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::ty::DefIdTree;
25 use rustc_middle::{bug, span_bug};
26 use rustc_session::lint;
27 use rustc_span::symbol::{kw, sym, Ident, Symbol};
28 use rustc_span::{BytePos, Span};
29 use smallvec::{smallvec, SmallVec};
31 use rustc_span::source_map::{respan, Spanned};
32 use std::collections::{hash_map::Entry, BTreeSet};
33 use std::mem::{replace, take};
37 pub(crate) mod lifetimes;
39 type Res = def::Res<NodeId>;
41 type IdentMap<T> = FxHashMap<Ident, T>;
43 /// Map from the name in a pattern to its binding mode.
44 type BindingMap = IdentMap<BindingInfo>;
46 #[derive(Copy, Clone, Debug)]
49 binding_mode: BindingMode,
52 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
53 pub enum PatternSource {
60 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
67 pub fn descr(self) -> &'static str {
69 PatternSource::Match => "match binding",
70 PatternSource::Let => "let binding",
71 PatternSource::For => "for binding",
72 PatternSource::FnParam => "function parameter",
77 /// Denotes whether the context for the set of already bound bindings is a `Product`
78 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
79 /// See those functions for more information.
82 /// A product pattern context, e.g., `Variant(a, b)`.
84 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
88 /// Does this the item (from the item rib scope) allow generic parameters?
89 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
90 pub(crate) enum HasGenericParams {
95 impl HasGenericParams {
96 fn force_yes_if(self, b: bool) -> Self {
97 if b { Self::Yes } else { self }
101 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
102 pub(crate) enum ConstantItemKind {
107 /// The rib kind restricts certain accesses,
108 /// e.g. to a `Res::Local` of an outer item.
109 #[derive(Copy, Clone, Debug)]
110 pub(crate) enum RibKind<'a> {
111 /// No restriction needs to be applied.
114 /// We passed through an impl or trait and are now in one of its
115 /// methods or associated types. Allow references to ty params that impl or trait
116 /// binds. Disallow any other upvars (including other ty params that are
120 /// We passed through a closure. Disallow labels.
121 ClosureOrAsyncRibKind,
123 /// We passed through a function definition. Disallow upvars.
124 /// Permit only those const parameters that are specified in the function's generics.
127 /// We passed through an item scope. Disallow upvars.
128 ItemRibKind(HasGenericParams),
130 /// We're in a constant item. Can't refer to dynamic stuff.
132 /// The item may reference generic parameters in trivial constant expressions.
133 /// All other constants aren't allowed to use generic params at all.
134 ConstantItemRibKind(HasGenericParams, Option<(Ident, ConstantItemKind)>),
136 /// We passed through a module.
137 ModuleRibKind(Module<'a>),
139 /// We passed through a `macro_rules!` statement
140 MacroDefinition(DefId),
142 /// All bindings in this rib are generic parameters that can't be used
143 /// from the default of a generic parameter because they're not declared
144 /// before said generic parameter. Also see the `visit_generics` override.
145 ForwardGenericParamBanRibKind,
147 /// We are inside of the type of a const parameter. Can't refer to any
151 /// We are inside a `sym` inline assembly operand. Can only refer to
157 /// Whether this rib kind contains generic parameters, as opposed to local
159 pub(crate) fn contains_params(&self) -> bool {
162 | ClosureOrAsyncRibKind
164 | ConstantItemRibKind(..)
167 | ConstParamTyRibKind
168 | InlineAsmSymRibKind => false,
169 AssocItemRibKind | ItemRibKind(_) | ForwardGenericParamBanRibKind => true,
173 /// This rib forbids referring to labels defined in upwards ribs.
174 fn is_label_barrier(self) -> bool {
176 NormalRibKind | MacroDefinition(..) => false,
179 | ClosureOrAsyncRibKind
182 | ConstantItemRibKind(..)
184 | ForwardGenericParamBanRibKind
185 | ConstParamTyRibKind
186 | InlineAsmSymRibKind => true,
191 /// A single local scope.
193 /// A rib represents a scope names can live in. Note that these appear in many places, not just
194 /// around braces. At any place where the list of accessible names (of the given namespace)
195 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
196 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
199 /// Different [rib kinds](enum@RibKind) are transparent for different names.
201 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
202 /// resolving, the name is looked up from inside out.
204 pub(crate) struct Rib<'a, R = Res> {
205 pub bindings: IdentMap<R>,
206 pub kind: RibKind<'a>,
209 impl<'a, R> Rib<'a, R> {
210 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
211 Rib { bindings: Default::default(), kind }
215 #[derive(Clone, Copy, Debug)]
216 enum LifetimeUseSet {
217 One { use_span: Span, use_ctxt: visit::LifetimeCtxt },
221 #[derive(Copy, Clone, Debug)]
222 enum LifetimeRibKind {
223 /// This rib acts as a barrier to forbid reference to lifetimes of a parent item.
226 /// This rib declares generic parameters.
227 Generics { binder: NodeId, span: Span, kind: LifetimeBinderKind },
229 /// FIXME(const_generics): This patches over an ICE caused by non-'static lifetimes in const
230 /// generics. We are disallowing this until we can decide on how we want to handle non-'static
231 /// lifetimes in const generics. See issue #74052 for discussion.
234 /// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`.
235 /// This function will emit an error if `generic_const_exprs` is not enabled, the body identified by
236 /// `body_id` is an anonymous constant and `lifetime_ref` is non-static.
239 /// Create a new anonymous lifetime parameter and reference it.
241 /// If `report_in_path`, report an error when encountering lifetime elision in a path:
243 /// struct Foo<'a> { x: &'a () }
244 /// async fn foo(x: Foo) {}
247 /// Note: the error should not trigger when the elided lifetime is in a pattern or
248 /// expression-position path:
250 /// struct Foo<'a> { x: &'a () }
251 /// async fn foo(Foo { x: _ }: Foo<'_>) {}
253 AnonymousCreateParameter { binder: NodeId, report_in_path: bool },
255 /// Give a hard error when either `&` or `'_` is written. Used to
256 /// rule out things like `where T: Foo<'_>`. Does not imply an
257 /// error on default object bounds (e.g., `Box<dyn Foo>`).
258 AnonymousReportError,
260 /// Pass responsibility to `resolve_lifetime` code for all cases.
261 AnonymousPassThrough(NodeId, /* in_fn_return */ bool),
264 #[derive(Copy, Clone, Debug)]
265 enum LifetimeBinderKind {
275 impl LifetimeBinderKind {
276 fn descr(self) -> &'static str {
277 use LifetimeBinderKind::*;
279 BareFnType => "type",
280 PolyTrait => "bound",
281 WhereBound => "bound",
283 ImplBlock => "impl block",
284 Function => "function",
285 Closure => "closure",
292 kind: LifetimeRibKind,
293 // We need to preserve insertion order for async fns.
294 bindings: FxIndexMap<Ident, (NodeId, LifetimeRes)>,
298 fn new(kind: LifetimeRibKind) -> LifetimeRib {
299 LifetimeRib { bindings: Default::default(), kind }
303 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
304 pub(crate) enum AliasPossibility {
309 #[derive(Copy, Clone, Debug)]
310 pub(crate) enum PathSource<'a> {
311 // Type paths `Path`.
313 // Trait paths in bounds or impls.
314 Trait(AliasPossibility),
315 // Expression paths `path`, with optional parent context.
316 Expr(Option<&'a Expr>),
317 // Paths in path patterns `Path`.
319 // Paths in struct expressions and patterns `Path { .. }`.
321 // Paths in tuple struct patterns `Path(..)`.
322 TupleStruct(Span, &'a [Span]),
323 // `m::A::B` in `<T as m::A>::B::C`.
324 TraitItem(Namespace),
327 impl<'a> PathSource<'a> {
328 fn namespace(self) -> Namespace {
330 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
331 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
332 PathSource::TraitItem(ns) => ns,
336 fn defer_to_typeck(self) -> bool {
339 | PathSource::Expr(..)
342 | PathSource::TupleStruct(..) => true,
343 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
347 fn descr_expected(self) -> &'static str {
349 PathSource::Type => "type",
350 PathSource::Trait(_) => "trait",
351 PathSource::Pat => "unit struct, unit variant or constant",
352 PathSource::Struct => "struct, variant or union type",
353 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
354 PathSource::TraitItem(ns) => match ns {
355 TypeNS => "associated type",
356 ValueNS => "method or associated constant",
357 MacroNS => bug!("associated macro"),
359 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
360 // "function" here means "anything callable" rather than `DefKind::Fn`,
361 // this is not precise but usually more helpful than just "value".
362 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
363 // the case of `::some_crate()`
364 ExprKind::Path(_, path)
365 if path.segments.len() == 2
366 && path.segments[0].ident.name == kw::PathRoot =>
370 ExprKind::Path(_, path) => {
371 let mut msg = "function";
372 if let Some(segment) = path.segments.iter().last() {
373 if let Some(c) = segment.ident.to_string().chars().next() {
374 if c.is_uppercase() {
375 msg = "function, tuple struct or tuple variant";
388 fn is_call(self) -> bool {
389 matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
392 pub(crate) fn is_expected(self, res: Res) -> bool {
394 PathSource::Type => matches!(
401 | DefKind::TraitAlias
406 | DefKind::ForeignTy,
411 PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
412 PathSource::Trait(AliasPossibility::Maybe) => {
413 matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
415 PathSource::Expr(..) => matches!(
418 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
423 | DefKind::AssocConst
424 | DefKind::ConstParam,
430 res.expected_in_unit_struct_pat()
431 || matches!(res, Res::Def(DefKind::Const | DefKind::AssocConst, _))
433 PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
434 PathSource::Struct => matches!(
443 ) | Res::SelfTy { .. }
445 PathSource::TraitItem(ns) => match res {
446 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
447 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
453 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
454 use rustc_errors::error_code;
455 match (self, has_unexpected_resolution) {
456 (PathSource::Trait(_), true) => error_code!(E0404),
457 (PathSource::Trait(_), false) => error_code!(E0405),
458 (PathSource::Type, true) => error_code!(E0573),
459 (PathSource::Type, false) => error_code!(E0412),
460 (PathSource::Struct, true) => error_code!(E0574),
461 (PathSource::Struct, false) => error_code!(E0422),
462 (PathSource::Expr(..), true) => error_code!(E0423),
463 (PathSource::Expr(..), false) => error_code!(E0425),
464 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
465 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
466 (PathSource::TraitItem(..), true) => error_code!(E0575),
467 (PathSource::TraitItem(..), false) => error_code!(E0576),
473 struct DiagnosticMetadata<'ast> {
474 /// The current trait's associated items' ident, used for diagnostic suggestions.
475 current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
477 /// The current self type if inside an impl (used for better errors).
478 current_self_type: Option<Ty>,
480 /// The current self item if inside an ADT (used for better errors).
481 current_self_item: Option<NodeId>,
483 /// The current trait (used to suggest).
484 current_item: Option<&'ast Item>,
486 /// When processing generics and encountering a type not found, suggest introducing a type
488 currently_processing_generics: bool,
490 /// The current enclosing (non-closure) function (used for better errors).
491 current_function: Option<(FnKind<'ast>, Span)>,
493 /// A list of labels as of yet unused. Labels will be removed from this map when
494 /// they are used (in a `break` or `continue` statement)
495 unused_labels: FxHashMap<NodeId, Span>,
497 /// Only used for better errors on `fn(): fn()`.
498 current_type_ascription: Vec<Span>,
500 /// Only used for better errors on `let x = { foo: bar };`.
501 /// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only
502 /// needed for cases where this parses as a correct type ascription.
503 current_block_could_be_bare_struct_literal: Option<Span>,
505 /// Only used for better errors on `let <pat>: <expr, not type>;`.
506 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
508 /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
509 in_if_condition: Option<&'ast Expr>,
511 /// If we are currently in a trait object definition. Used to point at the bounds when
512 /// encountering a struct or enum.
513 current_trait_object: Option<&'ast [ast::GenericBound]>,
515 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
516 current_where_predicate: Option<&'ast WherePredicate>,
518 current_type_path: Option<&'ast Ty>,
520 /// The current impl items (used to suggest).
521 current_impl_items: Option<&'ast [P<AssocItem>]>,
523 /// When processing impl trait
524 currently_processing_impl_trait: Option<(TraitRef, Ty)>,
527 struct LateResolutionVisitor<'a, 'b, 'ast> {
528 r: &'b mut Resolver<'a>,
530 /// The module that represents the current item scope.
531 parent_scope: ParentScope<'a>,
533 /// The current set of local scopes for types and values.
534 /// FIXME #4948: Reuse ribs to avoid allocation.
535 ribs: PerNS<Vec<Rib<'a>>>,
537 /// The current set of local scopes, for labels.
538 label_ribs: Vec<Rib<'a, NodeId>>,
540 /// The current set of local scopes for lifetimes.
541 lifetime_ribs: Vec<LifetimeRib>,
543 /// The trait that the current context can refer to.
544 current_trait_ref: Option<(Module<'a>, TraitRef)>,
546 /// Fields used to add information to diagnostic errors.
547 diagnostic_metadata: DiagnosticMetadata<'ast>,
549 /// State used to know whether to ignore resolution errors for function bodies.
551 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
552 /// In most cases this will be `None`, in which case errors will always be reported.
553 /// If it is `true`, then it will be updated when entering a nested function or trait body.
556 /// Count the number of places a lifetime is used.
557 lifetime_uses: FxHashMap<LocalDefId, LifetimeUseSet>,
560 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
561 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
562 fn visit_attribute(&mut self, _: &'ast Attribute) {
563 // We do not want to resolve expressions that appear in attributes,
564 // as they do not correspond to actual code.
566 fn visit_item(&mut self, item: &'ast Item) {
567 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
568 // Always report errors in items we just entered.
569 let old_ignore = replace(&mut self.in_func_body, false);
570 self.with_lifetime_rib(LifetimeRibKind::Item, |this| this.resolve_item(item));
571 self.in_func_body = old_ignore;
572 self.diagnostic_metadata.current_item = prev;
574 fn visit_arm(&mut self, arm: &'ast Arm) {
575 self.resolve_arm(arm);
577 fn visit_block(&mut self, block: &'ast Block) {
578 self.resolve_block(block);
580 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
581 // We deal with repeat expressions explicitly in `resolve_expr`.
582 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
583 this.resolve_anon_const(constant, IsRepeatExpr::No);
586 fn visit_expr(&mut self, expr: &'ast Expr) {
587 self.resolve_expr(expr, None);
589 fn visit_local(&mut self, local: &'ast Local) {
590 let local_spans = match local.pat.kind {
591 // We check for this to avoid tuple struct fields.
592 PatKind::Wild => None,
595 local.ty.as_ref().map(|ty| ty.span),
596 local.kind.init().map(|init| init.span),
599 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
600 self.resolve_local(local);
601 self.diagnostic_metadata.current_let_binding = original;
603 fn visit_ty(&mut self, ty: &'ast Ty) {
604 let prev = self.diagnostic_metadata.current_trait_object;
605 let prev_ty = self.diagnostic_metadata.current_type_path;
607 TyKind::Rptr(None, _) => {
608 // Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
610 let span = self.r.session.source_map().next_point(ty.span.shrink_to_lo());
611 self.resolve_elided_lifetime(ty.id, span);
613 TyKind::Path(ref qself, ref path) => {
614 self.diagnostic_metadata.current_type_path = Some(ty);
615 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
617 // Check whether we should interpret this as a bare trait object.
619 && let Some(partial_res) = self.r.partial_res_map.get(&ty.id)
620 && partial_res.unresolved_segments() == 0
621 && let Res::Def(DefKind::Trait | DefKind::TraitAlias, _) = partial_res.base_res()
623 // This path is actually a bare trait object. In case of a bare `Fn`-trait
624 // object with anonymous lifetimes, we need this rib to correctly place the
625 // synthetic lifetimes.
626 let span = ty.span.shrink_to_lo().to(path.span.shrink_to_lo());
627 self.with_generic_param_rib(
630 LifetimeRibKind::Generics {
632 kind: LifetimeBinderKind::PolyTrait,
635 |this| this.visit_path(&path, ty.id),
637 self.diagnostic_metadata.current_type_path = prev_ty;
641 TyKind::ImplicitSelf => {
642 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
644 .resolve_ident_in_lexical_scope(
647 Some(Finalize::new(ty.id, ty.span)),
650 .map_or(Res::Err, |d| d.res());
651 self.r.record_partial_res(ty.id, PartialRes::new(res));
653 TyKind::TraitObject(ref bounds, ..) => {
654 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
656 TyKind::BareFn(ref bare_fn) => {
657 let span = ty.span.shrink_to_lo().to(bare_fn.decl_span.shrink_to_lo());
658 self.with_generic_param_rib(
659 &bare_fn.generic_params,
661 LifetimeRibKind::Generics {
663 kind: LifetimeBinderKind::BareFnType,
667 this.visit_generic_params(&bare_fn.generic_params, false);
668 this.with_lifetime_rib(
669 LifetimeRibKind::AnonymousCreateParameter {
671 report_in_path: false,
673 |this| walk_list!(this, visit_param, &bare_fn.decl.inputs),
675 this.with_lifetime_rib(
676 LifetimeRibKind::AnonymousPassThrough(ty.id, true),
677 |this| this.visit_fn_ret_ty(&bare_fn.decl.output),
681 self.diagnostic_metadata.current_trait_object = prev;
686 visit::walk_ty(self, ty);
687 self.diagnostic_metadata.current_trait_object = prev;
688 self.diagnostic_metadata.current_type_path = prev_ty;
690 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef, _: &'ast TraitBoundModifier) {
691 let span = tref.span.shrink_to_lo().to(tref.trait_ref.path.span.shrink_to_lo());
692 self.with_generic_param_rib(
693 &tref.bound_generic_params,
695 LifetimeRibKind::Generics {
696 binder: tref.trait_ref.ref_id,
697 kind: LifetimeBinderKind::PolyTrait,
701 this.visit_generic_params(&tref.bound_generic_params, false);
702 this.smart_resolve_path(
703 tref.trait_ref.ref_id,
705 &tref.trait_ref.path,
706 PathSource::Trait(AliasPossibility::Maybe),
708 this.visit_trait_ref(&tref.trait_ref);
712 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
713 match foreign_item.kind {
714 ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
715 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
716 this.with_generic_param_rib(
718 ItemRibKind(HasGenericParams::Yes),
719 LifetimeRibKind::Generics {
720 binder: foreign_item.id,
721 kind: LifetimeBinderKind::Item,
724 |this| visit::walk_foreign_item(this, foreign_item),
728 ForeignItemKind::Fn(box Fn { ref generics, .. }) => {
729 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
730 this.with_generic_param_rib(
732 ItemRibKind(HasGenericParams::Yes),
733 LifetimeRibKind::Generics {
734 binder: foreign_item.id,
735 kind: LifetimeBinderKind::Function,
738 |this| visit::walk_foreign_item(this, foreign_item),
742 ForeignItemKind::Static(..) => {
743 self.with_item_rib(|this| {
744 visit::walk_foreign_item(this, foreign_item);
747 ForeignItemKind::MacCall(..) => {
748 panic!("unexpanded macro in resolve!")
752 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, fn_id: NodeId) {
753 let rib_kind = match fn_kind {
754 // Bail if the function is foreign, and thus cannot validly have
755 // a body, or if there's no body for some other reason.
756 FnKind::Fn(FnCtxt::Foreign, _, sig, _, generics, _)
757 | FnKind::Fn(_, _, sig, _, generics, None) => {
758 self.visit_fn_header(&sig.header);
759 self.visit_generics(generics);
760 // We don't need to deal with patterns in parameters, because
761 // they are not possible for foreign or bodiless functions.
762 self.with_lifetime_rib(
763 LifetimeRibKind::AnonymousCreateParameter {
765 report_in_path: false,
767 |this| walk_list!(this, visit_param, &sig.decl.inputs),
769 self.with_lifetime_rib(
770 LifetimeRibKind::AnonymousPassThrough(fn_id, true),
771 |this| this.visit_fn_ret_ty(&sig.decl.output),
775 FnKind::Fn(FnCtxt::Free, ..) => FnItemRibKind,
776 FnKind::Fn(FnCtxt::Assoc(_), ..) => NormalRibKind,
777 FnKind::Closure(..) => ClosureOrAsyncRibKind,
779 let previous_value = self.diagnostic_metadata.current_function;
780 if matches!(fn_kind, FnKind::Fn(..)) {
781 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
783 debug!("(resolving function) entering function");
785 // Create a value rib for the function.
786 self.with_rib(ValueNS, rib_kind, |this| {
787 // Create a label rib for the function.
788 this.with_label_rib(FnItemRibKind, |this| {
790 FnKind::Fn(_, _, sig, _, generics, body) => {
791 this.visit_generics(generics);
793 let declaration = &sig.decl;
794 let async_node_id = sig.header.asyncness.opt_return_id();
796 // Argument-position elided lifetimes must be transformed into fresh
797 // generic parameters. This is especially useful for `async fn`, where
798 // these fresh generic parameters can be applied to the opaque `impl Trait`
800 this.with_lifetime_rib(
801 LifetimeRibKind::AnonymousCreateParameter {
803 // Only emit a hard error for `async fn`, since this kind of
804 // elision has always been allowed in regular `fn`s.
805 report_in_path: async_node_id.is_some(),
807 // Add each argument to the rib.
808 |this| this.resolve_params(&declaration.inputs),
811 // Construct the list of in-scope lifetime parameters for async lowering.
812 // We include all lifetime parameters, either named or "Fresh".
813 // The order of those parameters does not matter, as long as it is
815 if let Some(async_node_id) = async_node_id {
816 let mut extra_lifetime_params = this
818 .extra_lifetime_params_map
821 .unwrap_or_default();
822 for rib in this.lifetime_ribs.iter().rev() {
823 extra_lifetime_params.extend(
826 .map(|(&ident, &(node_id, res))| (ident, node_id, res)),
829 LifetimeRibKind::Item => break,
830 LifetimeRibKind::AnonymousCreateParameter {
833 if let Some(earlier_fresh) =
834 this.r.extra_lifetime_params_map.get(&binder)
836 extra_lifetime_params.extend(earlier_fresh);
843 .extra_lifetime_params_map
844 .insert(async_node_id, extra_lifetime_params);
847 this.with_lifetime_rib(
848 LifetimeRibKind::AnonymousPassThrough(
849 // For async fn, the return type appears inside a custom
850 // `impl Future` RPIT, so we override the binder's id.
851 async_node_id.unwrap_or(fn_id),
854 |this| visit::walk_fn_ret_ty(this, &declaration.output),
857 if let Some(body) = body {
858 // Ignore errors in function bodies if this is rustdoc
859 // Be sure not to set this until the function signature has been resolved.
860 let previous_state = replace(&mut this.in_func_body, true);
861 // Resolve the function body, potentially inside the body of an async closure
862 this.with_lifetime_rib(
863 LifetimeRibKind::AnonymousPassThrough(fn_id, false),
864 |this| this.visit_block(body),
867 debug!("(resolving function) leaving function");
868 this.in_func_body = previous_state;
871 FnKind::Closure(binder, declaration, body) => {
872 this.visit_closure_binder(binder);
874 this.with_lifetime_rib(
876 // We do not have any explicit generic lifetime parameter.
877 ClosureBinder::NotPresent => {
878 LifetimeRibKind::AnonymousCreateParameter {
880 report_in_path: false,
883 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
885 // Add each argument to the rib.
886 |this| this.resolve_params(&declaration.inputs),
888 this.with_lifetime_rib(
890 ClosureBinder::NotPresent => {
891 LifetimeRibKind::AnonymousPassThrough(fn_id, true)
893 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
895 |this| visit::walk_fn_ret_ty(this, &declaration.output),
898 // Ignore errors in function bodies if this is rustdoc
899 // Be sure not to set this until the function signature has been resolved.
900 let previous_state = replace(&mut this.in_func_body, true);
901 // Resolve the function body, potentially inside the body of an async closure
902 this.with_lifetime_rib(
903 LifetimeRibKind::AnonymousPassThrough(fn_id, false),
904 |this| this.visit_expr(body),
907 debug!("(resolving function) leaving function");
908 this.in_func_body = previous_state;
913 self.diagnostic_metadata.current_function = previous_value;
915 fn visit_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
916 self.resolve_lifetime(lifetime, use_ctxt)
919 fn visit_generics(&mut self, generics: &'ast Generics) {
920 self.visit_generic_params(
922 self.diagnostic_metadata.current_self_item.is_some(),
924 for p in &generics.where_clause.predicates {
925 self.visit_where_predicate(p);
929 fn visit_closure_binder(&mut self, b: &'ast ClosureBinder) {
931 ClosureBinder::NotPresent => {}
932 ClosureBinder::For { generic_params, .. } => {
933 self.visit_generic_params(
935 self.diagnostic_metadata.current_self_item.is_some(),
941 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
942 debug!("visit_generic_arg({:?})", arg);
943 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
945 GenericArg::Type(ref ty) => {
946 // We parse const arguments as path types as we cannot distinguish them during
947 // parsing. We try to resolve that ambiguity by attempting resolution the type
948 // namespace first, and if that fails we try again in the value namespace. If
949 // resolution in the value namespace succeeds, we have an generic const argument on
951 if let TyKind::Path(ref qself, ref path) = ty.kind {
952 // We cannot disambiguate multi-segment paths right now as that requires type
954 if path.segments.len() == 1 && path.segments[0].args.is_none() {
955 let mut check_ns = |ns| {
956 self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns)
959 if !check_ns(TypeNS) && check_ns(ValueNS) {
960 // This must be equivalent to `visit_anon_const`, but we cannot call it
961 // directly due to visitor lifetimes so we have to copy-paste some code.
963 // Note that we might not be inside of an repeat expression here,
964 // but considering that `IsRepeatExpr` is only relevant for
965 // non-trivial constants this is doesn't matter.
966 self.with_constant_rib(
968 HasGenericParams::Yes,
971 this.smart_resolve_path(
975 PathSource::Expr(None),
978 if let Some(ref qself) = *qself {
979 this.visit_ty(&qself.ty);
981 this.visit_path(path, ty.id);
985 self.diagnostic_metadata.currently_processing_generics = prev;
993 GenericArg::Lifetime(lt) => self.visit_lifetime(lt, visit::LifetimeCtxt::GenericArg),
994 GenericArg::Const(ct) => self.visit_anon_const(ct),
996 self.diagnostic_metadata.currently_processing_generics = prev;
999 fn visit_assoc_constraint(&mut self, constraint: &'ast AssocConstraint) {
1000 self.visit_ident(constraint.ident);
1001 if let Some(ref gen_args) = constraint.gen_args {
1002 // Forbid anonymous lifetimes in GAT parameters until proper semantics are decided.
1003 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1004 this.visit_generic_args(gen_args.span(), gen_args)
1007 match constraint.kind {
1008 AssocConstraintKind::Equality { ref term } => match term {
1009 Term::Ty(ty) => self.visit_ty(ty),
1010 Term::Const(c) => self.visit_anon_const(c),
1012 AssocConstraintKind::Bound { ref bounds } => {
1013 walk_list!(self, visit_param_bound, bounds, BoundKind::Bound);
1018 fn visit_path_segment(&mut self, path_span: Span, path_segment: &'ast PathSegment) {
1019 if let Some(ref args) = path_segment.args {
1021 GenericArgs::AngleBracketed(..) => visit::walk_generic_args(self, path_span, args),
1022 GenericArgs::Parenthesized(p_args) => {
1023 // Probe the lifetime ribs to know how to behave.
1024 for rib in self.lifetime_ribs.iter().rev() {
1026 // We are inside a `PolyTraitRef`. The lifetimes are
1027 // to be intoduced in that (maybe implicit) `for<>` binder.
1028 LifetimeRibKind::Generics {
1030 kind: LifetimeBinderKind::PolyTrait,
1033 self.with_lifetime_rib(
1034 LifetimeRibKind::AnonymousCreateParameter {
1036 report_in_path: false,
1038 |this| walk_list!(this, visit_ty, &p_args.inputs),
1040 self.with_lifetime_rib(
1041 LifetimeRibKind::AnonymousPassThrough(binder, true),
1042 |this| visit::walk_fn_ret_ty(this, &p_args.output),
1046 // We have nowhere to introduce generics. Code is malformed,
1047 // so use regular lifetime resolution to avoid spurious errors.
1048 LifetimeRibKind::Item | LifetimeRibKind::Generics { .. } => {
1049 visit::walk_generic_args(self, path_span, args);
1052 LifetimeRibKind::AnonymousPassThrough(..)
1053 | LifetimeRibKind::AnonymousCreateParameter { .. }
1054 | LifetimeRibKind::AnonymousReportError
1055 | LifetimeRibKind::AnonConst
1056 | LifetimeRibKind::ConstGeneric => {}
1064 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
1065 debug!("visit_where_predicate {:?}", p);
1066 let previous_value =
1067 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
1068 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1069 if let WherePredicate::BoundPredicate(WhereBoundPredicate {
1072 ref bound_generic_params,
1073 span: predicate_span,
1077 let span = predicate_span.shrink_to_lo().to(bounded_ty.span.shrink_to_lo());
1078 this.with_generic_param_rib(
1079 &bound_generic_params,
1081 LifetimeRibKind::Generics {
1082 binder: bounded_ty.id,
1083 kind: LifetimeBinderKind::WhereBound,
1087 this.visit_generic_params(&bound_generic_params, false);
1088 this.visit_ty(bounded_ty);
1089 for bound in bounds {
1090 this.visit_param_bound(bound, BoundKind::Bound)
1095 visit::walk_where_predicate(this, p);
1098 self.diagnostic_metadata.current_where_predicate = previous_value;
1101 fn visit_inline_asm(&mut self, asm: &'ast InlineAsm) {
1102 for (op, _) in &asm.operands {
1104 InlineAsmOperand::In { expr, .. }
1105 | InlineAsmOperand::Out { expr: Some(expr), .. }
1106 | InlineAsmOperand::InOut { expr, .. } => self.visit_expr(expr),
1107 InlineAsmOperand::Out { expr: None, .. } => {}
1108 InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
1109 self.visit_expr(in_expr);
1110 if let Some(out_expr) = out_expr {
1111 self.visit_expr(out_expr);
1114 InlineAsmOperand::Const { anon_const, .. } => {
1115 // Although this is `DefKind::AnonConst`, it is allowed to reference outer
1116 // generic parameters like an inline const.
1117 self.resolve_inline_const(anon_const);
1119 InlineAsmOperand::Sym { sym } => self.visit_inline_asm_sym(sym),
1124 fn visit_inline_asm_sym(&mut self, sym: &'ast InlineAsmSym) {
1125 // This is similar to the code for AnonConst.
1126 self.with_rib(ValueNS, InlineAsmSymRibKind, |this| {
1127 this.with_rib(TypeNS, InlineAsmSymRibKind, |this| {
1128 this.with_label_rib(InlineAsmSymRibKind, |this| {
1129 this.smart_resolve_path(
1133 PathSource::Expr(None),
1135 visit::walk_inline_asm_sym(this, sym);
1142 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
1143 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
1144 // During late resolution we only track the module component of the parent scope,
1145 // although it may be useful to track other components as well for diagnostics.
1146 let graph_root = resolver.graph_root;
1147 let parent_scope = ParentScope::module(graph_root, resolver);
1148 let start_rib_kind = ModuleRibKind(graph_root);
1149 LateResolutionVisitor {
1153 value_ns: vec![Rib::new(start_rib_kind)],
1154 type_ns: vec![Rib::new(start_rib_kind)],
1155 macro_ns: vec![Rib::new(start_rib_kind)],
1157 label_ribs: Vec::new(),
1158 lifetime_ribs: Vec::new(),
1159 current_trait_ref: None,
1160 diagnostic_metadata: DiagnosticMetadata::default(),
1161 // errors at module scope should always be reported
1162 in_func_body: false,
1163 lifetime_uses: Default::default(),
1167 fn maybe_resolve_ident_in_lexical_scope(
1171 ) -> Option<LexicalScopeBinding<'a>> {
1172 self.r.resolve_ident_in_lexical_scope(
1182 fn resolve_ident_in_lexical_scope(
1186 finalize: Option<Finalize>,
1187 ignore_binding: Option<&'a NameBinding<'a>>,
1188 ) -> Option<LexicalScopeBinding<'a>> {
1189 self.r.resolve_ident_in_lexical_scope(
1202 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1203 finalize: Option<Finalize>,
1204 ) -> PathResult<'a> {
1205 self.r.resolve_path_with_ribs(
1217 // We maintain a list of value ribs and type ribs.
1219 // Simultaneously, we keep track of the current position in the module
1220 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
1221 // the value or type namespaces, we first look through all the ribs and
1222 // then query the module graph. When we resolve a name in the module
1223 // namespace, we can skip all the ribs (since nested modules are not
1224 // allowed within blocks in Rust) and jump straight to the current module
1227 // Named implementations are handled separately. When we find a method
1228 // call, we consult the module node to find all of the implementations in
1229 // scope. This information is lazily cached in the module node. We then
1230 // generate a fake "implementation scope" containing all the
1231 // implementations thus found, for compatibility with old resolve pass.
1233 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
1238 work: impl FnOnce(&mut Self) -> T,
1240 self.ribs[ns].push(Rib::new(kind));
1241 let ret = work(self);
1242 self.ribs[ns].pop();
1246 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
1247 if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
1248 // Move down in the graph.
1249 let orig_module = replace(&mut self.parent_scope.module, module);
1250 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
1251 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
1253 this.parent_scope.module = orig_module;
1262 fn visit_generic_params(&mut self, params: &'ast [GenericParam], add_self_upper: bool) {
1263 // For type parameter defaults, we have to ban access
1264 // to following type parameters, as the InternalSubsts can only
1265 // provide previous type parameters as they're built. We
1266 // put all the parameters on the ban list and then remove
1267 // them one by one as they are processed and become available.
1268 let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1269 let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1270 for param in params.iter() {
1272 GenericParamKind::Type { .. } => {
1275 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1277 GenericParamKind::Const { .. } => {
1278 forward_const_ban_rib
1280 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1282 GenericParamKind::Lifetime => {}
1286 // rust-lang/rust#61631: The type `Self` is essentially
1287 // another type parameter. For ADTs, we consider it
1288 // well-defined only after all of the ADT type parameters have
1289 // been provided. Therefore, we do not allow use of `Self`
1290 // anywhere in ADT type parameter defaults.
1292 // (We however cannot ban `Self` for defaults on *all* generic
1293 // lists; e.g. trait generics can usefully refer to `Self`,
1294 // such as in the case of `trait Add<Rhs = Self>`.)
1296 // (`Some` if + only if we are in ADT's generics.)
1297 forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
1300 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1301 for param in params {
1303 GenericParamKind::Lifetime => {
1304 for bound in ¶m.bounds {
1305 this.visit_param_bound(bound, BoundKind::Bound);
1308 GenericParamKind::Type { ref default } => {
1309 for bound in ¶m.bounds {
1310 this.visit_param_bound(bound, BoundKind::Bound);
1313 if let Some(ref ty) = default {
1314 this.ribs[TypeNS].push(forward_ty_ban_rib);
1315 this.ribs[ValueNS].push(forward_const_ban_rib);
1317 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1318 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1321 // Allow all following defaults to refer to this type parameter.
1324 .remove(&Ident::with_dummy_span(param.ident.name));
1326 GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
1327 // Const parameters can't have param bounds.
1328 assert!(param.bounds.is_empty());
1330 this.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
1331 this.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
1332 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1335 this.ribs[TypeNS].pop().unwrap();
1336 this.ribs[ValueNS].pop().unwrap();
1338 if let Some(ref expr) = default {
1339 this.ribs[TypeNS].push(forward_ty_ban_rib);
1340 this.ribs[ValueNS].push(forward_const_ban_rib);
1341 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1342 this.resolve_anon_const(expr, IsRepeatExpr::No)
1344 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1345 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1348 // Allow all following defaults to refer to this const parameter.
1349 forward_const_ban_rib
1351 .remove(&Ident::with_dummy_span(param.ident.name));
1358 #[tracing::instrument(level = "debug", skip(self, work))]
1359 fn with_lifetime_rib<T>(
1361 kind: LifetimeRibKind,
1362 work: impl FnOnce(&mut Self) -> T,
1364 self.lifetime_ribs.push(LifetimeRib::new(kind));
1365 let ret = work(self);
1366 self.lifetime_ribs.pop();
1370 #[tracing::instrument(level = "debug", skip(self))]
1371 fn resolve_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
1372 let ident = lifetime.ident;
1374 if ident.name == kw::StaticLifetime {
1375 self.record_lifetime_res(lifetime.id, LifetimeRes::Static);
1379 if ident.name == kw::UnderscoreLifetime {
1380 return self.resolve_anonymous_lifetime(lifetime, false);
1383 let mut indices = (0..self.lifetime_ribs.len()).rev();
1384 for i in &mut indices {
1385 let rib = &self.lifetime_ribs[i];
1386 let normalized_ident = ident.normalize_to_macros_2_0();
1387 if let Some(&(_, res)) = rib.bindings.get(&normalized_ident) {
1388 self.record_lifetime_res(lifetime.id, res);
1390 if let LifetimeRes::Param { param, .. } = res {
1391 match self.lifetime_uses.entry(param) {
1392 Entry::Vacant(v) => {
1393 debug!("First use of {:?} at {:?}", res, ident.span);
1398 .find_map(|rib| match rib.kind {
1399 // Do not suggest eliding a lifetime where an anonymous
1400 // lifetime would be illegal.
1401 LifetimeRibKind::Item
1402 | LifetimeRibKind::AnonymousPassThrough(_, true)
1403 | LifetimeRibKind::AnonymousReportError => {
1404 Some(LifetimeUseSet::Many)
1406 // An anonymous lifetime is legal here, go ahead.
1407 LifetimeRibKind::AnonymousPassThrough(_, false)
1408 | LifetimeRibKind::AnonymousCreateParameter { .. } => {
1409 Some(LifetimeUseSet::One { use_span: ident.span, use_ctxt })
1411 LifetimeRibKind::Generics { .. }
1412 | LifetimeRibKind::ConstGeneric
1413 | LifetimeRibKind::AnonConst => None,
1415 .unwrap_or(LifetimeUseSet::Many);
1416 debug!(?use_ctxt, ?use_set);
1419 Entry::Occupied(mut o) => {
1420 debug!("Many uses of {:?} at {:?}", res, ident.span);
1421 *o.get_mut() = LifetimeUseSet::Many;
1429 LifetimeRibKind::Item => break,
1430 LifetimeRibKind::ConstGeneric => {
1431 self.emit_non_static_lt_in_const_generic_error(lifetime);
1432 self.r.lifetimes_res_map.insert(lifetime.id, LifetimeRes::Error);
1435 LifetimeRibKind::AnonConst => {
1436 self.maybe_emit_forbidden_non_static_lifetime_error(lifetime);
1437 self.r.lifetimes_res_map.insert(lifetime.id, LifetimeRes::Error);
1444 let mut outer_res = None;
1446 let rib = &self.lifetime_ribs[i];
1447 let normalized_ident = ident.normalize_to_macros_2_0();
1448 if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) {
1449 outer_res = Some(outer);
1454 self.emit_undeclared_lifetime_error(lifetime, outer_res);
1455 self.record_lifetime_res(lifetime.id, LifetimeRes::Error);
1458 #[tracing::instrument(level = "debug", skip(self))]
1459 fn resolve_anonymous_lifetime(&mut self, lifetime: &Lifetime, elided: bool) {
1460 debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
1462 for i in (0..self.lifetime_ribs.len()).rev() {
1463 let rib = &mut self.lifetime_ribs[i];
1465 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1466 let res = self.create_fresh_lifetime(lifetime.id, lifetime.ident, binder);
1467 self.record_lifetime_res(lifetime.id, res);
1470 LifetimeRibKind::AnonymousReportError => {
1471 let (msg, note) = if elided {
1473 "`&` without an explicit lifetime name cannot be used here",
1474 "explicit lifetime name needed here",
1477 ("`'_` cannot be used here", "`'_` is a reserved lifetime name")
1479 rustc_errors::struct_span_err!(
1481 lifetime.ident.span,
1486 .span_label(lifetime.ident.span, note)
1489 self.record_lifetime_res(lifetime.id, LifetimeRes::Error);
1492 LifetimeRibKind::AnonymousPassThrough(node_id, _) => {
1493 self.record_lifetime_res(
1495 LifetimeRes::Anonymous { binder: node_id, elided },
1499 LifetimeRibKind::Item => break,
1500 LifetimeRibKind::Generics { .. }
1501 | LifetimeRibKind::ConstGeneric
1502 | LifetimeRibKind::AnonConst => {}
1505 // This resolution is wrong, it passes the work to HIR lifetime resolution.
1506 // We cannot use `LifetimeRes::Error` because we do not emit a diagnostic.
1507 self.record_lifetime_res(
1509 LifetimeRes::Anonymous { binder: DUMMY_NODE_ID, elided },
1513 #[tracing::instrument(level = "debug", skip(self))]
1514 fn resolve_elided_lifetime(&mut self, anchor_id: NodeId, span: Span) {
1515 let id = self.r.next_node_id();
1516 self.record_lifetime_res(
1518 LifetimeRes::ElidedAnchor { start: id, end: NodeId::from_u32(id.as_u32() + 1) },
1521 let lt = Lifetime { id, ident: Ident::new(kw::UnderscoreLifetime, span) };
1522 self.resolve_anonymous_lifetime(<, true);
1525 #[tracing::instrument(level = "debug", skip(self))]
1526 fn create_fresh_lifetime(&mut self, id: NodeId, ident: Ident, binder: NodeId) -> LifetimeRes {
1527 debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
1528 debug!(?ident.span);
1530 // Leave the responsibility to create the `LocalDefId` to lowering.
1531 let param = self.r.next_node_id();
1532 let res = LifetimeRes::Fresh { param, binder };
1534 // Record the created lifetime parameter so lowering can pick it up and add it to HIR.
1536 .extra_lifetime_params_map
1538 .or_insert_with(Vec::new)
1539 .push((ident, param, res));
1543 #[tracing::instrument(level = "debug", skip(self))]
1544 fn resolve_elided_lifetimes_in_path(
1547 partial_res: PartialRes,
1549 source: PathSource<'_>,
1552 let proj_start = path.len() - partial_res.unresolved_segments();
1553 for (i, segment) in path.iter().enumerate() {
1554 if segment.has_lifetime_args {
1557 let Some(segment_id) = segment.id else {
1561 // Figure out if this is a type/trait segment,
1562 // which may need lifetime elision performed.
1563 let type_def_id = match partial_res.base_res() {
1564 Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => self.r.parent(def_id),
1565 Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => self.r.parent(def_id),
1566 Res::Def(DefKind::Struct, def_id)
1567 | Res::Def(DefKind::Union, def_id)
1568 | Res::Def(DefKind::Enum, def_id)
1569 | Res::Def(DefKind::TyAlias, def_id)
1570 | Res::Def(DefKind::Trait, def_id)
1571 if i + 1 == proj_start =>
1578 let expected_lifetimes = self.r.item_generics_num_lifetimes(type_def_id);
1579 if expected_lifetimes == 0 {
1583 let missing = match source {
1584 PathSource::Trait(..) | PathSource::TraitItem(..) | PathSource::Type => true,
1585 PathSource::Expr(..)
1587 | PathSource::Struct
1588 | PathSource::TupleStruct(..) => false,
1591 let elided_lifetime_span = if segment.has_generic_args {
1592 // If there are brackets, but not generic arguments, then use the opening bracket
1593 segment.args_span.with_hi(segment.args_span.lo() + BytePos(1))
1595 // If there are no brackets, use the identifier span.
1596 // HACK: we use find_ancestor_inside to properly suggest elided spans in paths
1597 // originating from macros, since the segment's span might be from a macro arg.
1598 segment.ident.span.find_ancestor_inside(path_span).unwrap_or(path_span)
1600 let ident = Ident::new(kw::UnderscoreLifetime, elided_lifetime_span);
1602 let node_ids = self.r.next_node_ids(expected_lifetimes);
1603 self.record_lifetime_res(
1605 LifetimeRes::ElidedAnchor { start: node_ids.start, end: node_ids.end },
1609 // Do not create a parameter for patterns and expressions.
1610 for rib in self.lifetime_ribs.iter().rev() {
1612 LifetimeRibKind::AnonymousPassThrough(binder, _) => {
1613 let res = LifetimeRes::Anonymous { binder, elided: true };
1614 for id in node_ids {
1615 self.record_lifetime_res(id, res);
1619 // `LifetimeRes::Error`, which would usually be used in the case of
1620 // `ReportError`, is unsuitable here, as we don't emit an error yet. Instead,
1621 // we simply resolve to an implicit lifetime, which will be checked later, at
1622 // which point a suitable error will be emitted.
1623 LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
1624 // FIXME(cjgillot) This resolution is wrong, but this does not matter
1625 // since these cases are erroneous anyway. Lifetime resolution should
1626 // emit a "missing lifetime specifier" diagnostic.
1628 LifetimeRes::Anonymous { binder: DUMMY_NODE_ID, elided: true };
1629 for id in node_ids {
1630 self.record_lifetime_res(id, res);
1634 LifetimeRibKind::AnonymousCreateParameter { .. }
1635 | LifetimeRibKind::Generics { .. }
1636 | LifetimeRibKind::ConstGeneric
1637 | LifetimeRibKind::AnonConst => {}
1643 let mut should_lint = true;
1644 for rib in self.lifetime_ribs.iter().rev() {
1646 // In create-parameter mode we error here because we don't want to support
1647 // deprecated impl elision in new features like impl elision and `async fn`,
1648 // both of which work using the `CreateParameter` mode:
1650 // impl Foo for std::cell::Ref<u32> // note lack of '_
1651 // async fn foo(_: std::cell::Ref<u32>) { ... }
1652 LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. } => {
1653 let sess = self.r.session;
1654 let mut err = rustc_errors::struct_span_err!(
1658 "implicit elided lifetime not allowed here"
1660 rustc_errors::add_elided_lifetime_in_path_suggestion(
1665 !segment.has_generic_args,
1666 elided_lifetime_span,
1668 err.note("assuming a `'static` lifetime...");
1670 should_lint = false;
1672 for id in node_ids {
1673 self.record_lifetime_res(id, LifetimeRes::Error);
1677 // Do not create a parameter for patterns and expressions.
1678 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1679 for id in node_ids {
1680 let res = self.create_fresh_lifetime(id, ident, binder);
1681 self.record_lifetime_res(id, res);
1685 // `PassThrough` is the normal case.
1686 LifetimeRibKind::AnonymousPassThrough(binder, _) => {
1687 let res = LifetimeRes::Anonymous { binder, elided: true };
1688 for id in node_ids {
1689 self.record_lifetime_res(id, res);
1693 // `LifetimeRes::Error`, which would usually be used in the case of
1694 // `ReportError`, is unsuitable here, as we don't emit an error yet. Instead,
1695 // we simply resolve to an implicit lifetime, which will be checked later, at
1696 // which point a suitable error will be emitted.
1697 LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
1698 // FIXME(cjgillot) This resolution is wrong, but this does not matter
1699 // since these cases are erroneous anyway. Lifetime resolution should
1700 // emit a "missing lifetime specifier" diagnostic.
1701 let res = LifetimeRes::Anonymous { binder: DUMMY_NODE_ID, elided: true };
1702 for id in node_ids {
1703 self.record_lifetime_res(id, res);
1707 LifetimeRibKind::Generics { .. }
1708 | LifetimeRibKind::ConstGeneric
1709 | LifetimeRibKind::AnonConst => {}
1714 self.r.lint_buffer.buffer_lint_with_diagnostic(
1715 lint::builtin::ELIDED_LIFETIMES_IN_PATHS,
1717 elided_lifetime_span,
1718 "hidden lifetime parameters in types are deprecated",
1719 lint::BuiltinLintDiagnostics::ElidedLifetimesInPaths(
1722 !segment.has_generic_args,
1723 elided_lifetime_span,
1730 #[tracing::instrument(level = "debug", skip(self))]
1731 fn record_lifetime_res(&mut self, id: NodeId, res: LifetimeRes) {
1732 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1734 "lifetime {:?} resolved multiple times ({:?} before, {:?} now)",
1740 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
1741 /// label and reports an error if the label is not found or is unreachable.
1742 fn resolve_label(&mut self, mut label: Ident) -> Result<(NodeId, Span), ResolutionError<'a>> {
1743 let mut suggestion = None;
1745 for i in (0..self.label_ribs.len()).rev() {
1746 let rib = &self.label_ribs[i];
1748 if let MacroDefinition(def) = rib.kind {
1749 // If an invocation of this macro created `ident`, give up on `ident`
1750 // and switch to `ident`'s source from the macro definition.
1751 if def == self.r.macro_def(label.span.ctxt()) {
1752 label.span.remove_mark();
1756 let ident = label.normalize_to_macro_rules();
1757 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
1758 let definition_span = ident.span;
1759 return if self.is_label_valid_from_rib(i) {
1760 Ok((*id, definition_span))
1762 Err(ResolutionError::UnreachableLabel {
1770 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
1771 // the first such label that is encountered.
1772 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
1775 Err(ResolutionError::UndeclaredLabel { name: label.name, suggestion })
1778 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
1779 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
1780 let ribs = &self.label_ribs[rib_index + 1..];
1783 if rib.kind.is_label_barrier() {
1791 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
1792 debug!("resolve_adt");
1793 self.with_current_self_item(item, |this| {
1794 this.with_generic_param_rib(
1796 ItemRibKind(HasGenericParams::Yes),
1797 LifetimeRibKind::Generics {
1799 kind: LifetimeBinderKind::Item,
1800 span: generics.span,
1803 let item_def_id = this.r.local_def_id(item.id).to_def_id();
1805 Res::SelfTy { trait_: None, alias_to: Some((item_def_id, false)) },
1807 visit::walk_item(this, item);
1815 fn future_proof_import(&mut self, use_tree: &UseTree) {
1816 let segments = &use_tree.prefix.segments;
1817 if !segments.is_empty() {
1818 let ident = segments[0].ident;
1819 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
1823 let nss = match use_tree.kind {
1824 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
1827 let report_error = |this: &Self, ns| {
1828 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
1829 if this.should_report_errs() {
1832 .span_err(ident.span, &format!("imports cannot refer to {}", what));
1837 match self.maybe_resolve_ident_in_lexical_scope(ident, ns) {
1838 Some(LexicalScopeBinding::Res(..)) => {
1839 report_error(self, ns);
1841 Some(LexicalScopeBinding::Item(binding)) => {
1842 if let Some(LexicalScopeBinding::Res(..)) =
1843 self.resolve_ident_in_lexical_scope(ident, ns, None, Some(binding))
1845 report_error(self, ns);
1851 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
1852 for (use_tree, _) in use_trees {
1853 self.future_proof_import(use_tree);
1858 fn resolve_item(&mut self, item: &'ast Item) {
1859 let name = item.ident.name;
1860 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
1863 ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
1864 self.with_generic_param_rib(
1866 ItemRibKind(HasGenericParams::Yes),
1867 LifetimeRibKind::Generics {
1869 kind: LifetimeBinderKind::Item,
1870 span: generics.span,
1872 |this| visit::walk_item(this, item),
1876 ItemKind::Fn(box Fn { ref generics, .. }) => {
1877 self.with_generic_param_rib(
1879 ItemRibKind(HasGenericParams::Yes),
1880 LifetimeRibKind::Generics {
1882 kind: LifetimeBinderKind::Function,
1883 span: generics.span,
1885 |this| visit::walk_item(this, item),
1889 ItemKind::Enum(_, ref generics)
1890 | ItemKind::Struct(_, ref generics)
1891 | ItemKind::Union(_, ref generics) => {
1892 self.resolve_adt(item, generics);
1895 ItemKind::Impl(box Impl {
1899 items: ref impl_items,
1902 self.diagnostic_metadata.current_impl_items = Some(impl_items);
1903 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
1904 self.diagnostic_metadata.current_impl_items = None;
1907 ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
1908 // Create a new rib for the trait-wide type parameters.
1909 self.with_generic_param_rib(
1911 ItemRibKind(HasGenericParams::Yes),
1912 LifetimeRibKind::Generics {
1914 kind: LifetimeBinderKind::Item,
1915 span: generics.span,
1918 let local_def_id = this.r.local_def_id(item.id).to_def_id();
1920 Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
1922 this.visit_generics(generics);
1923 walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);
1924 this.resolve_trait_items(items);
1931 ItemKind::TraitAlias(ref generics, ref bounds) => {
1932 // Create a new rib for the trait-wide type parameters.
1933 self.with_generic_param_rib(
1935 ItemRibKind(HasGenericParams::Yes),
1936 LifetimeRibKind::Generics {
1938 kind: LifetimeBinderKind::Item,
1939 span: generics.span,
1942 let local_def_id = this.r.local_def_id(item.id).to_def_id();
1944 Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
1946 this.visit_generics(generics);
1947 walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
1954 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
1955 self.with_scope(item.id, |this| {
1956 visit::walk_item(this, item);
1960 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
1961 self.with_item_rib(|this| {
1963 if let Some(expr) = expr {
1964 let constant_item_kind = match item.kind {
1965 ItemKind::Const(..) => ConstantItemKind::Const,
1966 ItemKind::Static(..) => ConstantItemKind::Static,
1967 _ => unreachable!(),
1969 // We already forbid generic params because of the above item rib,
1970 // so it doesn't matter whether this is a trivial constant.
1971 this.with_constant_rib(
1973 HasGenericParams::Yes,
1974 Some((item.ident, constant_item_kind)),
1975 |this| this.visit_expr(expr),
1981 ItemKind::Use(ref use_tree) => {
1982 self.future_proof_import(use_tree);
1985 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => {
1986 // do nothing, these are just around to be encoded
1989 ItemKind::GlobalAsm(_) => {
1990 visit::walk_item(self, item);
1993 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
1997 fn with_generic_param_rib<'c, F>(
1999 params: &'c [GenericParam],
2001 lifetime_kind: LifetimeRibKind,
2004 F: FnOnce(&mut Self),
2006 debug!("with_generic_param_rib");
2007 let LifetimeRibKind::Generics { binder, span: generics_span, kind: generics_kind, .. }
2008 = lifetime_kind else { panic!() };
2010 let mut function_type_rib = Rib::new(kind);
2011 let mut function_value_rib = Rib::new(kind);
2012 let mut function_lifetime_rib = LifetimeRib::new(lifetime_kind);
2013 let mut seen_bindings = FxHashMap::default();
2014 // Store all seen lifetimes names from outer scopes.
2015 let mut seen_lifetimes = FxHashSet::default();
2017 // We also can't shadow bindings from the parent item
2018 if let AssocItemRibKind = kind {
2019 let mut add_bindings_for_ns = |ns| {
2020 let parent_rib = self.ribs[ns]
2022 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
2023 .expect("associated item outside of an item");
2025 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
2027 add_bindings_for_ns(ValueNS);
2028 add_bindings_for_ns(TypeNS);
2031 // Forbid shadowing lifetime bindings
2032 for rib in self.lifetime_ribs.iter().rev() {
2033 seen_lifetimes.extend(rib.bindings.iter().map(|(ident, _)| *ident));
2034 if let LifetimeRibKind::Item = rib.kind {
2039 for param in params {
2040 let ident = param.ident.normalize_to_macros_2_0();
2041 debug!("with_generic_param_rib: {}", param.id);
2043 if let GenericParamKind::Lifetime = param.kind
2044 && let Some(&original) = seen_lifetimes.get(&ident)
2046 diagnostics::signal_lifetime_shadowing(self.r.session, original, param.ident);
2047 // Record lifetime res, so lowering knows there is something fishy.
2048 self.record_lifetime_res(param.id, LifetimeRes::Error);
2052 match seen_bindings.entry(ident) {
2053 Entry::Occupied(entry) => {
2054 let span = *entry.get();
2055 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
2056 self.report_error(param.ident.span, err);
2057 if let GenericParamKind::Lifetime = param.kind {
2058 // Record lifetime res, so lowering knows there is something fishy.
2059 self.record_lifetime_res(param.id, LifetimeRes::Error);
2063 Entry::Vacant(entry) => {
2064 entry.insert(param.ident.span);
2068 if param.ident.name == kw::UnderscoreLifetime {
2069 rustc_errors::struct_span_err!(
2073 "`'_` cannot be used here"
2075 .span_label(param.ident.span, "`'_` is a reserved lifetime name")
2077 // Record lifetime res, so lowering knows there is something fishy.
2078 self.record_lifetime_res(param.id, LifetimeRes::Error);
2082 if param.ident.name == kw::StaticLifetime {
2083 rustc_errors::struct_span_err!(
2087 "invalid lifetime parameter name: `{}`",
2090 .span_label(param.ident.span, "'static is a reserved lifetime name")
2092 // Record lifetime res, so lowering knows there is something fishy.
2093 self.record_lifetime_res(param.id, LifetimeRes::Error);
2097 let def_id = self.r.local_def_id(param.id);
2099 // Plain insert (no renaming).
2100 let (rib, def_kind) = match param.kind {
2101 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
2102 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
2103 GenericParamKind::Lifetime => {
2104 let res = LifetimeRes::Param { param: def_id, binder };
2105 self.record_lifetime_res(param.id, res);
2106 function_lifetime_rib.bindings.insert(ident, (param.id, res));
2111 let res = match kind {
2112 ItemRibKind(..) | AssocItemRibKind => Res::Def(def_kind, def_id.to_def_id()),
2113 NormalRibKind => Res::Err,
2114 _ => bug!("Unexpected rib kind {:?}", kind),
2116 self.r.record_partial_res(param.id, PartialRes::new(res));
2117 rib.bindings.insert(ident, res);
2120 self.lifetime_ribs.push(function_lifetime_rib);
2121 self.ribs[ValueNS].push(function_value_rib);
2122 self.ribs[TypeNS].push(function_type_rib);
2126 self.ribs[TypeNS].pop();
2127 self.ribs[ValueNS].pop();
2128 self.lifetime_ribs.pop();
2130 if let LifetimeBinderKind::BareFnType
2131 | LifetimeBinderKind::WhereBound
2132 | LifetimeBinderKind::Function
2133 | LifetimeBinderKind::ImplBlock = generics_kind
2135 self.maybe_report_lifetime_uses(generics_span, params)
2139 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
2140 self.label_ribs.push(Rib::new(kind));
2142 self.label_ribs.pop();
2145 fn with_item_rib(&mut self, f: impl FnOnce(&mut Self)) {
2146 let kind = ItemRibKind(HasGenericParams::No);
2147 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
2148 this.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
2152 // HACK(min_const_generics,const_evaluatable_unchecked): We
2153 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
2154 // with a future compat lint for now. We do this by adding an
2155 // additional special case for repeat expressions.
2157 // Note that we intentionally still forbid `[0; N + 1]` during
2158 // name resolution so that we don't extend the future
2159 // compat lint to new cases.
2160 #[instrument(level = "debug", skip(self, f))]
2161 fn with_constant_rib(
2163 is_repeat: IsRepeatExpr,
2164 may_use_generics: HasGenericParams,
2165 item: Option<(Ident, ConstantItemKind)>,
2166 f: impl FnOnce(&mut Self),
2168 self.with_rib(ValueNS, ConstantItemRibKind(may_use_generics, item), |this| {
2171 ConstantItemRibKind(
2172 may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes),
2176 this.with_label_rib(ConstantItemRibKind(may_use_generics, item), f);
2182 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
2183 // Handle nested impls (inside fn bodies)
2184 let previous_value =
2185 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
2186 let result = f(self);
2187 self.diagnostic_metadata.current_self_type = previous_value;
2191 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
2192 let previous_value =
2193 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
2194 let result = f(self);
2195 self.diagnostic_metadata.current_self_item = previous_value;
2199 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
2200 fn resolve_trait_items(&mut self, trait_items: &'ast [P<AssocItem>]) {
2201 let trait_assoc_items =
2202 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
2204 let walk_assoc_item =
2205 |this: &mut Self, generics: &Generics, kind, item: &'ast AssocItem| {
2206 this.with_generic_param_rib(
2209 LifetimeRibKind::Generics { binder: item.id, span: generics.span, kind },
2210 |this| visit::walk_assoc_item(this, item, AssocCtxt::Trait),
2214 for item in trait_items {
2216 AssocItemKind::Const(_, ty, default) => {
2218 // Only impose the restrictions of `ConstRibKind` for an
2219 // actual constant expression in a provided default.
2220 if let Some(expr) = default {
2221 // We allow arbitrary const expressions inside of associated consts,
2222 // even if they are potentially not const evaluatable.
2224 // Type parameters can already be used and as associated consts are
2225 // not used as part of the type system, this is far less surprising.
2226 self.with_constant_rib(
2228 HasGenericParams::Yes,
2230 |this| this.visit_expr(expr),
2234 AssocItemKind::Fn(box Fn { generics, .. }) => {
2235 walk_assoc_item(self, generics, LifetimeBinderKind::Function, item);
2237 AssocItemKind::TyAlias(box TyAlias { generics, .. }) => {
2238 walk_assoc_item(self, generics, LifetimeBinderKind::Item, item);
2240 AssocItemKind::MacCall(_) => {
2241 panic!("unexpanded macro in resolve!")
2246 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
2249 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
2250 fn with_optional_trait_ref<T>(
2252 opt_trait_ref: Option<&TraitRef>,
2253 self_type: &'ast Ty,
2254 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
2256 let mut new_val = None;
2257 let mut new_id = None;
2258 if let Some(trait_ref) = opt_trait_ref {
2259 let path: Vec<_> = Segment::from_path(&trait_ref.path);
2260 self.diagnostic_metadata.currently_processing_impl_trait =
2261 Some((trait_ref.clone(), self_type.clone()));
2262 let res = self.smart_resolve_path_fragment(
2265 PathSource::Trait(AliasPossibility::No),
2266 Finalize::new(trait_ref.ref_id, trait_ref.path.span),
2268 self.diagnostic_metadata.currently_processing_impl_trait = None;
2269 if let Some(def_id) = res.base_res().opt_def_id() {
2270 new_id = Some(def_id);
2271 new_val = Some((self.r.expect_module(def_id), trait_ref.clone()));
2274 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
2275 let result = f(self, new_id);
2276 self.current_trait_ref = original_trait_ref;
2280 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
2281 let mut self_type_rib = Rib::new(NormalRibKind);
2283 // Plain insert (no renaming, since types are not currently hygienic)
2284 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
2285 self.ribs[ns].push(self_type_rib);
2287 self.ribs[ns].pop();
2290 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
2291 self.with_self_rib_ns(TypeNS, self_res, f)
2294 fn resolve_implementation(
2296 generics: &'ast Generics,
2297 opt_trait_reference: &'ast Option<TraitRef>,
2298 self_type: &'ast Ty,
2300 impl_items: &'ast [P<AssocItem>],
2302 debug!("resolve_implementation");
2303 // If applicable, create a rib for the type parameters.
2304 self.with_generic_param_rib(
2306 ItemRibKind(HasGenericParams::Yes),
2307 LifetimeRibKind::Generics {
2308 span: generics.span,
2310 kind: LifetimeBinderKind::ImplBlock
2313 // Dummy self type for better errors if `Self` is used in the trait path.
2314 this.with_self_rib(Res::SelfTy { trait_: None, alias_to: None }, |this| {
2315 this.with_lifetime_rib(
2316 LifetimeRibKind::AnonymousCreateParameter {
2318 report_in_path: true
2321 // Resolve the trait reference, if necessary.
2322 this.with_optional_trait_ref(
2323 opt_trait_reference.as_ref(),
2326 let item_def_id = this.r.local_def_id(item_id);
2328 // Register the trait definitions from here.
2329 if let Some(trait_id) = trait_id {
2330 this.r.trait_impls.entry(trait_id).or_default().push(item_def_id);
2333 let item_def_id = item_def_id.to_def_id();
2334 let res = Res::SelfTy {
2336 alias_to: Some((item_def_id, false)),
2338 this.with_self_rib(res, |this| {
2339 if let Some(trait_ref) = opt_trait_reference.as_ref() {
2340 // Resolve type arguments in the trait path.
2341 visit::walk_trait_ref(this, trait_ref);
2343 // Resolve the self type.
2344 this.visit_ty(self_type);
2345 // Resolve the generic parameters.
2346 this.visit_generics(generics);
2348 // Resolve the items within the impl.
2349 this.with_lifetime_rib(LifetimeRibKind::AnonymousPassThrough(item_id,false),
2351 this.with_current_self_type(self_type, |this| {
2352 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
2353 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
2354 for item in impl_items {
2355 this.resolve_impl_item(&**item);
2371 fn resolve_impl_item(&mut self, item: &'ast AssocItem) {
2372 use crate::ResolutionError::*;
2374 AssocItemKind::Const(_, ty, default) => {
2375 debug!("resolve_implementation AssocItemKind::Const");
2376 // If this is a trait impl, ensure the const
2378 self.check_trait_item(
2384 |i, s, c| ConstNotMemberOfTrait(i, s, c),
2388 if let Some(expr) = default {
2389 // We allow arbitrary const expressions inside of associated consts,
2390 // even if they are potentially not const evaluatable.
2392 // Type parameters can already be used and as associated consts are
2393 // not used as part of the type system, this is far less surprising.
2394 self.with_constant_rib(IsRepeatExpr::No, HasGenericParams::Yes, None, |this| {
2395 this.visit_expr(expr)
2399 AssocItemKind::Fn(box Fn { generics, .. }) => {
2400 debug!("resolve_implementation AssocItemKind::Fn");
2401 // We also need a new scope for the impl item type parameters.
2402 self.with_generic_param_rib(
2405 LifetimeRibKind::Generics {
2407 span: generics.span,
2408 kind: LifetimeBinderKind::Function,
2411 // If this is a trait impl, ensure the method
2413 this.check_trait_item(
2419 |i, s, c| MethodNotMemberOfTrait(i, s, c),
2422 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2426 AssocItemKind::TyAlias(box TyAlias { generics, .. }) => {
2427 debug!("resolve_implementation AssocItemKind::TyAlias");
2428 // We also need a new scope for the impl item type parameters.
2429 self.with_generic_param_rib(
2432 LifetimeRibKind::Generics {
2434 span: generics.span,
2435 kind: LifetimeBinderKind::Item,
2438 // If this is a trait impl, ensure the type
2440 this.check_trait_item(
2446 |i, s, c| TypeNotMemberOfTrait(i, s, c),
2449 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2453 AssocItemKind::MacCall(_) => {
2454 panic!("unexpanded macro in resolve!")
2459 fn check_trait_item<F>(
2463 kind: &AssocItemKind,
2468 F: FnOnce(Ident, String, Option<Symbol>) -> ResolutionError<'a>,
2470 // If there is a TraitRef in scope for an impl, then the method must be in the trait.
2471 let Some((module, _)) = &self.current_trait_ref else { return; };
2472 ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
2473 let key = self.r.new_key(ident, ns);
2474 let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2476 if binding.is_none() {
2477 // We could not find the trait item in the correct namespace.
2478 // Check the other namespace to report an error.
2484 let key = self.r.new_key(ident, ns);
2485 binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2488 let Some(binding) = binding else {
2489 // We could not find the method: report an error.
2490 let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
2491 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2492 let path_names = path_names_to_string(path);
2493 self.report_error(span, err(ident, path_names, candidate));
2497 let res = binding.res();
2498 let Res::Def(def_kind, _) = res else { bug!() };
2499 match (def_kind, kind) {
2500 (DefKind::AssocTy, AssocItemKind::TyAlias(..))
2501 | (DefKind::AssocFn, AssocItemKind::Fn(..))
2502 | (DefKind::AssocConst, AssocItemKind::Const(..)) => {
2503 self.r.record_partial_res(id, PartialRes::new(res));
2509 // The method kind does not correspond to what appeared in the trait, report.
2510 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2511 let (code, kind) = match kind {
2512 AssocItemKind::Const(..) => (rustc_errors::error_code!(E0323), "const"),
2513 AssocItemKind::Fn(..) => (rustc_errors::error_code!(E0324), "method"),
2514 AssocItemKind::TyAlias(..) => (rustc_errors::error_code!(E0325), "type"),
2515 AssocItemKind::MacCall(..) => span_bug!(span, "unexpanded macro"),
2517 let trait_path = path_names_to_string(path);
2520 ResolutionError::TraitImplMismatch {
2525 trait_item_span: binding.span,
2530 fn resolve_params(&mut self, params: &'ast [Param]) {
2531 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2532 for Param { pat, ty, .. } in params {
2533 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
2535 debug!("(resolving function / closure) recorded parameter");
2539 fn resolve_local(&mut self, local: &'ast Local) {
2540 debug!("resolving local ({:?})", local);
2541 // Resolve the type.
2542 walk_list!(self, visit_ty, &local.ty);
2544 // Resolve the initializer.
2545 if let Some((init, els)) = local.kind.init_else_opt() {
2546 self.visit_expr(init);
2548 // Resolve the `else` block
2549 if let Some(els) = els {
2550 self.visit_block(els);
2554 // Resolve the pattern.
2555 self.resolve_pattern_top(&local.pat, PatternSource::Let);
2558 /// build a map from pattern identifiers to binding-info's.
2559 /// this is done hygienically. This could arise for a macro
2560 /// that expands into an or-pattern where one 'x' was from the
2561 /// user and one 'x' came from the macro.
2562 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2563 let mut binding_map = FxHashMap::default();
2565 pat.walk(&mut |pat| {
2567 PatKind::Ident(binding_mode, ident, ref sub_pat)
2568 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
2570 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
2572 PatKind::Or(ref ps) => {
2573 // Check the consistency of this or-pattern and
2574 // then add all bindings to the larger map.
2575 for bm in self.check_consistent_bindings(ps) {
2576 binding_map.extend(bm);
2589 fn is_base_res_local(&self, nid: NodeId) -> bool {
2590 matches!(self.r.partial_res_map.get(&nid).map(|res| res.base_res()), Some(Res::Local(..)))
2593 /// Checks that all of the arms in an or-pattern have exactly the
2594 /// same set of bindings, with the same binding modes for each.
2595 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
2596 let mut missing_vars = FxHashMap::default();
2597 let mut inconsistent_vars = FxHashMap::default();
2599 // 1) Compute the binding maps of all arms.
2600 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
2602 // 2) Record any missing bindings or binding mode inconsistencies.
2603 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
2604 // Check against all arms except for the same pattern which is always self-consistent.
2608 .filter(|(_, pat)| pat.id != pat_outer.id)
2609 .flat_map(|(idx, _)| maps[idx].iter())
2610 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
2612 for (name, info, &binding_inner) in inners {
2615 // The inner binding is missing in the outer.
2617 missing_vars.entry(name).or_insert_with(|| BindingError {
2619 origin: BTreeSet::new(),
2620 target: BTreeSet::new(),
2621 could_be_path: name.as_str().starts_with(char::is_uppercase),
2623 binding_error.origin.insert(binding_inner.span);
2624 binding_error.target.insert(pat_outer.span);
2626 Some(binding_outer) => {
2627 if binding_outer.binding_mode != binding_inner.binding_mode {
2628 // The binding modes in the outer and inner bindings differ.
2631 .or_insert((binding_inner.span, binding_outer.span));
2638 // 3) Report all missing variables we found.
2639 let mut missing_vars = missing_vars.into_iter().collect::<Vec<_>>();
2640 missing_vars.sort_by_key(|&(sym, ref _err)| sym);
2642 for (name, mut v) in missing_vars.into_iter() {
2643 if inconsistent_vars.contains_key(&name) {
2644 v.could_be_path = false;
2647 *v.origin.iter().next().unwrap(),
2648 ResolutionError::VariableNotBoundInPattern(v, self.parent_scope),
2652 // 4) Report all inconsistencies in binding modes we found.
2653 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
2654 inconsistent_vars.sort();
2655 for (name, v) in inconsistent_vars {
2656 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
2659 // 5) Finally bubble up all the binding maps.
2663 /// Check the consistency of the outermost or-patterns.
2664 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
2665 pat.walk(&mut |pat| match pat.kind {
2666 PatKind::Or(ref ps) => {
2667 self.check_consistent_bindings(ps);
2674 fn resolve_arm(&mut self, arm: &'ast Arm) {
2675 self.with_rib(ValueNS, NormalRibKind, |this| {
2676 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
2677 walk_list!(this, visit_expr, &arm.guard);
2678 this.visit_expr(&arm.body);
2682 /// Arising from `source`, resolve a top level pattern.
2683 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
2684 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2685 self.resolve_pattern(pat, pat_src, &mut bindings);
2691 pat_src: PatternSource,
2692 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
2694 // We walk the pattern before declaring the pattern's inner bindings,
2695 // so that we avoid resolving a literal expression to a binding defined
2697 visit::walk_pat(self, pat);
2698 self.resolve_pattern_inner(pat, pat_src, bindings);
2699 // This has to happen *after* we determine which pat_idents are variants:
2700 self.check_consistent_bindings_top(pat);
2703 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
2707 /// A stack of sets of bindings accumulated.
2709 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
2710 /// be interpreted as re-binding an already bound binding. This results in an error.
2711 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
2712 /// in reusing this binding rather than creating a fresh one.
2714 /// When called at the top level, the stack must have a single element
2715 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
2716 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
2717 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
2718 /// When each `p_i` has been dealt with, the top set is merged with its parent.
2719 /// When a whole or-pattern has been dealt with, the thing happens.
2721 /// See the implementation and `fresh_binding` for more details.
2722 fn resolve_pattern_inner(
2725 pat_src: PatternSource,
2726 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
2728 // Visit all direct subpatterns of this pattern.
2729 pat.walk(&mut |pat| {
2730 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
2732 PatKind::Ident(bmode, ident, ref sub) => {
2733 // First try to resolve the identifier as some existing entity,
2734 // then fall back to a fresh binding.
2735 let has_sub = sub.is_some();
2737 .try_resolve_as_non_binding(pat_src, bmode, ident, has_sub)
2738 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
2739 self.r.record_partial_res(pat.id, PartialRes::new(res));
2740 self.r.record_pat_span(pat.id, pat.span);
2742 PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
2743 self.smart_resolve_path(
2747 PathSource::TupleStruct(
2749 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
2753 PatKind::Path(ref qself, ref path) => {
2754 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
2756 PatKind::Struct(ref qself, ref path, ..) => {
2757 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Struct);
2759 PatKind::Or(ref ps) => {
2760 // Add a new set of bindings to the stack. `Or` here records that when a
2761 // binding already exists in this set, it should not result in an error because
2762 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
2763 bindings.push((PatBoundCtx::Or, Default::default()));
2765 // Now we need to switch back to a product context so that each
2766 // part of the or-pattern internally rejects already bound names.
2767 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
2768 bindings.push((PatBoundCtx::Product, Default::default()));
2769 self.resolve_pattern_inner(p, pat_src, bindings);
2770 // Move up the non-overlapping bindings to the or-pattern.
2771 // Existing bindings just get "merged".
2772 let collected = bindings.pop().unwrap().1;
2773 bindings.last_mut().unwrap().1.extend(collected);
2775 // This or-pattern itself can itself be part of a product,
2776 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
2777 // Both cases bind `a` again in a product pattern and must be rejected.
2778 let collected = bindings.pop().unwrap().1;
2779 bindings.last_mut().unwrap().1.extend(collected);
2781 // Prevent visiting `ps` as we've already done so above.
2794 pat_src: PatternSource,
2795 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
2797 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
2798 // (We must not add it if it's in the bindings map because that breaks the assumptions
2799 // later passes make about or-patterns.)
2800 let ident = ident.normalize_to_macro_rules();
2802 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
2803 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
2804 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
2805 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
2806 // This is *required* for consistency which is checked later.
2807 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
2809 if already_bound_and {
2810 // Overlap in a product pattern somewhere; report an error.
2811 use ResolutionError::*;
2812 let error = match pat_src {
2813 // `fn f(a: u8, a: u8)`:
2814 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
2816 _ => IdentifierBoundMoreThanOnceInSamePattern,
2818 self.report_error(ident.span, error(ident.name));
2821 // Record as bound if it's valid:
2822 let ident_valid = ident.name != kw::Empty;
2824 bindings.last_mut().unwrap().1.insert(ident);
2827 if already_bound_or {
2828 // `Variant1(a) | Variant2(a)`, ok
2829 // Reuse definition from the first `a`.
2830 self.innermost_rib_bindings(ValueNS)[&ident]
2832 let res = Res::Local(pat_id);
2834 // A completely fresh binding add to the set if it's valid.
2835 self.innermost_rib_bindings(ValueNS).insert(ident, res);
2841 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
2842 &mut self.ribs[ns].last_mut().unwrap().bindings
2845 fn try_resolve_as_non_binding(
2847 pat_src: PatternSource,
2852 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
2853 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
2854 // also be interpreted as a path to e.g. a constant, variant, etc.
2855 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
2857 let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?;
2858 let (res, binding) = match ls_binding {
2859 LexicalScopeBinding::Item(binding)
2860 if is_syntactic_ambiguity && binding.is_ambiguity() =>
2862 // For ambiguous bindings we don't know all their definitions and cannot check
2863 // whether they can be shadowed by fresh bindings or not, so force an error.
2864 // issues/33118#issuecomment-233962221 (see below) still applies here,
2865 // but we have to ignore it for backward compatibility.
2866 self.r.record_use(ident, binding, false);
2869 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
2870 LexicalScopeBinding::Res(res) => (res, None),
2874 Res::SelfCtor(_) // See #70549.
2876 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
2878 ) if is_syntactic_ambiguity => {
2879 // Disambiguate in favor of a unit struct/variant or constant pattern.
2880 if let Some(binding) = binding {
2881 self.r.record_use(ident, binding, false);
2885 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static(_), _) => {
2886 // This is unambiguously a fresh binding, either syntactically
2887 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
2888 // to something unusable as a pattern (e.g., constructor function),
2889 // but we still conservatively report an error, see
2890 // issues/33118#issuecomment-233962221 for one reason why.
2891 let binding = binding.expect("no binding for a ctor or static");
2894 ResolutionError::BindingShadowsSomethingUnacceptable {
2895 shadowing_binding: pat_src,
2897 participle: if binding.is_import() { "imported" } else { "defined" },
2898 article: binding.res().article(),
2899 shadowed_binding: binding.res(),
2900 shadowed_binding_span: binding.span,
2905 Res::Def(DefKind::ConstParam, def_id) => {
2906 // Same as for DefKind::Const above, but here, `binding` is `None`, so we
2907 // have to construct the error differently
2910 ResolutionError::BindingShadowsSomethingUnacceptable {
2911 shadowing_binding: pat_src,
2913 participle: "defined",
2914 article: res.article(),
2915 shadowed_binding: res,
2916 shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"),
2921 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
2922 // These entities are explicitly allowed to be shadowed by fresh bindings.
2925 Res::SelfCtor(_) => {
2926 // We resolve `Self` in pattern position as an ident sometimes during recovery,
2927 // so delay a bug instead of ICEing.
2928 self.r.session.delay_span_bug(
2930 "unexpected `SelfCtor` in pattern, expected identifier"
2936 "unexpected resolution for an identifier in pattern: {:?}",
2942 // High-level and context dependent path resolution routine.
2943 // Resolves the path and records the resolution into definition map.
2944 // If resolution fails tries several techniques to find likely
2945 // resolution candidates, suggest imports or other help, and report
2946 // errors in user friendly way.
2947 fn smart_resolve_path(
2950 qself: Option<&QSelf>,
2952 source: PathSource<'ast>,
2954 self.smart_resolve_path_fragment(
2956 &Segment::from_path(path),
2958 Finalize::new(id, path.span),
2962 fn smart_resolve_path_fragment(
2964 qself: Option<&QSelf>,
2966 source: PathSource<'ast>,
2970 "smart_resolve_path_fragment(qself={:?}, path={:?}, finalize={:?})",
2975 let ns = source.namespace();
2977 let Finalize { node_id, path_span, .. } = finalize;
2978 let report_errors = |this: &mut Self, res: Option<Res>| {
2979 if this.should_report_errs() {
2980 let (err, candidates) =
2981 this.smart_resolve_report_errors(path, path_span, source, res);
2983 let def_id = this.parent_scope.module.nearest_parent_mod();
2984 let instead = res.is_some();
2986 if res.is_none() { this.report_missing_type_error(path) } else { None };
2988 this.r.use_injections.push(UseError {
2998 PartialRes::new(Res::Err)
3001 // For paths originating from calls (like in `HashMap::new()`), tries
3002 // to enrich the plain `failed to resolve: ...` message with hints
3003 // about possible missing imports.
3005 // Similar thing, for types, happens in `report_errors` above.
3006 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
3007 if !source.is_call() {
3008 return Some(parent_err);
3011 // Before we start looking for candidates, we have to get our hands
3012 // on the type user is trying to perform invocation on; basically:
3013 // we're transforming `HashMap::new` into just `HashMap`.
3014 let path = match path.split_last() {
3015 Some((_, path)) if !path.is_empty() => path,
3016 _ => return Some(parent_err),
3019 let (mut err, candidates) =
3020 this.smart_resolve_report_errors(path, path_span, PathSource::Type, None);
3022 if candidates.is_empty() {
3024 return Some(parent_err);
3027 // There are two different error messages user might receive at
3029 // - E0412 cannot find type `{}` in this scope
3030 // - E0433 failed to resolve: use of undeclared type or module `{}`
3032 // The first one is emitted for paths in type-position, and the
3033 // latter one - for paths in expression-position.
3035 // Thus (since we're in expression-position at this point), not to
3036 // confuse the user, we want to keep the *message* from E0432 (so
3037 // `parent_err`), but we want *hints* from E0412 (so `err`).
3039 // And that's what happens below - we're just mixing both messages
3040 // into a single one.
3041 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
3043 err.message = take(&mut parent_err.message);
3044 err.code = take(&mut parent_err.code);
3045 err.children = take(&mut parent_err.children);
3047 parent_err.cancel();
3049 let def_id = this.parent_scope.module.nearest_parent_mod();
3051 if this.should_report_errs() {
3052 this.r.use_injections.push(UseError {
3064 // We don't return `Some(parent_err)` here, because the error will
3065 // be already printed as part of the `use` injections
3069 let partial_res = match self.resolve_qpath_anywhere(
3074 source.defer_to_typeck(),
3077 Ok(Some(partial_res)) if partial_res.unresolved_segments() == 0 => {
3078 if source.is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err
3082 report_errors(self, Some(partial_res.base_res()))
3086 Ok(Some(partial_res)) if source.defer_to_typeck() => {
3087 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
3088 // or `<T>::A::B`. If `B` should be resolved in value namespace then
3089 // it needs to be added to the trait map.
3091 let item_name = path.last().unwrap().ident;
3092 let traits = self.traits_in_scope(item_name, ns);
3093 self.r.trait_map.insert(node_id, traits);
3096 if PrimTy::from_name(path[0].ident.name).is_some() {
3097 let mut std_path = Vec::with_capacity(1 + path.len());
3099 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
3100 std_path.extend(path);
3101 if let PathResult::Module(_) | PathResult::NonModule(_) =
3102 self.resolve_path(&std_path, Some(ns), None)
3104 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
3106 path.iter().last().map_or(path_span, |segment| segment.ident.span);
3108 self.r.confused_type_with_std_module.insert(item_span, path_span);
3109 self.r.confused_type_with_std_module.insert(path_span, path_span);
3117 if let Some(err) = report_errors_for_call(self, err) {
3118 self.report_error(err.span, err.node);
3121 PartialRes::new(Res::Err)
3124 _ => report_errors(self, None),
3127 if !matches!(source, PathSource::TraitItem(..)) {
3128 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
3129 self.r.record_partial_res(node_id, partial_res);
3130 self.resolve_elided_lifetimes_in_path(node_id, partial_res, path, source, path_span);
3136 fn self_type_is_available(&mut self) -> bool {
3138 .maybe_resolve_ident_in_lexical_scope(Ident::with_dummy_span(kw::SelfUpper), TypeNS);
3139 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3142 fn self_value_is_available(&mut self, self_span: Span) -> bool {
3143 let ident = Ident::new(kw::SelfLower, self_span);
3144 let binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS);
3145 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3148 /// A wrapper around [`Resolver::report_error`].
3150 /// This doesn't emit errors for function bodies if this is rustdoc.
3151 fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) {
3152 if self.should_report_errs() {
3153 self.r.report_error(span, resolution_error);
3158 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
3159 fn should_report_errs(&self) -> bool {
3160 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
3163 // Resolve in alternative namespaces if resolution in the primary namespace fails.
3164 fn resolve_qpath_anywhere(
3166 qself: Option<&QSelf>,
3168 primary_ns: Namespace,
3170 defer_to_typeck: bool,
3172 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3173 let mut fin_res = None;
3175 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
3176 if i == 0 || ns != primary_ns {
3177 match self.resolve_qpath(qself, path, ns, finalize)? {
3179 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
3181 return Ok(Some(partial_res));
3184 if fin_res.is_none() {
3185 fin_res = partial_res;
3192 assert!(primary_ns != MacroNS);
3194 if qself.is_none() {
3195 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
3196 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
3197 if let Ok((_, res)) =
3198 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
3200 return Ok(Some(PartialRes::new(res)));
3207 /// Handles paths that may refer to associated items.
3210 qself: Option<&QSelf>,
3214 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3216 "resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})",
3217 qself, path, ns, finalize,
3220 if let Some(qself) = qself {
3221 if qself.position == 0 {
3222 // This is a case like `<T>::B`, where there is no
3223 // trait to resolve. In that case, we leave the `B`
3224 // segment to be resolved by type-check.
3225 return Ok(Some(PartialRes::with_unresolved_segments(
3226 Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()),
3231 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
3233 // Currently, `path` names the full item (`A::B::C`, in
3234 // our example). so we extract the prefix of that that is
3235 // the trait (the slice upto and including
3236 // `qself.position`). And then we recursively resolve that,
3237 // but with `qself` set to `None`.
3238 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
3239 let partial_res = self.smart_resolve_path_fragment(
3241 &path[..=qself.position],
3242 PathSource::TraitItem(ns),
3243 Finalize::with_root_span(finalize.node_id, finalize.path_span, qself.path_span),
3246 // The remaining segments (the `C` in our example) will
3247 // have to be resolved by type-check, since that requires doing
3248 // trait resolution.
3249 return Ok(Some(PartialRes::with_unresolved_segments(
3250 partial_res.base_res(),
3251 partial_res.unresolved_segments() + path.len() - qself.position - 1,
3255 let result = match self.resolve_path(&path, Some(ns), Some(finalize)) {
3256 PathResult::NonModule(path_res) => path_res,
3257 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
3258 PartialRes::new(module.res().unwrap())
3260 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
3261 // don't report an error right away, but try to fallback to a primitive type.
3262 // So, we are still able to successfully resolve something like
3264 // use std::u8; // bring module u8 in scope
3265 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
3266 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
3267 // // not to non-existent std::u8::max_value
3270 // Such behavior is required for backward compatibility.
3271 // The same fallback is used when `a` resolves to nothing.
3272 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
3273 if (ns == TypeNS || path.len() > 1)
3274 && PrimTy::from_name(path[0].ident.name).is_some() =>
3276 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
3277 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
3279 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3280 PartialRes::new(module.res().unwrap())
3282 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
3283 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
3285 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
3286 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
3290 && result.base_res() != Res::Err
3291 && path[0].ident.name != kw::PathRoot
3292 && path[0].ident.name != kw::DollarCrate
3294 let unqualified_result = {
3295 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
3296 PathResult::NonModule(path_res) => path_res.base_res(),
3297 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3298 module.res().unwrap()
3300 _ => return Ok(Some(result)),
3303 if result.base_res() == unqualified_result {
3304 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
3305 self.r.lint_buffer.buffer_lint(
3309 "unnecessary qualification",
3317 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
3318 if let Some(label) = label {
3319 if label.ident.as_str().as_bytes()[1] != b'_' {
3320 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
3323 if let Ok((_, orig_span)) = self.resolve_label(label.ident) {
3324 diagnostics::signal_label_shadowing(self.r.session, orig_span, label.ident)
3327 self.with_label_rib(NormalRibKind, |this| {
3328 let ident = label.ident.normalize_to_macro_rules();
3329 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
3337 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
3338 self.with_resolved_label(label, id, |this| this.visit_block(block));
3341 fn resolve_block(&mut self, block: &'ast Block) {
3342 debug!("(resolving block) entering block");
3343 // Move down in the graph, if there's an anonymous module rooted here.
3344 let orig_module = self.parent_scope.module;
3345 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
3347 let mut num_macro_definition_ribs = 0;
3348 if let Some(anonymous_module) = anonymous_module {
3349 debug!("(resolving block) found anonymous module, moving down");
3350 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3351 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3352 self.parent_scope.module = anonymous_module;
3354 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3357 let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
3358 if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
3359 (block.could_be_bare_literal, &block.stmts[..])
3360 && let ExprKind::Type(..) = expr.kind
3362 self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
3365 // Descend into the block.
3366 for stmt in &block.stmts {
3367 if let StmtKind::Item(ref item) = stmt.kind
3368 && let ItemKind::MacroDef(..) = item.kind {
3369 num_macro_definition_ribs += 1;
3370 let res = self.r.local_def_id(item.id).to_def_id();
3371 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
3372 self.label_ribs.push(Rib::new(MacroDefinition(res)));
3375 self.visit_stmt(stmt);
3377 self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
3380 self.parent_scope.module = orig_module;
3381 for _ in 0..num_macro_definition_ribs {
3382 self.ribs[ValueNS].pop();
3383 self.label_ribs.pop();
3385 self.ribs[ValueNS].pop();
3386 if anonymous_module.is_some() {
3387 self.ribs[TypeNS].pop();
3389 debug!("(resolving block) leaving block");
3392 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
3393 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
3394 self.with_constant_rib(
3396 if constant.value.is_potential_trivial_const_param() {
3397 HasGenericParams::Yes
3399 HasGenericParams::No
3402 |this| visit::walk_anon_const(this, constant),
3406 fn resolve_inline_const(&mut self, constant: &'ast AnonConst) {
3407 debug!("resolve_anon_const {constant:?}");
3408 self.with_constant_rib(IsRepeatExpr::No, HasGenericParams::Yes, None, |this| {
3409 visit::walk_anon_const(this, constant);
3413 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
3414 // First, record candidate traits for this expression if it could
3415 // result in the invocation of a method call.
3417 self.record_candidate_traits_for_expr_if_necessary(expr);
3419 // Next, resolve the node.
3421 ExprKind::Path(ref qself, ref path) => {
3422 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
3423 visit::walk_expr(self, expr);
3426 ExprKind::Struct(ref se) => {
3427 self.smart_resolve_path(expr.id, se.qself.as_ref(), &se.path, PathSource::Struct);
3428 visit::walk_expr(self, expr);
3431 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
3432 match self.resolve_label(label.ident) {
3433 Ok((node_id, _)) => {
3434 // Since this res is a label, it is never read.
3435 self.r.label_res_map.insert(expr.id, node_id);
3436 self.diagnostic_metadata.unused_labels.remove(&node_id);
3439 self.report_error(label.ident.span, error);
3443 // visit `break` argument if any
3444 visit::walk_expr(self, expr);
3447 ExprKind::Break(None, Some(ref e)) => {
3448 // We use this instead of `visit::walk_expr` to keep the parent expr around for
3449 // better diagnostics.
3450 self.resolve_expr(e, Some(&expr));
3453 ExprKind::Let(ref pat, ref scrutinee, _) => {
3454 self.visit_expr(scrutinee);
3455 self.resolve_pattern_top(pat, PatternSource::Let);
3458 ExprKind::If(ref cond, ref then, ref opt_else) => {
3459 self.with_rib(ValueNS, NormalRibKind, |this| {
3460 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3461 this.visit_expr(cond);
3462 this.diagnostic_metadata.in_if_condition = old;
3463 this.visit_block(then);
3465 if let Some(expr) = opt_else {
3466 self.visit_expr(expr);
3470 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3472 ExprKind::While(ref cond, ref block, label) => {
3473 self.with_resolved_label(label, expr.id, |this| {
3474 this.with_rib(ValueNS, NormalRibKind, |this| {
3475 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3476 this.visit_expr(cond);
3477 this.diagnostic_metadata.in_if_condition = old;
3478 this.visit_block(block);
3483 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
3484 self.visit_expr(iter_expr);
3485 self.with_rib(ValueNS, NormalRibKind, |this| {
3486 this.resolve_pattern_top(pat, PatternSource::For);
3487 this.resolve_labeled_block(label, expr.id, block);
3491 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
3493 // Equivalent to `visit::walk_expr` + passing some context to children.
3494 ExprKind::Field(ref subexpression, _) => {
3495 self.resolve_expr(subexpression, Some(expr));
3497 ExprKind::MethodCall(ref segment, ref arguments, _) => {
3498 let mut arguments = arguments.iter();
3499 self.resolve_expr(arguments.next().unwrap(), Some(expr));
3500 for argument in arguments {
3501 self.resolve_expr(argument, None);
3503 self.visit_path_segment(expr.span, segment);
3506 ExprKind::Call(ref callee, ref arguments) => {
3507 self.resolve_expr(callee, Some(expr));
3508 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
3509 for (idx, argument) in arguments.iter().enumerate() {
3510 // Constant arguments need to be treated as AnonConst since
3511 // that is how they will be later lowered to HIR.
3512 if const_args.contains(&idx) {
3513 self.with_constant_rib(
3515 if argument.is_potential_trivial_const_param() {
3516 HasGenericParams::Yes
3518 HasGenericParams::No
3522 this.resolve_expr(argument, None);
3526 self.resolve_expr(argument, None);
3530 ExprKind::Type(ref type_expr, ref ty) => {
3531 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
3532 // type ascription. Here we are trying to retrieve the span of the colon token as
3533 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
3534 // with `expr::Ty`, only in this case it will match the span from
3535 // `type_ascription_path_suggestions`.
3536 self.diagnostic_metadata
3537 .current_type_ascription
3538 .push(type_expr.span.between(ty.span));
3539 visit::walk_expr(self, expr);
3540 self.diagnostic_metadata.current_type_ascription.pop();
3542 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
3543 // resolve the arguments within the proper scopes so that usages of them inside the
3544 // closure are detected as upvars rather than normal closure arg usages.
3545 ExprKind::Closure(_, _, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
3546 self.with_rib(ValueNS, NormalRibKind, |this| {
3547 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
3548 // Resolve arguments:
3549 this.resolve_params(&fn_decl.inputs);
3550 // No need to resolve return type --
3551 // the outer closure return type is `FnRetTy::Default`.
3553 // Now resolve the inner closure
3555 // No need to resolve arguments: the inner closure has none.
3556 // Resolve the return type:
3557 visit::walk_fn_ret_ty(this, &fn_decl.output);
3559 this.visit_expr(body);
3564 // For closures, ClosureOrAsyncRibKind is added in visit_fn
3565 ExprKind::Closure(ClosureBinder::For { ref generic_params, span }, ..) => {
3566 self.with_generic_param_rib(
3569 LifetimeRibKind::Generics {
3571 kind: LifetimeBinderKind::Closure,
3574 |this| visit::walk_expr(this, expr),
3577 ExprKind::Closure(..) => visit::walk_expr(self, expr),
3578 ExprKind::Async(..) => {
3579 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
3581 ExprKind::Repeat(ref elem, ref ct) => {
3582 self.visit_expr(elem);
3583 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
3584 this.resolve_anon_const(ct, IsRepeatExpr::Yes)
3587 ExprKind::ConstBlock(ref ct) => {
3588 self.resolve_inline_const(ct);
3590 ExprKind::Index(ref elem, ref idx) => {
3591 self.resolve_expr(elem, Some(expr));
3592 self.visit_expr(idx);
3595 visit::walk_expr(self, expr);
3600 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
3602 ExprKind::Field(_, ident) => {
3603 // FIXME(#6890): Even though you can't treat a method like a
3604 // field, we need to add any trait methods we find that match
3605 // the field name so that we can do some nice error reporting
3606 // later on in typeck.
3607 let traits = self.traits_in_scope(ident, ValueNS);
3608 self.r.trait_map.insert(expr.id, traits);
3610 ExprKind::MethodCall(ref segment, ..) => {
3611 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
3612 let traits = self.traits_in_scope(segment.ident, ValueNS);
3613 self.r.trait_map.insert(expr.id, traits);
3621 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
3622 self.r.traits_in_scope(
3623 self.current_trait_ref.as_ref().map(|(module, _)| *module),
3626 Some((ident.name, ns)),
3631 struct LifetimeCountVisitor<'a, 'b> {
3632 r: &'b mut Resolver<'a>,
3635 /// Walks the whole crate in DFS order, visiting each item, counting the declared number of
3636 /// lifetime generic parameters.
3637 impl<'ast> Visitor<'ast> for LifetimeCountVisitor<'_, '_> {
3638 fn visit_item(&mut self, item: &'ast Item) {
3640 ItemKind::TyAlias(box TyAlias { ref generics, .. })
3641 | ItemKind::Fn(box Fn { ref generics, .. })
3642 | ItemKind::Enum(_, ref generics)
3643 | ItemKind::Struct(_, ref generics)
3644 | ItemKind::Union(_, ref generics)
3645 | ItemKind::Impl(box Impl { ref generics, .. })
3646 | ItemKind::Trait(box Trait { ref generics, .. })
3647 | ItemKind::TraitAlias(ref generics, _) => {
3648 let def_id = self.r.local_def_id(item.id);
3649 let count = generics
3652 .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
3654 self.r.item_generics_num_lifetimes.insert(def_id, count);
3658 | ItemKind::ForeignMod(..)
3659 | ItemKind::Static(..)
3660 | ItemKind::Const(..)
3662 | ItemKind::ExternCrate(..)
3663 | ItemKind::MacroDef(..)
3664 | ItemKind::GlobalAsm(..)
3665 | ItemKind::MacCall(..) => {}
3667 visit::walk_item(self, item)
3671 impl<'a> Resolver<'a> {
3672 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
3673 visit::walk_crate(&mut LifetimeCountVisitor { r: self }, krate);
3674 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
3675 visit::walk_crate(&mut late_resolution_visitor, krate);
3676 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
3677 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");