1 // ignore-tidy-filelength
2 //! "Late resolution" is the pass that resolves most of names in a crate beside imports and macros.
3 //! It runs when the crate is fully expanded and its module structure is fully built.
4 //! So it just walks through the crate and resolves all the expressions, types, etc.
6 //! If you wonder why there's no `early.rs`, that's because it's split into three files -
7 //! `build_reduced_graph.rs`, `macros.rs` and `imports.rs`.
11 use crate::{path_names_to_string, BindingError, Finalize, LexicalScopeBinding};
12 use crate::{Module, ModuleOrUniformRoot, NameBinding, ParentScope, PathResult};
13 use crate::{ResolutionError, Resolver, Segment, UseError};
15 use rustc_ast::ptr::P;
16 use rustc_ast::visit::{self, AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor};
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, LifetimeRes, PartialRes, PerNS};
22 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
23 use rustc_hir::{BindingAnnotation, PrimTy, TraitCandidate};
24 use rustc_middle::middle::resolve_lifetime::Set1;
25 use rustc_middle::ty::DefIdTree;
26 use rustc_middle::{bug, span_bug};
27 use rustc_session::lint;
28 use rustc_span::symbol::{kw, sym, Ident, Symbol};
29 use rustc_span::{BytePos, Span};
30 use smallvec::{smallvec, SmallVec};
32 use rustc_span::source_map::{respan, Spanned};
33 use std::assert_matches::debug_assert_matches;
34 use std::collections::{hash_map::Entry, BTreeSet};
35 use std::mem::{replace, swap, take};
39 type Res = def::Res<NodeId>;
41 type IdentMap<T> = FxHashMap<Ident, T>;
43 /// Map from the name in a pattern to its binding mode.
44 type BindingMap = IdentMap<BindingInfo>;
47 ElisionFnParameter, LifetimeElisionCandidate, MissingLifetime, MissingLifetimeKind,
50 #[derive(Copy, Clone, Debug)]
53 annotation: BindingAnnotation,
56 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
57 pub enum PatternSource {
64 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
71 pub fn descr(self) -> &'static str {
73 PatternSource::Match => "match binding",
74 PatternSource::Let => "let binding",
75 PatternSource::For => "for binding",
76 PatternSource::FnParam => "function parameter",
81 /// Denotes whether the context for the set of already bound bindings is a `Product`
82 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
83 /// See those functions for more information.
86 /// A product pattern context, e.g., `Variant(a, b)`.
88 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
92 /// Does this the item (from the item rib scope) allow generic parameters?
93 #[derive(Copy, Clone, Debug)]
94 pub(crate) enum HasGenericParams {
99 /// May this constant have generics?
100 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
101 pub(crate) enum ConstantHasGenerics {
106 impl ConstantHasGenerics {
107 fn force_yes_if(self, b: bool) -> Self {
108 if b { Self::Yes } else { self }
112 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
113 pub(crate) enum ConstantItemKind {
118 /// The rib kind restricts certain accesses,
119 /// e.g. to a `Res::Local` of an outer item.
120 #[derive(Copy, Clone, Debug)]
121 pub(crate) enum RibKind<'a> {
122 /// No restriction needs to be applied.
125 /// We passed through an impl or trait and are now in one of its
126 /// methods or associated types. Allow references to ty params that impl or trait
127 /// binds. Disallow any other upvars (including other ty params that are
131 /// We passed through a closure. Disallow labels.
132 ClosureOrAsyncRibKind,
134 /// We passed through an item scope. Disallow upvars.
135 ItemRibKind(HasGenericParams),
137 /// We're in a constant item. Can't refer to dynamic stuff.
139 /// The item may reference generic parameters in trivial constant expressions.
140 /// All other constants aren't allowed to use generic params at all.
141 ConstantItemRibKind(ConstantHasGenerics, Option<(Ident, ConstantItemKind)>),
143 /// We passed through a module.
144 ModuleRibKind(Module<'a>),
146 /// We passed through a `macro_rules!` statement
147 MacroDefinition(DefId),
149 /// All bindings in this rib are generic parameters that can't be used
150 /// from the default of a generic parameter because they're not declared
151 /// before said generic parameter. Also see the `visit_generics` override.
152 ForwardGenericParamBanRibKind,
154 /// We are inside of the type of a const parameter. Can't refer to any
158 /// We are inside a `sym` inline assembly operand. Can only refer to
164 /// Whether this rib kind contains generic parameters, as opposed to local
166 pub(crate) fn contains_params(&self) -> bool {
169 | ClosureOrAsyncRibKind
170 | ConstantItemRibKind(..)
173 | ConstParamTyRibKind
174 | InlineAsmSymRibKind => false,
175 AssocItemRibKind | ItemRibKind(_) | ForwardGenericParamBanRibKind => true,
179 /// This rib forbids referring to labels defined in upwards ribs.
180 fn is_label_barrier(self) -> bool {
182 NormalRibKind | MacroDefinition(..) => false,
185 | ClosureOrAsyncRibKind
187 | ConstantItemRibKind(..)
189 | ForwardGenericParamBanRibKind
190 | ConstParamTyRibKind
191 | InlineAsmSymRibKind => true,
196 /// A single local scope.
198 /// A rib represents a scope names can live in. Note that these appear in many places, not just
199 /// around braces. At any place where the list of accessible names (of the given namespace)
200 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
201 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
204 /// Different [rib kinds](enum@RibKind) are transparent for different names.
206 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
207 /// resolving, the name is looked up from inside out.
209 pub(crate) struct Rib<'a, R = Res> {
210 pub bindings: IdentMap<R>,
211 pub kind: RibKind<'a>,
214 impl<'a, R> Rib<'a, R> {
215 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
216 Rib { bindings: Default::default(), kind }
220 #[derive(Clone, Copy, Debug)]
221 enum LifetimeUseSet {
222 One { use_span: Span, use_ctxt: visit::LifetimeCtxt },
226 #[derive(Copy, Clone, Debug)]
227 enum LifetimeRibKind {
228 // -- Ribs introducing named lifetimes
230 /// This rib declares generic parameters.
231 /// Only for this kind the `LifetimeRib::bindings` field can be non-empty.
232 Generics { binder: NodeId, span: Span, kind: LifetimeBinderKind },
234 // -- Ribs introducing unnamed lifetimes
236 /// Create a new anonymous lifetime parameter and reference it.
238 /// If `report_in_path`, report an error when encountering lifetime elision in a path:
240 /// struct Foo<'a> { x: &'a () }
241 /// async fn foo(x: Foo) {}
244 /// Note: the error should not trigger when the elided lifetime is in a pattern or
245 /// expression-position path:
247 /// struct Foo<'a> { x: &'a () }
248 /// async fn foo(Foo { x: _ }: Foo<'_>) {}
250 AnonymousCreateParameter { binder: NodeId, report_in_path: bool },
252 /// Replace all anonymous lifetimes by provided lifetime.
255 // -- Barrier ribs that stop lifetime lookup, or continue it but produce an error later.
257 /// Give a hard error when either `&` or `'_` is written. Used to
258 /// rule out things like `where T: Foo<'_>`. Does not imply an
259 /// error on default object bounds (e.g., `Box<dyn Foo>`).
260 AnonymousReportError,
262 /// Signal we cannot find which should be the anonymous lifetime.
265 /// FIXME(const_generics): This patches over an ICE caused by non-'static lifetimes in const
266 /// generics. We are disallowing this until we can decide on how we want to handle non-'static
267 /// lifetimes in const generics. See issue #74052 for discussion.
270 /// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`.
271 /// This function will emit an error if `generic_const_exprs` is not enabled, the body
272 /// identified by `body_id` is an anonymous constant and `lifetime_ref` is non-static.
275 /// This rib acts as a barrier to forbid reference to lifetimes of a parent item.
279 #[derive(Copy, Clone, Debug)]
280 enum LifetimeBinderKind {
290 impl LifetimeBinderKind {
291 fn descr(self) -> &'static str {
292 use LifetimeBinderKind::*;
294 BareFnType => "type",
295 PolyTrait => "bound",
296 WhereBound => "bound",
298 ImplBlock => "impl block",
299 Function => "function",
300 Closure => "closure",
307 kind: LifetimeRibKind,
308 // We need to preserve insertion order for async fns.
309 bindings: FxIndexMap<Ident, (NodeId, LifetimeRes)>,
313 fn new(kind: LifetimeRibKind) -> LifetimeRib {
314 LifetimeRib { bindings: Default::default(), kind }
318 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
319 pub(crate) enum AliasPossibility {
324 #[derive(Copy, Clone, Debug)]
325 pub(crate) enum PathSource<'a> {
326 // Type paths `Path`.
328 // Trait paths in bounds or impls.
329 Trait(AliasPossibility),
330 // Expression paths `path`, with optional parent context.
331 Expr(Option<&'a Expr>),
332 // Paths in path patterns `Path`.
334 // Paths in struct expressions and patterns `Path { .. }`.
336 // Paths in tuple struct patterns `Path(..)`.
337 TupleStruct(Span, &'a [Span]),
338 // `m::A::B` in `<T as m::A>::B::C`.
339 TraitItem(Namespace),
342 impl<'a> PathSource<'a> {
343 fn namespace(self) -> Namespace {
345 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
346 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
347 PathSource::TraitItem(ns) => ns,
351 fn defer_to_typeck(self) -> bool {
354 | PathSource::Expr(..)
357 | PathSource::TupleStruct(..) => true,
358 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
362 fn descr_expected(self) -> &'static str {
364 PathSource::Type => "type",
365 PathSource::Trait(_) => "trait",
366 PathSource::Pat => "unit struct, unit variant or constant",
367 PathSource::Struct => "struct, variant or union type",
368 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
369 PathSource::TraitItem(ns) => match ns {
370 TypeNS => "associated type",
371 ValueNS => "method or associated constant",
372 MacroNS => bug!("associated macro"),
374 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
375 // "function" here means "anything callable" rather than `DefKind::Fn`,
376 // this is not precise but usually more helpful than just "value".
377 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
378 // the case of `::some_crate()`
379 ExprKind::Path(_, path)
380 if path.segments.len() == 2
381 && path.segments[0].ident.name == kw::PathRoot =>
385 ExprKind::Path(_, path) => {
386 let mut msg = "function";
387 if let Some(segment) = path.segments.iter().last() {
388 if let Some(c) = segment.ident.to_string().chars().next() {
389 if c.is_uppercase() {
390 msg = "function, tuple struct or tuple variant";
403 fn is_call(self) -> bool {
404 matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
407 pub(crate) fn is_expected(self, res: Res) -> bool {
409 PathSource::Type => matches!(
416 | DefKind::TraitAlias
421 | DefKind::ForeignTy,
424 | Res::SelfTyParam { .. }
425 | Res::SelfTyAlias { .. }
427 PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
428 PathSource::Trait(AliasPossibility::Maybe) => {
429 matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
431 PathSource::Expr(..) => matches!(
434 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
439 | DefKind::AssocConst
440 | DefKind::ConstParam,
446 res.expected_in_unit_struct_pat()
447 || matches!(res, Res::Def(DefKind::Const | DefKind::AssocConst, _))
449 PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
450 PathSource::Struct => matches!(
459 ) | Res::SelfTyParam { .. }
460 | Res::SelfTyAlias { .. }
462 PathSource::TraitItem(ns) => match res {
463 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
464 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
470 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
471 use rustc_errors::error_code;
472 match (self, has_unexpected_resolution) {
473 (PathSource::Trait(_), true) => error_code!(E0404),
474 (PathSource::Trait(_), false) => error_code!(E0405),
475 (PathSource::Type, true) => error_code!(E0573),
476 (PathSource::Type, false) => error_code!(E0412),
477 (PathSource::Struct, true) => error_code!(E0574),
478 (PathSource::Struct, false) => error_code!(E0422),
479 (PathSource::Expr(..), true) => error_code!(E0423),
480 (PathSource::Expr(..), false) => error_code!(E0425),
481 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
482 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
483 (PathSource::TraitItem(..), true) => error_code!(E0575),
484 (PathSource::TraitItem(..), false) => error_code!(E0576),
490 struct DiagnosticMetadata<'ast> {
491 /// The current trait's associated items' ident, used for diagnostic suggestions.
492 current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
494 /// The current self type if inside an impl (used for better errors).
495 current_self_type: Option<Ty>,
497 /// The current self item if inside an ADT (used for better errors).
498 current_self_item: Option<NodeId>,
500 /// The current trait (used to suggest).
501 current_item: Option<&'ast Item>,
503 /// When processing generics and encountering a type not found, suggest introducing a type
505 currently_processing_generics: bool,
507 /// The current enclosing (non-closure) function (used for better errors).
508 current_function: Option<(FnKind<'ast>, Span)>,
510 /// A list of labels as of yet unused. Labels will be removed from this map when
511 /// they are used (in a `break` or `continue` statement)
512 unused_labels: FxHashMap<NodeId, Span>,
514 /// Only used for better errors on `fn(): fn()`.
515 current_type_ascription: Vec<Span>,
517 /// Only used for better errors on `let x = { foo: bar };`.
518 /// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only
519 /// needed for cases where this parses as a correct type ascription.
520 current_block_could_be_bare_struct_literal: Option<Span>,
522 /// Only used for better errors on `let <pat>: <expr, not type>;`.
523 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
525 /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
526 in_if_condition: Option<&'ast Expr>,
528 /// Used to detect possible new binding written without `let` and to provide structured suggestion.
529 in_assignment: Option<&'ast Expr>,
531 /// If we are currently in a trait object definition. Used to point at the bounds when
532 /// encountering a struct or enum.
533 current_trait_object: Option<&'ast [ast::GenericBound]>,
535 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
536 current_where_predicate: Option<&'ast WherePredicate>,
538 current_type_path: Option<&'ast Ty>,
540 /// The current impl items (used to suggest).
541 current_impl_items: Option<&'ast [P<AssocItem>]>,
543 /// When processing impl trait
544 currently_processing_impl_trait: Option<(TraitRef, Ty)>,
546 /// Accumulate the errors due to missed lifetime elision,
547 /// and report them all at once for each function.
548 current_elision_failures: Vec<MissingLifetime>,
551 struct LateResolutionVisitor<'a, 'b, 'ast> {
552 r: &'b mut Resolver<'a>,
554 /// The module that represents the current item scope.
555 parent_scope: ParentScope<'a>,
557 /// The current set of local scopes for types and values.
558 /// FIXME #4948: Reuse ribs to avoid allocation.
559 ribs: PerNS<Vec<Rib<'a>>>,
561 /// The current set of local scopes, for labels.
562 label_ribs: Vec<Rib<'a, NodeId>>,
564 /// The current set of local scopes for lifetimes.
565 lifetime_ribs: Vec<LifetimeRib>,
567 /// We are looking for lifetimes in an elision context.
568 /// The set contains all the resolutions that we encountered so far.
569 /// They will be used to determine the correct lifetime for the fn return type.
570 /// The `LifetimeElisionCandidate` is used for diagnostics, to suggest introducing named
572 lifetime_elision_candidates: Option<Vec<(LifetimeRes, LifetimeElisionCandidate)>>,
574 /// The trait that the current context can refer to.
575 current_trait_ref: Option<(Module<'a>, TraitRef)>,
577 /// Fields used to add information to diagnostic errors.
578 diagnostic_metadata: Box<DiagnosticMetadata<'ast>>,
580 /// State used to know whether to ignore resolution errors for function bodies.
582 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
583 /// In most cases this will be `None`, in which case errors will always be reported.
584 /// If it is `true`, then it will be updated when entering a nested function or trait body.
587 /// Count the number of places a lifetime is used.
588 lifetime_uses: FxHashMap<LocalDefId, LifetimeUseSet>,
591 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
592 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
593 fn visit_attribute(&mut self, _: &'ast Attribute) {
594 // We do not want to resolve expressions that appear in attributes,
595 // as they do not correspond to actual code.
597 fn visit_item(&mut self, item: &'ast Item) {
598 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
599 // Always report errors in items we just entered.
600 let old_ignore = replace(&mut self.in_func_body, false);
601 self.with_lifetime_rib(LifetimeRibKind::Item, |this| this.resolve_item(item));
602 self.in_func_body = old_ignore;
603 self.diagnostic_metadata.current_item = prev;
605 fn visit_arm(&mut self, arm: &'ast Arm) {
606 self.resolve_arm(arm);
608 fn visit_block(&mut self, block: &'ast Block) {
609 self.resolve_block(block);
611 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
612 // We deal with repeat expressions explicitly in `resolve_expr`.
613 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
614 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
615 this.resolve_anon_const(constant, IsRepeatExpr::No);
619 fn visit_expr(&mut self, expr: &'ast Expr) {
620 self.resolve_expr(expr, None);
622 fn visit_local(&mut self, local: &'ast Local) {
623 let local_spans = match local.pat.kind {
624 // We check for this to avoid tuple struct fields.
625 PatKind::Wild => None,
628 local.ty.as_ref().map(|ty| ty.span),
629 local.kind.init().map(|init| init.span),
632 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
633 self.resolve_local(local);
634 self.diagnostic_metadata.current_let_binding = original;
636 fn visit_ty(&mut self, ty: &'ast Ty) {
637 let prev = self.diagnostic_metadata.current_trait_object;
638 let prev_ty = self.diagnostic_metadata.current_type_path;
640 TyKind::Rptr(None, _) => {
641 // Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
643 // This span will be used in case of elision failure.
644 let span = self.r.session.source_map().start_point(ty.span);
645 self.resolve_elided_lifetime(ty.id, span);
646 visit::walk_ty(self, ty);
648 TyKind::Path(ref qself, ref path) => {
649 self.diagnostic_metadata.current_type_path = Some(ty);
650 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
652 // Check whether we should interpret this as a bare trait object.
654 && let Some(partial_res) = self.r.partial_res_map.get(&ty.id)
655 && let Some(Res::Def(DefKind::Trait | DefKind::TraitAlias, _)) = partial_res.full_res()
657 // This path is actually a bare trait object. In case of a bare `Fn`-trait
658 // object with anonymous lifetimes, we need this rib to correctly place the
659 // synthetic lifetimes.
660 let span = ty.span.shrink_to_lo().to(path.span.shrink_to_lo());
661 self.with_generic_param_rib(
664 LifetimeRibKind::Generics {
666 kind: LifetimeBinderKind::PolyTrait,
669 |this| this.visit_path(&path, ty.id),
672 visit::walk_ty(self, ty)
675 TyKind::ImplicitSelf => {
676 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
678 .resolve_ident_in_lexical_scope(
681 Some(Finalize::new(ty.id, ty.span)),
684 .map_or(Res::Err, |d| d.res());
685 self.r.record_partial_res(ty.id, PartialRes::new(res));
686 visit::walk_ty(self, ty)
688 TyKind::ImplTrait(..) => {
689 let candidates = self.lifetime_elision_candidates.take();
690 visit::walk_ty(self, ty);
691 self.lifetime_elision_candidates = candidates;
693 TyKind::TraitObject(ref bounds, ..) => {
694 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
695 visit::walk_ty(self, ty)
697 TyKind::BareFn(ref bare_fn) => {
698 let span = ty.span.shrink_to_lo().to(bare_fn.decl_span.shrink_to_lo());
699 self.with_generic_param_rib(
700 &bare_fn.generic_params,
702 LifetimeRibKind::Generics {
704 kind: LifetimeBinderKind::BareFnType,
708 this.visit_generic_params(&bare_fn.generic_params, false);
709 this.with_lifetime_rib(
710 LifetimeRibKind::AnonymousCreateParameter {
712 report_in_path: false,
715 this.resolve_fn_signature(
718 // We don't need to deal with patterns in parameters, because
719 // they are not possible for foreign or bodiless functions.
724 .map(|Param { ty, .. }| (None, &**ty)),
725 &bare_fn.decl.output,
732 _ => visit::walk_ty(self, ty),
734 self.diagnostic_metadata.current_trait_object = prev;
735 self.diagnostic_metadata.current_type_path = prev_ty;
737 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef) {
738 let span = tref.span.shrink_to_lo().to(tref.trait_ref.path.span.shrink_to_lo());
739 self.with_generic_param_rib(
740 &tref.bound_generic_params,
742 LifetimeRibKind::Generics {
743 binder: tref.trait_ref.ref_id,
744 kind: LifetimeBinderKind::PolyTrait,
748 this.visit_generic_params(&tref.bound_generic_params, false);
749 this.smart_resolve_path(
750 tref.trait_ref.ref_id,
752 &tref.trait_ref.path,
753 PathSource::Trait(AliasPossibility::Maybe),
755 this.visit_trait_ref(&tref.trait_ref);
759 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
760 match foreign_item.kind {
761 ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
762 self.with_generic_param_rib(
764 ItemRibKind(HasGenericParams::Yes(generics.span)),
765 LifetimeRibKind::Generics {
766 binder: foreign_item.id,
767 kind: LifetimeBinderKind::Item,
770 |this| visit::walk_foreign_item(this, foreign_item),
773 ForeignItemKind::Fn(box Fn { ref generics, .. }) => {
774 self.with_generic_param_rib(
776 ItemRibKind(HasGenericParams::Yes(generics.span)),
777 LifetimeRibKind::Generics {
778 binder: foreign_item.id,
779 kind: LifetimeBinderKind::Function,
782 |this| visit::walk_foreign_item(this, foreign_item),
785 ForeignItemKind::Static(..) => {
786 self.with_static_rib(|this| {
787 visit::walk_foreign_item(this, foreign_item);
790 ForeignItemKind::MacCall(..) => {
791 panic!("unexpanded macro in resolve!")
795 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, fn_id: NodeId) {
796 let previous_value = self.diagnostic_metadata.current_function;
798 // Bail if the function is foreign, and thus cannot validly have
799 // a body, or if there's no body for some other reason.
800 FnKind::Fn(FnCtxt::Foreign, _, sig, _, generics, _)
801 | FnKind::Fn(_, _, sig, _, generics, None) => {
802 self.visit_fn_header(&sig.header);
803 self.visit_generics(generics);
804 self.with_lifetime_rib(
805 LifetimeRibKind::AnonymousCreateParameter {
807 report_in_path: false,
810 this.resolve_fn_signature(
813 sig.decl.inputs.iter().map(|Param { ty, .. }| (None, &**ty)),
817 this.record_lifetime_params_for_async(
819 sig.header.asyncness.opt_return_id(),
826 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
828 // Do not update `current_function` for closures: it suggests `self` parameters.
829 FnKind::Closure(..) => {}
831 debug!("(resolving function) entering function");
833 // Create a value rib for the function.
834 self.with_rib(ValueNS, ClosureOrAsyncRibKind, |this| {
835 // Create a label rib for the function.
836 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
838 FnKind::Fn(_, _, sig, _, generics, body) => {
839 this.visit_generics(generics);
841 let declaration = &sig.decl;
842 let async_node_id = sig.header.asyncness.opt_return_id();
844 this.with_lifetime_rib(
845 LifetimeRibKind::AnonymousCreateParameter {
847 report_in_path: async_node_id.is_some(),
850 this.resolve_fn_signature(
852 declaration.has_self(),
856 .map(|Param { pat, ty, .. }| (Some(&**pat), &**ty)),
862 this.record_lifetime_params_for_async(fn_id, async_node_id);
864 if let Some(body) = body {
865 // Ignore errors in function bodies if this is rustdoc
866 // Be sure not to set this until the function signature has been resolved.
867 let previous_state = replace(&mut this.in_func_body, true);
868 // Resolve the function body, potentially inside the body of an async closure
869 this.with_lifetime_rib(
870 LifetimeRibKind::Elided(LifetimeRes::Infer),
871 |this| this.visit_block(body),
874 debug!("(resolving function) leaving function");
875 this.in_func_body = previous_state;
878 FnKind::Closure(binder, declaration, body) => {
879 this.visit_closure_binder(binder);
881 this.with_lifetime_rib(
883 // We do not have any explicit generic lifetime parameter.
884 ClosureBinder::NotPresent => {
885 LifetimeRibKind::AnonymousCreateParameter {
887 report_in_path: false,
890 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
892 // Add each argument to the rib.
893 |this| this.resolve_params(&declaration.inputs),
895 this.with_lifetime_rib(
897 ClosureBinder::NotPresent => {
898 LifetimeRibKind::Elided(LifetimeRes::Infer)
900 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
902 |this| visit::walk_fn_ret_ty(this, &declaration.output),
905 // Ignore errors in function bodies if this is rustdoc
906 // Be sure not to set this until the function signature has been resolved.
907 let previous_state = replace(&mut this.in_func_body, true);
908 // Resolve the function body, potentially inside the body of an async closure
909 this.with_lifetime_rib(
910 LifetimeRibKind::Elided(LifetimeRes::Infer),
911 |this| this.visit_expr(body),
914 debug!("(resolving function) leaving function");
915 this.in_func_body = previous_state;
920 self.diagnostic_metadata.current_function = previous_value;
922 fn visit_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
923 self.resolve_lifetime(lifetime, use_ctxt)
926 fn visit_generics(&mut self, generics: &'ast Generics) {
927 self.visit_generic_params(
929 self.diagnostic_metadata.current_self_item.is_some(),
931 for p in &generics.where_clause.predicates {
932 self.visit_where_predicate(p);
936 fn visit_closure_binder(&mut self, b: &'ast ClosureBinder) {
938 ClosureBinder::NotPresent => {}
939 ClosureBinder::For { generic_params, .. } => {
940 self.visit_generic_params(
942 self.diagnostic_metadata.current_self_item.is_some(),
948 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
949 debug!("visit_generic_arg({:?})", arg);
950 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
952 GenericArg::Type(ref ty) => {
953 // We parse const arguments as path types as we cannot distinguish them during
954 // parsing. We try to resolve that ambiguity by attempting resolution the type
955 // namespace first, and if that fails we try again in the value namespace. If
956 // resolution in the value namespace succeeds, we have an generic const argument on
958 if let TyKind::Path(ref qself, ref path) = ty.kind {
959 // We cannot disambiguate multi-segment paths right now as that requires type
961 if path.segments.len() == 1 && path.segments[0].args.is_none() {
962 let mut check_ns = |ns| {
963 self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns)
966 if !check_ns(TypeNS) && check_ns(ValueNS) {
967 // This must be equivalent to `visit_anon_const`, but we cannot call it
968 // directly due to visitor lifetimes so we have to copy-paste some code.
970 // Note that we might not be inside of an repeat expression here,
971 // but considering that `IsRepeatExpr` is only relevant for
972 // non-trivial constants this is doesn't matter.
973 self.with_constant_rib(
975 ConstantHasGenerics::Yes,
978 this.smart_resolve_path(
982 PathSource::Expr(None),
985 if let Some(ref qself) = *qself {
986 this.visit_ty(&qself.ty);
988 this.visit_path(path, ty.id);
992 self.diagnostic_metadata.currently_processing_generics = prev;
1000 GenericArg::Lifetime(lt) => self.visit_lifetime(lt, visit::LifetimeCtxt::GenericArg),
1001 GenericArg::Const(ct) => self.visit_anon_const(ct),
1003 self.diagnostic_metadata.currently_processing_generics = prev;
1006 fn visit_assoc_constraint(&mut self, constraint: &'ast AssocConstraint) {
1007 self.visit_ident(constraint.ident);
1008 if let Some(ref gen_args) = constraint.gen_args {
1009 // Forbid anonymous lifetimes in GAT parameters until proper semantics are decided.
1010 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1011 this.visit_generic_args(gen_args)
1014 match constraint.kind {
1015 AssocConstraintKind::Equality { ref term } => match term {
1016 Term::Ty(ty) => self.visit_ty(ty),
1017 Term::Const(c) => self.visit_anon_const(c),
1019 AssocConstraintKind::Bound { ref bounds } => {
1020 walk_list!(self, visit_param_bound, bounds, BoundKind::Bound);
1025 fn visit_path_segment(&mut self, path_segment: &'ast PathSegment) {
1026 if let Some(ref args) = path_segment.args {
1028 GenericArgs::AngleBracketed(..) => visit::walk_generic_args(self, args),
1029 GenericArgs::Parenthesized(p_args) => {
1030 // Probe the lifetime ribs to know how to behave.
1031 for rib in self.lifetime_ribs.iter().rev() {
1033 // We are inside a `PolyTraitRef`. The lifetimes are
1034 // to be intoduced in that (maybe implicit) `for<>` binder.
1035 LifetimeRibKind::Generics {
1037 kind: LifetimeBinderKind::PolyTrait,
1040 self.with_lifetime_rib(
1041 LifetimeRibKind::AnonymousCreateParameter {
1043 report_in_path: false,
1046 this.resolve_fn_signature(
1049 p_args.inputs.iter().map(|ty| (None, &**ty)),
1056 // We have nowhere to introduce generics. Code is malformed,
1057 // so use regular lifetime resolution to avoid spurious errors.
1058 LifetimeRibKind::Item | LifetimeRibKind::Generics { .. } => {
1059 visit::walk_generic_args(self, args);
1062 LifetimeRibKind::AnonymousCreateParameter { .. }
1063 | LifetimeRibKind::AnonymousReportError
1064 | LifetimeRibKind::Elided(_)
1065 | LifetimeRibKind::ElisionFailure
1066 | LifetimeRibKind::AnonConst
1067 | LifetimeRibKind::ConstGeneric => {}
1075 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
1076 debug!("visit_where_predicate {:?}", p);
1077 let previous_value =
1078 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
1079 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1080 if let WherePredicate::BoundPredicate(WhereBoundPredicate {
1083 ref bound_generic_params,
1084 span: predicate_span,
1088 let span = predicate_span.shrink_to_lo().to(bounded_ty.span.shrink_to_lo());
1089 this.with_generic_param_rib(
1090 &bound_generic_params,
1092 LifetimeRibKind::Generics {
1093 binder: bounded_ty.id,
1094 kind: LifetimeBinderKind::WhereBound,
1098 this.visit_generic_params(&bound_generic_params, false);
1099 this.visit_ty(bounded_ty);
1100 for bound in bounds {
1101 this.visit_param_bound(bound, BoundKind::Bound)
1106 visit::walk_where_predicate(this, p);
1109 self.diagnostic_metadata.current_where_predicate = previous_value;
1112 fn visit_inline_asm(&mut self, asm: &'ast InlineAsm) {
1113 for (op, _) in &asm.operands {
1115 InlineAsmOperand::In { expr, .. }
1116 | InlineAsmOperand::Out { expr: Some(expr), .. }
1117 | InlineAsmOperand::InOut { expr, .. } => self.visit_expr(expr),
1118 InlineAsmOperand::Out { expr: None, .. } => {}
1119 InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
1120 self.visit_expr(in_expr);
1121 if let Some(out_expr) = out_expr {
1122 self.visit_expr(out_expr);
1125 InlineAsmOperand::Const { anon_const, .. } => {
1126 // Although this is `DefKind::AnonConst`, it is allowed to reference outer
1127 // generic parameters like an inline const.
1128 self.resolve_inline_const(anon_const);
1130 InlineAsmOperand::Sym { sym } => self.visit_inline_asm_sym(sym),
1135 fn visit_inline_asm_sym(&mut self, sym: &'ast InlineAsmSym) {
1136 // This is similar to the code for AnonConst.
1137 self.with_rib(ValueNS, InlineAsmSymRibKind, |this| {
1138 this.with_rib(TypeNS, InlineAsmSymRibKind, |this| {
1139 this.with_label_rib(InlineAsmSymRibKind, |this| {
1140 this.smart_resolve_path(
1144 PathSource::Expr(None),
1146 visit::walk_inline_asm_sym(this, sym);
1153 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
1154 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
1155 // During late resolution we only track the module component of the parent scope,
1156 // although it may be useful to track other components as well for diagnostics.
1157 let graph_root = resolver.graph_root;
1158 let parent_scope = ParentScope::module(graph_root, resolver);
1159 let start_rib_kind = ModuleRibKind(graph_root);
1160 LateResolutionVisitor {
1164 value_ns: vec![Rib::new(start_rib_kind)],
1165 type_ns: vec![Rib::new(start_rib_kind)],
1166 macro_ns: vec![Rib::new(start_rib_kind)],
1168 label_ribs: Vec::new(),
1169 lifetime_ribs: Vec::new(),
1170 lifetime_elision_candidates: None,
1171 current_trait_ref: None,
1172 diagnostic_metadata: Box::new(DiagnosticMetadata::default()),
1173 // errors at module scope should always be reported
1174 in_func_body: false,
1175 lifetime_uses: Default::default(),
1179 fn maybe_resolve_ident_in_lexical_scope(
1183 ) -> Option<LexicalScopeBinding<'a>> {
1184 self.r.resolve_ident_in_lexical_scope(
1194 fn resolve_ident_in_lexical_scope(
1198 finalize: Option<Finalize>,
1199 ignore_binding: Option<&'a NameBinding<'a>>,
1200 ) -> Option<LexicalScopeBinding<'a>> {
1201 self.r.resolve_ident_in_lexical_scope(
1214 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1215 finalize: Option<Finalize>,
1216 ) -> PathResult<'a> {
1217 self.r.resolve_path_with_ribs(
1229 // We maintain a list of value ribs and type ribs.
1231 // Simultaneously, we keep track of the current position in the module
1232 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
1233 // the value or type namespaces, we first look through all the ribs and
1234 // then query the module graph. When we resolve a name in the module
1235 // namespace, we can skip all the ribs (since nested modules are not
1236 // allowed within blocks in Rust) and jump straight to the current module
1239 // Named implementations are handled separately. When we find a method
1240 // call, we consult the module node to find all of the implementations in
1241 // scope. This information is lazily cached in the module node. We then
1242 // generate a fake "implementation scope" containing all the
1243 // implementations thus found, for compatibility with old resolve pass.
1245 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
1250 work: impl FnOnce(&mut Self) -> T,
1252 self.ribs[ns].push(Rib::new(kind));
1253 let ret = work(self);
1254 self.ribs[ns].pop();
1258 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
1259 if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
1260 // Move down in the graph.
1261 let orig_module = replace(&mut self.parent_scope.module, module);
1262 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
1263 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
1265 this.parent_scope.module = orig_module;
1274 fn visit_generic_params(&mut self, params: &'ast [GenericParam], add_self_upper: bool) {
1275 // For type parameter defaults, we have to ban access
1276 // to following type parameters, as the InternalSubsts can only
1277 // provide previous type parameters as they're built. We
1278 // put all the parameters on the ban list and then remove
1279 // them one by one as they are processed and become available.
1280 let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1281 let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1282 for param in params.iter() {
1284 GenericParamKind::Type { .. } => {
1287 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1289 GenericParamKind::Const { .. } => {
1290 forward_const_ban_rib
1292 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1294 GenericParamKind::Lifetime => {}
1298 // rust-lang/rust#61631: The type `Self` is essentially
1299 // another type parameter. For ADTs, we consider it
1300 // well-defined only after all of the ADT type parameters have
1301 // been provided. Therefore, we do not allow use of `Self`
1302 // anywhere in ADT type parameter defaults.
1304 // (We however cannot ban `Self` for defaults on *all* generic
1305 // lists; e.g. trait generics can usefully refer to `Self`,
1306 // such as in the case of `trait Add<Rhs = Self>`.)
1308 // (`Some` if + only if we are in ADT's generics.)
1309 forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
1312 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1313 for param in params {
1315 GenericParamKind::Lifetime => {
1316 for bound in ¶m.bounds {
1317 this.visit_param_bound(bound, BoundKind::Bound);
1320 GenericParamKind::Type { ref default } => {
1321 for bound in ¶m.bounds {
1322 this.visit_param_bound(bound, BoundKind::Bound);
1325 if let Some(ref ty) = default {
1326 this.ribs[TypeNS].push(forward_ty_ban_rib);
1327 this.ribs[ValueNS].push(forward_const_ban_rib);
1329 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1330 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1333 // Allow all following defaults to refer to this type parameter.
1336 .remove(&Ident::with_dummy_span(param.ident.name));
1338 GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
1339 // Const parameters can't have param bounds.
1340 assert!(param.bounds.is_empty());
1342 this.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
1343 this.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
1344 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1347 this.ribs[TypeNS].pop().unwrap();
1348 this.ribs[ValueNS].pop().unwrap();
1350 if let Some(ref expr) = default {
1351 this.ribs[TypeNS].push(forward_ty_ban_rib);
1352 this.ribs[ValueNS].push(forward_const_ban_rib);
1353 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1354 this.resolve_anon_const(expr, IsRepeatExpr::No)
1356 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1357 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1360 // Allow all following defaults to refer to this const parameter.
1361 forward_const_ban_rib
1363 .remove(&Ident::with_dummy_span(param.ident.name));
1370 #[instrument(level = "debug", skip(self, work))]
1371 fn with_lifetime_rib<T>(
1373 kind: LifetimeRibKind,
1374 work: impl FnOnce(&mut Self) -> T,
1376 self.lifetime_ribs.push(LifetimeRib::new(kind));
1377 let outer_elision_candidates = self.lifetime_elision_candidates.take();
1378 let ret = work(self);
1379 self.lifetime_elision_candidates = outer_elision_candidates;
1380 self.lifetime_ribs.pop();
1384 #[instrument(level = "debug", skip(self))]
1385 fn resolve_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
1386 let ident = lifetime.ident;
1388 if ident.name == kw::StaticLifetime {
1389 self.record_lifetime_res(
1391 LifetimeRes::Static,
1392 LifetimeElisionCandidate::Named,
1397 if ident.name == kw::UnderscoreLifetime {
1398 return self.resolve_anonymous_lifetime(lifetime, false);
1401 let mut lifetime_rib_iter = self.lifetime_ribs.iter().rev();
1402 while let Some(rib) = lifetime_rib_iter.next() {
1403 let normalized_ident = ident.normalize_to_macros_2_0();
1404 if let Some(&(_, res)) = rib.bindings.get(&normalized_ident) {
1405 self.record_lifetime_res(lifetime.id, res, LifetimeElisionCandidate::Named);
1407 if let LifetimeRes::Param { param, .. } = res {
1408 match self.lifetime_uses.entry(param) {
1409 Entry::Vacant(v) => {
1410 debug!("First use of {:?} at {:?}", res, ident.span);
1415 .find_map(|rib| match rib.kind {
1416 // Do not suggest eliding a lifetime where an anonymous
1417 // lifetime would be illegal.
1418 LifetimeRibKind::Item
1419 | LifetimeRibKind::AnonymousReportError
1420 | LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many),
1421 // An anonymous lifetime is legal here, go ahead.
1422 LifetimeRibKind::AnonymousCreateParameter { .. } => {
1423 Some(LifetimeUseSet::One { use_span: ident.span, use_ctxt })
1425 // Only report if eliding the lifetime would have the same
1427 LifetimeRibKind::Elided(r) => Some(if res == r {
1428 LifetimeUseSet::One { use_span: ident.span, use_ctxt }
1430 LifetimeUseSet::Many
1432 LifetimeRibKind::Generics { .. } => None,
1433 LifetimeRibKind::ConstGeneric | LifetimeRibKind::AnonConst => {
1434 span_bug!(ident.span, "unexpected rib kind: {:?}", rib.kind)
1437 .unwrap_or(LifetimeUseSet::Many);
1438 debug!(?use_ctxt, ?use_set);
1441 Entry::Occupied(mut o) => {
1442 debug!("Many uses of {:?} at {:?}", res, ident.span);
1443 *o.get_mut() = LifetimeUseSet::Many;
1451 LifetimeRibKind::Item => break,
1452 LifetimeRibKind::ConstGeneric => {
1453 self.emit_non_static_lt_in_const_generic_error(lifetime);
1454 self.record_lifetime_res(
1457 LifetimeElisionCandidate::Ignore,
1461 LifetimeRibKind::AnonConst => {
1462 self.maybe_emit_forbidden_non_static_lifetime_error(lifetime);
1463 self.record_lifetime_res(
1466 LifetimeElisionCandidate::Ignore,
1470 LifetimeRibKind::AnonymousCreateParameter { .. }
1471 | LifetimeRibKind::Elided(_)
1472 | LifetimeRibKind::Generics { .. }
1473 | LifetimeRibKind::ElisionFailure
1474 | LifetimeRibKind::AnonymousReportError => {}
1478 let mut outer_res = None;
1479 for rib in lifetime_rib_iter {
1480 let normalized_ident = ident.normalize_to_macros_2_0();
1481 if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) {
1482 outer_res = Some(outer);
1487 self.emit_undeclared_lifetime_error(lifetime, outer_res);
1488 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, LifetimeElisionCandidate::Named);
1491 #[instrument(level = "debug", skip(self))]
1492 fn resolve_anonymous_lifetime(&mut self, lifetime: &Lifetime, elided: bool) {
1493 debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
1495 let missing_lifetime = MissingLifetime {
1497 span: lifetime.ident.span,
1499 MissingLifetimeKind::Ampersand
1501 MissingLifetimeKind::Underscore
1505 let elision_candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1506 for rib in self.lifetime_ribs.iter().rev() {
1509 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1510 let res = self.create_fresh_lifetime(lifetime.id, lifetime.ident, binder);
1511 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1514 LifetimeRibKind::AnonymousReportError => {
1515 let (msg, note) = if elided {
1517 "`&` without an explicit lifetime name cannot be used here",
1518 "explicit lifetime name needed here",
1521 ("`'_` cannot be used here", "`'_` is a reserved lifetime name")
1523 rustc_errors::struct_span_err!(
1525 lifetime.ident.span,
1530 .span_label(lifetime.ident.span, note)
1533 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1536 LifetimeRibKind::Elided(res) => {
1537 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1540 LifetimeRibKind::ElisionFailure => {
1541 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1542 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1545 LifetimeRibKind::Item => break,
1546 LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstGeneric => {}
1547 LifetimeRibKind::AnonConst => {
1548 // There is always an `Elided(LifetimeRes::Static)` inside an `AnonConst`.
1549 span_bug!(lifetime.ident.span, "unexpected rib kind: {:?}", rib.kind)
1553 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1554 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1557 #[instrument(level = "debug", skip(self))]
1558 fn resolve_elided_lifetime(&mut self, anchor_id: NodeId, span: Span) {
1559 let id = self.r.next_node_id();
1560 let lt = Lifetime { id, ident: Ident::new(kw::UnderscoreLifetime, span) };
1562 self.record_lifetime_res(
1564 LifetimeRes::ElidedAnchor { start: id, end: NodeId::from_u32(id.as_u32() + 1) },
1565 LifetimeElisionCandidate::Ignore,
1567 self.resolve_anonymous_lifetime(<, true);
1570 #[instrument(level = "debug", skip(self))]
1571 fn create_fresh_lifetime(&mut self, id: NodeId, ident: Ident, binder: NodeId) -> LifetimeRes {
1572 debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
1573 debug!(?ident.span);
1575 // Leave the responsibility to create the `LocalDefId` to lowering.
1576 let param = self.r.next_node_id();
1577 let res = LifetimeRes::Fresh { param, binder };
1579 // Record the created lifetime parameter so lowering can pick it up and add it to HIR.
1581 .extra_lifetime_params_map
1583 .or_insert_with(Vec::new)
1584 .push((ident, param, res));
1588 #[instrument(level = "debug", skip(self))]
1589 fn resolve_elided_lifetimes_in_path(
1592 partial_res: PartialRes,
1594 source: PathSource<'_>,
1597 let proj_start = path.len() - partial_res.unresolved_segments();
1598 for (i, segment) in path.iter().enumerate() {
1599 if segment.has_lifetime_args {
1602 let Some(segment_id) = segment.id else {
1606 // Figure out if this is a type/trait segment,
1607 // which may need lifetime elision performed.
1608 let type_def_id = match partial_res.base_res() {
1609 Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => self.r.parent(def_id),
1610 Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => self.r.parent(def_id),
1611 Res::Def(DefKind::Struct, def_id)
1612 | Res::Def(DefKind::Union, def_id)
1613 | Res::Def(DefKind::Enum, def_id)
1614 | Res::Def(DefKind::TyAlias, def_id)
1615 | Res::Def(DefKind::Trait, def_id)
1616 if i + 1 == proj_start =>
1623 let expected_lifetimes = self.r.item_generics_num_lifetimes(type_def_id);
1624 if expected_lifetimes == 0 {
1628 let node_ids = self.r.next_node_ids(expected_lifetimes);
1629 self.record_lifetime_res(
1631 LifetimeRes::ElidedAnchor { start: node_ids.start, end: node_ids.end },
1632 LifetimeElisionCandidate::Ignore,
1635 let inferred = match source {
1636 PathSource::Trait(..) | PathSource::TraitItem(..) | PathSource::Type => false,
1637 PathSource::Expr(..)
1639 | PathSource::Struct
1640 | PathSource::TupleStruct(..) => true,
1643 // Do not create a parameter for patterns and expressions: type checking can infer
1644 // the appropriate lifetime for us.
1645 for id in node_ids {
1646 self.record_lifetime_res(
1649 LifetimeElisionCandidate::Named,
1655 let elided_lifetime_span = if segment.has_generic_args {
1656 // If there are brackets, but not generic arguments, then use the opening bracket
1657 segment.args_span.with_hi(segment.args_span.lo() + BytePos(1))
1659 // If there are no brackets, use the identifier span.
1660 // HACK: we use find_ancestor_inside to properly suggest elided spans in paths
1661 // originating from macros, since the segment's span might be from a macro arg.
1662 segment.ident.span.find_ancestor_inside(path_span).unwrap_or(path_span)
1664 let ident = Ident::new(kw::UnderscoreLifetime, elided_lifetime_span);
1666 let missing_lifetime = MissingLifetime {
1668 span: elided_lifetime_span,
1669 kind: if segment.has_generic_args {
1670 MissingLifetimeKind::Comma
1672 MissingLifetimeKind::Brackets
1674 count: expected_lifetimes,
1676 let mut should_lint = true;
1677 for rib in self.lifetime_ribs.iter().rev() {
1679 // In create-parameter mode we error here because we don't want to support
1680 // deprecated impl elision in new features like impl elision and `async fn`,
1681 // both of which work using the `CreateParameter` mode:
1683 // impl Foo for std::cell::Ref<u32> // note lack of '_
1684 // async fn foo(_: std::cell::Ref<u32>) { ... }
1685 LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. } => {
1686 let sess = self.r.session;
1687 let mut err = rustc_errors::struct_span_err!(
1691 "implicit elided lifetime not allowed here"
1693 rustc_errors::add_elided_lifetime_in_path_suggestion(
1698 !segment.has_generic_args,
1699 elided_lifetime_span,
1701 err.note("assuming a `'static` lifetime...");
1703 should_lint = false;
1705 for id in node_ids {
1706 self.record_lifetime_res(
1709 LifetimeElisionCandidate::Named,
1714 // Do not create a parameter for patterns and expressions.
1715 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1716 // Group all suggestions into the first record.
1717 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1718 for id in node_ids {
1719 let res = self.create_fresh_lifetime(id, ident, binder);
1720 self.record_lifetime_res(
1723 replace(&mut candidate, LifetimeElisionCandidate::Named),
1728 LifetimeRibKind::Elided(res) => {
1729 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1730 for id in node_ids {
1731 self.record_lifetime_res(
1734 replace(&mut candidate, LifetimeElisionCandidate::Ignore),
1739 LifetimeRibKind::ElisionFailure => {
1740 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1741 for id in node_ids {
1742 self.record_lifetime_res(
1745 LifetimeElisionCandidate::Ignore,
1750 // `LifetimeRes::Error`, which would usually be used in the case of
1751 // `ReportError`, is unsuitable here, as we don't emit an error yet. Instead,
1752 // we simply resolve to an implicit lifetime, which will be checked later, at
1753 // which point a suitable error will be emitted.
1754 LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
1755 for id in node_ids {
1756 self.record_lifetime_res(
1759 LifetimeElisionCandidate::Ignore,
1762 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1765 LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstGeneric => {}
1766 LifetimeRibKind::AnonConst => {
1767 // There is always an `Elided(LifetimeRes::Static)` inside an `AnonConst`.
1768 span_bug!(elided_lifetime_span, "unexpected rib kind: {:?}", rib.kind)
1774 self.r.lint_buffer.buffer_lint_with_diagnostic(
1775 lint::builtin::ELIDED_LIFETIMES_IN_PATHS,
1777 elided_lifetime_span,
1778 "hidden lifetime parameters in types are deprecated",
1779 lint::BuiltinLintDiagnostics::ElidedLifetimesInPaths(
1782 !segment.has_generic_args,
1783 elided_lifetime_span,
1790 #[instrument(level = "debug", skip(self))]
1791 fn record_lifetime_res(
1795 candidate: LifetimeElisionCandidate,
1797 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1799 "lifetime {:?} resolved multiple times ({:?} before, {:?} now)",
1804 LifetimeRes::Param { .. } | LifetimeRes::Fresh { .. } | LifetimeRes::Static => {
1805 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
1806 candidates.push((res, candidate));
1809 LifetimeRes::Infer | LifetimeRes::Error | LifetimeRes::ElidedAnchor { .. } => {}
1813 #[instrument(level = "debug", skip(self))]
1814 fn record_lifetime_param(&mut self, id: NodeId, res: LifetimeRes) {
1815 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1817 "lifetime parameter {:?} resolved multiple times ({:?} before, {:?} now)",
1823 /// Perform resolution of a function signature, accounting for lifetime elision.
1824 #[instrument(level = "debug", skip(self, inputs))]
1825 fn resolve_fn_signature(
1829 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)> + Clone,
1830 output_ty: &'ast FnRetTy,
1832 // Add each argument to the rib.
1833 let elision_lifetime = self.resolve_fn_params(has_self, inputs);
1834 debug!(?elision_lifetime);
1836 let outer_failures = take(&mut self.diagnostic_metadata.current_elision_failures);
1837 let output_rib = if let Ok(res) = elision_lifetime.as_ref() {
1838 LifetimeRibKind::Elided(*res)
1840 LifetimeRibKind::ElisionFailure
1842 self.with_lifetime_rib(output_rib, |this| visit::walk_fn_ret_ty(this, &output_ty));
1843 let elision_failures =
1844 replace(&mut self.diagnostic_metadata.current_elision_failures, outer_failures);
1845 if !elision_failures.is_empty() {
1846 let Err(failure_info) = elision_lifetime else { bug!() };
1847 self.report_missing_lifetime_specifiers(elision_failures, Some(failure_info));
1851 /// Resolve inside function parameters and parameter types.
1852 /// Returns the lifetime for elision in fn return type,
1853 /// or diagnostic information in case of elision failure.
1854 fn resolve_fn_params(
1857 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)>,
1858 ) -> Result<LifetimeRes, (Vec<MissingLifetime>, Vec<ElisionFnParameter>)> {
1860 /// We have not found any candidate.
1862 /// We have a candidate bound to `self`.
1864 /// We have a candidate bound to a parameter.
1866 /// We failed elision.
1870 // Save elision state to reinstate it later.
1871 let outer_candidates = self.lifetime_elision_candidates.take();
1873 // Result of elision.
1874 let mut elision_lifetime = Elision::None;
1875 // Information for diagnostics.
1876 let mut parameter_info = Vec::new();
1877 let mut all_candidates = Vec::new();
1879 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1880 for (index, (pat, ty)) in inputs.enumerate() {
1882 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
1883 if let Some(pat) = pat {
1884 this.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1888 // Record elision candidates only for this parameter.
1889 debug_assert_matches!(self.lifetime_elision_candidates, None);
1890 self.lifetime_elision_candidates = Some(Default::default());
1892 let local_candidates = self.lifetime_elision_candidates.take();
1894 if let Some(candidates) = local_candidates {
1895 let distinct: FxHashSet<_> = candidates.iter().map(|(res, _)| *res).collect();
1896 let lifetime_count = distinct.len();
1897 if lifetime_count != 0 {
1898 parameter_info.push(ElisionFnParameter {
1900 ident: if let Some(pat) = pat && let PatKind::Ident(_, ident, _) = pat.kind {
1908 all_candidates.extend(candidates.into_iter().filter_map(|(_, candidate)| {
1910 LifetimeElisionCandidate::Ignore | LifetimeElisionCandidate::Named => {
1913 LifetimeElisionCandidate::Missing(missing) => Some(missing),
1917 let mut distinct_iter = distinct.into_iter();
1918 if let Some(res) = distinct_iter.next() {
1919 match elision_lifetime {
1920 // We are the first parameter to bind lifetimes.
1922 if distinct_iter.next().is_none() {
1923 // We have a single lifetime => success.
1924 elision_lifetime = Elision::Param(res)
1926 // We have have multiple lifetimes => error.
1927 elision_lifetime = Elision::Err;
1930 // We have 2 parameters that bind lifetimes => error.
1931 Elision::Param(_) => elision_lifetime = Elision::Err,
1932 // `self` elision takes precedence over everything else.
1933 Elision::Self_(_) | Elision::Err => {}
1938 // Handle `self` specially.
1939 if index == 0 && has_self {
1940 let self_lifetime = self.find_lifetime_for_self(ty);
1941 if let Set1::One(lifetime) = self_lifetime {
1942 // We found `self` elision.
1943 elision_lifetime = Elision::Self_(lifetime);
1945 // We do not have `self` elision: disregard the `Elision::Param` that we may
1947 elision_lifetime = Elision::None;
1950 debug!("(resolving function / closure) recorded parameter");
1953 // Reinstate elision state.
1954 debug_assert_matches!(self.lifetime_elision_candidates, None);
1955 self.lifetime_elision_candidates = outer_candidates;
1957 if let Elision::Param(res) | Elision::Self_(res) = elision_lifetime {
1961 // We do not have a candidate.
1962 Err((all_candidates, parameter_info))
1965 /// List all the lifetimes that appear in the provided type.
1966 fn find_lifetime_for_self(&self, ty: &'ast Ty) -> Set1<LifetimeRes> {
1967 struct SelfVisitor<'r, 'a> {
1968 r: &'r Resolver<'a>,
1969 impl_self: Option<Res>,
1970 lifetime: Set1<LifetimeRes>,
1973 impl SelfVisitor<'_, '_> {
1974 // Look for `self: &'a Self` - also desugared from `&'a self`,
1975 // and if that matches, use it for elision and return early.
1976 fn is_self_ty(&self, ty: &Ty) -> bool {
1978 TyKind::ImplicitSelf => true,
1979 TyKind::Path(None, _) => {
1980 let path_res = self.r.partial_res_map[&ty.id].full_res();
1981 if let Some(Res::SelfTyParam { .. } | Res::SelfTyAlias { .. }) = path_res {
1984 self.impl_self.is_some() && path_res == self.impl_self
1991 impl<'a> Visitor<'a> for SelfVisitor<'_, '_> {
1992 fn visit_ty(&mut self, ty: &'a Ty) {
1993 trace!("SelfVisitor considering ty={:?}", ty);
1994 if let TyKind::Rptr(lt, ref mt) = ty.kind && self.is_self_ty(&mt.ty) {
1995 let lt_id = if let Some(lt) = lt {
1998 let res = self.r.lifetimes_res_map[&ty.id];
1999 let LifetimeRes::ElidedAnchor { start, .. } = res else { bug!() };
2002 let lt_res = self.r.lifetimes_res_map[<_id];
2003 trace!("SelfVisitor inserting res={:?}", lt_res);
2004 self.lifetime.insert(lt_res);
2006 visit::walk_ty(self, ty)
2010 let impl_self = self
2011 .diagnostic_metadata
2015 if let TyKind::Path(None, _) = ty.kind {
2016 self.r.partial_res_map.get(&ty.id)
2021 .and_then(|res| res.full_res())
2023 // Permit the types that unambiguously always
2024 // result in the same type constructor being used
2025 // (it can't differ between `Self` and `self`).
2028 Res::Def(DefKind::Struct | DefKind::Union | DefKind::Enum, _,) | Res::PrimTy(_)
2031 let mut visitor = SelfVisitor { r: self.r, impl_self, lifetime: Set1::Empty };
2032 visitor.visit_ty(ty);
2033 trace!("SelfVisitor found={:?}", visitor.lifetime);
2037 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
2038 /// label and reports an error if the label is not found or is unreachable.
2039 fn resolve_label(&mut self, mut label: Ident) -> Result<(NodeId, Span), ResolutionError<'a>> {
2040 let mut suggestion = None;
2042 for i in (0..self.label_ribs.len()).rev() {
2043 let rib = &self.label_ribs[i];
2045 if let MacroDefinition(def) = rib.kind {
2046 // If an invocation of this macro created `ident`, give up on `ident`
2047 // and switch to `ident`'s source from the macro definition.
2048 if def == self.r.macro_def(label.span.ctxt()) {
2049 label.span.remove_mark();
2053 let ident = label.normalize_to_macro_rules();
2054 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
2055 let definition_span = ident.span;
2056 return if self.is_label_valid_from_rib(i) {
2057 Ok((*id, definition_span))
2059 Err(ResolutionError::UnreachableLabel {
2067 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
2068 // the first such label that is encountered.
2069 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
2072 Err(ResolutionError::UndeclaredLabel { name: label.name, suggestion })
2075 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
2076 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
2077 let ribs = &self.label_ribs[rib_index + 1..];
2080 if rib.kind.is_label_barrier() {
2088 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
2089 debug!("resolve_adt");
2090 self.with_current_self_item(item, |this| {
2091 this.with_generic_param_rib(
2093 ItemRibKind(HasGenericParams::Yes(generics.span)),
2094 LifetimeRibKind::Generics {
2096 kind: LifetimeBinderKind::Item,
2097 span: generics.span,
2100 let item_def_id = this.r.local_def_id(item.id).to_def_id();
2103 alias_to: item_def_id,
2104 forbid_generic: false,
2105 is_trait_impl: false,
2108 visit::walk_item(this, item);
2116 fn future_proof_import(&mut self, use_tree: &UseTree) {
2117 let segments = &use_tree.prefix.segments;
2118 if !segments.is_empty() {
2119 let ident = segments[0].ident;
2120 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
2124 let nss = match use_tree.kind {
2125 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
2128 let report_error = |this: &Self, ns| {
2129 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
2130 if this.should_report_errs() {
2133 .span_err(ident.span, &format!("imports cannot refer to {}", what));
2138 match self.maybe_resolve_ident_in_lexical_scope(ident, ns) {
2139 Some(LexicalScopeBinding::Res(..)) => {
2140 report_error(self, ns);
2142 Some(LexicalScopeBinding::Item(binding)) => {
2143 if let Some(LexicalScopeBinding::Res(..)) =
2144 self.resolve_ident_in_lexical_scope(ident, ns, None, Some(binding))
2146 report_error(self, ns);
2152 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
2153 for (use_tree, _) in use_trees {
2154 self.future_proof_import(use_tree);
2159 fn resolve_item(&mut self, item: &'ast Item) {
2160 let name = item.ident.name;
2161 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
2164 ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
2165 self.with_generic_param_rib(
2167 ItemRibKind(HasGenericParams::Yes(generics.span)),
2168 LifetimeRibKind::Generics {
2170 kind: LifetimeBinderKind::Item,
2171 span: generics.span,
2173 |this| visit::walk_item(this, item),
2177 ItemKind::Fn(box Fn { ref generics, .. }) => {
2178 self.with_generic_param_rib(
2180 ItemRibKind(HasGenericParams::Yes(generics.span)),
2181 LifetimeRibKind::Generics {
2183 kind: LifetimeBinderKind::Function,
2184 span: generics.span,
2186 |this| visit::walk_item(this, item),
2190 ItemKind::Enum(_, ref generics)
2191 | ItemKind::Struct(_, ref generics)
2192 | ItemKind::Union(_, ref generics) => {
2193 self.resolve_adt(item, generics);
2196 ItemKind::Impl(box Impl {
2200 items: ref impl_items,
2203 self.diagnostic_metadata.current_impl_items = Some(impl_items);
2204 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
2205 self.diagnostic_metadata.current_impl_items = None;
2208 ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
2209 // Create a new rib for the trait-wide type parameters.
2210 self.with_generic_param_rib(
2212 ItemRibKind(HasGenericParams::Yes(generics.span)),
2213 LifetimeRibKind::Generics {
2215 kind: LifetimeBinderKind::Item,
2216 span: generics.span,
2219 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2220 this.with_self_rib(Res::SelfTyParam { trait_: local_def_id }, |this| {
2221 this.visit_generics(generics);
2222 walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);
2223 this.resolve_trait_items(items);
2229 ItemKind::TraitAlias(ref generics, ref bounds) => {
2230 // Create a new rib for the trait-wide type parameters.
2231 self.with_generic_param_rib(
2233 ItemRibKind(HasGenericParams::Yes(generics.span)),
2234 LifetimeRibKind::Generics {
2236 kind: LifetimeBinderKind::Item,
2237 span: generics.span,
2240 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2241 this.with_self_rib(Res::SelfTyParam { trait_: local_def_id }, |this| {
2242 this.visit_generics(generics);
2243 walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
2249 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
2250 self.with_scope(item.id, |this| {
2251 visit::walk_item(this, item);
2255 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
2256 self.with_static_rib(|this| {
2257 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
2260 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2261 if let Some(expr) = expr {
2262 let constant_item_kind = match item.kind {
2263 ItemKind::Const(..) => ConstantItemKind::Const,
2264 ItemKind::Static(..) => ConstantItemKind::Static,
2265 _ => unreachable!(),
2267 // We already forbid generic params because of the above item rib,
2268 // so it doesn't matter whether this is a trivial constant.
2269 this.with_constant_rib(
2271 ConstantHasGenerics::Yes,
2272 Some((item.ident, constant_item_kind)),
2273 |this| this.visit_expr(expr),
2280 ItemKind::Use(ref use_tree) => {
2281 self.future_proof_import(use_tree);
2284 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => {
2285 // do nothing, these are just around to be encoded
2288 ItemKind::GlobalAsm(_) => {
2289 visit::walk_item(self, item);
2292 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
2296 fn with_generic_param_rib<'c, F>(
2298 params: &'c [GenericParam],
2300 lifetime_kind: LifetimeRibKind,
2303 F: FnOnce(&mut Self),
2305 debug!("with_generic_param_rib");
2306 let LifetimeRibKind::Generics { binder, span: generics_span, kind: generics_kind, .. }
2307 = lifetime_kind else { panic!() };
2309 let mut function_type_rib = Rib::new(kind);
2310 let mut function_value_rib = Rib::new(kind);
2311 let mut function_lifetime_rib = LifetimeRib::new(lifetime_kind);
2312 let mut seen_bindings = FxHashMap::default();
2313 // Store all seen lifetimes names from outer scopes.
2314 let mut seen_lifetimes = FxHashSet::default();
2316 // We also can't shadow bindings from the parent item
2317 if let AssocItemRibKind = kind {
2318 let mut add_bindings_for_ns = |ns| {
2319 let parent_rib = self.ribs[ns]
2321 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
2322 .expect("associated item outside of an item");
2324 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
2326 add_bindings_for_ns(ValueNS);
2327 add_bindings_for_ns(TypeNS);
2330 // Forbid shadowing lifetime bindings
2331 for rib in self.lifetime_ribs.iter().rev() {
2332 seen_lifetimes.extend(rib.bindings.iter().map(|(ident, _)| *ident));
2333 if let LifetimeRibKind::Item = rib.kind {
2338 for param in params {
2339 let ident = param.ident.normalize_to_macros_2_0();
2340 debug!("with_generic_param_rib: {}", param.id);
2342 if let GenericParamKind::Lifetime = param.kind
2343 && let Some(&original) = seen_lifetimes.get(&ident)
2345 diagnostics::signal_lifetime_shadowing(self.r.session, original, param.ident);
2346 // Record lifetime res, so lowering knows there is something fishy.
2347 self.record_lifetime_param(param.id, LifetimeRes::Error);
2351 match seen_bindings.entry(ident) {
2352 Entry::Occupied(entry) => {
2353 let span = *entry.get();
2354 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
2355 self.report_error(param.ident.span, err);
2356 if let GenericParamKind::Lifetime = param.kind {
2357 // Record lifetime res, so lowering knows there is something fishy.
2358 self.record_lifetime_param(param.id, LifetimeRes::Error);
2362 Entry::Vacant(entry) => {
2363 entry.insert(param.ident.span);
2367 if param.ident.name == kw::UnderscoreLifetime {
2368 rustc_errors::struct_span_err!(
2372 "`'_` cannot be used here"
2374 .span_label(param.ident.span, "`'_` is a reserved lifetime name")
2376 // Record lifetime res, so lowering knows there is something fishy.
2377 self.record_lifetime_param(param.id, LifetimeRes::Error);
2381 if param.ident.name == kw::StaticLifetime {
2382 rustc_errors::struct_span_err!(
2386 "invalid lifetime parameter name: `{}`",
2389 .span_label(param.ident.span, "'static is a reserved lifetime name")
2391 // Record lifetime res, so lowering knows there is something fishy.
2392 self.record_lifetime_param(param.id, LifetimeRes::Error);
2396 let def_id = self.r.local_def_id(param.id);
2398 // Plain insert (no renaming).
2399 let (rib, def_kind) = match param.kind {
2400 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
2401 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
2402 GenericParamKind::Lifetime => {
2403 let res = LifetimeRes::Param { param: def_id, binder };
2404 self.record_lifetime_param(param.id, res);
2405 function_lifetime_rib.bindings.insert(ident, (param.id, res));
2410 let res = match kind {
2411 ItemRibKind(..) | AssocItemRibKind => Res::Def(def_kind, def_id.to_def_id()),
2412 NormalRibKind => Res::Err,
2413 _ => span_bug!(param.ident.span, "Unexpected rib kind {:?}", kind),
2415 self.r.record_partial_res(param.id, PartialRes::new(res));
2416 rib.bindings.insert(ident, res);
2419 self.lifetime_ribs.push(function_lifetime_rib);
2420 self.ribs[ValueNS].push(function_value_rib);
2421 self.ribs[TypeNS].push(function_type_rib);
2425 self.ribs[TypeNS].pop();
2426 self.ribs[ValueNS].pop();
2427 let function_lifetime_rib = self.lifetime_ribs.pop().unwrap();
2429 // Do not account for the parameters we just bound for function lifetime elision.
2430 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
2431 for (_, res) in function_lifetime_rib.bindings.values() {
2432 candidates.retain(|(r, _)| r != res);
2436 if let LifetimeBinderKind::BareFnType
2437 | LifetimeBinderKind::WhereBound
2438 | LifetimeBinderKind::Function
2439 | LifetimeBinderKind::ImplBlock = generics_kind
2441 self.maybe_report_lifetime_uses(generics_span, params)
2445 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
2446 self.label_ribs.push(Rib::new(kind));
2448 self.label_ribs.pop();
2451 fn with_static_rib(&mut self, f: impl FnOnce(&mut Self)) {
2452 let kind = ItemRibKind(HasGenericParams::No);
2453 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
2456 // HACK(min_const_generics,const_evaluatable_unchecked): We
2457 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
2458 // with a future compat lint for now. We do this by adding an
2459 // additional special case for repeat expressions.
2461 // Note that we intentionally still forbid `[0; N + 1]` during
2462 // name resolution so that we don't extend the future
2463 // compat lint to new cases.
2464 #[instrument(level = "debug", skip(self, f))]
2465 fn with_constant_rib(
2467 is_repeat: IsRepeatExpr,
2468 may_use_generics: ConstantHasGenerics,
2469 item: Option<(Ident, ConstantItemKind)>,
2470 f: impl FnOnce(&mut Self),
2472 self.with_rib(ValueNS, ConstantItemRibKind(may_use_generics, item), |this| {
2475 ConstantItemRibKind(
2476 may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes),
2480 this.with_label_rib(ConstantItemRibKind(may_use_generics, item), f);
2486 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
2487 // Handle nested impls (inside fn bodies)
2488 let previous_value =
2489 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
2490 let result = f(self);
2491 self.diagnostic_metadata.current_self_type = previous_value;
2495 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
2496 let previous_value =
2497 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
2498 let result = f(self);
2499 self.diagnostic_metadata.current_self_item = previous_value;
2503 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
2504 fn resolve_trait_items(&mut self, trait_items: &'ast [P<AssocItem>]) {
2505 let trait_assoc_items =
2506 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
2508 let walk_assoc_item =
2509 |this: &mut Self, generics: &Generics, kind, item: &'ast AssocItem| {
2510 this.with_generic_param_rib(
2513 LifetimeRibKind::Generics { binder: item.id, span: generics.span, kind },
2514 |this| visit::walk_assoc_item(this, item, AssocCtxt::Trait),
2518 for item in trait_items {
2520 AssocItemKind::Const(_, ty, default) => {
2522 // Only impose the restrictions of `ConstRibKind` for an
2523 // actual constant expression in a provided default.
2524 if let Some(expr) = default {
2525 // We allow arbitrary const expressions inside of associated consts,
2526 // even if they are potentially not const evaluatable.
2528 // Type parameters can already be used and as associated consts are
2529 // not used as part of the type system, this is far less surprising.
2530 self.with_lifetime_rib(
2531 LifetimeRibKind::Elided(LifetimeRes::Infer),
2533 this.with_constant_rib(
2535 ConstantHasGenerics::Yes,
2537 |this| this.visit_expr(expr),
2543 AssocItemKind::Fn(box Fn { generics, .. }) => {
2544 walk_assoc_item(self, generics, LifetimeBinderKind::Function, item);
2546 AssocItemKind::Type(box TyAlias { generics, .. }) => self
2547 .with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2548 walk_assoc_item(this, generics, LifetimeBinderKind::Item, item)
2550 AssocItemKind::MacCall(_) => {
2551 panic!("unexpanded macro in resolve!")
2556 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
2559 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
2560 fn with_optional_trait_ref<T>(
2562 opt_trait_ref: Option<&TraitRef>,
2563 self_type: &'ast Ty,
2564 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
2566 let mut new_val = None;
2567 let mut new_id = None;
2568 if let Some(trait_ref) = opt_trait_ref {
2569 let path: Vec<_> = Segment::from_path(&trait_ref.path);
2570 self.diagnostic_metadata.currently_processing_impl_trait =
2571 Some((trait_ref.clone(), self_type.clone()));
2572 let res = self.smart_resolve_path_fragment(
2575 PathSource::Trait(AliasPossibility::No),
2576 Finalize::new(trait_ref.ref_id, trait_ref.path.span),
2578 self.diagnostic_metadata.currently_processing_impl_trait = None;
2579 if let Some(def_id) = res.expect_full_res().opt_def_id() {
2580 new_id = Some(def_id);
2581 new_val = Some((self.r.expect_module(def_id), trait_ref.clone()));
2584 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
2585 let result = f(self, new_id);
2586 self.current_trait_ref = original_trait_ref;
2590 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
2591 let mut self_type_rib = Rib::new(NormalRibKind);
2593 // Plain insert (no renaming, since types are not currently hygienic)
2594 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
2595 self.ribs[ns].push(self_type_rib);
2597 self.ribs[ns].pop();
2600 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
2601 self.with_self_rib_ns(TypeNS, self_res, f)
2604 fn resolve_implementation(
2606 generics: &'ast Generics,
2607 opt_trait_reference: &'ast Option<TraitRef>,
2608 self_type: &'ast Ty,
2610 impl_items: &'ast [P<AssocItem>],
2612 debug!("resolve_implementation");
2613 // If applicable, create a rib for the type parameters.
2614 self.with_generic_param_rib(
2616 ItemRibKind(HasGenericParams::Yes(generics.span)),
2617 LifetimeRibKind::Generics {
2618 span: generics.span,
2620 kind: LifetimeBinderKind::ImplBlock,
2623 // Dummy self type for better errors if `Self` is used in the trait path.
2624 this.with_self_rib(Res::SelfTyParam { trait_: LOCAL_CRATE.as_def_id() }, |this| {
2625 this.with_lifetime_rib(
2626 LifetimeRibKind::AnonymousCreateParameter {
2628 report_in_path: true
2631 // Resolve the trait reference, if necessary.
2632 this.with_optional_trait_ref(
2633 opt_trait_reference.as_ref(),
2636 let item_def_id = this.r.local_def_id(item_id);
2638 // Register the trait definitions from here.
2639 if let Some(trait_id) = trait_id {
2647 let item_def_id = item_def_id.to_def_id();
2648 let res = Res::SelfTyAlias {
2649 alias_to: item_def_id,
2650 forbid_generic: false,
2651 is_trait_impl: trait_id.is_some()
2653 this.with_self_rib(res, |this| {
2654 if let Some(trait_ref) = opt_trait_reference.as_ref() {
2655 // Resolve type arguments in the trait path.
2656 visit::walk_trait_ref(this, trait_ref);
2658 // Resolve the self type.
2659 this.visit_ty(self_type);
2660 // Resolve the generic parameters.
2661 this.visit_generics(generics);
2663 // Resolve the items within the impl.
2664 this.with_current_self_type(self_type, |this| {
2665 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
2666 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
2667 let mut seen_trait_items = Default::default();
2668 for item in impl_items {
2669 this.resolve_impl_item(&**item, &mut seen_trait_items);
2683 fn resolve_impl_item(
2685 item: &'ast AssocItem,
2686 seen_trait_items: &mut FxHashMap<DefId, Span>,
2688 use crate::ResolutionError::*;
2690 AssocItemKind::Const(_, ty, default) => {
2691 debug!("resolve_implementation AssocItemKind::Const");
2692 // If this is a trait impl, ensure the const
2694 self.check_trait_item(
2701 |i, s, c| ConstNotMemberOfTrait(i, s, c),
2705 if let Some(expr) = default {
2706 // We allow arbitrary const expressions inside of associated consts,
2707 // even if they are potentially not const evaluatable.
2709 // Type parameters can already be used and as associated consts are
2710 // not used as part of the type system, this is far less surprising.
2711 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2712 this.with_constant_rib(
2714 ConstantHasGenerics::Yes,
2716 |this| this.visit_expr(expr),
2721 AssocItemKind::Fn(box Fn { generics, .. }) => {
2722 debug!("resolve_implementation AssocItemKind::Fn");
2723 // We also need a new scope for the impl item type parameters.
2724 self.with_generic_param_rib(
2727 LifetimeRibKind::Generics {
2729 span: generics.span,
2730 kind: LifetimeBinderKind::Function,
2733 // If this is a trait impl, ensure the method
2735 this.check_trait_item(
2742 |i, s, c| MethodNotMemberOfTrait(i, s, c),
2745 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2749 AssocItemKind::Type(box TyAlias { generics, .. }) => {
2750 debug!("resolve_implementation AssocItemKind::Type");
2751 // We also need a new scope for the impl item type parameters.
2752 self.with_generic_param_rib(
2755 LifetimeRibKind::Generics {
2757 span: generics.span,
2758 kind: LifetimeBinderKind::Item,
2761 this.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2762 // If this is a trait impl, ensure the type
2764 this.check_trait_item(
2771 |i, s, c| TypeNotMemberOfTrait(i, s, c),
2774 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2779 AssocItemKind::MacCall(_) => {
2780 panic!("unexpanded macro in resolve!")
2785 fn check_trait_item<F>(
2789 kind: &AssocItemKind,
2792 seen_trait_items: &mut FxHashMap<DefId, Span>,
2795 F: FnOnce(Ident, String, Option<Symbol>) -> ResolutionError<'a>,
2797 // If there is a TraitRef in scope for an impl, then the method must be in the trait.
2798 let Some((module, _)) = &self.current_trait_ref else { return; };
2799 ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
2800 let key = self.r.new_key(ident, ns);
2801 let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2803 if binding.is_none() {
2804 // We could not find the trait item in the correct namespace.
2805 // Check the other namespace to report an error.
2811 let key = self.r.new_key(ident, ns);
2812 binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2815 let Some(binding) = binding else {
2816 // We could not find the method: report an error.
2817 let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
2818 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2819 let path_names = path_names_to_string(path);
2820 self.report_error(span, err(ident, path_names, candidate));
2824 let res = binding.res();
2825 let Res::Def(def_kind, id_in_trait) = res else { bug!() };
2827 match seen_trait_items.entry(id_in_trait) {
2828 Entry::Occupied(entry) => {
2831 ResolutionError::TraitImplDuplicate {
2833 old_span: *entry.get(),
2834 trait_item_span: binding.span,
2839 Entry::Vacant(entry) => {
2844 match (def_kind, kind) {
2845 (DefKind::AssocTy, AssocItemKind::Type(..))
2846 | (DefKind::AssocFn, AssocItemKind::Fn(..))
2847 | (DefKind::AssocConst, AssocItemKind::Const(..)) => {
2848 self.r.record_partial_res(id, PartialRes::new(res));
2854 // The method kind does not correspond to what appeared in the trait, report.
2855 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2856 let (code, kind) = match kind {
2857 AssocItemKind::Const(..) => (rustc_errors::error_code!(E0323), "const"),
2858 AssocItemKind::Fn(..) => (rustc_errors::error_code!(E0324), "method"),
2859 AssocItemKind::Type(..) => (rustc_errors::error_code!(E0325), "type"),
2860 AssocItemKind::MacCall(..) => span_bug!(span, "unexpanded macro"),
2862 let trait_path = path_names_to_string(path);
2865 ResolutionError::TraitImplMismatch {
2870 trait_item_span: binding.span,
2875 fn resolve_params(&mut self, params: &'ast [Param]) {
2876 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2877 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2878 for Param { pat, .. } in params {
2879 this.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
2882 for Param { ty, .. } in params {
2887 fn resolve_local(&mut self, local: &'ast Local) {
2888 debug!("resolving local ({:?})", local);
2889 // Resolve the type.
2890 walk_list!(self, visit_ty, &local.ty);
2892 // Resolve the initializer.
2893 if let Some((init, els)) = local.kind.init_else_opt() {
2894 self.visit_expr(init);
2896 // Resolve the `else` block
2897 if let Some(els) = els {
2898 self.visit_block(els);
2902 // Resolve the pattern.
2903 self.resolve_pattern_top(&local.pat, PatternSource::Let);
2906 /// build a map from pattern identifiers to binding-info's.
2907 /// this is done hygienically. This could arise for a macro
2908 /// that expands into an or-pattern where one 'x' was from the
2909 /// user and one 'x' came from the macro.
2910 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2911 let mut binding_map = FxHashMap::default();
2913 pat.walk(&mut |pat| {
2915 PatKind::Ident(annotation, ident, ref sub_pat)
2916 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
2918 binding_map.insert(ident, BindingInfo { span: ident.span, annotation });
2920 PatKind::Or(ref ps) => {
2921 // Check the consistency of this or-pattern and
2922 // then add all bindings to the larger map.
2923 for bm in self.check_consistent_bindings(ps) {
2924 binding_map.extend(bm);
2937 fn is_base_res_local(&self, nid: NodeId) -> bool {
2939 self.r.partial_res_map.get(&nid).map(|res| res.expect_full_res()),
2940 Some(Res::Local(..))
2944 /// Checks that all of the arms in an or-pattern have exactly the
2945 /// same set of bindings, with the same binding modes for each.
2946 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
2947 let mut missing_vars = FxHashMap::default();
2948 let mut inconsistent_vars = FxHashMap::default();
2950 // 1) Compute the binding maps of all arms.
2951 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
2953 // 2) Record any missing bindings or binding mode inconsistencies.
2954 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
2955 // Check against all arms except for the same pattern which is always self-consistent.
2959 .filter(|(_, pat)| pat.id != pat_outer.id)
2960 .flat_map(|(idx, _)| maps[idx].iter())
2961 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
2963 for (name, info, &binding_inner) in inners {
2966 // The inner binding is missing in the outer.
2968 missing_vars.entry(name).or_insert_with(|| BindingError {
2970 origin: BTreeSet::new(),
2971 target: BTreeSet::new(),
2972 could_be_path: name.as_str().starts_with(char::is_uppercase),
2974 binding_error.origin.insert(binding_inner.span);
2975 binding_error.target.insert(pat_outer.span);
2977 Some(binding_outer) => {
2978 if binding_outer.annotation != binding_inner.annotation {
2979 // The binding modes in the outer and inner bindings differ.
2982 .or_insert((binding_inner.span, binding_outer.span));
2989 // 3) Report all missing variables we found.
2990 let mut missing_vars = missing_vars.into_iter().collect::<Vec<_>>();
2991 missing_vars.sort_by_key(|&(sym, ref _err)| sym);
2993 for (name, mut v) in missing_vars.into_iter() {
2994 if inconsistent_vars.contains_key(&name) {
2995 v.could_be_path = false;
2998 *v.origin.iter().next().unwrap(),
2999 ResolutionError::VariableNotBoundInPattern(v, self.parent_scope),
3003 // 4) Report all inconsistencies in binding modes we found.
3004 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
3005 inconsistent_vars.sort();
3006 for (name, v) in inconsistent_vars {
3007 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
3010 // 5) Finally bubble up all the binding maps.
3014 /// Check the consistency of the outermost or-patterns.
3015 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
3016 pat.walk(&mut |pat| match pat.kind {
3017 PatKind::Or(ref ps) => {
3018 self.check_consistent_bindings(ps);
3025 fn resolve_arm(&mut self, arm: &'ast Arm) {
3026 self.with_rib(ValueNS, NormalRibKind, |this| {
3027 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
3028 walk_list!(this, visit_expr, &arm.guard);
3029 this.visit_expr(&arm.body);
3033 /// Arising from `source`, resolve a top level pattern.
3034 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
3035 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
3036 self.resolve_pattern(pat, pat_src, &mut bindings);
3042 pat_src: PatternSource,
3043 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3045 // We walk the pattern before declaring the pattern's inner bindings,
3046 // so that we avoid resolving a literal expression to a binding defined
3048 visit::walk_pat(self, pat);
3049 self.resolve_pattern_inner(pat, pat_src, bindings);
3050 // This has to happen *after* we determine which pat_idents are variants:
3051 self.check_consistent_bindings_top(pat);
3054 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
3058 /// A stack of sets of bindings accumulated.
3060 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
3061 /// be interpreted as re-binding an already bound binding. This results in an error.
3062 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
3063 /// in reusing this binding rather than creating a fresh one.
3065 /// When called at the top level, the stack must have a single element
3066 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
3067 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
3068 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
3069 /// When each `p_i` has been dealt with, the top set is merged with its parent.
3070 /// When a whole or-pattern has been dealt with, the thing happens.
3072 /// See the implementation and `fresh_binding` for more details.
3073 fn resolve_pattern_inner(
3076 pat_src: PatternSource,
3077 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3079 // Visit all direct subpatterns of this pattern.
3080 pat.walk(&mut |pat| {
3081 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
3083 PatKind::Ident(bmode, ident, ref sub) => {
3084 // First try to resolve the identifier as some existing entity,
3085 // then fall back to a fresh binding.
3086 let has_sub = sub.is_some();
3088 .try_resolve_as_non_binding(pat_src, bmode, ident, has_sub)
3089 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
3090 self.r.record_partial_res(pat.id, PartialRes::new(res));
3091 self.r.record_pat_span(pat.id, pat.span);
3093 PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
3094 self.smart_resolve_path(
3098 PathSource::TupleStruct(
3100 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
3104 PatKind::Path(ref qself, ref path) => {
3105 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
3107 PatKind::Struct(ref qself, ref path, ..) => {
3108 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Struct);
3110 PatKind::Or(ref ps) => {
3111 // Add a new set of bindings to the stack. `Or` here records that when a
3112 // binding already exists in this set, it should not result in an error because
3113 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
3114 bindings.push((PatBoundCtx::Or, Default::default()));
3116 // Now we need to switch back to a product context so that each
3117 // part of the or-pattern internally rejects already bound names.
3118 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
3119 bindings.push((PatBoundCtx::Product, Default::default()));
3120 self.resolve_pattern_inner(p, pat_src, bindings);
3121 // Move up the non-overlapping bindings to the or-pattern.
3122 // Existing bindings just get "merged".
3123 let collected = bindings.pop().unwrap().1;
3124 bindings.last_mut().unwrap().1.extend(collected);
3126 // This or-pattern itself can itself be part of a product,
3127 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
3128 // Both cases bind `a` again in a product pattern and must be rejected.
3129 let collected = bindings.pop().unwrap().1;
3130 bindings.last_mut().unwrap().1.extend(collected);
3132 // Prevent visiting `ps` as we've already done so above.
3145 pat_src: PatternSource,
3146 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3148 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
3149 // (We must not add it if it's in the bindings map because that breaks the assumptions
3150 // later passes make about or-patterns.)
3151 let ident = ident.normalize_to_macro_rules();
3153 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
3154 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
3155 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
3156 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
3157 // This is *required* for consistency which is checked later.
3158 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
3160 if already_bound_and {
3161 // Overlap in a product pattern somewhere; report an error.
3162 use ResolutionError::*;
3163 let error = match pat_src {
3164 // `fn f(a: u8, a: u8)`:
3165 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
3167 _ => IdentifierBoundMoreThanOnceInSamePattern,
3169 self.report_error(ident.span, error(ident.name));
3172 // Record as bound if it's valid:
3173 let ident_valid = ident.name != kw::Empty;
3175 bindings.last_mut().unwrap().1.insert(ident);
3178 if already_bound_or {
3179 // `Variant1(a) | Variant2(a)`, ok
3180 // Reuse definition from the first `a`.
3181 self.innermost_rib_bindings(ValueNS)[&ident]
3183 let res = Res::Local(pat_id);
3185 // A completely fresh binding add to the set if it's valid.
3186 self.innermost_rib_bindings(ValueNS).insert(ident, res);
3192 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
3193 &mut self.ribs[ns].last_mut().unwrap().bindings
3196 fn try_resolve_as_non_binding(
3198 pat_src: PatternSource,
3199 ann: BindingAnnotation,
3203 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
3204 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
3205 // also be interpreted as a path to e.g. a constant, variant, etc.
3206 let is_syntactic_ambiguity = !has_sub && ann == BindingAnnotation::NONE;
3208 let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?;
3209 let (res, binding) = match ls_binding {
3210 LexicalScopeBinding::Item(binding)
3211 if is_syntactic_ambiguity && binding.is_ambiguity() =>
3213 // For ambiguous bindings we don't know all their definitions and cannot check
3214 // whether they can be shadowed by fresh bindings or not, so force an error.
3215 // issues/33118#issuecomment-233962221 (see below) still applies here,
3216 // but we have to ignore it for backward compatibility.
3217 self.r.record_use(ident, binding, false);
3220 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
3221 LexicalScopeBinding::Res(res) => (res, None),
3225 Res::SelfCtor(_) // See #70549.
3227 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
3229 ) if is_syntactic_ambiguity => {
3230 // Disambiguate in favor of a unit struct/variant or constant pattern.
3231 if let Some(binding) = binding {
3232 self.r.record_use(ident, binding, false);
3236 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static(_), _) => {
3237 // This is unambiguously a fresh binding, either syntactically
3238 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
3239 // to something unusable as a pattern (e.g., constructor function),
3240 // but we still conservatively report an error, see
3241 // issues/33118#issuecomment-233962221 for one reason why.
3242 let binding = binding.expect("no binding for a ctor or static");
3245 ResolutionError::BindingShadowsSomethingUnacceptable {
3246 shadowing_binding: pat_src,
3248 participle: if binding.is_import() { "imported" } else { "defined" },
3249 article: binding.res().article(),
3250 shadowed_binding: binding.res(),
3251 shadowed_binding_span: binding.span,
3256 Res::Def(DefKind::ConstParam, def_id) => {
3257 // Same as for DefKind::Const above, but here, `binding` is `None`, so we
3258 // have to construct the error differently
3261 ResolutionError::BindingShadowsSomethingUnacceptable {
3262 shadowing_binding: pat_src,
3264 participle: "defined",
3265 article: res.article(),
3266 shadowed_binding: res,
3267 shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"),
3272 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
3273 // These entities are explicitly allowed to be shadowed by fresh bindings.
3276 Res::SelfCtor(_) => {
3277 // We resolve `Self` in pattern position as an ident sometimes during recovery,
3278 // so delay a bug instead of ICEing.
3279 self.r.session.delay_span_bug(
3281 "unexpected `SelfCtor` in pattern, expected identifier"
3287 "unexpected resolution for an identifier in pattern: {:?}",
3293 // High-level and context dependent path resolution routine.
3294 // Resolves the path and records the resolution into definition map.
3295 // If resolution fails tries several techniques to find likely
3296 // resolution candidates, suggest imports or other help, and report
3297 // errors in user friendly way.
3298 fn smart_resolve_path(
3301 qself: Option<&QSelf>,
3303 source: PathSource<'ast>,
3305 self.smart_resolve_path_fragment(
3307 &Segment::from_path(path),
3309 Finalize::new(id, path.span),
3313 fn smart_resolve_path_fragment(
3315 qself: Option<&QSelf>,
3317 source: PathSource<'ast>,
3321 "smart_resolve_path_fragment(qself={:?}, path={:?}, finalize={:?})",
3322 qself, path, finalize,
3324 let ns = source.namespace();
3326 let Finalize { node_id, path_span, .. } = finalize;
3327 let report_errors = |this: &mut Self, res: Option<Res>| {
3328 if this.should_report_errs() {
3329 let (err, candidates) =
3330 this.smart_resolve_report_errors(path, path_span, source, res);
3332 let def_id = this.parent_scope.module.nearest_parent_mod();
3333 let instead = res.is_some();
3335 if res.is_none() { this.report_missing_type_error(path) } else { None };
3337 this.r.use_injections.push(UseError {
3344 is_call: source.is_call(),
3348 PartialRes::new(Res::Err)
3351 // For paths originating from calls (like in `HashMap::new()`), tries
3352 // to enrich the plain `failed to resolve: ...` message with hints
3353 // about possible missing imports.
3355 // Similar thing, for types, happens in `report_errors` above.
3356 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
3357 if !source.is_call() {
3358 return Some(parent_err);
3361 // Before we start looking for candidates, we have to get our hands
3362 // on the type user is trying to perform invocation on; basically:
3363 // we're transforming `HashMap::new` into just `HashMap`.
3364 let path = match path.split_last() {
3365 Some((_, path)) if !path.is_empty() => path,
3366 _ => return Some(parent_err),
3369 let (mut err, candidates) =
3370 this.smart_resolve_report_errors(path, path_span, PathSource::Type, None);
3372 // There are two different error messages user might receive at
3374 // - E0412 cannot find type `{}` in this scope
3375 // - E0433 failed to resolve: use of undeclared type or module `{}`
3377 // The first one is emitted for paths in type-position, and the
3378 // latter one - for paths in expression-position.
3380 // Thus (since we're in expression-position at this point), not to
3381 // confuse the user, we want to keep the *message* from E0433 (so
3382 // `parent_err`), but we want *hints* from E0412 (so `err`).
3384 // And that's what happens below - we're just mixing both messages
3385 // into a single one.
3386 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
3388 // overwrite all properties with the parent's error message
3389 err.message = take(&mut parent_err.message);
3390 err.code = take(&mut parent_err.code);
3391 swap(&mut err.span, &mut parent_err.span);
3392 err.children = take(&mut parent_err.children);
3393 err.sort_span = parent_err.sort_span;
3394 err.is_lint = parent_err.is_lint;
3396 // merge the parent's suggestions with the typo suggestions
3397 fn append_result<T, E>(res1: &mut Result<Vec<T>, E>, res2: Result<Vec<T>, E>) {
3399 Ok(vec1) => match res2 {
3400 Ok(mut vec2) => vec1.append(&mut vec2),
3401 Err(e) => *res1 = Err(e),
3406 append_result(&mut err.suggestions, parent_err.suggestions.clone());
3408 parent_err.cancel();
3410 let def_id = this.parent_scope.module.nearest_parent_mod();
3412 if this.should_report_errs() {
3413 if candidates.is_empty() {
3414 // When there is no suggested imports, we can just emit the error
3415 // and suggestions immediately. Note that we bypass the usually error
3416 // reporting routine (ie via `self.r.report_error`) because we need
3417 // to post-process the `ResolutionError` above.
3420 // If there are suggested imports, the error reporting is delayed
3421 this.r.use_injections.push(UseError {
3428 is_call: source.is_call(),
3435 // We don't return `Some(parent_err)` here, because the error will
3436 // be already printed either immediately or as part of the `use` injections
3440 let partial_res = match self.resolve_qpath_anywhere(
3445 source.defer_to_typeck(),
3448 Ok(Some(partial_res)) if let Some(res) = partial_res.full_res() => {
3449 if source.is_expected(res) || res == Res::Err {
3452 report_errors(self, Some(res))
3456 Ok(Some(partial_res)) if source.defer_to_typeck() => {
3457 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
3458 // or `<T>::A::B`. If `B` should be resolved in value namespace then
3459 // it needs to be added to the trait map.
3461 let item_name = path.last().unwrap().ident;
3462 let traits = self.traits_in_scope(item_name, ns);
3463 self.r.trait_map.insert(node_id, traits);
3466 if PrimTy::from_name(path[0].ident.name).is_some() {
3467 let mut std_path = Vec::with_capacity(1 + path.len());
3469 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
3470 std_path.extend(path);
3471 if let PathResult::Module(_) | PathResult::NonModule(_) =
3472 self.resolve_path(&std_path, Some(ns), None)
3474 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
3476 path.iter().last().map_or(path_span, |segment| segment.ident.span);
3478 self.r.confused_type_with_std_module.insert(item_span, path_span);
3479 self.r.confused_type_with_std_module.insert(path_span, path_span);
3487 if let Some(err) = report_errors_for_call(self, err) {
3488 self.report_error(err.span, err.node);
3491 PartialRes::new(Res::Err)
3494 _ => report_errors(self, None),
3497 if !matches!(source, PathSource::TraitItem(..)) {
3498 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
3499 self.r.record_partial_res(node_id, partial_res);
3500 self.resolve_elided_lifetimes_in_path(node_id, partial_res, path, source, path_span);
3506 fn self_type_is_available(&mut self) -> bool {
3508 .maybe_resolve_ident_in_lexical_scope(Ident::with_dummy_span(kw::SelfUpper), TypeNS);
3509 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3512 fn self_value_is_available(&mut self, self_span: Span) -> bool {
3513 let ident = Ident::new(kw::SelfLower, self_span);
3514 let binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS);
3515 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3518 /// A wrapper around [`Resolver::report_error`].
3520 /// This doesn't emit errors for function bodies if this is rustdoc.
3521 fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) {
3522 if self.should_report_errs() {
3523 self.r.report_error(span, resolution_error);
3528 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
3529 fn should_report_errs(&self) -> bool {
3530 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
3533 // Resolve in alternative namespaces if resolution in the primary namespace fails.
3534 fn resolve_qpath_anywhere(
3536 qself: Option<&QSelf>,
3538 primary_ns: Namespace,
3540 defer_to_typeck: bool,
3542 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3543 let mut fin_res = None;
3545 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
3546 if i == 0 || ns != primary_ns {
3547 match self.resolve_qpath(qself, path, ns, finalize)? {
3549 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
3551 return Ok(Some(partial_res));
3554 if fin_res.is_none() {
3555 fin_res = partial_res;
3562 assert!(primary_ns != MacroNS);
3564 if qself.is_none() {
3565 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
3566 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
3567 if let Ok((_, res)) =
3568 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
3570 return Ok(Some(PartialRes::new(res)));
3577 /// Handles paths that may refer to associated items.
3580 qself: Option<&QSelf>,
3584 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3586 "resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})",
3587 qself, path, ns, finalize,
3590 if let Some(qself) = qself {
3591 if qself.position == 0 {
3592 // This is a case like `<T>::B`, where there is no
3593 // trait to resolve. In that case, we leave the `B`
3594 // segment to be resolved by type-check.
3595 return Ok(Some(PartialRes::with_unresolved_segments(
3596 Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()),
3601 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
3603 // Currently, `path` names the full item (`A::B::C`, in
3604 // our example). so we extract the prefix of that that is
3605 // the trait (the slice upto and including
3606 // `qself.position`). And then we recursively resolve that,
3607 // but with `qself` set to `None`.
3608 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
3609 let partial_res = self.smart_resolve_path_fragment(
3611 &path[..=qself.position],
3612 PathSource::TraitItem(ns),
3613 Finalize::with_root_span(finalize.node_id, finalize.path_span, qself.path_span),
3616 // The remaining segments (the `C` in our example) will
3617 // have to be resolved by type-check, since that requires doing
3618 // trait resolution.
3619 return Ok(Some(PartialRes::with_unresolved_segments(
3620 partial_res.base_res(),
3621 partial_res.unresolved_segments() + path.len() - qself.position - 1,
3625 let result = match self.resolve_path(&path, Some(ns), Some(finalize)) {
3626 PathResult::NonModule(path_res) => path_res,
3627 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
3628 PartialRes::new(module.res().unwrap())
3630 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
3631 // don't report an error right away, but try to fallback to a primitive type.
3632 // So, we are still able to successfully resolve something like
3634 // use std::u8; // bring module u8 in scope
3635 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
3636 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
3637 // // not to non-existent std::u8::max_value
3640 // Such behavior is required for backward compatibility.
3641 // The same fallback is used when `a` resolves to nothing.
3642 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
3643 if (ns == TypeNS || path.len() > 1)
3644 && PrimTy::from_name(path[0].ident.name).is_some() =>
3646 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
3647 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
3649 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3650 PartialRes::new(module.res().unwrap())
3652 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
3653 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
3655 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
3656 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
3660 && let Some(res) = result.full_res()
3662 && path[0].ident.name != kw::PathRoot
3663 && path[0].ident.name != kw::DollarCrate
3665 let unqualified_result = {
3666 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
3667 PathResult::NonModule(path_res) => path_res.expect_full_res(),
3668 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3669 module.res().unwrap()
3671 _ => return Ok(Some(result)),
3674 if res == unqualified_result {
3675 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
3676 self.r.lint_buffer.buffer_lint(
3680 "unnecessary qualification",
3688 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
3689 if let Some(label) = label {
3690 if label.ident.as_str().as_bytes()[1] != b'_' {
3691 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
3694 if let Ok((_, orig_span)) = self.resolve_label(label.ident) {
3695 diagnostics::signal_label_shadowing(self.r.session, orig_span, label.ident)
3698 self.with_label_rib(NormalRibKind, |this| {
3699 let ident = label.ident.normalize_to_macro_rules();
3700 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
3708 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
3709 self.with_resolved_label(label, id, |this| this.visit_block(block));
3712 fn resolve_block(&mut self, block: &'ast Block) {
3713 debug!("(resolving block) entering block");
3714 // Move down in the graph, if there's an anonymous module rooted here.
3715 let orig_module = self.parent_scope.module;
3716 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
3718 let mut num_macro_definition_ribs = 0;
3719 if let Some(anonymous_module) = anonymous_module {
3720 debug!("(resolving block) found anonymous module, moving down");
3721 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3722 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3723 self.parent_scope.module = anonymous_module;
3725 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3728 let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
3729 if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
3730 (block.could_be_bare_literal, &block.stmts[..])
3731 && let ExprKind::Type(..) = expr.kind
3733 self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
3736 // Descend into the block.
3737 for stmt in &block.stmts {
3738 if let StmtKind::Item(ref item) = stmt.kind
3739 && let ItemKind::MacroDef(..) = item.kind {
3740 num_macro_definition_ribs += 1;
3741 let res = self.r.local_def_id(item.id).to_def_id();
3742 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
3743 self.label_ribs.push(Rib::new(MacroDefinition(res)));
3746 self.visit_stmt(stmt);
3748 self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
3751 self.parent_scope.module = orig_module;
3752 for _ in 0..num_macro_definition_ribs {
3753 self.ribs[ValueNS].pop();
3754 self.label_ribs.pop();
3756 self.ribs[ValueNS].pop();
3757 if anonymous_module.is_some() {
3758 self.ribs[TypeNS].pop();
3760 debug!("(resolving block) leaving block");
3763 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
3764 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
3765 self.with_constant_rib(
3767 if constant.value.is_potential_trivial_const_param() {
3768 ConstantHasGenerics::Yes
3770 ConstantHasGenerics::No
3773 |this| visit::walk_anon_const(this, constant),
3777 fn resolve_inline_const(&mut self, constant: &'ast AnonConst) {
3778 debug!("resolve_anon_const {constant:?}");
3779 self.with_constant_rib(IsRepeatExpr::No, ConstantHasGenerics::Yes, None, |this| {
3780 visit::walk_anon_const(this, constant)
3784 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
3785 // First, record candidate traits for this expression if it could
3786 // result in the invocation of a method call.
3788 self.record_candidate_traits_for_expr_if_necessary(expr);
3790 // Next, resolve the node.
3792 ExprKind::Path(ref qself, ref path) => {
3793 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
3794 visit::walk_expr(self, expr);
3797 ExprKind::Struct(ref se) => {
3798 self.smart_resolve_path(expr.id, se.qself.as_ref(), &se.path, PathSource::Struct);
3799 visit::walk_expr(self, expr);
3802 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
3803 match self.resolve_label(label.ident) {
3804 Ok((node_id, _)) => {
3805 // Since this res is a label, it is never read.
3806 self.r.label_res_map.insert(expr.id, node_id);
3807 self.diagnostic_metadata.unused_labels.remove(&node_id);
3810 self.report_error(label.ident.span, error);
3814 // visit `break` argument if any
3815 visit::walk_expr(self, expr);
3818 ExprKind::Break(None, Some(ref e)) => {
3819 // We use this instead of `visit::walk_expr` to keep the parent expr around for
3820 // better diagnostics.
3821 self.resolve_expr(e, Some(&expr));
3824 ExprKind::Let(ref pat, ref scrutinee, _) => {
3825 self.visit_expr(scrutinee);
3826 self.resolve_pattern_top(pat, PatternSource::Let);
3829 ExprKind::If(ref cond, ref then, ref opt_else) => {
3830 self.with_rib(ValueNS, NormalRibKind, |this| {
3831 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3832 this.visit_expr(cond);
3833 this.diagnostic_metadata.in_if_condition = old;
3834 this.visit_block(then);
3836 if let Some(expr) = opt_else {
3837 self.visit_expr(expr);
3841 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3843 ExprKind::While(ref cond, ref block, label) => {
3844 self.with_resolved_label(label, expr.id, |this| {
3845 this.with_rib(ValueNS, NormalRibKind, |this| {
3846 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3847 this.visit_expr(cond);
3848 this.diagnostic_metadata.in_if_condition = old;
3849 this.visit_block(block);
3854 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
3855 self.visit_expr(iter_expr);
3856 self.with_rib(ValueNS, NormalRibKind, |this| {
3857 this.resolve_pattern_top(pat, PatternSource::For);
3858 this.resolve_labeled_block(label, expr.id, block);
3862 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
3864 // Equivalent to `visit::walk_expr` + passing some context to children.
3865 ExprKind::Field(ref subexpression, _) => {
3866 self.resolve_expr(subexpression, Some(expr));
3868 ExprKind::MethodCall(ref segment, ref receiver, ref arguments, _) => {
3869 self.resolve_expr(receiver, Some(expr));
3870 for argument in arguments {
3871 self.resolve_expr(argument, None);
3873 self.visit_path_segment(segment);
3876 ExprKind::Call(ref callee, ref arguments) => {
3877 self.resolve_expr(callee, Some(expr));
3878 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
3879 for (idx, argument) in arguments.iter().enumerate() {
3880 // Constant arguments need to be treated as AnonConst since
3881 // that is how they will be later lowered to HIR.
3882 if const_args.contains(&idx) {
3883 self.with_constant_rib(
3885 if argument.is_potential_trivial_const_param() {
3886 ConstantHasGenerics::Yes
3888 ConstantHasGenerics::No
3892 this.resolve_expr(argument, None);
3896 self.resolve_expr(argument, None);
3900 ExprKind::Type(ref type_expr, ref ty) => {
3901 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
3902 // type ascription. Here we are trying to retrieve the span of the colon token as
3903 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
3904 // with `expr::Ty`, only in this case it will match the span from
3905 // `type_ascription_path_suggestions`.
3906 self.diagnostic_metadata
3907 .current_type_ascription
3908 .push(type_expr.span.between(ty.span));
3909 visit::walk_expr(self, expr);
3910 self.diagnostic_metadata.current_type_ascription.pop();
3912 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
3913 // resolve the arguments within the proper scopes so that usages of them inside the
3914 // closure are detected as upvars rather than normal closure arg usages.
3915 ExprKind::Closure(_, _, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
3916 self.with_rib(ValueNS, NormalRibKind, |this| {
3917 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
3918 // Resolve arguments:
3919 this.resolve_params(&fn_decl.inputs);
3920 // No need to resolve return type --
3921 // the outer closure return type is `FnRetTy::Default`.
3923 // Now resolve the inner closure
3925 // No need to resolve arguments: the inner closure has none.
3926 // Resolve the return type:
3927 visit::walk_fn_ret_ty(this, &fn_decl.output);
3929 this.visit_expr(body);
3934 // For closures, ClosureOrAsyncRibKind is added in visit_fn
3935 ExprKind::Closure(ClosureBinder::For { ref generic_params, span }, ..) => {
3936 self.with_generic_param_rib(
3939 LifetimeRibKind::Generics {
3941 kind: LifetimeBinderKind::Closure,
3944 |this| visit::walk_expr(this, expr),
3947 ExprKind::Closure(..) => visit::walk_expr(self, expr),
3948 ExprKind::Async(..) => {
3949 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
3951 ExprKind::Repeat(ref elem, ref ct) => {
3952 self.visit_expr(elem);
3953 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
3954 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
3955 this.resolve_anon_const(ct, IsRepeatExpr::Yes)
3959 ExprKind::ConstBlock(ref ct) => {
3960 self.resolve_inline_const(ct);
3962 ExprKind::Index(ref elem, ref idx) => {
3963 self.resolve_expr(elem, Some(expr));
3964 self.visit_expr(idx);
3966 ExprKind::Assign(..) => {
3967 let old = self.diagnostic_metadata.in_assignment.replace(expr);
3968 visit::walk_expr(self, expr);
3969 self.diagnostic_metadata.in_assignment = old;
3972 visit::walk_expr(self, expr);
3977 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
3979 ExprKind::Field(_, ident) => {
3980 // FIXME(#6890): Even though you can't treat a method like a
3981 // field, we need to add any trait methods we find that match
3982 // the field name so that we can do some nice error reporting
3983 // later on in typeck.
3984 let traits = self.traits_in_scope(ident, ValueNS);
3985 self.r.trait_map.insert(expr.id, traits);
3987 ExprKind::MethodCall(ref segment, ..) => {
3988 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
3989 let traits = self.traits_in_scope(segment.ident, ValueNS);
3990 self.r.trait_map.insert(expr.id, traits);
3998 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
3999 self.r.traits_in_scope(
4000 self.current_trait_ref.as_ref().map(|(module, _)| *module),
4003 Some((ident.name, ns)),
4007 /// Construct the list of in-scope lifetime parameters for async lowering.
4008 /// We include all lifetime parameters, either named or "Fresh".
4009 /// The order of those parameters does not matter, as long as it is
4011 fn record_lifetime_params_for_async(
4014 async_node_id: Option<(NodeId, Span)>,
4016 if let Some((async_node_id, span)) = async_node_id {
4017 let mut extra_lifetime_params =
4018 self.r.extra_lifetime_params_map.get(&fn_id).cloned().unwrap_or_default();
4019 for rib in self.lifetime_ribs.iter().rev() {
4020 extra_lifetime_params.extend(
4021 rib.bindings.iter().map(|(&ident, &(node_id, res))| (ident, node_id, res)),
4024 LifetimeRibKind::Item => break,
4025 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
4026 if let Some(earlier_fresh) = self.r.extra_lifetime_params_map.get(&binder) {
4027 extra_lifetime_params.extend(earlier_fresh);
4030 LifetimeRibKind::Generics { .. } => {}
4032 // We are in a function definition. We should only find `Generics`
4033 // and `AnonymousCreateParameter` inside the innermost `Item`.
4034 span_bug!(span, "unexpected rib kind: {:?}", rib.kind)
4038 self.r.extra_lifetime_params_map.insert(async_node_id, extra_lifetime_params);
4043 struct LifetimeCountVisitor<'a, 'b> {
4044 r: &'b mut Resolver<'a>,
4047 /// Walks the whole crate in DFS order, visiting each item, counting the declared number of
4048 /// lifetime generic parameters.
4049 impl<'ast> Visitor<'ast> for LifetimeCountVisitor<'_, '_> {
4050 fn visit_item(&mut self, item: &'ast Item) {
4052 ItemKind::TyAlias(box TyAlias { ref generics, .. })
4053 | ItemKind::Fn(box Fn { ref generics, .. })
4054 | ItemKind::Enum(_, ref generics)
4055 | ItemKind::Struct(_, ref generics)
4056 | ItemKind::Union(_, ref generics)
4057 | ItemKind::Impl(box Impl { ref generics, .. })
4058 | ItemKind::Trait(box Trait { ref generics, .. })
4059 | ItemKind::TraitAlias(ref generics, _) => {
4060 let def_id = self.r.local_def_id(item.id);
4061 let count = generics
4064 .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
4066 self.r.item_generics_num_lifetimes.insert(def_id, count);
4070 | ItemKind::ForeignMod(..)
4071 | ItemKind::Static(..)
4072 | ItemKind::Const(..)
4074 | ItemKind::ExternCrate(..)
4075 | ItemKind::MacroDef(..)
4076 | ItemKind::GlobalAsm(..)
4077 | ItemKind::MacCall(..) => {}
4079 visit::walk_item(self, item)
4083 impl<'a> Resolver<'a> {
4084 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
4085 visit::walk_crate(&mut LifetimeCountVisitor { r: self }, krate);
4086 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
4087 visit::walk_crate(&mut late_resolution_visitor, krate);
4088 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
4089 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");