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 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
98 crate enum ConstantItemKind {
103 /// The rib kind restricts certain accesses,
104 /// e.g. to a `Res::Local` of an outer item.
105 #[derive(Copy, Clone, Debug)]
106 crate enum RibKind<'a> {
107 /// No restriction needs to be applied.
110 /// We passed through an impl or trait and are now in one of its
111 /// methods or associated types. Allow references to ty params that impl or trait
112 /// binds. Disallow any other upvars (including other ty params that are
116 /// We passed through a closure. Disallow labels.
117 ClosureOrAsyncRibKind,
119 /// We passed through a function definition. Disallow upvars.
120 /// Permit only those const parameters that are specified in the function's generics.
123 /// We passed through an item scope. Disallow upvars.
124 ItemRibKind(HasGenericParams),
126 /// We're in a constant item. Can't refer to dynamic stuff.
128 /// The `bool` indicates if this constant may reference generic parameters
129 /// and is used to only allow generic parameters to be used in trivial constant expressions.
130 ConstantItemRibKind(bool, Option<(Ident, ConstantItemKind)>),
132 /// We passed through a module.
133 ModuleRibKind(Module<'a>),
135 /// We passed through a `macro_rules!` statement
136 MacroDefinition(DefId),
138 /// All bindings in this rib are generic parameters that can't be used
139 /// from the default of a generic parameter because they're not declared
140 /// before said generic parameter. Also see the `visit_generics` override.
141 ForwardGenericParamBanRibKind,
143 /// We are inside of the type of a const parameter. Can't refer to any
147 /// We are inside a `sym` inline assembly operand. Can only refer to
153 /// Whether this rib kind contains generic parameters, as opposed to local
155 crate fn contains_params(&self) -> bool {
158 | ClosureOrAsyncRibKind
160 | ConstantItemRibKind(..)
163 | ConstParamTyRibKind
164 | InlineAsmSymRibKind => false,
165 AssocItemRibKind | ItemRibKind(_) | ForwardGenericParamBanRibKind => true,
170 /// A single local scope.
172 /// A rib represents a scope names can live in. Note that these appear in many places, not just
173 /// around braces. At any place where the list of accessible names (of the given namespace)
174 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
175 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
178 /// Different [rib kinds](enum.RibKind) are transparent for different names.
180 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
181 /// resolving, the name is looked up from inside out.
183 crate struct Rib<'a, R = Res> {
184 pub bindings: IdentMap<R>,
185 pub kind: RibKind<'a>,
188 impl<'a, R> Rib<'a, R> {
189 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
190 Rib { bindings: Default::default(), kind }
194 #[derive(Copy, Clone, Debug)]
195 enum LifetimeRibKind {
196 /// This rib acts as a barrier to forbid reference to lifetimes of a parent item.
199 /// This rib declares generic parameters.
200 Generics { parent: NodeId, span: Span, kind: LifetimeBinderKind },
202 /// FIXME(const_generics): This patches over an ICE caused by non-'static lifetimes in const
203 /// generics. We are disallowing this until we can decide on how we want to handle non-'static
204 /// lifetimes in const generics. See issue #74052 for discussion.
207 /// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`.
208 /// This function will emit an error if `generic_const_exprs` is not enabled, the body identified by
209 /// `body_id` is an anonymous constant and `lifetime_ref` is non-static.
212 /// For **Modern** cases, create a new anonymous region parameter
213 /// and reference that.
215 /// For **Dyn Bound** cases, pass responsibility to
216 /// `resolve_lifetime` code.
218 /// For **Deprecated** cases, report an error.
219 AnonymousCreateParameter(NodeId),
221 /// Give a hard error when either `&` or `'_` is written. Used to
222 /// rule out things like `where T: Foo<'_>`. Does not imply an
223 /// error on default object bounds (e.g., `Box<dyn Foo>`).
224 AnonymousReportError,
226 /// Pass responsibility to `resolve_lifetime` code for all cases.
227 AnonymousPassThrough(NodeId),
230 #[derive(Copy, Clone, Debug)]
231 enum LifetimeBinderKind {
240 impl LifetimeBinderKind {
241 fn descr(self) -> &'static str {
242 use LifetimeBinderKind::*;
244 BareFnType => "type",
245 PolyTrait => "bound",
246 WhereBound => "bound",
248 ImplBlock => "impl block",
249 Function => "function",
256 kind: LifetimeRibKind,
257 // We need to preserve insertion order for async fns.
258 bindings: FxIndexMap<Ident, (NodeId, LifetimeRes)>,
262 fn new(kind: LifetimeRibKind) -> LifetimeRib {
263 LifetimeRib { bindings: Default::default(), kind }
267 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
268 crate enum AliasPossibility {
273 #[derive(Copy, Clone, Debug)]
274 crate enum PathSource<'a> {
275 // Type paths `Path`.
277 // Trait paths in bounds or impls.
278 Trait(AliasPossibility),
279 // Expression paths `path`, with optional parent context.
280 Expr(Option<&'a Expr>),
281 // Paths in path patterns `Path`.
283 // Paths in struct expressions and patterns `Path { .. }`.
285 // Paths in tuple struct patterns `Path(..)`.
286 TupleStruct(Span, &'a [Span]),
287 // `m::A::B` in `<T as m::A>::B::C`.
288 TraitItem(Namespace),
291 impl<'a> PathSource<'a> {
292 fn namespace(self) -> Namespace {
294 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
295 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
296 PathSource::TraitItem(ns) => ns,
300 fn defer_to_typeck(self) -> bool {
303 | PathSource::Expr(..)
306 | PathSource::TupleStruct(..) => true,
307 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
311 fn descr_expected(self) -> &'static str {
313 PathSource::Type => "type",
314 PathSource::Trait(_) => "trait",
315 PathSource::Pat => "unit struct, unit variant or constant",
316 PathSource::Struct => "struct, variant or union type",
317 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
318 PathSource::TraitItem(ns) => match ns {
319 TypeNS => "associated type",
320 ValueNS => "method or associated constant",
321 MacroNS => bug!("associated macro"),
323 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
324 // "function" here means "anything callable" rather than `DefKind::Fn`,
325 // this is not precise but usually more helpful than just "value".
326 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
327 // the case of `::some_crate()`
328 ExprKind::Path(_, path)
329 if path.segments.len() == 2
330 && path.segments[0].ident.name == kw::PathRoot =>
334 ExprKind::Path(_, path) => {
335 let mut msg = "function";
336 if let Some(segment) = path.segments.iter().last() {
337 if let Some(c) = segment.ident.to_string().chars().next() {
338 if c.is_uppercase() {
339 msg = "function, tuple struct or tuple variant";
352 fn is_call(self) -> bool {
353 matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
356 crate fn is_expected(self, res: Res) -> bool {
358 PathSource::Type => matches!(
365 | DefKind::TraitAlias
370 | DefKind::ForeignTy,
375 PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
376 PathSource::Trait(AliasPossibility::Maybe) => {
377 matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
379 PathSource::Expr(..) => matches!(
382 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
387 | DefKind::AssocConst
388 | DefKind::ConstParam,
393 PathSource::Pat => matches!(
396 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::AssocConst,
398 ) | Res::SelfCtor(..)
400 PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
401 PathSource::Struct => matches!(
410 ) | Res::SelfTy { .. }
412 PathSource::TraitItem(ns) => match res {
413 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
414 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
420 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
421 use rustc_errors::error_code;
422 match (self, has_unexpected_resolution) {
423 (PathSource::Trait(_), true) => error_code!(E0404),
424 (PathSource::Trait(_), false) => error_code!(E0405),
425 (PathSource::Type, true) => error_code!(E0573),
426 (PathSource::Type, false) => error_code!(E0412),
427 (PathSource::Struct, true) => error_code!(E0574),
428 (PathSource::Struct, false) => error_code!(E0422),
429 (PathSource::Expr(..), true) => error_code!(E0423),
430 (PathSource::Expr(..), false) => error_code!(E0425),
431 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
432 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
433 (PathSource::TraitItem(..), true) => error_code!(E0575),
434 (PathSource::TraitItem(..), false) => error_code!(E0576),
440 struct DiagnosticMetadata<'ast> {
441 /// The current trait's associated items' ident, used for diagnostic suggestions.
442 current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
444 /// The current self type if inside an impl (used for better errors).
445 current_self_type: Option<Ty>,
447 /// The current self item if inside an ADT (used for better errors).
448 current_self_item: Option<NodeId>,
450 /// The current trait (used to suggest).
451 current_item: Option<&'ast Item>,
453 /// When processing generics and encountering a type not found, suggest introducing a type
455 currently_processing_generics: bool,
457 /// The current enclosing (non-closure) function (used for better errors).
458 current_function: Option<(FnKind<'ast>, Span)>,
460 /// A list of labels as of yet unused. Labels will be removed from this map when
461 /// they are used (in a `break` or `continue` statement)
462 unused_labels: FxHashMap<NodeId, Span>,
464 /// Only used for better errors on `fn(): fn()`.
465 current_type_ascription: Vec<Span>,
467 /// Only used for better errors on `let x = { foo: bar };`.
468 /// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only
469 /// needed for cases where this parses as a correct type ascription.
470 current_block_could_be_bare_struct_literal: Option<Span>,
472 /// Only used for better errors on `let <pat>: <expr, not type>;`.
473 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
475 /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
476 in_if_condition: Option<&'ast Expr>,
478 /// If we are currently in a trait object definition. Used to point at the bounds when
479 /// encountering a struct or enum.
480 current_trait_object: Option<&'ast [ast::GenericBound]>,
482 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
483 current_where_predicate: Option<&'ast WherePredicate>,
485 current_type_path: Option<&'ast Ty>,
488 struct LateResolutionVisitor<'a, 'b, 'ast> {
489 r: &'b mut Resolver<'a>,
491 /// The module that represents the current item scope.
492 parent_scope: ParentScope<'a>,
494 /// The current set of local scopes for types and values.
495 /// FIXME #4948: Reuse ribs to avoid allocation.
496 ribs: PerNS<Vec<Rib<'a>>>,
498 /// The current set of local scopes, for labels.
499 label_ribs: Vec<Rib<'a, NodeId>>,
501 /// The current set of local scopes for lifetimes.
502 lifetime_ribs: Vec<LifetimeRib>,
504 /// The trait that the current context can refer to.
505 current_trait_ref: Option<(Module<'a>, TraitRef)>,
507 /// Fields used to add information to diagnostic errors.
508 diagnostic_metadata: DiagnosticMetadata<'ast>,
510 /// State used to know whether to ignore resolution errors for function bodies.
512 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
513 /// In most cases this will be `None`, in which case errors will always be reported.
514 /// If it is `true`, then it will be updated when entering a nested function or trait body.
518 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
519 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
520 fn visit_attribute(&mut self, _: &'ast Attribute) {
521 // We do not want to resolve expressions that appear in attributes,
522 // as they do not correspond to actual code.
524 fn visit_item(&mut self, item: &'ast Item) {
525 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
526 // Always report errors in items we just entered.
527 let old_ignore = replace(&mut self.in_func_body, false);
528 self.with_lifetime_rib(LifetimeRibKind::Item, |this| this.resolve_item(item));
529 self.in_func_body = old_ignore;
530 self.diagnostic_metadata.current_item = prev;
532 fn visit_arm(&mut self, arm: &'ast Arm) {
533 self.resolve_arm(arm);
535 fn visit_block(&mut self, block: &'ast Block) {
536 self.resolve_block(block);
538 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
539 // We deal with repeat expressions explicitly in `resolve_expr`.
540 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
541 this.resolve_anon_const(constant, IsRepeatExpr::No);
544 fn visit_expr(&mut self, expr: &'ast Expr) {
545 self.resolve_expr(expr, None);
547 fn visit_local(&mut self, local: &'ast Local) {
548 let local_spans = match local.pat.kind {
549 // We check for this to avoid tuple struct fields.
550 PatKind::Wild => None,
553 local.ty.as_ref().map(|ty| ty.span),
554 local.kind.init().map(|init| init.span),
557 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
558 self.resolve_local(local);
559 self.diagnostic_metadata.current_let_binding = original;
561 fn visit_ty(&mut self, ty: &'ast Ty) {
562 let prev = self.diagnostic_metadata.current_trait_object;
563 let prev_ty = self.diagnostic_metadata.current_type_path;
565 TyKind::Rptr(None, _) => {
566 // Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
568 let span = self.r.session.source_map().next_point(ty.span.shrink_to_lo());
569 self.resolve_elided_lifetime(ty.id, span);
571 TyKind::Path(ref qself, ref path) => {
572 self.diagnostic_metadata.current_type_path = Some(ty);
573 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
575 TyKind::ImplicitSelf => {
576 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
578 .resolve_ident_in_lexical_scope(
581 Some(Finalize::new(ty.id, ty.span)),
584 .map_or(Res::Err, |d| d.res());
585 self.r.record_partial_res(ty.id, PartialRes::new(res));
587 TyKind::TraitObject(ref bounds, ..) => {
588 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
590 TyKind::BareFn(ref bare_fn) => {
591 let span = if bare_fn.generic_params.is_empty() {
592 ty.span.shrink_to_lo()
596 self.with_generic_param_rib(
597 &bare_fn.generic_params,
599 LifetimeRibKind::Generics {
601 kind: LifetimeBinderKind::BareFnType,
605 this.with_lifetime_rib(
606 LifetimeRibKind::AnonymousPassThrough(ty.id),
608 this.visit_generic_param_vec(&bare_fn.generic_params, false);
609 visit::walk_fn_decl(this, &bare_fn.decl);
614 self.diagnostic_metadata.current_trait_object = prev;
619 visit::walk_ty(self, ty);
620 self.diagnostic_metadata.current_trait_object = prev;
621 self.diagnostic_metadata.current_type_path = prev_ty;
623 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef, _: &'ast TraitBoundModifier) {
625 if tref.bound_generic_params.is_empty() { tref.span.shrink_to_lo() } else { tref.span };
626 self.with_generic_param_rib(
627 &tref.bound_generic_params,
629 LifetimeRibKind::Generics {
630 parent: tref.trait_ref.ref_id,
631 kind: LifetimeBinderKind::PolyTrait,
635 this.visit_generic_param_vec(&tref.bound_generic_params, false);
636 this.smart_resolve_path(
637 tref.trait_ref.ref_id,
639 &tref.trait_ref.path,
640 PathSource::Trait(AliasPossibility::Maybe),
642 this.visit_trait_ref(&tref.trait_ref);
646 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
647 match foreign_item.kind {
648 ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
649 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
650 this.with_generic_param_rib(
652 ItemRibKind(HasGenericParams::Yes),
653 LifetimeRibKind::Generics {
654 parent: foreign_item.id,
655 kind: LifetimeBinderKind::Item,
658 |this| visit::walk_foreign_item(this, foreign_item),
662 ForeignItemKind::Fn(box Fn { ref generics, .. }) => {
663 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
664 this.with_generic_param_rib(
666 ItemRibKind(HasGenericParams::Yes),
667 LifetimeRibKind::Generics {
668 parent: foreign_item.id,
669 kind: LifetimeBinderKind::Function,
672 |this| visit::walk_foreign_item(this, foreign_item),
676 ForeignItemKind::Static(..) => {
677 self.with_item_rib(|this| {
678 visit::walk_foreign_item(this, foreign_item);
681 ForeignItemKind::MacCall(..) => {
682 panic!("unexpanded macro in resolve!")
686 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, fn_id: NodeId) {
687 let rib_kind = match fn_kind {
688 // Bail if the function is foreign, and thus cannot validly have
689 // a body, or if there's no body for some other reason.
690 FnKind::Fn(FnCtxt::Foreign, _, sig, _, generics, _)
691 | FnKind::Fn(_, _, sig, _, generics, None) => {
692 self.with_lifetime_rib(LifetimeRibKind::AnonymousPassThrough(fn_id), |this| {
693 // We don't need to deal with patterns in parameters, because
694 // they are not possible for foreign or bodiless functions.
695 this.visit_fn_header(&sig.header);
696 this.visit_generics(generics);
697 visit::walk_fn_decl(this, &sig.decl);
701 FnKind::Fn(FnCtxt::Free, ..) => FnItemRibKind,
702 FnKind::Fn(FnCtxt::Assoc(_), ..) => NormalRibKind,
703 FnKind::Closure(..) => ClosureOrAsyncRibKind,
705 let previous_value = self.diagnostic_metadata.current_function;
706 if matches!(fn_kind, FnKind::Fn(..)) {
707 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
709 debug!("(resolving function) entering function");
710 let declaration = fn_kind.decl();
712 // Create a value rib for the function.
713 self.with_rib(ValueNS, rib_kind, |this| {
714 // Create a label rib for the function.
715 this.with_label_rib(rib_kind, |this| {
716 let async_node_id = fn_kind.header().and_then(|h| h.asyncness.opt_return_id());
718 if let FnKind::Fn(_, _, _, _, generics, _) = fn_kind {
719 this.visit_generics(generics);
722 if let Some(async_node_id) = async_node_id {
723 // In `async fn`, argument-position elided lifetimes
724 // must be transformed into fresh generic parameters so that
725 // they can be applied to the opaque `impl Trait` return type.
726 this.with_lifetime_rib(
727 LifetimeRibKind::AnonymousCreateParameter(fn_id),
729 // Add each argument to the rib.
730 this.resolve_params(&declaration.inputs)
734 // Construct the list of in-scope lifetime parameters for async lowering.
735 // We include all lifetime parameters, either named or "Fresh".
736 // The order of those parameters does not matter, as long as it is
738 let mut extra_lifetime_params =
739 this.r.extra_lifetime_params_map.get(&fn_id).cloned().unwrap_or_default();
740 for rib in this.lifetime_ribs.iter().rev() {
741 extra_lifetime_params.extend(
744 .map(|(&ident, &(node_id, res))| (ident, node_id, res)),
747 LifetimeRibKind::Item => break,
748 LifetimeRibKind::AnonymousCreateParameter(id) => {
749 if let Some(earlier_fresh) =
750 this.r.extra_lifetime_params_map.get(&id)
752 extra_lifetime_params.extend(earlier_fresh);
758 this.r.extra_lifetime_params_map.insert(async_node_id, extra_lifetime_params);
760 this.with_lifetime_rib(
761 LifetimeRibKind::AnonymousPassThrough(async_node_id),
762 |this| visit::walk_fn_ret_ty(this, &declaration.output),
765 this.with_lifetime_rib(LifetimeRibKind::AnonymousPassThrough(fn_id), |this| {
766 // Add each argument to the rib.
767 this.resolve_params(&declaration.inputs);
769 visit::walk_fn_ret_ty(this, &declaration.output);
773 // Ignore errors in function bodies if this is rustdoc
774 // Be sure not to set this until the function signature has been resolved.
775 let previous_state = replace(&mut this.in_func_body, true);
776 // Resolve the function body, potentially inside the body of an async closure
777 this.with_lifetime_rib(LifetimeRibKind::AnonymousPassThrough(fn_id), |this| {
779 FnKind::Fn(.., body) => walk_list!(this, visit_block, body),
780 FnKind::Closure(_, body) => this.visit_expr(body),
784 debug!("(resolving function) leaving function");
785 this.in_func_body = previous_state;
788 self.diagnostic_metadata.current_function = previous_value;
790 fn visit_lifetime(&mut self, lifetime: &'ast Lifetime) {
791 self.resolve_lifetime(lifetime)
794 fn visit_generics(&mut self, generics: &'ast Generics) {
795 self.visit_generic_param_vec(
797 self.diagnostic_metadata.current_self_item.is_some(),
799 for p in &generics.where_clause.predicates {
800 self.visit_where_predicate(p);
804 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
805 debug!("visit_generic_arg({:?})", arg);
806 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
808 GenericArg::Type(ref ty) => {
809 // We parse const arguments as path types as we cannot distinguish them during
810 // parsing. We try to resolve that ambiguity by attempting resolution the type
811 // namespace first, and if that fails we try again in the value namespace. If
812 // resolution in the value namespace succeeds, we have an generic const argument on
814 if let TyKind::Path(ref qself, ref path) = ty.kind {
815 // We cannot disambiguate multi-segment paths right now as that requires type
817 if path.segments.len() == 1 && path.segments[0].args.is_none() {
818 let mut check_ns = |ns| {
819 self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns)
822 if !check_ns(TypeNS) && check_ns(ValueNS) {
823 // This must be equivalent to `visit_anon_const`, but we cannot call it
824 // directly due to visitor lifetimes so we have to copy-paste some code.
826 // Note that we might not be inside of an repeat expression here,
827 // but considering that `IsRepeatExpr` is only relevant for
828 // non-trivial constants this is doesn't matter.
829 self.with_constant_rib(IsRepeatExpr::No, true, None, |this| {
830 this.smart_resolve_path(
834 PathSource::Expr(None),
837 if let Some(ref qself) = *qself {
838 this.visit_ty(&qself.ty);
840 this.visit_path(path, ty.id);
843 self.diagnostic_metadata.currently_processing_generics = prev;
851 GenericArg::Lifetime(lt) => self.visit_lifetime(lt),
852 GenericArg::Const(ct) => self.visit_anon_const(ct),
854 self.diagnostic_metadata.currently_processing_generics = prev;
857 fn visit_path_segment(&mut self, path_span: Span, path_segment: &'ast PathSegment) {
858 if let Some(ref args) = path_segment.args {
860 GenericArgs::AngleBracketed(..) => visit::walk_generic_args(self, path_span, args),
861 GenericArgs::Parenthesized(..) => self.with_lifetime_rib(
862 LifetimeRibKind::AnonymousPassThrough(path_segment.id),
863 |this| visit::walk_generic_args(this, path_span, args),
869 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
870 debug!("visit_where_predicate {:?}", p);
872 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
873 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
874 if let WherePredicate::BoundPredicate(WhereBoundPredicate {
877 ref bound_generic_params,
878 span: predicate_span,
882 let span = if bound_generic_params.is_empty() {
883 predicate_span.shrink_to_lo()
887 this.with_generic_param_rib(
888 &bound_generic_params,
890 LifetimeRibKind::Generics {
891 parent: bounded_ty.id,
892 kind: LifetimeBinderKind::WhereBound,
896 this.visit_generic_param_vec(&bound_generic_params, false);
897 this.visit_ty(bounded_ty);
898 for bound in bounds {
899 this.visit_param_bound(bound, BoundKind::Bound)
904 visit::walk_where_predicate(this, p);
907 self.diagnostic_metadata.current_where_predicate = previous_value;
910 fn visit_inline_asm_sym(&mut self, sym: &'ast InlineAsmSym) {
911 // This is similar to the code for AnonConst.
912 self.with_rib(ValueNS, InlineAsmSymRibKind, |this| {
913 this.with_rib(TypeNS, InlineAsmSymRibKind, |this| {
914 this.with_label_rib(InlineAsmSymRibKind, |this| {
915 this.smart_resolve_path(
919 PathSource::Expr(None),
921 visit::walk_inline_asm_sym(this, sym);
928 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
929 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
930 // During late resolution we only track the module component of the parent scope,
931 // although it may be useful to track other components as well for diagnostics.
932 let graph_root = resolver.graph_root;
933 let parent_scope = ParentScope::module(graph_root, resolver);
934 let start_rib_kind = ModuleRibKind(graph_root);
935 LateResolutionVisitor {
939 value_ns: vec![Rib::new(start_rib_kind)],
940 type_ns: vec![Rib::new(start_rib_kind)],
941 macro_ns: vec![Rib::new(start_rib_kind)],
943 label_ribs: Vec::new(),
944 lifetime_ribs: Vec::new(),
945 current_trait_ref: None,
946 diagnostic_metadata: DiagnosticMetadata::default(),
947 // errors at module scope should always be reported
952 fn maybe_resolve_ident_in_lexical_scope(
956 ) -> Option<LexicalScopeBinding<'a>> {
957 self.r.resolve_ident_in_lexical_scope(
967 fn resolve_ident_in_lexical_scope(
971 finalize: Option<Finalize>,
972 ignore_binding: Option<&'a NameBinding<'a>>,
973 ) -> Option<LexicalScopeBinding<'a>> {
974 self.r.resolve_ident_in_lexical_scope(
987 opt_ns: Option<Namespace>, // `None` indicates a module path in import
988 finalize: Option<Finalize>,
989 ) -> PathResult<'a> {
990 self.r.resolve_path_with_ribs(
1002 // We maintain a list of value ribs and type ribs.
1004 // Simultaneously, we keep track of the current position in the module
1005 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
1006 // the value or type namespaces, we first look through all the ribs and
1007 // then query the module graph. When we resolve a name in the module
1008 // namespace, we can skip all the ribs (since nested modules are not
1009 // allowed within blocks in Rust) and jump straight to the current module
1012 // Named implementations are handled separately. When we find a method
1013 // call, we consult the module node to find all of the implementations in
1014 // scope. This information is lazily cached in the module node. We then
1015 // generate a fake "implementation scope" containing all the
1016 // implementations thus found, for compatibility with old resolve pass.
1018 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
1023 work: impl FnOnce(&mut Self) -> T,
1025 self.ribs[ns].push(Rib::new(kind));
1026 let ret = work(self);
1027 self.ribs[ns].pop();
1031 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
1032 if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
1033 // Move down in the graph.
1034 let orig_module = replace(&mut self.parent_scope.module, module);
1035 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
1036 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
1038 this.parent_scope.module = orig_module;
1047 fn visit_generic_param_vec(&mut self, params: &'ast Vec<GenericParam>, add_self_upper: bool) {
1048 // For type parameter defaults, we have to ban access
1049 // to following type parameters, as the InternalSubsts can only
1050 // provide previous type parameters as they're built. We
1051 // put all the parameters on the ban list and then remove
1052 // them one by one as they are processed and become available.
1053 let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1054 let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1055 for param in params.iter() {
1057 GenericParamKind::Type { .. } => {
1060 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1062 GenericParamKind::Const { .. } => {
1063 forward_const_ban_rib
1065 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1067 GenericParamKind::Lifetime => {}
1071 // rust-lang/rust#61631: The type `Self` is essentially
1072 // another type parameter. For ADTs, we consider it
1073 // well-defined only after all of the ADT type parameters have
1074 // been provided. Therefore, we do not allow use of `Self`
1075 // anywhere in ADT type parameter defaults.
1077 // (We however cannot ban `Self` for defaults on *all* generic
1078 // lists; e.g. trait generics can usefully refer to `Self`,
1079 // such as in the case of `trait Add<Rhs = Self>`.)
1081 // (`Some` if + only if we are in ADT's generics.)
1082 forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
1085 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1086 for param in params {
1088 GenericParamKind::Lifetime => {
1089 for bound in ¶m.bounds {
1090 this.visit_param_bound(bound, BoundKind::Bound);
1093 GenericParamKind::Type { ref default } => {
1094 for bound in ¶m.bounds {
1095 this.visit_param_bound(bound, BoundKind::Bound);
1098 if let Some(ref ty) = default {
1099 this.ribs[TypeNS].push(forward_ty_ban_rib);
1100 this.ribs[ValueNS].push(forward_const_ban_rib);
1102 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1103 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1106 // Allow all following defaults to refer to this type parameter.
1109 .remove(&Ident::with_dummy_span(param.ident.name));
1111 GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
1112 // Const parameters can't have param bounds.
1113 assert!(param.bounds.is_empty());
1115 this.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
1116 this.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
1117 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1120 this.ribs[TypeNS].pop().unwrap();
1121 this.ribs[ValueNS].pop().unwrap();
1123 if let Some(ref expr) = default {
1124 this.ribs[TypeNS].push(forward_ty_ban_rib);
1125 this.ribs[ValueNS].push(forward_const_ban_rib);
1126 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1127 this.resolve_anon_const(expr, IsRepeatExpr::No)
1129 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1130 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1133 // Allow all following defaults to refer to this const parameter.
1134 forward_const_ban_rib
1136 .remove(&Ident::with_dummy_span(param.ident.name));
1143 #[tracing::instrument(level = "debug", skip(self, work))]
1144 fn with_lifetime_rib<T>(
1146 kind: LifetimeRibKind,
1147 work: impl FnOnce(&mut Self) -> T,
1149 self.lifetime_ribs.push(LifetimeRib::new(kind));
1150 let ret = work(self);
1151 self.lifetime_ribs.pop();
1155 #[tracing::instrument(level = "debug", skip(self))]
1156 fn resolve_lifetime(&mut self, lifetime: &'ast Lifetime) {
1157 let ident = lifetime.ident;
1159 if ident.name == kw::StaticLifetime {
1160 self.record_lifetime_res(lifetime.id, LifetimeRes::Static);
1164 if ident.name == kw::UnderscoreLifetime {
1165 return self.resolve_anonymous_lifetime(lifetime, false);
1168 let mut indices = (0..self.lifetime_ribs.len()).rev();
1169 for i in &mut indices {
1170 let rib = &self.lifetime_ribs[i];
1171 let normalized_ident = ident.normalize_to_macros_2_0();
1172 if let Some(&(_, region)) = rib.bindings.get(&normalized_ident) {
1173 self.record_lifetime_res(lifetime.id, region);
1178 LifetimeRibKind::Item => break,
1179 LifetimeRibKind::ConstGeneric => {
1180 self.emit_non_static_lt_in_const_generic_error(lifetime);
1181 self.r.lifetimes_res_map.insert(lifetime.id, LifetimeRes::Error);
1184 LifetimeRibKind::AnonConst => {
1185 self.maybe_emit_forbidden_non_static_lifetime_error(lifetime);
1186 self.r.lifetimes_res_map.insert(lifetime.id, LifetimeRes::Error);
1193 let mut outer_res = None;
1195 let rib = &self.lifetime_ribs[i];
1196 let normalized_ident = ident.normalize_to_macros_2_0();
1197 if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) {
1198 outer_res = Some(outer);
1203 self.emit_undeclared_lifetime_error(lifetime, outer_res);
1204 self.record_lifetime_res(lifetime.id, LifetimeRes::Error);
1207 #[tracing::instrument(level = "debug", skip(self))]
1208 fn resolve_anonymous_lifetime(&mut self, lifetime: &Lifetime, elided: bool) {
1209 debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
1211 for i in (0..self.lifetime_ribs.len()).rev() {
1212 let rib = &mut self.lifetime_ribs[i];
1214 LifetimeRibKind::AnonymousCreateParameter(item_node_id) => {
1215 self.create_fresh_lifetime(lifetime.id, lifetime.ident, item_node_id);
1218 LifetimeRibKind::AnonymousReportError => {
1219 let (msg, note) = if elided {
1221 "`&` without an explicit lifetime name cannot be used here",
1222 "explicit lifetime name needed here",
1225 ("`'_` cannot be used here", "`'_` is a reserved lifetime name")
1227 rustc_errors::struct_span_err!(
1229 lifetime.ident.span,
1234 .span_label(lifetime.ident.span, note)
1237 self.record_lifetime_res(lifetime.id, LifetimeRes::Error);
1240 LifetimeRibKind::AnonymousPassThrough(node_id) => {
1241 self.record_lifetime_res(
1243 LifetimeRes::Anonymous { binder: node_id, elided },
1247 LifetimeRibKind::Item => break,
1251 // This resolution is wrong, it passes the work to HIR lifetime resolution.
1252 // We cannot use `LifetimeRes::Error` because we do not emit a diagnostic.
1253 self.record_lifetime_res(
1255 LifetimeRes::Anonymous { binder: DUMMY_NODE_ID, elided },
1259 #[tracing::instrument(level = "debug", skip(self))]
1260 fn resolve_elided_lifetime(&mut self, anchor_id: NodeId, span: Span) {
1261 let id = self.r.next_node_id();
1262 self.record_lifetime_res(
1264 LifetimeRes::ElidedAnchor { start: id, end: NodeId::from_u32(id.as_u32() + 1) },
1267 let lt = Lifetime { id, ident: Ident::new(kw::UnderscoreLifetime, span) };
1268 self.resolve_anonymous_lifetime(<, true);
1271 #[tracing::instrument(level = "debug", skip(self))]
1272 fn create_fresh_lifetime(&mut self, id: NodeId, ident: Ident, item_node_id: NodeId) {
1273 debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
1274 debug!(?ident.span);
1275 let item_def_id = self.r.local_def_id(item_node_id);
1276 let def_node_id = self.r.next_node_id();
1277 let def_id = self.r.create_def(
1280 DefPathData::LifetimeNs(kw::UnderscoreLifetime),
1281 self.parent_scope.expansion.to_expn_id(),
1286 let region = LifetimeRes::Fresh { param: def_id, binder: item_node_id };
1287 self.record_lifetime_res(id, region);
1288 self.r.extra_lifetime_params_map.entry(item_node_id).or_insert_with(Vec::new).push((
1295 #[tracing::instrument(level = "debug", skip(self))]
1296 fn resolve_elided_lifetimes_in_path(
1299 partial_res: PartialRes,
1301 source: PathSource<'_>,
1304 let proj_start = path.len() - partial_res.unresolved_segments();
1305 for (i, segment) in path.iter().enumerate() {
1306 if segment.has_lifetime_args {
1309 let Some(segment_id) = segment.id else {
1313 // Figure out if this is a type/trait segment,
1314 // which may need lifetime elision performed.
1315 let type_def_id = match partial_res.base_res() {
1316 Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => self.r.parent(def_id),
1317 Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => self.r.parent(def_id),
1318 Res::Def(DefKind::Struct, def_id)
1319 | Res::Def(DefKind::Union, def_id)
1320 | Res::Def(DefKind::Enum, def_id)
1321 | Res::Def(DefKind::TyAlias, def_id)
1322 | Res::Def(DefKind::Trait, def_id)
1323 if i + 1 == proj_start =>
1330 let expected_lifetimes = self.r.item_generics_num_lifetimes(type_def_id);
1331 if expected_lifetimes == 0 {
1335 let missing = match source {
1336 PathSource::Trait(..) | PathSource::TraitItem(..) | PathSource::Type => true,
1337 PathSource::Expr(..)
1339 | PathSource::Struct
1340 | PathSource::TupleStruct(..) => false,
1342 let mut res = LifetimeRes::Error;
1343 for rib in self.lifetime_ribs.iter().rev() {
1345 // In create-parameter mode we error here because we don't want to support
1346 // deprecated impl elision in new features like impl elision and `async fn`,
1347 // both of which work using the `CreateParameter` mode:
1349 // impl Foo for std::cell::Ref<u32> // note lack of '_
1350 // async fn foo(_: std::cell::Ref<u32>) { ... }
1351 LifetimeRibKind::AnonymousCreateParameter(_) => {
1354 // `PassThrough` is the normal case.
1355 // `new_error_lifetime`, which would usually be used in the case of `ReportError`,
1356 // is unsuitable here, as these can occur from missing lifetime parameters in a
1357 // `PathSegment`, for which there is no associated `'_` or `&T` with no explicit
1358 // lifetime. Instead, we simply create an implicit lifetime, which will be checked
1359 // later, at which point a suitable error will be emitted.
1360 LifetimeRibKind::AnonymousPassThrough(binder) => {
1361 res = LifetimeRes::Anonymous { binder, elided: true };
1364 LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
1365 // FIXME(cjgillot) This resolution is wrong, but this does not matter
1366 // since these cases are erroneous anyway. Lifetime resolution should
1367 // emit a "missing lifetime specifier" diagnostic.
1368 res = LifetimeRes::Anonymous { binder: DUMMY_NODE_ID, elided: true };
1375 let node_ids = self.r.next_node_ids(expected_lifetimes);
1376 self.record_lifetime_res(
1378 LifetimeRes::ElidedAnchor { start: node_ids.start, end: node_ids.end },
1380 for i in 0..expected_lifetimes {
1381 let id = node_ids.start.plus(i);
1382 self.record_lifetime_res(id, res);
1389 let elided_lifetime_span = if segment.has_generic_args {
1390 // If there are brackets, but not generic arguments, then use the opening bracket
1391 segment.args_span.with_hi(segment.args_span.lo() + BytePos(1))
1393 // If there are no brackets, use the identifier span.
1394 // HACK: we use find_ancestor_inside to properly suggest elided spans in paths
1395 // originating from macros, since the segment's span might be from a macro arg.
1396 segment.ident.span.find_ancestor_inside(path_span).unwrap_or(path_span)
1398 if let LifetimeRes::Error = res {
1399 let sess = self.r.session;
1400 let mut err = rustc_errors::struct_span_err!(
1404 "implicit elided lifetime not allowed here"
1406 rustc_errors::add_elided_lifetime_in_path_suggestion(
1411 !segment.has_generic_args,
1412 elided_lifetime_span,
1414 err.note("assuming a `'static` lifetime...");
1417 self.r.lint_buffer.buffer_lint_with_diagnostic(
1418 lint::builtin::ELIDED_LIFETIMES_IN_PATHS,
1420 elided_lifetime_span,
1421 "hidden lifetime parameters in types are deprecated",
1422 lint::BuiltinLintDiagnostics::ElidedLifetimesInPaths(
1425 !segment.has_generic_args,
1426 elided_lifetime_span,
1433 #[tracing::instrument(level = "debug", skip(self))]
1434 fn record_lifetime_res(&mut self, id: NodeId, res: LifetimeRes) {
1435 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1437 "lifetime {:?} resolved multiple times ({:?} before, {:?} now)",
1443 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
1444 /// label and reports an error if the label is not found or is unreachable.
1445 fn resolve_label(&mut self, mut label: Ident) -> Option<NodeId> {
1446 let mut suggestion = None;
1448 // Preserve the original span so that errors contain "in this macro invocation"
1450 let original_span = label.span;
1452 for i in (0..self.label_ribs.len()).rev() {
1453 let rib = &self.label_ribs[i];
1455 if let MacroDefinition(def) = rib.kind {
1456 // If an invocation of this macro created `ident`, give up on `ident`
1457 // and switch to `ident`'s source from the macro definition.
1458 if def == self.r.macro_def(label.span.ctxt()) {
1459 label.span.remove_mark();
1463 let ident = label.normalize_to_macro_rules();
1464 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
1465 let definition_span = ident.span;
1466 return if self.is_label_valid_from_rib(i) {
1471 ResolutionError::UnreachableLabel {
1482 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
1483 // the first such label that is encountered.
1484 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
1489 ResolutionError::UndeclaredLabel { name: label.name, suggestion },
1494 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
1495 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
1496 let ribs = &self.label_ribs[rib_index + 1..];
1500 NormalRibKind | MacroDefinition(..) => {
1501 // Nothing to do. Continue.
1505 | ClosureOrAsyncRibKind
1508 | ConstantItemRibKind(..)
1510 | ForwardGenericParamBanRibKind
1511 | ConstParamTyRibKind
1512 | InlineAsmSymRibKind => {
1521 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
1522 debug!("resolve_adt");
1523 self.with_current_self_item(item, |this| {
1524 this.with_generic_param_rib(
1526 ItemRibKind(HasGenericParams::Yes),
1527 LifetimeRibKind::Generics {
1529 kind: LifetimeBinderKind::Item,
1530 span: generics.span,
1533 let item_def_id = this.r.local_def_id(item.id).to_def_id();
1535 Res::SelfTy { trait_: None, alias_to: Some((item_def_id, false)) },
1537 visit::walk_item(this, item);
1545 fn future_proof_import(&mut self, use_tree: &UseTree) {
1546 let segments = &use_tree.prefix.segments;
1547 if !segments.is_empty() {
1548 let ident = segments[0].ident;
1549 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
1553 let nss = match use_tree.kind {
1554 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
1557 let report_error = |this: &Self, ns| {
1558 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
1559 if this.should_report_errs() {
1562 .span_err(ident.span, &format!("imports cannot refer to {}", what));
1567 match self.maybe_resolve_ident_in_lexical_scope(ident, ns) {
1568 Some(LexicalScopeBinding::Res(..)) => {
1569 report_error(self, ns);
1571 Some(LexicalScopeBinding::Item(binding)) => {
1572 if let Some(LexicalScopeBinding::Res(..)) =
1573 self.resolve_ident_in_lexical_scope(ident, ns, None, Some(binding))
1575 report_error(self, ns);
1581 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
1582 for (use_tree, _) in use_trees {
1583 self.future_proof_import(use_tree);
1588 fn resolve_item(&mut self, item: &'ast Item) {
1589 let name = item.ident.name;
1590 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
1593 ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
1594 self.with_generic_param_rib(
1596 ItemRibKind(HasGenericParams::Yes),
1597 LifetimeRibKind::Generics {
1599 kind: LifetimeBinderKind::Item,
1600 span: generics.span,
1602 |this| visit::walk_item(this, item),
1606 ItemKind::Fn(box Fn { ref generics, .. }) => {
1607 self.with_generic_param_rib(
1609 ItemRibKind(HasGenericParams::Yes),
1610 LifetimeRibKind::Generics {
1612 kind: LifetimeBinderKind::Function,
1613 span: generics.span,
1615 |this| visit::walk_item(this, item),
1619 ItemKind::Enum(_, ref generics)
1620 | ItemKind::Struct(_, ref generics)
1621 | ItemKind::Union(_, ref generics) => {
1622 self.resolve_adt(item, generics);
1625 ItemKind::Impl(box Impl {
1629 items: ref impl_items,
1632 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
1635 ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
1636 // Create a new rib for the trait-wide type parameters.
1637 self.with_generic_param_rib(
1639 ItemRibKind(HasGenericParams::Yes),
1640 LifetimeRibKind::Generics {
1642 kind: LifetimeBinderKind::Item,
1643 span: generics.span,
1646 let local_def_id = this.r.local_def_id(item.id).to_def_id();
1648 Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
1650 this.visit_generics(generics);
1651 walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);
1653 let walk_assoc_item =
1655 generics: &Generics,
1657 item: &'ast AssocItem| {
1658 this.with_generic_param_rib(
1661 LifetimeRibKind::Generics {
1663 span: generics.span,
1667 visit::walk_assoc_item(this, item, AssocCtxt::Trait)
1672 this.with_trait_items(items, |this| {
1675 AssocItemKind::Const(_, ty, default) => {
1677 // Only impose the restrictions of `ConstRibKind` for an
1678 // actual constant expression in a provided default.
1679 if let Some(expr) = default {
1680 // We allow arbitrary const expressions inside of associated consts,
1681 // even if they are potentially not const evaluatable.
1683 // Type parameters can already be used and as associated consts are
1684 // not used as part of the type system, this is far less surprising.
1685 this.with_constant_rib(
1689 |this| this.visit_expr(expr),
1693 AssocItemKind::Fn(box Fn { generics, .. }) => {
1697 LifetimeBinderKind::Function,
1701 AssocItemKind::TyAlias(box TyAlias {
1708 LifetimeBinderKind::Item,
1712 AssocItemKind::MacCall(_) => {
1713 panic!("unexpanded macro in resolve!")
1724 ItemKind::TraitAlias(ref generics, ref bounds) => {
1725 // Create a new rib for the trait-wide type parameters.
1726 self.with_generic_param_rib(
1728 ItemRibKind(HasGenericParams::Yes),
1729 LifetimeRibKind::Generics {
1731 kind: LifetimeBinderKind::Item,
1732 span: generics.span,
1735 let local_def_id = this.r.local_def_id(item.id).to_def_id();
1737 Res::SelfTy { trait_: Some(local_def_id), alias_to: None },
1739 this.visit_generics(generics);
1740 walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
1747 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
1748 self.with_scope(item.id, |this| {
1749 visit::walk_item(this, item);
1753 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
1754 self.with_item_rib(|this| {
1756 if let Some(expr) = expr {
1757 let constant_item_kind = match item.kind {
1758 ItemKind::Const(..) => ConstantItemKind::Const,
1759 ItemKind::Static(..) => ConstantItemKind::Static,
1760 _ => unreachable!(),
1762 // We already forbid generic params because of the above item rib,
1763 // so it doesn't matter whether this is a trivial constant.
1764 this.with_constant_rib(
1767 Some((item.ident, constant_item_kind)),
1768 |this| this.visit_expr(expr),
1774 ItemKind::Use(ref use_tree) => {
1775 self.future_proof_import(use_tree);
1778 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => {
1779 // do nothing, these are just around to be encoded
1782 ItemKind::GlobalAsm(_) => {
1783 visit::walk_item(self, item);
1786 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
1790 fn with_generic_param_rib<'c, F>(
1792 params: &'c Vec<GenericParam>,
1794 lifetime_kind: LifetimeRibKind,
1797 F: FnOnce(&mut Self),
1799 debug!("with_generic_param_rib");
1800 let mut function_type_rib = Rib::new(kind);
1801 let mut function_value_rib = Rib::new(kind);
1802 let mut function_lifetime_rib = LifetimeRib::new(lifetime_kind);
1803 let mut seen_bindings = FxHashMap::default();
1805 // We also can't shadow bindings from the parent item
1806 if let AssocItemRibKind = kind {
1807 let mut add_bindings_for_ns = |ns| {
1808 let parent_rib = self.ribs[ns]
1810 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
1811 .expect("associated item outside of an item");
1813 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
1815 add_bindings_for_ns(ValueNS);
1816 add_bindings_for_ns(TypeNS);
1819 for param in params {
1820 let ident = param.ident.normalize_to_macros_2_0();
1821 debug!("with_generic_param_rib: {}", param.id);
1823 match seen_bindings.entry(ident) {
1824 Entry::Occupied(entry) => {
1825 let span = *entry.get();
1826 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
1827 if !matches!(param.kind, GenericParamKind::Lifetime) {
1828 self.report_error(param.ident.span, err);
1831 Entry::Vacant(entry) => {
1832 entry.insert(param.ident.span);
1836 if param.ident.name == kw::UnderscoreLifetime {
1837 rustc_errors::struct_span_err!(
1841 "`'_` cannot be used here"
1843 .span_label(param.ident.span, "`'_` is a reserved lifetime name")
1848 if param.ident.name == kw::StaticLifetime {
1849 rustc_errors::struct_span_err!(
1853 "invalid lifetime parameter name: `{}`",
1856 .span_label(param.ident.span, "'static is a reserved lifetime name")
1861 let def_id = self.r.local_def_id(param.id);
1863 // Plain insert (no renaming).
1864 let (rib, def_kind) = match param.kind {
1865 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
1866 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
1867 GenericParamKind::Lifetime => {
1868 let LifetimeRibKind::Generics { parent, .. } = lifetime_kind else { panic!() };
1869 let res = LifetimeRes::Param { param: def_id, binder: parent };
1870 self.record_lifetime_res(param.id, res);
1871 function_lifetime_rib.bindings.insert(ident, (param.id, res));
1875 let res = Res::Def(def_kind, def_id.to_def_id());
1876 self.r.record_partial_res(param.id, PartialRes::new(res));
1877 rib.bindings.insert(ident, res);
1880 self.lifetime_ribs.push(function_lifetime_rib);
1881 self.ribs[ValueNS].push(function_value_rib);
1882 self.ribs[TypeNS].push(function_type_rib);
1886 self.ribs[TypeNS].pop();
1887 self.ribs[ValueNS].pop();
1888 self.lifetime_ribs.pop();
1891 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
1892 self.label_ribs.push(Rib::new(kind));
1894 self.label_ribs.pop();
1897 fn with_item_rib(&mut self, f: impl FnOnce(&mut Self)) {
1898 let kind = ItemRibKind(HasGenericParams::No);
1899 self.with_lifetime_rib(LifetimeRibKind::Item, |this| {
1900 this.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
1904 // HACK(min_const_generics,const_evaluatable_unchecked): We
1905 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
1906 // with a future compat lint for now. We do this by adding an
1907 // additional special case for repeat expressions.
1909 // Note that we intentionally still forbid `[0; N + 1]` during
1910 // name resolution so that we don't extend the future
1911 // compat lint to new cases.
1912 fn with_constant_rib(
1914 is_repeat: IsRepeatExpr,
1916 item: Option<(Ident, ConstantItemKind)>,
1917 f: impl FnOnce(&mut Self),
1919 debug!("with_constant_rib: is_repeat={:?} is_trivial={}", is_repeat, is_trivial);
1920 self.with_rib(ValueNS, ConstantItemRibKind(is_trivial, item), |this| {
1923 ConstantItemRibKind(is_repeat == IsRepeatExpr::Yes || is_trivial, item),
1925 this.with_label_rib(ConstantItemRibKind(is_trivial, item), f);
1931 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
1932 // Handle nested impls (inside fn bodies)
1933 let previous_value =
1934 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
1935 let result = f(self);
1936 self.diagnostic_metadata.current_self_type = previous_value;
1940 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
1941 let previous_value =
1942 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
1943 let result = f(self);
1944 self.diagnostic_metadata.current_self_item = previous_value;
1948 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
1949 fn with_trait_items<T>(
1951 trait_items: &'ast [P<AssocItem>],
1952 f: impl FnOnce(&mut Self) -> T,
1954 let trait_assoc_items =
1955 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
1956 let result = f(self);
1957 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
1961 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
1962 fn with_optional_trait_ref<T>(
1964 opt_trait_ref: Option<&TraitRef>,
1965 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
1967 let mut new_val = None;
1968 let mut new_id = None;
1969 if let Some(trait_ref) = opt_trait_ref {
1970 let path: Vec<_> = Segment::from_path(&trait_ref.path);
1971 let res = self.smart_resolve_path_fragment(
1974 PathSource::Trait(AliasPossibility::No),
1975 Finalize::new(trait_ref.ref_id, trait_ref.path.span),
1977 if let Some(def_id) = res.base_res().opt_def_id() {
1978 new_id = Some(def_id);
1979 new_val = Some((self.r.expect_module(def_id), trait_ref.clone()));
1982 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1983 let result = f(self, new_id);
1984 self.current_trait_ref = original_trait_ref;
1988 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
1989 let mut self_type_rib = Rib::new(NormalRibKind);
1991 // Plain insert (no renaming, since types are not currently hygienic)
1992 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
1993 self.ribs[ns].push(self_type_rib);
1995 self.ribs[ns].pop();
1998 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
1999 self.with_self_rib_ns(TypeNS, self_res, f)
2002 fn resolve_implementation(
2004 generics: &'ast Generics,
2005 opt_trait_reference: &'ast Option<TraitRef>,
2006 self_type: &'ast Ty,
2008 impl_items: &'ast [P<AssocItem>],
2010 debug!("resolve_implementation");
2011 // If applicable, create a rib for the type parameters.
2012 self.with_generic_param_rib(&generics.params, ItemRibKind(HasGenericParams::Yes), LifetimeRibKind::Generics { span: generics.span, parent: item_id, kind: LifetimeBinderKind::ImplBlock }, |this| {
2013 // Dummy self type for better errors if `Self` is used in the trait path.
2014 this.with_self_rib(Res::SelfTy { trait_: None, alias_to: None }, |this| {
2015 this.with_lifetime_rib(LifetimeRibKind::AnonymousCreateParameter(item_id), |this| {
2016 // Resolve the trait reference, if necessary.
2017 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
2018 let item_def_id = this.r.local_def_id(item_id);
2020 // Register the trait definitions from here.
2021 if let Some(trait_id) = trait_id {
2022 this.r.trait_impls.entry(trait_id).or_default().push(item_def_id);
2025 let item_def_id = item_def_id.to_def_id();
2027 Res::SelfTy { trait_: trait_id, alias_to: Some((item_def_id, false)) };
2028 this.with_self_rib(res, |this| {
2029 if let Some(trait_ref) = opt_trait_reference.as_ref() {
2030 // Resolve type arguments in the trait path.
2031 visit::walk_trait_ref(this, trait_ref);
2033 // Resolve the self type.
2034 this.visit_ty(self_type);
2035 // Resolve the generic parameters.
2036 this.visit_generics(generics);
2038 // Resolve the items within the impl.
2039 this.with_lifetime_rib(LifetimeRibKind::AnonymousPassThrough(item_id),
2041 this.with_current_self_type(self_type, |this| {
2042 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
2043 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
2044 for item in impl_items {
2045 use crate::ResolutionError::*;
2047 AssocItemKind::Const(_default, _ty, _expr) => {
2048 debug!("resolve_implementation AssocItemKind::Const");
2049 // If this is a trait impl, ensure the const
2051 this.check_trait_item(
2057 |i, s, c| ConstNotMemberOfTrait(i, s, c),
2060 // We allow arbitrary const expressions inside of associated consts,
2061 // even if they are potentially not const evaluatable.
2063 // Type parameters can already be used and as associated consts are
2064 // not used as part of the type system, this is far less surprising.
2065 this.with_constant_rib(
2070 visit::walk_assoc_item(
2078 AssocItemKind::Fn(box Fn { generics, .. }) => {
2079 debug!("resolve_implementation AssocItemKind::Fn");
2080 // We also need a new scope for the impl item type parameters.
2081 this.with_generic_param_rib(
2084 LifetimeRibKind::Generics { parent: item.id, span: generics.span, kind: LifetimeBinderKind::Function },
2086 // If this is a trait impl, ensure the method
2088 this.check_trait_item(
2094 |i, s, c| MethodNotMemberOfTrait(i, s, c),
2097 visit::walk_assoc_item(
2105 AssocItemKind::TyAlias(box TyAlias {
2108 debug!("resolve_implementation AssocItemKind::TyAlias");
2109 // We also need a new scope for the impl item type parameters.
2110 this.with_generic_param_rib(
2113 LifetimeRibKind::Generics { parent: item.id, span: generics.span, kind: LifetimeBinderKind::Item },
2115 // If this is a trait impl, ensure the type
2117 this.check_trait_item(
2123 |i, s, c| TypeNotMemberOfTrait(i, s, c),
2126 visit::walk_assoc_item(
2134 AssocItemKind::MacCall(_) => {
2135 panic!("unexpanded macro in resolve!")
2150 fn check_trait_item<F>(
2154 kind: &AssocItemKind,
2159 F: FnOnce(Ident, String, Option<Symbol>) -> ResolutionError<'a>,
2161 // If there is a TraitRef in scope for an impl, then the method must be in the trait.
2162 let Some((module, _)) = &self.current_trait_ref else { return; };
2163 ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
2164 let key = self.r.new_key(ident, ns);
2165 let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2167 if binding.is_none() {
2168 // We could not find the trait item in the correct namespace.
2169 // Check the other namespace to report an error.
2175 let key = self.r.new_key(ident, ns);
2176 binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2179 let Some(binding) = binding else {
2180 // We could not find the method: report an error.
2181 let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
2182 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2183 let path_names = path_names_to_string(path);
2184 self.report_error(span, err(ident, path_names, candidate));
2188 let res = binding.res();
2189 let Res::Def(def_kind, _) = res else { bug!() };
2190 match (def_kind, kind) {
2191 (DefKind::AssocTy, AssocItemKind::TyAlias(..))
2192 | (DefKind::AssocFn, AssocItemKind::Fn(..))
2193 | (DefKind::AssocConst, AssocItemKind::Const(..)) => {
2194 self.r.record_partial_res(id, PartialRes::new(res));
2200 // The method kind does not correspond to what appeared in the trait, report.
2201 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2202 let (code, kind) = match kind {
2203 AssocItemKind::Const(..) => (rustc_errors::error_code!(E0323), "const"),
2204 AssocItemKind::Fn(..) => (rustc_errors::error_code!(E0324), "method"),
2205 AssocItemKind::TyAlias(..) => (rustc_errors::error_code!(E0325), "type"),
2206 AssocItemKind::MacCall(..) => span_bug!(span, "unexpanded macro"),
2208 let trait_path = path_names_to_string(path);
2211 ResolutionError::TraitImplMismatch {
2216 trait_item_span: binding.span,
2221 fn resolve_params(&mut self, params: &'ast [Param]) {
2222 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2223 for Param { pat, ty, .. } in params {
2224 self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
2226 debug!("(resolving function / closure) recorded parameter");
2230 fn resolve_local(&mut self, local: &'ast Local) {
2231 debug!("resolving local ({:?})", local);
2232 // Resolve the type.
2233 walk_list!(self, visit_ty, &local.ty);
2235 // Resolve the initializer.
2236 if let Some((init, els)) = local.kind.init_else_opt() {
2237 self.visit_expr(init);
2239 // Resolve the `else` block
2240 if let Some(els) = els {
2241 self.visit_block(els);
2245 // Resolve the pattern.
2246 self.resolve_pattern_top(&local.pat, PatternSource::Let);
2249 /// build a map from pattern identifiers to binding-info's.
2250 /// this is done hygienically. This could arise for a macro
2251 /// that expands into an or-pattern where one 'x' was from the
2252 /// user and one 'x' came from the macro.
2253 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2254 let mut binding_map = FxHashMap::default();
2256 pat.walk(&mut |pat| {
2258 PatKind::Ident(binding_mode, ident, ref sub_pat)
2259 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
2261 binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode });
2263 PatKind::Or(ref ps) => {
2264 // Check the consistency of this or-pattern and
2265 // then add all bindings to the larger map.
2266 for bm in self.check_consistent_bindings(ps) {
2267 binding_map.extend(bm);
2280 fn is_base_res_local(&self, nid: NodeId) -> bool {
2281 matches!(self.r.partial_res_map.get(&nid).map(|res| res.base_res()), Some(Res::Local(..)))
2284 /// Checks that all of the arms in an or-pattern have exactly the
2285 /// same set of bindings, with the same binding modes for each.
2286 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
2287 let mut missing_vars = FxHashMap::default();
2288 let mut inconsistent_vars = FxHashMap::default();
2290 // 1) Compute the binding maps of all arms.
2291 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
2293 // 2) Record any missing bindings or binding mode inconsistencies.
2294 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
2295 // Check against all arms except for the same pattern which is always self-consistent.
2299 .filter(|(_, pat)| pat.id != pat_outer.id)
2300 .flat_map(|(idx, _)| maps[idx].iter())
2301 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
2303 for (name, info, &binding_inner) in inners {
2306 // The inner binding is missing in the outer.
2308 missing_vars.entry(name).or_insert_with(|| BindingError {
2310 origin: BTreeSet::new(),
2311 target: BTreeSet::new(),
2312 could_be_path: name.as_str().starts_with(char::is_uppercase),
2314 binding_error.origin.insert(binding_inner.span);
2315 binding_error.target.insert(pat_outer.span);
2317 Some(binding_outer) => {
2318 if binding_outer.binding_mode != binding_inner.binding_mode {
2319 // The binding modes in the outer and inner bindings differ.
2322 .or_insert((binding_inner.span, binding_outer.span));
2329 // 3) Report all missing variables we found.
2330 let mut missing_vars = missing_vars.into_iter().collect::<Vec<_>>();
2331 missing_vars.sort_by_key(|&(sym, ref _err)| sym);
2333 for (name, mut v) in missing_vars.into_iter() {
2334 if inconsistent_vars.contains_key(&name) {
2335 v.could_be_path = false;
2338 *v.origin.iter().next().unwrap(),
2339 ResolutionError::VariableNotBoundInPattern(v, self.parent_scope),
2343 // 4) Report all inconsistencies in binding modes we found.
2344 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
2345 inconsistent_vars.sort();
2346 for (name, v) in inconsistent_vars {
2347 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
2350 // 5) Finally bubble up all the binding maps.
2354 /// Check the consistency of the outermost or-patterns.
2355 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
2356 pat.walk(&mut |pat| match pat.kind {
2357 PatKind::Or(ref ps) => {
2358 self.check_consistent_bindings(ps);
2365 fn resolve_arm(&mut self, arm: &'ast Arm) {
2366 self.with_rib(ValueNS, NormalRibKind, |this| {
2367 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
2368 walk_list!(this, visit_expr, &arm.guard);
2369 this.visit_expr(&arm.body);
2373 /// Arising from `source`, resolve a top level pattern.
2374 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
2375 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2376 self.resolve_pattern(pat, pat_src, &mut bindings);
2382 pat_src: PatternSource,
2383 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
2385 // We walk the pattern before declaring the pattern's inner bindings,
2386 // so that we avoid resolving a literal expression to a binding defined
2388 visit::walk_pat(self, pat);
2389 self.resolve_pattern_inner(pat, pat_src, bindings);
2390 // This has to happen *after* we determine which pat_idents are variants:
2391 self.check_consistent_bindings_top(pat);
2394 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
2398 /// A stack of sets of bindings accumulated.
2400 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
2401 /// be interpreted as re-binding an already bound binding. This results in an error.
2402 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
2403 /// in reusing this binding rather than creating a fresh one.
2405 /// When called at the top level, the stack must have a single element
2406 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
2407 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
2408 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
2409 /// When each `p_i` has been dealt with, the top set is merged with its parent.
2410 /// When a whole or-pattern has been dealt with, the thing happens.
2412 /// See the implementation and `fresh_binding` for more details.
2413 fn resolve_pattern_inner(
2416 pat_src: PatternSource,
2417 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
2419 // Visit all direct subpatterns of this pattern.
2420 pat.walk(&mut |pat| {
2421 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
2423 PatKind::Ident(bmode, ident, ref sub) => {
2424 // First try to resolve the identifier as some existing entity,
2425 // then fall back to a fresh binding.
2426 let has_sub = sub.is_some();
2428 .try_resolve_as_non_binding(pat_src, bmode, ident, has_sub)
2429 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
2430 self.r.record_partial_res(pat.id, PartialRes::new(res));
2431 self.r.record_pat_span(pat.id, pat.span);
2433 PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
2434 self.smart_resolve_path(
2438 PathSource::TupleStruct(
2440 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
2444 PatKind::Path(ref qself, ref path) => {
2445 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
2447 PatKind::Struct(ref qself, ref path, ..) => {
2448 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Struct);
2450 PatKind::Or(ref ps) => {
2451 // Add a new set of bindings to the stack. `Or` here records that when a
2452 // binding already exists in this set, it should not result in an error because
2453 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
2454 bindings.push((PatBoundCtx::Or, Default::default()));
2456 // Now we need to switch back to a product context so that each
2457 // part of the or-pattern internally rejects already bound names.
2458 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
2459 bindings.push((PatBoundCtx::Product, Default::default()));
2460 self.resolve_pattern_inner(p, pat_src, bindings);
2461 // Move up the non-overlapping bindings to the or-pattern.
2462 // Existing bindings just get "merged".
2463 let collected = bindings.pop().unwrap().1;
2464 bindings.last_mut().unwrap().1.extend(collected);
2466 // This or-pattern itself can itself be part of a product,
2467 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
2468 // Both cases bind `a` again in a product pattern and must be rejected.
2469 let collected = bindings.pop().unwrap().1;
2470 bindings.last_mut().unwrap().1.extend(collected);
2472 // Prevent visiting `ps` as we've already done so above.
2485 pat_src: PatternSource,
2486 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
2488 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
2489 // (We must not add it if it's in the bindings map because that breaks the assumptions
2490 // later passes make about or-patterns.)
2491 let ident = ident.normalize_to_macro_rules();
2493 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
2494 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
2495 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
2496 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
2497 // This is *required* for consistency which is checked later.
2498 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
2500 if already_bound_and {
2501 // Overlap in a product pattern somewhere; report an error.
2502 use ResolutionError::*;
2503 let error = match pat_src {
2504 // `fn f(a: u8, a: u8)`:
2505 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
2507 _ => IdentifierBoundMoreThanOnceInSamePattern,
2509 self.report_error(ident.span, error(ident.name));
2512 // Record as bound if it's valid:
2513 let ident_valid = ident.name != kw::Empty;
2515 bindings.last_mut().unwrap().1.insert(ident);
2518 if already_bound_or {
2519 // `Variant1(a) | Variant2(a)`, ok
2520 // Reuse definition from the first `a`.
2521 self.innermost_rib_bindings(ValueNS)[&ident]
2523 let res = Res::Local(pat_id);
2525 // A completely fresh binding add to the set if it's valid.
2526 self.innermost_rib_bindings(ValueNS).insert(ident, res);
2532 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
2533 &mut self.ribs[ns].last_mut().unwrap().bindings
2536 fn try_resolve_as_non_binding(
2538 pat_src: PatternSource,
2543 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
2544 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
2545 // also be interpreted as a path to e.g. a constant, variant, etc.
2546 let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not);
2548 let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?;
2549 let (res, binding) = match ls_binding {
2550 LexicalScopeBinding::Item(binding)
2551 if is_syntactic_ambiguity && binding.is_ambiguity() =>
2553 // For ambiguous bindings we don't know all their definitions and cannot check
2554 // whether they can be shadowed by fresh bindings or not, so force an error.
2555 // issues/33118#issuecomment-233962221 (see below) still applies here,
2556 // but we have to ignore it for backward compatibility.
2557 self.r.record_use(ident, binding, false);
2560 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
2561 LexicalScopeBinding::Res(res) => (res, None),
2565 Res::SelfCtor(_) // See #70549.
2567 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
2569 ) if is_syntactic_ambiguity => {
2570 // Disambiguate in favor of a unit struct/variant or constant pattern.
2571 if let Some(binding) = binding {
2572 self.r.record_use(ident, binding, false);
2576 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static(_), _) => {
2577 // This is unambiguously a fresh binding, either syntactically
2578 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
2579 // to something unusable as a pattern (e.g., constructor function),
2580 // but we still conservatively report an error, see
2581 // issues/33118#issuecomment-233962221 for one reason why.
2582 let binding = binding.expect("no binding for a ctor or static");
2585 ResolutionError::BindingShadowsSomethingUnacceptable {
2586 shadowing_binding_descr: pat_src.descr(),
2588 participle: if binding.is_import() { "imported" } else { "defined" },
2589 article: binding.res().article(),
2590 shadowed_binding_descr: binding.res().descr(),
2591 shadowed_binding_span: binding.span,
2596 Res::Def(DefKind::ConstParam, def_id) => {
2597 // Same as for DefKind::Const above, but here, `binding` is `None`, so we
2598 // have to construct the error differently
2601 ResolutionError::BindingShadowsSomethingUnacceptable {
2602 shadowing_binding_descr: pat_src.descr(),
2604 participle: "defined",
2605 article: res.article(),
2606 shadowed_binding_descr: res.descr(),
2607 shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"),
2612 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
2613 // These entities are explicitly allowed to be shadowed by fresh bindings.
2616 Res::SelfCtor(_) => {
2617 // We resolve `Self` in pattern position as an ident sometimes during recovery,
2618 // so delay a bug instead of ICEing.
2619 self.r.session.delay_span_bug(
2621 "unexpected `SelfCtor` in pattern, expected identifier"
2627 "unexpected resolution for an identifier in pattern: {:?}",
2633 // High-level and context dependent path resolution routine.
2634 // Resolves the path and records the resolution into definition map.
2635 // If resolution fails tries several techniques to find likely
2636 // resolution candidates, suggest imports or other help, and report
2637 // errors in user friendly way.
2638 fn smart_resolve_path(
2641 qself: Option<&QSelf>,
2643 source: PathSource<'ast>,
2645 self.smart_resolve_path_fragment(
2647 &Segment::from_path(path),
2649 Finalize::new(id, path.span),
2653 fn smart_resolve_path_fragment(
2655 qself: Option<&QSelf>,
2657 source: PathSource<'ast>,
2661 "smart_resolve_path_fragment(qself={:?}, path={:?}, finalize={:?})",
2666 let ns = source.namespace();
2668 let Finalize { node_id, path_span, .. } = finalize;
2669 let report_errors = |this: &mut Self, res: Option<Res>| {
2670 if this.should_report_errs() {
2671 let (err, candidates) =
2672 this.smart_resolve_report_errors(path, path_span, source, res);
2674 let def_id = this.parent_scope.module.nearest_parent_mod();
2675 let instead = res.is_some();
2677 if res.is_none() { this.report_missing_type_error(path) } else { None };
2679 this.r.use_injections.push(UseError {
2688 PartialRes::new(Res::Err)
2691 // For paths originating from calls (like in `HashMap::new()`), tries
2692 // to enrich the plain `failed to resolve: ...` message with hints
2693 // about possible missing imports.
2695 // Similar thing, for types, happens in `report_errors` above.
2696 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
2697 if !source.is_call() {
2698 return Some(parent_err);
2701 // Before we start looking for candidates, we have to get our hands
2702 // on the type user is trying to perform invocation on; basically:
2703 // we're transforming `HashMap::new` into just `HashMap`.
2704 let path = match path.split_last() {
2705 Some((_, path)) if !path.is_empty() => path,
2706 _ => return Some(parent_err),
2709 let (mut err, candidates) =
2710 this.smart_resolve_report_errors(path, path_span, PathSource::Type, None);
2712 if candidates.is_empty() {
2714 return Some(parent_err);
2717 // There are two different error messages user might receive at
2719 // - E0412 cannot find type `{}` in this scope
2720 // - E0433 failed to resolve: use of undeclared type or module `{}`
2722 // The first one is emitted for paths in type-position, and the
2723 // latter one - for paths in expression-position.
2725 // Thus (since we're in expression-position at this point), not to
2726 // confuse the user, we want to keep the *message* from E0432 (so
2727 // `parent_err`), but we want *hints* from E0412 (so `err`).
2729 // And that's what happens below - we're just mixing both messages
2730 // into a single one.
2731 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
2733 err.message = take(&mut parent_err.message);
2734 err.code = take(&mut parent_err.code);
2735 err.children = take(&mut parent_err.children);
2737 parent_err.cancel();
2739 let def_id = this.parent_scope.module.nearest_parent_mod();
2741 if this.should_report_errs() {
2742 this.r.use_injections.push(UseError {
2753 // We don't return `Some(parent_err)` here, because the error will
2754 // be already printed as part of the `use` injections
2758 let partial_res = match self.resolve_qpath_anywhere(
2763 source.defer_to_typeck(),
2766 Ok(Some(partial_res)) if partial_res.unresolved_segments() == 0 => {
2767 if source.is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err
2771 report_errors(self, Some(partial_res.base_res()))
2775 Ok(Some(partial_res)) if source.defer_to_typeck() => {
2776 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
2777 // or `<T>::A::B`. If `B` should be resolved in value namespace then
2778 // it needs to be added to the trait map.
2780 let item_name = path.last().unwrap().ident;
2781 let traits = self.traits_in_scope(item_name, ns);
2782 self.r.trait_map.insert(node_id, traits);
2785 if PrimTy::from_name(path[0].ident.name).is_some() {
2786 let mut std_path = Vec::with_capacity(1 + path.len());
2788 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
2789 std_path.extend(path);
2790 if let PathResult::Module(_) | PathResult::NonModule(_) =
2791 self.resolve_path(&std_path, Some(ns), None)
2793 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
2795 path.iter().last().map_or(path_span, |segment| segment.ident.span);
2797 self.r.confused_type_with_std_module.insert(item_span, path_span);
2798 self.r.confused_type_with_std_module.insert(path_span, path_span);
2806 if let Some(err) = report_errors_for_call(self, err) {
2807 self.report_error(err.span, err.node);
2810 PartialRes::new(Res::Err)
2813 _ => report_errors(self, None),
2816 if !matches!(source, PathSource::TraitItem(..)) {
2817 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
2818 self.r.record_partial_res(node_id, partial_res);
2819 self.resolve_elided_lifetimes_in_path(node_id, partial_res, path, source, path_span);
2825 fn self_type_is_available(&mut self) -> bool {
2827 .maybe_resolve_ident_in_lexical_scope(Ident::with_dummy_span(kw::SelfUpper), TypeNS);
2828 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
2831 fn self_value_is_available(&mut self, self_span: Span) -> bool {
2832 let ident = Ident::new(kw::SelfLower, self_span);
2833 let binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS);
2834 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
2837 /// A wrapper around [`Resolver::report_error`].
2839 /// This doesn't emit errors for function bodies if this is rustdoc.
2840 fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) {
2841 if self.should_report_errs() {
2842 self.r.report_error(span, resolution_error);
2847 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
2848 fn should_report_errs(&self) -> bool {
2849 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
2852 // Resolve in alternative namespaces if resolution in the primary namespace fails.
2853 fn resolve_qpath_anywhere(
2855 qself: Option<&QSelf>,
2857 primary_ns: Namespace,
2859 defer_to_typeck: bool,
2861 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2862 let mut fin_res = None;
2864 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
2865 if i == 0 || ns != primary_ns {
2866 match self.resolve_qpath(qself, path, ns, finalize)? {
2868 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
2870 return Ok(Some(partial_res));
2873 if fin_res.is_none() {
2874 fin_res = partial_res;
2881 assert!(primary_ns != MacroNS);
2883 if qself.is_none() {
2884 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
2885 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
2886 if let Ok((_, res)) =
2887 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
2889 return Ok(Some(PartialRes::new(res)));
2896 /// Handles paths that may refer to associated items.
2899 qself: Option<&QSelf>,
2903 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
2905 "resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})",
2906 qself, path, ns, finalize,
2909 if let Some(qself) = qself {
2910 if qself.position == 0 {
2911 // This is a case like `<T>::B`, where there is no
2912 // trait to resolve. In that case, we leave the `B`
2913 // segment to be resolved by type-check.
2914 return Ok(Some(PartialRes::with_unresolved_segments(
2915 Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()),
2920 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
2922 // Currently, `path` names the full item (`A::B::C`, in
2923 // our example). so we extract the prefix of that that is
2924 // the trait (the slice upto and including
2925 // `qself.position`). And then we recursively resolve that,
2926 // but with `qself` set to `None`.
2927 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2928 let partial_res = self.smart_resolve_path_fragment(
2930 &path[..=qself.position],
2931 PathSource::TraitItem(ns),
2932 Finalize::with_root_span(finalize.node_id, finalize.path_span, qself.path_span),
2935 // The remaining segments (the `C` in our example) will
2936 // have to be resolved by type-check, since that requires doing
2937 // trait resolution.
2938 return Ok(Some(PartialRes::with_unresolved_segments(
2939 partial_res.base_res(),
2940 partial_res.unresolved_segments() + path.len() - qself.position - 1,
2944 let result = match self.resolve_path(&path, Some(ns), Some(finalize)) {
2945 PathResult::NonModule(path_res) => path_res,
2946 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
2947 PartialRes::new(module.res().unwrap())
2949 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2950 // don't report an error right away, but try to fallback to a primitive type.
2951 // So, we are still able to successfully resolve something like
2953 // use std::u8; // bring module u8 in scope
2954 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2955 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
2956 // // not to non-existent std::u8::max_value
2959 // Such behavior is required for backward compatibility.
2960 // The same fallback is used when `a` resolves to nothing.
2961 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
2962 if (ns == TypeNS || path.len() > 1)
2963 && PrimTy::from_name(path[0].ident.name).is_some() =>
2965 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
2966 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
2968 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2969 PartialRes::new(module.res().unwrap())
2971 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
2972 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
2974 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
2975 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
2979 && result.base_res() != Res::Err
2980 && path[0].ident.name != kw::PathRoot
2981 && path[0].ident.name != kw::DollarCrate
2983 let unqualified_result = {
2984 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
2985 PathResult::NonModule(path_res) => path_res.base_res(),
2986 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
2987 module.res().unwrap()
2989 _ => return Ok(Some(result)),
2992 if result.base_res() == unqualified_result {
2993 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
2994 self.r.lint_buffer.buffer_lint(
2998 "unnecessary qualification",
3006 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
3007 if let Some(label) = label {
3008 if label.ident.as_str().as_bytes()[1] != b'_' {
3009 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
3011 self.with_label_rib(NormalRibKind, |this| {
3012 let ident = label.ident.normalize_to_macro_rules();
3013 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
3021 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
3022 self.with_resolved_label(label, id, |this| this.visit_block(block));
3025 fn resolve_block(&mut self, block: &'ast Block) {
3026 debug!("(resolving block) entering block");
3027 // Move down in the graph, if there's an anonymous module rooted here.
3028 let orig_module = self.parent_scope.module;
3029 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
3031 let mut num_macro_definition_ribs = 0;
3032 if let Some(anonymous_module) = anonymous_module {
3033 debug!("(resolving block) found anonymous module, moving down");
3034 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3035 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3036 self.parent_scope.module = anonymous_module;
3038 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3041 let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
3042 if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
3043 (block.could_be_bare_literal, &block.stmts[..])
3044 && let ExprKind::Type(..) = expr.kind
3046 self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
3049 // Descend into the block.
3050 for stmt in &block.stmts {
3051 if let StmtKind::Item(ref item) = stmt.kind
3052 && let ItemKind::MacroDef(..) = item.kind {
3053 num_macro_definition_ribs += 1;
3054 let res = self.r.local_def_id(item.id).to_def_id();
3055 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
3056 self.label_ribs.push(Rib::new(MacroDefinition(res)));
3059 self.visit_stmt(stmt);
3061 self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
3064 self.parent_scope.module = orig_module;
3065 for _ in 0..num_macro_definition_ribs {
3066 self.ribs[ValueNS].pop();
3067 self.label_ribs.pop();
3069 self.ribs[ValueNS].pop();
3070 if anonymous_module.is_some() {
3071 self.ribs[TypeNS].pop();
3073 debug!("(resolving block) leaving block");
3076 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
3077 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
3078 self.with_constant_rib(
3080 constant.value.is_potential_trivial_const_param(),
3082 |this| visit::walk_anon_const(this, constant),
3086 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
3087 // First, record candidate traits for this expression if it could
3088 // result in the invocation of a method call.
3090 self.record_candidate_traits_for_expr_if_necessary(expr);
3092 // Next, resolve the node.
3094 ExprKind::Path(ref qself, ref path) => {
3095 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
3096 visit::walk_expr(self, expr);
3099 ExprKind::Struct(ref se) => {
3100 self.smart_resolve_path(expr.id, se.qself.as_ref(), &se.path, PathSource::Struct);
3101 visit::walk_expr(self, expr);
3104 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
3105 if let Some(node_id) = self.resolve_label(label.ident) {
3106 // Since this res is a label, it is never read.
3107 self.r.label_res_map.insert(expr.id, node_id);
3108 self.diagnostic_metadata.unused_labels.remove(&node_id);
3111 // visit `break` argument if any
3112 visit::walk_expr(self, expr);
3115 ExprKind::Break(None, Some(ref e)) => {
3116 // We use this instead of `visit::walk_expr` to keep the parent expr around for
3117 // better diagnostics.
3118 self.resolve_expr(e, Some(&expr));
3121 ExprKind::Let(ref pat, ref scrutinee, _) => {
3122 self.visit_expr(scrutinee);
3123 self.resolve_pattern_top(pat, PatternSource::Let);
3126 ExprKind::If(ref cond, ref then, ref opt_else) => {
3127 self.with_rib(ValueNS, NormalRibKind, |this| {
3128 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3129 this.visit_expr(cond);
3130 this.diagnostic_metadata.in_if_condition = old;
3131 this.visit_block(then);
3133 if let Some(expr) = opt_else {
3134 self.visit_expr(expr);
3138 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3140 ExprKind::While(ref cond, ref block, label) => {
3141 self.with_resolved_label(label, expr.id, |this| {
3142 this.with_rib(ValueNS, NormalRibKind, |this| {
3143 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3144 this.visit_expr(cond);
3145 this.diagnostic_metadata.in_if_condition = old;
3146 this.visit_block(block);
3151 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
3152 self.visit_expr(iter_expr);
3153 self.with_rib(ValueNS, NormalRibKind, |this| {
3154 this.resolve_pattern_top(pat, PatternSource::For);
3155 this.resolve_labeled_block(label, expr.id, block);
3159 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
3161 // Equivalent to `visit::walk_expr` + passing some context to children.
3162 ExprKind::Field(ref subexpression, _) => {
3163 self.resolve_expr(subexpression, Some(expr));
3165 ExprKind::MethodCall(ref segment, ref arguments, _) => {
3166 let mut arguments = arguments.iter();
3167 self.resolve_expr(arguments.next().unwrap(), Some(expr));
3168 for argument in arguments {
3169 self.resolve_expr(argument, None);
3171 self.visit_path_segment(expr.span, segment);
3174 ExprKind::Call(ref callee, ref arguments) => {
3175 self.resolve_expr(callee, Some(expr));
3176 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
3177 for (idx, argument) in arguments.iter().enumerate() {
3178 // Constant arguments need to be treated as AnonConst since
3179 // that is how they will be later lowered to HIR.
3180 if const_args.contains(&idx) {
3181 self.with_constant_rib(
3183 argument.is_potential_trivial_const_param(),
3186 this.resolve_expr(argument, None);
3190 self.resolve_expr(argument, None);
3194 ExprKind::Type(ref type_expr, ref ty) => {
3195 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
3196 // type ascription. Here we are trying to retrieve the span of the colon token as
3197 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
3198 // with `expr::Ty`, only in this case it will match the span from
3199 // `type_ascription_path_suggestions`.
3200 self.diagnostic_metadata
3201 .current_type_ascription
3202 .push(type_expr.span.between(ty.span));
3203 visit::walk_expr(self, expr);
3204 self.diagnostic_metadata.current_type_ascription.pop();
3206 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
3207 // resolve the arguments within the proper scopes so that usages of them inside the
3208 // closure are detected as upvars rather than normal closure arg usages.
3209 ExprKind::Closure(_, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
3210 self.with_rib(ValueNS, NormalRibKind, |this| {
3211 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
3212 // Resolve arguments:
3213 this.resolve_params(&fn_decl.inputs);
3214 // No need to resolve return type --
3215 // the outer closure return type is `FnRetTy::Default`.
3217 // Now resolve the inner closure
3219 // No need to resolve arguments: the inner closure has none.
3220 // Resolve the return type:
3221 visit::walk_fn_ret_ty(this, &fn_decl.output);
3223 this.visit_expr(body);
3228 ExprKind::Async(..) | ExprKind::Closure(..) => {
3229 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
3231 ExprKind::Repeat(ref elem, ref ct) => {
3232 self.visit_expr(elem);
3233 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
3234 this.resolve_anon_const(ct, IsRepeatExpr::Yes)
3237 ExprKind::ConstBlock(ref ct) => {
3238 self.resolve_anon_const(ct, IsRepeatExpr::No);
3240 ExprKind::Index(ref elem, ref idx) => {
3241 self.resolve_expr(elem, Some(expr));
3242 self.visit_expr(idx);
3245 visit::walk_expr(self, expr);
3250 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
3252 ExprKind::Field(_, ident) => {
3253 // FIXME(#6890): Even though you can't treat a method like a
3254 // field, we need to add any trait methods we find that match
3255 // the field name so that we can do some nice error reporting
3256 // later on in typeck.
3257 let traits = self.traits_in_scope(ident, ValueNS);
3258 self.r.trait_map.insert(expr.id, traits);
3260 ExprKind::MethodCall(ref segment, ..) => {
3261 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
3262 let traits = self.traits_in_scope(segment.ident, ValueNS);
3263 self.r.trait_map.insert(expr.id, traits);
3271 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
3272 self.r.traits_in_scope(
3273 self.current_trait_ref.as_ref().map(|(module, _)| *module),
3276 Some((ident.name, ns)),
3281 struct LifetimeCountVisitor<'a, 'b> {
3282 r: &'b mut Resolver<'a>,
3285 /// Walks the whole crate in DFS order, visiting each item, counting the declared number of
3286 /// lifetime generic parameters.
3287 impl<'ast> Visitor<'ast> for LifetimeCountVisitor<'_, '_> {
3288 fn visit_item(&mut self, item: &'ast Item) {
3290 ItemKind::TyAlias(box TyAlias { ref generics, .. })
3291 | ItemKind::Fn(box Fn { ref generics, .. })
3292 | ItemKind::Enum(_, ref generics)
3293 | ItemKind::Struct(_, ref generics)
3294 | ItemKind::Union(_, ref generics)
3295 | ItemKind::Impl(box Impl { ref generics, .. })
3296 | ItemKind::Trait(box Trait { ref generics, .. })
3297 | ItemKind::TraitAlias(ref generics, _) => {
3298 let def_id = self.r.local_def_id(item.id);
3299 let count = generics
3302 .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
3304 self.r.item_generics_num_lifetimes.insert(def_id, count);
3308 | ItemKind::ForeignMod(..)
3309 | ItemKind::Static(..)
3310 | ItemKind::Const(..)
3312 | ItemKind::ExternCrate(..)
3313 | ItemKind::MacroDef(..)
3314 | ItemKind::GlobalAsm(..)
3315 | ItemKind::MacCall(..) => {}
3317 visit::walk_item(self, item)
3321 impl<'a> Resolver<'a> {
3322 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
3323 visit::walk_crate(&mut LifetimeCountVisitor { r: self }, krate);
3324 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
3325 visit::walk_crate(&mut late_resolution_visitor, krate);
3326 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
3327 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");