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>,
532 /// If we are currently in a trait object definition. Used to point at the bounds when
533 /// encountering a struct or enum.
534 current_trait_object: Option<&'ast [ast::GenericBound]>,
536 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
537 current_where_predicate: Option<&'ast WherePredicate>,
539 current_type_path: Option<&'ast Ty>,
541 /// The current impl items (used to suggest).
542 current_impl_items: Option<&'ast [P<AssocItem>]>,
544 /// When processing impl trait
545 currently_processing_impl_trait: Option<(TraitRef, Ty)>,
547 /// Accumulate the errors due to missed lifetime elision,
548 /// and report them all at once for each function.
549 current_elision_failures: Vec<MissingLifetime>,
552 struct LateResolutionVisitor<'a, 'b, 'ast> {
553 r: &'b mut Resolver<'a>,
555 /// The module that represents the current item scope.
556 parent_scope: ParentScope<'a>,
558 /// The current set of local scopes for types and values.
559 /// FIXME #4948: Reuse ribs to avoid allocation.
560 ribs: PerNS<Vec<Rib<'a>>>,
562 /// The current set of local scopes, for labels.
563 label_ribs: Vec<Rib<'a, NodeId>>,
565 /// The current set of local scopes for lifetimes.
566 lifetime_ribs: Vec<LifetimeRib>,
568 /// We are looking for lifetimes in an elision context.
569 /// The set contains all the resolutions that we encountered so far.
570 /// They will be used to determine the correct lifetime for the fn return type.
571 /// The `LifetimeElisionCandidate` is used for diagnostics, to suggest introducing named
573 lifetime_elision_candidates: Option<Vec<(LifetimeRes, LifetimeElisionCandidate)>>,
575 /// The trait that the current context can refer to.
576 current_trait_ref: Option<(Module<'a>, TraitRef)>,
578 /// Fields used to add information to diagnostic errors.
579 diagnostic_metadata: Box<DiagnosticMetadata<'ast>>,
581 /// State used to know whether to ignore resolution errors for function bodies.
583 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
584 /// In most cases this will be `None`, in which case errors will always be reported.
585 /// If it is `true`, then it will be updated when entering a nested function or trait body.
588 /// Count the number of places a lifetime is used.
589 lifetime_uses: FxHashMap<LocalDefId, LifetimeUseSet>,
592 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
593 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
594 fn visit_attribute(&mut self, _: &'ast Attribute) {
595 // We do not want to resolve expressions that appear in attributes,
596 // as they do not correspond to actual code.
598 fn visit_item(&mut self, item: &'ast Item) {
599 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
600 // Always report errors in items we just entered.
601 let old_ignore = replace(&mut self.in_func_body, false);
602 self.with_lifetime_rib(LifetimeRibKind::Item, |this| this.resolve_item(item));
603 self.in_func_body = old_ignore;
604 self.diagnostic_metadata.current_item = prev;
606 fn visit_arm(&mut self, arm: &'ast Arm) {
607 self.resolve_arm(arm);
609 fn visit_block(&mut self, block: &'ast Block) {
610 self.resolve_block(block);
612 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
613 // We deal with repeat expressions explicitly in `resolve_expr`.
614 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
615 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
616 this.resolve_anon_const(constant, IsRepeatExpr::No);
620 fn visit_expr(&mut self, expr: &'ast Expr) {
621 self.resolve_expr(expr, None);
623 fn visit_local(&mut self, local: &'ast Local) {
624 let local_spans = match local.pat.kind {
625 // We check for this to avoid tuple struct fields.
626 PatKind::Wild => None,
629 local.ty.as_ref().map(|ty| ty.span),
630 local.kind.init().map(|init| init.span),
633 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
634 self.resolve_local(local);
635 self.diagnostic_metadata.current_let_binding = original;
637 fn visit_ty(&mut self, ty: &'ast Ty) {
638 let prev = self.diagnostic_metadata.current_trait_object;
639 let prev_ty = self.diagnostic_metadata.current_type_path;
641 TyKind::Rptr(None, _) => {
642 // Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
644 // This span will be used in case of elision failure.
645 let span = self.r.session.source_map().start_point(ty.span);
646 self.resolve_elided_lifetime(ty.id, span);
647 visit::walk_ty(self, ty);
649 TyKind::Path(ref qself, ref path) => {
650 self.diagnostic_metadata.current_type_path = Some(ty);
651 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
653 // Check whether we should interpret this as a bare trait object.
655 && let Some(partial_res) = self.r.partial_res_map.get(&ty.id)
656 && let Some(Res::Def(DefKind::Trait | DefKind::TraitAlias, _)) = partial_res.full_res()
658 // This path is actually a bare trait object. In case of a bare `Fn`-trait
659 // object with anonymous lifetimes, we need this rib to correctly place the
660 // synthetic lifetimes.
661 let span = ty.span.shrink_to_lo().to(path.span.shrink_to_lo());
662 self.with_generic_param_rib(
665 LifetimeRibKind::Generics {
667 kind: LifetimeBinderKind::PolyTrait,
670 |this| this.visit_path(&path, ty.id),
673 visit::walk_ty(self, ty)
676 TyKind::ImplicitSelf => {
677 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
679 .resolve_ident_in_lexical_scope(
682 Some(Finalize::new(ty.id, ty.span)),
685 .map_or(Res::Err, |d| d.res());
686 self.r.record_partial_res(ty.id, PartialRes::new(res));
687 visit::walk_ty(self, ty)
689 TyKind::ImplTrait(..) => {
690 let candidates = self.lifetime_elision_candidates.take();
691 visit::walk_ty(self, ty);
692 self.lifetime_elision_candidates = candidates;
694 TyKind::TraitObject(ref bounds, ..) => {
695 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
696 visit::walk_ty(self, ty)
698 TyKind::BareFn(ref bare_fn) => {
699 let span = ty.span.shrink_to_lo().to(bare_fn.decl_span.shrink_to_lo());
700 self.with_generic_param_rib(
701 &bare_fn.generic_params,
703 LifetimeRibKind::Generics {
705 kind: LifetimeBinderKind::BareFnType,
709 this.visit_generic_params(&bare_fn.generic_params, false);
710 this.with_lifetime_rib(
711 LifetimeRibKind::AnonymousCreateParameter {
713 report_in_path: false,
716 this.resolve_fn_signature(
719 // We don't need to deal with patterns in parameters, because
720 // they are not possible for foreign or bodiless functions.
725 .map(|Param { ty, .. }| (None, &**ty)),
726 &bare_fn.decl.output,
733 _ => visit::walk_ty(self, ty),
735 self.diagnostic_metadata.current_trait_object = prev;
736 self.diagnostic_metadata.current_type_path = prev_ty;
738 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef) {
739 let span = tref.span.shrink_to_lo().to(tref.trait_ref.path.span.shrink_to_lo());
740 self.with_generic_param_rib(
741 &tref.bound_generic_params,
743 LifetimeRibKind::Generics {
744 binder: tref.trait_ref.ref_id,
745 kind: LifetimeBinderKind::PolyTrait,
749 this.visit_generic_params(&tref.bound_generic_params, false);
750 this.smart_resolve_path(
751 tref.trait_ref.ref_id,
753 &tref.trait_ref.path,
754 PathSource::Trait(AliasPossibility::Maybe),
756 this.visit_trait_ref(&tref.trait_ref);
760 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
761 match foreign_item.kind {
762 ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
763 self.with_generic_param_rib(
765 ItemRibKind(HasGenericParams::Yes(generics.span)),
766 LifetimeRibKind::Generics {
767 binder: foreign_item.id,
768 kind: LifetimeBinderKind::Item,
771 |this| visit::walk_foreign_item(this, foreign_item),
774 ForeignItemKind::Fn(box Fn { ref generics, .. }) => {
775 self.with_generic_param_rib(
777 ItemRibKind(HasGenericParams::Yes(generics.span)),
778 LifetimeRibKind::Generics {
779 binder: foreign_item.id,
780 kind: LifetimeBinderKind::Function,
783 |this| visit::walk_foreign_item(this, foreign_item),
786 ForeignItemKind::Static(..) => {
787 self.with_static_rib(|this| {
788 visit::walk_foreign_item(this, foreign_item);
791 ForeignItemKind::MacCall(..) => {
792 panic!("unexpanded macro in resolve!")
796 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, fn_id: NodeId) {
797 let previous_value = self.diagnostic_metadata.current_function;
799 // Bail if the function is foreign, and thus cannot validly have
800 // a body, or if there's no body for some other reason.
801 FnKind::Fn(FnCtxt::Foreign, _, sig, _, generics, _)
802 | FnKind::Fn(_, _, sig, _, generics, None) => {
803 self.visit_fn_header(&sig.header);
804 self.visit_generics(generics);
805 self.with_lifetime_rib(
806 LifetimeRibKind::AnonymousCreateParameter {
808 report_in_path: false,
811 this.resolve_fn_signature(
814 sig.decl.inputs.iter().map(|Param { ty, .. }| (None, &**ty)),
818 this.record_lifetime_params_for_async(
820 sig.header.asyncness.opt_return_id(),
827 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
829 // Do not update `current_function` for closures: it suggests `self` parameters.
830 FnKind::Closure(..) => {}
832 debug!("(resolving function) entering function");
834 // Create a value rib for the function.
835 self.with_rib(ValueNS, ClosureOrAsyncRibKind, |this| {
836 // Create a label rib for the function.
837 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
839 FnKind::Fn(_, _, sig, _, generics, body) => {
840 this.visit_generics(generics);
842 let declaration = &sig.decl;
843 let async_node_id = sig.header.asyncness.opt_return_id();
845 this.with_lifetime_rib(
846 LifetimeRibKind::AnonymousCreateParameter {
848 report_in_path: async_node_id.is_some(),
851 this.resolve_fn_signature(
853 declaration.has_self(),
857 .map(|Param { pat, ty, .. }| (Some(&**pat), &**ty)),
863 this.record_lifetime_params_for_async(fn_id, async_node_id);
865 if let Some(body) = body {
866 // Ignore errors in function bodies if this is rustdoc
867 // Be sure not to set this until the function signature has been resolved.
868 let previous_state = replace(&mut this.in_func_body, true);
869 // Resolve the function body, potentially inside the body of an async closure
870 this.with_lifetime_rib(
871 LifetimeRibKind::Elided(LifetimeRes::Infer),
872 |this| this.visit_block(body),
875 debug!("(resolving function) leaving function");
876 this.in_func_body = previous_state;
879 FnKind::Closure(binder, declaration, body) => {
880 this.visit_closure_binder(binder);
882 this.with_lifetime_rib(
884 // We do not have any explicit generic lifetime parameter.
885 ClosureBinder::NotPresent => {
886 LifetimeRibKind::AnonymousCreateParameter {
888 report_in_path: false,
891 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
893 // Add each argument to the rib.
894 |this| this.resolve_params(&declaration.inputs),
896 this.with_lifetime_rib(
898 ClosureBinder::NotPresent => {
899 LifetimeRibKind::Elided(LifetimeRes::Infer)
901 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
903 |this| visit::walk_fn_ret_ty(this, &declaration.output),
906 // Ignore errors in function bodies if this is rustdoc
907 // Be sure not to set this until the function signature has been resolved.
908 let previous_state = replace(&mut this.in_func_body, true);
909 // Resolve the function body, potentially inside the body of an async closure
910 this.with_lifetime_rib(
911 LifetimeRibKind::Elided(LifetimeRes::Infer),
912 |this| this.visit_expr(body),
915 debug!("(resolving function) leaving function");
916 this.in_func_body = previous_state;
921 self.diagnostic_metadata.current_function = previous_value;
923 fn visit_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
924 self.resolve_lifetime(lifetime, use_ctxt)
927 fn visit_generics(&mut self, generics: &'ast Generics) {
928 self.visit_generic_params(
930 self.diagnostic_metadata.current_self_item.is_some(),
932 for p in &generics.where_clause.predicates {
933 self.visit_where_predicate(p);
937 fn visit_closure_binder(&mut self, b: &'ast ClosureBinder) {
939 ClosureBinder::NotPresent => {}
940 ClosureBinder::For { generic_params, .. } => {
941 self.visit_generic_params(
943 self.diagnostic_metadata.current_self_item.is_some(),
949 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
950 debug!("visit_generic_arg({:?})", arg);
951 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
953 GenericArg::Type(ref ty) => {
954 // We parse const arguments as path types as we cannot distinguish them during
955 // parsing. We try to resolve that ambiguity by attempting resolution the type
956 // namespace first, and if that fails we try again in the value namespace. If
957 // resolution in the value namespace succeeds, we have an generic const argument on
959 if let TyKind::Path(ref qself, ref path) = ty.kind {
960 // We cannot disambiguate multi-segment paths right now as that requires type
962 if path.segments.len() == 1 && path.segments[0].args.is_none() {
963 let mut check_ns = |ns| {
964 self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns)
967 if !check_ns(TypeNS) && check_ns(ValueNS) {
968 // This must be equivalent to `visit_anon_const`, but we cannot call it
969 // directly due to visitor lifetimes so we have to copy-paste some code.
971 // Note that we might not be inside of an repeat expression here,
972 // but considering that `IsRepeatExpr` is only relevant for
973 // non-trivial constants this is doesn't matter.
974 self.with_constant_rib(
976 ConstantHasGenerics::Yes,
979 this.smart_resolve_path(
983 PathSource::Expr(None),
986 if let Some(ref qself) = *qself {
987 this.visit_ty(&qself.ty);
989 this.visit_path(path, ty.id);
993 self.diagnostic_metadata.currently_processing_generics = prev;
1001 GenericArg::Lifetime(lt) => self.visit_lifetime(lt, visit::LifetimeCtxt::GenericArg),
1002 GenericArg::Const(ct) => self.visit_anon_const(ct),
1004 self.diagnostic_metadata.currently_processing_generics = prev;
1007 fn visit_assoc_constraint(&mut self, constraint: &'ast AssocConstraint) {
1008 self.visit_ident(constraint.ident);
1009 if let Some(ref gen_args) = constraint.gen_args {
1010 // Forbid anonymous lifetimes in GAT parameters until proper semantics are decided.
1011 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1012 this.visit_generic_args(gen_args)
1015 match constraint.kind {
1016 AssocConstraintKind::Equality { ref term } => match term {
1017 Term::Ty(ty) => self.visit_ty(ty),
1018 Term::Const(c) => self.visit_anon_const(c),
1020 AssocConstraintKind::Bound { ref bounds } => {
1021 walk_list!(self, visit_param_bound, bounds, BoundKind::Bound);
1026 fn visit_path_segment(&mut self, path_segment: &'ast PathSegment) {
1027 if let Some(ref args) = path_segment.args {
1029 GenericArgs::AngleBracketed(..) => visit::walk_generic_args(self, args),
1030 GenericArgs::Parenthesized(p_args) => {
1031 // Probe the lifetime ribs to know how to behave.
1032 for rib in self.lifetime_ribs.iter().rev() {
1034 // We are inside a `PolyTraitRef`. The lifetimes are
1035 // to be intoduced in that (maybe implicit) `for<>` binder.
1036 LifetimeRibKind::Generics {
1038 kind: LifetimeBinderKind::PolyTrait,
1041 self.with_lifetime_rib(
1042 LifetimeRibKind::AnonymousCreateParameter {
1044 report_in_path: false,
1047 this.resolve_fn_signature(
1050 p_args.inputs.iter().map(|ty| (None, &**ty)),
1057 // We have nowhere to introduce generics. Code is malformed,
1058 // so use regular lifetime resolution to avoid spurious errors.
1059 LifetimeRibKind::Item | LifetimeRibKind::Generics { .. } => {
1060 visit::walk_generic_args(self, args);
1063 LifetimeRibKind::AnonymousCreateParameter { .. }
1064 | LifetimeRibKind::AnonymousReportError
1065 | LifetimeRibKind::Elided(_)
1066 | LifetimeRibKind::ElisionFailure
1067 | LifetimeRibKind::AnonConst
1068 | LifetimeRibKind::ConstGeneric => {}
1076 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
1077 debug!("visit_where_predicate {:?}", p);
1078 let previous_value =
1079 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
1080 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1081 if let WherePredicate::BoundPredicate(WhereBoundPredicate {
1084 ref bound_generic_params,
1085 span: predicate_span,
1089 let span = predicate_span.shrink_to_lo().to(bounded_ty.span.shrink_to_lo());
1090 this.with_generic_param_rib(
1091 &bound_generic_params,
1093 LifetimeRibKind::Generics {
1094 binder: bounded_ty.id,
1095 kind: LifetimeBinderKind::WhereBound,
1099 this.visit_generic_params(&bound_generic_params, false);
1100 this.visit_ty(bounded_ty);
1101 for bound in bounds {
1102 this.visit_param_bound(bound, BoundKind::Bound)
1107 visit::walk_where_predicate(this, p);
1110 self.diagnostic_metadata.current_where_predicate = previous_value;
1113 fn visit_inline_asm(&mut self, asm: &'ast InlineAsm) {
1114 for (op, _) in &asm.operands {
1116 InlineAsmOperand::In { expr, .. }
1117 | InlineAsmOperand::Out { expr: Some(expr), .. }
1118 | InlineAsmOperand::InOut { expr, .. } => self.visit_expr(expr),
1119 InlineAsmOperand::Out { expr: None, .. } => {}
1120 InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
1121 self.visit_expr(in_expr);
1122 if let Some(out_expr) = out_expr {
1123 self.visit_expr(out_expr);
1126 InlineAsmOperand::Const { anon_const, .. } => {
1127 // Although this is `DefKind::AnonConst`, it is allowed to reference outer
1128 // generic parameters like an inline const.
1129 self.resolve_inline_const(anon_const);
1131 InlineAsmOperand::Sym { sym } => self.visit_inline_asm_sym(sym),
1136 fn visit_inline_asm_sym(&mut self, sym: &'ast InlineAsmSym) {
1137 // This is similar to the code for AnonConst.
1138 self.with_rib(ValueNS, InlineAsmSymRibKind, |this| {
1139 this.with_rib(TypeNS, InlineAsmSymRibKind, |this| {
1140 this.with_label_rib(InlineAsmSymRibKind, |this| {
1141 this.smart_resolve_path(
1145 PathSource::Expr(None),
1147 visit::walk_inline_asm_sym(this, sym);
1154 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
1155 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
1156 // During late resolution we only track the module component of the parent scope,
1157 // although it may be useful to track other components as well for diagnostics.
1158 let graph_root = resolver.graph_root;
1159 let parent_scope = ParentScope::module(graph_root, resolver);
1160 let start_rib_kind = ModuleRibKind(graph_root);
1161 LateResolutionVisitor {
1165 value_ns: vec![Rib::new(start_rib_kind)],
1166 type_ns: vec![Rib::new(start_rib_kind)],
1167 macro_ns: vec![Rib::new(start_rib_kind)],
1169 label_ribs: Vec::new(),
1170 lifetime_ribs: Vec::new(),
1171 lifetime_elision_candidates: None,
1172 current_trait_ref: None,
1173 diagnostic_metadata: Box::new(DiagnosticMetadata::default()),
1174 // errors at module scope should always be reported
1175 in_func_body: false,
1176 lifetime_uses: Default::default(),
1180 fn maybe_resolve_ident_in_lexical_scope(
1184 ) -> Option<LexicalScopeBinding<'a>> {
1185 self.r.resolve_ident_in_lexical_scope(
1195 fn resolve_ident_in_lexical_scope(
1199 finalize: Option<Finalize>,
1200 ignore_binding: Option<&'a NameBinding<'a>>,
1201 ) -> Option<LexicalScopeBinding<'a>> {
1202 self.r.resolve_ident_in_lexical_scope(
1215 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1216 finalize: Option<Finalize>,
1217 ) -> PathResult<'a> {
1218 self.r.resolve_path_with_ribs(
1230 // We maintain a list of value ribs and type ribs.
1232 // Simultaneously, we keep track of the current position in the module
1233 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
1234 // the value or type namespaces, we first look through all the ribs and
1235 // then query the module graph. When we resolve a name in the module
1236 // namespace, we can skip all the ribs (since nested modules are not
1237 // allowed within blocks in Rust) and jump straight to the current module
1240 // Named implementations are handled separately. When we find a method
1241 // call, we consult the module node to find all of the implementations in
1242 // scope. This information is lazily cached in the module node. We then
1243 // generate a fake "implementation scope" containing all the
1244 // implementations thus found, for compatibility with old resolve pass.
1246 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
1251 work: impl FnOnce(&mut Self) -> T,
1253 self.ribs[ns].push(Rib::new(kind));
1254 let ret = work(self);
1255 self.ribs[ns].pop();
1259 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
1260 if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
1261 // Move down in the graph.
1262 let orig_module = replace(&mut self.parent_scope.module, module);
1263 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
1264 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
1266 this.parent_scope.module = orig_module;
1275 fn visit_generic_params(&mut self, params: &'ast [GenericParam], add_self_upper: bool) {
1276 // For type parameter defaults, we have to ban access
1277 // to following type parameters, as the InternalSubsts can only
1278 // provide previous type parameters as they're built. We
1279 // put all the parameters on the ban list and then remove
1280 // them one by one as they are processed and become available.
1281 let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1282 let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1283 for param in params.iter() {
1285 GenericParamKind::Type { .. } => {
1288 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1290 GenericParamKind::Const { .. } => {
1291 forward_const_ban_rib
1293 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1295 GenericParamKind::Lifetime => {}
1299 // rust-lang/rust#61631: The type `Self` is essentially
1300 // another type parameter. For ADTs, we consider it
1301 // well-defined only after all of the ADT type parameters have
1302 // been provided. Therefore, we do not allow use of `Self`
1303 // anywhere in ADT type parameter defaults.
1305 // (We however cannot ban `Self` for defaults on *all* generic
1306 // lists; e.g. trait generics can usefully refer to `Self`,
1307 // such as in the case of `trait Add<Rhs = Self>`.)
1309 // (`Some` if + only if we are in ADT's generics.)
1310 forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
1313 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1314 for param in params {
1316 GenericParamKind::Lifetime => {
1317 for bound in ¶m.bounds {
1318 this.visit_param_bound(bound, BoundKind::Bound);
1321 GenericParamKind::Type { ref default } => {
1322 for bound in ¶m.bounds {
1323 this.visit_param_bound(bound, BoundKind::Bound);
1326 if let Some(ref ty) = default {
1327 this.ribs[TypeNS].push(forward_ty_ban_rib);
1328 this.ribs[ValueNS].push(forward_const_ban_rib);
1330 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1331 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1334 // Allow all following defaults to refer to this type parameter.
1337 .remove(&Ident::with_dummy_span(param.ident.name));
1339 GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
1340 // Const parameters can't have param bounds.
1341 assert!(param.bounds.is_empty());
1343 this.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
1344 this.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
1345 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1348 this.ribs[TypeNS].pop().unwrap();
1349 this.ribs[ValueNS].pop().unwrap();
1351 if let Some(ref expr) = default {
1352 this.ribs[TypeNS].push(forward_ty_ban_rib);
1353 this.ribs[ValueNS].push(forward_const_ban_rib);
1354 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1355 this.resolve_anon_const(expr, IsRepeatExpr::No)
1357 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1358 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1361 // Allow all following defaults to refer to this const parameter.
1362 forward_const_ban_rib
1364 .remove(&Ident::with_dummy_span(param.ident.name));
1371 #[instrument(level = "debug", skip(self, work))]
1372 fn with_lifetime_rib<T>(
1374 kind: LifetimeRibKind,
1375 work: impl FnOnce(&mut Self) -> T,
1377 self.lifetime_ribs.push(LifetimeRib::new(kind));
1378 let outer_elision_candidates = self.lifetime_elision_candidates.take();
1379 let ret = work(self);
1380 self.lifetime_elision_candidates = outer_elision_candidates;
1381 self.lifetime_ribs.pop();
1385 #[instrument(level = "debug", skip(self))]
1386 fn resolve_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
1387 let ident = lifetime.ident;
1389 if ident.name == kw::StaticLifetime {
1390 self.record_lifetime_res(
1392 LifetimeRes::Static,
1393 LifetimeElisionCandidate::Named,
1398 if ident.name == kw::UnderscoreLifetime {
1399 return self.resolve_anonymous_lifetime(lifetime, false);
1402 let mut lifetime_rib_iter = self.lifetime_ribs.iter().rev();
1403 while let Some(rib) = lifetime_rib_iter.next() {
1404 let normalized_ident = ident.normalize_to_macros_2_0();
1405 if let Some(&(_, res)) = rib.bindings.get(&normalized_ident) {
1406 self.record_lifetime_res(lifetime.id, res, LifetimeElisionCandidate::Named);
1408 if let LifetimeRes::Param { param, .. } = res {
1409 match self.lifetime_uses.entry(param) {
1410 Entry::Vacant(v) => {
1411 debug!("First use of {:?} at {:?}", res, ident.span);
1416 .find_map(|rib| match rib.kind {
1417 // Do not suggest eliding a lifetime where an anonymous
1418 // lifetime would be illegal.
1419 LifetimeRibKind::Item
1420 | LifetimeRibKind::AnonymousReportError
1421 | LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many),
1422 // An anonymous lifetime is legal here, go ahead.
1423 LifetimeRibKind::AnonymousCreateParameter { .. } => {
1424 Some(LifetimeUseSet::One { use_span: ident.span, use_ctxt })
1426 // Only report if eliding the lifetime would have the same
1428 LifetimeRibKind::Elided(r) => Some(if res == r {
1429 LifetimeUseSet::One { use_span: ident.span, use_ctxt }
1431 LifetimeUseSet::Many
1433 LifetimeRibKind::Generics { .. } => None,
1434 LifetimeRibKind::ConstGeneric | LifetimeRibKind::AnonConst => {
1435 span_bug!(ident.span, "unexpected rib kind: {:?}", rib.kind)
1438 .unwrap_or(LifetimeUseSet::Many);
1439 debug!(?use_ctxt, ?use_set);
1442 Entry::Occupied(mut o) => {
1443 debug!("Many uses of {:?} at {:?}", res, ident.span);
1444 *o.get_mut() = LifetimeUseSet::Many;
1452 LifetimeRibKind::Item => break,
1453 LifetimeRibKind::ConstGeneric => {
1454 self.emit_non_static_lt_in_const_generic_error(lifetime);
1455 self.record_lifetime_res(
1458 LifetimeElisionCandidate::Ignore,
1462 LifetimeRibKind::AnonConst => {
1463 self.maybe_emit_forbidden_non_static_lifetime_error(lifetime);
1464 self.record_lifetime_res(
1467 LifetimeElisionCandidate::Ignore,
1471 LifetimeRibKind::AnonymousCreateParameter { .. }
1472 | LifetimeRibKind::Elided(_)
1473 | LifetimeRibKind::Generics { .. }
1474 | LifetimeRibKind::ElisionFailure
1475 | LifetimeRibKind::AnonymousReportError => {}
1479 let mut outer_res = None;
1480 for rib in lifetime_rib_iter {
1481 let normalized_ident = ident.normalize_to_macros_2_0();
1482 if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) {
1483 outer_res = Some(outer);
1488 self.emit_undeclared_lifetime_error(lifetime, outer_res);
1489 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, LifetimeElisionCandidate::Named);
1492 #[instrument(level = "debug", skip(self))]
1493 fn resolve_anonymous_lifetime(&mut self, lifetime: &Lifetime, elided: bool) {
1494 debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
1496 let missing_lifetime = MissingLifetime {
1498 span: lifetime.ident.span,
1500 MissingLifetimeKind::Ampersand
1502 MissingLifetimeKind::Underscore
1506 let elision_candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1507 for rib in self.lifetime_ribs.iter().rev() {
1510 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1511 let res = self.create_fresh_lifetime(lifetime.id, lifetime.ident, binder);
1512 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1515 LifetimeRibKind::AnonymousReportError => {
1516 let (msg, note) = if elided {
1518 "`&` without an explicit lifetime name cannot be used here",
1519 "explicit lifetime name needed here",
1522 ("`'_` cannot be used here", "`'_` is a reserved lifetime name")
1524 rustc_errors::struct_span_err!(
1526 lifetime.ident.span,
1531 .span_label(lifetime.ident.span, note)
1534 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1537 LifetimeRibKind::Elided(res) => {
1538 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1541 LifetimeRibKind::ElisionFailure => {
1542 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1543 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1546 LifetimeRibKind::Item => break,
1547 LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstGeneric => {}
1548 LifetimeRibKind::AnonConst => {
1549 // There is always an `Elided(LifetimeRes::Static)` inside an `AnonConst`.
1550 span_bug!(lifetime.ident.span, "unexpected rib kind: {:?}", rib.kind)
1554 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1555 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1558 #[instrument(level = "debug", skip(self))]
1559 fn resolve_elided_lifetime(&mut self, anchor_id: NodeId, span: Span) {
1560 let id = self.r.next_node_id();
1561 let lt = Lifetime { id, ident: Ident::new(kw::UnderscoreLifetime, span) };
1563 self.record_lifetime_res(
1565 LifetimeRes::ElidedAnchor { start: id, end: NodeId::from_u32(id.as_u32() + 1) },
1566 LifetimeElisionCandidate::Ignore,
1568 self.resolve_anonymous_lifetime(<, true);
1571 #[instrument(level = "debug", skip(self))]
1572 fn create_fresh_lifetime(&mut self, id: NodeId, ident: Ident, binder: NodeId) -> LifetimeRes {
1573 debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
1574 debug!(?ident.span);
1576 // Leave the responsibility to create the `LocalDefId` to lowering.
1577 let param = self.r.next_node_id();
1578 let res = LifetimeRes::Fresh { param, binder };
1580 // Record the created lifetime parameter so lowering can pick it up and add it to HIR.
1582 .extra_lifetime_params_map
1584 .or_insert_with(Vec::new)
1585 .push((ident, param, res));
1589 #[instrument(level = "debug", skip(self))]
1590 fn resolve_elided_lifetimes_in_path(
1593 partial_res: PartialRes,
1595 source: PathSource<'_>,
1598 let proj_start = path.len() - partial_res.unresolved_segments();
1599 for (i, segment) in path.iter().enumerate() {
1600 if segment.has_lifetime_args {
1603 let Some(segment_id) = segment.id else {
1607 // Figure out if this is a type/trait segment,
1608 // which may need lifetime elision performed.
1609 let type_def_id = match partial_res.base_res() {
1610 Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => self.r.parent(def_id),
1611 Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => self.r.parent(def_id),
1612 Res::Def(DefKind::Struct, def_id)
1613 | Res::Def(DefKind::Union, def_id)
1614 | Res::Def(DefKind::Enum, def_id)
1615 | Res::Def(DefKind::TyAlias, def_id)
1616 | Res::Def(DefKind::Trait, def_id)
1617 if i + 1 == proj_start =>
1624 let expected_lifetimes = self.r.item_generics_num_lifetimes(type_def_id);
1625 if expected_lifetimes == 0 {
1629 let node_ids = self.r.next_node_ids(expected_lifetimes);
1630 self.record_lifetime_res(
1632 LifetimeRes::ElidedAnchor { start: node_ids.start, end: node_ids.end },
1633 LifetimeElisionCandidate::Ignore,
1636 let inferred = match source {
1637 PathSource::Trait(..) | PathSource::TraitItem(..) | PathSource::Type => false,
1638 PathSource::Expr(..)
1640 | PathSource::Struct
1641 | PathSource::TupleStruct(..) => true,
1644 // Do not create a parameter for patterns and expressions: type checking can infer
1645 // the appropriate lifetime for us.
1646 for id in node_ids {
1647 self.record_lifetime_res(
1650 LifetimeElisionCandidate::Named,
1656 let elided_lifetime_span = if segment.has_generic_args {
1657 // If there are brackets, but not generic arguments, then use the opening bracket
1658 segment.args_span.with_hi(segment.args_span.lo() + BytePos(1))
1660 // If there are no brackets, use the identifier span.
1661 // HACK: we use find_ancestor_inside to properly suggest elided spans in paths
1662 // originating from macros, since the segment's span might be from a macro arg.
1663 segment.ident.span.find_ancestor_inside(path_span).unwrap_or(path_span)
1665 let ident = Ident::new(kw::UnderscoreLifetime, elided_lifetime_span);
1667 let missing_lifetime = MissingLifetime {
1669 span: elided_lifetime_span,
1670 kind: if segment.has_generic_args {
1671 MissingLifetimeKind::Comma
1673 MissingLifetimeKind::Brackets
1675 count: expected_lifetimes,
1677 let mut should_lint = true;
1678 for rib in self.lifetime_ribs.iter().rev() {
1680 // In create-parameter mode we error here because we don't want to support
1681 // deprecated impl elision in new features like impl elision and `async fn`,
1682 // both of which work using the `CreateParameter` mode:
1684 // impl Foo for std::cell::Ref<u32> // note lack of '_
1685 // async fn foo(_: std::cell::Ref<u32>) { ... }
1686 LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. } => {
1687 let sess = self.r.session;
1688 let mut err = rustc_errors::struct_span_err!(
1692 "implicit elided lifetime not allowed here"
1694 rustc_errors::add_elided_lifetime_in_path_suggestion(
1699 !segment.has_generic_args,
1700 elided_lifetime_span,
1702 err.note("assuming a `'static` lifetime...");
1704 should_lint = false;
1706 for id in node_ids {
1707 self.record_lifetime_res(
1710 LifetimeElisionCandidate::Named,
1715 // Do not create a parameter for patterns and expressions.
1716 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1717 // Group all suggestions into the first record.
1718 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1719 for id in node_ids {
1720 let res = self.create_fresh_lifetime(id, ident, binder);
1721 self.record_lifetime_res(
1724 replace(&mut candidate, LifetimeElisionCandidate::Named),
1729 LifetimeRibKind::Elided(res) => {
1730 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1731 for id in node_ids {
1732 self.record_lifetime_res(
1735 replace(&mut candidate, LifetimeElisionCandidate::Ignore),
1740 LifetimeRibKind::ElisionFailure => {
1741 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1742 for id in node_ids {
1743 self.record_lifetime_res(
1746 LifetimeElisionCandidate::Ignore,
1751 // `LifetimeRes::Error`, which would usually be used in the case of
1752 // `ReportError`, is unsuitable here, as we don't emit an error yet. Instead,
1753 // we simply resolve to an implicit lifetime, which will be checked later, at
1754 // which point a suitable error will be emitted.
1755 LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
1756 for id in node_ids {
1757 self.record_lifetime_res(
1760 LifetimeElisionCandidate::Ignore,
1763 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1766 LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstGeneric => {}
1767 LifetimeRibKind::AnonConst => {
1768 // There is always an `Elided(LifetimeRes::Static)` inside an `AnonConst`.
1769 span_bug!(elided_lifetime_span, "unexpected rib kind: {:?}", rib.kind)
1775 self.r.lint_buffer.buffer_lint_with_diagnostic(
1776 lint::builtin::ELIDED_LIFETIMES_IN_PATHS,
1778 elided_lifetime_span,
1779 "hidden lifetime parameters in types are deprecated",
1780 lint::BuiltinLintDiagnostics::ElidedLifetimesInPaths(
1783 !segment.has_generic_args,
1784 elided_lifetime_span,
1791 #[instrument(level = "debug", skip(self))]
1792 fn record_lifetime_res(
1796 candidate: LifetimeElisionCandidate,
1798 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1800 "lifetime {:?} resolved multiple times ({:?} before, {:?} now)",
1805 LifetimeRes::Param { .. } | LifetimeRes::Fresh { .. } | LifetimeRes::Static => {
1806 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
1807 candidates.push((res, candidate));
1810 LifetimeRes::Infer | LifetimeRes::Error | LifetimeRes::ElidedAnchor { .. } => {}
1814 #[instrument(level = "debug", skip(self))]
1815 fn record_lifetime_param(&mut self, id: NodeId, res: LifetimeRes) {
1816 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1818 "lifetime parameter {:?} resolved multiple times ({:?} before, {:?} now)",
1824 /// Perform resolution of a function signature, accounting for lifetime elision.
1825 #[instrument(level = "debug", skip(self, inputs))]
1826 fn resolve_fn_signature(
1830 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)> + Clone,
1831 output_ty: &'ast FnRetTy,
1833 // Add each argument to the rib.
1834 let elision_lifetime = self.resolve_fn_params(has_self, inputs);
1835 debug!(?elision_lifetime);
1837 let outer_failures = take(&mut self.diagnostic_metadata.current_elision_failures);
1838 let output_rib = if let Ok(res) = elision_lifetime.as_ref() {
1839 LifetimeRibKind::Elided(*res)
1841 LifetimeRibKind::ElisionFailure
1843 self.with_lifetime_rib(output_rib, |this| visit::walk_fn_ret_ty(this, &output_ty));
1844 let elision_failures =
1845 replace(&mut self.diagnostic_metadata.current_elision_failures, outer_failures);
1846 if !elision_failures.is_empty() {
1847 let Err(failure_info) = elision_lifetime else { bug!() };
1848 self.report_missing_lifetime_specifiers(elision_failures, Some(failure_info));
1852 /// Resolve inside function parameters and parameter types.
1853 /// Returns the lifetime for elision in fn return type,
1854 /// or diagnostic information in case of elision failure.
1855 fn resolve_fn_params(
1858 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)>,
1859 ) -> Result<LifetimeRes, (Vec<MissingLifetime>, Vec<ElisionFnParameter>)> {
1861 /// We have not found any candidate.
1863 /// We have a candidate bound to `self`.
1865 /// We have a candidate bound to a parameter.
1867 /// We failed elision.
1871 // Save elision state to reinstate it later.
1872 let outer_candidates = self.lifetime_elision_candidates.take();
1874 // Result of elision.
1875 let mut elision_lifetime = Elision::None;
1876 // Information for diagnostics.
1877 let mut parameter_info = Vec::new();
1878 let mut all_candidates = Vec::new();
1880 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1881 for (index, (pat, ty)) in inputs.enumerate() {
1883 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
1884 if let Some(pat) = pat {
1885 this.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1889 // Record elision candidates only for this parameter.
1890 debug_assert_matches!(self.lifetime_elision_candidates, None);
1891 self.lifetime_elision_candidates = Some(Default::default());
1893 let local_candidates = self.lifetime_elision_candidates.take();
1895 if let Some(candidates) = local_candidates {
1896 let distinct: FxHashSet<_> = candidates.iter().map(|(res, _)| *res).collect();
1897 let lifetime_count = distinct.len();
1898 if lifetime_count != 0 {
1899 parameter_info.push(ElisionFnParameter {
1901 ident: if let Some(pat) = pat && let PatKind::Ident(_, ident, _) = pat.kind {
1909 all_candidates.extend(candidates.into_iter().filter_map(|(_, candidate)| {
1911 LifetimeElisionCandidate::Ignore | LifetimeElisionCandidate::Named => {
1914 LifetimeElisionCandidate::Missing(missing) => Some(missing),
1918 let mut distinct_iter = distinct.into_iter();
1919 if let Some(res) = distinct_iter.next() {
1920 match elision_lifetime {
1921 // We are the first parameter to bind lifetimes.
1923 if distinct_iter.next().is_none() {
1924 // We have a single lifetime => success.
1925 elision_lifetime = Elision::Param(res)
1927 // We have have multiple lifetimes => error.
1928 elision_lifetime = Elision::Err;
1931 // We have 2 parameters that bind lifetimes => error.
1932 Elision::Param(_) => elision_lifetime = Elision::Err,
1933 // `self` elision takes precedence over everything else.
1934 Elision::Self_(_) | Elision::Err => {}
1939 // Handle `self` specially.
1940 if index == 0 && has_self {
1941 let self_lifetime = self.find_lifetime_for_self(ty);
1942 if let Set1::One(lifetime) = self_lifetime {
1943 // We found `self` elision.
1944 elision_lifetime = Elision::Self_(lifetime);
1946 // We do not have `self` elision: disregard the `Elision::Param` that we may
1948 elision_lifetime = Elision::None;
1951 debug!("(resolving function / closure) recorded parameter");
1954 // Reinstate elision state.
1955 debug_assert_matches!(self.lifetime_elision_candidates, None);
1956 self.lifetime_elision_candidates = outer_candidates;
1958 if let Elision::Param(res) | Elision::Self_(res) = elision_lifetime {
1962 // We do not have a candidate.
1963 Err((all_candidates, parameter_info))
1966 /// List all the lifetimes that appear in the provided type.
1967 fn find_lifetime_for_self(&self, ty: &'ast Ty) -> Set1<LifetimeRes> {
1968 struct SelfVisitor<'r, 'a> {
1969 r: &'r Resolver<'a>,
1970 impl_self: Option<Res>,
1971 lifetime: Set1<LifetimeRes>,
1974 impl SelfVisitor<'_, '_> {
1975 // Look for `self: &'a Self` - also desugared from `&'a self`,
1976 // and if that matches, use it for elision and return early.
1977 fn is_self_ty(&self, ty: &Ty) -> bool {
1979 TyKind::ImplicitSelf => true,
1980 TyKind::Path(None, _) => {
1981 let path_res = self.r.partial_res_map[&ty.id].full_res();
1982 if let Some(Res::SelfTyParam { .. } | Res::SelfTyAlias { .. }) = path_res {
1985 self.impl_self.is_some() && path_res == self.impl_self
1992 impl<'a> Visitor<'a> for SelfVisitor<'_, '_> {
1993 fn visit_ty(&mut self, ty: &'a Ty) {
1994 trace!("SelfVisitor considering ty={:?}", ty);
1995 if let TyKind::Rptr(lt, ref mt) = ty.kind && self.is_self_ty(&mt.ty) {
1996 let lt_id = if let Some(lt) = lt {
1999 let res = self.r.lifetimes_res_map[&ty.id];
2000 let LifetimeRes::ElidedAnchor { start, .. } = res else { bug!() };
2003 let lt_res = self.r.lifetimes_res_map[<_id];
2004 trace!("SelfVisitor inserting res={:?}", lt_res);
2005 self.lifetime.insert(lt_res);
2007 visit::walk_ty(self, ty)
2011 let impl_self = self
2012 .diagnostic_metadata
2016 if let TyKind::Path(None, _) = ty.kind {
2017 self.r.partial_res_map.get(&ty.id)
2022 .and_then(|res| res.full_res())
2024 // Permit the types that unambiguously always
2025 // result in the same type constructor being used
2026 // (it can't differ between `Self` and `self`).
2029 Res::Def(DefKind::Struct | DefKind::Union | DefKind::Enum, _,) | Res::PrimTy(_)
2032 let mut visitor = SelfVisitor { r: self.r, impl_self, lifetime: Set1::Empty };
2033 visitor.visit_ty(ty);
2034 trace!("SelfVisitor found={:?}", visitor.lifetime);
2038 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
2039 /// label and reports an error if the label is not found or is unreachable.
2040 fn resolve_label(&mut self, mut label: Ident) -> Result<(NodeId, Span), ResolutionError<'a>> {
2041 let mut suggestion = None;
2043 for i in (0..self.label_ribs.len()).rev() {
2044 let rib = &self.label_ribs[i];
2046 if let MacroDefinition(def) = rib.kind {
2047 // If an invocation of this macro created `ident`, give up on `ident`
2048 // and switch to `ident`'s source from the macro definition.
2049 if def == self.r.macro_def(label.span.ctxt()) {
2050 label.span.remove_mark();
2054 let ident = label.normalize_to_macro_rules();
2055 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
2056 let definition_span = ident.span;
2057 return if self.is_label_valid_from_rib(i) {
2058 Ok((*id, definition_span))
2060 Err(ResolutionError::UnreachableLabel {
2068 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
2069 // the first such label that is encountered.
2070 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
2073 Err(ResolutionError::UndeclaredLabel { name: label.name, suggestion })
2076 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
2077 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
2078 let ribs = &self.label_ribs[rib_index + 1..];
2081 if rib.kind.is_label_barrier() {
2089 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
2090 debug!("resolve_adt");
2091 self.with_current_self_item(item, |this| {
2092 this.with_generic_param_rib(
2094 ItemRibKind(HasGenericParams::Yes(generics.span)),
2095 LifetimeRibKind::Generics {
2097 kind: LifetimeBinderKind::Item,
2098 span: generics.span,
2101 let item_def_id = this.r.local_def_id(item.id).to_def_id();
2104 alias_to: item_def_id,
2105 forbid_generic: false,
2106 is_trait_impl: false,
2109 visit::walk_item(this, item);
2117 fn future_proof_import(&mut self, use_tree: &UseTree) {
2118 let segments = &use_tree.prefix.segments;
2119 if !segments.is_empty() {
2120 let ident = segments[0].ident;
2121 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
2125 let nss = match use_tree.kind {
2126 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
2129 let report_error = |this: &Self, ns| {
2130 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
2131 if this.should_report_errs() {
2134 .span_err(ident.span, &format!("imports cannot refer to {}", what));
2139 match self.maybe_resolve_ident_in_lexical_scope(ident, ns) {
2140 Some(LexicalScopeBinding::Res(..)) => {
2141 report_error(self, ns);
2143 Some(LexicalScopeBinding::Item(binding)) => {
2144 if let Some(LexicalScopeBinding::Res(..)) =
2145 self.resolve_ident_in_lexical_scope(ident, ns, None, Some(binding))
2147 report_error(self, ns);
2153 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
2154 for (use_tree, _) in use_trees {
2155 self.future_proof_import(use_tree);
2160 fn resolve_item(&mut self, item: &'ast Item) {
2161 let name = item.ident.name;
2162 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
2165 ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
2166 self.with_generic_param_rib(
2168 ItemRibKind(HasGenericParams::Yes(generics.span)),
2169 LifetimeRibKind::Generics {
2171 kind: LifetimeBinderKind::Item,
2172 span: generics.span,
2174 |this| visit::walk_item(this, item),
2178 ItemKind::Fn(box Fn { ref generics, .. }) => {
2179 self.with_generic_param_rib(
2181 ItemRibKind(HasGenericParams::Yes(generics.span)),
2182 LifetimeRibKind::Generics {
2184 kind: LifetimeBinderKind::Function,
2185 span: generics.span,
2187 |this| visit::walk_item(this, item),
2191 ItemKind::Enum(_, ref generics)
2192 | ItemKind::Struct(_, ref generics)
2193 | ItemKind::Union(_, ref generics) => {
2194 self.resolve_adt(item, generics);
2197 ItemKind::Impl(box Impl {
2201 items: ref impl_items,
2204 self.diagnostic_metadata.current_impl_items = Some(impl_items);
2205 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
2206 self.diagnostic_metadata.current_impl_items = None;
2209 ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
2210 // Create a new rib for the trait-wide type parameters.
2211 self.with_generic_param_rib(
2213 ItemRibKind(HasGenericParams::Yes(generics.span)),
2214 LifetimeRibKind::Generics {
2216 kind: LifetimeBinderKind::Item,
2217 span: generics.span,
2220 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2221 this.with_self_rib(Res::SelfTyParam { trait_: local_def_id }, |this| {
2222 this.visit_generics(generics);
2223 walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);
2224 this.resolve_trait_items(items);
2230 ItemKind::TraitAlias(ref generics, ref bounds) => {
2231 // Create a new rib for the trait-wide type parameters.
2232 self.with_generic_param_rib(
2234 ItemRibKind(HasGenericParams::Yes(generics.span)),
2235 LifetimeRibKind::Generics {
2237 kind: LifetimeBinderKind::Item,
2238 span: generics.span,
2241 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2242 this.with_self_rib(Res::SelfTyParam { trait_: local_def_id }, |this| {
2243 this.visit_generics(generics);
2244 walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
2250 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
2251 self.with_scope(item.id, |this| {
2252 visit::walk_item(this, item);
2256 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
2257 self.with_static_rib(|this| {
2258 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
2261 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2262 if let Some(expr) = expr {
2263 let constant_item_kind = match item.kind {
2264 ItemKind::Const(..) => ConstantItemKind::Const,
2265 ItemKind::Static(..) => ConstantItemKind::Static,
2266 _ => unreachable!(),
2268 // We already forbid generic params because of the above item rib,
2269 // so it doesn't matter whether this is a trivial constant.
2270 this.with_constant_rib(
2272 ConstantHasGenerics::Yes,
2273 Some((item.ident, constant_item_kind)),
2274 |this| this.visit_expr(expr),
2281 ItemKind::Use(ref use_tree) => {
2282 self.future_proof_import(use_tree);
2285 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => {
2286 // do nothing, these are just around to be encoded
2289 ItemKind::GlobalAsm(_) => {
2290 visit::walk_item(self, item);
2293 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
2297 fn with_generic_param_rib<'c, F>(
2299 params: &'c [GenericParam],
2301 lifetime_kind: LifetimeRibKind,
2304 F: FnOnce(&mut Self),
2306 debug!("with_generic_param_rib");
2307 let LifetimeRibKind::Generics { binder, span: generics_span, kind: generics_kind, .. }
2308 = lifetime_kind else { panic!() };
2310 let mut function_type_rib = Rib::new(kind);
2311 let mut function_value_rib = Rib::new(kind);
2312 let mut function_lifetime_rib = LifetimeRib::new(lifetime_kind);
2313 let mut seen_bindings = FxHashMap::default();
2314 // Store all seen lifetimes names from outer scopes.
2315 let mut seen_lifetimes = FxHashSet::default();
2317 // We also can't shadow bindings from the parent item
2318 if let AssocItemRibKind = kind {
2319 let mut add_bindings_for_ns = |ns| {
2320 let parent_rib = self.ribs[ns]
2322 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
2323 .expect("associated item outside of an item");
2325 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
2327 add_bindings_for_ns(ValueNS);
2328 add_bindings_for_ns(TypeNS);
2331 // Forbid shadowing lifetime bindings
2332 for rib in self.lifetime_ribs.iter().rev() {
2333 seen_lifetimes.extend(rib.bindings.iter().map(|(ident, _)| *ident));
2334 if let LifetimeRibKind::Item = rib.kind {
2339 for param in params {
2340 let ident = param.ident.normalize_to_macros_2_0();
2341 debug!("with_generic_param_rib: {}", param.id);
2343 if let GenericParamKind::Lifetime = param.kind
2344 && let Some(&original) = seen_lifetimes.get(&ident)
2346 diagnostics::signal_lifetime_shadowing(self.r.session, original, param.ident);
2347 // Record lifetime res, so lowering knows there is something fishy.
2348 self.record_lifetime_param(param.id, LifetimeRes::Error);
2352 match seen_bindings.entry(ident) {
2353 Entry::Occupied(entry) => {
2354 let span = *entry.get();
2355 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
2356 self.report_error(param.ident.span, err);
2357 if let GenericParamKind::Lifetime = param.kind {
2358 // Record lifetime res, so lowering knows there is something fishy.
2359 self.record_lifetime_param(param.id, LifetimeRes::Error);
2363 Entry::Vacant(entry) => {
2364 entry.insert(param.ident.span);
2368 if param.ident.name == kw::UnderscoreLifetime {
2369 rustc_errors::struct_span_err!(
2373 "`'_` cannot be used here"
2375 .span_label(param.ident.span, "`'_` is a reserved lifetime name")
2377 // Record lifetime res, so lowering knows there is something fishy.
2378 self.record_lifetime_param(param.id, LifetimeRes::Error);
2382 if param.ident.name == kw::StaticLifetime {
2383 rustc_errors::struct_span_err!(
2387 "invalid lifetime parameter name: `{}`",
2390 .span_label(param.ident.span, "'static is a reserved lifetime name")
2392 // Record lifetime res, so lowering knows there is something fishy.
2393 self.record_lifetime_param(param.id, LifetimeRes::Error);
2397 let def_id = self.r.local_def_id(param.id);
2399 // Plain insert (no renaming).
2400 let (rib, def_kind) = match param.kind {
2401 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
2402 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
2403 GenericParamKind::Lifetime => {
2404 let res = LifetimeRes::Param { param: def_id, binder };
2405 self.record_lifetime_param(param.id, res);
2406 function_lifetime_rib.bindings.insert(ident, (param.id, res));
2411 let res = match kind {
2412 ItemRibKind(..) | AssocItemRibKind => Res::Def(def_kind, def_id.to_def_id()),
2413 NormalRibKind => Res::Err,
2414 _ => span_bug!(param.ident.span, "Unexpected rib kind {:?}", kind),
2416 self.r.record_partial_res(param.id, PartialRes::new(res));
2417 rib.bindings.insert(ident, res);
2420 self.lifetime_ribs.push(function_lifetime_rib);
2421 self.ribs[ValueNS].push(function_value_rib);
2422 self.ribs[TypeNS].push(function_type_rib);
2426 self.ribs[TypeNS].pop();
2427 self.ribs[ValueNS].pop();
2428 let function_lifetime_rib = self.lifetime_ribs.pop().unwrap();
2430 // Do not account for the parameters we just bound for function lifetime elision.
2431 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
2432 for (_, res) in function_lifetime_rib.bindings.values() {
2433 candidates.retain(|(r, _)| r != res);
2437 if let LifetimeBinderKind::BareFnType
2438 | LifetimeBinderKind::WhereBound
2439 | LifetimeBinderKind::Function
2440 | LifetimeBinderKind::ImplBlock = generics_kind
2442 self.maybe_report_lifetime_uses(generics_span, params)
2446 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
2447 self.label_ribs.push(Rib::new(kind));
2449 self.label_ribs.pop();
2452 fn with_static_rib(&mut self, f: impl FnOnce(&mut Self)) {
2453 let kind = ItemRibKind(HasGenericParams::No);
2454 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
2457 // HACK(min_const_generics,const_evaluatable_unchecked): We
2458 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
2459 // with a future compat lint for now. We do this by adding an
2460 // additional special case for repeat expressions.
2462 // Note that we intentionally still forbid `[0; N + 1]` during
2463 // name resolution so that we don't extend the future
2464 // compat lint to new cases.
2465 #[instrument(level = "debug", skip(self, f))]
2466 fn with_constant_rib(
2468 is_repeat: IsRepeatExpr,
2469 may_use_generics: ConstantHasGenerics,
2470 item: Option<(Ident, ConstantItemKind)>,
2471 f: impl FnOnce(&mut Self),
2473 self.with_rib(ValueNS, ConstantItemRibKind(may_use_generics, item), |this| {
2476 ConstantItemRibKind(
2477 may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes),
2481 this.with_label_rib(ConstantItemRibKind(may_use_generics, item), f);
2487 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
2488 // Handle nested impls (inside fn bodies)
2489 let previous_value =
2490 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
2491 let result = f(self);
2492 self.diagnostic_metadata.current_self_type = previous_value;
2496 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
2497 let previous_value =
2498 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
2499 let result = f(self);
2500 self.diagnostic_metadata.current_self_item = previous_value;
2504 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
2505 fn resolve_trait_items(&mut self, trait_items: &'ast [P<AssocItem>]) {
2506 let trait_assoc_items =
2507 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
2509 let walk_assoc_item =
2510 |this: &mut Self, generics: &Generics, kind, item: &'ast AssocItem| {
2511 this.with_generic_param_rib(
2514 LifetimeRibKind::Generics { binder: item.id, span: generics.span, kind },
2515 |this| visit::walk_assoc_item(this, item, AssocCtxt::Trait),
2519 for item in trait_items {
2521 AssocItemKind::Const(_, ty, default) => {
2523 // Only impose the restrictions of `ConstRibKind` for an
2524 // actual constant expression in a provided default.
2525 if let Some(expr) = default {
2526 // We allow arbitrary const expressions inside of associated consts,
2527 // even if they are potentially not const evaluatable.
2529 // Type parameters can already be used and as associated consts are
2530 // not used as part of the type system, this is far less surprising.
2531 self.with_lifetime_rib(
2532 LifetimeRibKind::Elided(LifetimeRes::Infer),
2534 this.with_constant_rib(
2536 ConstantHasGenerics::Yes,
2538 |this| this.visit_expr(expr),
2544 AssocItemKind::Fn(box Fn { generics, .. }) => {
2545 walk_assoc_item(self, generics, LifetimeBinderKind::Function, item);
2547 AssocItemKind::Type(box TyAlias { generics, .. }) => self
2548 .with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2549 walk_assoc_item(this, generics, LifetimeBinderKind::Item, item)
2551 AssocItemKind::MacCall(_) => {
2552 panic!("unexpanded macro in resolve!")
2557 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
2560 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
2561 fn with_optional_trait_ref<T>(
2563 opt_trait_ref: Option<&TraitRef>,
2564 self_type: &'ast Ty,
2565 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
2567 let mut new_val = None;
2568 let mut new_id = None;
2569 if let Some(trait_ref) = opt_trait_ref {
2570 let path: Vec<_> = Segment::from_path(&trait_ref.path);
2571 self.diagnostic_metadata.currently_processing_impl_trait =
2572 Some((trait_ref.clone(), self_type.clone()));
2573 let res = self.smart_resolve_path_fragment(
2576 PathSource::Trait(AliasPossibility::No),
2577 Finalize::new(trait_ref.ref_id, trait_ref.path.span),
2579 self.diagnostic_metadata.currently_processing_impl_trait = None;
2580 if let Some(def_id) = res.expect_full_res().opt_def_id() {
2581 new_id = Some(def_id);
2582 new_val = Some((self.r.expect_module(def_id), trait_ref.clone()));
2585 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
2586 let result = f(self, new_id);
2587 self.current_trait_ref = original_trait_ref;
2591 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
2592 let mut self_type_rib = Rib::new(NormalRibKind);
2594 // Plain insert (no renaming, since types are not currently hygienic)
2595 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
2596 self.ribs[ns].push(self_type_rib);
2598 self.ribs[ns].pop();
2601 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
2602 self.with_self_rib_ns(TypeNS, self_res, f)
2605 fn resolve_implementation(
2607 generics: &'ast Generics,
2608 opt_trait_reference: &'ast Option<TraitRef>,
2609 self_type: &'ast Ty,
2611 impl_items: &'ast [P<AssocItem>],
2613 debug!("resolve_implementation");
2614 // If applicable, create a rib for the type parameters.
2615 self.with_generic_param_rib(
2617 ItemRibKind(HasGenericParams::Yes(generics.span)),
2618 LifetimeRibKind::Generics {
2619 span: generics.span,
2621 kind: LifetimeBinderKind::ImplBlock,
2624 // Dummy self type for better errors if `Self` is used in the trait path.
2625 this.with_self_rib(Res::SelfTyParam { trait_: LOCAL_CRATE.as_def_id() }, |this| {
2626 this.with_lifetime_rib(
2627 LifetimeRibKind::AnonymousCreateParameter {
2629 report_in_path: true
2632 // Resolve the trait reference, if necessary.
2633 this.with_optional_trait_ref(
2634 opt_trait_reference.as_ref(),
2637 let item_def_id = this.r.local_def_id(item_id);
2639 // Register the trait definitions from here.
2640 if let Some(trait_id) = trait_id {
2648 let item_def_id = item_def_id.to_def_id();
2649 let res = Res::SelfTyAlias {
2650 alias_to: item_def_id,
2651 forbid_generic: false,
2652 is_trait_impl: trait_id.is_some()
2654 this.with_self_rib(res, |this| {
2655 if let Some(trait_ref) = opt_trait_reference.as_ref() {
2656 // Resolve type arguments in the trait path.
2657 visit::walk_trait_ref(this, trait_ref);
2659 // Resolve the self type.
2660 this.visit_ty(self_type);
2661 // Resolve the generic parameters.
2662 this.visit_generics(generics);
2664 // Resolve the items within the impl.
2665 this.with_current_self_type(self_type, |this| {
2666 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
2667 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
2668 let mut seen_trait_items = Default::default();
2669 for item in impl_items {
2670 this.resolve_impl_item(&**item, &mut seen_trait_items);
2684 fn resolve_impl_item(
2686 item: &'ast AssocItem,
2687 seen_trait_items: &mut FxHashMap<DefId, Span>,
2689 use crate::ResolutionError::*;
2691 AssocItemKind::Const(_, ty, default) => {
2692 debug!("resolve_implementation AssocItemKind::Const");
2693 // If this is a trait impl, ensure the const
2695 self.check_trait_item(
2702 |i, s, c| ConstNotMemberOfTrait(i, s, c),
2706 if let Some(expr) = default {
2707 // We allow arbitrary const expressions inside of associated consts,
2708 // even if they are potentially not const evaluatable.
2710 // Type parameters can already be used and as associated consts are
2711 // not used as part of the type system, this is far less surprising.
2712 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2713 this.with_constant_rib(
2715 ConstantHasGenerics::Yes,
2717 |this| this.visit_expr(expr),
2722 AssocItemKind::Fn(box Fn { generics, .. }) => {
2723 debug!("resolve_implementation AssocItemKind::Fn");
2724 // We also need a new scope for the impl item type parameters.
2725 self.with_generic_param_rib(
2728 LifetimeRibKind::Generics {
2730 span: generics.span,
2731 kind: LifetimeBinderKind::Function,
2734 // If this is a trait impl, ensure the method
2736 this.check_trait_item(
2743 |i, s, c| MethodNotMemberOfTrait(i, s, c),
2746 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2750 AssocItemKind::Type(box TyAlias { generics, .. }) => {
2751 debug!("resolve_implementation AssocItemKind::Type");
2752 // We also need a new scope for the impl item type parameters.
2753 self.with_generic_param_rib(
2756 LifetimeRibKind::Generics {
2758 span: generics.span,
2759 kind: LifetimeBinderKind::Item,
2762 this.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2763 // If this is a trait impl, ensure the type
2765 this.check_trait_item(
2772 |i, s, c| TypeNotMemberOfTrait(i, s, c),
2775 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2780 AssocItemKind::MacCall(_) => {
2781 panic!("unexpanded macro in resolve!")
2786 fn check_trait_item<F>(
2790 kind: &AssocItemKind,
2793 seen_trait_items: &mut FxHashMap<DefId, Span>,
2796 F: FnOnce(Ident, String, Option<Symbol>) -> ResolutionError<'a>,
2798 // If there is a TraitRef in scope for an impl, then the method must be in the trait.
2799 let Some((module, _)) = &self.current_trait_ref else { return; };
2800 ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
2801 let key = self.r.new_key(ident, ns);
2802 let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2804 if binding.is_none() {
2805 // We could not find the trait item in the correct namespace.
2806 // Check the other namespace to report an error.
2812 let key = self.r.new_key(ident, ns);
2813 binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2816 let Some(binding) = binding else {
2817 // We could not find the method: report an error.
2818 let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
2819 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2820 let path_names = path_names_to_string(path);
2821 self.report_error(span, err(ident, path_names, candidate));
2825 let res = binding.res();
2826 let Res::Def(def_kind, id_in_trait) = res else { bug!() };
2828 match seen_trait_items.entry(id_in_trait) {
2829 Entry::Occupied(entry) => {
2832 ResolutionError::TraitImplDuplicate {
2834 old_span: *entry.get(),
2835 trait_item_span: binding.span,
2840 Entry::Vacant(entry) => {
2845 match (def_kind, kind) {
2846 (DefKind::AssocTy, AssocItemKind::Type(..))
2847 | (DefKind::AssocFn, AssocItemKind::Fn(..))
2848 | (DefKind::AssocConst, AssocItemKind::Const(..)) => {
2849 self.r.record_partial_res(id, PartialRes::new(res));
2855 // The method kind does not correspond to what appeared in the trait, report.
2856 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2857 let (code, kind) = match kind {
2858 AssocItemKind::Const(..) => (rustc_errors::error_code!(E0323), "const"),
2859 AssocItemKind::Fn(..) => (rustc_errors::error_code!(E0324), "method"),
2860 AssocItemKind::Type(..) => (rustc_errors::error_code!(E0325), "type"),
2861 AssocItemKind::MacCall(..) => span_bug!(span, "unexpanded macro"),
2863 let trait_path = path_names_to_string(path);
2866 ResolutionError::TraitImplMismatch {
2871 trait_item_span: binding.span,
2876 fn resolve_params(&mut self, params: &'ast [Param]) {
2877 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2878 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2879 for Param { pat, .. } in params {
2880 this.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
2883 for Param { ty, .. } in params {
2888 fn resolve_local(&mut self, local: &'ast Local) {
2889 debug!("resolving local ({:?})", local);
2890 // Resolve the type.
2891 walk_list!(self, visit_ty, &local.ty);
2893 // Resolve the initializer.
2894 if let Some((init, els)) = local.kind.init_else_opt() {
2895 self.visit_expr(init);
2897 // Resolve the `else` block
2898 if let Some(els) = els {
2899 self.visit_block(els);
2903 // Resolve the pattern.
2904 self.resolve_pattern_top(&local.pat, PatternSource::Let);
2907 /// build a map from pattern identifiers to binding-info's.
2908 /// this is done hygienically. This could arise for a macro
2909 /// that expands into an or-pattern where one 'x' was from the
2910 /// user and one 'x' came from the macro.
2911 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2912 let mut binding_map = FxHashMap::default();
2914 pat.walk(&mut |pat| {
2916 PatKind::Ident(annotation, ident, ref sub_pat)
2917 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
2919 binding_map.insert(ident, BindingInfo { span: ident.span, annotation });
2921 PatKind::Or(ref ps) => {
2922 // Check the consistency of this or-pattern and
2923 // then add all bindings to the larger map.
2924 for bm in self.check_consistent_bindings(ps) {
2925 binding_map.extend(bm);
2938 fn is_base_res_local(&self, nid: NodeId) -> bool {
2940 self.r.partial_res_map.get(&nid).map(|res| res.expect_full_res()),
2941 Some(Res::Local(..))
2945 /// Checks that all of the arms in an or-pattern have exactly the
2946 /// same set of bindings, with the same binding modes for each.
2947 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
2948 let mut missing_vars = FxHashMap::default();
2949 let mut inconsistent_vars = FxHashMap::default();
2951 // 1) Compute the binding maps of all arms.
2952 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
2954 // 2) Record any missing bindings or binding mode inconsistencies.
2955 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
2956 // Check against all arms except for the same pattern which is always self-consistent.
2960 .filter(|(_, pat)| pat.id != pat_outer.id)
2961 .flat_map(|(idx, _)| maps[idx].iter())
2962 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
2964 for (name, info, &binding_inner) in inners {
2967 // The inner binding is missing in the outer.
2969 missing_vars.entry(name).or_insert_with(|| BindingError {
2971 origin: BTreeSet::new(),
2972 target: BTreeSet::new(),
2973 could_be_path: name.as_str().starts_with(char::is_uppercase),
2975 binding_error.origin.insert(binding_inner.span);
2976 binding_error.target.insert(pat_outer.span);
2978 Some(binding_outer) => {
2979 if binding_outer.annotation != binding_inner.annotation {
2980 // The binding modes in the outer and inner bindings differ.
2983 .or_insert((binding_inner.span, binding_outer.span));
2990 // 3) Report all missing variables we found.
2991 let mut missing_vars = missing_vars.into_iter().collect::<Vec<_>>();
2992 missing_vars.sort_by_key(|&(sym, ref _err)| sym);
2994 for (name, mut v) in missing_vars.into_iter() {
2995 if inconsistent_vars.contains_key(&name) {
2996 v.could_be_path = false;
2999 *v.origin.iter().next().unwrap(),
3000 ResolutionError::VariableNotBoundInPattern(v, self.parent_scope),
3004 // 4) Report all inconsistencies in binding modes we found.
3005 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
3006 inconsistent_vars.sort();
3007 for (name, v) in inconsistent_vars {
3008 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
3011 // 5) Finally bubble up all the binding maps.
3015 /// Check the consistency of the outermost or-patterns.
3016 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
3017 pat.walk(&mut |pat| match pat.kind {
3018 PatKind::Or(ref ps) => {
3019 self.check_consistent_bindings(ps);
3026 fn resolve_arm(&mut self, arm: &'ast Arm) {
3027 self.with_rib(ValueNS, NormalRibKind, |this| {
3028 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
3029 walk_list!(this, visit_expr, &arm.guard);
3030 this.visit_expr(&arm.body);
3034 /// Arising from `source`, resolve a top level pattern.
3035 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
3036 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
3037 self.resolve_pattern(pat, pat_src, &mut bindings);
3043 pat_src: PatternSource,
3044 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3046 // We walk the pattern before declaring the pattern's inner bindings,
3047 // so that we avoid resolving a literal expression to a binding defined
3049 visit::walk_pat(self, pat);
3050 self.resolve_pattern_inner(pat, pat_src, bindings);
3051 // This has to happen *after* we determine which pat_idents are variants:
3052 self.check_consistent_bindings_top(pat);
3055 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
3059 /// A stack of sets of bindings accumulated.
3061 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
3062 /// be interpreted as re-binding an already bound binding. This results in an error.
3063 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
3064 /// in reusing this binding rather than creating a fresh one.
3066 /// When called at the top level, the stack must have a single element
3067 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
3068 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
3069 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
3070 /// When each `p_i` has been dealt with, the top set is merged with its parent.
3071 /// When a whole or-pattern has been dealt with, the thing happens.
3073 /// See the implementation and `fresh_binding` for more details.
3074 fn resolve_pattern_inner(
3077 pat_src: PatternSource,
3078 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3080 // Visit all direct subpatterns of this pattern.
3081 pat.walk(&mut |pat| {
3082 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
3084 PatKind::Ident(bmode, ident, ref sub) => {
3085 // First try to resolve the identifier as some existing entity,
3086 // then fall back to a fresh binding.
3087 let has_sub = sub.is_some();
3089 .try_resolve_as_non_binding(pat_src, bmode, ident, has_sub)
3090 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
3091 self.r.record_partial_res(pat.id, PartialRes::new(res));
3092 self.r.record_pat_span(pat.id, pat.span);
3094 PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
3095 self.smart_resolve_path(
3099 PathSource::TupleStruct(
3101 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
3105 PatKind::Path(ref qself, ref path) => {
3106 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
3108 PatKind::Struct(ref qself, ref path, ..) => {
3109 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Struct);
3111 PatKind::Or(ref ps) => {
3112 // Add a new set of bindings to the stack. `Or` here records that when a
3113 // binding already exists in this set, it should not result in an error because
3114 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
3115 bindings.push((PatBoundCtx::Or, Default::default()));
3117 // Now we need to switch back to a product context so that each
3118 // part of the or-pattern internally rejects already bound names.
3119 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
3120 bindings.push((PatBoundCtx::Product, Default::default()));
3121 self.resolve_pattern_inner(p, pat_src, bindings);
3122 // Move up the non-overlapping bindings to the or-pattern.
3123 // Existing bindings just get "merged".
3124 let collected = bindings.pop().unwrap().1;
3125 bindings.last_mut().unwrap().1.extend(collected);
3127 // This or-pattern itself can itself be part of a product,
3128 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
3129 // Both cases bind `a` again in a product pattern and must be rejected.
3130 let collected = bindings.pop().unwrap().1;
3131 bindings.last_mut().unwrap().1.extend(collected);
3133 // Prevent visiting `ps` as we've already done so above.
3146 pat_src: PatternSource,
3147 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3149 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
3150 // (We must not add it if it's in the bindings map because that breaks the assumptions
3151 // later passes make about or-patterns.)
3152 let ident = ident.normalize_to_macro_rules();
3154 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
3155 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
3156 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
3157 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
3158 // This is *required* for consistency which is checked later.
3159 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
3161 if already_bound_and {
3162 // Overlap in a product pattern somewhere; report an error.
3163 use ResolutionError::*;
3164 let error = match pat_src {
3165 // `fn f(a: u8, a: u8)`:
3166 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
3168 _ => IdentifierBoundMoreThanOnceInSamePattern,
3170 self.report_error(ident.span, error(ident.name));
3173 // Record as bound if it's valid:
3174 let ident_valid = ident.name != kw::Empty;
3176 bindings.last_mut().unwrap().1.insert(ident);
3179 if already_bound_or {
3180 // `Variant1(a) | Variant2(a)`, ok
3181 // Reuse definition from the first `a`.
3182 self.innermost_rib_bindings(ValueNS)[&ident]
3184 let res = Res::Local(pat_id);
3186 // A completely fresh binding add to the set if it's valid.
3187 self.innermost_rib_bindings(ValueNS).insert(ident, res);
3193 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
3194 &mut self.ribs[ns].last_mut().unwrap().bindings
3197 fn try_resolve_as_non_binding(
3199 pat_src: PatternSource,
3200 ann: BindingAnnotation,
3204 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
3205 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
3206 // also be interpreted as a path to e.g. a constant, variant, etc.
3207 let is_syntactic_ambiguity = !has_sub && ann == BindingAnnotation::NONE;
3209 let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?;
3210 let (res, binding) = match ls_binding {
3211 LexicalScopeBinding::Item(binding)
3212 if is_syntactic_ambiguity && binding.is_ambiguity() =>
3214 // For ambiguous bindings we don't know all their definitions and cannot check
3215 // whether they can be shadowed by fresh bindings or not, so force an error.
3216 // issues/33118#issuecomment-233962221 (see below) still applies here,
3217 // but we have to ignore it for backward compatibility.
3218 self.r.record_use(ident, binding, false);
3221 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
3222 LexicalScopeBinding::Res(res) => (res, None),
3226 Res::SelfCtor(_) // See #70549.
3228 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
3230 ) if is_syntactic_ambiguity => {
3231 // Disambiguate in favor of a unit struct/variant or constant pattern.
3232 if let Some(binding) = binding {
3233 self.r.record_use(ident, binding, false);
3237 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static(_), _) => {
3238 // This is unambiguously a fresh binding, either syntactically
3239 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
3240 // to something unusable as a pattern (e.g., constructor function),
3241 // but we still conservatively report an error, see
3242 // issues/33118#issuecomment-233962221 for one reason why.
3243 let binding = binding.expect("no binding for a ctor or static");
3246 ResolutionError::BindingShadowsSomethingUnacceptable {
3247 shadowing_binding: pat_src,
3249 participle: if binding.is_import() { "imported" } else { "defined" },
3250 article: binding.res().article(),
3251 shadowed_binding: binding.res(),
3252 shadowed_binding_span: binding.span,
3257 Res::Def(DefKind::ConstParam, def_id) => {
3258 // Same as for DefKind::Const above, but here, `binding` is `None`, so we
3259 // have to construct the error differently
3262 ResolutionError::BindingShadowsSomethingUnacceptable {
3263 shadowing_binding: pat_src,
3265 participle: "defined",
3266 article: res.article(),
3267 shadowed_binding: res,
3268 shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"),
3273 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
3274 // These entities are explicitly allowed to be shadowed by fresh bindings.
3277 Res::SelfCtor(_) => {
3278 // We resolve `Self` in pattern position as an ident sometimes during recovery,
3279 // so delay a bug instead of ICEing.
3280 self.r.session.delay_span_bug(
3282 "unexpected `SelfCtor` in pattern, expected identifier"
3288 "unexpected resolution for an identifier in pattern: {:?}",
3294 // High-level and context dependent path resolution routine.
3295 // Resolves the path and records the resolution into definition map.
3296 // If resolution fails tries several techniques to find likely
3297 // resolution candidates, suggest imports or other help, and report
3298 // errors in user friendly way.
3299 fn smart_resolve_path(
3302 qself: Option<&QSelf>,
3304 source: PathSource<'ast>,
3306 self.smart_resolve_path_fragment(
3308 &Segment::from_path(path),
3310 Finalize::new(id, path.span),
3314 fn smart_resolve_path_fragment(
3316 qself: Option<&QSelf>,
3318 source: PathSource<'ast>,
3322 "smart_resolve_path_fragment(qself={:?}, path={:?}, finalize={:?})",
3323 qself, path, finalize,
3325 let ns = source.namespace();
3327 let Finalize { node_id, path_span, .. } = finalize;
3328 let report_errors = |this: &mut Self, res: Option<Res>| {
3329 if this.should_report_errs() {
3330 let (err, candidates) =
3331 this.smart_resolve_report_errors(path, path_span, source, res);
3333 let def_id = this.parent_scope.module.nearest_parent_mod();
3334 let instead = res.is_some();
3336 if res.is_none() { this.report_missing_type_error(path) } else { None };
3338 this.r.use_injections.push(UseError {
3345 is_call: source.is_call(),
3349 PartialRes::new(Res::Err)
3352 // For paths originating from calls (like in `HashMap::new()`), tries
3353 // to enrich the plain `failed to resolve: ...` message with hints
3354 // about possible missing imports.
3356 // Similar thing, for types, happens in `report_errors` above.
3357 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
3358 if !source.is_call() {
3359 return Some(parent_err);
3362 // Before we start looking for candidates, we have to get our hands
3363 // on the type user is trying to perform invocation on; basically:
3364 // we're transforming `HashMap::new` into just `HashMap`.
3365 let path = match path.split_last() {
3366 Some((_, path)) if !path.is_empty() => path,
3367 _ => return Some(parent_err),
3370 let (mut err, candidates) =
3371 this.smart_resolve_report_errors(path, path_span, PathSource::Type, None);
3373 // There are two different error messages user might receive at
3375 // - E0412 cannot find type `{}` in this scope
3376 // - E0433 failed to resolve: use of undeclared type or module `{}`
3378 // The first one is emitted for paths in type-position, and the
3379 // latter one - for paths in expression-position.
3381 // Thus (since we're in expression-position at this point), not to
3382 // confuse the user, we want to keep the *message* from E0433 (so
3383 // `parent_err`), but we want *hints* from E0412 (so `err`).
3385 // And that's what happens below - we're just mixing both messages
3386 // into a single one.
3387 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
3389 // overwrite all properties with the parent's error message
3390 err.message = take(&mut parent_err.message);
3391 err.code = take(&mut parent_err.code);
3392 swap(&mut err.span, &mut parent_err.span);
3393 err.children = take(&mut parent_err.children);
3394 err.sort_span = parent_err.sort_span;
3395 err.is_lint = parent_err.is_lint;
3397 // merge the parent's suggestions with the typo suggestions
3398 fn append_result<T, E>(res1: &mut Result<Vec<T>, E>, res2: Result<Vec<T>, E>) {
3400 Ok(vec1) => match res2 {
3401 Ok(mut vec2) => vec1.append(&mut vec2),
3402 Err(e) => *res1 = Err(e),
3407 append_result(&mut err.suggestions, parent_err.suggestions.clone());
3409 parent_err.cancel();
3411 let def_id = this.parent_scope.module.nearest_parent_mod();
3413 if this.should_report_errs() {
3414 if candidates.is_empty() {
3415 // When there is no suggested imports, we can just emit the error
3416 // and suggestions immediately. Note that we bypass the usually error
3417 // reporting routine (ie via `self.r.report_error`) because we need
3418 // to post-process the `ResolutionError` above.
3421 // If there are suggested imports, the error reporting is delayed
3422 this.r.use_injections.push(UseError {
3429 is_call: source.is_call(),
3436 // We don't return `Some(parent_err)` here, because the error will
3437 // be already printed either immediately or as part of the `use` injections
3441 let partial_res = match self.resolve_qpath_anywhere(
3446 source.defer_to_typeck(),
3449 Ok(Some(partial_res)) if let Some(res) = partial_res.full_res() => {
3450 if source.is_expected(res) || res == Res::Err {
3453 report_errors(self, Some(res))
3457 Ok(Some(partial_res)) if source.defer_to_typeck() => {
3458 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
3459 // or `<T>::A::B`. If `B` should be resolved in value namespace then
3460 // it needs to be added to the trait map.
3462 let item_name = path.last().unwrap().ident;
3463 let traits = self.traits_in_scope(item_name, ns);
3464 self.r.trait_map.insert(node_id, traits);
3467 if PrimTy::from_name(path[0].ident.name).is_some() {
3468 let mut std_path = Vec::with_capacity(1 + path.len());
3470 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
3471 std_path.extend(path);
3472 if let PathResult::Module(_) | PathResult::NonModule(_) =
3473 self.resolve_path(&std_path, Some(ns), None)
3475 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
3477 path.iter().last().map_or(path_span, |segment| segment.ident.span);
3479 self.r.confused_type_with_std_module.insert(item_span, path_span);
3480 self.r.confused_type_with_std_module.insert(path_span, path_span);
3488 if let Some(err) = report_errors_for_call(self, err) {
3489 self.report_error(err.span, err.node);
3492 PartialRes::new(Res::Err)
3495 _ => report_errors(self, None),
3498 if !matches!(source, PathSource::TraitItem(..)) {
3499 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
3500 self.r.record_partial_res(node_id, partial_res);
3501 self.resolve_elided_lifetimes_in_path(node_id, partial_res, path, source, path_span);
3507 fn self_type_is_available(&mut self) -> bool {
3509 .maybe_resolve_ident_in_lexical_scope(Ident::with_dummy_span(kw::SelfUpper), TypeNS);
3510 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3513 fn self_value_is_available(&mut self, self_span: Span) -> bool {
3514 let ident = Ident::new(kw::SelfLower, self_span);
3515 let binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS);
3516 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3519 /// A wrapper around [`Resolver::report_error`].
3521 /// This doesn't emit errors for function bodies if this is rustdoc.
3522 fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) {
3523 if self.should_report_errs() {
3524 self.r.report_error(span, resolution_error);
3529 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
3530 fn should_report_errs(&self) -> bool {
3531 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
3534 // Resolve in alternative namespaces if resolution in the primary namespace fails.
3535 fn resolve_qpath_anywhere(
3537 qself: Option<&QSelf>,
3539 primary_ns: Namespace,
3541 defer_to_typeck: bool,
3543 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3544 let mut fin_res = None;
3546 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
3547 if i == 0 || ns != primary_ns {
3548 match self.resolve_qpath(qself, path, ns, finalize)? {
3550 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
3552 return Ok(Some(partial_res));
3555 if fin_res.is_none() {
3556 fin_res = partial_res;
3563 assert!(primary_ns != MacroNS);
3565 if qself.is_none() {
3566 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
3567 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
3568 if let Ok((_, res)) =
3569 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
3571 return Ok(Some(PartialRes::new(res)));
3578 /// Handles paths that may refer to associated items.
3581 qself: Option<&QSelf>,
3585 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3587 "resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})",
3588 qself, path, ns, finalize,
3591 if let Some(qself) = qself {
3592 if qself.position == 0 {
3593 // This is a case like `<T>::B`, where there is no
3594 // trait to resolve. In that case, we leave the `B`
3595 // segment to be resolved by type-check.
3596 return Ok(Some(PartialRes::with_unresolved_segments(
3597 Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()),
3602 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
3604 // Currently, `path` names the full item (`A::B::C`, in
3605 // our example). so we extract the prefix of that that is
3606 // the trait (the slice upto and including
3607 // `qself.position`). And then we recursively resolve that,
3608 // but with `qself` set to `None`.
3609 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
3610 let partial_res = self.smart_resolve_path_fragment(
3612 &path[..=qself.position],
3613 PathSource::TraitItem(ns),
3614 Finalize::with_root_span(finalize.node_id, finalize.path_span, qself.path_span),
3617 // The remaining segments (the `C` in our example) will
3618 // have to be resolved by type-check, since that requires doing
3619 // trait resolution.
3620 return Ok(Some(PartialRes::with_unresolved_segments(
3621 partial_res.base_res(),
3622 partial_res.unresolved_segments() + path.len() - qself.position - 1,
3626 let result = match self.resolve_path(&path, Some(ns), Some(finalize)) {
3627 PathResult::NonModule(path_res) => path_res,
3628 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
3629 PartialRes::new(module.res().unwrap())
3631 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
3632 // don't report an error right away, but try to fallback to a primitive type.
3633 // So, we are still able to successfully resolve something like
3635 // use std::u8; // bring module u8 in scope
3636 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
3637 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
3638 // // not to non-existent std::u8::max_value
3641 // Such behavior is required for backward compatibility.
3642 // The same fallback is used when `a` resolves to nothing.
3643 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
3644 if (ns == TypeNS || path.len() > 1)
3645 && PrimTy::from_name(path[0].ident.name).is_some() =>
3647 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
3648 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
3650 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3651 PartialRes::new(module.res().unwrap())
3653 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
3654 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
3656 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
3657 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
3661 && let Some(res) = result.full_res()
3663 && path[0].ident.name != kw::PathRoot
3664 && path[0].ident.name != kw::DollarCrate
3666 let unqualified_result = {
3667 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
3668 PathResult::NonModule(path_res) => path_res.expect_full_res(),
3669 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3670 module.res().unwrap()
3672 _ => return Ok(Some(result)),
3675 if res == unqualified_result {
3676 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
3677 self.r.lint_buffer.buffer_lint(
3681 "unnecessary qualification",
3689 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
3690 if let Some(label) = label {
3691 if label.ident.as_str().as_bytes()[1] != b'_' {
3692 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
3695 if let Ok((_, orig_span)) = self.resolve_label(label.ident) {
3696 diagnostics::signal_label_shadowing(self.r.session, orig_span, label.ident)
3699 self.with_label_rib(NormalRibKind, |this| {
3700 let ident = label.ident.normalize_to_macro_rules();
3701 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
3709 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
3710 self.with_resolved_label(label, id, |this| this.visit_block(block));
3713 fn resolve_block(&mut self, block: &'ast Block) {
3714 debug!("(resolving block) entering block");
3715 // Move down in the graph, if there's an anonymous module rooted here.
3716 let orig_module = self.parent_scope.module;
3717 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
3719 let mut num_macro_definition_ribs = 0;
3720 if let Some(anonymous_module) = anonymous_module {
3721 debug!("(resolving block) found anonymous module, moving down");
3722 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3723 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3724 self.parent_scope.module = anonymous_module;
3726 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3729 let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
3730 if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
3731 (block.could_be_bare_literal, &block.stmts[..])
3732 && let ExprKind::Type(..) = expr.kind
3734 self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
3737 // Descend into the block.
3738 for stmt in &block.stmts {
3739 if let StmtKind::Item(ref item) = stmt.kind
3740 && let ItemKind::MacroDef(..) = item.kind {
3741 num_macro_definition_ribs += 1;
3742 let res = self.r.local_def_id(item.id).to_def_id();
3743 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
3744 self.label_ribs.push(Rib::new(MacroDefinition(res)));
3747 self.visit_stmt(stmt);
3749 self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
3752 self.parent_scope.module = orig_module;
3753 for _ in 0..num_macro_definition_ribs {
3754 self.ribs[ValueNS].pop();
3755 self.label_ribs.pop();
3757 self.ribs[ValueNS].pop();
3758 if anonymous_module.is_some() {
3759 self.ribs[TypeNS].pop();
3761 debug!("(resolving block) leaving block");
3764 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
3765 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
3766 self.with_constant_rib(
3768 if constant.value.is_potential_trivial_const_param() {
3769 ConstantHasGenerics::Yes
3771 ConstantHasGenerics::No
3774 |this| visit::walk_anon_const(this, constant),
3778 fn resolve_inline_const(&mut self, constant: &'ast AnonConst) {
3779 debug!("resolve_anon_const {constant:?}");
3780 self.with_constant_rib(IsRepeatExpr::No, ConstantHasGenerics::Yes, None, |this| {
3781 visit::walk_anon_const(this, constant)
3785 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
3786 // First, record candidate traits for this expression if it could
3787 // result in the invocation of a method call.
3789 self.record_candidate_traits_for_expr_if_necessary(expr);
3791 // Next, resolve the node.
3793 ExprKind::Path(ref qself, ref path) => {
3794 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
3795 visit::walk_expr(self, expr);
3798 ExprKind::Struct(ref se) => {
3799 self.smart_resolve_path(expr.id, se.qself.as_ref(), &se.path, PathSource::Struct);
3800 visit::walk_expr(self, expr);
3803 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
3804 match self.resolve_label(label.ident) {
3805 Ok((node_id, _)) => {
3806 // Since this res is a label, it is never read.
3807 self.r.label_res_map.insert(expr.id, node_id);
3808 self.diagnostic_metadata.unused_labels.remove(&node_id);
3811 self.report_error(label.ident.span, error);
3815 // visit `break` argument if any
3816 visit::walk_expr(self, expr);
3819 ExprKind::Break(None, Some(ref e)) => {
3820 // We use this instead of `visit::walk_expr` to keep the parent expr around for
3821 // better diagnostics.
3822 self.resolve_expr(e, Some(&expr));
3825 ExprKind::Let(ref pat, ref scrutinee, _) => {
3826 self.visit_expr(scrutinee);
3827 self.resolve_pattern_top(pat, PatternSource::Let);
3830 ExprKind::If(ref cond, ref then, ref opt_else) => {
3831 self.with_rib(ValueNS, NormalRibKind, |this| {
3832 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3833 this.visit_expr(cond);
3834 this.diagnostic_metadata.in_if_condition = old;
3835 this.visit_block(then);
3837 if let Some(expr) = opt_else {
3838 self.visit_expr(expr);
3842 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3844 ExprKind::While(ref cond, ref block, label) => {
3845 self.with_resolved_label(label, expr.id, |this| {
3846 this.with_rib(ValueNS, NormalRibKind, |this| {
3847 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3848 this.visit_expr(cond);
3849 this.diagnostic_metadata.in_if_condition = old;
3850 this.visit_block(block);
3855 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
3856 self.visit_expr(iter_expr);
3857 self.with_rib(ValueNS, NormalRibKind, |this| {
3858 this.resolve_pattern_top(pat, PatternSource::For);
3859 this.resolve_labeled_block(label, expr.id, block);
3863 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
3865 // Equivalent to `visit::walk_expr` + passing some context to children.
3866 ExprKind::Field(ref subexpression, _) => {
3867 self.resolve_expr(subexpression, Some(expr));
3869 ExprKind::MethodCall(ref segment, ref receiver, ref arguments, _) => {
3870 self.resolve_expr(receiver, Some(expr));
3871 for argument in arguments {
3872 self.resolve_expr(argument, None);
3874 self.visit_path_segment(segment);
3877 ExprKind::Call(ref callee, ref arguments) => {
3878 self.resolve_expr(callee, Some(expr));
3879 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
3880 for (idx, argument) in arguments.iter().enumerate() {
3881 // Constant arguments need to be treated as AnonConst since
3882 // that is how they will be later lowered to HIR.
3883 if const_args.contains(&idx) {
3884 self.with_constant_rib(
3886 if argument.is_potential_trivial_const_param() {
3887 ConstantHasGenerics::Yes
3889 ConstantHasGenerics::No
3893 this.resolve_expr(argument, None);
3897 self.resolve_expr(argument, None);
3901 ExprKind::Type(ref type_expr, ref ty) => {
3902 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
3903 // type ascription. Here we are trying to retrieve the span of the colon token as
3904 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
3905 // with `expr::Ty`, only in this case it will match the span from
3906 // `type_ascription_path_suggestions`.
3907 self.diagnostic_metadata
3908 .current_type_ascription
3909 .push(type_expr.span.between(ty.span));
3910 visit::walk_expr(self, expr);
3911 self.diagnostic_metadata.current_type_ascription.pop();
3913 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
3914 // resolve the arguments within the proper scopes so that usages of them inside the
3915 // closure are detected as upvars rather than normal closure arg usages.
3916 ExprKind::Closure(_, _, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
3917 self.with_rib(ValueNS, NormalRibKind, |this| {
3918 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
3919 // Resolve arguments:
3920 this.resolve_params(&fn_decl.inputs);
3921 // No need to resolve return type --
3922 // the outer closure return type is `FnRetTy::Default`.
3924 // Now resolve the inner closure
3926 // No need to resolve arguments: the inner closure has none.
3927 // Resolve the return type:
3928 visit::walk_fn_ret_ty(this, &fn_decl.output);
3930 this.visit_expr(body);
3935 // For closures, ClosureOrAsyncRibKind is added in visit_fn
3936 ExprKind::Closure(ClosureBinder::For { ref generic_params, span }, ..) => {
3937 self.with_generic_param_rib(
3940 LifetimeRibKind::Generics {
3942 kind: LifetimeBinderKind::Closure,
3945 |this| visit::walk_expr(this, expr),
3948 ExprKind::Closure(..) => visit::walk_expr(self, expr),
3949 ExprKind::Async(..) => {
3950 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
3952 ExprKind::Repeat(ref elem, ref ct) => {
3953 self.visit_expr(elem);
3954 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
3955 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
3956 this.resolve_anon_const(ct, IsRepeatExpr::Yes)
3960 ExprKind::ConstBlock(ref ct) => {
3961 self.resolve_inline_const(ct);
3963 ExprKind::Index(ref elem, ref idx) => {
3964 self.resolve_expr(elem, Some(expr));
3965 self.visit_expr(idx);
3967 ExprKind::Assign(ref lhs, ref rhs, _) => {
3968 if !self.diagnostic_metadata.is_assign_rhs {
3969 self.diagnostic_metadata.in_assignment = Some(expr);
3971 self.visit_expr(lhs);
3972 self.diagnostic_metadata.is_assign_rhs = true;
3973 self.diagnostic_metadata.in_assignment = None;
3974 self.visit_expr(rhs);
3975 self.diagnostic_metadata.is_assign_rhs = false;
3978 visit::walk_expr(self, expr);
3983 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
3985 ExprKind::Field(_, ident) => {
3986 // FIXME(#6890): Even though you can't treat a method like a
3987 // field, we need to add any trait methods we find that match
3988 // the field name so that we can do some nice error reporting
3989 // later on in typeck.
3990 let traits = self.traits_in_scope(ident, ValueNS);
3991 self.r.trait_map.insert(expr.id, traits);
3993 ExprKind::MethodCall(ref segment, ..) => {
3994 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
3995 let traits = self.traits_in_scope(segment.ident, ValueNS);
3996 self.r.trait_map.insert(expr.id, traits);
4004 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
4005 self.r.traits_in_scope(
4006 self.current_trait_ref.as_ref().map(|(module, _)| *module),
4009 Some((ident.name, ns)),
4013 /// Construct the list of in-scope lifetime parameters for async lowering.
4014 /// We include all lifetime parameters, either named or "Fresh".
4015 /// The order of those parameters does not matter, as long as it is
4017 fn record_lifetime_params_for_async(
4020 async_node_id: Option<(NodeId, Span)>,
4022 if let Some((async_node_id, span)) = async_node_id {
4023 let mut extra_lifetime_params =
4024 self.r.extra_lifetime_params_map.get(&fn_id).cloned().unwrap_or_default();
4025 for rib in self.lifetime_ribs.iter().rev() {
4026 extra_lifetime_params.extend(
4027 rib.bindings.iter().map(|(&ident, &(node_id, res))| (ident, node_id, res)),
4030 LifetimeRibKind::Item => break,
4031 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
4032 if let Some(earlier_fresh) = self.r.extra_lifetime_params_map.get(&binder) {
4033 extra_lifetime_params.extend(earlier_fresh);
4036 LifetimeRibKind::Generics { .. } => {}
4038 // We are in a function definition. We should only find `Generics`
4039 // and `AnonymousCreateParameter` inside the innermost `Item`.
4040 span_bug!(span, "unexpected rib kind: {:?}", rib.kind)
4044 self.r.extra_lifetime_params_map.insert(async_node_id, extra_lifetime_params);
4049 struct LifetimeCountVisitor<'a, 'b> {
4050 r: &'b mut Resolver<'a>,
4053 /// Walks the whole crate in DFS order, visiting each item, counting the declared number of
4054 /// lifetime generic parameters.
4055 impl<'ast> Visitor<'ast> for LifetimeCountVisitor<'_, '_> {
4056 fn visit_item(&mut self, item: &'ast Item) {
4058 ItemKind::TyAlias(box TyAlias { ref generics, .. })
4059 | ItemKind::Fn(box Fn { ref generics, .. })
4060 | ItemKind::Enum(_, ref generics)
4061 | ItemKind::Struct(_, ref generics)
4062 | ItemKind::Union(_, ref generics)
4063 | ItemKind::Impl(box Impl { ref generics, .. })
4064 | ItemKind::Trait(box Trait { ref generics, .. })
4065 | ItemKind::TraitAlias(ref generics, _) => {
4066 let def_id = self.r.local_def_id(item.id);
4067 let count = generics
4070 .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
4072 self.r.item_generics_num_lifetimes.insert(def_id, count);
4076 | ItemKind::ForeignMod(..)
4077 | ItemKind::Static(..)
4078 | ItemKind::Const(..)
4080 | ItemKind::ExternCrate(..)
4081 | ItemKind::MacroDef(..)
4082 | ItemKind::GlobalAsm(..)
4083 | ItemKind::MacCall(..) => {}
4085 visit::walk_item(self, item)
4089 impl<'a> Resolver<'a> {
4090 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
4091 visit::walk_crate(&mut LifetimeCountVisitor { r: self }, krate);
4092 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
4093 visit::walk_crate(&mut late_resolution_visitor, krate);
4094 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
4095 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");