HashMap`
1813 let path = if let Some((_, path)) = path.split_last() {
1816 return Some(parent_err);
1819 let (mut err, candidates) =
1820 this.smart_resolve_report_errors(path, span, PathSource::Type, None);
1822 if candidates.is_empty() {
1824 return Some(parent_err);
1827 // There are two different error messages user might receive at
1829 // - E0412 cannot find type `{}` in this scope
1830 // - E0433 failed to resolve: use of undeclared type or module `{}`
1832 // The first one is emitted for paths in type-position, and the
1833 // latter one - for paths in expression-position.
1835 // Thus (since we're in expression-position at this point), not to
1836 // confuse the user, we want to keep the *message* from E0432 (so
1837 // `parent_err`), but we want *hints* from E0412 (so `err`).
1839 // And that's what happens below - we're just mixing both messages
1840 // into a single one.
1841 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
1843 parent_err.cancel();
1845 err.message = take(&mut parent_err.message);
1846 err.code = take(&mut parent_err.code);
1847 err.children = take(&mut parent_err.children);
1851 let def_id = this.parent_scope.module.normal_ancestor_id;
1853 if this.should_report_errs() {
1854 this.r.use_injections.push(UseError {
1865 // We don't return `Some(parent_err)` here, because the error will
1866 // be already printed as part of the `use` injections
1870 let partial_res = match self.resolve_qpath_anywhere(
1876 source.defer_to_typeck(),
1879 Ok(Some(partial_res)) if partial_res.unresolved_segments() == 0 => {
1880 if is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err {
1883 report_errors(self, Some(partial_res.base_res()))
1887 Ok(Some(partial_res)) if source.defer_to_typeck() => {
1888 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
1889 // or `<T>::A::B`. If `B` should be resolved in value namespace then
1890 // it needs to be added to the trait map.
1892 let item_name = path.last().unwrap().ident;
1893 let traits = self.get_traits_containing_item(item_name, ns);
1894 self.r.trait_map.insert(id, traits);
1897 let mut std_path = vec![Segment::from_ident(Ident::with_dummy_span(sym::std))];
1899 std_path.extend(path);
1901 if self.r.primitive_type_table.primitive_types.contains_key(&path[0].ident.name) {
1902 if let PathResult::Module(_) | PathResult::NonModule(_) =
1903 self.resolve_path(&std_path, Some(ns), false, span, CrateLint::No)
1905 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
1907 path.iter().last().map(|segment| segment.ident.span).unwrap_or(span);
1909 let mut hm = self.r.session.confused_type_with_std_module.borrow_mut();
1910 hm.insert(item_span, span);
1911 hm.insert(span, span);
1919 if let Some(err) = report_errors_for_call(self, err) {
1920 self.report_error(err.span, err.node);
1923 PartialRes::new(Res::Err)
1926 _ => report_errors(self, None),
1929 if let PathSource::TraitItem(..) = source {
1931 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
1932 self.r.record_partial_res(id, partial_res);
1938 fn self_type_is_available(&mut self, span: Span) -> bool {
1939 let binding = self.resolve_ident_in_lexical_scope(
1940 Ident::with_dummy_span(kw::SelfUpper),
1945 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1948 fn self_value_is_available(&mut self, self_span: Span, path_span: Span) -> bool {
1949 let ident = Ident::new(kw::SelfLower, self_span);
1950 let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, path_span);
1951 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1954 /// A wrapper around [`Resolver::report_error`].
1956 /// This doesn't emit errors for function bodies if this is rustdoc.
1957 fn report_error(&self, span: Span, resolution_error: ResolutionError<'_>) {
1958 if self.should_report_errs() {
1959 self.r.report_error(span, resolution_error);
1964 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
1965 fn should_report_errs(&self) -> bool {
1966 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
1969 // Resolve in alternative namespaces if resolution in the primary namespace fails.
1970 fn resolve_qpath_anywhere(
1973 qself: Option<&QSelf>,
1975 primary_ns: Namespace,
1977 defer_to_typeck: bool,
1978 crate_lint: CrateLint,
1979 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
1980 let mut fin_res = None;
1982 for (i, ns) in [primary_ns, TypeNS, ValueNS].iter().cloned().enumerate() {
1983 if i == 0 || ns != primary_ns {
1984 match self.resolve_qpath(id, qself, path, ns, span, crate_lint)? {
1986 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
1988 return Ok(Some(partial_res));
1991 if fin_res.is_none() {
1992 fin_res = partial_res
1999 assert!(primary_ns != MacroNS);
2001 if qself.is_none() {
2002 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
2003 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
2004 if let Ok((_, res)) =
2005 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
2007 return Ok(Some(PartialRes::new(res)));
2014 /// Handles paths that may refer to associated items.
2018 qself: Option<&QSelf>,
2022 crate_lint: CrateLint,
2023 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2025 "resolve_qpath(id={:?}, qself={:?}, path={:?}, ns={:?}, span={:?})",
2026 id, qself, path, ns, span,
2029 if let Some(qself) = qself {
2030 if qself.position == 0 {
2031 // This is a case like `<T>::B`, where there is no
2032 // trait to resolve. In that case, we leave the `B`
2033 // segment to be resolved by type-check.
2034 return Ok(Some(PartialRes::with_unresolved_segments(
2035 Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX)),
2040 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
2042 // Currently, `path` names the full item (`A::B::C`, in
2043 // our example). so we extract the prefix of that that is
2044 // the trait (the slice upto and including
2045 // `qself.position`). And then we recursively resolve that,
2046 // but with `qself` set to `None`.
2048 // However, setting `qself` to none (but not changing the
2049 // span) loses the information about where this path
2050 // *actually* appears, so for the purposes of the crate
2051 // lint we pass along information that this is the trait
2052 // name from a fully qualified path, and this also
2053 // contains the full span (the `CrateLint::QPathTrait`).
2054 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2055 let partial_res = self.smart_resolve_path_fragment(
2058 &path[..=qself.position],
2060 PathSource::TraitItem(ns),
2061 CrateLint::QPathTrait { qpath_id: id, qpath_span: qself.path_span },
2064 // The remaining segments (the `C` in our example) will
2065 // have to be resolved by type-check, since that requires doing
2066 // trait resolution.
2067 return Ok(Some(PartialRes::with_unresolved_segments(
2068 partial_res.base_res(),
2069 partial_res.unresolved_segments() + path.len() - qself.position - 1,
2073 let result = match self.resolve_path(&path, Some(ns), true, span, crate_lint) {
2074 PathResult::NonModule(path_res) => path_res,
2075 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
2076 PartialRes::new(module.res().unwrap())
2078 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2079 // don't report an error right away, but try to fallback to a primitive type.
2080 // So, we are still able to successfully resolve something like
2082 // use std::u8; // bring module u8 in scope
2083 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2084 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
2085 // // not to non-existent std::u8::max_value
2088 // Such behavior is required for backward compatibility.
2089 // The same fallback is used when `a` resolves to nothing.
2090 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
2091 if (ns == TypeNS || path.len() > 1)
2094 .primitive_type_table
2096 .contains_key(&path[0].ident.name) =>
2098 let prim = self.r.primitive_type_table.primitive_types[&path[0].ident.name];
2099 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
2101 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2102 PartialRes::new(module.res().unwrap())
2104 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
2105 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
2107 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
2108 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
2112 && result.base_res() != Res::Err
2113 && path[0].ident.name != kw::PathRoot
2114 && path[0].ident.name != kw::DollarCrate
2116 let unqualified_result = {
2117 match self.resolve_path(
2118 &[*path.last().unwrap()],
2124 PathResult::NonModule(path_res) => path_res.base_res(),
2125 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2126 module.res().unwrap()
2128 _ => return Ok(Some(result)),
2131 if result.base_res() == unqualified_result {
2132 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
2133 self.r.lint_buffer.buffer_lint(lint, id, span, "unnecessary qualification")
2140 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
2141 if let Some(label) = label {
2142 if label.ident.as_str().as_bytes()[1] != b'_' {
2143 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
2145 self.with_label_rib(NormalRibKind, |this| {
2146 let ident = label.ident.normalize_to_macro_rules();
2147 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
2155 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
2156 self.with_resolved_label(label, id, |this| this.visit_block(block));
2159 fn resolve_block(&mut self, block: &'ast Block) {
2160 debug!("(resolving block) entering block");
2161 // Move down in the graph, if there's an anonymous module rooted here.
2162 let orig_module = self.parent_scope.module;
2163 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
2165 let mut num_macro_definition_ribs = 0;
2166 if let Some(anonymous_module) = anonymous_module {
2167 debug!("(resolving block) found anonymous module, moving down");
2168 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2169 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2170 self.parent_scope.module = anonymous_module;
2172 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2175 // Descend into the block.
2176 for stmt in &block.stmts {
2177 if let StmtKind::Item(ref item) = stmt.kind {
2178 if let ItemKind::MacroDef(..) = item.kind {
2179 num_macro_definition_ribs += 1;
2180 let res = self.r.local_def_id(item.id).to_def_id();
2181 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
2182 self.label_ribs.push(Rib::new(MacroDefinition(res)));
2186 self.visit_stmt(stmt);
2190 self.parent_scope.module = orig_module;
2191 for _ in 0..num_macro_definition_ribs {
2192 self.ribs[ValueNS].pop();
2193 self.label_ribs.pop();
2195 self.ribs[ValueNS].pop();
2196 if anonymous_module.is_some() {
2197 self.ribs[TypeNS].pop();
2199 debug!("(resolving block) leaving block");
2202 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
2203 // First, record candidate traits for this expression if it could
2204 // result in the invocation of a method call.
2206 self.record_candidate_traits_for_expr_if_necessary(expr);
2208 // Next, resolve the node.
2210 ExprKind::Path(ref qself, ref path) => {
2211 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
2212 visit::walk_expr(self, expr);
2215 ExprKind::Struct(ref path, ..) => {
2216 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
2217 visit::walk_expr(self, expr);
2220 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
2221 if let Some(node_id) = self.resolve_label(label.ident) {
2222 // Since this res is a label, it is never read.
2223 self.r.label_res_map.insert(expr.id, node_id);
2224 self.diagnostic_metadata.unused_labels.remove(&node_id);
2227 // visit `break` argument if any
2228 visit::walk_expr(self, expr);
2231 ExprKind::Let(ref pat, ref scrutinee) => {
2232 self.visit_expr(scrutinee);
2233 self.resolve_pattern_top(pat, PatternSource::Let);
2236 ExprKind::If(ref cond, ref then, ref opt_else) => {
2237 self.with_rib(ValueNS, NormalRibKind, |this| {
2238 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
2239 this.visit_expr(cond);
2240 this.diagnostic_metadata.in_if_condition = old;
2241 this.visit_block(then);
2243 if let Some(expr) = opt_else {
2244 self.visit_expr(expr);
2248 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
2250 ExprKind::While(ref cond, ref block, label) => {
2251 self.with_resolved_label(label, expr.id, |this| {
2252 this.with_rib(ValueNS, NormalRibKind, |this| {
2253 this.visit_expr(cond);
2254 this.visit_block(block);
2259 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
2260 self.visit_expr(iter_expr);
2261 self.with_rib(ValueNS, NormalRibKind, |this| {
2262 this.resolve_pattern_top(pat, PatternSource::For);
2263 this.resolve_labeled_block(label, expr.id, block);
2267 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
2269 // Equivalent to `visit::walk_expr` + passing some context to children.
2270 ExprKind::Field(ref subexpression, _) => {
2271 self.resolve_expr(subexpression, Some(expr));
2273 ExprKind::MethodCall(ref segment, ref arguments, _) => {
2274 let mut arguments = arguments.iter();
2275 self.resolve_expr(arguments.next().unwrap(), Some(expr));
2276 for argument in arguments {
2277 self.resolve_expr(argument, None);
2279 self.visit_path_segment(expr.span, segment);
2282 ExprKind::Call(ref callee, ref arguments) => {
2283 self.resolve_expr(callee, Some(expr));
2284 for argument in arguments {
2285 self.resolve_expr(argument, None);
2288 ExprKind::Type(ref type_expr, ref ty) => {
2289 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
2290 // type ascription. Here we are trying to retrieve the span of the colon token as
2291 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
2292 // with `expr::Ty`, only in this case it will match the span from
2293 // `type_ascription_path_suggestions`.
2294 self.diagnostic_metadata
2295 .current_type_ascription
2296 .push(type_expr.span.between(ty.span));
2297 visit::walk_expr(self, expr);
2298 self.diagnostic_metadata.current_type_ascription.pop();
2300 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
2301 // resolve the arguments within the proper scopes so that usages of them inside the
2302 // closure are detected as upvars rather than normal closure arg usages.
2303 ExprKind::Closure(_, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
2304 self.with_rib(ValueNS, NormalRibKind, |this| {
2305 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
2306 // Resolve arguments:
2307 this.resolve_params(&fn_decl.inputs);
2308 // No need to resolve return type --
2309 // the outer closure return type is `FnRetTy::Default`.
2311 // Now resolve the inner closure
2313 // No need to resolve arguments: the inner closure has none.
2314 // Resolve the return type:
2315 visit::walk_fn_ret_ty(this, &fn_decl.output);
2317 this.visit_expr(body);
2322 ExprKind::Async(..) | ExprKind::Closure(..) => {
2323 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
2326 visit::walk_expr(self, expr);
2331 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
2333 ExprKind::Field(_, ident) => {
2334 // FIXME(#6890): Even though you can't treat a method like a
2335 // field, we need to add any trait methods we find that match
2336 // the field name so that we can do some nice error reporting
2337 // later on in typeck.
2338 let traits = self.get_traits_containing_item(ident, ValueNS);
2339 self.r.trait_map.insert(expr.id, traits);
2341 ExprKind::MethodCall(ref segment, ..) => {
2342 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
2343 let traits = self.get_traits_containing_item(segment.ident, ValueNS);
2344 self.r.trait_map.insert(expr.id, traits);
2352 fn get_traits_containing_item(
2356 ) -> Vec<TraitCandidate> {
2357 debug!("(getting traits containing item) looking for '{}'", ident.name);
2359 let mut found_traits = Vec::new();
2360 // Look for the current trait.
2361 if let Some((module, _)) = self.current_trait_ref {
2364 .resolve_ident_in_module(
2365 ModuleOrUniformRoot::Module(module),
2374 let def_id = module.def_id().unwrap();
2375 found_traits.push(TraitCandidate { def_id, import_ids: smallvec![] });
2379 ident.span = ident.span.normalize_to_macros_2_0();
2380 let mut search_module = self.parent_scope.module;
2382 self.r.get_traits_in_module_containing_item(
2390 unwrap_or!(self.r.hygienic_lexical_parent(search_module, &mut ident.span), break);
2393 if let Some(prelude) = self.r.prelude {
2394 if !search_module.no_implicit_prelude {
2395 self.r.get_traits_in_module_containing_item(
2409 impl<'a> Resolver<'a> {
2410 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
2411 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
2412 visit::walk_crate(&mut late_resolution_visitor, krate);
2413 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
2414 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");