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::{hash_map::Entry, 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)]
60 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
67 fn descr(self) -> &'static str {
69 PatternSource::Match => "match binding",
70 PatternSource::Let => "let binding",
71 PatternSource::For => "for binding",
72 PatternSource::FnParam => "function parameter",
77 /// Denotes whether the context for the set of already bound bindings is a `Product`
78 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
79 /// See those functions for more information.
82 /// A product pattern context, e.g., `Variant(a, b)`.
84 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
88 /// Does this the item (from the item rib scope) allow generic parameters?
89 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
90 crate enum HasGenericParams {
95 /// The rib kind restricts certain accesses,
96 /// e.g. to a `Res::Local` of an outer item.
97 #[derive(Copy, Clone, Debug)]
98 crate enum RibKind<'a> {
99 /// No restriction needs to be applied.
102 /// We passed through an impl or trait and are now in one of its
103 /// methods or associated types. Allow references to ty params that impl or trait
104 /// binds. Disallow any other upvars (including other ty params that are
108 /// We passed through a closure. Disallow labels.
109 ClosureOrAsyncRibKind,
111 /// We passed through a function definition. Disallow upvars.
112 /// Permit only those const parameters that are specified in the function's generics.
115 /// We passed through an item scope. Disallow upvars.
116 ItemRibKind(HasGenericParams),
118 /// We're in a constant item. Can't refer to dynamic stuff.
120 /// The `bool` indicates if this constant may reference generic parameters
121 /// and is used to only allow generic parameters to be used in trivial constant expressions.
122 ConstantItemRibKind(bool),
124 /// We passed through a module.
125 ModuleRibKind(Module<'a>),
127 /// We passed through a `macro_rules!` statement
128 MacroDefinition(DefId),
130 /// All bindings in this rib are type parameters that can't be used
131 /// from the default of a type parameter because they're not declared
132 /// before said type parameter. Also see the `visit_generics` override.
133 ForwardTyParamBanRibKind,
135 /// We are inside of the type of a const parameter. Can't refer to any
141 /// Whether this rib kind contains generic parameters, as opposed to local
143 crate fn contains_params(&self) -> bool {
146 | ClosureOrAsyncRibKind
148 | ConstantItemRibKind(_)
151 | ConstParamTyRibKind => false,
152 AssocItemRibKind | ItemRibKind(_) | ForwardTyParamBanRibKind => true,
157 /// A single local scope.
159 /// A rib represents a scope names can live in. Note that these appear in many places, not just
160 /// around braces. At any place where the list of accessible names (of the given namespace)
161 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
162 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
165 /// Different [rib kinds](enum.RibKind) are transparent for different names.
167 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
168 /// resolving, the name is looked up from inside out.
170 crate struct Rib<'a, R = Res> {
171 pub bindings: IdentMap<R>,
172 pub kind: RibKind<'a>,
175 impl<'a, R> Rib<'a, R> {
176 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
177 Rib { bindings: Default::default(), kind }
181 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
182 crate enum AliasPossibility {
187 #[derive(Copy, Clone, Debug)]
188 crate enum PathSource<'a> {
189 // Type paths `Path`.
191 // Trait paths in bounds or impls.
192 Trait(AliasPossibility),
193 // Expression paths `path`, with optional parent context.
194 Expr(Option<&'a Expr>),
195 // Paths in path patterns `Path`.
197 // Paths in struct expressions and patterns `Path { .. }`.
199 // Paths in tuple struct patterns `Path(..)`.
200 TupleStruct(Span, &'a [Span]),
201 // `m::A::B` in `<T as m::A>::B::C`.
202 TraitItem(Namespace),
205 impl<'a> PathSource<'a> {
206 fn namespace(self) -> Namespace {
208 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
209 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
210 PathSource::TraitItem(ns) => ns,
214 fn defer_to_typeck(self) -> bool {
217 | PathSource::Expr(..)
220 | PathSource::TupleStruct(..) => true,
221 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
225 fn descr_expected(self) -> &'static str {
227 PathSource::Type => "type",
228 PathSource::Trait(_) => "trait",
229 PathSource::Pat => "unit struct, unit variant or constant",
230 PathSource::Struct => "struct, variant or union type",
231 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
232 PathSource::TraitItem(ns) => match ns {
233 TypeNS => "associated type",
234 ValueNS => "method or associated constant",
235 MacroNS => bug!("associated macro"),
237 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
238 // "function" here means "anything callable" rather than `DefKind::Fn`,
239 // this is not precise but usually more helpful than just "value".
240 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
241 ExprKind::Path(_, path) => {
242 let mut msg = "function";
243 if let Some(segment) = path.segments.iter().last() {
244 if let Some(c) = segment.ident.to_string().chars().next() {
245 if c.is_uppercase() {
246 msg = "function, tuple struct or tuple variant";
259 fn is_call(self) -> bool {
260 matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
263 crate fn is_expected(self, res: Res) -> bool {
265 PathSource::Type => matches!(res, Res::Def(
270 | DefKind::TraitAlias
275 | DefKind::ForeignTy,
280 PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
281 PathSource::Trait(AliasPossibility::Maybe) => {
282 matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
284 PathSource::Expr(..) => matches!(res, Res::Def(
285 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
290 | DefKind::AssocConst
291 | DefKind::ConstParam,
295 | Res::SelfCtor(..)),
296 PathSource::Pat => matches!(res, Res::Def(
297 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::AssocConst,
300 | Res::SelfCtor(..)),
301 PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
302 PathSource::Struct => matches!(res, Res::Def(
311 PathSource::TraitItem(ns) => match res {
312 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
313 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
319 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
320 use rustc_errors::error_code;
321 match (self, has_unexpected_resolution) {
322 (PathSource::Trait(_), true) => error_code!(E0404),
323 (PathSource::Trait(_), false) => error_code!(E0405),
324 (PathSource::Type, true) => error_code!(E0573),
325 (PathSource::Type, false) => error_code!(E0412),
326 (PathSource::Struct, true) => error_code!(E0574),
327 (PathSource::Struct, false) => error_code!(E0422),
328 (PathSource::Expr(..), true) => error_code!(E0423),
329 (PathSource::Expr(..), false) => error_code!(E0425),
330 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
331 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
332 (PathSource::TraitItem(..), true) => error_code!(E0575),
333 (PathSource::TraitItem(..), false) => error_code!(E0576),
339 struct DiagnosticMetadata<'ast> {
340 /// The current trait's associated items' ident, used for diagnostic suggestions.
341 current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
343 /// The current self type if inside an impl (used for better errors).
344 current_self_type: Option<Ty>,
346 /// The current self item if inside an ADT (used for better errors).
347 current_self_item: Option<NodeId>,
349 /// The current trait (used to suggest).
350 current_item: Option<&'ast Item>,
352 /// When processing generics and encountering a type not found, suggest introducing a type
354 currently_processing_generics: bool,
356 /// The current enclosing (non-closure) function (used for better errors).
357 current_function: Option<(FnKind<'ast>, Span)>,
359 /// A list of labels as of yet unused. Labels will be removed from this map when
360 /// they are used (in a `break` or `continue` statement)
361 unused_labels: FxHashMap<NodeId, Span>,
363 /// Only used for better errors on `fn(): fn()`.
364 current_type_ascription: Vec<Span>,
366 /// Only used for better errors on `let <pat>: <expr, not type>;`.
367 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
369 /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
370 in_if_condition: Option<&'ast Expr>,
372 /// If we are currently in a trait object definition. Used to point at the bounds when
373 /// encountering a struct or enum.
374 current_trait_object: Option<&'ast [ast::GenericBound]>,
376 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
377 current_where_predicate: Option<&'ast WherePredicate>,
380 struct LateResolutionVisitor<'a, 'b, 'ast> {
381 r: &'b mut Resolver<'a>,
383 /// The module that represents the current item scope.
384 parent_scope: ParentScope<'a>,
386 /// The current set of local scopes for types and values.
387 /// FIXME #4948: Reuse ribs to avoid allocation.
388 ribs: PerNS<Vec<Rib<'a>>>,
390 /// The current set of local scopes, for labels.
391 label_ribs: Vec<Rib<'a, NodeId>>,
393 /// The trait that the current context can refer to.
394 current_trait_ref: Option<(Module<'a>, TraitRef)>,
396 /// Fields used to add information to diagnostic errors.
397 diagnostic_metadata: DiagnosticMetadata<'ast>,
399 /// State used to know whether to ignore resolution errors for function bodies.
401 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
402 /// In most cases this will be `None`, in which case errors will always be reported.
403 /// If it is `true`, then it will be updated when entering a nested function or trait body.
407 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
408 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
409 fn visit_item(&mut self, item: &'ast Item) {
410 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
411 // Always report errors in items we just entered.
412 let old_ignore = replace(&mut self.in_func_body, false);
413 self.resolve_item(item);
414 self.in_func_body = old_ignore;
415 self.diagnostic_metadata.current_item = prev;
417 fn visit_arm(&mut self, arm: &'ast Arm) {
418 self.resolve_arm(arm);
420 fn visit_block(&mut self, block: &'ast Block) {
421 self.resolve_block(block);
423 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
424 // We deal with repeat expressions explicitly in `resolve_expr`.
425 self.resolve_anon_const(constant, IsRepeatExpr::No);
427 fn visit_expr(&mut self, expr: &'ast Expr) {
428 self.resolve_expr(expr, None);
430 fn visit_local(&mut self, local: &'ast Local) {
431 let local_spans = match local.pat.kind {
432 // We check for this to avoid tuple struct fields.
433 PatKind::Wild => None,
436 local.ty.as_ref().map(|ty| ty.span),
437 local.init.as_ref().map(|init| init.span),
440 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
441 self.resolve_local(local);
442 self.diagnostic_metadata.current_let_binding = original;
444 fn visit_ty(&mut self, ty: &'ast Ty) {
445 let prev = self.diagnostic_metadata.current_trait_object;
447 TyKind::Path(ref qself, ref path) => {
448 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
450 TyKind::ImplicitSelf => {
451 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
453 .resolve_ident_in_lexical_scope(self_ty, TypeNS, Some(ty.id), ty.span)
454 .map_or(Res::Err, |d| d.res());
455 self.r.record_partial_res(ty.id, PartialRes::new(res));
457 TyKind::TraitObject(ref bounds, ..) => {
458 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
462 visit::walk_ty(self, ty);
463 self.diagnostic_metadata.current_trait_object = prev;
465 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef, m: &'ast TraitBoundModifier) {
466 self.smart_resolve_path(
467 tref.trait_ref.ref_id,
469 &tref.trait_ref.path,
470 PathSource::Trait(AliasPossibility::Maybe),
472 visit::walk_poly_trait_ref(self, tref, m);
474 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
475 match foreign_item.kind {
476 ForeignItemKind::Fn(_, _, ref generics, _)
477 | ForeignItemKind::TyAlias(_, ref generics, ..) => {
478 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
479 visit::walk_foreign_item(this, foreign_item);
482 ForeignItemKind::Static(..) => {
483 self.with_item_rib(HasGenericParams::No, |this| {
484 visit::walk_foreign_item(this, foreign_item);
487 ForeignItemKind::MacCall(..) => {
488 visit::walk_foreign_item(self, foreign_item);
492 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, _: NodeId) {
493 let rib_kind = match fn_kind {
494 // Bail if there's no body.
495 FnKind::Fn(.., None) => return visit::walk_fn(self, fn_kind, sp),
496 FnKind::Fn(FnCtxt::Free | FnCtxt::Foreign, ..) => FnItemRibKind,
497 FnKind::Fn(FnCtxt::Assoc(_), ..) => NormalRibKind,
498 FnKind::Closure(..) => ClosureOrAsyncRibKind,
500 let previous_value = self.diagnostic_metadata.current_function;
501 if matches!(fn_kind, FnKind::Fn(..)) {
502 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
504 debug!("(resolving function) entering function");
505 let declaration = fn_kind.decl();
507 // Create a value rib for the function.
508 self.with_rib(ValueNS, rib_kind, |this| {
509 // Create a label rib for the function.
510 this.with_label_rib(rib_kind, |this| {
511 // Add each argument to the rib.
512 this.resolve_params(&declaration.inputs);
514 visit::walk_fn_ret_ty(this, &declaration.output);
516 // Ignore errors in function bodies if this is rustdoc
517 // Be sure not to set this until the function signature has been resolved.
518 let previous_state = replace(&mut this.in_func_body, true);
519 // Resolve the function body, potentially inside the body of an async closure
521 FnKind::Fn(.., body) => walk_list!(this, visit_block, body),
522 FnKind::Closure(_, body) => this.visit_expr(body),
525 debug!("(resolving function) leaving function");
526 this.in_func_body = previous_state;
529 self.diagnostic_metadata.current_function = previous_value;
532 fn visit_generics(&mut self, generics: &'ast Generics) {
533 // For type parameter defaults, we have to ban access
534 // to following type parameters, as the InternalSubsts can only
535 // provide previous type parameters as they're built. We
536 // put all the parameters on the ban list and then remove
537 // them one by one as they are processed and become available.
538 let mut default_ban_rib = Rib::new(ForwardTyParamBanRibKind);
539 let mut found_default = false;
540 default_ban_rib.bindings.extend(generics.params.iter().filter_map(
541 |param| match param.kind {
542 GenericParamKind::Const { .. } | GenericParamKind::Lifetime { .. } => None,
543 GenericParamKind::Type { ref default, .. } => {
544 found_default |= default.is_some();
545 found_default.then_some((Ident::with_dummy_span(param.ident.name), Res::Err))
550 // rust-lang/rust#61631: The type `Self` is essentially
551 // another type parameter. For ADTs, we consider it
552 // well-defined only after all of the ADT type parameters have
553 // been provided. Therefore, we do not allow use of `Self`
554 // anywhere in ADT type parameter defaults.
556 // (We however cannot ban `Self` for defaults on *all* generic
557 // lists; e.g. trait generics can usefully refer to `Self`,
558 // such as in the case of `trait Add<Rhs = Self>`.)
559 if self.diagnostic_metadata.current_self_item.is_some() {
560 // (`Some` if + only if we are in ADT's generics.)
561 default_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
564 for param in &generics.params {
566 GenericParamKind::Lifetime => self.visit_generic_param(param),
567 GenericParamKind::Type { ref default } => {
568 for bound in ¶m.bounds {
569 self.visit_param_bound(bound);
572 if let Some(ref ty) = default {
573 self.ribs[TypeNS].push(default_ban_rib);
574 self.with_rib(ValueNS, ForwardTyParamBanRibKind, |this| {
575 // HACK: We use an empty `ForwardTyParamBanRibKind` here which
576 // is only used to forbid the use of const parameters inside of
579 // While the rib name doesn't really fit here, it does allow us to use the same
580 // code for both const and type parameters.
583 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
586 // Allow all following defaults to refer to this type parameter.
587 default_ban_rib.bindings.remove(&Ident::with_dummy_span(param.ident.name));
589 GenericParamKind::Const { ref ty, kw_span: _, default: _ } => {
590 // FIXME(const_generics_defaults): handle `default` value here
591 for bound in ¶m.bounds {
592 self.visit_param_bound(bound);
594 self.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
595 self.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
597 self.ribs[TypeNS].pop().unwrap();
598 self.ribs[ValueNS].pop().unwrap();
602 for p in &generics.where_clause.predicates {
603 self.visit_where_predicate(p);
607 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
608 debug!("visit_generic_arg({:?})", arg);
609 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
611 GenericArg::Type(ref ty) => {
612 // We parse const arguments as path types as we cannot distinguish them during
613 // parsing. We try to resolve that ambiguity by attempting resolution the type
614 // namespace first, and if that fails we try again in the value namespace. If
615 // resolution in the value namespace succeeds, we have an generic const argument on
617 if let TyKind::Path(ref qself, ref path) = ty.kind {
618 // We cannot disambiguate multi-segment paths right now as that requires type
620 if path.segments.len() == 1 && path.segments[0].args.is_none() {
621 let mut check_ns = |ns| {
622 self.resolve_ident_in_lexical_scope(
623 path.segments[0].ident,
630 if !check_ns(TypeNS) && check_ns(ValueNS) {
631 // This must be equivalent to `visit_anon_const`, but we cannot call it
632 // directly due to visitor lifetimes so we have to copy-paste some code.
634 // Note that we might not be inside of an repeat expression here,
635 // but considering that `IsRepeatExpr` is only relevant for
636 // non-trivial constants this is doesn't matter.
637 self.with_constant_rib(IsRepeatExpr::No, true, |this| {
638 this.smart_resolve_path(
642 PathSource::Expr(None),
645 if let Some(ref qself) = *qself {
646 this.visit_ty(&qself.ty);
648 this.visit_path(path, ty.id);
651 self.diagnostic_metadata.currently_processing_generics = prev;
659 GenericArg::Lifetime(lt) => self.visit_lifetime(lt),
660 GenericArg::Const(ct) => self.visit_anon_const(ct),
662 self.diagnostic_metadata.currently_processing_generics = prev;
665 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
666 debug!("visit_where_predicate {:?}", p);
668 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
669 visit::walk_where_predicate(self, p);
670 self.diagnostic_metadata.current_where_predicate = previous_value;
674 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
675 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
676 // During late resolution we only track the module component of the parent scope,
677 // although it may be useful to track other components as well for diagnostics.
678 let graph_root = resolver.graph_root;
679 let parent_scope = ParentScope::module(graph_root, resolver);
680 let start_rib_kind = ModuleRibKind(graph_root);
681 LateResolutionVisitor {
685 value_ns: vec![Rib::new(start_rib_kind)],
686 type_ns: vec![Rib::new(start_rib_kind)],
687 macro_ns: vec![Rib::new(start_rib_kind)],
689 label_ribs: Vec::new(),
690 current_trait_ref: None,
691 diagnostic_metadata: DiagnosticMetadata::default(),
692 // errors at module scope should always be reported
697 fn resolve_ident_in_lexical_scope(
701 record_used_id: Option<NodeId>,
703 ) -> Option<LexicalScopeBinding<'a>> {
704 self.r.resolve_ident_in_lexical_scope(
717 opt_ns: Option<Namespace>, // `None` indicates a module path in import
720 crate_lint: CrateLint,
721 ) -> PathResult<'a> {
722 self.r.resolve_path_with_ribs(
735 // We maintain a list of value ribs and type ribs.
737 // Simultaneously, we keep track of the current position in the module
738 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
739 // the value or type namespaces, we first look through all the ribs and
740 // then query the module graph. When we resolve a name in the module
741 // namespace, we can skip all the ribs (since nested modules are not
742 // allowed within blocks in Rust) and jump straight to the current module
745 // Named implementations are handled separately. When we find a method
746 // call, we consult the module node to find all of the implementations in
747 // scope. This information is lazily cached in the module node. We then
748 // generate a fake "implementation scope" containing all the
749 // implementations thus found, for compatibility with old resolve pass.
751 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
756 work: impl FnOnce(&mut Self) -> T,
758 self.ribs[ns].push(Rib::new(kind));
759 let ret = work(self);
764 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
765 let id = self.r.local_def_id(id);
766 let module = self.r.module_map.get(&id).cloned(); // clones a reference
767 if let Some(module) = module {
768 // Move down in the graph.
769 let orig_module = replace(&mut self.parent_scope.module, module);
770 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
771 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
773 this.parent_scope.module = orig_module;
782 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
783 /// label and reports an error if the label is not found or is unreachable.
784 fn resolve_label(&self, mut label: Ident) -> Option<NodeId> {
785 let mut suggestion = None;
787 // Preserve the original span so that errors contain "in this macro invocation"
789 let original_span = label.span;
791 for i in (0..self.label_ribs.len()).rev() {
792 let rib = &self.label_ribs[i];
794 if let MacroDefinition(def) = rib.kind {
795 // If an invocation of this macro created `ident`, give up on `ident`
796 // and switch to `ident`'s source from the macro definition.
797 if def == self.r.macro_def(label.span.ctxt()) {
798 label.span.remove_mark();
802 let ident = label.normalize_to_macro_rules();
803 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
804 return if self.is_label_valid_from_rib(i) {
809 ResolutionError::UnreachableLabel {
811 definition_span: ident.span,
820 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
821 // the first such label that is encountered.
822 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
827 ResolutionError::UndeclaredLabel { name: label.name, suggestion },
832 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
833 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
834 let ribs = &self.label_ribs[rib_index + 1..];
838 NormalRibKind | MacroDefinition(..) => {
839 // Nothing to do. Continue.
843 | ClosureOrAsyncRibKind
846 | ConstantItemRibKind(_)
848 | ForwardTyParamBanRibKind
849 | ConstParamTyRibKind => {
858 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
859 debug!("resolve_adt");
860 self.with_current_self_item(item, |this| {
861 this.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
862 let item_def_id = this.r.local_def_id(item.id).to_def_id();
863 this.with_self_rib(Res::SelfTy(None, Some((item_def_id, false))), |this| {
864 visit::walk_item(this, item);
870 fn future_proof_import(&mut self, use_tree: &UseTree) {
871 let segments = &use_tree.prefix.segments;
872 if !segments.is_empty() {
873 let ident = segments[0].ident;
874 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
878 let nss = match use_tree.kind {
879 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
882 let report_error = |this: &Self, ns| {
883 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
884 if this.should_report_errs() {
887 .span_err(ident.span, &format!("imports cannot refer to {}", what));
892 match self.resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span) {
893 Some(LexicalScopeBinding::Res(..)) => {
894 report_error(self, ns);
896 Some(LexicalScopeBinding::Item(binding)) => {
897 let orig_unusable_binding =
898 replace(&mut self.r.unusable_binding, Some(binding));
899 if let Some(LexicalScopeBinding::Res(..)) = self
900 .resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span)
902 report_error(self, ns);
904 self.r.unusable_binding = orig_unusable_binding;
909 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
910 for (use_tree, _) in use_trees {
911 self.future_proof_import(use_tree);
916 fn resolve_item(&mut self, item: &'ast Item) {
917 let name = item.ident.name;
918 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
921 ItemKind::TyAlias(_, ref generics, _, _) | ItemKind::Fn(_, _, ref generics, _) => {
922 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
923 visit::walk_item(this, item)
927 ItemKind::Enum(_, ref generics)
928 | ItemKind::Struct(_, ref generics)
929 | ItemKind::Union(_, ref generics) => {
930 self.resolve_adt(item, generics);
937 items: ref impl_items,
940 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
943 ItemKind::Trait(.., ref generics, ref bounds, ref trait_items) => {
944 // Create a new rib for the trait-wide type parameters.
945 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
946 let local_def_id = this.r.local_def_id(item.id).to_def_id();
947 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
948 this.visit_generics(generics);
949 walk_list!(this, visit_param_bound, bounds);
951 let walk_assoc_item = |this: &mut Self, generics, item| {
952 this.with_generic_param_rib(generics, AssocItemRibKind, |this| {
953 visit::walk_assoc_item(this, item, AssocCtxt::Trait)
957 this.with_trait_items(trait_items, |this| {
958 for item in trait_items {
960 AssocItemKind::Const(_, ty, default) => {
962 // Only impose the restrictions of `ConstRibKind` for an
963 // actual constant expression in a provided default.
964 if let Some(expr) = default {
965 // We allow arbitrary const expressions inside of associated consts,
966 // even if they are potentially not const evaluatable.
968 // Type parameters can already be used and as associated consts are
969 // not used as part of the type system, this is far less surprising.
970 this.with_constant_rib(
973 |this| this.visit_expr(expr),
977 AssocItemKind::Fn(_, _, generics, _) => {
978 walk_assoc_item(this, generics, item);
980 AssocItemKind::TyAlias(_, generics, _, _) => {
981 walk_assoc_item(this, generics, item);
983 AssocItemKind::MacCall(_) => {
984 panic!("unexpanded macro in resolve!")
993 ItemKind::TraitAlias(ref generics, ref bounds) => {
994 // Create a new rib for the trait-wide type parameters.
995 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
996 let local_def_id = this.r.local_def_id(item.id).to_def_id();
997 this.with_self_rib(Res::SelfTy(Some(local_def_id), None), |this| {
998 this.visit_generics(generics);
999 walk_list!(this, visit_param_bound, bounds);
1004 ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
1005 self.with_scope(item.id, |this| {
1006 visit::walk_item(this, item);
1010 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
1011 debug!("resolve_item ItemKind::Const");
1012 self.with_item_rib(HasGenericParams::No, |this| {
1014 if let Some(expr) = expr {
1015 // We already forbid generic params because of the above item rib,
1016 // so it doesn't matter whether this is a trivial constant.
1017 this.with_constant_rib(IsRepeatExpr::No, true, |this| {
1018 this.visit_expr(expr)
1024 ItemKind::Use(ref use_tree) => {
1025 self.future_proof_import(use_tree);
1028 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) | ItemKind::GlobalAsm(..) => {
1029 // do nothing, these are just around to be encoded
1032 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
1036 fn with_generic_param_rib<'c, F>(&'c mut self, generics: &'c Generics, kind: RibKind<'a>, f: F)
1038 F: FnOnce(&mut Self),
1040 debug!("with_generic_param_rib");
1041 let mut function_type_rib = Rib::new(kind);
1042 let mut function_value_rib = Rib::new(kind);
1043 let mut seen_bindings = FxHashMap::default();
1045 // We also can't shadow bindings from the parent item
1046 if let AssocItemRibKind = kind {
1047 let mut add_bindings_for_ns = |ns| {
1048 let parent_rib = self.ribs[ns]
1050 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
1051 .expect("associated item outside of an item");
1053 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
1055 add_bindings_for_ns(ValueNS);
1056 add_bindings_for_ns(TypeNS);
1059 for param in &generics.params {
1060 if let GenericParamKind::Lifetime { .. } = param.kind {
1064 let ident = param.ident.normalize_to_macros_2_0();
1065 debug!("with_generic_param_rib: {}", param.id);
1067 match seen_bindings.entry(ident) {
1068 Entry::Occupied(entry) => {
1069 let span = *entry.get();
1070 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
1071 self.report_error(param.ident.span, err);
1073 Entry::Vacant(entry) => {
1074 entry.insert(param.ident.span);
1078 // Plain insert (no renaming).
1079 let (rib, def_kind) = match param.kind {
1080 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
1081 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
1082 _ => unreachable!(),
1084 let res = Res::Def(def_kind, self.r.local_def_id(param.id).to_def_id());
1085 self.r.record_partial_res(param.id, PartialRes::new(res));
1086 rib.bindings.insert(ident, res);
1089 self.ribs[ValueNS].push(function_value_rib);
1090 self.ribs[TypeNS].push(function_type_rib);
1094 self.ribs[TypeNS].pop();
1095 self.ribs[ValueNS].pop();
1098 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
1099 self.label_ribs.push(Rib::new(kind));
1101 self.label_ribs.pop();
1104 fn with_item_rib(&mut self, has_generic_params: HasGenericParams, f: impl FnOnce(&mut Self)) {
1105 let kind = ItemRibKind(has_generic_params);
1106 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
1109 // HACK(min_const_generics,const_evaluatable_unchecked): We
1110 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
1111 // with a future compat lint for now. We do this by adding an
1112 // additional special case for repeat expressions.
1114 // Note that we intentionally still forbid `[0; N + 1]` during
1115 // name resolution so that we don't extend the future
1116 // compat lint to new cases.
1117 fn with_constant_rib(
1119 is_repeat: IsRepeatExpr,
1121 f: impl FnOnce(&mut Self),
1123 debug!("with_constant_rib: is_repeat={:?} is_trivial={}", is_repeat, is_trivial);
1124 self.with_rib(ValueNS, ConstantItemRibKind(is_trivial), |this| {
1127 ConstantItemRibKind(is_repeat == IsRepeatExpr::Yes || is_trivial),
1129 this.with_label_rib(ConstantItemRibKind(is_trivial), f);
1135 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
1136 // Handle nested impls (inside fn bodies)
1137 let previous_value =
1138 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
1139 let result = f(self);
1140 self.diagnostic_metadata.current_self_type = previous_value;
1144 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
1145 let previous_value =
1146 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
1147 let result = f(self);
1148 self.diagnostic_metadata.current_self_item = previous_value;
1152 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
1153 fn with_trait_items<T>(
1155 trait_items: &'ast [P<AssocItem>],
1156 f: impl FnOnce(&mut Self) -> T,
1158 let trait_assoc_items =
1159 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
1160 let result = f(self);
1161 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
1165 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
1166 fn with_optional_trait_ref<T>(
1168 opt_trait_ref: Option<&TraitRef>,
1169 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
1171 let mut new_val = None;
1172 let mut new_id = None;
1173 if let Some(trait_ref) = opt_trait_ref {
1174 let path: Vec<_> = Segment::from_path(&trait_ref.path);
1175 let res = self.smart_resolve_path_fragment(
1179 trait_ref.path.span,
1180 PathSource::Trait(AliasPossibility::No),
1181 CrateLint::SimplePath(trait_ref.ref_id),
1183 let res = res.base_res();
1184 if res != Res::Err {
1185 new_id = Some(res.def_id());
1186 let span = trait_ref.path.span;
1187 if let PathResult::Module(ModuleOrUniformRoot::Module(module)) = self.resolve_path(
1192 CrateLint::SimplePath(trait_ref.ref_id),
1194 new_val = Some((module, trait_ref.clone()));
1198 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1199 let result = f(self, new_id);
1200 self.current_trait_ref = original_trait_ref;
1204 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
1205 let mut self_type_rib = Rib::new(NormalRibKind);
1207 // Plain insert (no renaming, since types are not currently hygienic)
1208 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
1209 self.ribs[ns].push(self_type_rib);
1211 self.ribs[ns].pop();
1214 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
1215 self.with_self_rib_ns(TypeNS, self_res, f)
1218 fn resolve_implementation(
1220 generics: &'ast Generics,
1221 opt_trait_reference: &'ast Option<TraitRef>,
1222 self_type: &'ast Ty,
1224 impl_items: &'ast [P<AssocItem>],
1226 debug!("resolve_implementation");
1227 // If applicable, create a rib for the type parameters.
1228 self.with_generic_param_rib(generics, ItemRibKind(HasGenericParams::Yes), |this| {
1229 // Dummy self type for better errors if `Self` is used in the trait path.
1230 this.with_self_rib(Res::SelfTy(None, None), |this| {
1231 // Resolve the trait reference, if necessary.
1232 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1233 let item_def_id = this.r.local_def_id(item_id).to_def_id();
1234 this.with_self_rib(Res::SelfTy(trait_id, Some((item_def_id, false))), |this| {
1235 if let Some(trait_ref) = opt_trait_reference.as_ref() {
1236 // Resolve type arguments in the trait path.
1237 visit::walk_trait_ref(this, trait_ref);
1239 // Resolve the self type.
1240 this.visit_ty(self_type);
1241 // Resolve the generic parameters.
1242 this.visit_generics(generics);
1243 // Resolve the items within the impl.
1244 this.with_current_self_type(self_type, |this| {
1245 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
1246 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
1247 for item in impl_items {
1248 use crate::ResolutionError::*;
1250 AssocItemKind::Const(_default, _ty, _expr) => {
1251 debug!("resolve_implementation AssocItemKind::Const",);
1252 // If this is a trait impl, ensure the const
1254 this.check_trait_item(
1258 |n, s| ConstNotMemberOfTrait(n, s),
1261 // We allow arbitrary const expressions inside of associated consts,
1262 // even if they are potentially not const evaluatable.
1264 // Type parameters can already be used and as associated consts are
1265 // not used as part of the type system, this is far less surprising.
1266 this.with_constant_rib(
1270 visit::walk_assoc_item(
1278 AssocItemKind::Fn(_, _, generics, _) => {
1279 // We also need a new scope for the impl item type parameters.
1280 this.with_generic_param_rib(
1284 // If this is a trait impl, ensure the method
1286 this.check_trait_item(
1290 |n, s| MethodNotMemberOfTrait(n, s),
1293 visit::walk_assoc_item(
1301 AssocItemKind::TyAlias(_, generics, _, _) => {
1302 // We also need a new scope for the impl item type parameters.
1303 this.with_generic_param_rib(
1307 // If this is a trait impl, ensure the type
1309 this.check_trait_item(
1313 |n, s| TypeNotMemberOfTrait(n, s),
1316 visit::walk_assoc_item(
1324 AssocItemKind::MacCall(_) => {
1325 panic!("unexpanded macro in resolve!")
1337 fn check_trait_item<F>(&mut self, ident: Ident, ns: Namespace, span: Span, err: F)
1339 F: FnOnce(Symbol, &str) -> ResolutionError<'_>,
1341 // If there is a TraitRef in scope for an impl, then the method must be in the
1343 if let Some((module, _)) = self.current_trait_ref {
1346 .resolve_ident_in_module(
1347 ModuleOrUniformRoot::Module(module),
1356 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
1357 self.report_error(span, err(ident.name, &path_names_to_string(path)));
1362 fn resolve_params(&mut self, params: &'ast [Param]) {
1363 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1364 for Param { pat, ty, .. } in params {
1365 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1367 debug!("(resolving function / closure) recorded parameter");
1371 fn resolve_local(&mut self, local: &'ast Local) {
1372 debug!("resolving local ({:?})", local);
1373 // Resolve the type.
1374 walk_list!(self, visit_ty, &local.ty);
1376 // Resolve the initializer.
1377 walk_list!(self, visit_expr, &local.init);
1379 // Resolve the pattern.
1380 self.resolve_pattern_top(&local.pat, PatternSource::Let);
1383 /// build a map from pattern identifiers to binding-info's.
1384 /// this is done hygienically. This could arise for a macro
1385 /// that expands into an or-pattern where one 'x' was from the
1386 /// user and one 'x' came from the macro.
1387 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1388 let mut binding_map = FxHashMap::default();
1390 pat.walk(&mut |pat| {
1392 PatKind::Ident(binding_mode, ident, ref sub_pat)
1393 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
1395 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
1397 PatKind::Or(ref ps) => {
1398 // Check the consistency of this or-pattern and
1399 // then add all bindings to the larger map.
1400 for bm in self.check_consistent_bindings(ps) {
1401 binding_map.extend(bm);
1414 fn is_base_res_local(&self, nid: NodeId) -> bool {
1415 matches!(self.r.partial_res_map.get(&nid).map(|res| res.base_res()), Some(Res::Local(..)))
1418 /// Checks that all of the arms in an or-pattern have exactly the
1419 /// same set of bindings, with the same binding modes for each.
1420 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
1421 let mut missing_vars = FxHashMap::default();
1422 let mut inconsistent_vars = FxHashMap::default();
1424 // 1) Compute the binding maps of all arms.
1425 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
1427 // 2) Record any missing bindings or binding mode inconsistencies.
1428 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
1429 // Check against all arms except for the same pattern which is always self-consistent.
1433 .filter(|(_, pat)| pat.id != pat_outer.id)
1434 .flat_map(|(idx, _)| maps[idx].iter())
1435 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
1437 for (name, info, &binding_inner) in inners {
1440 // The inner binding is missing in the outer.
1442 missing_vars.entry(name).or_insert_with(|| BindingError {
1444 origin: BTreeSet::new(),
1445 target: BTreeSet::new(),
1446 could_be_path: name.as_str().starts_with(char::is_uppercase),
1448 binding_error.origin.insert(binding_inner.span);
1449 binding_error.target.insert(pat_outer.span);
1451 Some(binding_outer) => {
1452 if binding_outer.binding_mode != binding_inner.binding_mode {
1453 // The binding modes in the outer and inner bindings differ.
1456 .or_insert((binding_inner.span, binding_outer.span));
1463 // 3) Report all missing variables we found.
1464 let mut missing_vars = missing_vars.iter_mut().collect::<Vec<_>>();
1465 missing_vars.sort_by_key(|(sym, _err)| sym.as_str());
1467 for (name, mut v) in missing_vars {
1468 if inconsistent_vars.contains_key(name) {
1469 v.could_be_path = false;
1472 *v.origin.iter().next().unwrap(),
1473 ResolutionError::VariableNotBoundInPattern(v),
1477 // 4) Report all inconsistencies in binding modes we found.
1478 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
1479 inconsistent_vars.sort();
1480 for (name, v) in inconsistent_vars {
1481 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
1484 // 5) Finally bubble up all the binding maps.
1488 /// Check the consistency of the outermost or-patterns.
1489 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
1490 pat.walk(&mut |pat| match pat.kind {
1491 PatKind::Or(ref ps) => {
1492 self.check_consistent_bindings(ps);
1499 fn resolve_arm(&mut self, arm: &'ast Arm) {
1500 self.with_rib(ValueNS, NormalRibKind, |this| {
1501 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
1502 walk_list!(this, visit_expr, &arm.guard);
1503 this.visit_expr(&arm.body);
1507 /// Arising from `source`, resolve a top level pattern.
1508 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
1509 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1510 self.resolve_pattern(pat, pat_src, &mut bindings);
1516 pat_src: PatternSource,
1517 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1519 self.resolve_pattern_inner(pat, pat_src, bindings);
1520 // This has to happen *after* we determine which pat_idents are variants:
1521 self.check_consistent_bindings_top(pat);
1522 visit::walk_pat(self, pat);
1525 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
1529 /// A stack of sets of bindings accumulated.
1531 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
1532 /// be interpreted as re-binding an already bound binding. This results in an error.
1533 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
1534 /// in reusing this binding rather than creating a fresh one.
1536 /// When called at the top level, the stack must have a single element
1537 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
1538 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
1539 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
1540 /// When each `p_i` has been dealt with, the top set is merged with its parent.
1541 /// When a whole or-pattern has been dealt with, the thing happens.
1543 /// See the implementation and `fresh_binding` for more details.
1544 fn resolve_pattern_inner(
1547 pat_src: PatternSource,
1548 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1550 // Visit all direct subpatterns of this pattern.
1551 pat.walk(&mut |pat| {
1552 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
1554 PatKind::Ident(bmode, ident, ref sub) => {
1555 // First try to resolve the identifier as some existing entity,
1556 // then fall back to a fresh binding.
1557 let has_sub = sub.is_some();
1559 .try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub)
1560 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
1561 self.r.record_partial_res(pat.id, PartialRes::new(res));
1563 PatKind::TupleStruct(ref path, ref sub_patterns) => {
1564 self.smart_resolve_path(
1568 PathSource::TupleStruct(
1570 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
1574 PatKind::Path(ref qself, ref path) => {
1575 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
1577 PatKind::Struct(ref path, ..) => {
1578 self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
1580 PatKind::Or(ref ps) => {
1581 // Add a new set of bindings to the stack. `Or` here records that when a
1582 // binding already exists in this set, it should not result in an error because
1583 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
1584 bindings.push((PatBoundCtx::Or, Default::default()));
1586 // Now we need to switch back to a product context so that each
1587 // part of the or-pattern internally rejects already bound names.
1588 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
1589 bindings.push((PatBoundCtx::Product, Default::default()));
1590 self.resolve_pattern_inner(p, pat_src, bindings);
1591 // Move up the non-overlapping bindings to the or-pattern.
1592 // Existing bindings just get "merged".
1593 let collected = bindings.pop().unwrap().1;
1594 bindings.last_mut().unwrap().1.extend(collected);
1596 // This or-pattern itself can itself be part of a product,
1597 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
1598 // Both cases bind `a` again in a product pattern and must be rejected.
1599 let collected = bindings.pop().unwrap().1;
1600 bindings.last_mut().unwrap().1.extend(collected);
1602 // Prevent visiting `ps` as we've already done so above.
1615 pat_src: PatternSource,
1616 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
1618 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
1619 // (We must not add it if it's in the bindings map because that breaks the assumptions
1620 // later passes make about or-patterns.)
1621 let ident = ident.normalize_to_macro_rules();
1623 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
1624 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
1625 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
1626 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
1627 // This is *required* for consistency which is checked later.
1628 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
1630 if already_bound_and {
1631 // Overlap in a product pattern somewhere; report an error.
1632 use ResolutionError::*;
1633 let error = match pat_src {
1634 // `fn f(a: u8, a: u8)`:
1635 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
1637 _ => IdentifierBoundMoreThanOnceInSamePattern,
1639 self.report_error(ident.span, error(ident.name));
1642 // Record as bound if it's valid:
1643 let ident_valid = ident.name != kw::Empty;
1645 bindings.last_mut().unwrap().1.insert(ident);
1648 if already_bound_or {
1649 // `Variant1(a) | Variant2(a)`, ok
1650 // Reuse definition from the first `a`.
1651 self.innermost_rib_bindings(ValueNS)[&ident]
1653 let res = Res::Local(pat_id);
1655 // A completely fresh binding add to the set if it's valid.
1656 self.innermost_rib_bindings(ValueNS).insert(ident, res);
1662 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
1663 &mut self.ribs[ns].last_mut().unwrap().bindings
1666 fn try_resolve_as_non_binding(
1668 pat_src: PatternSource,
1674 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
1675 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
1676 // also be interpreted as a path to e.g. a constant, variant, etc.
1677 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
1679 let ls_binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, pat.span)?;
1680 let (res, binding) = match ls_binding {
1681 LexicalScopeBinding::Item(binding)
1682 if is_syntactic_ambiguity && binding.is_ambiguity() =>
1684 // For ambiguous bindings we don't know all their definitions and cannot check
1685 // whether they can be shadowed by fresh bindings or not, so force an error.
1686 // issues/33118#issuecomment-233962221 (see below) still applies here,
1687 // but we have to ignore it for backward compatibility.
1688 self.r.record_use(ident, ValueNS, binding, false);
1691 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
1692 LexicalScopeBinding::Res(res) => (res, None),
1696 Res::SelfCtor(_) // See #70549.
1698 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
1700 ) if is_syntactic_ambiguity => {
1701 // Disambiguate in favor of a unit struct/variant or constant pattern.
1702 if let Some(binding) = binding {
1703 self.r.record_use(ident, ValueNS, binding, false);
1707 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static, _) => {
1708 // This is unambiguously a fresh binding, either syntactically
1709 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
1710 // to something unusable as a pattern (e.g., constructor function),
1711 // but we still conservatively report an error, see
1712 // issues/33118#issuecomment-233962221 for one reason why.
1715 ResolutionError::BindingShadowsSomethingUnacceptable(
1718 binding.expect("no binding for a ctor or static"),
1723 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
1724 // These entities are explicitly allowed to be shadowed by fresh bindings.
1729 "unexpected resolution for an identifier in pattern: {:?}",
1735 // High-level and context dependent path resolution routine.
1736 // Resolves the path and records the resolution into definition map.
1737 // If resolution fails tries several techniques to find likely
1738 // resolution candidates, suggest imports or other help, and report
1739 // errors in user friendly way.
1740 fn smart_resolve_path(
1743 qself: Option<&QSelf>,
1745 source: PathSource<'ast>,
1747 self.smart_resolve_path_fragment(
1750 &Segment::from_path(path),
1753 CrateLint::SimplePath(id),
1757 fn smart_resolve_path_fragment(
1760 qself: Option<&QSelf>,
1763 source: PathSource<'ast>,
1764 crate_lint: CrateLint,
1767 "smart_resolve_path_fragment(id={:?},qself={:?},path={:?}",
1772 let ns = source.namespace();
1774 let report_errors = |this: &mut Self, res: Option<Res>| {
1775 if this.should_report_errs() {
1776 let (err, candidates) = this.smart_resolve_report_errors(path, span, source, res);
1778 let def_id = this.parent_scope.module.nearest_parent_mod;
1779 let instead = res.is_some();
1781 if res.is_none() { this.report_missing_type_error(path) } else { None };
1783 this.r.use_injections.push(UseError {
1792 PartialRes::new(Res::Err)
1795 // For paths originating from calls (like in `HashMap::new()`), tries
1796 // to enrich the plain `failed to resolve: ...` message with hints
1797 // about possible missing imports.
1799 // Similar thing, for types, happens in `report_errors` above.
1800 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
1801 if !source.is_call() {
1802 return Some(parent_err);
1805 // Before we start looking for candidates, we have to get our hands
1806 // on the type user is trying to perform invocation on; basically:
1807 // we're transforming `HashMap::new` into just `HashMap`
1808 let path = if let Some((_, path)) = path.split_last() {
1811 return Some(parent_err);
1814 let (mut err, candidates) =
1815 this.smart_resolve_report_errors(path, span, PathSource::Type, None);
1817 if candidates.is_empty() {
1819 return Some(parent_err);
1822 // There are two different error messages user might receive at
1824 // - E0412 cannot find type `{}` in this scope
1825 // - E0433 failed to resolve: use of undeclared type or module `{}`
1827 // The first one is emitted for paths in type-position, and the
1828 // latter one - for paths in expression-position.
1830 // Thus (since we're in expression-position at this point), not to
1831 // confuse the user, we want to keep the *message* from E0432 (so
1832 // `parent_err`), but we want *hints* from E0412 (so `err`).
1834 // And that's what happens below - we're just mixing both messages
1835 // into a single one.
1836 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
1838 parent_err.cancel();
1840 err.message = take(&mut parent_err.message);
1841 err.code = take(&mut parent_err.code);
1842 err.children = take(&mut parent_err.children);
1846 let def_id = this.parent_scope.module.nearest_parent_mod;
1848 if this.should_report_errs() {
1849 this.r.use_injections.push(UseError {
1860 // We don't return `Some(parent_err)` here, because the error will
1861 // be already printed as part of the `use` injections
1865 let partial_res = match self.resolve_qpath_anywhere(
1871 source.defer_to_typeck(),
1874 Ok(Some(partial_res)) if partial_res.unresolved_segments() == 0 => {
1875 if source.is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err
1879 report_errors(self, Some(partial_res.base_res()))
1883 Ok(Some(partial_res)) if source.defer_to_typeck() => {
1884 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
1885 // or `<T>::A::B`. If `B` should be resolved in value namespace then
1886 // it needs to be added to the trait map.
1888 let item_name = path.last().unwrap().ident;
1889 let traits = self.get_traits_containing_item(item_name, ns);
1890 self.r.trait_map.insert(id, traits);
1893 if self.r.primitive_type_table.primitive_types.contains_key(&path[0].ident.name) {
1894 let mut std_path = Vec::with_capacity(1 + path.len());
1896 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
1897 std_path.extend(path);
1898 if let PathResult::Module(_) | PathResult::NonModule(_) =
1899 self.resolve_path(&std_path, Some(ns), false, span, CrateLint::No)
1901 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
1903 path.iter().last().map(|segment| segment.ident.span).unwrap_or(span);
1905 let mut hm = self.r.session.confused_type_with_std_module.borrow_mut();
1906 hm.insert(item_span, span);
1907 hm.insert(span, span);
1915 if let Some(err) = report_errors_for_call(self, err) {
1916 self.report_error(err.span, err.node);
1919 PartialRes::new(Res::Err)
1922 _ => report_errors(self, None),
1925 if let PathSource::TraitItem(..) = source {
1927 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
1928 self.r.record_partial_res(id, partial_res);
1934 fn self_type_is_available(&mut self, span: Span) -> bool {
1935 let binding = self.resolve_ident_in_lexical_scope(
1936 Ident::with_dummy_span(kw::SelfUpper),
1941 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1944 fn self_value_is_available(&mut self, self_span: Span, path_span: Span) -> bool {
1945 let ident = Ident::new(kw::SelfLower, self_span);
1946 let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, path_span);
1947 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
1950 /// A wrapper around [`Resolver::report_error`].
1952 /// This doesn't emit errors for function bodies if this is rustdoc.
1953 fn report_error(&self, span: Span, resolution_error: ResolutionError<'_>) {
1954 if self.should_report_errs() {
1955 self.r.report_error(span, resolution_error);
1960 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
1961 fn should_report_errs(&self) -> bool {
1962 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
1965 // Resolve in alternative namespaces if resolution in the primary namespace fails.
1966 fn resolve_qpath_anywhere(
1969 qself: Option<&QSelf>,
1971 primary_ns: Namespace,
1973 defer_to_typeck: bool,
1974 crate_lint: CrateLint,
1975 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
1976 let mut fin_res = None;
1978 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
1979 if i == 0 || ns != primary_ns {
1980 match self.resolve_qpath(id, qself, path, ns, span, crate_lint)? {
1982 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
1984 return Ok(Some(partial_res));
1987 if fin_res.is_none() {
1988 fin_res = partial_res;
1995 assert!(primary_ns != MacroNS);
1997 if qself.is_none() {
1998 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
1999 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
2000 if let Ok((_, res)) =
2001 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
2003 return Ok(Some(PartialRes::new(res)));
2010 /// Handles paths that may refer to associated items.
2014 qself: Option<&QSelf>,
2018 crate_lint: CrateLint,
2019 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2021 "resolve_qpath(id={:?}, qself={:?}, path={:?}, ns={:?}, span={:?})",
2022 id, qself, path, ns, span,
2025 if let Some(qself) = qself {
2026 if qself.position == 0 {
2027 // This is a case like `<T>::B`, where there is no
2028 // trait to resolve. In that case, we leave the `B`
2029 // segment to be resolved by type-check.
2030 return Ok(Some(PartialRes::with_unresolved_segments(
2031 Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX)),
2036 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
2038 // Currently, `path` names the full item (`A::B::C`, in
2039 // our example). so we extract the prefix of that that is
2040 // the trait (the slice upto and including
2041 // `qself.position`). And then we recursively resolve that,
2042 // but with `qself` set to `None`.
2044 // However, setting `qself` to none (but not changing the
2045 // span) loses the information about where this path
2046 // *actually* appears, so for the purposes of the crate
2047 // lint we pass along information that this is the trait
2048 // name from a fully qualified path, and this also
2049 // contains the full span (the `CrateLint::QPathTrait`).
2050 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2051 let partial_res = self.smart_resolve_path_fragment(
2054 &path[..=qself.position],
2056 PathSource::TraitItem(ns),
2057 CrateLint::QPathTrait { qpath_id: id, qpath_span: qself.path_span },
2060 // The remaining segments (the `C` in our example) will
2061 // have to be resolved by type-check, since that requires doing
2062 // trait resolution.
2063 return Ok(Some(PartialRes::with_unresolved_segments(
2064 partial_res.base_res(),
2065 partial_res.unresolved_segments() + path.len() - qself.position - 1,
2069 let result = match self.resolve_path(&path, Some(ns), true, span, crate_lint) {
2070 PathResult::NonModule(path_res) => path_res,
2071 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
2072 PartialRes::new(module.res().unwrap())
2074 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2075 // don't report an error right away, but try to fallback to a primitive type.
2076 // So, we are still able to successfully resolve something like
2078 // use std::u8; // bring module u8 in scope
2079 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2080 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
2081 // // not to non-existent std::u8::max_value
2084 // Such behavior is required for backward compatibility.
2085 // The same fallback is used when `a` resolves to nothing.
2086 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
2087 if (ns == TypeNS || path.len() > 1)
2090 .primitive_type_table
2092 .contains_key(&path[0].ident.name) =>
2094 let prim = self.r.primitive_type_table.primitive_types[&path[0].ident.name];
2095 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
2097 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2098 PartialRes::new(module.res().unwrap())
2100 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
2101 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
2103 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
2104 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
2108 && result.base_res() != Res::Err
2109 && path[0].ident.name != kw::PathRoot
2110 && path[0].ident.name != kw::DollarCrate
2112 let unqualified_result = {
2113 match self.resolve_path(
2114 &[*path.last().unwrap()],
2120 PathResult::NonModule(path_res) => path_res.base_res(),
2121 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2122 module.res().unwrap()
2124 _ => return Ok(Some(result)),
2127 if result.base_res() == unqualified_result {
2128 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
2129 self.r.lint_buffer.buffer_lint(lint, id, span, "unnecessary qualification")
2136 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
2137 if let Some(label) = label {
2138 if label.ident.as_str().as_bytes()[1] != b'_' {
2139 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
2141 self.with_label_rib(NormalRibKind, |this| {
2142 let ident = label.ident.normalize_to_macro_rules();
2143 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
2151 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
2152 self.with_resolved_label(label, id, |this| this.visit_block(block));
2155 fn resolve_block(&mut self, block: &'ast Block) {
2156 debug!("(resolving block) entering block");
2157 // Move down in the graph, if there's an anonymous module rooted here.
2158 let orig_module = self.parent_scope.module;
2159 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
2161 let mut num_macro_definition_ribs = 0;
2162 if let Some(anonymous_module) = anonymous_module {
2163 debug!("(resolving block) found anonymous module, moving down");
2164 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2165 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2166 self.parent_scope.module = anonymous_module;
2168 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2171 // Descend into the block.
2172 for stmt in &block.stmts {
2173 if let StmtKind::Item(ref item) = stmt.kind {
2174 if let ItemKind::MacroDef(..) = item.kind {
2175 num_macro_definition_ribs += 1;
2176 let res = self.r.local_def_id(item.id).to_def_id();
2177 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
2178 self.label_ribs.push(Rib::new(MacroDefinition(res)));
2182 self.visit_stmt(stmt);
2186 self.parent_scope.module = orig_module;
2187 for _ in 0..num_macro_definition_ribs {
2188 self.ribs[ValueNS].pop();
2189 self.label_ribs.pop();
2191 self.ribs[ValueNS].pop();
2192 if anonymous_module.is_some() {
2193 self.ribs[TypeNS].pop();
2195 debug!("(resolving block) leaving block");
2198 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
2199 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
2200 self.with_constant_rib(
2202 constant.value.is_potential_trivial_const_param(),
2204 visit::walk_anon_const(this, constant);
2209 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
2210 // First, record candidate traits for this expression if it could
2211 // result in the invocation of a method call.
2213 self.record_candidate_traits_for_expr_if_necessary(expr);
2215 // Next, resolve the node.
2217 ExprKind::Path(ref qself, ref path) => {
2218 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
2219 visit::walk_expr(self, expr);
2222 ExprKind::Struct(ref path, ..) => {
2223 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
2224 visit::walk_expr(self, expr);
2227 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
2228 if let Some(node_id) = self.resolve_label(label.ident) {
2229 // Since this res is a label, it is never read.
2230 self.r.label_res_map.insert(expr.id, node_id);
2231 self.diagnostic_metadata.unused_labels.remove(&node_id);
2234 // visit `break` argument if any
2235 visit::walk_expr(self, expr);
2238 ExprKind::Let(ref pat, ref scrutinee) => {
2239 self.visit_expr(scrutinee);
2240 self.resolve_pattern_top(pat, PatternSource::Let);
2243 ExprKind::If(ref cond, ref then, ref opt_else) => {
2244 self.with_rib(ValueNS, NormalRibKind, |this| {
2245 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
2246 this.visit_expr(cond);
2247 this.diagnostic_metadata.in_if_condition = old;
2248 this.visit_block(then);
2250 if let Some(expr) = opt_else {
2251 self.visit_expr(expr);
2255 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
2257 ExprKind::While(ref cond, ref block, label) => {
2258 self.with_resolved_label(label, expr.id, |this| {
2259 this.with_rib(ValueNS, NormalRibKind, |this| {
2260 this.visit_expr(cond);
2261 this.visit_block(block);
2266 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
2267 self.visit_expr(iter_expr);
2268 self.with_rib(ValueNS, NormalRibKind, |this| {
2269 this.resolve_pattern_top(pat, PatternSource::For);
2270 this.resolve_labeled_block(label, expr.id, block);
2274 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
2276 // Equivalent to `visit::walk_expr` + passing some context to children.
2277 ExprKind::Field(ref subexpression, _) => {
2278 self.resolve_expr(subexpression, Some(expr));
2280 ExprKind::MethodCall(ref segment, ref arguments, _) => {
2281 let mut arguments = arguments.iter();
2282 self.resolve_expr(arguments.next().unwrap(), Some(expr));
2283 for argument in arguments {
2284 self.resolve_expr(argument, None);
2286 self.visit_path_segment(expr.span, segment);
2289 ExprKind::Call(ref callee, ref arguments) => {
2290 self.resolve_expr(callee, Some(expr));
2291 for argument in arguments {
2292 self.resolve_expr(argument, None);
2295 ExprKind::Type(ref type_expr, ref ty) => {
2296 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
2297 // type ascription. Here we are trying to retrieve the span of the colon token as
2298 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
2299 // with `expr::Ty`, only in this case it will match the span from
2300 // `type_ascription_path_suggestions`.
2301 self.diagnostic_metadata
2302 .current_type_ascription
2303 .push(type_expr.span.between(ty.span));
2304 visit::walk_expr(self, expr);
2305 self.diagnostic_metadata.current_type_ascription.pop();
2307 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
2308 // resolve the arguments within the proper scopes so that usages of them inside the
2309 // closure are detected as upvars rather than normal closure arg usages.
2310 ExprKind::Closure(_, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
2311 self.with_rib(ValueNS, NormalRibKind, |this| {
2312 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
2313 // Resolve arguments:
2314 this.resolve_params(&fn_decl.inputs);
2315 // No need to resolve return type --
2316 // the outer closure return type is `FnRetTy::Default`.
2318 // Now resolve the inner closure
2320 // No need to resolve arguments: the inner closure has none.
2321 // Resolve the return type:
2322 visit::walk_fn_ret_ty(this, &fn_decl.output);
2324 this.visit_expr(body);
2329 ExprKind::Async(..) | ExprKind::Closure(..) => {
2330 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
2332 ExprKind::Repeat(ref elem, ref ct) => {
2333 self.visit_expr(elem);
2334 self.resolve_anon_const(ct, IsRepeatExpr::Yes);
2337 visit::walk_expr(self, expr);
2342 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
2344 ExprKind::Field(_, ident) => {
2345 // FIXME(#6890): Even though you can't treat a method like a
2346 // field, we need to add any trait methods we find that match
2347 // the field name so that we can do some nice error reporting
2348 // later on in typeck.
2349 let traits = self.get_traits_containing_item(ident, ValueNS);
2350 self.r.trait_map.insert(expr.id, traits);
2352 ExprKind::MethodCall(ref segment, ..) => {
2353 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
2354 let traits = self.get_traits_containing_item(segment.ident, ValueNS);
2355 self.r.trait_map.insert(expr.id, traits);
2363 fn get_traits_containing_item(
2367 ) -> Vec<TraitCandidate> {
2368 debug!("(getting traits containing item) looking for '{}'", ident.name);
2370 let mut found_traits = Vec::new();
2371 // Look for the current trait.
2372 if let Some((module, _)) = self.current_trait_ref {
2375 .resolve_ident_in_module(
2376 ModuleOrUniformRoot::Module(module),
2385 let def_id = module.def_id().unwrap();
2386 found_traits.push(TraitCandidate { def_id, import_ids: smallvec![] });
2390 ident.span = ident.span.normalize_to_macros_2_0();
2391 let mut search_module = self.parent_scope.module;
2393 self.r.get_traits_in_module_containing_item(
2401 unwrap_or!(self.r.hygienic_lexical_parent(search_module, &mut ident.span), break);
2404 if let Some(prelude) = self.r.prelude {
2405 if !search_module.no_implicit_prelude {
2406 self.r.get_traits_in_module_containing_item(
2420 impl<'a> Resolver<'a> {
2421 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
2422 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
2423 visit::walk_crate(&mut late_resolution_visitor, krate);
2424 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
2425 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");