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, 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(sym.id, &sym.qself, &sym.path, PathSource::Expr(None));
1142 visit::walk_inline_asm_sym(this, sym);
1149 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
1150 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
1151 // During late resolution we only track the module component of the parent scope,
1152 // although it may be useful to track other components as well for diagnostics.
1153 let graph_root = resolver.graph_root;
1154 let parent_scope = ParentScope::module(graph_root, resolver);
1155 let start_rib_kind = ModuleRibKind(graph_root);
1156 LateResolutionVisitor {
1160 value_ns: vec![Rib::new(start_rib_kind)],
1161 type_ns: vec![Rib::new(start_rib_kind)],
1162 macro_ns: vec![Rib::new(start_rib_kind)],
1164 label_ribs: Vec::new(),
1165 lifetime_ribs: Vec::new(),
1166 lifetime_elision_candidates: None,
1167 current_trait_ref: None,
1168 diagnostic_metadata: Box::new(DiagnosticMetadata::default()),
1169 // errors at module scope should always be reported
1170 in_func_body: false,
1171 lifetime_uses: Default::default(),
1175 fn maybe_resolve_ident_in_lexical_scope(
1179 ) -> Option<LexicalScopeBinding<'a>> {
1180 self.r.resolve_ident_in_lexical_scope(
1190 fn resolve_ident_in_lexical_scope(
1194 finalize: Option<Finalize>,
1195 ignore_binding: Option<&'a NameBinding<'a>>,
1196 ) -> Option<LexicalScopeBinding<'a>> {
1197 self.r.resolve_ident_in_lexical_scope(
1210 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1211 finalize: Option<Finalize>,
1212 ) -> PathResult<'a> {
1213 self.r.resolve_path_with_ribs(
1225 // We maintain a list of value ribs and type ribs.
1227 // Simultaneously, we keep track of the current position in the module
1228 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
1229 // the value or type namespaces, we first look through all the ribs and
1230 // then query the module graph. When we resolve a name in the module
1231 // namespace, we can skip all the ribs (since nested modules are not
1232 // allowed within blocks in Rust) and jump straight to the current module
1235 // Named implementations are handled separately. When we find a method
1236 // call, we consult the module node to find all of the implementations in
1237 // scope. This information is lazily cached in the module node. We then
1238 // generate a fake "implementation scope" containing all the
1239 // implementations thus found, for compatibility with old resolve pass.
1241 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
1246 work: impl FnOnce(&mut Self) -> T,
1248 self.ribs[ns].push(Rib::new(kind));
1249 let ret = work(self);
1250 self.ribs[ns].pop();
1254 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
1255 if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
1256 // Move down in the graph.
1257 let orig_module = replace(&mut self.parent_scope.module, module);
1258 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
1259 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
1261 this.parent_scope.module = orig_module;
1270 fn visit_generic_params(&mut self, params: &'ast [GenericParam], add_self_upper: bool) {
1271 // For type parameter defaults, we have to ban access
1272 // to following type parameters, as the InternalSubsts can only
1273 // provide previous type parameters as they're built. We
1274 // put all the parameters on the ban list and then remove
1275 // them one by one as they are processed and become available.
1276 let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1277 let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1278 for param in params.iter() {
1280 GenericParamKind::Type { .. } => {
1283 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1285 GenericParamKind::Const { .. } => {
1286 forward_const_ban_rib
1288 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1290 GenericParamKind::Lifetime => {}
1294 // rust-lang/rust#61631: The type `Self` is essentially
1295 // another type parameter. For ADTs, we consider it
1296 // well-defined only after all of the ADT type parameters have
1297 // been provided. Therefore, we do not allow use of `Self`
1298 // anywhere in ADT type parameter defaults.
1300 // (We however cannot ban `Self` for defaults on *all* generic
1301 // lists; e.g. trait generics can usefully refer to `Self`,
1302 // such as in the case of `trait Add<Rhs = Self>`.)
1304 // (`Some` if + only if we are in ADT's generics.)
1305 forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
1308 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1309 for param in params {
1311 GenericParamKind::Lifetime => {
1312 for bound in ¶m.bounds {
1313 this.visit_param_bound(bound, BoundKind::Bound);
1316 GenericParamKind::Type { ref default } => {
1317 for bound in ¶m.bounds {
1318 this.visit_param_bound(bound, BoundKind::Bound);
1321 if let Some(ref ty) = default {
1322 this.ribs[TypeNS].push(forward_ty_ban_rib);
1323 this.ribs[ValueNS].push(forward_const_ban_rib);
1325 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1326 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1329 // Allow all following defaults to refer to this type parameter.
1332 .remove(&Ident::with_dummy_span(param.ident.name));
1334 GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
1335 // Const parameters can't have param bounds.
1336 assert!(param.bounds.is_empty());
1338 this.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
1339 this.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
1340 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1343 this.ribs[TypeNS].pop().unwrap();
1344 this.ribs[ValueNS].pop().unwrap();
1346 if let Some(ref expr) = default {
1347 this.ribs[TypeNS].push(forward_ty_ban_rib);
1348 this.ribs[ValueNS].push(forward_const_ban_rib);
1349 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1350 this.resolve_anon_const(expr, IsRepeatExpr::No)
1352 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1353 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1356 // Allow all following defaults to refer to this const parameter.
1357 forward_const_ban_rib
1359 .remove(&Ident::with_dummy_span(param.ident.name));
1366 #[instrument(level = "debug", skip(self, work))]
1367 fn with_lifetime_rib<T>(
1369 kind: LifetimeRibKind,
1370 work: impl FnOnce(&mut Self) -> T,
1372 self.lifetime_ribs.push(LifetimeRib::new(kind));
1373 let outer_elision_candidates = self.lifetime_elision_candidates.take();
1374 let ret = work(self);
1375 self.lifetime_elision_candidates = outer_elision_candidates;
1376 self.lifetime_ribs.pop();
1380 #[instrument(level = "debug", skip(self))]
1381 fn resolve_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
1382 let ident = lifetime.ident;
1384 if ident.name == kw::StaticLifetime {
1385 self.record_lifetime_res(
1387 LifetimeRes::Static,
1388 LifetimeElisionCandidate::Named,
1393 if ident.name == kw::UnderscoreLifetime {
1394 return self.resolve_anonymous_lifetime(lifetime, false);
1397 let mut lifetime_rib_iter = self.lifetime_ribs.iter().rev();
1398 while let Some(rib) = lifetime_rib_iter.next() {
1399 let normalized_ident = ident.normalize_to_macros_2_0();
1400 if let Some(&(_, res)) = rib.bindings.get(&normalized_ident) {
1401 self.record_lifetime_res(lifetime.id, res, LifetimeElisionCandidate::Named);
1403 if let LifetimeRes::Param { param, .. } = res {
1404 match self.lifetime_uses.entry(param) {
1405 Entry::Vacant(v) => {
1406 debug!("First use of {:?} at {:?}", res, ident.span);
1411 .find_map(|rib| match rib.kind {
1412 // Do not suggest eliding a lifetime where an anonymous
1413 // lifetime would be illegal.
1414 LifetimeRibKind::Item
1415 | LifetimeRibKind::AnonymousReportError
1416 | LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many),
1417 // An anonymous lifetime is legal here, go ahead.
1418 LifetimeRibKind::AnonymousCreateParameter { .. } => {
1419 Some(LifetimeUseSet::One { use_span: ident.span, use_ctxt })
1421 // Only report if eliding the lifetime would have the same
1423 LifetimeRibKind::Elided(r) => Some(if res == r {
1424 LifetimeUseSet::One { use_span: ident.span, use_ctxt }
1426 LifetimeUseSet::Many
1428 LifetimeRibKind::Generics { .. } => None,
1429 LifetimeRibKind::ConstGeneric | LifetimeRibKind::AnonConst => {
1430 span_bug!(ident.span, "unexpected rib kind: {:?}", rib.kind)
1433 .unwrap_or(LifetimeUseSet::Many);
1434 debug!(?use_ctxt, ?use_set);
1437 Entry::Occupied(mut o) => {
1438 debug!("Many uses of {:?} at {:?}", res, ident.span);
1439 *o.get_mut() = LifetimeUseSet::Many;
1447 LifetimeRibKind::Item => break,
1448 LifetimeRibKind::ConstGeneric => {
1449 self.emit_non_static_lt_in_const_generic_error(lifetime);
1450 self.record_lifetime_res(
1453 LifetimeElisionCandidate::Ignore,
1457 LifetimeRibKind::AnonConst => {
1458 self.maybe_emit_forbidden_non_static_lifetime_error(lifetime);
1459 self.record_lifetime_res(
1462 LifetimeElisionCandidate::Ignore,
1466 LifetimeRibKind::AnonymousCreateParameter { .. }
1467 | LifetimeRibKind::Elided(_)
1468 | LifetimeRibKind::Generics { .. }
1469 | LifetimeRibKind::ElisionFailure
1470 | LifetimeRibKind::AnonymousReportError => {}
1474 let mut outer_res = None;
1475 for rib in lifetime_rib_iter {
1476 let normalized_ident = ident.normalize_to_macros_2_0();
1477 if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) {
1478 outer_res = Some(outer);
1483 self.emit_undeclared_lifetime_error(lifetime, outer_res);
1484 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, LifetimeElisionCandidate::Named);
1487 #[instrument(level = "debug", skip(self))]
1488 fn resolve_anonymous_lifetime(&mut self, lifetime: &Lifetime, elided: bool) {
1489 debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
1491 let missing_lifetime = MissingLifetime {
1493 span: lifetime.ident.span,
1495 MissingLifetimeKind::Ampersand
1497 MissingLifetimeKind::Underscore
1501 let elision_candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1502 for rib in self.lifetime_ribs.iter().rev() {
1505 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1506 let res = self.create_fresh_lifetime(lifetime.id, lifetime.ident, binder);
1507 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1510 LifetimeRibKind::AnonymousReportError => {
1511 let (msg, note) = if elided {
1513 "`&` without an explicit lifetime name cannot be used here",
1514 "explicit lifetime name needed here",
1517 ("`'_` cannot be used here", "`'_` is a reserved lifetime name")
1519 rustc_errors::struct_span_err!(
1521 lifetime.ident.span,
1526 .span_label(lifetime.ident.span, note)
1529 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1532 LifetimeRibKind::Elided(res) => {
1533 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1536 LifetimeRibKind::ElisionFailure => {
1537 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1538 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1541 LifetimeRibKind::Item => break,
1542 LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstGeneric => {}
1543 LifetimeRibKind::AnonConst => {
1544 // There is always an `Elided(LifetimeRes::Static)` inside an `AnonConst`.
1545 span_bug!(lifetime.ident.span, "unexpected rib kind: {:?}", rib.kind)
1549 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1550 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1553 #[instrument(level = "debug", skip(self))]
1554 fn resolve_elided_lifetime(&mut self, anchor_id: NodeId, span: Span) {
1555 let id = self.r.next_node_id();
1556 let lt = Lifetime { id, ident: Ident::new(kw::UnderscoreLifetime, span) };
1558 self.record_lifetime_res(
1560 LifetimeRes::ElidedAnchor { start: id, end: NodeId::from_u32(id.as_u32() + 1) },
1561 LifetimeElisionCandidate::Ignore,
1563 self.resolve_anonymous_lifetime(<, true);
1566 #[instrument(level = "debug", skip(self))]
1567 fn create_fresh_lifetime(&mut self, id: NodeId, ident: Ident, binder: NodeId) -> LifetimeRes {
1568 debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
1569 debug!(?ident.span);
1571 // Leave the responsibility to create the `LocalDefId` to lowering.
1572 let param = self.r.next_node_id();
1573 let res = LifetimeRes::Fresh { param, binder };
1575 // Record the created lifetime parameter so lowering can pick it up and add it to HIR.
1577 .extra_lifetime_params_map
1579 .or_insert_with(Vec::new)
1580 .push((ident, param, res));
1584 #[instrument(level = "debug", skip(self))]
1585 fn resolve_elided_lifetimes_in_path(
1588 partial_res: PartialRes,
1590 source: PathSource<'_>,
1593 let proj_start = path.len() - partial_res.unresolved_segments();
1594 for (i, segment) in path.iter().enumerate() {
1595 if segment.has_lifetime_args {
1598 let Some(segment_id) = segment.id else {
1602 // Figure out if this is a type/trait segment,
1603 // which may need lifetime elision performed.
1604 let type_def_id = match partial_res.base_res() {
1605 Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => self.r.parent(def_id),
1606 Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => self.r.parent(def_id),
1607 Res::Def(DefKind::Struct, def_id)
1608 | Res::Def(DefKind::Union, def_id)
1609 | Res::Def(DefKind::Enum, def_id)
1610 | Res::Def(DefKind::TyAlias, def_id)
1611 | Res::Def(DefKind::Trait, def_id)
1612 if i + 1 == proj_start =>
1619 let expected_lifetimes = self.r.item_generics_num_lifetimes(type_def_id);
1620 if expected_lifetimes == 0 {
1624 let node_ids = self.r.next_node_ids(expected_lifetimes);
1625 self.record_lifetime_res(
1627 LifetimeRes::ElidedAnchor { start: node_ids.start, end: node_ids.end },
1628 LifetimeElisionCandidate::Ignore,
1631 let inferred = match source {
1632 PathSource::Trait(..) | PathSource::TraitItem(..) | PathSource::Type => false,
1633 PathSource::Expr(..)
1635 | PathSource::Struct
1636 | PathSource::TupleStruct(..) => true,
1639 // Do not create a parameter for patterns and expressions: type checking can infer
1640 // the appropriate lifetime for us.
1641 for id in node_ids {
1642 self.record_lifetime_res(
1645 LifetimeElisionCandidate::Named,
1651 let elided_lifetime_span = if segment.has_generic_args {
1652 // If there are brackets, but not generic arguments, then use the opening bracket
1653 segment.args_span.with_hi(segment.args_span.lo() + BytePos(1))
1655 // If there are no brackets, use the identifier span.
1656 // HACK: we use find_ancestor_inside to properly suggest elided spans in paths
1657 // originating from macros, since the segment's span might be from a macro arg.
1658 segment.ident.span.find_ancestor_inside(path_span).unwrap_or(path_span)
1660 let ident = Ident::new(kw::UnderscoreLifetime, elided_lifetime_span);
1662 let missing_lifetime = MissingLifetime {
1664 span: elided_lifetime_span,
1665 kind: if segment.has_generic_args {
1666 MissingLifetimeKind::Comma
1668 MissingLifetimeKind::Brackets
1670 count: expected_lifetimes,
1672 let mut should_lint = true;
1673 for rib in self.lifetime_ribs.iter().rev() {
1675 // In create-parameter mode we error here because we don't want to support
1676 // deprecated impl elision in new features like impl elision and `async fn`,
1677 // both of which work using the `CreateParameter` mode:
1679 // impl Foo for std::cell::Ref<u32> // note lack of '_
1680 // async fn foo(_: std::cell::Ref<u32>) { ... }
1681 LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. } => {
1682 let sess = self.r.session;
1683 let mut err = rustc_errors::struct_span_err!(
1687 "implicit elided lifetime not allowed here"
1689 rustc_errors::add_elided_lifetime_in_path_suggestion(
1694 !segment.has_generic_args,
1695 elided_lifetime_span,
1697 err.note("assuming a `'static` lifetime...");
1699 should_lint = false;
1701 for id in node_ids {
1702 self.record_lifetime_res(
1705 LifetimeElisionCandidate::Named,
1710 // Do not create a parameter for patterns and expressions.
1711 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1712 // Group all suggestions into the first record.
1713 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1714 for id in node_ids {
1715 let res = self.create_fresh_lifetime(id, ident, binder);
1716 self.record_lifetime_res(
1719 replace(&mut candidate, LifetimeElisionCandidate::Named),
1724 LifetimeRibKind::Elided(res) => {
1725 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1726 for id in node_ids {
1727 self.record_lifetime_res(
1730 replace(&mut candidate, LifetimeElisionCandidate::Ignore),
1735 LifetimeRibKind::ElisionFailure => {
1736 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1737 for id in node_ids {
1738 self.record_lifetime_res(
1741 LifetimeElisionCandidate::Ignore,
1746 // `LifetimeRes::Error`, which would usually be used in the case of
1747 // `ReportError`, is unsuitable here, as we don't emit an error yet. Instead,
1748 // we simply resolve to an implicit lifetime, which will be checked later, at
1749 // which point a suitable error will be emitted.
1750 LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
1751 for id in node_ids {
1752 self.record_lifetime_res(
1755 LifetimeElisionCandidate::Ignore,
1758 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1761 LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstGeneric => {}
1762 LifetimeRibKind::AnonConst => {
1763 // There is always an `Elided(LifetimeRes::Static)` inside an `AnonConst`.
1764 span_bug!(elided_lifetime_span, "unexpected rib kind: {:?}", rib.kind)
1770 self.r.lint_buffer.buffer_lint_with_diagnostic(
1771 lint::builtin::ELIDED_LIFETIMES_IN_PATHS,
1773 elided_lifetime_span,
1774 "hidden lifetime parameters in types are deprecated",
1775 lint::BuiltinLintDiagnostics::ElidedLifetimesInPaths(
1778 !segment.has_generic_args,
1779 elided_lifetime_span,
1786 #[instrument(level = "debug", skip(self))]
1787 fn record_lifetime_res(
1791 candidate: LifetimeElisionCandidate,
1793 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1795 "lifetime {:?} resolved multiple times ({:?} before, {:?} now)",
1800 LifetimeRes::Param { .. } | LifetimeRes::Fresh { .. } | LifetimeRes::Static => {
1801 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
1802 candidates.push((res, candidate));
1805 LifetimeRes::Infer | LifetimeRes::Error | LifetimeRes::ElidedAnchor { .. } => {}
1809 #[instrument(level = "debug", skip(self))]
1810 fn record_lifetime_param(&mut self, id: NodeId, res: LifetimeRes) {
1811 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1813 "lifetime parameter {:?} resolved multiple times ({:?} before, {:?} now)",
1819 /// Perform resolution of a function signature, accounting for lifetime elision.
1820 #[instrument(level = "debug", skip(self, inputs))]
1821 fn resolve_fn_signature(
1825 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)> + Clone,
1826 output_ty: &'ast FnRetTy,
1828 // Add each argument to the rib.
1829 let elision_lifetime = self.resolve_fn_params(has_self, inputs);
1830 debug!(?elision_lifetime);
1832 let outer_failures = take(&mut self.diagnostic_metadata.current_elision_failures);
1833 let output_rib = if let Ok(res) = elision_lifetime.as_ref() {
1834 LifetimeRibKind::Elided(*res)
1836 LifetimeRibKind::ElisionFailure
1838 self.with_lifetime_rib(output_rib, |this| visit::walk_fn_ret_ty(this, &output_ty));
1839 let elision_failures =
1840 replace(&mut self.diagnostic_metadata.current_elision_failures, outer_failures);
1841 if !elision_failures.is_empty() {
1842 let Err(failure_info) = elision_lifetime else { bug!() };
1843 self.report_missing_lifetime_specifiers(elision_failures, Some(failure_info));
1847 /// Resolve inside function parameters and parameter types.
1848 /// Returns the lifetime for elision in fn return type,
1849 /// or diagnostic information in case of elision failure.
1850 fn resolve_fn_params(
1853 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)>,
1854 ) -> Result<LifetimeRes, (Vec<MissingLifetime>, Vec<ElisionFnParameter>)> {
1856 /// We have not found any candidate.
1858 /// We have a candidate bound to `self`.
1860 /// We have a candidate bound to a parameter.
1862 /// We failed elision.
1866 // Save elision state to reinstate it later.
1867 let outer_candidates = self.lifetime_elision_candidates.take();
1869 // Result of elision.
1870 let mut elision_lifetime = Elision::None;
1871 // Information for diagnostics.
1872 let mut parameter_info = Vec::new();
1873 let mut all_candidates = Vec::new();
1875 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1876 for (index, (pat, ty)) in inputs.enumerate() {
1878 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
1879 if let Some(pat) = pat {
1880 this.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1884 // Record elision candidates only for this parameter.
1885 debug_assert_matches!(self.lifetime_elision_candidates, None);
1886 self.lifetime_elision_candidates = Some(Default::default());
1888 let local_candidates = self.lifetime_elision_candidates.take();
1890 if let Some(candidates) = local_candidates {
1891 let distinct: FxHashSet<_> = candidates.iter().map(|(res, _)| *res).collect();
1892 let lifetime_count = distinct.len();
1893 if lifetime_count != 0 {
1894 parameter_info.push(ElisionFnParameter {
1896 ident: if let Some(pat) = pat && let PatKind::Ident(_, ident, _) = pat.kind {
1904 all_candidates.extend(candidates.into_iter().filter_map(|(_, candidate)| {
1906 LifetimeElisionCandidate::Ignore | LifetimeElisionCandidate::Named => {
1909 LifetimeElisionCandidate::Missing(missing) => Some(missing),
1913 let mut distinct_iter = distinct.into_iter();
1914 if let Some(res) = distinct_iter.next() {
1915 match elision_lifetime {
1916 // We are the first parameter to bind lifetimes.
1918 if distinct_iter.next().is_none() {
1919 // We have a single lifetime => success.
1920 elision_lifetime = Elision::Param(res)
1922 // We have have multiple lifetimes => error.
1923 elision_lifetime = Elision::Err;
1926 // We have 2 parameters that bind lifetimes => error.
1927 Elision::Param(_) => elision_lifetime = Elision::Err,
1928 // `self` elision takes precedence over everything else.
1929 Elision::Self_(_) | Elision::Err => {}
1934 // Handle `self` specially.
1935 if index == 0 && has_self {
1936 let self_lifetime = self.find_lifetime_for_self(ty);
1937 if let Set1::One(lifetime) = self_lifetime {
1938 // We found `self` elision.
1939 elision_lifetime = Elision::Self_(lifetime);
1941 // We do not have `self` elision: disregard the `Elision::Param` that we may
1943 elision_lifetime = Elision::None;
1946 debug!("(resolving function / closure) recorded parameter");
1949 // Reinstate elision state.
1950 debug_assert_matches!(self.lifetime_elision_candidates, None);
1951 self.lifetime_elision_candidates = outer_candidates;
1953 if let Elision::Param(res) | Elision::Self_(res) = elision_lifetime {
1957 // We do not have a candidate.
1958 Err((all_candidates, parameter_info))
1961 /// List all the lifetimes that appear in the provided type.
1962 fn find_lifetime_for_self(&self, ty: &'ast Ty) -> Set1<LifetimeRes> {
1963 struct SelfVisitor<'r, 'a> {
1964 r: &'r Resolver<'a>,
1965 impl_self: Option<Res>,
1966 lifetime: Set1<LifetimeRes>,
1969 impl SelfVisitor<'_, '_> {
1970 // Look for `self: &'a Self` - also desugared from `&'a self`,
1971 // and if that matches, use it for elision and return early.
1972 fn is_self_ty(&self, ty: &Ty) -> bool {
1974 TyKind::ImplicitSelf => true,
1975 TyKind::Path(None, _) => {
1976 let path_res = self.r.partial_res_map[&ty.id].full_res();
1977 if let Some(Res::SelfTyParam { .. } | Res::SelfTyAlias { .. }) = path_res {
1980 self.impl_self.is_some() && path_res == self.impl_self
1987 impl<'a> Visitor<'a> for SelfVisitor<'_, '_> {
1988 fn visit_ty(&mut self, ty: &'a Ty) {
1989 trace!("SelfVisitor considering ty={:?}", ty);
1990 if let TyKind::Rptr(lt, ref mt) = ty.kind && self.is_self_ty(&mt.ty) {
1991 let lt_id = if let Some(lt) = lt {
1994 let res = self.r.lifetimes_res_map[&ty.id];
1995 let LifetimeRes::ElidedAnchor { start, .. } = res else { bug!() };
1998 let lt_res = self.r.lifetimes_res_map[<_id];
1999 trace!("SelfVisitor inserting res={:?}", lt_res);
2000 self.lifetime.insert(lt_res);
2002 visit::walk_ty(self, ty)
2006 let impl_self = self
2007 .diagnostic_metadata
2011 if let TyKind::Path(None, _) = ty.kind {
2012 self.r.partial_res_map.get(&ty.id)
2017 .and_then(|res| res.full_res())
2019 // Permit the types that unambiguously always
2020 // result in the same type constructor being used
2021 // (it can't differ between `Self` and `self`).
2024 Res::Def(DefKind::Struct | DefKind::Union | DefKind::Enum, _,) | Res::PrimTy(_)
2027 let mut visitor = SelfVisitor { r: self.r, impl_self, lifetime: Set1::Empty };
2028 visitor.visit_ty(ty);
2029 trace!("SelfVisitor found={:?}", visitor.lifetime);
2033 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
2034 /// label and reports an error if the label is not found or is unreachable.
2035 fn resolve_label(&mut self, mut label: Ident) -> Result<(NodeId, Span), ResolutionError<'a>> {
2036 let mut suggestion = None;
2038 for i in (0..self.label_ribs.len()).rev() {
2039 let rib = &self.label_ribs[i];
2041 if let MacroDefinition(def) = rib.kind {
2042 // If an invocation of this macro created `ident`, give up on `ident`
2043 // and switch to `ident`'s source from the macro definition.
2044 if def == self.r.macro_def(label.span.ctxt()) {
2045 label.span.remove_mark();
2049 let ident = label.normalize_to_macro_rules();
2050 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
2051 let definition_span = ident.span;
2052 return if self.is_label_valid_from_rib(i) {
2053 Ok((*id, definition_span))
2055 Err(ResolutionError::UnreachableLabel {
2063 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
2064 // the first such label that is encountered.
2065 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
2068 Err(ResolutionError::UndeclaredLabel { name: label.name, suggestion })
2071 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
2072 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
2073 let ribs = &self.label_ribs[rib_index + 1..];
2076 if rib.kind.is_label_barrier() {
2084 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
2085 debug!("resolve_adt");
2086 self.with_current_self_item(item, |this| {
2087 this.with_generic_param_rib(
2089 ItemRibKind(HasGenericParams::Yes(generics.span)),
2090 LifetimeRibKind::Generics {
2092 kind: LifetimeBinderKind::Item,
2093 span: generics.span,
2096 let item_def_id = this.r.local_def_id(item.id).to_def_id();
2099 alias_to: item_def_id,
2100 forbid_generic: false,
2101 is_trait_impl: false,
2104 visit::walk_item(this, item);
2112 fn future_proof_import(&mut self, use_tree: &UseTree) {
2113 let segments = &use_tree.prefix.segments;
2114 if !segments.is_empty() {
2115 let ident = segments[0].ident;
2116 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
2120 let nss = match use_tree.kind {
2121 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
2124 let report_error = |this: &Self, ns| {
2125 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
2126 if this.should_report_errs() {
2129 .span_err(ident.span, &format!("imports cannot refer to {}", what));
2134 match self.maybe_resolve_ident_in_lexical_scope(ident, ns) {
2135 Some(LexicalScopeBinding::Res(..)) => {
2136 report_error(self, ns);
2138 Some(LexicalScopeBinding::Item(binding)) => {
2139 if let Some(LexicalScopeBinding::Res(..)) =
2140 self.resolve_ident_in_lexical_scope(ident, ns, None, Some(binding))
2142 report_error(self, ns);
2148 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
2149 for (use_tree, _) in use_trees {
2150 self.future_proof_import(use_tree);
2155 fn resolve_item(&mut self, item: &'ast Item) {
2156 let name = item.ident.name;
2157 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
2160 ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
2161 self.with_generic_param_rib(
2163 ItemRibKind(HasGenericParams::Yes(generics.span)),
2164 LifetimeRibKind::Generics {
2166 kind: LifetimeBinderKind::Item,
2167 span: generics.span,
2169 |this| visit::walk_item(this, item),
2173 ItemKind::Fn(box Fn { ref generics, .. }) => {
2174 self.with_generic_param_rib(
2176 ItemRibKind(HasGenericParams::Yes(generics.span)),
2177 LifetimeRibKind::Generics {
2179 kind: LifetimeBinderKind::Function,
2180 span: generics.span,
2182 |this| visit::walk_item(this, item),
2186 ItemKind::Enum(_, ref generics)
2187 | ItemKind::Struct(_, ref generics)
2188 | ItemKind::Union(_, ref generics) => {
2189 self.resolve_adt(item, generics);
2192 ItemKind::Impl(box Impl {
2196 items: ref impl_items,
2199 self.diagnostic_metadata.current_impl_items = Some(impl_items);
2200 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
2201 self.diagnostic_metadata.current_impl_items = None;
2204 ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
2205 // Create a new rib for the trait-wide type parameters.
2206 self.with_generic_param_rib(
2208 ItemRibKind(HasGenericParams::Yes(generics.span)),
2209 LifetimeRibKind::Generics {
2211 kind: LifetimeBinderKind::Item,
2212 span: generics.span,
2215 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2216 this.with_self_rib(Res::SelfTyParam { trait_: local_def_id }, |this| {
2217 this.visit_generics(generics);
2218 walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);
2219 this.resolve_trait_items(items);
2225 ItemKind::TraitAlias(ref generics, ref bounds) => {
2226 // Create a new rib for the trait-wide type parameters.
2227 self.with_generic_param_rib(
2229 ItemRibKind(HasGenericParams::Yes(generics.span)),
2230 LifetimeRibKind::Generics {
2232 kind: LifetimeBinderKind::Item,
2233 span: generics.span,
2236 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2237 this.with_self_rib(Res::SelfTyParam { trait_: local_def_id }, |this| {
2238 this.visit_generics(generics);
2239 walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
2245 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
2246 self.with_scope(item.id, |this| {
2247 visit::walk_item(this, item);
2251 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
2252 self.with_static_rib(|this| {
2253 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
2256 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2257 if let Some(expr) = expr {
2258 let constant_item_kind = match item.kind {
2259 ItemKind::Const(..) => ConstantItemKind::Const,
2260 ItemKind::Static(..) => ConstantItemKind::Static,
2261 _ => unreachable!(),
2263 // We already forbid generic params because of the above item rib,
2264 // so it doesn't matter whether this is a trivial constant.
2265 this.with_constant_rib(
2267 ConstantHasGenerics::Yes,
2268 Some((item.ident, constant_item_kind)),
2269 |this| this.visit_expr(expr),
2276 ItemKind::Use(ref use_tree) => {
2277 self.future_proof_import(use_tree);
2280 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => {
2281 // do nothing, these are just around to be encoded
2284 ItemKind::GlobalAsm(_) => {
2285 visit::walk_item(self, item);
2288 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
2292 fn with_generic_param_rib<'c, F>(
2294 params: &'c [GenericParam],
2296 lifetime_kind: LifetimeRibKind,
2299 F: FnOnce(&mut Self),
2301 debug!("with_generic_param_rib");
2302 let LifetimeRibKind::Generics { binder, span: generics_span, kind: generics_kind, .. }
2303 = lifetime_kind else { panic!() };
2305 let mut function_type_rib = Rib::new(kind);
2306 let mut function_value_rib = Rib::new(kind);
2307 let mut function_lifetime_rib = LifetimeRib::new(lifetime_kind);
2308 let mut seen_bindings = FxHashMap::default();
2309 // Store all seen lifetimes names from outer scopes.
2310 let mut seen_lifetimes = FxHashSet::default();
2312 // We also can't shadow bindings from the parent item
2313 if let AssocItemRibKind = kind {
2314 let mut add_bindings_for_ns = |ns| {
2315 let parent_rib = self.ribs[ns]
2317 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
2318 .expect("associated item outside of an item");
2320 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
2322 add_bindings_for_ns(ValueNS);
2323 add_bindings_for_ns(TypeNS);
2326 // Forbid shadowing lifetime bindings
2327 for rib in self.lifetime_ribs.iter().rev() {
2328 seen_lifetimes.extend(rib.bindings.iter().map(|(ident, _)| *ident));
2329 if let LifetimeRibKind::Item = rib.kind {
2334 for param in params {
2335 let ident = param.ident.normalize_to_macros_2_0();
2336 debug!("with_generic_param_rib: {}", param.id);
2338 if let GenericParamKind::Lifetime = param.kind
2339 && let Some(&original) = seen_lifetimes.get(&ident)
2341 diagnostics::signal_lifetime_shadowing(self.r.session, original, param.ident);
2342 // Record lifetime res, so lowering knows there is something fishy.
2343 self.record_lifetime_param(param.id, LifetimeRes::Error);
2347 match seen_bindings.entry(ident) {
2348 Entry::Occupied(entry) => {
2349 let span = *entry.get();
2350 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
2351 self.report_error(param.ident.span, err);
2352 if let GenericParamKind::Lifetime = param.kind {
2353 // Record lifetime res, so lowering knows there is something fishy.
2354 self.record_lifetime_param(param.id, LifetimeRes::Error);
2358 Entry::Vacant(entry) => {
2359 entry.insert(param.ident.span);
2363 if param.ident.name == kw::UnderscoreLifetime {
2364 rustc_errors::struct_span_err!(
2368 "`'_` cannot be used here"
2370 .span_label(param.ident.span, "`'_` is a reserved lifetime name")
2372 // Record lifetime res, so lowering knows there is something fishy.
2373 self.record_lifetime_param(param.id, LifetimeRes::Error);
2377 if param.ident.name == kw::StaticLifetime {
2378 rustc_errors::struct_span_err!(
2382 "invalid lifetime parameter name: `{}`",
2385 .span_label(param.ident.span, "'static is a reserved lifetime name")
2387 // Record lifetime res, so lowering knows there is something fishy.
2388 self.record_lifetime_param(param.id, LifetimeRes::Error);
2392 let def_id = self.r.local_def_id(param.id);
2394 // Plain insert (no renaming).
2395 let (rib, def_kind) = match param.kind {
2396 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
2397 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
2398 GenericParamKind::Lifetime => {
2399 let res = LifetimeRes::Param { param: def_id, binder };
2400 self.record_lifetime_param(param.id, res);
2401 function_lifetime_rib.bindings.insert(ident, (param.id, res));
2406 let res = match kind {
2407 ItemRibKind(..) | AssocItemRibKind => Res::Def(def_kind, def_id.to_def_id()),
2408 NormalRibKind => Res::Err,
2409 _ => span_bug!(param.ident.span, "Unexpected rib kind {:?}", kind),
2411 self.r.record_partial_res(param.id, PartialRes::new(res));
2412 rib.bindings.insert(ident, res);
2415 self.lifetime_ribs.push(function_lifetime_rib);
2416 self.ribs[ValueNS].push(function_value_rib);
2417 self.ribs[TypeNS].push(function_type_rib);
2421 self.ribs[TypeNS].pop();
2422 self.ribs[ValueNS].pop();
2423 let function_lifetime_rib = self.lifetime_ribs.pop().unwrap();
2425 // Do not account for the parameters we just bound for function lifetime elision.
2426 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
2427 for (_, res) in function_lifetime_rib.bindings.values() {
2428 candidates.retain(|(r, _)| r != res);
2432 if let LifetimeBinderKind::BareFnType
2433 | LifetimeBinderKind::WhereBound
2434 | LifetimeBinderKind::Function
2435 | LifetimeBinderKind::ImplBlock = generics_kind
2437 self.maybe_report_lifetime_uses(generics_span, params)
2441 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
2442 self.label_ribs.push(Rib::new(kind));
2444 self.label_ribs.pop();
2447 fn with_static_rib(&mut self, f: impl FnOnce(&mut Self)) {
2448 let kind = ItemRibKind(HasGenericParams::No);
2449 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
2452 // HACK(min_const_generics,const_evaluatable_unchecked): We
2453 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
2454 // with a future compat lint for now. We do this by adding an
2455 // additional special case for repeat expressions.
2457 // Note that we intentionally still forbid `[0; N + 1]` during
2458 // name resolution so that we don't extend the future
2459 // compat lint to new cases.
2460 #[instrument(level = "debug", skip(self, f))]
2461 fn with_constant_rib(
2463 is_repeat: IsRepeatExpr,
2464 may_use_generics: ConstantHasGenerics,
2465 item: Option<(Ident, ConstantItemKind)>,
2466 f: impl FnOnce(&mut Self),
2468 self.with_rib(ValueNS, ConstantItemRibKind(may_use_generics, item), |this| {
2471 ConstantItemRibKind(
2472 may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes),
2476 this.with_label_rib(ConstantItemRibKind(may_use_generics, item), f);
2482 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
2483 // Handle nested impls (inside fn bodies)
2484 let previous_value =
2485 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
2486 let result = f(self);
2487 self.diagnostic_metadata.current_self_type = previous_value;
2491 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
2492 let previous_value =
2493 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
2494 let result = f(self);
2495 self.diagnostic_metadata.current_self_item = previous_value;
2499 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
2500 fn resolve_trait_items(&mut self, trait_items: &'ast [P<AssocItem>]) {
2501 let trait_assoc_items =
2502 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
2504 let walk_assoc_item =
2505 |this: &mut Self, generics: &Generics, kind, item: &'ast AssocItem| {
2506 this.with_generic_param_rib(
2509 LifetimeRibKind::Generics { binder: item.id, span: generics.span, kind },
2510 |this| visit::walk_assoc_item(this, item, AssocCtxt::Trait),
2514 for item in trait_items {
2516 AssocItemKind::Const(_, ty, default) => {
2518 // Only impose the restrictions of `ConstRibKind` for an
2519 // actual constant expression in a provided default.
2520 if let Some(expr) = default {
2521 // We allow arbitrary const expressions inside of associated consts,
2522 // even if they are potentially not const evaluatable.
2524 // Type parameters can already be used and as associated consts are
2525 // not used as part of the type system, this is far less surprising.
2526 self.with_lifetime_rib(
2527 LifetimeRibKind::Elided(LifetimeRes::Infer),
2529 this.with_constant_rib(
2531 ConstantHasGenerics::Yes,
2533 |this| this.visit_expr(expr),
2539 AssocItemKind::Fn(box Fn { generics, .. }) => {
2540 walk_assoc_item(self, generics, LifetimeBinderKind::Function, item);
2542 AssocItemKind::Type(box TyAlias { generics, .. }) => self
2543 .with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2544 walk_assoc_item(this, generics, LifetimeBinderKind::Item, item)
2546 AssocItemKind::MacCall(_) => {
2547 panic!("unexpanded macro in resolve!")
2552 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
2555 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
2556 fn with_optional_trait_ref<T>(
2558 opt_trait_ref: Option<&TraitRef>,
2559 self_type: &'ast Ty,
2560 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
2562 let mut new_val = None;
2563 let mut new_id = None;
2564 if let Some(trait_ref) = opt_trait_ref {
2565 let path: Vec<_> = Segment::from_path(&trait_ref.path);
2566 self.diagnostic_metadata.currently_processing_impl_trait =
2567 Some((trait_ref.clone(), self_type.clone()));
2568 let res = self.smart_resolve_path_fragment(
2571 PathSource::Trait(AliasPossibility::No),
2572 Finalize::new(trait_ref.ref_id, trait_ref.path.span),
2574 self.diagnostic_metadata.currently_processing_impl_trait = None;
2575 if let Some(def_id) = res.expect_full_res().opt_def_id() {
2576 new_id = Some(def_id);
2577 new_val = Some((self.r.expect_module(def_id), trait_ref.clone()));
2580 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
2581 let result = f(self, new_id);
2582 self.current_trait_ref = original_trait_ref;
2586 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
2587 let mut self_type_rib = Rib::new(NormalRibKind);
2589 // Plain insert (no renaming, since types are not currently hygienic)
2590 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
2591 self.ribs[ns].push(self_type_rib);
2593 self.ribs[ns].pop();
2596 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
2597 self.with_self_rib_ns(TypeNS, self_res, f)
2600 fn resolve_implementation(
2602 generics: &'ast Generics,
2603 opt_trait_reference: &'ast Option<TraitRef>,
2604 self_type: &'ast Ty,
2606 impl_items: &'ast [P<AssocItem>],
2608 debug!("resolve_implementation");
2609 // If applicable, create a rib for the type parameters.
2610 self.with_generic_param_rib(
2612 ItemRibKind(HasGenericParams::Yes(generics.span)),
2613 LifetimeRibKind::Generics {
2614 span: generics.span,
2616 kind: LifetimeBinderKind::ImplBlock,
2619 // Dummy self type for better errors if `Self` is used in the trait path.
2620 this.with_self_rib(Res::SelfTyParam { trait_: LOCAL_CRATE.as_def_id() }, |this| {
2621 this.with_lifetime_rib(
2622 LifetimeRibKind::AnonymousCreateParameter {
2624 report_in_path: true
2627 // Resolve the trait reference, if necessary.
2628 this.with_optional_trait_ref(
2629 opt_trait_reference.as_ref(),
2632 let item_def_id = this.r.local_def_id(item_id);
2634 // Register the trait definitions from here.
2635 if let Some(trait_id) = trait_id {
2643 let item_def_id = item_def_id.to_def_id();
2644 let res = Res::SelfTyAlias {
2645 alias_to: item_def_id,
2646 forbid_generic: false,
2647 is_trait_impl: trait_id.is_some()
2649 this.with_self_rib(res, |this| {
2650 if let Some(trait_ref) = opt_trait_reference.as_ref() {
2651 // Resolve type arguments in the trait path.
2652 visit::walk_trait_ref(this, trait_ref);
2654 // Resolve the self type.
2655 this.visit_ty(self_type);
2656 // Resolve the generic parameters.
2657 this.visit_generics(generics);
2659 // Resolve the items within the impl.
2660 this.with_current_self_type(self_type, |this| {
2661 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
2662 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
2663 let mut seen_trait_items = Default::default();
2664 for item in impl_items {
2665 this.resolve_impl_item(&**item, &mut seen_trait_items);
2679 fn resolve_impl_item(
2681 item: &'ast AssocItem,
2682 seen_trait_items: &mut FxHashMap<DefId, Span>,
2684 use crate::ResolutionError::*;
2686 AssocItemKind::Const(_, ty, default) => {
2687 debug!("resolve_implementation AssocItemKind::Const");
2688 // If this is a trait impl, ensure the const
2690 self.check_trait_item(
2697 |i, s, c| ConstNotMemberOfTrait(i, s, c),
2701 if let Some(expr) = default {
2702 // We allow arbitrary const expressions inside of associated consts,
2703 // even if they are potentially not const evaluatable.
2705 // Type parameters can already be used and as associated consts are
2706 // not used as part of the type system, this is far less surprising.
2707 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2708 this.with_constant_rib(
2710 ConstantHasGenerics::Yes,
2712 |this| this.visit_expr(expr),
2717 AssocItemKind::Fn(box Fn { generics, .. }) => {
2718 debug!("resolve_implementation AssocItemKind::Fn");
2719 // We also need a new scope for the impl item type parameters.
2720 self.with_generic_param_rib(
2723 LifetimeRibKind::Generics {
2725 span: generics.span,
2726 kind: LifetimeBinderKind::Function,
2729 // If this is a trait impl, ensure the method
2731 this.check_trait_item(
2738 |i, s, c| MethodNotMemberOfTrait(i, s, c),
2741 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2745 AssocItemKind::Type(box TyAlias { generics, .. }) => {
2746 debug!("resolve_implementation AssocItemKind::Type");
2747 // We also need a new scope for the impl item type parameters.
2748 self.with_generic_param_rib(
2751 LifetimeRibKind::Generics {
2753 span: generics.span,
2754 kind: LifetimeBinderKind::Item,
2757 this.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2758 // If this is a trait impl, ensure the type
2760 this.check_trait_item(
2767 |i, s, c| TypeNotMemberOfTrait(i, s, c),
2770 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2775 AssocItemKind::MacCall(_) => {
2776 panic!("unexpanded macro in resolve!")
2781 fn check_trait_item<F>(
2785 kind: &AssocItemKind,
2788 seen_trait_items: &mut FxHashMap<DefId, Span>,
2791 F: FnOnce(Ident, String, Option<Symbol>) -> ResolutionError<'a>,
2793 // If there is a TraitRef in scope for an impl, then the method must be in the trait.
2794 let Some((module, _)) = &self.current_trait_ref else { return; };
2795 ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
2796 let key = self.r.new_key(ident, ns);
2797 let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2799 if binding.is_none() {
2800 // We could not find the trait item in the correct namespace.
2801 // Check the other namespace to report an error.
2807 let key = self.r.new_key(ident, ns);
2808 binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2811 let Some(binding) = binding else {
2812 // We could not find the method: report an error.
2813 let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
2814 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2815 let path_names = path_names_to_string(path);
2816 self.report_error(span, err(ident, path_names, candidate));
2820 let res = binding.res();
2821 let Res::Def(def_kind, id_in_trait) = res else { bug!() };
2823 match seen_trait_items.entry(id_in_trait) {
2824 Entry::Occupied(entry) => {
2827 ResolutionError::TraitImplDuplicate {
2829 old_span: *entry.get(),
2830 trait_item_span: binding.span,
2835 Entry::Vacant(entry) => {
2840 match (def_kind, kind) {
2841 (DefKind::AssocTy, AssocItemKind::Type(..))
2842 | (DefKind::AssocFn, AssocItemKind::Fn(..))
2843 | (DefKind::AssocConst, AssocItemKind::Const(..)) => {
2844 self.r.record_partial_res(id, PartialRes::new(res));
2850 // The method kind does not correspond to what appeared in the trait, report.
2851 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2852 let (code, kind) = match kind {
2853 AssocItemKind::Const(..) => (rustc_errors::error_code!(E0323), "const"),
2854 AssocItemKind::Fn(..) => (rustc_errors::error_code!(E0324), "method"),
2855 AssocItemKind::Type(..) => (rustc_errors::error_code!(E0325), "type"),
2856 AssocItemKind::MacCall(..) => span_bug!(span, "unexpanded macro"),
2858 let trait_path = path_names_to_string(path);
2861 ResolutionError::TraitImplMismatch {
2866 trait_item_span: binding.span,
2871 fn resolve_params(&mut self, params: &'ast [Param]) {
2872 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2873 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2874 for Param { pat, .. } in params {
2875 this.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
2878 for Param { ty, .. } in params {
2883 fn resolve_local(&mut self, local: &'ast Local) {
2884 debug!("resolving local ({:?})", local);
2885 // Resolve the type.
2886 walk_list!(self, visit_ty, &local.ty);
2888 // Resolve the initializer.
2889 if let Some((init, els)) = local.kind.init_else_opt() {
2890 self.visit_expr(init);
2892 // Resolve the `else` block
2893 if let Some(els) = els {
2894 self.visit_block(els);
2898 // Resolve the pattern.
2899 self.resolve_pattern_top(&local.pat, PatternSource::Let);
2902 /// build a map from pattern identifiers to binding-info's.
2903 /// this is done hygienically. This could arise for a macro
2904 /// that expands into an or-pattern where one 'x' was from the
2905 /// user and one 'x' came from the macro.
2906 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2907 let mut binding_map = FxHashMap::default();
2909 pat.walk(&mut |pat| {
2911 PatKind::Ident(annotation, ident, ref sub_pat)
2912 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
2914 binding_map.insert(ident, BindingInfo { span: ident.span, annotation });
2916 PatKind::Or(ref ps) => {
2917 // Check the consistency of this or-pattern and
2918 // then add all bindings to the larger map.
2919 for bm in self.check_consistent_bindings(ps) {
2920 binding_map.extend(bm);
2933 fn is_base_res_local(&self, nid: NodeId) -> bool {
2935 self.r.partial_res_map.get(&nid).map(|res| res.expect_full_res()),
2936 Some(Res::Local(..))
2940 /// Checks that all of the arms in an or-pattern have exactly the
2941 /// same set of bindings, with the same binding modes for each.
2942 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
2943 let mut missing_vars = FxHashMap::default();
2944 let mut inconsistent_vars = FxHashMap::default();
2946 // 1) Compute the binding maps of all arms.
2947 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
2949 // 2) Record any missing bindings or binding mode inconsistencies.
2950 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
2951 // Check against all arms except for the same pattern which is always self-consistent.
2955 .filter(|(_, pat)| pat.id != pat_outer.id)
2956 .flat_map(|(idx, _)| maps[idx].iter())
2957 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
2959 for (name, info, &binding_inner) in inners {
2962 // The inner binding is missing in the outer.
2964 missing_vars.entry(name).or_insert_with(|| BindingError {
2966 origin: BTreeSet::new(),
2967 target: BTreeSet::new(),
2968 could_be_path: name.as_str().starts_with(char::is_uppercase),
2970 binding_error.origin.insert(binding_inner.span);
2971 binding_error.target.insert(pat_outer.span);
2973 Some(binding_outer) => {
2974 if binding_outer.annotation != binding_inner.annotation {
2975 // The binding modes in the outer and inner bindings differ.
2978 .or_insert((binding_inner.span, binding_outer.span));
2985 // 3) Report all missing variables we found.
2986 let mut missing_vars = missing_vars.into_iter().collect::<Vec<_>>();
2987 missing_vars.sort_by_key(|&(sym, ref _err)| sym);
2989 for (name, mut v) in missing_vars.into_iter() {
2990 if inconsistent_vars.contains_key(&name) {
2991 v.could_be_path = false;
2994 *v.origin.iter().next().unwrap(),
2995 ResolutionError::VariableNotBoundInPattern(v, self.parent_scope),
2999 // 4) Report all inconsistencies in binding modes we found.
3000 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
3001 inconsistent_vars.sort();
3002 for (name, v) in inconsistent_vars {
3003 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
3006 // 5) Finally bubble up all the binding maps.
3010 /// Check the consistency of the outermost or-patterns.
3011 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
3012 pat.walk(&mut |pat| match pat.kind {
3013 PatKind::Or(ref ps) => {
3014 self.check_consistent_bindings(ps);
3021 fn resolve_arm(&mut self, arm: &'ast Arm) {
3022 self.with_rib(ValueNS, NormalRibKind, |this| {
3023 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
3024 walk_list!(this, visit_expr, &arm.guard);
3025 this.visit_expr(&arm.body);
3029 /// Arising from `source`, resolve a top level pattern.
3030 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
3031 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
3032 self.resolve_pattern(pat, pat_src, &mut bindings);
3038 pat_src: PatternSource,
3039 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3041 // We walk the pattern before declaring the pattern's inner bindings,
3042 // so that we avoid resolving a literal expression to a binding defined
3044 visit::walk_pat(self, pat);
3045 self.resolve_pattern_inner(pat, pat_src, bindings);
3046 // This has to happen *after* we determine which pat_idents are variants:
3047 self.check_consistent_bindings_top(pat);
3050 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
3054 /// A stack of sets of bindings accumulated.
3056 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
3057 /// be interpreted as re-binding an already bound binding. This results in an error.
3058 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
3059 /// in reusing this binding rather than creating a fresh one.
3061 /// When called at the top level, the stack must have a single element
3062 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
3063 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
3064 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
3065 /// When each `p_i` has been dealt with, the top set is merged with its parent.
3066 /// When a whole or-pattern has been dealt with, the thing happens.
3068 /// See the implementation and `fresh_binding` for more details.
3069 fn resolve_pattern_inner(
3072 pat_src: PatternSource,
3073 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3075 // Visit all direct subpatterns of this pattern.
3076 pat.walk(&mut |pat| {
3077 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
3079 PatKind::Ident(bmode, ident, ref sub) => {
3080 // First try to resolve the identifier as some existing entity,
3081 // then fall back to a fresh binding.
3082 let has_sub = sub.is_some();
3084 .try_resolve_as_non_binding(pat_src, bmode, ident, has_sub)
3085 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
3086 self.r.record_partial_res(pat.id, PartialRes::new(res));
3087 self.r.record_pat_span(pat.id, pat.span);
3089 PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
3090 self.smart_resolve_path(
3094 PathSource::TupleStruct(
3096 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
3100 PatKind::Path(ref qself, ref path) => {
3101 self.smart_resolve_path(pat.id, qself, path, PathSource::Pat);
3103 PatKind::Struct(ref qself, ref path, ..) => {
3104 self.smart_resolve_path(pat.id, qself, path, PathSource::Struct);
3106 PatKind::Or(ref ps) => {
3107 // Add a new set of bindings to the stack. `Or` here records that when a
3108 // binding already exists in this set, it should not result in an error because
3109 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
3110 bindings.push((PatBoundCtx::Or, Default::default()));
3112 // Now we need to switch back to a product context so that each
3113 // part of the or-pattern internally rejects already bound names.
3114 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
3115 bindings.push((PatBoundCtx::Product, Default::default()));
3116 self.resolve_pattern_inner(p, pat_src, bindings);
3117 // Move up the non-overlapping bindings to the or-pattern.
3118 // Existing bindings just get "merged".
3119 let collected = bindings.pop().unwrap().1;
3120 bindings.last_mut().unwrap().1.extend(collected);
3122 // This or-pattern itself can itself be part of a product,
3123 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
3124 // Both cases bind `a` again in a product pattern and must be rejected.
3125 let collected = bindings.pop().unwrap().1;
3126 bindings.last_mut().unwrap().1.extend(collected);
3128 // Prevent visiting `ps` as we've already done so above.
3141 pat_src: PatternSource,
3142 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3144 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
3145 // (We must not add it if it's in the bindings map because that breaks the assumptions
3146 // later passes make about or-patterns.)
3147 let ident = ident.normalize_to_macro_rules();
3149 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
3150 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
3151 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
3152 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
3153 // This is *required* for consistency which is checked later.
3154 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
3156 if already_bound_and {
3157 // Overlap in a product pattern somewhere; report an error.
3158 use ResolutionError::*;
3159 let error = match pat_src {
3160 // `fn f(a: u8, a: u8)`:
3161 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
3163 _ => IdentifierBoundMoreThanOnceInSamePattern,
3165 self.report_error(ident.span, error(ident.name));
3168 // Record as bound if it's valid:
3169 let ident_valid = ident.name != kw::Empty;
3171 bindings.last_mut().unwrap().1.insert(ident);
3174 if already_bound_or {
3175 // `Variant1(a) | Variant2(a)`, ok
3176 // Reuse definition from the first `a`.
3177 self.innermost_rib_bindings(ValueNS)[&ident]
3179 let res = Res::Local(pat_id);
3181 // A completely fresh binding add to the set if it's valid.
3182 self.innermost_rib_bindings(ValueNS).insert(ident, res);
3188 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
3189 &mut self.ribs[ns].last_mut().unwrap().bindings
3192 fn try_resolve_as_non_binding(
3194 pat_src: PatternSource,
3195 ann: BindingAnnotation,
3199 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
3200 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
3201 // also be interpreted as a path to e.g. a constant, variant, etc.
3202 let is_syntactic_ambiguity = !has_sub && ann == BindingAnnotation::NONE;
3204 let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?;
3205 let (res, binding) = match ls_binding {
3206 LexicalScopeBinding::Item(binding)
3207 if is_syntactic_ambiguity && binding.is_ambiguity() =>
3209 // For ambiguous bindings we don't know all their definitions and cannot check
3210 // whether they can be shadowed by fresh bindings or not, so force an error.
3211 // issues/33118#issuecomment-233962221 (see below) still applies here,
3212 // but we have to ignore it for backward compatibility.
3213 self.r.record_use(ident, binding, false);
3216 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
3217 LexicalScopeBinding::Res(res) => (res, None),
3221 Res::SelfCtor(_) // See #70549.
3223 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
3225 ) if is_syntactic_ambiguity => {
3226 // Disambiguate in favor of a unit struct/variant or constant pattern.
3227 if let Some(binding) = binding {
3228 self.r.record_use(ident, binding, false);
3232 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static(_), _) => {
3233 // This is unambiguously a fresh binding, either syntactically
3234 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
3235 // to something unusable as a pattern (e.g., constructor function),
3236 // but we still conservatively report an error, see
3237 // issues/33118#issuecomment-233962221 for one reason why.
3238 let binding = binding.expect("no binding for a ctor or static");
3241 ResolutionError::BindingShadowsSomethingUnacceptable {
3242 shadowing_binding: pat_src,
3244 participle: if binding.is_import() { "imported" } else { "defined" },
3245 article: binding.res().article(),
3246 shadowed_binding: binding.res(),
3247 shadowed_binding_span: binding.span,
3252 Res::Def(DefKind::ConstParam, def_id) => {
3253 // Same as for DefKind::Const above, but here, `binding` is `None`, so we
3254 // have to construct the error differently
3257 ResolutionError::BindingShadowsSomethingUnacceptable {
3258 shadowing_binding: pat_src,
3260 participle: "defined",
3261 article: res.article(),
3262 shadowed_binding: res,
3263 shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"),
3268 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
3269 // These entities are explicitly allowed to be shadowed by fresh bindings.
3272 Res::SelfCtor(_) => {
3273 // We resolve `Self` in pattern position as an ident sometimes during recovery,
3274 // so delay a bug instead of ICEing.
3275 self.r.session.delay_span_bug(
3277 "unexpected `SelfCtor` in pattern, expected identifier"
3283 "unexpected resolution for an identifier in pattern: {:?}",
3289 // High-level and context dependent path resolution routine.
3290 // Resolves the path and records the resolution into definition map.
3291 // If resolution fails tries several techniques to find likely
3292 // resolution candidates, suggest imports or other help, and report
3293 // errors in user friendly way.
3294 fn smart_resolve_path(
3297 qself: &Option<P<QSelf>>,
3299 source: PathSource<'ast>,
3301 self.smart_resolve_path_fragment(
3303 &Segment::from_path(path),
3305 Finalize::new(id, path.span),
3309 fn smart_resolve_path_fragment(
3311 qself: &Option<P<QSelf>>,
3313 source: PathSource<'ast>,
3317 "smart_resolve_path_fragment(qself={:?}, path={:?}, finalize={:?})",
3318 qself, path, finalize,
3320 let ns = source.namespace();
3322 let Finalize { node_id, path_span, .. } = finalize;
3323 let report_errors = |this: &mut Self, res: Option<Res>| {
3324 if this.should_report_errs() {
3325 let (err, candidates) =
3326 this.smart_resolve_report_errors(path, path_span, source, res);
3328 let def_id = this.parent_scope.module.nearest_parent_mod();
3329 let instead = res.is_some();
3331 if res.is_none() { this.report_missing_type_error(path) } else { None };
3333 this.r.use_injections.push(UseError {
3340 is_call: source.is_call(),
3344 PartialRes::new(Res::Err)
3347 // For paths originating from calls (like in `HashMap::new()`), tries
3348 // to enrich the plain `failed to resolve: ...` message with hints
3349 // about possible missing imports.
3351 // Similar thing, for types, happens in `report_errors` above.
3352 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
3353 if !source.is_call() {
3354 return Some(parent_err);
3357 // Before we start looking for candidates, we have to get our hands
3358 // on the type user is trying to perform invocation on; basically:
3359 // we're transforming `HashMap::new` into just `HashMap`.
3360 let path = match path.split_last() {
3361 Some((_, path)) if !path.is_empty() => path,
3362 _ => return Some(parent_err),
3365 let (mut err, candidates) =
3366 this.smart_resolve_report_errors(path, path_span, PathSource::Type, None);
3368 // There are two different error messages user might receive at
3370 // - E0412 cannot find type `{}` in this scope
3371 // - E0433 failed to resolve: use of undeclared type or module `{}`
3373 // The first one is emitted for paths in type-position, and the
3374 // latter one - for paths in expression-position.
3376 // Thus (since we're in expression-position at this point), not to
3377 // confuse the user, we want to keep the *message* from E0433 (so
3378 // `parent_err`), but we want *hints* from E0412 (so `err`).
3380 // And that's what happens below - we're just mixing both messages
3381 // into a single one.
3382 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
3384 // overwrite all properties with the parent's error message
3385 err.message = take(&mut parent_err.message);
3386 err.code = take(&mut parent_err.code);
3387 swap(&mut err.span, &mut parent_err.span);
3388 err.children = take(&mut parent_err.children);
3389 err.sort_span = parent_err.sort_span;
3390 err.is_lint = parent_err.is_lint;
3392 // merge the parent's suggestions with the typo suggestions
3393 fn append_result<T, E>(res1: &mut Result<Vec<T>, E>, res2: Result<Vec<T>, E>) {
3395 Ok(vec1) => match res2 {
3396 Ok(mut vec2) => vec1.append(&mut vec2),
3397 Err(e) => *res1 = Err(e),
3402 append_result(&mut err.suggestions, parent_err.suggestions.clone());
3404 parent_err.cancel();
3406 let def_id = this.parent_scope.module.nearest_parent_mod();
3408 if this.should_report_errs() {
3409 if candidates.is_empty() {
3410 // When there is no suggested imports, we can just emit the error
3411 // and suggestions immediately. Note that we bypass the usually error
3412 // reporting routine (ie via `self.r.report_error`) because we need
3413 // to post-process the `ResolutionError` above.
3416 // If there are suggested imports, the error reporting is delayed
3417 this.r.use_injections.push(UseError {
3424 is_call: source.is_call(),
3431 // We don't return `Some(parent_err)` here, because the error will
3432 // be already printed either immediately or as part of the `use` injections
3436 let partial_res = match self.resolve_qpath_anywhere(
3441 source.defer_to_typeck(),
3444 Ok(Some(partial_res)) if let Some(res) = partial_res.full_res() => {
3445 if source.is_expected(res) || res == Res::Err {
3448 report_errors(self, Some(res))
3452 Ok(Some(partial_res)) if source.defer_to_typeck() => {
3453 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
3454 // or `<T>::A::B`. If `B` should be resolved in value namespace then
3455 // it needs to be added to the trait map.
3457 let item_name = path.last().unwrap().ident;
3458 let traits = self.traits_in_scope(item_name, ns);
3459 self.r.trait_map.insert(node_id, traits);
3462 if PrimTy::from_name(path[0].ident.name).is_some() {
3463 let mut std_path = Vec::with_capacity(1 + path.len());
3465 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
3466 std_path.extend(path);
3467 if let PathResult::Module(_) | PathResult::NonModule(_) =
3468 self.resolve_path(&std_path, Some(ns), None)
3470 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
3472 path.iter().last().map_or(path_span, |segment| segment.ident.span);
3474 self.r.confused_type_with_std_module.insert(item_span, path_span);
3475 self.r.confused_type_with_std_module.insert(path_span, path_span);
3483 if let Some(err) = report_errors_for_call(self, err) {
3484 self.report_error(err.span, err.node);
3487 PartialRes::new(Res::Err)
3490 _ => report_errors(self, None),
3493 if !matches!(source, PathSource::TraitItem(..)) {
3494 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
3495 self.r.record_partial_res(node_id, partial_res);
3496 self.resolve_elided_lifetimes_in_path(node_id, partial_res, path, source, path_span);
3502 fn self_type_is_available(&mut self) -> bool {
3504 .maybe_resolve_ident_in_lexical_scope(Ident::with_dummy_span(kw::SelfUpper), TypeNS);
3505 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3508 fn self_value_is_available(&mut self, self_span: Span) -> bool {
3509 let ident = Ident::new(kw::SelfLower, self_span);
3510 let binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS);
3511 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3514 /// A wrapper around [`Resolver::report_error`].
3516 /// This doesn't emit errors for function bodies if this is rustdoc.
3517 fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) {
3518 if self.should_report_errs() {
3519 self.r.report_error(span, resolution_error);
3524 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
3525 fn should_report_errs(&self) -> bool {
3526 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
3529 // Resolve in alternative namespaces if resolution in the primary namespace fails.
3530 fn resolve_qpath_anywhere(
3532 qself: &Option<P<QSelf>>,
3534 primary_ns: Namespace,
3536 defer_to_typeck: bool,
3538 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3539 let mut fin_res = None;
3541 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
3542 if i == 0 || ns != primary_ns {
3543 match self.resolve_qpath(qself, path, ns, finalize)? {
3545 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
3547 return Ok(Some(partial_res));
3550 if fin_res.is_none() {
3551 fin_res = partial_res;
3558 assert!(primary_ns != MacroNS);
3560 if qself.is_none() {
3561 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
3562 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
3563 if let Ok((_, res)) =
3564 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
3566 return Ok(Some(PartialRes::new(res)));
3573 /// Handles paths that may refer to associated items.
3576 qself: &Option<P<QSelf>>,
3580 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3582 "resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})",
3583 qself, path, ns, finalize,
3586 if let Some(qself) = qself {
3587 if qself.position == 0 {
3588 // This is a case like `<T>::B`, where there is no
3589 // trait to resolve. In that case, we leave the `B`
3590 // segment to be resolved by type-check.
3591 return Ok(Some(PartialRes::with_unresolved_segments(
3592 Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()),
3597 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
3599 // Currently, `path` names the full item (`A::B::C`, in
3600 // our example). so we extract the prefix of that that is
3601 // the trait (the slice upto and including
3602 // `qself.position`). And then we recursively resolve that,
3603 // but with `qself` set to `None`.
3604 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
3605 let partial_res = self.smart_resolve_path_fragment(
3607 &path[..=qself.position],
3608 PathSource::TraitItem(ns),
3609 Finalize::with_root_span(finalize.node_id, finalize.path_span, qself.path_span),
3612 // The remaining segments (the `C` in our example) will
3613 // have to be resolved by type-check, since that requires doing
3614 // trait resolution.
3615 return Ok(Some(PartialRes::with_unresolved_segments(
3616 partial_res.base_res(),
3617 partial_res.unresolved_segments() + path.len() - qself.position - 1,
3621 let result = match self.resolve_path(&path, Some(ns), Some(finalize)) {
3622 PathResult::NonModule(path_res) => path_res,
3623 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
3624 PartialRes::new(module.res().unwrap())
3626 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
3627 // don't report an error right away, but try to fallback to a primitive type.
3628 // So, we are still able to successfully resolve something like
3630 // use std::u8; // bring module u8 in scope
3631 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
3632 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
3633 // // not to non-existent std::u8::max_value
3636 // Such behavior is required for backward compatibility.
3637 // The same fallback is used when `a` resolves to nothing.
3638 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
3639 if (ns == TypeNS || path.len() > 1)
3640 && PrimTy::from_name(path[0].ident.name).is_some() =>
3642 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
3643 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
3645 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3646 PartialRes::new(module.res().unwrap())
3648 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
3649 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
3651 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
3652 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
3656 && let Some(res) = result.full_res()
3658 && path[0].ident.name != kw::PathRoot
3659 && path[0].ident.name != kw::DollarCrate
3661 let unqualified_result = {
3662 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
3663 PathResult::NonModule(path_res) => path_res.expect_full_res(),
3664 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3665 module.res().unwrap()
3667 _ => return Ok(Some(result)),
3670 if res == unqualified_result {
3671 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
3672 self.r.lint_buffer.buffer_lint(
3676 "unnecessary qualification",
3684 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
3685 if let Some(label) = label {
3686 if label.ident.as_str().as_bytes()[1] != b'_' {
3687 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
3690 if let Ok((_, orig_span)) = self.resolve_label(label.ident) {
3691 diagnostics::signal_label_shadowing(self.r.session, orig_span, label.ident)
3694 self.with_label_rib(NormalRibKind, |this| {
3695 let ident = label.ident.normalize_to_macro_rules();
3696 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
3704 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
3705 self.with_resolved_label(label, id, |this| this.visit_block(block));
3708 fn resolve_block(&mut self, block: &'ast Block) {
3709 debug!("(resolving block) entering block");
3710 // Move down in the graph, if there's an anonymous module rooted here.
3711 let orig_module = self.parent_scope.module;
3712 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
3714 let mut num_macro_definition_ribs = 0;
3715 if let Some(anonymous_module) = anonymous_module {
3716 debug!("(resolving block) found anonymous module, moving down");
3717 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3718 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3719 self.parent_scope.module = anonymous_module;
3721 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3724 let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
3725 if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
3726 (block.could_be_bare_literal, &block.stmts[..])
3727 && let ExprKind::Type(..) = expr.kind
3729 self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
3732 // Descend into the block.
3733 for stmt in &block.stmts {
3734 if let StmtKind::Item(ref item) = stmt.kind
3735 && let ItemKind::MacroDef(..) = item.kind {
3736 num_macro_definition_ribs += 1;
3737 let res = self.r.local_def_id(item.id).to_def_id();
3738 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
3739 self.label_ribs.push(Rib::new(MacroDefinition(res)));
3742 self.visit_stmt(stmt);
3744 self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
3747 self.parent_scope.module = orig_module;
3748 for _ in 0..num_macro_definition_ribs {
3749 self.ribs[ValueNS].pop();
3750 self.label_ribs.pop();
3752 self.ribs[ValueNS].pop();
3753 if anonymous_module.is_some() {
3754 self.ribs[TypeNS].pop();
3756 debug!("(resolving block) leaving block");
3759 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
3760 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
3761 self.with_constant_rib(
3763 if constant.value.is_potential_trivial_const_param() {
3764 ConstantHasGenerics::Yes
3766 ConstantHasGenerics::No
3769 |this| visit::walk_anon_const(this, constant),
3773 fn resolve_inline_const(&mut self, constant: &'ast AnonConst) {
3774 debug!("resolve_anon_const {constant:?}");
3775 self.with_constant_rib(IsRepeatExpr::No, ConstantHasGenerics::Yes, None, |this| {
3776 visit::walk_anon_const(this, constant)
3780 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
3781 // First, record candidate traits for this expression if it could
3782 // result in the invocation of a method call.
3784 self.record_candidate_traits_for_expr_if_necessary(expr);
3786 // Next, resolve the node.
3788 ExprKind::Path(ref qself, ref path) => {
3789 self.smart_resolve_path(expr.id, qself, path, PathSource::Expr(parent));
3790 visit::walk_expr(self, expr);
3793 ExprKind::Struct(ref se) => {
3794 self.smart_resolve_path(expr.id, &se.qself, &se.path, PathSource::Struct);
3795 visit::walk_expr(self, expr);
3798 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
3799 match self.resolve_label(label.ident) {
3800 Ok((node_id, _)) => {
3801 // Since this res is a label, it is never read.
3802 self.r.label_res_map.insert(expr.id, node_id);
3803 self.diagnostic_metadata.unused_labels.remove(&node_id);
3806 self.report_error(label.ident.span, error);
3810 // visit `break` argument if any
3811 visit::walk_expr(self, expr);
3814 ExprKind::Break(None, Some(ref e)) => {
3815 // We use this instead of `visit::walk_expr` to keep the parent expr around for
3816 // better diagnostics.
3817 self.resolve_expr(e, Some(&expr));
3820 ExprKind::Let(ref pat, ref scrutinee, _) => {
3821 self.visit_expr(scrutinee);
3822 self.resolve_pattern_top(pat, PatternSource::Let);
3825 ExprKind::If(ref cond, ref then, ref opt_else) => {
3826 self.with_rib(ValueNS, NormalRibKind, |this| {
3827 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3828 this.visit_expr(cond);
3829 this.diagnostic_metadata.in_if_condition = old;
3830 this.visit_block(then);
3832 if let Some(expr) = opt_else {
3833 self.visit_expr(expr);
3837 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3839 ExprKind::While(ref cond, ref block, label) => {
3840 self.with_resolved_label(label, expr.id, |this| {
3841 this.with_rib(ValueNS, NormalRibKind, |this| {
3842 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3843 this.visit_expr(cond);
3844 this.diagnostic_metadata.in_if_condition = old;
3845 this.visit_block(block);
3850 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
3851 self.visit_expr(iter_expr);
3852 self.with_rib(ValueNS, NormalRibKind, |this| {
3853 this.resolve_pattern_top(pat, PatternSource::For);
3854 this.resolve_labeled_block(label, expr.id, block);
3858 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
3860 // Equivalent to `visit::walk_expr` + passing some context to children.
3861 ExprKind::Field(ref subexpression, _) => {
3862 self.resolve_expr(subexpression, Some(expr));
3864 ExprKind::MethodCall(box MethodCall { ref seg, ref receiver, ref args, .. }) => {
3865 self.resolve_expr(receiver, Some(expr));
3867 self.resolve_expr(arg, None);
3869 self.visit_path_segment(seg);
3872 ExprKind::Call(ref callee, ref arguments) => {
3873 self.resolve_expr(callee, Some(expr));
3874 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
3875 for (idx, argument) in arguments.iter().enumerate() {
3876 // Constant arguments need to be treated as AnonConst since
3877 // that is how they will be later lowered to HIR.
3878 if const_args.contains(&idx) {
3879 self.with_constant_rib(
3881 if argument.is_potential_trivial_const_param() {
3882 ConstantHasGenerics::Yes
3884 ConstantHasGenerics::No
3888 this.resolve_expr(argument, None);
3892 self.resolve_expr(argument, None);
3896 ExprKind::Type(ref type_expr, ref ty) => {
3897 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
3898 // type ascription. Here we are trying to retrieve the span of the colon token as
3899 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
3900 // with `expr::Ty`, only in this case it will match the span from
3901 // `type_ascription_path_suggestions`.
3902 self.diagnostic_metadata
3903 .current_type_ascription
3904 .push(type_expr.span.between(ty.span));
3905 visit::walk_expr(self, expr);
3906 self.diagnostic_metadata.current_type_ascription.pop();
3908 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
3909 // resolve the arguments within the proper scopes so that usages of them inside the
3910 // closure are detected as upvars rather than normal closure arg usages.
3911 ExprKind::Closure(box ast::Closure {
3912 asyncness: Async::Yes { .. },
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(box ast::Closure {
3937 binder: ClosureBinder::For { ref generic_params, span },
3940 self.with_generic_param_rib(
3943 LifetimeRibKind::Generics {
3945 kind: LifetimeBinderKind::Closure,
3948 |this| visit::walk_expr(this, expr),
3951 ExprKind::Closure(..) => visit::walk_expr(self, expr),
3952 ExprKind::Async(..) => {
3953 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
3955 ExprKind::Repeat(ref elem, ref ct) => {
3956 self.visit_expr(elem);
3957 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
3958 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
3959 this.resolve_anon_const(ct, IsRepeatExpr::Yes)
3963 ExprKind::ConstBlock(ref ct) => {
3964 self.resolve_inline_const(ct);
3966 ExprKind::Index(ref elem, ref idx) => {
3967 self.resolve_expr(elem, Some(expr));
3968 self.visit_expr(idx);
3970 ExprKind::Assign(ref lhs, ref rhs, _) => {
3971 if !self.diagnostic_metadata.is_assign_rhs {
3972 self.diagnostic_metadata.in_assignment = Some(expr);
3974 self.visit_expr(lhs);
3975 self.diagnostic_metadata.is_assign_rhs = true;
3976 self.diagnostic_metadata.in_assignment = None;
3977 self.visit_expr(rhs);
3978 self.diagnostic_metadata.is_assign_rhs = false;
3981 visit::walk_expr(self, expr);
3986 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
3988 ExprKind::Field(_, ident) => {
3989 // FIXME(#6890): Even though you can't treat a method like a
3990 // field, we need to add any trait methods we find that match
3991 // the field name so that we can do some nice error reporting
3992 // later on in typeck.
3993 let traits = self.traits_in_scope(ident, ValueNS);
3994 self.r.trait_map.insert(expr.id, traits);
3996 ExprKind::MethodCall(ref call) => {
3997 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
3998 let traits = self.traits_in_scope(call.seg.ident, ValueNS);
3999 self.r.trait_map.insert(expr.id, traits);
4007 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
4008 self.r.traits_in_scope(
4009 self.current_trait_ref.as_ref().map(|(module, _)| *module),
4012 Some((ident.name, ns)),
4016 /// Construct the list of in-scope lifetime parameters for async lowering.
4017 /// We include all lifetime parameters, either named or "Fresh".
4018 /// The order of those parameters does not matter, as long as it is
4020 fn record_lifetime_params_for_async(
4023 async_node_id: Option<(NodeId, Span)>,
4025 if let Some((async_node_id, span)) = async_node_id {
4026 let mut extra_lifetime_params =
4027 self.r.extra_lifetime_params_map.get(&fn_id).cloned().unwrap_or_default();
4028 for rib in self.lifetime_ribs.iter().rev() {
4029 extra_lifetime_params.extend(
4030 rib.bindings.iter().map(|(&ident, &(node_id, res))| (ident, node_id, res)),
4033 LifetimeRibKind::Item => break,
4034 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
4035 if let Some(earlier_fresh) = self.r.extra_lifetime_params_map.get(&binder) {
4036 extra_lifetime_params.extend(earlier_fresh);
4039 LifetimeRibKind::Generics { .. } => {}
4041 // We are in a function definition. We should only find `Generics`
4042 // and `AnonymousCreateParameter` inside the innermost `Item`.
4043 span_bug!(span, "unexpected rib kind: {:?}", rib.kind)
4047 self.r.extra_lifetime_params_map.insert(async_node_id, extra_lifetime_params);
4052 struct LifetimeCountVisitor<'a, 'b> {
4053 r: &'b mut Resolver<'a>,
4056 /// Walks the whole crate in DFS order, visiting each item, counting the declared number of
4057 /// lifetime generic parameters.
4058 impl<'ast> Visitor<'ast> for LifetimeCountVisitor<'_, '_> {
4059 fn visit_item(&mut self, item: &'ast Item) {
4061 ItemKind::TyAlias(box TyAlias { ref generics, .. })
4062 | ItemKind::Fn(box Fn { ref generics, .. })
4063 | ItemKind::Enum(_, ref generics)
4064 | ItemKind::Struct(_, ref generics)
4065 | ItemKind::Union(_, ref generics)
4066 | ItemKind::Impl(box Impl { ref generics, .. })
4067 | ItemKind::Trait(box Trait { ref generics, .. })
4068 | ItemKind::TraitAlias(ref generics, _) => {
4069 let def_id = self.r.local_def_id(item.id);
4070 let count = generics
4073 .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
4075 self.r.item_generics_num_lifetimes.insert(def_id, count);
4079 | ItemKind::ForeignMod(..)
4080 | ItemKind::Static(..)
4081 | ItemKind::Const(..)
4083 | ItemKind::ExternCrate(..)
4084 | ItemKind::MacroDef(..)
4085 | ItemKind::GlobalAsm(..)
4086 | ItemKind::MacCall(..) => {}
4088 visit::walk_item(self, item)
4092 impl<'a> Resolver<'a> {
4093 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
4094 visit::walk_crate(&mut LifetimeCountVisitor { r: self }, krate);
4095 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
4096 visit::walk_crate(&mut late_resolution_visitor, krate);
4097 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
4098 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");