1 // ignore-tidy-filelength
2 //! "Late resolution" is the pass that resolves most of names in a crate beside imports and macros.
3 //! It runs when the crate is fully expanded and its module structure is fully built.
4 //! So it just walks through the crate and resolves all the expressions, types, etc.
6 //! If you wonder why there's no `early.rs`, that's because it's split into three files -
7 //! `build_reduced_graph.rs`, `macros.rs` and `imports.rs`.
11 use crate::{path_names_to_string, BindingError, Finalize, LexicalScopeBinding};
12 use crate::{Module, ModuleOrUniformRoot, NameBinding, ParentScope, PathResult};
13 use crate::{ResolutionError, Resolver, Segment, UseError};
15 use rustc_ast::ptr::P;
16 use rustc_ast::visit::{self, AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor};
18 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
19 use rustc_errors::DiagnosticId;
20 use rustc_hir::def::Namespace::{self, *};
21 use rustc_hir::def::{self, CtorKind, DefKind, LifetimeRes, PartialRes, PerNS};
22 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
23 use rustc_hir::{BindingAnnotation, PrimTy, TraitCandidate};
24 use rustc_middle::middle::resolve_lifetime::Set1;
25 use rustc_middle::ty::DefIdTree;
26 use rustc_middle::{bug, span_bug};
27 use rustc_session::lint;
28 use rustc_span::symbol::{kw, sym, Ident, Symbol};
29 use rustc_span::{BytePos, Span};
30 use smallvec::{smallvec, SmallVec};
32 use rustc_span::source_map::{respan, Spanned};
33 use std::collections::{hash_map::Entry, BTreeSet};
34 use std::mem::{replace, take};
38 type Res = def::Res<NodeId>;
40 type IdentMap<T> = FxHashMap<Ident, T>;
42 /// Map from the name in a pattern to its binding mode.
43 type BindingMap = IdentMap<BindingInfo>;
46 ElisionFnParameter, LifetimeElisionCandidate, MissingLifetime, MissingLifetimeKind,
49 #[derive(Copy, Clone, Debug)]
52 annotation: BindingAnnotation,
55 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
56 pub enum PatternSource {
63 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
70 pub fn descr(self) -> &'static str {
72 PatternSource::Match => "match binding",
73 PatternSource::Let => "let binding",
74 PatternSource::For => "for binding",
75 PatternSource::FnParam => "function parameter",
80 /// Denotes whether the context for the set of already bound bindings is a `Product`
81 /// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`.
82 /// See those functions for more information.
85 /// A product pattern context, e.g., `Variant(a, b)`.
87 /// An or-pattern context, e.g., `p_0 | ... | p_n`.
91 /// Does this the item (from the item rib scope) allow generic parameters?
92 #[derive(Copy, Clone, Debug)]
93 pub(crate) enum HasGenericParams {
98 /// May this constant have generics?
99 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
100 pub(crate) enum ConstantHasGenerics {
105 impl ConstantHasGenerics {
106 fn force_yes_if(self, b: bool) -> Self {
107 if b { Self::Yes } else { self }
111 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
112 pub(crate) enum ConstantItemKind {
117 /// The rib kind restricts certain accesses,
118 /// e.g. to a `Res::Local` of an outer item.
119 #[derive(Copy, Clone, Debug)]
120 pub(crate) enum RibKind<'a> {
121 /// No restriction needs to be applied.
124 /// We passed through an impl or trait and are now in one of its
125 /// methods or associated types. Allow references to ty params that impl or trait
126 /// binds. Disallow any other upvars (including other ty params that are
130 /// We passed through a closure. Disallow labels.
131 ClosureOrAsyncRibKind,
133 /// We passed through an item scope. Disallow upvars.
134 ItemRibKind(HasGenericParams),
136 /// We're in a constant item. Can't refer to dynamic stuff.
138 /// The item may reference generic parameters in trivial constant expressions.
139 /// All other constants aren't allowed to use generic params at all.
140 ConstantItemRibKind(ConstantHasGenerics, Option<(Ident, ConstantItemKind)>),
142 /// We passed through a module.
143 ModuleRibKind(Module<'a>),
145 /// We passed through a `macro_rules!` statement
146 MacroDefinition(DefId),
148 /// All bindings in this rib are generic parameters that can't be used
149 /// from the default of a generic parameter because they're not declared
150 /// before said generic parameter. Also see the `visit_generics` override.
151 ForwardGenericParamBanRibKind,
153 /// We are inside of the type of a const parameter. Can't refer to any
157 /// We are inside a `sym` inline assembly operand. Can only refer to
163 /// Whether this rib kind contains generic parameters, as opposed to local
165 pub(crate) fn contains_params(&self) -> bool {
168 | ClosureOrAsyncRibKind
169 | ConstantItemRibKind(..)
172 | ConstParamTyRibKind
173 | InlineAsmSymRibKind => false,
174 AssocItemRibKind | ItemRibKind(_) | ForwardGenericParamBanRibKind => true,
178 /// This rib forbids referring to labels defined in upwards ribs.
179 fn is_label_barrier(self) -> bool {
181 NormalRibKind | MacroDefinition(..) => false,
184 | ClosureOrAsyncRibKind
186 | ConstantItemRibKind(..)
188 | ForwardGenericParamBanRibKind
189 | ConstParamTyRibKind
190 | InlineAsmSymRibKind => true,
195 /// A single local scope.
197 /// A rib represents a scope names can live in. Note that these appear in many places, not just
198 /// around braces. At any place where the list of accessible names (of the given namespace)
199 /// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a
200 /// stack. This may be, for example, a `let` statement (because it introduces variables), a macro,
203 /// Different [rib kinds](enum@RibKind) are transparent for different names.
205 /// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When
206 /// resolving, the name is looked up from inside out.
208 pub(crate) struct Rib<'a, R = Res> {
209 pub bindings: IdentMap<R>,
210 pub kind: RibKind<'a>,
213 impl<'a, R> Rib<'a, R> {
214 fn new(kind: RibKind<'a>) -> Rib<'a, R> {
215 Rib { bindings: Default::default(), kind }
219 #[derive(Clone, Copy, Debug)]
220 enum LifetimeUseSet {
221 One { use_span: Span, use_ctxt: visit::LifetimeCtxt },
225 #[derive(Copy, Clone, Debug)]
226 enum LifetimeRibKind {
227 // -- Ribs introducing named lifetimes
229 /// This rib declares generic parameters.
230 /// Only for this kind the `LifetimeRib::bindings` field can be non-empty.
231 Generics { binder: NodeId, span: Span, kind: LifetimeBinderKind },
233 // -- Ribs introducing unnamed lifetimes
235 /// Create a new anonymous lifetime parameter and reference it.
237 /// If `report_in_path`, report an error when encountering lifetime elision in a path:
239 /// struct Foo<'a> { x: &'a () }
240 /// async fn foo(x: Foo) {}
243 /// Note: the error should not trigger when the elided lifetime is in a pattern or
244 /// expression-position path:
246 /// struct Foo<'a> { x: &'a () }
247 /// async fn foo(Foo { x: _ }: Foo<'_>) {}
249 AnonymousCreateParameter { binder: NodeId, report_in_path: bool },
251 /// Replace all anonymous lifetimes by provided lifetime.
254 // -- Barrier ribs that stop lifetime lookup, or continue it but produce an error later.
256 /// Give a hard error when either `&` or `'_` is written. Used to
257 /// rule out things like `where T: Foo<'_>`. Does not imply an
258 /// error on default object bounds (e.g., `Box<dyn Foo>`).
259 AnonymousReportError,
261 /// Signal we cannot find which should be the anonymous lifetime.
264 /// FIXME(const_generics): This patches over an ICE caused by non-'static lifetimes in const
265 /// generics. We are disallowing this until we can decide on how we want to handle non-'static
266 /// lifetimes in const generics. See issue #74052 for discussion.
269 /// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`.
270 /// This function will emit an error if `generic_const_exprs` is not enabled, the body
271 /// identified by `body_id` is an anonymous constant and `lifetime_ref` is non-static.
274 /// This rib acts as a barrier to forbid reference to lifetimes of a parent item.
278 #[derive(Copy, Clone, Debug)]
279 enum LifetimeBinderKind {
289 impl LifetimeBinderKind {
290 fn descr(self) -> &'static str {
291 use LifetimeBinderKind::*;
293 BareFnType => "type",
294 PolyTrait => "bound",
295 WhereBound => "bound",
297 ImplBlock => "impl block",
298 Function => "function",
299 Closure => "closure",
306 kind: LifetimeRibKind,
307 // We need to preserve insertion order for async fns.
308 bindings: FxIndexMap<Ident, (NodeId, LifetimeRes)>,
312 fn new(kind: LifetimeRibKind) -> LifetimeRib {
313 LifetimeRib { bindings: Default::default(), kind }
317 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
318 pub(crate) enum AliasPossibility {
323 #[derive(Copy, Clone, Debug)]
324 pub(crate) enum PathSource<'a> {
325 // Type paths `Path`.
327 // Trait paths in bounds or impls.
328 Trait(AliasPossibility),
329 // Expression paths `path`, with optional parent context.
330 Expr(Option<&'a Expr>),
331 // Paths in path patterns `Path`.
333 // Paths in struct expressions and patterns `Path { .. }`.
335 // Paths in tuple struct patterns `Path(..)`.
336 TupleStruct(Span, &'a [Span]),
337 // `m::A::B` in `<T as m::A>::B::C`.
338 TraitItem(Namespace),
341 impl<'a> PathSource<'a> {
342 fn namespace(self) -> Namespace {
344 PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS,
345 PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS,
346 PathSource::TraitItem(ns) => ns,
350 fn defer_to_typeck(self) -> bool {
353 | PathSource::Expr(..)
356 | PathSource::TupleStruct(..) => true,
357 PathSource::Trait(_) | PathSource::TraitItem(..) => false,
361 fn descr_expected(self) -> &'static str {
363 PathSource::Type => "type",
364 PathSource::Trait(_) => "trait",
365 PathSource::Pat => "unit struct, unit variant or constant",
366 PathSource::Struct => "struct, variant or union type",
367 PathSource::TupleStruct(..) => "tuple struct or tuple variant",
368 PathSource::TraitItem(ns) => match ns {
369 TypeNS => "associated type",
370 ValueNS => "method or associated constant",
371 MacroNS => bug!("associated macro"),
373 PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) {
374 // "function" here means "anything callable" rather than `DefKind::Fn`,
375 // this is not precise but usually more helpful than just "value".
376 Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind {
377 // the case of `::some_crate()`
378 ExprKind::Path(_, path)
379 if path.segments.len() == 2
380 && path.segments[0].ident.name == kw::PathRoot =>
384 ExprKind::Path(_, path) => {
385 let mut msg = "function";
386 if let Some(segment) = path.segments.iter().last() {
387 if let Some(c) = segment.ident.to_string().chars().next() {
388 if c.is_uppercase() {
389 msg = "function, tuple struct or tuple variant";
402 fn is_call(self) -> bool {
403 matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
406 pub(crate) fn is_expected(self, res: Res) -> bool {
408 PathSource::Type => matches!(
415 | DefKind::TraitAlias
420 | DefKind::ForeignTy,
423 | Res::SelfTyParam { .. }
424 | Res::SelfTyAlias { .. }
426 PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
427 PathSource::Trait(AliasPossibility::Maybe) => {
428 matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
430 PathSource::Expr(..) => matches!(
433 DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
438 | DefKind::AssocConst
439 | DefKind::ConstParam,
445 res.expected_in_unit_struct_pat()
446 || matches!(res, Res::Def(DefKind::Const | DefKind::AssocConst, _))
448 PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(),
449 PathSource::Struct => matches!(
458 ) | Res::SelfTyParam { .. }
459 | Res::SelfTyAlias { .. }
461 PathSource::TraitItem(ns) => match res {
462 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
463 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
469 fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId {
470 use rustc_errors::error_code;
471 match (self, has_unexpected_resolution) {
472 (PathSource::Trait(_), true) => error_code!(E0404),
473 (PathSource::Trait(_), false) => error_code!(E0405),
474 (PathSource::Type, true) => error_code!(E0573),
475 (PathSource::Type, false) => error_code!(E0412),
476 (PathSource::Struct, true) => error_code!(E0574),
477 (PathSource::Struct, false) => error_code!(E0422),
478 (PathSource::Expr(..), true) => error_code!(E0423),
479 (PathSource::Expr(..), false) => error_code!(E0425),
480 (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532),
481 (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531),
482 (PathSource::TraitItem(..), true) => error_code!(E0575),
483 (PathSource::TraitItem(..), false) => error_code!(E0576),
489 struct DiagnosticMetadata<'ast> {
490 /// The current trait's associated items' ident, used for diagnostic suggestions.
491 current_trait_assoc_items: Option<&'ast [P<AssocItem>]>,
493 /// The current self type if inside an impl (used for better errors).
494 current_self_type: Option<Ty>,
496 /// The current self item if inside an ADT (used for better errors).
497 current_self_item: Option<NodeId>,
499 /// The current trait (used to suggest).
500 current_item: Option<&'ast Item>,
502 /// When processing generics and encountering a type not found, suggest introducing a type
504 currently_processing_generics: bool,
506 /// The current enclosing (non-closure) function (used for better errors).
507 current_function: Option<(FnKind<'ast>, Span)>,
509 /// A list of labels as of yet unused. Labels will be removed from this map when
510 /// they are used (in a `break` or `continue` statement)
511 unused_labels: FxHashMap<NodeId, Span>,
513 /// Only used for better errors on `fn(): fn()`.
514 current_type_ascription: Vec<Span>,
516 /// Only used for better errors on `let x = { foo: bar };`.
517 /// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only
518 /// needed for cases where this parses as a correct type ascription.
519 current_block_could_be_bare_struct_literal: Option<Span>,
521 /// Only used for better errors on `let <pat>: <expr, not type>;`.
522 current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
524 /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
525 in_if_condition: Option<&'ast Expr>,
527 /// If we are currently in a trait object definition. Used to point at the bounds when
528 /// encountering a struct or enum.
529 current_trait_object: Option<&'ast [ast::GenericBound]>,
531 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
532 current_where_predicate: Option<&'ast WherePredicate>,
534 current_type_path: Option<&'ast Ty>,
536 /// The current impl items (used to suggest).
537 current_impl_items: Option<&'ast [P<AssocItem>]>,
539 /// When processing impl trait
540 currently_processing_impl_trait: Option<(TraitRef, Ty)>,
542 /// Accumulate the errors due to missed lifetime elision,
543 /// and report them all at once for each function.
544 current_elision_failures: Vec<MissingLifetime>,
547 struct LateResolutionVisitor<'a, 'b, 'ast> {
548 r: &'b mut Resolver<'a>,
550 /// The module that represents the current item scope.
551 parent_scope: ParentScope<'a>,
553 /// The current set of local scopes for types and values.
554 /// FIXME #4948: Reuse ribs to avoid allocation.
555 ribs: PerNS<Vec<Rib<'a>>>,
557 /// The current set of local scopes, for labels.
558 label_ribs: Vec<Rib<'a, NodeId>>,
560 /// The current set of local scopes for lifetimes.
561 lifetime_ribs: Vec<LifetimeRib>,
563 /// We are looking for lifetimes in an elision context.
564 /// The set contains all the resolutions that we encountered so far.
565 /// They will be used to determine the correct lifetime for the fn return type.
566 /// The `LifetimeElisionCandidate` is used for diagnostics, to suggest introducing named
568 lifetime_elision_candidates: Option<FxIndexMap<LifetimeRes, LifetimeElisionCandidate>>,
570 /// The trait that the current context can refer to.
571 current_trait_ref: Option<(Module<'a>, TraitRef)>,
573 /// Fields used to add information to diagnostic errors.
574 diagnostic_metadata: Box<DiagnosticMetadata<'ast>>,
576 /// State used to know whether to ignore resolution errors for function bodies.
578 /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items.
579 /// In most cases this will be `None`, in which case errors will always be reported.
580 /// If it is `true`, then it will be updated when entering a nested function or trait body.
583 /// Count the number of places a lifetime is used.
584 lifetime_uses: FxHashMap<LocalDefId, LifetimeUseSet>,
587 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
588 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
589 fn visit_attribute(&mut self, _: &'ast Attribute) {
590 // We do not want to resolve expressions that appear in attributes,
591 // as they do not correspond to actual code.
593 fn visit_item(&mut self, item: &'ast Item) {
594 let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
595 // Always report errors in items we just entered.
596 let old_ignore = replace(&mut self.in_func_body, false);
597 self.with_lifetime_rib(LifetimeRibKind::Item, |this| this.resolve_item(item));
598 self.in_func_body = old_ignore;
599 self.diagnostic_metadata.current_item = prev;
601 fn visit_arm(&mut self, arm: &'ast Arm) {
602 self.resolve_arm(arm);
604 fn visit_block(&mut self, block: &'ast Block) {
605 self.resolve_block(block);
607 fn visit_anon_const(&mut self, constant: &'ast AnonConst) {
608 // We deal with repeat expressions explicitly in `resolve_expr`.
609 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
610 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
611 this.resolve_anon_const(constant, IsRepeatExpr::No);
615 fn visit_expr(&mut self, expr: &'ast Expr) {
616 self.resolve_expr(expr, None);
618 fn visit_local(&mut self, local: &'ast Local) {
619 let local_spans = match local.pat.kind {
620 // We check for this to avoid tuple struct fields.
621 PatKind::Wild => None,
624 local.ty.as_ref().map(|ty| ty.span),
625 local.kind.init().map(|init| init.span),
628 let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans);
629 self.resolve_local(local);
630 self.diagnostic_metadata.current_let_binding = original;
632 fn visit_ty(&mut self, ty: &'ast Ty) {
633 let prev = self.diagnostic_metadata.current_trait_object;
634 let prev_ty = self.diagnostic_metadata.current_type_path;
636 TyKind::Rptr(None, _) => {
637 // Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
639 // This span will be used in case of elision failure.
640 let span = self.r.session.source_map().start_point(ty.span);
641 self.resolve_elided_lifetime(ty.id, span);
642 visit::walk_ty(self, ty);
644 TyKind::Path(ref qself, ref path) => {
645 self.diagnostic_metadata.current_type_path = Some(ty);
646 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
648 // Check whether we should interpret this as a bare trait object.
650 && let Some(partial_res) = self.r.partial_res_map.get(&ty.id)
651 && let Some(Res::Def(DefKind::Trait | DefKind::TraitAlias, _)) = partial_res.full_res()
653 // This path is actually a bare trait object. In case of a bare `Fn`-trait
654 // object with anonymous lifetimes, we need this rib to correctly place the
655 // synthetic lifetimes.
656 let span = ty.span.shrink_to_lo().to(path.span.shrink_to_lo());
657 self.with_generic_param_rib(
660 LifetimeRibKind::Generics {
662 kind: LifetimeBinderKind::PolyTrait,
665 |this| this.visit_path(&path, ty.id),
668 visit::walk_ty(self, ty)
671 TyKind::ImplicitSelf => {
672 let self_ty = Ident::with_dummy_span(kw::SelfUpper);
674 .resolve_ident_in_lexical_scope(
677 Some(Finalize::new(ty.id, ty.span)),
680 .map_or(Res::Err, |d| d.res());
681 self.r.record_partial_res(ty.id, PartialRes::new(res));
682 visit::walk_ty(self, ty)
684 TyKind::ImplTrait(..) => {
685 let candidates = self.lifetime_elision_candidates.take();
686 visit::walk_ty(self, ty);
687 self.lifetime_elision_candidates = candidates;
689 TyKind::TraitObject(ref bounds, ..) => {
690 self.diagnostic_metadata.current_trait_object = Some(&bounds[..]);
691 visit::walk_ty(self, ty)
693 TyKind::BareFn(ref bare_fn) => {
694 let span = ty.span.shrink_to_lo().to(bare_fn.decl_span.shrink_to_lo());
695 self.with_generic_param_rib(
696 &bare_fn.generic_params,
698 LifetimeRibKind::Generics {
700 kind: LifetimeBinderKind::BareFnType,
704 this.visit_generic_params(&bare_fn.generic_params, false);
705 this.with_lifetime_rib(
706 LifetimeRibKind::AnonymousCreateParameter {
708 report_in_path: false,
711 this.resolve_fn_signature(
714 // We don't need to deal with patterns in parameters, because
715 // they are not possible for foreign or bodiless functions.
720 .map(|Param { ty, .. }| (None, &**ty)),
721 &bare_fn.decl.output,
728 _ => visit::walk_ty(self, ty),
730 self.diagnostic_metadata.current_trait_object = prev;
731 self.diagnostic_metadata.current_type_path = prev_ty;
733 fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef) {
734 let span = tref.span.shrink_to_lo().to(tref.trait_ref.path.span.shrink_to_lo());
735 self.with_generic_param_rib(
736 &tref.bound_generic_params,
738 LifetimeRibKind::Generics {
739 binder: tref.trait_ref.ref_id,
740 kind: LifetimeBinderKind::PolyTrait,
744 this.visit_generic_params(&tref.bound_generic_params, false);
745 this.smart_resolve_path(
746 tref.trait_ref.ref_id,
748 &tref.trait_ref.path,
749 PathSource::Trait(AliasPossibility::Maybe),
751 this.visit_trait_ref(&tref.trait_ref);
755 fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) {
756 match foreign_item.kind {
757 ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
758 self.with_generic_param_rib(
760 ItemRibKind(HasGenericParams::Yes(generics.span)),
761 LifetimeRibKind::Generics {
762 binder: foreign_item.id,
763 kind: LifetimeBinderKind::Item,
766 |this| visit::walk_foreign_item(this, foreign_item),
769 ForeignItemKind::Fn(box Fn { ref generics, .. }) => {
770 self.with_generic_param_rib(
772 ItemRibKind(HasGenericParams::Yes(generics.span)),
773 LifetimeRibKind::Generics {
774 binder: foreign_item.id,
775 kind: LifetimeBinderKind::Function,
778 |this| visit::walk_foreign_item(this, foreign_item),
781 ForeignItemKind::Static(..) => {
782 self.with_static_rib(|this| {
783 visit::walk_foreign_item(this, foreign_item);
786 ForeignItemKind::MacCall(..) => {
787 panic!("unexpanded macro in resolve!")
791 fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, fn_id: NodeId) {
792 let previous_value = self.diagnostic_metadata.current_function;
794 // Bail if the function is foreign, and thus cannot validly have
795 // a body, or if there's no body for some other reason.
796 FnKind::Fn(FnCtxt::Foreign, _, sig, _, generics, _)
797 | FnKind::Fn(_, _, sig, _, generics, None) => {
798 self.visit_fn_header(&sig.header);
799 self.visit_generics(generics);
800 self.with_lifetime_rib(
801 LifetimeRibKind::AnonymousCreateParameter {
803 report_in_path: false,
806 this.resolve_fn_signature(
809 sig.decl.inputs.iter().map(|Param { ty, .. }| (None, &**ty)),
813 this.record_lifetime_params_for_async(
815 sig.header.asyncness.opt_return_id(),
822 self.diagnostic_metadata.current_function = Some((fn_kind, sp));
824 // Do not update `current_function` for closures: it suggests `self` parameters.
825 FnKind::Closure(..) => {}
827 debug!("(resolving function) entering function");
829 // Create a value rib for the function.
830 self.with_rib(ValueNS, ClosureOrAsyncRibKind, |this| {
831 // Create a label rib for the function.
832 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
834 FnKind::Fn(_, _, sig, _, generics, body) => {
835 this.visit_generics(generics);
837 let declaration = &sig.decl;
838 let async_node_id = sig.header.asyncness.opt_return_id();
840 this.with_lifetime_rib(
841 LifetimeRibKind::AnonymousCreateParameter {
843 report_in_path: async_node_id.is_some(),
846 this.resolve_fn_signature(
848 declaration.has_self(),
852 .map(|Param { pat, ty, .. }| (Some(&**pat), &**ty)),
858 this.record_lifetime_params_for_async(fn_id, async_node_id);
860 if let Some(body) = body {
861 // Ignore errors in function bodies if this is rustdoc
862 // Be sure not to set this until the function signature has been resolved.
863 let previous_state = replace(&mut this.in_func_body, true);
864 // Resolve the function body, potentially inside the body of an async closure
865 this.with_lifetime_rib(
866 LifetimeRibKind::Elided(LifetimeRes::Infer),
867 |this| this.visit_block(body),
870 debug!("(resolving function) leaving function");
871 this.in_func_body = previous_state;
874 FnKind::Closure(binder, declaration, body) => {
875 this.visit_closure_binder(binder);
877 this.with_lifetime_rib(
879 // We do not have any explicit generic lifetime parameter.
880 ClosureBinder::NotPresent => {
881 LifetimeRibKind::AnonymousCreateParameter {
883 report_in_path: false,
886 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
888 // Add each argument to the rib.
889 |this| this.resolve_params(&declaration.inputs),
891 this.with_lifetime_rib(
893 ClosureBinder::NotPresent => {
894 LifetimeRibKind::Elided(LifetimeRes::Infer)
896 ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError,
898 |this| visit::walk_fn_ret_ty(this, &declaration.output),
901 // Ignore errors in function bodies if this is rustdoc
902 // Be sure not to set this until the function signature has been resolved.
903 let previous_state = replace(&mut this.in_func_body, true);
904 // Resolve the function body, potentially inside the body of an async closure
905 this.with_lifetime_rib(
906 LifetimeRibKind::Elided(LifetimeRes::Infer),
907 |this| this.visit_expr(body),
910 debug!("(resolving function) leaving function");
911 this.in_func_body = previous_state;
916 self.diagnostic_metadata.current_function = previous_value;
918 fn visit_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
919 self.resolve_lifetime(lifetime, use_ctxt)
922 fn visit_generics(&mut self, generics: &'ast Generics) {
923 self.visit_generic_params(
925 self.diagnostic_metadata.current_self_item.is_some(),
927 for p in &generics.where_clause.predicates {
928 self.visit_where_predicate(p);
932 fn visit_closure_binder(&mut self, b: &'ast ClosureBinder) {
934 ClosureBinder::NotPresent => {}
935 ClosureBinder::For { generic_params, .. } => {
936 self.visit_generic_params(
938 self.diagnostic_metadata.current_self_item.is_some(),
944 fn visit_generic_arg(&mut self, arg: &'ast GenericArg) {
945 debug!("visit_generic_arg({:?})", arg);
946 let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true);
948 GenericArg::Type(ref ty) => {
949 // We parse const arguments as path types as we cannot distinguish them during
950 // parsing. We try to resolve that ambiguity by attempting resolution the type
951 // namespace first, and if that fails we try again in the value namespace. If
952 // resolution in the value namespace succeeds, we have an generic const argument on
954 if let TyKind::Path(ref qself, ref path) = ty.kind {
955 // We cannot disambiguate multi-segment paths right now as that requires type
957 if path.segments.len() == 1 && path.segments[0].args.is_none() {
958 let mut check_ns = |ns| {
959 self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns)
962 if !check_ns(TypeNS) && check_ns(ValueNS) {
963 // This must be equivalent to `visit_anon_const`, but we cannot call it
964 // directly due to visitor lifetimes so we have to copy-paste some code.
966 // Note that we might not be inside of an repeat expression here,
967 // but considering that `IsRepeatExpr` is only relevant for
968 // non-trivial constants this is doesn't matter.
969 self.with_constant_rib(
971 ConstantHasGenerics::Yes,
974 this.smart_resolve_path(
978 PathSource::Expr(None),
981 if let Some(ref qself) = *qself {
982 this.visit_ty(&qself.ty);
984 this.visit_path(path, ty.id);
988 self.diagnostic_metadata.currently_processing_generics = prev;
996 GenericArg::Lifetime(lt) => self.visit_lifetime(lt, visit::LifetimeCtxt::GenericArg),
997 GenericArg::Const(ct) => self.visit_anon_const(ct),
999 self.diagnostic_metadata.currently_processing_generics = prev;
1002 fn visit_assoc_constraint(&mut self, constraint: &'ast AssocConstraint) {
1003 self.visit_ident(constraint.ident);
1004 if let Some(ref gen_args) = constraint.gen_args {
1005 // Forbid anonymous lifetimes in GAT parameters until proper semantics are decided.
1006 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1007 this.visit_generic_args(gen_args)
1010 match constraint.kind {
1011 AssocConstraintKind::Equality { ref term } => match term {
1012 Term::Ty(ty) => self.visit_ty(ty),
1013 Term::Const(c) => self.visit_anon_const(c),
1015 AssocConstraintKind::Bound { ref bounds } => {
1016 walk_list!(self, visit_param_bound, bounds, BoundKind::Bound);
1021 fn visit_path_segment(&mut self, path_segment: &'ast PathSegment) {
1022 if let Some(ref args) = path_segment.args {
1024 GenericArgs::AngleBracketed(..) => visit::walk_generic_args(self, args),
1025 GenericArgs::Parenthesized(p_args) => {
1026 // Probe the lifetime ribs to know how to behave.
1027 for rib in self.lifetime_ribs.iter().rev() {
1029 // We are inside a `PolyTraitRef`. The lifetimes are
1030 // to be intoduced in that (maybe implicit) `for<>` binder.
1031 LifetimeRibKind::Generics {
1033 kind: LifetimeBinderKind::PolyTrait,
1036 self.with_lifetime_rib(
1037 LifetimeRibKind::AnonymousCreateParameter {
1039 report_in_path: false,
1042 this.resolve_fn_signature(
1045 p_args.inputs.iter().map(|ty| (None, &**ty)),
1052 // We have nowhere to introduce generics. Code is malformed,
1053 // so use regular lifetime resolution to avoid spurious errors.
1054 LifetimeRibKind::Item | LifetimeRibKind::Generics { .. } => {
1055 visit::walk_generic_args(self, args);
1058 LifetimeRibKind::AnonymousCreateParameter { .. }
1059 | LifetimeRibKind::AnonymousReportError
1060 | LifetimeRibKind::Elided(_)
1061 | LifetimeRibKind::ElisionFailure
1062 | LifetimeRibKind::AnonConst
1063 | LifetimeRibKind::ConstGeneric => {}
1071 fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
1072 debug!("visit_where_predicate {:?}", p);
1073 let previous_value =
1074 replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p));
1075 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1076 if let WherePredicate::BoundPredicate(WhereBoundPredicate {
1079 ref bound_generic_params,
1080 span: predicate_span,
1084 let span = predicate_span.shrink_to_lo().to(bounded_ty.span.shrink_to_lo());
1085 this.with_generic_param_rib(
1086 &bound_generic_params,
1088 LifetimeRibKind::Generics {
1089 binder: bounded_ty.id,
1090 kind: LifetimeBinderKind::WhereBound,
1094 this.visit_generic_params(&bound_generic_params, false);
1095 this.visit_ty(bounded_ty);
1096 for bound in bounds {
1097 this.visit_param_bound(bound, BoundKind::Bound)
1102 visit::walk_where_predicate(this, p);
1105 self.diagnostic_metadata.current_where_predicate = previous_value;
1108 fn visit_inline_asm(&mut self, asm: &'ast InlineAsm) {
1109 for (op, _) in &asm.operands {
1111 InlineAsmOperand::In { expr, .. }
1112 | InlineAsmOperand::Out { expr: Some(expr), .. }
1113 | InlineAsmOperand::InOut { expr, .. } => self.visit_expr(expr),
1114 InlineAsmOperand::Out { expr: None, .. } => {}
1115 InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
1116 self.visit_expr(in_expr);
1117 if let Some(out_expr) = out_expr {
1118 self.visit_expr(out_expr);
1121 InlineAsmOperand::Const { anon_const, .. } => {
1122 // Although this is `DefKind::AnonConst`, it is allowed to reference outer
1123 // generic parameters like an inline const.
1124 self.resolve_inline_const(anon_const);
1126 InlineAsmOperand::Sym { sym } => self.visit_inline_asm_sym(sym),
1131 fn visit_inline_asm_sym(&mut self, sym: &'ast InlineAsmSym) {
1132 // This is similar to the code for AnonConst.
1133 self.with_rib(ValueNS, InlineAsmSymRibKind, |this| {
1134 this.with_rib(TypeNS, InlineAsmSymRibKind, |this| {
1135 this.with_label_rib(InlineAsmSymRibKind, |this| {
1136 this.smart_resolve_path(
1140 PathSource::Expr(None),
1142 visit::walk_inline_asm_sym(this, sym);
1149 impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
1150 fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> {
1151 // During late resolution we only track the module component of the parent scope,
1152 // although it may be useful to track other components as well for diagnostics.
1153 let graph_root = resolver.graph_root;
1154 let parent_scope = ParentScope::module(graph_root, resolver);
1155 let start_rib_kind = ModuleRibKind(graph_root);
1156 LateResolutionVisitor {
1160 value_ns: vec![Rib::new(start_rib_kind)],
1161 type_ns: vec![Rib::new(start_rib_kind)],
1162 macro_ns: vec![Rib::new(start_rib_kind)],
1164 label_ribs: Vec::new(),
1165 lifetime_ribs: Vec::new(),
1166 lifetime_elision_candidates: None,
1167 current_trait_ref: None,
1168 diagnostic_metadata: Box::new(DiagnosticMetadata::default()),
1169 // errors at module scope should always be reported
1170 in_func_body: false,
1171 lifetime_uses: Default::default(),
1175 fn maybe_resolve_ident_in_lexical_scope(
1179 ) -> Option<LexicalScopeBinding<'a>> {
1180 self.r.resolve_ident_in_lexical_scope(
1190 fn resolve_ident_in_lexical_scope(
1194 finalize: Option<Finalize>,
1195 ignore_binding: Option<&'a NameBinding<'a>>,
1196 ) -> Option<LexicalScopeBinding<'a>> {
1197 self.r.resolve_ident_in_lexical_scope(
1210 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1211 finalize: Option<Finalize>,
1212 ) -> PathResult<'a> {
1213 self.r.resolve_path_with_ribs(
1225 // We maintain a list of value ribs and type ribs.
1227 // Simultaneously, we keep track of the current position in the module
1228 // graph in the `parent_scope.module` pointer. When we go to resolve a name in
1229 // the value or type namespaces, we first look through all the ribs and
1230 // then query the module graph. When we resolve a name in the module
1231 // namespace, we can skip all the ribs (since nested modules are not
1232 // allowed within blocks in Rust) and jump straight to the current module
1235 // Named implementations are handled separately. When we find a method
1236 // call, we consult the module node to find all of the implementations in
1237 // scope. This information is lazily cached in the module node. We then
1238 // generate a fake "implementation scope" containing all the
1239 // implementations thus found, for compatibility with old resolve pass.
1241 /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`).
1246 work: impl FnOnce(&mut Self) -> T,
1248 self.ribs[ns].push(Rib::new(kind));
1249 let ret = work(self);
1250 self.ribs[ns].pop();
1254 fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
1255 if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
1256 // Move down in the graph.
1257 let orig_module = replace(&mut self.parent_scope.module, module);
1258 self.with_rib(ValueNS, ModuleRibKind(module), |this| {
1259 this.with_rib(TypeNS, ModuleRibKind(module), |this| {
1261 this.parent_scope.module = orig_module;
1270 fn visit_generic_params(&mut self, params: &'ast [GenericParam], add_self_upper: bool) {
1271 // For type parameter defaults, we have to ban access
1272 // to following type parameters, as the InternalSubsts can only
1273 // provide previous type parameters as they're built. We
1274 // put all the parameters on the ban list and then remove
1275 // them one by one as they are processed and become available.
1276 let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1277 let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
1278 for param in params.iter() {
1280 GenericParamKind::Type { .. } => {
1283 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1285 GenericParamKind::Const { .. } => {
1286 forward_const_ban_rib
1288 .insert(Ident::with_dummy_span(param.ident.name), Res::Err);
1290 GenericParamKind::Lifetime => {}
1294 // rust-lang/rust#61631: The type `Self` is essentially
1295 // another type parameter. For ADTs, we consider it
1296 // well-defined only after all of the ADT type parameters have
1297 // been provided. Therefore, we do not allow use of `Self`
1298 // anywhere in ADT type parameter defaults.
1300 // (We however cannot ban `Self` for defaults on *all* generic
1301 // lists; e.g. trait generics can usefully refer to `Self`,
1302 // such as in the case of `trait Add<Rhs = Self>`.)
1304 // (`Some` if + only if we are in ADT's generics.)
1305 forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
1308 self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
1309 for param in params {
1311 GenericParamKind::Lifetime => {
1312 for bound in ¶m.bounds {
1313 this.visit_param_bound(bound, BoundKind::Bound);
1316 GenericParamKind::Type { ref default } => {
1317 for bound in ¶m.bounds {
1318 this.visit_param_bound(bound, BoundKind::Bound);
1321 if let Some(ref ty) = default {
1322 this.ribs[TypeNS].push(forward_ty_ban_rib);
1323 this.ribs[ValueNS].push(forward_const_ban_rib);
1325 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1326 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1329 // Allow all following defaults to refer to this type parameter.
1332 .remove(&Ident::with_dummy_span(param.ident.name));
1334 GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
1335 // Const parameters can't have param bounds.
1336 assert!(param.bounds.is_empty());
1338 this.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
1339 this.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
1340 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1343 this.ribs[TypeNS].pop().unwrap();
1344 this.ribs[ValueNS].pop().unwrap();
1346 if let Some(ref expr) = default {
1347 this.ribs[TypeNS].push(forward_ty_ban_rib);
1348 this.ribs[ValueNS].push(forward_const_ban_rib);
1349 this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| {
1350 this.resolve_anon_const(expr, IsRepeatExpr::No)
1352 forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap();
1353 forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap();
1356 // Allow all following defaults to refer to this const parameter.
1357 forward_const_ban_rib
1359 .remove(&Ident::with_dummy_span(param.ident.name));
1366 #[instrument(level = "debug", skip(self, work))]
1367 fn with_lifetime_rib<T>(
1369 kind: LifetimeRibKind,
1370 work: impl FnOnce(&mut Self) -> T,
1372 self.lifetime_ribs.push(LifetimeRib::new(kind));
1373 let outer_elision_candidates = self.lifetime_elision_candidates.take();
1374 let ret = work(self);
1375 self.lifetime_elision_candidates = outer_elision_candidates;
1376 self.lifetime_ribs.pop();
1380 #[instrument(level = "debug", skip(self))]
1381 fn resolve_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) {
1382 let ident = lifetime.ident;
1384 if ident.name == kw::StaticLifetime {
1385 self.record_lifetime_res(
1387 LifetimeRes::Static,
1388 LifetimeElisionCandidate::Named,
1393 if ident.name == kw::UnderscoreLifetime {
1394 return self.resolve_anonymous_lifetime(lifetime, false);
1397 let mut lifetime_rib_iter = self.lifetime_ribs.iter().rev();
1398 while let Some(rib) = lifetime_rib_iter.next() {
1399 let normalized_ident = ident.normalize_to_macros_2_0();
1400 if let Some(&(_, res)) = rib.bindings.get(&normalized_ident) {
1401 self.record_lifetime_res(lifetime.id, res, LifetimeElisionCandidate::Named);
1403 if let LifetimeRes::Param { param, .. } = res {
1404 match self.lifetime_uses.entry(param) {
1405 Entry::Vacant(v) => {
1406 debug!("First use of {:?} at {:?}", res, ident.span);
1411 .find_map(|rib| match rib.kind {
1412 // Do not suggest eliding a lifetime where an anonymous
1413 // lifetime would be illegal.
1414 LifetimeRibKind::Item
1415 | LifetimeRibKind::AnonymousReportError
1416 | LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many),
1417 // An anonymous lifetime is legal here, go ahead.
1418 LifetimeRibKind::AnonymousCreateParameter { .. } => {
1419 Some(LifetimeUseSet::One { use_span: ident.span, use_ctxt })
1421 // Only report if eliding the lifetime would have the same
1423 LifetimeRibKind::Elided(r) => Some(if res == r {
1424 LifetimeUseSet::One { use_span: ident.span, use_ctxt }
1426 LifetimeUseSet::Many
1428 LifetimeRibKind::Generics { .. } => None,
1429 LifetimeRibKind::ConstGeneric | LifetimeRibKind::AnonConst => {
1430 span_bug!(ident.span, "unexpected rib kind: {:?}", rib.kind)
1433 .unwrap_or(LifetimeUseSet::Many);
1434 debug!(?use_ctxt, ?use_set);
1437 Entry::Occupied(mut o) => {
1438 debug!("Many uses of {:?} at {:?}", res, ident.span);
1439 *o.get_mut() = LifetimeUseSet::Many;
1447 LifetimeRibKind::Item => break,
1448 LifetimeRibKind::ConstGeneric => {
1449 self.emit_non_static_lt_in_const_generic_error(lifetime);
1450 self.record_lifetime_res(
1453 LifetimeElisionCandidate::Ignore,
1457 LifetimeRibKind::AnonConst => {
1458 self.maybe_emit_forbidden_non_static_lifetime_error(lifetime);
1459 self.record_lifetime_res(
1462 LifetimeElisionCandidate::Ignore,
1466 LifetimeRibKind::AnonymousCreateParameter { .. }
1467 | LifetimeRibKind::Elided(_)
1468 | LifetimeRibKind::Generics { .. }
1469 | LifetimeRibKind::ElisionFailure
1470 | LifetimeRibKind::AnonymousReportError => {}
1474 let mut outer_res = None;
1475 for rib in lifetime_rib_iter {
1476 let normalized_ident = ident.normalize_to_macros_2_0();
1477 if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) {
1478 outer_res = Some(outer);
1483 self.emit_undeclared_lifetime_error(lifetime, outer_res);
1484 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, LifetimeElisionCandidate::Named);
1487 #[instrument(level = "debug", skip(self))]
1488 fn resolve_anonymous_lifetime(&mut self, lifetime: &Lifetime, elided: bool) {
1489 debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
1491 let missing_lifetime = MissingLifetime {
1493 span: lifetime.ident.span,
1495 MissingLifetimeKind::Ampersand
1497 MissingLifetimeKind::Underscore
1501 let elision_candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1502 for rib in self.lifetime_ribs.iter().rev() {
1505 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1506 let res = self.create_fresh_lifetime(lifetime.id, lifetime.ident, binder);
1507 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1510 LifetimeRibKind::AnonymousReportError => {
1511 let (msg, note) = if elided {
1513 "`&` without an explicit lifetime name cannot be used here",
1514 "explicit lifetime name needed here",
1517 ("`'_` cannot be used here", "`'_` is a reserved lifetime name")
1519 rustc_errors::struct_span_err!(
1521 lifetime.ident.span,
1526 .span_label(lifetime.ident.span, note)
1529 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1532 LifetimeRibKind::Elided(res) => {
1533 self.record_lifetime_res(lifetime.id, res, elision_candidate);
1536 LifetimeRibKind::ElisionFailure => {
1537 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1538 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1541 LifetimeRibKind::Item => break,
1542 LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstGeneric => {}
1543 LifetimeRibKind::AnonConst => {
1544 // There is always an `Elided(LifetimeRes::Static)` inside an `AnonConst`.
1545 span_bug!(lifetime.ident.span, "unexpected rib kind: {:?}", rib.kind)
1549 self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate);
1550 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1553 #[instrument(level = "debug", skip(self))]
1554 fn resolve_elided_lifetime(&mut self, anchor_id: NodeId, span: Span) {
1555 let id = self.r.next_node_id();
1556 let lt = Lifetime { id, ident: Ident::new(kw::UnderscoreLifetime, span) };
1558 self.record_lifetime_res(
1560 LifetimeRes::ElidedAnchor { start: id, end: NodeId::from_u32(id.as_u32() + 1) },
1561 LifetimeElisionCandidate::Ignore,
1563 self.resolve_anonymous_lifetime(<, true);
1566 #[instrument(level = "debug", skip(self))]
1567 fn create_fresh_lifetime(&mut self, id: NodeId, ident: Ident, binder: NodeId) -> LifetimeRes {
1568 debug_assert_eq!(ident.name, kw::UnderscoreLifetime);
1569 debug!(?ident.span);
1571 // Leave the responsibility to create the `LocalDefId` to lowering.
1572 let param = self.r.next_node_id();
1573 let res = LifetimeRes::Fresh { param, binder };
1575 // Record the created lifetime parameter so lowering can pick it up and add it to HIR.
1577 .extra_lifetime_params_map
1579 .or_insert_with(Vec::new)
1580 .push((ident, param, res));
1584 #[instrument(level = "debug", skip(self))]
1585 fn resolve_elided_lifetimes_in_path(
1588 partial_res: PartialRes,
1590 source: PathSource<'_>,
1593 let proj_start = path.len() - partial_res.unresolved_segments();
1594 for (i, segment) in path.iter().enumerate() {
1595 if segment.has_lifetime_args {
1598 let Some(segment_id) = segment.id else {
1602 // Figure out if this is a type/trait segment,
1603 // which may need lifetime elision performed.
1604 let type_def_id = match partial_res.base_res() {
1605 Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => self.r.parent(def_id),
1606 Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => self.r.parent(def_id),
1607 Res::Def(DefKind::Struct, def_id)
1608 | Res::Def(DefKind::Union, def_id)
1609 | Res::Def(DefKind::Enum, def_id)
1610 | Res::Def(DefKind::TyAlias, def_id)
1611 | Res::Def(DefKind::Trait, def_id)
1612 if i + 1 == proj_start =>
1619 let expected_lifetimes = self.r.item_generics_num_lifetimes(type_def_id);
1620 if expected_lifetimes == 0 {
1624 let node_ids = self.r.next_node_ids(expected_lifetimes);
1625 self.record_lifetime_res(
1627 LifetimeRes::ElidedAnchor { start: node_ids.start, end: node_ids.end },
1628 LifetimeElisionCandidate::Ignore,
1631 let inferred = match source {
1632 PathSource::Trait(..) | PathSource::TraitItem(..) | PathSource::Type => false,
1633 PathSource::Expr(..)
1635 | PathSource::Struct
1636 | PathSource::TupleStruct(..) => true,
1639 // Do not create a parameter for patterns and expressions: type checking can infer
1640 // the appropriate lifetime for us.
1641 for id in node_ids {
1642 self.record_lifetime_res(
1645 LifetimeElisionCandidate::Named,
1651 let elided_lifetime_span = if segment.has_generic_args {
1652 // If there are brackets, but not generic arguments, then use the opening bracket
1653 segment.args_span.with_hi(segment.args_span.lo() + BytePos(1))
1655 // If there are no brackets, use the identifier span.
1656 // HACK: we use find_ancestor_inside to properly suggest elided spans in paths
1657 // originating from macros, since the segment's span might be from a macro arg.
1658 segment.ident.span.find_ancestor_inside(path_span).unwrap_or(path_span)
1660 let ident = Ident::new(kw::UnderscoreLifetime, elided_lifetime_span);
1662 let missing_lifetime = MissingLifetime {
1664 span: elided_lifetime_span,
1665 kind: if segment.has_generic_args {
1666 MissingLifetimeKind::Comma
1668 MissingLifetimeKind::Brackets
1670 count: expected_lifetimes,
1672 let mut should_lint = true;
1673 for rib in self.lifetime_ribs.iter().rev() {
1675 // In create-parameter mode we error here because we don't want to support
1676 // deprecated impl elision in new features like impl elision and `async fn`,
1677 // both of which work using the `CreateParameter` mode:
1679 // impl Foo for std::cell::Ref<u32> // note lack of '_
1680 // async fn foo(_: std::cell::Ref<u32>) { ... }
1681 LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. } => {
1682 let sess = self.r.session;
1683 let mut err = rustc_errors::struct_span_err!(
1687 "implicit elided lifetime not allowed here"
1689 rustc_errors::add_elided_lifetime_in_path_suggestion(
1694 !segment.has_generic_args,
1695 elided_lifetime_span,
1697 err.note("assuming a `'static` lifetime...");
1699 should_lint = false;
1701 for id in node_ids {
1702 self.record_lifetime_res(
1705 LifetimeElisionCandidate::Named,
1710 // Do not create a parameter for patterns and expressions.
1711 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
1712 // Group all suggestions into the first record.
1713 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1714 for id in node_ids {
1715 let res = self.create_fresh_lifetime(id, ident, binder);
1716 self.record_lifetime_res(
1719 replace(&mut candidate, LifetimeElisionCandidate::Named),
1724 LifetimeRibKind::Elided(res) => {
1725 let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime);
1726 for id in node_ids {
1727 self.record_lifetime_res(
1730 replace(&mut candidate, LifetimeElisionCandidate::Ignore),
1735 LifetimeRibKind::ElisionFailure => {
1736 self.diagnostic_metadata.current_elision_failures.push(missing_lifetime);
1737 for id in node_ids {
1738 self.record_lifetime_res(
1741 LifetimeElisionCandidate::Ignore,
1746 // `LifetimeRes::Error`, which would usually be used in the case of
1747 // `ReportError`, is unsuitable here, as we don't emit an error yet. Instead,
1748 // we simply resolve to an implicit lifetime, which will be checked later, at
1749 // which point a suitable error will be emitted.
1750 LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => {
1751 for id in node_ids {
1752 self.record_lifetime_res(
1755 LifetimeElisionCandidate::Ignore,
1758 self.report_missing_lifetime_specifiers(vec![missing_lifetime], None);
1761 LifetimeRibKind::Generics { .. } | LifetimeRibKind::ConstGeneric => {}
1762 LifetimeRibKind::AnonConst => {
1763 // There is always an `Elided(LifetimeRes::Static)` inside an `AnonConst`.
1764 span_bug!(elided_lifetime_span, "unexpected rib kind: {:?}", rib.kind)
1770 self.r.lint_buffer.buffer_lint_with_diagnostic(
1771 lint::builtin::ELIDED_LIFETIMES_IN_PATHS,
1773 elided_lifetime_span,
1774 "hidden lifetime parameters in types are deprecated",
1775 lint::BuiltinLintDiagnostics::ElidedLifetimesInPaths(
1778 !segment.has_generic_args,
1779 elided_lifetime_span,
1786 #[instrument(level = "debug", skip(self))]
1787 fn record_lifetime_res(
1791 candidate: LifetimeElisionCandidate,
1793 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1795 "lifetime {:?} resolved multiple times ({:?} before, {:?} now)",
1800 LifetimeRes::Param { .. } | LifetimeRes::Fresh { .. } | LifetimeRes::Static => {
1801 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
1802 candidates.insert(res, candidate);
1805 LifetimeRes::Infer | LifetimeRes::Error | LifetimeRes::ElidedAnchor { .. } => {}
1809 #[instrument(level = "debug", skip(self))]
1810 fn record_lifetime_param(&mut self, id: NodeId, res: LifetimeRes) {
1811 if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) {
1813 "lifetime parameter {:?} resolved multiple times ({:?} before, {:?} now)",
1819 /// Perform resolution of a function signature, accounting for lifetime elision.
1820 #[instrument(level = "debug", skip(self, inputs))]
1821 fn resolve_fn_signature(
1825 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)> + Clone,
1826 output_ty: &'ast FnRetTy,
1828 // Add each argument to the rib.
1829 let elision_lifetime = self.resolve_fn_params(has_self, inputs);
1830 debug!(?elision_lifetime);
1832 let outer_failures = take(&mut self.diagnostic_metadata.current_elision_failures);
1833 let output_rib = if let Ok(res) = elision_lifetime.as_ref() {
1834 LifetimeRibKind::Elided(*res)
1836 LifetimeRibKind::ElisionFailure
1838 self.with_lifetime_rib(output_rib, |this| visit::walk_fn_ret_ty(this, &output_ty));
1839 let elision_failures =
1840 replace(&mut self.diagnostic_metadata.current_elision_failures, outer_failures);
1841 if !elision_failures.is_empty() {
1842 let Err(failure_info) = elision_lifetime else { bug!() };
1843 self.report_missing_lifetime_specifiers(elision_failures, Some(failure_info));
1847 /// Resolve inside function parameters and parameter types.
1848 /// Returns the lifetime for elision in fn return type,
1849 /// or diagnostic information in case of elision failure.
1850 fn resolve_fn_params(
1853 inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)>,
1854 ) -> Result<LifetimeRes, (Vec<MissingLifetime>, Vec<ElisionFnParameter>)> {
1855 let outer_candidates =
1856 replace(&mut self.lifetime_elision_candidates, Some(Default::default()));
1858 let mut elision_lifetime = None;
1859 let mut lifetime_count = 0;
1860 let mut parameter_info = Vec::new();
1862 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
1863 for (index, (pat, ty)) in inputs.enumerate() {
1865 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
1866 if let Some(pat) = pat {
1867 this.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
1872 if let Some(ref candidates) = self.lifetime_elision_candidates {
1873 let new_count = candidates.len();
1874 let local_count = new_count - lifetime_count;
1875 if local_count != 0 {
1876 parameter_info.push(ElisionFnParameter {
1878 ident: if let Some(pat) = pat && let PatKind::Ident(_, ident, _) = pat.kind {
1883 lifetime_count: local_count,
1887 lifetime_count = new_count;
1890 // Handle `self` specially.
1891 if index == 0 && has_self {
1892 let self_lifetime = self.find_lifetime_for_self(ty);
1893 if let Set1::One(lifetime) = self_lifetime {
1894 elision_lifetime = Some(lifetime);
1895 self.lifetime_elision_candidates = None;
1897 self.lifetime_elision_candidates = Some(Default::default());
1901 debug!("(resolving function / closure) recorded parameter");
1904 let all_candidates = replace(&mut self.lifetime_elision_candidates, outer_candidates);
1905 debug!(?all_candidates);
1907 if let Some(res) = elision_lifetime {
1911 // We do not have a `self` candidate, look at the full list.
1912 let all_candidates = all_candidates.unwrap();
1913 if all_candidates.len() == 1 {
1914 Ok(*all_candidates.first().unwrap().0)
1916 let all_candidates = all_candidates
1918 .filter_map(|(_, candidate)| match candidate {
1919 LifetimeElisionCandidate::Ignore | LifetimeElisionCandidate::Named => None,
1920 LifetimeElisionCandidate::Missing(missing) => Some(missing),
1923 Err((all_candidates, parameter_info))
1927 /// List all the lifetimes that appear in the provided type.
1928 fn find_lifetime_for_self(&self, ty: &'ast Ty) -> Set1<LifetimeRes> {
1929 struct SelfVisitor<'r, 'a> {
1930 r: &'r Resolver<'a>,
1931 impl_self: Option<Res>,
1932 lifetime: Set1<LifetimeRes>,
1935 impl SelfVisitor<'_, '_> {
1936 // Look for `self: &'a Self` - also desugared from `&'a self`,
1937 // and if that matches, use it for elision and return early.
1938 fn is_self_ty(&self, ty: &Ty) -> bool {
1940 TyKind::ImplicitSelf => true,
1941 TyKind::Path(None, _) => {
1942 let path_res = self.r.partial_res_map[&ty.id].full_res();
1943 if let Some(Res::SelfTyParam { .. } | Res::SelfTyAlias { .. }) = path_res {
1946 self.impl_self.is_some() && path_res == self.impl_self
1953 impl<'a> Visitor<'a> for SelfVisitor<'_, '_> {
1954 fn visit_ty(&mut self, ty: &'a Ty) {
1955 trace!("SelfVisitor considering ty={:?}", ty);
1956 if let TyKind::Rptr(lt, ref mt) = ty.kind && self.is_self_ty(&mt.ty) {
1957 let lt_id = if let Some(lt) = lt {
1960 let res = self.r.lifetimes_res_map[&ty.id];
1961 let LifetimeRes::ElidedAnchor { start, .. } = res else { bug!() };
1964 let lt_res = self.r.lifetimes_res_map[<_id];
1965 trace!("SelfVisitor inserting res={:?}", lt_res);
1966 self.lifetime.insert(lt_res);
1968 visit::walk_ty(self, ty)
1972 let impl_self = self
1973 .diagnostic_metadata
1977 if let TyKind::Path(None, _) = ty.kind {
1978 self.r.partial_res_map.get(&ty.id)
1983 .and_then(|res| res.full_res())
1985 // Permit the types that unambiguously always
1986 // result in the same type constructor being used
1987 // (it can't differ between `Self` and `self`).
1990 Res::Def(DefKind::Struct | DefKind::Union | DefKind::Enum, _,) | Res::PrimTy(_)
1993 let mut visitor = SelfVisitor { r: self.r, impl_self, lifetime: Set1::Empty };
1994 visitor.visit_ty(ty);
1995 trace!("SelfVisitor found={:?}", visitor.lifetime);
1999 /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved
2000 /// label and reports an error if the label is not found or is unreachable.
2001 fn resolve_label(&mut self, mut label: Ident) -> Result<(NodeId, Span), ResolutionError<'a>> {
2002 let mut suggestion = None;
2004 for i in (0..self.label_ribs.len()).rev() {
2005 let rib = &self.label_ribs[i];
2007 if let MacroDefinition(def) = rib.kind {
2008 // If an invocation of this macro created `ident`, give up on `ident`
2009 // and switch to `ident`'s source from the macro definition.
2010 if def == self.r.macro_def(label.span.ctxt()) {
2011 label.span.remove_mark();
2015 let ident = label.normalize_to_macro_rules();
2016 if let Some((ident, id)) = rib.bindings.get_key_value(&ident) {
2017 let definition_span = ident.span;
2018 return if self.is_label_valid_from_rib(i) {
2019 Ok((*id, definition_span))
2021 Err(ResolutionError::UnreachableLabel {
2029 // Diagnostics: Check if this rib contains a label with a similar name, keep track of
2030 // the first such label that is encountered.
2031 suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label));
2034 Err(ResolutionError::UndeclaredLabel { name: label.name, suggestion })
2037 /// Determine whether or not a label from the `rib_index`th label rib is reachable.
2038 fn is_label_valid_from_rib(&self, rib_index: usize) -> bool {
2039 let ribs = &self.label_ribs[rib_index + 1..];
2042 if rib.kind.is_label_barrier() {
2050 fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
2051 debug!("resolve_adt");
2052 self.with_current_self_item(item, |this| {
2053 this.with_generic_param_rib(
2055 ItemRibKind(HasGenericParams::Yes(generics.span)),
2056 LifetimeRibKind::Generics {
2058 kind: LifetimeBinderKind::Item,
2059 span: generics.span,
2062 let item_def_id = this.r.local_def_id(item.id).to_def_id();
2065 alias_to: item_def_id,
2066 forbid_generic: false,
2067 is_trait_impl: false,
2070 visit::walk_item(this, item);
2078 fn future_proof_import(&mut self, use_tree: &UseTree) {
2079 let segments = &use_tree.prefix.segments;
2080 if !segments.is_empty() {
2081 let ident = segments[0].ident;
2082 if ident.is_path_segment_keyword() || ident.span.rust_2015() {
2086 let nss = match use_tree.kind {
2087 UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
2090 let report_error = |this: &Self, ns| {
2091 let what = if ns == TypeNS { "type parameters" } else { "local variables" };
2092 if this.should_report_errs() {
2095 .span_err(ident.span, &format!("imports cannot refer to {}", what));
2100 match self.maybe_resolve_ident_in_lexical_scope(ident, ns) {
2101 Some(LexicalScopeBinding::Res(..)) => {
2102 report_error(self, ns);
2104 Some(LexicalScopeBinding::Item(binding)) => {
2105 if let Some(LexicalScopeBinding::Res(..)) =
2106 self.resolve_ident_in_lexical_scope(ident, ns, None, Some(binding))
2108 report_error(self, ns);
2114 } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind {
2115 for (use_tree, _) in use_trees {
2116 self.future_proof_import(use_tree);
2121 fn resolve_item(&mut self, item: &'ast Item) {
2122 let name = item.ident.name;
2123 debug!("(resolving item) resolving {} ({:?})", name, item.kind);
2126 ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
2127 self.with_generic_param_rib(
2129 ItemRibKind(HasGenericParams::Yes(generics.span)),
2130 LifetimeRibKind::Generics {
2132 kind: LifetimeBinderKind::Item,
2133 span: generics.span,
2135 |this| visit::walk_item(this, item),
2139 ItemKind::Fn(box Fn { ref generics, .. }) => {
2140 self.with_generic_param_rib(
2142 ItemRibKind(HasGenericParams::Yes(generics.span)),
2143 LifetimeRibKind::Generics {
2145 kind: LifetimeBinderKind::Function,
2146 span: generics.span,
2148 |this| visit::walk_item(this, item),
2152 ItemKind::Enum(_, ref generics)
2153 | ItemKind::Struct(_, ref generics)
2154 | ItemKind::Union(_, ref generics) => {
2155 self.resolve_adt(item, generics);
2158 ItemKind::Impl(box Impl {
2162 items: ref impl_items,
2165 self.diagnostic_metadata.current_impl_items = Some(impl_items);
2166 self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items);
2167 self.diagnostic_metadata.current_impl_items = None;
2170 ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
2171 // Create a new rib for the trait-wide type parameters.
2172 self.with_generic_param_rib(
2174 ItemRibKind(HasGenericParams::Yes(generics.span)),
2175 LifetimeRibKind::Generics {
2177 kind: LifetimeBinderKind::Item,
2178 span: generics.span,
2181 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2182 this.with_self_rib(Res::SelfTyParam { trait_: local_def_id }, |this| {
2183 this.visit_generics(generics);
2184 walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);
2185 this.resolve_trait_items(items);
2191 ItemKind::TraitAlias(ref generics, ref bounds) => {
2192 // Create a new rib for the trait-wide type parameters.
2193 self.with_generic_param_rib(
2195 ItemRibKind(HasGenericParams::Yes(generics.span)),
2196 LifetimeRibKind::Generics {
2198 kind: LifetimeBinderKind::Item,
2199 span: generics.span,
2202 let local_def_id = this.r.local_def_id(item.id).to_def_id();
2203 this.with_self_rib(Res::SelfTyParam { trait_: local_def_id }, |this| {
2204 this.visit_generics(generics);
2205 walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
2211 ItemKind::Mod(..) | ItemKind::ForeignMod(_) => {
2212 self.with_scope(item.id, |this| {
2213 visit::walk_item(this, item);
2217 ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => {
2218 self.with_static_rib(|this| {
2219 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
2222 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2223 if let Some(expr) = expr {
2224 let constant_item_kind = match item.kind {
2225 ItemKind::Const(..) => ConstantItemKind::Const,
2226 ItemKind::Static(..) => ConstantItemKind::Static,
2227 _ => unreachable!(),
2229 // We already forbid generic params because of the above item rib,
2230 // so it doesn't matter whether this is a trivial constant.
2231 this.with_constant_rib(
2233 ConstantHasGenerics::Yes,
2234 Some((item.ident, constant_item_kind)),
2235 |this| this.visit_expr(expr),
2242 ItemKind::Use(ref use_tree) => {
2243 self.future_proof_import(use_tree);
2246 ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => {
2247 // do nothing, these are just around to be encoded
2250 ItemKind::GlobalAsm(_) => {
2251 visit::walk_item(self, item);
2254 ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"),
2258 fn with_generic_param_rib<'c, F>(
2260 params: &'c [GenericParam],
2262 lifetime_kind: LifetimeRibKind,
2265 F: FnOnce(&mut Self),
2267 debug!("with_generic_param_rib");
2268 let LifetimeRibKind::Generics { binder, span: generics_span, kind: generics_kind, .. }
2269 = lifetime_kind else { panic!() };
2271 let mut function_type_rib = Rib::new(kind);
2272 let mut function_value_rib = Rib::new(kind);
2273 let mut function_lifetime_rib = LifetimeRib::new(lifetime_kind);
2274 let mut seen_bindings = FxHashMap::default();
2275 // Store all seen lifetimes names from outer scopes.
2276 let mut seen_lifetimes = FxHashSet::default();
2278 // We also can't shadow bindings from the parent item
2279 if let AssocItemRibKind = kind {
2280 let mut add_bindings_for_ns = |ns| {
2281 let parent_rib = self.ribs[ns]
2283 .rfind(|r| matches!(r.kind, ItemRibKind(_)))
2284 .expect("associated item outside of an item");
2286 .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span)));
2288 add_bindings_for_ns(ValueNS);
2289 add_bindings_for_ns(TypeNS);
2292 // Forbid shadowing lifetime bindings
2293 for rib in self.lifetime_ribs.iter().rev() {
2294 seen_lifetimes.extend(rib.bindings.iter().map(|(ident, _)| *ident));
2295 if let LifetimeRibKind::Item = rib.kind {
2300 for param in params {
2301 let ident = param.ident.normalize_to_macros_2_0();
2302 debug!("with_generic_param_rib: {}", param.id);
2304 if let GenericParamKind::Lifetime = param.kind
2305 && let Some(&original) = seen_lifetimes.get(&ident)
2307 diagnostics::signal_lifetime_shadowing(self.r.session, original, param.ident);
2308 // Record lifetime res, so lowering knows there is something fishy.
2309 self.record_lifetime_param(param.id, LifetimeRes::Error);
2313 match seen_bindings.entry(ident) {
2314 Entry::Occupied(entry) => {
2315 let span = *entry.get();
2316 let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span);
2317 self.report_error(param.ident.span, err);
2318 if let GenericParamKind::Lifetime = param.kind {
2319 // Record lifetime res, so lowering knows there is something fishy.
2320 self.record_lifetime_param(param.id, LifetimeRes::Error);
2324 Entry::Vacant(entry) => {
2325 entry.insert(param.ident.span);
2329 if param.ident.name == kw::UnderscoreLifetime {
2330 rustc_errors::struct_span_err!(
2334 "`'_` cannot be used here"
2336 .span_label(param.ident.span, "`'_` is a reserved lifetime name")
2338 // Record lifetime res, so lowering knows there is something fishy.
2339 self.record_lifetime_param(param.id, LifetimeRes::Error);
2343 if param.ident.name == kw::StaticLifetime {
2344 rustc_errors::struct_span_err!(
2348 "invalid lifetime parameter name: `{}`",
2351 .span_label(param.ident.span, "'static is a reserved lifetime name")
2353 // Record lifetime res, so lowering knows there is something fishy.
2354 self.record_lifetime_param(param.id, LifetimeRes::Error);
2358 let def_id = self.r.local_def_id(param.id);
2360 // Plain insert (no renaming).
2361 let (rib, def_kind) = match param.kind {
2362 GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam),
2363 GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam),
2364 GenericParamKind::Lifetime => {
2365 let res = LifetimeRes::Param { param: def_id, binder };
2366 self.record_lifetime_param(param.id, res);
2367 function_lifetime_rib.bindings.insert(ident, (param.id, res));
2372 let res = match kind {
2373 ItemRibKind(..) | AssocItemRibKind => Res::Def(def_kind, def_id.to_def_id()),
2374 NormalRibKind => Res::Err,
2375 _ => span_bug!(param.ident.span, "Unexpected rib kind {:?}", kind),
2377 self.r.record_partial_res(param.id, PartialRes::new(res));
2378 rib.bindings.insert(ident, res);
2381 self.lifetime_ribs.push(function_lifetime_rib);
2382 self.ribs[ValueNS].push(function_value_rib);
2383 self.ribs[TypeNS].push(function_type_rib);
2387 self.ribs[TypeNS].pop();
2388 self.ribs[ValueNS].pop();
2389 let function_lifetime_rib = self.lifetime_ribs.pop().unwrap();
2391 // Do not account for the parameters we just bound for function lifetime elision.
2392 if let Some(ref mut candidates) = self.lifetime_elision_candidates {
2393 for (_, res) in function_lifetime_rib.bindings.values() {
2394 candidates.remove(res);
2398 if let LifetimeBinderKind::BareFnType
2399 | LifetimeBinderKind::WhereBound
2400 | LifetimeBinderKind::Function
2401 | LifetimeBinderKind::ImplBlock = generics_kind
2403 self.maybe_report_lifetime_uses(generics_span, params)
2407 fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) {
2408 self.label_ribs.push(Rib::new(kind));
2410 self.label_ribs.pop();
2413 fn with_static_rib(&mut self, f: impl FnOnce(&mut Self)) {
2414 let kind = ItemRibKind(HasGenericParams::No);
2415 self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
2418 // HACK(min_const_generics,const_evaluatable_unchecked): We
2419 // want to keep allowing `[0; std::mem::size_of::<*mut T>()]`
2420 // with a future compat lint for now. We do this by adding an
2421 // additional special case for repeat expressions.
2423 // Note that we intentionally still forbid `[0; N + 1]` during
2424 // name resolution so that we don't extend the future
2425 // compat lint to new cases.
2426 #[instrument(level = "debug", skip(self, f))]
2427 fn with_constant_rib(
2429 is_repeat: IsRepeatExpr,
2430 may_use_generics: ConstantHasGenerics,
2431 item: Option<(Ident, ConstantItemKind)>,
2432 f: impl FnOnce(&mut Self),
2434 self.with_rib(ValueNS, ConstantItemRibKind(may_use_generics, item), |this| {
2437 ConstantItemRibKind(
2438 may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes),
2442 this.with_label_rib(ConstantItemRibKind(may_use_generics, item), f);
2448 fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T {
2449 // Handle nested impls (inside fn bodies)
2450 let previous_value =
2451 replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone()));
2452 let result = f(self);
2453 self.diagnostic_metadata.current_self_type = previous_value;
2457 fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T {
2458 let previous_value =
2459 replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id));
2460 let result = f(self);
2461 self.diagnostic_metadata.current_self_item = previous_value;
2465 /// When evaluating a `trait` use its associated types' idents for suggestions in E0412.
2466 fn resolve_trait_items(&mut self, trait_items: &'ast [P<AssocItem>]) {
2467 let trait_assoc_items =
2468 replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items));
2470 let walk_assoc_item =
2471 |this: &mut Self, generics: &Generics, kind, item: &'ast AssocItem| {
2472 this.with_generic_param_rib(
2475 LifetimeRibKind::Generics { binder: item.id, span: generics.span, kind },
2476 |this| visit::walk_assoc_item(this, item, AssocCtxt::Trait),
2480 for item in trait_items {
2482 AssocItemKind::Const(_, ty, default) => {
2484 // Only impose the restrictions of `ConstRibKind` for an
2485 // actual constant expression in a provided default.
2486 if let Some(expr) = default {
2487 // We allow arbitrary const expressions inside of associated consts,
2488 // even if they are potentially not const evaluatable.
2490 // Type parameters can already be used and as associated consts are
2491 // not used as part of the type system, this is far less surprising.
2492 self.with_lifetime_rib(
2493 LifetimeRibKind::Elided(LifetimeRes::Infer),
2495 this.with_constant_rib(
2497 ConstantHasGenerics::Yes,
2499 |this| this.visit_expr(expr),
2505 AssocItemKind::Fn(box Fn { generics, .. }) => {
2506 walk_assoc_item(self, generics, LifetimeBinderKind::Function, item);
2508 AssocItemKind::Type(box TyAlias { generics, .. }) => self
2509 .with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2510 walk_assoc_item(this, generics, LifetimeBinderKind::Item, item)
2512 AssocItemKind::MacCall(_) => {
2513 panic!("unexpanded macro in resolve!")
2518 self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items;
2521 /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`).
2522 fn with_optional_trait_ref<T>(
2524 opt_trait_ref: Option<&TraitRef>,
2525 self_type: &'ast Ty,
2526 f: impl FnOnce(&mut Self, Option<DefId>) -> T,
2528 let mut new_val = None;
2529 let mut new_id = None;
2530 if let Some(trait_ref) = opt_trait_ref {
2531 let path: Vec<_> = Segment::from_path(&trait_ref.path);
2532 self.diagnostic_metadata.currently_processing_impl_trait =
2533 Some((trait_ref.clone(), self_type.clone()));
2534 let res = self.smart_resolve_path_fragment(
2537 PathSource::Trait(AliasPossibility::No),
2538 Finalize::new(trait_ref.ref_id, trait_ref.path.span),
2540 self.diagnostic_metadata.currently_processing_impl_trait = None;
2541 if let Some(def_id) = res.expect_full_res().opt_def_id() {
2542 new_id = Some(def_id);
2543 new_val = Some((self.r.expect_module(def_id), trait_ref.clone()));
2546 let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
2547 let result = f(self, new_id);
2548 self.current_trait_ref = original_trait_ref;
2552 fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) {
2553 let mut self_type_rib = Rib::new(NormalRibKind);
2555 // Plain insert (no renaming, since types are not currently hygienic)
2556 self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res);
2557 self.ribs[ns].push(self_type_rib);
2559 self.ribs[ns].pop();
2562 fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) {
2563 self.with_self_rib_ns(TypeNS, self_res, f)
2566 fn resolve_implementation(
2568 generics: &'ast Generics,
2569 opt_trait_reference: &'ast Option<TraitRef>,
2570 self_type: &'ast Ty,
2572 impl_items: &'ast [P<AssocItem>],
2574 debug!("resolve_implementation");
2575 // If applicable, create a rib for the type parameters.
2576 self.with_generic_param_rib(
2578 ItemRibKind(HasGenericParams::Yes(generics.span)),
2579 LifetimeRibKind::Generics {
2580 span: generics.span,
2582 kind: LifetimeBinderKind::ImplBlock,
2585 // Dummy self type for better errors if `Self` is used in the trait path.
2586 this.with_self_rib(Res::SelfTyParam { trait_: LOCAL_CRATE.as_def_id() }, |this| {
2587 this.with_lifetime_rib(
2588 LifetimeRibKind::AnonymousCreateParameter {
2590 report_in_path: true
2593 // Resolve the trait reference, if necessary.
2594 this.with_optional_trait_ref(
2595 opt_trait_reference.as_ref(),
2598 let item_def_id = this.r.local_def_id(item_id);
2600 // Register the trait definitions from here.
2601 if let Some(trait_id) = trait_id {
2609 let item_def_id = item_def_id.to_def_id();
2610 let res = Res::SelfTyAlias {
2611 alias_to: item_def_id,
2612 forbid_generic: false,
2613 is_trait_impl: trait_id.is_some()
2615 this.with_self_rib(res, |this| {
2616 if let Some(trait_ref) = opt_trait_reference.as_ref() {
2617 // Resolve type arguments in the trait path.
2618 visit::walk_trait_ref(this, trait_ref);
2620 // Resolve the self type.
2621 this.visit_ty(self_type);
2622 // Resolve the generic parameters.
2623 this.visit_generics(generics);
2625 // Resolve the items within the impl.
2626 this.with_current_self_type(self_type, |this| {
2627 this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| {
2628 debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)");
2629 let mut seen_trait_items = Default::default();
2630 for item in impl_items {
2631 this.resolve_impl_item(&**item, &mut seen_trait_items);
2645 fn resolve_impl_item(
2647 item: &'ast AssocItem,
2648 seen_trait_items: &mut FxHashMap<DefId, Span>,
2650 use crate::ResolutionError::*;
2652 AssocItemKind::Const(_, ty, default) => {
2653 debug!("resolve_implementation AssocItemKind::Const");
2654 // If this is a trait impl, ensure the const
2656 self.check_trait_item(
2663 |i, s, c| ConstNotMemberOfTrait(i, s, c),
2667 if let Some(expr) = default {
2668 // We allow arbitrary const expressions inside of associated consts,
2669 // even if they are potentially not const evaluatable.
2671 // Type parameters can already be used and as associated consts are
2672 // not used as part of the type system, this is far less surprising.
2673 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2674 this.with_constant_rib(
2676 ConstantHasGenerics::Yes,
2678 |this| this.visit_expr(expr),
2683 AssocItemKind::Fn(box Fn { generics, .. }) => {
2684 debug!("resolve_implementation AssocItemKind::Fn");
2685 // We also need a new scope for the impl item type parameters.
2686 self.with_generic_param_rib(
2689 LifetimeRibKind::Generics {
2691 span: generics.span,
2692 kind: LifetimeBinderKind::Function,
2695 // If this is a trait impl, ensure the method
2697 this.check_trait_item(
2704 |i, s, c| MethodNotMemberOfTrait(i, s, c),
2707 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2711 AssocItemKind::Type(box TyAlias { generics, .. }) => {
2712 debug!("resolve_implementation AssocItemKind::Type");
2713 // We also need a new scope for the impl item type parameters.
2714 self.with_generic_param_rib(
2717 LifetimeRibKind::Generics {
2719 span: generics.span,
2720 kind: LifetimeBinderKind::Item,
2723 this.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| {
2724 // If this is a trait impl, ensure the type
2726 this.check_trait_item(
2733 |i, s, c| TypeNotMemberOfTrait(i, s, c),
2736 visit::walk_assoc_item(this, item, AssocCtxt::Impl)
2741 AssocItemKind::MacCall(_) => {
2742 panic!("unexpanded macro in resolve!")
2747 fn check_trait_item<F>(
2751 kind: &AssocItemKind,
2754 seen_trait_items: &mut FxHashMap<DefId, Span>,
2757 F: FnOnce(Ident, String, Option<Symbol>) -> ResolutionError<'a>,
2759 // If there is a TraitRef in scope for an impl, then the method must be in the trait.
2760 let Some((module, _)) = &self.current_trait_ref else { return; };
2761 ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
2762 let key = self.r.new_key(ident, ns);
2763 let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2765 if binding.is_none() {
2766 // We could not find the trait item in the correct namespace.
2767 // Check the other namespace to report an error.
2773 let key = self.r.new_key(ident, ns);
2774 binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
2777 let Some(binding) = binding else {
2778 // We could not find the method: report an error.
2779 let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
2780 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2781 let path_names = path_names_to_string(path);
2782 self.report_error(span, err(ident, path_names, candidate));
2786 let res = binding.res();
2787 let Res::Def(def_kind, id_in_trait) = res else { bug!() };
2789 match seen_trait_items.entry(id_in_trait) {
2790 Entry::Occupied(entry) => {
2793 ResolutionError::TraitImplDuplicate {
2795 old_span: *entry.get(),
2796 trait_item_span: binding.span,
2801 Entry::Vacant(entry) => {
2806 match (def_kind, kind) {
2807 (DefKind::AssocTy, AssocItemKind::Type(..))
2808 | (DefKind::AssocFn, AssocItemKind::Fn(..))
2809 | (DefKind::AssocConst, AssocItemKind::Const(..)) => {
2810 self.r.record_partial_res(id, PartialRes::new(res));
2816 // The method kind does not correspond to what appeared in the trait, report.
2817 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2818 let (code, kind) = match kind {
2819 AssocItemKind::Const(..) => (rustc_errors::error_code!(E0323), "const"),
2820 AssocItemKind::Fn(..) => (rustc_errors::error_code!(E0324), "method"),
2821 AssocItemKind::Type(..) => (rustc_errors::error_code!(E0325), "type"),
2822 AssocItemKind::MacCall(..) => span_bug!(span, "unexpanded macro"),
2824 let trait_path = path_names_to_string(path);
2827 ResolutionError::TraitImplMismatch {
2832 trait_item_span: binding.span,
2837 fn resolve_params(&mut self, params: &'ast [Param]) {
2838 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2839 self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
2840 for Param { pat, .. } in params {
2841 this.resolve_pattern(pat, PatternSource::FnParam, &mut bindings);
2844 for Param { ty, .. } in params {
2849 fn resolve_local(&mut self, local: &'ast Local) {
2850 debug!("resolving local ({:?})", local);
2851 // Resolve the type.
2852 walk_list!(self, visit_ty, &local.ty);
2854 // Resolve the initializer.
2855 if let Some((init, els)) = local.kind.init_else_opt() {
2856 self.visit_expr(init);
2858 // Resolve the `else` block
2859 if let Some(els) = els {
2860 self.visit_block(els);
2864 // Resolve the pattern.
2865 self.resolve_pattern_top(&local.pat, PatternSource::Let);
2868 /// build a map from pattern identifiers to binding-info's.
2869 /// this is done hygienically. This could arise for a macro
2870 /// that expands into an or-pattern where one 'x' was from the
2871 /// user and one 'x' came from the macro.
2872 fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2873 let mut binding_map = FxHashMap::default();
2875 pat.walk(&mut |pat| {
2877 PatKind::Ident(annotation, ident, ref sub_pat)
2878 if sub_pat.is_some() || self.is_base_res_local(pat.id) =>
2880 binding_map.insert(ident, BindingInfo { span: ident.span, annotation });
2882 PatKind::Or(ref ps) => {
2883 // Check the consistency of this or-pattern and
2884 // then add all bindings to the larger map.
2885 for bm in self.check_consistent_bindings(ps) {
2886 binding_map.extend(bm);
2899 fn is_base_res_local(&self, nid: NodeId) -> bool {
2901 self.r.partial_res_map.get(&nid).map(|res| res.expect_full_res()),
2902 Some(Res::Local(..))
2906 /// Checks that all of the arms in an or-pattern have exactly the
2907 /// same set of bindings, with the same binding modes for each.
2908 fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> {
2909 let mut missing_vars = FxHashMap::default();
2910 let mut inconsistent_vars = FxHashMap::default();
2912 // 1) Compute the binding maps of all arms.
2913 let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>();
2915 // 2) Record any missing bindings or binding mode inconsistencies.
2916 for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) {
2917 // Check against all arms except for the same pattern which is always self-consistent.
2921 .filter(|(_, pat)| pat.id != pat_outer.id)
2922 .flat_map(|(idx, _)| maps[idx].iter())
2923 .map(|(key, binding)| (key.name, map_outer.get(&key), binding));
2925 for (name, info, &binding_inner) in inners {
2928 // The inner binding is missing in the outer.
2930 missing_vars.entry(name).or_insert_with(|| BindingError {
2932 origin: BTreeSet::new(),
2933 target: BTreeSet::new(),
2934 could_be_path: name.as_str().starts_with(char::is_uppercase),
2936 binding_error.origin.insert(binding_inner.span);
2937 binding_error.target.insert(pat_outer.span);
2939 Some(binding_outer) => {
2940 if binding_outer.annotation != binding_inner.annotation {
2941 // The binding modes in the outer and inner bindings differ.
2944 .or_insert((binding_inner.span, binding_outer.span));
2951 // 3) Report all missing variables we found.
2952 let mut missing_vars = missing_vars.into_iter().collect::<Vec<_>>();
2953 missing_vars.sort_by_key(|&(sym, ref _err)| sym);
2955 for (name, mut v) in missing_vars.into_iter() {
2956 if inconsistent_vars.contains_key(&name) {
2957 v.could_be_path = false;
2960 *v.origin.iter().next().unwrap(),
2961 ResolutionError::VariableNotBoundInPattern(v, self.parent_scope),
2965 // 4) Report all inconsistencies in binding modes we found.
2966 let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
2967 inconsistent_vars.sort();
2968 for (name, v) in inconsistent_vars {
2969 self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
2972 // 5) Finally bubble up all the binding maps.
2976 /// Check the consistency of the outermost or-patterns.
2977 fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) {
2978 pat.walk(&mut |pat| match pat.kind {
2979 PatKind::Or(ref ps) => {
2980 self.check_consistent_bindings(ps);
2987 fn resolve_arm(&mut self, arm: &'ast Arm) {
2988 self.with_rib(ValueNS, NormalRibKind, |this| {
2989 this.resolve_pattern_top(&arm.pat, PatternSource::Match);
2990 walk_list!(this, visit_expr, &arm.guard);
2991 this.visit_expr(&arm.body);
2995 /// Arising from `source`, resolve a top level pattern.
2996 fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) {
2997 let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
2998 self.resolve_pattern(pat, pat_src, &mut bindings);
3004 pat_src: PatternSource,
3005 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3007 // We walk the pattern before declaring the pattern's inner bindings,
3008 // so that we avoid resolving a literal expression to a binding defined
3010 visit::walk_pat(self, pat);
3011 self.resolve_pattern_inner(pat, pat_src, bindings);
3012 // This has to happen *after* we determine which pat_idents are variants:
3013 self.check_consistent_bindings_top(pat);
3016 /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`.
3020 /// A stack of sets of bindings accumulated.
3022 /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should
3023 /// be interpreted as re-binding an already bound binding. This results in an error.
3024 /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result
3025 /// in reusing this binding rather than creating a fresh one.
3027 /// When called at the top level, the stack must have a single element
3028 /// with `PatBound::Product`. Otherwise, pushing to the stack happens as
3029 /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs
3030 /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`.
3031 /// When each `p_i` has been dealt with, the top set is merged with its parent.
3032 /// When a whole or-pattern has been dealt with, the thing happens.
3034 /// See the implementation and `fresh_binding` for more details.
3035 fn resolve_pattern_inner(
3038 pat_src: PatternSource,
3039 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3041 // Visit all direct subpatterns of this pattern.
3042 pat.walk(&mut |pat| {
3043 debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
3045 PatKind::Ident(bmode, ident, ref sub) => {
3046 // First try to resolve the identifier as some existing entity,
3047 // then fall back to a fresh binding.
3048 let has_sub = sub.is_some();
3050 .try_resolve_as_non_binding(pat_src, bmode, ident, has_sub)
3051 .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
3052 self.r.record_partial_res(pat.id, PartialRes::new(res));
3053 self.r.record_pat_span(pat.id, pat.span);
3055 PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => {
3056 self.smart_resolve_path(
3060 PathSource::TupleStruct(
3062 self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)),
3066 PatKind::Path(ref qself, ref path) => {
3067 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
3069 PatKind::Struct(ref qself, ref path, ..) => {
3070 self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Struct);
3072 PatKind::Or(ref ps) => {
3073 // Add a new set of bindings to the stack. `Or` here records that when a
3074 // binding already exists in this set, it should not result in an error because
3075 // `V1(a) | V2(a)` must be allowed and are checked for consistency later.
3076 bindings.push((PatBoundCtx::Or, Default::default()));
3078 // Now we need to switch back to a product context so that each
3079 // part of the or-pattern internally rejects already bound names.
3080 // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad.
3081 bindings.push((PatBoundCtx::Product, Default::default()));
3082 self.resolve_pattern_inner(p, pat_src, bindings);
3083 // Move up the non-overlapping bindings to the or-pattern.
3084 // Existing bindings just get "merged".
3085 let collected = bindings.pop().unwrap().1;
3086 bindings.last_mut().unwrap().1.extend(collected);
3088 // This or-pattern itself can itself be part of a product,
3089 // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`.
3090 // Both cases bind `a` again in a product pattern and must be rejected.
3091 let collected = bindings.pop().unwrap().1;
3092 bindings.last_mut().unwrap().1.extend(collected);
3094 // Prevent visiting `ps` as we've already done so above.
3107 pat_src: PatternSource,
3108 bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
3110 // Add the binding to the local ribs, if it doesn't already exist in the bindings map.
3111 // (We must not add it if it's in the bindings map because that breaks the assumptions
3112 // later passes make about or-patterns.)
3113 let ident = ident.normalize_to_macro_rules();
3115 let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident));
3116 // Already bound in a product pattern? e.g. `(a, a)` which is not allowed.
3117 let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product);
3118 // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`.
3119 // This is *required* for consistency which is checked later.
3120 let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or);
3122 if already_bound_and {
3123 // Overlap in a product pattern somewhere; report an error.
3124 use ResolutionError::*;
3125 let error = match pat_src {
3126 // `fn f(a: u8, a: u8)`:
3127 PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList,
3129 _ => IdentifierBoundMoreThanOnceInSamePattern,
3131 self.report_error(ident.span, error(ident.name));
3134 // Record as bound if it's valid:
3135 let ident_valid = ident.name != kw::Empty;
3137 bindings.last_mut().unwrap().1.insert(ident);
3140 if already_bound_or {
3141 // `Variant1(a) | Variant2(a)`, ok
3142 // Reuse definition from the first `a`.
3143 self.innermost_rib_bindings(ValueNS)[&ident]
3145 let res = Res::Local(pat_id);
3147 // A completely fresh binding add to the set if it's valid.
3148 self.innermost_rib_bindings(ValueNS).insert(ident, res);
3154 fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> {
3155 &mut self.ribs[ns].last_mut().unwrap().bindings
3158 fn try_resolve_as_non_binding(
3160 pat_src: PatternSource,
3161 ann: BindingAnnotation,
3165 // An immutable (no `mut`) by-value (no `ref`) binding pattern without
3166 // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could
3167 // also be interpreted as a path to e.g. a constant, variant, etc.
3168 let is_syntactic_ambiguity = !has_sub && ann == BindingAnnotation::NONE;
3170 let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?;
3171 let (res, binding) = match ls_binding {
3172 LexicalScopeBinding::Item(binding)
3173 if is_syntactic_ambiguity && binding.is_ambiguity() =>
3175 // For ambiguous bindings we don't know all their definitions and cannot check
3176 // whether they can be shadowed by fresh bindings or not, so force an error.
3177 // issues/33118#issuecomment-233962221 (see below) still applies here,
3178 // but we have to ignore it for backward compatibility.
3179 self.r.record_use(ident, binding, false);
3182 LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
3183 LexicalScopeBinding::Res(res) => (res, None),
3187 Res::SelfCtor(_) // See #70549.
3189 DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam,
3191 ) if is_syntactic_ambiguity => {
3192 // Disambiguate in favor of a unit struct/variant or constant pattern.
3193 if let Some(binding) = binding {
3194 self.r.record_use(ident, binding, false);
3198 Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static(_), _) => {
3199 // This is unambiguously a fresh binding, either syntactically
3200 // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves
3201 // to something unusable as a pattern (e.g., constructor function),
3202 // but we still conservatively report an error, see
3203 // issues/33118#issuecomment-233962221 for one reason why.
3204 let binding = binding.expect("no binding for a ctor or static");
3207 ResolutionError::BindingShadowsSomethingUnacceptable {
3208 shadowing_binding: pat_src,
3210 participle: if binding.is_import() { "imported" } else { "defined" },
3211 article: binding.res().article(),
3212 shadowed_binding: binding.res(),
3213 shadowed_binding_span: binding.span,
3218 Res::Def(DefKind::ConstParam, def_id) => {
3219 // Same as for DefKind::Const above, but here, `binding` is `None`, so we
3220 // have to construct the error differently
3223 ResolutionError::BindingShadowsSomethingUnacceptable {
3224 shadowing_binding: pat_src,
3226 participle: "defined",
3227 article: res.article(),
3228 shadowed_binding: res,
3229 shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"),
3234 Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => {
3235 // These entities are explicitly allowed to be shadowed by fresh bindings.
3238 Res::SelfCtor(_) => {
3239 // We resolve `Self` in pattern position as an ident sometimes during recovery,
3240 // so delay a bug instead of ICEing.
3241 self.r.session.delay_span_bug(
3243 "unexpected `SelfCtor` in pattern, expected identifier"
3249 "unexpected resolution for an identifier in pattern: {:?}",
3255 // High-level and context dependent path resolution routine.
3256 // Resolves the path and records the resolution into definition map.
3257 // If resolution fails tries several techniques to find likely
3258 // resolution candidates, suggest imports or other help, and report
3259 // errors in user friendly way.
3260 fn smart_resolve_path(
3263 qself: Option<&QSelf>,
3265 source: PathSource<'ast>,
3267 self.smart_resolve_path_fragment(
3269 &Segment::from_path(path),
3271 Finalize::new(id, path.span),
3275 fn smart_resolve_path_fragment(
3277 qself: Option<&QSelf>,
3279 source: PathSource<'ast>,
3283 "smart_resolve_path_fragment(qself={:?}, path={:?}, finalize={:?})",
3284 qself, path, finalize,
3286 let ns = source.namespace();
3288 let Finalize { node_id, path_span, .. } = finalize;
3289 let report_errors = |this: &mut Self, res: Option<Res>| {
3290 if this.should_report_errs() {
3291 let (err, candidates) =
3292 this.smart_resolve_report_errors(path, path_span, source, res);
3294 let def_id = this.parent_scope.module.nearest_parent_mod();
3295 let instead = res.is_some();
3297 if res.is_none() { this.report_missing_type_error(path) } else { None };
3299 this.r.use_injections.push(UseError {
3306 is_call: source.is_call(),
3310 PartialRes::new(Res::Err)
3313 // For paths originating from calls (like in `HashMap::new()`), tries
3314 // to enrich the plain `failed to resolve: ...` message with hints
3315 // about possible missing imports.
3317 // Similar thing, for types, happens in `report_errors` above.
3318 let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| {
3319 if !source.is_call() {
3320 return Some(parent_err);
3323 // Before we start looking for candidates, we have to get our hands
3324 // on the type user is trying to perform invocation on; basically:
3325 // we're transforming `HashMap::new` into just `HashMap`.
3326 let path = match path.split_last() {
3327 Some((_, path)) if !path.is_empty() => path,
3328 _ => return Some(parent_err),
3331 let (mut err, candidates) =
3332 this.smart_resolve_report_errors(path, path_span, PathSource::Type, None);
3334 if candidates.is_empty() {
3336 return Some(parent_err);
3339 // There are two different error messages user might receive at
3341 // - E0412 cannot find type `{}` in this scope
3342 // - E0433 failed to resolve: use of undeclared type or module `{}`
3344 // The first one is emitted for paths in type-position, and the
3345 // latter one - for paths in expression-position.
3347 // Thus (since we're in expression-position at this point), not to
3348 // confuse the user, we want to keep the *message* from E0432 (so
3349 // `parent_err`), but we want *hints* from E0412 (so `err`).
3351 // And that's what happens below - we're just mixing both messages
3352 // into a single one.
3353 let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
3355 err.message = take(&mut parent_err.message);
3356 err.code = take(&mut parent_err.code);
3357 err.children = take(&mut parent_err.children);
3359 parent_err.cancel();
3361 let def_id = this.parent_scope.module.nearest_parent_mod();
3363 if this.should_report_errs() {
3364 this.r.use_injections.push(UseError {
3371 is_call: source.is_call(),
3377 // We don't return `Some(parent_err)` here, because the error will
3378 // be already printed as part of the `use` injections
3382 let partial_res = match self.resolve_qpath_anywhere(
3387 source.defer_to_typeck(),
3390 Ok(Some(partial_res)) if let Some(res) = partial_res.full_res() => {
3391 if source.is_expected(res) || res == Res::Err {
3394 report_errors(self, Some(res))
3398 Ok(Some(partial_res)) if source.defer_to_typeck() => {
3399 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
3400 // or `<T>::A::B`. If `B` should be resolved in value namespace then
3401 // it needs to be added to the trait map.
3403 let item_name = path.last().unwrap().ident;
3404 let traits = self.traits_in_scope(item_name, ns);
3405 self.r.trait_map.insert(node_id, traits);
3408 if PrimTy::from_name(path[0].ident.name).is_some() {
3409 let mut std_path = Vec::with_capacity(1 + path.len());
3411 std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std)));
3412 std_path.extend(path);
3413 if let PathResult::Module(_) | PathResult::NonModule(_) =
3414 self.resolve_path(&std_path, Some(ns), None)
3416 // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8`
3418 path.iter().last().map_or(path_span, |segment| segment.ident.span);
3420 self.r.confused_type_with_std_module.insert(item_span, path_span);
3421 self.r.confused_type_with_std_module.insert(path_span, path_span);
3429 if let Some(err) = report_errors_for_call(self, err) {
3430 self.report_error(err.span, err.node);
3433 PartialRes::new(Res::Err)
3436 _ => report_errors(self, None),
3439 if !matches!(source, PathSource::TraitItem(..)) {
3440 // Avoid recording definition of `A::B` in `<T as A>::B::C`.
3441 self.r.record_partial_res(node_id, partial_res);
3442 self.resolve_elided_lifetimes_in_path(node_id, partial_res, path, source, path_span);
3448 fn self_type_is_available(&mut self) -> bool {
3450 .maybe_resolve_ident_in_lexical_scope(Ident::with_dummy_span(kw::SelfUpper), TypeNS);
3451 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3454 fn self_value_is_available(&mut self, self_span: Span) -> bool {
3455 let ident = Ident::new(kw::SelfLower, self_span);
3456 let binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS);
3457 if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false }
3460 /// A wrapper around [`Resolver::report_error`].
3462 /// This doesn't emit errors for function bodies if this is rustdoc.
3463 fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) {
3464 if self.should_report_errs() {
3465 self.r.report_error(span, resolution_error);
3470 /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items.
3471 fn should_report_errs(&self) -> bool {
3472 !(self.r.session.opts.actually_rustdoc && self.in_func_body)
3475 // Resolve in alternative namespaces if resolution in the primary namespace fails.
3476 fn resolve_qpath_anywhere(
3478 qself: Option<&QSelf>,
3480 primary_ns: Namespace,
3482 defer_to_typeck: bool,
3484 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3485 let mut fin_res = None;
3487 for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() {
3488 if i == 0 || ns != primary_ns {
3489 match self.resolve_qpath(qself, path, ns, finalize)? {
3491 if partial_res.unresolved_segments() == 0 || defer_to_typeck =>
3493 return Ok(Some(partial_res));
3496 if fin_res.is_none() {
3497 fin_res = partial_res;
3504 assert!(primary_ns != MacroNS);
3506 if qself.is_none() {
3507 let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
3508 let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
3509 if let Ok((_, res)) =
3510 self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false)
3512 return Ok(Some(PartialRes::new(res)));
3519 /// Handles paths that may refer to associated items.
3522 qself: Option<&QSelf>,
3526 ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> {
3528 "resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})",
3529 qself, path, ns, finalize,
3532 if let Some(qself) = qself {
3533 if qself.position == 0 {
3534 // This is a case like `<T>::B`, where there is no
3535 // trait to resolve. In that case, we leave the `B`
3536 // segment to be resolved by type-check.
3537 return Ok(Some(PartialRes::with_unresolved_segments(
3538 Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()),
3543 // Make sure `A::B` in `<T as A::B>::C` is a trait item.
3545 // Currently, `path` names the full item (`A::B::C`, in
3546 // our example). so we extract the prefix of that that is
3547 // the trait (the slice upto and including
3548 // `qself.position`). And then we recursively resolve that,
3549 // but with `qself` set to `None`.
3550 let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
3551 let partial_res = self.smart_resolve_path_fragment(
3553 &path[..=qself.position],
3554 PathSource::TraitItem(ns),
3555 Finalize::with_root_span(finalize.node_id, finalize.path_span, qself.path_span),
3558 // The remaining segments (the `C` in our example) will
3559 // have to be resolved by type-check, since that requires doing
3560 // trait resolution.
3561 return Ok(Some(PartialRes::with_unresolved_segments(
3562 partial_res.base_res(),
3563 partial_res.unresolved_segments() + path.len() - qself.position - 1,
3567 let result = match self.resolve_path(&path, Some(ns), Some(finalize)) {
3568 PathResult::NonModule(path_res) => path_res,
3569 PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => {
3570 PartialRes::new(module.res().unwrap())
3572 // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
3573 // don't report an error right away, but try to fallback to a primitive type.
3574 // So, we are still able to successfully resolve something like
3576 // use std::u8; // bring module u8 in scope
3577 // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
3578 // u8::max_value() // OK, resolves to associated function <u8>::max_value,
3579 // // not to non-existent std::u8::max_value
3582 // Such behavior is required for backward compatibility.
3583 // The same fallback is used when `a` resolves to nothing.
3584 PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. }
3585 if (ns == TypeNS || path.len() > 1)
3586 && PrimTy::from_name(path[0].ident.name).is_some() =>
3588 let prim = PrimTy::from_name(path[0].ident.name).unwrap();
3589 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
3591 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3592 PartialRes::new(module.res().unwrap())
3594 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
3595 return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion }));
3597 PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None),
3598 PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"),
3602 && let Some(res) = result.full_res()
3604 && path[0].ident.name != kw::PathRoot
3605 && path[0].ident.name != kw::DollarCrate
3607 let unqualified_result = {
3608 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
3609 PathResult::NonModule(path_res) => path_res.expect_full_res(),
3610 PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
3611 module.res().unwrap()
3613 _ => return Ok(Some(result)),
3616 if res == unqualified_result {
3617 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
3618 self.r.lint_buffer.buffer_lint(
3622 "unnecessary qualification",
3630 fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) {
3631 if let Some(label) = label {
3632 if label.ident.as_str().as_bytes()[1] != b'_' {
3633 self.diagnostic_metadata.unused_labels.insert(id, label.ident.span);
3636 if let Ok((_, orig_span)) = self.resolve_label(label.ident) {
3637 diagnostics::signal_label_shadowing(self.r.session, orig_span, label.ident)
3640 self.with_label_rib(NormalRibKind, |this| {
3641 let ident = label.ident.normalize_to_macro_rules();
3642 this.label_ribs.last_mut().unwrap().bindings.insert(ident, id);
3650 fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) {
3651 self.with_resolved_label(label, id, |this| this.visit_block(block));
3654 fn resolve_block(&mut self, block: &'ast Block) {
3655 debug!("(resolving block) entering block");
3656 // Move down in the graph, if there's an anonymous module rooted here.
3657 let orig_module = self.parent_scope.module;
3658 let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
3660 let mut num_macro_definition_ribs = 0;
3661 if let Some(anonymous_module) = anonymous_module {
3662 debug!("(resolving block) found anonymous module, moving down");
3663 self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3664 self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
3665 self.parent_scope.module = anonymous_module;
3667 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3670 let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take();
3671 if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) =
3672 (block.could_be_bare_literal, &block.stmts[..])
3673 && let ExprKind::Type(..) = expr.kind
3675 self.diagnostic_metadata.current_block_could_be_bare_struct_literal =
3678 // Descend into the block.
3679 for stmt in &block.stmts {
3680 if let StmtKind::Item(ref item) = stmt.kind
3681 && let ItemKind::MacroDef(..) = item.kind {
3682 num_macro_definition_ribs += 1;
3683 let res = self.r.local_def_id(item.id).to_def_id();
3684 self.ribs[ValueNS].push(Rib::new(MacroDefinition(res)));
3685 self.label_ribs.push(Rib::new(MacroDefinition(res)));
3688 self.visit_stmt(stmt);
3690 self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev;
3693 self.parent_scope.module = orig_module;
3694 for _ in 0..num_macro_definition_ribs {
3695 self.ribs[ValueNS].pop();
3696 self.label_ribs.pop();
3698 self.ribs[ValueNS].pop();
3699 if anonymous_module.is_some() {
3700 self.ribs[TypeNS].pop();
3702 debug!("(resolving block) leaving block");
3705 fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) {
3706 debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat);
3707 self.with_constant_rib(
3709 if constant.value.is_potential_trivial_const_param() {
3710 ConstantHasGenerics::Yes
3712 ConstantHasGenerics::No
3715 |this| visit::walk_anon_const(this, constant),
3719 fn resolve_inline_const(&mut self, constant: &'ast AnonConst) {
3720 debug!("resolve_anon_const {constant:?}");
3721 self.with_constant_rib(IsRepeatExpr::No, ConstantHasGenerics::Yes, None, |this| {
3722 visit::walk_anon_const(this, constant)
3726 fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
3727 // First, record candidate traits for this expression if it could
3728 // result in the invocation of a method call.
3730 self.record_candidate_traits_for_expr_if_necessary(expr);
3732 // Next, resolve the node.
3734 ExprKind::Path(ref qself, ref path) => {
3735 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
3736 visit::walk_expr(self, expr);
3739 ExprKind::Struct(ref se) => {
3740 self.smart_resolve_path(expr.id, se.qself.as_ref(), &se.path, PathSource::Struct);
3741 visit::walk_expr(self, expr);
3744 ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
3745 match self.resolve_label(label.ident) {
3746 Ok((node_id, _)) => {
3747 // Since this res is a label, it is never read.
3748 self.r.label_res_map.insert(expr.id, node_id);
3749 self.diagnostic_metadata.unused_labels.remove(&node_id);
3752 self.report_error(label.ident.span, error);
3756 // visit `break` argument if any
3757 visit::walk_expr(self, expr);
3760 ExprKind::Break(None, Some(ref e)) => {
3761 // We use this instead of `visit::walk_expr` to keep the parent expr around for
3762 // better diagnostics.
3763 self.resolve_expr(e, Some(&expr));
3766 ExprKind::Let(ref pat, ref scrutinee, _) => {
3767 self.visit_expr(scrutinee);
3768 self.resolve_pattern_top(pat, PatternSource::Let);
3771 ExprKind::If(ref cond, ref then, ref opt_else) => {
3772 self.with_rib(ValueNS, NormalRibKind, |this| {
3773 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3774 this.visit_expr(cond);
3775 this.diagnostic_metadata.in_if_condition = old;
3776 this.visit_block(then);
3778 if let Some(expr) = opt_else {
3779 self.visit_expr(expr);
3783 ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3785 ExprKind::While(ref cond, ref block, label) => {
3786 self.with_resolved_label(label, expr.id, |this| {
3787 this.with_rib(ValueNS, NormalRibKind, |this| {
3788 let old = this.diagnostic_metadata.in_if_condition.replace(cond);
3789 this.visit_expr(cond);
3790 this.diagnostic_metadata.in_if_condition = old;
3791 this.visit_block(block);
3796 ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => {
3797 self.visit_expr(iter_expr);
3798 self.with_rib(ValueNS, NormalRibKind, |this| {
3799 this.resolve_pattern_top(pat, PatternSource::For);
3800 this.resolve_labeled_block(label, expr.id, block);
3804 ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block),
3806 // Equivalent to `visit::walk_expr` + passing some context to children.
3807 ExprKind::Field(ref subexpression, _) => {
3808 self.resolve_expr(subexpression, Some(expr));
3810 ExprKind::MethodCall(ref segment, ref receiver, ref arguments, _) => {
3811 self.resolve_expr(receiver, Some(expr));
3812 for argument in arguments {
3813 self.resolve_expr(argument, None);
3815 self.visit_path_segment(segment);
3818 ExprKind::Call(ref callee, ref arguments) => {
3819 self.resolve_expr(callee, Some(expr));
3820 let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default();
3821 for (idx, argument) in arguments.iter().enumerate() {
3822 // Constant arguments need to be treated as AnonConst since
3823 // that is how they will be later lowered to HIR.
3824 if const_args.contains(&idx) {
3825 self.with_constant_rib(
3827 if argument.is_potential_trivial_const_param() {
3828 ConstantHasGenerics::Yes
3830 ConstantHasGenerics::No
3834 this.resolve_expr(argument, None);
3838 self.resolve_expr(argument, None);
3842 ExprKind::Type(ref type_expr, ref ty) => {
3843 // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in
3844 // type ascription. Here we are trying to retrieve the span of the colon token as
3845 // well, but only if it's written without spaces `expr:Ty` and therefore confusable
3846 // with `expr::Ty`, only in this case it will match the span from
3847 // `type_ascription_path_suggestions`.
3848 self.diagnostic_metadata
3849 .current_type_ascription
3850 .push(type_expr.span.between(ty.span));
3851 visit::walk_expr(self, expr);
3852 self.diagnostic_metadata.current_type_ascription.pop();
3854 // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to
3855 // resolve the arguments within the proper scopes so that usages of them inside the
3856 // closure are detected as upvars rather than normal closure arg usages.
3857 ExprKind::Closure(_, _, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => {
3858 self.with_rib(ValueNS, NormalRibKind, |this| {
3859 this.with_label_rib(ClosureOrAsyncRibKind, |this| {
3860 // Resolve arguments:
3861 this.resolve_params(&fn_decl.inputs);
3862 // No need to resolve return type --
3863 // the outer closure return type is `FnRetTy::Default`.
3865 // Now resolve the inner closure
3867 // No need to resolve arguments: the inner closure has none.
3868 // Resolve the return type:
3869 visit::walk_fn_ret_ty(this, &fn_decl.output);
3871 this.visit_expr(body);
3876 // For closures, ClosureOrAsyncRibKind is added in visit_fn
3877 ExprKind::Closure(ClosureBinder::For { ref generic_params, span }, ..) => {
3878 self.with_generic_param_rib(
3881 LifetimeRibKind::Generics {
3883 kind: LifetimeBinderKind::Closure,
3886 |this| visit::walk_expr(this, expr),
3889 ExprKind::Closure(..) => visit::walk_expr(self, expr),
3890 ExprKind::Async(..) => {
3891 self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr));
3893 ExprKind::Repeat(ref elem, ref ct) => {
3894 self.visit_expr(elem);
3895 self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| {
3896 this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
3897 this.resolve_anon_const(ct, IsRepeatExpr::Yes)
3901 ExprKind::ConstBlock(ref ct) => {
3902 self.resolve_inline_const(ct);
3904 ExprKind::Index(ref elem, ref idx) => {
3905 self.resolve_expr(elem, Some(expr));
3906 self.visit_expr(idx);
3909 visit::walk_expr(self, expr);
3914 fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) {
3916 ExprKind::Field(_, ident) => {
3917 // FIXME(#6890): Even though you can't treat a method like a
3918 // field, we need to add any trait methods we find that match
3919 // the field name so that we can do some nice error reporting
3920 // later on in typeck.
3921 let traits = self.traits_in_scope(ident, ValueNS);
3922 self.r.trait_map.insert(expr.id, traits);
3924 ExprKind::MethodCall(ref segment, ..) => {
3925 debug!("(recording candidate traits for expr) recording traits for {}", expr.id);
3926 let traits = self.traits_in_scope(segment.ident, ValueNS);
3927 self.r.trait_map.insert(expr.id, traits);
3935 fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> {
3936 self.r.traits_in_scope(
3937 self.current_trait_ref.as_ref().map(|(module, _)| *module),
3940 Some((ident.name, ns)),
3944 /// Construct the list of in-scope lifetime parameters for async lowering.
3945 /// We include all lifetime parameters, either named or "Fresh".
3946 /// The order of those parameters does not matter, as long as it is
3948 fn record_lifetime_params_for_async(
3951 async_node_id: Option<(NodeId, Span)>,
3953 if let Some((async_node_id, span)) = async_node_id {
3954 let mut extra_lifetime_params =
3955 self.r.extra_lifetime_params_map.get(&fn_id).cloned().unwrap_or_default();
3956 for rib in self.lifetime_ribs.iter().rev() {
3957 extra_lifetime_params.extend(
3958 rib.bindings.iter().map(|(&ident, &(node_id, res))| (ident, node_id, res)),
3961 LifetimeRibKind::Item => break,
3962 LifetimeRibKind::AnonymousCreateParameter { binder, .. } => {
3963 if let Some(earlier_fresh) = self.r.extra_lifetime_params_map.get(&binder) {
3964 extra_lifetime_params.extend(earlier_fresh);
3967 LifetimeRibKind::Generics { .. } => {}
3969 // We are in a function definition. We should only find `Generics`
3970 // and `AnonymousCreateParameter` inside the innermost `Item`.
3971 span_bug!(span, "unexpected rib kind: {:?}", rib.kind)
3975 self.r.extra_lifetime_params_map.insert(async_node_id, extra_lifetime_params);
3980 struct LifetimeCountVisitor<'a, 'b> {
3981 r: &'b mut Resolver<'a>,
3984 /// Walks the whole crate in DFS order, visiting each item, counting the declared number of
3985 /// lifetime generic parameters.
3986 impl<'ast> Visitor<'ast> for LifetimeCountVisitor<'_, '_> {
3987 fn visit_item(&mut self, item: &'ast Item) {
3989 ItemKind::TyAlias(box TyAlias { ref generics, .. })
3990 | ItemKind::Fn(box Fn { ref generics, .. })
3991 | ItemKind::Enum(_, ref generics)
3992 | ItemKind::Struct(_, ref generics)
3993 | ItemKind::Union(_, ref generics)
3994 | ItemKind::Impl(box Impl { ref generics, .. })
3995 | ItemKind::Trait(box Trait { ref generics, .. })
3996 | ItemKind::TraitAlias(ref generics, _) => {
3997 let def_id = self.r.local_def_id(item.id);
3998 let count = generics
4001 .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
4003 self.r.item_generics_num_lifetimes.insert(def_id, count);
4007 | ItemKind::ForeignMod(..)
4008 | ItemKind::Static(..)
4009 | ItemKind::Const(..)
4011 | ItemKind::ExternCrate(..)
4012 | ItemKind::MacroDef(..)
4013 | ItemKind::GlobalAsm(..)
4014 | ItemKind::MacCall(..) => {}
4016 visit::walk_item(self, item)
4020 impl<'a> Resolver<'a> {
4021 pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) {
4022 visit::walk_crate(&mut LifetimeCountVisitor { r: self }, krate);
4023 let mut late_resolution_visitor = LateResolutionVisitor::new(self);
4024 visit::walk_crate(&mut late_resolution_visitor, krate);
4025 for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() {
4026 self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label");