1 // ignore-tidy-filelength
2 //! "Late resolution" is the pass that resolves most of names in a crate beside imports and macros.
3 //! It runs when the crate is fully expanded and its module structure is fully built.
4 //! So it just walks through the crate and resolves all the expressions, types, etc.
6 //! If you wonder why there's no `early.rs`, that's because it's split into three files -
7 //! `build_reduced_graph.rs`, `macros.rs` and `imports.rs`.
11 use crate::{path_names_to_string, BindingError, Finalize, LexicalScopeBinding};
12 use crate::{Module, ModuleOrUniformRoot, NameBinding, ParentScope, PathResult};
13 use crate::{ResolutionError, Resolver, Segment, UseError};
15 use rustc_ast::ptr::P;
16 use rustc_ast::visit::{self, AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor};
18 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
19 use rustc_errors::DiagnosticId;
20 use rustc_hir::def::Namespace::{self, *};
21 use rustc_hir::def::{self, CtorKind, DefKind, LifetimeRes, PartialRes, PerNS};
22 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID};
23 use rustc_hir::{PrimTy, TraitCandidate};
24 use rustc_middle::middle::resolve_lifetime::Set1;
25 use rustc_middle::ty::DefIdTree;
26 use rustc_middle::{bug, span_bug};
27 use rustc_session::lint;
28 use rustc_span::symbol::{kw, sym, Ident, Symbol};
29 use rustc_span::{BytePos, Span};
30 use smallvec::{smallvec, SmallVec};
32 use rustc_span::source_map::{respan, Spanned};
33 use std::collections::{hash_map::Entry, BTreeSet};
34 use std::mem::{replace, take};
38 pub(crate) mod lifetimes;
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 binding_mode: BindingMode,
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 /// Denotes whether the context for the set of already bound bindings is a `Product`
83 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
84 /// See those functions for more information.
87 /// A product pattern context, e.g., `Variant(a, b)`.
89 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
93 /// Does this the item (from the item rib scope) allow generic parameters?
94 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
95 pub(crate) enum HasGenericParams {
100 impl HasGenericParams {
101 fn force_yes_if(self, b: bool) -> Self {
102 if b { Self::Yes } else { self }
106 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
107 pub(crate) enum ConstantItemKind {
112 /// The rib kind restricts certain accesses,
113 /// e.g. to a `Res::Local` of an outer item.
114 #[derive(Copy, Clone, Debug)]
115 pub(crate) enum RibKind<'a> {
116 /// No restriction needs to be applied.
119 /// We passed through an impl or trait and are now in one of its
120 /// methods or associated types. Allow references to ty params that impl or trait
121 /// binds. Disallow any other upvars (including other ty params that are
125 /// We passed through a closure. Disallow labels.
126 ClosureOrAsyncRibKind,
128 /// We passed through a function definition. Disallow upvars.
129 /// Permit only those const parameters that are specified in the function's generics.
132 /// We passed through an item scope. Disallow upvars.
133 ItemRibKind(HasGenericParams),
135 /// We're in a constant item. Can't refer to dynamic stuff.
137 /// The item may reference generic parameters in trivial constant expressions.
138 /// All other constants aren't allowed to use generic params at all.
139 ConstantItemRibKind(HasGenericParams, Option<(Ident, ConstantItemKind)>),
141 /// We passed through a module.
142 ModuleRibKind(Module<'a>),
144 /// We passed through a `macro_rules!` statement
145 MacroDefinition(DefId),
147 /// All bindings in this rib are generic parameters that can't be used
148 /// from the default of a generic parameter because they're not declared
149 /// before said generic parameter. Also see the `visit_generics` override.
150 ForwardGenericParamBanRibKind,
152 /// We are inside of the type of a const parameter. Can't refer to any
156 /// We are inside a `sym` inline assembly operand. Can only refer to
162 /// Whether this rib kind contains generic parameters, as opposed to local
164 pub(crate) fn contains_params(&self) -> bool {
167 | ClosureOrAsyncRibKind
169 | ConstantItemRibKind(..)
172 | ConstParamTyRibKind
173 | InlineAsmSymRibKind => false,
174 AssocItemRibKind | ItemRibKind(_) | ForwardGenericParamBanRibKind => true,
178 /// This rib forbids referring to labels defined in upwards ribs.
179 fn is_label_barrier(self) -> bool {
181 NormalRibKind | MacroDefinition(..) => false,
184 | ClosureOrAsyncRibKind
187 | ConstantItemRibKind(..)
189 | ForwardGenericParamBanRibKind
190 | ConstParamTyRibKind
191 | InlineAsmSymRibKind => true,
196 /// A single local scope.
198 /// A rib represents a scope names can live in. Note that these appear in many places, not just
199 /// around braces. At any place where the list of accessible names (of the given namespace)
200 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
201 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
204 /// Different [rib kinds](enum@RibKind) are transparent for different names.
206 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
207 /// resolving, the name is looked up from inside out.
209 pub(crate) struct Rib<'a, R = Res> {
210 pub bindings: IdentMap<R>,
211 pub kind: RibKind<'a>,
214 impl<'a, R> Rib<'a, R> {
215 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
216 Rib { bindings: Default::default(), kind }
220 #[derive(Clone, Copy, Debug)]
221 enum LifetimeUseSet {
222 One { use_span: Span, use_ctxt: visit::LifetimeCtxt },
226 #[derive(Copy, Clone, Debug)]
227 enum LifetimeRibKind {
228 /// This rib acts as a barrier to forbid reference to lifetimes of a parent item.
231 /// This rib declares generic parameters.
232 Generics { binder: NodeId, span: Span, kind: LifetimeBinderKind },
234 /// FIXME(const_generics): This patches over an ICE caused by non-'static lifetimes in const
235 /// generics. We are disallowing this until we can decide on how we want to handle non-'static
236 /// lifetimes in const generics. See issue #74052 for discussion.
239 /// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`.
240 /// This function will emit an error if `generic_const_exprs` is not enabled, the body identified by
241 /// `body_id` is an anonymous constant and `lifetime_ref` is non-static.
244 /// Create a new anonymous lifetime parameter and reference it.
246 /// If `report_in_path`, report an error when encountering lifetime elision in a path:
248 /// struct Foo<'a> { x: &'a () }
249 /// async fn foo(x: Foo) {}
252 /// Note: the error should not trigger when the elided lifetime is in a pattern or
253 /// expression-position path:
255 /// struct Foo<'a> { x: &'a () }
256 /// async fn foo(Foo { x: _ }: Foo<'_>) {}
258 AnonymousCreateParameter { binder: NodeId, report_in_path: bool },
260 /// Give a hard error when either `&` or `'_` is written. Used to
261 /// rule out things like `where T: Foo<'_>`. Does not imply an
262 /// error on default object bounds (e.g., `Box<dyn Foo>`).
263 AnonymousReportError,
265 /// Pass responsibility to `resolve_lifetime` code for all cases.
266 AnonymousPassThrough(NodeId),
268 /// Replace all anonymous lifetimes by provided lifetime.
271 /// Signal we cannot find which should be the anonymous lifetime.
275 #[derive(Copy, Clone, Debug)]
276 enum LifetimeBinderKind {
286 impl LifetimeBinderKind {
287 fn descr(self) -> &'static str {
288 use LifetimeBinderKind::*;
290 BareFnType => "type",
291 PolyTrait => "bound",
292 WhereBound => "bound",
294 ImplBlock => "impl block",
295 Function => "function",
296 Closure => "closure",
303 kind: LifetimeRibKind,
304 // We need to preserve insertion order for async fns.
305 bindings: FxIndexMap<Ident, (NodeId, LifetimeRes)>,
309 fn new(kind: LifetimeRibKind) -> LifetimeRib {
310 LifetimeRib { bindings: Default::default(), kind }
314 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
315 pub(crate) enum AliasPossibility {
320 #[derive(Copy, Clone, Debug)]
321 pub(crate) enum PathSource<'a> {
322 // Type paths `Path`.
324 // Trait paths in bounds or impls.
325 Trait(AliasPossibility),
326 // Expression paths `path`, with optional parent context.
327 Expr(Option<&'a Expr>),
328 // Paths in path patterns `Path`.
330 // Paths in struct expressions and patterns `Path { .. }`.
332 // Paths in tuple struct patterns `Path(..)`.
333 TupleStruct(Span, &'a [Span]),
334 // `m::A::B` in `<T as m::A>::B::C`.
335 TraitItem(Namespace),
338 impl<'a> PathSource<'a> {
339 fn namespace(self) -> Namespace {
341 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
342 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
343 PathSource::TraitItem(ns) => ns,
347 fn defer_to_typeck(self) -> bool {
350 | PathSource::Expr(..)
353 | PathSource::TupleStruct(..) => true,
354 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
358 fn descr_expected(self) -> &'static str {
360 PathSource::Type => "type",
361 PathSource::Trait(_) => "trait",
362 PathSource::Pat => "unit struct, unit variant or constant",
363 PathSource::Struct => "struct, variant or union type",
364 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
365 PathSource::TraitItem(ns) => match ns {
366 TypeNS => "associated type",
367 ValueNS => "method or associated constant",
368 MacroNS => bug!("associated macro"),
370 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
371 // "function" here means "anything callable" rather than `DefKind::Fn`,
372 // this is not precise but usually more helpful than just "value".
373 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
374 // the case of `::some_crate()`
375 ExprKind::Path(_, path)
376 if path.segments.len() == 2
377 && path.segments[0].ident.name == kw::PathRoot =>
381 ExprKind::Path(_, path) => {
382 let mut msg = "function";
383 if let Some(segment) = path.segments.iter().last() {
384 if let Some(c) = segment.ident.to_string().chars().next() {
385 if c.is_uppercase() {
386 msg = "function, tuple struct or tuple variant";
399 fn is_call(self) -> bool {
400 matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
403 pub(crate) fn is_expected(self, res: Res) -> bool {
405 PathSource::Type => matches!(
412 | DefKind::TraitAlias
417 | DefKind::ForeignTy,
422 PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
423 PathSource::Trait(AliasPossibility::Maybe) => {
424 matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
426 PathSource::Expr(..) => matches!(
429 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
434 | DefKind::AssocConst
435 | DefKind::ConstParam,
441 res.expected_in_unit_struct_pat()
442 || matches!(res, Res::Def(DefKind::Const | DefKind::AssocConst, _))
444 PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
445 PathSource::Struct => matches!(
454 ) | Res::SelfTy { .. }
456 PathSource::TraitItem(ns) => match res {
457 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
458 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
464 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
465 use rustc_errors::error_code;
466 match (self, has_unexpected_resolution) {
467 (PathSource::Trait(_), true) => error_code!(E0404),
468 (PathSource::Trait(_), false) => error_code!(E0405),
469 (PathSource::Type, true) => error_code!(E0573),
470 (PathSource::Type, false) => error_code!(E0412),
471 (PathSource::Struct, true) => error_code!(E0574),
472 (PathSource::Struct, false) => error_code!(E0422),
473 (PathSource::Expr(..), true) => error_code!(E0423),
474 (PathSource::Expr(..), false) => error_code!(E0425),
475 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
476 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
477 (PathSource::TraitItem(..), true) => error_code!(E0575),
478 (PathSource::TraitItem(..), false) => error_code!(E0576),
484 struct DiagnosticMetadata<'ast> {
485 /// The current trait's associated items' ident, used for diagnostic suggestions.
486 current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
488 /// The current self type if inside an impl (used for better errors).
489 current_self_type: Option<Ty>,
491 /// The current self item if inside an ADT (used for better errors).
492 current_self_item: Option<NodeId>,
494 /// The current trait (used to suggest).
495 current_item: Option<&'ast Item>,
497 /// When processing generics and encountering a type not found, suggest introducing a type
499 currently_processing_generics: bool,
501 /// The current enclosing (non-closure) function (used for better errors).
502 current_function: Option<(FnKind<'ast>, Span)>,
504 /// A list of labels as of yet unused. Labels will be removed from this map when
505 /// they are used (in a `break` or `continue` statement)
506 unused_labels: FxHashMap<NodeId, Span>,
508 /// Only used for better errors on `fn(): fn()`.
509 current_type_ascription: Vec<Span>,
511 /// Only used for better errors on `let x = { foo: bar };`.
512 /// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only
513 /// needed for cases where this parses as a correct type ascription.
514 current_block_could_be_bare_struct_literal: Option<Span>,
516 /// Only used for better errors on `let <pat>: <expr, not type>;`.
517 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
519 /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
520 in_if_condition: Option<&'ast Expr>,
522 /// If we are currently in a trait object definition. Used to point at the bounds when
523 /// encountering a struct or enum.
524 current_trait_object: Option<&'ast [ast::GenericBound]>,
526 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
527 current_where_predicate: Option<&'ast WherePredicate>,
529 current_type_path: Option<&'ast Ty>,
531 /// The current impl items (used to suggest).
532 current_impl_items: Option<&'ast [P<AssocItem>]>,
534 /// When processing impl trait
535 currently_processing_impl_trait: Option<(TraitRef, Ty)>,
537 /// Accumulate the errors due to missed lifetime elision,
538 /// and report them all at once for each function.
539 current_elision_failures: Vec<MissingLifetime>,
542 struct LateResolutionVisitor<'a, 'b, 'ast> {
543 r: &'b mut Resolver<'a>,
545 /// The module that represents the current item scope.
546 parent_scope: ParentScope<'a>,
548 /// The current set of local scopes for types and values.
549 /// FIXME #4948: Reuse ribs to avoid allocation.
550 ribs: PerNS<Vec<Rib<'a>>>,
552 /// The current set of local scopes, for labels.
553 label_ribs: Vec<Rib<'a, NodeId>>,
555 /// The current set of local scopes for lifetimes.
556 lifetime_ribs: Vec<LifetimeRib>,
558 /// We are looking for lifetimes in an elision context.
559 /// The set contains all the resolutions that we encountered so far.
560 /// They will be used to determine the correct lifetime for the fn return type.
561 /// The `LifetimeElisionCandidate` is used for diagnostics, to suggest introducing named
563 lifetime_elision_candidates: Option<FxIndexMap<LifetimeRes, LifetimeElisionCandidate>>,
565 /// The trait that the current context can refer to.
566 current_trait_ref: Option<(Module<'a>, TraitRef)>,
568 /// Fields used to add information to diagnostic errors.
569 diagnostic_metadata: Box<DiagnosticMetadata<'ast>>,
571 /// State used to know whether to ignore resolution errors for function bodies.
573 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
574 /// In most cases this will be `None`, in which case errors will always be reported.
575 /// If it is `true`, then it will be updated when entering a nested function or trait body.
578 /// Count the number of places a lifetime is used.
579 lifetime_uses: FxHashMap<LocalDefId, LifetimeUseSet>,
582 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
583 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
584 fn visit_attribute(&mut self, _: &'ast Attribute) {
585 // We do not want to resolve expressions that appear in attributes,
586 // as they do not correspond to actual code.
588 fn visit_item(&mut self, item: &'ast Item) {
589 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
590 // Always report errors in items we just entered.
591 let old_ignore = replace(&mut self.in_func_body, false);
592 self.with_lifetime_rib(LifetimeRibKind::Item, |this| this.resolve_item(item));
593 self.in_func_body = old_ignore;
594 self.diagnostic_metadata.current_item = prev;
596 fn visit_arm(&mut self, arm: &'ast Arm) {
597 self.resolve_arm(arm);
599 fn visit_block(&mut self, block: &'ast Block) {
600 self.resolve_block(block);
602 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
603 // We deal with repeat expressions explicitly in `resolve_expr`.
604 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
605 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
606 this.resolve_anon_const(constant, IsRepeatExpr::No);
610 fn visit_expr(&mut self, expr: &'ast Expr) {
611 self.resolve_expr(expr, None);
613 fn visit_local(&mut self, local: &'ast Local) {
614 let local_spans = match local.pat.kind {
615 // We check for this to avoid tuple struct fields.
616 PatKind::Wild => None,
619 local.ty.as_ref().map(|ty| ty.span),
620 local.kind.init().map(|init| init.span),
623 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
624 self.resolve_local(local);
625 self.diagnostic_metadata.current_let_binding = original;
627 fn visit_ty(&mut self, ty: &'ast Ty) {
628 let prev = self.diagnostic_metadata.current_trait_object;
629 let prev_ty = self.diagnostic_metadata.current_type_path;
631 TyKind::Rptr(None, _) => {
632 // Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
634 // This span will be used in case of elision failure.
635 let span = self.r.session.source_map().next_point(ty.span.shrink_to_lo());
636 self.resolve_elided_lifetime(ty.id, span);
637 visit::walk_ty(self, ty);
639 TyKind::Path(ref qself, ref path) => {
640 self.diagnostic_metadata.current_type_path = Some(ty);
641 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
643 // Check whether we should interpret this as a bare trait object.
645 && let Some(partial_res) = self.r.partial_res_map.get(&ty.id)
646 && partial_res.unresolved_segments() == 0
647 && let Res::Def(DefKind::Trait | DefKind::TraitAlias, _) = partial_res.base_res()
649 // This path is actually a bare trait object. In case of a bare `Fn`-trait
650 // object with anonymous lifetimes, we need this rib to correctly place the
651 // synthetic lifetimes.
652 let span = ty.span.shrink_to_lo().to(path.span.shrink_to_lo());
653 self.with_generic_param_rib(
656 LifetimeRibKind::Generics {
658 kind: LifetimeBinderKind::PolyTrait,
661 |this| this.visit_path(&path, ty.id),
664 visit::walk_ty(self, ty)
667 TyKind::ImplicitSelf => {
668 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
670 .resolve_ident_in_lexical_scope(
673 Some(Finalize::new(ty.id, ty.span)),
676 .map_or(Res::Err, |d| d.res());
677 self.r.record_partial_res(ty.id, PartialRes::new(res));
678 visit::walk_ty(self, ty)
680 TyKind::ImplTrait(..) => {
681 let candidates = self.lifetime_elision_candidates.take();
682 visit::walk_ty(self, ty);
683 self.lifetime_elision_candidates = candidates;
685 TyKind::TraitObject(ref bounds, ..) => {
686 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
687 visit::walk_ty(self, ty)
689 TyKind::BareFn(ref bare_fn) => {
690 let span = ty.span.shrink_to_lo().to(bare_fn.decl_span.shrink_to_lo());
691 self.with_generic_param_rib(
692 &bare_fn.generic_params,
694 LifetimeRibKind::Generics {
696 kind: LifetimeBinderKind::BareFnType,
700 this.visit_generic_params(&bare_fn.generic_params, false);
701 this.resolve_fn_signature(
705 // We don't need to deal with patterns in parameters, because
706 // they are not possible for foreign or bodiless functions.
707 bare_fn.decl.inputs.iter().map(|Param { ty, .. }| (None, &**ty)),
708 &bare_fn.decl.output,
713 _ => visit::walk_ty(self, ty),
715 self.diagnostic_metadata.current_trait_object = prev;
716 self.diagnostic_metadata.current_type_path = prev_ty;
718 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef, _: &'ast TraitBoundModifier) {
719 let span = tref.span.shrink_to_lo().to(tref.trait_ref.path.span.shrink_to_lo());
720 self.with_generic_param_rib(
721 &tref.bound_generic_params,
723 LifetimeRibKind::Generics {
724 binder: tref.trait_ref.ref_id,
725 kind: LifetimeBinderKind::PolyTrait,
729 this.visit_generic_params(&tref.bound_generic_params, false);
730 this.smart_resolve_path(
731 tref.trait_ref.ref_id,
733 &tref.trait_ref.path,
734 PathSource::Trait(AliasPossibility::Maybe),
736 this.visit_trait_ref(&tref.trait_ref);
740 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
741 match foreign_item.kind {
742 ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
743 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
744 this.with_generic_param_rib(
746 ItemRibKind(HasGenericParams::Yes),
747 LifetimeRibKind::Generics {
748 binder: foreign_item.id,
749 kind: LifetimeBinderKind::Item,
752 |this| visit::walk_foreign_item(this, foreign_item),
756 ForeignItemKind::Fn(box Fn { ref generics, .. }) => {
757 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
758 this.with_generic_param_rib(
760 ItemRibKind(HasGenericParams::Yes),
761 LifetimeRibKind::Generics {
762 binder: foreign_item.id,
763 kind: LifetimeBinderKind::Function,
766 |this| visit::walk_foreign_item(this, foreign_item),
770 ForeignItemKind::Static(..) => {
771 self.with_item_rib(|this| {
772 visit::walk_foreign_item(this, foreign_item);
775 ForeignItemKind::MacCall(..) => {
776 panic!("unexpanded macro in resolve!")
780 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, fn_id: NodeId) {
781 let rib_kind = match fn_kind {
782 // Bail if the function is foreign, and thus cannot validly have
783 // a body, or if there's no body for some other reason.
784 FnKind::Fn(FnCtxt::Foreign, _, sig, _, generics, _)
785 | FnKind::Fn(_, _, sig, _, generics, None) => {
786 self.visit_fn_header(&sig.header);
787 self.visit_generics(generics);
788 self.resolve_fn_signature(
792 sig.decl.inputs.iter().map(|Param { ty, .. }| (None, &**ty)),
797 FnKind::Fn(FnCtxt::Free, ..) => FnItemRibKind,
798 FnKind::Fn(FnCtxt::Assoc(_), ..) => NormalRibKind,
799 FnKind::Closure(..) => ClosureOrAsyncRibKind,
801 let previous_value = self.diagnostic_metadata.current_function;
802 if matches!(fn_kind, FnKind::Fn(..)) {
803 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
805 debug!("(resolving function) entering function");
807 // Create a value rib for the function.
808 self.with_rib(ValueNS, rib_kind, |this| {
809 // Create a label rib for the function.
810 this.with_label_rib(FnItemRibKind, |this| {
812 FnKind::Fn(_, _, sig, _, generics, body) => {
813 this.visit_generics(generics);
815 let declaration = &sig.decl;
816 let async_node_id = sig.header.asyncness.opt_return_id();
818 this.resolve_fn_signature(
821 declaration.has_self(),
825 .map(|Param { pat, ty, .. }| (Some(&**pat), &**ty)),
829 // Construct the list of in-scope lifetime parameters for async lowering.
830 // We include all lifetime parameters, either named or "Fresh".
831 // The order of those parameters does not matter, as long as it is
833 if let Some(async_node_id) = async_node_id {
834 let mut extra_lifetime_params = this
836 .extra_lifetime_params_map
839 .unwrap_or_default();
840 for rib in this.lifetime_ribs.iter().rev() {
841 extra_lifetime_params.extend(
844 .map(|(&ident, &(node_id, res))| (ident, node_id, res)),
847 LifetimeRibKind::Item => break,
848 LifetimeRibKind::AnonymousCreateParameter {
851 if let Some(earlier_fresh) =
852 this.r.extra_lifetime_params_map.get(&binder)
854 extra_lifetime_params.extend(earlier_fresh);
861 .extra_lifetime_params_map
862 .insert(async_node_id, extra_lifetime_params);
865 if let Some(body) = body {
866 // Ignore errors in function bodies if this is rustdoc
867 // Be sure not to set this until the function signature has been resolved.
868 let previous_state = replace(&mut this.in_func_body, true);
869 // Resolve the function body, potentially inside the body of an async closure
870 this.with_lifetime_rib(
871 LifetimeRibKind::AnonymousPassThrough(fn_id),
872 |this| this.visit_block(body),
875 debug!("(resolving function) leaving function");
876 this.in_func_body = previous_state;
879 FnKind::Closure(binder, declaration, body) => {
880 this.visit_closure_binder(binder);
882 this.with_lifetime_rib(
884 // We do not have any explicit generic lifetime parameter.
885 ClosureBinder::NotPresent => {
886 LifetimeRibKind::AnonymousCreateParameter {
888 report_in_path: false,
891 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
893 // Add each argument to the rib.
894 |this| this.resolve_params(&declaration.inputs),
896 this.with_lifetime_rib(
898 ClosureBinder::NotPresent => {
899 LifetimeRibKind::AnonymousPassThrough(fn_id)
901 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
903 |this| visit::walk_fn_ret_ty(this, &declaration.output),
906 // Ignore errors in function bodies if this is rustdoc
907 // Be sure not to set this until the function signature has been resolved.
908 let previous_state = replace(&mut this.in_func_body, true);
909 // Resolve the function body, potentially inside the body of an async closure
910 this.with_lifetime_rib(
911 LifetimeRibKind::AnonymousPassThrough(fn_id),
912 |this| this.visit_expr(body),
915 debug!("(resolving function) leaving function");
916 this.in_func_body = previous_state;
921 self.diagnostic_metadata.current_function = previous_value;
923 fn visit_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
924 self.resolve_lifetime(lifetime, use_ctxt)
927 fn visit_generics(&mut self, generics: &'ast Generics) {
928 self.visit_generic_params(
930 self.diagnostic_metadata.current_self_item.is_some(),
932 for p in &generics.where_clause.predicates {
933 self.visit_where_predicate(p);
937 fn visit_closure_binder(&mut self, b: &'ast ClosureBinder) {
939 ClosureBinder::NotPresent => {}
940 ClosureBinder::For { generic_params, .. } => {
941 self.visit_generic_params(
943 self.diagnostic_metadata.current_self_item.is_some(),
949 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
950 debug!("visit_generic_arg({:?})", arg);
951 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
953 GenericArg::Type(ref ty) => {
954 // We parse const arguments as path types as we cannot distinguish them during
955 // parsing. We try to resolve that ambiguity by attempting resolution the type
956 // namespace first, and if that fails we try again in the value namespace. If
957 // resolution in the value namespace succeeds, we have an generic const argument on
959 if let TyKind::Path(ref qself, ref path) = ty.kind {
960 // We cannot disambiguate multi-segment paths right now as that requires type
962 if path.segments.len() == 1 && path.segments[0].args.is_none() {
963 let mut check_ns = |ns| {
964 self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns)
967 if !check_ns(TypeNS) && check_ns(ValueNS) {
968 // This must be equivalent to `visit_anon_const`, but we cannot call it
969 // directly due to visitor lifetimes so we have to copy-paste some code.
971 // Note that we might not be inside of an repeat expression here,
972 // but considering that `IsRepeatExpr` is only relevant for
973 // non-trivial constants this is doesn't matter.
974 self.with_constant_rib(
976 HasGenericParams::Yes,
979 this.smart_resolve_path(
983 PathSource::Expr(None),
986 if let Some(ref qself) = *qself {
987 this.visit_ty(&qself.ty);
989 this.visit_path(path, ty.id);
993 self.diagnostic_metadata.currently_processing_generics = prev;
1001 GenericArg::Lifetime(lt) => self.visit_lifetime(lt, visit::LifetimeCtxt::GenericArg),
1002 GenericArg::Const(ct) => self.visit_anon_const(ct),
1004 self.diagnostic_metadata.currently_processing_generics = prev;
1007 fn visit_assoc_constraint(&mut self, constraint: &'ast AssocConstraint) {
1008 self.visit_ident(constraint.ident);
1009 if let Some(ref gen_args) = constraint.gen_args {
1010 // Forbid anonymous lifetimes in GAT parameters until proper semantics are decided.
1011 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1012 this.visit_generic_args(gen_args.span(), gen_args)
1015 match constraint.kind {
1016 AssocConstraintKind::Equality { ref term } => match term {
1017 Term::Ty(ty) => self.visit_ty(ty),
1018 Term::Const(c) => self.visit_anon_const(c),
1020 AssocConstraintKind::Bound { ref bounds } => {
1021 walk_list!(self, visit_param_bound, bounds, BoundKind::Bound);
1026 fn visit_path_segment(&mut self, path_span: Span, path_segment: &'ast PathSegment) {
1027 if let Some(ref args) = path_segment.args {
1029 GenericArgs::AngleBracketed(..) => visit::walk_generic_args(self, path_span, args),
1030 GenericArgs::Parenthesized(p_args) => {
1031 // Probe the lifetime ribs to know how to behave.
1032 for rib in self.lifetime_ribs.iter().rev() {
1034 // We are inside a `PolyTraitRef`. The lifetimes are
1035 // to be intoduced in that (maybe implicit) `for<>` binder.
1036 LifetimeRibKind::Generics {
1038 kind: LifetimeBinderKind::PolyTrait,
1041 self.resolve_fn_signature(
1045 p_args.inputs.iter().map(|ty| (None, &**ty)),
1050 // We have nowhere to introduce generics. Code is malformed,
1051 // so use regular lifetime resolution to avoid spurious errors.
1052 LifetimeRibKind::Item | LifetimeRibKind::Generics { .. } => {
1053 visit::walk_generic_args(self, path_span, args);
1056 LifetimeRibKind::AnonymousPassThrough(..)
1057 | LifetimeRibKind::AnonymousCreateParameter { .. }
1058 | LifetimeRibKind::AnonymousReportError
1059 | LifetimeRibKind::Elided(_)
1060 | LifetimeRibKind::ElisionFailure
1061 | LifetimeRibKind::AnonConst
1062 | LifetimeRibKind::ConstGeneric => {}
1070 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
1071 debug!("visit_where_predicate {:?}", p);
1072 let previous_value =
1073 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
1074 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1075 if let WherePredicate::BoundPredicate(WhereBoundPredicate {
1078 ref bound_generic_params,
1079 span: predicate_span,
1083 let span = predicate_span.shrink_to_lo().to(bounded_ty.span.shrink_to_lo());
1084 this.with_generic_param_rib(
1085 &bound_generic_params,
1087 LifetimeRibKind::Generics {
1088 binder: bounded_ty.id,
1089 kind: LifetimeBinderKind::WhereBound,
1093 this.visit_generic_params(&bound_generic_params, false);
1094 this.visit_ty(bounded_ty);
1095 for bound in bounds {
1096 this.visit_param_bound(bound, BoundKind::Bound)
1101 visit::walk_where_predicate(this, p);
1104 self.diagnostic_metadata.current_where_predicate = previous_value;
1107 fn visit_inline_asm(&mut self, asm: &'ast InlineAsm) {
1108 for (op, _) in &asm.operands {
1110 InlineAsmOperand::In { expr, .. }
1111 | InlineAsmOperand::Out { expr: Some(expr), .. }
1112 | InlineAsmOperand::InOut { expr, .. } => self.visit_expr(expr),
1113 InlineAsmOperand::Out { expr: None, .. } => {}
1114 InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
1115 self.visit_expr(in_expr);
1116 if let Some(out_expr) = out_expr {
1117 self.visit_expr(out_expr);
1120 InlineAsmOperand::Const { anon_const, .. } => {
1121 // Although this is `DefKind::AnonConst`, it is allowed to reference outer
1122 // generic parameters like an inline const.
1123 self.resolve_inline_const(anon_const);
1125 InlineAsmOperand::Sym { sym } => self.visit_inline_asm_sym(sym),
1130 fn visit_inline_asm_sym(&mut self, sym: &'ast InlineAsmSym) {
1131 // This is similar to the code for AnonConst.
1132 self.with_rib(ValueNS, InlineAsmSymRibKind, |this| {
1133 this.with_rib(TypeNS, InlineAsmSymRibKind, |this| {
1134 this.with_label_rib(InlineAsmSymRibKind, |this| {
1135 this.smart_resolve_path(
1139 PathSource::Expr(None),
1141 visit::walk_inline_asm_sym(this, sym);
1148 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
1149 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
1150 // During late resolution we only track the module component of the parent scope,
1151 // although it may be useful to track other components as well for diagnostics.
1152 let graph_root = resolver.graph_root;
1153 let parent_scope = ParentScope::module(graph_root, resolver);
1154 let start_rib_kind = ModuleRibKind(graph_root);
1155 LateResolutionVisitor {
1159 value_ns: vec![Rib::new(start_rib_kind)],
1160 type_ns: vec![Rib::new(start_rib_kind)],
1161 macro_ns: vec![Rib::new(start_rib_kind)],
1163 label_ribs: Vec::new(),
1164 lifetime_ribs: Vec::new(),
1165 lifetime_elision_candidates: None,
1166 current_trait_ref: None,
1167 diagnostic_metadata: Box::new(DiagnosticMetadata::default()),
1168 // errors at module scope should always be reported
1169 in_func_body: false,
1170 lifetime_uses: Default::default(),
1174 fn maybe_resolve_ident_in_lexical_scope(
1178 ) -> Option<LexicalScopeBinding<'a>> {
1179 self.r.resolve_ident_in_lexical_scope(
1189 fn resolve_ident_in_lexical_scope(
1193 finalize: Option<Finalize>,
1194 ignore_binding: Option<&'a NameBinding<'a>>,
1195 ) -> Option<LexicalScopeBinding<'a>> {
1196 self.r.resolve_ident_in_lexical_scope(
1209 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1210 finalize: Option<Finalize>,
1211 ) -> PathResult<'a> {
1212 self.r.resolve_path_with_ribs(
1224 // We maintain a list of value ribs and type ribs.
1226 // Simultaneously, we keep track of the current position in the module
1227 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
1228 // the value or type namespaces, we first look through all the ribs and
1229 // then query the module graph. When we resolve a name in the module
1230 // namespace, we can skip all the ribs (since nested modules are not
1231 // allowed within blocks in Rust) and jump straight to the current module
1234 // Named implementations are handled separately. When we find a method
1235 // call, we consult the module node to find all of the implementations in
1236 // scope. This information is lazily cached in the module node. We then
1237 // generate a fake "implementation scope" containing all the
1238 // implementations thus found, for compatibility with old resolve pass.
1240 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
1245 work: impl FnOnce(&mut Self) -> T,
1247 self.ribs[ns].push(Rib::new(kind));
1248 let ret = work(self);
1249 self.ribs[ns].pop();
1253 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
1254 if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
1255 // Move down in the graph.
1256 let orig_module = replace(&mut self.parent_scope.module, module);
1257 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
1258 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
1260 this.parent_scope.module = orig_module;
1269 fn visit_generic_params(&mut self, params: &'ast [GenericParam], add_self_upper: bool) {
1270 // For type parameter defaults, we have to ban access
1271 // to following type parameters, as the InternalSubsts can only
1272 // provide previous type parameters as they're built. We
1273 // put all the parameters on the ban list and then remove
1274 // them one by one as they are processed and become available.
1275 let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1276 let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1277 for param in params.iter() {
1279 GenericParamKind::Type { .. } => {
1282 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1284 GenericParamKind::Const { .. } => {
1285 forward_const_ban_rib
1287 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1289 GenericParamKind::Lifetime => {}
1293 // rust-lang/rust#61631: The type `Self` is essentially
1294 // another type parameter. For ADTs, we consider it
1295 // well-defined only after all of the ADT type parameters have
1296 // been provided. Therefore, we do not allow use of `Self`
1297 // anywhere in ADT type parameter defaults.
1299 // (We however cannot ban `Self` for defaults on *all* generic
1300 // lists; e.g. trait generics can usefully refer to `Self`,
1301 // such as in the case of `trait Add<Rhs = Self>`.)
1303 // (`Some` if + only if we are in ADT's generics.)
1304 forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
1307 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1308 for param in params {
1310 GenericParamKind::Lifetime => {
1311 for bound in ¶m.bounds {
1312 this.visit_param_bound(bound, BoundKind::Bound);
1315 GenericParamKind::Type { ref default } => {
1316 for bound in ¶m.bounds {
1317 this.visit_param_bound(bound, BoundKind::Bound);
1320 if let Some(ref ty) = default {
1321 this.ribs[TypeNS].push(forward_ty_ban_rib);
1322 this.ribs[ValueNS].push(forward_const_ban_rib);
1324 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1325 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1328 // Allow all following defaults to refer to this type parameter.
1331 .remove(&Ident::with_dummy_span(param.ident.name));
1333 GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
1334 // Const parameters can't have param bounds.
1335 assert!(param.bounds.is_empty());
1337 this.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
1338 this.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
1339 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1342 this.ribs[TypeNS].pop().unwrap();
1343 this.ribs[ValueNS].pop().unwrap();
1345 if let Some(ref expr) = default {
1346 this.ribs[TypeNS].push(forward_ty_ban_rib);
1347 this.ribs[ValueNS].push(forward_const_ban_rib);
1348 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1349 this.resolve_anon_const(expr, IsRepeatExpr::No)
1351 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1352 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1355 // Allow all following defaults to refer to this const parameter.
1356 forward_const_ban_rib
1358 .remove(&Ident::with_dummy_span(param.ident.name));
1365 #[tracing::instrument(level = "debug", skip(self, work))]
1366 fn with_lifetime_rib<T>(
1368 kind: LifetimeRibKind,
1369 work: impl FnOnce(&mut Self) -> T,
1371 self.lifetime_ribs.push(LifetimeRib::new(kind));
1372 let outer_elision_candidates = self.lifetime_elision_candidates.take();
1373 let ret = work(self);
1374 self.lifetime_elision_candidates = outer_elision_candidates;
1375 self.lifetime_ribs.pop();
1379 #[tracing::instrument(level = "debug", skip(self))]
1380 fn resolve_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
1381 let ident = lifetime.ident;
1383 if ident.name == kw::StaticLifetime {
1384 self.record_lifetime_res(
1386 LifetimeRes::Static,
1387 LifetimeElisionCandidate::Named,
1392 if ident.name == kw::UnderscoreLifetime {
1393 return self.resolve_anonymous_lifetime(lifetime, false);
1396 let mut indices = (0..self.lifetime_ribs.len()).rev();
1397 for i in &mut indices {
1398 let rib = &self.lifetime_ribs[i];
1399 let normalized_ident = ident.normalize_to_macros_2_0();
1400 if let Some(&(_, res)) = rib.bindings.get(&normalized_ident) {
1401 self.record_lifetime_res(lifetime.id, res, LifetimeElisionCandidate::Named);
1403 if let LifetimeRes::Param { param, .. } = res {
1404 match self.lifetime_uses.entry(param) {
1405 Entry::Vacant(v) => {
1406 debug!("First use of {:?} at {:?}", res, ident.span);
1411 .find_map(|rib| match rib.kind {
1412 // Do not suggest eliding a lifetime where an anonymous
1413 // lifetime would be illegal.
1414 LifetimeRibKind::Item
1415 | LifetimeRibKind::AnonymousReportError
1416 | LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many),
1417 // An anonymous lifetime is legal here, go ahead.
1418 LifetimeRibKind::AnonymousPassThrough(_)
1419 | LifetimeRibKind::AnonymousCreateParameter { .. } => {
1420 Some(LifetimeUseSet::One { use_span: ident.span, use_ctxt })
1422 // Only report if eliding the lifetime would have the same
1424 LifetimeRibKind::Elided(r) => Some(if res == r {
1425 LifetimeUseSet::One { use_span: ident.span, use_ctxt }
1427 LifetimeUseSet::Many
1429 LifetimeRibKind::Generics { .. }
1430 | LifetimeRibKind::ConstGeneric
1431 | LifetimeRibKind::AnonConst => None,
1433 .unwrap_or(LifetimeUseSet::Many);
1434 debug!(?use_ctxt, ?use_set);
1437 Entry::Occupied(mut o) => {
1438 debug!("Many uses of {:?} at {:?}", res, ident.span);
1439 *o.get_mut() = LifetimeUseSet::Many;
1447 LifetimeRibKind::Item => break,
1448 LifetimeRibKind::ConstGeneric => {
1449 self.emit_non_static_lt_in_const_generic_error(lifetime);
1450 self.record_lifetime_res(
1453 LifetimeElisionCandidate::Ignore,
1457 LifetimeRibKind::AnonConst => {
1458 self.maybe_emit_forbidden_non_static_lifetime_error(lifetime);
1459 self.record_lifetime_res(
1462 LifetimeElisionCandidate::Ignore,
1470 let mut outer_res = None;
1472 let rib = &self.lifetime_ribs[i];
1473 let normalized_ident = ident.normalize_to_macros_2_0();
1474 if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) {
1475 outer_res = Some(outer);
1480 self.emit_undeclared_lifetime_error(lifetime, outer_res);
1481 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, LifetimeElisionCandidate::Named);
1484 #[tracing::instrument(level = "debug", skip(self))]
1485 fn resolve_anonymous_lifetime(&mut self, lifetime: &Lifetime, elided: bool) {
1486 debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
1488 let missing_lifetime = MissingLifetime {
1490 span: lifetime.ident.span,
1492 MissingLifetimeKind::Ampersand
1494 MissingLifetimeKind::Underscore
1498 let elision_candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1499 for i in (0..self.lifetime_ribs.len()).rev() {
1500 let rib = &mut self.lifetime_ribs[i];
1503 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1504 let res = self.create_fresh_lifetime(lifetime.id, lifetime.ident, binder);
1505 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1508 LifetimeRibKind::AnonymousReportError => {
1509 let (msg, note) = if elided {
1511 "`&` without an explicit lifetime name cannot be used here",
1512 "explicit lifetime name needed here",
1515 ("`'_` cannot be used here", "`'_` is a reserved lifetime name")
1517 rustc_errors::struct_span_err!(
1519 lifetime.ident.span,
1524 .span_label(lifetime.ident.span, note)
1527 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1530 LifetimeRibKind::AnonymousPassThrough(node_id) => {
1531 self.record_lifetime_res(
1533 LifetimeRes::Anonymous { binder: node_id, elided },
1538 LifetimeRibKind::Elided(res) => {
1539 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1542 LifetimeRibKind::ElisionFailure => {
1543 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1544 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1547 LifetimeRibKind::Item => break,
1548 LifetimeRibKind::Generics { .. }
1549 | LifetimeRibKind::ConstGeneric
1550 | LifetimeRibKind::AnonConst => {}
1553 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1554 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1557 #[tracing::instrument(level = "debug", skip(self))]
1558 fn resolve_elided_lifetime(&mut self, anchor_id: NodeId, span: Span) {
1559 let id = self.r.next_node_id();
1560 let lt = Lifetime { id, ident: Ident::new(kw::UnderscoreLifetime, span) };
1562 self.record_lifetime_res(
1564 LifetimeRes::ElidedAnchor { start: id, end: NodeId::from_u32(id.as_u32() + 1) },
1565 LifetimeElisionCandidate::Ignore,
1567 self.resolve_anonymous_lifetime(<, true);
1570 #[tracing::instrument(level = "debug", skip(self))]
1571 fn create_fresh_lifetime(&mut self, id: NodeId, ident: Ident, binder: NodeId) -> LifetimeRes {
1572 debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
1573 debug!(?ident.span);
1575 // Leave the responsibility to create the `LocalDefId` to lowering.
1576 let param = self.r.next_node_id();
1577 let res = LifetimeRes::Fresh { param, binder };
1579 // Record the created lifetime parameter so lowering can pick it up and add it to HIR.
1581 .extra_lifetime_params_map
1583 .or_insert_with(Vec::new)
1584 .push((ident, param, res));
1588 #[tracing::instrument(level = "debug", skip(self))]
1589 fn resolve_elided_lifetimes_in_path(
1592 partial_res: PartialRes,
1594 source: PathSource<'_>,
1597 let proj_start = path.len() - partial_res.unresolved_segments();
1598 for (i, segment) in path.iter().enumerate() {
1599 if segment.has_lifetime_args {
1602 let Some(segment_id) = segment.id else {
1606 // Figure out if this is a type/trait segment,
1607 // which may need lifetime elision performed.
1608 let type_def_id = match partial_res.base_res() {
1609 Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => self.r.parent(def_id),
1610 Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => self.r.parent(def_id),
1611 Res::Def(DefKind::Struct, def_id)
1612 | Res::Def(DefKind::Union, def_id)
1613 | Res::Def(DefKind::Enum, def_id)
1614 | Res::Def(DefKind::TyAlias, def_id)
1615 | Res::Def(DefKind::Trait, def_id)
1616 if i + 1 == proj_start =>
1623 let expected_lifetimes = self.r.item_generics_num_lifetimes(type_def_id);
1624 if expected_lifetimes == 0 {
1628 let missing = match source {
1629 PathSource::Trait(..) | PathSource::TraitItem(..) | PathSource::Type => true,
1630 PathSource::Expr(..)
1632 | PathSource::Struct
1633 | PathSource::TupleStruct(..) => false,
1636 let elided_lifetime_span = if segment.has_generic_args {
1637 // If there are brackets, but not generic arguments, then use the opening bracket
1638 segment.args_span.with_hi(segment.args_span.lo() + BytePos(1))
1640 // If there are no brackets, use the identifier span.
1641 // HACK: we use find_ancestor_inside to properly suggest elided spans in paths
1642 // originating from macros, since the segment's span might be from a macro arg.
1643 segment.ident.span.find_ancestor_inside(path_span).unwrap_or(path_span)
1645 let ident = Ident::new(kw::UnderscoreLifetime, elided_lifetime_span);
1647 let node_ids = self.r.next_node_ids(expected_lifetimes);
1648 self.record_lifetime_res(
1650 LifetimeRes::ElidedAnchor { start: node_ids.start, end: node_ids.end },
1651 LifetimeElisionCandidate::Ignore,
1655 // Do not create a parameter for patterns and expressions.
1656 for rib in self.lifetime_ribs.iter().rev() {
1658 LifetimeRibKind::AnonymousPassThrough(binder) => {
1659 let res = LifetimeRes::Anonymous { binder, elided: true };
1660 for id in node_ids {
1661 self.record_lifetime_res(id, res, LifetimeElisionCandidate::Named);
1665 // `LifetimeRes::Error`, which would usually be used in the case of
1666 // `ReportError`, is unsuitable here, as we don't emit an error yet. Instead,
1667 // we simply resolve to an implicit lifetime, which will be checked later, at
1668 // which point a suitable error will be emitted.
1669 LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
1670 // FIXME(cjgillot) This resolution is wrong, but this does not matter
1671 // since these cases are erroneous anyway. Lifetime resolution should
1672 // emit a "missing lifetime specifier" diagnostic.
1674 LifetimeRes::Anonymous { binder: DUMMY_NODE_ID, elided: true };
1675 for id in node_ids {
1676 self.record_lifetime_res(id, res, LifetimeElisionCandidate::Named);
1680 LifetimeRibKind::AnonymousCreateParameter { .. }
1681 | LifetimeRibKind::Elided(_)
1682 | LifetimeRibKind::ElisionFailure
1683 | LifetimeRibKind::Generics { .. }
1684 | LifetimeRibKind::ConstGeneric
1685 | LifetimeRibKind::AnonConst => {}
1691 let missing_lifetime = MissingLifetime {
1693 span: elided_lifetime_span,
1694 kind: if segment.has_generic_args {
1695 MissingLifetimeKind::Comma
1697 MissingLifetimeKind::Brackets
1699 count: expected_lifetimes,
1701 let mut should_lint = true;
1702 for rib in self.lifetime_ribs.iter().rev() {
1704 // In create-parameter mode we error here because we don't want to support
1705 // deprecated impl elision in new features like impl elision and `async fn`,
1706 // both of which work using the `CreateParameter` mode:
1708 // impl Foo for std::cell::Ref<u32> // note lack of '_
1709 // async fn foo(_: std::cell::Ref<u32>) { ... }
1710 LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. } => {
1711 let sess = self.r.session;
1712 let mut err = rustc_errors::struct_span_err!(
1716 "implicit elided lifetime not allowed here"
1718 rustc_errors::add_elided_lifetime_in_path_suggestion(
1723 !segment.has_generic_args,
1724 elided_lifetime_span,
1726 err.note("assuming a `'static` lifetime...");
1728 should_lint = false;
1730 for id in node_ids {
1731 self.record_lifetime_res(
1734 LifetimeElisionCandidate::Named,
1739 // Do not create a parameter for patterns and expressions.
1740 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1741 // Group all suggestions into the first record.
1742 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1743 for id in node_ids {
1744 let res = self.create_fresh_lifetime(id, ident, binder);
1745 self.record_lifetime_res(
1748 replace(&mut candidate, LifetimeElisionCandidate::Named),
1753 // `PassThrough` is the normal case.
1754 LifetimeRibKind::AnonymousPassThrough(binder) => {
1755 let res = LifetimeRes::Anonymous { binder, elided: true };
1756 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1757 for id in node_ids {
1758 self.record_lifetime_res(
1761 replace(&mut candidate, LifetimeElisionCandidate::Ignore),
1766 LifetimeRibKind::Elided(res) => {
1767 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1768 for id in node_ids {
1769 self.record_lifetime_res(
1772 replace(&mut candidate, LifetimeElisionCandidate::Ignore),
1777 LifetimeRibKind::ElisionFailure => {
1778 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1779 for id in node_ids {
1780 self.record_lifetime_res(
1783 LifetimeElisionCandidate::Ignore,
1788 // `LifetimeRes::Error`, which would usually be used in the case of
1789 // `ReportError`, is unsuitable here, as we don't emit an error yet. Instead,
1790 // we simply resolve to an implicit lifetime, which will be checked later, at
1791 // which point a suitable error will be emitted.
1792 LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
1793 for id in node_ids {
1794 self.record_lifetime_res(
1797 LifetimeElisionCandidate::Ignore,
1800 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1803 LifetimeRibKind::Generics { .. }
1804 | LifetimeRibKind::ConstGeneric
1805 | LifetimeRibKind::AnonConst => {}
1810 self.r.lint_buffer.buffer_lint_with_diagnostic(
1811 lint::builtin::ELIDED_LIFETIMES_IN_PATHS,
1813 elided_lifetime_span,
1814 "hidden lifetime parameters in types are deprecated",
1815 lint::BuiltinLintDiagnostics::ElidedLifetimesInPaths(
1818 !segment.has_generic_args,
1819 elided_lifetime_span,
1826 #[tracing::instrument(level = "debug", skip(self))]
1827 fn record_lifetime_res(
1831 candidate: LifetimeElisionCandidate,
1833 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1835 "lifetime {:?} resolved multiple times ({:?} before, {:?} now)",
1840 LifetimeRes::Param { .. }
1841 | LifetimeRes::Fresh { .. }
1842 | LifetimeRes::Anonymous { .. }
1843 | LifetimeRes::Static => {
1844 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
1845 candidates.insert(res, candidate);
1848 LifetimeRes::Error | LifetimeRes::ElidedAnchor { .. } => {}
1852 #[tracing::instrument(level = "debug", skip(self))]
1853 fn record_lifetime_param(&mut self, id: NodeId, res: LifetimeRes) {
1854 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1856 "lifetime parameter {:?} resolved multiple times ({:?} before, {:?} now)",
1862 /// Perform resolution of a function signature, accounting for lifetime elision.
1863 #[tracing::instrument(level = "debug", skip(self, inputs))]
1864 fn resolve_fn_signature(
1867 async_node_id: Option<NodeId>,
1869 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)> + Clone,
1870 output_ty: &'ast FnRetTy,
1872 // Add each argument to the rib.
1873 let parameter_rib = LifetimeRibKind::AnonymousCreateParameter {
1875 report_in_path: async_node_id.is_some(),
1877 let elision_lifetime =
1878 self.with_lifetime_rib(parameter_rib, |this| this.resolve_fn_params(has_self, inputs));
1879 debug!(?elision_lifetime);
1881 let outer_failures = take(&mut self.diagnostic_metadata.current_elision_failures);
1882 let output_rib = if let Ok(res) = elision_lifetime.as_ref() {
1883 LifetimeRibKind::Elided(*res)
1885 LifetimeRibKind::ElisionFailure
1887 self.with_lifetime_rib(output_rib, |this| visit::walk_fn_ret_ty(this, &output_ty));
1888 let elision_failures =
1889 replace(&mut self.diagnostic_metadata.current_elision_failures, outer_failures);
1890 if !elision_failures.is_empty() {
1891 let Err(failure_info) = elision_lifetime else { bug!() };
1892 self.report_missing_lifetime_specifiers(elision_failures, Some(failure_info));
1896 /// Resolve inside function parameters and parameter types.
1897 /// Returns the lifetime for elision in fn return type,
1898 /// or diagnostic information in case of elision failure.
1899 fn resolve_fn_params(
1902 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)>,
1903 ) -> Result<LifetimeRes, (Vec<MissingLifetime>, Vec<ElisionFnParameter>)> {
1904 let outer_candidates =
1905 replace(&mut self.lifetime_elision_candidates, Some(Default::default()));
1907 let mut elision_lifetime = None;
1908 let mut lifetime_count = 0;
1909 let mut parameter_info = Vec::new();
1911 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1912 for (index, (pat, ty)) in inputs.enumerate() {
1914 if let Some(pat) = pat {
1915 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1919 if let Some(ref candidates) = self.lifetime_elision_candidates {
1920 let new_count = candidates.len();
1921 let local_count = new_count - lifetime_count;
1922 if local_count != 0 {
1923 parameter_info.push(ElisionFnParameter {
1925 ident: if let Some(pat) = pat && let PatKind::Ident(_, ident, _) = pat.kind {
1930 lifetime_count: local_count,
1934 lifetime_count = new_count;
1937 // Handle `self` specially.
1938 if index == 0 && has_self {
1939 let self_lifetime = self.find_lifetime_for_self(ty);
1940 if let Set1::One(lifetime) = self_lifetime {
1941 elision_lifetime = Some(lifetime);
1942 self.lifetime_elision_candidates = None;
1944 self.lifetime_elision_candidates = Some(Default::default());
1948 debug!("(resolving function / closure) recorded parameter");
1951 let all_candidates = replace(&mut self.lifetime_elision_candidates, outer_candidates);
1952 debug!(?all_candidates);
1954 if let Some(res) = elision_lifetime {
1958 // We do not have a `self` candidate, look at the full list.
1959 let all_candidates = all_candidates.unwrap();
1960 if all_candidates.len() == 1 {
1961 Ok(*all_candidates.first().unwrap().0)
1963 let all_candidates = all_candidates
1965 .filter_map(|(_, candidate)| match candidate {
1966 LifetimeElisionCandidate::Ignore | LifetimeElisionCandidate::Named => None,
1967 LifetimeElisionCandidate::Missing(missing) => Some(missing),
1970 Err((all_candidates, parameter_info))
1974 /// List all the lifetimes that appear in the provided type.
1975 fn find_lifetime_for_self(&self, ty: &'ast Ty) -> Set1<LifetimeRes> {
1976 struct SelfVisitor<'r, 'a> {
1977 r: &'r Resolver<'a>,
1978 impl_self: Option<Res>,
1979 lifetime: Set1<LifetimeRes>,
1982 impl SelfVisitor<'_, '_> {
1983 // Look for `self: &'a Self` - also desugared from `&'a self`,
1984 // and if that matches, use it for elision and return early.
1985 fn is_self_ty(&self, ty: &Ty) -> bool {
1987 TyKind::ImplicitSelf => true,
1988 TyKind::Path(None, _) => {
1989 let path_res = self.r.partial_res_map[&ty.id].base_res();
1990 if let Res::SelfTy { .. } = path_res {
1993 Some(path_res) == self.impl_self
2000 impl<'a> Visitor<'a> for SelfVisitor<'_, '_> {
2001 fn visit_ty(&mut self, ty: &'a Ty) {
2002 trace!("SelfVisitor considering ty={:?}", ty);
2003 if let TyKind::Rptr(lt, ref mt) = ty.kind && self.is_self_ty(&mt.ty) {
2004 let lt_id = if let Some(lt) = lt {
2007 let res = self.r.lifetimes_res_map[&ty.id];
2008 let LifetimeRes::ElidedAnchor { start, .. } = res else { bug!() };
2011 let lt_res = self.r.lifetimes_res_map[<_id];
2012 trace!("SelfVisitor inserting res={:?}", lt_res);
2013 self.lifetime.insert(lt_res);
2015 visit::walk_ty(self, ty)
2019 let impl_self = self
2020 .diagnostic_metadata
2024 if let TyKind::Path(None, _) = ty.kind {
2025 self.r.partial_res_map.get(&ty.id)
2030 .map(|res| res.base_res())
2032 // Permit the types that unambiguously always
2033 // result in the same type constructor being used
2034 // (it can't differ between `Self` and `self`).
2037 Res::Def(DefKind::Struct | DefKind::Union | DefKind::Enum, _,) | Res::PrimTy(_)
2040 let mut visitor = SelfVisitor { r: self.r, impl_self, lifetime: Set1::Empty };
2041 visitor.visit_ty(ty);
2042 trace!("SelfVisitor found={:?}", visitor.lifetime);
2046 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
2047 /// label and reports an error if the label is not found or is unreachable.
2048 fn resolve_label(&mut self, mut label: Ident) -> Result<(NodeId, Span), ResolutionError<'a>> {
2049 let mut suggestion = None;
2051 for i in (0..self.label_ribs.len()).rev() {
2052 let rib = &self.label_ribs[i];
2054 if let MacroDefinition(def) = rib.kind {
2055 // If an invocation of this macro created `ident`, give up on `ident`
2056 // and switch to `ident`'s source from the macro definition.
2057 if def == self.r.macro_def(label.span.ctxt()) {
2058 label.span.remove_mark();
2062 let ident = label.normalize_to_macro_rules();
2063 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
2064 let definition_span = ident.span;
2065 return if self.is_label_valid_from_rib(i) {
2066 Ok((*id, definition_span))
2068 Err(ResolutionError::UnreachableLabel {
2076 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
2077 // the first such label that is encountered.
2078 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
2081 Err(ResolutionError::UndeclaredLabel { name: label.name, suggestion })
2084 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
2085 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
2086 let ribs = &self.label_ribs[rib_index + 1..];
2089 if rib.kind.is_label_barrier() {
2097 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
2098 debug!("resolve_adt");
2099 self.with_current_self_item(item, |this| {
2100 this.with_generic_param_rib(
2102 ItemRibKind(HasGenericParams::Yes),
2103 LifetimeRibKind::Generics {
2105 kind: LifetimeBinderKind::Item,
2106 span: generics.span,
2109 let item_def_id = this.r.local_def_id(item.id).to_def_id();
2111 Res::SelfTy { trait_: None, alias_to: Some((item_def_id, false)) },
2113 visit::walk_item(this, item);
2121 fn future_proof_import(&mut self, use_tree: &UseTree) {
2122 let segments = &use_tree.prefix.segments;
2123 if !segments.is_empty() {
2124 let ident = segments[0].ident;
2125 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
2129 let nss = match use_tree.kind {
2130 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
2133 let report_error = |this: &Self, ns| {
2134 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
2135 if this.should_report_errs() {
2138 .span_err(ident.span, &format!("imports cannot refer to {}", what));
2143 match self.maybe_resolve_ident_in_lexical_scope(ident, ns) {
2144 Some(LexicalScopeBinding::Res(..)) => {
2145 report_error(self, ns);
2147 Some(LexicalScopeBinding::Item(binding)) => {
2148 if let Some(LexicalScopeBinding::Res(..)) =
2149 self.resolve_ident_in_lexical_scope(ident, ns, None, Some(binding))
2151 report_error(self, ns);
2157 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
2158 for (use_tree, _) in use_trees {
2159 self.future_proof_import(use_tree);
2164 fn resolve_item(&mut self, item: &'ast Item) {
2165 let name = item.ident.name;
2166 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
2169 ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
2170 self.with_generic_param_rib(
2172 ItemRibKind(HasGenericParams::Yes),
2173 LifetimeRibKind::Generics {
2175 kind: LifetimeBinderKind::Item,
2176 span: generics.span,
2178 |this| visit::walk_item(this, item),
2182 ItemKind::Fn(box Fn { ref generics, .. }) => {
2183 self.with_generic_param_rib(
2185 ItemRibKind(HasGenericParams::Yes),
2186 LifetimeRibKind::Generics {
2188 kind: LifetimeBinderKind::Function,
2189 span: generics.span,
2191 |this| visit::walk_item(this, item),
2195 ItemKind::Enum(_, ref generics)
2196 | ItemKind::Struct(_, ref generics)
2197 | ItemKind::Union(_, ref generics) => {
2198 self.resolve_adt(item, generics);
2201 ItemKind::Impl(box Impl {
2205 items: ref impl_items,
2208 self.diagnostic_metadata.current_impl_items = Some(impl_items);
2209 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
2210 self.diagnostic_metadata.current_impl_items = None;
2213 ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
2214 // Create a new rib for the trait-wide type parameters.
2215 self.with_generic_param_rib(
2217 ItemRibKind(HasGenericParams::Yes),
2218 LifetimeRibKind::Generics {
2220 kind: LifetimeBinderKind::Item,
2221 span: generics.span,
2224 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2226 Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
2228 this.visit_generics(generics);
2229 walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);
2230 this.resolve_trait_items(items);
2237 ItemKind::TraitAlias(ref generics, ref bounds) => {
2238 // Create a new rib for the trait-wide type parameters.
2239 self.with_generic_param_rib(
2241 ItemRibKind(HasGenericParams::Yes),
2242 LifetimeRibKind::Generics {
2244 kind: LifetimeBinderKind::Item,
2245 span: generics.span,
2248 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2250 Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
2252 this.visit_generics(generics);
2253 walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
2260 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
2261 self.with_scope(item.id, |this| {
2262 visit::walk_item(this, item);
2266 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
2267 self.with_item_rib(|this| {
2268 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
2271 this.with_lifetime_rib(
2272 LifetimeRibKind::AnonymousPassThrough(item.id),
2274 if let Some(expr) = expr {
2275 let constant_item_kind = match item.kind {
2276 ItemKind::Const(..) => ConstantItemKind::Const,
2277 ItemKind::Static(..) => ConstantItemKind::Static,
2278 _ => unreachable!(),
2280 // We already forbid generic params because of the above item rib,
2281 // so it doesn't matter whether this is a trivial constant.
2282 this.with_constant_rib(
2284 HasGenericParams::Yes,
2285 Some((item.ident, constant_item_kind)),
2286 |this| this.visit_expr(expr),
2294 ItemKind::Use(ref use_tree) => {
2295 self.future_proof_import(use_tree);
2298 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => {
2299 // do nothing, these are just around to be encoded
2302 ItemKind::GlobalAsm(_) => {
2303 visit::walk_item(self, item);
2306 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
2310 fn with_generic_param_rib<'c, F>(
2312 params: &'c [GenericParam],
2314 lifetime_kind: LifetimeRibKind,
2317 F: FnOnce(&mut Self),
2319 debug!("with_generic_param_rib");
2320 let LifetimeRibKind::Generics { binder, span: generics_span, kind: generics_kind, .. }
2321 = lifetime_kind else { panic!() };
2323 let mut function_type_rib = Rib::new(kind);
2324 let mut function_value_rib = Rib::new(kind);
2325 let mut function_lifetime_rib = LifetimeRib::new(lifetime_kind);
2326 let mut seen_bindings = FxHashMap::default();
2327 // Store all seen lifetimes names from outer scopes.
2328 let mut seen_lifetimes = FxHashSet::default();
2330 // We also can't shadow bindings from the parent item
2331 if let AssocItemRibKind = kind {
2332 let mut add_bindings_for_ns = |ns| {
2333 let parent_rib = self.ribs[ns]
2335 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
2336 .expect("associated item outside of an item");
2338 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
2340 add_bindings_for_ns(ValueNS);
2341 add_bindings_for_ns(TypeNS);
2344 // Forbid shadowing lifetime bindings
2345 for rib in self.lifetime_ribs.iter().rev() {
2346 seen_lifetimes.extend(rib.bindings.iter().map(|(ident, _)| *ident));
2347 if let LifetimeRibKind::Item = rib.kind {
2352 for param in params {
2353 let ident = param.ident.normalize_to_macros_2_0();
2354 debug!("with_generic_param_rib: {}", param.id);
2356 if let GenericParamKind::Lifetime = param.kind
2357 && let Some(&original) = seen_lifetimes.get(&ident)
2359 diagnostics::signal_lifetime_shadowing(self.r.session, original, param.ident);
2360 // Record lifetime res, so lowering knows there is something fishy.
2361 self.record_lifetime_param(param.id, LifetimeRes::Error);
2365 match seen_bindings.entry(ident) {
2366 Entry::Occupied(entry) => {
2367 let span = *entry.get();
2368 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
2369 self.report_error(param.ident.span, err);
2370 if let GenericParamKind::Lifetime = param.kind {
2371 // Record lifetime res, so lowering knows there is something fishy.
2372 self.record_lifetime_param(param.id, LifetimeRes::Error);
2376 Entry::Vacant(entry) => {
2377 entry.insert(param.ident.span);
2381 if param.ident.name == kw::UnderscoreLifetime {
2382 rustc_errors::struct_span_err!(
2386 "`'_` cannot be used here"
2388 .span_label(param.ident.span, "`'_` is a reserved lifetime name")
2390 // Record lifetime res, so lowering knows there is something fishy.
2391 self.record_lifetime_param(param.id, LifetimeRes::Error);
2395 if param.ident.name == kw::StaticLifetime {
2396 rustc_errors::struct_span_err!(
2400 "invalid lifetime parameter name: `{}`",
2403 .span_label(param.ident.span, "'static is a reserved lifetime name")
2405 // Record lifetime res, so lowering knows there is something fishy.
2406 self.record_lifetime_param(param.id, LifetimeRes::Error);
2410 let def_id = self.r.local_def_id(param.id);
2412 // Plain insert (no renaming).
2413 let (rib, def_kind) = match param.kind {
2414 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
2415 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
2416 GenericParamKind::Lifetime => {
2417 let res = LifetimeRes::Param { param: def_id, binder };
2418 self.record_lifetime_param(param.id, res);
2419 function_lifetime_rib.bindings.insert(ident, (param.id, res));
2424 let res = match kind {
2425 ItemRibKind(..) | AssocItemRibKind => Res::Def(def_kind, def_id.to_def_id()),
2426 NormalRibKind => Res::Err,
2427 _ => span_bug!(param.ident.span, "Unexpected rib kind {:?}", kind),
2429 self.r.record_partial_res(param.id, PartialRes::new(res));
2430 rib.bindings.insert(ident, res);
2433 self.lifetime_ribs.push(function_lifetime_rib);
2434 self.ribs[ValueNS].push(function_value_rib);
2435 self.ribs[TypeNS].push(function_type_rib);
2439 self.ribs[TypeNS].pop();
2440 self.ribs[ValueNS].pop();
2441 let function_lifetime_rib = self.lifetime_ribs.pop().unwrap();
2443 // Do not account for the parameters we just bound for function lifetime elision.
2444 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
2445 for (_, res) in function_lifetime_rib.bindings.values() {
2446 candidates.remove(res);
2450 if let LifetimeBinderKind::BareFnType
2451 | LifetimeBinderKind::WhereBound
2452 | LifetimeBinderKind::Function
2453 | LifetimeBinderKind::ImplBlock = generics_kind
2455 self.maybe_report_lifetime_uses(generics_span, params)
2459 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
2460 self.label_ribs.push(Rib::new(kind));
2462 self.label_ribs.pop();
2465 fn with_item_rib(&mut self, f: impl FnOnce(&mut Self)) {
2466 let kind = ItemRibKind(HasGenericParams::No);
2467 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
2468 this.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
2472 // HACK(min_const_generics,const_evaluatable_unchecked): We
2473 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
2474 // with a future compat lint for now. We do this by adding an
2475 // additional special case for repeat expressions.
2477 // Note that we intentionally still forbid `[0; N + 1]` during
2478 // name resolution so that we don't extend the future
2479 // compat lint to new cases.
2480 #[instrument(level = "debug", skip(self, f))]
2481 fn with_constant_rib(
2483 is_repeat: IsRepeatExpr,
2484 may_use_generics: HasGenericParams,
2485 item: Option<(Ident, ConstantItemKind)>,
2486 f: impl FnOnce(&mut Self),
2488 self.with_rib(ValueNS, ConstantItemRibKind(may_use_generics, item), |this| {
2491 ConstantItemRibKind(
2492 may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes),
2496 this.with_label_rib(ConstantItemRibKind(may_use_generics, item), f);
2502 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
2503 // Handle nested impls (inside fn bodies)
2504 let previous_value =
2505 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
2506 let result = f(self);
2507 self.diagnostic_metadata.current_self_type = previous_value;
2511 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
2512 let previous_value =
2513 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
2514 let result = f(self);
2515 self.diagnostic_metadata.current_self_item = previous_value;
2519 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
2520 fn resolve_trait_items(&mut self, trait_items: &'ast [P<AssocItem>]) {
2521 let trait_assoc_items =
2522 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
2524 let walk_assoc_item =
2525 |this: &mut Self, generics: &Generics, kind, item: &'ast AssocItem| {
2526 this.with_generic_param_rib(
2529 LifetimeRibKind::Generics { binder: item.id, span: generics.span, kind },
2530 |this| visit::walk_assoc_item(this, item, AssocCtxt::Trait),
2534 for item in trait_items {
2536 AssocItemKind::Const(_, ty, default) => {
2538 // Only impose the restrictions of `ConstRibKind` for an
2539 // actual constant expression in a provided default.
2540 if let Some(expr) = default {
2541 // We allow arbitrary const expressions inside of associated consts,
2542 // even if they are potentially not const evaluatable.
2544 // Type parameters can already be used and as associated consts are
2545 // not used as part of the type system, this is far less surprising.
2546 self.with_lifetime_rib(
2547 LifetimeRibKind::AnonymousPassThrough(item.id),
2549 this.with_constant_rib(
2551 HasGenericParams::Yes,
2553 |this| this.visit_expr(expr),
2559 AssocItemKind::Fn(box Fn { generics, .. }) => {
2560 walk_assoc_item(self, generics, LifetimeBinderKind::Function, item);
2562 AssocItemKind::TyAlias(box TyAlias { generics, .. }) => self
2563 .with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2564 walk_assoc_item(this, generics, LifetimeBinderKind::Item, item)
2566 AssocItemKind::MacCall(_) => {
2567 panic!("unexpanded macro in resolve!")
2572 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
2575 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
2576 fn with_optional_trait_ref<T>(
2578 opt_trait_ref: Option<&TraitRef>,
2579 self_type: &'ast Ty,
2580 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
2582 let mut new_val = None;
2583 let mut new_id = None;
2584 if let Some(trait_ref) = opt_trait_ref {
2585 let path: Vec<_> = Segment::from_path(&trait_ref.path);
2586 self.diagnostic_metadata.currently_processing_impl_trait =
2587 Some((trait_ref.clone(), self_type.clone()));
2588 let res = self.smart_resolve_path_fragment(
2591 PathSource::Trait(AliasPossibility::No),
2592 Finalize::new(trait_ref.ref_id, trait_ref.path.span),
2594 self.diagnostic_metadata.currently_processing_impl_trait = None;
2595 if let Some(def_id) = res.base_res().opt_def_id() {
2596 new_id = Some(def_id);
2597 new_val = Some((self.r.expect_module(def_id), trait_ref.clone()));
2600 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
2601 let result = f(self, new_id);
2602 self.current_trait_ref = original_trait_ref;
2606 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
2607 let mut self_type_rib = Rib::new(NormalRibKind);
2609 // Plain insert (no renaming, since types are not currently hygienic)
2610 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
2611 self.ribs[ns].push(self_type_rib);
2613 self.ribs[ns].pop();
2616 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
2617 self.with_self_rib_ns(TypeNS, self_res, f)
2620 fn resolve_implementation(
2622 generics: &'ast Generics,
2623 opt_trait_reference: &'ast Option<TraitRef>,
2624 self_type: &'ast Ty,
2626 impl_items: &'ast [P<AssocItem>],
2628 debug!("resolve_implementation");
2629 // If applicable, create a rib for the type parameters.
2630 self.with_generic_param_rib(
2632 ItemRibKind(HasGenericParams::Yes),
2633 LifetimeRibKind::Generics {
2634 span: generics.span,
2636 kind: LifetimeBinderKind::ImplBlock,
2639 // Dummy self type for better errors if `Self` is used in the trait path.
2640 this.with_self_rib(Res::SelfTy { trait_: None, alias_to: None }, |this| {
2641 this.with_lifetime_rib(
2642 LifetimeRibKind::AnonymousCreateParameter {
2644 report_in_path: true
2647 // Resolve the trait reference, if necessary.
2648 this.with_optional_trait_ref(
2649 opt_trait_reference.as_ref(),
2652 let item_def_id = this.r.local_def_id(item_id);
2654 // Register the trait definitions from here.
2655 if let Some(trait_id) = trait_id {
2663 let item_def_id = item_def_id.to_def_id();
2664 let res = Res::SelfTy {
2666 alias_to: Some((item_def_id, false)),
2668 this.with_self_rib(res, |this| {
2669 if let Some(trait_ref) = opt_trait_reference.as_ref() {
2670 // Resolve type arguments in the trait path.
2671 visit::walk_trait_ref(this, trait_ref);
2673 // Resolve the self type.
2674 this.visit_ty(self_type);
2675 // Resolve the generic parameters.
2676 this.visit_generics(generics);
2678 // Resolve the items within the impl.
2679 this.with_current_self_type(self_type, |this| {
2680 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
2681 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
2682 for item in impl_items {
2683 this.resolve_impl_item(&**item);
2697 fn resolve_impl_item(&mut self, item: &'ast AssocItem) {
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(
2710 |i, s, c| ConstNotMemberOfTrait(i, s, c),
2714 if let Some(expr) = default {
2715 // We allow arbitrary const expressions inside of associated consts,
2716 // even if they are potentially not const evaluatable.
2718 // Type parameters can already be used and as associated consts are
2719 // not used as part of the type system, this is far less surprising.
2720 self.with_lifetime_rib(
2721 LifetimeRibKind::AnonymousPassThrough(item.id),
2723 this.with_constant_rib(
2725 HasGenericParams::Yes,
2727 |this| this.visit_expr(expr),
2733 AssocItemKind::Fn(box Fn { generics, .. }) => {
2734 debug!("resolve_implementation AssocItemKind::Fn");
2735 // We also need a new scope for the impl item type parameters.
2736 self.with_generic_param_rib(
2739 LifetimeRibKind::Generics {
2741 span: generics.span,
2742 kind: LifetimeBinderKind::Function,
2745 // If this is a trait impl, ensure the method
2747 this.check_trait_item(
2753 |i, s, c| MethodNotMemberOfTrait(i, s, c),
2756 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2760 AssocItemKind::TyAlias(box TyAlias { generics, .. }) => {
2761 debug!("resolve_implementation AssocItemKind::TyAlias");
2762 // We also need a new scope for the impl item type parameters.
2763 self.with_generic_param_rib(
2766 LifetimeRibKind::Generics {
2768 span: generics.span,
2769 kind: LifetimeBinderKind::Item,
2772 this.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2773 // If this is a trait impl, ensure the type
2775 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,
2804 F: FnOnce(Ident, String, Option<Symbol>) -> ResolutionError<'a>,
2806 // If there is a TraitRef in scope for an impl, then the method must be in the trait.
2807 let Some((module, _)) = &self.current_trait_ref else { return; };
2808 ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
2809 let key = self.r.new_key(ident, ns);
2810 let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2812 if binding.is_none() {
2813 // We could not find the trait item in the correct namespace.
2814 // Check the other namespace to report an error.
2820 let key = self.r.new_key(ident, ns);
2821 binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2824 let Some(binding) = binding else {
2825 // We could not find the method: report an error.
2826 let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
2827 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2828 let path_names = path_names_to_string(path);
2829 self.report_error(span, err(ident, path_names, candidate));
2833 let res = binding.res();
2834 let Res::Def(def_kind, _) = res else { bug!() };
2835 match (def_kind, kind) {
2836 (DefKind::AssocTy, AssocItemKind::TyAlias(..))
2837 | (DefKind::AssocFn, AssocItemKind::Fn(..))
2838 | (DefKind::AssocConst, AssocItemKind::Const(..)) => {
2839 self.r.record_partial_res(id, PartialRes::new(res));
2845 // The method kind does not correspond to what appeared in the trait, report.
2846 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2847 let (code, kind) = match kind {
2848 AssocItemKind::Const(..) => (rustc_errors::error_code!(E0323), "const"),
2849 AssocItemKind::Fn(..) => (rustc_errors::error_code!(E0324), "method"),
2850 AssocItemKind::TyAlias(..) => (rustc_errors::error_code!(E0325), "type"),
2851 AssocItemKind::MacCall(..) => span_bug!(span, "unexpanded macro"),
2853 let trait_path = path_names_to_string(path);
2856 ResolutionError::TraitImplMismatch {
2861 trait_item_span: binding.span,
2866 fn resolve_params(&mut self, params: &'ast [Param]) {
2867 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2868 for Param { pat, ty, .. } in params {
2869 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
2871 debug!("(resolving function / closure) recorded parameter");
2875 fn resolve_local(&mut self, local: &'ast Local) {
2876 debug!("resolving local ({:?})", local);
2877 // Resolve the type.
2878 walk_list!(self, visit_ty, &local.ty);
2880 // Resolve the initializer.
2881 if let Some((init, els)) = local.kind.init_else_opt() {
2882 self.visit_expr(init);
2884 // Resolve the `else` block
2885 if let Some(els) = els {
2886 self.visit_block(els);
2890 // Resolve the pattern.
2891 self.resolve_pattern_top(&local.pat, PatternSource::Let);
2894 /// build a map from pattern identifiers to binding-info's.
2895 /// this is done hygienically. This could arise for a macro
2896 /// that expands into an or-pattern where one 'x' was from the
2897 /// user and one 'x' came from the macro.
2898 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2899 let mut binding_map = FxHashMap::default();
2901 pat.walk(&mut |pat| {
2903 PatKind::Ident(binding_mode, ident, ref sub_pat)
2904 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
2906 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
2908 PatKind::Or(ref ps) => {
2909 // Check the consistency of this or-pattern and
2910 // then add all bindings to the larger map.
2911 for bm in self.check_consistent_bindings(ps) {
2912 binding_map.extend(bm);
2925 fn is_base_res_local(&self, nid: NodeId) -> bool {
2926 matches!(self.r.partial_res_map.get(&nid).map(|res| res.base_res()), Some(Res::Local(..)))
2929 /// Checks that all of the arms in an or-pattern have exactly the
2930 /// same set of bindings, with the same binding modes for each.
2931 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
2932 let mut missing_vars = FxHashMap::default();
2933 let mut inconsistent_vars = FxHashMap::default();
2935 // 1) Compute the binding maps of all arms.
2936 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
2938 // 2) Record any missing bindings or binding mode inconsistencies.
2939 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
2940 // Check against all arms except for the same pattern which is always self-consistent.
2944 .filter(|(_, pat)| pat.id != pat_outer.id)
2945 .flat_map(|(idx, _)| maps[idx].iter())
2946 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
2948 for (name, info, &binding_inner) in inners {
2951 // The inner binding is missing in the outer.
2953 missing_vars.entry(name).or_insert_with(|| BindingError {
2955 origin: BTreeSet::new(),
2956 target: BTreeSet::new(),
2957 could_be_path: name.as_str().starts_with(char::is_uppercase),
2959 binding_error.origin.insert(binding_inner.span);
2960 binding_error.target.insert(pat_outer.span);
2962 Some(binding_outer) => {
2963 if binding_outer.binding_mode != binding_inner.binding_mode {
2964 // The binding modes in the outer and inner bindings differ.
2967 .or_insert((binding_inner.span, binding_outer.span));
2974 // 3) Report all missing variables we found.
2975 let mut missing_vars = missing_vars.into_iter().collect::<Vec<_>>();
2976 missing_vars.sort_by_key(|&(sym, ref _err)| sym);
2978 for (name, mut v) in missing_vars.into_iter() {
2979 if inconsistent_vars.contains_key(&name) {
2980 v.could_be_path = false;
2983 *v.origin.iter().next().unwrap(),
2984 ResolutionError::VariableNotBoundInPattern(v, self.parent_scope),
2988 // 4) Report all inconsistencies in binding modes we found.
2989 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
2990 inconsistent_vars.sort();
2991 for (name, v) in inconsistent_vars {
2992 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
2995 // 5) Finally bubble up all the binding maps.
2999 /// Check the consistency of the outermost or-patterns.
3000 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
3001 pat.walk(&mut |pat| match pat.kind {
3002 PatKind::Or(ref ps) => {
3003 self.check_consistent_bindings(ps);
3010 fn resolve_arm(&mut self, arm: &'ast Arm) {
3011 self.with_rib(ValueNS, NormalRibKind, |this| {
3012 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
3013 walk_list!(this, visit_expr, &arm.guard);
3014 this.visit_expr(&arm.body);
3018 /// Arising from `source`, resolve a top level pattern.
3019 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
3020 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
3021 self.resolve_pattern(pat, pat_src, &mut bindings);
3027 pat_src: PatternSource,
3028 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3030 // We walk the pattern before declaring the pattern's inner bindings,
3031 // so that we avoid resolving a literal expression to a binding defined
3033 visit::walk_pat(self, pat);
3034 self.resolve_pattern_inner(pat, pat_src, bindings);
3035 // This has to happen *after* we determine which pat_idents are variants:
3036 self.check_consistent_bindings_top(pat);
3039 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
3043 /// A stack of sets of bindings accumulated.
3045 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
3046 /// be interpreted as re-binding an already bound binding. This results in an error.
3047 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
3048 /// in reusing this binding rather than creating a fresh one.
3050 /// When called at the top level, the stack must have a single element
3051 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
3052 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
3053 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
3054 /// When each `p_i` has been dealt with, the top set is merged with its parent.
3055 /// When a whole or-pattern has been dealt with, the thing happens.
3057 /// See the implementation and `fresh_binding` for more details.
3058 fn resolve_pattern_inner(
3061 pat_src: PatternSource,
3062 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3064 // Visit all direct subpatterns of this pattern.
3065 pat.walk(&mut |pat| {
3066 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
3068 PatKind::Ident(bmode, ident, ref sub) => {
3069 // First try to resolve the identifier as some existing entity,
3070 // then fall back to a fresh binding.
3071 let has_sub = sub.is_some();
3073 .try_resolve_as_non_binding(pat_src, bmode, ident, has_sub)
3074 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
3075 self.r.record_partial_res(pat.id, PartialRes::new(res));
3076 self.r.record_pat_span(pat.id, pat.span);
3078 PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
3079 self.smart_resolve_path(
3083 PathSource::TupleStruct(
3085 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
3089 PatKind::Path(ref qself, ref path) => {
3090 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
3092 PatKind::Struct(ref qself, ref path, ..) => {
3093 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Struct);
3095 PatKind::Or(ref ps) => {
3096 // Add a new set of bindings to the stack. `Or` here records that when a
3097 // binding already exists in this set, it should not result in an error because
3098 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
3099 bindings.push((PatBoundCtx::Or, Default::default()));
3101 // Now we need to switch back to a product context so that each
3102 // part of the or-pattern internally rejects already bound names.
3103 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
3104 bindings.push((PatBoundCtx::Product, Default::default()));
3105 self.resolve_pattern_inner(p, pat_src, bindings);
3106 // Move up the non-overlapping bindings to the or-pattern.
3107 // Existing bindings just get "merged".
3108 let collected = bindings.pop().unwrap().1;
3109 bindings.last_mut().unwrap().1.extend(collected);
3111 // This or-pattern itself can itself be part of a product,
3112 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
3113 // Both cases bind `a` again in a product pattern and must be rejected.
3114 let collected = bindings.pop().unwrap().1;
3115 bindings.last_mut().unwrap().1.extend(collected);
3117 // Prevent visiting `ps` as we've already done so above.
3130 pat_src: PatternSource,
3131 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3133 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
3134 // (We must not add it if it's in the bindings map because that breaks the assumptions
3135 // later passes make about or-patterns.)
3136 let ident = ident.normalize_to_macro_rules();
3138 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
3139 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
3140 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
3141 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
3142 // This is *required* for consistency which is checked later.
3143 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
3145 if already_bound_and {
3146 // Overlap in a product pattern somewhere; report an error.
3147 use ResolutionError::*;
3148 let error = match pat_src {
3149 // `fn f(a: u8, a: u8)`:
3150 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
3152 _ => IdentifierBoundMoreThanOnceInSamePattern,
3154 self.report_error(ident.span, error(ident.name));
3157 // Record as bound if it's valid:
3158 let ident_valid = ident.name != kw::Empty;
3160 bindings.last_mut().unwrap().1.insert(ident);
3163 if already_bound_or {
3164 // `Variant1(a) | Variant2(a)`, ok
3165 // Reuse definition from the first `a`.
3166 self.innermost_rib_bindings(ValueNS)[&ident]
3168 let res = Res::Local(pat_id);
3170 // A completely fresh binding add to the set if it's valid.
3171 self.innermost_rib_bindings(ValueNS).insert(ident, res);
3177 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
3178 &mut self.ribs[ns].last_mut().unwrap().bindings
3181 fn try_resolve_as_non_binding(
3183 pat_src: PatternSource,
3188 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
3189 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
3190 // also be interpreted as a path to e.g. a constant, variant, etc.
3191 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
3193 let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?;
3194 let (res, binding) = match ls_binding {
3195 LexicalScopeBinding::Item(binding)
3196 if is_syntactic_ambiguity && binding.is_ambiguity() =>
3198 // For ambiguous bindings we don't know all their definitions and cannot check
3199 // whether they can be shadowed by fresh bindings or not, so force an error.
3200 // issues/33118#issuecomment-233962221 (see below) still applies here,
3201 // but we have to ignore it for backward compatibility.
3202 self.r.record_use(ident, binding, false);
3205 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
3206 LexicalScopeBinding::Res(res) => (res, None),
3210 Res::SelfCtor(_) // See #70549.
3212 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
3214 ) if is_syntactic_ambiguity => {
3215 // Disambiguate in favor of a unit struct/variant or constant pattern.
3216 if let Some(binding) = binding {
3217 self.r.record_use(ident, binding, false);
3221 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static(_), _) => {
3222 // This is unambiguously a fresh binding, either syntactically
3223 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
3224 // to something unusable as a pattern (e.g., constructor function),
3225 // but we still conservatively report an error, see
3226 // issues/33118#issuecomment-233962221 for one reason why.
3227 let binding = binding.expect("no binding for a ctor or static");
3230 ResolutionError::BindingShadowsSomethingUnacceptable {
3231 shadowing_binding: pat_src,
3233 participle: if binding.is_import() { "imported" } else { "defined" },
3234 article: binding.res().article(),
3235 shadowed_binding: binding.res(),
3236 shadowed_binding_span: binding.span,
3241 Res::Def(DefKind::ConstParam, def_id) => {
3242 // Same as for DefKind::Const above, but here, `binding` is `None`, so we
3243 // have to construct the error differently
3246 ResolutionError::BindingShadowsSomethingUnacceptable {
3247 shadowing_binding: pat_src,
3249 participle: "defined",
3250 article: res.article(),
3251 shadowed_binding: res,
3252 shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"),
3257 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
3258 // These entities are explicitly allowed to be shadowed by fresh bindings.
3261 Res::SelfCtor(_) => {
3262 // We resolve `Self` in pattern position as an ident sometimes during recovery,
3263 // so delay a bug instead of ICEing.
3264 self.r.session.delay_span_bug(
3266 "unexpected `SelfCtor` in pattern, expected identifier"
3272 "unexpected resolution for an identifier in pattern: {:?}",
3278 // High-level and context dependent path resolution routine.
3279 // Resolves the path and records the resolution into definition map.
3280 // If resolution fails tries several techniques to find likely
3281 // resolution candidates, suggest imports or other help, and report
3282 // errors in user friendly way.
3283 fn smart_resolve_path(
3286 qself: Option<&QSelf>,
3288 source: PathSource<'ast>,
3290 self.smart_resolve_path_fragment(
3292 &Segment::from_path(path),
3294 Finalize::new(id, path.span),
3298 fn smart_resolve_path_fragment(
3300 qself: Option<&QSelf>,
3302 source: PathSource<'ast>,
3306 "smart_resolve_path_fragment(qself={:?}, path={:?}, finalize={:?})",
3311 let ns = source.namespace();
3313 let Finalize { node_id, path_span, .. } = finalize;
3314 let report_errors = |this: &mut Self, res: Option<Res>| {
3315 if this.should_report_errs() {
3316 let (err, candidates) =
3317 this.smart_resolve_report_errors(path, path_span, source, res);
3319 let def_id = this.parent_scope.module.nearest_parent_mod();
3320 let instead = res.is_some();
3322 if res.is_none() { this.report_missing_type_error(path) } else { None };
3324 this.r.use_injections.push(UseError {
3334 PartialRes::new(Res::Err)
3337 // For paths originating from calls (like in `HashMap::new()`), tries
3338 // to enrich the plain `failed to resolve: ...` message with hints
3339 // about possible missing imports.
3341 // Similar thing, for types, happens in `report_errors` above.
3342 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
3343 if !source.is_call() {
3344 return Some(parent_err);
3347 // Before we start looking for candidates, we have to get our hands
3348 // on the type user is trying to perform invocation on; basically:
3349 // we're transforming `HashMap::new` into just `HashMap`.
3350 let path = match path.split_last() {
3351 Some((_, path)) if !path.is_empty() => path,
3352 _ => return Some(parent_err),
3355 let (mut err, candidates) =
3356 this.smart_resolve_report_errors(path, path_span, PathSource::Type, None);
3358 if candidates.is_empty() {
3360 return Some(parent_err);
3363 // There are two different error messages user might receive at
3365 // - E0412 cannot find type `{}` in this scope
3366 // - E0433 failed to resolve: use of undeclared type or module `{}`
3368 // The first one is emitted for paths in type-position, and the
3369 // latter one - for paths in expression-position.
3371 // Thus (since we're in expression-position at this point), not to
3372 // confuse the user, we want to keep the *message* from E0432 (so
3373 // `parent_err`), but we want *hints* from E0412 (so `err`).
3375 // And that's what happens below - we're just mixing both messages
3376 // into a single one.
3377 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
3379 err.message = take(&mut parent_err.message);
3380 err.code = take(&mut parent_err.code);
3381 err.children = take(&mut parent_err.children);
3383 parent_err.cancel();
3385 let def_id = this.parent_scope.module.nearest_parent_mod();
3387 if this.should_report_errs() {
3388 this.r.use_injections.push(UseError {
3400 // We don't return `Some(parent_err)` here, because the error will
3401 // be already printed as part of the `use` injections
3405 let partial_res = match self.resolve_qpath_anywhere(
3410 source.defer_to_typeck(),
3413 Ok(Some(partial_res)) if partial_res.unresolved_segments() == 0 => {
3414 if source.is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err
3418 report_errors(self, Some(partial_res.base_res()))
3422 Ok(Some(partial_res)) if source.defer_to_typeck() => {
3423 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
3424 // or `<T>::A::B`. If `B` should be resolved in value namespace then
3425 // it needs to be added to the trait map.
3427 let item_name = path.last().unwrap().ident;
3428 let traits = self.traits_in_scope(item_name, ns);
3429 self.r.trait_map.insert(node_id, traits);
3432 if PrimTy::from_name(path[0].ident.name).is_some() {
3433 let mut std_path = Vec::with_capacity(1 + path.len());
3435 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
3436 std_path.extend(path);
3437 if let PathResult::Module(_) | PathResult::NonModule(_) =
3438 self.resolve_path(&std_path, Some(ns), None)
3440 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
3442 path.iter().last().map_or(path_span, |segment| segment.ident.span);
3444 self.r.confused_type_with_std_module.insert(item_span, path_span);
3445 self.r.confused_type_with_std_module.insert(path_span, path_span);
3453 if let Some(err) = report_errors_for_call(self, err) {
3454 self.report_error(err.span, err.node);
3457 PartialRes::new(Res::Err)
3460 _ => report_errors(self, None),
3463 if !matches!(source, PathSource::TraitItem(..)) {
3464 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
3465 self.r.record_partial_res(node_id, partial_res);
3466 self.resolve_elided_lifetimes_in_path(node_id, partial_res, path, source, path_span);
3472 fn self_type_is_available(&mut self) -> bool {
3474 .maybe_resolve_ident_in_lexical_scope(Ident::with_dummy_span(kw::SelfUpper), TypeNS);
3475 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3478 fn self_value_is_available(&mut self, self_span: Span) -> bool {
3479 let ident = Ident::new(kw::SelfLower, self_span);
3480 let binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS);
3481 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3484 /// A wrapper around [`Resolver::report_error`].
3486 /// This doesn't emit errors for function bodies if this is rustdoc.
3487 fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) {
3488 if self.should_report_errs() {
3489 self.r.report_error(span, resolution_error);
3494 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
3495 fn should_report_errs(&self) -> bool {
3496 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
3499 // Resolve in alternative namespaces if resolution in the primary namespace fails.
3500 fn resolve_qpath_anywhere(
3502 qself: Option<&QSelf>,
3504 primary_ns: Namespace,
3506 defer_to_typeck: bool,
3508 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3509 let mut fin_res = None;
3511 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
3512 if i == 0 || ns != primary_ns {
3513 match self.resolve_qpath(qself, path, ns, finalize)? {
3515 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
3517 return Ok(Some(partial_res));
3520 if fin_res.is_none() {
3521 fin_res = partial_res;
3528 assert!(primary_ns != MacroNS);
3530 if qself.is_none() {
3531 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
3532 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
3533 if let Ok((_, res)) =
3534 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
3536 return Ok(Some(PartialRes::new(res)));
3543 /// Handles paths that may refer to associated items.
3546 qself: Option<&QSelf>,
3550 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3552 "resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})",
3553 qself, path, ns, finalize,
3556 if let Some(qself) = qself {
3557 if qself.position == 0 {
3558 // This is a case like `<T>::B`, where there is no
3559 // trait to resolve. In that case, we leave the `B`
3560 // segment to be resolved by type-check.
3561 return Ok(Some(PartialRes::with_unresolved_segments(
3562 Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()),
3567 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
3569 // Currently, `path` names the full item (`A::B::C`, in
3570 // our example). so we extract the prefix of that that is
3571 // the trait (the slice upto and including
3572 // `qself.position`). And then we recursively resolve that,
3573 // but with `qself` set to `None`.
3574 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
3575 let partial_res = self.smart_resolve_path_fragment(
3577 &path[..=qself.position],
3578 PathSource::TraitItem(ns),
3579 Finalize::with_root_span(finalize.node_id, finalize.path_span, qself.path_span),
3582 // The remaining segments (the `C` in our example) will
3583 // have to be resolved by type-check, since that requires doing
3584 // trait resolution.
3585 return Ok(Some(PartialRes::with_unresolved_segments(
3586 partial_res.base_res(),
3587 partial_res.unresolved_segments() + path.len() - qself.position - 1,
3591 let result = match self.resolve_path(&path, Some(ns), Some(finalize)) {
3592 PathResult::NonModule(path_res) => path_res,
3593 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
3594 PartialRes::new(module.res().unwrap())
3596 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
3597 // don't report an error right away, but try to fallback to a primitive type.
3598 // So, we are still able to successfully resolve something like
3600 // use std::u8; // bring module u8 in scope
3601 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
3602 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
3603 // // not to non-existent std::u8::max_value
3606 // Such behavior is required for backward compatibility.
3607 // The same fallback is used when `a` resolves to nothing.
3608 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
3609 if (ns == TypeNS || path.len() > 1)
3610 && PrimTy::from_name(path[0].ident.name).is_some() =>
3612 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
3613 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
3615 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3616 PartialRes::new(module.res().unwrap())
3618 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
3619 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
3621 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
3622 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
3626 && result.base_res() != Res::Err
3627 && path[0].ident.name != kw::PathRoot
3628 && path[0].ident.name != kw::DollarCrate
3630 let unqualified_result = {
3631 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
3632 PathResult::NonModule(path_res) => path_res.base_res(),
3633 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3634 module.res().unwrap()
3636 _ => return Ok(Some(result)),
3639 if result.base_res() == unqualified_result {
3640 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
3641 self.r.lint_buffer.buffer_lint(
3645 "unnecessary qualification",
3653 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
3654 if let Some(label) = label {
3655 if label.ident.as_str().as_bytes()[1] != b'_' {
3656 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
3659 if let Ok((_, orig_span)) = self.resolve_label(label.ident) {
3660 diagnostics::signal_label_shadowing(self.r.session, orig_span, label.ident)
3663 self.with_label_rib(NormalRibKind, |this| {
3664 let ident = label.ident.normalize_to_macro_rules();
3665 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
3673 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
3674 self.with_resolved_label(label, id, |this| this.visit_block(block));
3677 fn resolve_block(&mut self, block: &'ast Block) {
3678 debug!("(resolving block) entering block");
3679 // Move down in the graph, if there's an anonymous module rooted here.
3680 let orig_module = self.parent_scope.module;
3681 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
3683 let mut num_macro_definition_ribs = 0;
3684 if let Some(anonymous_module) = anonymous_module {
3685 debug!("(resolving block) found anonymous module, moving down");
3686 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3687 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3688 self.parent_scope.module = anonymous_module;
3690 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3693 let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
3694 if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
3695 (block.could_be_bare_literal, &block.stmts[..])
3696 && let ExprKind::Type(..) = expr.kind
3698 self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
3701 // Descend into the block.
3702 for stmt in &block.stmts {
3703 if let StmtKind::Item(ref item) = stmt.kind
3704 && let ItemKind::MacroDef(..) = item.kind {
3705 num_macro_definition_ribs += 1;
3706 let res = self.r.local_def_id(item.id).to_def_id();
3707 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
3708 self.label_ribs.push(Rib::new(MacroDefinition(res)));
3711 self.visit_stmt(stmt);
3713 self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
3716 self.parent_scope.module = orig_module;
3717 for _ in 0..num_macro_definition_ribs {
3718 self.ribs[ValueNS].pop();
3719 self.label_ribs.pop();
3721 self.ribs[ValueNS].pop();
3722 if anonymous_module.is_some() {
3723 self.ribs[TypeNS].pop();
3725 debug!("(resolving block) leaving block");
3728 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
3729 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
3730 self.with_constant_rib(
3732 if constant.value.is_potential_trivial_const_param() {
3733 HasGenericParams::Yes
3735 HasGenericParams::No
3738 |this| visit::walk_anon_const(this, constant),
3742 fn resolve_inline_const(&mut self, constant: &'ast AnonConst) {
3743 debug!("resolve_anon_const {constant:?}");
3744 self.with_constant_rib(IsRepeatExpr::No, HasGenericParams::Yes, None, |this| {
3745 visit::walk_anon_const(this, constant);
3749 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
3750 // First, record candidate traits for this expression if it could
3751 // result in the invocation of a method call.
3753 self.record_candidate_traits_for_expr_if_necessary(expr);
3755 // Next, resolve the node.
3757 ExprKind::Path(ref qself, ref path) => {
3758 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
3759 visit::walk_expr(self, expr);
3762 ExprKind::Struct(ref se) => {
3763 self.smart_resolve_path(expr.id, se.qself.as_ref(), &se.path, PathSource::Struct);
3764 visit::walk_expr(self, expr);
3767 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
3768 match self.resolve_label(label.ident) {
3769 Ok((node_id, _)) => {
3770 // Since this res is a label, it is never read.
3771 self.r.label_res_map.insert(expr.id, node_id);
3772 self.diagnostic_metadata.unused_labels.remove(&node_id);
3775 self.report_error(label.ident.span, error);
3779 // visit `break` argument if any
3780 visit::walk_expr(self, expr);
3783 ExprKind::Break(None, Some(ref e)) => {
3784 // We use this instead of `visit::walk_expr` to keep the parent expr around for
3785 // better diagnostics.
3786 self.resolve_expr(e, Some(&expr));
3789 ExprKind::Let(ref pat, ref scrutinee, _) => {
3790 self.visit_expr(scrutinee);
3791 self.resolve_pattern_top(pat, PatternSource::Let);
3794 ExprKind::If(ref cond, ref then, ref opt_else) => {
3795 self.with_rib(ValueNS, NormalRibKind, |this| {
3796 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3797 this.visit_expr(cond);
3798 this.diagnostic_metadata.in_if_condition = old;
3799 this.visit_block(then);
3801 if let Some(expr) = opt_else {
3802 self.visit_expr(expr);
3806 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3808 ExprKind::While(ref cond, ref block, label) => {
3809 self.with_resolved_label(label, expr.id, |this| {
3810 this.with_rib(ValueNS, NormalRibKind, |this| {
3811 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3812 this.visit_expr(cond);
3813 this.diagnostic_metadata.in_if_condition = old;
3814 this.visit_block(block);
3819 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
3820 self.visit_expr(iter_expr);
3821 self.with_rib(ValueNS, NormalRibKind, |this| {
3822 this.resolve_pattern_top(pat, PatternSource::For);
3823 this.resolve_labeled_block(label, expr.id, block);
3827 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
3829 // Equivalent to `visit::walk_expr` + passing some context to children.
3830 ExprKind::Field(ref subexpression, _) => {
3831 self.resolve_expr(subexpression, Some(expr));
3833 ExprKind::MethodCall(ref segment, ref arguments, _) => {
3834 let mut arguments = arguments.iter();
3835 self.resolve_expr(arguments.next().unwrap(), Some(expr));
3836 for argument in arguments {
3837 self.resolve_expr(argument, None);
3839 self.visit_path_segment(expr.span, segment);
3842 ExprKind::Call(ref callee, ref arguments) => {
3843 self.resolve_expr(callee, Some(expr));
3844 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
3845 for (idx, argument) in arguments.iter().enumerate() {
3846 // Constant arguments need to be treated as AnonConst since
3847 // that is how they will be later lowered to HIR.
3848 if const_args.contains(&idx) {
3849 self.with_constant_rib(
3851 if argument.is_potential_trivial_const_param() {
3852 HasGenericParams::Yes
3854 HasGenericParams::No
3858 this.resolve_expr(argument, None);
3862 self.resolve_expr(argument, None);
3866 ExprKind::Type(ref type_expr, ref ty) => {
3867 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
3868 // type ascription. Here we are trying to retrieve the span of the colon token as
3869 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
3870 // with `expr::Ty`, only in this case it will match the span from
3871 // `type_ascription_path_suggestions`.
3872 self.diagnostic_metadata
3873 .current_type_ascription
3874 .push(type_expr.span.between(ty.span));
3875 visit::walk_expr(self, expr);
3876 self.diagnostic_metadata.current_type_ascription.pop();
3878 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
3879 // resolve the arguments within the proper scopes so that usages of them inside the
3880 // closure are detected as upvars rather than normal closure arg usages.
3881 ExprKind::Closure(_, _, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
3882 self.with_rib(ValueNS, NormalRibKind, |this| {
3883 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
3884 // Resolve arguments:
3885 this.resolve_params(&fn_decl.inputs);
3886 // No need to resolve return type --
3887 // the outer closure return type is `FnRetTy::Default`.
3889 // Now resolve the inner closure
3891 // No need to resolve arguments: the inner closure has none.
3892 // Resolve the return type:
3893 visit::walk_fn_ret_ty(this, &fn_decl.output);
3895 this.visit_expr(body);
3900 // For closures, ClosureOrAsyncRibKind is added in visit_fn
3901 ExprKind::Closure(ClosureBinder::For { ref generic_params, span }, ..) => {
3902 self.with_generic_param_rib(
3905 LifetimeRibKind::Generics {
3907 kind: LifetimeBinderKind::Closure,
3910 |this| visit::walk_expr(this, expr),
3913 ExprKind::Closure(..) => visit::walk_expr(self, expr),
3914 ExprKind::Async(..) => {
3915 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
3917 ExprKind::Repeat(ref elem, ref ct) => {
3918 self.visit_expr(elem);
3919 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
3920 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
3921 this.resolve_anon_const(ct, IsRepeatExpr::Yes)
3925 ExprKind::ConstBlock(ref ct) => {
3926 self.resolve_inline_const(ct);
3928 ExprKind::Index(ref elem, ref idx) => {
3929 self.resolve_expr(elem, Some(expr));
3930 self.visit_expr(idx);
3933 visit::walk_expr(self, expr);
3938 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
3940 ExprKind::Field(_, ident) => {
3941 // FIXME(#6890): Even though you can't treat a method like a
3942 // field, we need to add any trait methods we find that match
3943 // the field name so that we can do some nice error reporting
3944 // later on in typeck.
3945 let traits = self.traits_in_scope(ident, ValueNS);
3946 self.r.trait_map.insert(expr.id, traits);
3948 ExprKind::MethodCall(ref segment, ..) => {
3949 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
3950 let traits = self.traits_in_scope(segment.ident, ValueNS);
3951 self.r.trait_map.insert(expr.id, traits);
3959 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
3960 self.r.traits_in_scope(
3961 self.current_trait_ref.as_ref().map(|(module, _)| *module),
3964 Some((ident.name, ns)),
3969 struct LifetimeCountVisitor<'a, 'b> {
3970 r: &'b mut Resolver<'a>,
3973 /// Walks the whole crate in DFS order, visiting each item, counting the declared number of
3974 /// lifetime generic parameters.
3975 impl<'ast> Visitor<'ast> for LifetimeCountVisitor<'_, '_> {
3976 fn visit_item(&mut self, item: &'ast Item) {
3978 ItemKind::TyAlias(box TyAlias { ref generics, .. })
3979 | ItemKind::Fn(box Fn { ref generics, .. })
3980 | ItemKind::Enum(_, ref generics)
3981 | ItemKind::Struct(_, ref generics)
3982 | ItemKind::Union(_, ref generics)
3983 | ItemKind::Impl(box Impl { ref generics, .. })
3984 | ItemKind::Trait(box Trait { ref generics, .. })
3985 | ItemKind::TraitAlias(ref generics, _) => {
3986 let def_id = self.r.local_def_id(item.id);
3987 let count = generics
3990 .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
3992 self.r.item_generics_num_lifetimes.insert(def_id, count);
3996 | ItemKind::ForeignMod(..)
3997 | ItemKind::Static(..)
3998 | ItemKind::Const(..)
4000 | ItemKind::ExternCrate(..)
4001 | ItemKind::MacroDef(..)
4002 | ItemKind::GlobalAsm(..)
4003 | ItemKind::MacCall(..) => {}
4005 visit::walk_item(self, item)
4009 impl<'a> Resolver<'a> {
4010 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
4011 visit::walk_crate(&mut LifetimeCountVisitor { r: self }, krate);
4012 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
4013 visit::walk_crate(&mut late_resolution_visitor, krate);
4014 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
4015 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");