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::{DiagnosticArgValue, DiagnosticId, IntoDiagnosticArg};
20 use rustc_hir::def::Namespace::{self, *};
21 use rustc_hir::def::{self, CtorKind, DefKind, LifetimeRes, PartialRes, PerNS};
22 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
23 use rustc_hir::{BindingAnnotation, PrimTy, TraitCandidate};
24 use rustc_middle::middle::resolve_lifetime::Set1;
25 use rustc_middle::ty::DefIdTree;
26 use rustc_middle::{bug, span_bug};
27 use rustc_session::lint;
28 use rustc_span::symbol::{kw, sym, Ident, Symbol};
29 use rustc_span::{BytePos, Span};
30 use smallvec::{smallvec, SmallVec};
32 use rustc_span::source_map::{respan, Spanned};
33 use std::assert_matches::debug_assert_matches;
35 use std::collections::{hash_map::Entry, BTreeSet};
36 use std::mem::{replace, swap, take};
40 type Res = def::Res<NodeId>;
42 type IdentMap<T> = FxHashMap<Ident, T>;
44 /// Map from the name in a pattern to its binding mode.
45 type BindingMap = IdentMap<BindingInfo>;
48 ElisionFnParameter, LifetimeElisionCandidate, MissingLifetime, MissingLifetimeKind,
51 #[derive(Copy, Clone, Debug)]
54 annotation: BindingAnnotation,
57 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
58 pub enum PatternSource {
65 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
72 pub fn descr(self) -> &'static str {
74 PatternSource::Match => "match binding",
75 PatternSource::Let => "let binding",
76 PatternSource::For => "for binding",
77 PatternSource::FnParam => "function parameter",
82 impl IntoDiagnosticArg for PatternSource {
83 fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
84 DiagnosticArgValue::Str(Cow::Borrowed(self.descr()))
88 /// Denotes whether the context for the set of already bound bindings is a `Product`
89 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
90 /// See those functions for more information.
93 /// A product pattern context, e.g., `Variant(a, b)`.
95 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
99 /// Does this the item (from the item rib scope) allow generic parameters?
100 #[derive(Copy, Clone, Debug)]
101 pub(crate) enum HasGenericParams {
106 /// May this constant have generics?
107 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
108 pub(crate) enum ConstantHasGenerics {
113 impl ConstantHasGenerics {
114 fn force_yes_if(self, b: bool) -> Self {
115 if b { Self::Yes } else { self }
119 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
120 pub(crate) enum ConstantItemKind {
125 /// The rib kind restricts certain accesses,
126 /// e.g. to a `Res::Local` of an outer item.
127 #[derive(Copy, Clone, Debug)]
128 pub(crate) enum RibKind<'a> {
129 /// No restriction needs to be applied.
132 /// We passed through an impl or trait and are now in one of its
133 /// methods or associated types. Allow references to ty params that impl or trait
134 /// binds. Disallow any other upvars (including other ty params that are
138 /// We passed through a closure. Disallow labels.
139 ClosureOrAsyncRibKind,
141 /// We passed through an item scope. Disallow upvars.
142 ItemRibKind(HasGenericParams),
144 /// We're in a constant item. Can't refer to dynamic stuff.
146 /// The item may reference generic parameters in trivial constant expressions.
147 /// All other constants aren't allowed to use generic params at all.
148 ConstantItemRibKind(ConstantHasGenerics, Option<(Ident, ConstantItemKind)>),
150 /// We passed through a module.
151 ModuleRibKind(Module<'a>),
153 /// We passed through a `macro_rules!` statement
154 MacroDefinition(DefId),
156 /// All bindings in this rib are generic parameters that can't be used
157 /// from the default of a generic parameter because they're not declared
158 /// before said generic parameter. Also see the `visit_generics` override.
159 ForwardGenericParamBanRibKind,
161 /// We are inside of the type of a const parameter. Can't refer to any
165 /// We are inside a `sym` inline assembly operand. Can only refer to
171 /// Whether this rib kind contains generic parameters, as opposed to local
173 pub(crate) fn contains_params(&self) -> bool {
176 | ClosureOrAsyncRibKind
177 | ConstantItemRibKind(..)
180 | ConstParamTyRibKind
181 | InlineAsmSymRibKind => false,
182 AssocItemRibKind | ItemRibKind(_) | ForwardGenericParamBanRibKind => true,
186 /// This rib forbids referring to labels defined in upwards ribs.
187 fn is_label_barrier(self) -> bool {
189 NormalRibKind | MacroDefinition(..) => false,
192 | ClosureOrAsyncRibKind
194 | ConstantItemRibKind(..)
196 | ForwardGenericParamBanRibKind
197 | ConstParamTyRibKind
198 | InlineAsmSymRibKind => true,
203 /// A single local scope.
205 /// A rib represents a scope names can live in. Note that these appear in many places, not just
206 /// around braces. At any place where the list of accessible names (of the given namespace)
207 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
208 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
211 /// Different [rib kinds](enum@RibKind) are transparent for different names.
213 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
214 /// resolving, the name is looked up from inside out.
216 pub(crate) struct Rib<'a, R = Res> {
217 pub bindings: IdentMap<R>,
218 pub kind: RibKind<'a>,
221 impl<'a, R> Rib<'a, R> {
222 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
223 Rib { bindings: Default::default(), kind }
227 #[derive(Clone, Copy, Debug)]
228 enum LifetimeUseSet {
229 One { use_span: Span, use_ctxt: visit::LifetimeCtxt },
233 #[derive(Copy, Clone, Debug)]
234 enum LifetimeRibKind {
235 // -- Ribs introducing named lifetimes
237 /// This rib declares generic parameters.
238 /// Only for this kind the `LifetimeRib::bindings` field can be non-empty.
239 Generics { binder: NodeId, span: Span, kind: LifetimeBinderKind },
241 // -- Ribs introducing unnamed lifetimes
243 /// Create a new anonymous lifetime parameter and reference it.
245 /// If `report_in_path`, report an error when encountering lifetime elision in a path:
247 /// struct Foo<'a> { x: &'a () }
248 /// async fn foo(x: Foo) {}
251 /// Note: the error should not trigger when the elided lifetime is in a pattern or
252 /// expression-position path:
254 /// struct Foo<'a> { x: &'a () }
255 /// async fn foo(Foo { x: _ }: Foo<'_>) {}
257 AnonymousCreateParameter { binder: NodeId, report_in_path: bool },
259 /// Replace all anonymous lifetimes by provided lifetime.
262 // -- Barrier ribs that stop lifetime lookup, or continue it but produce an error later.
264 /// Give a hard error when either `&` or `'_` is written. Used to
265 /// rule out things like `where T: Foo<'_>`. Does not imply an
266 /// error on default object bounds (e.g., `Box<dyn Foo>`).
267 AnonymousReportError,
269 /// Signal we cannot find which should be the anonymous lifetime.
272 /// FIXME(const_generics): This patches over an ICE caused by non-'static lifetimes in const
273 /// generics. We are disallowing this until we can decide on how we want to handle non-'static
274 /// lifetimes in const generics. See issue #74052 for discussion.
277 /// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`.
278 /// This function will emit an error if `generic_const_exprs` is not enabled, the body
279 /// identified by `body_id` is an anonymous constant and `lifetime_ref` is non-static.
282 /// This rib acts as a barrier to forbid reference to lifetimes of a parent item.
286 #[derive(Copy, Clone, Debug)]
287 enum LifetimeBinderKind {
297 impl LifetimeBinderKind {
298 fn descr(self) -> &'static str {
299 use LifetimeBinderKind::*;
301 BareFnType => "type",
302 PolyTrait => "bound",
303 WhereBound => "bound",
305 ImplBlock => "impl block",
306 Function => "function",
307 Closure => "closure",
314 kind: LifetimeRibKind,
315 // We need to preserve insertion order for async fns.
316 bindings: FxIndexMap<Ident, (NodeId, LifetimeRes)>,
320 fn new(kind: LifetimeRibKind) -> LifetimeRib {
321 LifetimeRib { bindings: Default::default(), kind }
325 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
326 pub(crate) enum AliasPossibility {
331 #[derive(Copy, Clone, Debug)]
332 pub(crate) enum PathSource<'a> {
333 // Type paths `Path`.
335 // Trait paths in bounds or impls.
336 Trait(AliasPossibility),
337 // Expression paths `path`, with optional parent context.
338 Expr(Option<&'a Expr>),
339 // Paths in path patterns `Path`.
341 // Paths in struct expressions and patterns `Path { .. }`.
343 // Paths in tuple struct patterns `Path(..)`.
344 TupleStruct(Span, &'a [Span]),
345 // `m::A::B` in `<T as m::A>::B::C`.
346 TraitItem(Namespace),
349 impl<'a> PathSource<'a> {
350 fn namespace(self) -> Namespace {
352 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
353 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
354 PathSource::TraitItem(ns) => ns,
358 fn defer_to_typeck(self) -> bool {
361 | PathSource::Expr(..)
364 | PathSource::TupleStruct(..) => true,
365 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
369 fn descr_expected(self) -> &'static str {
371 PathSource::Type => "type",
372 PathSource::Trait(_) => "trait",
373 PathSource::Pat => "unit struct, unit variant or constant",
374 PathSource::Struct => "struct, variant or union type",
375 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
376 PathSource::TraitItem(ns) => match ns {
377 TypeNS => "associated type",
378 ValueNS => "method or associated constant",
379 MacroNS => bug!("associated macro"),
381 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
382 // "function" here means "anything callable" rather than `DefKind::Fn`,
383 // this is not precise but usually more helpful than just "value".
384 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
385 // the case of `::some_crate()`
386 ExprKind::Path(_, path)
387 if path.segments.len() == 2
388 && path.segments[0].ident.name == kw::PathRoot =>
392 ExprKind::Path(_, path) => {
393 let mut msg = "function";
394 if let Some(segment) = path.segments.iter().last() {
395 if let Some(c) = segment.ident.to_string().chars().next() {
396 if c.is_uppercase() {
397 msg = "function, tuple struct or tuple variant";
410 fn is_call(self) -> bool {
411 matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
414 pub(crate) fn is_expected(self, res: Res) -> bool {
416 PathSource::Type => matches!(
423 | DefKind::TraitAlias
428 | DefKind::ForeignTy,
431 | Res::SelfTyParam { .. }
432 | Res::SelfTyAlias { .. }
434 PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
435 PathSource::Trait(AliasPossibility::Maybe) => {
436 matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
438 PathSource::Expr(..) => matches!(
441 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
446 | DefKind::AssocConst
447 | DefKind::ConstParam,
453 res.expected_in_unit_struct_pat()
454 || matches!(res, Res::Def(DefKind::Const | DefKind::AssocConst, _))
456 PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
457 PathSource::Struct => matches!(
466 ) | Res::SelfTyParam { .. }
467 | Res::SelfTyAlias { .. }
469 PathSource::TraitItem(ns) => match res {
470 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
471 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
477 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
478 use rustc_errors::error_code;
479 match (self, has_unexpected_resolution) {
480 (PathSource::Trait(_), true) => error_code!(E0404),
481 (PathSource::Trait(_), false) => error_code!(E0405),
482 (PathSource::Type, true) => error_code!(E0573),
483 (PathSource::Type, false) => error_code!(E0412),
484 (PathSource::Struct, true) => error_code!(E0574),
485 (PathSource::Struct, false) => error_code!(E0422),
486 (PathSource::Expr(..), true) => error_code!(E0423),
487 (PathSource::Expr(..), false) => error_code!(E0425),
488 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
489 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
490 (PathSource::TraitItem(..), true) => error_code!(E0575),
491 (PathSource::TraitItem(..), false) => error_code!(E0576),
497 struct DiagnosticMetadata<'ast> {
498 /// The current trait's associated items' ident, used for diagnostic suggestions.
499 current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
501 /// The current self type if inside an impl (used for better errors).
502 current_self_type: Option<Ty>,
504 /// The current self item if inside an ADT (used for better errors).
505 current_self_item: Option<NodeId>,
507 /// The current trait (used to suggest).
508 current_item: Option<&'ast Item>,
510 /// When processing generics and encountering a type not found, suggest introducing a type
512 currently_processing_generics: bool,
514 /// The current enclosing (non-closure) function (used for better errors).
515 current_function: Option<(FnKind<'ast>, Span)>,
517 /// A list of labels as of yet unused. Labels will be removed from this map when
518 /// they are used (in a `break` or `continue` statement)
519 unused_labels: FxHashMap<NodeId, Span>,
521 /// Only used for better errors on `fn(): fn()`.
522 current_type_ascription: Vec<Span>,
524 /// Only used for better errors on `let x = { foo: bar };`.
525 /// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only
526 /// needed for cases where this parses as a correct type ascription.
527 current_block_could_be_bare_struct_literal: Option<Span>,
529 /// Only used for better errors on `let <pat>: <expr, not type>;`.
530 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
532 /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
533 in_if_condition: Option<&'ast Expr>,
535 /// Used to detect possible new binding written without `let` and to provide structured suggestion.
536 in_assignment: Option<&'ast Expr>,
539 /// If we are currently in a trait object definition. Used to point at the bounds when
540 /// encountering a struct or enum.
541 current_trait_object: Option<&'ast [ast::GenericBound]>,
543 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
544 current_where_predicate: Option<&'ast WherePredicate>,
546 current_type_path: Option<&'ast Ty>,
548 /// The current impl items (used to suggest).
549 current_impl_items: Option<&'ast [P<AssocItem>]>,
551 /// When processing impl trait
552 currently_processing_impl_trait: Option<(TraitRef, Ty)>,
554 /// Accumulate the errors due to missed lifetime elision,
555 /// and report them all at once for each function.
556 current_elision_failures: Vec<MissingLifetime>,
559 struct LateResolutionVisitor<'a, 'b, 'ast> {
560 r: &'b mut Resolver<'a>,
562 /// The module that represents the current item scope.
563 parent_scope: ParentScope<'a>,
565 /// The current set of local scopes for types and values.
566 /// FIXME #4948: Reuse ribs to avoid allocation.
567 ribs: PerNS<Vec<Rib<'a>>>,
569 /// Previous poped `rib`, only used for diagnostic.
570 last_block_rib: Option<Rib<'a>>,
572 /// The current set of local scopes, for labels.
573 label_ribs: Vec<Rib<'a, NodeId>>,
575 /// The current set of local scopes for lifetimes.
576 lifetime_ribs: Vec<LifetimeRib>,
578 /// We are looking for lifetimes in an elision context.
579 /// The set contains all the resolutions that we encountered so far.
580 /// They will be used to determine the correct lifetime for the fn return type.
581 /// The `LifetimeElisionCandidate` is used for diagnostics, to suggest introducing named
583 lifetime_elision_candidates: Option<Vec<(LifetimeRes, LifetimeElisionCandidate)>>,
585 /// The trait that the current context can refer to.
586 current_trait_ref: Option<(Module<'a>, TraitRef)>,
588 /// Fields used to add information to diagnostic errors.
589 diagnostic_metadata: Box<DiagnosticMetadata<'ast>>,
591 /// State used to know whether to ignore resolution errors for function bodies.
593 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
594 /// In most cases this will be `None`, in which case errors will always be reported.
595 /// If it is `true`, then it will be updated when entering a nested function or trait body.
598 /// Count the number of places a lifetime is used.
599 lifetime_uses: FxHashMap<LocalDefId, LifetimeUseSet>,
602 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
603 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
604 fn visit_attribute(&mut self, _: &'ast Attribute) {
605 // We do not want to resolve expressions that appear in attributes,
606 // as they do not correspond to actual code.
608 fn visit_item(&mut self, item: &'ast Item) {
609 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
610 // Always report errors in items we just entered.
611 let old_ignore = replace(&mut self.in_func_body, false);
612 self.with_lifetime_rib(LifetimeRibKind::Item, |this| this.resolve_item(item));
613 self.in_func_body = old_ignore;
614 self.diagnostic_metadata.current_item = prev;
616 fn visit_arm(&mut self, arm: &'ast Arm) {
617 self.resolve_arm(arm);
619 fn visit_block(&mut self, block: &'ast Block) {
620 self.resolve_block(block);
622 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
623 // We deal with repeat expressions explicitly in `resolve_expr`.
624 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
625 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
626 this.resolve_anon_const(constant, IsRepeatExpr::No);
630 fn visit_expr(&mut self, expr: &'ast Expr) {
631 self.resolve_expr(expr, None);
633 fn visit_local(&mut self, local: &'ast Local) {
634 let local_spans = match local.pat.kind {
635 // We check for this to avoid tuple struct fields.
636 PatKind::Wild => None,
639 local.ty.as_ref().map(|ty| ty.span),
640 local.kind.init().map(|init| init.span),
643 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
644 self.resolve_local(local);
645 self.diagnostic_metadata.current_let_binding = original;
647 fn visit_ty(&mut self, ty: &'ast Ty) {
648 let prev = self.diagnostic_metadata.current_trait_object;
649 let prev_ty = self.diagnostic_metadata.current_type_path;
651 TyKind::Rptr(None, _) => {
652 // Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
654 // This span will be used in case of elision failure.
655 let span = self.r.session.source_map().start_point(ty.span);
656 self.resolve_elided_lifetime(ty.id, span);
657 visit::walk_ty(self, ty);
659 TyKind::Path(ref qself, ref path) => {
660 self.diagnostic_metadata.current_type_path = Some(ty);
661 self.smart_resolve_path(ty.id, &qself, path, PathSource::Type);
663 // Check whether we should interpret this as a bare trait object.
665 && let Some(partial_res) = self.r.partial_res_map.get(&ty.id)
666 && let Some(Res::Def(DefKind::Trait | DefKind::TraitAlias, _)) = partial_res.full_res()
668 // This path is actually a bare trait object. In case of a bare `Fn`-trait
669 // object with anonymous lifetimes, we need this rib to correctly place the
670 // synthetic lifetimes.
671 let span = ty.span.shrink_to_lo().to(path.span.shrink_to_lo());
672 self.with_generic_param_rib(
675 LifetimeRibKind::Generics {
677 kind: LifetimeBinderKind::PolyTrait,
680 |this| this.visit_path(&path, ty.id),
683 visit::walk_ty(self, ty)
686 TyKind::ImplicitSelf => {
687 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
689 .resolve_ident_in_lexical_scope(
692 Some(Finalize::new(ty.id, ty.span)),
695 .map_or(Res::Err, |d| d.res());
696 self.r.record_partial_res(ty.id, PartialRes::new(res));
697 visit::walk_ty(self, ty)
699 TyKind::ImplTrait(..) => {
700 let candidates = self.lifetime_elision_candidates.take();
701 visit::walk_ty(self, ty);
702 self.lifetime_elision_candidates = candidates;
704 TyKind::TraitObject(ref bounds, ..) => {
705 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
706 visit::walk_ty(self, ty)
708 TyKind::BareFn(ref bare_fn) => {
709 let span = ty.span.shrink_to_lo().to(bare_fn.decl_span.shrink_to_lo());
710 self.with_generic_param_rib(
711 &bare_fn.generic_params,
713 LifetimeRibKind::Generics {
715 kind: LifetimeBinderKind::BareFnType,
719 this.visit_generic_params(&bare_fn.generic_params, false);
720 this.with_lifetime_rib(
721 LifetimeRibKind::AnonymousCreateParameter {
723 report_in_path: false,
726 this.resolve_fn_signature(
729 // We don't need to deal with patterns in parameters, because
730 // they are not possible for foreign or bodiless functions.
735 .map(|Param { ty, .. }| (None, &**ty)),
736 &bare_fn.decl.output,
743 _ => visit::walk_ty(self, ty),
745 self.diagnostic_metadata.current_trait_object = prev;
746 self.diagnostic_metadata.current_type_path = prev_ty;
748 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef) {
749 let span = tref.span.shrink_to_lo().to(tref.trait_ref.path.span.shrink_to_lo());
750 self.with_generic_param_rib(
751 &tref.bound_generic_params,
753 LifetimeRibKind::Generics {
754 binder: tref.trait_ref.ref_id,
755 kind: LifetimeBinderKind::PolyTrait,
759 this.visit_generic_params(&tref.bound_generic_params, false);
760 this.smart_resolve_path(
761 tref.trait_ref.ref_id,
763 &tref.trait_ref.path,
764 PathSource::Trait(AliasPossibility::Maybe),
766 this.visit_trait_ref(&tref.trait_ref);
770 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
771 match foreign_item.kind {
772 ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
773 self.with_generic_param_rib(
775 ItemRibKind(HasGenericParams::Yes(generics.span)),
776 LifetimeRibKind::Generics {
777 binder: foreign_item.id,
778 kind: LifetimeBinderKind::Item,
781 |this| visit::walk_foreign_item(this, foreign_item),
784 ForeignItemKind::Fn(box Fn { ref generics, .. }) => {
785 self.with_generic_param_rib(
787 ItemRibKind(HasGenericParams::Yes(generics.span)),
788 LifetimeRibKind::Generics {
789 binder: foreign_item.id,
790 kind: LifetimeBinderKind::Function,
793 |this| visit::walk_foreign_item(this, foreign_item),
796 ForeignItemKind::Static(..) => {
797 self.with_static_rib(|this| {
798 visit::walk_foreign_item(this, foreign_item);
801 ForeignItemKind::MacCall(..) => {
802 panic!("unexpanded macro in resolve!")
806 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, fn_id: NodeId) {
807 let previous_value = self.diagnostic_metadata.current_function;
809 // Bail if the function is foreign, and thus cannot validly have
810 // a body, or if there's no body for some other reason.
811 FnKind::Fn(FnCtxt::Foreign, _, sig, _, generics, _)
812 | FnKind::Fn(_, _, sig, _, generics, None) => {
813 self.visit_fn_header(&sig.header);
814 self.visit_generics(generics);
815 self.with_lifetime_rib(
816 LifetimeRibKind::AnonymousCreateParameter {
818 report_in_path: false,
821 this.resolve_fn_signature(
824 sig.decl.inputs.iter().map(|Param { ty, .. }| (None, &**ty)),
828 this.record_lifetime_params_for_async(
830 sig.header.asyncness.opt_return_id(),
837 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
839 // Do not update `current_function` for closures: it suggests `self` parameters.
840 FnKind::Closure(..) => {}
842 debug!("(resolving function) entering function");
844 // Create a value rib for the function.
845 self.with_rib(ValueNS, ClosureOrAsyncRibKind, |this| {
846 // Create a label rib for the function.
847 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
849 FnKind::Fn(_, _, sig, _, generics, body) => {
850 this.visit_generics(generics);
852 let declaration = &sig.decl;
853 let async_node_id = sig.header.asyncness.opt_return_id();
855 this.with_lifetime_rib(
856 LifetimeRibKind::AnonymousCreateParameter {
858 report_in_path: async_node_id.is_some(),
861 this.resolve_fn_signature(
863 declaration.has_self(),
867 .map(|Param { pat, ty, .. }| (Some(&**pat), &**ty)),
873 this.record_lifetime_params_for_async(fn_id, async_node_id);
875 if let Some(body) = body {
876 // Ignore errors in function bodies if this is rustdoc
877 // Be sure not to set this until the function signature has been resolved.
878 let previous_state = replace(&mut this.in_func_body, true);
879 // We only care block in the same function
880 this.last_block_rib = None;
881 // Resolve the function body, potentially inside the body of an async closure
882 this.with_lifetime_rib(
883 LifetimeRibKind::Elided(LifetimeRes::Infer),
884 |this| this.visit_block(body),
887 debug!("(resolving function) leaving function");
888 this.in_func_body = previous_state;
891 FnKind::Closure(binder, declaration, body) => {
892 this.visit_closure_binder(binder);
894 this.with_lifetime_rib(
896 // We do not have any explicit generic lifetime parameter.
897 ClosureBinder::NotPresent => {
898 LifetimeRibKind::AnonymousCreateParameter {
900 report_in_path: false,
903 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
905 // Add each argument to the rib.
906 |this| this.resolve_params(&declaration.inputs),
908 this.with_lifetime_rib(
910 ClosureBinder::NotPresent => {
911 LifetimeRibKind::Elided(LifetimeRes::Infer)
913 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
915 |this| visit::walk_fn_ret_ty(this, &declaration.output),
918 // Ignore errors in function bodies if this is rustdoc
919 // Be sure not to set this until the function signature has been resolved.
920 let previous_state = replace(&mut this.in_func_body, true);
921 // Resolve the function body, potentially inside the body of an async closure
922 this.with_lifetime_rib(
923 LifetimeRibKind::Elided(LifetimeRes::Infer),
924 |this| this.visit_expr(body),
927 debug!("(resolving function) leaving function");
928 this.in_func_body = previous_state;
933 self.diagnostic_metadata.current_function = previous_value;
935 fn visit_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
936 self.resolve_lifetime(lifetime, use_ctxt)
939 fn visit_generics(&mut self, generics: &'ast Generics) {
940 self.visit_generic_params(
942 self.diagnostic_metadata.current_self_item.is_some(),
944 for p in &generics.where_clause.predicates {
945 self.visit_where_predicate(p);
949 fn visit_closure_binder(&mut self, b: &'ast ClosureBinder) {
951 ClosureBinder::NotPresent => {}
952 ClosureBinder::For { generic_params, .. } => {
953 self.visit_generic_params(
955 self.diagnostic_metadata.current_self_item.is_some(),
961 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
962 debug!("visit_generic_arg({:?})", arg);
963 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
965 GenericArg::Type(ref ty) => {
966 // We parse const arguments as path types as we cannot distinguish them during
967 // parsing. We try to resolve that ambiguity by attempting resolution the type
968 // namespace first, and if that fails we try again in the value namespace. If
969 // resolution in the value namespace succeeds, we have an generic const argument on
971 if let TyKind::Path(ref qself, ref path) = ty.kind {
972 // We cannot disambiguate multi-segment paths right now as that requires type
974 if path.segments.len() == 1 && path.segments[0].args.is_none() {
975 let mut check_ns = |ns| {
976 self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns)
979 if !check_ns(TypeNS) && check_ns(ValueNS) {
980 // This must be equivalent to `visit_anon_const`, but we cannot call it
981 // directly due to visitor lifetimes so we have to copy-paste some code.
983 // Note that we might not be inside of an repeat expression here,
984 // but considering that `IsRepeatExpr` is only relevant for
985 // non-trivial constants this is doesn't matter.
986 self.with_constant_rib(
988 ConstantHasGenerics::Yes,
991 this.smart_resolve_path(
995 PathSource::Expr(None),
998 if let Some(ref qself) = *qself {
999 this.visit_ty(&qself.ty);
1001 this.visit_path(path, ty.id);
1005 self.diagnostic_metadata.currently_processing_generics = prev;
1013 GenericArg::Lifetime(lt) => self.visit_lifetime(lt, visit::LifetimeCtxt::GenericArg),
1014 GenericArg::Const(ct) => self.visit_anon_const(ct),
1016 self.diagnostic_metadata.currently_processing_generics = prev;
1019 fn visit_assoc_constraint(&mut self, constraint: &'ast AssocConstraint) {
1020 self.visit_ident(constraint.ident);
1021 if let Some(ref gen_args) = constraint.gen_args {
1022 // Forbid anonymous lifetimes in GAT parameters until proper semantics are decided.
1023 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1024 this.visit_generic_args(gen_args)
1027 match constraint.kind {
1028 AssocConstraintKind::Equality { ref term } => match term {
1029 Term::Ty(ty) => self.visit_ty(ty),
1030 Term::Const(c) => self.visit_anon_const(c),
1032 AssocConstraintKind::Bound { ref bounds } => {
1033 walk_list!(self, visit_param_bound, bounds, BoundKind::Bound);
1038 fn visit_path_segment(&mut self, path_segment: &'ast PathSegment) {
1039 if let Some(ref args) = path_segment.args {
1041 GenericArgs::AngleBracketed(..) => visit::walk_generic_args(self, args),
1042 GenericArgs::Parenthesized(p_args) => {
1043 // Probe the lifetime ribs to know how to behave.
1044 for rib in self.lifetime_ribs.iter().rev() {
1046 // We are inside a `PolyTraitRef`. The lifetimes are
1047 // to be intoduced in that (maybe implicit) `for<>` binder.
1048 LifetimeRibKind::Generics {
1050 kind: LifetimeBinderKind::PolyTrait,
1053 self.with_lifetime_rib(
1054 LifetimeRibKind::AnonymousCreateParameter {
1056 report_in_path: false,
1059 this.resolve_fn_signature(
1062 p_args.inputs.iter().map(|ty| (None, &**ty)),
1069 // We have nowhere to introduce generics. Code is malformed,
1070 // so use regular lifetime resolution to avoid spurious errors.
1071 LifetimeRibKind::Item | LifetimeRibKind::Generics { .. } => {
1072 visit::walk_generic_args(self, args);
1075 LifetimeRibKind::AnonymousCreateParameter { .. }
1076 | LifetimeRibKind::AnonymousReportError
1077 | LifetimeRibKind::Elided(_)
1078 | LifetimeRibKind::ElisionFailure
1079 | LifetimeRibKind::AnonConst
1080 | LifetimeRibKind::ConstGeneric => {}
1088 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
1089 debug!("visit_where_predicate {:?}", p);
1090 let previous_value =
1091 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
1092 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1093 if let WherePredicate::BoundPredicate(WhereBoundPredicate {
1096 ref bound_generic_params,
1097 span: predicate_span,
1101 let span = predicate_span.shrink_to_lo().to(bounded_ty.span.shrink_to_lo());
1102 this.with_generic_param_rib(
1103 &bound_generic_params,
1105 LifetimeRibKind::Generics {
1106 binder: bounded_ty.id,
1107 kind: LifetimeBinderKind::WhereBound,
1111 this.visit_generic_params(&bound_generic_params, false);
1112 this.visit_ty(bounded_ty);
1113 for bound in bounds {
1114 this.visit_param_bound(bound, BoundKind::Bound)
1119 visit::walk_where_predicate(this, p);
1122 self.diagnostic_metadata.current_where_predicate = previous_value;
1125 fn visit_inline_asm(&mut self, asm: &'ast InlineAsm) {
1126 for (op, _) in &asm.operands {
1128 InlineAsmOperand::In { expr, .. }
1129 | InlineAsmOperand::Out { expr: Some(expr), .. }
1130 | InlineAsmOperand::InOut { expr, .. } => self.visit_expr(expr),
1131 InlineAsmOperand::Out { expr: None, .. } => {}
1132 InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
1133 self.visit_expr(in_expr);
1134 if let Some(out_expr) = out_expr {
1135 self.visit_expr(out_expr);
1138 InlineAsmOperand::Const { anon_const, .. } => {
1139 // Although this is `DefKind::AnonConst`, it is allowed to reference outer
1140 // generic parameters like an inline const.
1141 self.resolve_inline_const(anon_const);
1143 InlineAsmOperand::Sym { sym } => self.visit_inline_asm_sym(sym),
1148 fn visit_inline_asm_sym(&mut self, sym: &'ast InlineAsmSym) {
1149 // This is similar to the code for AnonConst.
1150 self.with_rib(ValueNS, InlineAsmSymRibKind, |this| {
1151 this.with_rib(TypeNS, InlineAsmSymRibKind, |this| {
1152 this.with_label_rib(InlineAsmSymRibKind, |this| {
1153 this.smart_resolve_path(sym.id, &sym.qself, &sym.path, PathSource::Expr(None));
1154 visit::walk_inline_asm_sym(this, sym);
1161 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
1162 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
1163 // During late resolution we only track the module component of the parent scope,
1164 // although it may be useful to track other components as well for diagnostics.
1165 let graph_root = resolver.graph_root;
1166 let parent_scope = ParentScope::module(graph_root, resolver);
1167 let start_rib_kind = ModuleRibKind(graph_root);
1168 LateResolutionVisitor {
1172 value_ns: vec![Rib::new(start_rib_kind)],
1173 type_ns: vec![Rib::new(start_rib_kind)],
1174 macro_ns: vec![Rib::new(start_rib_kind)],
1176 last_block_rib: None,
1177 label_ribs: Vec::new(),
1178 lifetime_ribs: Vec::new(),
1179 lifetime_elision_candidates: None,
1180 current_trait_ref: None,
1181 diagnostic_metadata: Box::new(DiagnosticMetadata::default()),
1182 // errors at module scope should always be reported
1183 in_func_body: false,
1184 lifetime_uses: Default::default(),
1188 fn maybe_resolve_ident_in_lexical_scope(
1192 ) -> Option<LexicalScopeBinding<'a>> {
1193 self.r.resolve_ident_in_lexical_scope(
1203 fn resolve_ident_in_lexical_scope(
1207 finalize: Option<Finalize>,
1208 ignore_binding: Option<&'a NameBinding<'a>>,
1209 ) -> Option<LexicalScopeBinding<'a>> {
1210 self.r.resolve_ident_in_lexical_scope(
1223 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1224 finalize: Option<Finalize>,
1225 ) -> PathResult<'a> {
1226 self.r.resolve_path_with_ribs(
1238 // We maintain a list of value ribs and type ribs.
1240 // Simultaneously, we keep track of the current position in the module
1241 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
1242 // the value or type namespaces, we first look through all the ribs and
1243 // then query the module graph. When we resolve a name in the module
1244 // namespace, we can skip all the ribs (since nested modules are not
1245 // allowed within blocks in Rust) and jump straight to the current module
1248 // Named implementations are handled separately. When we find a method
1249 // call, we consult the module node to find all of the implementations in
1250 // scope. This information is lazily cached in the module node. We then
1251 // generate a fake "implementation scope" containing all the
1252 // implementations thus found, for compatibility with old resolve pass.
1254 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
1259 work: impl FnOnce(&mut Self) -> T,
1261 self.ribs[ns].push(Rib::new(kind));
1262 let ret = work(self);
1263 self.ribs[ns].pop();
1267 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
1268 if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
1269 // Move down in the graph.
1270 let orig_module = replace(&mut self.parent_scope.module, module);
1271 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
1272 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
1274 this.parent_scope.module = orig_module;
1283 fn visit_generic_params(&mut self, params: &'ast [GenericParam], add_self_upper: bool) {
1284 // For type parameter defaults, we have to ban access
1285 // to following type parameters, as the InternalSubsts can only
1286 // provide previous type parameters as they're built. We
1287 // put all the parameters on the ban list and then remove
1288 // them one by one as they are processed and become available.
1289 let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1290 let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1291 for param in params.iter() {
1293 GenericParamKind::Type { .. } => {
1296 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1298 GenericParamKind::Const { .. } => {
1299 forward_const_ban_rib
1301 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1303 GenericParamKind::Lifetime => {}
1307 // rust-lang/rust#61631: The type `Self` is essentially
1308 // another type parameter. For ADTs, we consider it
1309 // well-defined only after all of the ADT type parameters have
1310 // been provided. Therefore, we do not allow use of `Self`
1311 // anywhere in ADT type parameter defaults.
1313 // (We however cannot ban `Self` for defaults on *all* generic
1314 // lists; e.g. trait generics can usefully refer to `Self`,
1315 // such as in the case of `trait Add<Rhs = Self>`.)
1317 // (`Some` if + only if we are in ADT's generics.)
1318 forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
1321 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1322 for param in params {
1324 GenericParamKind::Lifetime => {
1325 for bound in ¶m.bounds {
1326 this.visit_param_bound(bound, BoundKind::Bound);
1329 GenericParamKind::Type { ref default } => {
1330 for bound in ¶m.bounds {
1331 this.visit_param_bound(bound, BoundKind::Bound);
1334 if let Some(ref ty) = default {
1335 this.ribs[TypeNS].push(forward_ty_ban_rib);
1336 this.ribs[ValueNS].push(forward_const_ban_rib);
1338 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1339 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1342 // Allow all following defaults to refer to this type parameter.
1345 .remove(&Ident::with_dummy_span(param.ident.name));
1347 GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
1348 // Const parameters can't have param bounds.
1349 assert!(param.bounds.is_empty());
1351 this.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
1352 this.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
1353 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1356 this.ribs[TypeNS].pop().unwrap();
1357 this.ribs[ValueNS].pop().unwrap();
1359 if let Some(ref expr) = default {
1360 this.ribs[TypeNS].push(forward_ty_ban_rib);
1361 this.ribs[ValueNS].push(forward_const_ban_rib);
1362 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1363 this.resolve_anon_const(expr, IsRepeatExpr::No)
1365 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1366 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1369 // Allow all following defaults to refer to this const parameter.
1370 forward_const_ban_rib
1372 .remove(&Ident::with_dummy_span(param.ident.name));
1379 #[instrument(level = "debug", skip(self, work))]
1380 fn with_lifetime_rib<T>(
1382 kind: LifetimeRibKind,
1383 work: impl FnOnce(&mut Self) -> T,
1385 self.lifetime_ribs.push(LifetimeRib::new(kind));
1386 let outer_elision_candidates = self.lifetime_elision_candidates.take();
1387 let ret = work(self);
1388 self.lifetime_elision_candidates = outer_elision_candidates;
1389 self.lifetime_ribs.pop();
1393 #[instrument(level = "debug", skip(self))]
1394 fn resolve_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
1395 let ident = lifetime.ident;
1397 if ident.name == kw::StaticLifetime {
1398 self.record_lifetime_res(
1400 LifetimeRes::Static,
1401 LifetimeElisionCandidate::Named,
1406 if ident.name == kw::UnderscoreLifetime {
1407 return self.resolve_anonymous_lifetime(lifetime, false);
1410 let mut lifetime_rib_iter = self.lifetime_ribs.iter().rev();
1411 while let Some(rib) = lifetime_rib_iter.next() {
1412 let normalized_ident = ident.normalize_to_macros_2_0();
1413 if let Some(&(_, res)) = rib.bindings.get(&normalized_ident) {
1414 self.record_lifetime_res(lifetime.id, res, LifetimeElisionCandidate::Named);
1416 if let LifetimeRes::Param { param, .. } = res {
1417 match self.lifetime_uses.entry(param) {
1418 Entry::Vacant(v) => {
1419 debug!("First use of {:?} at {:?}", res, ident.span);
1424 .find_map(|rib| match rib.kind {
1425 // Do not suggest eliding a lifetime where an anonymous
1426 // lifetime would be illegal.
1427 LifetimeRibKind::Item
1428 | LifetimeRibKind::AnonymousReportError
1429 | LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many),
1430 // An anonymous lifetime is legal here, go ahead.
1431 LifetimeRibKind::AnonymousCreateParameter { .. } => {
1432 Some(LifetimeUseSet::One { use_span: ident.span, use_ctxt })
1434 // Only report if eliding the lifetime would have the same
1436 LifetimeRibKind::Elided(r) => Some(if res == r {
1437 LifetimeUseSet::One { use_span: ident.span, use_ctxt }
1439 LifetimeUseSet::Many
1441 LifetimeRibKind::Generics { .. } => None,
1442 LifetimeRibKind::ConstGeneric | LifetimeRibKind::AnonConst => {
1443 span_bug!(ident.span, "unexpected rib kind: {:?}", rib.kind)
1446 .unwrap_or(LifetimeUseSet::Many);
1447 debug!(?use_ctxt, ?use_set);
1450 Entry::Occupied(mut o) => {
1451 debug!("Many uses of {:?} at {:?}", res, ident.span);
1452 *o.get_mut() = LifetimeUseSet::Many;
1460 LifetimeRibKind::Item => break,
1461 LifetimeRibKind::ConstGeneric => {
1462 self.emit_non_static_lt_in_const_generic_error(lifetime);
1463 self.record_lifetime_res(
1466 LifetimeElisionCandidate::Ignore,
1470 LifetimeRibKind::AnonConst => {
1471 self.maybe_emit_forbidden_non_static_lifetime_error(lifetime);
1472 self.record_lifetime_res(
1475 LifetimeElisionCandidate::Ignore,
1479 LifetimeRibKind::AnonymousCreateParameter { .. }
1480 | LifetimeRibKind::Elided(_)
1481 | LifetimeRibKind::Generics { .. }
1482 | LifetimeRibKind::ElisionFailure
1483 | LifetimeRibKind::AnonymousReportError => {}
1487 let mut outer_res = None;
1488 for rib in lifetime_rib_iter {
1489 let normalized_ident = ident.normalize_to_macros_2_0();
1490 if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) {
1491 outer_res = Some(outer);
1496 self.emit_undeclared_lifetime_error(lifetime, outer_res);
1497 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, LifetimeElisionCandidate::Named);
1500 #[instrument(level = "debug", skip(self))]
1501 fn resolve_anonymous_lifetime(&mut self, lifetime: &Lifetime, elided: bool) {
1502 debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
1504 let missing_lifetime = MissingLifetime {
1506 span: lifetime.ident.span,
1508 MissingLifetimeKind::Ampersand
1510 MissingLifetimeKind::Underscore
1514 let elision_candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1515 for rib in self.lifetime_ribs.iter().rev() {
1518 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1519 let res = self.create_fresh_lifetime(lifetime.id, lifetime.ident, binder);
1520 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1523 LifetimeRibKind::AnonymousReportError => {
1524 let (msg, note) = if elided {
1526 "`&` without an explicit lifetime name cannot be used here",
1527 "explicit lifetime name needed here",
1530 ("`'_` cannot be used here", "`'_` is a reserved lifetime name")
1532 rustc_errors::struct_span_err!(
1534 lifetime.ident.span,
1539 .span_label(lifetime.ident.span, note)
1542 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1545 LifetimeRibKind::Elided(res) => {
1546 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1549 LifetimeRibKind::ElisionFailure => {
1550 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1551 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1554 LifetimeRibKind::Item => break,
1555 LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstGeneric => {}
1556 LifetimeRibKind::AnonConst => {
1557 // There is always an `Elided(LifetimeRes::Static)` inside an `AnonConst`.
1558 span_bug!(lifetime.ident.span, "unexpected rib kind: {:?}", rib.kind)
1562 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1563 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1566 #[instrument(level = "debug", skip(self))]
1567 fn resolve_elided_lifetime(&mut self, anchor_id: NodeId, span: Span) {
1568 let id = self.r.next_node_id();
1569 let lt = Lifetime { id, ident: Ident::new(kw::UnderscoreLifetime, span) };
1571 self.record_lifetime_res(
1573 LifetimeRes::ElidedAnchor { start: id, end: NodeId::from_u32(id.as_u32() + 1) },
1574 LifetimeElisionCandidate::Ignore,
1576 self.resolve_anonymous_lifetime(<, true);
1579 #[instrument(level = "debug", skip(self))]
1580 fn create_fresh_lifetime(&mut self, id: NodeId, ident: Ident, binder: NodeId) -> LifetimeRes {
1581 debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
1582 debug!(?ident.span);
1584 // Leave the responsibility to create the `LocalDefId` to lowering.
1585 let param = self.r.next_node_id();
1586 let res = LifetimeRes::Fresh { param, binder };
1588 // Record the created lifetime parameter so lowering can pick it up and add it to HIR.
1590 .extra_lifetime_params_map
1592 .or_insert_with(Vec::new)
1593 .push((ident, param, res));
1597 #[instrument(level = "debug", skip(self))]
1598 fn resolve_elided_lifetimes_in_path(
1601 partial_res: PartialRes,
1603 source: PathSource<'_>,
1606 let proj_start = path.len() - partial_res.unresolved_segments();
1607 for (i, segment) in path.iter().enumerate() {
1608 if segment.has_lifetime_args {
1611 let Some(segment_id) = segment.id else {
1615 // Figure out if this is a type/trait segment,
1616 // which may need lifetime elision performed.
1617 let type_def_id = match partial_res.base_res() {
1618 Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => self.r.parent(def_id),
1619 Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => self.r.parent(def_id),
1620 Res::Def(DefKind::Struct, def_id)
1621 | Res::Def(DefKind::Union, def_id)
1622 | Res::Def(DefKind::Enum, def_id)
1623 | Res::Def(DefKind::TyAlias, def_id)
1624 | Res::Def(DefKind::Trait, def_id)
1625 if i + 1 == proj_start =>
1632 let expected_lifetimes = self.r.item_generics_num_lifetimes(type_def_id);
1633 if expected_lifetimes == 0 {
1637 let node_ids = self.r.next_node_ids(expected_lifetimes);
1638 self.record_lifetime_res(
1640 LifetimeRes::ElidedAnchor { start: node_ids.start, end: node_ids.end },
1641 LifetimeElisionCandidate::Ignore,
1644 let inferred = match source {
1645 PathSource::Trait(..) | PathSource::TraitItem(..) | PathSource::Type => false,
1646 PathSource::Expr(..)
1648 | PathSource::Struct
1649 | PathSource::TupleStruct(..) => true,
1652 // Do not create a parameter for patterns and expressions: type checking can infer
1653 // the appropriate lifetime for us.
1654 for id in node_ids {
1655 self.record_lifetime_res(
1658 LifetimeElisionCandidate::Named,
1664 let elided_lifetime_span = if segment.has_generic_args {
1665 // If there are brackets, but not generic arguments, then use the opening bracket
1666 segment.args_span.with_hi(segment.args_span.lo() + BytePos(1))
1668 // If there are no brackets, use the identifier span.
1669 // HACK: we use find_ancestor_inside to properly suggest elided spans in paths
1670 // originating from macros, since the segment's span might be from a macro arg.
1671 segment.ident.span.find_ancestor_inside(path_span).unwrap_or(path_span)
1673 let ident = Ident::new(kw::UnderscoreLifetime, elided_lifetime_span);
1675 let missing_lifetime = MissingLifetime {
1677 span: elided_lifetime_span,
1678 kind: if segment.has_generic_args {
1679 MissingLifetimeKind::Comma
1681 MissingLifetimeKind::Brackets
1683 count: expected_lifetimes,
1685 let mut should_lint = true;
1686 for rib in self.lifetime_ribs.iter().rev() {
1688 // In create-parameter mode we error here because we don't want to support
1689 // deprecated impl elision in new features like impl elision and `async fn`,
1690 // both of which work using the `CreateParameter` mode:
1692 // impl Foo for std::cell::Ref<u32> // note lack of '_
1693 // async fn foo(_: std::cell::Ref<u32>) { ... }
1694 LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. } => {
1695 let sess = self.r.session;
1696 let mut err = rustc_errors::struct_span_err!(
1700 "implicit elided lifetime not allowed here"
1702 rustc_errors::add_elided_lifetime_in_path_suggestion(
1707 !segment.has_generic_args,
1708 elided_lifetime_span,
1710 err.note("assuming a `'static` lifetime...");
1712 should_lint = false;
1714 for id in node_ids {
1715 self.record_lifetime_res(
1718 LifetimeElisionCandidate::Named,
1723 // Do not create a parameter for patterns and expressions.
1724 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1725 // Group all suggestions into the first record.
1726 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1727 for id in node_ids {
1728 let res = self.create_fresh_lifetime(id, ident, binder);
1729 self.record_lifetime_res(
1732 replace(&mut candidate, LifetimeElisionCandidate::Named),
1737 LifetimeRibKind::Elided(res) => {
1738 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1739 for id in node_ids {
1740 self.record_lifetime_res(
1743 replace(&mut candidate, LifetimeElisionCandidate::Ignore),
1748 LifetimeRibKind::ElisionFailure => {
1749 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1750 for id in node_ids {
1751 self.record_lifetime_res(
1754 LifetimeElisionCandidate::Ignore,
1759 // `LifetimeRes::Error`, which would usually be used in the case of
1760 // `ReportError`, is unsuitable here, as we don't emit an error yet. Instead,
1761 // we simply resolve to an implicit lifetime, which will be checked later, at
1762 // which point a suitable error will be emitted.
1763 LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
1764 for id in node_ids {
1765 self.record_lifetime_res(
1768 LifetimeElisionCandidate::Ignore,
1771 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1774 LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstGeneric => {}
1775 LifetimeRibKind::AnonConst => {
1776 // There is always an `Elided(LifetimeRes::Static)` inside an `AnonConst`.
1777 span_bug!(elided_lifetime_span, "unexpected rib kind: {:?}", rib.kind)
1783 self.r.lint_buffer.buffer_lint_with_diagnostic(
1784 lint::builtin::ELIDED_LIFETIMES_IN_PATHS,
1786 elided_lifetime_span,
1787 "hidden lifetime parameters in types are deprecated",
1788 lint::BuiltinLintDiagnostics::ElidedLifetimesInPaths(
1791 !segment.has_generic_args,
1792 elided_lifetime_span,
1799 #[instrument(level = "debug", skip(self))]
1800 fn record_lifetime_res(
1804 candidate: LifetimeElisionCandidate,
1806 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1808 "lifetime {:?} resolved multiple times ({:?} before, {:?} now)",
1813 LifetimeRes::Param { .. } | LifetimeRes::Fresh { .. } | LifetimeRes::Static => {
1814 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
1815 candidates.push((res, candidate));
1818 LifetimeRes::Infer | LifetimeRes::Error | LifetimeRes::ElidedAnchor { .. } => {}
1822 #[instrument(level = "debug", skip(self))]
1823 fn record_lifetime_param(&mut self, id: NodeId, res: LifetimeRes) {
1824 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1826 "lifetime parameter {:?} resolved multiple times ({:?} before, {:?} now)",
1832 /// Perform resolution of a function signature, accounting for lifetime elision.
1833 #[instrument(level = "debug", skip(self, inputs))]
1834 fn resolve_fn_signature(
1838 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)> + Clone,
1839 output_ty: &'ast FnRetTy,
1841 // Add each argument to the rib.
1842 let elision_lifetime = self.resolve_fn_params(has_self, inputs);
1843 debug!(?elision_lifetime);
1845 let outer_failures = take(&mut self.diagnostic_metadata.current_elision_failures);
1846 let output_rib = if let Ok(res) = elision_lifetime.as_ref() {
1847 self.r.lifetime_elision_allowed.insert(fn_id);
1848 LifetimeRibKind::Elided(*res)
1850 LifetimeRibKind::ElisionFailure
1852 self.with_lifetime_rib(output_rib, |this| visit::walk_fn_ret_ty(this, &output_ty));
1853 let elision_failures =
1854 replace(&mut self.diagnostic_metadata.current_elision_failures, outer_failures);
1855 if !elision_failures.is_empty() {
1856 let Err(failure_info) = elision_lifetime else { bug!() };
1857 self.report_missing_lifetime_specifiers(elision_failures, Some(failure_info));
1861 /// Resolve inside function parameters and parameter types.
1862 /// Returns the lifetime for elision in fn return type,
1863 /// or diagnostic information in case of elision failure.
1864 fn resolve_fn_params(
1867 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)>,
1868 ) -> Result<LifetimeRes, (Vec<MissingLifetime>, Vec<ElisionFnParameter>)> {
1870 /// We have not found any candidate.
1872 /// We have a candidate bound to `self`.
1874 /// We have a candidate bound to a parameter.
1876 /// We failed elision.
1880 // Save elision state to reinstate it later.
1881 let outer_candidates = self.lifetime_elision_candidates.take();
1883 // Result of elision.
1884 let mut elision_lifetime = Elision::None;
1885 // Information for diagnostics.
1886 let mut parameter_info = Vec::new();
1887 let mut all_candidates = Vec::new();
1889 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1890 for (index, (pat, ty)) in inputs.enumerate() {
1892 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
1893 if let Some(pat) = pat {
1894 this.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1898 // Record elision candidates only for this parameter.
1899 debug_assert_matches!(self.lifetime_elision_candidates, None);
1900 self.lifetime_elision_candidates = Some(Default::default());
1902 let local_candidates = self.lifetime_elision_candidates.take();
1904 if let Some(candidates) = local_candidates {
1905 let distinct: FxHashSet<_> = candidates.iter().map(|(res, _)| *res).collect();
1906 let lifetime_count = distinct.len();
1907 if lifetime_count != 0 {
1908 parameter_info.push(ElisionFnParameter {
1910 ident: if let Some(pat) = pat && let PatKind::Ident(_, ident, _) = pat.kind {
1918 all_candidates.extend(candidates.into_iter().filter_map(|(_, candidate)| {
1920 LifetimeElisionCandidate::Ignore | LifetimeElisionCandidate::Named => {
1923 LifetimeElisionCandidate::Missing(missing) => Some(missing),
1927 let mut distinct_iter = distinct.into_iter();
1928 if let Some(res) = distinct_iter.next() {
1929 match elision_lifetime {
1930 // We are the first parameter to bind lifetimes.
1932 if distinct_iter.next().is_none() {
1933 // We have a single lifetime => success.
1934 elision_lifetime = Elision::Param(res)
1936 // We have multiple lifetimes => error.
1937 elision_lifetime = Elision::Err;
1940 // We have 2 parameters that bind lifetimes => error.
1941 Elision::Param(_) => elision_lifetime = Elision::Err,
1942 // `self` elision takes precedence over everything else.
1943 Elision::Self_(_) | Elision::Err => {}
1948 // Handle `self` specially.
1949 if index == 0 && has_self {
1950 let self_lifetime = self.find_lifetime_for_self(ty);
1951 if let Set1::One(lifetime) = self_lifetime {
1952 // We found `self` elision.
1953 elision_lifetime = Elision::Self_(lifetime);
1955 // We do not have `self` elision: disregard the `Elision::Param` that we may
1957 elision_lifetime = Elision::None;
1960 debug!("(resolving function / closure) recorded parameter");
1963 // Reinstate elision state.
1964 debug_assert_matches!(self.lifetime_elision_candidates, None);
1965 self.lifetime_elision_candidates = outer_candidates;
1967 if let Elision::Param(res) | Elision::Self_(res) = elision_lifetime {
1971 // We do not have a candidate.
1972 Err((all_candidates, parameter_info))
1975 /// List all the lifetimes that appear in the provided type.
1976 fn find_lifetime_for_self(&self, ty: &'ast Ty) -> Set1<LifetimeRes> {
1977 struct SelfVisitor<'r, 'a> {
1978 r: &'r Resolver<'a>,
1979 impl_self: Option<Res>,
1980 lifetime: Set1<LifetimeRes>,
1983 impl SelfVisitor<'_, '_> {
1984 // Look for `self: &'a Self` - also desugared from `&'a self`,
1985 // and if that matches, use it for elision and return early.
1986 fn is_self_ty(&self, ty: &Ty) -> bool {
1988 TyKind::ImplicitSelf => true,
1989 TyKind::Path(None, _) => {
1990 let path_res = self.r.partial_res_map[&ty.id].full_res();
1991 if let Some(Res::SelfTyParam { .. } | Res::SelfTyAlias { .. }) = path_res {
1994 self.impl_self.is_some() && path_res == self.impl_self
2001 impl<'a> Visitor<'a> for SelfVisitor<'_, '_> {
2002 fn visit_ty(&mut self, ty: &'a Ty) {
2003 trace!("SelfVisitor considering ty={:?}", ty);
2004 if let TyKind::Rptr(lt, ref mt) = ty.kind && self.is_self_ty(&mt.ty) {
2005 let lt_id = if let Some(lt) = lt {
2008 let res = self.r.lifetimes_res_map[&ty.id];
2009 let LifetimeRes::ElidedAnchor { start, .. } = res else { bug!() };
2012 let lt_res = self.r.lifetimes_res_map[<_id];
2013 trace!("SelfVisitor inserting res={:?}", lt_res);
2014 self.lifetime.insert(lt_res);
2016 visit::walk_ty(self, ty)
2020 let impl_self = self
2021 .diagnostic_metadata
2025 if let TyKind::Path(None, _) = ty.kind {
2026 self.r.partial_res_map.get(&ty.id)
2031 .and_then(|res| res.full_res())
2033 // Permit the types that unambiguously always
2034 // result in the same type constructor being used
2035 // (it can't differ between `Self` and `self`).
2038 Res::Def(DefKind::Struct | DefKind::Union | DefKind::Enum, _,) | Res::PrimTy(_)
2041 let mut visitor = SelfVisitor { r: self.r, impl_self, lifetime: Set1::Empty };
2042 visitor.visit_ty(ty);
2043 trace!("SelfVisitor found={:?}", visitor.lifetime);
2047 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
2048 /// label and reports an error if the label is not found or is unreachable.
2049 fn resolve_label(&mut self, mut label: Ident) -> Result<(NodeId, Span), ResolutionError<'a>> {
2050 let mut suggestion = None;
2052 for i in (0..self.label_ribs.len()).rev() {
2053 let rib = &self.label_ribs[i];
2055 if let MacroDefinition(def) = rib.kind {
2056 // If an invocation of this macro created `ident`, give up on `ident`
2057 // and switch to `ident`'s source from the macro definition.
2058 if def == self.r.macro_def(label.span.ctxt()) {
2059 label.span.remove_mark();
2063 let ident = label.normalize_to_macro_rules();
2064 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
2065 let definition_span = ident.span;
2066 return if self.is_label_valid_from_rib(i) {
2067 Ok((*id, definition_span))
2069 Err(ResolutionError::UnreachableLabel {
2077 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
2078 // the first such label that is encountered.
2079 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
2082 Err(ResolutionError::UndeclaredLabel { name: label.name, suggestion })
2085 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
2086 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
2087 let ribs = &self.label_ribs[rib_index + 1..];
2090 if rib.kind.is_label_barrier() {
2098 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
2099 debug!("resolve_adt");
2100 self.with_current_self_item(item, |this| {
2101 this.with_generic_param_rib(
2103 ItemRibKind(HasGenericParams::Yes(generics.span)),
2104 LifetimeRibKind::Generics {
2106 kind: LifetimeBinderKind::Item,
2107 span: generics.span,
2110 let item_def_id = this.r.local_def_id(item.id).to_def_id();
2113 alias_to: item_def_id,
2114 forbid_generic: false,
2115 is_trait_impl: false,
2118 visit::walk_item(this, item);
2126 fn future_proof_import(&mut self, use_tree: &UseTree) {
2127 let segments = &use_tree.prefix.segments;
2128 if !segments.is_empty() {
2129 let ident = segments[0].ident;
2130 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
2134 let nss = match use_tree.kind {
2135 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
2138 let report_error = |this: &Self, ns| {
2139 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
2140 if this.should_report_errs() {
2143 .span_err(ident.span, &format!("imports cannot refer to {}", what));
2148 match self.maybe_resolve_ident_in_lexical_scope(ident, ns) {
2149 Some(LexicalScopeBinding::Res(..)) => {
2150 report_error(self, ns);
2152 Some(LexicalScopeBinding::Item(binding)) => {
2153 if let Some(LexicalScopeBinding::Res(..)) =
2154 self.resolve_ident_in_lexical_scope(ident, ns, None, Some(binding))
2156 report_error(self, ns);
2162 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
2163 for (use_tree, _) in use_trees {
2164 self.future_proof_import(use_tree);
2169 fn resolve_item(&mut self, item: &'ast Item) {
2170 let name = item.ident.name;
2171 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
2174 ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
2175 self.with_generic_param_rib(
2177 ItemRibKind(HasGenericParams::Yes(generics.span)),
2178 LifetimeRibKind::Generics {
2180 kind: LifetimeBinderKind::Item,
2181 span: generics.span,
2183 |this| visit::walk_item(this, item),
2187 ItemKind::Fn(box Fn { ref generics, .. }) => {
2188 self.with_generic_param_rib(
2190 ItemRibKind(HasGenericParams::Yes(generics.span)),
2191 LifetimeRibKind::Generics {
2193 kind: LifetimeBinderKind::Function,
2194 span: generics.span,
2196 |this| visit::walk_item(this, item),
2200 ItemKind::Enum(_, ref generics)
2201 | ItemKind::Struct(_, ref generics)
2202 | ItemKind::Union(_, ref generics) => {
2203 self.resolve_adt(item, generics);
2206 ItemKind::Impl(box Impl {
2210 items: ref impl_items,
2213 self.diagnostic_metadata.current_impl_items = Some(impl_items);
2214 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
2215 self.diagnostic_metadata.current_impl_items = None;
2218 ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
2219 // Create a new rib for the trait-wide type parameters.
2220 self.with_generic_param_rib(
2222 ItemRibKind(HasGenericParams::Yes(generics.span)),
2223 LifetimeRibKind::Generics {
2225 kind: LifetimeBinderKind::Item,
2226 span: generics.span,
2229 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2230 this.with_self_rib(Res::SelfTyParam { trait_: local_def_id }, |this| {
2231 this.visit_generics(generics);
2232 walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);
2233 this.resolve_trait_items(items);
2239 ItemKind::TraitAlias(ref generics, ref bounds) => {
2240 // Create a new rib for the trait-wide type parameters.
2241 self.with_generic_param_rib(
2243 ItemRibKind(HasGenericParams::Yes(generics.span)),
2244 LifetimeRibKind::Generics {
2246 kind: LifetimeBinderKind::Item,
2247 span: generics.span,
2250 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2251 this.with_self_rib(Res::SelfTyParam { trait_: local_def_id }, |this| {
2252 this.visit_generics(generics);
2253 walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
2259 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
2260 self.with_scope(item.id, |this| {
2261 visit::walk_item(this, item);
2265 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
2266 self.with_static_rib(|this| {
2267 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
2270 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2271 if let Some(expr) = expr {
2272 let constant_item_kind = match item.kind {
2273 ItemKind::Const(..) => ConstantItemKind::Const,
2274 ItemKind::Static(..) => ConstantItemKind::Static,
2275 _ => unreachable!(),
2277 // We already forbid generic params because of the above item rib,
2278 // so it doesn't matter whether this is a trivial constant.
2279 this.with_constant_rib(
2281 ConstantHasGenerics::Yes,
2282 Some((item.ident, constant_item_kind)),
2283 |this| this.visit_expr(expr),
2290 ItemKind::Use(ref use_tree) => {
2291 self.future_proof_import(use_tree);
2294 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => {
2295 // do nothing, these are just around to be encoded
2298 ItemKind::GlobalAsm(_) => {
2299 visit::walk_item(self, item);
2302 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
2306 fn with_generic_param_rib<'c, F>(
2308 params: &'c [GenericParam],
2310 lifetime_kind: LifetimeRibKind,
2313 F: FnOnce(&mut Self),
2315 debug!("with_generic_param_rib");
2316 let LifetimeRibKind::Generics { binder, span: generics_span, kind: generics_kind, .. }
2317 = lifetime_kind else { panic!() };
2319 let mut function_type_rib = Rib::new(kind);
2320 let mut function_value_rib = Rib::new(kind);
2321 let mut function_lifetime_rib = LifetimeRib::new(lifetime_kind);
2322 let mut seen_bindings = FxHashMap::default();
2323 // Store all seen lifetimes names from outer scopes.
2324 let mut seen_lifetimes = FxHashSet::default();
2326 // We also can't shadow bindings from the parent item
2327 if let AssocItemRibKind = kind {
2328 let mut add_bindings_for_ns = |ns| {
2329 let parent_rib = self.ribs[ns]
2331 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
2332 .expect("associated item outside of an item");
2334 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
2336 add_bindings_for_ns(ValueNS);
2337 add_bindings_for_ns(TypeNS);
2340 // Forbid shadowing lifetime bindings
2341 for rib in self.lifetime_ribs.iter().rev() {
2342 seen_lifetimes.extend(rib.bindings.iter().map(|(ident, _)| *ident));
2343 if let LifetimeRibKind::Item = rib.kind {
2348 for param in params {
2349 let ident = param.ident.normalize_to_macros_2_0();
2350 debug!("with_generic_param_rib: {}", param.id);
2352 if let GenericParamKind::Lifetime = param.kind
2353 && let Some(&original) = seen_lifetimes.get(&ident)
2355 diagnostics::signal_lifetime_shadowing(self.r.session, original, param.ident);
2356 // Record lifetime res, so lowering knows there is something fishy.
2357 self.record_lifetime_param(param.id, LifetimeRes::Error);
2361 match seen_bindings.entry(ident) {
2362 Entry::Occupied(entry) => {
2363 let span = *entry.get();
2364 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
2365 self.report_error(param.ident.span, err);
2366 if let GenericParamKind::Lifetime = param.kind {
2367 // Record lifetime res, so lowering knows there is something fishy.
2368 self.record_lifetime_param(param.id, LifetimeRes::Error);
2372 Entry::Vacant(entry) => {
2373 entry.insert(param.ident.span);
2377 if param.ident.name == kw::UnderscoreLifetime {
2378 rustc_errors::struct_span_err!(
2382 "`'_` cannot be used here"
2384 .span_label(param.ident.span, "`'_` is a reserved lifetime name")
2386 // Record lifetime res, so lowering knows there is something fishy.
2387 self.record_lifetime_param(param.id, LifetimeRes::Error);
2391 if param.ident.name == kw::StaticLifetime {
2392 rustc_errors::struct_span_err!(
2396 "invalid lifetime parameter name: `{}`",
2399 .span_label(param.ident.span, "'static is a reserved lifetime name")
2401 // Record lifetime res, so lowering knows there is something fishy.
2402 self.record_lifetime_param(param.id, LifetimeRes::Error);
2406 let def_id = self.r.local_def_id(param.id);
2408 // Plain insert (no renaming).
2409 let (rib, def_kind) = match param.kind {
2410 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
2411 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
2412 GenericParamKind::Lifetime => {
2413 let res = LifetimeRes::Param { param: def_id, binder };
2414 self.record_lifetime_param(param.id, res);
2415 function_lifetime_rib.bindings.insert(ident, (param.id, res));
2420 let res = match kind {
2421 ItemRibKind(..) | AssocItemRibKind => Res::Def(def_kind, def_id.to_def_id()),
2422 NormalRibKind => Res::Err,
2423 _ => span_bug!(param.ident.span, "Unexpected rib kind {:?}", kind),
2425 self.r.record_partial_res(param.id, PartialRes::new(res));
2426 rib.bindings.insert(ident, res);
2429 self.lifetime_ribs.push(function_lifetime_rib);
2430 self.ribs[ValueNS].push(function_value_rib);
2431 self.ribs[TypeNS].push(function_type_rib);
2435 self.ribs[TypeNS].pop();
2436 self.ribs[ValueNS].pop();
2437 let function_lifetime_rib = self.lifetime_ribs.pop().unwrap();
2439 // Do not account for the parameters we just bound for function lifetime elision.
2440 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
2441 for (_, res) in function_lifetime_rib.bindings.values() {
2442 candidates.retain(|(r, _)| r != res);
2446 if let LifetimeBinderKind::BareFnType
2447 | LifetimeBinderKind::WhereBound
2448 | LifetimeBinderKind::Function
2449 | LifetimeBinderKind::ImplBlock = generics_kind
2451 self.maybe_report_lifetime_uses(generics_span, params)
2455 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
2456 self.label_ribs.push(Rib::new(kind));
2458 self.label_ribs.pop();
2461 fn with_static_rib(&mut self, f: impl FnOnce(&mut Self)) {
2462 let kind = ItemRibKind(HasGenericParams::No);
2463 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
2466 // HACK(min_const_generics,const_evaluatable_unchecked): We
2467 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
2468 // with a future compat lint for now. We do this by adding an
2469 // additional special case for repeat expressions.
2471 // Note that we intentionally still forbid `[0; N + 1]` during
2472 // name resolution so that we don't extend the future
2473 // compat lint to new cases.
2474 #[instrument(level = "debug", skip(self, f))]
2475 fn with_constant_rib(
2477 is_repeat: IsRepeatExpr,
2478 may_use_generics: ConstantHasGenerics,
2479 item: Option<(Ident, ConstantItemKind)>,
2480 f: impl FnOnce(&mut Self),
2482 self.with_rib(ValueNS, ConstantItemRibKind(may_use_generics, item), |this| {
2485 ConstantItemRibKind(
2486 may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes),
2490 this.with_label_rib(ConstantItemRibKind(may_use_generics, item), f);
2496 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
2497 // Handle nested impls (inside fn bodies)
2498 let previous_value =
2499 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
2500 let result = f(self);
2501 self.diagnostic_metadata.current_self_type = previous_value;
2505 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
2506 let previous_value =
2507 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
2508 let result = f(self);
2509 self.diagnostic_metadata.current_self_item = previous_value;
2513 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
2514 fn resolve_trait_items(&mut self, trait_items: &'ast [P<AssocItem>]) {
2515 let trait_assoc_items =
2516 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
2518 let walk_assoc_item =
2519 |this: &mut Self, generics: &Generics, kind, item: &'ast AssocItem| {
2520 this.with_generic_param_rib(
2523 LifetimeRibKind::Generics { binder: item.id, span: generics.span, kind },
2524 |this| visit::walk_assoc_item(this, item, AssocCtxt::Trait),
2528 for item in trait_items {
2530 AssocItemKind::Const(_, ty, default) => {
2532 // Only impose the restrictions of `ConstRibKind` for an
2533 // actual constant expression in a provided default.
2534 if let Some(expr) = default {
2535 // We allow arbitrary const expressions inside of associated consts,
2536 // even if they are potentially not const evaluatable.
2538 // Type parameters can already be used and as associated consts are
2539 // not used as part of the type system, this is far less surprising.
2540 self.with_lifetime_rib(
2541 LifetimeRibKind::Elided(LifetimeRes::Infer),
2543 this.with_constant_rib(
2545 ConstantHasGenerics::Yes,
2547 |this| this.visit_expr(expr),
2553 AssocItemKind::Fn(box Fn { generics, .. }) => {
2554 walk_assoc_item(self, generics, LifetimeBinderKind::Function, item);
2556 AssocItemKind::Type(box TyAlias { generics, .. }) => self
2557 .with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2558 walk_assoc_item(this, generics, LifetimeBinderKind::Item, item)
2560 AssocItemKind::MacCall(_) => {
2561 panic!("unexpanded macro in resolve!")
2566 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
2569 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
2570 fn with_optional_trait_ref<T>(
2572 opt_trait_ref: Option<&TraitRef>,
2573 self_type: &'ast Ty,
2574 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
2576 let mut new_val = None;
2577 let mut new_id = None;
2578 if let Some(trait_ref) = opt_trait_ref {
2579 let path: Vec<_> = Segment::from_path(&trait_ref.path);
2580 self.diagnostic_metadata.currently_processing_impl_trait =
2581 Some((trait_ref.clone(), self_type.clone()));
2582 let res = self.smart_resolve_path_fragment(
2585 PathSource::Trait(AliasPossibility::No),
2586 Finalize::new(trait_ref.ref_id, trait_ref.path.span),
2588 self.diagnostic_metadata.currently_processing_impl_trait = None;
2589 if let Some(def_id) = res.expect_full_res().opt_def_id() {
2590 new_id = Some(def_id);
2591 new_val = Some((self.r.expect_module(def_id), trait_ref.clone()));
2594 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
2595 let result = f(self, new_id);
2596 self.current_trait_ref = original_trait_ref;
2600 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
2601 let mut self_type_rib = Rib::new(NormalRibKind);
2603 // Plain insert (no renaming, since types are not currently hygienic)
2604 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
2605 self.ribs[ns].push(self_type_rib);
2607 self.ribs[ns].pop();
2610 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
2611 self.with_self_rib_ns(TypeNS, self_res, f)
2614 fn resolve_implementation(
2616 generics: &'ast Generics,
2617 opt_trait_reference: &'ast Option<TraitRef>,
2618 self_type: &'ast Ty,
2620 impl_items: &'ast [P<AssocItem>],
2622 debug!("resolve_implementation");
2623 // If applicable, create a rib for the type parameters.
2624 self.with_generic_param_rib(
2626 ItemRibKind(HasGenericParams::Yes(generics.span)),
2627 LifetimeRibKind::Generics {
2628 span: generics.span,
2630 kind: LifetimeBinderKind::ImplBlock,
2633 // Dummy self type for better errors if `Self` is used in the trait path.
2634 this.with_self_rib(Res::SelfTyParam { trait_: LOCAL_CRATE.as_def_id() }, |this| {
2635 this.with_lifetime_rib(
2636 LifetimeRibKind::AnonymousCreateParameter {
2638 report_in_path: true
2641 // Resolve the trait reference, if necessary.
2642 this.with_optional_trait_ref(
2643 opt_trait_reference.as_ref(),
2646 let item_def_id = this.r.local_def_id(item_id);
2648 // Register the trait definitions from here.
2649 if let Some(trait_id) = trait_id {
2657 let item_def_id = item_def_id.to_def_id();
2658 let res = Res::SelfTyAlias {
2659 alias_to: item_def_id,
2660 forbid_generic: false,
2661 is_trait_impl: trait_id.is_some()
2663 this.with_self_rib(res, |this| {
2664 if let Some(trait_ref) = opt_trait_reference.as_ref() {
2665 // Resolve type arguments in the trait path.
2666 visit::walk_trait_ref(this, trait_ref);
2668 // Resolve the self type.
2669 this.visit_ty(self_type);
2670 // Resolve the generic parameters.
2671 this.visit_generics(generics);
2673 // Resolve the items within the impl.
2674 this.with_current_self_type(self_type, |this| {
2675 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
2676 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
2677 let mut seen_trait_items = Default::default();
2678 for item in impl_items {
2679 this.resolve_impl_item(&**item, &mut seen_trait_items);
2693 fn resolve_impl_item(
2695 item: &'ast AssocItem,
2696 seen_trait_items: &mut FxHashMap<DefId, Span>,
2698 use crate::ResolutionError::*;
2700 AssocItemKind::Const(_, ty, default) => {
2701 debug!("resolve_implementation AssocItemKind::Const");
2702 // If this is a trait impl, ensure the const
2704 self.check_trait_item(
2711 |i, s, c| ConstNotMemberOfTrait(i, s, c),
2715 if let Some(expr) = default {
2716 // We allow arbitrary const expressions inside of associated consts,
2717 // even if they are potentially not const evaluatable.
2719 // Type parameters can already be used and as associated consts are
2720 // not used as part of the type system, this is far less surprising.
2721 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2722 this.with_constant_rib(
2724 ConstantHasGenerics::Yes,
2726 |this| this.visit_expr(expr),
2731 AssocItemKind::Fn(box Fn { generics, .. }) => {
2732 debug!("resolve_implementation AssocItemKind::Fn");
2733 // We also need a new scope for the impl item type parameters.
2734 self.with_generic_param_rib(
2737 LifetimeRibKind::Generics {
2739 span: generics.span,
2740 kind: LifetimeBinderKind::Function,
2743 // If this is a trait impl, ensure the method
2745 this.check_trait_item(
2752 |i, s, c| MethodNotMemberOfTrait(i, s, c),
2755 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2759 AssocItemKind::Type(box TyAlias { generics, .. }) => {
2760 debug!("resolve_implementation AssocItemKind::Type");
2761 // We also need a new scope for the impl item type parameters.
2762 self.with_generic_param_rib(
2765 LifetimeRibKind::Generics {
2767 span: generics.span,
2768 kind: LifetimeBinderKind::Item,
2771 this.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2772 // If this is a trait impl, ensure the type
2774 this.check_trait_item(
2781 |i, s, c| TypeNotMemberOfTrait(i, s, c),
2784 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2789 AssocItemKind::MacCall(_) => {
2790 panic!("unexpanded macro in resolve!")
2795 fn check_trait_item<F>(
2799 kind: &AssocItemKind,
2802 seen_trait_items: &mut FxHashMap<DefId, Span>,
2805 F: FnOnce(Ident, String, Option<Symbol>) -> ResolutionError<'a>,
2807 // If there is a TraitRef in scope for an impl, then the method must be in the trait.
2808 let Some((module, _)) = &self.current_trait_ref else { return; };
2809 ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
2810 let key = self.r.new_key(ident, ns);
2811 let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2813 if binding.is_none() {
2814 // We could not find the trait item in the correct namespace.
2815 // Check the other namespace to report an error.
2821 let key = self.r.new_key(ident, ns);
2822 binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2825 let Some(binding) = binding else {
2826 // We could not find the method: report an error.
2827 let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
2828 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2829 let path_names = path_names_to_string(path);
2830 self.report_error(span, err(ident, path_names, candidate));
2834 let res = binding.res();
2835 let Res::Def(def_kind, id_in_trait) = res else { bug!() };
2837 match seen_trait_items.entry(id_in_trait) {
2838 Entry::Occupied(entry) => {
2841 ResolutionError::TraitImplDuplicate {
2843 old_span: *entry.get(),
2844 trait_item_span: binding.span,
2849 Entry::Vacant(entry) => {
2854 match (def_kind, kind) {
2855 (DefKind::AssocTy, AssocItemKind::Type(..))
2856 | (DefKind::AssocFn, AssocItemKind::Fn(..))
2857 | (DefKind::AssocConst, AssocItemKind::Const(..)) => {
2858 self.r.record_partial_res(id, PartialRes::new(res));
2864 // The method kind does not correspond to what appeared in the trait, report.
2865 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2866 let (code, kind) = match kind {
2867 AssocItemKind::Const(..) => (rustc_errors::error_code!(E0323), "const"),
2868 AssocItemKind::Fn(..) => (rustc_errors::error_code!(E0324), "method"),
2869 AssocItemKind::Type(..) => (rustc_errors::error_code!(E0325), "type"),
2870 AssocItemKind::MacCall(..) => span_bug!(span, "unexpanded macro"),
2872 let trait_path = path_names_to_string(path);
2875 ResolutionError::TraitImplMismatch {
2880 trait_item_span: binding.span,
2885 fn resolve_params(&mut self, params: &'ast [Param]) {
2886 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2887 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2888 for Param { pat, .. } in params {
2889 this.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
2892 for Param { ty, .. } in params {
2897 fn resolve_local(&mut self, local: &'ast Local) {
2898 debug!("resolving local ({:?})", local);
2899 // Resolve the type.
2900 walk_list!(self, visit_ty, &local.ty);
2902 // Resolve the initializer.
2903 if let Some((init, els)) = local.kind.init_else_opt() {
2904 self.visit_expr(init);
2906 // Resolve the `else` block
2907 if let Some(els) = els {
2908 self.visit_block(els);
2912 // Resolve the pattern.
2913 self.resolve_pattern_top(&local.pat, PatternSource::Let);
2916 /// build a map from pattern identifiers to binding-info's.
2917 /// this is done hygienically. This could arise for a macro
2918 /// that expands into an or-pattern where one 'x' was from the
2919 /// user and one 'x' came from the macro.
2920 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2921 let mut binding_map = FxHashMap::default();
2923 pat.walk(&mut |pat| {
2925 PatKind::Ident(annotation, ident, ref sub_pat)
2926 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
2928 binding_map.insert(ident, BindingInfo { span: ident.span, annotation });
2930 PatKind::Or(ref ps) => {
2931 // Check the consistency of this or-pattern and
2932 // then add all bindings to the larger map.
2933 for bm in self.check_consistent_bindings(ps) {
2934 binding_map.extend(bm);
2947 fn is_base_res_local(&self, nid: NodeId) -> bool {
2949 self.r.partial_res_map.get(&nid).map(|res| res.expect_full_res()),
2950 Some(Res::Local(..))
2954 /// Checks that all of the arms in an or-pattern have exactly the
2955 /// same set of bindings, with the same binding modes for each.
2956 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
2957 let mut missing_vars = FxHashMap::default();
2958 let mut inconsistent_vars = FxHashMap::default();
2960 // 1) Compute the binding maps of all arms.
2961 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
2963 // 2) Record any missing bindings or binding mode inconsistencies.
2964 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
2965 // Check against all arms except for the same pattern which is always self-consistent.
2969 .filter(|(_, pat)| pat.id != pat_outer.id)
2970 .flat_map(|(idx, _)| maps[idx].iter())
2971 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
2973 for (name, info, &binding_inner) in inners {
2976 // The inner binding is missing in the outer.
2978 missing_vars.entry(name).or_insert_with(|| BindingError {
2980 origin: BTreeSet::new(),
2981 target: BTreeSet::new(),
2982 could_be_path: name.as_str().starts_with(char::is_uppercase),
2984 binding_error.origin.insert(binding_inner.span);
2985 binding_error.target.insert(pat_outer.span);
2987 Some(binding_outer) => {
2988 if binding_outer.annotation != binding_inner.annotation {
2989 // The binding modes in the outer and inner bindings differ.
2992 .or_insert((binding_inner.span, binding_outer.span));
2999 // 3) Report all missing variables we found.
3000 let mut missing_vars = missing_vars.into_iter().collect::<Vec<_>>();
3001 missing_vars.sort_by_key(|&(sym, ref _err)| sym);
3003 for (name, mut v) in missing_vars.into_iter() {
3004 if inconsistent_vars.contains_key(&name) {
3005 v.could_be_path = false;
3008 *v.origin.iter().next().unwrap(),
3009 ResolutionError::VariableNotBoundInPattern(v, self.parent_scope),
3013 // 4) Report all inconsistencies in binding modes we found.
3014 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
3015 inconsistent_vars.sort();
3016 for (name, v) in inconsistent_vars {
3017 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
3020 // 5) Finally bubble up all the binding maps.
3024 /// Check the consistency of the outermost or-patterns.
3025 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
3026 pat.walk(&mut |pat| match pat.kind {
3027 PatKind::Or(ref ps) => {
3028 self.check_consistent_bindings(ps);
3035 fn resolve_arm(&mut self, arm: &'ast Arm) {
3036 self.with_rib(ValueNS, NormalRibKind, |this| {
3037 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
3038 walk_list!(this, visit_expr, &arm.guard);
3039 this.visit_expr(&arm.body);
3043 /// Arising from `source`, resolve a top level pattern.
3044 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
3045 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
3046 self.resolve_pattern(pat, pat_src, &mut bindings);
3052 pat_src: PatternSource,
3053 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3055 // We walk the pattern before declaring the pattern's inner bindings,
3056 // so that we avoid resolving a literal expression to a binding defined
3058 visit::walk_pat(self, pat);
3059 self.resolve_pattern_inner(pat, pat_src, bindings);
3060 // This has to happen *after* we determine which pat_idents are variants:
3061 self.check_consistent_bindings_top(pat);
3064 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
3068 /// A stack of sets of bindings accumulated.
3070 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
3071 /// be interpreted as re-binding an already bound binding. This results in an error.
3072 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
3073 /// in reusing this binding rather than creating a fresh one.
3075 /// When called at the top level, the stack must have a single element
3076 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
3077 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
3078 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
3079 /// When each `p_i` has been dealt with, the top set is merged with its parent.
3080 /// When a whole or-pattern has been dealt with, the thing happens.
3082 /// See the implementation and `fresh_binding` for more details.
3083 fn resolve_pattern_inner(
3086 pat_src: PatternSource,
3087 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3089 // Visit all direct subpatterns of this pattern.
3090 pat.walk(&mut |pat| {
3091 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
3093 PatKind::Ident(bmode, ident, ref sub) => {
3094 // First try to resolve the identifier as some existing entity,
3095 // then fall back to a fresh binding.
3096 let has_sub = sub.is_some();
3098 .try_resolve_as_non_binding(pat_src, bmode, ident, has_sub)
3099 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
3100 self.r.record_partial_res(pat.id, PartialRes::new(res));
3101 self.r.record_pat_span(pat.id, pat.span);
3103 PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
3104 self.smart_resolve_path(
3108 PathSource::TupleStruct(
3110 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
3114 PatKind::Path(ref qself, ref path) => {
3115 self.smart_resolve_path(pat.id, qself, path, PathSource::Pat);
3117 PatKind::Struct(ref qself, ref path, ..) => {
3118 self.smart_resolve_path(pat.id, qself, path, PathSource::Struct);
3120 PatKind::Or(ref ps) => {
3121 // Add a new set of bindings to the stack. `Or` here records that when a
3122 // binding already exists in this set, it should not result in an error because
3123 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
3124 bindings.push((PatBoundCtx::Or, Default::default()));
3126 // Now we need to switch back to a product context so that each
3127 // part of the or-pattern internally rejects already bound names.
3128 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
3129 bindings.push((PatBoundCtx::Product, Default::default()));
3130 self.resolve_pattern_inner(p, pat_src, bindings);
3131 // Move up the non-overlapping bindings to the or-pattern.
3132 // Existing bindings just get "merged".
3133 let collected = bindings.pop().unwrap().1;
3134 bindings.last_mut().unwrap().1.extend(collected);
3136 // This or-pattern itself can itself be part of a product,
3137 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
3138 // Both cases bind `a` again in a product pattern and must be rejected.
3139 let collected = bindings.pop().unwrap().1;
3140 bindings.last_mut().unwrap().1.extend(collected);
3142 // Prevent visiting `ps` as we've already done so above.
3155 pat_src: PatternSource,
3156 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3158 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
3159 // (We must not add it if it's in the bindings map because that breaks the assumptions
3160 // later passes make about or-patterns.)
3161 let ident = ident.normalize_to_macro_rules();
3163 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
3164 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
3165 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
3166 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
3167 // This is *required* for consistency which is checked later.
3168 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
3170 if already_bound_and {
3171 // Overlap in a product pattern somewhere; report an error.
3172 use ResolutionError::*;
3173 let error = match pat_src {
3174 // `fn f(a: u8, a: u8)`:
3175 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
3177 _ => IdentifierBoundMoreThanOnceInSamePattern,
3179 self.report_error(ident.span, error(ident.name));
3182 // Record as bound if it's valid:
3183 let ident_valid = ident.name != kw::Empty;
3185 bindings.last_mut().unwrap().1.insert(ident);
3188 if already_bound_or {
3189 // `Variant1(a) | Variant2(a)`, ok
3190 // Reuse definition from the first `a`.
3191 self.innermost_rib_bindings(ValueNS)[&ident]
3193 let res = Res::Local(pat_id);
3195 // A completely fresh binding add to the set if it's valid.
3196 self.innermost_rib_bindings(ValueNS).insert(ident, res);
3202 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
3203 &mut self.ribs[ns].last_mut().unwrap().bindings
3206 fn try_resolve_as_non_binding(
3208 pat_src: PatternSource,
3209 ann: BindingAnnotation,
3213 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
3214 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
3215 // also be interpreted as a path to e.g. a constant, variant, etc.
3216 let is_syntactic_ambiguity = !has_sub && ann == BindingAnnotation::NONE;
3218 let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?;
3219 let (res, binding) = match ls_binding {
3220 LexicalScopeBinding::Item(binding)
3221 if is_syntactic_ambiguity && binding.is_ambiguity() =>
3223 // For ambiguous bindings we don't know all their definitions and cannot check
3224 // whether they can be shadowed by fresh bindings or not, so force an error.
3225 // issues/33118#issuecomment-233962221 (see below) still applies here,
3226 // but we have to ignore it for backward compatibility.
3227 self.r.record_use(ident, binding, false);
3230 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
3231 LexicalScopeBinding::Res(res) => (res, None),
3235 Res::SelfCtor(_) // See #70549.
3237 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
3239 ) if is_syntactic_ambiguity => {
3240 // Disambiguate in favor of a unit struct/variant or constant pattern.
3241 if let Some(binding) = binding {
3242 self.r.record_use(ident, binding, false);
3246 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static(_), _) => {
3247 // This is unambiguously a fresh binding, either syntactically
3248 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
3249 // to something unusable as a pattern (e.g., constructor function),
3250 // but we still conservatively report an error, see
3251 // issues/33118#issuecomment-233962221 for one reason why.
3252 let binding = binding.expect("no binding for a ctor or static");
3255 ResolutionError::BindingShadowsSomethingUnacceptable {
3256 shadowing_binding: pat_src,
3258 participle: if binding.is_import() { "imported" } else { "defined" },
3259 article: binding.res().article(),
3260 shadowed_binding: binding.res(),
3261 shadowed_binding_span: binding.span,
3266 Res::Def(DefKind::ConstParam, def_id) => {
3267 // Same as for DefKind::Const above, but here, `binding` is `None`, so we
3268 // have to construct the error differently
3271 ResolutionError::BindingShadowsSomethingUnacceptable {
3272 shadowing_binding: pat_src,
3274 participle: "defined",
3275 article: res.article(),
3276 shadowed_binding: res,
3277 shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"),
3282 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
3283 // These entities are explicitly allowed to be shadowed by fresh bindings.
3286 Res::SelfCtor(_) => {
3287 // We resolve `Self` in pattern position as an ident sometimes during recovery,
3288 // so delay a bug instead of ICEing.
3289 self.r.session.delay_span_bug(
3291 "unexpected `SelfCtor` in pattern, expected identifier"
3297 "unexpected resolution for an identifier in pattern: {:?}",
3303 // High-level and context dependent path resolution routine.
3304 // Resolves the path and records the resolution into definition map.
3305 // If resolution fails tries several techniques to find likely
3306 // resolution candidates, suggest imports or other help, and report
3307 // errors in user friendly way.
3308 fn smart_resolve_path(
3311 qself: &Option<P<QSelf>>,
3313 source: PathSource<'ast>,
3315 self.smart_resolve_path_fragment(
3317 &Segment::from_path(path),
3319 Finalize::new(id, path.span),
3323 fn smart_resolve_path_fragment(
3325 qself: &Option<P<QSelf>>,
3327 source: PathSource<'ast>,
3331 "smart_resolve_path_fragment(qself={:?}, path={:?}, finalize={:?})",
3332 qself, path, finalize,
3334 let ns = source.namespace();
3336 let Finalize { node_id, path_span, .. } = finalize;
3337 let report_errors = |this: &mut Self, res: Option<Res>| {
3338 if this.should_report_errs() {
3339 let (err, candidates) =
3340 this.smart_resolve_report_errors(path, path_span, source, res);
3342 let def_id = this.parent_scope.module.nearest_parent_mod();
3343 let instead = res.is_some();
3345 if res.is_none() { this.report_missing_type_error(path) } else { None };
3347 this.r.use_injections.push(UseError {
3354 is_call: source.is_call(),
3358 PartialRes::new(Res::Err)
3361 // For paths originating from calls (like in `HashMap::new()`), tries
3362 // to enrich the plain `failed to resolve: ...` message with hints
3363 // about possible missing imports.
3365 // Similar thing, for types, happens in `report_errors` above.
3366 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
3367 if !source.is_call() {
3368 return Some(parent_err);
3371 // Before we start looking for candidates, we have to get our hands
3372 // on the type user is trying to perform invocation on; basically:
3373 // we're transforming `HashMap::new` into just `HashMap`.
3374 let prefix_path = match path.split_last() {
3375 Some((_, path)) if !path.is_empty() => path,
3376 _ => return Some(parent_err),
3379 let (mut err, candidates) =
3380 this.smart_resolve_report_errors(prefix_path, path_span, PathSource::Type, None);
3382 // There are two different error messages user might receive at
3384 // - E0412 cannot find type `{}` in this scope
3385 // - E0433 failed to resolve: use of undeclared type or module `{}`
3387 // The first one is emitted for paths in type-position, and the
3388 // latter one - for paths in expression-position.
3390 // Thus (since we're in expression-position at this point), not to
3391 // confuse the user, we want to keep the *message* from E0433 (so
3392 // `parent_err`), but we want *hints* from E0412 (so `err`).
3394 // And that's what happens below - we're just mixing both messages
3395 // into a single one.
3396 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
3398 // overwrite all properties with the parent's error message
3399 err.message = take(&mut parent_err.message);
3400 err.code = take(&mut parent_err.code);
3401 swap(&mut err.span, &mut parent_err.span);
3402 err.children = take(&mut parent_err.children);
3403 err.sort_span = parent_err.sort_span;
3404 err.is_lint = parent_err.is_lint;
3406 // merge the parent's suggestions with the typo suggestions
3407 fn append_result<T, E>(res1: &mut Result<Vec<T>, E>, res2: Result<Vec<T>, E>) {
3409 Ok(vec1) => match res2 {
3410 Ok(mut vec2) => vec1.append(&mut vec2),
3411 Err(e) => *res1 = Err(e),
3416 append_result(&mut err.suggestions, parent_err.suggestions.clone());
3418 parent_err.cancel();
3420 let def_id = this.parent_scope.module.nearest_parent_mod();
3422 if this.should_report_errs() {
3423 if candidates.is_empty() {
3424 if path.len() == 2 && prefix_path.len() == 1 {
3425 // Delay to check whether methond name is an associated function or not
3427 // let foo = Foo {};
3428 // foo::bar(); // possibly suggest to foo.bar();
3431 prefix_path[0].ident.span,
3432 rustc_errors::StashKey::CallAssocMethod,
3435 // When there is no suggested imports, we can just emit the error
3436 // and suggestions immediately. Note that we bypass the usually error
3437 // reporting routine (ie via `self.r.report_error`) because we need
3438 // to post-process the `ResolutionError` above.
3442 // If there are suggested imports, the error reporting is delayed
3443 this.r.use_injections.push(UseError {
3449 path: prefix_path.into(),
3450 is_call: source.is_call(),
3457 // We don't return `Some(parent_err)` here, because the error will
3458 // be already printed either immediately or as part of the `use` injections
3462 let partial_res = match self.resolve_qpath_anywhere(
3467 source.defer_to_typeck(),
3470 Ok(Some(partial_res)) if let Some(res) = partial_res.full_res() => {
3471 if source.is_expected(res) || res == Res::Err {
3474 report_errors(self, Some(res))
3478 Ok(Some(partial_res)) if source.defer_to_typeck() => {
3479 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
3480 // or `<T>::A::B`. If `B` should be resolved in value namespace then
3481 // it needs to be added to the trait map.
3483 let item_name = path.last().unwrap().ident;
3484 let traits = self.traits_in_scope(item_name, ns);
3485 self.r.trait_map.insert(node_id, traits);
3488 if PrimTy::from_name(path[0].ident.name).is_some() {
3489 let mut std_path = Vec::with_capacity(1 + path.len());
3491 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
3492 std_path.extend(path);
3493 if let PathResult::Module(_) | PathResult::NonModule(_) =
3494 self.resolve_path(&std_path, Some(ns), None)
3496 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
3498 path.iter().last().map_or(path_span, |segment| segment.ident.span);
3500 self.r.confused_type_with_std_module.insert(item_span, path_span);
3501 self.r.confused_type_with_std_module.insert(path_span, path_span);
3509 if let Some(err) = report_errors_for_call(self, err) {
3510 self.report_error(err.span, err.node);
3513 PartialRes::new(Res::Err)
3516 _ => report_errors(self, None),
3519 if !matches!(source, PathSource::TraitItem(..)) {
3520 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
3521 self.r.record_partial_res(node_id, partial_res);
3522 self.resolve_elided_lifetimes_in_path(node_id, partial_res, path, source, path_span);
3528 fn self_type_is_available(&mut self) -> bool {
3530 .maybe_resolve_ident_in_lexical_scope(Ident::with_dummy_span(kw::SelfUpper), TypeNS);
3531 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3534 fn self_value_is_available(&mut self, self_span: Span) -> bool {
3535 let ident = Ident::new(kw::SelfLower, self_span);
3536 let binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS);
3537 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3540 /// A wrapper around [`Resolver::report_error`].
3542 /// This doesn't emit errors for function bodies if this is rustdoc.
3543 fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) {
3544 if self.should_report_errs() {
3545 self.r.report_error(span, resolution_error);
3550 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
3551 fn should_report_errs(&self) -> bool {
3552 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
3555 // Resolve in alternative namespaces if resolution in the primary namespace fails.
3556 fn resolve_qpath_anywhere(
3558 qself: &Option<P<QSelf>>,
3560 primary_ns: Namespace,
3562 defer_to_typeck: bool,
3564 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3565 let mut fin_res = None;
3567 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
3568 if i == 0 || ns != primary_ns {
3569 match self.resolve_qpath(qself, path, ns, finalize)? {
3571 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
3573 return Ok(Some(partial_res));
3576 if fin_res.is_none() {
3577 fin_res = partial_res;
3584 assert!(primary_ns != MacroNS);
3586 if qself.is_none() {
3587 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
3588 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
3589 if let Ok((_, res)) =
3590 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
3592 return Ok(Some(PartialRes::new(res)));
3599 /// Handles paths that may refer to associated items.
3602 qself: &Option<P<QSelf>>,
3606 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3608 "resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})",
3609 qself, path, ns, finalize,
3612 if let Some(qself) = qself {
3613 if qself.position == 0 {
3614 // This is a case like `<T>::B`, where there is no
3615 // trait to resolve. In that case, we leave the `B`
3616 // segment to be resolved by type-check.
3617 return Ok(Some(PartialRes::with_unresolved_segments(
3618 Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()),
3623 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
3625 // Currently, `path` names the full item (`A::B::C`, in
3626 // our example). so we extract the prefix of that that is
3627 // the trait (the slice upto and including
3628 // `qself.position`). And then we recursively resolve that,
3629 // but with `qself` set to `None`.
3630 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
3631 let partial_res = self.smart_resolve_path_fragment(
3633 &path[..=qself.position],
3634 PathSource::TraitItem(ns),
3635 Finalize::with_root_span(finalize.node_id, finalize.path_span, qself.path_span),
3638 // The remaining segments (the `C` in our example) will
3639 // have to be resolved by type-check, since that requires doing
3640 // trait resolution.
3641 return Ok(Some(PartialRes::with_unresolved_segments(
3642 partial_res.base_res(),
3643 partial_res.unresolved_segments() + path.len() - qself.position - 1,
3647 let result = match self.resolve_path(&path, Some(ns), Some(finalize)) {
3648 PathResult::NonModule(path_res) => path_res,
3649 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
3650 PartialRes::new(module.res().unwrap())
3652 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
3653 // don't report an error right away, but try to fallback to a primitive type.
3654 // So, we are still able to successfully resolve something like
3656 // use std::u8; // bring module u8 in scope
3657 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
3658 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
3659 // // not to non-existent std::u8::max_value
3662 // Such behavior is required for backward compatibility.
3663 // The same fallback is used when `a` resolves to nothing.
3664 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
3665 if (ns == TypeNS || path.len() > 1)
3666 && PrimTy::from_name(path[0].ident.name).is_some() =>
3668 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
3669 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
3671 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3672 PartialRes::new(module.res().unwrap())
3674 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
3675 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
3677 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
3678 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
3682 && let Some(res) = result.full_res()
3684 && path[0].ident.name != kw::PathRoot
3685 && path[0].ident.name != kw::DollarCrate
3687 let unqualified_result = {
3688 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
3689 PathResult::NonModule(path_res) => path_res.expect_full_res(),
3690 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3691 module.res().unwrap()
3693 _ => return Ok(Some(result)),
3696 if res == unqualified_result {
3697 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
3698 self.r.lint_buffer.buffer_lint(
3702 "unnecessary qualification",
3710 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
3711 if let Some(label) = label {
3712 if label.ident.as_str().as_bytes()[1] != b'_' {
3713 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
3716 if let Ok((_, orig_span)) = self.resolve_label(label.ident) {
3717 diagnostics::signal_label_shadowing(self.r.session, orig_span, label.ident)
3720 self.with_label_rib(NormalRibKind, |this| {
3721 let ident = label.ident.normalize_to_macro_rules();
3722 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
3730 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
3731 self.with_resolved_label(label, id, |this| this.visit_block(block));
3734 fn resolve_block(&mut self, block: &'ast Block) {
3735 debug!("(resolving block) entering block");
3736 // Move down in the graph, if there's an anonymous module rooted here.
3737 let orig_module = self.parent_scope.module;
3738 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
3740 let mut num_macro_definition_ribs = 0;
3741 if let Some(anonymous_module) = anonymous_module {
3742 debug!("(resolving block) found anonymous module, moving down");
3743 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3744 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3745 self.parent_scope.module = anonymous_module;
3747 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3750 let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
3751 if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
3752 (block.could_be_bare_literal, &block.stmts[..])
3753 && let ExprKind::Type(..) = expr.kind
3755 self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
3758 // Descend into the block.
3759 for stmt in &block.stmts {
3760 if let StmtKind::Item(ref item) = stmt.kind
3761 && let ItemKind::MacroDef(..) = item.kind {
3762 num_macro_definition_ribs += 1;
3763 let res = self.r.local_def_id(item.id).to_def_id();
3764 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
3765 self.label_ribs.push(Rib::new(MacroDefinition(res)));
3768 self.visit_stmt(stmt);
3770 self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
3773 self.parent_scope.module = orig_module;
3774 for _ in 0..num_macro_definition_ribs {
3775 self.ribs[ValueNS].pop();
3776 self.label_ribs.pop();
3778 self.last_block_rib = self.ribs[ValueNS].pop();
3779 if anonymous_module.is_some() {
3780 self.ribs[TypeNS].pop();
3782 debug!("(resolving block) leaving block");
3785 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
3786 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
3787 self.with_constant_rib(
3789 if constant.value.is_potential_trivial_const_param() {
3790 ConstantHasGenerics::Yes
3792 ConstantHasGenerics::No
3795 |this| visit::walk_anon_const(this, constant),
3799 fn resolve_inline_const(&mut self, constant: &'ast AnonConst) {
3800 debug!("resolve_anon_const {constant:?}");
3801 self.with_constant_rib(IsRepeatExpr::No, ConstantHasGenerics::Yes, None, |this| {
3802 visit::walk_anon_const(this, constant)
3806 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
3807 // First, record candidate traits for this expression if it could
3808 // result in the invocation of a method call.
3810 self.record_candidate_traits_for_expr_if_necessary(expr);
3812 // Next, resolve the node.
3814 ExprKind::Path(ref qself, ref path) => {
3815 self.smart_resolve_path(expr.id, qself, path, PathSource::Expr(parent));
3816 visit::walk_expr(self, expr);
3819 ExprKind::Struct(ref se) => {
3820 self.smart_resolve_path(expr.id, &se.qself, &se.path, PathSource::Struct);
3821 visit::walk_expr(self, expr);
3824 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
3825 match self.resolve_label(label.ident) {
3826 Ok((node_id, _)) => {
3827 // Since this res is a label, it is never read.
3828 self.r.label_res_map.insert(expr.id, node_id);
3829 self.diagnostic_metadata.unused_labels.remove(&node_id);
3832 self.report_error(label.ident.span, error);
3836 // visit `break` argument if any
3837 visit::walk_expr(self, expr);
3840 ExprKind::Break(None, Some(ref e)) => {
3841 // We use this instead of `visit::walk_expr` to keep the parent expr around for
3842 // better diagnostics.
3843 self.resolve_expr(e, Some(&expr));
3846 ExprKind::Let(ref pat, ref scrutinee, _) => {
3847 self.visit_expr(scrutinee);
3848 self.resolve_pattern_top(pat, PatternSource::Let);
3851 ExprKind::If(ref cond, ref then, ref opt_else) => {
3852 self.with_rib(ValueNS, NormalRibKind, |this| {
3853 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3854 this.visit_expr(cond);
3855 this.diagnostic_metadata.in_if_condition = old;
3856 this.visit_block(then);
3858 if let Some(expr) = opt_else {
3859 self.visit_expr(expr);
3863 ExprKind::Loop(ref block, label, _) => {
3864 self.resolve_labeled_block(label, expr.id, &block)
3867 ExprKind::While(ref cond, ref block, label) => {
3868 self.with_resolved_label(label, expr.id, |this| {
3869 this.with_rib(ValueNS, NormalRibKind, |this| {
3870 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3871 this.visit_expr(cond);
3872 this.diagnostic_metadata.in_if_condition = old;
3873 this.visit_block(block);
3878 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
3879 self.visit_expr(iter_expr);
3880 self.with_rib(ValueNS, NormalRibKind, |this| {
3881 this.resolve_pattern_top(pat, PatternSource::For);
3882 this.resolve_labeled_block(label, expr.id, block);
3886 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
3888 // Equivalent to `visit::walk_expr` + passing some context to children.
3889 ExprKind::Field(ref subexpression, _) => {
3890 self.resolve_expr(subexpression, Some(expr));
3892 ExprKind::MethodCall(box MethodCall { ref seg, ref receiver, ref args, .. }) => {
3893 self.resolve_expr(receiver, Some(expr));
3895 self.resolve_expr(arg, None);
3897 self.visit_path_segment(seg);
3900 ExprKind::Call(ref callee, ref arguments) => {
3901 self.resolve_expr(callee, Some(expr));
3902 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
3903 for (idx, argument) in arguments.iter().enumerate() {
3904 // Constant arguments need to be treated as AnonConst since
3905 // that is how they will be later lowered to HIR.
3906 if const_args.contains(&idx) {
3907 self.with_constant_rib(
3909 if argument.is_potential_trivial_const_param() {
3910 ConstantHasGenerics::Yes
3912 ConstantHasGenerics::No
3916 this.resolve_expr(argument, None);
3920 self.resolve_expr(argument, None);
3924 ExprKind::Type(ref type_expr, ref ty) => {
3925 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
3926 // type ascription. Here we are trying to retrieve the span of the colon token as
3927 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
3928 // with `expr::Ty`, only in this case it will match the span from
3929 // `type_ascription_path_suggestions`.
3930 self.diagnostic_metadata
3931 .current_type_ascription
3932 .push(type_expr.span.between(ty.span));
3933 visit::walk_expr(self, expr);
3934 self.diagnostic_metadata.current_type_ascription.pop();
3936 // `async |x| ...` gets desugared to `|x| async {...}`, so we need to
3937 // resolve the arguments within the proper scopes so that usages of them inside the
3938 // closure are detected as upvars rather than normal closure arg usages.
3939 ExprKind::Closure(box ast::Closure {
3940 asyncness: Async::Yes { .. },
3945 self.with_rib(ValueNS, NormalRibKind, |this| {
3946 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
3947 // Resolve arguments:
3948 this.resolve_params(&fn_decl.inputs);
3949 // No need to resolve return type --
3950 // the outer closure return type is `FnRetTy::Default`.
3952 // Now resolve the inner closure
3954 // No need to resolve arguments: the inner closure has none.
3955 // Resolve the return type:
3956 visit::walk_fn_ret_ty(this, &fn_decl.output);
3958 this.visit_expr(body);
3963 // For closures, ClosureOrAsyncRibKind is added in visit_fn
3964 ExprKind::Closure(box ast::Closure {
3965 binder: ClosureBinder::For { ref generic_params, span },
3968 self.with_generic_param_rib(
3971 LifetimeRibKind::Generics {
3973 kind: LifetimeBinderKind::Closure,
3976 |this| visit::walk_expr(this, expr),
3979 ExprKind::Closure(..) => visit::walk_expr(self, expr),
3980 ExprKind::Async(..) => {
3981 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
3983 ExprKind::Repeat(ref elem, ref ct) => {
3984 self.visit_expr(elem);
3985 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
3986 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
3987 this.resolve_anon_const(ct, IsRepeatExpr::Yes)
3991 ExprKind::ConstBlock(ref ct) => {
3992 self.resolve_inline_const(ct);
3994 ExprKind::Index(ref elem, ref idx) => {
3995 self.resolve_expr(elem, Some(expr));
3996 self.visit_expr(idx);
3998 ExprKind::Assign(ref lhs, ref rhs, _) => {
3999 if !self.diagnostic_metadata.is_assign_rhs {
4000 self.diagnostic_metadata.in_assignment = Some(expr);
4002 self.visit_expr(lhs);
4003 self.diagnostic_metadata.is_assign_rhs = true;
4004 self.diagnostic_metadata.in_assignment = None;
4005 self.visit_expr(rhs);
4006 self.diagnostic_metadata.is_assign_rhs = false;
4009 visit::walk_expr(self, expr);
4014 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
4016 ExprKind::Field(_, ident) => {
4017 // FIXME(#6890): Even though you can't treat a method like a
4018 // field, we need to add any trait methods we find that match
4019 // the field name so that we can do some nice error reporting
4020 // later on in typeck.
4021 let traits = self.traits_in_scope(ident, ValueNS);
4022 self.r.trait_map.insert(expr.id, traits);
4024 ExprKind::MethodCall(ref call) => {
4025 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
4026 let traits = self.traits_in_scope(call.seg.ident, ValueNS);
4027 self.r.trait_map.insert(expr.id, traits);
4035 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
4036 self.r.traits_in_scope(
4037 self.current_trait_ref.as_ref().map(|(module, _)| *module),
4040 Some((ident.name, ns)),
4044 /// Construct the list of in-scope lifetime parameters for async lowering.
4045 /// We include all lifetime parameters, either named or "Fresh".
4046 /// The order of those parameters does not matter, as long as it is
4048 fn record_lifetime_params_for_async(
4051 async_node_id: Option<(NodeId, Span)>,
4053 if let Some((async_node_id, span)) = async_node_id {
4054 let mut extra_lifetime_params =
4055 self.r.extra_lifetime_params_map.get(&fn_id).cloned().unwrap_or_default();
4056 for rib in self.lifetime_ribs.iter().rev() {
4057 extra_lifetime_params.extend(
4058 rib.bindings.iter().map(|(&ident, &(node_id, res))| (ident, node_id, res)),
4061 LifetimeRibKind::Item => break,
4062 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
4063 if let Some(earlier_fresh) = self.r.extra_lifetime_params_map.get(&binder) {
4064 extra_lifetime_params.extend(earlier_fresh);
4067 LifetimeRibKind::Generics { .. } => {}
4069 // We are in a function definition. We should only find `Generics`
4070 // and `AnonymousCreateParameter` inside the innermost `Item`.
4071 span_bug!(span, "unexpected rib kind: {:?}", rib.kind)
4075 self.r.extra_lifetime_params_map.insert(async_node_id, extra_lifetime_params);
4080 struct LifetimeCountVisitor<'a, 'b> {
4081 r: &'b mut Resolver<'a>,
4084 /// Walks the whole crate in DFS order, visiting each item, counting the declared number of
4085 /// lifetime generic parameters.
4086 impl<'ast> Visitor<'ast> for LifetimeCountVisitor<'_, '_> {
4087 fn visit_item(&mut self, item: &'ast Item) {
4089 ItemKind::TyAlias(box TyAlias { ref generics, .. })
4090 | ItemKind::Fn(box Fn { ref generics, .. })
4091 | ItemKind::Enum(_, ref generics)
4092 | ItemKind::Struct(_, ref generics)
4093 | ItemKind::Union(_, ref generics)
4094 | ItemKind::Impl(box Impl { ref generics, .. })
4095 | ItemKind::Trait(box Trait { ref generics, .. })
4096 | ItemKind::TraitAlias(ref generics, _) => {
4097 let def_id = self.r.local_def_id(item.id);
4098 let count = generics
4101 .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
4103 self.r.item_generics_num_lifetimes.insert(def_id, count);
4107 | ItemKind::ForeignMod(..)
4108 | ItemKind::Static(..)
4109 | ItemKind::Const(..)
4111 | ItemKind::ExternCrate(..)
4112 | ItemKind::MacroDef(..)
4113 | ItemKind::GlobalAsm(..)
4114 | ItemKind::MacCall(..) => {}
4116 visit::walk_item(self, item)
4120 impl<'a> Resolver<'a> {
4121 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
4122 visit::walk_crate(&mut LifetimeCountVisitor { r: self }, krate);
4123 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
4124 visit::walk_crate(&mut late_resolution_visitor, krate);
4125 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
4126 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");