1 //! "Late resolution" is the pass that resolves most of names in a crate beside imports and macros.
2 //! It runs when the crate is fully expanded and its module structure is fully built.
3 //! So it just walks through the crate and resolves all the expressions, types, etc.
5 //! If you wonder why there's no `early.rs`, that's because it's split into three files -
6 //! `build_reduced_graph.rs`, `macros.rs` and `imports.rs`.
10 use crate::{path_names_to_string, BindingError, Finalize, LexicalScopeBinding};
11 use crate::{Module, ModuleOrUniformRoot, NameBinding, ParentScope, PathResult};
12 use crate::{ResolutionError, Resolver, Segment, UseError};
14 use rustc_ast::ptr::P;
15 use rustc_ast::visit::{self, AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor};
17 use rustc_ast_lowering::{LifetimeRes, ResolverAstLowering};
18 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
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_ID};
23 use rustc_hir::definitions::DefPathData;
24 use rustc_hir::{PrimTy, TraitCandidate};
25 use rustc_index::vec::Idx;
26 use rustc_middle::ty::DefIdTree;
27 use rustc_middle::{bug, span_bug};
28 use rustc_session::lint;
29 use rustc_span::symbol::{kw, sym, Ident, Symbol};
30 use rustc_span::{BytePos, Span};
31 use smallvec::{smallvec, SmallVec};
33 use rustc_span::source_map::{respan, Spanned};
34 use std::collections::{hash_map::Entry, BTreeSet};
35 use std::mem::{replace, take};
41 type Res = def::Res<NodeId>;
43 type IdentMap<T> = FxHashMap<Ident, T>;
45 /// Map from the name in a pattern to its binding mode.
46 type BindingMap = IdentMap<BindingInfo>;
48 #[derive(Copy, Clone, Debug)]
51 binding_mode: BindingMode,
54 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
62 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
69 fn descr(self) -> &'static str {
71 PatternSource::Match => "match binding",
72 PatternSource::Let => "let binding",
73 PatternSource::For => "for binding",
74 PatternSource::FnParam => "function parameter",
79 /// Denotes whether the context for the set of already bound bindings is a `Product`
80 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
81 /// See those functions for more information.
84 /// A product pattern context, e.g., `Variant(a, b)`.
86 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
90 /// Does this the item (from the item rib scope) allow generic parameters?
91 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
92 crate enum HasGenericParams {
97 impl HasGenericParams {
98 fn force_yes_if(self, b: bool) -> Self {
99 if b { Self::Yes } else { self }
103 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
104 crate enum ConstantItemKind {
109 /// The rib kind restricts certain accesses,
110 /// e.g. to a `Res::Local` of an outer item.
111 #[derive(Copy, Clone, Debug)]
112 crate enum RibKind<'a> {
113 /// No restriction needs to be applied.
116 /// We passed through an impl or trait and are now in one of its
117 /// methods or associated types. Allow references to ty params that impl or trait
118 /// binds. Disallow any other upvars (including other ty params that are
122 /// We passed through a closure. Disallow labels.
123 ClosureOrAsyncRibKind,
125 /// We passed through a function definition. Disallow upvars.
126 /// Permit only those const parameters that are specified in the function's generics.
129 /// We passed through an item scope. Disallow upvars.
130 ItemRibKind(HasGenericParams),
132 /// We're in a constant item. Can't refer to dynamic stuff.
134 /// The item may reference generic parameters in trivial constant expressions.
135 /// All other constants aren't allowed to use generic params at all.
136 ConstantItemRibKind(HasGenericParams, Option<(Ident, ConstantItemKind)>),
138 /// We passed through a module.
139 ModuleRibKind(Module<'a>),
141 /// We passed through a `macro_rules!` statement
142 MacroDefinition(DefId),
144 /// All bindings in this rib are generic parameters that can't be used
145 /// from the default of a generic parameter because they're not declared
146 /// before said generic parameter. Also see the `visit_generics` override.
147 ForwardGenericParamBanRibKind,
149 /// We are inside of the type of a const parameter. Can't refer to any
153 /// We are inside a `sym` inline assembly operand. Can only refer to
159 /// Whether this rib kind contains generic parameters, as opposed to local
161 crate fn contains_params(&self) -> bool {
164 | ClosureOrAsyncRibKind
166 | ConstantItemRibKind(..)
169 | ConstParamTyRibKind
170 | InlineAsmSymRibKind => false,
171 AssocItemRibKind | ItemRibKind(_) | ForwardGenericParamBanRibKind => true,
176 /// A single local scope.
178 /// A rib represents a scope names can live in. Note that these appear in many places, not just
179 /// around braces. At any place where the list of accessible names (of the given namespace)
180 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
181 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
184 /// Different [rib kinds](enum.RibKind) are transparent for different names.
186 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
187 /// resolving, the name is looked up from inside out.
189 crate struct Rib<'a, R = Res> {
190 pub bindings: IdentMap<R>,
191 pub kind: RibKind<'a>,
194 impl<'a, R> Rib<'a, R> {
195 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
196 Rib { bindings: Default::default(), kind }
200 #[derive(Copy, Clone, Debug)]
201 enum LifetimeRibKind {
202 /// This rib acts as a barrier to forbid reference to lifetimes of a parent item.
205 /// This rib declares generic parameters.
206 Generics { parent: NodeId, span: Span, kind: LifetimeBinderKind },
208 /// FIXME(const_generics): This patches over an ICE caused by non-'static lifetimes in const
209 /// generics. We are disallowing this until we can decide on how we want to handle non-'static
210 /// lifetimes in const generics. See issue #74052 for discussion.
213 /// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`.
214 /// This function will emit an error if `generic_const_exprs` is not enabled, the body identified by
215 /// `body_id` is an anonymous constant and `lifetime_ref` is non-static.
218 /// For **Modern** cases, create a new anonymous region parameter
219 /// and reference that.
221 /// For **Dyn Bound** cases, pass responsibility to
222 /// `resolve_lifetime` code.
224 /// For **Deprecated** cases, report an error.
225 AnonymousCreateParameter(NodeId),
227 /// Give a hard error when either `&` or `'_` is written. Used to
228 /// rule out things like `where T: Foo<'_>`. Does not imply an
229 /// error on default object bounds (e.g., `Box<dyn Foo>`).
230 AnonymousReportError,
232 /// Pass responsibility to `resolve_lifetime` code for all cases.
233 AnonymousPassThrough(NodeId),
236 #[derive(Copy, Clone, Debug)]
237 enum LifetimeBinderKind {
246 impl LifetimeBinderKind {
247 fn descr(self) -> &'static str {
248 use LifetimeBinderKind::*;
250 BareFnType => "type",
251 PolyTrait => "bound",
252 WhereBound => "bound",
254 ImplBlock => "impl block",
255 Function => "function",
262 kind: LifetimeRibKind,
263 // We need to preserve insertion order for async fns.
264 bindings: FxIndexMap<Ident, (NodeId, LifetimeRes)>,
268 fn new(kind: LifetimeRibKind) -> LifetimeRib {
269 LifetimeRib { bindings: Default::default(), kind }
273 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
274 crate enum AliasPossibility {
279 #[derive(Copy, Clone, Debug)]
280 crate enum PathSource<'a> {
281 // Type paths `Path`.
283 // Trait paths in bounds or impls.
284 Trait(AliasPossibility),
285 // Expression paths `path`, with optional parent context.
286 Expr(Option<&'a Expr>),
287 // Paths in path patterns `Path`.
289 // Paths in struct expressions and patterns `Path { .. }`.
291 // Paths in tuple struct patterns `Path(..)`.
292 TupleStruct(Span, &'a [Span]),
293 // `m::A::B` in `<T as m::A>::B::C`.
294 TraitItem(Namespace),
297 impl<'a> PathSource<'a> {
298 fn namespace(self) -> Namespace {
300 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
301 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
302 PathSource::TraitItem(ns) => ns,
306 fn defer_to_typeck(self) -> bool {
309 | PathSource::Expr(..)
312 | PathSource::TupleStruct(..) => true,
313 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
317 fn descr_expected(self) -> &'static str {
319 PathSource::Type => "type",
320 PathSource::Trait(_) => "trait",
321 PathSource::Pat => "unit struct, unit variant or constant",
322 PathSource::Struct => "struct, variant or union type",
323 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
324 PathSource::TraitItem(ns) => match ns {
325 TypeNS => "associated type",
326 ValueNS => "method or associated constant",
327 MacroNS => bug!("associated macro"),
329 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
330 // "function" here means "anything callable" rather than `DefKind::Fn`,
331 // this is not precise but usually more helpful than just "value".
332 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
333 // the case of `::some_crate()`
334 ExprKind::Path(_, path)
335 if path.segments.len() == 2
336 && path.segments[0].ident.name == kw::PathRoot =>
340 ExprKind::Path(_, path) => {
341 let mut msg = "function";
342 if let Some(segment) = path.segments.iter().last() {
343 if let Some(c) = segment.ident.to_string().chars().next() {
344 if c.is_uppercase() {
345 msg = "function, tuple struct or tuple variant";
358 fn is_call(self) -> bool {
359 matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
362 crate fn is_expected(self, res: Res) -> bool {
364 PathSource::Type => matches!(
371 | DefKind::TraitAlias
376 | DefKind::ForeignTy,
381 PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
382 PathSource::Trait(AliasPossibility::Maybe) => {
383 matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
385 PathSource::Expr(..) => matches!(
388 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
393 | DefKind::AssocConst
394 | DefKind::ConstParam,
400 res.expected_in_unit_struct_pat()
401 || matches!(res, Res::Def(DefKind::Const | DefKind::AssocConst, _))
403 PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
404 PathSource::Struct => matches!(
413 ) | Res::SelfTy { .. }
415 PathSource::TraitItem(ns) => match res {
416 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
417 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
423 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
424 use rustc_errors::error_code;
425 match (self, has_unexpected_resolution) {
426 (PathSource::Trait(_), true) => error_code!(E0404),
427 (PathSource::Trait(_), false) => error_code!(E0405),
428 (PathSource::Type, true) => error_code!(E0573),
429 (PathSource::Type, false) => error_code!(E0412),
430 (PathSource::Struct, true) => error_code!(E0574),
431 (PathSource::Struct, false) => error_code!(E0422),
432 (PathSource::Expr(..), true) => error_code!(E0423),
433 (PathSource::Expr(..), false) => error_code!(E0425),
434 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
435 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
436 (PathSource::TraitItem(..), true) => error_code!(E0575),
437 (PathSource::TraitItem(..), false) => error_code!(E0576),
443 struct DiagnosticMetadata<'ast> {
444 /// The current trait's associated items' ident, used for diagnostic suggestions.
445 current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
447 /// The current self type if inside an impl (used for better errors).
448 current_self_type: Option<Ty>,
450 /// The current self item if inside an ADT (used for better errors).
451 current_self_item: Option<NodeId>,
453 /// The current trait (used to suggest).
454 current_item: Option<&'ast Item>,
456 /// When processing generics and encountering a type not found, suggest introducing a type
458 currently_processing_generics: bool,
460 /// The current enclosing (non-closure) function (used for better errors).
461 current_function: Option<(FnKind<'ast>, Span)>,
463 /// A list of labels as of yet unused. Labels will be removed from this map when
464 /// they are used (in a `break` or `continue` statement)
465 unused_labels: FxHashMap<NodeId, Span>,
467 /// Only used for better errors on `fn(): fn()`.
468 current_type_ascription: Vec<Span>,
470 /// Only used for better errors on `let x = { foo: bar };`.
471 /// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only
472 /// needed for cases where this parses as a correct type ascription.
473 current_block_could_be_bare_struct_literal: Option<Span>,
475 /// Only used for better errors on `let <pat>: <expr, not type>;`.
476 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
478 /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
479 in_if_condition: Option<&'ast Expr>,
481 /// If we are currently in a trait object definition. Used to point at the bounds when
482 /// encountering a struct or enum.
483 current_trait_object: Option<&'ast [ast::GenericBound]>,
485 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
486 current_where_predicate: Option<&'ast WherePredicate>,
488 current_type_path: Option<&'ast Ty>,
491 struct LateResolutionVisitor<'a, 'b, 'ast> {
492 r: &'b mut Resolver<'a>,
494 /// The module that represents the current item scope.
495 parent_scope: ParentScope<'a>,
497 /// The current set of local scopes for types and values.
498 /// FIXME #4948: Reuse ribs to avoid allocation.
499 ribs: PerNS<Vec<Rib<'a>>>,
501 /// The current set of local scopes, for labels.
502 label_ribs: Vec<Rib<'a, NodeId>>,
504 /// The current set of local scopes for lifetimes.
505 lifetime_ribs: Vec<LifetimeRib>,
507 /// The trait that the current context can refer to.
508 current_trait_ref: Option<(Module<'a>, TraitRef)>,
510 /// Fields used to add information to diagnostic errors.
511 diagnostic_metadata: DiagnosticMetadata<'ast>,
513 /// State used to know whether to ignore resolution errors for function bodies.
515 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
516 /// In most cases this will be `None`, in which case errors will always be reported.
517 /// If it is `true`, then it will be updated when entering a nested function or trait body.
521 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
522 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
523 fn visit_attribute(&mut self, _: &'ast Attribute) {
524 // We do not want to resolve expressions that appear in attributes,
525 // as they do not correspond to actual code.
527 fn visit_item(&mut self, item: &'ast Item) {
528 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
529 // Always report errors in items we just entered.
530 let old_ignore = replace(&mut self.in_func_body, false);
531 self.with_lifetime_rib(LifetimeRibKind::Item, |this| this.resolve_item(item));
532 self.in_func_body = old_ignore;
533 self.diagnostic_metadata.current_item = prev;
535 fn visit_arm(&mut self, arm: &'ast Arm) {
536 self.resolve_arm(arm);
538 fn visit_block(&mut self, block: &'ast Block) {
539 self.resolve_block(block);
541 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
542 // We deal with repeat expressions explicitly in `resolve_expr`.
543 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
544 this.resolve_anon_const(constant, IsRepeatExpr::No);
547 fn visit_expr(&mut self, expr: &'ast Expr) {
548 self.resolve_expr(expr, None);
550 fn visit_local(&mut self, local: &'ast Local) {
551 let local_spans = match local.pat.kind {
552 // We check for this to avoid tuple struct fields.
553 PatKind::Wild => None,
556 local.ty.as_ref().map(|ty| ty.span),
557 local.kind.init().map(|init| init.span),
560 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
561 self.resolve_local(local);
562 self.diagnostic_metadata.current_let_binding = original;
564 fn visit_ty(&mut self, ty: &'ast Ty) {
565 let prev = self.diagnostic_metadata.current_trait_object;
566 let prev_ty = self.diagnostic_metadata.current_type_path;
568 TyKind::Rptr(None, _) => {
569 // Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
571 let span = self.r.session.source_map().next_point(ty.span.shrink_to_lo());
572 self.resolve_elided_lifetime(ty.id, span);
574 TyKind::Path(ref qself, ref path) => {
575 self.diagnostic_metadata.current_type_path = Some(ty);
576 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
578 TyKind::ImplicitSelf => {
579 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
581 .resolve_ident_in_lexical_scope(
584 Some(Finalize::new(ty.id, ty.span)),
587 .map_or(Res::Err, |d| d.res());
588 self.r.record_partial_res(ty.id, PartialRes::new(res));
590 TyKind::TraitObject(ref bounds, ..) => {
591 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
593 TyKind::BareFn(ref bare_fn) => {
594 let span = if bare_fn.generic_params.is_empty() {
595 ty.span.shrink_to_lo()
599 self.with_generic_param_rib(
600 &bare_fn.generic_params,
602 LifetimeRibKind::Generics {
604 kind: LifetimeBinderKind::BareFnType,
608 this.with_lifetime_rib(
609 LifetimeRibKind::AnonymousPassThrough(ty.id),
611 this.visit_generic_param_vec(&bare_fn.generic_params, false);
612 visit::walk_fn_decl(this, &bare_fn.decl);
617 self.diagnostic_metadata.current_trait_object = prev;
622 visit::walk_ty(self, ty);
623 self.diagnostic_metadata.current_trait_object = prev;
624 self.diagnostic_metadata.current_type_path = prev_ty;
626 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef, _: &'ast TraitBoundModifier) {
628 if tref.bound_generic_params.is_empty() { tref.span.shrink_to_lo() } else { tref.span };
629 self.with_generic_param_rib(
630 &tref.bound_generic_params,
632 LifetimeRibKind::Generics {
633 parent: tref.trait_ref.ref_id,
634 kind: LifetimeBinderKind::PolyTrait,
638 this.visit_generic_param_vec(&tref.bound_generic_params, false);
639 this.smart_resolve_path(
640 tref.trait_ref.ref_id,
642 &tref.trait_ref.path,
643 PathSource::Trait(AliasPossibility::Maybe),
645 this.visit_trait_ref(&tref.trait_ref);
649 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
650 match foreign_item.kind {
651 ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
652 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
653 this.with_generic_param_rib(
655 ItemRibKind(HasGenericParams::Yes),
656 LifetimeRibKind::Generics {
657 parent: foreign_item.id,
658 kind: LifetimeBinderKind::Item,
661 |this| visit::walk_foreign_item(this, foreign_item),
665 ForeignItemKind::Fn(box Fn { ref generics, .. }) => {
666 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
667 this.with_generic_param_rib(
669 ItemRibKind(HasGenericParams::Yes),
670 LifetimeRibKind::Generics {
671 parent: foreign_item.id,
672 kind: LifetimeBinderKind::Function,
675 |this| visit::walk_foreign_item(this, foreign_item),
679 ForeignItemKind::Static(..) => {
680 self.with_item_rib(|this| {
681 visit::walk_foreign_item(this, foreign_item);
684 ForeignItemKind::MacCall(..) => {
685 panic!("unexpanded macro in resolve!")
689 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, fn_id: NodeId) {
690 let rib_kind = match fn_kind {
691 // Bail if the function is foreign, and thus cannot validly have
692 // a body, or if there's no body for some other reason.
693 FnKind::Fn(FnCtxt::Foreign, _, sig, _, generics, _)
694 | FnKind::Fn(_, _, sig, _, generics, None) => {
695 self.with_lifetime_rib(LifetimeRibKind::AnonymousPassThrough(fn_id), |this| {
696 // We don't need to deal with patterns in parameters, because
697 // they are not possible for foreign or bodiless functions.
698 this.visit_fn_header(&sig.header);
699 this.visit_generics(generics);
700 visit::walk_fn_decl(this, &sig.decl);
704 FnKind::Fn(FnCtxt::Free, ..) => FnItemRibKind,
705 FnKind::Fn(FnCtxt::Assoc(_), ..) => NormalRibKind,
706 FnKind::Closure(..) => ClosureOrAsyncRibKind,
708 let previous_value = self.diagnostic_metadata.current_function;
709 if matches!(fn_kind, FnKind::Fn(..)) {
710 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
712 debug!("(resolving function) entering function");
713 let declaration = fn_kind.decl();
715 // Create a value rib for the function.
716 self.with_rib(ValueNS, rib_kind, |this| {
717 // Create a label rib for the function.
718 this.with_label_rib(rib_kind, |this| {
719 let async_node_id = fn_kind.header().and_then(|h| h.asyncness.opt_return_id());
721 if let FnKind::Fn(_, _, _, _, generics, _) = fn_kind {
722 this.visit_generics(generics);
725 if let Some(async_node_id) = async_node_id {
726 // In `async fn`, argument-position elided lifetimes
727 // must be transformed into fresh generic parameters so that
728 // they can be applied to the opaque `impl Trait` return type.
729 this.with_lifetime_rib(
730 LifetimeRibKind::AnonymousCreateParameter(fn_id),
732 // Add each argument to the rib.
733 this.resolve_params(&declaration.inputs)
737 // Construct the list of in-scope lifetime parameters for async lowering.
738 // We include all lifetime parameters, either named or "Fresh".
739 // The order of those parameters does not matter, as long as it is
741 let mut extra_lifetime_params =
742 this.r.extra_lifetime_params_map.get(&fn_id).cloned().unwrap_or_default();
743 for rib in this.lifetime_ribs.iter().rev() {
744 extra_lifetime_params.extend(
747 .map(|(&ident, &(node_id, res))| (ident, node_id, res)),
750 LifetimeRibKind::Item => break,
751 LifetimeRibKind::AnonymousCreateParameter(id) => {
752 if let Some(earlier_fresh) =
753 this.r.extra_lifetime_params_map.get(&id)
755 extra_lifetime_params.extend(earlier_fresh);
761 this.r.extra_lifetime_params_map.insert(async_node_id, extra_lifetime_params);
763 this.with_lifetime_rib(
764 LifetimeRibKind::AnonymousPassThrough(async_node_id),
765 |this| visit::walk_fn_ret_ty(this, &declaration.output),
768 this.with_lifetime_rib(LifetimeRibKind::AnonymousPassThrough(fn_id), |this| {
769 // Add each argument to the rib.
770 this.resolve_params(&declaration.inputs);
772 visit::walk_fn_ret_ty(this, &declaration.output);
776 // Ignore errors in function bodies if this is rustdoc
777 // Be sure not to set this until the function signature has been resolved.
778 let previous_state = replace(&mut this.in_func_body, true);
779 // Resolve the function body, potentially inside the body of an async closure
780 this.with_lifetime_rib(LifetimeRibKind::AnonymousPassThrough(fn_id), |this| {
782 FnKind::Fn(.., body) => walk_list!(this, visit_block, body),
783 FnKind::Closure(_, body) => this.visit_expr(body),
787 debug!("(resolving function) leaving function");
788 this.in_func_body = previous_state;
791 self.diagnostic_metadata.current_function = previous_value;
793 fn visit_lifetime(&mut self, lifetime: &'ast Lifetime) {
794 self.resolve_lifetime(lifetime)
797 fn visit_generics(&mut self, generics: &'ast Generics) {
798 self.visit_generic_param_vec(
800 self.diagnostic_metadata.current_self_item.is_some(),
802 for p in &generics.where_clause.predicates {
803 self.visit_where_predicate(p);
807 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
808 debug!("visit_generic_arg({:?})", arg);
809 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
811 GenericArg::Type(ref ty) => {
812 // We parse const arguments as path types as we cannot distinguish them during
813 // parsing. We try to resolve that ambiguity by attempting resolution the type
814 // namespace first, and if that fails we try again in the value namespace. If
815 // resolution in the value namespace succeeds, we have an generic const argument on
817 if let TyKind::Path(ref qself, ref path) = ty.kind {
818 // We cannot disambiguate multi-segment paths right now as that requires type
820 if path.segments.len() == 1 && path.segments[0].args.is_none() {
821 let mut check_ns = |ns| {
822 self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns)
825 if !check_ns(TypeNS) && check_ns(ValueNS) {
826 // This must be equivalent to `visit_anon_const`, but we cannot call it
827 // directly due to visitor lifetimes so we have to copy-paste some code.
829 // Note that we might not be inside of an repeat expression here,
830 // but considering that `IsRepeatExpr` is only relevant for
831 // non-trivial constants this is doesn't matter.
832 self.with_constant_rib(
834 HasGenericParams::Yes,
837 this.smart_resolve_path(
841 PathSource::Expr(None),
844 if let Some(ref qself) = *qself {
845 this.visit_ty(&qself.ty);
847 this.visit_path(path, ty.id);
851 self.diagnostic_metadata.currently_processing_generics = prev;
859 GenericArg::Lifetime(lt) => self.visit_lifetime(lt),
860 GenericArg::Const(ct) => self.visit_anon_const(ct),
862 self.diagnostic_metadata.currently_processing_generics = prev;
865 fn visit_path_segment(&mut self, path_span: Span, path_segment: &'ast PathSegment) {
866 if let Some(ref args) = path_segment.args {
868 GenericArgs::AngleBracketed(..) => visit::walk_generic_args(self, path_span, args),
869 GenericArgs::Parenthesized(..) => self.with_lifetime_rib(
870 LifetimeRibKind::AnonymousPassThrough(path_segment.id),
871 |this| visit::walk_generic_args(this, path_span, args),
877 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
878 debug!("visit_where_predicate {:?}", p);
880 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
881 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
882 if let WherePredicate::BoundPredicate(WhereBoundPredicate {
885 ref bound_generic_params,
886 span: predicate_span,
890 let span = if bound_generic_params.is_empty() {
891 predicate_span.shrink_to_lo()
895 this.with_generic_param_rib(
896 &bound_generic_params,
898 LifetimeRibKind::Generics {
899 parent: bounded_ty.id,
900 kind: LifetimeBinderKind::WhereBound,
904 this.visit_generic_param_vec(&bound_generic_params, false);
905 this.visit_ty(bounded_ty);
906 for bound in bounds {
907 this.visit_param_bound(bound, BoundKind::Bound)
912 visit::walk_where_predicate(this, p);
915 self.diagnostic_metadata.current_where_predicate = previous_value;
918 fn visit_inline_asm_sym(&mut self, sym: &'ast InlineAsmSym) {
919 // This is similar to the code for AnonConst.
920 self.with_rib(ValueNS, InlineAsmSymRibKind, |this| {
921 this.with_rib(TypeNS, InlineAsmSymRibKind, |this| {
922 this.with_label_rib(InlineAsmSymRibKind, |this| {
923 this.smart_resolve_path(
927 PathSource::Expr(None),
929 visit::walk_inline_asm_sym(this, sym);
936 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
937 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
938 // During late resolution we only track the module component of the parent scope,
939 // although it may be useful to track other components as well for diagnostics.
940 let graph_root = resolver.graph_root;
941 let parent_scope = ParentScope::module(graph_root, resolver);
942 let start_rib_kind = ModuleRibKind(graph_root);
943 LateResolutionVisitor {
947 value_ns: vec![Rib::new(start_rib_kind)],
948 type_ns: vec![Rib::new(start_rib_kind)],
949 macro_ns: vec![Rib::new(start_rib_kind)],
951 label_ribs: Vec::new(),
952 lifetime_ribs: Vec::new(),
953 current_trait_ref: None,
954 diagnostic_metadata: DiagnosticMetadata::default(),
955 // errors at module scope should always be reported
960 fn maybe_resolve_ident_in_lexical_scope(
964 ) -> Option<LexicalScopeBinding<'a>> {
965 self.r.resolve_ident_in_lexical_scope(
975 fn resolve_ident_in_lexical_scope(
979 finalize: Option<Finalize>,
980 ignore_binding: Option<&'a NameBinding<'a>>,
981 ) -> Option<LexicalScopeBinding<'a>> {
982 self.r.resolve_ident_in_lexical_scope(
995 opt_ns: Option<Namespace>, // `None` indicates a module path in import
996 finalize: Option<Finalize>,
997 ) -> PathResult<'a> {
998 self.r.resolve_path_with_ribs(
1010 // We maintain a list of value ribs and type ribs.
1012 // Simultaneously, we keep track of the current position in the module
1013 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
1014 // the value or type namespaces, we first look through all the ribs and
1015 // then query the module graph. When we resolve a name in the module
1016 // namespace, we can skip all the ribs (since nested modules are not
1017 // allowed within blocks in Rust) and jump straight to the current module
1020 // Named implementations are handled separately. When we find a method
1021 // call, we consult the module node to find all of the implementations in
1022 // scope. This information is lazily cached in the module node. We then
1023 // generate a fake "implementation scope" containing all the
1024 // implementations thus found, for compatibility with old resolve pass.
1026 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
1031 work: impl FnOnce(&mut Self) -> T,
1033 self.ribs[ns].push(Rib::new(kind));
1034 let ret = work(self);
1035 self.ribs[ns].pop();
1039 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
1040 if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
1041 // Move down in the graph.
1042 let orig_module = replace(&mut self.parent_scope.module, module);
1043 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
1044 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
1046 this.parent_scope.module = orig_module;
1055 fn visit_generic_param_vec(&mut self, params: &'ast Vec<GenericParam>, add_self_upper: bool) {
1056 // For type parameter defaults, we have to ban access
1057 // to following type parameters, as the InternalSubsts can only
1058 // provide previous type parameters as they're built. We
1059 // put all the parameters on the ban list and then remove
1060 // them one by one as they are processed and become available.
1061 let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1062 let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1063 for param in params.iter() {
1065 GenericParamKind::Type { .. } => {
1068 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1070 GenericParamKind::Const { .. } => {
1071 forward_const_ban_rib
1073 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1075 GenericParamKind::Lifetime => {}
1079 // rust-lang/rust#61631: The type `Self` is essentially
1080 // another type parameter. For ADTs, we consider it
1081 // well-defined only after all of the ADT type parameters have
1082 // been provided. Therefore, we do not allow use of `Self`
1083 // anywhere in ADT type parameter defaults.
1085 // (We however cannot ban `Self` for defaults on *all* generic
1086 // lists; e.g. trait generics can usefully refer to `Self`,
1087 // such as in the case of `trait Add<Rhs = Self>`.)
1089 // (`Some` if + only if we are in ADT's generics.)
1090 forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
1093 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1094 for param in params {
1096 GenericParamKind::Lifetime => {
1097 for bound in ¶m.bounds {
1098 this.visit_param_bound(bound, BoundKind::Bound);
1101 GenericParamKind::Type { ref default } => {
1102 for bound in ¶m.bounds {
1103 this.visit_param_bound(bound, BoundKind::Bound);
1106 if let Some(ref ty) = default {
1107 this.ribs[TypeNS].push(forward_ty_ban_rib);
1108 this.ribs[ValueNS].push(forward_const_ban_rib);
1110 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1111 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1114 // Allow all following defaults to refer to this type parameter.
1117 .remove(&Ident::with_dummy_span(param.ident.name));
1119 GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
1120 // Const parameters can't have param bounds.
1121 assert!(param.bounds.is_empty());
1123 this.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
1124 this.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
1125 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1128 this.ribs[TypeNS].pop().unwrap();
1129 this.ribs[ValueNS].pop().unwrap();
1131 if let Some(ref expr) = default {
1132 this.ribs[TypeNS].push(forward_ty_ban_rib);
1133 this.ribs[ValueNS].push(forward_const_ban_rib);
1134 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1135 this.resolve_anon_const(expr, IsRepeatExpr::No)
1137 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1138 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1141 // Allow all following defaults to refer to this const parameter.
1142 forward_const_ban_rib
1144 .remove(&Ident::with_dummy_span(param.ident.name));
1151 #[tracing::instrument(level = "debug", skip(self, work))]
1152 fn with_lifetime_rib<T>(
1154 kind: LifetimeRibKind,
1155 work: impl FnOnce(&mut Self) -> T,
1157 self.lifetime_ribs.push(LifetimeRib::new(kind));
1158 let ret = work(self);
1159 self.lifetime_ribs.pop();
1163 #[tracing::instrument(level = "debug", skip(self))]
1164 fn resolve_lifetime(&mut self, lifetime: &'ast Lifetime) {
1165 let ident = lifetime.ident;
1167 if ident.name == kw::StaticLifetime {
1168 self.record_lifetime_res(lifetime.id, LifetimeRes::Static);
1172 if ident.name == kw::UnderscoreLifetime {
1173 return self.resolve_anonymous_lifetime(lifetime, false);
1176 let mut indices = (0..self.lifetime_ribs.len()).rev();
1177 for i in &mut indices {
1178 let rib = &self.lifetime_ribs[i];
1179 let normalized_ident = ident.normalize_to_macros_2_0();
1180 if let Some(&(_, region)) = rib.bindings.get(&normalized_ident) {
1181 self.record_lifetime_res(lifetime.id, region);
1186 LifetimeRibKind::Item => break,
1187 LifetimeRibKind::ConstGeneric => {
1188 self.emit_non_static_lt_in_const_generic_error(lifetime);
1189 self.r.lifetimes_res_map.insert(lifetime.id, LifetimeRes::Error);
1192 LifetimeRibKind::AnonConst => {
1193 self.maybe_emit_forbidden_non_static_lifetime_error(lifetime);
1194 self.r.lifetimes_res_map.insert(lifetime.id, LifetimeRes::Error);
1201 let mut outer_res = None;
1203 let rib = &self.lifetime_ribs[i];
1204 let normalized_ident = ident.normalize_to_macros_2_0();
1205 if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) {
1206 outer_res = Some(outer);
1211 self.emit_undeclared_lifetime_error(lifetime, outer_res);
1212 self.record_lifetime_res(lifetime.id, LifetimeRes::Error);
1215 #[tracing::instrument(level = "debug", skip(self))]
1216 fn resolve_anonymous_lifetime(&mut self, lifetime: &Lifetime, elided: bool) {
1217 debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
1219 for i in (0..self.lifetime_ribs.len()).rev() {
1220 let rib = &mut self.lifetime_ribs[i];
1222 LifetimeRibKind::AnonymousCreateParameter(item_node_id) => {
1223 self.create_fresh_lifetime(lifetime.id, lifetime.ident, item_node_id);
1226 LifetimeRibKind::AnonymousReportError => {
1227 let (msg, note) = if elided {
1229 "`&` without an explicit lifetime name cannot be used here",
1230 "explicit lifetime name needed here",
1233 ("`'_` cannot be used here", "`'_` is a reserved lifetime name")
1235 rustc_errors::struct_span_err!(
1237 lifetime.ident.span,
1242 .span_label(lifetime.ident.span, note)
1245 self.record_lifetime_res(lifetime.id, LifetimeRes::Error);
1248 LifetimeRibKind::AnonymousPassThrough(node_id) => {
1249 self.record_lifetime_res(
1251 LifetimeRes::Anonymous { binder: node_id, elided },
1255 LifetimeRibKind::Item => break,
1259 // This resolution is wrong, it passes the work to HIR lifetime resolution.
1260 // We cannot use `LifetimeRes::Error` because we do not emit a diagnostic.
1261 self.record_lifetime_res(
1263 LifetimeRes::Anonymous { binder: DUMMY_NODE_ID, elided },
1267 #[tracing::instrument(level = "debug", skip(self))]
1268 fn resolve_elided_lifetime(&mut self, anchor_id: NodeId, span: Span) {
1269 let id = self.r.next_node_id();
1270 self.record_lifetime_res(
1272 LifetimeRes::ElidedAnchor { start: id, end: NodeId::from_u32(id.as_u32() + 1) },
1275 let lt = Lifetime { id, ident: Ident::new(kw::UnderscoreLifetime, span) };
1276 self.resolve_anonymous_lifetime(<, true);
1279 #[tracing::instrument(level = "debug", skip(self))]
1280 fn create_fresh_lifetime(&mut self, id: NodeId, ident: Ident, item_node_id: NodeId) {
1281 debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
1282 debug!(?ident.span);
1283 let item_def_id = self.r.local_def_id(item_node_id);
1284 let def_node_id = self.r.next_node_id();
1285 let def_id = self.r.create_def(
1288 DefPathData::LifetimeNs(kw::UnderscoreLifetime),
1289 self.parent_scope.expansion.to_expn_id(),
1294 let region = LifetimeRes::Fresh { param: def_id, binder: item_node_id };
1295 self.record_lifetime_res(id, region);
1296 self.r.extra_lifetime_params_map.entry(item_node_id).or_insert_with(Vec::new).push((
1303 #[tracing::instrument(level = "debug", skip(self))]
1304 fn resolve_elided_lifetimes_in_path(
1307 partial_res: PartialRes,
1309 source: PathSource<'_>,
1312 let proj_start = path.len() - partial_res.unresolved_segments();
1313 for (i, segment) in path.iter().enumerate() {
1314 if segment.has_lifetime_args {
1317 let Some(segment_id) = segment.id else {
1321 // Figure out if this is a type/trait segment,
1322 // which may need lifetime elision performed.
1323 let type_def_id = match partial_res.base_res() {
1324 Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => self.r.parent(def_id),
1325 Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => self.r.parent(def_id),
1326 Res::Def(DefKind::Struct, def_id)
1327 | Res::Def(DefKind::Union, def_id)
1328 | Res::Def(DefKind::Enum, def_id)
1329 | Res::Def(DefKind::TyAlias, def_id)
1330 | Res::Def(DefKind::Trait, def_id)
1331 if i + 1 == proj_start =>
1338 let expected_lifetimes = self.r.item_generics_num_lifetimes(type_def_id);
1339 if expected_lifetimes == 0 {
1343 let missing = match source {
1344 PathSource::Trait(..) | PathSource::TraitItem(..) | PathSource::Type => true,
1345 PathSource::Expr(..)
1347 | PathSource::Struct
1348 | PathSource::TupleStruct(..) => false,
1350 let mut res = LifetimeRes::Error;
1351 for rib in self.lifetime_ribs.iter().rev() {
1353 // In create-parameter mode we error here because we don't want to support
1354 // deprecated impl elision in new features like impl elision and `async fn`,
1355 // both of which work using the `CreateParameter` mode:
1357 // impl Foo for std::cell::Ref<u32> // note lack of '_
1358 // async fn foo(_: std::cell::Ref<u32>) { ... }
1359 LifetimeRibKind::AnonymousCreateParameter(_) => {
1362 // `PassThrough` is the normal case.
1363 // `new_error_lifetime`, which would usually be used in the case of `ReportError`,
1364 // is unsuitable here, as these can occur from missing lifetime parameters in a
1365 // `PathSegment`, for which there is no associated `'_` or `&T` with no explicit
1366 // lifetime. Instead, we simply create an implicit lifetime, which will be checked
1367 // later, at which point a suitable error will be emitted.
1368 LifetimeRibKind::AnonymousPassThrough(binder) => {
1369 res = LifetimeRes::Anonymous { binder, elided: true };
1372 LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
1373 // FIXME(cjgillot) This resolution is wrong, but this does not matter
1374 // since these cases are erroneous anyway. Lifetime resolution should
1375 // emit a "missing lifetime specifier" diagnostic.
1376 res = LifetimeRes::Anonymous { binder: DUMMY_NODE_ID, elided: true };
1383 let node_ids = self.r.next_node_ids(expected_lifetimes);
1384 self.record_lifetime_res(
1386 LifetimeRes::ElidedAnchor { start: node_ids.start, end: node_ids.end },
1388 for i in 0..expected_lifetimes {
1389 let id = node_ids.start.plus(i);
1390 self.record_lifetime_res(id, res);
1397 let elided_lifetime_span = if segment.has_generic_args {
1398 // If there are brackets, but not generic arguments, then use the opening bracket
1399 segment.args_span.with_hi(segment.args_span.lo() + BytePos(1))
1401 // If there are no brackets, use the identifier span.
1402 // HACK: we use find_ancestor_inside to properly suggest elided spans in paths
1403 // originating from macros, since the segment's span might be from a macro arg.
1404 segment.ident.span.find_ancestor_inside(path_span).unwrap_or(path_span)
1406 if let LifetimeRes::Error = res {
1407 let sess = self.r.session;
1408 let mut err = rustc_errors::struct_span_err!(
1412 "implicit elided lifetime not allowed here"
1414 rustc_errors::add_elided_lifetime_in_path_suggestion(
1419 !segment.has_generic_args,
1420 elided_lifetime_span,
1422 err.note("assuming a `'static` lifetime...");
1425 self.r.lint_buffer.buffer_lint_with_diagnostic(
1426 lint::builtin::ELIDED_LIFETIMES_IN_PATHS,
1428 elided_lifetime_span,
1429 "hidden lifetime parameters in types are deprecated",
1430 lint::BuiltinLintDiagnostics::ElidedLifetimesInPaths(
1433 !segment.has_generic_args,
1434 elided_lifetime_span,
1441 #[tracing::instrument(level = "debug", skip(self))]
1442 fn record_lifetime_res(&mut self, id: NodeId, res: LifetimeRes) {
1443 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1445 "lifetime {:?} resolved multiple times ({:?} before, {:?} now)",
1451 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
1452 /// label and reports an error if the label is not found or is unreachable.
1453 fn resolve_label(&mut self, mut label: Ident) -> Option<NodeId> {
1454 let mut suggestion = None;
1456 // Preserve the original span so that errors contain "in this macro invocation"
1458 let original_span = label.span;
1460 for i in (0..self.label_ribs.len()).rev() {
1461 let rib = &self.label_ribs[i];
1463 if let MacroDefinition(def) = rib.kind {
1464 // If an invocation of this macro created `ident`, give up on `ident`
1465 // and switch to `ident`'s source from the macro definition.
1466 if def == self.r.macro_def(label.span.ctxt()) {
1467 label.span.remove_mark();
1471 let ident = label.normalize_to_macro_rules();
1472 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
1473 let definition_span = ident.span;
1474 return if self.is_label_valid_from_rib(i) {
1479 ResolutionError::UnreachableLabel {
1490 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
1491 // the first such label that is encountered.
1492 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
1497 ResolutionError::UndeclaredLabel { name: label.name, suggestion },
1502 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
1503 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
1504 let ribs = &self.label_ribs[rib_index + 1..];
1508 NormalRibKind | MacroDefinition(..) => {
1509 // Nothing to do. Continue.
1513 | ClosureOrAsyncRibKind
1516 | ConstantItemRibKind(..)
1518 | ForwardGenericParamBanRibKind
1519 | ConstParamTyRibKind
1520 | InlineAsmSymRibKind => {
1529 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
1530 debug!("resolve_adt");
1531 self.with_current_self_item(item, |this| {
1532 this.with_generic_param_rib(
1534 ItemRibKind(HasGenericParams::Yes),
1535 LifetimeRibKind::Generics {
1537 kind: LifetimeBinderKind::Item,
1538 span: generics.span,
1541 let item_def_id = this.r.local_def_id(item.id).to_def_id();
1543 Res::SelfTy { trait_: None, alias_to: Some((item_def_id, false)) },
1545 visit::walk_item(this, item);
1553 fn future_proof_import(&mut self, use_tree: &UseTree) {
1554 let segments = &use_tree.prefix.segments;
1555 if !segments.is_empty() {
1556 let ident = segments[0].ident;
1557 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
1561 let nss = match use_tree.kind {
1562 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
1565 let report_error = |this: &Self, ns| {
1566 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
1567 if this.should_report_errs() {
1570 .span_err(ident.span, &format!("imports cannot refer to {}", what));
1575 match self.maybe_resolve_ident_in_lexical_scope(ident, ns) {
1576 Some(LexicalScopeBinding::Res(..)) => {
1577 report_error(self, ns);
1579 Some(LexicalScopeBinding::Item(binding)) => {
1580 if let Some(LexicalScopeBinding::Res(..)) =
1581 self.resolve_ident_in_lexical_scope(ident, ns, None, Some(binding))
1583 report_error(self, ns);
1589 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
1590 for (use_tree, _) in use_trees {
1591 self.future_proof_import(use_tree);
1596 fn resolve_item(&mut self, item: &'ast Item) {
1597 let name = item.ident.name;
1598 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
1601 ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
1602 self.with_generic_param_rib(
1604 ItemRibKind(HasGenericParams::Yes),
1605 LifetimeRibKind::Generics {
1607 kind: LifetimeBinderKind::Item,
1608 span: generics.span,
1610 |this| visit::walk_item(this, item),
1614 ItemKind::Fn(box Fn { ref generics, .. }) => {
1615 self.with_generic_param_rib(
1617 ItemRibKind(HasGenericParams::Yes),
1618 LifetimeRibKind::Generics {
1620 kind: LifetimeBinderKind::Function,
1621 span: generics.span,
1623 |this| visit::walk_item(this, item),
1627 ItemKind::Enum(_, ref generics)
1628 | ItemKind::Struct(_, ref generics)
1629 | ItemKind::Union(_, ref generics) => {
1630 self.resolve_adt(item, generics);
1633 ItemKind::Impl(box Impl {
1637 items: ref impl_items,
1640 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
1643 ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
1644 // Create a new rib for the trait-wide type parameters.
1645 self.with_generic_param_rib(
1647 ItemRibKind(HasGenericParams::Yes),
1648 LifetimeRibKind::Generics {
1650 kind: LifetimeBinderKind::Item,
1651 span: generics.span,
1654 let local_def_id = this.r.local_def_id(item.id).to_def_id();
1656 Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
1658 this.visit_generics(generics);
1659 walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);
1661 let walk_assoc_item =
1663 generics: &Generics,
1665 item: &'ast AssocItem| {
1666 this.with_generic_param_rib(
1669 LifetimeRibKind::Generics {
1671 span: generics.span,
1675 visit::walk_assoc_item(this, item, AssocCtxt::Trait)
1680 this.with_trait_items(items, |this| {
1683 AssocItemKind::Const(_, ty, default) => {
1685 // Only impose the restrictions of `ConstRibKind` for an
1686 // actual constant expression in a provided default.
1687 if let Some(expr) = default {
1688 // We allow arbitrary const expressions inside of associated consts,
1689 // even if they are potentially not const evaluatable.
1691 // Type parameters can already be used and as associated consts are
1692 // not used as part of the type system, this is far less surprising.
1693 this.with_constant_rib(
1695 HasGenericParams::Yes,
1697 |this| this.visit_expr(expr),
1701 AssocItemKind::Fn(box Fn { generics, .. }) => {
1705 LifetimeBinderKind::Function,
1709 AssocItemKind::TyAlias(box TyAlias {
1716 LifetimeBinderKind::Item,
1720 AssocItemKind::MacCall(_) => {
1721 panic!("unexpanded macro in resolve!")
1732 ItemKind::TraitAlias(ref generics, ref bounds) => {
1733 // Create a new rib for the trait-wide type parameters.
1734 self.with_generic_param_rib(
1736 ItemRibKind(HasGenericParams::Yes),
1737 LifetimeRibKind::Generics {
1739 kind: LifetimeBinderKind::Item,
1740 span: generics.span,
1743 let local_def_id = this.r.local_def_id(item.id).to_def_id();
1745 Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
1747 this.visit_generics(generics);
1748 walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
1755 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
1756 self.with_scope(item.id, |this| {
1757 visit::walk_item(this, item);
1761 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
1762 self.with_item_rib(|this| {
1764 if let Some(expr) = expr {
1765 let constant_item_kind = match item.kind {
1766 ItemKind::Const(..) => ConstantItemKind::Const,
1767 ItemKind::Static(..) => ConstantItemKind::Static,
1768 _ => unreachable!(),
1770 // We already forbid generic params because of the above item rib,
1771 // so it doesn't matter whether this is a trivial constant.
1772 this.with_constant_rib(
1774 HasGenericParams::Yes,
1775 Some((item.ident, constant_item_kind)),
1776 |this| this.visit_expr(expr),
1782 ItemKind::Use(ref use_tree) => {
1783 self.future_proof_import(use_tree);
1786 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => {
1787 // do nothing, these are just around to be encoded
1790 ItemKind::GlobalAsm(_) => {
1791 visit::walk_item(self, item);
1794 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
1798 fn with_generic_param_rib<'c, F>(
1800 params: &'c Vec<GenericParam>,
1802 lifetime_kind: LifetimeRibKind,
1805 F: FnOnce(&mut Self),
1807 debug!("with_generic_param_rib");
1808 let mut function_type_rib = Rib::new(kind);
1809 let mut function_value_rib = Rib::new(kind);
1810 let mut function_lifetime_rib = LifetimeRib::new(lifetime_kind);
1811 let mut seen_bindings = FxHashMap::default();
1813 // We also can't shadow bindings from the parent item
1814 if let AssocItemRibKind = kind {
1815 let mut add_bindings_for_ns = |ns| {
1816 let parent_rib = self.ribs[ns]
1818 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
1819 .expect("associated item outside of an item");
1821 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
1823 add_bindings_for_ns(ValueNS);
1824 add_bindings_for_ns(TypeNS);
1827 for param in params {
1828 let ident = param.ident.normalize_to_macros_2_0();
1829 debug!("with_generic_param_rib: {}", param.id);
1831 match seen_bindings.entry(ident) {
1832 Entry::Occupied(entry) => {
1833 let span = *entry.get();
1834 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
1835 if !matches!(param.kind, GenericParamKind::Lifetime) {
1836 self.report_error(param.ident.span, err);
1839 Entry::Vacant(entry) => {
1840 entry.insert(param.ident.span);
1844 if param.ident.name == kw::UnderscoreLifetime {
1845 rustc_errors::struct_span_err!(
1849 "`'_` cannot be used here"
1851 .span_label(param.ident.span, "`'_` is a reserved lifetime name")
1856 if param.ident.name == kw::StaticLifetime {
1857 rustc_errors::struct_span_err!(
1861 "invalid lifetime parameter name: `{}`",
1864 .span_label(param.ident.span, "'static is a reserved lifetime name")
1869 let def_id = self.r.local_def_id(param.id);
1871 // Plain insert (no renaming).
1872 let (rib, def_kind) = match param.kind {
1873 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
1874 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
1875 GenericParamKind::Lifetime => {
1876 let LifetimeRibKind::Generics { parent, .. } = lifetime_kind else { panic!() };
1877 let res = LifetimeRes::Param { param: def_id, binder: parent };
1878 self.record_lifetime_res(param.id, res);
1879 function_lifetime_rib.bindings.insert(ident, (param.id, res));
1883 let res = Res::Def(def_kind, def_id.to_def_id());
1884 self.r.record_partial_res(param.id, PartialRes::new(res));
1885 rib.bindings.insert(ident, res);
1888 self.lifetime_ribs.push(function_lifetime_rib);
1889 self.ribs[ValueNS].push(function_value_rib);
1890 self.ribs[TypeNS].push(function_type_rib);
1894 self.ribs[TypeNS].pop();
1895 self.ribs[ValueNS].pop();
1896 self.lifetime_ribs.pop();
1899 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
1900 self.label_ribs.push(Rib::new(kind));
1902 self.label_ribs.pop();
1905 fn with_item_rib(&mut self, f: impl FnOnce(&mut Self)) {
1906 let kind = ItemRibKind(HasGenericParams::No);
1907 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
1908 this.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
1912 // HACK(min_const_generics,const_evaluatable_unchecked): We
1913 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
1914 // with a future compat lint for now. We do this by adding an
1915 // additional special case for repeat expressions.
1917 // Note that we intentionally still forbid `[0; N + 1]` during
1918 // name resolution so that we don't extend the future
1919 // compat lint to new cases.
1920 #[instrument(level = "debug", skip(self, f))]
1921 fn with_constant_rib(
1923 is_repeat: IsRepeatExpr,
1924 may_use_generics: HasGenericParams,
1925 item: Option<(Ident, ConstantItemKind)>,
1926 f: impl FnOnce(&mut Self),
1928 self.with_rib(ValueNS, ConstantItemRibKind(may_use_generics, item), |this| {
1931 ConstantItemRibKind(
1932 may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes),
1936 this.with_label_rib(ConstantItemRibKind(may_use_generics, item), f);
1942 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
1943 // Handle nested impls (inside fn bodies)
1944 let previous_value =
1945 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
1946 let result = f(self);
1947 self.diagnostic_metadata.current_self_type = previous_value;
1951 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
1952 let previous_value =
1953 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
1954 let result = f(self);
1955 self.diagnostic_metadata.current_self_item = previous_value;
1959 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
1960 fn with_trait_items<T>(
1962 trait_items: &'ast [P<AssocItem>],
1963 f: impl FnOnce(&mut Self) -> T,
1965 let trait_assoc_items =
1966 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
1967 let result = f(self);
1968 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
1972 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
1973 fn with_optional_trait_ref<T>(
1975 opt_trait_ref: Option<&TraitRef>,
1976 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
1978 let mut new_val = None;
1979 let mut new_id = None;
1980 if let Some(trait_ref) = opt_trait_ref {
1981 let path: Vec<_> = Segment::from_path(&trait_ref.path);
1982 let res = self.smart_resolve_path_fragment(
1985 PathSource::Trait(AliasPossibility::No),
1986 Finalize::new(trait_ref.ref_id, trait_ref.path.span),
1988 if let Some(def_id) = res.base_res().opt_def_id() {
1989 new_id = Some(def_id);
1990 new_val = Some((self.r.expect_module(def_id), trait_ref.clone()));
1993 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1994 let result = f(self, new_id);
1995 self.current_trait_ref = original_trait_ref;
1999 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
2000 let mut self_type_rib = Rib::new(NormalRibKind);
2002 // Plain insert (no renaming, since types are not currently hygienic)
2003 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
2004 self.ribs[ns].push(self_type_rib);
2006 self.ribs[ns].pop();
2009 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
2010 self.with_self_rib_ns(TypeNS, self_res, f)
2013 fn resolve_implementation(
2015 generics: &'ast Generics,
2016 opt_trait_reference: &'ast Option<TraitRef>,
2017 self_type: &'ast Ty,
2019 impl_items: &'ast [P<AssocItem>],
2021 debug!("resolve_implementation");
2022 // If applicable, create a rib for the type parameters.
2023 self.with_generic_param_rib(&generics.params, ItemRibKind(HasGenericParams::Yes), LifetimeRibKind::Generics { span: generics.span, parent: item_id, kind: LifetimeBinderKind::ImplBlock }, |this| {
2024 // Dummy self type for better errors if `Self` is used in the trait path.
2025 this.with_self_rib(Res::SelfTy { trait_: None, alias_to: None }, |this| {
2026 this.with_lifetime_rib(LifetimeRibKind::AnonymousCreateParameter(item_id), |this| {
2027 // Resolve the trait reference, if necessary.
2028 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
2029 let item_def_id = this.r.local_def_id(item_id);
2031 // Register the trait definitions from here.
2032 if let Some(trait_id) = trait_id {
2033 this.r.trait_impls.entry(trait_id).or_default().push(item_def_id);
2036 let item_def_id = item_def_id.to_def_id();
2038 Res::SelfTy { trait_: trait_id, alias_to: Some((item_def_id, false)) };
2039 this.with_self_rib(res, |this| {
2040 if let Some(trait_ref) = opt_trait_reference.as_ref() {
2041 // Resolve type arguments in the trait path.
2042 visit::walk_trait_ref(this, trait_ref);
2044 // Resolve the self type.
2045 this.visit_ty(self_type);
2046 // Resolve the generic parameters.
2047 this.visit_generics(generics);
2049 // Resolve the items within the impl.
2050 this.with_lifetime_rib(LifetimeRibKind::AnonymousPassThrough(item_id),
2052 this.with_current_self_type(self_type, |this| {
2053 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
2054 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
2055 for item in impl_items {
2056 use crate::ResolutionError::*;
2058 AssocItemKind::Const(_default, _ty, _expr) => {
2059 debug!("resolve_implementation AssocItemKind::Const");
2060 // If this is a trait impl, ensure the const
2062 this.check_trait_item(
2068 |i, s, c| ConstNotMemberOfTrait(i, s, c),
2071 // We allow arbitrary const expressions inside of associated consts,
2072 // even if they are potentially not const evaluatable.
2074 // Type parameters can already be used and as associated consts are
2075 // not used as part of the type system, this is far less surprising.
2076 this.with_constant_rib(
2078 HasGenericParams::Yes,
2081 visit::walk_assoc_item(
2089 AssocItemKind::Fn(box Fn { generics, .. }) => {
2090 debug!("resolve_implementation AssocItemKind::Fn");
2091 // We also need a new scope for the impl item type parameters.
2092 this.with_generic_param_rib(
2095 LifetimeRibKind::Generics { parent: item.id, span: generics.span, kind: LifetimeBinderKind::Function },
2097 // If this is a trait impl, ensure the method
2099 this.check_trait_item(
2105 |i, s, c| MethodNotMemberOfTrait(i, s, c),
2108 visit::walk_assoc_item(
2116 AssocItemKind::TyAlias(box TyAlias {
2119 debug!("resolve_implementation AssocItemKind::TyAlias");
2120 // We also need a new scope for the impl item type parameters.
2121 this.with_generic_param_rib(
2124 LifetimeRibKind::Generics { parent: item.id, span: generics.span, kind: LifetimeBinderKind::Item },
2126 // If this is a trait impl, ensure the type
2128 this.check_trait_item(
2134 |i, s, c| TypeNotMemberOfTrait(i, s, c),
2137 visit::walk_assoc_item(
2145 AssocItemKind::MacCall(_) => {
2146 panic!("unexpanded macro in resolve!")
2161 fn check_trait_item<F>(
2165 kind: &AssocItemKind,
2170 F: FnOnce(Ident, String, Option<Symbol>) -> ResolutionError<'a>,
2172 // If there is a TraitRef in scope for an impl, then the method must be in the trait.
2173 let Some((module, _)) = &self.current_trait_ref else { return; };
2174 ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
2175 let key = self.r.new_key(ident, ns);
2176 let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2178 if binding.is_none() {
2179 // We could not find the trait item in the correct namespace.
2180 // Check the other namespace to report an error.
2186 let key = self.r.new_key(ident, ns);
2187 binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2190 let Some(binding) = binding else {
2191 // We could not find the method: report an error.
2192 let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
2193 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2194 let path_names = path_names_to_string(path);
2195 self.report_error(span, err(ident, path_names, candidate));
2199 let res = binding.res();
2200 let Res::Def(def_kind, _) = res else { bug!() };
2201 match (def_kind, kind) {
2202 (DefKind::AssocTy, AssocItemKind::TyAlias(..))
2203 | (DefKind::AssocFn, AssocItemKind::Fn(..))
2204 | (DefKind::AssocConst, AssocItemKind::Const(..)) => {
2205 self.r.record_partial_res(id, PartialRes::new(res));
2211 // The method kind does not correspond to what appeared in the trait, report.
2212 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2213 let (code, kind) = match kind {
2214 AssocItemKind::Const(..) => (rustc_errors::error_code!(E0323), "const"),
2215 AssocItemKind::Fn(..) => (rustc_errors::error_code!(E0324), "method"),
2216 AssocItemKind::TyAlias(..) => (rustc_errors::error_code!(E0325), "type"),
2217 AssocItemKind::MacCall(..) => span_bug!(span, "unexpanded macro"),
2219 let trait_path = path_names_to_string(path);
2222 ResolutionError::TraitImplMismatch {
2227 trait_item_span: binding.span,
2232 fn resolve_params(&mut self, params: &'ast [Param]) {
2233 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2234 for Param { pat, ty, .. } in params {
2235 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
2237 debug!("(resolving function / closure) recorded parameter");
2241 fn resolve_local(&mut self, local: &'ast Local) {
2242 debug!("resolving local ({:?})", local);
2243 // Resolve the type.
2244 walk_list!(self, visit_ty, &local.ty);
2246 // Resolve the initializer.
2247 if let Some((init, els)) = local.kind.init_else_opt() {
2248 self.visit_expr(init);
2250 // Resolve the `else` block
2251 if let Some(els) = els {
2252 self.visit_block(els);
2256 // Resolve the pattern.
2257 self.resolve_pattern_top(&local.pat, PatternSource::Let);
2260 /// build a map from pattern identifiers to binding-info's.
2261 /// this is done hygienically. This could arise for a macro
2262 /// that expands into an or-pattern where one 'x' was from the
2263 /// user and one 'x' came from the macro.
2264 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2265 let mut binding_map = FxHashMap::default();
2267 pat.walk(&mut |pat| {
2269 PatKind::Ident(binding_mode, ident, ref sub_pat)
2270 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
2272 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
2274 PatKind::Or(ref ps) => {
2275 // Check the consistency of this or-pattern and
2276 // then add all bindings to the larger map.
2277 for bm in self.check_consistent_bindings(ps) {
2278 binding_map.extend(bm);
2291 fn is_base_res_local(&self, nid: NodeId) -> bool {
2292 matches!(self.r.partial_res_map.get(&nid).map(|res| res.base_res()), Some(Res::Local(..)))
2295 /// Checks that all of the arms in an or-pattern have exactly the
2296 /// same set of bindings, with the same binding modes for each.
2297 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
2298 let mut missing_vars = FxHashMap::default();
2299 let mut inconsistent_vars = FxHashMap::default();
2301 // 1) Compute the binding maps of all arms.
2302 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
2304 // 2) Record any missing bindings or binding mode inconsistencies.
2305 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
2306 // Check against all arms except for the same pattern which is always self-consistent.
2310 .filter(|(_, pat)| pat.id != pat_outer.id)
2311 .flat_map(|(idx, _)| maps[idx].iter())
2312 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
2314 for (name, info, &binding_inner) in inners {
2317 // The inner binding is missing in the outer.
2319 missing_vars.entry(name).or_insert_with(|| BindingError {
2321 origin: BTreeSet::new(),
2322 target: BTreeSet::new(),
2323 could_be_path: name.as_str().starts_with(char::is_uppercase),
2325 binding_error.origin.insert(binding_inner.span);
2326 binding_error.target.insert(pat_outer.span);
2328 Some(binding_outer) => {
2329 if binding_outer.binding_mode != binding_inner.binding_mode {
2330 // The binding modes in the outer and inner bindings differ.
2333 .or_insert((binding_inner.span, binding_outer.span));
2340 // 3) Report all missing variables we found.
2341 let mut missing_vars = missing_vars.into_iter().collect::<Vec<_>>();
2342 missing_vars.sort_by_key(|&(sym, ref _err)| sym);
2344 for (name, mut v) in missing_vars.into_iter() {
2345 if inconsistent_vars.contains_key(&name) {
2346 v.could_be_path = false;
2349 *v.origin.iter().next().unwrap(),
2350 ResolutionError::VariableNotBoundInPattern(v, self.parent_scope),
2354 // 4) Report all inconsistencies in binding modes we found.
2355 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
2356 inconsistent_vars.sort();
2357 for (name, v) in inconsistent_vars {
2358 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
2361 // 5) Finally bubble up all the binding maps.
2365 /// Check the consistency of the outermost or-patterns.
2366 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
2367 pat.walk(&mut |pat| match pat.kind {
2368 PatKind::Or(ref ps) => {
2369 self.check_consistent_bindings(ps);
2376 fn resolve_arm(&mut self, arm: &'ast Arm) {
2377 self.with_rib(ValueNS, NormalRibKind, |this| {
2378 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
2379 walk_list!(this, visit_expr, &arm.guard);
2380 this.visit_expr(&arm.body);
2384 /// Arising from `source`, resolve a top level pattern.
2385 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
2386 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2387 self.resolve_pattern(pat, pat_src, &mut bindings);
2393 pat_src: PatternSource,
2394 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
2396 // We walk the pattern before declaring the pattern's inner bindings,
2397 // so that we avoid resolving a literal expression to a binding defined
2399 visit::walk_pat(self, pat);
2400 self.resolve_pattern_inner(pat, pat_src, bindings);
2401 // This has to happen *after* we determine which pat_idents are variants:
2402 self.check_consistent_bindings_top(pat);
2405 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
2409 /// A stack of sets of bindings accumulated.
2411 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
2412 /// be interpreted as re-binding an already bound binding. This results in an error.
2413 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
2414 /// in reusing this binding rather than creating a fresh one.
2416 /// When called at the top level, the stack must have a single element
2417 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
2418 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
2419 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
2420 /// When each `p_i` has been dealt with, the top set is merged with its parent.
2421 /// When a whole or-pattern has been dealt with, the thing happens.
2423 /// See the implementation and `fresh_binding` for more details.
2424 fn resolve_pattern_inner(
2427 pat_src: PatternSource,
2428 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
2430 // Visit all direct subpatterns of this pattern.
2431 pat.walk(&mut |pat| {
2432 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
2434 PatKind::Ident(bmode, ident, ref sub) => {
2435 // First try to resolve the identifier as some existing entity,
2436 // then fall back to a fresh binding.
2437 let has_sub = sub.is_some();
2439 .try_resolve_as_non_binding(pat_src, bmode, ident, has_sub)
2440 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
2441 self.r.record_partial_res(pat.id, PartialRes::new(res));
2442 self.r.record_pat_span(pat.id, pat.span);
2444 PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
2445 self.smart_resolve_path(
2449 PathSource::TupleStruct(
2451 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
2455 PatKind::Path(ref qself, ref path) => {
2456 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
2458 PatKind::Struct(ref qself, ref path, ..) => {
2459 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Struct);
2461 PatKind::Or(ref ps) => {
2462 // Add a new set of bindings to the stack. `Or` here records that when a
2463 // binding already exists in this set, it should not result in an error because
2464 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
2465 bindings.push((PatBoundCtx::Or, Default::default()));
2467 // Now we need to switch back to a product context so that each
2468 // part of the or-pattern internally rejects already bound names.
2469 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
2470 bindings.push((PatBoundCtx::Product, Default::default()));
2471 self.resolve_pattern_inner(p, pat_src, bindings);
2472 // Move up the non-overlapping bindings to the or-pattern.
2473 // Existing bindings just get "merged".
2474 let collected = bindings.pop().unwrap().1;
2475 bindings.last_mut().unwrap().1.extend(collected);
2477 // This or-pattern itself can itself be part of a product,
2478 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
2479 // Both cases bind `a` again in a product pattern and must be rejected.
2480 let collected = bindings.pop().unwrap().1;
2481 bindings.last_mut().unwrap().1.extend(collected);
2483 // Prevent visiting `ps` as we've already done so above.
2496 pat_src: PatternSource,
2497 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
2499 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
2500 // (We must not add it if it's in the bindings map because that breaks the assumptions
2501 // later passes make about or-patterns.)
2502 let ident = ident.normalize_to_macro_rules();
2504 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
2505 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
2506 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
2507 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
2508 // This is *required* for consistency which is checked later.
2509 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
2511 if already_bound_and {
2512 // Overlap in a product pattern somewhere; report an error.
2513 use ResolutionError::*;
2514 let error = match pat_src {
2515 // `fn f(a: u8, a: u8)`:
2516 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
2518 _ => IdentifierBoundMoreThanOnceInSamePattern,
2520 self.report_error(ident.span, error(ident.name));
2523 // Record as bound if it's valid:
2524 let ident_valid = ident.name != kw::Empty;
2526 bindings.last_mut().unwrap().1.insert(ident);
2529 if already_bound_or {
2530 // `Variant1(a) | Variant2(a)`, ok
2531 // Reuse definition from the first `a`.
2532 self.innermost_rib_bindings(ValueNS)[&ident]
2534 let res = Res::Local(pat_id);
2536 // A completely fresh binding add to the set if it's valid.
2537 self.innermost_rib_bindings(ValueNS).insert(ident, res);
2543 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
2544 &mut self.ribs[ns].last_mut().unwrap().bindings
2547 fn try_resolve_as_non_binding(
2549 pat_src: PatternSource,
2554 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
2555 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
2556 // also be interpreted as a path to e.g. a constant, variant, etc.
2557 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
2559 let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?;
2560 let (res, binding) = match ls_binding {
2561 LexicalScopeBinding::Item(binding)
2562 if is_syntactic_ambiguity && binding.is_ambiguity() =>
2564 // For ambiguous bindings we don't know all their definitions and cannot check
2565 // whether they can be shadowed by fresh bindings or not, so force an error.
2566 // issues/33118#issuecomment-233962221 (see below) still applies here,
2567 // but we have to ignore it for backward compatibility.
2568 self.r.record_use(ident, binding, false);
2571 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
2572 LexicalScopeBinding::Res(res) => (res, None),
2576 Res::SelfCtor(_) // See #70549.
2578 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
2580 ) if is_syntactic_ambiguity => {
2581 // Disambiguate in favor of a unit struct/variant or constant pattern.
2582 if let Some(binding) = binding {
2583 self.r.record_use(ident, binding, false);
2587 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static(_), _) => {
2588 // This is unambiguously a fresh binding, either syntactically
2589 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
2590 // to something unusable as a pattern (e.g., constructor function),
2591 // but we still conservatively report an error, see
2592 // issues/33118#issuecomment-233962221 for one reason why.
2593 let binding = binding.expect("no binding for a ctor or static");
2596 ResolutionError::BindingShadowsSomethingUnacceptable {
2597 shadowing_binding_descr: pat_src.descr(),
2599 participle: if binding.is_import() { "imported" } else { "defined" },
2600 article: binding.res().article(),
2601 shadowed_binding_descr: binding.res().descr(),
2602 shadowed_binding_span: binding.span,
2607 Res::Def(DefKind::ConstParam, def_id) => {
2608 // Same as for DefKind::Const above, but here, `binding` is `None`, so we
2609 // have to construct the error differently
2612 ResolutionError::BindingShadowsSomethingUnacceptable {
2613 shadowing_binding_descr: pat_src.descr(),
2615 participle: "defined",
2616 article: res.article(),
2617 shadowed_binding_descr: res.descr(),
2618 shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"),
2623 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
2624 // These entities are explicitly allowed to be shadowed by fresh bindings.
2627 Res::SelfCtor(_) => {
2628 // We resolve `Self` in pattern position as an ident sometimes during recovery,
2629 // so delay a bug instead of ICEing.
2630 self.r.session.delay_span_bug(
2632 "unexpected `SelfCtor` in pattern, expected identifier"
2638 "unexpected resolution for an identifier in pattern: {:?}",
2644 // High-level and context dependent path resolution routine.
2645 // Resolves the path and records the resolution into definition map.
2646 // If resolution fails tries several techniques to find likely
2647 // resolution candidates, suggest imports or other help, and report
2648 // errors in user friendly way.
2649 fn smart_resolve_path(
2652 qself: Option<&QSelf>,
2654 source: PathSource<'ast>,
2656 self.smart_resolve_path_fragment(
2658 &Segment::from_path(path),
2660 Finalize::new(id, path.span),
2664 fn smart_resolve_path_fragment(
2666 qself: Option<&QSelf>,
2668 source: PathSource<'ast>,
2672 "smart_resolve_path_fragment(qself={:?}, path={:?}, finalize={:?})",
2677 let ns = source.namespace();
2679 let Finalize { node_id, path_span, .. } = finalize;
2680 let report_errors = |this: &mut Self, res: Option<Res>| {
2681 if this.should_report_errs() {
2682 let (err, candidates) =
2683 this.smart_resolve_report_errors(path, path_span, source, res);
2685 let def_id = this.parent_scope.module.nearest_parent_mod();
2686 let instead = res.is_some();
2688 if res.is_none() { this.report_missing_type_error(path) } else { None };
2690 this.r.use_injections.push(UseError {
2700 PartialRes::new(Res::Err)
2703 // For paths originating from calls (like in `HashMap::new()`), tries
2704 // to enrich the plain `failed to resolve: ...` message with hints
2705 // about possible missing imports.
2707 // Similar thing, for types, happens in `report_errors` above.
2708 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
2709 if !source.is_call() {
2710 return Some(parent_err);
2713 // Before we start looking for candidates, we have to get our hands
2714 // on the type user is trying to perform invocation on; basically:
2715 // we're transforming `HashMap::new` into just `HashMap`.
2716 let path = match path.split_last() {
2717 Some((_, path)) if !path.is_empty() => path,
2718 _ => return Some(parent_err),
2721 let (mut err, candidates) =
2722 this.smart_resolve_report_errors(path, path_span, PathSource::Type, None);
2724 if candidates.is_empty() {
2726 return Some(parent_err);
2729 // There are two different error messages user might receive at
2731 // - E0412 cannot find type `{}` in this scope
2732 // - E0433 failed to resolve: use of undeclared type or module `{}`
2734 // The first one is emitted for paths in type-position, and the
2735 // latter one - for paths in expression-position.
2737 // Thus (since we're in expression-position at this point), not to
2738 // confuse the user, we want to keep the *message* from E0432 (so
2739 // `parent_err`), but we want *hints* from E0412 (so `err`).
2741 // And that's what happens below - we're just mixing both messages
2742 // into a single one.
2743 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
2745 err.message = take(&mut parent_err.message);
2746 err.code = take(&mut parent_err.code);
2747 err.children = take(&mut parent_err.children);
2749 parent_err.cancel();
2751 let def_id = this.parent_scope.module.nearest_parent_mod();
2753 if this.should_report_errs() {
2754 this.r.use_injections.push(UseError {
2766 // We don't return `Some(parent_err)` here, because the error will
2767 // be already printed as part of the `use` injections
2771 let partial_res = match self.resolve_qpath_anywhere(
2776 source.defer_to_typeck(),
2779 Ok(Some(partial_res)) if partial_res.unresolved_segments() == 0 => {
2780 if source.is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err
2784 report_errors(self, Some(partial_res.base_res()))
2788 Ok(Some(partial_res)) if source.defer_to_typeck() => {
2789 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
2790 // or `<T>::A::B`. If `B` should be resolved in value namespace then
2791 // it needs to be added to the trait map.
2793 let item_name = path.last().unwrap().ident;
2794 let traits = self.traits_in_scope(item_name, ns);
2795 self.r.trait_map.insert(node_id, traits);
2798 if PrimTy::from_name(path[0].ident.name).is_some() {
2799 let mut std_path = Vec::with_capacity(1 + path.len());
2801 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
2802 std_path.extend(path);
2803 if let PathResult::Module(_) | PathResult::NonModule(_) =
2804 self.resolve_path(&std_path, Some(ns), None)
2806 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
2808 path.iter().last().map_or(path_span, |segment| segment.ident.span);
2810 self.r.confused_type_with_std_module.insert(item_span, path_span);
2811 self.r.confused_type_with_std_module.insert(path_span, path_span);
2819 if let Some(err) = report_errors_for_call(self, err) {
2820 self.report_error(err.span, err.node);
2823 PartialRes::new(Res::Err)
2826 _ => report_errors(self, None),
2829 if !matches!(source, PathSource::TraitItem(..)) {
2830 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
2831 self.r.record_partial_res(node_id, partial_res);
2832 self.resolve_elided_lifetimes_in_path(node_id, partial_res, path, source, path_span);
2838 fn self_type_is_available(&mut self) -> bool {
2840 .maybe_resolve_ident_in_lexical_scope(Ident::with_dummy_span(kw::SelfUpper), TypeNS);
2841 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
2844 fn self_value_is_available(&mut self, self_span: Span) -> bool {
2845 let ident = Ident::new(kw::SelfLower, self_span);
2846 let binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS);
2847 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
2850 /// A wrapper around [`Resolver::report_error`].
2852 /// This doesn't emit errors for function bodies if this is rustdoc.
2853 fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) {
2854 if self.should_report_errs() {
2855 self.r.report_error(span, resolution_error);
2860 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
2861 fn should_report_errs(&self) -> bool {
2862 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
2865 // Resolve in alternative namespaces if resolution in the primary namespace fails.
2866 fn resolve_qpath_anywhere(
2868 qself: Option<&QSelf>,
2870 primary_ns: Namespace,
2872 defer_to_typeck: bool,
2874 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2875 let mut fin_res = None;
2877 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
2878 if i == 0 || ns != primary_ns {
2879 match self.resolve_qpath(qself, path, ns, finalize)? {
2881 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
2883 return Ok(Some(partial_res));
2886 if fin_res.is_none() {
2887 fin_res = partial_res;
2894 assert!(primary_ns != MacroNS);
2896 if qself.is_none() {
2897 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
2898 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
2899 if let Ok((_, res)) =
2900 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
2902 return Ok(Some(PartialRes::new(res)));
2909 /// Handles paths that may refer to associated items.
2912 qself: Option<&QSelf>,
2916 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2918 "resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})",
2919 qself, path, ns, finalize,
2922 if let Some(qself) = qself {
2923 if qself.position == 0 {
2924 // This is a case like `<T>::B`, where there is no
2925 // trait to resolve. In that case, we leave the `B`
2926 // segment to be resolved by type-check.
2927 return Ok(Some(PartialRes::with_unresolved_segments(
2928 Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()),
2933 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
2935 // Currently, `path` names the full item (`A::B::C`, in
2936 // our example). so we extract the prefix of that that is
2937 // the trait (the slice upto and including
2938 // `qself.position`). And then we recursively resolve that,
2939 // but with `qself` set to `None`.
2940 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2941 let partial_res = self.smart_resolve_path_fragment(
2943 &path[..=qself.position],
2944 PathSource::TraitItem(ns),
2945 Finalize::with_root_span(finalize.node_id, finalize.path_span, qself.path_span),
2948 // The remaining segments (the `C` in our example) will
2949 // have to be resolved by type-check, since that requires doing
2950 // trait resolution.
2951 return Ok(Some(PartialRes::with_unresolved_segments(
2952 partial_res.base_res(),
2953 partial_res.unresolved_segments() + path.len() - qself.position - 1,
2957 let result = match self.resolve_path(&path, Some(ns), Some(finalize)) {
2958 PathResult::NonModule(path_res) => path_res,
2959 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
2960 PartialRes::new(module.res().unwrap())
2962 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2963 // don't report an error right away, but try to fallback to a primitive type.
2964 // So, we are still able to successfully resolve something like
2966 // use std::u8; // bring module u8 in scope
2967 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2968 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
2969 // // not to non-existent std::u8::max_value
2972 // Such behavior is required for backward compatibility.
2973 // The same fallback is used when `a` resolves to nothing.
2974 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
2975 if (ns == TypeNS || path.len() > 1)
2976 && PrimTy::from_name(path[0].ident.name).is_some() =>
2978 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
2979 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
2981 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2982 PartialRes::new(module.res().unwrap())
2984 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
2985 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
2987 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
2988 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
2992 && result.base_res() != Res::Err
2993 && path[0].ident.name != kw::PathRoot
2994 && path[0].ident.name != kw::DollarCrate
2996 let unqualified_result = {
2997 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
2998 PathResult::NonModule(path_res) => path_res.base_res(),
2999 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3000 module.res().unwrap()
3002 _ => return Ok(Some(result)),
3005 if result.base_res() == unqualified_result {
3006 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
3007 self.r.lint_buffer.buffer_lint(
3011 "unnecessary qualification",
3019 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
3020 if let Some(label) = label {
3021 if label.ident.as_str().as_bytes()[1] != b'_' {
3022 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
3024 self.with_label_rib(NormalRibKind, |this| {
3025 let ident = label.ident.normalize_to_macro_rules();
3026 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
3034 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
3035 self.with_resolved_label(label, id, |this| this.visit_block(block));
3038 fn resolve_block(&mut self, block: &'ast Block) {
3039 debug!("(resolving block) entering block");
3040 // Move down in the graph, if there's an anonymous module rooted here.
3041 let orig_module = self.parent_scope.module;
3042 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
3044 let mut num_macro_definition_ribs = 0;
3045 if let Some(anonymous_module) = anonymous_module {
3046 debug!("(resolving block) found anonymous module, moving down");
3047 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3048 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3049 self.parent_scope.module = anonymous_module;
3051 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3054 let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
3055 if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
3056 (block.could_be_bare_literal, &block.stmts[..])
3057 && let ExprKind::Type(..) = expr.kind
3059 self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
3062 // Descend into the block.
3063 for stmt in &block.stmts {
3064 if let StmtKind::Item(ref item) = stmt.kind
3065 && let ItemKind::MacroDef(..) = item.kind {
3066 num_macro_definition_ribs += 1;
3067 let res = self.r.local_def_id(item.id).to_def_id();
3068 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
3069 self.label_ribs.push(Rib::new(MacroDefinition(res)));
3072 self.visit_stmt(stmt);
3074 self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
3077 self.parent_scope.module = orig_module;
3078 for _ in 0..num_macro_definition_ribs {
3079 self.ribs[ValueNS].pop();
3080 self.label_ribs.pop();
3082 self.ribs[ValueNS].pop();
3083 if anonymous_module.is_some() {
3084 self.ribs[TypeNS].pop();
3086 debug!("(resolving block) leaving block");
3089 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
3090 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
3091 self.with_constant_rib(
3093 if constant.value.is_potential_trivial_const_param() {
3094 HasGenericParams::Yes
3096 HasGenericParams::No
3099 |this| visit::walk_anon_const(this, constant),
3103 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
3104 // First, record candidate traits for this expression if it could
3105 // result in the invocation of a method call.
3107 self.record_candidate_traits_for_expr_if_necessary(expr);
3109 // Next, resolve the node.
3111 ExprKind::Path(ref qself, ref path) => {
3112 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
3113 visit::walk_expr(self, expr);
3116 ExprKind::Struct(ref se) => {
3117 self.smart_resolve_path(expr.id, se.qself.as_ref(), &se.path, PathSource::Struct);
3118 visit::walk_expr(self, expr);
3121 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
3122 if let Some(node_id) = self.resolve_label(label.ident) {
3123 // Since this res is a label, it is never read.
3124 self.r.label_res_map.insert(expr.id, node_id);
3125 self.diagnostic_metadata.unused_labels.remove(&node_id);
3128 // visit `break` argument if any
3129 visit::walk_expr(self, expr);
3132 ExprKind::Break(None, Some(ref e)) => {
3133 // We use this instead of `visit::walk_expr` to keep the parent expr around for
3134 // better diagnostics.
3135 self.resolve_expr(e, Some(&expr));
3138 ExprKind::Let(ref pat, ref scrutinee, _) => {
3139 self.visit_expr(scrutinee);
3140 self.resolve_pattern_top(pat, PatternSource::Let);
3143 ExprKind::If(ref cond, ref then, ref opt_else) => {
3144 self.with_rib(ValueNS, NormalRibKind, |this| {
3145 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3146 this.visit_expr(cond);
3147 this.diagnostic_metadata.in_if_condition = old;
3148 this.visit_block(then);
3150 if let Some(expr) = opt_else {
3151 self.visit_expr(expr);
3155 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3157 ExprKind::While(ref cond, ref block, label) => {
3158 self.with_resolved_label(label, expr.id, |this| {
3159 this.with_rib(ValueNS, NormalRibKind, |this| {
3160 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3161 this.visit_expr(cond);
3162 this.diagnostic_metadata.in_if_condition = old;
3163 this.visit_block(block);
3168 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
3169 self.visit_expr(iter_expr);
3170 self.with_rib(ValueNS, NormalRibKind, |this| {
3171 this.resolve_pattern_top(pat, PatternSource::For);
3172 this.resolve_labeled_block(label, expr.id, block);
3176 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
3178 // Equivalent to `visit::walk_expr` + passing some context to children.
3179 ExprKind::Field(ref subexpression, _) => {
3180 self.resolve_expr(subexpression, Some(expr));
3182 ExprKind::MethodCall(ref segment, ref arguments, _) => {
3183 let mut arguments = arguments.iter();
3184 self.resolve_expr(arguments.next().unwrap(), Some(expr));
3185 for argument in arguments {
3186 self.resolve_expr(argument, None);
3188 self.visit_path_segment(expr.span, segment);
3191 ExprKind::Call(ref callee, ref arguments) => {
3192 self.resolve_expr(callee, Some(expr));
3193 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
3194 for (idx, argument) in arguments.iter().enumerate() {
3195 // Constant arguments need to be treated as AnonConst since
3196 // that is how they will be later lowered to HIR.
3197 if const_args.contains(&idx) {
3198 self.with_constant_rib(
3200 if argument.is_potential_trivial_const_param() {
3201 HasGenericParams::Yes
3203 HasGenericParams::No
3207 this.resolve_expr(argument, None);
3211 self.resolve_expr(argument, None);
3215 ExprKind::Type(ref type_expr, ref ty) => {
3216 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
3217 // type ascription. Here we are trying to retrieve the span of the colon token as
3218 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
3219 // with `expr::Ty`, only in this case it will match the span from
3220 // `type_ascription_path_suggestions`.
3221 self.diagnostic_metadata
3222 .current_type_ascription
3223 .push(type_expr.span.between(ty.span));
3224 visit::walk_expr(self, expr);
3225 self.diagnostic_metadata.current_type_ascription.pop();
3227 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
3228 // resolve the arguments within the proper scopes so that usages of them inside the
3229 // closure are detected as upvars rather than normal closure arg usages.
3230 ExprKind::Closure(_, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
3231 self.with_rib(ValueNS, NormalRibKind, |this| {
3232 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
3233 // Resolve arguments:
3234 this.resolve_params(&fn_decl.inputs);
3235 // No need to resolve return type --
3236 // the outer closure return type is `FnRetTy::Default`.
3238 // Now resolve the inner closure
3240 // No need to resolve arguments: the inner closure has none.
3241 // Resolve the return type:
3242 visit::walk_fn_ret_ty(this, &fn_decl.output);
3244 this.visit_expr(body);
3249 ExprKind::Async(..) | ExprKind::Closure(..) => {
3250 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
3252 ExprKind::Repeat(ref elem, ref ct) => {
3253 self.visit_expr(elem);
3254 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
3255 this.resolve_anon_const(ct, IsRepeatExpr::Yes)
3258 ExprKind::ConstBlock(ref ct) => {
3259 self.resolve_anon_const(ct, IsRepeatExpr::No);
3261 ExprKind::Index(ref elem, ref idx) => {
3262 self.resolve_expr(elem, Some(expr));
3263 self.visit_expr(idx);
3266 visit::walk_expr(self, expr);
3271 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
3273 ExprKind::Field(_, ident) => {
3274 // FIXME(#6890): Even though you can't treat a method like a
3275 // field, we need to add any trait methods we find that match
3276 // the field name so that we can do some nice error reporting
3277 // later on in typeck.
3278 let traits = self.traits_in_scope(ident, ValueNS);
3279 self.r.trait_map.insert(expr.id, traits);
3281 ExprKind::MethodCall(ref segment, ..) => {
3282 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
3283 let traits = self.traits_in_scope(segment.ident, ValueNS);
3284 self.r.trait_map.insert(expr.id, traits);
3292 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
3293 self.r.traits_in_scope(
3294 self.current_trait_ref.as_ref().map(|(module, _)| *module),
3297 Some((ident.name, ns)),
3302 struct LifetimeCountVisitor<'a, 'b> {
3303 r: &'b mut Resolver<'a>,
3306 /// Walks the whole crate in DFS order, visiting each item, counting the declared number of
3307 /// lifetime generic parameters.
3308 impl<'ast> Visitor<'ast> for LifetimeCountVisitor<'_, '_> {
3309 fn visit_item(&mut self, item: &'ast Item) {
3311 ItemKind::TyAlias(box TyAlias { ref generics, .. })
3312 | ItemKind::Fn(box Fn { ref generics, .. })
3313 | ItemKind::Enum(_, ref generics)
3314 | ItemKind::Struct(_, ref generics)
3315 | ItemKind::Union(_, ref generics)
3316 | ItemKind::Impl(box Impl { ref generics, .. })
3317 | ItemKind::Trait(box Trait { ref generics, .. })
3318 | ItemKind::TraitAlias(ref generics, _) => {
3319 let def_id = self.r.local_def_id(item.id);
3320 let count = generics
3323 .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
3325 self.r.item_generics_num_lifetimes.insert(def_id, count);
3329 | ItemKind::ForeignMod(..)
3330 | ItemKind::Static(..)
3331 | ItemKind::Const(..)
3333 | ItemKind::ExternCrate(..)
3334 | ItemKind::MacroDef(..)
3335 | ItemKind::GlobalAsm(..)
3336 | ItemKind::MacCall(..) => {}
3338 visit::walk_item(self, item)
3342 impl<'a> Resolver<'a> {
3343 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
3344 visit::walk_crate(&mut LifetimeCountVisitor { r: self }, krate);
3345 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
3346 visit::walk_crate(&mut late_resolution_visitor, krate);
3347 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
3348 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");