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_lowering::ResolverAstLowering;
18 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
19 use rustc_errors::DiagnosticId;
20 use rustc_hir::def::Namespace::{self, *};
21 use rustc_hir::def::{self, CtorKind, DefKind, PartialRes, PerNS};
22 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
23 use rustc_hir::{PrimTy, TraitCandidate};
24 use rustc_middle::{bug, span_bug};
25 use rustc_session::lint;
26 use rustc_span::symbol::{kw, sym, Ident, Symbol};
28 use smallvec::{smallvec, SmallVec};
30 use rustc_span::source_map::{respan, Spanned};
31 use std::collections::{hash_map::Entry, BTreeSet};
32 use std::mem::{replace, take};
38 type Res = def::Res<NodeId>;
40 type IdentMap<T> = FxHashMap<Ident, T>;
42 /// Map from the name in a pattern to its binding mode.
43 type BindingMap = IdentMap<BindingInfo>;
45 #[derive(Copy, Clone, Debug)]
48 binding_mode: BindingMode,
51 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
59 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
66 fn descr(self) -> &'static str {
68 PatternSource::Match => "match binding",
69 PatternSource::Let => "let binding",
70 PatternSource::For => "for binding",
71 PatternSource::FnParam => "function parameter",
76 /// Denotes whether the context for the set of already bound bindings is a `Product`
77 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
78 /// See those functions for more information.
81 /// A product pattern context, e.g., `Variant(a, b)`.
83 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
87 /// Does this the item (from the item rib scope) allow generic parameters?
88 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
89 crate enum HasGenericParams {
94 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
95 crate enum ConstantItemKind {
100 /// The rib kind restricts certain accesses,
101 /// e.g. to a `Res::Local` of an outer item.
102 #[derive(Copy, Clone, Debug)]
103 crate enum RibKind<'a> {
104 /// No restriction needs to be applied.
107 /// We passed through an impl or trait and are now in one of its
108 /// methods or associated types. Allow references to ty params that impl or trait
109 /// binds. Disallow any other upvars (including other ty params that are
113 /// We passed through a closure. Disallow labels.
114 ClosureOrAsyncRibKind,
116 /// We passed through a function definition. Disallow upvars.
117 /// Permit only those const parameters that are specified in the function's generics.
120 /// We passed through an item scope. Disallow upvars.
121 ItemRibKind(HasGenericParams),
123 /// We're in a constant item. Can't refer to dynamic stuff.
125 /// The `bool` indicates if this constant may reference generic parameters
126 /// and is used to only allow generic parameters to be used in trivial constant expressions.
127 ConstantItemRibKind(bool, Option<(Ident, ConstantItemKind)>),
129 /// We passed through a module.
130 ModuleRibKind(Module<'a>),
132 /// We passed through a `macro_rules!` statement
133 MacroDefinition(DefId),
135 /// All bindings in this rib are generic parameters that can't be used
136 /// from the default of a generic parameter because they're not declared
137 /// before said generic parameter. Also see the `visit_generics` override.
138 ForwardGenericParamBanRibKind,
140 /// We are inside of the type of a const parameter. Can't refer to any
146 /// Whether this rib kind contains generic parameters, as opposed to local
148 crate fn contains_params(&self) -> bool {
151 | ClosureOrAsyncRibKind
153 | ConstantItemRibKind(..)
156 | ConstParamTyRibKind => false,
157 AssocItemRibKind | ItemRibKind(_) | ForwardGenericParamBanRibKind => true,
162 /// A single local scope.
164 /// A rib represents a scope names can live in. Note that these appear in many places, not just
165 /// around braces. At any place where the list of accessible names (of the given namespace)
166 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
167 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
170 /// Different [rib kinds](enum.RibKind) are transparent for different names.
172 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
173 /// resolving, the name is looked up from inside out.
175 crate struct Rib<'a, R = Res> {
176 pub bindings: IdentMap<R>,
177 pub kind: RibKind<'a>,
180 impl<'a, R> Rib<'a, R> {
181 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
182 Rib { bindings: Default::default(), kind }
186 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
187 crate enum AliasPossibility {
192 #[derive(Copy, Clone, Debug)]
193 crate enum PathSource<'a> {
194 // Type paths `Path`.
196 // Trait paths in bounds or impls.
197 Trait(AliasPossibility),
198 // Expression paths `path`, with optional parent context.
199 Expr(Option<&'a Expr>),
200 // Paths in path patterns `Path`.
202 // Paths in struct expressions and patterns `Path { .. }`.
204 // Paths in tuple struct patterns `Path(..)`.
205 TupleStruct(Span, &'a [Span]),
206 // `m::A::B` in `<T as m::A>::B::C`.
207 TraitItem(Namespace),
210 impl<'a> PathSource<'a> {
211 fn namespace(self) -> Namespace {
213 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
214 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
215 PathSource::TraitItem(ns) => ns,
219 fn defer_to_typeck(self) -> bool {
222 | PathSource::Expr(..)
225 | PathSource::TupleStruct(..) => true,
226 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
230 fn descr_expected(self) -> &'static str {
232 PathSource::Type => "type",
233 PathSource::Trait(_) => "trait",
234 PathSource::Pat => "unit struct, unit variant or constant",
235 PathSource::Struct => "struct, variant or union type",
236 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
237 PathSource::TraitItem(ns) => match ns {
238 TypeNS => "associated type",
239 ValueNS => "method or associated constant",
240 MacroNS => bug!("associated macro"),
242 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
243 // "function" here means "anything callable" rather than `DefKind::Fn`,
244 // this is not precise but usually more helpful than just "value".
245 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
246 // the case of `::some_crate()`
247 ExprKind::Path(_, path)
248 if path.segments.len() == 2
249 && path.segments[0].ident.name == kw::PathRoot =>
253 ExprKind::Path(_, path) => {
254 let mut msg = "function";
255 if let Some(segment) = path.segments.iter().last() {
256 if let Some(c) = segment.ident.to_string().chars().next() {
257 if c.is_uppercase() {
258 msg = "function, tuple struct or tuple variant";
271 fn is_call(self) -> bool {
272 matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
275 crate fn is_expected(self, res: Res) -> bool {
277 PathSource::Type => matches!(
284 | DefKind::TraitAlias
289 | DefKind::ForeignTy,
294 PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
295 PathSource::Trait(AliasPossibility::Maybe) => {
296 matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
298 PathSource::Expr(..) => matches!(
301 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
306 | DefKind::AssocConst
307 | DefKind::ConstParam,
312 PathSource::Pat => matches!(
315 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::AssocConst,
317 ) | Res::SelfCtor(..)
319 PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
320 PathSource::Struct => matches!(
331 PathSource::TraitItem(ns) => match res {
332 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
333 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
339 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
340 use rustc_errors::error_code;
341 match (self, has_unexpected_resolution) {
342 (PathSource::Trait(_), true) => error_code!(E0404),
343 (PathSource::Trait(_), false) => error_code!(E0405),
344 (PathSource::Type, true) => error_code!(E0573),
345 (PathSource::Type, false) => error_code!(E0412),
346 (PathSource::Struct, true) => error_code!(E0574),
347 (PathSource::Struct, false) => error_code!(E0422),
348 (PathSource::Expr(..), true) => error_code!(E0423),
349 (PathSource::Expr(..), false) => error_code!(E0425),
350 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
351 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
352 (PathSource::TraitItem(..), true) => error_code!(E0575),
353 (PathSource::TraitItem(..), false) => error_code!(E0576),
359 struct DiagnosticMetadata<'ast> {
360 /// The current trait's associated items' ident, used for diagnostic suggestions.
361 current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
363 /// The current self type if inside an impl (used for better errors).
364 current_self_type: Option<Ty>,
366 /// The current self item if inside an ADT (used for better errors).
367 current_self_item: Option<NodeId>,
369 /// The current trait (used to suggest).
370 current_item: Option<&'ast Item>,
372 /// When processing generics and encountering a type not found, suggest introducing a type
374 currently_processing_generics: bool,
376 /// The current enclosing (non-closure) function (used for better errors).
377 current_function: Option<(FnKind<'ast>, Span)>,
379 /// A list of labels as of yet unused. Labels will be removed from this map when
380 /// they are used (in a `break` or `continue` statement)
381 unused_labels: FxHashMap<NodeId, Span>,
383 /// Only used for better errors on `fn(): fn()`.
384 current_type_ascription: Vec<Span>,
386 /// Only used for better errors on `let <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.init.as_ref().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 default_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
559 let mut found_default = false;
560 default_ban_rib.bindings.extend(generics.params.iter().filter_map(
561 |param| match param.kind {
562 GenericParamKind::Type { default: Some(_), .. }
563 | GenericParamKind::Const { default: Some(_), .. } => {
564 found_default = true;
565 Some((Ident::with_dummy_span(param.ident.name), Res::Err))
571 // rust-lang/rust#61631: The type `Self` is essentially
572 // another type parameter. For ADTs, we consider it
573 // well-defined only after all of the ADT type parameters have
574 // been provided. Therefore, we do not allow use of `Self`
575 // anywhere in ADT type parameter defaults.
577 // (We however cannot ban `Self` for defaults on *all* generic
578 // lists; e.g. trait generics can usefully refer to `Self`,
579 // such as in the case of `trait Add<Rhs = Self>`.)
580 if self.diagnostic_metadata.current_self_item.is_some() {
581 // (`Some` if + only if we are in ADT's generics.)
582 default_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
585 for param in &generics.params {
587 GenericParamKind::Lifetime => self.visit_generic_param(param),
588 GenericParamKind::Type { ref default } => {
589 for bound in ¶m.bounds {
590 self.visit_param_bound(bound);
593 if let Some(ref ty) = default {
594 self.ribs[TypeNS].push(default_ban_rib);
595 self.with_rib(ValueNS, ForwardGenericParamBanRibKind, |this| {
596 // HACK: We use an empty `ForwardGenericParamBanRibKind` here which
597 // is only used to forbid the use of const parameters inside of
600 // While the rib name doesn't really fit here, it does allow us to use the same
601 // code for both const and type parameters.
604 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
607 // Allow all following defaults to refer to this type parameter.
608 default_ban_rib.bindings.remove(&Ident::with_dummy_span(param.ident.name));
610 GenericParamKind::Const { ref ty, kw_span: _, default: _ } => {
611 // FIXME(const_generics_defaults): handle `default` value here
612 for bound in ¶m.bounds {
613 self.visit_param_bound(bound);
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();
623 for p in &generics.where_clause.predicates {
624 self.visit_where_predicate(p);
628 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
629 debug!("visit_generic_arg({:?})", arg);
630 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
632 GenericArg::Type(ref ty) => {
633 // We parse const arguments as path types as we cannot distinguish them during
634 // parsing. We try to resolve that ambiguity by attempting resolution the type
635 // namespace first, and if that fails we try again in the value namespace. If
636 // resolution in the value namespace succeeds, we have an generic const argument on
638 if let TyKind::Path(ref qself, ref path) = ty.kind {
639 // We cannot disambiguate multi-segment paths right now as that requires type
641 if path.segments.len() == 1 && path.segments[0].args.is_none() {
642 let mut check_ns = |ns| {
643 self.resolve_ident_in_lexical_scope(
644 path.segments[0].ident,
651 if !check_ns(TypeNS) && check_ns(ValueNS) {
652 // This must be equivalent to `visit_anon_const`, but we cannot call it
653 // directly due to visitor lifetimes so we have to copy-paste some code.
655 // Note that we might not be inside of an repeat expression here,
656 // but considering that `IsRepeatExpr` is only relevant for
657 // non-trivial constants this is doesn't matter.
658 self.with_constant_rib(IsRepeatExpr::No, true, None, |this| {
659 this.smart_resolve_path(
663 PathSource::Expr(None),
666 if let Some(ref qself) = *qself {
667 this.visit_ty(&qself.ty);
669 this.visit_path(path, ty.id);
672 self.diagnostic_metadata.currently_processing_generics = prev;
680 GenericArg::Lifetime(lt) => self.visit_lifetime(lt),
681 GenericArg::Const(ct) => self.visit_anon_const(ct),
683 self.diagnostic_metadata.currently_processing_generics = prev;
686 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
687 debug!("visit_where_predicate {:?}", p);
689 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
690 visit::walk_where_predicate(self, p);
691 self.diagnostic_metadata.current_where_predicate = previous_value;
695 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
696 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
697 // During late resolution we only track the module component of the parent scope,
698 // although it may be useful to track other components as well for diagnostics.
699 let graph_root = resolver.graph_root;
700 let parent_scope = ParentScope::module(graph_root, resolver);
701 let start_rib_kind = ModuleRibKind(graph_root);
702 LateResolutionVisitor {
706 value_ns: vec![Rib::new(start_rib_kind)],
707 type_ns: vec![Rib::new(start_rib_kind)],
708 macro_ns: vec![Rib::new(start_rib_kind)],
710 label_ribs: Vec::new(),
711 current_trait_ref: None,
712 diagnostic_metadata: DiagnosticMetadata::default(),
713 // errors at module scope should always be reported
718 fn resolve_ident_in_lexical_scope(
722 record_used_id: Option<NodeId>,
724 ) -> Option<LexicalScopeBinding<'a>> {
725 self.r.resolve_ident_in_lexical_scope(
738 opt_ns: Option<Namespace>, // `None` indicates a module path in import
741 crate_lint: CrateLint,
742 ) -> PathResult<'a> {
743 self.r.resolve_path_with_ribs(
756 // We maintain a list of value ribs and type ribs.
758 // Simultaneously, we keep track of the current position in the module
759 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
760 // the value or type namespaces, we first look through all the ribs and
761 // then query the module graph. When we resolve a name in the module
762 // namespace, we can skip all the ribs (since nested modules are not
763 // allowed within blocks in Rust) and jump straight to the current module
766 // Named implementations are handled separately. When we find a method
767 // call, we consult the module node to find all of the implementations in
768 // scope. This information is lazily cached in the module node. We then
769 // generate a fake "implementation scope" containing all the
770 // implementations thus found, for compatibility with old resolve pass.
772 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
777 work: impl FnOnce(&mut Self) -> T,
779 self.ribs[ns].push(Rib::new(kind));
780 let ret = work(self);
785 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
786 let id = self.r.local_def_id(id);
787 let module = self.r.module_map.get(&id).cloned(); // clones a reference
788 if let Some(module) = module {
789 // Move down in the graph.
790 let orig_module = replace(&mut self.parent_scope.module, module);
791 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
792 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
794 this.parent_scope.module = orig_module;
803 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
804 /// label and reports an error if the label is not found or is unreachable.
805 fn resolve_label(&self, mut label: Ident) -> Option<NodeId> {
806 let mut suggestion = None;
808 // Preserve the original span so that errors contain "in this macro invocation"
810 let original_span = label.span;
812 for i in (0..self.label_ribs.len()).rev() {
813 let rib = &self.label_ribs[i];
815 if let MacroDefinition(def) = rib.kind {
816 // If an invocation of this macro created `ident`, give up on `ident`
817 // and switch to `ident`'s source from the macro definition.
818 if def == self.r.macro_def(label.span.ctxt()) {
819 label.span.remove_mark();
823 let ident = label.normalize_to_macro_rules();
824 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
825 return if self.is_label_valid_from_rib(i) {
830 ResolutionError::UnreachableLabel {
832 definition_span: ident.span,
841 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
842 // the first such label that is encountered.
843 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
848 ResolutionError::UndeclaredLabel { name: label.name, suggestion },
853 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
854 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
855 let ribs = &self.label_ribs[rib_index + 1..];
859 NormalRibKind | MacroDefinition(..) => {
860 // Nothing to do. Continue.
864 | ClosureOrAsyncRibKind
867 | ConstantItemRibKind(..)
869 | ForwardGenericParamBanRibKind
870 | ConstParamTyRibKind => {
879 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
880 debug!("resolve_adt");
881 self.with_current_self_item(item, |this| {
882 this.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
883 let item_def_id = this.r.local_def_id(item.id).to_def_id();
884 this.with_self_rib(Res::SelfTy(None, Some((item_def_id, false))), |this| {
885 visit::walk_item(this, item);
891 fn future_proof_import(&mut self, use_tree: &UseTree) {
892 let segments = &use_tree.prefix.segments;
893 if !segments.is_empty() {
894 let ident = segments[0].ident;
895 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
899 let nss = match use_tree.kind {
900 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
903 let report_error = |this: &Self, ns| {
904 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
905 if this.should_report_errs() {
908 .span_err(ident.span, &format!("imports cannot refer to {}", what));
913 match self.resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span) {
914 Some(LexicalScopeBinding::Res(..)) => {
915 report_error(self, ns);
917 Some(LexicalScopeBinding::Item(binding)) => {
918 let orig_unusable_binding =
919 replace(&mut self.r.unusable_binding, Some(binding));
920 if let Some(LexicalScopeBinding::Res(..)) = self
921 .resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span)
923 report_error(self, ns);
925 self.r.unusable_binding = orig_unusable_binding;
930 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
931 for (use_tree, _) in use_trees {
932 self.future_proof_import(use_tree);
937 fn resolve_item(&mut self, item: &'ast Item) {
938 let name = item.ident.name;
939 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
942 ItemKind::TyAlias(box TyAliasKind(_, ref generics, _, _))
943 | ItemKind::Fn(box FnKind(_, _, ref generics, _)) => {
944 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
945 visit::walk_item(this, item)
949 ItemKind::Enum(_, ref generics)
950 | ItemKind::Struct(_, ref generics)
951 | ItemKind::Union(_, ref generics) => {
952 self.resolve_adt(item, generics);
955 ItemKind::Impl(box ImplKind {
959 items: ref impl_items,
962 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
965 ItemKind::Trait(box TraitKind(.., ref generics, ref bounds, ref trait_items)) => {
966 // Create a new rib for the trait-wide type parameters.
967 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
968 let local_def_id = this.r.local_def_id(item.id).to_def_id();
969 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
970 this.visit_generics(generics);
971 walk_list!(this, visit_param_bound, bounds);
973 let walk_assoc_item = |this: &mut Self, generics, item| {
974 this.with_generic_param_rib(generics, AssocItemRibKind, |this| {
975 visit::walk_assoc_item(this, item, AssocCtxt::Trait)
979 this.with_trait_items(trait_items, |this| {
980 for item in trait_items {
982 AssocItemKind::Const(_, ty, default) => {
984 // Only impose the restrictions of `ConstRibKind` for an
985 // actual constant expression in a provided default.
986 if let Some(expr) = default {
987 // We allow arbitrary const expressions inside of associated consts,
988 // even if they are potentially not const evaluatable.
990 // Type parameters can already be used and as associated consts are
991 // not used as part of the type system, this is far less surprising.
992 this.with_constant_rib(
996 |this| this.visit_expr(expr),
1000 AssocItemKind::Fn(box FnKind(_, _, generics, _)) => {
1001 walk_assoc_item(this, generics, item);
1003 AssocItemKind::TyAlias(box TyAliasKind(_, generics, _, _)) => {
1004 walk_assoc_item(this, generics, item);
1006 AssocItemKind::MacCall(_) => {
1007 panic!("unexpanded macro in resolve!")
1016 ItemKind::TraitAlias(ref generics, ref bounds) => {
1017 // Create a new rib for the trait-wide type parameters.
1018 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1019 let local_def_id = this.r.local_def_id(item.id).to_def_id();
1020 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
1021 this.visit_generics(generics);
1022 walk_list!(this, visit_param_bound, bounds);
1027 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
1028 self.with_scope(item.id, |this| {
1029 visit::walk_item(this, item);
1033 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
1034 debug!("resolve_item ItemKind::Const");
1035 self.with_item_rib(HasGenericParams::No, |this| {
1037 if let Some(expr) = expr {
1038 let constant_item_kind = match item.kind {
1039 ItemKind::Const(..) => ConstantItemKind::Const,
1040 ItemKind::Static(..) => ConstantItemKind::Static,
1041 _ => unreachable!(),
1043 // We already forbid generic params because of the above item rib,
1044 // so it doesn't matter whether this is a trivial constant.
1045 this.with_constant_rib(
1048 Some((item.ident, constant_item_kind)),
1049 |this| this.visit_expr(expr),
1055 ItemKind::Use(ref use_tree) => {
1056 self.future_proof_import(use_tree);
1059 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) | ItemKind::GlobalAsm(..) => {
1060 // do nothing, these are just around to be encoded
1063 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
1067 fn with_generic_param_rib<'c, F>(&'c mut self, generics: &'c Generics, kind: RibKind<'a>, f: F)
1069 F: FnOnce(&mut Self),
1071 debug!("with_generic_param_rib");
1072 let mut function_type_rib = Rib::new(kind);
1073 let mut function_value_rib = Rib::new(kind);
1074 let mut seen_bindings = FxHashMap::default();
1076 // We also can't shadow bindings from the parent item
1077 if let AssocItemRibKind = kind {
1078 let mut add_bindings_for_ns = |ns| {
1079 let parent_rib = self.ribs[ns]
1081 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
1082 .expect("associated item outside of an item");
1084 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
1086 add_bindings_for_ns(ValueNS);
1087 add_bindings_for_ns(TypeNS);
1090 for param in &generics.params {
1091 if let GenericParamKind::Lifetime { .. } = param.kind {
1095 let ident = param.ident.normalize_to_macros_2_0();
1096 debug!("with_generic_param_rib: {}", param.id);
1098 match seen_bindings.entry(ident) {
1099 Entry::Occupied(entry) => {
1100 let span = *entry.get();
1101 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
1102 self.report_error(param.ident.span, err);
1104 Entry::Vacant(entry) => {
1105 entry.insert(param.ident.span);
1109 // Plain insert (no renaming).
1110 let (rib, def_kind) = match param.kind {
1111 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
1112 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
1113 _ => unreachable!(),
1115 let res = Res::Def(def_kind, self.r.local_def_id(param.id).to_def_id());
1116 self.r.record_partial_res(param.id, PartialRes::new(res));
1117 rib.bindings.insert(ident, res);
1120 self.ribs[ValueNS].push(function_value_rib);
1121 self.ribs[TypeNS].push(function_type_rib);
1125 self.ribs[TypeNS].pop();
1126 self.ribs[ValueNS].pop();
1129 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
1130 self.label_ribs.push(Rib::new(kind));
1132 self.label_ribs.pop();
1135 fn with_item_rib(&mut self, has_generic_params: HasGenericParams, f: impl FnOnce(&mut Self)) {
1136 let kind = ItemRibKind(has_generic_params);
1137 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
1140 // HACK(min_const_generics,const_evaluatable_unchecked): We
1141 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
1142 // with a future compat lint for now. We do this by adding an
1143 // additional special case for repeat expressions.
1145 // Note that we intentionally still forbid `[0; N + 1]` during
1146 // name resolution so that we don't extend the future
1147 // compat lint to new cases.
1148 fn with_constant_rib(
1150 is_repeat: IsRepeatExpr,
1152 item: Option<(Ident, ConstantItemKind)>,
1153 f: impl FnOnce(&mut Self),
1155 debug!("with_constant_rib: is_repeat={:?} is_trivial={}", is_repeat, is_trivial);
1156 self.with_rib(ValueNS, ConstantItemRibKind(is_trivial, item), |this| {
1159 ConstantItemRibKind(is_repeat == IsRepeatExpr::Yes || is_trivial, item),
1161 this.with_label_rib(ConstantItemRibKind(is_trivial, item), f);
1167 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
1168 // Handle nested impls (inside fn bodies)
1169 let previous_value =
1170 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
1171 let result = f(self);
1172 self.diagnostic_metadata.current_self_type = previous_value;
1176 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
1177 let previous_value =
1178 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
1179 let result = f(self);
1180 self.diagnostic_metadata.current_self_item = previous_value;
1184 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
1185 fn with_trait_items<T>(
1187 trait_items: &'ast [P<AssocItem>],
1188 f: impl FnOnce(&mut Self) -> T,
1190 let trait_assoc_items =
1191 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
1192 let result = f(self);
1193 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
1197 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
1198 fn with_optional_trait_ref<T>(
1200 opt_trait_ref: Option<&TraitRef>,
1201 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
1203 let mut new_val = None;
1204 let mut new_id = None;
1205 if let Some(trait_ref) = opt_trait_ref {
1206 let path: Vec<_> = Segment::from_path(&trait_ref.path);
1207 let res = self.smart_resolve_path_fragment(
1211 trait_ref.path.span,
1212 PathSource::Trait(AliasPossibility::No),
1213 CrateLint::SimplePath(trait_ref.ref_id),
1215 let res = res.base_res();
1216 if res != Res::Err {
1217 new_id = Some(res.def_id());
1218 let span = trait_ref.path.span;
1219 if let PathResult::Module(ModuleOrUniformRoot::Module(module)) = self.resolve_path(
1224 CrateLint::SimplePath(trait_ref.ref_id),
1226 new_val = Some((module, trait_ref.clone()));
1230 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1231 let result = f(self, new_id);
1232 self.current_trait_ref = original_trait_ref;
1236 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
1237 let mut self_type_rib = Rib::new(NormalRibKind);
1239 // Plain insert (no renaming, since types are not currently hygienic)
1240 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
1241 self.ribs[ns].push(self_type_rib);
1243 self.ribs[ns].pop();
1246 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
1247 self.with_self_rib_ns(TypeNS, self_res, f)
1250 fn resolve_implementation(
1252 generics: &'ast Generics,
1253 opt_trait_reference: &'ast Option<TraitRef>,
1254 self_type: &'ast Ty,
1256 impl_items: &'ast [P<AssocItem>],
1258 debug!("resolve_implementation");
1259 // If applicable, create a rib for the type parameters.
1260 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1261 // Dummy self type for better errors if `Self` is used in the trait path.
1262 this.with_self_rib(Res::SelfTy(None, None), |this| {
1263 // Resolve the trait reference, if necessary.
1264 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1265 let item_def_id = this.r.local_def_id(item_id).to_def_id();
1266 this.with_self_rib(Res::SelfTy(trait_id, Some((item_def_id, false))), |this| {
1267 if let Some(trait_ref) = opt_trait_reference.as_ref() {
1268 // Resolve type arguments in the trait path.
1269 visit::walk_trait_ref(this, trait_ref);
1271 // Resolve the self type.
1272 this.visit_ty(self_type);
1273 // Resolve the generic parameters.
1274 this.visit_generics(generics);
1275 // Resolve the items within the impl.
1276 this.with_current_self_type(self_type, |this| {
1277 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
1278 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
1279 for item in impl_items {
1280 use crate::ResolutionError::*;
1282 AssocItemKind::Const(_default, _ty, _expr) => {
1283 debug!("resolve_implementation AssocItemKind::Const",);
1284 // If this is a trait impl, ensure the const
1286 this.check_trait_item(
1290 |n, s| ConstNotMemberOfTrait(n, s),
1293 // We allow arbitrary const expressions inside of associated consts,
1294 // even if they are potentially not const evaluatable.
1296 // Type parameters can already be used and as associated consts are
1297 // not used as part of the type system, this is far less surprising.
1298 this.with_constant_rib(
1303 visit::walk_assoc_item(
1311 AssocItemKind::Fn(box FnKind(.., generics, _)) => {
1312 // We also need a new scope for the impl item type parameters.
1313 this.with_generic_param_rib(
1317 // If this is a trait impl, ensure the method
1319 this.check_trait_item(
1323 |n, s| MethodNotMemberOfTrait(n, s),
1326 visit::walk_assoc_item(
1334 AssocItemKind::TyAlias(box TyAliasKind(
1340 // We also need a new scope for the impl item type parameters.
1341 this.with_generic_param_rib(
1345 // If this is a trait impl, ensure the type
1347 this.check_trait_item(
1351 |n, s| TypeNotMemberOfTrait(n, s),
1354 visit::walk_assoc_item(
1362 AssocItemKind::MacCall(_) => {
1363 panic!("unexpanded macro in resolve!")
1375 fn check_trait_item<F>(&mut self, ident: Ident, ns: Namespace, span: Span, err: F)
1377 F: FnOnce(Symbol, &str) -> ResolutionError<'_>,
1379 // If there is a TraitRef in scope for an impl, then the method must be in the
1381 if let Some((module, _)) = self.current_trait_ref {
1384 .resolve_ident_in_module(
1385 ModuleOrUniformRoot::Module(module),
1394 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
1395 self.report_error(span, err(ident.name, &path_names_to_string(path)));
1400 fn resolve_params(&mut self, params: &'ast [Param]) {
1401 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1402 for Param { pat, ty, .. } in params {
1403 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1405 debug!("(resolving function / closure) recorded parameter");
1409 fn resolve_local(&mut self, local: &'ast Local) {
1410 debug!("resolving local ({:?})", local);
1411 // Resolve the type.
1412 walk_list!(self, visit_ty, &local.ty);
1414 // Resolve the initializer.
1415 walk_list!(self, visit_expr, &local.init);
1417 // Resolve the pattern.
1418 self.resolve_pattern_top(&local.pat, PatternSource::Let);
1421 /// build a map from pattern identifiers to binding-info's.
1422 /// this is done hygienically. This could arise for a macro
1423 /// that expands into an or-pattern where one 'x' was from the
1424 /// user and one 'x' came from the macro.
1425 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1426 let mut binding_map = FxHashMap::default();
1428 pat.walk(&mut |pat| {
1430 PatKind::Ident(binding_mode, ident, ref sub_pat)
1431 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
1433 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
1435 PatKind::Or(ref ps) => {
1436 // Check the consistency of this or-pattern and
1437 // then add all bindings to the larger map.
1438 for bm in self.check_consistent_bindings(ps) {
1439 binding_map.extend(bm);
1452 fn is_base_res_local(&self, nid: NodeId) -> bool {
1453 matches!(self.r.partial_res_map.get(&nid).map(|res| res.base_res()), Some(Res::Local(..)))
1456 /// Checks that all of the arms in an or-pattern have exactly the
1457 /// same set of bindings, with the same binding modes for each.
1458 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
1459 let mut missing_vars = FxHashMap::default();
1460 let mut inconsistent_vars = FxHashMap::default();
1462 // 1) Compute the binding maps of all arms.
1463 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
1465 // 2) Record any missing bindings or binding mode inconsistencies.
1466 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
1467 // Check against all arms except for the same pattern which is always self-consistent.
1471 .filter(|(_, pat)| pat.id != pat_outer.id)
1472 .flat_map(|(idx, _)| maps[idx].iter())
1473 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
1475 for (name, info, &binding_inner) in inners {
1478 // The inner binding is missing in the outer.
1480 missing_vars.entry(name).or_insert_with(|| BindingError {
1482 origin: BTreeSet::new(),
1483 target: BTreeSet::new(),
1484 could_be_path: name.as_str().starts_with(char::is_uppercase),
1486 binding_error.origin.insert(binding_inner.span);
1487 binding_error.target.insert(pat_outer.span);
1489 Some(binding_outer) => {
1490 if binding_outer.binding_mode != binding_inner.binding_mode {
1491 // The binding modes in the outer and inner bindings differ.
1494 .or_insert((binding_inner.span, binding_outer.span));
1501 // 3) Report all missing variables we found.
1502 let mut missing_vars = missing_vars.iter_mut().collect::<Vec<_>>();
1503 missing_vars.sort_by_key(|(sym, _err)| sym.as_str());
1505 for (name, mut v) in missing_vars {
1506 if inconsistent_vars.contains_key(name) {
1507 v.could_be_path = false;
1510 *v.origin.iter().next().unwrap(),
1511 ResolutionError::VariableNotBoundInPattern(v),
1515 // 4) Report all inconsistencies in binding modes we found.
1516 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
1517 inconsistent_vars.sort();
1518 for (name, v) in inconsistent_vars {
1519 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
1522 // 5) Finally bubble up all the binding maps.
1526 /// Check the consistency of the outermost or-patterns.
1527 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
1528 pat.walk(&mut |pat| match pat.kind {
1529 PatKind::Or(ref ps) => {
1530 self.check_consistent_bindings(ps);
1537 fn resolve_arm(&mut self, arm: &'ast Arm) {
1538 self.with_rib(ValueNS, NormalRibKind, |this| {
1539 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
1540 walk_list!(this, visit_expr, &arm.guard);
1541 this.visit_expr(&arm.body);
1545 /// Arising from `source`, resolve a top level pattern.
1546 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
1547 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1548 self.resolve_pattern(pat, pat_src, &mut bindings);
1554 pat_src: PatternSource,
1555 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1557 self.resolve_pattern_inner(pat, pat_src, bindings);
1558 // This has to happen *after* we determine which pat_idents are variants:
1559 self.check_consistent_bindings_top(pat);
1560 visit::walk_pat(self, pat);
1563 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
1567 /// A stack of sets of bindings accumulated.
1569 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
1570 /// be interpreted as re-binding an already bound binding. This results in an error.
1571 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
1572 /// in reusing this binding rather than creating a fresh one.
1574 /// When called at the top level, the stack must have a single element
1575 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
1576 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
1577 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
1578 /// When each `p_i` has been dealt with, the top set is merged with its parent.
1579 /// When a whole or-pattern has been dealt with, the thing happens.
1581 /// See the implementation and `fresh_binding` for more details.
1582 fn resolve_pattern_inner(
1585 pat_src: PatternSource,
1586 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1588 // Visit all direct subpatterns of this pattern.
1589 pat.walk(&mut |pat| {
1590 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
1592 PatKind::Ident(bmode, ident, ref sub) => {
1593 // First try to resolve the identifier as some existing entity,
1594 // then fall back to a fresh binding.
1595 let has_sub = sub.is_some();
1597 .try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub)
1598 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
1599 self.r.record_partial_res(pat.id, PartialRes::new(res));
1601 PatKind::TupleStruct(ref path, ref sub_patterns) => {
1602 self.smart_resolve_path(
1606 PathSource::TupleStruct(
1608 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
1612 PatKind::Path(ref qself, ref path) => {
1613 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
1615 PatKind::Struct(ref path, ..) => {
1616 self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
1618 PatKind::Or(ref ps) => {
1619 // Add a new set of bindings to the stack. `Or` here records that when a
1620 // binding already exists in this set, it should not result in an error because
1621 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
1622 bindings.push((PatBoundCtx::Or, Default::default()));
1624 // Now we need to switch back to a product context so that each
1625 // part of the or-pattern internally rejects already bound names.
1626 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
1627 bindings.push((PatBoundCtx::Product, Default::default()));
1628 self.resolve_pattern_inner(p, pat_src, bindings);
1629 // Move up the non-overlapping bindings to the or-pattern.
1630 // Existing bindings just get "merged".
1631 let collected = bindings.pop().unwrap().1;
1632 bindings.last_mut().unwrap().1.extend(collected);
1634 // This or-pattern itself can itself be part of a product,
1635 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
1636 // Both cases bind `a` again in a product pattern and must be rejected.
1637 let collected = bindings.pop().unwrap().1;
1638 bindings.last_mut().unwrap().1.extend(collected);
1640 // Prevent visiting `ps` as we've already done so above.
1653 pat_src: PatternSource,
1654 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1656 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
1657 // (We must not add it if it's in the bindings map because that breaks the assumptions
1658 // later passes make about or-patterns.)
1659 let ident = ident.normalize_to_macro_rules();
1661 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
1662 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
1663 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
1664 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
1665 // This is *required* for consistency which is checked later.
1666 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
1668 if already_bound_and {
1669 // Overlap in a product pattern somewhere; report an error.
1670 use ResolutionError::*;
1671 let error = match pat_src {
1672 // `fn f(a: u8, a: u8)`:
1673 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
1675 _ => IdentifierBoundMoreThanOnceInSamePattern,
1677 self.report_error(ident.span, error(ident.name));
1680 // Record as bound if it's valid:
1681 let ident_valid = ident.name != kw::Empty;
1683 bindings.last_mut().unwrap().1.insert(ident);
1686 if already_bound_or {
1687 // `Variant1(a) | Variant2(a)`, ok
1688 // Reuse definition from the first `a`.
1689 self.innermost_rib_bindings(ValueNS)[&ident]
1691 let res = Res::Local(pat_id);
1693 // A completely fresh binding add to the set if it's valid.
1694 self.innermost_rib_bindings(ValueNS).insert(ident, res);
1700 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
1701 &mut self.ribs[ns].last_mut().unwrap().bindings
1704 fn try_resolve_as_non_binding(
1706 pat_src: PatternSource,
1712 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
1713 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
1714 // also be interpreted as a path to e.g. a constant, variant, etc.
1715 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
1717 let ls_binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, pat.span)?;
1718 let (res, binding) = match ls_binding {
1719 LexicalScopeBinding::Item(binding)
1720 if is_syntactic_ambiguity && binding.is_ambiguity() =>
1722 // For ambiguous bindings we don't know all their definitions and cannot check
1723 // whether they can be shadowed by fresh bindings or not, so force an error.
1724 // issues/33118#issuecomment-233962221 (see below) still applies here,
1725 // but we have to ignore it for backward compatibility.
1726 self.r.record_use(ident, ValueNS, binding, false);
1729 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
1730 LexicalScopeBinding::Res(res) => (res, None),
1734 Res::SelfCtor(_) // See #70549.
1736 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
1738 ) if is_syntactic_ambiguity => {
1739 // Disambiguate in favor of a unit struct/variant or constant pattern.
1740 if let Some(binding) = binding {
1741 self.r.record_use(ident, ValueNS, binding, false);
1745 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static, _) => {
1746 // This is unambiguously a fresh binding, either syntactically
1747 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
1748 // to something unusable as a pattern (e.g., constructor function),
1749 // but we still conservatively report an error, see
1750 // issues/33118#issuecomment-233962221 for one reason why.
1753 ResolutionError::BindingShadowsSomethingUnacceptable(
1756 binding.expect("no binding for a ctor or static"),
1761 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
1762 // These entities are explicitly allowed to be shadowed by fresh bindings.
1767 "unexpected resolution for an identifier in pattern: {:?}",
1773 // High-level and context dependent path resolution routine.
1774 // Resolves the path and records the resolution into definition map.
1775 // If resolution fails tries several techniques to find likely
1776 // resolution candidates, suggest imports or other help, and report
1777 // errors in user friendly way.
1778 fn smart_resolve_path(
1781 qself: Option<&QSelf>,
1783 source: PathSource<'ast>,
1785 self.smart_resolve_path_fragment(
1788 &Segment::from_path(path),
1791 CrateLint::SimplePath(id),
1795 fn smart_resolve_path_fragment(
1798 qself: Option<&QSelf>,
1801 source: PathSource<'ast>,
1802 crate_lint: CrateLint,
1805 "smart_resolve_path_fragment(id={:?}, qself={:?}, path={:?})",
1810 let ns = source.namespace();
1812 let report_errors = |this: &mut Self, res: Option<Res>| {
1813 if this.should_report_errs() {
1814 let (err, candidates) = this.smart_resolve_report_errors(path, span, source, res);
1816 let def_id = this.parent_scope.module.nearest_parent_mod;
1817 let instead = res.is_some();
1819 if res.is_none() { this.report_missing_type_error(path) } else { None };
1821 this.r.use_injections.push(UseError {
1830 PartialRes::new(Res::Err)
1833 // For paths originating from calls (like in `HashMap::new()`), tries
1834 // to enrich the plain `failed to resolve: ...` message with hints
1835 // about possible missing imports.
1837 // Similar thing, for types, happens in `report_errors` above.
1838 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
1839 if !source.is_call() {
1840 return Some(parent_err);
1843 // Before we start looking for candidates, we have to get our hands
1844 // on the type user is trying to perform invocation on; basically:
1845 // we're transforming `HashMap::new` into just `HashMap`.
1846 let path = match path.split_last() {
1847 Some((_, path)) if !path.is_empty() => path,
1848 _ => return Some(parent_err),
1851 let (mut err, candidates) =
1852 this.smart_resolve_report_errors(path, span, PathSource::Type, None);
1854 if candidates.is_empty() {
1856 return Some(parent_err);
1859 // There are two different error messages user might receive at
1861 // - E0412 cannot find type `{}` in this scope
1862 // - E0433 failed to resolve: use of undeclared type or module `{}`
1864 // The first one is emitted for paths in type-position, and the
1865 // latter one - for paths in expression-position.
1867 // Thus (since we're in expression-position at this point), not to
1868 // confuse the user, we want to keep the *message* from E0432 (so
1869 // `parent_err`), but we want *hints* from E0412 (so `err`).
1871 // And that's what happens below - we're just mixing both messages
1872 // into a single one.
1873 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
1875 parent_err.cancel();
1877 err.message = take(&mut parent_err.message);
1878 err.code = take(&mut parent_err.code);
1879 err.children = take(&mut parent_err.children);
1883 let def_id = this.parent_scope.module.nearest_parent_mod;
1885 if this.should_report_errs() {
1886 this.r.use_injections.push(UseError {
1897 // We don't return `Some(parent_err)` here, because the error will
1898 // be already printed as part of the `use` injections
1902 let partial_res = match self.resolve_qpath_anywhere(
1908 source.defer_to_typeck(),
1911 Ok(Some(partial_res)) if partial_res.unresolved_segments() == 0 => {
1912 if source.is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err
1916 report_errors(self, Some(partial_res.base_res()))
1920 Ok(Some(partial_res)) if source.defer_to_typeck() => {
1921 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
1922 // or `<T>::A::B`. If `B` should be resolved in value namespace then
1923 // it needs to be added to the trait map.
1925 let item_name = path.last().unwrap().ident;
1926 let traits = self.traits_in_scope(item_name, ns);
1927 self.r.trait_map.insert(id, traits);
1930 if PrimTy::from_name(path[0].ident.name).is_some() {
1931 let mut std_path = Vec::with_capacity(1 + path.len());
1933 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
1934 std_path.extend(path);
1935 if let PathResult::Module(_) | PathResult::NonModule(_) =
1936 self.resolve_path(&std_path, Some(ns), false, span, CrateLint::No)
1938 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
1940 path.iter().last().map_or(span, |segment| segment.ident.span);
1942 let mut hm = self.r.session.confused_type_with_std_module.borrow_mut();
1943 hm.insert(item_span, span);
1944 hm.insert(span, span);
1952 if let Some(err) = report_errors_for_call(self, err) {
1953 self.report_error(err.span, err.node);
1956 PartialRes::new(Res::Err)
1959 _ => report_errors(self, None),
1962 if !matches!(source, PathSource::TraitItem(..)) {
1963 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
1964 self.r.record_partial_res(id, partial_res);
1970 fn self_type_is_available(&mut self, span: Span) -> bool {
1971 let binding = self.resolve_ident_in_lexical_scope(
1972 Ident::with_dummy_span(kw::SelfUpper),
1977 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1980 fn self_value_is_available(&mut self, self_span: Span, path_span: Span) -> bool {
1981 let ident = Ident::new(kw::SelfLower, self_span);
1982 let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, path_span);
1983 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1986 /// A wrapper around [`Resolver::report_error`].
1988 /// This doesn't emit errors for function bodies if this is rustdoc.
1989 fn report_error(&self, span: Span, resolution_error: ResolutionError<'_>) {
1990 if self.should_report_errs() {
1991 self.r.report_error(span, resolution_error);
1996 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
1997 fn should_report_errs(&self) -> bool {
1998 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
2001 // Resolve in alternative namespaces if resolution in the primary namespace fails.
2002 fn resolve_qpath_anywhere(
2005 qself: Option<&QSelf>,
2007 primary_ns: Namespace,
2009 defer_to_typeck: bool,
2010 crate_lint: CrateLint,
2011 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2012 let mut fin_res = None;
2014 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
2015 if i == 0 || ns != primary_ns {
2016 match self.resolve_qpath(id, qself, path, ns, span, crate_lint)? {
2018 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
2020 return Ok(Some(partial_res));
2023 if fin_res.is_none() {
2024 fin_res = partial_res;
2031 assert!(primary_ns != MacroNS);
2033 if qself.is_none() {
2034 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
2035 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
2036 if let Ok((_, res)) =
2037 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
2039 return Ok(Some(PartialRes::new(res)));
2046 /// Handles paths that may refer to associated items.
2050 qself: Option<&QSelf>,
2054 crate_lint: CrateLint,
2055 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2057 "resolve_qpath(id={:?}, qself={:?}, path={:?}, ns={:?}, span={:?})",
2058 id, qself, path, ns, span,
2061 if let Some(qself) = qself {
2062 if qself.position == 0 {
2063 // This is a case like `<T>::B`, where there is no
2064 // trait to resolve. In that case, we leave the `B`
2065 // segment to be resolved by type-check.
2066 return Ok(Some(PartialRes::with_unresolved_segments(
2067 Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX)),
2072 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
2074 // Currently, `path` names the full item (`A::B::C`, in
2075 // our example). so we extract the prefix of that that is
2076 // the trait (the slice upto and including
2077 // `qself.position`). And then we recursively resolve that,
2078 // but with `qself` set to `None`.
2080 // However, setting `qself` to none (but not changing the
2081 // span) loses the information about where this path
2082 // *actually* appears, so for the purposes of the crate
2083 // lint we pass along information that this is the trait
2084 // name from a fully qualified path, and this also
2085 // contains the full span (the `CrateLint::QPathTrait`).
2086 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2087 let partial_res = self.smart_resolve_path_fragment(
2090 &path[..=qself.position],
2092 PathSource::TraitItem(ns),
2093 CrateLint::QPathTrait { qpath_id: id, qpath_span: qself.path_span },
2096 // The remaining segments (the `C` in our example) will
2097 // have to be resolved by type-check, since that requires doing
2098 // trait resolution.
2099 return Ok(Some(PartialRes::with_unresolved_segments(
2100 partial_res.base_res(),
2101 partial_res.unresolved_segments() + path.len() - qself.position - 1,
2105 let result = match self.resolve_path(&path, Some(ns), true, span, crate_lint) {
2106 PathResult::NonModule(path_res) => path_res,
2107 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
2108 PartialRes::new(module.res().unwrap())
2110 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2111 // don't report an error right away, but try to fallback to a primitive type.
2112 // So, we are still able to successfully resolve something like
2114 // use std::u8; // bring module u8 in scope
2115 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2116 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
2117 // // not to non-existent std::u8::max_value
2120 // Such behavior is required for backward compatibility.
2121 // The same fallback is used when `a` resolves to nothing.
2122 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
2123 if (ns == TypeNS || path.len() > 1)
2124 && PrimTy::from_name(path[0].ident.name).is_some() =>
2126 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
2127 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
2129 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2130 PartialRes::new(module.res().unwrap())
2132 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
2133 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
2135 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
2136 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
2140 && result.base_res() != Res::Err
2141 && path[0].ident.name != kw::PathRoot
2142 && path[0].ident.name != kw::DollarCrate
2144 let unqualified_result = {
2145 match self.resolve_path(
2146 &[*path.last().unwrap()],
2152 PathResult::NonModule(path_res) => path_res.base_res(),
2153 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2154 module.res().unwrap()
2156 _ => return Ok(Some(result)),
2159 if result.base_res() == unqualified_result {
2160 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
2161 self.r.lint_buffer.buffer_lint(lint, id, span, "unnecessary qualification")
2168 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
2169 if let Some(label) = label {
2170 if label.ident.as_str().as_bytes()[1] != b'_' {
2171 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
2173 self.with_label_rib(NormalRibKind, |this| {
2174 let ident = label.ident.normalize_to_macro_rules();
2175 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
2183 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
2184 self.with_resolved_label(label, id, |this| this.visit_block(block));
2187 fn resolve_block(&mut self, block: &'ast Block) {
2188 debug!("(resolving block) entering block");
2189 // Move down in the graph, if there's an anonymous module rooted here.
2190 let orig_module = self.parent_scope.module;
2191 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
2193 let mut num_macro_definition_ribs = 0;
2194 if let Some(anonymous_module) = anonymous_module {
2195 debug!("(resolving block) found anonymous module, moving down");
2196 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2197 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2198 self.parent_scope.module = anonymous_module;
2200 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2203 // Descend into the block.
2204 for stmt in &block.stmts {
2205 if let StmtKind::Item(ref item) = stmt.kind {
2206 if let ItemKind::MacroDef(..) = item.kind {
2207 num_macro_definition_ribs += 1;
2208 let res = self.r.local_def_id(item.id).to_def_id();
2209 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
2210 self.label_ribs.push(Rib::new(MacroDefinition(res)));
2214 self.visit_stmt(stmt);
2218 self.parent_scope.module = orig_module;
2219 for _ in 0..num_macro_definition_ribs {
2220 self.ribs[ValueNS].pop();
2221 self.label_ribs.pop();
2223 self.ribs[ValueNS].pop();
2224 if anonymous_module.is_some() {
2225 self.ribs[TypeNS].pop();
2227 debug!("(resolving block) leaving block");
2230 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
2231 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
2232 self.with_constant_rib(
2234 constant.value.is_potential_trivial_const_param(),
2237 visit::walk_anon_const(this, constant);
2242 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
2243 // First, record candidate traits for this expression if it could
2244 // result in the invocation of a method call.
2246 self.record_candidate_traits_for_expr_if_necessary(expr);
2248 // Next, resolve the node.
2250 ExprKind::Path(ref qself, ref path) => {
2251 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
2252 visit::walk_expr(self, expr);
2255 ExprKind::Struct(ref se) => {
2256 self.smart_resolve_path(expr.id, None, &se.path, PathSource::Struct);
2257 visit::walk_expr(self, expr);
2260 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
2261 if let Some(node_id) = self.resolve_label(label.ident) {
2262 // Since this res is a label, it is never read.
2263 self.r.label_res_map.insert(expr.id, node_id);
2264 self.diagnostic_metadata.unused_labels.remove(&node_id);
2267 // visit `break` argument if any
2268 visit::walk_expr(self, expr);
2271 ExprKind::Break(None, Some(ref e)) => {
2272 // We use this instead of `visit::walk_expr` to keep the parent expr around for
2273 // better diagnostics.
2274 self.resolve_expr(e, Some(&expr));
2277 ExprKind::Let(ref pat, ref scrutinee) => {
2278 self.visit_expr(scrutinee);
2279 self.resolve_pattern_top(pat, PatternSource::Let);
2282 ExprKind::If(ref cond, ref then, ref opt_else) => {
2283 self.with_rib(ValueNS, NormalRibKind, |this| {
2284 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
2285 this.visit_expr(cond);
2286 this.diagnostic_metadata.in_if_condition = old;
2287 this.visit_block(then);
2289 if let Some(expr) = opt_else {
2290 self.visit_expr(expr);
2294 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
2296 ExprKind::While(ref cond, ref block, label) => {
2297 self.with_resolved_label(label, expr.id, |this| {
2298 this.with_rib(ValueNS, NormalRibKind, |this| {
2299 this.visit_expr(cond);
2300 this.visit_block(block);
2305 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
2306 self.visit_expr(iter_expr);
2307 self.with_rib(ValueNS, NormalRibKind, |this| {
2308 this.resolve_pattern_top(pat, PatternSource::For);
2309 this.resolve_labeled_block(label, expr.id, block);
2313 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
2315 // Equivalent to `visit::walk_expr` + passing some context to children.
2316 ExprKind::Field(ref subexpression, _) => {
2317 self.resolve_expr(subexpression, Some(expr));
2319 ExprKind::MethodCall(ref segment, ref arguments, _) => {
2320 let mut arguments = arguments.iter();
2321 self.resolve_expr(arguments.next().unwrap(), Some(expr));
2322 for argument in arguments {
2323 self.resolve_expr(argument, None);
2325 self.visit_path_segment(expr.span, segment);
2328 ExprKind::Call(ref callee, ref arguments) => {
2329 self.resolve_expr(callee, Some(expr));
2330 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or(Vec::new());
2331 for (idx, argument) in arguments.iter().enumerate() {
2332 // Constant arguments need to be treated as AnonConst since
2333 // that is how they will be later lowered to HIR.
2334 if const_args.contains(&idx) {
2335 self.with_constant_rib(
2337 argument.is_potential_trivial_const_param(),
2340 this.resolve_expr(argument, None);
2344 self.resolve_expr(argument, None);
2348 ExprKind::Type(ref type_expr, ref ty) => {
2349 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
2350 // type ascription. Here we are trying to retrieve the span of the colon token as
2351 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
2352 // with `expr::Ty`, only in this case it will match the span from
2353 // `type_ascription_path_suggestions`.
2354 self.diagnostic_metadata
2355 .current_type_ascription
2356 .push(type_expr.span.between(ty.span));
2357 visit::walk_expr(self, expr);
2358 self.diagnostic_metadata.current_type_ascription.pop();
2360 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
2361 // resolve the arguments within the proper scopes so that usages of them inside the
2362 // closure are detected as upvars rather than normal closure arg usages.
2363 ExprKind::Closure(_, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
2364 self.with_rib(ValueNS, NormalRibKind, |this| {
2365 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
2366 // Resolve arguments:
2367 this.resolve_params(&fn_decl.inputs);
2368 // No need to resolve return type --
2369 // the outer closure return type is `FnRetTy::Default`.
2371 // Now resolve the inner closure
2373 // No need to resolve arguments: the inner closure has none.
2374 // Resolve the return type:
2375 visit::walk_fn_ret_ty(this, &fn_decl.output);
2377 this.visit_expr(body);
2382 ExprKind::Async(..) | ExprKind::Closure(..) => {
2383 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
2385 ExprKind::Repeat(ref elem, ref ct) => {
2386 self.visit_expr(elem);
2387 self.resolve_anon_const(ct, IsRepeatExpr::Yes);
2390 visit::walk_expr(self, expr);
2395 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
2397 ExprKind::Field(_, ident) => {
2398 // FIXME(#6890): Even though you can't treat a method like a
2399 // field, we need to add any trait methods we find that match
2400 // the field name so that we can do some nice error reporting
2401 // later on in typeck.
2402 let traits = self.traits_in_scope(ident, ValueNS);
2403 self.r.trait_map.insert(expr.id, traits);
2405 ExprKind::MethodCall(ref segment, ..) => {
2406 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
2407 let traits = self.traits_in_scope(segment.ident, ValueNS);
2408 self.r.trait_map.insert(expr.id, traits);
2416 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
2417 self.r.traits_in_scope(
2418 self.current_trait_ref.as_ref().map(|(module, _)| *module),
2421 Some((ident.name, ns)),
2426 impl<'a> Resolver<'a> {
2427 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
2428 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
2429 visit::walk_crate(&mut late_resolution_visitor, krate);
2430 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
2431 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");