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Diffstat (limited to 'compiler/rustc_resolve/src/late.rs')
| -rw-r--r-- | compiler/rustc_resolve/src/late.rs | 3984 |
1 files changed, 3984 insertions, 0 deletions
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs new file mode 100644 index 000000000..dea3eaecd --- /dev/null +++ b/compiler/rustc_resolve/src/late.rs @@ -0,0 +1,3984 @@ +// ignore-tidy-filelength +//! "Late resolution" is the pass that resolves most of names in a crate beside imports and macros. +//! It runs when the crate is fully expanded and its module structure is fully built. +//! So it just walks through the crate and resolves all the expressions, types, etc. +//! +//! If you wonder why there's no `early.rs`, that's because it's split into three files - +//! `build_reduced_graph.rs`, `macros.rs` and `imports.rs`. + +use RibKind::*; + +use crate::{path_names_to_string, BindingError, Finalize, LexicalScopeBinding}; +use crate::{Module, ModuleOrUniformRoot, NameBinding, ParentScope, PathResult}; +use crate::{ResolutionError, Resolver, Segment, UseError}; + +use rustc_ast::ptr::P; +use rustc_ast::visit::{self, AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor}; +use rustc_ast::*; +use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap}; +use rustc_errors::DiagnosticId; +use rustc_hir::def::Namespace::{self, *}; +use rustc_hir::def::{self, CtorKind, DefKind, LifetimeRes, PartialRes, PerNS}; +use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID}; +use rustc_hir::{PrimTy, TraitCandidate}; +use rustc_middle::middle::resolve_lifetime::Set1; +use rustc_middle::ty::DefIdTree; +use rustc_middle::{bug, span_bug}; +use rustc_session::lint; +use rustc_span::symbol::{kw, sym, Ident, Symbol}; +use rustc_span::{BytePos, Span}; +use smallvec::{smallvec, SmallVec}; + +use rustc_span::source_map::{respan, Spanned}; +use std::collections::{hash_map::Entry, BTreeSet}; +use std::mem::{replace, take}; +use tracing::debug; + +mod diagnostics; +pub(crate) mod lifetimes; + +type Res = def::Res<NodeId>; + +type IdentMap<T> = FxHashMap<Ident, T>; + +/// Map from the name in a pattern to its binding mode. +type BindingMap = IdentMap<BindingInfo>; + +use diagnostics::{ + ElisionFnParameter, LifetimeElisionCandidate, MissingLifetime, MissingLifetimeKind, +}; + +#[derive(Copy, Clone, Debug)] +struct BindingInfo { + span: Span, + binding_mode: BindingMode, +} + +#[derive(Copy, Clone, PartialEq, Eq, Debug)] +pub enum PatternSource { + Match, + Let, + For, + FnParam, +} + +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +enum IsRepeatExpr { + No, + Yes, +} + +impl PatternSource { + pub fn descr(self) -> &'static str { + match self { + PatternSource::Match => "match binding", + PatternSource::Let => "let binding", + PatternSource::For => "for binding", + PatternSource::FnParam => "function parameter", + } + } +} + +/// Denotes whether the context for the set of already bound bindings is a `Product` +/// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`. +/// See those functions for more information. +#[derive(PartialEq)] +enum PatBoundCtx { + /// A product pattern context, e.g., `Variant(a, b)`. + Product, + /// An or-pattern context, e.g., `p_0 | ... | p_n`. + Or, +} + +/// Does this the item (from the item rib scope) allow generic parameters? +#[derive(Copy, Clone, Debug, Eq, PartialEq)] +pub(crate) enum HasGenericParams { + Yes, + No, +} + +impl HasGenericParams { + fn force_yes_if(self, b: bool) -> Self { + if b { Self::Yes } else { self } + } +} + +#[derive(Copy, Clone, Debug, Eq, PartialEq)] +pub(crate) enum ConstantItemKind { + Const, + Static, +} + +/// The rib kind restricts certain accesses, +/// e.g. to a `Res::Local` of an outer item. +#[derive(Copy, Clone, Debug)] +pub(crate) enum RibKind<'a> { + /// No restriction needs to be applied. + NormalRibKind, + + /// We passed through an impl or trait and are now in one of its + /// methods or associated types. Allow references to ty params that impl or trait + /// binds. Disallow any other upvars (including other ty params that are + /// upvars). + AssocItemRibKind, + + /// We passed through a closure. Disallow labels. + ClosureOrAsyncRibKind, + + /// We passed through a function definition. Disallow upvars. + /// Permit only those const parameters that are specified in the function's generics. + FnItemRibKind, + + /// We passed through an item scope. Disallow upvars. + ItemRibKind(HasGenericParams), + + /// We're in a constant item. Can't refer to dynamic stuff. + /// + /// The item may reference generic parameters in trivial constant expressions. + /// All other constants aren't allowed to use generic params at all. + ConstantItemRibKind(HasGenericParams, Option<(Ident, ConstantItemKind)>), + + /// We passed through a module. + ModuleRibKind(Module<'a>), + + /// We passed through a `macro_rules!` statement + MacroDefinition(DefId), + + /// All bindings in this rib are generic parameters that can't be used + /// from the default of a generic parameter because they're not declared + /// before said generic parameter. Also see the `visit_generics` override. + ForwardGenericParamBanRibKind, + + /// We are inside of the type of a const parameter. Can't refer to any + /// parameters. + ConstParamTyRibKind, + + /// We are inside a `sym` inline assembly operand. Can only refer to + /// globals. + InlineAsmSymRibKind, +} + +impl RibKind<'_> { + /// Whether this rib kind contains generic parameters, as opposed to local + /// variables. + pub(crate) fn contains_params(&self) -> bool { + match self { + NormalRibKind + | ClosureOrAsyncRibKind + | FnItemRibKind + | ConstantItemRibKind(..) + | ModuleRibKind(_) + | MacroDefinition(_) + | ConstParamTyRibKind + | InlineAsmSymRibKind => false, + AssocItemRibKind | ItemRibKind(_) | ForwardGenericParamBanRibKind => true, + } + } + + /// This rib forbids referring to labels defined in upwards ribs. + fn is_label_barrier(self) -> bool { + match self { + NormalRibKind | MacroDefinition(..) => false, + + AssocItemRibKind + | ClosureOrAsyncRibKind + | FnItemRibKind + | ItemRibKind(..) + | ConstantItemRibKind(..) + | ModuleRibKind(..) + | ForwardGenericParamBanRibKind + | ConstParamTyRibKind + | InlineAsmSymRibKind => true, + } + } +} + +/// A single local scope. +/// +/// A rib represents a scope names can live in. Note that these appear in many places, not just +/// around braces. At any place where the list of accessible names (of the given namespace) +/// changes or a new restrictions on the name accessibility are introduced, a new rib is put onto a +/// stack. This may be, for example, a `let` statement (because it introduces variables), a macro, +/// etc. +/// +/// Different [rib kinds](enum@RibKind) are transparent for different names. +/// +/// The resolution keeps a separate stack of ribs as it traverses the AST for each namespace. When +/// resolving, the name is looked up from inside out. +#[derive(Debug)] +pub(crate) struct Rib<'a, R = Res> { + pub bindings: IdentMap<R>, + pub kind: RibKind<'a>, +} + +impl<'a, R> Rib<'a, R> { + fn new(kind: RibKind<'a>) -> Rib<'a, R> { + Rib { bindings: Default::default(), kind } + } +} + +#[derive(Clone, Copy, Debug)] +enum LifetimeUseSet { + One { use_span: Span, use_ctxt: visit::LifetimeCtxt }, + Many, +} + +#[derive(Copy, Clone, Debug)] +enum LifetimeRibKind { + /// This rib acts as a barrier to forbid reference to lifetimes of a parent item. + Item, + + /// This rib declares generic parameters. + Generics { binder: NodeId, span: Span, kind: LifetimeBinderKind }, + + /// FIXME(const_generics): This patches over an ICE caused by non-'static lifetimes in const + /// generics. We are disallowing this until we can decide on how we want to handle non-'static + /// lifetimes in const generics. See issue #74052 for discussion. + ConstGeneric, + + /// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`. + /// This function will emit an error if `generic_const_exprs` is not enabled, the body identified by + /// `body_id` is an anonymous constant and `lifetime_ref` is non-static. + AnonConst, + + /// Create a new anonymous lifetime parameter and reference it. + /// + /// If `report_in_path`, report an error when encountering lifetime elision in a path: + /// ```compile_fail + /// struct Foo<'a> { x: &'a () } + /// async fn foo(x: Foo) {} + /// ``` + /// + /// Note: the error should not trigger when the elided lifetime is in a pattern or + /// expression-position path: + /// ``` + /// struct Foo<'a> { x: &'a () } + /// async fn foo(Foo { x: _ }: Foo<'_>) {} + /// ``` + AnonymousCreateParameter { binder: NodeId, report_in_path: bool }, + + /// Give a hard error when either `&` or `'_` is written. Used to + /// rule out things like `where T: Foo<'_>`. Does not imply an + /// error on default object bounds (e.g., `Box<dyn Foo>`). + AnonymousReportError, + + /// Replace all anonymous lifetimes by provided lifetime. + Elided(LifetimeRes), + + /// Signal we cannot find which should be the anonymous lifetime. + ElisionFailure, +} + +#[derive(Copy, Clone, Debug)] +enum LifetimeBinderKind { + BareFnType, + PolyTrait, + WhereBound, + Item, + Function, + Closure, + ImplBlock, +} + +impl LifetimeBinderKind { + fn descr(self) -> &'static str { + use LifetimeBinderKind::*; + match self { + BareFnType => "type", + PolyTrait => "bound", + WhereBound => "bound", + Item => "item", + ImplBlock => "impl block", + Function => "function", + Closure => "closure", + } + } +} + +#[derive(Debug)] +struct LifetimeRib { + kind: LifetimeRibKind, + // We need to preserve insertion order for async fns. + bindings: FxIndexMap<Ident, (NodeId, LifetimeRes)>, +} + +impl LifetimeRib { + fn new(kind: LifetimeRibKind) -> LifetimeRib { + LifetimeRib { bindings: Default::default(), kind } + } +} + +#[derive(Copy, Clone, PartialEq, Eq, Debug)] +pub(crate) enum AliasPossibility { + No, + Maybe, +} + +#[derive(Copy, Clone, Debug)] +pub(crate) enum PathSource<'a> { + // Type paths `Path`. + Type, + // Trait paths in bounds or impls. + Trait(AliasPossibility), + // Expression paths `path`, with optional parent context. + Expr(Option<&'a Expr>), + // Paths in path patterns `Path`. + Pat, + // Paths in struct expressions and patterns `Path { .. }`. + Struct, + // Paths in tuple struct patterns `Path(..)`. + TupleStruct(Span, &'a [Span]), + // `m::A::B` in `<T as m::A>::B::C`. + TraitItem(Namespace), +} + +impl<'a> PathSource<'a> { + fn namespace(self) -> Namespace { + match self { + PathSource::Type | PathSource::Trait(_) | PathSource::Struct => TypeNS, + PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct(..) => ValueNS, + PathSource::TraitItem(ns) => ns, + } + } + + fn defer_to_typeck(self) -> bool { + match self { + PathSource::Type + | PathSource::Expr(..) + | PathSource::Pat + | PathSource::Struct + | PathSource::TupleStruct(..) => true, + PathSource::Trait(_) | PathSource::TraitItem(..) => false, + } + } + + fn descr_expected(self) -> &'static str { + match &self { + PathSource::Type => "type", + PathSource::Trait(_) => "trait", + PathSource::Pat => "unit struct, unit variant or constant", + PathSource::Struct => "struct, variant or union type", + PathSource::TupleStruct(..) => "tuple struct or tuple variant", + PathSource::TraitItem(ns) => match ns { + TypeNS => "associated type", + ValueNS => "method or associated constant", + MacroNS => bug!("associated macro"), + }, + PathSource::Expr(parent) => match parent.as_ref().map(|p| &p.kind) { + // "function" here means "anything callable" rather than `DefKind::Fn`, + // this is not precise but usually more helpful than just "value". + Some(ExprKind::Call(call_expr, _)) => match &call_expr.kind { + // the case of `::some_crate()` + ExprKind::Path(_, path) + if path.segments.len() == 2 + && path.segments[0].ident.name == kw::PathRoot => + { + "external crate" + } + ExprKind::Path(_, path) => { + let mut msg = "function"; + if let Some(segment) = path.segments.iter().last() { + if let Some(c) = segment.ident.to_string().chars().next() { + if c.is_uppercase() { + msg = "function, tuple struct or tuple variant"; + } + } + } + msg + } + _ => "function", + }, + _ => "value", + }, + } + } + + fn is_call(self) -> bool { + matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. }))) + } + + pub(crate) fn is_expected(self, res: Res) -> bool { + match self { + PathSource::Type => matches!( + res, + Res::Def( + DefKind::Struct + | DefKind::Union + | DefKind::Enum + | DefKind::Trait + | DefKind::TraitAlias + | DefKind::TyAlias + | DefKind::AssocTy + | DefKind::TyParam + | DefKind::OpaqueTy + | DefKind::ForeignTy, + _, + ) | Res::PrimTy(..) + | Res::SelfTy { .. } + ), + PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)), + PathSource::Trait(AliasPossibility::Maybe) => { + matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _)) + } + PathSource::Expr(..) => matches!( + res, + Res::Def( + DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn) + | DefKind::Const + | DefKind::Static(_) + | DefKind::Fn + | DefKind::AssocFn + | DefKind::AssocConst + | DefKind::ConstParam, + _, + ) | Res::Local(..) + | Res::SelfCtor(..) + ), + PathSource::Pat => { + res.expected_in_unit_struct_pat() + || matches!(res, Res::Def(DefKind::Const | DefKind::AssocConst, _)) + } + PathSource::TupleStruct(..) => res.expected_in_tuple_struct_pat(), + PathSource::Struct => matches!( + res, + Res::Def( + DefKind::Struct + | DefKind::Union + | DefKind::Variant + | DefKind::TyAlias + | DefKind::AssocTy, + _, + ) | Res::SelfTy { .. } + ), + PathSource::TraitItem(ns) => match res { + Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true, + Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true, + _ => false, + }, + } + } + + fn error_code(self, has_unexpected_resolution: bool) -> DiagnosticId { + use rustc_errors::error_code; + match (self, has_unexpected_resolution) { + (PathSource::Trait(_), true) => error_code!(E0404), + (PathSource::Trait(_), false) => error_code!(E0405), + (PathSource::Type, true) => error_code!(E0573), + (PathSource::Type, false) => error_code!(E0412), + (PathSource::Struct, true) => error_code!(E0574), + (PathSource::Struct, false) => error_code!(E0422), + (PathSource::Expr(..), true) => error_code!(E0423), + (PathSource::Expr(..), false) => error_code!(E0425), + (PathSource::Pat | PathSource::TupleStruct(..), true) => error_code!(E0532), + (PathSource::Pat | PathSource::TupleStruct(..), false) => error_code!(E0531), + (PathSource::TraitItem(..), true) => error_code!(E0575), + (PathSource::TraitItem(..), false) => error_code!(E0576), + } + } +} + +#[derive(Default)] +struct DiagnosticMetadata<'ast> { + /// The current trait's associated items' ident, used for diagnostic suggestions. + current_trait_assoc_items: Option<&'ast [P<AssocItem>]>, + + /// The current self type if inside an impl (used for better errors). + current_self_type: Option<Ty>, + + /// The current self item if inside an ADT (used for better errors). + current_self_item: Option<NodeId>, + + /// The current trait (used to suggest). + current_item: Option<&'ast Item>, + + /// When processing generics and encountering a type not found, suggest introducing a type + /// param. + currently_processing_generics: bool, + + /// The current enclosing (non-closure) function (used for better errors). + current_function: Option<(FnKind<'ast>, Span)>, + + /// A list of labels as of yet unused. Labels will be removed from this map when + /// they are used (in a `break` or `continue` statement) + unused_labels: FxHashMap<NodeId, Span>, + + /// Only used for better errors on `fn(): fn()`. + current_type_ascription: Vec<Span>, + + /// Only used for better errors on `let x = { foo: bar };`. + /// In the case of a parse error with `let x = { foo: bar, };`, this isn't needed, it's only + /// needed for cases where this parses as a correct type ascription. + current_block_could_be_bare_struct_literal: Option<Span>, + + /// Only used for better errors on `let <pat>: <expr, not type>;`. + current_let_binding: Option<(Span, Option<Span>, Option<Span>)>, + + /// Used to detect possible `if let` written without `let` and to provide structured suggestion. + in_if_condition: Option<&'ast Expr>, + + /// If we are currently in a trait object definition. Used to point at the bounds when + /// encountering a struct or enum. + current_trait_object: Option<&'ast [ast::GenericBound]>, + + /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`. + current_where_predicate: Option<&'ast WherePredicate>, + + current_type_path: Option<&'ast Ty>, + + /// The current impl items (used to suggest). + current_impl_items: Option<&'ast [P<AssocItem>]>, + + /// When processing impl trait + currently_processing_impl_trait: Option<(TraitRef, Ty)>, + + /// Accumulate the errors due to missed lifetime elision, + /// and report them all at once for each function. + current_elision_failures: Vec<MissingLifetime>, +} + +struct LateResolutionVisitor<'a, 'b, 'ast> { + r: &'b mut Resolver<'a>, + + /// The module that represents the current item scope. + parent_scope: ParentScope<'a>, + + /// The current set of local scopes for types and values. + /// FIXME #4948: Reuse ribs to avoid allocation. + ribs: PerNS<Vec<Rib<'a>>>, + + /// The current set of local scopes, for labels. + label_ribs: Vec<Rib<'a, NodeId>>, + + /// The current set of local scopes for lifetimes. + lifetime_ribs: Vec<LifetimeRib>, + + /// We are looking for lifetimes in an elision context. + /// The set contains all the resolutions that we encountered so far. + /// They will be used to determine the correct lifetime for the fn return type. + /// The `LifetimeElisionCandidate` is used for diagnostics, to suggest introducing named + /// lifetimes. + lifetime_elision_candidates: Option<FxIndexMap<LifetimeRes, LifetimeElisionCandidate>>, + + /// The trait that the current context can refer to. + current_trait_ref: Option<(Module<'a>, TraitRef)>, + + /// Fields used to add information to diagnostic errors. + diagnostic_metadata: Box<DiagnosticMetadata<'ast>>, + + /// State used to know whether to ignore resolution errors for function bodies. + /// + /// In particular, rustdoc uses this to avoid giving errors for `cfg()` items. + /// In most cases this will be `None`, in which case errors will always be reported. + /// If it is `true`, then it will be updated when entering a nested function or trait body. + in_func_body: bool, + + /// Count the number of places a lifetime is used. + lifetime_uses: FxHashMap<LocalDefId, LifetimeUseSet>, +} + +/// Walks the whole crate in DFS order, visiting each item, resolving names as it goes. +impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> { + fn visit_attribute(&mut self, _: &'ast Attribute) { + // We do not want to resolve expressions that appear in attributes, + // as they do not correspond to actual code. + } + fn visit_item(&mut self, item: &'ast Item) { + let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item)); + // Always report errors in items we just entered. + let old_ignore = replace(&mut self.in_func_body, false); + self.with_lifetime_rib(LifetimeRibKind::Item, |this| this.resolve_item(item)); + self.in_func_body = old_ignore; + self.diagnostic_metadata.current_item = prev; + } + fn visit_arm(&mut self, arm: &'ast Arm) { + self.resolve_arm(arm); + } + fn visit_block(&mut self, block: &'ast Block) { + self.resolve_block(block); + } + fn visit_anon_const(&mut self, constant: &'ast AnonConst) { + // We deal with repeat expressions explicitly in `resolve_expr`. + self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| { + this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| { + this.resolve_anon_const(constant, IsRepeatExpr::No); + }) + }) + } + fn visit_expr(&mut self, expr: &'ast Expr) { + self.resolve_expr(expr, None); + } + fn visit_local(&mut self, local: &'ast Local) { + let local_spans = match local.pat.kind { + // We check for this to avoid tuple struct fields. + PatKind::Wild => None, + _ => Some(( + local.pat.span, + local.ty.as_ref().map(|ty| ty.span), + local.kind.init().map(|init| init.span), + )), + }; + let original = replace(&mut self.diagnostic_metadata.current_let_binding, local_spans); + self.resolve_local(local); + self.diagnostic_metadata.current_let_binding = original; + } + fn visit_ty(&mut self, ty: &'ast Ty) { + let prev = self.diagnostic_metadata.current_trait_object; + let prev_ty = self.diagnostic_metadata.current_type_path; + match ty.kind { + TyKind::Rptr(None, _) => { + // Elided lifetime in reference: we resolve as if there was some lifetime `'_` with + // NodeId `ty.id`. + // This span will be used in case of elision failure. + let span = self.r.session.source_map().next_point(ty.span.shrink_to_lo()); + self.resolve_elided_lifetime(ty.id, span); + visit::walk_ty(self, ty); + } + TyKind::Path(ref qself, ref path) => { + self.diagnostic_metadata.current_type_path = Some(ty); + self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type); + + // Check whether we should interpret this as a bare trait object. + if qself.is_none() + && let Some(partial_res) = self.r.partial_res_map.get(&ty.id) + && partial_res.unresolved_segments() == 0 + && let Res::Def(DefKind::Trait | DefKind::TraitAlias, _) = partial_res.base_res() + { + // This path is actually a bare trait object. In case of a bare `Fn`-trait + // object with anonymous lifetimes, we need this rib to correctly place the + // synthetic lifetimes. + let span = ty.span.shrink_to_lo().to(path.span.shrink_to_lo()); + self.with_generic_param_rib( + &[], + NormalRibKind, + LifetimeRibKind::Generics { + binder: ty.id, + kind: LifetimeBinderKind::PolyTrait, + span, + }, + |this| this.visit_path(&path, ty.id), + ); + } else { + visit::walk_ty(self, ty) + } + } + TyKind::ImplicitSelf => { + let self_ty = Ident::with_dummy_span(kw::SelfUpper); + let res = self + .resolve_ident_in_lexical_scope( + self_ty, + TypeNS, + Some(Finalize::new(ty.id, ty.span)), + None, + ) + .map_or(Res::Err, |d| d.res()); + self.r.record_partial_res(ty.id, PartialRes::new(res)); + visit::walk_ty(self, ty) + } + TyKind::ImplTrait(..) => { + let candidates = self.lifetime_elision_candidates.take(); + visit::walk_ty(self, ty); + self.lifetime_elision_candidates = candidates; + } + TyKind::TraitObject(ref bounds, ..) => { + self.diagnostic_metadata.current_trait_object = Some(&bounds[..]); + visit::walk_ty(self, ty) + } + TyKind::BareFn(ref bare_fn) => { + let span = ty.span.shrink_to_lo().to(bare_fn.decl_span.shrink_to_lo()); + self.with_generic_param_rib( + &bare_fn.generic_params, + NormalRibKind, + LifetimeRibKind::Generics { + binder: ty.id, + kind: LifetimeBinderKind::BareFnType, + span, + }, + |this| { + this.visit_generic_params(&bare_fn.generic_params, false); + this.with_lifetime_rib( + LifetimeRibKind::AnonymousCreateParameter { + binder: ty.id, + report_in_path: false, + }, + |this| { + this.resolve_fn_signature( + ty.id, + false, + // We don't need to deal with patterns in parameters, because + // they are not possible for foreign or bodiless functions. + bare_fn + .decl + .inputs + .iter() + .map(|Param { ty, .. }| (None, &**ty)), + &bare_fn.decl.output, + ) + }, + ); + }, + ) + } + _ => visit::walk_ty(self, ty), + } + self.diagnostic_metadata.current_trait_object = prev; + self.diagnostic_metadata.current_type_path = prev_ty; + } + fn visit_poly_trait_ref(&mut self, tref: &'ast PolyTraitRef, _: &'ast TraitBoundModifier) { + let span = tref.span.shrink_to_lo().to(tref.trait_ref.path.span.shrink_to_lo()); + self.with_generic_param_rib( + &tref.bound_generic_params, + NormalRibKind, + LifetimeRibKind::Generics { + binder: tref.trait_ref.ref_id, + kind: LifetimeBinderKind::PolyTrait, + span, + }, + |this| { + this.visit_generic_params(&tref.bound_generic_params, false); + this.smart_resolve_path( + tref.trait_ref.ref_id, + None, + &tref.trait_ref.path, + PathSource::Trait(AliasPossibility::Maybe), + ); + this.visit_trait_ref(&tref.trait_ref); + }, + ); + } + fn visit_foreign_item(&mut self, foreign_item: &'ast ForeignItem) { + match foreign_item.kind { + ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => { + self.with_lifetime_rib(LifetimeRibKind::Item, |this| { + this.with_generic_param_rib( + &generics.params, + ItemRibKind(HasGenericParams::Yes), + LifetimeRibKind::Generics { + binder: foreign_item.id, + kind: LifetimeBinderKind::Item, + span: generics.span, + }, + |this| visit::walk_foreign_item(this, foreign_item), + ) + }); + } + ForeignItemKind::Fn(box Fn { ref generics, .. }) => { + self.with_lifetime_rib(LifetimeRibKind::Item, |this| { + this.with_generic_param_rib( + &generics.params, + ItemRibKind(HasGenericParams::Yes), + LifetimeRibKind::Generics { + binder: foreign_item.id, + kind: LifetimeBinderKind::Function, + span: generics.span, + }, + |this| visit::walk_foreign_item(this, foreign_item), + ) + }); + } + ForeignItemKind::Static(..) => { + self.with_item_rib(|this| { + visit::walk_foreign_item(this, foreign_item); + }); + } + ForeignItemKind::MacCall(..) => { + panic!("unexpanded macro in resolve!") + } + } + } + fn visit_fn(&mut self, fn_kind: FnKind<'ast>, sp: Span, fn_id: NodeId) { + let rib_kind = match fn_kind { + // Bail if the function is foreign, and thus cannot validly have + // a body, or if there's no body for some other reason. + FnKind::Fn(FnCtxt::Foreign, _, sig, _, generics, _) + | FnKind::Fn(_, _, sig, _, generics, None) => { + self.visit_fn_header(&sig.header); + self.visit_generics(generics); + self.with_lifetime_rib( + LifetimeRibKind::AnonymousCreateParameter { + binder: fn_id, + report_in_path: false, + }, + |this| { + this.resolve_fn_signature( + fn_id, + sig.decl.has_self(), + sig.decl.inputs.iter().map(|Param { ty, .. }| (None, &**ty)), + &sig.decl.output, + ) + }, + ); + return; + } + FnKind::Fn(FnCtxt::Free, ..) => FnItemRibKind, + FnKind::Fn(FnCtxt::Assoc(_), ..) => NormalRibKind, + FnKind::Closure(..) => ClosureOrAsyncRibKind, + }; + let previous_value = self.diagnostic_metadata.current_function; + if matches!(fn_kind, FnKind::Fn(..)) { + self.diagnostic_metadata.current_function = Some((fn_kind, sp)); + } + debug!("(resolving function) entering function"); + + // Create a value rib for the function. + self.with_rib(ValueNS, rib_kind, |this| { + // Create a label rib for the function. + this.with_label_rib(FnItemRibKind, |this| { + match fn_kind { + FnKind::Fn(_, _, sig, _, generics, body) => { + this.visit_generics(generics); + + let declaration = &sig.decl; + let async_node_id = sig.header.asyncness.opt_return_id(); + + this.with_lifetime_rib( + LifetimeRibKind::AnonymousCreateParameter { + binder: fn_id, + report_in_path: async_node_id.is_some(), + }, + |this| { + this.resolve_fn_signature( + fn_id, + declaration.has_self(), + declaration + .inputs + .iter() + .map(|Param { pat, ty, .. }| (Some(&**pat), &**ty)), + &declaration.output, + ) + }, + ); + + // Construct the list of in-scope lifetime parameters for async lowering. + // We include all lifetime parameters, either named or "Fresh". + // The order of those parameters does not matter, as long as it is + // deterministic. + if let Some(async_node_id) = async_node_id { + let mut extra_lifetime_params = this + .r + .extra_lifetime_params_map + .get(&fn_id) + .cloned() + .unwrap_or_default(); + for rib in this.lifetime_ribs.iter().rev() { + extra_lifetime_params.extend( + rib.bindings + .iter() + .map(|(&ident, &(node_id, res))| (ident, node_id, res)), + ); + match rib.kind { + LifetimeRibKind::Item => break, + LifetimeRibKind::AnonymousCreateParameter { + binder, .. + } => { + if let Some(earlier_fresh) = + this.r.extra_lifetime_params_map.get(&binder) + { + extra_lifetime_params.extend(earlier_fresh); + } + } + _ => {} + } + } + this.r + .extra_lifetime_params_map + .insert(async_node_id, extra_lifetime_params); + } + + if let Some(body) = body { + // Ignore errors in function bodies if this is rustdoc + // Be sure not to set this until the function signature has been resolved. + let previous_state = replace(&mut this.in_func_body, true); + // Resolve the function body, potentially inside the body of an async closure + this.with_lifetime_rib( + LifetimeRibKind::Elided(LifetimeRes::Infer), + |this| this.visit_block(body), + ); + + debug!("(resolving function) leaving function"); + this.in_func_body = previous_state; + } + } + FnKind::Closure(binder, declaration, body) => { + this.visit_closure_binder(binder); + + this.with_lifetime_rib( + match binder { + // We do not have any explicit generic lifetime parameter. + ClosureBinder::NotPresent => { + LifetimeRibKind::AnonymousCreateParameter { + binder: fn_id, + report_in_path: false, + } + } + ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError, + }, + // Add each argument to the rib. + |this| this.resolve_params(&declaration.inputs), + ); + this.with_lifetime_rib( + match binder { + ClosureBinder::NotPresent => { + LifetimeRibKind::Elided(LifetimeRes::Infer) + } + ClosureBinder::For { .. } => LifetimeRibKind::AnonymousReportError, + }, + |this| visit::walk_fn_ret_ty(this, &declaration.output), + ); + + // Ignore errors in function bodies if this is rustdoc + // Be sure not to set this until the function signature has been resolved. + let previous_state = replace(&mut this.in_func_body, true); + // Resolve the function body, potentially inside the body of an async closure + this.with_lifetime_rib( + LifetimeRibKind::Elided(LifetimeRes::Infer), + |this| this.visit_expr(body), + ); + + debug!("(resolving function) leaving function"); + this.in_func_body = previous_state; + } + } + }) + }); + self.diagnostic_metadata.current_function = previous_value; + } + fn visit_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) { + self.resolve_lifetime(lifetime, use_ctxt) + } + + fn visit_generics(&mut self, generics: &'ast Generics) { + self.visit_generic_params( + &generics.params, + self.diagnostic_metadata.current_self_item.is_some(), + ); + for p in &generics.where_clause.predicates { + self.visit_where_predicate(p); + } + } + + fn visit_closure_binder(&mut self, b: &'ast ClosureBinder) { + match b { + ClosureBinder::NotPresent => {} + ClosureBinder::For { generic_params, .. } => { + self.visit_generic_params( + &generic_params, + self.diagnostic_metadata.current_self_item.is_some(), + ); + } + } + } + + fn visit_generic_arg(&mut self, arg: &'ast GenericArg) { + debug!("visit_generic_arg({:?})", arg); + let prev = replace(&mut self.diagnostic_metadata.currently_processing_generics, true); + match arg { + GenericArg::Type(ref ty) => { + // We parse const arguments as path types as we cannot distinguish them during + // parsing. We try to resolve that ambiguity by attempting resolution the type + // namespace first, and if that fails we try again in the value namespace. If + // resolution in the value namespace succeeds, we have an generic const argument on + // our hands. + if let TyKind::Path(ref qself, ref path) = ty.kind { + // We cannot disambiguate multi-segment paths right now as that requires type + // checking. + if path.segments.len() == 1 && path.segments[0].args.is_none() { + let mut check_ns = |ns| { + self.maybe_resolve_ident_in_lexical_scope(path.segments[0].ident, ns) + .is_some() + }; + if !check_ns(TypeNS) && check_ns(ValueNS) { + // This must be equivalent to `visit_anon_const`, but we cannot call it + // directly due to visitor lifetimes so we have to copy-paste some code. + // + // Note that we might not be inside of an repeat expression here, + // but considering that `IsRepeatExpr` is only relevant for + // non-trivial constants this is doesn't matter. + self.with_constant_rib( + IsRepeatExpr::No, + HasGenericParams::Yes, + None, + |this| { + this.smart_resolve_path( + ty.id, + qself.as_ref(), + path, + PathSource::Expr(None), + ); + + if let Some(ref qself) = *qself { + this.visit_ty(&qself.ty); + } + this.visit_path(path, ty.id); + }, + ); + + self.diagnostic_metadata.currently_processing_generics = prev; + return; + } + } + } + + self.visit_ty(ty); + } + GenericArg::Lifetime(lt) => self.visit_lifetime(lt, visit::LifetimeCtxt::GenericArg), + GenericArg::Const(ct) => self.visit_anon_const(ct), + } + self.diagnostic_metadata.currently_processing_generics = prev; + } + + fn visit_assoc_constraint(&mut self, constraint: &'ast AssocConstraint) { + self.visit_ident(constraint.ident); + if let Some(ref gen_args) = constraint.gen_args { + // Forbid anonymous lifetimes in GAT parameters until proper semantics are decided. + self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| { + this.visit_generic_args(gen_args.span(), gen_args) + }); + } + match constraint.kind { + AssocConstraintKind::Equality { ref term } => match term { + Term::Ty(ty) => self.visit_ty(ty), + Term::Const(c) => self.visit_anon_const(c), + }, + AssocConstraintKind::Bound { ref bounds } => { + walk_list!(self, visit_param_bound, bounds, BoundKind::Bound); + } + } + } + + fn visit_path_segment(&mut self, path_span: Span, path_segment: &'ast PathSegment) { + if let Some(ref args) = path_segment.args { + match &**args { + GenericArgs::AngleBracketed(..) => visit::walk_generic_args(self, path_span, args), + GenericArgs::Parenthesized(p_args) => { + // Probe the lifetime ribs to know how to behave. + for rib in self.lifetime_ribs.iter().rev() { + match rib.kind { + // We are inside a `PolyTraitRef`. The lifetimes are + // to be intoduced in that (maybe implicit) `for<>` binder. + LifetimeRibKind::Generics { + binder, + kind: LifetimeBinderKind::PolyTrait, + .. + } => { + self.with_lifetime_rib( + LifetimeRibKind::AnonymousCreateParameter { + binder, + report_in_path: false, + }, + |this| { + this.resolve_fn_signature( + binder, + false, + p_args.inputs.iter().map(|ty| (None, &**ty)), + &p_args.output, + ) + }, + ); + break; + } + // We have nowhere to introduce generics. Code is malformed, + // so use regular lifetime resolution to avoid spurious errors. + LifetimeRibKind::Item | LifetimeRibKind::Generics { .. } => { + visit::walk_generic_args(self, path_span, args); + break; + } + LifetimeRibKind::AnonymousCreateParameter { .. } + | LifetimeRibKind::AnonymousReportError + | LifetimeRibKind::Elided(_) + | LifetimeRibKind::ElisionFailure + | LifetimeRibKind::AnonConst + | LifetimeRibKind::ConstGeneric => {} + } + } + } + } + } + } + + fn visit_where_predicate(&mut self, p: &'ast WherePredicate) { + debug!("visit_where_predicate {:?}", p); + let previous_value = + replace(&mut self.diagnostic_metadata.current_where_predicate, Some(p)); + self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| { + if let WherePredicate::BoundPredicate(WhereBoundPredicate { + ref bounded_ty, + ref bounds, + ref bound_generic_params, + span: predicate_span, + .. + }) = p + { + let span = predicate_span.shrink_to_lo().to(bounded_ty.span.shrink_to_lo()); + this.with_generic_param_rib( + &bound_generic_params, + NormalRibKind, + LifetimeRibKind::Generics { + binder: bounded_ty.id, + kind: LifetimeBinderKind::WhereBound, + span, + }, + |this| { + this.visit_generic_params(&bound_generic_params, false); + this.visit_ty(bounded_ty); + for bound in bounds { + this.visit_param_bound(bound, BoundKind::Bound) + } + }, + ); + } else { + visit::walk_where_predicate(this, p); + } + }); + self.diagnostic_metadata.current_where_predicate = previous_value; + } + + fn visit_inline_asm(&mut self, asm: &'ast InlineAsm) { + for (op, _) in &asm.operands { + match op { + InlineAsmOperand::In { expr, .. } + | InlineAsmOperand::Out { expr: Some(expr), .. } + | InlineAsmOperand::InOut { expr, .. } => self.visit_expr(expr), + InlineAsmOperand::Out { expr: None, .. } => {} + InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => { + self.visit_expr(in_expr); + if let Some(out_expr) = out_expr { + self.visit_expr(out_expr); + } + } + InlineAsmOperand::Const { anon_const, .. } => { + // Although this is `DefKind::AnonConst`, it is allowed to reference outer + // generic parameters like an inline const. + self.resolve_inline_const(anon_const); + } + InlineAsmOperand::Sym { sym } => self.visit_inline_asm_sym(sym), + } + } + } + + fn visit_inline_asm_sym(&mut self, sym: &'ast InlineAsmSym) { + // This is similar to the code for AnonConst. + self.with_rib(ValueNS, InlineAsmSymRibKind, |this| { + this.with_rib(TypeNS, InlineAsmSymRibKind, |this| { + this.with_label_rib(InlineAsmSymRibKind, |this| { + this.smart_resolve_path( + sym.id, + sym.qself.as_ref(), + &sym.path, + PathSource::Expr(None), + ); + visit::walk_inline_asm_sym(this, sym); + }); + }) + }); + } +} + +impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> { + fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b, 'ast> { + // During late resolution we only track the module component of the parent scope, + // although it may be useful to track other components as well for diagnostics. + let graph_root = resolver.graph_root; + let parent_scope = ParentScope::module(graph_root, resolver); + let start_rib_kind = ModuleRibKind(graph_root); + LateResolutionVisitor { + r: resolver, + parent_scope, + ribs: PerNS { + value_ns: vec![Rib::new(start_rib_kind)], + type_ns: vec![Rib::new(start_rib_kind)], + macro_ns: vec![Rib::new(start_rib_kind)], + }, + label_ribs: Vec::new(), + lifetime_ribs: Vec::new(), + lifetime_elision_candidates: None, + current_trait_ref: None, + diagnostic_metadata: Box::new(DiagnosticMetadata::default()), + // errors at module scope should always be reported + in_func_body: false, + lifetime_uses: Default::default(), + } + } + + fn maybe_resolve_ident_in_lexical_scope( + &mut self, + ident: Ident, + ns: Namespace, + ) -> Option<LexicalScopeBinding<'a>> { + self.r.resolve_ident_in_lexical_scope( + ident, + ns, + &self.parent_scope, + None, + &self.ribs[ns], + None, + ) + } + + fn resolve_ident_in_lexical_scope( + &mut self, + ident: Ident, + ns: Namespace, + finalize: Option<Finalize>, + ignore_binding: Option<&'a NameBinding<'a>>, + ) -> Option<LexicalScopeBinding<'a>> { + self.r.resolve_ident_in_lexical_scope( + ident, + ns, + &self.parent_scope, + finalize, + &self.ribs[ns], + ignore_binding, + ) + } + + fn resolve_path( + &mut self, + path: &[Segment], + opt_ns: Option<Namespace>, // `None` indicates a module path in import + finalize: Option<Finalize>, + ) -> PathResult<'a> { + self.r.resolve_path_with_ribs( + path, + opt_ns, + &self.parent_scope, + finalize, + Some(&self.ribs), + None, + ) + } + + // AST resolution + // + // We maintain a list of value ribs and type ribs. + // + // Simultaneously, we keep track of the current position in the module + // graph in the `parent_scope.module` pointer. When we go to resolve a name in + // the value or type namespaces, we first look through all the ribs and + // then query the module graph. When we resolve a name in the module + // namespace, we can skip all the ribs (since nested modules are not + // allowed within blocks in Rust) and jump straight to the current module + // graph node. + // + // Named implementations are handled separately. When we find a method + // call, we consult the module node to find all of the implementations in + // scope. This information is lazily cached in the module node. We then + // generate a fake "implementation scope" containing all the + // implementations thus found, for compatibility with old resolve pass. + + /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`). + fn with_rib<T>( + &mut self, + ns: Namespace, + kind: RibKind<'a>, + work: impl FnOnce(&mut Self) -> T, + ) -> T { + self.ribs[ns].push(Rib::new(kind)); + let ret = work(self); + self.ribs[ns].pop(); + ret + } + + fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T { + if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) { + // Move down in the graph. + let orig_module = replace(&mut self.parent_scope.module, module); + self.with_rib(ValueNS, ModuleRibKind(module), |this| { + this.with_rib(TypeNS, ModuleRibKind(module), |this| { + let ret = f(this); + this.parent_scope.module = orig_module; + ret + }) + }) + } else { + f(self) + } + } + + fn visit_generic_params(&mut self, params: &'ast [GenericParam], add_self_upper: bool) { + // For type parameter defaults, we have to ban access + // to following type parameters, as the InternalSubsts can only + // provide previous type parameters as they're built. We + // put all the parameters on the ban list and then remove + // them one by one as they are processed and become available. + let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind); + let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind); + for param in params.iter() { + match param.kind { + GenericParamKind::Type { .. } => { + forward_ty_ban_rib + .bindings + .insert(Ident::with_dummy_span(param.ident.name), Res::Err); + } + GenericParamKind::Const { .. } => { + forward_const_ban_rib + .bindings + .insert(Ident::with_dummy_span(param.ident.name), Res::Err); + } + GenericParamKind::Lifetime => {} + } + } + + // rust-lang/rust#61631: The type `Self` is essentially + // another type parameter. For ADTs, we consider it + // well-defined only after all of the ADT type parameters have + // been provided. Therefore, we do not allow use of `Self` + // anywhere in ADT type parameter defaults. + // + // (We however cannot ban `Self` for defaults on *all* generic + // lists; e.g. trait generics can usefully refer to `Self`, + // such as in the case of `trait Add<Rhs = Self>`.) + if add_self_upper { + // (`Some` if + only if we are in ADT's generics.) + forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err); + } + + self.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| { + for param in params { + match param.kind { + GenericParamKind::Lifetime => { + for bound in ¶m.bounds { + this.visit_param_bound(bound, BoundKind::Bound); + } + } + GenericParamKind::Type { ref default } => { + for bound in ¶m.bounds { + this.visit_param_bound(bound, BoundKind::Bound); + } + + if let Some(ref ty) = default { + this.ribs[TypeNS].push(forward_ty_ban_rib); + this.ribs[ValueNS].push(forward_const_ban_rib); + this.visit_ty(ty); + forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap(); + forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap(); + } + + // Allow all following defaults to refer to this type parameter. + forward_ty_ban_rib + .bindings + .remove(&Ident::with_dummy_span(param.ident.name)); + } + GenericParamKind::Const { ref ty, kw_span: _, ref default } => { + // Const parameters can't have param bounds. + assert!(param.bounds.is_empty()); + + this.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind)); + this.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind)); + this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| { + this.visit_ty(ty) + }); + this.ribs[TypeNS].pop().unwrap(); + this.ribs[ValueNS].pop().unwrap(); + + if let Some(ref expr) = default { + this.ribs[TypeNS].push(forward_ty_ban_rib); + this.ribs[ValueNS].push(forward_const_ban_rib); + this.with_lifetime_rib(LifetimeRibKind::ConstGeneric, |this| { + this.resolve_anon_const(expr, IsRepeatExpr::No) + }); + forward_const_ban_rib = this.ribs[ValueNS].pop().unwrap(); + forward_ty_ban_rib = this.ribs[TypeNS].pop().unwrap(); + } + + // Allow all following defaults to refer to this const parameter. + forward_const_ban_rib + .bindings + .remove(&Ident::with_dummy_span(param.ident.name)); + } + } + } + }) + } + + #[tracing::instrument(level = "debug", skip(self, work))] + fn with_lifetime_rib<T>( + &mut self, + kind: LifetimeRibKind, + work: impl FnOnce(&mut Self) -> T, + ) -> T { + self.lifetime_ribs.push(LifetimeRib::new(kind)); + let outer_elision_candidates = self.lifetime_elision_candidates.take(); + let ret = work(self); + self.lifetime_elision_candidates = outer_elision_candidates; + self.lifetime_ribs.pop(); + ret + } + + #[tracing::instrument(level = "debug", skip(self))] + fn resolve_lifetime(&mut self, lifetime: &'ast Lifetime, use_ctxt: visit::LifetimeCtxt) { + let ident = lifetime.ident; + + if ident.name == kw::StaticLifetime { + self.record_lifetime_res( + lifetime.id, + LifetimeRes::Static, + LifetimeElisionCandidate::Named, + ); + return; + } + + if ident.name == kw::UnderscoreLifetime { + return self.resolve_anonymous_lifetime(lifetime, false); + } + + let mut indices = (0..self.lifetime_ribs.len()).rev(); + for i in &mut indices { + let rib = &self.lifetime_ribs[i]; + let normalized_ident = ident.normalize_to_macros_2_0(); + if let Some(&(_, res)) = rib.bindings.get(&normalized_ident) { + self.record_lifetime_res(lifetime.id, res, LifetimeElisionCandidate::Named); + + if let LifetimeRes::Param { param, .. } = res { + match self.lifetime_uses.entry(param) { + Entry::Vacant(v) => { + debug!("First use of {:?} at {:?}", res, ident.span); + let use_set = self + .lifetime_ribs + .iter() + .rev() + .find_map(|rib| match rib.kind { + // Do not suggest eliding a lifetime where an anonymous + // lifetime would be illegal. + LifetimeRibKind::Item + | LifetimeRibKind::AnonymousReportError + | LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many), + // An anonymous lifetime is legal here, go ahead. + LifetimeRibKind::AnonymousCreateParameter { .. } => { + Some(LifetimeUseSet::One { use_span: ident.span, use_ctxt }) + } + // Only report if eliding the lifetime would have the same + // semantics. + LifetimeRibKind::Elided(r) => Some(if res == r { + LifetimeUseSet::One { use_span: ident.span, use_ctxt } + } else { + LifetimeUseSet::Many + }), + LifetimeRibKind::Generics { .. } + | LifetimeRibKind::ConstGeneric + | LifetimeRibKind::AnonConst => None, + }) + .unwrap_or(LifetimeUseSet::Many); + debug!(?use_ctxt, ?use_set); + v.insert(use_set); + } + Entry::Occupied(mut o) => { + debug!("Many uses of {:?} at {:?}", res, ident.span); + *o.get_mut() = LifetimeUseSet::Many; + } + } + } + return; + } + + match rib.kind { + LifetimeRibKind::Item => break, + LifetimeRibKind::ConstGeneric => { + self.emit_non_static_lt_in_const_generic_error(lifetime); + self.record_lifetime_res( + lifetime.id, + LifetimeRes::Error, + LifetimeElisionCandidate::Ignore, + ); + return; + } + LifetimeRibKind::AnonConst => { + self.maybe_emit_forbidden_non_static_lifetime_error(lifetime); + self.record_lifetime_res( + lifetime.id, + LifetimeRes::Error, + LifetimeElisionCandidate::Ignore, + ); + return; + } + _ => {} + } + } + + let mut outer_res = None; + for i in indices { + let rib = &self.lifetime_ribs[i]; + let normalized_ident = ident.normalize_to_macros_2_0(); + if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) { + outer_res = Some(outer); + break; + } + } + + self.emit_undeclared_lifetime_error(lifetime, outer_res); + self.record_lifetime_res(lifetime.id, LifetimeRes::Error, LifetimeElisionCandidate::Named); + } + + #[tracing::instrument(level = "debug", skip(self))] + fn resolve_anonymous_lifetime(&mut self, lifetime: &Lifetime, elided: bool) { + debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime); + + let missing_lifetime = MissingLifetime { + id: lifetime.id, + span: lifetime.ident.span, + kind: if elided { + MissingLifetimeKind::Ampersand + } else { + MissingLifetimeKind::Underscore + }, + count: 1, + }; + let elision_candidate = LifetimeElisionCandidate::Missing(missing_lifetime); + for i in (0..self.lifetime_ribs.len()).rev() { + let rib = &mut self.lifetime_ribs[i]; + debug!(?rib.kind); + match rib.kind { + LifetimeRibKind::AnonymousCreateParameter { binder, .. } => { + let res = self.create_fresh_lifetime(lifetime.id, lifetime.ident, binder); + self.record_lifetime_res(lifetime.id, res, elision_candidate); + return; + } + LifetimeRibKind::AnonymousReportError => { + let (msg, note) = if elided { + ( + "`&` without an explicit lifetime name cannot be used here", + "explicit lifetime name needed here", + ) + } else { + ("`'_` cannot be used here", "`'_` is a reserved lifetime name") + }; + rustc_errors::struct_span_err!( + self.r.session, + lifetime.ident.span, + E0637, + "{}", + msg, + ) + .span_label(lifetime.ident.span, note) + .emit(); + + self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate); + return; + } + LifetimeRibKind::Elided(res) => { + self.record_lifetime_res(lifetime.id, res, elision_candidate); + return; + } + LifetimeRibKind::ElisionFailure => { + self.diagnostic_metadata.current_elision_failures.push(missing_lifetime); + self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate); + return; + } + LifetimeRibKind::Item => break, + LifetimeRibKind::Generics { .. } + | LifetimeRibKind::ConstGeneric + | LifetimeRibKind::AnonConst => {} + } + } + self.record_lifetime_res(lifetime.id, LifetimeRes::Error, elision_candidate); + self.report_missing_lifetime_specifiers(vec![missing_lifetime], None); + } + + #[tracing::instrument(level = "debug", skip(self))] + fn resolve_elided_lifetime(&mut self, anchor_id: NodeId, span: Span) { + let id = self.r.next_node_id(); + let lt = Lifetime { id, ident: Ident::new(kw::UnderscoreLifetime, span) }; + + self.record_lifetime_res( + anchor_id, + LifetimeRes::ElidedAnchor { start: id, end: NodeId::from_u32(id.as_u32() + 1) }, + LifetimeElisionCandidate::Ignore, + ); + self.resolve_anonymous_lifetime(<, true); + } + + #[tracing::instrument(level = "debug", skip(self))] + fn create_fresh_lifetime(&mut self, id: NodeId, ident: Ident, binder: NodeId) -> LifetimeRes { + debug_assert_eq!(ident.name, kw::UnderscoreLifetime); + debug!(?ident.span); + + // Leave the responsibility to create the `LocalDefId` to lowering. + let param = self.r.next_node_id(); + let res = LifetimeRes::Fresh { param, binder }; + + // Record the created lifetime parameter so lowering can pick it up and add it to HIR. + self.r + .extra_lifetime_params_map + .entry(binder) + .or_insert_with(Vec::new) + .push((ident, param, res)); + res + } + + #[tracing::instrument(level = "debug", skip(self))] + fn resolve_elided_lifetimes_in_path( + &mut self, + path_id: NodeId, + partial_res: PartialRes, + path: &[Segment], + source: PathSource<'_>, + path_span: Span, + ) { + let proj_start = path.len() - partial_res.unresolved_segments(); + for (i, segment) in path.iter().enumerate() { + if segment.has_lifetime_args { + continue; + } + let Some(segment_id) = segment.id else { + continue; + }; + + // Figure out if this is a type/trait segment, + // which may need lifetime elision performed. + let type_def_id = match partial_res.base_res() { + Res::Def(DefKind::AssocTy, def_id) if i + 2 == proj_start => self.r.parent(def_id), + Res::Def(DefKind::Variant, def_id) if i + 1 == proj_start => self.r.parent(def_id), + Res::Def(DefKind::Struct, def_id) + | Res::Def(DefKind::Union, def_id) + | Res::Def(DefKind::Enum, def_id) + | Res::Def(DefKind::TyAlias, def_id) + | Res::Def(DefKind::Trait, def_id) + if i + 1 == proj_start => + { + def_id + } + _ => continue, + }; + + let expected_lifetimes = self.r.item_generics_num_lifetimes(type_def_id); + if expected_lifetimes == 0 { + continue; + } + + let node_ids = self.r.next_node_ids(expected_lifetimes); + self.record_lifetime_res( + segment_id, + LifetimeRes::ElidedAnchor { start: node_ids.start, end: node_ids.end }, + LifetimeElisionCandidate::Ignore, + ); + + let inferred = match source { + PathSource::Trait(..) | PathSource::TraitItem(..) | PathSource::Type => false, + PathSource::Expr(..) + | PathSource::Pat + | PathSource::Struct + | PathSource::TupleStruct(..) => true, + }; + if inferred { + // Do not create a parameter for patterns and expressions: type checking can infer + // the appropriate lifetime for us. + for id in node_ids { + self.record_lifetime_res( + id, + LifetimeRes::Infer, + LifetimeElisionCandidate::Named, + ); + } + continue; + } + + let elided_lifetime_span = if segment.has_generic_args { + // If there are brackets, but not generic arguments, then use the opening bracket + segment.args_span.with_hi(segment.args_span.lo() + BytePos(1)) + } else { + // If there are no brackets, use the identifier span. + // HACK: we use find_ancestor_inside to properly suggest elided spans in paths + // originating from macros, since the segment's span might be from a macro arg. + segment.ident.span.find_ancestor_inside(path_span).unwrap_or(path_span) + }; + let ident = Ident::new(kw::UnderscoreLifetime, elided_lifetime_span); + + let missing_lifetime = MissingLifetime { + id: node_ids.start, + span: elided_lifetime_span, + kind: if segment.has_generic_args { + MissingLifetimeKind::Comma + } else { + MissingLifetimeKind::Brackets + }, + count: expected_lifetimes, + }; + let mut should_lint = true; + for rib in self.lifetime_ribs.iter().rev() { + match rib.kind { + // In create-parameter mode we error here because we don't want to support + // deprecated impl elision in new features like impl elision and `async fn`, + // both of which work using the `CreateParameter` mode: + // + // impl Foo for std::cell::Ref<u32> // note lack of '_ + // async fn foo(_: std::cell::Ref<u32>) { ... } + LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. } => { + let sess = self.r.session; + let mut err = rustc_errors::struct_span_err!( + sess, + path_span, + E0726, + "implicit elided lifetime not allowed here" + ); + rustc_errors::add_elided_lifetime_in_path_suggestion( + sess.source_map(), + &mut err, + expected_lifetimes, + path_span, + !segment.has_generic_args, + elided_lifetime_span, + ); + err.note("assuming a `'static` lifetime..."); + err.emit(); + should_lint = false; + + for id in node_ids { + self.record_lifetime_res( + id, + LifetimeRes::Error, + LifetimeElisionCandidate::Named, + ); + } + break; + } + // Do not create a parameter for patterns and expressions. + LifetimeRibKind::AnonymousCreateParameter { binder, .. } => { + // Group all suggestions into the first record. + let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime); + for id in node_ids { + let res = self.create_fresh_lifetime(id, ident, binder); + self.record_lifetime_res( + id, + res, + replace(&mut candidate, LifetimeElisionCandidate::Named), + ); + } + break; + } + LifetimeRibKind::Elided(res) => { + let mut candidate = LifetimeElisionCandidate::Missing(missing_lifetime); + for id in node_ids { + self.record_lifetime_res( + id, + res, + replace(&mut candidate, LifetimeElisionCandidate::Ignore), + ); + } + break; + } + LifetimeRibKind::ElisionFailure => { + self.diagnostic_metadata.current_elision_failures.push(missing_lifetime); + for id in node_ids { + self.record_lifetime_res( + id, + LifetimeRes::Error, + LifetimeElisionCandidate::Ignore, + ); + } + break; + } + // `LifetimeRes::Error`, which would usually be used in the case of + // `ReportError`, is unsuitable here, as we don't emit an error yet. Instead, + // we simply resolve to an implicit lifetime, which will be checked later, at + // which point a suitable error will be emitted. + LifetimeRibKind::AnonymousReportError | LifetimeRibKind::Item => { + for id in node_ids { + self.record_lifetime_res( + id, + LifetimeRes::Error, + LifetimeElisionCandidate::Ignore, + ); + } + self.report_missing_lifetime_specifiers(vec![missing_lifetime], None); + break; + } + LifetimeRibKind::Generics { .. } + | LifetimeRibKind::ConstGeneric + | LifetimeRibKind::AnonConst => {} + } + } + + if should_lint { + self.r.lint_buffer.buffer_lint_with_diagnostic( + lint::builtin::ELIDED_LIFETIMES_IN_PATHS, + segment_id, + elided_lifetime_span, + "hidden lifetime parameters in types are deprecated", + lint::BuiltinLintDiagnostics::ElidedLifetimesInPaths( + expected_lifetimes, + path_span, + !segment.has_generic_args, + elided_lifetime_span, + ), + ); + } + } + } + + #[tracing::instrument(level = "debug", skip(self))] + fn record_lifetime_res( + &mut self, + id: NodeId, + res: LifetimeRes, + candidate: LifetimeElisionCandidate, + ) { + if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) { + panic!( + "lifetime {:?} resolved multiple times ({:?} before, {:?} now)", + id, prev_res, res + ) + } + match res { + LifetimeRes::Param { .. } | LifetimeRes::Fresh { .. } | LifetimeRes::Static => { + if let Some(ref mut candidates) = self.lifetime_elision_candidates { + candidates.insert(res, candidate); + } + } + LifetimeRes::Infer | LifetimeRes::Error | LifetimeRes::ElidedAnchor { .. } => {} + } + } + + #[tracing::instrument(level = "debug", skip(self))] + fn record_lifetime_param(&mut self, id: NodeId, res: LifetimeRes) { + if let Some(prev_res) = self.r.lifetimes_res_map.insert(id, res) { + panic!( + "lifetime parameter {:?} resolved multiple times ({:?} before, {:?} now)", + id, prev_res, res + ) + } + } + + /// Perform resolution of a function signature, accounting for lifetime elision. + #[tracing::instrument(level = "debug", skip(self, inputs))] + fn resolve_fn_signature( + &mut self, + fn_id: NodeId, + has_self: bool, + inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)> + Clone, + output_ty: &'ast FnRetTy, + ) { + // Add each argument to the rib. + let elision_lifetime = self.resolve_fn_params(has_self, inputs); + debug!(?elision_lifetime); + + let outer_failures = take(&mut self.diagnostic_metadata.current_elision_failures); + let output_rib = if let Ok(res) = elision_lifetime.as_ref() { + LifetimeRibKind::Elided(*res) + } else { + LifetimeRibKind::ElisionFailure + }; + self.with_lifetime_rib(output_rib, |this| visit::walk_fn_ret_ty(this, &output_ty)); + let elision_failures = + replace(&mut self.diagnostic_metadata.current_elision_failures, outer_failures); + if !elision_failures.is_empty() { + let Err(failure_info) = elision_lifetime else { bug!() }; + self.report_missing_lifetime_specifiers(elision_failures, Some(failure_info)); + } + } + + /// Resolve inside function parameters and parameter types. + /// Returns the lifetime for elision in fn return type, + /// or diagnostic information in case of elision failure. + fn resolve_fn_params( + &mut self, + has_self: bool, + inputs: impl Iterator<Item = (Option<&'ast Pat>, &'ast Ty)>, + ) -> Result<LifetimeRes, (Vec<MissingLifetime>, Vec<ElisionFnParameter>)> { + let outer_candidates = + replace(&mut self.lifetime_elision_candidates, Some(Default::default())); + + let mut elision_lifetime = None; + let mut lifetime_count = 0; + let mut parameter_info = Vec::new(); + + let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())]; + for (index, (pat, ty)) in inputs.enumerate() { + debug!(?pat, ?ty); + if let Some(pat) = pat { + self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings); + } + self.visit_ty(ty); + + if let Some(ref candidates) = self.lifetime_elision_candidates { + let new_count = candidates.len(); + let local_count = new_count - lifetime_count; + if local_count != 0 { + parameter_info.push(ElisionFnParameter { + index, + ident: if let Some(pat) = pat && let PatKind::Ident(_, ident, _) = pat.kind { + Some(ident) + } else { + None + }, + lifetime_count: local_count, + span: ty.span, + }); + } + lifetime_count = new_count; + } + + // Handle `self` specially. + if index == 0 && has_self { + let self_lifetime = self.find_lifetime_for_self(ty); + if let Set1::One(lifetime) = self_lifetime { + elision_lifetime = Some(lifetime); + self.lifetime_elision_candidates = None; + } else { + self.lifetime_elision_candidates = Some(Default::default()); + lifetime_count = 0; + } + } + debug!("(resolving function / closure) recorded parameter"); + } + + let all_candidates = replace(&mut self.lifetime_elision_candidates, outer_candidates); + debug!(?all_candidates); + + if let Some(res) = elision_lifetime { + return Ok(res); + } + + // We do not have a `self` candidate, look at the full list. + let all_candidates = all_candidates.unwrap(); + if all_candidates.len() == 1 { + Ok(*all_candidates.first().unwrap().0) + } else { + let all_candidates = all_candidates + .into_iter() + .filter_map(|(_, candidate)| match candidate { + LifetimeElisionCandidate::Ignore | LifetimeElisionCandidate::Named => None, + LifetimeElisionCandidate::Missing(missing) => Some(missing), + }) + .collect(); + Err((all_candidates, parameter_info)) + } + } + + /// List all the lifetimes that appear in the provided type. + fn find_lifetime_for_self(&self, ty: &'ast Ty) -> Set1<LifetimeRes> { + struct SelfVisitor<'r, 'a> { + r: &'r Resolver<'a>, + impl_self: Option<Res>, + lifetime: Set1<LifetimeRes>, + } + + impl SelfVisitor<'_, '_> { + // Look for `self: &'a Self` - also desugared from `&'a self`, + // and if that matches, use it for elision and return early. + fn is_self_ty(&self, ty: &Ty) -> bool { + match ty.kind { + TyKind::ImplicitSelf => true, + TyKind::Path(None, _) => { + let path_res = self.r.partial_res_map[&ty.id].base_res(); + if let Res::SelfTy { .. } = path_res { + return true; + } + Some(path_res) == self.impl_self + } + _ => false, + } + } + } + + impl<'a> Visitor<'a> for SelfVisitor<'_, '_> { + fn visit_ty(&mut self, ty: &'a Ty) { + trace!("SelfVisitor considering ty={:?}", ty); + if let TyKind::Rptr(lt, ref mt) = ty.kind && self.is_self_ty(&mt.ty) { + let lt_id = if let Some(lt) = lt { + lt.id + } else { + let res = self.r.lifetimes_res_map[&ty.id]; + let LifetimeRes::ElidedAnchor { start, .. } = res else { bug!() }; + start + }; + let lt_res = self.r.lifetimes_res_map[<_id]; + trace!("SelfVisitor inserting res={:?}", lt_res); + self.lifetime.insert(lt_res); + } + visit::walk_ty(self, ty) + } + } + + let impl_self = self + .diagnostic_metadata + .current_self_type + .as_ref() + .and_then(|ty| { + if let TyKind::Path(None, _) = ty.kind { + self.r.partial_res_map.get(&ty.id) + } else { + None + } + }) + .map(|res| res.base_res()) + .filter(|res| { + // Permit the types that unambiguously always + // result in the same type constructor being used + // (it can't differ between `Self` and `self`). + matches!( + res, + Res::Def(DefKind::Struct | DefKind::Union | DefKind::Enum, _,) | Res::PrimTy(_) + ) + }); + let mut visitor = SelfVisitor { r: self.r, impl_self, lifetime: Set1::Empty }; + visitor.visit_ty(ty); + trace!("SelfVisitor found={:?}", visitor.lifetime); + visitor.lifetime + } + + /// Searches the current set of local scopes for labels. Returns the `NodeId` of the resolved + /// label and reports an error if the label is not found or is unreachable. + fn resolve_label(&mut self, mut label: Ident) -> Result<(NodeId, Span), ResolutionError<'a>> { + let mut suggestion = None; + + for i in (0..self.label_ribs.len()).rev() { + let rib = &self.label_ribs[i]; + + if let MacroDefinition(def) = rib.kind { + // If an invocation of this macro created `ident`, give up on `ident` + // and switch to `ident`'s source from the macro definition. + if def == self.r.macro_def(label.span.ctxt()) { + label.span.remove_mark(); + } + } + + let ident = label.normalize_to_macro_rules(); + if let Some((ident, id)) = rib.bindings.get_key_value(&ident) { + let definition_span = ident.span; + return if self.is_label_valid_from_rib(i) { + Ok((*id, definition_span)) + } else { + Err(ResolutionError::UnreachableLabel { + name: label.name, + definition_span, + suggestion, + }) + }; + } + + // Diagnostics: Check if this rib contains a label with a similar name, keep track of + // the first such label that is encountered. + suggestion = suggestion.or_else(|| self.suggestion_for_label_in_rib(i, label)); + } + + Err(ResolutionError::UndeclaredLabel { name: label.name, suggestion }) + } + + /// Determine whether or not a label from the `rib_index`th label rib is reachable. + fn is_label_valid_from_rib(&self, rib_index: usize) -> bool { + let ribs = &self.label_ribs[rib_index + 1..]; + + for rib in ribs { + if rib.kind.is_label_barrier() { + return false; + } + } + + true + } + + fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) { + debug!("resolve_adt"); + self.with_current_self_item(item, |this| { + this.with_generic_param_rib( + &generics.params, + ItemRibKind(HasGenericParams::Yes), + LifetimeRibKind::Generics { + binder: item.id, + kind: LifetimeBinderKind::Item, + span: generics.span, + }, + |this| { + let item_def_id = this.r.local_def_id(item.id).to_def_id(); + this.with_self_rib( + Res::SelfTy { trait_: None, alias_to: Some((item_def_id, false)) }, + |this| { + visit::walk_item(this, item); + }, + ); + }, + ); + }); + } + + fn future_proof_import(&mut self, use_tree: &UseTree) { + let segments = &use_tree.prefix.segments; + if !segments.is_empty() { + let ident = segments[0].ident; + if ident.is_path_segment_keyword() || ident.span.rust_2015() { + return; + } + + let nss = match use_tree.kind { + UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..], + _ => &[TypeNS], + }; + let report_error = |this: &Self, ns| { + let what = if ns == TypeNS { "type parameters" } else { "local variables" }; + if this.should_report_errs() { + this.r + .session + .span_err(ident.span, &format!("imports cannot refer to {}", what)); + } + }; + + for &ns in nss { + match self.maybe_resolve_ident_in_lexical_scope(ident, ns) { + Some(LexicalScopeBinding::Res(..)) => { + report_error(self, ns); + } + Some(LexicalScopeBinding::Item(binding)) => { + if let Some(LexicalScopeBinding::Res(..)) = + self.resolve_ident_in_lexical_scope(ident, ns, None, Some(binding)) + { + report_error(self, ns); + } + } + None => {} + } + } + } else if let UseTreeKind::Nested(use_trees) = &use_tree.kind { + for (use_tree, _) in use_trees { + self.future_proof_import(use_tree); + } + } + } + + fn resolve_item(&mut self, item: &'ast Item) { + let name = item.ident.name; + debug!("(resolving item) resolving {} ({:?})", name, item.kind); + + match item.kind { + ItemKind::TyAlias(box TyAlias { ref generics, .. }) => { + self.with_generic_param_rib( + &generics.params, + ItemRibKind(HasGenericParams::Yes), + LifetimeRibKind::Generics { + binder: item.id, + kind: LifetimeBinderKind::Item, + span: generics.span, + }, + |this| visit::walk_item(this, item), + ); + } + + ItemKind::Fn(box Fn { ref generics, .. }) => { + self.with_generic_param_rib( + &generics.params, + ItemRibKind(HasGenericParams::Yes), + LifetimeRibKind::Generics { + binder: item.id, + kind: LifetimeBinderKind::Function, + span: generics.span, + }, + |this| visit::walk_item(this, item), + ); + } + + ItemKind::Enum(_, ref generics) + | ItemKind::Struct(_, ref generics) + | ItemKind::Union(_, ref generics) => { + self.resolve_adt(item, generics); + } + + ItemKind::Impl(box Impl { + ref generics, + ref of_trait, + ref self_ty, + items: ref impl_items, + .. + }) => { + self.diagnostic_metadata.current_impl_items = Some(impl_items); + self.resolve_implementation(generics, of_trait, &self_ty, item.id, impl_items); + self.diagnostic_metadata.current_impl_items = None; + } + + ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => { + // Create a new rib for the trait-wide type parameters. + self.with_generic_param_rib( + &generics.params, + ItemRibKind(HasGenericParams::Yes), + LifetimeRibKind::Generics { + binder: item.id, + kind: LifetimeBinderKind::Item, + span: generics.span, + }, + |this| { + let local_def_id = this.r.local_def_id(item.id).to_def_id(); + this.with_self_rib( + Res::SelfTy { trait_: Some(local_def_id), alias_to: None }, + |this| { + this.visit_generics(generics); + walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits); + this.resolve_trait_items(items); + }, + ); + }, + ); + } + + ItemKind::TraitAlias(ref generics, ref bounds) => { + // Create a new rib for the trait-wide type parameters. + self.with_generic_param_rib( + &generics.params, + ItemRibKind(HasGenericParams::Yes), + LifetimeRibKind::Generics { + binder: item.id, + kind: LifetimeBinderKind::Item, + span: generics.span, + }, + |this| { + let local_def_id = this.r.local_def_id(item.id).to_def_id(); + this.with_self_rib( + Res::SelfTy { trait_: Some(local_def_id), alias_to: None }, + |this| { + this.visit_generics(generics); + walk_list!(this, visit_param_bound, bounds, BoundKind::Bound); + }, + ); + }, + ); + } + + ItemKind::Mod(..) | ItemKind::ForeignMod(_) => { + self.with_scope(item.id, |this| { + visit::walk_item(this, item); + }); + } + + ItemKind::Static(ref ty, _, ref expr) | ItemKind::Const(_, ref ty, ref expr) => { + self.with_item_rib(|this| { + this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| { + this.visit_ty(ty); + }); + this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| { + if let Some(expr) = expr { + let constant_item_kind = match item.kind { + ItemKind::Const(..) => ConstantItemKind::Const, + ItemKind::Static(..) => ConstantItemKind::Static, + _ => unreachable!(), + }; + // We already forbid generic params because of the above item rib, + // so it doesn't matter whether this is a trivial constant. + this.with_constant_rib( + IsRepeatExpr::No, + HasGenericParams::Yes, + Some((item.ident, constant_item_kind)), + |this| this.visit_expr(expr), + ); + } + }); + }); + } + + ItemKind::Use(ref use_tree) => { + self.future_proof_import(use_tree); + } + + ItemKind::ExternCrate(..) | ItemKind::MacroDef(..) => { + // do nothing, these are just around to be encoded + } + + ItemKind::GlobalAsm(_) => { + visit::walk_item(self, item); + } + + ItemKind::MacCall(_) => panic!("unexpanded macro in resolve!"), + } + } + + fn with_generic_param_rib<'c, F>( + &'c mut self, + params: &'c [GenericParam], + kind: RibKind<'a>, + lifetime_kind: LifetimeRibKind, + f: F, + ) where + F: FnOnce(&mut Self), + { + debug!("with_generic_param_rib"); + let LifetimeRibKind::Generics { binder, span: generics_span, kind: generics_kind, .. } + = lifetime_kind else { panic!() }; + + let mut function_type_rib = Rib::new(kind); + let mut function_value_rib = Rib::new(kind); + let mut function_lifetime_rib = LifetimeRib::new(lifetime_kind); + let mut seen_bindings = FxHashMap::default(); + // Store all seen lifetimes names from outer scopes. + let mut seen_lifetimes = FxHashSet::default(); + + // We also can't shadow bindings from the parent item + if let AssocItemRibKind = kind { + let mut add_bindings_for_ns = |ns| { + let parent_rib = self.ribs[ns] + .iter() + .rfind(|r| matches!(r.kind, ItemRibKind(_))) + .expect("associated item outside of an item"); + seen_bindings + .extend(parent_rib.bindings.iter().map(|(ident, _)| (*ident, ident.span))); + }; + add_bindings_for_ns(ValueNS); + add_bindings_for_ns(TypeNS); + } + + // Forbid shadowing lifetime bindings + for rib in self.lifetime_ribs.iter().rev() { + seen_lifetimes.extend(rib.bindings.iter().map(|(ident, _)| *ident)); + if let LifetimeRibKind::Item = rib.kind { + break; + } + } + + for param in params { + let ident = param.ident.normalize_to_macros_2_0(); + debug!("with_generic_param_rib: {}", param.id); + + if let GenericParamKind::Lifetime = param.kind + && let Some(&original) = seen_lifetimes.get(&ident) + { + diagnostics::signal_lifetime_shadowing(self.r.session, original, param.ident); + // Record lifetime res, so lowering knows there is something fishy. + self.record_lifetime_param(param.id, LifetimeRes::Error); + continue; + } + + match seen_bindings.entry(ident) { + Entry::Occupied(entry) => { + let span = *entry.get(); + let err = ResolutionError::NameAlreadyUsedInParameterList(ident.name, span); + self.report_error(param.ident.span, err); + if let GenericParamKind::Lifetime = param.kind { + // Record lifetime res, so lowering knows there is something fishy. + self.record_lifetime_param(param.id, LifetimeRes::Error); + continue; + } + } + Entry::Vacant(entry) => { + entry.insert(param.ident.span); + } + } + + if param.ident.name == kw::UnderscoreLifetime { + rustc_errors::struct_span_err!( + self.r.session, + param.ident.span, + E0637, + "`'_` cannot be used here" + ) + .span_label(param.ident.span, "`'_` is a reserved lifetime name") + .emit(); + // Record lifetime res, so lowering knows there is something fishy. + self.record_lifetime_param(param.id, LifetimeRes::Error); + continue; + } + + if param.ident.name == kw::StaticLifetime { + rustc_errors::struct_span_err!( + self.r.session, + param.ident.span, + E0262, + "invalid lifetime parameter name: `{}`", + param.ident, + ) + .span_label(param.ident.span, "'static is a reserved lifetime name") + .emit(); + // Record lifetime res, so lowering knows there is something fishy. + self.record_lifetime_param(param.id, LifetimeRes::Error); + continue; + } + + let def_id = self.r.local_def_id(param.id); + + // Plain insert (no renaming). + let (rib, def_kind) = match param.kind { + GenericParamKind::Type { .. } => (&mut function_type_rib, DefKind::TyParam), + GenericParamKind::Const { .. } => (&mut function_value_rib, DefKind::ConstParam), + GenericParamKind::Lifetime => { + let res = LifetimeRes::Param { param: def_id, binder }; + self.record_lifetime_param(param.id, res); + function_lifetime_rib.bindings.insert(ident, (param.id, res)); + continue; + } + }; + + let res = match kind { + ItemRibKind(..) | AssocItemRibKind => Res::Def(def_kind, def_id.to_def_id()), + NormalRibKind => Res::Err, + _ => span_bug!(param.ident.span, "Unexpected rib kind {:?}", kind), + }; + self.r.record_partial_res(param.id, PartialRes::new(res)); + rib.bindings.insert(ident, res); + } + + self.lifetime_ribs.push(function_lifetime_rib); + self.ribs[ValueNS].push(function_value_rib); + self.ribs[TypeNS].push(function_type_rib); + + f(self); + + self.ribs[TypeNS].pop(); + self.ribs[ValueNS].pop(); + let function_lifetime_rib = self.lifetime_ribs.pop().unwrap(); + + // Do not account for the parameters we just bound for function lifetime elision. + if let Some(ref mut candidates) = self.lifetime_elision_candidates { + for (_, res) in function_lifetime_rib.bindings.values() { + candidates.remove(res); + } + } + + if let LifetimeBinderKind::BareFnType + | LifetimeBinderKind::WhereBound + | LifetimeBinderKind::Function + | LifetimeBinderKind::ImplBlock = generics_kind + { + self.maybe_report_lifetime_uses(generics_span, params) + } + } + + fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) { + self.label_ribs.push(Rib::new(kind)); + f(self); + self.label_ribs.pop(); + } + + fn with_item_rib(&mut self, f: impl FnOnce(&mut Self)) { + let kind = ItemRibKind(HasGenericParams::No); + self.with_lifetime_rib(LifetimeRibKind::Item, |this| { + this.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f)) + }) + } + + // HACK(min_const_generics,const_evaluatable_unchecked): We + // want to keep allowing `[0; std::mem::size_of::<*mut T>()]` + // with a future compat lint for now. We do this by adding an + // additional special case for repeat expressions. + // + // Note that we intentionally still forbid `[0; N + 1]` during + // name resolution so that we don't extend the future + // compat lint to new cases. + #[instrument(level = "debug", skip(self, f))] + fn with_constant_rib( + &mut self, + is_repeat: IsRepeatExpr, + may_use_generics: HasGenericParams, + item: Option<(Ident, ConstantItemKind)>, + f: impl FnOnce(&mut Self), + ) { + self.with_rib(ValueNS, ConstantItemRibKind(may_use_generics, item), |this| { + this.with_rib( + TypeNS, + ConstantItemRibKind( + may_use_generics.force_yes_if(is_repeat == IsRepeatExpr::Yes), + item, + ), + |this| { + this.with_label_rib(ConstantItemRibKind(may_use_generics, item), f); + }, + ) + }); + } + + fn with_current_self_type<T>(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T { + // Handle nested impls (inside fn bodies) + let previous_value = + replace(&mut self.diagnostic_metadata.current_self_type, Some(self_type.clone())); + let result = f(self); + self.diagnostic_metadata.current_self_type = previous_value; + result + } + + fn with_current_self_item<T>(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T { + let previous_value = + replace(&mut self.diagnostic_metadata.current_self_item, Some(self_item.id)); + let result = f(self); + self.diagnostic_metadata.current_self_item = previous_value; + result + } + + /// When evaluating a `trait` use its associated types' idents for suggestions in E0412. + fn resolve_trait_items(&mut self, trait_items: &'ast [P<AssocItem>]) { + let trait_assoc_items = + replace(&mut self.diagnostic_metadata.current_trait_assoc_items, Some(&trait_items)); + + let walk_assoc_item = + |this: &mut Self, generics: &Generics, kind, item: &'ast AssocItem| { + this.with_generic_param_rib( + &generics.params, + AssocItemRibKind, + LifetimeRibKind::Generics { binder: item.id, span: generics.span, kind }, + |this| visit::walk_assoc_item(this, item, AssocCtxt::Trait), + ); + }; + + for item in trait_items { + match &item.kind { + AssocItemKind::Const(_, ty, default) => { + self.visit_ty(ty); + // Only impose the restrictions of `ConstRibKind` for an + // actual constant expression in a provided default. + if let Some(expr) = default { + // We allow arbitrary const expressions inside of associated consts, + // even if they are potentially not const evaluatable. + // + // Type parameters can already be used and as associated consts are + // not used as part of the type system, this is far less surprising. + self.with_lifetime_rib( + LifetimeRibKind::Elided(LifetimeRes::Infer), + |this| { + this.with_constant_rib( + IsRepeatExpr::No, + HasGenericParams::Yes, + None, + |this| this.visit_expr(expr), + ) + }, + ); + } + } + AssocItemKind::Fn(box Fn { generics, .. }) => { + walk_assoc_item(self, generics, LifetimeBinderKind::Function, item); + } + AssocItemKind::TyAlias(box TyAlias { generics, .. }) => self + .with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| { + walk_assoc_item(this, generics, LifetimeBinderKind::Item, item) + }), + AssocItemKind::MacCall(_) => { + panic!("unexpanded macro in resolve!") + } + }; + } + + self.diagnostic_metadata.current_trait_assoc_items = trait_assoc_items; + } + + /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`). + fn with_optional_trait_ref<T>( + &mut self, + opt_trait_ref: Option<&TraitRef>, + self_type: &'ast Ty, + f: impl FnOnce(&mut Self, Option<DefId>) -> T, + ) -> T { + let mut new_val = None; + let mut new_id = None; + if let Some(trait_ref) = opt_trait_ref { + let path: Vec<_> = Segment::from_path(&trait_ref.path); + self.diagnostic_metadata.currently_processing_impl_trait = + Some((trait_ref.clone(), self_type.clone())); + let res = self.smart_resolve_path_fragment( + None, + &path, + PathSource::Trait(AliasPossibility::No), + Finalize::new(trait_ref.ref_id, trait_ref.path.span), + ); + self.diagnostic_metadata.currently_processing_impl_trait = None; + if let Some(def_id) = res.base_res().opt_def_id() { + new_id = Some(def_id); + new_val = Some((self.r.expect_module(def_id), trait_ref.clone())); + } + } + let original_trait_ref = replace(&mut self.current_trait_ref, new_val); + let result = f(self, new_id); + self.current_trait_ref = original_trait_ref; + result + } + + fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) { + let mut self_type_rib = Rib::new(NormalRibKind); + + // Plain insert (no renaming, since types are not currently hygienic) + self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res); + self.ribs[ns].push(self_type_rib); + f(self); + self.ribs[ns].pop(); + } + + fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) { + self.with_self_rib_ns(TypeNS, self_res, f) + } + + fn resolve_implementation( + &mut self, + generics: &'ast Generics, + opt_trait_reference: &'ast Option<TraitRef>, + self_type: &'ast Ty, + item_id: NodeId, + impl_items: &'ast [P<AssocItem>], + ) { + debug!("resolve_implementation"); + // If applicable, create a rib for the type parameters. + self.with_generic_param_rib( + &generics.params, + ItemRibKind(HasGenericParams::Yes), + LifetimeRibKind::Generics { + span: generics.span, + binder: item_id, + kind: LifetimeBinderKind::ImplBlock, + }, + |this| { + // Dummy self type for better errors if `Self` is used in the trait path. + this.with_self_rib(Res::SelfTy { trait_: None, alias_to: None }, |this| { + this.with_lifetime_rib( + LifetimeRibKind::AnonymousCreateParameter { + binder: item_id, + report_in_path: true + }, + |this| { + // Resolve the trait reference, if necessary. + this.with_optional_trait_ref( + opt_trait_reference.as_ref(), + self_type, + |this, trait_id| { + let item_def_id = this.r.local_def_id(item_id); + + // Register the trait definitions from here. + if let Some(trait_id) = trait_id { + this.r + .trait_impls + .entry(trait_id) + .or_default() + .push(item_def_id); + } + + let item_def_id = item_def_id.to_def_id(); + let res = Res::SelfTy { + trait_: trait_id, + alias_to: Some((item_def_id, false)), + }; + this.with_self_rib(res, |this| { + if let Some(trait_ref) = opt_trait_reference.as_ref() { + // Resolve type arguments in the trait path. + visit::walk_trait_ref(this, trait_ref); + } + // Resolve the self type. + this.visit_ty(self_type); + // Resolve the generic parameters. + this.visit_generics(generics); + + // Resolve the items within the impl. + this.with_current_self_type(self_type, |this| { + this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| { + debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)"); + for item in impl_items { + this.resolve_impl_item(&**item); + } + }); + }); + }); + }, + ) + }, + ); + }); + }, + ); + } + + fn resolve_impl_item(&mut self, item: &'ast AssocItem) { + use crate::ResolutionError::*; + match &item.kind { + AssocItemKind::Const(_, ty, default) => { + debug!("resolve_implementation AssocItemKind::Const"); + // If this is a trait impl, ensure the const + // exists in trait + self.check_trait_item( + item.id, + item.ident, + &item.kind, + ValueNS, + item.span, + |i, s, c| ConstNotMemberOfTrait(i, s, c), + ); + + self.visit_ty(ty); + if let Some(expr) = default { + // We allow arbitrary const expressions inside of associated consts, + // even if they are potentially not const evaluatable. + // + // Type parameters can already be used and as associated consts are + // not used as part of the type system, this is far less surprising. + self.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| { + this.with_constant_rib( + IsRepeatExpr::No, + HasGenericParams::Yes, + None, + |this| this.visit_expr(expr), + ) + }); + } + } + AssocItemKind::Fn(box Fn { generics, .. }) => { + debug!("resolve_implementation AssocItemKind::Fn"); + // We also need a new scope for the impl item type parameters. + self.with_generic_param_rib( + &generics.params, + AssocItemRibKind, + LifetimeRibKind::Generics { + binder: item.id, + span: generics.span, + kind: LifetimeBinderKind::Function, + }, + |this| { + // If this is a trait impl, ensure the method + // exists in trait + this.check_trait_item( + item.id, + item.ident, + &item.kind, + ValueNS, + item.span, + |i, s, c| MethodNotMemberOfTrait(i, s, c), + ); + + visit::walk_assoc_item(this, item, AssocCtxt::Impl) + }, + ); + } + AssocItemKind::TyAlias(box TyAlias { generics, .. }) => { + debug!("resolve_implementation AssocItemKind::TyAlias"); + // We also need a new scope for the impl item type parameters. + self.with_generic_param_rib( + &generics.params, + AssocItemRibKind, + LifetimeRibKind::Generics { + binder: item.id, + span: generics.span, + kind: LifetimeBinderKind::Item, + }, + |this| { + this.with_lifetime_rib(LifetimeRibKind::AnonymousReportError, |this| { + // If this is a trait impl, ensure the type + // exists in trait + this.check_trait_item( + item.id, + item.ident, + &item.kind, + TypeNS, + item.span, + |i, s, c| TypeNotMemberOfTrait(i, s, c), + ); + + visit::walk_assoc_item(this, item, AssocCtxt::Impl) + }); + }, + ); + } + AssocItemKind::MacCall(_) => { + panic!("unexpanded macro in resolve!") + } + } + } + + fn check_trait_item<F>( + &mut self, + id: NodeId, + mut ident: Ident, + kind: &AssocItemKind, + ns: Namespace, + span: Span, + err: F, + ) where + F: FnOnce(Ident, String, Option<Symbol>) -> ResolutionError<'a>, + { + // If there is a TraitRef in scope for an impl, then the method must be in the trait. + let Some((module, _)) = &self.current_trait_ref else { return; }; + ident.span.normalize_to_macros_2_0_and_adjust(module.expansion); + let key = self.r.new_key(ident, ns); + let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding); + debug!(?binding); + if binding.is_none() { + // We could not find the trait item in the correct namespace. + // Check the other namespace to report an error. + let ns = match ns { + ValueNS => TypeNS, + TypeNS => ValueNS, + _ => ns, + }; + let key = self.r.new_key(ident, ns); + binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding); + debug!(?binding); + } + let Some(binding) = binding else { + // We could not find the method: report an error. + let candidate = self.find_similarly_named_assoc_item(ident.name, kind); + let path = &self.current_trait_ref.as_ref().unwrap().1.path; + let path_names = path_names_to_string(path); + self.report_error(span, err(ident, path_names, candidate)); + return; + }; + + let res = binding.res(); + let Res::Def(def_kind, _) = res else { bug!() }; + match (def_kind, kind) { + (DefKind::AssocTy, AssocItemKind::TyAlias(..)) + | (DefKind::AssocFn, AssocItemKind::Fn(..)) + | (DefKind::AssocConst, AssocItemKind::Const(..)) => { + self.r.record_partial_res(id, PartialRes::new(res)); + return; + } + _ => {} + } + + // The method kind does not correspond to what appeared in the trait, report. + let path = &self.current_trait_ref.as_ref().unwrap().1.path; + let (code, kind) = match kind { + AssocItemKind::Const(..) => (rustc_errors::error_code!(E0323), "const"), + AssocItemKind::Fn(..) => (rustc_errors::error_code!(E0324), "method"), + AssocItemKind::TyAlias(..) => (rustc_errors::error_code!(E0325), "type"), + AssocItemKind::MacCall(..) => span_bug!(span, "unexpanded macro"), + }; + let trait_path = path_names_to_string(path); + self.report_error( + span, + ResolutionError::TraitImplMismatch { + name: ident.name, + kind, + code, + trait_path, + trait_item_span: binding.span, + }, + ); + } + + fn resolve_params(&mut self, params: &'ast [Param]) { + let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())]; + for Param { pat, ty, .. } in params { + self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings); + self.visit_ty(ty); + debug!("(resolving function / closure) recorded parameter"); + } + } + + fn resolve_local(&mut self, local: &'ast Local) { + debug!("resolving local ({:?})", local); + // Resolve the type. + walk_list!(self, visit_ty, &local.ty); + + // Resolve the initializer. + if let Some((init, els)) = local.kind.init_else_opt() { + self.visit_expr(init); + + // Resolve the `else` block + if let Some(els) = els { + self.visit_block(els); + } + } + + // Resolve the pattern. + self.resolve_pattern_top(&local.pat, PatternSource::Let); + } + + /// build a map from pattern identifiers to binding-info's. + /// this is done hygienically. This could arise for a macro + /// that expands into an or-pattern where one 'x' was from the + /// user and one 'x' came from the macro. + fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap { + let mut binding_map = FxHashMap::default(); + + pat.walk(&mut |pat| { + match pat.kind { + PatKind::Ident(binding_mode, ident, ref sub_pat) + if sub_pat.is_some() || self.is_base_res_local(pat.id) => + { + binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode }); + } + PatKind::Or(ref ps) => { + // Check the consistency of this or-pattern and + // then add all bindings to the larger map. + for bm in self.check_consistent_bindings(ps) { + binding_map.extend(bm); + } + return false; + } + _ => {} + } + + true + }); + + binding_map + } + + fn is_base_res_local(&self, nid: NodeId) -> bool { + matches!(self.r.partial_res_map.get(&nid).map(|res| res.base_res()), Some(Res::Local(..))) + } + + /// Checks that all of the arms in an or-pattern have exactly the + /// same set of bindings, with the same binding modes for each. + fn check_consistent_bindings(&mut self, pats: &[P<Pat>]) -> Vec<BindingMap> { + let mut missing_vars = FxHashMap::default(); + let mut inconsistent_vars = FxHashMap::default(); + + // 1) Compute the binding maps of all arms. + let maps = pats.iter().map(|pat| self.binding_mode_map(pat)).collect::<Vec<_>>(); + + // 2) Record any missing bindings or binding mode inconsistencies. + for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) { + // Check against all arms except for the same pattern which is always self-consistent. + let inners = pats + .iter() + .enumerate() + .filter(|(_, pat)| pat.id != pat_outer.id) + .flat_map(|(idx, _)| maps[idx].iter()) + .map(|(key, binding)| (key.name, map_outer.get(&key), binding)); + + for (name, info, &binding_inner) in inners { + match info { + None => { + // The inner binding is missing in the outer. + let binding_error = + missing_vars.entry(name).or_insert_with(|| BindingError { + name, + origin: BTreeSet::new(), + target: BTreeSet::new(), + could_be_path: name.as_str().starts_with(char::is_uppercase), + }); + binding_error.origin.insert(binding_inner.span); + binding_error.target.insert(pat_outer.span); + } + Some(binding_outer) => { + if binding_outer.binding_mode != binding_inner.binding_mode { + // The binding modes in the outer and inner bindings differ. + inconsistent_vars + .entry(name) + .or_insert((binding_inner.span, binding_outer.span)); + } + } + } + } + } + + // 3) Report all missing variables we found. + let mut missing_vars = missing_vars.into_iter().collect::<Vec<_>>(); + missing_vars.sort_by_key(|&(sym, ref _err)| sym); + + for (name, mut v) in missing_vars.into_iter() { + if inconsistent_vars.contains_key(&name) { + v.could_be_path = false; + } + self.report_error( + *v.origin.iter().next().unwrap(), + ResolutionError::VariableNotBoundInPattern(v, self.parent_scope), + ); + } + + // 4) Report all inconsistencies in binding modes we found. + let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>(); + inconsistent_vars.sort(); + for (name, v) in inconsistent_vars { + self.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1)); + } + + // 5) Finally bubble up all the binding maps. + maps + } + + /// Check the consistency of the outermost or-patterns. + fn check_consistent_bindings_top(&mut self, pat: &'ast Pat) { + pat.walk(&mut |pat| match pat.kind { + PatKind::Or(ref ps) => { + self.check_consistent_bindings(ps); + false + } + _ => true, + }) + } + + fn resolve_arm(&mut self, arm: &'ast Arm) { + self.with_rib(ValueNS, NormalRibKind, |this| { + this.resolve_pattern_top(&arm.pat, PatternSource::Match); + walk_list!(this, visit_expr, &arm.guard); + this.visit_expr(&arm.body); + }); + } + + /// Arising from `source`, resolve a top level pattern. + fn resolve_pattern_top(&mut self, pat: &'ast Pat, pat_src: PatternSource) { + let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())]; + self.resolve_pattern(pat, pat_src, &mut bindings); + } + + fn resolve_pattern( + &mut self, + pat: &'ast Pat, + pat_src: PatternSource, + bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>, + ) { + // We walk the pattern before declaring the pattern's inner bindings, + // so that we avoid resolving a literal expression to a binding defined + // by the pattern. + visit::walk_pat(self, pat); + self.resolve_pattern_inner(pat, pat_src, bindings); + // This has to happen *after* we determine which pat_idents are variants: + self.check_consistent_bindings_top(pat); + } + + /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`. + /// + /// ### `bindings` + /// + /// A stack of sets of bindings accumulated. + /// + /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should + /// be interpreted as re-binding an already bound binding. This results in an error. + /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result + /// in reusing this binding rather than creating a fresh one. + /// + /// When called at the top level, the stack must have a single element + /// with `PatBound::Product`. Otherwise, pushing to the stack happens as + /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs + /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`. + /// When each `p_i` has been dealt with, the top set is merged with its parent. + /// When a whole or-pattern has been dealt with, the thing happens. + /// + /// See the implementation and `fresh_binding` for more details. + fn resolve_pattern_inner( + &mut self, + pat: &Pat, + pat_src: PatternSource, + bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>, + ) { + // Visit all direct subpatterns of this pattern. + pat.walk(&mut |pat| { + debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind); + match pat.kind { + PatKind::Ident(bmode, ident, ref sub) => { + // First try to resolve the identifier as some existing entity, + // then fall back to a fresh binding. + let has_sub = sub.is_some(); + let res = self + .try_resolve_as_non_binding(pat_src, bmode, ident, has_sub) + .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings)); + self.r.record_partial_res(pat.id, PartialRes::new(res)); + self.r.record_pat_span(pat.id, pat.span); + } + PatKind::TupleStruct(ref qself, ref path, ref sub_patterns) => { + self.smart_resolve_path( + pat.id, + qself.as_ref(), + path, + PathSource::TupleStruct( + pat.span, + self.r.arenas.alloc_pattern_spans(sub_patterns.iter().map(|p| p.span)), + ), + ); + } + PatKind::Path(ref qself, ref path) => { + self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat); + } + PatKind::Struct(ref qself, ref path, ..) => { + self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Struct); + } + PatKind::Or(ref ps) => { + // Add a new set of bindings to the stack. `Or` here records that when a + // binding already exists in this set, it should not result in an error because + // `V1(a) | V2(a)` must be allowed and are checked for consistency later. + bindings.push((PatBoundCtx::Or, Default::default())); + for p in ps { + // Now we need to switch back to a product context so that each + // part of the or-pattern internally rejects already bound names. + // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad. + bindings.push((PatBoundCtx::Product, Default::default())); + self.resolve_pattern_inner(p, pat_src, bindings); + // Move up the non-overlapping bindings to the or-pattern. + // Existing bindings just get "merged". + let collected = bindings.pop().unwrap().1; + bindings.last_mut().unwrap().1.extend(collected); + } + // This or-pattern itself can itself be part of a product, + // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`. + // Both cases bind `a` again in a product pattern and must be rejected. + let collected = bindings.pop().unwrap().1; + bindings.last_mut().unwrap().1.extend(collected); + + // Prevent visiting `ps` as we've already done so above. + return false; + } + _ => {} + } + true + }); + } + + fn fresh_binding( + &mut self, + ident: Ident, + pat_id: NodeId, + pat_src: PatternSource, + bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>, + ) -> Res { + // Add the binding to the local ribs, if it doesn't already exist in the bindings map. + // (We must not add it if it's in the bindings map because that breaks the assumptions + // later passes make about or-patterns.) + let ident = ident.normalize_to_macro_rules(); + + let mut bound_iter = bindings.iter().filter(|(_, set)| set.contains(&ident)); + // Already bound in a product pattern? e.g. `(a, a)` which is not allowed. + let already_bound_and = bound_iter.clone().any(|(ctx, _)| *ctx == PatBoundCtx::Product); + // Already bound in an or-pattern? e.g. `V1(a) | V2(a)`. + // This is *required* for consistency which is checked later. + let already_bound_or = bound_iter.any(|(ctx, _)| *ctx == PatBoundCtx::Or); + + if already_bound_and { + // Overlap in a product pattern somewhere; report an error. + use ResolutionError::*; + let error = match pat_src { + // `fn f(a: u8, a: u8)`: + PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList, + // `Variant(a, a)`: + _ => IdentifierBoundMoreThanOnceInSamePattern, + }; + self.report_error(ident.span, error(ident.name)); + } + + // Record as bound if it's valid: + let ident_valid = ident.name != kw::Empty; + if ident_valid { + bindings.last_mut().unwrap().1.insert(ident); + } + + if already_bound_or { + // `Variant1(a) | Variant2(a)`, ok + // Reuse definition from the first `a`. + self.innermost_rib_bindings(ValueNS)[&ident] + } else { + let res = Res::Local(pat_id); + if ident_valid { + // A completely fresh binding add to the set if it's valid. + self.innermost_rib_bindings(ValueNS).insert(ident, res); + } + res + } + } + + fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap<Res> { + &mut self.ribs[ns].last_mut().unwrap().bindings + } + + fn try_resolve_as_non_binding( + &mut self, + pat_src: PatternSource, + bm: BindingMode, + ident: Ident, + has_sub: bool, + ) -> Option<Res> { + // An immutable (no `mut`) by-value (no `ref`) binding pattern without + // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could + // also be interpreted as a path to e.g. a constant, variant, etc. + let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Not); + + let ls_binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS)?; + let (res, binding) = match ls_binding { + LexicalScopeBinding::Item(binding) + if is_syntactic_ambiguity && binding.is_ambiguity() => + { + // For ambiguous bindings we don't know all their definitions and cannot check + // whether they can be shadowed by fresh bindings or not, so force an error. + // issues/33118#issuecomment-233962221 (see below) still applies here, + // but we have to ignore it for backward compatibility. + self.r.record_use(ident, binding, false); + return None; + } + LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)), + LexicalScopeBinding::Res(res) => (res, None), + }; + + match res { + Res::SelfCtor(_) // See #70549. + | Res::Def( + DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::ConstParam, + _, + ) if is_syntactic_ambiguity => { + // Disambiguate in favor of a unit struct/variant or constant pattern. + if let Some(binding) = binding { + self.r.record_use(ident, binding, false); + } + Some(res) + } + Res::Def(DefKind::Ctor(..) | DefKind::Const | DefKind::Static(_), _) => { + // This is unambiguously a fresh binding, either syntactically + // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves + // to something unusable as a pattern (e.g., constructor function), + // but we still conservatively report an error, see + // issues/33118#issuecomment-233962221 for one reason why. + let binding = binding.expect("no binding for a ctor or static"); + self.report_error( + ident.span, + ResolutionError::BindingShadowsSomethingUnacceptable { + shadowing_binding: pat_src, + name: ident.name, + participle: if binding.is_import() { "imported" } else { "defined" }, + article: binding.res().article(), + shadowed_binding: binding.res(), + shadowed_binding_span: binding.span, + }, + ); + None + } + Res::Def(DefKind::ConstParam, def_id) => { + // Same as for DefKind::Const above, but here, `binding` is `None`, so we + // have to construct the error differently + self.report_error( + ident.span, + ResolutionError::BindingShadowsSomethingUnacceptable { + shadowing_binding: pat_src, + name: ident.name, + participle: "defined", + article: res.article(), + shadowed_binding: res, + shadowed_binding_span: self.r.opt_span(def_id).expect("const parameter defined outside of local crate"), + } + ); + None + } + Res::Def(DefKind::Fn, _) | Res::Local(..) | Res::Err => { + // These entities are explicitly allowed to be shadowed by fresh bindings. + None + } + Res::SelfCtor(_) => { + // We resolve `Self` in pattern position as an ident sometimes during recovery, + // so delay a bug instead of ICEing. + self.r.session.delay_span_bug( + ident.span, + "unexpected `SelfCtor` in pattern, expected identifier" + ); + None + } + _ => span_bug!( + ident.span, + "unexpected resolution for an identifier in pattern: {:?}", + res, + ), + } + } + + // High-level and context dependent path resolution routine. + // Resolves the path and records the resolution into definition map. + // If resolution fails tries several techniques to find likely + // resolution candidates, suggest imports or other help, and report + // errors in user friendly way. + fn smart_resolve_path( + &mut self, + id: NodeId, + qself: Option<&QSelf>, + path: &Path, + source: PathSource<'ast>, + ) { + self.smart_resolve_path_fragment( + qself, + &Segment::from_path(path), + source, + Finalize::new(id, path.span), + ); + } + + fn smart_resolve_path_fragment( + &mut self, + qself: Option<&QSelf>, + path: &[Segment], + source: PathSource<'ast>, + finalize: Finalize, + ) -> PartialRes { + tracing::debug!( + "smart_resolve_path_fragment(qself={:?}, path={:?}, finalize={:?})", + qself, + path, + finalize, + ); + let ns = source.namespace(); + + let Finalize { node_id, path_span, .. } = finalize; + let report_errors = |this: &mut Self, res: Option<Res>| { + if this.should_report_errs() { + let (err, candidates) = + this.smart_resolve_report_errors(path, path_span, source, res); + + let def_id = this.parent_scope.module.nearest_parent_mod(); + let instead = res.is_some(); + let suggestion = + if res.is_none() { this.report_missing_type_error(path) } else { None }; + + this.r.use_injections.push(UseError { + err, + candidates, + def_id, + instead, + suggestion, + path: path.into(), + }); + } + + PartialRes::new(Res::Err) + }; + + // For paths originating from calls (like in `HashMap::new()`), tries + // to enrich the plain `failed to resolve: ...` message with hints + // about possible missing imports. + // + // Similar thing, for types, happens in `report_errors` above. + let report_errors_for_call = |this: &mut Self, parent_err: Spanned<ResolutionError<'a>>| { + if !source.is_call() { + return Some(parent_err); + } + + // Before we start looking for candidates, we have to get our hands + // on the type user is trying to perform invocation on; basically: + // we're transforming `HashMap::new` into just `HashMap`. + let path = match path.split_last() { + Some((_, path)) if !path.is_empty() => path, + _ => return Some(parent_err), + }; + + let (mut err, candidates) = + this.smart_resolve_report_errors(path, path_span, PathSource::Type, None); + + if candidates.is_empty() { + err.cancel(); + return Some(parent_err); + } + + // There are two different error messages user might receive at + // this point: + // - E0412 cannot find type `{}` in this scope + // - E0433 failed to resolve: use of undeclared type or module `{}` + // + // The first one is emitted for paths in type-position, and the + // latter one - for paths in expression-position. + // + // Thus (since we're in expression-position at this point), not to + // confuse the user, we want to keep the *message* from E0432 (so + // `parent_err`), but we want *hints* from E0412 (so `err`). + // + // And that's what happens below - we're just mixing both messages + // into a single one. + let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node); + + err.message = take(&mut parent_err.message); + err.code = take(&mut parent_err.code); + err.children = take(&mut parent_err.children); + + parent_err.cancel(); + + let def_id = this.parent_scope.module.nearest_parent_mod(); + + if this.should_report_errs() { + this.r.use_injections.push(UseError { + err, + candidates, + def_id, + instead: false, + suggestion: None, + path: path.into(), + }); + } else { + err.cancel(); + } + + // We don't return `Some(parent_err)` here, because the error will + // be already printed as part of the `use` injections + None + }; + + let partial_res = match self.resolve_qpath_anywhere( + qself, + path, + ns, + path_span, + source.defer_to_typeck(), + finalize, + ) { + Ok(Some(partial_res)) if partial_res.unresolved_segments() == 0 => { + if source.is_expected(partial_res.base_res()) || partial_res.base_res() == Res::Err + { + partial_res + } else { + report_errors(self, Some(partial_res.base_res())) + } + } + + Ok(Some(partial_res)) if source.defer_to_typeck() => { + // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B` + // or `<T>::A::B`. If `B` should be resolved in value namespace then + // it needs to be added to the trait map. + if ns == ValueNS { + let item_name = path.last().unwrap().ident; + let traits = self.traits_in_scope(item_name, ns); + self.r.trait_map.insert(node_id, traits); + } + + if PrimTy::from_name(path[0].ident.name).is_some() { + let mut std_path = Vec::with_capacity(1 + path.len()); + + std_path.push(Segment::from_ident(Ident::with_dummy_span(sym::std))); + std_path.extend(path); + if let PathResult::Module(_) | PathResult::NonModule(_) = + self.resolve_path(&std_path, Some(ns), None) + { + // Check if we wrote `str::from_utf8` instead of `std::str::from_utf8` + let item_span = + path.iter().last().map_or(path_span, |segment| segment.ident.span); + + self.r.confused_type_with_std_module.insert(item_span, path_span); + self.r.confused_type_with_std_module.insert(path_span, path_span); + } + } + + partial_res + } + + Err(err) => { + if let Some(err) = report_errors_for_call(self, err) { + self.report_error(err.span, err.node); + } + + PartialRes::new(Res::Err) + } + + _ => report_errors(self, None), + }; + + if !matches!(source, PathSource::TraitItem(..)) { + // Avoid recording definition of `A::B` in `<T as A>::B::C`. + self.r.record_partial_res(node_id, partial_res); + self.resolve_elided_lifetimes_in_path(node_id, partial_res, path, source, path_span); + } + + partial_res + } + + fn self_type_is_available(&mut self) -> bool { + let binding = self + .maybe_resolve_ident_in_lexical_scope(Ident::with_dummy_span(kw::SelfUpper), TypeNS); + if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false } + } + + fn self_value_is_available(&mut self, self_span: Span) -> bool { + let ident = Ident::new(kw::SelfLower, self_span); + let binding = self.maybe_resolve_ident_in_lexical_scope(ident, ValueNS); + if let Some(LexicalScopeBinding::Res(res)) = binding { res != Res::Err } else { false } + } + + /// A wrapper around [`Resolver::report_error`]. + /// + /// This doesn't emit errors for function bodies if this is rustdoc. + fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) { + if self.should_report_errs() { + self.r.report_error(span, resolution_error); + } + } + + #[inline] + /// If we're actually rustdoc then avoid giving a name resolution error for `cfg()` items. + fn should_report_errs(&self) -> bool { + !(self.r.session.opts.actually_rustdoc && self.in_func_body) + } + + // Resolve in alternative namespaces if resolution in the primary namespace fails. + fn resolve_qpath_anywhere( + &mut self, + qself: Option<&QSelf>, + path: &[Segment], + primary_ns: Namespace, + span: Span, + defer_to_typeck: bool, + finalize: Finalize, + ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> { + let mut fin_res = None; + + for (i, &ns) in [primary_ns, TypeNS, ValueNS].iter().enumerate() { + if i == 0 || ns != primary_ns { + match self.resolve_qpath(qself, path, ns, finalize)? { + Some(partial_res) + if partial_res.unresolved_segments() == 0 || defer_to_typeck => + { + return Ok(Some(partial_res)); + } + partial_res => { + if fin_res.is_none() { + fin_res = partial_res; + } + } + } + } + } + + assert!(primary_ns != MacroNS); + + if qself.is_none() { + let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident); + let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None }; + if let Ok((_, res)) = + self.r.resolve_macro_path(&path, None, &self.parent_scope, false, false) + { + return Ok(Some(PartialRes::new(res))); + } + } + + Ok(fin_res) + } + + /// Handles paths that may refer to associated items. + fn resolve_qpath( + &mut self, + qself: Option<&QSelf>, + path: &[Segment], + ns: Namespace, + finalize: Finalize, + ) -> Result<Option<PartialRes>, Spanned<ResolutionError<'a>>> { + debug!( + "resolve_qpath(qself={:?}, path={:?}, ns={:?}, finalize={:?})", + qself, path, ns, finalize, + ); + + if let Some(qself) = qself { + if qself.position == 0 { + // This is a case like `<T>::B`, where there is no + // trait to resolve. In that case, we leave the `B` + // segment to be resolved by type-check. + return Ok(Some(PartialRes::with_unresolved_segments( + Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()), + path.len(), + ))); + } + + // Make sure `A::B` in `<T as A::B>::C` is a trait item. + // + // Currently, `path` names the full item (`A::B::C`, in + // our example). so we extract the prefix of that that is + // the trait (the slice upto and including + // `qself.position`). And then we recursively resolve that, + // but with `qself` set to `None`. + let ns = if qself.position + 1 == path.len() { ns } else { TypeNS }; + let partial_res = self.smart_resolve_path_fragment( + None, + &path[..=qself.position], + PathSource::TraitItem(ns), + Finalize::with_root_span(finalize.node_id, finalize.path_span, qself.path_span), + ); + + // The remaining segments (the `C` in our example) will + // have to be resolved by type-check, since that requires doing + // trait resolution. + return Ok(Some(PartialRes::with_unresolved_segments( + partial_res.base_res(), + partial_res.unresolved_segments() + path.len() - qself.position - 1, + ))); + } + + let result = match self.resolve_path(&path, Some(ns), Some(finalize)) { + PathResult::NonModule(path_res) => path_res, + PathResult::Module(ModuleOrUniformRoot::Module(module)) if !module.is_normal() => { + PartialRes::new(module.res().unwrap()) + } + // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we + // don't report an error right away, but try to fallback to a primitive type. + // So, we are still able to successfully resolve something like + // + // use std::u8; // bring module u8 in scope + // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8 + // u8::max_value() // OK, resolves to associated function <u8>::max_value, + // // not to non-existent std::u8::max_value + // } + // + // Such behavior is required for backward compatibility. + // The same fallback is used when `a` resolves to nothing. + PathResult::Module(ModuleOrUniformRoot::Module(_)) | PathResult::Failed { .. } + if (ns == TypeNS || path.len() > 1) + && PrimTy::from_name(path[0].ident.name).is_some() => + { + let prim = PrimTy::from_name(path[0].ident.name).unwrap(); + PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1) + } + PathResult::Module(ModuleOrUniformRoot::Module(module)) => { + PartialRes::new(module.res().unwrap()) + } + PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => { + return Err(respan(span, ResolutionError::FailedToResolve { label, suggestion })); + } + PathResult::Module(..) | PathResult::Failed { .. } => return Ok(None), + PathResult::Indeterminate => bug!("indeterminate path result in resolve_qpath"), + }; + + if path.len() > 1 + && result.base_res() != Res::Err + && path[0].ident.name != kw::PathRoot + && path[0].ident.name != kw::DollarCrate + { + let unqualified_result = { + match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) { + PathResult::NonModule(path_res) => path_res.base_res(), + PathResult::Module(ModuleOrUniformRoot::Module(module)) => { + module.res().unwrap() + } + _ => return Ok(Some(result)), + } + }; + if result.base_res() == unqualified_result { + let lint = lint::builtin::UNUSED_QUALIFICATIONS; + self.r.lint_buffer.buffer_lint( + lint, + finalize.node_id, + finalize.path_span, + "unnecessary qualification", + ) + } + } + + Ok(Some(result)) + } + + fn with_resolved_label(&mut self, label: Option<Label>, id: NodeId, f: impl FnOnce(&mut Self)) { + if let Some(label) = label { + if label.ident.as_str().as_bytes()[1] != b'_' { + self.diagnostic_metadata.unused_labels.insert(id, label.ident.span); + } + + if let Ok((_, orig_span)) = self.resolve_label(label.ident) { + diagnostics::signal_label_shadowing(self.r.session, orig_span, label.ident) + } + + self.with_label_rib(NormalRibKind, |this| { + let ident = label.ident.normalize_to_macro_rules(); + this.label_ribs.last_mut().unwrap().bindings.insert(ident, id); + f(this); + }); + } else { + f(self); + } + } + + fn resolve_labeled_block(&mut self, label: Option<Label>, id: NodeId, block: &'ast Block) { + self.with_resolved_label(label, id, |this| this.visit_block(block)); + } + + fn resolve_block(&mut self, block: &'ast Block) { + debug!("(resolving block) entering block"); + // Move down in the graph, if there's an anonymous module rooted here. + let orig_module = self.parent_scope.module; + let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference + + let mut num_macro_definition_ribs = 0; + if let Some(anonymous_module) = anonymous_module { + debug!("(resolving block) found anonymous module, moving down"); + self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module))); + self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module))); + self.parent_scope.module = anonymous_module; + } else { + self.ribs[ValueNS].push(Rib::new(NormalRibKind)); + } + + let prev = self.diagnostic_metadata.current_block_could_be_bare_struct_literal.take(); + if let (true, [Stmt { kind: StmtKind::Expr(expr), .. }]) = + (block.could_be_bare_literal, &block.stmts[..]) + && let ExprKind::Type(..) = expr.kind + { + self.diagnostic_metadata.current_block_could_be_bare_struct_literal = + Some(block.span); + } + // Descend into the block. + for stmt in &block.stmts { + if let StmtKind::Item(ref item) = stmt.kind + && let ItemKind::MacroDef(..) = item.kind { + num_macro_definition_ribs += 1; + let res = self.r.local_def_id(item.id).to_def_id(); + self.ribs[ValueNS].push(Rib::new(MacroDefinition(res))); + self.label_ribs.push(Rib::new(MacroDefinition(res))); + } + + self.visit_stmt(stmt); + } + self.diagnostic_metadata.current_block_could_be_bare_struct_literal = prev; + + // Move back up. + self.parent_scope.module = orig_module; + for _ in 0..num_macro_definition_ribs { + self.ribs[ValueNS].pop(); + self.label_ribs.pop(); + } + self.ribs[ValueNS].pop(); + if anonymous_module.is_some() { + self.ribs[TypeNS].pop(); + } + debug!("(resolving block) leaving block"); + } + + fn resolve_anon_const(&mut self, constant: &'ast AnonConst, is_repeat: IsRepeatExpr) { + debug!("resolve_anon_const {:?} is_repeat: {:?}", constant, is_repeat); + self.with_constant_rib( + is_repeat, + if constant.value.is_potential_trivial_const_param() { + HasGenericParams::Yes + } else { + HasGenericParams::No + }, + None, + |this| visit::walk_anon_const(this, constant), + ); + } + + fn resolve_inline_const(&mut self, constant: &'ast AnonConst) { + debug!("resolve_anon_const {constant:?}"); + self.with_constant_rib(IsRepeatExpr::No, HasGenericParams::Yes, None, |this| { + visit::walk_anon_const(this, constant); + }); + } + + fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) { + // First, record candidate traits for this expression if it could + // result in the invocation of a method call. + + self.record_candidate_traits_for_expr_if_necessary(expr); + + // Next, resolve the node. + match expr.kind { + ExprKind::Path(ref qself, ref path) => { + self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent)); + visit::walk_expr(self, expr); + } + + ExprKind::Struct(ref se) => { + self.smart_resolve_path(expr.id, se.qself.as_ref(), &se.path, PathSource::Struct); + visit::walk_expr(self, expr); + } + + ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => { + match self.resolve_label(label.ident) { + Ok((node_id, _)) => { + // Since this res is a label, it is never read. + self.r.label_res_map.insert(expr.id, node_id); + self.diagnostic_metadata.unused_labels.remove(&node_id); + } + Err(error) => { + self.report_error(label.ident.span, error); + } + } + + // visit `break` argument if any + visit::walk_expr(self, expr); + } + + ExprKind::Break(None, Some(ref e)) => { + // We use this instead of `visit::walk_expr` to keep the parent expr around for + // better diagnostics. + self.resolve_expr(e, Some(&expr)); + } + + ExprKind::Let(ref pat, ref scrutinee, _) => { + self.visit_expr(scrutinee); + self.resolve_pattern_top(pat, PatternSource::Let); + } + + ExprKind::If(ref cond, ref then, ref opt_else) => { + self.with_rib(ValueNS, NormalRibKind, |this| { + let old = this.diagnostic_metadata.in_if_condition.replace(cond); + this.visit_expr(cond); + this.diagnostic_metadata.in_if_condition = old; + this.visit_block(then); + }); + if let Some(expr) = opt_else { + self.visit_expr(expr); + } + } + + ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block), + + ExprKind::While(ref cond, ref block, label) => { + self.with_resolved_label(label, expr.id, |this| { + this.with_rib(ValueNS, NormalRibKind, |this| { + let old = this.diagnostic_metadata.in_if_condition.replace(cond); + this.visit_expr(cond); + this.diagnostic_metadata.in_if_condition = old; + this.visit_block(block); + }) + }); + } + + ExprKind::ForLoop(ref pat, ref iter_expr, ref block, label) => { + self.visit_expr(iter_expr); + self.with_rib(ValueNS, NormalRibKind, |this| { + this.resolve_pattern_top(pat, PatternSource::For); + this.resolve_labeled_block(label, expr.id, block); + }); + } + + ExprKind::Block(ref block, label) => self.resolve_labeled_block(label, block.id, block), + + // Equivalent to `visit::walk_expr` + passing some context to children. + ExprKind::Field(ref subexpression, _) => { + self.resolve_expr(subexpression, Some(expr)); + } + ExprKind::MethodCall(ref segment, ref arguments, _) => { + let mut arguments = arguments.iter(); + self.resolve_expr(arguments.next().unwrap(), Some(expr)); + for argument in arguments { + self.resolve_expr(argument, None); + } + self.visit_path_segment(expr.span, segment); + } + + ExprKind::Call(ref callee, ref arguments) => { + self.resolve_expr(callee, Some(expr)); + let const_args = self.r.legacy_const_generic_args(callee).unwrap_or_default(); + for (idx, argument) in arguments.iter().enumerate() { + // Constant arguments need to be treated as AnonConst since + // that is how they will be later lowered to HIR. + if const_args.contains(&idx) { + self.with_constant_rib( + IsRepeatExpr::No, + if argument.is_potential_trivial_const_param() { + HasGenericParams::Yes + } else { + HasGenericParams::No + }, + None, + |this| { + this.resolve_expr(argument, None); + }, + ); + } else { + self.resolve_expr(argument, None); + } + } + } + ExprKind::Type(ref type_expr, ref ty) => { + // `ParseSess::type_ascription_path_suggestions` keeps spans of colon tokens in + // type ascription. Here we are trying to retrieve the span of the colon token as + // well, but only if it's written without spaces `expr:Ty` and therefore confusable + // with `expr::Ty`, only in this case it will match the span from + // `type_ascription_path_suggestions`. + self.diagnostic_metadata + .current_type_ascription + .push(type_expr.span.between(ty.span)); + visit::walk_expr(self, expr); + self.diagnostic_metadata.current_type_ascription.pop(); + } + // `async |x| ...` gets desugared to `|x| future_from_generator(|| ...)`, so we need to + // resolve the arguments within the proper scopes so that usages of them inside the + // closure are detected as upvars rather than normal closure arg usages. + ExprKind::Closure(_, _, Async::Yes { .. }, _, ref fn_decl, ref body, _span) => { + self.with_rib(ValueNS, NormalRibKind, |this| { + this.with_label_rib(ClosureOrAsyncRibKind, |this| { + // Resolve arguments: + this.resolve_params(&fn_decl.inputs); + // No need to resolve return type -- + // the outer closure return type is `FnRetTy::Default`. + + // Now resolve the inner closure + { + // No need to resolve arguments: the inner closure has none. + // Resolve the return type: + visit::walk_fn_ret_ty(this, &fn_decl.output); + // Resolve the body + this.visit_expr(body); + } + }) + }); + } + // For closures, ClosureOrAsyncRibKind is added in visit_fn + ExprKind::Closure(ClosureBinder::For { ref generic_params, span }, ..) => { + self.with_generic_param_rib( + &generic_params, + NormalRibKind, + LifetimeRibKind::Generics { + binder: expr.id, + kind: LifetimeBinderKind::Closure, + span, + }, + |this| visit::walk_expr(this, expr), + ); + } + ExprKind::Closure(..) => visit::walk_expr(self, expr), + ExprKind::Async(..) => { + self.with_label_rib(ClosureOrAsyncRibKind, |this| visit::walk_expr(this, expr)); + } + ExprKind::Repeat(ref elem, ref ct) => { + self.visit_expr(elem); + self.with_lifetime_rib(LifetimeRibKind::AnonConst, |this| { + this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| { + this.resolve_anon_const(ct, IsRepeatExpr::Yes) + }) + }); + } + ExprKind::ConstBlock(ref ct) => { + self.resolve_inline_const(ct); + } + ExprKind::Index(ref elem, ref idx) => { + self.resolve_expr(elem, Some(expr)); + self.visit_expr(idx); + } + _ => { + visit::walk_expr(self, expr); + } + } + } + + fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &'ast Expr) { + match expr.kind { + ExprKind::Field(_, ident) => { + // FIXME(#6890): Even though you can't treat a method like a + // field, we need to add any trait methods we find that match + // the field name so that we can do some nice error reporting + // later on in typeck. + let traits = self.traits_in_scope(ident, ValueNS); + self.r.trait_map.insert(expr.id, traits); + } + ExprKind::MethodCall(ref segment, ..) => { + debug!("(recording candidate traits for expr) recording traits for {}", expr.id); + let traits = self.traits_in_scope(segment.ident, ValueNS); + self.r.trait_map.insert(expr.id, traits); + } + _ => { + // Nothing to do. + } + } + } + + fn traits_in_scope(&mut self, ident: Ident, ns: Namespace) -> Vec<TraitCandidate> { + self.r.traits_in_scope( + self.current_trait_ref.as_ref().map(|(module, _)| *module), + &self.parent_scope, + ident.span.ctxt(), + Some((ident.name, ns)), + ) + } +} + +struct LifetimeCountVisitor<'a, 'b> { + r: &'b mut Resolver<'a>, +} + +/// Walks the whole crate in DFS order, visiting each item, counting the declared number of +/// lifetime generic parameters. +impl<'ast> Visitor<'ast> for LifetimeCountVisitor<'_, '_> { + fn visit_item(&mut self, item: &'ast Item) { + match &item.kind { + ItemKind::TyAlias(box TyAlias { ref generics, .. }) + | ItemKind::Fn(box Fn { ref generics, .. }) + | ItemKind::Enum(_, ref generics) + | ItemKind::Struct(_, ref generics) + | ItemKind::Union(_, ref generics) + | ItemKind::Impl(box Impl { ref generics, .. }) + | ItemKind::Trait(box Trait { ref generics, .. }) + | ItemKind::TraitAlias(ref generics, _) => { + let def_id = self.r.local_def_id(item.id); + let count = generics + .params + .iter() + .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. })) + .count(); + self.r.item_generics_num_lifetimes.insert(def_id, count); + } + + ItemKind::Mod(..) + | ItemKind::ForeignMod(..) + | ItemKind::Static(..) + | ItemKind::Const(..) + | ItemKind::Use(..) + | ItemKind::ExternCrate(..) + | ItemKind::MacroDef(..) + | ItemKind::GlobalAsm(..) + | ItemKind::MacCall(..) => {} + } + visit::walk_item(self, item) + } +} + +impl<'a> Resolver<'a> { + pub(crate) fn late_resolve_crate(&mut self, krate: &Crate) { + visit::walk_crate(&mut LifetimeCountVisitor { r: self }, krate); + let mut late_resolution_visitor = LateResolutionVisitor::new(self); + visit::walk_crate(&mut late_resolution_visitor, krate); + for (id, span) in late_resolution_visitor.diagnostic_metadata.unused_labels.iter() { + self.lint_buffer.buffer_lint(lint::builtin::UNUSED_LABELS, *id, *span, "unused label"); + } + } +} |