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};
23 use rustc_hir::{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::collections::{hash_map::Entry, BTreeSet};
34 use std::mem::{replace, take};
37 pub(crate) mod lifetimes;
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 binding_mode: BindingMode,
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 /// This rib acts as a barrier to forbid reference to lifetimes of a parent item.
231 /// This rib declares generic parameters.
232 Generics { binder: NodeId, span: Span, kind: LifetimeBinderKind },
234 /// FIXME(const_generics): This patches over an ICE caused by non-'static lifetimes in const
235 /// generics. We are disallowing this until we can decide on how we want to handle non-'static
236 /// lifetimes in const generics. See issue #74052 for discussion.
239 /// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`.
240 /// This function will emit an error if `generic_const_exprs` is not enabled, the body identified by
241 /// `body_id` is an anonymous constant and `lifetime_ref` is non-static.
244 /// Create a new anonymous lifetime parameter and reference it.
246 /// If `report_in_path`, report an error when encountering lifetime elision in a path:
248 /// struct Foo<'a> { x: &'a () }
249 /// async fn foo(x: Foo) {}
252 /// Note: the error should not trigger when the elided lifetime is in a pattern or
253 /// expression-position path:
255 /// struct Foo<'a> { x: &'a () }
256 /// async fn foo(Foo { x: _ }: Foo<'_>) {}
258 AnonymousCreateParameter { binder: NodeId, report_in_path: bool },
260 /// Give a hard error when either `&` or `'_` is written. Used to
261 /// rule out things like `where T: Foo<'_>`. Does not imply an
262 /// error on default object bounds (e.g., `Box<dyn Foo>`).
263 AnonymousReportError,
265 /// Replace all anonymous lifetimes by provided lifetime.
268 /// Signal we cannot find which should be the anonymous lifetime.
272 #[derive(Copy, Clone, Debug)]
273 enum LifetimeBinderKind {
283 impl LifetimeBinderKind {
284 fn descr(self) -> &'static str {
285 use LifetimeBinderKind::*;
287 BareFnType => "type",
288 PolyTrait => "bound",
289 WhereBound => "bound",
291 ImplBlock => "impl block",
292 Function => "function",
293 Closure => "closure",
300 kind: LifetimeRibKind,
301 // We need to preserve insertion order for async fns.
302 bindings: FxIndexMap<Ident, (NodeId, LifetimeRes)>,
306 fn new(kind: LifetimeRibKind) -> LifetimeRib {
307 LifetimeRib { bindings: Default::default(), kind }
311 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
312 pub(crate) enum AliasPossibility {
317 #[derive(Copy, Clone, Debug)]
318 pub(crate) enum PathSource<'a> {
319 // Type paths `Path`.
321 // Trait paths in bounds or impls.
322 Trait(AliasPossibility),
323 // Expression paths `path`, with optional parent context.
324 Expr(Option<&'a Expr>),
325 // Paths in path patterns `Path`.
327 // Paths in struct expressions and patterns `Path { .. }`.
329 // Paths in tuple struct patterns `Path(..)`.
330 TupleStruct(Span, &'a [Span]),
331 // `m::A::B` in `<T as m::A>::B::C`.
332 TraitItem(Namespace),
335 impl<'a> PathSource<'a> {
336 fn namespace(self) -> Namespace {
338 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
339 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
340 PathSource::TraitItem(ns) => ns,
344 fn defer_to_typeck(self) -> bool {
347 | PathSource::Expr(..)
350 | PathSource::TupleStruct(..) => true,
351 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
355 fn descr_expected(self) -> &'static str {
357 PathSource::Type => "type",
358 PathSource::Trait(_) => "trait",
359 PathSource::Pat => "unit struct, unit variant or constant",
360 PathSource::Struct => "struct, variant or union type",
361 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
362 PathSource::TraitItem(ns) => match ns {
363 TypeNS => "associated type",
364 ValueNS => "method or associated constant",
365 MacroNS => bug!("associated macro"),
367 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
368 // "function" here means "anything callable" rather than `DefKind::Fn`,
369 // this is not precise but usually more helpful than just "value".
370 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
371 // the case of `::some_crate()`
372 ExprKind::Path(_, path)
373 if path.segments.len() == 2
374 && path.segments[0].ident.name == kw::PathRoot =>
378 ExprKind::Path(_, path) => {
379 let mut msg = "function";
380 if let Some(segment) = path.segments.iter().last() {
381 if let Some(c) = segment.ident.to_string().chars().next() {
382 if c.is_uppercase() {
383 msg = "function, tuple struct or tuple variant";
396 fn is_call(self) -> bool {
397 matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
400 pub(crate) fn is_expected(self, res: Res) -> bool {
402 PathSource::Type => matches!(
409 | DefKind::TraitAlias
414 | DefKind::ForeignTy,
419 PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
420 PathSource::Trait(AliasPossibility::Maybe) => {
421 matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
423 PathSource::Expr(..) => matches!(
426 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
431 | DefKind::AssocConst
432 | DefKind::ConstParam,
438 res.expected_in_unit_struct_pat()
439 || matches!(res, Res::Def(DefKind::Const | DefKind::AssocConst, _))
441 PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
442 PathSource::Struct => matches!(
451 ) | Res::SelfTy { .. }
453 PathSource::TraitItem(ns) => match res {
454 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
455 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
461 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
462 use rustc_errors::error_code;
463 match (self, has_unexpected_resolution) {
464 (PathSource::Trait(_), true) => error_code!(E0404),
465 (PathSource::Trait(_), false) => error_code!(E0405),
466 (PathSource::Type, true) => error_code!(E0573),
467 (PathSource::Type, false) => error_code!(E0412),
468 (PathSource::Struct, true) => error_code!(E0574),
469 (PathSource::Struct, false) => error_code!(E0422),
470 (PathSource::Expr(..), true) => error_code!(E0423),
471 (PathSource::Expr(..), false) => error_code!(E0425),
472 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
473 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
474 (PathSource::TraitItem(..), true) => error_code!(E0575),
475 (PathSource::TraitItem(..), false) => error_code!(E0576),
481 struct DiagnosticMetadata<'ast> {
482 /// The current trait's associated items' ident, used for diagnostic suggestions.
483 current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
485 /// The current self type if inside an impl (used for better errors).
486 current_self_type: Option<Ty>,
488 /// The current self item if inside an ADT (used for better errors).
489 current_self_item: Option<NodeId>,
491 /// The current trait (used to suggest).
492 current_item: Option<&'ast Item>,
494 /// When processing generics and encountering a type not found, suggest introducing a type
496 currently_processing_generics: bool,
498 /// The current enclosing (non-closure) function (used for better errors).
499 current_function: Option<(FnKind<'ast>, Span)>,
501 /// A list of labels as of yet unused. Labels will be removed from this map when
502 /// they are used (in a `break` or `continue` statement)
503 unused_labels: FxHashMap<NodeId, Span>,
505 /// Only used for better errors on `fn(): fn()`.
506 current_type_ascription: Vec<Span>,
508 /// Only used for better errors on `let x = { foo: bar };`.
509 /// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only
510 /// needed for cases where this parses as a correct type ascription.
511 current_block_could_be_bare_struct_literal: Option<Span>,
513 /// Only used for better errors on `let <pat>: <expr, not type>;`.
514 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
516 /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
517 in_if_condition: Option<&'ast Expr>,
519 /// If we are currently in a trait object definition. Used to point at the bounds when
520 /// encountering a struct or enum.
521 current_trait_object: Option<&'ast [ast::GenericBound]>,
523 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
524 current_where_predicate: Option<&'ast WherePredicate>,
526 current_type_path: Option<&'ast Ty>,
528 /// The current impl items (used to suggest).
529 current_impl_items: Option<&'ast [P<AssocItem>]>,
531 /// When processing impl trait
532 currently_processing_impl_trait: Option<(TraitRef, Ty)>,
534 /// Accumulate the errors due to missed lifetime elision,
535 /// and report them all at once for each function.
536 current_elision_failures: Vec<MissingLifetime>,
539 struct LateResolutionVisitor<'a, 'b, 'ast> {
540 r: &'b mut Resolver<'a>,
542 /// The module that represents the current item scope.
543 parent_scope: ParentScope<'a>,
545 /// The current set of local scopes for types and values.
546 /// FIXME #4948: Reuse ribs to avoid allocation.
547 ribs: PerNS<Vec<Rib<'a>>>,
549 /// The current set of local scopes, for labels.
550 label_ribs: Vec<Rib<'a, NodeId>>,
552 /// The current set of local scopes for lifetimes.
553 lifetime_ribs: Vec<LifetimeRib>,
555 /// We are looking for lifetimes in an elision context.
556 /// The set contains all the resolutions that we encountered so far.
557 /// They will be used to determine the correct lifetime for the fn return type.
558 /// The `LifetimeElisionCandidate` is used for diagnostics, to suggest introducing named
560 lifetime_elision_candidates: Option<FxIndexMap<LifetimeRes, LifetimeElisionCandidate>>,
562 /// The trait that the current context can refer to.
563 current_trait_ref: Option<(Module<'a>, TraitRef)>,
565 /// Fields used to add information to diagnostic errors.
566 diagnostic_metadata: Box<DiagnosticMetadata<'ast>>,
568 /// State used to know whether to ignore resolution errors for function bodies.
570 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
571 /// In most cases this will be `None`, in which case errors will always be reported.
572 /// If it is `true`, then it will be updated when entering a nested function or trait body.
575 /// Count the number of places a lifetime is used.
576 lifetime_uses: FxHashMap<LocalDefId, LifetimeUseSet>,
579 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
580 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
581 fn visit_attribute(&mut self, _: &'ast Attribute) {
582 // We do not want to resolve expressions that appear in attributes,
583 // as they do not correspond to actual code.
585 fn visit_item(&mut self, item: &'ast Item) {
586 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
587 // Always report errors in items we just entered.
588 let old_ignore = replace(&mut self.in_func_body, false);
589 self.with_lifetime_rib(LifetimeRibKind::Item, |this| this.resolve_item(item));
590 self.in_func_body = old_ignore;
591 self.diagnostic_metadata.current_item = prev;
593 fn visit_arm(&mut self, arm: &'ast Arm) {
594 self.resolve_arm(arm);
596 fn visit_block(&mut self, block: &'ast Block) {
597 self.resolve_block(block);
599 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
600 // We deal with repeat expressions explicitly in `resolve_expr`.
601 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
602 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
603 this.resolve_anon_const(constant, IsRepeatExpr::No);
607 fn visit_expr(&mut self, expr: &'ast Expr) {
608 self.resolve_expr(expr, None);
610 fn visit_local(&mut self, local: &'ast Local) {
611 let local_spans = match local.pat.kind {
612 // We check for this to avoid tuple struct fields.
613 PatKind::Wild => None,
616 local.ty.as_ref().map(|ty| ty.span),
617 local.kind.init().map(|init| init.span),
620 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
621 self.resolve_local(local);
622 self.diagnostic_metadata.current_let_binding = original;
624 fn visit_ty(&mut self, ty: &'ast Ty) {
625 let prev = self.diagnostic_metadata.current_trait_object;
626 let prev_ty = self.diagnostic_metadata.current_type_path;
628 TyKind::Rptr(None, _) => {
629 // Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
631 // This span will be used in case of elision failure.
632 let span = self.r.session.source_map().start_point(ty.span);
633 self.resolve_elided_lifetime(ty.id, span);
634 visit::walk_ty(self, ty);
636 TyKind::Path(ref qself, ref path) => {
637 self.diagnostic_metadata.current_type_path = Some(ty);
638 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
640 // Check whether we should interpret this as a bare trait object.
642 && let Some(partial_res) = self.r.partial_res_map.get(&ty.id)
643 && partial_res.unresolved_segments() == 0
644 && let Res::Def(DefKind::Trait | DefKind::TraitAlias, _) = partial_res.base_res()
646 // This path is actually a bare trait object. In case of a bare `Fn`-trait
647 // object with anonymous lifetimes, we need this rib to correctly place the
648 // synthetic lifetimes.
649 let span = ty.span.shrink_to_lo().to(path.span.shrink_to_lo());
650 self.with_generic_param_rib(
653 LifetimeRibKind::Generics {
655 kind: LifetimeBinderKind::PolyTrait,
658 |this| this.visit_path(&path, ty.id),
661 visit::walk_ty(self, ty)
664 TyKind::ImplicitSelf => {
665 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
667 .resolve_ident_in_lexical_scope(
670 Some(Finalize::new(ty.id, ty.span)),
673 .map_or(Res::Err, |d| d.res());
674 self.r.record_partial_res(ty.id, PartialRes::new(res));
675 visit::walk_ty(self, ty)
677 TyKind::ImplTrait(..) => {
678 let candidates = self.lifetime_elision_candidates.take();
679 visit::walk_ty(self, ty);
680 self.lifetime_elision_candidates = candidates;
682 TyKind::TraitObject(ref bounds, ..) => {
683 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
684 visit::walk_ty(self, ty)
686 TyKind::BareFn(ref bare_fn) => {
687 let span = ty.span.shrink_to_lo().to(bare_fn.decl_span.shrink_to_lo());
688 self.with_generic_param_rib(
689 &bare_fn.generic_params,
691 LifetimeRibKind::Generics {
693 kind: LifetimeBinderKind::BareFnType,
697 this.visit_generic_params(&bare_fn.generic_params, false);
698 this.with_lifetime_rib(
699 LifetimeRibKind::AnonymousCreateParameter {
701 report_in_path: false,
704 this.resolve_fn_signature(
707 // We don't need to deal with patterns in parameters, because
708 // they are not possible for foreign or bodiless functions.
713 .map(|Param { ty, .. }| (None, &**ty)),
714 &bare_fn.decl.output,
721 _ => visit::walk_ty(self, ty),
723 self.diagnostic_metadata.current_trait_object = prev;
724 self.diagnostic_metadata.current_type_path = prev_ty;
726 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef) {
727 let span = tref.span.shrink_to_lo().to(tref.trait_ref.path.span.shrink_to_lo());
728 self.with_generic_param_rib(
729 &tref.bound_generic_params,
731 LifetimeRibKind::Generics {
732 binder: tref.trait_ref.ref_id,
733 kind: LifetimeBinderKind::PolyTrait,
737 this.visit_generic_params(&tref.bound_generic_params, false);
738 this.smart_resolve_path(
739 tref.trait_ref.ref_id,
741 &tref.trait_ref.path,
742 PathSource::Trait(AliasPossibility::Maybe),
744 this.visit_trait_ref(&tref.trait_ref);
748 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
749 match foreign_item.kind {
750 ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
751 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
752 this.with_generic_param_rib(
754 ItemRibKind(HasGenericParams::Yes(generics.span)),
755 LifetimeRibKind::Generics {
756 binder: foreign_item.id,
757 kind: LifetimeBinderKind::Item,
760 |this| visit::walk_foreign_item(this, foreign_item),
764 ForeignItemKind::Fn(box Fn { ref generics, .. }) => {
765 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
766 this.with_generic_param_rib(
768 ItemRibKind(HasGenericParams::Yes(generics.span)),
769 LifetimeRibKind::Generics {
770 binder: foreign_item.id,
771 kind: LifetimeBinderKind::Function,
774 |this| visit::walk_foreign_item(this, foreign_item),
778 ForeignItemKind::Static(..) => {
779 self.with_item_rib(|this| {
780 visit::walk_foreign_item(this, foreign_item);
783 ForeignItemKind::MacCall(..) => {
784 panic!("unexpanded macro in resolve!")
788 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, fn_id: NodeId) {
789 let previous_value = self.diagnostic_metadata.current_function;
791 // Bail if the function is foreign, and thus cannot validly have
792 // a body, or if there's no body for some other reason.
793 FnKind::Fn(FnCtxt::Foreign, _, sig, _, generics, _)
794 | FnKind::Fn(_, _, sig, _, generics, None) => {
795 self.visit_fn_header(&sig.header);
796 self.visit_generics(generics);
797 self.with_lifetime_rib(
798 LifetimeRibKind::AnonymousCreateParameter {
800 report_in_path: false,
803 this.resolve_fn_signature(
806 sig.decl.inputs.iter().map(|Param { ty, .. }| (None, &**ty)),
814 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
816 // Do not update `current_function` for closures: it suggests `self` parameters.
817 FnKind::Closure(..) => {}
819 debug!("(resolving function) entering function");
821 // Create a value rib for the function.
822 self.with_rib(ValueNS, ClosureOrAsyncRibKind, |this| {
823 // Create a label rib for the function.
824 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
826 FnKind::Fn(_, _, sig, _, generics, body) => {
827 this.visit_generics(generics);
829 let declaration = &sig.decl;
830 let async_node_id = sig.header.asyncness.opt_return_id();
832 this.with_lifetime_rib(
833 LifetimeRibKind::AnonymousCreateParameter {
835 report_in_path: async_node_id.is_some(),
838 this.resolve_fn_signature(
840 declaration.has_self(),
844 .map(|Param { pat, ty, .. }| (Some(&**pat), &**ty)),
850 // Construct the list of in-scope lifetime parameters for async lowering.
851 // We include all lifetime parameters, either named or "Fresh".
852 // The order of those parameters does not matter, as long as it is
854 if let Some(async_node_id) = async_node_id {
855 let mut extra_lifetime_params = this
857 .extra_lifetime_params_map
860 .unwrap_or_default();
861 for rib in this.lifetime_ribs.iter().rev() {
862 extra_lifetime_params.extend(
865 .map(|(&ident, &(node_id, res))| (ident, node_id, res)),
868 LifetimeRibKind::Item => break,
869 LifetimeRibKind::AnonymousCreateParameter {
872 if let Some(earlier_fresh) =
873 this.r.extra_lifetime_params_map.get(&binder)
875 extra_lifetime_params.extend(earlier_fresh);
882 .extra_lifetime_params_map
883 .insert(async_node_id, extra_lifetime_params);
886 if let Some(body) = body {
887 // Ignore errors in function bodies if this is rustdoc
888 // Be sure not to set this until the function signature has been resolved.
889 let previous_state = replace(&mut this.in_func_body, true);
890 // Resolve the function body, potentially inside the body of an async closure
891 this.with_lifetime_rib(
892 LifetimeRibKind::Elided(LifetimeRes::Infer),
893 |this| this.visit_block(body),
896 debug!("(resolving function) leaving function");
897 this.in_func_body = previous_state;
900 FnKind::Closure(binder, declaration, body) => {
901 this.visit_closure_binder(binder);
903 this.with_lifetime_rib(
905 // We do not have any explicit generic lifetime parameter.
906 ClosureBinder::NotPresent => {
907 LifetimeRibKind::AnonymousCreateParameter {
909 report_in_path: false,
912 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
914 // Add each argument to the rib.
915 |this| this.resolve_params(&declaration.inputs),
917 this.with_lifetime_rib(
919 ClosureBinder::NotPresent => {
920 LifetimeRibKind::Elided(LifetimeRes::Infer)
922 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
924 |this| visit::walk_fn_ret_ty(this, &declaration.output),
927 // Ignore errors in function bodies if this is rustdoc
928 // Be sure not to set this until the function signature has been resolved.
929 let previous_state = replace(&mut this.in_func_body, true);
930 // Resolve the function body, potentially inside the body of an async closure
931 this.with_lifetime_rib(
932 LifetimeRibKind::Elided(LifetimeRes::Infer),
933 |this| this.visit_expr(body),
936 debug!("(resolving function) leaving function");
937 this.in_func_body = previous_state;
942 self.diagnostic_metadata.current_function = previous_value;
944 fn visit_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
945 self.resolve_lifetime(lifetime, use_ctxt)
948 fn visit_generics(&mut self, generics: &'ast Generics) {
949 self.visit_generic_params(
951 self.diagnostic_metadata.current_self_item.is_some(),
953 for p in &generics.where_clause.predicates {
954 self.visit_where_predicate(p);
958 fn visit_closure_binder(&mut self, b: &'ast ClosureBinder) {
960 ClosureBinder::NotPresent => {}
961 ClosureBinder::For { generic_params, .. } => {
962 self.visit_generic_params(
964 self.diagnostic_metadata.current_self_item.is_some(),
970 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
971 debug!("visit_generic_arg({:?})", arg);
972 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
974 GenericArg::Type(ref ty) => {
975 // We parse const arguments as path types as we cannot distinguish them during
976 // parsing. We try to resolve that ambiguity by attempting resolution the type
977 // namespace first, and if that fails we try again in the value namespace. If
978 // resolution in the value namespace succeeds, we have an generic const argument on
980 if let TyKind::Path(ref qself, ref path) = ty.kind {
981 // We cannot disambiguate multi-segment paths right now as that requires type
983 if path.segments.len() == 1 && path.segments[0].args.is_none() {
984 let mut check_ns = |ns| {
985 self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns)
988 if !check_ns(TypeNS) && check_ns(ValueNS) {
989 // This must be equivalent to `visit_anon_const`, but we cannot call it
990 // directly due to visitor lifetimes so we have to copy-paste some code.
992 // Note that we might not be inside of an repeat expression here,
993 // but considering that `IsRepeatExpr` is only relevant for
994 // non-trivial constants this is doesn't matter.
995 self.with_constant_rib(
997 ConstantHasGenerics::Yes,
1000 this.smart_resolve_path(
1004 PathSource::Expr(None),
1007 if let Some(ref qself) = *qself {
1008 this.visit_ty(&qself.ty);
1010 this.visit_path(path, ty.id);
1014 self.diagnostic_metadata.currently_processing_generics = prev;
1022 GenericArg::Lifetime(lt) => self.visit_lifetime(lt, visit::LifetimeCtxt::GenericArg),
1023 GenericArg::Const(ct) => self.visit_anon_const(ct),
1025 self.diagnostic_metadata.currently_processing_generics = prev;
1028 fn visit_assoc_constraint(&mut self, constraint: &'ast AssocConstraint) {
1029 self.visit_ident(constraint.ident);
1030 if let Some(ref gen_args) = constraint.gen_args {
1031 // Forbid anonymous lifetimes in GAT parameters until proper semantics are decided.
1032 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1033 this.visit_generic_args(gen_args.span(), gen_args)
1036 match constraint.kind {
1037 AssocConstraintKind::Equality { ref term } => match term {
1038 Term::Ty(ty) => self.visit_ty(ty),
1039 Term::Const(c) => self.visit_anon_const(c),
1041 AssocConstraintKind::Bound { ref bounds } => {
1042 walk_list!(self, visit_param_bound, bounds, BoundKind::Bound);
1047 fn visit_path_segment(&mut self, path_span: Span, path_segment: &'ast PathSegment) {
1048 if let Some(ref args) = path_segment.args {
1050 GenericArgs::AngleBracketed(..) => visit::walk_generic_args(self, path_span, args),
1051 GenericArgs::Parenthesized(p_args) => {
1052 // Probe the lifetime ribs to know how to behave.
1053 for rib in self.lifetime_ribs.iter().rev() {
1055 // We are inside a `PolyTraitRef`. The lifetimes are
1056 // to be intoduced in that (maybe implicit) `for<>` binder.
1057 LifetimeRibKind::Generics {
1059 kind: LifetimeBinderKind::PolyTrait,
1062 self.with_lifetime_rib(
1063 LifetimeRibKind::AnonymousCreateParameter {
1065 report_in_path: false,
1068 this.resolve_fn_signature(
1071 p_args.inputs.iter().map(|ty| (None, &**ty)),
1078 // We have nowhere to introduce generics. Code is malformed,
1079 // so use regular lifetime resolution to avoid spurious errors.
1080 LifetimeRibKind::Item | LifetimeRibKind::Generics { .. } => {
1081 visit::walk_generic_args(self, path_span, args);
1084 LifetimeRibKind::AnonymousCreateParameter { .. }
1085 | LifetimeRibKind::AnonymousReportError
1086 | LifetimeRibKind::Elided(_)
1087 | LifetimeRibKind::ElisionFailure
1088 | LifetimeRibKind::AnonConst
1089 | LifetimeRibKind::ConstGeneric => {}
1097 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
1098 debug!("visit_where_predicate {:?}", p);
1099 let previous_value =
1100 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
1101 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1102 if let WherePredicate::BoundPredicate(WhereBoundPredicate {
1105 ref bound_generic_params,
1106 span: predicate_span,
1110 let span = predicate_span.shrink_to_lo().to(bounded_ty.span.shrink_to_lo());
1111 this.with_generic_param_rib(
1112 &bound_generic_params,
1114 LifetimeRibKind::Generics {
1115 binder: bounded_ty.id,
1116 kind: LifetimeBinderKind::WhereBound,
1120 this.visit_generic_params(&bound_generic_params, false);
1121 this.visit_ty(bounded_ty);
1122 for bound in bounds {
1123 this.visit_param_bound(bound, BoundKind::Bound)
1128 visit::walk_where_predicate(this, p);
1131 self.diagnostic_metadata.current_where_predicate = previous_value;
1134 fn visit_inline_asm(&mut self, asm: &'ast InlineAsm) {
1135 for (op, _) in &asm.operands {
1137 InlineAsmOperand::In { expr, .. }
1138 | InlineAsmOperand::Out { expr: Some(expr), .. }
1139 | InlineAsmOperand::InOut { expr, .. } => self.visit_expr(expr),
1140 InlineAsmOperand::Out { expr: None, .. } => {}
1141 InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
1142 self.visit_expr(in_expr);
1143 if let Some(out_expr) = out_expr {
1144 self.visit_expr(out_expr);
1147 InlineAsmOperand::Const { anon_const, .. } => {
1148 // Although this is `DefKind::AnonConst`, it is allowed to reference outer
1149 // generic parameters like an inline const.
1150 self.resolve_inline_const(anon_const);
1152 InlineAsmOperand::Sym { sym } => self.visit_inline_asm_sym(sym),
1157 fn visit_inline_asm_sym(&mut self, sym: &'ast InlineAsmSym) {
1158 // This is similar to the code for AnonConst.
1159 self.with_rib(ValueNS, InlineAsmSymRibKind, |this| {
1160 this.with_rib(TypeNS, InlineAsmSymRibKind, |this| {
1161 this.with_label_rib(InlineAsmSymRibKind, |this| {
1162 this.smart_resolve_path(
1166 PathSource::Expr(None),
1168 visit::walk_inline_asm_sym(this, sym);
1175 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
1176 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
1177 // During late resolution we only track the module component of the parent scope,
1178 // although it may be useful to track other components as well for diagnostics.
1179 let graph_root = resolver.graph_root;
1180 let parent_scope = ParentScope::module(graph_root, resolver);
1181 let start_rib_kind = ModuleRibKind(graph_root);
1182 LateResolutionVisitor {
1186 value_ns: vec![Rib::new(start_rib_kind)],
1187 type_ns: vec![Rib::new(start_rib_kind)],
1188 macro_ns: vec![Rib::new(start_rib_kind)],
1190 label_ribs: Vec::new(),
1191 lifetime_ribs: Vec::new(),
1192 lifetime_elision_candidates: None,
1193 current_trait_ref: None,
1194 diagnostic_metadata: Box::new(DiagnosticMetadata::default()),
1195 // errors at module scope should always be reported
1196 in_func_body: false,
1197 lifetime_uses: Default::default(),
1201 fn maybe_resolve_ident_in_lexical_scope(
1205 ) -> Option<LexicalScopeBinding<'a>> {
1206 self.r.resolve_ident_in_lexical_scope(
1216 fn resolve_ident_in_lexical_scope(
1220 finalize: Option<Finalize>,
1221 ignore_binding: Option<&'a NameBinding<'a>>,
1222 ) -> Option<LexicalScopeBinding<'a>> {
1223 self.r.resolve_ident_in_lexical_scope(
1236 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1237 finalize: Option<Finalize>,
1238 ) -> PathResult<'a> {
1239 self.r.resolve_path_with_ribs(
1251 // We maintain a list of value ribs and type ribs.
1253 // Simultaneously, we keep track of the current position in the module
1254 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
1255 // the value or type namespaces, we first look through all the ribs and
1256 // then query the module graph. When we resolve a name in the module
1257 // namespace, we can skip all the ribs (since nested modules are not
1258 // allowed within blocks in Rust) and jump straight to the current module
1261 // Named implementations are handled separately. When we find a method
1262 // call, we consult the module node to find all of the implementations in
1263 // scope. This information is lazily cached in the module node. We then
1264 // generate a fake "implementation scope" containing all the
1265 // implementations thus found, for compatibility with old resolve pass.
1267 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
1272 work: impl FnOnce(&mut Self) -> T,
1274 self.ribs[ns].push(Rib::new(kind));
1275 let ret = work(self);
1276 self.ribs[ns].pop();
1280 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
1281 if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
1282 // Move down in the graph.
1283 let orig_module = replace(&mut self.parent_scope.module, module);
1284 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
1285 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
1287 this.parent_scope.module = orig_module;
1296 fn visit_generic_params(&mut self, params: &'ast [GenericParam], add_self_upper: bool) {
1297 // For type parameter defaults, we have to ban access
1298 // to following type parameters, as the InternalSubsts can only
1299 // provide previous type parameters as they're built. We
1300 // put all the parameters on the ban list and then remove
1301 // them one by one as they are processed and become available.
1302 let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1303 let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1304 for param in params.iter() {
1306 GenericParamKind::Type { .. } => {
1309 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1311 GenericParamKind::Const { .. } => {
1312 forward_const_ban_rib
1314 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1316 GenericParamKind::Lifetime => {}
1320 // rust-lang/rust#61631: The type `Self` is essentially
1321 // another type parameter. For ADTs, we consider it
1322 // well-defined only after all of the ADT type parameters have
1323 // been provided. Therefore, we do not allow use of `Self`
1324 // anywhere in ADT type parameter defaults.
1326 // (We however cannot ban `Self` for defaults on *all* generic
1327 // lists; e.g. trait generics can usefully refer to `Self`,
1328 // such as in the case of `trait Add<Rhs = Self>`.)
1330 // (`Some` if + only if we are in ADT's generics.)
1331 forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
1334 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1335 for param in params {
1337 GenericParamKind::Lifetime => {
1338 for bound in ¶m.bounds {
1339 this.visit_param_bound(bound, BoundKind::Bound);
1342 GenericParamKind::Type { ref default } => {
1343 for bound in ¶m.bounds {
1344 this.visit_param_bound(bound, BoundKind::Bound);
1347 if let Some(ref ty) = default {
1348 this.ribs[TypeNS].push(forward_ty_ban_rib);
1349 this.ribs[ValueNS].push(forward_const_ban_rib);
1351 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1352 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1355 // Allow all following defaults to refer to this type parameter.
1358 .remove(&Ident::with_dummy_span(param.ident.name));
1360 GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
1361 // Const parameters can't have param bounds.
1362 assert!(param.bounds.is_empty());
1364 this.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
1365 this.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
1366 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1369 this.ribs[TypeNS].pop().unwrap();
1370 this.ribs[ValueNS].pop().unwrap();
1372 if let Some(ref expr) = default {
1373 this.ribs[TypeNS].push(forward_ty_ban_rib);
1374 this.ribs[ValueNS].push(forward_const_ban_rib);
1375 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1376 this.resolve_anon_const(expr, IsRepeatExpr::No)
1378 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1379 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1382 // Allow all following defaults to refer to this const parameter.
1383 forward_const_ban_rib
1385 .remove(&Ident::with_dummy_span(param.ident.name));
1392 #[instrument(level = "debug", skip(self, work))]
1393 fn with_lifetime_rib<T>(
1395 kind: LifetimeRibKind,
1396 work: impl FnOnce(&mut Self) -> T,
1398 self.lifetime_ribs.push(LifetimeRib::new(kind));
1399 let outer_elision_candidates = self.lifetime_elision_candidates.take();
1400 let ret = work(self);
1401 self.lifetime_elision_candidates = outer_elision_candidates;
1402 self.lifetime_ribs.pop();
1406 #[instrument(level = "debug", skip(self))]
1407 fn resolve_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
1408 let ident = lifetime.ident;
1410 if ident.name == kw::StaticLifetime {
1411 self.record_lifetime_res(
1413 LifetimeRes::Static,
1414 LifetimeElisionCandidate::Named,
1419 if ident.name == kw::UnderscoreLifetime {
1420 return self.resolve_anonymous_lifetime(lifetime, false);
1423 let mut indices = (0..self.lifetime_ribs.len()).rev();
1424 for i in &mut indices {
1425 let rib = &self.lifetime_ribs[i];
1426 let normalized_ident = ident.normalize_to_macros_2_0();
1427 if let Some(&(_, res)) = rib.bindings.get(&normalized_ident) {
1428 self.record_lifetime_res(lifetime.id, res, LifetimeElisionCandidate::Named);
1430 if let LifetimeRes::Param { param, .. } = res {
1431 match self.lifetime_uses.entry(param) {
1432 Entry::Vacant(v) => {
1433 debug!("First use of {:?} at {:?}", res, ident.span);
1438 .find_map(|rib| match rib.kind {
1439 // Do not suggest eliding a lifetime where an anonymous
1440 // lifetime would be illegal.
1441 LifetimeRibKind::Item
1442 | LifetimeRibKind::AnonymousReportError
1443 | LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many),
1444 // An anonymous lifetime is legal here, go ahead.
1445 LifetimeRibKind::AnonymousCreateParameter { .. } => {
1446 Some(LifetimeUseSet::One { use_span: ident.span, use_ctxt })
1448 // Only report if eliding the lifetime would have the same
1450 LifetimeRibKind::Elided(r) => Some(if res == r {
1451 LifetimeUseSet::One { use_span: ident.span, use_ctxt }
1453 LifetimeUseSet::Many
1455 LifetimeRibKind::Generics { .. }
1456 | LifetimeRibKind::ConstGeneric
1457 | LifetimeRibKind::AnonConst => None,
1459 .unwrap_or(LifetimeUseSet::Many);
1460 debug!(?use_ctxt, ?use_set);
1463 Entry::Occupied(mut o) => {
1464 debug!("Many uses of {:?} at {:?}", res, ident.span);
1465 *o.get_mut() = LifetimeUseSet::Many;
1473 LifetimeRibKind::Item => break,
1474 LifetimeRibKind::ConstGeneric => {
1475 self.emit_non_static_lt_in_const_generic_error(lifetime);
1476 self.record_lifetime_res(
1479 LifetimeElisionCandidate::Ignore,
1483 LifetimeRibKind::AnonConst => {
1484 self.maybe_emit_forbidden_non_static_lifetime_error(lifetime);
1485 self.record_lifetime_res(
1488 LifetimeElisionCandidate::Ignore,
1496 let mut outer_res = None;
1498 let rib = &self.lifetime_ribs[i];
1499 let normalized_ident = ident.normalize_to_macros_2_0();
1500 if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) {
1501 outer_res = Some(outer);
1506 self.emit_undeclared_lifetime_error(lifetime, outer_res);
1507 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, LifetimeElisionCandidate::Named);
1510 #[instrument(level = "debug", skip(self))]
1511 fn resolve_anonymous_lifetime(&mut self, lifetime: &Lifetime, elided: bool) {
1512 debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
1514 let missing_lifetime = MissingLifetime {
1516 span: lifetime.ident.span,
1518 MissingLifetimeKind::Ampersand
1520 MissingLifetimeKind::Underscore
1524 let elision_candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1525 for i in (0..self.lifetime_ribs.len()).rev() {
1526 let rib = &mut self.lifetime_ribs[i];
1529 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1530 let res = self.create_fresh_lifetime(lifetime.id, lifetime.ident, binder);
1531 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1534 LifetimeRibKind::AnonymousReportError => {
1535 let (msg, note) = if elided {
1537 "`&` without an explicit lifetime name cannot be used here",
1538 "explicit lifetime name needed here",
1541 ("`'_` cannot be used here", "`'_` is a reserved lifetime name")
1543 rustc_errors::struct_span_err!(
1545 lifetime.ident.span,
1550 .span_label(lifetime.ident.span, note)
1553 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1556 LifetimeRibKind::Elided(res) => {
1557 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1560 LifetimeRibKind::ElisionFailure => {
1561 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1562 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1565 LifetimeRibKind::Item => break,
1566 LifetimeRibKind::Generics { .. }
1567 | LifetimeRibKind::ConstGeneric
1568 | LifetimeRibKind::AnonConst => {}
1571 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1572 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1575 #[instrument(level = "debug", skip(self))]
1576 fn resolve_elided_lifetime(&mut self, anchor_id: NodeId, span: Span) {
1577 let id = self.r.next_node_id();
1578 let lt = Lifetime { id, ident: Ident::new(kw::UnderscoreLifetime, span) };
1580 self.record_lifetime_res(
1582 LifetimeRes::ElidedAnchor { start: id, end: NodeId::from_u32(id.as_u32() + 1) },
1583 LifetimeElisionCandidate::Ignore,
1585 self.resolve_anonymous_lifetime(<, true);
1588 #[instrument(level = "debug", skip(self))]
1589 fn create_fresh_lifetime(&mut self, id: NodeId, ident: Ident, binder: NodeId) -> LifetimeRes {
1590 debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
1591 debug!(?ident.span);
1593 // Leave the responsibility to create the `LocalDefId` to lowering.
1594 let param = self.r.next_node_id();
1595 let res = LifetimeRes::Fresh { param, binder };
1597 // Record the created lifetime parameter so lowering can pick it up and add it to HIR.
1599 .extra_lifetime_params_map
1601 .or_insert_with(Vec::new)
1602 .push((ident, param, res));
1606 #[instrument(level = "debug", skip(self))]
1607 fn resolve_elided_lifetimes_in_path(
1610 partial_res: PartialRes,
1612 source: PathSource<'_>,
1615 let proj_start = path.len() - partial_res.unresolved_segments();
1616 for (i, segment) in path.iter().enumerate() {
1617 if segment.has_lifetime_args {
1620 let Some(segment_id) = segment.id else {
1624 // Figure out if this is a type/trait segment,
1625 // which may need lifetime elision performed.
1626 let type_def_id = match partial_res.base_res() {
1627 Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => self.r.parent(def_id),
1628 Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => self.r.parent(def_id),
1629 Res::Def(DefKind::Struct, def_id)
1630 | Res::Def(DefKind::Union, def_id)
1631 | Res::Def(DefKind::Enum, def_id)
1632 | Res::Def(DefKind::TyAlias, def_id)
1633 | Res::Def(DefKind::Trait, def_id)
1634 if i + 1 == proj_start =>
1641 let expected_lifetimes = self.r.item_generics_num_lifetimes(type_def_id);
1642 if expected_lifetimes == 0 {
1646 let node_ids = self.r.next_node_ids(expected_lifetimes);
1647 self.record_lifetime_res(
1649 LifetimeRes::ElidedAnchor { start: node_ids.start, end: node_ids.end },
1650 LifetimeElisionCandidate::Ignore,
1653 let inferred = match source {
1654 PathSource::Trait(..) | PathSource::TraitItem(..) | PathSource::Type => false,
1655 PathSource::Expr(..)
1657 | PathSource::Struct
1658 | PathSource::TupleStruct(..) => true,
1661 // Do not create a parameter for patterns and expressions: type checking can infer
1662 // the appropriate lifetime for us.
1663 for id in node_ids {
1664 self.record_lifetime_res(
1667 LifetimeElisionCandidate::Named,
1673 let elided_lifetime_span = if segment.has_generic_args {
1674 // If there are brackets, but not generic arguments, then use the opening bracket
1675 segment.args_span.with_hi(segment.args_span.lo() + BytePos(1))
1677 // If there are no brackets, use the identifier span.
1678 // HACK: we use find_ancestor_inside to properly suggest elided spans in paths
1679 // originating from macros, since the segment's span might be from a macro arg.
1680 segment.ident.span.find_ancestor_inside(path_span).unwrap_or(path_span)
1682 let ident = Ident::new(kw::UnderscoreLifetime, elided_lifetime_span);
1684 let missing_lifetime = MissingLifetime {
1686 span: elided_lifetime_span,
1687 kind: if segment.has_generic_args {
1688 MissingLifetimeKind::Comma
1690 MissingLifetimeKind::Brackets
1692 count: expected_lifetimes,
1694 let mut should_lint = true;
1695 for rib in self.lifetime_ribs.iter().rev() {
1697 // In create-parameter mode we error here because we don't want to support
1698 // deprecated impl elision in new features like impl elision and `async fn`,
1699 // both of which work using the `CreateParameter` mode:
1701 // impl Foo for std::cell::Ref<u32> // note lack of '_
1702 // async fn foo(_: std::cell::Ref<u32>) { ... }
1703 LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. } => {
1704 let sess = self.r.session;
1705 let mut err = rustc_errors::struct_span_err!(
1709 "implicit elided lifetime not allowed here"
1711 rustc_errors::add_elided_lifetime_in_path_suggestion(
1716 !segment.has_generic_args,
1717 elided_lifetime_span,
1719 err.note("assuming a `'static` lifetime...");
1721 should_lint = false;
1723 for id in node_ids {
1724 self.record_lifetime_res(
1727 LifetimeElisionCandidate::Named,
1732 // Do not create a parameter for patterns and expressions.
1733 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1734 // Group all suggestions into the first record.
1735 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1736 for id in node_ids {
1737 let res = self.create_fresh_lifetime(id, ident, binder);
1738 self.record_lifetime_res(
1741 replace(&mut candidate, LifetimeElisionCandidate::Named),
1746 LifetimeRibKind::Elided(res) => {
1747 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1748 for id in node_ids {
1749 self.record_lifetime_res(
1752 replace(&mut candidate, LifetimeElisionCandidate::Ignore),
1757 LifetimeRibKind::ElisionFailure => {
1758 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1759 for id in node_ids {
1760 self.record_lifetime_res(
1763 LifetimeElisionCandidate::Ignore,
1768 // `LifetimeRes::Error`, which would usually be used in the case of
1769 // `ReportError`, is unsuitable here, as we don't emit an error yet. Instead,
1770 // we simply resolve to an implicit lifetime, which will be checked later, at
1771 // which point a suitable error will be emitted.
1772 LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
1773 for id in node_ids {
1774 self.record_lifetime_res(
1777 LifetimeElisionCandidate::Ignore,
1780 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1783 LifetimeRibKind::Generics { .. }
1784 | LifetimeRibKind::ConstGeneric
1785 | LifetimeRibKind::AnonConst => {}
1790 self.r.lint_buffer.buffer_lint_with_diagnostic(
1791 lint::builtin::ELIDED_LIFETIMES_IN_PATHS,
1793 elided_lifetime_span,
1794 "hidden lifetime parameters in types are deprecated",
1795 lint::BuiltinLintDiagnostics::ElidedLifetimesInPaths(
1798 !segment.has_generic_args,
1799 elided_lifetime_span,
1806 #[instrument(level = "debug", skip(self))]
1807 fn record_lifetime_res(
1811 candidate: LifetimeElisionCandidate,
1813 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1815 "lifetime {:?} resolved multiple times ({:?} before, {:?} now)",
1820 LifetimeRes::Param { .. } | LifetimeRes::Fresh { .. } | LifetimeRes::Static => {
1821 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
1822 candidates.insert(res, candidate);
1825 LifetimeRes::Infer | LifetimeRes::Error | LifetimeRes::ElidedAnchor { .. } => {}
1829 #[instrument(level = "debug", skip(self))]
1830 fn record_lifetime_param(&mut self, id: NodeId, res: LifetimeRes) {
1831 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1833 "lifetime parameter {:?} resolved multiple times ({:?} before, {:?} now)",
1839 /// Perform resolution of a function signature, accounting for lifetime elision.
1840 #[instrument(level = "debug", skip(self, inputs))]
1841 fn resolve_fn_signature(
1845 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)> + Clone,
1846 output_ty: &'ast FnRetTy,
1848 // Add each argument to the rib.
1849 let elision_lifetime = self.resolve_fn_params(has_self, inputs);
1850 debug!(?elision_lifetime);
1852 let outer_failures = take(&mut self.diagnostic_metadata.current_elision_failures);
1853 let output_rib = if let Ok(res) = elision_lifetime.as_ref() {
1854 LifetimeRibKind::Elided(*res)
1856 LifetimeRibKind::ElisionFailure
1858 self.with_lifetime_rib(output_rib, |this| visit::walk_fn_ret_ty(this, &output_ty));
1859 let elision_failures =
1860 replace(&mut self.diagnostic_metadata.current_elision_failures, outer_failures);
1861 if !elision_failures.is_empty() {
1862 let Err(failure_info) = elision_lifetime else { bug!() };
1863 self.report_missing_lifetime_specifiers(elision_failures, Some(failure_info));
1867 /// Resolve inside function parameters and parameter types.
1868 /// Returns the lifetime for elision in fn return type,
1869 /// or diagnostic information in case of elision failure.
1870 fn resolve_fn_params(
1873 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)>,
1874 ) -> Result<LifetimeRes, (Vec<MissingLifetime>, Vec<ElisionFnParameter>)> {
1875 let outer_candidates =
1876 replace(&mut self.lifetime_elision_candidates, Some(Default::default()));
1878 let mut elision_lifetime = None;
1879 let mut lifetime_count = 0;
1880 let mut parameter_info = Vec::new();
1882 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1883 for (index, (pat, ty)) in inputs.enumerate() {
1885 if let Some(pat) = pat {
1886 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1890 if let Some(ref candidates) = self.lifetime_elision_candidates {
1891 let new_count = candidates.len();
1892 let local_count = new_count - lifetime_count;
1893 if local_count != 0 {
1894 parameter_info.push(ElisionFnParameter {
1896 ident: if let Some(pat) = pat && let PatKind::Ident(_, ident, _) = pat.kind {
1901 lifetime_count: local_count,
1905 lifetime_count = new_count;
1908 // Handle `self` specially.
1909 if index == 0 && has_self {
1910 let self_lifetime = self.find_lifetime_for_self(ty);
1911 if let Set1::One(lifetime) = self_lifetime {
1912 elision_lifetime = Some(lifetime);
1913 self.lifetime_elision_candidates = None;
1915 self.lifetime_elision_candidates = Some(Default::default());
1919 debug!("(resolving function / closure) recorded parameter");
1922 let all_candidates = replace(&mut self.lifetime_elision_candidates, outer_candidates);
1923 debug!(?all_candidates);
1925 if let Some(res) = elision_lifetime {
1929 // We do not have a `self` candidate, look at the full list.
1930 let all_candidates = all_candidates.unwrap();
1931 if all_candidates.len() == 1 {
1932 Ok(*all_candidates.first().unwrap().0)
1934 let all_candidates = all_candidates
1936 .filter_map(|(_, candidate)| match candidate {
1937 LifetimeElisionCandidate::Ignore | LifetimeElisionCandidate::Named => None,
1938 LifetimeElisionCandidate::Missing(missing) => Some(missing),
1941 Err((all_candidates, parameter_info))
1945 /// List all the lifetimes that appear in the provided type.
1946 fn find_lifetime_for_self(&self, ty: &'ast Ty) -> Set1<LifetimeRes> {
1947 struct SelfVisitor<'r, 'a> {
1948 r: &'r Resolver<'a>,
1949 impl_self: Option<Res>,
1950 lifetime: Set1<LifetimeRes>,
1953 impl SelfVisitor<'_, '_> {
1954 // Look for `self: &'a Self` - also desugared from `&'a self`,
1955 // and if that matches, use it for elision and return early.
1956 fn is_self_ty(&self, ty: &Ty) -> bool {
1958 TyKind::ImplicitSelf => true,
1959 TyKind::Path(None, _) => {
1960 let path_res = self.r.partial_res_map[&ty.id].base_res();
1961 if let Res::SelfTy { .. } = path_res {
1964 Some(path_res) == self.impl_self
1971 impl<'a> Visitor<'a> for SelfVisitor<'_, '_> {
1972 fn visit_ty(&mut self, ty: &'a Ty) {
1973 trace!("SelfVisitor considering ty={:?}", ty);
1974 if let TyKind::Rptr(lt, ref mt) = ty.kind && self.is_self_ty(&mt.ty) {
1975 let lt_id = if let Some(lt) = lt {
1978 let res = self.r.lifetimes_res_map[&ty.id];
1979 let LifetimeRes::ElidedAnchor { start, .. } = res else { bug!() };
1982 let lt_res = self.r.lifetimes_res_map[<_id];
1983 trace!("SelfVisitor inserting res={:?}", lt_res);
1984 self.lifetime.insert(lt_res);
1986 visit::walk_ty(self, ty)
1990 let impl_self = self
1991 .diagnostic_metadata
1995 if let TyKind::Path(None, _) = ty.kind {
1996 self.r.partial_res_map.get(&ty.id)
2001 .map(|res| res.base_res())
2003 // Permit the types that unambiguously always
2004 // result in the same type constructor being used
2005 // (it can't differ between `Self` and `self`).
2008 Res::Def(DefKind::Struct | DefKind::Union | DefKind::Enum, _,) | Res::PrimTy(_)
2011 let mut visitor = SelfVisitor { r: self.r, impl_self, lifetime: Set1::Empty };
2012 visitor.visit_ty(ty);
2013 trace!("SelfVisitor found={:?}", visitor.lifetime);
2017 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
2018 /// label and reports an error if the label is not found or is unreachable.
2019 fn resolve_label(&mut self, mut label: Ident) -> Result<(NodeId, Span), ResolutionError<'a>> {
2020 let mut suggestion = None;
2022 for i in (0..self.label_ribs.len()).rev() {
2023 let rib = &self.label_ribs[i];
2025 if let MacroDefinition(def) = rib.kind {
2026 // If an invocation of this macro created `ident`, give up on `ident`
2027 // and switch to `ident`'s source from the macro definition.
2028 if def == self.r.macro_def(label.span.ctxt()) {
2029 label.span.remove_mark();
2033 let ident = label.normalize_to_macro_rules();
2034 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
2035 let definition_span = ident.span;
2036 return if self.is_label_valid_from_rib(i) {
2037 Ok((*id, definition_span))
2039 Err(ResolutionError::UnreachableLabel {
2047 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
2048 // the first such label that is encountered.
2049 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
2052 Err(ResolutionError::UndeclaredLabel { name: label.name, suggestion })
2055 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
2056 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
2057 let ribs = &self.label_ribs[rib_index + 1..];
2060 if rib.kind.is_label_barrier() {
2068 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
2069 debug!("resolve_adt");
2070 self.with_current_self_item(item, |this| {
2071 this.with_generic_param_rib(
2073 ItemRibKind(HasGenericParams::Yes(generics.span)),
2074 LifetimeRibKind::Generics {
2076 kind: LifetimeBinderKind::Item,
2077 span: generics.span,
2080 let item_def_id = this.r.local_def_id(item.id).to_def_id();
2082 Res::SelfTy { trait_: None, alias_to: Some((item_def_id, false)) },
2084 visit::walk_item(this, item);
2092 fn future_proof_import(&mut self, use_tree: &UseTree) {
2093 let segments = &use_tree.prefix.segments;
2094 if !segments.is_empty() {
2095 let ident = segments[0].ident;
2096 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
2100 let nss = match use_tree.kind {
2101 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
2104 let report_error = |this: &Self, ns| {
2105 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
2106 if this.should_report_errs() {
2109 .span_err(ident.span, &format!("imports cannot refer to {}", what));
2114 match self.maybe_resolve_ident_in_lexical_scope(ident, ns) {
2115 Some(LexicalScopeBinding::Res(..)) => {
2116 report_error(self, ns);
2118 Some(LexicalScopeBinding::Item(binding)) => {
2119 if let Some(LexicalScopeBinding::Res(..)) =
2120 self.resolve_ident_in_lexical_scope(ident, ns, None, Some(binding))
2122 report_error(self, ns);
2128 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
2129 for (use_tree, _) in use_trees {
2130 self.future_proof_import(use_tree);
2135 fn resolve_item(&mut self, item: &'ast Item) {
2136 let name = item.ident.name;
2137 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
2140 ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
2141 self.with_generic_param_rib(
2143 ItemRibKind(HasGenericParams::Yes(generics.span)),
2144 LifetimeRibKind::Generics {
2146 kind: LifetimeBinderKind::Item,
2147 span: generics.span,
2149 |this| visit::walk_item(this, item),
2153 ItemKind::Fn(box Fn { ref generics, .. }) => {
2154 self.with_generic_param_rib(
2156 ItemRibKind(HasGenericParams::Yes(generics.span)),
2157 LifetimeRibKind::Generics {
2159 kind: LifetimeBinderKind::Function,
2160 span: generics.span,
2162 |this| visit::walk_item(this, item),
2166 ItemKind::Enum(_, ref generics)
2167 | ItemKind::Struct(_, ref generics)
2168 | ItemKind::Union(_, ref generics) => {
2169 self.resolve_adt(item, generics);
2172 ItemKind::Impl(box Impl {
2176 items: ref impl_items,
2179 self.diagnostic_metadata.current_impl_items = Some(impl_items);
2180 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
2181 self.diagnostic_metadata.current_impl_items = None;
2184 ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
2185 // Create a new rib for the trait-wide type parameters.
2186 self.with_generic_param_rib(
2188 ItemRibKind(HasGenericParams::Yes(generics.span)),
2189 LifetimeRibKind::Generics {
2191 kind: LifetimeBinderKind::Item,
2192 span: generics.span,
2195 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2197 Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
2199 this.visit_generics(generics);
2200 walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);
2201 this.resolve_trait_items(items);
2208 ItemKind::TraitAlias(ref generics, ref bounds) => {
2209 // Create a new rib for the trait-wide type parameters.
2210 self.with_generic_param_rib(
2212 ItemRibKind(HasGenericParams::Yes(generics.span)),
2213 LifetimeRibKind::Generics {
2215 kind: LifetimeBinderKind::Item,
2216 span: generics.span,
2219 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2221 Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
2223 this.visit_generics(generics);
2224 walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
2231 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
2232 self.with_scope(item.id, |this| {
2233 visit::walk_item(this, item);
2237 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
2238 self.with_item_rib(|this| {
2239 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
2242 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2243 if let Some(expr) = expr {
2244 let constant_item_kind = match item.kind {
2245 ItemKind::Const(..) => ConstantItemKind::Const,
2246 ItemKind::Static(..) => ConstantItemKind::Static,
2247 _ => unreachable!(),
2249 // We already forbid generic params because of the above item rib,
2250 // so it doesn't matter whether this is a trivial constant.
2251 this.with_constant_rib(
2253 ConstantHasGenerics::Yes,
2254 Some((item.ident, constant_item_kind)),
2255 |this| this.visit_expr(expr),
2262 ItemKind::Use(ref use_tree) => {
2263 self.future_proof_import(use_tree);
2266 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => {
2267 // do nothing, these are just around to be encoded
2270 ItemKind::GlobalAsm(_) => {
2271 visit::walk_item(self, item);
2274 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
2278 fn with_generic_param_rib<'c, F>(
2280 params: &'c [GenericParam],
2282 lifetime_kind: LifetimeRibKind,
2285 F: FnOnce(&mut Self),
2287 debug!("with_generic_param_rib");
2288 let LifetimeRibKind::Generics { binder, span: generics_span, kind: generics_kind, .. }
2289 = lifetime_kind else { panic!() };
2291 let mut function_type_rib = Rib::new(kind);
2292 let mut function_value_rib = Rib::new(kind);
2293 let mut function_lifetime_rib = LifetimeRib::new(lifetime_kind);
2294 let mut seen_bindings = FxHashMap::default();
2295 // Store all seen lifetimes names from outer scopes.
2296 let mut seen_lifetimes = FxHashSet::default();
2298 // We also can't shadow bindings from the parent item
2299 if let AssocItemRibKind = kind {
2300 let mut add_bindings_for_ns = |ns| {
2301 let parent_rib = self.ribs[ns]
2303 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
2304 .expect("associated item outside of an item");
2306 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
2308 add_bindings_for_ns(ValueNS);
2309 add_bindings_for_ns(TypeNS);
2312 // Forbid shadowing lifetime bindings
2313 for rib in self.lifetime_ribs.iter().rev() {
2314 seen_lifetimes.extend(rib.bindings.iter().map(|(ident, _)| *ident));
2315 if let LifetimeRibKind::Item = rib.kind {
2320 for param in params {
2321 let ident = param.ident.normalize_to_macros_2_0();
2322 debug!("with_generic_param_rib: {}", param.id);
2324 if let GenericParamKind::Lifetime = param.kind
2325 && let Some(&original) = seen_lifetimes.get(&ident)
2327 diagnostics::signal_lifetime_shadowing(self.r.session, original, param.ident);
2328 // Record lifetime res, so lowering knows there is something fishy.
2329 self.record_lifetime_param(param.id, LifetimeRes::Error);
2333 match seen_bindings.entry(ident) {
2334 Entry::Occupied(entry) => {
2335 let span = *entry.get();
2336 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
2337 self.report_error(param.ident.span, err);
2338 if let GenericParamKind::Lifetime = param.kind {
2339 // Record lifetime res, so lowering knows there is something fishy.
2340 self.record_lifetime_param(param.id, LifetimeRes::Error);
2344 Entry::Vacant(entry) => {
2345 entry.insert(param.ident.span);
2349 if param.ident.name == kw::UnderscoreLifetime {
2350 rustc_errors::struct_span_err!(
2354 "`'_` cannot be used here"
2356 .span_label(param.ident.span, "`'_` is a reserved lifetime name")
2358 // Record lifetime res, so lowering knows there is something fishy.
2359 self.record_lifetime_param(param.id, LifetimeRes::Error);
2363 if param.ident.name == kw::StaticLifetime {
2364 rustc_errors::struct_span_err!(
2368 "invalid lifetime parameter name: `{}`",
2371 .span_label(param.ident.span, "'static is a reserved lifetime name")
2373 // Record lifetime res, so lowering knows there is something fishy.
2374 self.record_lifetime_param(param.id, LifetimeRes::Error);
2378 let def_id = self.r.local_def_id(param.id);
2380 // Plain insert (no renaming).
2381 let (rib, def_kind) = match param.kind {
2382 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
2383 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
2384 GenericParamKind::Lifetime => {
2385 let res = LifetimeRes::Param { param: def_id, binder };
2386 self.record_lifetime_param(param.id, res);
2387 function_lifetime_rib.bindings.insert(ident, (param.id, res));
2392 let res = match kind {
2393 ItemRibKind(..) | AssocItemRibKind => Res::Def(def_kind, def_id.to_def_id()),
2394 NormalRibKind => Res::Err,
2395 _ => span_bug!(param.ident.span, "Unexpected rib kind {:?}", kind),
2397 self.r.record_partial_res(param.id, PartialRes::new(res));
2398 rib.bindings.insert(ident, res);
2401 self.lifetime_ribs.push(function_lifetime_rib);
2402 self.ribs[ValueNS].push(function_value_rib);
2403 self.ribs[TypeNS].push(function_type_rib);
2407 self.ribs[TypeNS].pop();
2408 self.ribs[ValueNS].pop();
2409 let function_lifetime_rib = self.lifetime_ribs.pop().unwrap();
2411 // Do not account for the parameters we just bound for function lifetime elision.
2412 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
2413 for (_, res) in function_lifetime_rib.bindings.values() {
2414 candidates.remove(res);
2418 if let LifetimeBinderKind::BareFnType
2419 | LifetimeBinderKind::WhereBound
2420 | LifetimeBinderKind::Function
2421 | LifetimeBinderKind::ImplBlock = generics_kind
2423 self.maybe_report_lifetime_uses(generics_span, params)
2427 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
2428 self.label_ribs.push(Rib::new(kind));
2430 self.label_ribs.pop();
2433 fn with_item_rib(&mut self, f: impl FnOnce(&mut Self)) {
2434 let kind = ItemRibKind(HasGenericParams::No);
2435 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
2436 this.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
2440 // HACK(min_const_generics,const_evaluatable_unchecked): We
2441 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
2442 // with a future compat lint for now. We do this by adding an
2443 // additional special case for repeat expressions.
2445 // Note that we intentionally still forbid `[0; N + 1]` during
2446 // name resolution so that we don't extend the future
2447 // compat lint to new cases.
2448 #[instrument(level = "debug", skip(self, f))]
2449 fn with_constant_rib(
2451 is_repeat: IsRepeatExpr,
2452 may_use_generics: ConstantHasGenerics,
2453 item: Option<(Ident, ConstantItemKind)>,
2454 f: impl FnOnce(&mut Self),
2456 self.with_rib(ValueNS, ConstantItemRibKind(may_use_generics, item), |this| {
2459 ConstantItemRibKind(
2460 may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes),
2464 this.with_label_rib(ConstantItemRibKind(may_use_generics, item), f);
2470 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
2471 // Handle nested impls (inside fn bodies)
2472 let previous_value =
2473 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
2474 let result = f(self);
2475 self.diagnostic_metadata.current_self_type = previous_value;
2479 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
2480 let previous_value =
2481 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
2482 let result = f(self);
2483 self.diagnostic_metadata.current_self_item = previous_value;
2487 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
2488 fn resolve_trait_items(&mut self, trait_items: &'ast [P<AssocItem>]) {
2489 let trait_assoc_items =
2490 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
2492 let walk_assoc_item =
2493 |this: &mut Self, generics: &Generics, kind, item: &'ast AssocItem| {
2494 this.with_generic_param_rib(
2497 LifetimeRibKind::Generics { binder: item.id, span: generics.span, kind },
2498 |this| visit::walk_assoc_item(this, item, AssocCtxt::Trait),
2502 for item in trait_items {
2504 AssocItemKind::Const(_, ty, default) => {
2506 // Only impose the restrictions of `ConstRibKind` for an
2507 // actual constant expression in a provided default.
2508 if let Some(expr) = default {
2509 // We allow arbitrary const expressions inside of associated consts,
2510 // even if they are potentially not const evaluatable.
2512 // Type parameters can already be used and as associated consts are
2513 // not used as part of the type system, this is far less surprising.
2514 self.with_lifetime_rib(
2515 LifetimeRibKind::Elided(LifetimeRes::Infer),
2517 this.with_constant_rib(
2519 ConstantHasGenerics::Yes,
2521 |this| this.visit_expr(expr),
2527 AssocItemKind::Fn(box Fn { generics, .. }) => {
2528 walk_assoc_item(self, generics, LifetimeBinderKind::Function, item);
2530 AssocItemKind::TyAlias(box TyAlias { generics, .. }) => self
2531 .with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2532 walk_assoc_item(this, generics, LifetimeBinderKind::Item, item)
2534 AssocItemKind::MacCall(_) => {
2535 panic!("unexpanded macro in resolve!")
2540 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
2543 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
2544 fn with_optional_trait_ref<T>(
2546 opt_trait_ref: Option<&TraitRef>,
2547 self_type: &'ast Ty,
2548 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
2550 let mut new_val = None;
2551 let mut new_id = None;
2552 if let Some(trait_ref) = opt_trait_ref {
2553 let path: Vec<_> = Segment::from_path(&trait_ref.path);
2554 self.diagnostic_metadata.currently_processing_impl_trait =
2555 Some((trait_ref.clone(), self_type.clone()));
2556 let res = self.smart_resolve_path_fragment(
2559 PathSource::Trait(AliasPossibility::No),
2560 Finalize::new(trait_ref.ref_id, trait_ref.path.span),
2562 self.diagnostic_metadata.currently_processing_impl_trait = None;
2563 if let Some(def_id) = res.base_res().opt_def_id() {
2564 new_id = Some(def_id);
2565 new_val = Some((self.r.expect_module(def_id), trait_ref.clone()));
2568 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
2569 let result = f(self, new_id);
2570 self.current_trait_ref = original_trait_ref;
2574 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
2575 let mut self_type_rib = Rib::new(NormalRibKind);
2577 // Plain insert (no renaming, since types are not currently hygienic)
2578 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
2579 self.ribs[ns].push(self_type_rib);
2581 self.ribs[ns].pop();
2584 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
2585 self.with_self_rib_ns(TypeNS, self_res, f)
2588 fn resolve_implementation(
2590 generics: &'ast Generics,
2591 opt_trait_reference: &'ast Option<TraitRef>,
2592 self_type: &'ast Ty,
2594 impl_items: &'ast [P<AssocItem>],
2596 debug!("resolve_implementation");
2597 // If applicable, create a rib for the type parameters.
2598 self.with_generic_param_rib(
2600 ItemRibKind(HasGenericParams::Yes(generics.span)),
2601 LifetimeRibKind::Generics {
2602 span: generics.span,
2604 kind: LifetimeBinderKind::ImplBlock,
2607 // Dummy self type for better errors if `Self` is used in the trait path.
2608 this.with_self_rib(Res::SelfTy { trait_: None, alias_to: None }, |this| {
2609 this.with_lifetime_rib(
2610 LifetimeRibKind::AnonymousCreateParameter {
2612 report_in_path: true
2615 // Resolve the trait reference, if necessary.
2616 this.with_optional_trait_ref(
2617 opt_trait_reference.as_ref(),
2620 let item_def_id = this.r.local_def_id(item_id);
2622 // Register the trait definitions from here.
2623 if let Some(trait_id) = trait_id {
2631 let item_def_id = item_def_id.to_def_id();
2632 let res = Res::SelfTy {
2634 alias_to: Some((item_def_id, false)),
2636 this.with_self_rib(res, |this| {
2637 if let Some(trait_ref) = opt_trait_reference.as_ref() {
2638 // Resolve type arguments in the trait path.
2639 visit::walk_trait_ref(this, trait_ref);
2641 // Resolve the self type.
2642 this.visit_ty(self_type);
2643 // Resolve the generic parameters.
2644 this.visit_generics(generics);
2646 // Resolve the items within the impl.
2647 this.with_current_self_type(self_type, |this| {
2648 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
2649 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
2650 for item in impl_items {
2651 this.resolve_impl_item(&**item);
2665 fn resolve_impl_item(&mut self, item: &'ast AssocItem) {
2666 use crate::ResolutionError::*;
2668 AssocItemKind::Const(_, ty, default) => {
2669 debug!("resolve_implementation AssocItemKind::Const");
2670 // If this is a trait impl, ensure the const
2672 self.check_trait_item(
2678 |i, s, c| ConstNotMemberOfTrait(i, s, c),
2682 if let Some(expr) = default {
2683 // We allow arbitrary const expressions inside of associated consts,
2684 // even if they are potentially not const evaluatable.
2686 // Type parameters can already be used and as associated consts are
2687 // not used as part of the type system, this is far less surprising.
2688 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2689 this.with_constant_rib(
2691 ConstantHasGenerics::Yes,
2693 |this| this.visit_expr(expr),
2698 AssocItemKind::Fn(box Fn { generics, .. }) => {
2699 debug!("resolve_implementation AssocItemKind::Fn");
2700 // We also need a new scope for the impl item type parameters.
2701 self.with_generic_param_rib(
2704 LifetimeRibKind::Generics {
2706 span: generics.span,
2707 kind: LifetimeBinderKind::Function,
2710 // If this is a trait impl, ensure the method
2712 this.check_trait_item(
2718 |i, s, c| MethodNotMemberOfTrait(i, s, c),
2721 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2725 AssocItemKind::TyAlias(box TyAlias { generics, .. }) => {
2726 debug!("resolve_implementation AssocItemKind::TyAlias");
2727 // We also need a new scope for the impl item type parameters.
2728 self.with_generic_param_rib(
2731 LifetimeRibKind::Generics {
2733 span: generics.span,
2734 kind: LifetimeBinderKind::Item,
2737 this.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2738 // If this is a trait impl, ensure the type
2740 this.check_trait_item(
2746 |i, s, c| TypeNotMemberOfTrait(i, s, c),
2749 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2754 AssocItemKind::MacCall(_) => {
2755 panic!("unexpanded macro in resolve!")
2760 fn check_trait_item<F>(
2764 kind: &AssocItemKind,
2769 F: FnOnce(Ident, String, Option<Symbol>) -> ResolutionError<'a>,
2771 // If there is a TraitRef in scope for an impl, then the method must be in the trait.
2772 let Some((module, _)) = &self.current_trait_ref else { return; };
2773 ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
2774 let key = self.r.new_key(ident, ns);
2775 let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2777 if binding.is_none() {
2778 // We could not find the trait item in the correct namespace.
2779 // Check the other namespace to report an error.
2785 let key = self.r.new_key(ident, ns);
2786 binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2789 let Some(binding) = binding else {
2790 // We could not find the method: report an error.
2791 let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
2792 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2793 let path_names = path_names_to_string(path);
2794 self.report_error(span, err(ident, path_names, candidate));
2798 let res = binding.res();
2799 let Res::Def(def_kind, _) = res else { bug!() };
2800 match (def_kind, kind) {
2801 (DefKind::AssocTy, AssocItemKind::TyAlias(..))
2802 | (DefKind::AssocFn, AssocItemKind::Fn(..))
2803 | (DefKind::AssocConst, AssocItemKind::Const(..)) => {
2804 self.r.record_partial_res(id, PartialRes::new(res));
2810 // The method kind does not correspond to what appeared in the trait, report.
2811 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2812 let (code, kind) = match kind {
2813 AssocItemKind::Const(..) => (rustc_errors::error_code!(E0323), "const"),
2814 AssocItemKind::Fn(..) => (rustc_errors::error_code!(E0324), "method"),
2815 AssocItemKind::TyAlias(..) => (rustc_errors::error_code!(E0325), "type"),
2816 AssocItemKind::MacCall(..) => span_bug!(span, "unexpanded macro"),
2818 let trait_path = path_names_to_string(path);
2821 ResolutionError::TraitImplMismatch {
2826 trait_item_span: binding.span,
2831 fn resolve_params(&mut self, params: &'ast [Param]) {
2832 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2833 for Param { pat, ty, .. } in params {
2834 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
2836 debug!("(resolving function / closure) recorded parameter");
2840 fn resolve_local(&mut self, local: &'ast Local) {
2841 debug!("resolving local ({:?})", local);
2842 // Resolve the type.
2843 walk_list!(self, visit_ty, &local.ty);
2845 // Resolve the initializer.
2846 if let Some((init, els)) = local.kind.init_else_opt() {
2847 self.visit_expr(init);
2849 // Resolve the `else` block
2850 if let Some(els) = els {
2851 self.visit_block(els);
2855 // Resolve the pattern.
2856 self.resolve_pattern_top(&local.pat, PatternSource::Let);
2859 /// build a map from pattern identifiers to binding-info's.
2860 /// this is done hygienically. This could arise for a macro
2861 /// that expands into an or-pattern where one 'x' was from the
2862 /// user and one 'x' came from the macro.
2863 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2864 let mut binding_map = FxHashMap::default();
2866 pat.walk(&mut |pat| {
2868 PatKind::Ident(binding_mode, ident, ref sub_pat)
2869 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
2871 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
2873 PatKind::Or(ref ps) => {
2874 // Check the consistency of this or-pattern and
2875 // then add all bindings to the larger map.
2876 for bm in self.check_consistent_bindings(ps) {
2877 binding_map.extend(bm);
2890 fn is_base_res_local(&self, nid: NodeId) -> bool {
2891 matches!(self.r.partial_res_map.get(&nid).map(|res| res.base_res()), Some(Res::Local(..)))
2894 /// Checks that all of the arms in an or-pattern have exactly the
2895 /// same set of bindings, with the same binding modes for each.
2896 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
2897 let mut missing_vars = FxHashMap::default();
2898 let mut inconsistent_vars = FxHashMap::default();
2900 // 1) Compute the binding maps of all arms.
2901 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
2903 // 2) Record any missing bindings or binding mode inconsistencies.
2904 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
2905 // Check against all arms except for the same pattern which is always self-consistent.
2909 .filter(|(_, pat)| pat.id != pat_outer.id)
2910 .flat_map(|(idx, _)| maps[idx].iter())
2911 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
2913 for (name, info, &binding_inner) in inners {
2916 // The inner binding is missing in the outer.
2918 missing_vars.entry(name).or_insert_with(|| BindingError {
2920 origin: BTreeSet::new(),
2921 target: BTreeSet::new(),
2922 could_be_path: name.as_str().starts_with(char::is_uppercase),
2924 binding_error.origin.insert(binding_inner.span);
2925 binding_error.target.insert(pat_outer.span);
2927 Some(binding_outer) => {
2928 if binding_outer.binding_mode != binding_inner.binding_mode {
2929 // The binding modes in the outer and inner bindings differ.
2932 .or_insert((binding_inner.span, binding_outer.span));
2939 // 3) Report all missing variables we found.
2940 let mut missing_vars = missing_vars.into_iter().collect::<Vec<_>>();
2941 missing_vars.sort_by_key(|&(sym, ref _err)| sym);
2943 for (name, mut v) in missing_vars.into_iter() {
2944 if inconsistent_vars.contains_key(&name) {
2945 v.could_be_path = false;
2948 *v.origin.iter().next().unwrap(),
2949 ResolutionError::VariableNotBoundInPattern(v, self.parent_scope),
2953 // 4) Report all inconsistencies in binding modes we found.
2954 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
2955 inconsistent_vars.sort();
2956 for (name, v) in inconsistent_vars {
2957 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
2960 // 5) Finally bubble up all the binding maps.
2964 /// Check the consistency of the outermost or-patterns.
2965 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
2966 pat.walk(&mut |pat| match pat.kind {
2967 PatKind::Or(ref ps) => {
2968 self.check_consistent_bindings(ps);
2975 fn resolve_arm(&mut self, arm: &'ast Arm) {
2976 self.with_rib(ValueNS, NormalRibKind, |this| {
2977 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
2978 walk_list!(this, visit_expr, &arm.guard);
2979 this.visit_expr(&arm.body);
2983 /// Arising from `source`, resolve a top level pattern.
2984 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
2985 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2986 self.resolve_pattern(pat, pat_src, &mut bindings);
2992 pat_src: PatternSource,
2993 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
2995 // We walk the pattern before declaring the pattern's inner bindings,
2996 // so that we avoid resolving a literal expression to a binding defined
2998 visit::walk_pat(self, pat);
2999 self.resolve_pattern_inner(pat, pat_src, bindings);
3000 // This has to happen *after* we determine which pat_idents are variants:
3001 self.check_consistent_bindings_top(pat);
3004 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
3008 /// A stack of sets of bindings accumulated.
3010 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
3011 /// be interpreted as re-binding an already bound binding. This results in an error.
3012 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
3013 /// in reusing this binding rather than creating a fresh one.
3015 /// When called at the top level, the stack must have a single element
3016 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
3017 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
3018 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
3019 /// When each `p_i` has been dealt with, the top set is merged with its parent.
3020 /// When a whole or-pattern has been dealt with, the thing happens.
3022 /// See the implementation and `fresh_binding` for more details.
3023 fn resolve_pattern_inner(
3026 pat_src: PatternSource,
3027 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3029 // Visit all direct subpatterns of this pattern.
3030 pat.walk(&mut |pat| {
3031 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
3033 PatKind::Ident(bmode, ident, ref sub) => {
3034 // First try to resolve the identifier as some existing entity,
3035 // then fall back to a fresh binding.
3036 let has_sub = sub.is_some();
3038 .try_resolve_as_non_binding(pat_src, bmode, ident, has_sub)
3039 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
3040 self.r.record_partial_res(pat.id, PartialRes::new(res));
3041 self.r.record_pat_span(pat.id, pat.span);
3043 PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
3044 self.smart_resolve_path(
3048 PathSource::TupleStruct(
3050 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
3054 PatKind::Path(ref qself, ref path) => {
3055 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
3057 PatKind::Struct(ref qself, ref path, ..) => {
3058 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Struct);
3060 PatKind::Or(ref ps) => {
3061 // Add a new set of bindings to the stack. `Or` here records that when a
3062 // binding already exists in this set, it should not result in an error because
3063 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
3064 bindings.push((PatBoundCtx::Or, Default::default()));
3066 // Now we need to switch back to a product context so that each
3067 // part of the or-pattern internally rejects already bound names.
3068 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
3069 bindings.push((PatBoundCtx::Product, Default::default()));
3070 self.resolve_pattern_inner(p, pat_src, bindings);
3071 // Move up the non-overlapping bindings to the or-pattern.
3072 // Existing bindings just get "merged".
3073 let collected = bindings.pop().unwrap().1;
3074 bindings.last_mut().unwrap().1.extend(collected);
3076 // This or-pattern itself can itself be part of a product,
3077 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
3078 // Both cases bind `a` again in a product pattern and must be rejected.
3079 let collected = bindings.pop().unwrap().1;
3080 bindings.last_mut().unwrap().1.extend(collected);
3082 // Prevent visiting `ps` as we've already done so above.
3095 pat_src: PatternSource,
3096 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3098 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
3099 // (We must not add it if it's in the bindings map because that breaks the assumptions
3100 // later passes make about or-patterns.)
3101 let ident = ident.normalize_to_macro_rules();
3103 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
3104 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
3105 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
3106 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
3107 // This is *required* for consistency which is checked later.
3108 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
3110 if already_bound_and {
3111 // Overlap in a product pattern somewhere; report an error.
3112 use ResolutionError::*;
3113 let error = match pat_src {
3114 // `fn f(a: u8, a: u8)`:
3115 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
3117 _ => IdentifierBoundMoreThanOnceInSamePattern,
3119 self.report_error(ident.span, error(ident.name));
3122 // Record as bound if it's valid:
3123 let ident_valid = ident.name != kw::Empty;
3125 bindings.last_mut().unwrap().1.insert(ident);
3128 if already_bound_or {
3129 // `Variant1(a) | Variant2(a)`, ok
3130 // Reuse definition from the first `a`.
3131 self.innermost_rib_bindings(ValueNS)[&ident]
3133 let res = Res::Local(pat_id);
3135 // A completely fresh binding add to the set if it's valid.
3136 self.innermost_rib_bindings(ValueNS).insert(ident, res);
3142 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
3143 &mut self.ribs[ns].last_mut().unwrap().bindings
3146 fn try_resolve_as_non_binding(
3148 pat_src: PatternSource,
3153 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
3154 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
3155 // also be interpreted as a path to e.g. a constant, variant, etc.
3156 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
3158 let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?;
3159 let (res, binding) = match ls_binding {
3160 LexicalScopeBinding::Item(binding)
3161 if is_syntactic_ambiguity && binding.is_ambiguity() =>
3163 // For ambiguous bindings we don't know all their definitions and cannot check
3164 // whether they can be shadowed by fresh bindings or not, so force an error.
3165 // issues/33118#issuecomment-233962221 (see below) still applies here,
3166 // but we have to ignore it for backward compatibility.
3167 self.r.record_use(ident, binding, false);
3170 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
3171 LexicalScopeBinding::Res(res) => (res, None),
3175 Res::SelfCtor(_) // See #70549.
3177 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
3179 ) if is_syntactic_ambiguity => {
3180 // Disambiguate in favor of a unit struct/variant or constant pattern.
3181 if let Some(binding) = binding {
3182 self.r.record_use(ident, binding, false);
3186 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static(_), _) => {
3187 // This is unambiguously a fresh binding, either syntactically
3188 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
3189 // to something unusable as a pattern (e.g., constructor function),
3190 // but we still conservatively report an error, see
3191 // issues/33118#issuecomment-233962221 for one reason why.
3192 let binding = binding.expect("no binding for a ctor or static");
3195 ResolutionError::BindingShadowsSomethingUnacceptable {
3196 shadowing_binding: pat_src,
3198 participle: if binding.is_import() { "imported" } else { "defined" },
3199 article: binding.res().article(),
3200 shadowed_binding: binding.res(),
3201 shadowed_binding_span: binding.span,
3206 Res::Def(DefKind::ConstParam, def_id) => {
3207 // Same as for DefKind::Const above, but here, `binding` is `None`, so we
3208 // have to construct the error differently
3211 ResolutionError::BindingShadowsSomethingUnacceptable {
3212 shadowing_binding: pat_src,
3214 participle: "defined",
3215 article: res.article(),
3216 shadowed_binding: res,
3217 shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"),
3222 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
3223 // These entities are explicitly allowed to be shadowed by fresh bindings.
3226 Res::SelfCtor(_) => {
3227 // We resolve `Self` in pattern position as an ident sometimes during recovery,
3228 // so delay a bug instead of ICEing.
3229 self.r.session.delay_span_bug(
3231 "unexpected `SelfCtor` in pattern, expected identifier"
3237 "unexpected resolution for an identifier in pattern: {:?}",
3243 // High-level and context dependent path resolution routine.
3244 // Resolves the path and records the resolution into definition map.
3245 // If resolution fails tries several techniques to find likely
3246 // resolution candidates, suggest imports or other help, and report
3247 // errors in user friendly way.
3248 fn smart_resolve_path(
3251 qself: Option<&QSelf>,
3253 source: PathSource<'ast>,
3255 self.smart_resolve_path_fragment(
3257 &Segment::from_path(path),
3259 Finalize::new(id, path.span),
3263 fn smart_resolve_path_fragment(
3265 qself: Option<&QSelf>,
3267 source: PathSource<'ast>,
3271 "smart_resolve_path_fragment(qself={:?}, path={:?}, finalize={:?})",
3272 qself, path, finalize,
3274 let ns = source.namespace();
3276 let Finalize { node_id, path_span, .. } = finalize;
3277 let report_errors = |this: &mut Self, res: Option<Res>| {
3278 if this.should_report_errs() {
3279 let (err, candidates) =
3280 this.smart_resolve_report_errors(path, path_span, source, res);
3282 let def_id = this.parent_scope.module.nearest_parent_mod();
3283 let instead = res.is_some();
3285 if res.is_none() { this.report_missing_type_error(path) } else { None };
3287 this.r.use_injections.push(UseError {
3297 PartialRes::new(Res::Err)
3300 // For paths originating from calls (like in `HashMap::new()`), tries
3301 // to enrich the plain `failed to resolve: ...` message with hints
3302 // about possible missing imports.
3304 // Similar thing, for types, happens in `report_errors` above.
3305 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
3306 if !source.is_call() {
3307 return Some(parent_err);
3310 // Before we start looking for candidates, we have to get our hands
3311 // on the type user is trying to perform invocation on; basically:
3312 // we're transforming `HashMap::new` into just `HashMap`.
3313 let path = match path.split_last() {
3314 Some((_, path)) if !path.is_empty() => path,
3315 _ => return Some(parent_err),
3318 let (mut err, candidates) =
3319 this.smart_resolve_report_errors(path, path_span, PathSource::Type, None);
3321 if candidates.is_empty() {
3323 return Some(parent_err);
3326 // There are two different error messages user might receive at
3328 // - E0412 cannot find type `{}` in this scope
3329 // - E0433 failed to resolve: use of undeclared type or module `{}`
3331 // The first one is emitted for paths in type-position, and the
3332 // latter one - for paths in expression-position.
3334 // Thus (since we're in expression-position at this point), not to
3335 // confuse the user, we want to keep the *message* from E0432 (so
3336 // `parent_err`), but we want *hints* from E0412 (so `err`).
3338 // And that's what happens below - we're just mixing both messages
3339 // into a single one.
3340 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
3342 err.message = take(&mut parent_err.message);
3343 err.code = take(&mut parent_err.code);
3344 err.children = take(&mut parent_err.children);
3346 parent_err.cancel();
3348 let def_id = this.parent_scope.module.nearest_parent_mod();
3350 if this.should_report_errs() {
3351 this.r.use_injections.push(UseError {
3363 // We don't return `Some(parent_err)` here, because the error will
3364 // be already printed as part of the `use` injections
3368 let partial_res = match self.resolve_qpath_anywhere(
3373 source.defer_to_typeck(),
3376 Ok(Some(partial_res)) if partial_res.unresolved_segments() == 0 => {
3377 if source.is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err
3381 report_errors(self, Some(partial_res.base_res()))
3385 Ok(Some(partial_res)) if source.defer_to_typeck() => {
3386 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
3387 // or `<T>::A::B`. If `B` should be resolved in value namespace then
3388 // it needs to be added to the trait map.
3390 let item_name = path.last().unwrap().ident;
3391 let traits = self.traits_in_scope(item_name, ns);
3392 self.r.trait_map.insert(node_id, traits);
3395 if PrimTy::from_name(path[0].ident.name).is_some() {
3396 let mut std_path = Vec::with_capacity(1 + path.len());
3398 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
3399 std_path.extend(path);
3400 if let PathResult::Module(_) | PathResult::NonModule(_) =
3401 self.resolve_path(&std_path, Some(ns), None)
3403 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
3405 path.iter().last().map_or(path_span, |segment| segment.ident.span);
3407 self.r.confused_type_with_std_module.insert(item_span, path_span);
3408 self.r.confused_type_with_std_module.insert(path_span, path_span);
3416 if let Some(err) = report_errors_for_call(self, err) {
3417 self.report_error(err.span, err.node);
3420 PartialRes::new(Res::Err)
3423 _ => report_errors(self, None),
3426 if !matches!(source, PathSource::TraitItem(..)) {
3427 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
3428 self.r.record_partial_res(node_id, partial_res);
3429 self.resolve_elided_lifetimes_in_path(node_id, partial_res, path, source, path_span);
3435 fn self_type_is_available(&mut self) -> bool {
3437 .maybe_resolve_ident_in_lexical_scope(Ident::with_dummy_span(kw::SelfUpper), TypeNS);
3438 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3441 fn self_value_is_available(&mut self, self_span: Span) -> bool {
3442 let ident = Ident::new(kw::SelfLower, self_span);
3443 let binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS);
3444 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3447 /// A wrapper around [`Resolver::report_error`].
3449 /// This doesn't emit errors for function bodies if this is rustdoc.
3450 fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) {
3451 if self.should_report_errs() {
3452 self.r.report_error(span, resolution_error);
3457 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
3458 fn should_report_errs(&self) -> bool {
3459 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
3462 // Resolve in alternative namespaces if resolution in the primary namespace fails.
3463 fn resolve_qpath_anywhere(
3465 qself: Option<&QSelf>,
3467 primary_ns: Namespace,
3469 defer_to_typeck: bool,
3471 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3472 let mut fin_res = None;
3474 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
3475 if i == 0 || ns != primary_ns {
3476 match self.resolve_qpath(qself, path, ns, finalize)? {
3478 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
3480 return Ok(Some(partial_res));
3483 if fin_res.is_none() {
3484 fin_res = partial_res;
3491 assert!(primary_ns != MacroNS);
3493 if qself.is_none() {
3494 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
3495 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
3496 if let Ok((_, res)) =
3497 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
3499 return Ok(Some(PartialRes::new(res)));
3506 /// Handles paths that may refer to associated items.
3509 qself: Option<&QSelf>,
3513 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3515 "resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})",
3516 qself, path, ns, finalize,
3519 if let Some(qself) = qself {
3520 if qself.position == 0 {
3521 // This is a case like `<T>::B`, where there is no
3522 // trait to resolve. In that case, we leave the `B`
3523 // segment to be resolved by type-check.
3524 return Ok(Some(PartialRes::with_unresolved_segments(
3525 Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()),
3530 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
3532 // Currently, `path` names the full item (`A::B::C`, in
3533 // our example). so we extract the prefix of that that is
3534 // the trait (the slice upto and including
3535 // `qself.position`). And then we recursively resolve that,
3536 // but with `qself` set to `None`.
3537 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
3538 let partial_res = self.smart_resolve_path_fragment(
3540 &path[..=qself.position],
3541 PathSource::TraitItem(ns),
3542 Finalize::with_root_span(finalize.node_id, finalize.path_span, qself.path_span),
3545 // The remaining segments (the `C` in our example) will
3546 // have to be resolved by type-check, since that requires doing
3547 // trait resolution.
3548 return Ok(Some(PartialRes::with_unresolved_segments(
3549 partial_res.base_res(),
3550 partial_res.unresolved_segments() + path.len() - qself.position - 1,
3554 let result = match self.resolve_path(&path, Some(ns), Some(finalize)) {
3555 PathResult::NonModule(path_res) => path_res,
3556 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
3557 PartialRes::new(module.res().unwrap())
3559 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
3560 // don't report an error right away, but try to fallback to a primitive type.
3561 // So, we are still able to successfully resolve something like
3563 // use std::u8; // bring module u8 in scope
3564 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
3565 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
3566 // // not to non-existent std::u8::max_value
3569 // Such behavior is required for backward compatibility.
3570 // The same fallback is used when `a` resolves to nothing.
3571 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
3572 if (ns == TypeNS || path.len() > 1)
3573 && PrimTy::from_name(path[0].ident.name).is_some() =>
3575 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
3576 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
3578 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3579 PartialRes::new(module.res().unwrap())
3581 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
3582 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
3584 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
3585 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
3589 && result.base_res() != Res::Err
3590 && path[0].ident.name != kw::PathRoot
3591 && path[0].ident.name != kw::DollarCrate
3593 let unqualified_result = {
3594 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
3595 PathResult::NonModule(path_res) => path_res.base_res(),
3596 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3597 module.res().unwrap()
3599 _ => return Ok(Some(result)),
3602 if result.base_res() == unqualified_result {
3603 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
3604 self.r.lint_buffer.buffer_lint(
3608 "unnecessary qualification",
3616 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
3617 if let Some(label) = label {
3618 if label.ident.as_str().as_bytes()[1] != b'_' {
3619 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
3622 if let Ok((_, orig_span)) = self.resolve_label(label.ident) {
3623 diagnostics::signal_label_shadowing(self.r.session, orig_span, label.ident)
3626 self.with_label_rib(NormalRibKind, |this| {
3627 let ident = label.ident.normalize_to_macro_rules();
3628 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
3636 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
3637 self.with_resolved_label(label, id, |this| this.visit_block(block));
3640 fn resolve_block(&mut self, block: &'ast Block) {
3641 debug!("(resolving block) entering block");
3642 // Move down in the graph, if there's an anonymous module rooted here.
3643 let orig_module = self.parent_scope.module;
3644 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
3646 let mut num_macro_definition_ribs = 0;
3647 if let Some(anonymous_module) = anonymous_module {
3648 debug!("(resolving block) found anonymous module, moving down");
3649 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3650 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3651 self.parent_scope.module = anonymous_module;
3653 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3656 let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
3657 if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
3658 (block.could_be_bare_literal, &block.stmts[..])
3659 && let ExprKind::Type(..) = expr.kind
3661 self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
3664 // Descend into the block.
3665 for stmt in &block.stmts {
3666 if let StmtKind::Item(ref item) = stmt.kind
3667 && let ItemKind::MacroDef(..) = item.kind {
3668 num_macro_definition_ribs += 1;
3669 let res = self.r.local_def_id(item.id).to_def_id();
3670 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
3671 self.label_ribs.push(Rib::new(MacroDefinition(res)));
3674 self.visit_stmt(stmt);
3676 self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
3679 self.parent_scope.module = orig_module;
3680 for _ in 0..num_macro_definition_ribs {
3681 self.ribs[ValueNS].pop();
3682 self.label_ribs.pop();
3684 self.ribs[ValueNS].pop();
3685 if anonymous_module.is_some() {
3686 self.ribs[TypeNS].pop();
3688 debug!("(resolving block) leaving block");
3691 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
3692 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
3693 self.with_constant_rib(
3695 if constant.value.is_potential_trivial_const_param() {
3696 ConstantHasGenerics::Yes
3698 ConstantHasGenerics::No
3701 |this| visit::walk_anon_const(this, constant),
3705 fn resolve_inline_const(&mut self, constant: &'ast AnonConst) {
3706 debug!("resolve_anon_const {constant:?}");
3707 self.with_constant_rib(IsRepeatExpr::No, ConstantHasGenerics::Yes, None, |this| {
3708 visit::walk_anon_const(this, constant)
3712 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
3713 // First, record candidate traits for this expression if it could
3714 // result in the invocation of a method call.
3716 self.record_candidate_traits_for_expr_if_necessary(expr);
3718 // Next, resolve the node.
3720 ExprKind::Path(ref qself, ref path) => {
3721 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
3722 visit::walk_expr(self, expr);
3725 ExprKind::Struct(ref se) => {
3726 self.smart_resolve_path(expr.id, se.qself.as_ref(), &se.path, PathSource::Struct);
3727 visit::walk_expr(self, expr);
3730 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
3731 match self.resolve_label(label.ident) {
3732 Ok((node_id, _)) => {
3733 // Since this res is a label, it is never read.
3734 self.r.label_res_map.insert(expr.id, node_id);
3735 self.diagnostic_metadata.unused_labels.remove(&node_id);
3738 self.report_error(label.ident.span, error);
3742 // visit `break` argument if any
3743 visit::walk_expr(self, expr);
3746 ExprKind::Break(None, Some(ref e)) => {
3747 // We use this instead of `visit::walk_expr` to keep the parent expr around for
3748 // better diagnostics.
3749 self.resolve_expr(e, Some(&expr));
3752 ExprKind::Let(ref pat, ref scrutinee, _) => {
3753 self.visit_expr(scrutinee);
3754 self.resolve_pattern_top(pat, PatternSource::Let);
3757 ExprKind::If(ref cond, ref then, ref opt_else) => {
3758 self.with_rib(ValueNS, NormalRibKind, |this| {
3759 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3760 this.visit_expr(cond);
3761 this.diagnostic_metadata.in_if_condition = old;
3762 this.visit_block(then);
3764 if let Some(expr) = opt_else {
3765 self.visit_expr(expr);
3769 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3771 ExprKind::While(ref cond, ref block, label) => {
3772 self.with_resolved_label(label, expr.id, |this| {
3773 this.with_rib(ValueNS, NormalRibKind, |this| {
3774 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3775 this.visit_expr(cond);
3776 this.diagnostic_metadata.in_if_condition = old;
3777 this.visit_block(block);
3782 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
3783 self.visit_expr(iter_expr);
3784 self.with_rib(ValueNS, NormalRibKind, |this| {
3785 this.resolve_pattern_top(pat, PatternSource::For);
3786 this.resolve_labeled_block(label, expr.id, block);
3790 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
3792 // Equivalent to `visit::walk_expr` + passing some context to children.
3793 ExprKind::Field(ref subexpression, _) => {
3794 self.resolve_expr(subexpression, Some(expr));
3796 ExprKind::MethodCall(ref segment, ref receiver, ref arguments, _) => {
3797 self.resolve_expr(receiver, Some(expr));
3798 for argument in arguments {
3799 self.resolve_expr(argument, None);
3801 self.visit_path_segment(expr.span, segment);
3804 ExprKind::Call(ref callee, ref arguments) => {
3805 self.resolve_expr(callee, Some(expr));
3806 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
3807 for (idx, argument) in arguments.iter().enumerate() {
3808 // Constant arguments need to be treated as AnonConst since
3809 // that is how they will be later lowered to HIR.
3810 if const_args.contains(&idx) {
3811 self.with_constant_rib(
3813 if argument.is_potential_trivial_const_param() {
3814 ConstantHasGenerics::Yes
3816 ConstantHasGenerics::No
3820 this.resolve_expr(argument, None);
3824 self.resolve_expr(argument, None);
3828 ExprKind::Type(ref type_expr, ref ty) => {
3829 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
3830 // type ascription. Here we are trying to retrieve the span of the colon token as
3831 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
3832 // with `expr::Ty`, only in this case it will match the span from
3833 // `type_ascription_path_suggestions`.
3834 self.diagnostic_metadata
3835 .current_type_ascription
3836 .push(type_expr.span.between(ty.span));
3837 visit::walk_expr(self, expr);
3838 self.diagnostic_metadata.current_type_ascription.pop();
3840 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
3841 // resolve the arguments within the proper scopes so that usages of them inside the
3842 // closure are detected as upvars rather than normal closure arg usages.
3843 ExprKind::Closure(_, _, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
3844 self.with_rib(ValueNS, NormalRibKind, |this| {
3845 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
3846 // Resolve arguments:
3847 this.resolve_params(&fn_decl.inputs);
3848 // No need to resolve return type --
3849 // the outer closure return type is `FnRetTy::Default`.
3851 // Now resolve the inner closure
3853 // No need to resolve arguments: the inner closure has none.
3854 // Resolve the return type:
3855 visit::walk_fn_ret_ty(this, &fn_decl.output);
3857 this.visit_expr(body);
3862 // For closures, ClosureOrAsyncRibKind is added in visit_fn
3863 ExprKind::Closure(ClosureBinder::For { ref generic_params, span }, ..) => {
3864 self.with_generic_param_rib(
3867 LifetimeRibKind::Generics {
3869 kind: LifetimeBinderKind::Closure,
3872 |this| visit::walk_expr(this, expr),
3875 ExprKind::Closure(..) => visit::walk_expr(self, expr),
3876 ExprKind::Async(..) => {
3877 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
3879 ExprKind::Repeat(ref elem, ref ct) => {
3880 self.visit_expr(elem);
3881 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
3882 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
3883 this.resolve_anon_const(ct, IsRepeatExpr::Yes)
3887 ExprKind::ConstBlock(ref ct) => {
3888 self.resolve_inline_const(ct);
3890 ExprKind::Index(ref elem, ref idx) => {
3891 self.resolve_expr(elem, Some(expr));
3892 self.visit_expr(idx);
3895 visit::walk_expr(self, expr);
3900 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
3902 ExprKind::Field(_, ident) => {
3903 // FIXME(#6890): Even though you can't treat a method like a
3904 // field, we need to add any trait methods we find that match
3905 // the field name so that we can do some nice error reporting
3906 // later on in typeck.
3907 let traits = self.traits_in_scope(ident, ValueNS);
3908 self.r.trait_map.insert(expr.id, traits);
3910 ExprKind::MethodCall(ref segment, ..) => {
3911 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
3912 let traits = self.traits_in_scope(segment.ident, ValueNS);
3913 self.r.trait_map.insert(expr.id, traits);
3921 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
3922 self.r.traits_in_scope(
3923 self.current_trait_ref.as_ref().map(|(module, _)| *module),
3926 Some((ident.name, ns)),
3931 struct LifetimeCountVisitor<'a, 'b> {
3932 r: &'b mut Resolver<'a>,
3935 /// Walks the whole crate in DFS order, visiting each item, counting the declared number of
3936 /// lifetime generic parameters.
3937 impl<'ast> Visitor<'ast> for LifetimeCountVisitor<'_, '_> {
3938 fn visit_item(&mut self, item: &'ast Item) {
3940 ItemKind::TyAlias(box TyAlias { ref generics, .. })
3941 | ItemKind::Fn(box Fn { ref generics, .. })
3942 | ItemKind::Enum(_, ref generics)
3943 | ItemKind::Struct(_, ref generics)
3944 | ItemKind::Union(_, ref generics)
3945 | ItemKind::Impl(box Impl { ref generics, .. })
3946 | ItemKind::Trait(box Trait { ref generics, .. })
3947 | ItemKind::TraitAlias(ref generics, _) => {
3948 let def_id = self.r.local_def_id(item.id);
3949 let count = generics
3952 .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
3954 self.r.item_generics_num_lifetimes.insert(def_id, count);
3958 | ItemKind::ForeignMod(..)
3959 | ItemKind::Static(..)
3960 | ItemKind::Const(..)
3962 | ItemKind::ExternCrate(..)
3963 | ItemKind::MacroDef(..)
3964 | ItemKind::GlobalAsm(..)
3965 | ItemKind::MacCall(..) => {}
3967 visit::walk_item(self, item)
3971 impl<'a> Resolver<'a> {
3972 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
3973 visit::walk_crate(&mut LifetimeCountVisitor { r: self }, krate);
3974 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
3975 visit::walk_crate(&mut late_resolution_visitor, krate);
3976 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
3977 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");