1 //! "Late resolution" is the pass that resolves most of names in a crate beside imports and macros.
2 //! It runs when the crate is fully expanded and its module structure is fully built.
3 //! So it just walks through the crate and resolves all the expressions, types, etc.
5 //! If you wonder why there's no `early.rs`, that's because it's split into three files -
6 //! `build_reduced_graph.rs`, `macros.rs` and `imports.rs`.
10 use crate::{path_names_to_string, BindingError, Finalize, LexicalScopeBinding};
11 use crate::{Module, ModuleOrUniformRoot, NameBinding, ParentScope, PathResult};
12 use crate::{ResolutionError, Resolver, Segment, UseError};
14 use rustc_ast::ptr::P;
15 use rustc_ast::visit::{self, AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor};
17 use rustc_ast_lowering::{LifetimeRes, ResolverAstLowering};
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, PartialRes, PerNS};
22 use rustc_hir::def_id::{DefId, CRATE_DEF_ID};
23 use rustc_hir::definitions::DefPathData;
24 use rustc_hir::{PrimTy, TraitCandidate};
25 use rustc_index::vec::Idx;
26 use rustc_middle::ty::DefIdTree;
27 use rustc_middle::{bug, span_bug};
28 use rustc_session::lint;
29 use rustc_span::symbol::{kw, sym, Ident, Symbol};
30 use rustc_span::{BytePos, Span};
31 use smallvec::{smallvec, SmallVec};
33 use rustc_span::source_map::{respan, Spanned};
34 use std::collections::{hash_map::Entry, BTreeSet};
35 use std::mem::{replace, take};
41 type Res = def::Res<NodeId>;
43 type IdentMap<T> = FxHashMap<Ident, T>;
45 /// Map from the name in a pattern to its binding mode.
46 type BindingMap = IdentMap<BindingInfo>;
48 #[derive(Copy, Clone, Debug)]
51 binding_mode: BindingMode,
54 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
62 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
69 fn descr(self) -> &'static str {
71 PatternSource::Match => "match binding",
72 PatternSource::Let => "let binding",
73 PatternSource::For => "for binding",
74 PatternSource::FnParam => "function parameter",
79 /// Denotes whether the context for the set of already bound bindings is a `Product`
80 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
81 /// See those functions for more information.
84 /// A product pattern context, e.g., `Variant(a, b)`.
86 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
90 /// Does this the item (from the item rib scope) allow generic parameters?
91 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
92 crate enum HasGenericParams {
97 impl HasGenericParams {
98 fn force_yes_if(self, b: bool) -> Self {
99 if b { Self::Yes } else { self }
103 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
104 crate enum ConstantItemKind {
109 /// The rib kind restricts certain accesses,
110 /// e.g. to a `Res::Local` of an outer item.
111 #[derive(Copy, Clone, Debug)]
112 crate enum RibKind<'a> {
113 /// No restriction needs to be applied.
116 /// We passed through an impl or trait and are now in one of its
117 /// methods or associated types. Allow references to ty params that impl or trait
118 /// binds. Disallow any other upvars (including other ty params that are
122 /// We passed through a closure. Disallow labels.
123 ClosureOrAsyncRibKind,
125 /// We passed through a function definition. Disallow upvars.
126 /// Permit only those const parameters that are specified in the function's generics.
129 /// We passed through an item scope. Disallow upvars.
130 ItemRibKind(HasGenericParams),
132 /// We're in a constant item. Can't refer to dynamic stuff.
134 /// The item may reference generic parameters in trivial constant expressions.
135 /// All other constants aren't allowed to use generic params at all.
136 ConstantItemRibKind(HasGenericParams, Option<(Ident, ConstantItemKind)>),
138 /// We passed through a module.
139 ModuleRibKind(Module<'a>),
141 /// We passed through a `macro_rules!` statement
142 MacroDefinition(DefId),
144 /// All bindings in this rib are generic parameters that can't be used
145 /// from the default of a generic parameter because they're not declared
146 /// before said generic parameter. Also see the `visit_generics` override.
147 ForwardGenericParamBanRibKind,
149 /// We are inside of the type of a const parameter. Can't refer to any
153 /// We are inside a `sym` inline assembly operand. Can only refer to
159 /// Whether this rib kind contains generic parameters, as opposed to local
161 crate fn contains_params(&self) -> bool {
164 | ClosureOrAsyncRibKind
166 | ConstantItemRibKind(..)
169 | ConstParamTyRibKind
170 | InlineAsmSymRibKind => false,
171 AssocItemRibKind | ItemRibKind(_) | ForwardGenericParamBanRibKind => true,
176 /// A single local scope.
178 /// A rib represents a scope names can live in. Note that these appear in many places, not just
179 /// around braces. At any place where the list of accessible names (of the given namespace)
180 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
181 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
184 /// Different [rib kinds](enum.RibKind) are transparent for different names.
186 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
187 /// resolving, the name is looked up from inside out.
189 crate struct Rib<'a, R = Res> {
190 pub bindings: IdentMap<R>,
191 pub kind: RibKind<'a>,
194 impl<'a, R> Rib<'a, R> {
195 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
196 Rib { bindings: Default::default(), kind }
200 #[derive(Copy, Clone, Debug)]
201 enum LifetimeRibKind {
202 /// This rib acts as a barrier to forbid reference to lifetimes of a parent item.
205 /// This rib declares generic parameters.
206 Generics { parent: NodeId, span: Span, kind: LifetimeBinderKind },
208 /// FIXME(const_generics): This patches over an ICE caused by non-'static lifetimes in const
209 /// generics. We are disallowing this until we can decide on how we want to handle non-'static
210 /// lifetimes in const generics. See issue #74052 for discussion.
213 /// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`.
214 /// This function will emit an error if `generic_const_exprs` is not enabled, the body identified by
215 /// `body_id` is an anonymous constant and `lifetime_ref` is non-static.
218 /// For **Modern** cases, create a new anonymous region parameter
219 /// and reference that.
221 /// For **Dyn Bound** cases, pass responsibility to
222 /// `resolve_lifetime` code.
224 /// For **Deprecated** cases, report an error.
225 AnonymousCreateParameter(NodeId),
227 /// Give a hard error when either `&` or `'_` is written. Used to
228 /// rule out things like `where T: Foo<'_>`. Does not imply an
229 /// error on default object bounds (e.g., `Box<dyn Foo>`).
230 AnonymousReportError,
232 /// Pass responsibility to `resolve_lifetime` code for all cases.
233 AnonymousPassThrough(NodeId),
236 #[derive(Copy, Clone, Debug)]
237 enum LifetimeBinderKind {
246 impl LifetimeBinderKind {
247 fn descr(self) -> &'static str {
248 use LifetimeBinderKind::*;
250 BareFnType => "type",
251 PolyTrait => "bound",
252 WhereBound => "bound",
254 ImplBlock => "impl block",
255 Function => "function",
262 kind: LifetimeRibKind,
263 // We need to preserve insertion order for async fns.
264 bindings: FxIndexMap<Ident, (NodeId, LifetimeRes)>,
268 fn new(kind: LifetimeRibKind) -> LifetimeRib {
269 LifetimeRib { bindings: Default::default(), kind }
273 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
274 crate enum AliasPossibility {
279 #[derive(Copy, Clone, Debug)]
280 crate enum PathSource<'a> {
281 // Type paths `Path`.
283 // Trait paths in bounds or impls.
284 Trait(AliasPossibility),
285 // Expression paths `path`, with optional parent context.
286 Expr(Option<&'a Expr>),
287 // Paths in path patterns `Path`.
289 // Paths in struct expressions and patterns `Path { .. }`.
291 // Paths in tuple struct patterns `Path(..)`.
292 TupleStruct(Span, &'a [Span]),
293 // `m::A::B` in `<T as m::A>::B::C`.
294 TraitItem(Namespace),
297 impl<'a> PathSource<'a> {
298 fn namespace(self) -> Namespace {
300 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
301 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
302 PathSource::TraitItem(ns) => ns,
306 fn defer_to_typeck(self) -> bool {
309 | PathSource::Expr(..)
312 | PathSource::TupleStruct(..) => true,
313 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
317 fn descr_expected(self) -> &'static str {
319 PathSource::Type => "type",
320 PathSource::Trait(_) => "trait",
321 PathSource::Pat => "unit struct, unit variant or constant",
322 PathSource::Struct => "struct, variant or union type",
323 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
324 PathSource::TraitItem(ns) => match ns {
325 TypeNS => "associated type",
326 ValueNS => "method or associated constant",
327 MacroNS => bug!("associated macro"),
329 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
330 // "function" here means "anything callable" rather than `DefKind::Fn`,
331 // this is not precise but usually more helpful than just "value".
332 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
333 // the case of `::some_crate()`
334 ExprKind::Path(_, path)
335 if path.segments.len() == 2
336 && path.segments[0].ident.name == kw::PathRoot =>
340 ExprKind::Path(_, path) => {
341 let mut msg = "function";
342 if let Some(segment) = path.segments.iter().last() {
343 if let Some(c) = segment.ident.to_string().chars().next() {
344 if c.is_uppercase() {
345 msg = "function, tuple struct or tuple variant";
358 fn is_call(self) -> bool {
359 matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
362 crate fn is_expected(self, res: Res) -> bool {
364 PathSource::Type => matches!(
371 | DefKind::TraitAlias
376 | DefKind::ForeignTy,
381 PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
382 PathSource::Trait(AliasPossibility::Maybe) => {
383 matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
385 PathSource::Expr(..) => matches!(
388 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
393 | DefKind::AssocConst
394 | DefKind::ConstParam,
400 res.expected_in_unit_struct_pat()
401 || matches!(res, Res::Def(DefKind::Const | DefKind::AssocConst, _))
403 PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
404 PathSource::Struct => matches!(
413 ) | Res::SelfTy { .. }
415 PathSource::TraitItem(ns) => match res {
416 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
417 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
423 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
424 use rustc_errors::error_code;
425 match (self, has_unexpected_resolution) {
426 (PathSource::Trait(_), true) => error_code!(E0404),
427 (PathSource::Trait(_), false) => error_code!(E0405),
428 (PathSource::Type, true) => error_code!(E0573),
429 (PathSource::Type, false) => error_code!(E0412),
430 (PathSource::Struct, true) => error_code!(E0574),
431 (PathSource::Struct, false) => error_code!(E0422),
432 (PathSource::Expr(..), true) => error_code!(E0423),
433 (PathSource::Expr(..), false) => error_code!(E0425),
434 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
435 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
436 (PathSource::TraitItem(..), true) => error_code!(E0575),
437 (PathSource::TraitItem(..), false) => error_code!(E0576),
443 struct DiagnosticMetadata<'ast> {
444 /// The current trait's associated items' ident, used for diagnostic suggestions.
445 current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
447 /// The current self type if inside an impl (used for better errors).
448 current_self_type: Option<Ty>,
450 /// The current self item if inside an ADT (used for better errors).
451 current_self_item: Option<NodeId>,
453 /// The current trait (used to suggest).
454 current_item: Option<&'ast Item>,
456 /// When processing generics and encountering a type not found, suggest introducing a type
458 currently_processing_generics: bool,
460 /// The current enclosing (non-closure) function (used for better errors).
461 current_function: Option<(FnKind<'ast>, Span)>,
463 /// A list of labels as of yet unused. Labels will be removed from this map when
464 /// they are used (in a `break` or `continue` statement)
465 unused_labels: FxHashMap<NodeId, Span>,
467 /// Only used for better errors on `fn(): fn()`.
468 current_type_ascription: Vec<Span>,
470 /// Only used for better errors on `let x = { foo: bar };`.
471 /// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only
472 /// needed for cases where this parses as a correct type ascription.
473 current_block_could_be_bare_struct_literal: Option<Span>,
475 /// Only used for better errors on `let <pat>: <expr, not type>;`.
476 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
478 /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
479 in_if_condition: Option<&'ast Expr>,
481 /// If we are currently in a trait object definition. Used to point at the bounds when
482 /// encountering a struct or enum.
483 current_trait_object: Option<&'ast [ast::GenericBound]>,
485 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
486 current_where_predicate: Option<&'ast WherePredicate>,
488 current_type_path: Option<&'ast Ty>,
490 /// The current impl items (used to suggest).
491 current_impl_items: Option<&'ast [P<AssocItem>]>,
494 struct LateResolutionVisitor<'a, 'b, 'ast> {
495 r: &'b mut Resolver<'a>,
497 /// The module that represents the current item scope.
498 parent_scope: ParentScope<'a>,
500 /// The current set of local scopes for types and values.
501 /// FIXME #4948: Reuse ribs to avoid allocation.
502 ribs: PerNS<Vec<Rib<'a>>>,
504 /// The current set of local scopes, for labels.
505 label_ribs: Vec<Rib<'a, NodeId>>,
507 /// The current set of local scopes for lifetimes.
508 lifetime_ribs: Vec<LifetimeRib>,
510 /// The trait that the current context can refer to.
511 current_trait_ref: Option<(Module<'a>, TraitRef)>,
513 /// Fields used to add information to diagnostic errors.
514 diagnostic_metadata: DiagnosticMetadata<'ast>,
516 /// State used to know whether to ignore resolution errors for function bodies.
518 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
519 /// In most cases this will be `None`, in which case errors will always be reported.
520 /// If it is `true`, then it will be updated when entering a nested function or trait body.
524 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
525 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
526 fn visit_attribute(&mut self, _: &'ast Attribute) {
527 // We do not want to resolve expressions that appear in attributes,
528 // as they do not correspond to actual code.
530 fn visit_item(&mut self, item: &'ast Item) {
531 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
532 // Always report errors in items we just entered.
533 let old_ignore = replace(&mut self.in_func_body, false);
534 self.with_lifetime_rib(LifetimeRibKind::Item, |this| this.resolve_item(item));
535 self.in_func_body = old_ignore;
536 self.diagnostic_metadata.current_item = prev;
538 fn visit_arm(&mut self, arm: &'ast Arm) {
539 self.resolve_arm(arm);
541 fn visit_block(&mut self, block: &'ast Block) {
542 self.resolve_block(block);
544 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
545 // We deal with repeat expressions explicitly in `resolve_expr`.
546 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
547 this.resolve_anon_const(constant, IsRepeatExpr::No);
550 fn visit_expr(&mut self, expr: &'ast Expr) {
551 self.resolve_expr(expr, None);
553 fn visit_local(&mut self, local: &'ast Local) {
554 let local_spans = match local.pat.kind {
555 // We check for this to avoid tuple struct fields.
556 PatKind::Wild => None,
559 local.ty.as_ref().map(|ty| ty.span),
560 local.kind.init().map(|init| init.span),
563 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
564 self.resolve_local(local);
565 self.diagnostic_metadata.current_let_binding = original;
567 fn visit_ty(&mut self, ty: &'ast Ty) {
568 let prev = self.diagnostic_metadata.current_trait_object;
569 let prev_ty = self.diagnostic_metadata.current_type_path;
571 TyKind::Rptr(None, _) => {
572 // Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
574 let span = self.r.session.source_map().next_point(ty.span.shrink_to_lo());
575 self.resolve_elided_lifetime(ty.id, span);
577 TyKind::Path(ref qself, ref path) => {
578 self.diagnostic_metadata.current_type_path = Some(ty);
579 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
581 TyKind::ImplicitSelf => {
582 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
584 .resolve_ident_in_lexical_scope(
587 Some(Finalize::new(ty.id, ty.span)),
590 .map_or(Res::Err, |d| d.res());
591 self.r.record_partial_res(ty.id, PartialRes::new(res));
593 TyKind::TraitObject(ref bounds, ..) => {
594 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
596 TyKind::BareFn(ref bare_fn) => {
597 let span = if bare_fn.generic_params.is_empty() {
598 ty.span.shrink_to_lo()
602 self.with_generic_param_rib(
603 &bare_fn.generic_params,
605 LifetimeRibKind::Generics {
607 kind: LifetimeBinderKind::BareFnType,
611 this.with_lifetime_rib(
612 LifetimeRibKind::AnonymousPassThrough(ty.id),
614 this.visit_generic_param_vec(&bare_fn.generic_params, false);
615 visit::walk_fn_decl(this, &bare_fn.decl);
620 self.diagnostic_metadata.current_trait_object = prev;
625 visit::walk_ty(self, ty);
626 self.diagnostic_metadata.current_trait_object = prev;
627 self.diagnostic_metadata.current_type_path = prev_ty;
629 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef, _: &'ast TraitBoundModifier) {
631 if tref.bound_generic_params.is_empty() { tref.span.shrink_to_lo() } else { tref.span };
632 self.with_generic_param_rib(
633 &tref.bound_generic_params,
635 LifetimeRibKind::Generics {
636 parent: tref.trait_ref.ref_id,
637 kind: LifetimeBinderKind::PolyTrait,
641 this.visit_generic_param_vec(&tref.bound_generic_params, false);
642 this.smart_resolve_path(
643 tref.trait_ref.ref_id,
645 &tref.trait_ref.path,
646 PathSource::Trait(AliasPossibility::Maybe),
648 this.visit_trait_ref(&tref.trait_ref);
652 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
653 match foreign_item.kind {
654 ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
655 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
656 this.with_generic_param_rib(
658 ItemRibKind(HasGenericParams::Yes),
659 LifetimeRibKind::Generics {
660 parent: foreign_item.id,
661 kind: LifetimeBinderKind::Item,
664 |this| visit::walk_foreign_item(this, foreign_item),
668 ForeignItemKind::Fn(box Fn { ref generics, .. }) => {
669 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
670 this.with_generic_param_rib(
672 ItemRibKind(HasGenericParams::Yes),
673 LifetimeRibKind::Generics {
674 parent: foreign_item.id,
675 kind: LifetimeBinderKind::Function,
678 |this| visit::walk_foreign_item(this, foreign_item),
682 ForeignItemKind::Static(..) => {
683 self.with_item_rib(|this| {
684 visit::walk_foreign_item(this, foreign_item);
687 ForeignItemKind::MacCall(..) => {
688 panic!("unexpanded macro in resolve!")
692 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, fn_id: NodeId) {
693 let rib_kind = match fn_kind {
694 // Bail if the function is foreign, and thus cannot validly have
695 // a body, or if there's no body for some other reason.
696 FnKind::Fn(FnCtxt::Foreign, _, sig, _, generics, _)
697 | FnKind::Fn(_, _, sig, _, generics, None) => {
698 self.with_lifetime_rib(LifetimeRibKind::AnonymousPassThrough(fn_id), |this| {
699 // We don't need to deal with patterns in parameters, because
700 // they are not possible for foreign or bodiless functions.
701 this.visit_fn_header(&sig.header);
702 this.visit_generics(generics);
703 visit::walk_fn_decl(this, &sig.decl);
707 FnKind::Fn(FnCtxt::Free, ..) => FnItemRibKind,
708 FnKind::Fn(FnCtxt::Assoc(_), ..) => NormalRibKind,
709 FnKind::Closure(..) => ClosureOrAsyncRibKind,
711 let previous_value = self.diagnostic_metadata.current_function;
712 if matches!(fn_kind, FnKind::Fn(..)) {
713 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
715 debug!("(resolving function) entering function");
716 let declaration = fn_kind.decl();
718 // Create a value rib for the function.
719 self.with_rib(ValueNS, rib_kind, |this| {
720 // Create a label rib for the function.
721 this.with_label_rib(rib_kind, |this| {
722 let async_node_id = fn_kind.header().and_then(|h| h.asyncness.opt_return_id());
724 if let FnKind::Fn(_, _, _, _, generics, _) = fn_kind {
725 this.visit_generics(generics);
728 if let Some(async_node_id) = async_node_id {
729 // In `async fn`, argument-position elided lifetimes
730 // must be transformed into fresh generic parameters so that
731 // they can be applied to the opaque `impl Trait` return type.
732 this.with_lifetime_rib(
733 LifetimeRibKind::AnonymousCreateParameter(fn_id),
735 // Add each argument to the rib.
736 this.resolve_params(&declaration.inputs)
740 // Construct the list of in-scope lifetime parameters for async lowering.
741 // We include all lifetime parameters, either named or "Fresh".
742 // The order of those parameters does not matter, as long as it is
744 let mut extra_lifetime_params =
745 this.r.extra_lifetime_params_map.get(&fn_id).cloned().unwrap_or_default();
746 for rib in this.lifetime_ribs.iter().rev() {
747 extra_lifetime_params.extend(
750 .map(|(&ident, &(node_id, res))| (ident, node_id, res)),
753 LifetimeRibKind::Item => break,
754 LifetimeRibKind::AnonymousCreateParameter(id) => {
755 if let Some(earlier_fresh) =
756 this.r.extra_lifetime_params_map.get(&id)
758 extra_lifetime_params.extend(earlier_fresh);
764 this.r.extra_lifetime_params_map.insert(async_node_id, extra_lifetime_params);
766 this.with_lifetime_rib(
767 LifetimeRibKind::AnonymousPassThrough(async_node_id),
768 |this| visit::walk_fn_ret_ty(this, &declaration.output),
771 this.with_lifetime_rib(LifetimeRibKind::AnonymousPassThrough(fn_id), |this| {
772 // Add each argument to the rib.
773 this.resolve_params(&declaration.inputs);
775 visit::walk_fn_ret_ty(this, &declaration.output);
779 // Ignore errors in function bodies if this is rustdoc
780 // Be sure not to set this until the function signature has been resolved.
781 let previous_state = replace(&mut this.in_func_body, true);
782 // Resolve the function body, potentially inside the body of an async closure
783 this.with_lifetime_rib(LifetimeRibKind::AnonymousPassThrough(fn_id), |this| {
785 FnKind::Fn(.., body) => walk_list!(this, visit_block, body),
786 FnKind::Closure(_, body) => this.visit_expr(body),
790 debug!("(resolving function) leaving function");
791 this.in_func_body = previous_state;
794 self.diagnostic_metadata.current_function = previous_value;
796 fn visit_lifetime(&mut self, lifetime: &'ast Lifetime) {
797 self.resolve_lifetime(lifetime)
800 fn visit_generics(&mut self, generics: &'ast Generics) {
801 self.visit_generic_param_vec(
803 self.diagnostic_metadata.current_self_item.is_some(),
805 for p in &generics.where_clause.predicates {
806 self.visit_where_predicate(p);
810 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
811 debug!("visit_generic_arg({:?})", arg);
812 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
814 GenericArg::Type(ref ty) => {
815 // We parse const arguments as path types as we cannot distinguish them during
816 // parsing. We try to resolve that ambiguity by attempting resolution the type
817 // namespace first, and if that fails we try again in the value namespace. If
818 // resolution in the value namespace succeeds, we have an generic const argument on
820 if let TyKind::Path(ref qself, ref path) = ty.kind {
821 // We cannot disambiguate multi-segment paths right now as that requires type
823 if path.segments.len() == 1 && path.segments[0].args.is_none() {
824 let mut check_ns = |ns| {
825 self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns)
828 if !check_ns(TypeNS) && check_ns(ValueNS) {
829 // This must be equivalent to `visit_anon_const`, but we cannot call it
830 // directly due to visitor lifetimes so we have to copy-paste some code.
832 // Note that we might not be inside of an repeat expression here,
833 // but considering that `IsRepeatExpr` is only relevant for
834 // non-trivial constants this is doesn't matter.
835 self.with_constant_rib(
837 HasGenericParams::Yes,
840 this.smart_resolve_path(
844 PathSource::Expr(None),
847 if let Some(ref qself) = *qself {
848 this.visit_ty(&qself.ty);
850 this.visit_path(path, ty.id);
854 self.diagnostic_metadata.currently_processing_generics = prev;
862 GenericArg::Lifetime(lt) => self.visit_lifetime(lt),
863 GenericArg::Const(ct) => self.visit_anon_const(ct),
865 self.diagnostic_metadata.currently_processing_generics = prev;
868 fn visit_path_segment(&mut self, path_span: Span, path_segment: &'ast PathSegment) {
869 if let Some(ref args) = path_segment.args {
871 GenericArgs::AngleBracketed(..) => visit::walk_generic_args(self, path_span, args),
872 GenericArgs::Parenthesized(..) => self.with_lifetime_rib(
873 LifetimeRibKind::AnonymousPassThrough(path_segment.id),
874 |this| visit::walk_generic_args(this, path_span, args),
880 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
881 debug!("visit_where_predicate {:?}", p);
883 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
884 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
885 if let WherePredicate::BoundPredicate(WhereBoundPredicate {
888 ref bound_generic_params,
889 span: predicate_span,
893 let span = if bound_generic_params.is_empty() {
894 predicate_span.shrink_to_lo()
898 this.with_generic_param_rib(
899 &bound_generic_params,
901 LifetimeRibKind::Generics {
902 parent: bounded_ty.id,
903 kind: LifetimeBinderKind::WhereBound,
907 this.visit_generic_param_vec(&bound_generic_params, false);
908 this.visit_ty(bounded_ty);
909 for bound in bounds {
910 this.visit_param_bound(bound, BoundKind::Bound)
915 visit::walk_where_predicate(this, p);
918 self.diagnostic_metadata.current_where_predicate = previous_value;
921 fn visit_inline_asm_sym(&mut self, sym: &'ast InlineAsmSym) {
922 // This is similar to the code for AnonConst.
923 self.with_rib(ValueNS, InlineAsmSymRibKind, |this| {
924 this.with_rib(TypeNS, InlineAsmSymRibKind, |this| {
925 this.with_label_rib(InlineAsmSymRibKind, |this| {
926 this.smart_resolve_path(
930 PathSource::Expr(None),
932 visit::walk_inline_asm_sym(this, sym);
939 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
940 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
941 // During late resolution we only track the module component of the parent scope,
942 // although it may be useful to track other components as well for diagnostics.
943 let graph_root = resolver.graph_root;
944 let parent_scope = ParentScope::module(graph_root, resolver);
945 let start_rib_kind = ModuleRibKind(graph_root);
946 LateResolutionVisitor {
950 value_ns: vec![Rib::new(start_rib_kind)],
951 type_ns: vec![Rib::new(start_rib_kind)],
952 macro_ns: vec![Rib::new(start_rib_kind)],
954 label_ribs: Vec::new(),
955 lifetime_ribs: Vec::new(),
956 current_trait_ref: None,
957 diagnostic_metadata: DiagnosticMetadata::default(),
958 // errors at module scope should always be reported
963 fn maybe_resolve_ident_in_lexical_scope(
967 ) -> Option<LexicalScopeBinding<'a>> {
968 self.r.resolve_ident_in_lexical_scope(
978 fn resolve_ident_in_lexical_scope(
982 finalize: Option<Finalize>,
983 ignore_binding: Option<&'a NameBinding<'a>>,
984 ) -> Option<LexicalScopeBinding<'a>> {
985 self.r.resolve_ident_in_lexical_scope(
998 opt_ns: Option<Namespace>, // `None` indicates a module path in import
999 finalize: Option<Finalize>,
1000 ) -> PathResult<'a> {
1001 self.r.resolve_path_with_ribs(
1013 // We maintain a list of value ribs and type ribs.
1015 // Simultaneously, we keep track of the current position in the module
1016 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
1017 // the value or type namespaces, we first look through all the ribs and
1018 // then query the module graph. When we resolve a name in the module
1019 // namespace, we can skip all the ribs (since nested modules are not
1020 // allowed within blocks in Rust) and jump straight to the current module
1023 // Named implementations are handled separately. When we find a method
1024 // call, we consult the module node to find all of the implementations in
1025 // scope. This information is lazily cached in the module node. We then
1026 // generate a fake "implementation scope" containing all the
1027 // implementations thus found, for compatibility with old resolve pass.
1029 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
1034 work: impl FnOnce(&mut Self) -> T,
1036 self.ribs[ns].push(Rib::new(kind));
1037 let ret = work(self);
1038 self.ribs[ns].pop();
1042 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
1043 if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
1044 // Move down in the graph.
1045 let orig_module = replace(&mut self.parent_scope.module, module);
1046 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
1047 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
1049 this.parent_scope.module = orig_module;
1058 fn visit_generic_param_vec(&mut self, params: &'ast Vec<GenericParam>, add_self_upper: bool) {
1059 // For type parameter defaults, we have to ban access
1060 // to following type parameters, as the InternalSubsts can only
1061 // provide previous type parameters as they're built. We
1062 // put all the parameters on the ban list and then remove
1063 // them one by one as they are processed and become available.
1064 let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1065 let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1066 for param in params.iter() {
1068 GenericParamKind::Type { .. } => {
1071 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1073 GenericParamKind::Const { .. } => {
1074 forward_const_ban_rib
1076 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1078 GenericParamKind::Lifetime => {}
1082 // rust-lang/rust#61631: The type `Self` is essentially
1083 // another type parameter. For ADTs, we consider it
1084 // well-defined only after all of the ADT type parameters have
1085 // been provided. Therefore, we do not allow use of `Self`
1086 // anywhere in ADT type parameter defaults.
1088 // (We however cannot ban `Self` for defaults on *all* generic
1089 // lists; e.g. trait generics can usefully refer to `Self`,
1090 // such as in the case of `trait Add<Rhs = Self>`.)
1092 // (`Some` if + only if we are in ADT's generics.)
1093 forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
1096 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1097 for param in params {
1099 GenericParamKind::Lifetime => {
1100 for bound in ¶m.bounds {
1101 this.visit_param_bound(bound, BoundKind::Bound);
1104 GenericParamKind::Type { ref default } => {
1105 for bound in ¶m.bounds {
1106 this.visit_param_bound(bound, BoundKind::Bound);
1109 if let Some(ref ty) = default {
1110 this.ribs[TypeNS].push(forward_ty_ban_rib);
1111 this.ribs[ValueNS].push(forward_const_ban_rib);
1113 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1114 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1117 // Allow all following defaults to refer to this type parameter.
1120 .remove(&Ident::with_dummy_span(param.ident.name));
1122 GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
1123 // Const parameters can't have param bounds.
1124 assert!(param.bounds.is_empty());
1126 this.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
1127 this.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
1128 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1131 this.ribs[TypeNS].pop().unwrap();
1132 this.ribs[ValueNS].pop().unwrap();
1134 if let Some(ref expr) = default {
1135 this.ribs[TypeNS].push(forward_ty_ban_rib);
1136 this.ribs[ValueNS].push(forward_const_ban_rib);
1137 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1138 this.resolve_anon_const(expr, IsRepeatExpr::No)
1140 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1141 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1144 // Allow all following defaults to refer to this const parameter.
1145 forward_const_ban_rib
1147 .remove(&Ident::with_dummy_span(param.ident.name));
1154 #[tracing::instrument(level = "debug", skip(self, work))]
1155 fn with_lifetime_rib<T>(
1157 kind: LifetimeRibKind,
1158 work: impl FnOnce(&mut Self) -> T,
1160 self.lifetime_ribs.push(LifetimeRib::new(kind));
1161 let ret = work(self);
1162 self.lifetime_ribs.pop();
1166 #[tracing::instrument(level = "debug", skip(self))]
1167 fn resolve_lifetime(&mut self, lifetime: &'ast Lifetime) {
1168 let ident = lifetime.ident;
1170 if ident.name == kw::StaticLifetime {
1171 self.record_lifetime_res(lifetime.id, LifetimeRes::Static);
1175 if ident.name == kw::UnderscoreLifetime {
1176 return self.resolve_anonymous_lifetime(lifetime, false);
1179 let mut indices = (0..self.lifetime_ribs.len()).rev();
1180 for i in &mut indices {
1181 let rib = &self.lifetime_ribs[i];
1182 let normalized_ident = ident.normalize_to_macros_2_0();
1183 if let Some(&(_, region)) = rib.bindings.get(&normalized_ident) {
1184 self.record_lifetime_res(lifetime.id, region);
1189 LifetimeRibKind::Item => break,
1190 LifetimeRibKind::ConstGeneric => {
1191 self.emit_non_static_lt_in_const_generic_error(lifetime);
1192 self.r.lifetimes_res_map.insert(lifetime.id, LifetimeRes::Error);
1195 LifetimeRibKind::AnonConst => {
1196 self.maybe_emit_forbidden_non_static_lifetime_error(lifetime);
1197 self.r.lifetimes_res_map.insert(lifetime.id, LifetimeRes::Error);
1204 let mut outer_res = None;
1206 let rib = &self.lifetime_ribs[i];
1207 let normalized_ident = ident.normalize_to_macros_2_0();
1208 if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) {
1209 outer_res = Some(outer);
1214 self.emit_undeclared_lifetime_error(lifetime, outer_res);
1215 self.record_lifetime_res(lifetime.id, LifetimeRes::Error);
1218 #[tracing::instrument(level = "debug", skip(self))]
1219 fn resolve_anonymous_lifetime(&mut self, lifetime: &Lifetime, elided: bool) {
1220 debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
1222 for i in (0..self.lifetime_ribs.len()).rev() {
1223 let rib = &mut self.lifetime_ribs[i];
1225 LifetimeRibKind::AnonymousCreateParameter(item_node_id) => {
1226 self.create_fresh_lifetime(lifetime.id, lifetime.ident, item_node_id);
1229 LifetimeRibKind::AnonymousReportError => {
1230 let (msg, note) = if elided {
1232 "`&` without an explicit lifetime name cannot be used here",
1233 "explicit lifetime name needed here",
1236 ("`'_` cannot be used here", "`'_` is a reserved lifetime name")
1238 rustc_errors::struct_span_err!(
1240 lifetime.ident.span,
1245 .span_label(lifetime.ident.span, note)
1248 self.record_lifetime_res(lifetime.id, LifetimeRes::Error);
1251 LifetimeRibKind::AnonymousPassThrough(node_id) => {
1252 self.record_lifetime_res(
1254 LifetimeRes::Anonymous { binder: node_id, elided },
1258 LifetimeRibKind::Item => break,
1262 // This resolution is wrong, it passes the work to HIR lifetime resolution.
1263 // We cannot use `LifetimeRes::Error` because we do not emit a diagnostic.
1264 self.record_lifetime_res(
1266 LifetimeRes::Anonymous { binder: DUMMY_NODE_ID, elided },
1270 #[tracing::instrument(level = "debug", skip(self))]
1271 fn resolve_elided_lifetime(&mut self, anchor_id: NodeId, span: Span) {
1272 let id = self.r.next_node_id();
1273 self.record_lifetime_res(
1275 LifetimeRes::ElidedAnchor { start: id, end: NodeId::from_u32(id.as_u32() + 1) },
1278 let lt = Lifetime { id, ident: Ident::new(kw::UnderscoreLifetime, span) };
1279 self.resolve_anonymous_lifetime(<, true);
1282 #[tracing::instrument(level = "debug", skip(self))]
1283 fn create_fresh_lifetime(&mut self, id: NodeId, ident: Ident, item_node_id: NodeId) {
1284 debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
1285 debug!(?ident.span);
1286 let item_def_id = self.r.local_def_id(item_node_id);
1287 let def_node_id = self.r.next_node_id();
1288 let def_id = self.r.create_def(
1291 DefPathData::LifetimeNs(kw::UnderscoreLifetime),
1292 self.parent_scope.expansion.to_expn_id(),
1297 let region = LifetimeRes::Fresh { param: def_id, binder: item_node_id };
1298 self.record_lifetime_res(id, region);
1299 self.r.extra_lifetime_params_map.entry(item_node_id).or_insert_with(Vec::new).push((
1306 #[tracing::instrument(level = "debug", skip(self))]
1307 fn resolve_elided_lifetimes_in_path(
1310 partial_res: PartialRes,
1312 source: PathSource<'_>,
1315 let proj_start = path.len() - partial_res.unresolved_segments();
1316 for (i, segment) in path.iter().enumerate() {
1317 if segment.has_lifetime_args {
1320 let Some(segment_id) = segment.id else {
1324 // Figure out if this is a type/trait segment,
1325 // which may need lifetime elision performed.
1326 let type_def_id = match partial_res.base_res() {
1327 Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => self.r.parent(def_id),
1328 Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => self.r.parent(def_id),
1329 Res::Def(DefKind::Struct, def_id)
1330 | Res::Def(DefKind::Union, def_id)
1331 | Res::Def(DefKind::Enum, def_id)
1332 | Res::Def(DefKind::TyAlias, def_id)
1333 | Res::Def(DefKind::Trait, def_id)
1334 if i + 1 == proj_start =>
1341 let expected_lifetimes = self.r.item_generics_num_lifetimes(type_def_id);
1342 if expected_lifetimes == 0 {
1346 let missing = match source {
1347 PathSource::Trait(..) | PathSource::TraitItem(..) | PathSource::Type => true,
1348 PathSource::Expr(..)
1350 | PathSource::Struct
1351 | PathSource::TupleStruct(..) => false,
1353 let mut res = LifetimeRes::Error;
1354 for rib in self.lifetime_ribs.iter().rev() {
1356 // In create-parameter mode we error here because we don't want to support
1357 // deprecated impl elision in new features like impl elision and `async fn`,
1358 // both of which work using the `CreateParameter` mode:
1360 // impl Foo for std::cell::Ref<u32> // note lack of '_
1361 // async fn foo(_: std::cell::Ref<u32>) { ... }
1362 LifetimeRibKind::AnonymousCreateParameter(_) => {
1365 // `PassThrough` is the normal case.
1366 // `new_error_lifetime`, which would usually be used in the case of `ReportError`,
1367 // is unsuitable here, as these can occur from missing lifetime parameters in a
1368 // `PathSegment`, for which there is no associated `'_` or `&T` with no explicit
1369 // lifetime. Instead, we simply create an implicit lifetime, which will be checked
1370 // later, at which point a suitable error will be emitted.
1371 LifetimeRibKind::AnonymousPassThrough(binder) => {
1372 res = LifetimeRes::Anonymous { binder, elided: true };
1375 LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
1376 // FIXME(cjgillot) This resolution is wrong, but this does not matter
1377 // since these cases are erroneous anyway. Lifetime resolution should
1378 // emit a "missing lifetime specifier" diagnostic.
1379 res = LifetimeRes::Anonymous { binder: DUMMY_NODE_ID, elided: true };
1386 let node_ids = self.r.next_node_ids(expected_lifetimes);
1387 self.record_lifetime_res(
1389 LifetimeRes::ElidedAnchor { start: node_ids.start, end: node_ids.end },
1391 for i in 0..expected_lifetimes {
1392 let id = node_ids.start.plus(i);
1393 self.record_lifetime_res(id, res);
1400 let elided_lifetime_span = if segment.has_generic_args {
1401 // If there are brackets, but not generic arguments, then use the opening bracket
1402 segment.args_span.with_hi(segment.args_span.lo() + BytePos(1))
1404 // If there are no brackets, use the identifier span.
1405 // HACK: we use find_ancestor_inside to properly suggest elided spans in paths
1406 // originating from macros, since the segment's span might be from a macro arg.
1407 segment.ident.span.find_ancestor_inside(path_span).unwrap_or(path_span)
1409 if let LifetimeRes::Error = res {
1410 let sess = self.r.session;
1411 let mut err = rustc_errors::struct_span_err!(
1415 "implicit elided lifetime not allowed here"
1417 rustc_errors::add_elided_lifetime_in_path_suggestion(
1422 !segment.has_generic_args,
1423 elided_lifetime_span,
1425 err.note("assuming a `'static` lifetime...");
1428 self.r.lint_buffer.buffer_lint_with_diagnostic(
1429 lint::builtin::ELIDED_LIFETIMES_IN_PATHS,
1431 elided_lifetime_span,
1432 "hidden lifetime parameters in types are deprecated",
1433 lint::BuiltinLintDiagnostics::ElidedLifetimesInPaths(
1436 !segment.has_generic_args,
1437 elided_lifetime_span,
1444 #[tracing::instrument(level = "debug", skip(self))]
1445 fn record_lifetime_res(&mut self, id: NodeId, res: LifetimeRes) {
1446 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1448 "lifetime {:?} resolved multiple times ({:?} before, {:?} now)",
1454 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
1455 /// label and reports an error if the label is not found or is unreachable.
1456 fn resolve_label(&mut self, mut label: Ident) -> Option<NodeId> {
1457 let mut suggestion = None;
1459 // Preserve the original span so that errors contain "in this macro invocation"
1461 let original_span = label.span;
1463 for i in (0..self.label_ribs.len()).rev() {
1464 let rib = &self.label_ribs[i];
1466 if let MacroDefinition(def) = rib.kind {
1467 // If an invocation of this macro created `ident`, give up on `ident`
1468 // and switch to `ident`'s source from the macro definition.
1469 if def == self.r.macro_def(label.span.ctxt()) {
1470 label.span.remove_mark();
1474 let ident = label.normalize_to_macro_rules();
1475 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
1476 let definition_span = ident.span;
1477 return if self.is_label_valid_from_rib(i) {
1482 ResolutionError::UnreachableLabel {
1493 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
1494 // the first such label that is encountered.
1495 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
1500 ResolutionError::UndeclaredLabel { name: label.name, suggestion },
1505 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
1506 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
1507 let ribs = &self.label_ribs[rib_index + 1..];
1511 NormalRibKind | MacroDefinition(..) => {
1512 // Nothing to do. Continue.
1516 | ClosureOrAsyncRibKind
1519 | ConstantItemRibKind(..)
1521 | ForwardGenericParamBanRibKind
1522 | ConstParamTyRibKind
1523 | InlineAsmSymRibKind => {
1532 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
1533 debug!("resolve_adt");
1534 self.with_current_self_item(item, |this| {
1535 this.with_generic_param_rib(
1537 ItemRibKind(HasGenericParams::Yes),
1538 LifetimeRibKind::Generics {
1540 kind: LifetimeBinderKind::Item,
1541 span: generics.span,
1544 let item_def_id = this.r.local_def_id(item.id).to_def_id();
1546 Res::SelfTy { trait_: None, alias_to: Some((item_def_id, false)) },
1548 visit::walk_item(this, item);
1556 fn future_proof_import(&mut self, use_tree: &UseTree) {
1557 let segments = &use_tree.prefix.segments;
1558 if !segments.is_empty() {
1559 let ident = segments[0].ident;
1560 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
1564 let nss = match use_tree.kind {
1565 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
1568 let report_error = |this: &Self, ns| {
1569 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
1570 if this.should_report_errs() {
1573 .span_err(ident.span, &format!("imports cannot refer to {}", what));
1578 match self.maybe_resolve_ident_in_lexical_scope(ident, ns) {
1579 Some(LexicalScopeBinding::Res(..)) => {
1580 report_error(self, ns);
1582 Some(LexicalScopeBinding::Item(binding)) => {
1583 if let Some(LexicalScopeBinding::Res(..)) =
1584 self.resolve_ident_in_lexical_scope(ident, ns, None, Some(binding))
1586 report_error(self, ns);
1592 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
1593 for (use_tree, _) in use_trees {
1594 self.future_proof_import(use_tree);
1599 fn resolve_item(&mut self, item: &'ast Item) {
1600 let name = item.ident.name;
1601 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
1604 ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
1605 self.with_generic_param_rib(
1607 ItemRibKind(HasGenericParams::Yes),
1608 LifetimeRibKind::Generics {
1610 kind: LifetimeBinderKind::Item,
1611 span: generics.span,
1613 |this| visit::walk_item(this, item),
1617 ItemKind::Fn(box Fn { ref generics, .. }) => {
1618 self.with_generic_param_rib(
1620 ItemRibKind(HasGenericParams::Yes),
1621 LifetimeRibKind::Generics {
1623 kind: LifetimeBinderKind::Function,
1624 span: generics.span,
1626 |this| visit::walk_item(this, item),
1630 ItemKind::Enum(_, ref generics)
1631 | ItemKind::Struct(_, ref generics)
1632 | ItemKind::Union(_, ref generics) => {
1633 self.resolve_adt(item, generics);
1636 ItemKind::Impl(box Impl {
1640 items: ref impl_items,
1643 self.diagnostic_metadata.current_impl_items = Some(impl_items);
1644 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
1645 self.diagnostic_metadata.current_impl_items = None;
1648 ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
1649 // Create a new rib for the trait-wide type parameters.
1650 self.with_generic_param_rib(
1652 ItemRibKind(HasGenericParams::Yes),
1653 LifetimeRibKind::Generics {
1655 kind: LifetimeBinderKind::Item,
1656 span: generics.span,
1659 let local_def_id = this.r.local_def_id(item.id).to_def_id();
1661 Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
1663 this.visit_generics(generics);
1664 walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);
1666 let walk_assoc_item =
1668 generics: &Generics,
1670 item: &'ast AssocItem| {
1671 this.with_generic_param_rib(
1674 LifetimeRibKind::Generics {
1676 span: generics.span,
1680 visit::walk_assoc_item(this, item, AssocCtxt::Trait)
1685 this.with_trait_items(items, |this| {
1688 AssocItemKind::Const(_, ty, default) => {
1690 // Only impose the restrictions of `ConstRibKind` for an
1691 // actual constant expression in a provided default.
1692 if let Some(expr) = default {
1693 // We allow arbitrary const expressions inside of associated consts,
1694 // even if they are potentially not const evaluatable.
1696 // Type parameters can already be used and as associated consts are
1697 // not used as part of the type system, this is far less surprising.
1698 this.with_constant_rib(
1700 HasGenericParams::Yes,
1702 |this| this.visit_expr(expr),
1706 AssocItemKind::Fn(box Fn { generics, .. }) => {
1710 LifetimeBinderKind::Function,
1714 AssocItemKind::TyAlias(box TyAlias {
1721 LifetimeBinderKind::Item,
1725 AssocItemKind::MacCall(_) => {
1726 panic!("unexpanded macro in resolve!")
1737 ItemKind::TraitAlias(ref generics, ref bounds) => {
1738 // Create a new rib for the trait-wide type parameters.
1739 self.with_generic_param_rib(
1741 ItemRibKind(HasGenericParams::Yes),
1742 LifetimeRibKind::Generics {
1744 kind: LifetimeBinderKind::Item,
1745 span: generics.span,
1748 let local_def_id = this.r.local_def_id(item.id).to_def_id();
1750 Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
1752 this.visit_generics(generics);
1753 walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
1760 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
1761 self.with_scope(item.id, |this| {
1762 visit::walk_item(this, item);
1766 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
1767 self.with_item_rib(|this| {
1769 if let Some(expr) = expr {
1770 let constant_item_kind = match item.kind {
1771 ItemKind::Const(..) => ConstantItemKind::Const,
1772 ItemKind::Static(..) => ConstantItemKind::Static,
1773 _ => unreachable!(),
1775 // We already forbid generic params because of the above item rib,
1776 // so it doesn't matter whether this is a trivial constant.
1777 this.with_constant_rib(
1779 HasGenericParams::Yes,
1780 Some((item.ident, constant_item_kind)),
1781 |this| this.visit_expr(expr),
1787 ItemKind::Use(ref use_tree) => {
1788 self.future_proof_import(use_tree);
1791 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => {
1792 // do nothing, these are just around to be encoded
1795 ItemKind::GlobalAsm(_) => {
1796 visit::walk_item(self, item);
1799 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
1803 fn with_generic_param_rib<'c, F>(
1805 params: &'c Vec<GenericParam>,
1807 lifetime_kind: LifetimeRibKind,
1810 F: FnOnce(&mut Self),
1812 debug!("with_generic_param_rib");
1813 let mut function_type_rib = Rib::new(kind);
1814 let mut function_value_rib = Rib::new(kind);
1815 let mut function_lifetime_rib = LifetimeRib::new(lifetime_kind);
1816 let mut seen_bindings = FxHashMap::default();
1818 // We also can't shadow bindings from the parent item
1819 if let AssocItemRibKind = kind {
1820 let mut add_bindings_for_ns = |ns| {
1821 let parent_rib = self.ribs[ns]
1823 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
1824 .expect("associated item outside of an item");
1826 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
1828 add_bindings_for_ns(ValueNS);
1829 add_bindings_for_ns(TypeNS);
1832 for param in params {
1833 let ident = param.ident.normalize_to_macros_2_0();
1834 debug!("with_generic_param_rib: {}", param.id);
1836 match seen_bindings.entry(ident) {
1837 Entry::Occupied(entry) => {
1838 let span = *entry.get();
1839 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
1840 if !matches!(param.kind, GenericParamKind::Lifetime) {
1841 self.report_error(param.ident.span, err);
1844 Entry::Vacant(entry) => {
1845 entry.insert(param.ident.span);
1849 if param.ident.name == kw::UnderscoreLifetime {
1850 rustc_errors::struct_span_err!(
1854 "`'_` cannot be used here"
1856 .span_label(param.ident.span, "`'_` is a reserved lifetime name")
1861 if param.ident.name == kw::StaticLifetime {
1862 rustc_errors::struct_span_err!(
1866 "invalid lifetime parameter name: `{}`",
1869 .span_label(param.ident.span, "'static is a reserved lifetime name")
1874 let def_id = self.r.local_def_id(param.id);
1876 // Plain insert (no renaming).
1877 let (rib, def_kind) = match param.kind {
1878 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
1879 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
1880 GenericParamKind::Lifetime => {
1881 let LifetimeRibKind::Generics { parent, .. } = lifetime_kind else { panic!() };
1882 let res = LifetimeRes::Param { param: def_id, binder: parent };
1883 self.record_lifetime_res(param.id, res);
1884 function_lifetime_rib.bindings.insert(ident, (param.id, res));
1888 let res = Res::Def(def_kind, def_id.to_def_id());
1889 self.r.record_partial_res(param.id, PartialRes::new(res));
1890 rib.bindings.insert(ident, res);
1893 self.lifetime_ribs.push(function_lifetime_rib);
1894 self.ribs[ValueNS].push(function_value_rib);
1895 self.ribs[TypeNS].push(function_type_rib);
1899 self.ribs[TypeNS].pop();
1900 self.ribs[ValueNS].pop();
1901 self.lifetime_ribs.pop();
1904 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
1905 self.label_ribs.push(Rib::new(kind));
1907 self.label_ribs.pop();
1910 fn with_item_rib(&mut self, f: impl FnOnce(&mut Self)) {
1911 let kind = ItemRibKind(HasGenericParams::No);
1912 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
1913 this.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
1917 // HACK(min_const_generics,const_evaluatable_unchecked): We
1918 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
1919 // with a future compat lint for now. We do this by adding an
1920 // additional special case for repeat expressions.
1922 // Note that we intentionally still forbid `[0; N + 1]` during
1923 // name resolution so that we don't extend the future
1924 // compat lint to new cases.
1925 #[instrument(level = "debug", skip(self, f))]
1926 fn with_constant_rib(
1928 is_repeat: IsRepeatExpr,
1929 may_use_generics: HasGenericParams,
1930 item: Option<(Ident, ConstantItemKind)>,
1931 f: impl FnOnce(&mut Self),
1933 self.with_rib(ValueNS, ConstantItemRibKind(may_use_generics, item), |this| {
1936 ConstantItemRibKind(
1937 may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes),
1941 this.with_label_rib(ConstantItemRibKind(may_use_generics, item), f);
1947 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
1948 // Handle nested impls (inside fn bodies)
1949 let previous_value =
1950 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
1951 let result = f(self);
1952 self.diagnostic_metadata.current_self_type = previous_value;
1956 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
1957 let previous_value =
1958 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
1959 let result = f(self);
1960 self.diagnostic_metadata.current_self_item = previous_value;
1964 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
1965 fn with_trait_items<T>(
1967 trait_items: &'ast [P<AssocItem>],
1968 f: impl FnOnce(&mut Self) -> T,
1970 let trait_assoc_items =
1971 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
1972 let result = f(self);
1973 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
1977 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
1978 fn with_optional_trait_ref<T>(
1980 opt_trait_ref: Option<&TraitRef>,
1981 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
1983 let mut new_val = None;
1984 let mut new_id = None;
1985 if let Some(trait_ref) = opt_trait_ref {
1986 let path: Vec<_> = Segment::from_path(&trait_ref.path);
1987 let res = self.smart_resolve_path_fragment(
1990 PathSource::Trait(AliasPossibility::No),
1991 Finalize::new(trait_ref.ref_id, trait_ref.path.span),
1993 if let Some(def_id) = res.base_res().opt_def_id() {
1994 new_id = Some(def_id);
1995 new_val = Some((self.r.expect_module(def_id), trait_ref.clone()));
1998 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1999 let result = f(self, new_id);
2000 self.current_trait_ref = original_trait_ref;
2004 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
2005 let mut self_type_rib = Rib::new(NormalRibKind);
2007 // Plain insert (no renaming, since types are not currently hygienic)
2008 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
2009 self.ribs[ns].push(self_type_rib);
2011 self.ribs[ns].pop();
2014 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
2015 self.with_self_rib_ns(TypeNS, self_res, f)
2018 fn resolve_implementation(
2020 generics: &'ast Generics,
2021 opt_trait_reference: &'ast Option<TraitRef>,
2022 self_type: &'ast Ty,
2024 impl_items: &'ast [P<AssocItem>],
2026 debug!("resolve_implementation");
2027 // If applicable, create a rib for the type parameters.
2028 self.with_generic_param_rib(&generics.params, ItemRibKind(HasGenericParams::Yes), LifetimeRibKind::Generics { span: generics.span, parent: item_id, kind: LifetimeBinderKind::ImplBlock }, |this| {
2029 // Dummy self type for better errors if `Self` is used in the trait path.
2030 this.with_self_rib(Res::SelfTy { trait_: None, alias_to: None }, |this| {
2031 this.with_lifetime_rib(LifetimeRibKind::AnonymousCreateParameter(item_id), |this| {
2032 // Resolve the trait reference, if necessary.
2033 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
2034 let item_def_id = this.r.local_def_id(item_id);
2036 // Register the trait definitions from here.
2037 if let Some(trait_id) = trait_id {
2038 this.r.trait_impls.entry(trait_id).or_default().push(item_def_id);
2041 let item_def_id = item_def_id.to_def_id();
2043 Res::SelfTy { trait_: trait_id, alias_to: Some((item_def_id, false)) };
2044 this.with_self_rib(res, |this| {
2045 if let Some(trait_ref) = opt_trait_reference.as_ref() {
2046 // Resolve type arguments in the trait path.
2047 visit::walk_trait_ref(this, trait_ref);
2049 // Resolve the self type.
2050 this.visit_ty(self_type);
2051 // Resolve the generic parameters.
2052 this.visit_generics(generics);
2054 // Resolve the items within the impl.
2055 this.with_lifetime_rib(LifetimeRibKind::AnonymousPassThrough(item_id),
2057 this.with_current_self_type(self_type, |this| {
2058 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
2059 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
2060 for item in impl_items {
2061 use crate::ResolutionError::*;
2063 AssocItemKind::Const(_default, _ty, _expr) => {
2064 debug!("resolve_implementation AssocItemKind::Const");
2065 // If this is a trait impl, ensure the const
2067 this.check_trait_item(
2073 |i, s, c| ConstNotMemberOfTrait(i, s, c),
2076 // We allow arbitrary const expressions inside of associated consts,
2077 // even if they are potentially not const evaluatable.
2079 // Type parameters can already be used and as associated consts are
2080 // not used as part of the type system, this is far less surprising.
2081 this.with_constant_rib(
2083 HasGenericParams::Yes,
2086 visit::walk_assoc_item(
2094 AssocItemKind::Fn(box Fn { generics, .. }) => {
2095 debug!("resolve_implementation AssocItemKind::Fn");
2096 // We also need a new scope for the impl item type parameters.
2097 this.with_generic_param_rib(
2100 LifetimeRibKind::Generics { parent: item.id, span: generics.span, kind: LifetimeBinderKind::Function },
2102 // If this is a trait impl, ensure the method
2104 this.check_trait_item(
2110 |i, s, c| MethodNotMemberOfTrait(i, s, c),
2113 visit::walk_assoc_item(
2121 AssocItemKind::TyAlias(box TyAlias {
2124 debug!("resolve_implementation AssocItemKind::TyAlias");
2125 // We also need a new scope for the impl item type parameters.
2126 this.with_generic_param_rib(
2129 LifetimeRibKind::Generics { parent: item.id, span: generics.span, kind: LifetimeBinderKind::Item },
2131 // If this is a trait impl, ensure the type
2133 this.check_trait_item(
2139 |i, s, c| TypeNotMemberOfTrait(i, s, c),
2142 visit::walk_assoc_item(
2150 AssocItemKind::MacCall(_) => {
2151 panic!("unexpanded macro in resolve!")
2166 fn check_trait_item<F>(
2170 kind: &AssocItemKind,
2175 F: FnOnce(Ident, String, Option<Symbol>) -> ResolutionError<'a>,
2177 // If there is a TraitRef in scope for an impl, then the method must be in the trait.
2178 let Some((module, _)) = &self.current_trait_ref else { return; };
2179 ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
2180 let key = self.r.new_key(ident, ns);
2181 let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2183 if binding.is_none() {
2184 // We could not find the trait item in the correct namespace.
2185 // Check the other namespace to report an error.
2191 let key = self.r.new_key(ident, ns);
2192 binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2195 let Some(binding) = binding else {
2196 // We could not find the method: report an error.
2197 let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
2198 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2199 let path_names = path_names_to_string(path);
2200 self.report_error(span, err(ident, path_names, candidate));
2204 let res = binding.res();
2205 let Res::Def(def_kind, _) = res else { bug!() };
2206 match (def_kind, kind) {
2207 (DefKind::AssocTy, AssocItemKind::TyAlias(..))
2208 | (DefKind::AssocFn, AssocItemKind::Fn(..))
2209 | (DefKind::AssocConst, AssocItemKind::Const(..)) => {
2210 self.r.record_partial_res(id, PartialRes::new(res));
2216 // The method kind does not correspond to what appeared in the trait, report.
2217 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2218 let (code, kind) = match kind {
2219 AssocItemKind::Const(..) => (rustc_errors::error_code!(E0323), "const"),
2220 AssocItemKind::Fn(..) => (rustc_errors::error_code!(E0324), "method"),
2221 AssocItemKind::TyAlias(..) => (rustc_errors::error_code!(E0325), "type"),
2222 AssocItemKind::MacCall(..) => span_bug!(span, "unexpanded macro"),
2224 let trait_path = path_names_to_string(path);
2227 ResolutionError::TraitImplMismatch {
2232 trait_item_span: binding.span,
2237 fn resolve_params(&mut self, params: &'ast [Param]) {
2238 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2239 for Param { pat, ty, .. } in params {
2240 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
2242 debug!("(resolving function / closure) recorded parameter");
2246 fn resolve_local(&mut self, local: &'ast Local) {
2247 debug!("resolving local ({:?})", local);
2248 // Resolve the type.
2249 walk_list!(self, visit_ty, &local.ty);
2251 // Resolve the initializer.
2252 if let Some((init, els)) = local.kind.init_else_opt() {
2253 self.visit_expr(init);
2255 // Resolve the `else` block
2256 if let Some(els) = els {
2257 self.visit_block(els);
2261 // Resolve the pattern.
2262 self.resolve_pattern_top(&local.pat, PatternSource::Let);
2265 /// build a map from pattern identifiers to binding-info's.
2266 /// this is done hygienically. This could arise for a macro
2267 /// that expands into an or-pattern where one 'x' was from the
2268 /// user and one 'x' came from the macro.
2269 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2270 let mut binding_map = FxHashMap::default();
2272 pat.walk(&mut |pat| {
2274 PatKind::Ident(binding_mode, ident, ref sub_pat)
2275 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
2277 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
2279 PatKind::Or(ref ps) => {
2280 // Check the consistency of this or-pattern and
2281 // then add all bindings to the larger map.
2282 for bm in self.check_consistent_bindings(ps) {
2283 binding_map.extend(bm);
2296 fn is_base_res_local(&self, nid: NodeId) -> bool {
2297 matches!(self.r.partial_res_map.get(&nid).map(|res| res.base_res()), Some(Res::Local(..)))
2300 /// Checks that all of the arms in an or-pattern have exactly the
2301 /// same set of bindings, with the same binding modes for each.
2302 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
2303 let mut missing_vars = FxHashMap::default();
2304 let mut inconsistent_vars = FxHashMap::default();
2306 // 1) Compute the binding maps of all arms.
2307 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
2309 // 2) Record any missing bindings or binding mode inconsistencies.
2310 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
2311 // Check against all arms except for the same pattern which is always self-consistent.
2315 .filter(|(_, pat)| pat.id != pat_outer.id)
2316 .flat_map(|(idx, _)| maps[idx].iter())
2317 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
2319 for (name, info, &binding_inner) in inners {
2322 // The inner binding is missing in the outer.
2324 missing_vars.entry(name).or_insert_with(|| BindingError {
2326 origin: BTreeSet::new(),
2327 target: BTreeSet::new(),
2328 could_be_path: name.as_str().starts_with(char::is_uppercase),
2330 binding_error.origin.insert(binding_inner.span);
2331 binding_error.target.insert(pat_outer.span);
2333 Some(binding_outer) => {
2334 if binding_outer.binding_mode != binding_inner.binding_mode {
2335 // The binding modes in the outer and inner bindings differ.
2338 .or_insert((binding_inner.span, binding_outer.span));
2345 // 3) Report all missing variables we found.
2346 let mut missing_vars = missing_vars.into_iter().collect::<Vec<_>>();
2347 missing_vars.sort_by_key(|&(sym, ref _err)| sym);
2349 for (name, mut v) in missing_vars.into_iter() {
2350 if inconsistent_vars.contains_key(&name) {
2351 v.could_be_path = false;
2354 *v.origin.iter().next().unwrap(),
2355 ResolutionError::VariableNotBoundInPattern(v, self.parent_scope),
2359 // 4) Report all inconsistencies in binding modes we found.
2360 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
2361 inconsistent_vars.sort();
2362 for (name, v) in inconsistent_vars {
2363 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
2366 // 5) Finally bubble up all the binding maps.
2370 /// Check the consistency of the outermost or-patterns.
2371 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
2372 pat.walk(&mut |pat| match pat.kind {
2373 PatKind::Or(ref ps) => {
2374 self.check_consistent_bindings(ps);
2381 fn resolve_arm(&mut self, arm: &'ast Arm) {
2382 self.with_rib(ValueNS, NormalRibKind, |this| {
2383 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
2384 walk_list!(this, visit_expr, &arm.guard);
2385 this.visit_expr(&arm.body);
2389 /// Arising from `source`, resolve a top level pattern.
2390 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
2391 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2392 self.resolve_pattern(pat, pat_src, &mut bindings);
2398 pat_src: PatternSource,
2399 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
2401 // We walk the pattern before declaring the pattern's inner bindings,
2402 // so that we avoid resolving a literal expression to a binding defined
2404 visit::walk_pat(self, pat);
2405 self.resolve_pattern_inner(pat, pat_src, bindings);
2406 // This has to happen *after* we determine which pat_idents are variants:
2407 self.check_consistent_bindings_top(pat);
2410 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
2414 /// A stack of sets of bindings accumulated.
2416 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
2417 /// be interpreted as re-binding an already bound binding. This results in an error.
2418 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
2419 /// in reusing this binding rather than creating a fresh one.
2421 /// When called at the top level, the stack must have a single element
2422 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
2423 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
2424 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
2425 /// When each `p_i` has been dealt with, the top set is merged with its parent.
2426 /// When a whole or-pattern has been dealt with, the thing happens.
2428 /// See the implementation and `fresh_binding` for more details.
2429 fn resolve_pattern_inner(
2432 pat_src: PatternSource,
2433 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
2435 // Visit all direct subpatterns of this pattern.
2436 pat.walk(&mut |pat| {
2437 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
2439 PatKind::Ident(bmode, ident, ref sub) => {
2440 // First try to resolve the identifier as some existing entity,
2441 // then fall back to a fresh binding.
2442 let has_sub = sub.is_some();
2444 .try_resolve_as_non_binding(pat_src, bmode, ident, has_sub)
2445 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
2446 self.r.record_partial_res(pat.id, PartialRes::new(res));
2447 self.r.record_pat_span(pat.id, pat.span);
2449 PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
2450 self.smart_resolve_path(
2454 PathSource::TupleStruct(
2456 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
2460 PatKind::Path(ref qself, ref path) => {
2461 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
2463 PatKind::Struct(ref qself, ref path, ..) => {
2464 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Struct);
2466 PatKind::Or(ref ps) => {
2467 // Add a new set of bindings to the stack. `Or` here records that when a
2468 // binding already exists in this set, it should not result in an error because
2469 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
2470 bindings.push((PatBoundCtx::Or, Default::default()));
2472 // Now we need to switch back to a product context so that each
2473 // part of the or-pattern internally rejects already bound names.
2474 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
2475 bindings.push((PatBoundCtx::Product, Default::default()));
2476 self.resolve_pattern_inner(p, pat_src, bindings);
2477 // Move up the non-overlapping bindings to the or-pattern.
2478 // Existing bindings just get "merged".
2479 let collected = bindings.pop().unwrap().1;
2480 bindings.last_mut().unwrap().1.extend(collected);
2482 // This or-pattern itself can itself be part of a product,
2483 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
2484 // Both cases bind `a` again in a product pattern and must be rejected.
2485 let collected = bindings.pop().unwrap().1;
2486 bindings.last_mut().unwrap().1.extend(collected);
2488 // Prevent visiting `ps` as we've already done so above.
2501 pat_src: PatternSource,
2502 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
2504 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
2505 // (We must not add it if it's in the bindings map because that breaks the assumptions
2506 // later passes make about or-patterns.)
2507 let ident = ident.normalize_to_macro_rules();
2509 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
2510 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
2511 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
2512 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
2513 // This is *required* for consistency which is checked later.
2514 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
2516 if already_bound_and {
2517 // Overlap in a product pattern somewhere; report an error.
2518 use ResolutionError::*;
2519 let error = match pat_src {
2520 // `fn f(a: u8, a: u8)`:
2521 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
2523 _ => IdentifierBoundMoreThanOnceInSamePattern,
2525 self.report_error(ident.span, error(ident.name));
2528 // Record as bound if it's valid:
2529 let ident_valid = ident.name != kw::Empty;
2531 bindings.last_mut().unwrap().1.insert(ident);
2534 if already_bound_or {
2535 // `Variant1(a) | Variant2(a)`, ok
2536 // Reuse definition from the first `a`.
2537 self.innermost_rib_bindings(ValueNS)[&ident]
2539 let res = Res::Local(pat_id);
2541 // A completely fresh binding add to the set if it's valid.
2542 self.innermost_rib_bindings(ValueNS).insert(ident, res);
2548 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
2549 &mut self.ribs[ns].last_mut().unwrap().bindings
2552 fn try_resolve_as_non_binding(
2554 pat_src: PatternSource,
2559 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
2560 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
2561 // also be interpreted as a path to e.g. a constant, variant, etc.
2562 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
2564 let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?;
2565 let (res, binding) = match ls_binding {
2566 LexicalScopeBinding::Item(binding)
2567 if is_syntactic_ambiguity && binding.is_ambiguity() =>
2569 // For ambiguous bindings we don't know all their definitions and cannot check
2570 // whether they can be shadowed by fresh bindings or not, so force an error.
2571 // issues/33118#issuecomment-233962221 (see below) still applies here,
2572 // but we have to ignore it for backward compatibility.
2573 self.r.record_use(ident, binding, false);
2576 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
2577 LexicalScopeBinding::Res(res) => (res, None),
2581 Res::SelfCtor(_) // See #70549.
2583 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
2585 ) if is_syntactic_ambiguity => {
2586 // Disambiguate in favor of a unit struct/variant or constant pattern.
2587 if let Some(binding) = binding {
2588 self.r.record_use(ident, binding, false);
2592 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static(_), _) => {
2593 // This is unambiguously a fresh binding, either syntactically
2594 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
2595 // to something unusable as a pattern (e.g., constructor function),
2596 // but we still conservatively report an error, see
2597 // issues/33118#issuecomment-233962221 for one reason why.
2598 let binding = binding.expect("no binding for a ctor or static");
2601 ResolutionError::BindingShadowsSomethingUnacceptable {
2602 shadowing_binding_descr: pat_src.descr(),
2604 participle: if binding.is_import() { "imported" } else { "defined" },
2605 article: binding.res().article(),
2606 shadowed_binding_descr: binding.res().descr(),
2607 shadowed_binding_span: binding.span,
2612 Res::Def(DefKind::ConstParam, def_id) => {
2613 // Same as for DefKind::Const above, but here, `binding` is `None`, so we
2614 // have to construct the error differently
2617 ResolutionError::BindingShadowsSomethingUnacceptable {
2618 shadowing_binding_descr: pat_src.descr(),
2620 participle: "defined",
2621 article: res.article(),
2622 shadowed_binding_descr: res.descr(),
2623 shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"),
2628 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
2629 // These entities are explicitly allowed to be shadowed by fresh bindings.
2632 Res::SelfCtor(_) => {
2633 // We resolve `Self` in pattern position as an ident sometimes during recovery,
2634 // so delay a bug instead of ICEing.
2635 self.r.session.delay_span_bug(
2637 "unexpected `SelfCtor` in pattern, expected identifier"
2643 "unexpected resolution for an identifier in pattern: {:?}",
2649 // High-level and context dependent path resolution routine.
2650 // Resolves the path and records the resolution into definition map.
2651 // If resolution fails tries several techniques to find likely
2652 // resolution candidates, suggest imports or other help, and report
2653 // errors in user friendly way.
2654 fn smart_resolve_path(
2657 qself: Option<&QSelf>,
2659 source: PathSource<'ast>,
2661 self.smart_resolve_path_fragment(
2663 &Segment::from_path(path),
2665 Finalize::new(id, path.span),
2669 fn smart_resolve_path_fragment(
2671 qself: Option<&QSelf>,
2673 source: PathSource<'ast>,
2677 "smart_resolve_path_fragment(qself={:?}, path={:?}, finalize={:?})",
2682 let ns = source.namespace();
2684 let Finalize { node_id, path_span, .. } = finalize;
2685 let report_errors = |this: &mut Self, res: Option<Res>| {
2686 if this.should_report_errs() {
2687 let (err, candidates) =
2688 this.smart_resolve_report_errors(path, path_span, source, res);
2690 let def_id = this.parent_scope.module.nearest_parent_mod();
2691 let instead = res.is_some();
2693 if res.is_none() { this.report_missing_type_error(path) } else { None };
2695 this.r.use_injections.push(UseError {
2705 PartialRes::new(Res::Err)
2708 // For paths originating from calls (like in `HashMap::new()`), tries
2709 // to enrich the plain `failed to resolve: ...` message with hints
2710 // about possible missing imports.
2712 // Similar thing, for types, happens in `report_errors` above.
2713 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
2714 if !source.is_call() {
2715 return Some(parent_err);
2718 // Before we start looking for candidates, we have to get our hands
2719 // on the type user is trying to perform invocation on; basically:
2720 // we're transforming `HashMap::new` into just `HashMap`.
2721 let path = match path.split_last() {
2722 Some((_, path)) if !path.is_empty() => path,
2723 _ => return Some(parent_err),
2726 let (mut err, candidates) =
2727 this.smart_resolve_report_errors(path, path_span, PathSource::Type, None);
2729 if candidates.is_empty() {
2731 return Some(parent_err);
2734 // There are two different error messages user might receive at
2736 // - E0412 cannot find type `{}` in this scope
2737 // - E0433 failed to resolve: use of undeclared type or module `{}`
2739 // The first one is emitted for paths in type-position, and the
2740 // latter one - for paths in expression-position.
2742 // Thus (since we're in expression-position at this point), not to
2743 // confuse the user, we want to keep the *message* from E0432 (so
2744 // `parent_err`), but we want *hints* from E0412 (so `err`).
2746 // And that's what happens below - we're just mixing both messages
2747 // into a single one.
2748 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
2750 err.message = take(&mut parent_err.message);
2751 err.code = take(&mut parent_err.code);
2752 err.children = take(&mut parent_err.children);
2754 parent_err.cancel();
2756 let def_id = this.parent_scope.module.nearest_parent_mod();
2758 if this.should_report_errs() {
2759 this.r.use_injections.push(UseError {
2771 // We don't return `Some(parent_err)` here, because the error will
2772 // be already printed as part of the `use` injections
2776 let partial_res = match self.resolve_qpath_anywhere(
2781 source.defer_to_typeck(),
2784 Ok(Some(partial_res)) if partial_res.unresolved_segments() == 0 => {
2785 if source.is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err
2789 report_errors(self, Some(partial_res.base_res()))
2793 Ok(Some(partial_res)) if source.defer_to_typeck() => {
2794 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
2795 // or `<T>::A::B`. If `B` should be resolved in value namespace then
2796 // it needs to be added to the trait map.
2798 let item_name = path.last().unwrap().ident;
2799 let traits = self.traits_in_scope(item_name, ns);
2800 self.r.trait_map.insert(node_id, traits);
2803 if PrimTy::from_name(path[0].ident.name).is_some() {
2804 let mut std_path = Vec::with_capacity(1 + path.len());
2806 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
2807 std_path.extend(path);
2808 if let PathResult::Module(_) | PathResult::NonModule(_) =
2809 self.resolve_path(&std_path, Some(ns), None)
2811 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
2813 path.iter().last().map_or(path_span, |segment| segment.ident.span);
2815 self.r.confused_type_with_std_module.insert(item_span, path_span);
2816 self.r.confused_type_with_std_module.insert(path_span, path_span);
2824 if let Some(err) = report_errors_for_call(self, err) {
2825 self.report_error(err.span, err.node);
2828 PartialRes::new(Res::Err)
2831 _ => report_errors(self, None),
2834 if !matches!(source, PathSource::TraitItem(..)) {
2835 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
2836 self.r.record_partial_res(node_id, partial_res);
2837 self.resolve_elided_lifetimes_in_path(node_id, partial_res, path, source, path_span);
2843 fn self_type_is_available(&mut self) -> bool {
2845 .maybe_resolve_ident_in_lexical_scope(Ident::with_dummy_span(kw::SelfUpper), TypeNS);
2846 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
2849 fn self_value_is_available(&mut self, self_span: Span) -> bool {
2850 let ident = Ident::new(kw::SelfLower, self_span);
2851 let binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS);
2852 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
2855 /// A wrapper around [`Resolver::report_error`].
2857 /// This doesn't emit errors for function bodies if this is rustdoc.
2858 fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) {
2859 if self.should_report_errs() {
2860 self.r.report_error(span, resolution_error);
2865 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
2866 fn should_report_errs(&self) -> bool {
2867 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
2870 // Resolve in alternative namespaces if resolution in the primary namespace fails.
2871 fn resolve_qpath_anywhere(
2873 qself: Option<&QSelf>,
2875 primary_ns: Namespace,
2877 defer_to_typeck: bool,
2879 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2880 let mut fin_res = None;
2882 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
2883 if i == 0 || ns != primary_ns {
2884 match self.resolve_qpath(qself, path, ns, finalize)? {
2886 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
2888 return Ok(Some(partial_res));
2891 if fin_res.is_none() {
2892 fin_res = partial_res;
2899 assert!(primary_ns != MacroNS);
2901 if qself.is_none() {
2902 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
2903 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
2904 if let Ok((_, res)) =
2905 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
2907 return Ok(Some(PartialRes::new(res)));
2914 /// Handles paths that may refer to associated items.
2917 qself: Option<&QSelf>,
2921 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2923 "resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})",
2924 qself, path, ns, finalize,
2927 if let Some(qself) = qself {
2928 if qself.position == 0 {
2929 // This is a case like `<T>::B`, where there is no
2930 // trait to resolve. In that case, we leave the `B`
2931 // segment to be resolved by type-check.
2932 return Ok(Some(PartialRes::with_unresolved_segments(
2933 Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()),
2938 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
2940 // Currently, `path` names the full item (`A::B::C`, in
2941 // our example). so we extract the prefix of that that is
2942 // the trait (the slice upto and including
2943 // `qself.position`). And then we recursively resolve that,
2944 // but with `qself` set to `None`.
2945 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2946 let partial_res = self.smart_resolve_path_fragment(
2948 &path[..=qself.position],
2949 PathSource::TraitItem(ns),
2950 Finalize::with_root_span(finalize.node_id, finalize.path_span, qself.path_span),
2953 // The remaining segments (the `C` in our example) will
2954 // have to be resolved by type-check, since that requires doing
2955 // trait resolution.
2956 return Ok(Some(PartialRes::with_unresolved_segments(
2957 partial_res.base_res(),
2958 partial_res.unresolved_segments() + path.len() - qself.position - 1,
2962 let result = match self.resolve_path(&path, Some(ns), Some(finalize)) {
2963 PathResult::NonModule(path_res) => path_res,
2964 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
2965 PartialRes::new(module.res().unwrap())
2967 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2968 // don't report an error right away, but try to fallback to a primitive type.
2969 // So, we are still able to successfully resolve something like
2971 // use std::u8; // bring module u8 in scope
2972 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2973 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
2974 // // not to non-existent std::u8::max_value
2977 // Such behavior is required for backward compatibility.
2978 // The same fallback is used when `a` resolves to nothing.
2979 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
2980 if (ns == TypeNS || path.len() > 1)
2981 && PrimTy::from_name(path[0].ident.name).is_some() =>
2983 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
2984 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
2986 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2987 PartialRes::new(module.res().unwrap())
2989 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
2990 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
2992 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
2993 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
2997 && result.base_res() != Res::Err
2998 && path[0].ident.name != kw::PathRoot
2999 && path[0].ident.name != kw::DollarCrate
3001 let unqualified_result = {
3002 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
3003 PathResult::NonModule(path_res) => path_res.base_res(),
3004 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3005 module.res().unwrap()
3007 _ => return Ok(Some(result)),
3010 if result.base_res() == unqualified_result {
3011 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
3012 self.r.lint_buffer.buffer_lint(
3016 "unnecessary qualification",
3024 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
3025 if let Some(label) = label {
3026 if label.ident.as_str().as_bytes()[1] != b'_' {
3027 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
3029 self.with_label_rib(NormalRibKind, |this| {
3030 let ident = label.ident.normalize_to_macro_rules();
3031 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
3039 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
3040 self.with_resolved_label(label, id, |this| this.visit_block(block));
3043 fn resolve_block(&mut self, block: &'ast Block) {
3044 debug!("(resolving block) entering block");
3045 // Move down in the graph, if there's an anonymous module rooted here.
3046 let orig_module = self.parent_scope.module;
3047 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
3049 let mut num_macro_definition_ribs = 0;
3050 if let Some(anonymous_module) = anonymous_module {
3051 debug!("(resolving block) found anonymous module, moving down");
3052 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3053 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3054 self.parent_scope.module = anonymous_module;
3056 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3059 let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
3060 if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
3061 (block.could_be_bare_literal, &block.stmts[..])
3062 && let ExprKind::Type(..) = expr.kind
3064 self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
3067 // Descend into the block.
3068 for stmt in &block.stmts {
3069 if let StmtKind::Item(ref item) = stmt.kind
3070 && let ItemKind::MacroDef(..) = item.kind {
3071 num_macro_definition_ribs += 1;
3072 let res = self.r.local_def_id(item.id).to_def_id();
3073 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
3074 self.label_ribs.push(Rib::new(MacroDefinition(res)));
3077 self.visit_stmt(stmt);
3079 self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
3082 self.parent_scope.module = orig_module;
3083 for _ in 0..num_macro_definition_ribs {
3084 self.ribs[ValueNS].pop();
3085 self.label_ribs.pop();
3087 self.ribs[ValueNS].pop();
3088 if anonymous_module.is_some() {
3089 self.ribs[TypeNS].pop();
3091 debug!("(resolving block) leaving block");
3094 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
3095 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
3096 self.with_constant_rib(
3098 if constant.value.is_potential_trivial_const_param() {
3099 HasGenericParams::Yes
3101 HasGenericParams::No
3104 |this| visit::walk_anon_const(this, constant),
3108 fn resolve_inline_const(&mut self, constant: &'ast AnonConst) {
3109 debug!("resolve_anon_const {constant:?}");
3110 self.with_constant_rib(IsRepeatExpr::No, HasGenericParams::Yes, None, |this| {
3111 visit::walk_anon_const(this, constant);
3115 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
3116 // First, record candidate traits for this expression if it could
3117 // result in the invocation of a method call.
3119 self.record_candidate_traits_for_expr_if_necessary(expr);
3121 // Next, resolve the node.
3123 ExprKind::Path(ref qself, ref path) => {
3124 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
3125 visit::walk_expr(self, expr);
3128 ExprKind::Struct(ref se) => {
3129 self.smart_resolve_path(expr.id, se.qself.as_ref(), &se.path, PathSource::Struct);
3130 visit::walk_expr(self, expr);
3133 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
3134 if let Some(node_id) = self.resolve_label(label.ident) {
3135 // Since this res is a label, it is never read.
3136 self.r.label_res_map.insert(expr.id, node_id);
3137 self.diagnostic_metadata.unused_labels.remove(&node_id);
3140 // visit `break` argument if any
3141 visit::walk_expr(self, expr);
3144 ExprKind::Break(None, Some(ref e)) => {
3145 // We use this instead of `visit::walk_expr` to keep the parent expr around for
3146 // better diagnostics.
3147 self.resolve_expr(e, Some(&expr));
3150 ExprKind::Let(ref pat, ref scrutinee, _) => {
3151 self.visit_expr(scrutinee);
3152 self.resolve_pattern_top(pat, PatternSource::Let);
3155 ExprKind::If(ref cond, ref then, ref opt_else) => {
3156 self.with_rib(ValueNS, NormalRibKind, |this| {
3157 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3158 this.visit_expr(cond);
3159 this.diagnostic_metadata.in_if_condition = old;
3160 this.visit_block(then);
3162 if let Some(expr) = opt_else {
3163 self.visit_expr(expr);
3167 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3169 ExprKind::While(ref cond, ref block, label) => {
3170 self.with_resolved_label(label, expr.id, |this| {
3171 this.with_rib(ValueNS, NormalRibKind, |this| {
3172 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3173 this.visit_expr(cond);
3174 this.diagnostic_metadata.in_if_condition = old;
3175 this.visit_block(block);
3180 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
3181 self.visit_expr(iter_expr);
3182 self.with_rib(ValueNS, NormalRibKind, |this| {
3183 this.resolve_pattern_top(pat, PatternSource::For);
3184 this.resolve_labeled_block(label, expr.id, block);
3188 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
3190 // Equivalent to `visit::walk_expr` + passing some context to children.
3191 ExprKind::Field(ref subexpression, _) => {
3192 self.resolve_expr(subexpression, Some(expr));
3194 ExprKind::MethodCall(ref segment, ref arguments, _) => {
3195 let mut arguments = arguments.iter();
3196 self.resolve_expr(arguments.next().unwrap(), Some(expr));
3197 for argument in arguments {
3198 self.resolve_expr(argument, None);
3200 self.visit_path_segment(expr.span, segment);
3203 ExprKind::Call(ref callee, ref arguments) => {
3204 self.resolve_expr(callee, Some(expr));
3205 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
3206 for (idx, argument) in arguments.iter().enumerate() {
3207 // Constant arguments need to be treated as AnonConst since
3208 // that is how they will be later lowered to HIR.
3209 if const_args.contains(&idx) {
3210 self.with_constant_rib(
3212 if argument.is_potential_trivial_const_param() {
3213 HasGenericParams::Yes
3215 HasGenericParams::No
3219 this.resolve_expr(argument, None);
3223 self.resolve_expr(argument, None);
3227 ExprKind::Type(ref type_expr, ref ty) => {
3228 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
3229 // type ascription. Here we are trying to retrieve the span of the colon token as
3230 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
3231 // with `expr::Ty`, only in this case it will match the span from
3232 // `type_ascription_path_suggestions`.
3233 self.diagnostic_metadata
3234 .current_type_ascription
3235 .push(type_expr.span.between(ty.span));
3236 visit::walk_expr(self, expr);
3237 self.diagnostic_metadata.current_type_ascription.pop();
3239 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
3240 // resolve the arguments within the proper scopes so that usages of them inside the
3241 // closure are detected as upvars rather than normal closure arg usages.
3242 ExprKind::Closure(_, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
3243 self.with_rib(ValueNS, NormalRibKind, |this| {
3244 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
3245 // Resolve arguments:
3246 this.resolve_params(&fn_decl.inputs);
3247 // No need to resolve return type --
3248 // the outer closure return type is `FnRetTy::Default`.
3250 // Now resolve the inner closure
3252 // No need to resolve arguments: the inner closure has none.
3253 // Resolve the return type:
3254 visit::walk_fn_ret_ty(this, &fn_decl.output);
3256 this.visit_expr(body);
3261 ExprKind::Async(..) | ExprKind::Closure(..) => {
3262 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
3264 ExprKind::Repeat(ref elem, ref ct) => {
3265 self.visit_expr(elem);
3266 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
3267 this.resolve_anon_const(ct, IsRepeatExpr::Yes)
3270 ExprKind::ConstBlock(ref ct) => {
3271 self.resolve_inline_const(ct);
3273 ExprKind::Index(ref elem, ref idx) => {
3274 self.resolve_expr(elem, Some(expr));
3275 self.visit_expr(idx);
3278 visit::walk_expr(self, expr);
3283 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
3285 ExprKind::Field(_, ident) => {
3286 // FIXME(#6890): Even though you can't treat a method like a
3287 // field, we need to add any trait methods we find that match
3288 // the field name so that we can do some nice error reporting
3289 // later on in typeck.
3290 let traits = self.traits_in_scope(ident, ValueNS);
3291 self.r.trait_map.insert(expr.id, traits);
3293 ExprKind::MethodCall(ref segment, ..) => {
3294 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
3295 let traits = self.traits_in_scope(segment.ident, ValueNS);
3296 self.r.trait_map.insert(expr.id, traits);
3304 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
3305 self.r.traits_in_scope(
3306 self.current_trait_ref.as_ref().map(|(module, _)| *module),
3309 Some((ident.name, ns)),
3314 struct LifetimeCountVisitor<'a, 'b> {
3315 r: &'b mut Resolver<'a>,
3318 /// Walks the whole crate in DFS order, visiting each item, counting the declared number of
3319 /// lifetime generic parameters.
3320 impl<'ast> Visitor<'ast> for LifetimeCountVisitor<'_, '_> {
3321 fn visit_item(&mut self, item: &'ast Item) {
3323 ItemKind::TyAlias(box TyAlias { ref generics, .. })
3324 | ItemKind::Fn(box Fn { ref generics, .. })
3325 | ItemKind::Enum(_, ref generics)
3326 | ItemKind::Struct(_, ref generics)
3327 | ItemKind::Union(_, ref generics)
3328 | ItemKind::Impl(box Impl { ref generics, .. })
3329 | ItemKind::Trait(box Trait { ref generics, .. })
3330 | ItemKind::TraitAlias(ref generics, _) => {
3331 let def_id = self.r.local_def_id(item.id);
3332 let count = generics
3335 .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
3337 self.r.item_generics_num_lifetimes.insert(def_id, count);
3341 | ItemKind::ForeignMod(..)
3342 | ItemKind::Static(..)
3343 | ItemKind::Const(..)
3345 | ItemKind::ExternCrate(..)
3346 | ItemKind::MacroDef(..)
3347 | ItemKind::GlobalAsm(..)
3348 | ItemKind::MacCall(..) => {}
3350 visit::walk_item(self, item)
3354 impl<'a> Resolver<'a> {
3355 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
3356 visit::walk_crate(&mut LifetimeCountVisitor { r: self }, krate);
3357 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
3358 visit::walk_crate(&mut late_resolution_visitor, krate);
3359 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
3360 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");