| //! "Collection" is the process of determining the type and other external |
| //! details of each item in Rust. Collection is specifically concerned |
| //! with *inter-procedural* things -- for example, for a function |
| //! definition, collection will figure out the type and signature of the |
| //! function, but it will not visit the *body* of the function in any way, |
| //! nor examine type annotations on local variables (that's the job of |
| //! type *checking*). |
| //! |
| //! Collecting is ultimately defined by a bundle of queries that |
| //! inquire after various facts about the items in the crate (e.g., |
| //! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function |
| //! for the full set. |
| //! |
| //! At present, however, we do run collection across all items in the |
| //! crate as a kind of pass. This should eventually be factored away. |
| |
| use std::cell::Cell; |
| use std::iter; |
| use std::ops::Bound; |
| |
| use rustc_ast::Recovered; |
| use rustc_data_structures::captures::Captures; |
| use rustc_data_structures::fx::{FxHashSet, FxIndexMap}; |
| use rustc_data_structures::unord::UnordMap; |
| use rustc_errors::{ |
| Applicability, Diag, DiagCtxtHandle, E0228, ErrorGuaranteed, StashKey, struct_span_code_err, |
| }; |
| use rustc_hir::def::DefKind; |
| use rustc_hir::def_id::{DefId, LocalDefId}; |
| use rustc_hir::intravisit::{self, Visitor, walk_generics}; |
| use rustc_hir::{self as hir, GenericParamKind, Node}; |
| use rustc_infer::infer::{InferCtxt, TyCtxtInferExt}; |
| use rustc_infer::traits::ObligationCause; |
| use rustc_middle::hir::nested_filter; |
| use rustc_middle::query::Providers; |
| use rustc_middle::ty::util::{Discr, IntTypeExt}; |
| use rustc_middle::ty::{self, AdtKind, Const, IsSuggestable, Ty, TyCtxt}; |
| use rustc_middle::{bug, span_bug}; |
| use rustc_span::symbol::{Ident, Symbol, kw, sym}; |
| use rustc_span::{DUMMY_SP, Span}; |
| use rustc_target::spec::abi; |
| use rustc_trait_selection::error_reporting::traits::suggestions::NextTypeParamName; |
| use rustc_trait_selection::infer::InferCtxtExt; |
| use rustc_trait_selection::traits::ObligationCtxt; |
| use tracing::{debug, instrument}; |
| |
| use crate::check::intrinsic::intrinsic_operation_unsafety; |
| use crate::errors; |
| use crate::hir_ty_lowering::{HirTyLowerer, RegionInferReason}; |
| |
| pub(crate) mod dump; |
| mod generics_of; |
| mod item_bounds; |
| mod predicates_of; |
| mod resolve_bound_vars; |
| mod type_of; |
| |
| /////////////////////////////////////////////////////////////////////////// |
| |
| pub fn provide(providers: &mut Providers) { |
| resolve_bound_vars::provide(providers); |
| *providers = Providers { |
| type_of: type_of::type_of, |
| type_of_opaque: type_of::type_of_opaque, |
| type_alias_is_lazy: type_of::type_alias_is_lazy, |
| item_bounds: item_bounds::item_bounds, |
| explicit_item_bounds: item_bounds::explicit_item_bounds, |
| item_super_predicates: item_bounds::item_super_predicates, |
| explicit_item_super_predicates: item_bounds::explicit_item_super_predicates, |
| item_non_self_assumptions: item_bounds::item_non_self_assumptions, |
| impl_super_outlives: item_bounds::impl_super_outlives, |
| generics_of: generics_of::generics_of, |
| predicates_of: predicates_of::predicates_of, |
| explicit_predicates_of: predicates_of::explicit_predicates_of, |
| explicit_super_predicates_of: predicates_of::explicit_super_predicates_of, |
| explicit_implied_predicates_of: predicates_of::explicit_implied_predicates_of, |
| explicit_supertraits_containing_assoc_item: |
| predicates_of::explicit_supertraits_containing_assoc_item, |
| trait_explicit_predicates_and_bounds: predicates_of::trait_explicit_predicates_and_bounds, |
| type_param_predicates: predicates_of::type_param_predicates, |
| trait_def, |
| adt_def, |
| fn_sig, |
| impl_trait_header, |
| coroutine_kind, |
| coroutine_for_closure, |
| is_type_alias_impl_trait, |
| rendered_precise_capturing_args, |
| ..*providers |
| }; |
| } |
| |
| /////////////////////////////////////////////////////////////////////////// |
| |
| /// Context specific to some particular item. This is what implements [`HirTyLowerer`]. |
| /// |
| /// # `ItemCtxt` vs `FnCtxt` |
| /// |
| /// `ItemCtxt` is primarily used to type-check item signatures and lower them |
| /// from HIR to their [`ty::Ty`] representation, which is exposed using [`HirTyLowerer`]. |
| /// It's also used for the bodies of items like structs where the body (the fields) |
| /// are just signatures. |
| /// |
| /// This is in contrast to `FnCtxt`, which is used to type-check bodies of |
| /// functions, closures, and `const`s -- anywhere that expressions and statements show up. |
| /// |
| /// An important thing to note is that `ItemCtxt` does no inference -- it has no [`InferCtxt`] -- |
| /// while `FnCtxt` does do inference. |
| /// |
| /// [`InferCtxt`]: rustc_infer::infer::InferCtxt |
| /// |
| /// # Trait predicates |
| /// |
| /// `ItemCtxt` has information about the predicates that are defined |
| /// on the trait. Unfortunately, this predicate information is |
| /// available in various different forms at various points in the |
| /// process. So we can't just store a pointer to e.g., the HIR or the |
| /// parsed ty form, we have to be more flexible. To this end, the |
| /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy |
| /// `probe_ty_param_bounds` requests, drawing the information from |
| /// the HIR (`hir::Generics`), recursively. |
| pub struct ItemCtxt<'tcx> { |
| tcx: TyCtxt<'tcx>, |
| item_def_id: LocalDefId, |
| tainted_by_errors: Cell<Option<ErrorGuaranteed>>, |
| } |
| |
| /////////////////////////////////////////////////////////////////////////// |
| |
| #[derive(Default)] |
| pub(crate) struct HirPlaceholderCollector(pub(crate) Vec<Span>); |
| |
| impl<'v> Visitor<'v> for HirPlaceholderCollector { |
| fn visit_ty(&mut self, t: &'v hir::Ty<'v>) { |
| if let hir::TyKind::Infer = t.kind { |
| self.0.push(t.span); |
| } |
| intravisit::walk_ty(self, t) |
| } |
| fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) { |
| match generic_arg { |
| hir::GenericArg::Infer(inf) => { |
| self.0.push(inf.span); |
| intravisit::walk_inf(self, inf); |
| } |
| hir::GenericArg::Type(t) => self.visit_ty(t), |
| _ => {} |
| } |
| } |
| fn visit_array_length(&mut self, length: &'v hir::ArrayLen<'v>) { |
| if let hir::ArrayLen::Infer(inf) = length { |
| self.0.push(inf.span); |
| } |
| intravisit::walk_array_len(self, length) |
| } |
| } |
| |
| pub struct CollectItemTypesVisitor<'tcx> { |
| pub tcx: TyCtxt<'tcx>, |
| } |
| |
| /// If there are any placeholder types (`_`), emit an error explaining that this is not allowed |
| /// and suggest adding type parameters in the appropriate place, taking into consideration any and |
| /// all already existing generic type parameters to avoid suggesting a name that is already in use. |
| pub(crate) fn placeholder_type_error<'tcx>( |
| cx: &dyn HirTyLowerer<'tcx>, |
| generics: Option<&hir::Generics<'_>>, |
| placeholder_types: Vec<Span>, |
| suggest: bool, |
| hir_ty: Option<&hir::Ty<'_>>, |
| kind: &'static str, |
| ) { |
| if placeholder_types.is_empty() { |
| return; |
| } |
| |
| placeholder_type_error_diag(cx, generics, placeholder_types, vec![], suggest, hir_ty, kind) |
| .emit(); |
| } |
| |
| pub(crate) fn placeholder_type_error_diag<'cx, 'tcx>( |
| cx: &'cx dyn HirTyLowerer<'tcx>, |
| generics: Option<&hir::Generics<'_>>, |
| placeholder_types: Vec<Span>, |
| additional_spans: Vec<Span>, |
| suggest: bool, |
| hir_ty: Option<&hir::Ty<'_>>, |
| kind: &'static str, |
| ) -> Diag<'cx> { |
| if placeholder_types.is_empty() { |
| return bad_placeholder(cx, additional_spans, kind); |
| } |
| |
| let params = generics.map(|g| g.params).unwrap_or_default(); |
| let type_name = params.next_type_param_name(None); |
| let mut sugg: Vec<_> = |
| placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect(); |
| |
| if let Some(generics) = generics { |
| if let Some(arg) = params.iter().find(|arg| { |
| matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. })) |
| }) { |
| // Account for `_` already present in cases like `struct S<_>(_);` and suggest |
| // `struct S<T>(T);` instead of `struct S<_, T>(T);`. |
| sugg.push((arg.span, (*type_name).to_string())); |
| } else if let Some(span) = generics.span_for_param_suggestion() { |
| // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`. |
| sugg.push((span, format!(", {type_name}"))); |
| } else { |
| sugg.push((generics.span, format!("<{type_name}>"))); |
| } |
| } |
| |
| let mut err = |
| bad_placeholder(cx, placeholder_types.into_iter().chain(additional_spans).collect(), kind); |
| |
| // Suggest, but only if it is not a function in const or static |
| if suggest { |
| let mut is_fn = false; |
| let mut is_const_or_static = false; |
| |
| if let Some(hir_ty) = hir_ty |
| && let hir::TyKind::BareFn(_) = hir_ty.kind |
| { |
| is_fn = true; |
| |
| // Check if parent is const or static |
| is_const_or_static = matches!( |
| cx.tcx().parent_hir_node(hir_ty.hir_id), |
| Node::Item(&hir::Item { |
| kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..), |
| .. |
| }) | Node::TraitItem(&hir::TraitItem { kind: hir::TraitItemKind::Const(..), .. }) |
| | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. }) |
| ); |
| } |
| |
| // if function is wrapped around a const or static, |
| // then don't show the suggestion |
| if !(is_fn && is_const_or_static) { |
| err.multipart_suggestion( |
| "use type parameters instead", |
| sugg, |
| Applicability::HasPlaceholders, |
| ); |
| } |
| } |
| |
| err |
| } |
| |
| fn reject_placeholder_type_signatures_in_item<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| item: &'tcx hir::Item<'tcx>, |
| ) { |
| let (generics, suggest) = match &item.kind { |
| hir::ItemKind::Union(_, generics) |
| | hir::ItemKind::Enum(_, generics) |
| | hir::ItemKind::TraitAlias(generics, _) |
| | hir::ItemKind::Trait(_, _, generics, ..) |
| | hir::ItemKind::Impl(hir::Impl { generics, .. }) |
| | hir::ItemKind::Struct(_, generics) => (generics, true), |
| hir::ItemKind::TyAlias(_, generics) => (generics, false), |
| // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type. |
| _ => return, |
| }; |
| |
| let mut visitor = HirPlaceholderCollector::default(); |
| visitor.visit_item(item); |
| |
| let icx = ItemCtxt::new(tcx, item.owner_id.def_id); |
| |
| placeholder_type_error( |
| icx.lowerer(), |
| Some(generics), |
| visitor.0, |
| suggest, |
| None, |
| item.kind.descr(), |
| ); |
| } |
| |
| impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> { |
| type NestedFilter = nested_filter::OnlyBodies; |
| |
| fn nested_visit_map(&mut self) -> Self::Map { |
| self.tcx.hir() |
| } |
| |
| fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) { |
| lower_item(self.tcx, item.item_id()); |
| reject_placeholder_type_signatures_in_item(self.tcx, item); |
| intravisit::walk_item(self, item); |
| } |
| |
| fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) { |
| for param in generics.params { |
| match param.kind { |
| hir::GenericParamKind::Lifetime { .. } => {} |
| hir::GenericParamKind::Type { default: Some(_), .. } => { |
| self.tcx.ensure().type_of(param.def_id); |
| } |
| hir::GenericParamKind::Type { .. } => {} |
| hir::GenericParamKind::Const { default, .. } => { |
| self.tcx.ensure().type_of(param.def_id); |
| if let Some(default) = default { |
| // need to store default and type of default |
| if let hir::ConstArgKind::Anon(ac) = default.kind { |
| self.tcx.ensure().type_of(ac.def_id); |
| } |
| self.tcx.ensure().const_param_default(param.def_id); |
| } |
| } |
| } |
| } |
| intravisit::walk_generics(self, generics); |
| } |
| |
| fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) { |
| if let hir::ExprKind::Closure(closure) = expr.kind { |
| self.tcx.ensure().generics_of(closure.def_id); |
| self.tcx.ensure().codegen_fn_attrs(closure.def_id); |
| // We do not call `type_of` for closures here as that |
| // depends on typecheck and would therefore hide |
| // any further errors in case one typeck fails. |
| } |
| intravisit::walk_expr(self, expr); |
| } |
| |
| /// Don't call `type_of` on opaque types, since that depends on type checking function bodies. |
| /// `check_item_type` ensures that it's called instead. |
| fn visit_opaque_ty(&mut self, opaque: &'tcx hir::OpaqueTy<'tcx>) { |
| let def_id = opaque.def_id; |
| self.tcx.ensure().generics_of(def_id); |
| self.tcx.ensure().predicates_of(def_id); |
| self.tcx.ensure().explicit_item_bounds(def_id); |
| self.tcx.ensure().explicit_item_super_predicates(def_id); |
| self.tcx.ensure().item_bounds(def_id); |
| self.tcx.ensure().item_super_predicates(def_id); |
| intravisit::walk_opaque_ty(self, opaque); |
| } |
| |
| fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) { |
| lower_trait_item(self.tcx, trait_item.trait_item_id()); |
| intravisit::walk_trait_item(self, trait_item); |
| } |
| |
| fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) { |
| lower_impl_item(self.tcx, impl_item.impl_item_id()); |
| intravisit::walk_impl_item(self, impl_item); |
| } |
| } |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // Utility types and common code for the above passes. |
| |
| fn bad_placeholder<'cx, 'tcx>( |
| cx: &'cx dyn HirTyLowerer<'tcx>, |
| mut spans: Vec<Span>, |
| kind: &'static str, |
| ) -> Diag<'cx> { |
| let kind = if kind.ends_with('s') { format!("{kind}es") } else { format!("{kind}s") }; |
| |
| spans.sort(); |
| cx.dcx().create_err(errors::PlaceholderNotAllowedItemSignatures { spans, kind }) |
| } |
| |
| impl<'tcx> ItemCtxt<'tcx> { |
| pub fn new(tcx: TyCtxt<'tcx>, item_def_id: LocalDefId) -> ItemCtxt<'tcx> { |
| ItemCtxt { tcx, item_def_id, tainted_by_errors: Cell::new(None) } |
| } |
| |
| pub fn lower_ty(&self, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> { |
| self.lowerer().lower_ty(hir_ty) |
| } |
| |
| pub fn hir_id(&self) -> hir::HirId { |
| self.tcx.local_def_id_to_hir_id(self.item_def_id) |
| } |
| |
| pub fn node(&self) -> hir::Node<'tcx> { |
| self.tcx.hir_node(self.hir_id()) |
| } |
| |
| fn check_tainted_by_errors(&self) -> Result<(), ErrorGuaranteed> { |
| match self.tainted_by_errors.get() { |
| Some(err) => Err(err), |
| None => Ok(()), |
| } |
| } |
| } |
| |
| impl<'tcx> HirTyLowerer<'tcx> for ItemCtxt<'tcx> { |
| fn tcx(&self) -> TyCtxt<'tcx> { |
| self.tcx |
| } |
| |
| fn dcx(&self) -> DiagCtxtHandle<'_> { |
| self.tcx.dcx().taintable_handle(&self.tainted_by_errors) |
| } |
| |
| fn item_def_id(&self) -> LocalDefId { |
| self.item_def_id |
| } |
| |
| fn re_infer(&self, span: Span, reason: RegionInferReason<'_>) -> ty::Region<'tcx> { |
| if let RegionInferReason::ObjectLifetimeDefault = reason { |
| let e = struct_span_code_err!( |
| self.dcx(), |
| span, |
| E0228, |
| "the lifetime bound for this object type cannot be deduced \ |
| from context; please supply an explicit bound" |
| ) |
| .emit(); |
| ty::Region::new_error(self.tcx(), e) |
| } else { |
| // This indicates an illegal lifetime in a non-assoc-trait position |
| ty::Region::new_error_with_message(self.tcx(), span, "unelided lifetime in signature") |
| } |
| } |
| |
| fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> { |
| Ty::new_error_with_message(self.tcx(), span, "bad placeholder type") |
| } |
| |
| fn ct_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Const<'tcx> { |
| ty::Const::new_error_with_message(self.tcx(), span, "bad placeholder constant") |
| } |
| |
| fn probe_ty_param_bounds( |
| &self, |
| span: Span, |
| def_id: LocalDefId, |
| assoc_name: Ident, |
| ) -> ty::EarlyBinder<'tcx, &'tcx [(ty::Clause<'tcx>, Span)]> { |
| self.tcx.at(span).type_param_predicates((self.item_def_id, def_id, assoc_name)) |
| } |
| |
| fn lower_assoc_ty( |
| &self, |
| span: Span, |
| item_def_id: DefId, |
| item_segment: &hir::PathSegment<'tcx>, |
| poly_trait_ref: ty::PolyTraitRef<'tcx>, |
| ) -> Ty<'tcx> { |
| if let Some(trait_ref) = poly_trait_ref.no_bound_vars() { |
| let item_args = self.lowerer().lower_generic_args_of_assoc_item( |
| span, |
| item_def_id, |
| item_segment, |
| trait_ref.args, |
| ); |
| Ty::new_projection_from_args(self.tcx(), item_def_id, item_args) |
| } else { |
| // There are no late-bound regions; we can just ignore the binder. |
| let (mut mpart_sugg, mut inferred_sugg) = (None, None); |
| let mut bound = String::new(); |
| |
| match self.node() { |
| hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => { |
| let item = self |
| .tcx |
| .hir() |
| .expect_item(self.tcx.hir().get_parent_item(self.hir_id()).def_id); |
| match &item.kind { |
| hir::ItemKind::Enum(_, generics) |
| | hir::ItemKind::Struct(_, generics) |
| | hir::ItemKind::Union(_, generics) => { |
| let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics); |
| let (lt_sp, sugg) = match generics.params { |
| [] => (generics.span, format!("<{lt_name}>")), |
| [bound, ..] => (bound.span.shrink_to_lo(), format!("{lt_name}, ")), |
| }; |
| mpart_sugg = Some(errors::AssociatedItemTraitUninferredGenericParamsMultipartSuggestion { |
| fspan: lt_sp, |
| first: sugg, |
| sspan: span.with_hi(item_segment.ident.span.lo()), |
| second: format!( |
| "{}::", |
| // Replace the existing lifetimes with a new named lifetime. |
| self.tcx.instantiate_bound_regions_uncached( |
| poly_trait_ref, |
| |_| { |
| ty::Region::new_early_param(self.tcx, ty::EarlyParamRegion { |
| index: 0, |
| name: Symbol::intern(<_name), |
| }) |
| } |
| ), |
| ), |
| }); |
| } |
| _ => {} |
| } |
| } |
| hir::Node::Item(hir::Item { |
| kind: |
| hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..), |
| .. |
| }) => {} |
| hir::Node::Item(_) |
| | hir::Node::ForeignItem(_) |
| | hir::Node::TraitItem(_) |
| | hir::Node::ImplItem(_) => { |
| inferred_sugg = Some(span.with_hi(item_segment.ident.span.lo())); |
| bound = format!( |
| "{}::", |
| // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`. |
| self.tcx.anonymize_bound_vars(poly_trait_ref).skip_binder(), |
| ); |
| } |
| _ => {} |
| } |
| Ty::new_error( |
| self.tcx(), |
| self.tcx().dcx().emit_err(errors::AssociatedItemTraitUninferredGenericParams { |
| span, |
| inferred_sugg, |
| bound, |
| mpart_sugg, |
| what: "type", |
| }), |
| ) |
| } |
| } |
| |
| fn probe_adt(&self, _span: Span, ty: Ty<'tcx>) -> Option<ty::AdtDef<'tcx>> { |
| // FIXME(#103640): Should we handle the case where `ty` is a projection? |
| ty.ty_adt_def() |
| } |
| |
| fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) { |
| // There's no place to record types from signatures? |
| } |
| |
| fn infcx(&self) -> Option<&InferCtxt<'tcx>> { |
| None |
| } |
| |
| fn lower_fn_sig( |
| &self, |
| decl: &hir::FnDecl<'tcx>, |
| generics: Option<&hir::Generics<'_>>, |
| hir_id: rustc_hir::HirId, |
| hir_ty: Option<&hir::Ty<'_>>, |
| ) -> (Vec<Ty<'tcx>>, Ty<'tcx>) { |
| let tcx = self.tcx(); |
| // We proactively collect all the inferred type params to emit a single error per fn def. |
| let mut visitor = HirPlaceholderCollector::default(); |
| let mut infer_replacements = vec![]; |
| |
| if let Some(generics) = generics { |
| walk_generics(&mut visitor, generics); |
| } |
| |
| let input_tys = decl |
| .inputs |
| .iter() |
| .enumerate() |
| .map(|(i, a)| { |
| if let hir::TyKind::Infer = a.kind { |
| if let Some(suggested_ty) = |
| self.lowerer().suggest_trait_fn_ty_for_impl_fn_infer(hir_id, Some(i)) |
| { |
| infer_replacements.push((a.span, suggested_ty.to_string())); |
| return Ty::new_error_with_message(tcx, a.span, suggested_ty.to_string()); |
| } |
| } |
| |
| // Only visit the type looking for `_` if we didn't fix the type above |
| visitor.visit_ty(a); |
| self.lowerer().lower_arg_ty(a, None) |
| }) |
| .collect(); |
| |
| let output_ty = match decl.output { |
| hir::FnRetTy::Return(output) => { |
| if let hir::TyKind::Infer = output.kind |
| && let Some(suggested_ty) = |
| self.lowerer().suggest_trait_fn_ty_for_impl_fn_infer(hir_id, None) |
| { |
| infer_replacements.push((output.span, suggested_ty.to_string())); |
| Ty::new_error_with_message(tcx, output.span, suggested_ty.to_string()) |
| } else { |
| visitor.visit_ty(output); |
| self.lower_ty(output) |
| } |
| } |
| hir::FnRetTy::DefaultReturn(..) => tcx.types.unit, |
| }; |
| |
| if !(visitor.0.is_empty() && infer_replacements.is_empty()) { |
| // We check for the presence of |
| // `ident_span` to not emit an error twice when we have `fn foo(_: fn() -> _)`. |
| |
| let mut diag = crate::collect::placeholder_type_error_diag( |
| self, |
| generics, |
| visitor.0, |
| infer_replacements.iter().map(|(s, _)| *s).collect(), |
| true, |
| hir_ty, |
| "function", |
| ); |
| |
| if !infer_replacements.is_empty() { |
| diag.multipart_suggestion( |
| format!( |
| "try replacing `_` with the type{} in the corresponding trait method signature", |
| rustc_errors::pluralize!(infer_replacements.len()), |
| ), |
| infer_replacements, |
| Applicability::MachineApplicable, |
| ); |
| } |
| |
| diag.emit(); |
| } |
| |
| (input_tys, output_ty) |
| } |
| } |
| |
| /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present. |
| fn get_new_lifetime_name<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| poly_trait_ref: ty::PolyTraitRef<'tcx>, |
| generics: &hir::Generics<'tcx>, |
| ) -> String { |
| let existing_lifetimes = tcx |
| .collect_referenced_late_bound_regions(poly_trait_ref) |
| .into_iter() |
| .filter_map(|lt| { |
| if let ty::BoundRegionKind::BrNamed(_, name) = lt { |
| Some(name.as_str().to_string()) |
| } else { |
| None |
| } |
| }) |
| .chain(generics.params.iter().filter_map(|param| { |
| if let hir::GenericParamKind::Lifetime { .. } = ¶m.kind { |
| Some(param.name.ident().as_str().to_string()) |
| } else { |
| None |
| } |
| })) |
| .collect::<FxHashSet<String>>(); |
| |
| let a_to_z_repeat_n = |n| { |
| (b'a'..=b'z').map(move |c| { |
| let mut s = '\''.to_string(); |
| s.extend(std::iter::repeat(char::from(c)).take(n)); |
| s |
| }) |
| }; |
| |
| // If all single char lifetime names are present, we wrap around and double the chars. |
| (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap() |
| } |
| |
| #[instrument(level = "debug", skip_all)] |
| fn lower_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) { |
| let it = tcx.hir().item(item_id); |
| debug!(item = %it.ident, id = %it.hir_id()); |
| let def_id = item_id.owner_id.def_id; |
| let icx = ItemCtxt::new(tcx, def_id); |
| |
| match &it.kind { |
| // These don't define types. |
| hir::ItemKind::ExternCrate(_) |
| | hir::ItemKind::Use(..) |
| | hir::ItemKind::Macro(..) |
| | hir::ItemKind::Mod(_) |
| | hir::ItemKind::GlobalAsm(_) => {} |
| hir::ItemKind::ForeignMod { items, .. } => { |
| for item in *items { |
| let item = tcx.hir().foreign_item(item.id); |
| tcx.ensure().generics_of(item.owner_id); |
| tcx.ensure().type_of(item.owner_id); |
| tcx.ensure().predicates_of(item.owner_id); |
| match item.kind { |
| hir::ForeignItemKind::Fn(..) => { |
| tcx.ensure().codegen_fn_attrs(item.owner_id); |
| tcx.ensure().fn_sig(item.owner_id) |
| } |
| hir::ForeignItemKind::Static(..) => { |
| tcx.ensure().codegen_fn_attrs(item.owner_id); |
| let mut visitor = HirPlaceholderCollector::default(); |
| visitor.visit_foreign_item(item); |
| placeholder_type_error( |
| icx.lowerer(), |
| None, |
| visitor.0, |
| false, |
| None, |
| "static variable", |
| ); |
| } |
| _ => (), |
| } |
| } |
| } |
| hir::ItemKind::Enum(..) => { |
| tcx.ensure().generics_of(def_id); |
| tcx.ensure().type_of(def_id); |
| tcx.ensure().predicates_of(def_id); |
| lower_enum_variant_types(tcx, def_id.to_def_id()); |
| } |
| hir::ItemKind::Impl { .. } => { |
| tcx.ensure().generics_of(def_id); |
| tcx.ensure().type_of(def_id); |
| tcx.ensure().impl_trait_header(def_id); |
| tcx.ensure().predicates_of(def_id); |
| tcx.ensure().associated_items(def_id); |
| } |
| hir::ItemKind::Trait(..) => { |
| tcx.ensure().generics_of(def_id); |
| tcx.ensure().trait_def(def_id); |
| tcx.at(it.span).explicit_super_predicates_of(def_id); |
| tcx.ensure().predicates_of(def_id); |
| tcx.ensure().associated_items(def_id); |
| } |
| hir::ItemKind::TraitAlias(..) => { |
| tcx.ensure().generics_of(def_id); |
| tcx.at(it.span).explicit_implied_predicates_of(def_id); |
| tcx.at(it.span).explicit_super_predicates_of(def_id); |
| tcx.ensure().predicates_of(def_id); |
| } |
| hir::ItemKind::Struct(struct_def, _) | hir::ItemKind::Union(struct_def, _) => { |
| tcx.ensure().generics_of(def_id); |
| tcx.ensure().type_of(def_id); |
| tcx.ensure().predicates_of(def_id); |
| |
| for f in struct_def.fields() { |
| tcx.ensure().generics_of(f.def_id); |
| tcx.ensure().type_of(f.def_id); |
| tcx.ensure().predicates_of(f.def_id); |
| } |
| |
| if let Some(ctor_def_id) = struct_def.ctor_def_id() { |
| lower_variant_ctor(tcx, ctor_def_id); |
| } |
| } |
| |
| hir::ItemKind::TyAlias(..) => { |
| tcx.ensure().generics_of(def_id); |
| tcx.ensure().type_of(def_id); |
| tcx.ensure().predicates_of(def_id); |
| } |
| |
| hir::ItemKind::Static(ty, ..) | hir::ItemKind::Const(ty, ..) => { |
| tcx.ensure().generics_of(def_id); |
| tcx.ensure().type_of(def_id); |
| tcx.ensure().predicates_of(def_id); |
| if !ty.is_suggestable_infer_ty() { |
| let mut visitor = HirPlaceholderCollector::default(); |
| visitor.visit_item(it); |
| placeholder_type_error( |
| icx.lowerer(), |
| None, |
| visitor.0, |
| false, |
| None, |
| it.kind.descr(), |
| ); |
| } |
| } |
| |
| hir::ItemKind::Fn(..) => { |
| tcx.ensure().generics_of(def_id); |
| tcx.ensure().type_of(def_id); |
| tcx.ensure().predicates_of(def_id); |
| tcx.ensure().fn_sig(def_id); |
| tcx.ensure().codegen_fn_attrs(def_id); |
| } |
| } |
| } |
| |
| fn lower_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) { |
| let trait_item = tcx.hir().trait_item(trait_item_id); |
| let def_id = trait_item_id.owner_id; |
| tcx.ensure().generics_of(def_id); |
| let icx = ItemCtxt::new(tcx, def_id.def_id); |
| |
| match trait_item.kind { |
| hir::TraitItemKind::Fn(..) => { |
| tcx.ensure().codegen_fn_attrs(def_id); |
| tcx.ensure().type_of(def_id); |
| tcx.ensure().fn_sig(def_id); |
| } |
| |
| hir::TraitItemKind::Const(ty, body_id) => { |
| tcx.ensure().type_of(def_id); |
| if !tcx.dcx().has_stashed_diagnostic(ty.span, StashKey::ItemNoType) |
| && !(ty.is_suggestable_infer_ty() && body_id.is_some()) |
| { |
| // Account for `const C: _;`. |
| let mut visitor = HirPlaceholderCollector::default(); |
| visitor.visit_trait_item(trait_item); |
| placeholder_type_error( |
| icx.lowerer(), |
| None, |
| visitor.0, |
| false, |
| None, |
| "associated constant", |
| ); |
| } |
| } |
| |
| hir::TraitItemKind::Type(_, Some(_)) => { |
| tcx.ensure().item_bounds(def_id); |
| tcx.ensure().item_super_predicates(def_id); |
| tcx.ensure().type_of(def_id); |
| // Account for `type T = _;`. |
| let mut visitor = HirPlaceholderCollector::default(); |
| visitor.visit_trait_item(trait_item); |
| placeholder_type_error(icx.lowerer(), None, visitor.0, false, None, "associated type"); |
| } |
| |
| hir::TraitItemKind::Type(_, None) => { |
| tcx.ensure().item_bounds(def_id); |
| tcx.ensure().item_super_predicates(def_id); |
| // #74612: Visit and try to find bad placeholders |
| // even if there is no concrete type. |
| let mut visitor = HirPlaceholderCollector::default(); |
| visitor.visit_trait_item(trait_item); |
| |
| placeholder_type_error(icx.lowerer(), None, visitor.0, false, None, "associated type"); |
| } |
| }; |
| |
| tcx.ensure().predicates_of(def_id); |
| } |
| |
| fn lower_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) { |
| let def_id = impl_item_id.owner_id; |
| tcx.ensure().generics_of(def_id); |
| tcx.ensure().type_of(def_id); |
| tcx.ensure().predicates_of(def_id); |
| let impl_item = tcx.hir().impl_item(impl_item_id); |
| let icx = ItemCtxt::new(tcx, def_id.def_id); |
| match impl_item.kind { |
| hir::ImplItemKind::Fn(..) => { |
| tcx.ensure().codegen_fn_attrs(def_id); |
| tcx.ensure().fn_sig(def_id); |
| } |
| hir::ImplItemKind::Type(_) => { |
| // Account for `type T = _;` |
| let mut visitor = HirPlaceholderCollector::default(); |
| visitor.visit_impl_item(impl_item); |
| |
| placeholder_type_error(icx.lowerer(), None, visitor.0, false, None, "associated type"); |
| } |
| hir::ImplItemKind::Const(ty, _) => { |
| // Account for `const T: _ = ..;` |
| if !ty.is_suggestable_infer_ty() { |
| let mut visitor = HirPlaceholderCollector::default(); |
| visitor.visit_impl_item(impl_item); |
| placeholder_type_error( |
| icx.lowerer(), |
| None, |
| visitor.0, |
| false, |
| None, |
| "associated constant", |
| ); |
| } |
| } |
| } |
| } |
| |
| fn lower_variant_ctor(tcx: TyCtxt<'_>, def_id: LocalDefId) { |
| tcx.ensure().generics_of(def_id); |
| tcx.ensure().type_of(def_id); |
| tcx.ensure().predicates_of(def_id); |
| } |
| |
| fn lower_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId) { |
| let def = tcx.adt_def(def_id); |
| let repr_type = def.repr().discr_type(); |
| let initial = repr_type.initial_discriminant(tcx); |
| let mut prev_discr = None::<Discr<'_>>; |
| |
| // fill the discriminant values and field types |
| for variant in def.variants() { |
| let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx)); |
| prev_discr = Some( |
| if let ty::VariantDiscr::Explicit(const_def_id) = variant.discr { |
| def.eval_explicit_discr(tcx, const_def_id).ok() |
| } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) { |
| Some(discr) |
| } else { |
| let span = tcx.def_span(variant.def_id); |
| tcx.dcx().emit_err(errors::EnumDiscriminantOverflowed { |
| span, |
| discr: prev_discr.unwrap().to_string(), |
| item_name: tcx.item_name(variant.def_id), |
| wrapped_discr: wrapped_discr.to_string(), |
| }); |
| None |
| } |
| .unwrap_or(wrapped_discr), |
| ); |
| |
| for f in &variant.fields { |
| tcx.ensure().generics_of(f.did); |
| tcx.ensure().type_of(f.did); |
| tcx.ensure().predicates_of(f.did); |
| } |
| |
| // Lower the ctor, if any. This also registers the variant as an item. |
| if let Some(ctor_def_id) = variant.ctor_def_id() { |
| lower_variant_ctor(tcx, ctor_def_id.expect_local()); |
| } |
| } |
| } |
| |
| #[derive(Clone, Copy)] |
| struct NestedSpan { |
| span: Span, |
| nested_field_span: Span, |
| } |
| |
| impl NestedSpan { |
| fn to_field_already_declared_nested_help(&self) -> errors::FieldAlreadyDeclaredNestedHelp { |
| errors::FieldAlreadyDeclaredNestedHelp { span: self.span } |
| } |
| } |
| |
| #[derive(Clone, Copy)] |
| enum FieldDeclSpan { |
| NotNested(Span), |
| Nested(NestedSpan), |
| } |
| |
| impl From<Span> for FieldDeclSpan { |
| fn from(span: Span) -> Self { |
| Self::NotNested(span) |
| } |
| } |
| |
| impl From<NestedSpan> for FieldDeclSpan { |
| fn from(span: NestedSpan) -> Self { |
| Self::Nested(span) |
| } |
| } |
| |
| struct FieldUniquenessCheckContext<'tcx> { |
| tcx: TyCtxt<'tcx>, |
| seen_fields: FxIndexMap<Ident, FieldDeclSpan>, |
| } |
| |
| impl<'tcx> FieldUniquenessCheckContext<'tcx> { |
| fn new(tcx: TyCtxt<'tcx>) -> Self { |
| Self { tcx, seen_fields: FxIndexMap::default() } |
| } |
| |
| /// Check if a given field `ident` declared at `field_decl` has been declared elsewhere before. |
| fn check_field_decl(&mut self, ident: Ident, field_decl: FieldDeclSpan) { |
| use FieldDeclSpan::*; |
| let field_name = ident.name; |
| let ident = ident.normalize_to_macros_2_0(); |
| match (field_decl, self.seen_fields.get(&ident).copied()) { |
| (NotNested(span), Some(NotNested(prev_span))) => { |
| self.tcx.dcx().emit_err(errors::FieldAlreadyDeclared::NotNested { |
| field_name, |
| span, |
| prev_span, |
| }); |
| } |
| (NotNested(span), Some(Nested(prev))) => { |
| self.tcx.dcx().emit_err(errors::FieldAlreadyDeclared::PreviousNested { |
| field_name, |
| span, |
| prev_span: prev.span, |
| prev_nested_field_span: prev.nested_field_span, |
| prev_help: prev.to_field_already_declared_nested_help(), |
| }); |
| } |
| ( |
| Nested(current @ NestedSpan { span, nested_field_span, .. }), |
| Some(NotNested(prev_span)), |
| ) => { |
| self.tcx.dcx().emit_err(errors::FieldAlreadyDeclared::CurrentNested { |
| field_name, |
| span, |
| nested_field_span, |
| help: current.to_field_already_declared_nested_help(), |
| prev_span, |
| }); |
| } |
| (Nested(current @ NestedSpan { span, nested_field_span }), Some(Nested(prev))) => { |
| self.tcx.dcx().emit_err(errors::FieldAlreadyDeclared::BothNested { |
| field_name, |
| span, |
| nested_field_span, |
| help: current.to_field_already_declared_nested_help(), |
| prev_span: prev.span, |
| prev_nested_field_span: prev.nested_field_span, |
| prev_help: prev.to_field_already_declared_nested_help(), |
| }); |
| } |
| (field_decl, None) => { |
| self.seen_fields.insert(ident, field_decl); |
| } |
| } |
| } |
| } |
| |
| fn lower_variant( |
| tcx: TyCtxt<'_>, |
| variant_did: Option<LocalDefId>, |
| ident: Ident, |
| discr: ty::VariantDiscr, |
| def: &hir::VariantData<'_>, |
| adt_kind: ty::AdtKind, |
| parent_did: LocalDefId, |
| ) -> ty::VariantDef { |
| let mut field_uniqueness_check_ctx = FieldUniquenessCheckContext::new(tcx); |
| let fields = def |
| .fields() |
| .iter() |
| .inspect(|field| { |
| field_uniqueness_check_ctx.check_field_decl(field.ident, field.span.into()); |
| }) |
| .map(|f| ty::FieldDef { |
| did: f.def_id.to_def_id(), |
| name: f.ident.name, |
| vis: tcx.visibility(f.def_id), |
| }) |
| .collect(); |
| let recovered = match def { |
| hir::VariantData::Struct { recovered: Recovered::Yes(guar), .. } => Some(*guar), |
| _ => None, |
| }; |
| ty::VariantDef::new( |
| ident.name, |
| variant_did.map(LocalDefId::to_def_id), |
| def.ctor().map(|(kind, _, def_id)| (kind, def_id.to_def_id())), |
| discr, |
| fields, |
| adt_kind, |
| parent_did.to_def_id(), |
| recovered, |
| adt_kind == AdtKind::Struct && tcx.has_attr(parent_did, sym::non_exhaustive) |
| || variant_did |
| .is_some_and(|variant_did| tcx.has_attr(variant_did, sym::non_exhaustive)), |
| ) |
| } |
| |
| fn adt_def(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::AdtDef<'_> { |
| use rustc_hir::*; |
| |
| let Node::Item(item) = tcx.hir_node_by_def_id(def_id) else { |
| bug!("expected ADT to be an item"); |
| }; |
| |
| let repr = tcx.repr_options_of_def(def_id); |
| let (kind, variants) = match &item.kind { |
| ItemKind::Enum(def, _) => { |
| let mut distance_from_explicit = 0; |
| let variants = def |
| .variants |
| .iter() |
| .map(|v| { |
| let discr = if let Some(e) = &v.disr_expr { |
| distance_from_explicit = 0; |
| ty::VariantDiscr::Explicit(e.def_id.to_def_id()) |
| } else { |
| ty::VariantDiscr::Relative(distance_from_explicit) |
| }; |
| distance_from_explicit += 1; |
| |
| lower_variant( |
| tcx, |
| Some(v.def_id), |
| v.ident, |
| discr, |
| &v.data, |
| AdtKind::Enum, |
| def_id, |
| ) |
| }) |
| .collect(); |
| |
| (AdtKind::Enum, variants) |
| } |
| ItemKind::Struct(def, _) | ItemKind::Union(def, _) => { |
| let adt_kind = match item.kind { |
| ItemKind::Struct(..) => AdtKind::Struct, |
| _ => AdtKind::Union, |
| }; |
| let variants = std::iter::once(lower_variant( |
| tcx, |
| None, |
| item.ident, |
| ty::VariantDiscr::Relative(0), |
| def, |
| adt_kind, |
| def_id, |
| )) |
| .collect(); |
| |
| (adt_kind, variants) |
| } |
| _ => bug!("{:?} is not an ADT", item.owner_id.def_id), |
| }; |
| tcx.mk_adt_def(def_id.to_def_id(), kind, variants, repr) |
| } |
| |
| fn trait_def(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::TraitDef { |
| let item = tcx.hir().expect_item(def_id); |
| |
| let (is_alias, is_auto, safety, items) = match item.kind { |
| hir::ItemKind::Trait(is_auto, safety, .., items) => { |
| (false, is_auto == hir::IsAuto::Yes, safety, items) |
| } |
| hir::ItemKind::TraitAlias(..) => (true, false, hir::Safety::Safe, &[][..]), |
| _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"), |
| }; |
| |
| // Only regular traits can be const. |
| let constness = if !is_alias && tcx.has_attr(def_id, sym::const_trait) { |
| hir::Constness::Const |
| } else { |
| hir::Constness::NotConst |
| }; |
| |
| let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar); |
| if paren_sugar && !tcx.features().unboxed_closures { |
| tcx.dcx().emit_err(errors::ParenSugarAttribute { span: item.span }); |
| } |
| |
| // Only regular traits can be marker. |
| let is_marker = !is_alias && tcx.has_attr(def_id, sym::marker); |
| |
| let rustc_coinductive = tcx.has_attr(def_id, sym::rustc_coinductive); |
| let is_fundamental = tcx.has_attr(def_id, sym::fundamental); |
| |
| // FIXME: We could probably do way better attribute validation here. |
| let mut skip_array_during_method_dispatch = false; |
| let mut skip_boxed_slice_during_method_dispatch = false; |
| for attr in tcx.get_attrs(def_id, sym::rustc_skip_during_method_dispatch) { |
| if let Some(lst) = attr.meta_item_list() { |
| for item in lst { |
| if let Some(ident) = item.ident() { |
| match ident.as_str() { |
| "array" => skip_array_during_method_dispatch = true, |
| "boxed_slice" => skip_boxed_slice_during_method_dispatch = true, |
| _ => (), |
| } |
| } |
| } |
| } |
| } |
| |
| let specialization_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) { |
| ty::trait_def::TraitSpecializationKind::Marker |
| } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) { |
| ty::trait_def::TraitSpecializationKind::AlwaysApplicable |
| } else { |
| ty::trait_def::TraitSpecializationKind::None |
| }; |
| let must_implement_one_of = tcx |
| .get_attr(def_id, sym::rustc_must_implement_one_of) |
| // Check that there are at least 2 arguments of `#[rustc_must_implement_one_of]` |
| // and that they are all identifiers |
| .and_then(|attr| match attr.meta_item_list() { |
| Some(items) if items.len() < 2 => { |
| tcx.dcx().emit_err(errors::MustImplementOneOfAttribute { span: attr.span }); |
| |
| None |
| } |
| Some(items) => items |
| .into_iter() |
| .map(|item| item.ident().ok_or(item.span())) |
| .collect::<Result<Box<[_]>, _>>() |
| .map_err(|span| { |
| tcx.dcx().emit_err(errors::MustBeNameOfAssociatedFunction { span }); |
| }) |
| .ok() |
| .zip(Some(attr.span)), |
| // Error is reported by `rustc_attr!` |
| None => None, |
| }) |
| // Check that all arguments of `#[rustc_must_implement_one_of]` reference |
| // functions in the trait with default implementations |
| .and_then(|(list, attr_span)| { |
| let errors = list.iter().filter_map(|ident| { |
| let item = items.iter().find(|item| item.ident == *ident); |
| |
| match item { |
| Some(item) if matches!(item.kind, hir::AssocItemKind::Fn { .. }) => { |
| if !tcx.defaultness(item.id.owner_id).has_value() { |
| tcx.dcx().emit_err(errors::FunctionNotHaveDefaultImplementation { |
| span: item.span, |
| note_span: attr_span, |
| }); |
| |
| return Some(()); |
| } |
| |
| return None; |
| } |
| Some(item) => { |
| tcx.dcx().emit_err(errors::MustImplementNotFunction { |
| span: item.span, |
| span_note: errors::MustImplementNotFunctionSpanNote { span: attr_span }, |
| note: errors::MustImplementNotFunctionNote {}, |
| }); |
| } |
| None => { |
| tcx.dcx().emit_err(errors::FunctionNotFoundInTrait { span: ident.span }); |
| } |
| } |
| |
| Some(()) |
| }); |
| |
| (errors.count() == 0).then_some(list) |
| }) |
| // Check for duplicates |
| .and_then(|list| { |
| let mut set: UnordMap<Symbol, Span> = Default::default(); |
| let mut no_dups = true; |
| |
| for ident in &*list { |
| if let Some(dup) = set.insert(ident.name, ident.span) { |
| tcx.dcx() |
| .emit_err(errors::FunctionNamesDuplicated { spans: vec![dup, ident.span] }); |
| |
| no_dups = false; |
| } |
| } |
| |
| no_dups.then_some(list) |
| }); |
| |
| let mut deny_explicit_impl = false; |
| let mut implement_via_object = true; |
| if let Some(attr) = tcx.get_attr(def_id, sym::rustc_deny_explicit_impl) { |
| deny_explicit_impl = true; |
| let mut seen_attr = false; |
| for meta in attr.meta_item_list().iter().flatten() { |
| if let Some(meta) = meta.meta_item() |
| && meta.name_or_empty() == sym::implement_via_object |
| && let Some(lit) = meta.name_value_literal() |
| { |
| if seen_attr { |
| tcx.dcx().span_err(meta.span, "duplicated `implement_via_object` meta item"); |
| } |
| seen_attr = true; |
| |
| match lit.symbol { |
| kw::True => { |
| implement_via_object = true; |
| } |
| kw::False => { |
| implement_via_object = false; |
| } |
| _ => { |
| tcx.dcx().span_err( |
| meta.span, |
| format!( |
| "unknown literal passed to `implement_via_object` attribute: {}", |
| lit.symbol |
| ), |
| ); |
| } |
| } |
| } else { |
| tcx.dcx().span_err( |
| meta.span(), |
| format!("unknown meta item passed to `rustc_deny_explicit_impl` {meta:?}"), |
| ); |
| } |
| } |
| if !seen_attr { |
| tcx.dcx().span_err(attr.span, "missing `implement_via_object` meta item"); |
| } |
| } |
| |
| ty::TraitDef { |
| def_id: def_id.to_def_id(), |
| safety, |
| constness, |
| paren_sugar, |
| has_auto_impl: is_auto, |
| is_marker, |
| is_coinductive: rustc_coinductive || is_auto, |
| is_fundamental, |
| skip_array_during_method_dispatch, |
| skip_boxed_slice_during_method_dispatch, |
| specialization_kind, |
| must_implement_one_of, |
| implement_via_object, |
| deny_explicit_impl, |
| } |
| } |
| |
| #[instrument(level = "debug", skip(tcx))] |
| fn fn_sig(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::EarlyBinder<'_, ty::PolyFnSig<'_>> { |
| use rustc_hir::Node::*; |
| use rustc_hir::*; |
| |
| let hir_id = tcx.local_def_id_to_hir_id(def_id); |
| |
| let icx = ItemCtxt::new(tcx, def_id); |
| |
| let output = match tcx.hir_node(hir_id) { |
| TraitItem(hir::TraitItem { |
| kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)), |
| generics, |
| .. |
| }) |
| | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), .. }) => { |
| infer_return_ty_for_fn_sig(sig, generics, def_id, &icx) |
| } |
| |
| ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), generics, .. }) => { |
| // Do not try to infer the return type for a impl method coming from a trait |
| if let Item(hir::Item { kind: ItemKind::Impl(i), .. }) = tcx.parent_hir_node(hir_id) |
| && i.of_trait.is_some() |
| { |
| icx.lowerer().lower_fn_ty( |
| hir_id, |
| sig.header.safety, |
| sig.header.abi, |
| sig.decl, |
| Some(generics), |
| None, |
| ) |
| } else { |
| infer_return_ty_for_fn_sig(sig, generics, def_id, &icx) |
| } |
| } |
| |
| TraitItem(hir::TraitItem { |
| kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _), |
| generics, |
| .. |
| }) => { |
| icx.lowerer().lower_fn_ty(hir_id, header.safety, header.abi, decl, Some(generics), None) |
| } |
| |
| ForeignItem(&hir::ForeignItem { kind: ForeignItemKind::Fn(sig, _, _), .. }) => { |
| let abi = tcx.hir().get_foreign_abi(hir_id); |
| compute_sig_of_foreign_fn_decl(tcx, def_id, sig.decl, abi, sig.header.safety) |
| } |
| |
| Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor().is_some() => { |
| let adt_def_id = tcx.hir().get_parent_item(hir_id).def_id.to_def_id(); |
| let ty = tcx.type_of(adt_def_id).instantiate_identity(); |
| let inputs = data.fields().iter().map(|f| tcx.type_of(f.def_id).instantiate_identity()); |
| // constructors for structs with `layout_scalar_valid_range` are unsafe to call |
| let safety = match tcx.layout_scalar_valid_range(adt_def_id) { |
| (Bound::Unbounded, Bound::Unbounded) => hir::Safety::Safe, |
| _ => hir::Safety::Unsafe, |
| }; |
| ty::Binder::dummy(tcx.mk_fn_sig(inputs, ty, false, safety, abi::Abi::Rust)) |
| } |
| |
| Expr(&hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => { |
| // Closure signatures are not like other function |
| // signatures and cannot be accessed through `fn_sig`. For |
| // example, a closure signature excludes the `self` |
| // argument. In any case they are embedded within the |
| // closure type as part of the `ClosureArgs`. |
| // |
| // To get the signature of a closure, you should use the |
| // `sig` method on the `ClosureArgs`: |
| // |
| // args.as_closure().sig(def_id, tcx) |
| bug!("to get the signature of a closure, use `args.as_closure().sig()` not `fn_sig()`",); |
| } |
| |
| x => { |
| bug!("unexpected sort of node in fn_sig(): {:?}", x); |
| } |
| }; |
| ty::EarlyBinder::bind(output) |
| } |
| |
| fn infer_return_ty_for_fn_sig<'tcx>( |
| sig: &hir::FnSig<'tcx>, |
| generics: &hir::Generics<'_>, |
| def_id: LocalDefId, |
| icx: &ItemCtxt<'tcx>, |
| ) -> ty::PolyFnSig<'tcx> { |
| let tcx = icx.tcx; |
| let hir_id = tcx.local_def_id_to_hir_id(def_id); |
| |
| match sig.decl.output.get_infer_ret_ty() { |
| Some(ty) => { |
| let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id]; |
| // Typeck doesn't expect erased regions to be returned from `type_of`. |
| // This is a heuristic approach. If the scope has region parameters, |
| // we should change fn_sig's lifetime from `ReErased` to `ReError`, |
| // otherwise to `ReStatic`. |
| let has_region_params = generics.params.iter().any(|param| match param.kind { |
| GenericParamKind::Lifetime { .. } => true, |
| _ => false, |
| }); |
| let fn_sig = tcx.fold_regions(fn_sig, |r, _| match *r { |
| ty::ReErased => { |
| if has_region_params { |
| ty::Region::new_error_with_message( |
| tcx, |
| DUMMY_SP, |
| "erased region is not allowed here in return type", |
| ) |
| } else { |
| tcx.lifetimes.re_static |
| } |
| } |
| _ => r, |
| }); |
| |
| let mut visitor = HirPlaceholderCollector::default(); |
| visitor.visit_ty(ty); |
| |
| let mut diag = bad_placeholder(icx.lowerer(), visitor.0, "return type"); |
| let ret_ty = fn_sig.output(); |
| // Don't leak types into signatures unless they're nameable! |
| // For example, if a function returns itself, we don't want that |
| // recursive function definition to leak out into the fn sig. |
| let mut recovered_ret_ty = None; |
| |
| if let Some(suggestable_ret_ty) = ret_ty.make_suggestable(tcx, false, None) { |
| diag.span_suggestion( |
| ty.span, |
| "replace with the correct return type", |
| suggestable_ret_ty, |
| Applicability::MachineApplicable, |
| ); |
| recovered_ret_ty = Some(suggestable_ret_ty); |
| } else if let Some(sugg) = |
| suggest_impl_trait(&tcx.infer_ctxt().build(), tcx.param_env(def_id), ret_ty) |
| { |
| diag.span_suggestion( |
| ty.span, |
| "replace with an appropriate return type", |
| sugg, |
| Applicability::MachineApplicable, |
| ); |
| } else if ret_ty.is_closure() { |
| diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound"); |
| } |
| // Also note how `Fn` traits work just in case! |
| if ret_ty.is_closure() { |
| diag.note( |
| "for more information on `Fn` traits and closure types, see \ |
| https://doc.rust-lang.org/book/ch13-01-closures.html", |
| ); |
| } |
| |
| let guar = diag.emit(); |
| ty::Binder::dummy(tcx.mk_fn_sig( |
| fn_sig.inputs().iter().copied(), |
| recovered_ret_ty.unwrap_or_else(|| Ty::new_error(tcx, guar)), |
| fn_sig.c_variadic, |
| fn_sig.safety, |
| fn_sig.abi, |
| )) |
| } |
| None => icx.lowerer().lower_fn_ty( |
| hir_id, |
| sig.header.safety, |
| sig.header.abi, |
| sig.decl, |
| Some(generics), |
| None, |
| ), |
| } |
| } |
| |
| pub fn suggest_impl_trait<'tcx>( |
| infcx: &InferCtxt<'tcx>, |
| param_env: ty::ParamEnv<'tcx>, |
| ret_ty: Ty<'tcx>, |
| ) -> Option<String> { |
| let format_as_assoc: fn(_, _, _, _, _) -> _ = |
| |tcx: TyCtxt<'tcx>, |
| _: ty::GenericArgsRef<'tcx>, |
| trait_def_id: DefId, |
| assoc_item_def_id: DefId, |
| item_ty: Ty<'tcx>| { |
| let trait_name = tcx.item_name(trait_def_id); |
| let assoc_name = tcx.item_name(assoc_item_def_id); |
| Some(format!("impl {trait_name}<{assoc_name} = {item_ty}>")) |
| }; |
| let format_as_parenthesized: fn(_, _, _, _, _) -> _ = |
| |tcx: TyCtxt<'tcx>, |
| args: ty::GenericArgsRef<'tcx>, |
| trait_def_id: DefId, |
| _: DefId, |
| item_ty: Ty<'tcx>| { |
| let trait_name = tcx.item_name(trait_def_id); |
| let args_tuple = args.type_at(1); |
| let ty::Tuple(types) = *args_tuple.kind() else { |
| return None; |
| }; |
| let types = types.make_suggestable(tcx, false, None)?; |
| let maybe_ret = |
| if item_ty.is_unit() { String::new() } else { format!(" -> {item_ty}") }; |
| Some(format!( |
| "impl {trait_name}({}){maybe_ret}", |
| types.iter().map(|ty| ty.to_string()).collect::<Vec<_>>().join(", ") |
| )) |
| }; |
| |
| for (trait_def_id, assoc_item_def_id, formatter) in [ |
| ( |
| infcx.tcx.get_diagnostic_item(sym::Iterator), |
| infcx.tcx.get_diagnostic_item(sym::IteratorItem), |
| format_as_assoc, |
| ), |
| ( |
| infcx.tcx.lang_items().future_trait(), |
| infcx.tcx.lang_items().future_output(), |
| format_as_assoc, |
| ), |
| ( |
| infcx.tcx.lang_items().fn_trait(), |
| infcx.tcx.lang_items().fn_once_output(), |
| format_as_parenthesized, |
| ), |
| ( |
| infcx.tcx.lang_items().fn_mut_trait(), |
| infcx.tcx.lang_items().fn_once_output(), |
| format_as_parenthesized, |
| ), |
| ( |
| infcx.tcx.lang_items().fn_once_trait(), |
| infcx.tcx.lang_items().fn_once_output(), |
| format_as_parenthesized, |
| ), |
| ] { |
| let Some(trait_def_id) = trait_def_id else { |
| continue; |
| }; |
| let Some(assoc_item_def_id) = assoc_item_def_id else { |
| continue; |
| }; |
| if infcx.tcx.def_kind(assoc_item_def_id) != DefKind::AssocTy { |
| continue; |
| } |
| let sugg = infcx.probe(|_| { |
| let args = ty::GenericArgs::for_item(infcx.tcx, trait_def_id, |param, _| { |
| if param.index == 0 { ret_ty.into() } else { infcx.var_for_def(DUMMY_SP, param) } |
| }); |
| if !infcx |
| .type_implements_trait(trait_def_id, args, param_env) |
| .must_apply_modulo_regions() |
| { |
| return None; |
| } |
| let ocx = ObligationCtxt::new(&infcx); |
| let item_ty = ocx.normalize( |
| &ObligationCause::dummy(), |
| param_env, |
| Ty::new_projection_from_args(infcx.tcx, assoc_item_def_id, args), |
| ); |
| // FIXME(compiler-errors): We may benefit from resolving regions here. |
| if ocx.select_where_possible().is_empty() |
| && let item_ty = infcx.resolve_vars_if_possible(item_ty) |
| && let Some(item_ty) = item_ty.make_suggestable(infcx.tcx, false, None) |
| && let Some(sugg) = formatter( |
| infcx.tcx, |
| infcx.resolve_vars_if_possible(args), |
| trait_def_id, |
| assoc_item_def_id, |
| item_ty, |
| ) |
| { |
| return Some(sugg); |
| } |
| |
| None |
| }); |
| |
| if sugg.is_some() { |
| return sugg; |
| } |
| } |
| None |
| } |
| |
| fn impl_trait_header(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<ty::ImplTraitHeader<'_>> { |
| let icx = ItemCtxt::new(tcx, def_id); |
| let item = tcx.hir().expect_item(def_id); |
| let impl_ = item.expect_impl(); |
| impl_.of_trait.as_ref().map(|ast_trait_ref| { |
| let selfty = tcx.type_of(def_id).instantiate_identity(); |
| |
| check_impl_constness(tcx, tcx.is_const_trait_impl_raw(def_id.to_def_id()), ast_trait_ref); |
| |
| let trait_ref = icx.lowerer().lower_impl_trait_ref(ast_trait_ref, selfty); |
| |
| ty::ImplTraitHeader { |
| trait_ref: ty::EarlyBinder::bind(trait_ref), |
| safety: impl_.safety, |
| polarity: polarity_of_impl(tcx, def_id, impl_, item.span), |
| } |
| }) |
| } |
| |
| fn check_impl_constness( |
| tcx: TyCtxt<'_>, |
| is_const: bool, |
| hir_trait_ref: &hir::TraitRef<'_>, |
| ) -> Option<ErrorGuaranteed> { |
| if !is_const { |
| return None; |
| } |
| |
| let trait_def_id = hir_trait_ref.trait_def_id()?; |
| if tcx.is_const_trait(trait_def_id) { |
| return None; |
| } |
| |
| let trait_name = tcx.item_name(trait_def_id).to_string(); |
| Some(tcx.dcx().emit_err(errors::ConstImplForNonConstTrait { |
| trait_ref_span: hir_trait_ref.path.span, |
| trait_name, |
| local_trait_span: |
| trait_def_id.as_local().map(|_| tcx.def_span(trait_def_id).shrink_to_lo()), |
| marking: (), |
| adding: (), |
| })) |
| } |
| |
| fn polarity_of_impl( |
| tcx: TyCtxt<'_>, |
| def_id: LocalDefId, |
| impl_: &hir::Impl<'_>, |
| span: Span, |
| ) -> ty::ImplPolarity { |
| let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl); |
| match &impl_ { |
| hir::Impl { polarity: hir::ImplPolarity::Negative(span), of_trait, .. } => { |
| if is_rustc_reservation { |
| let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span)); |
| tcx.dcx().span_err(span, "reservation impls can't be negative"); |
| } |
| ty::ImplPolarity::Negative |
| } |
| hir::Impl { polarity: hir::ImplPolarity::Positive, of_trait: None, .. } => { |
| if is_rustc_reservation { |
| tcx.dcx().span_err(span, "reservation impls can't be inherent"); |
| } |
| ty::ImplPolarity::Positive |
| } |
| hir::Impl { polarity: hir::ImplPolarity::Positive, of_trait: Some(_), .. } => { |
| if is_rustc_reservation { |
| ty::ImplPolarity::Reservation |
| } else { |
| ty::ImplPolarity::Positive |
| } |
| } |
| } |
| } |
| |
| /// Returns the early-bound lifetimes declared in this generics |
| /// listing. For anything other than fns/methods, this is just all |
| /// the lifetimes that are declared. For fns or methods, we have to |
| /// screen out those that do not appear in any where-clauses etc using |
| /// `resolve_lifetime::early_bound_lifetimes`. |
| fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>( |
| tcx: TyCtxt<'tcx>, |
| generics: &'a hir::Generics<'a>, |
| ) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> { |
| generics.params.iter().filter(move |param| match param.kind { |
| GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id), |
| _ => false, |
| }) |
| } |
| |
| fn compute_sig_of_foreign_fn_decl<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| def_id: LocalDefId, |
| decl: &'tcx hir::FnDecl<'tcx>, |
| abi: abi::Abi, |
| safety: hir::Safety, |
| ) -> ty::PolyFnSig<'tcx> { |
| let safety = if abi == abi::Abi::RustIntrinsic { |
| intrinsic_operation_unsafety(tcx, def_id) |
| } else { |
| safety |
| }; |
| let hir_id = tcx.local_def_id_to_hir_id(def_id); |
| let fty = |
| ItemCtxt::new(tcx, def_id).lowerer().lower_fn_ty(hir_id, safety, abi, decl, None, None); |
| |
| // Feature gate SIMD types in FFI, since I am not sure that the |
| // ABIs are handled at all correctly. -huonw |
| if abi != abi::Abi::RustIntrinsic && !tcx.features().simd_ffi { |
| let check = |hir_ty: &hir::Ty<'_>, ty: Ty<'_>| { |
| if ty.is_simd() { |
| let snip = tcx |
| .sess |
| .source_map() |
| .span_to_snippet(hir_ty.span) |
| .map_or_else(|_| String::new(), |s| format!(" `{s}`")); |
| tcx.dcx().emit_err(errors::SIMDFFIHighlyExperimental { span: hir_ty.span, snip }); |
| } |
| }; |
| for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) { |
| check(input, *ty) |
| } |
| if let hir::FnRetTy::Return(ty) = decl.output { |
| check(ty, fty.output().skip_binder()) |
| } |
| } |
| |
| fty |
| } |
| |
| fn coroutine_kind(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<hir::CoroutineKind> { |
| match tcx.hir_node_by_def_id(def_id) { |
| Node::Expr(&hir::Expr { |
| kind: |
| hir::ExprKind::Closure(&rustc_hir::Closure { |
| kind: hir::ClosureKind::Coroutine(kind), |
| .. |
| }), |
| .. |
| }) => Some(kind), |
| _ => None, |
| } |
| } |
| |
| fn coroutine_for_closure(tcx: TyCtxt<'_>, def_id: LocalDefId) -> DefId { |
| let &rustc_hir::Closure { kind: hir::ClosureKind::CoroutineClosure(_), body, .. } = |
| tcx.hir_node_by_def_id(def_id).expect_closure() |
| else { |
| bug!() |
| }; |
| |
| let &hir::Expr { |
| kind: |
| hir::ExprKind::Closure(&rustc_hir::Closure { |
| def_id, |
| kind: hir::ClosureKind::Coroutine(_), |
| .. |
| }), |
| .. |
| } = tcx.hir().body(body).value |
| else { |
| bug!() |
| }; |
| |
| def_id.to_def_id() |
| } |
| |
| fn is_type_alias_impl_trait<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> bool { |
| let opaque = tcx.hir().expect_opaque_ty(def_id); |
| matches!(opaque.origin, hir::OpaqueTyOrigin::TyAlias { .. }) |
| } |
| |
| fn rendered_precise_capturing_args<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| def_id: LocalDefId, |
| ) -> Option<&'tcx [Symbol]> { |
| if let Some(ty::ImplTraitInTraitData::Trait { opaque_def_id, .. }) = |
| tcx.opt_rpitit_info(def_id.to_def_id()) |
| { |
| return tcx.rendered_precise_capturing_args(opaque_def_id); |
| } |
| |
| tcx.hir_node_by_def_id(def_id).expect_opaque_ty().bounds.iter().find_map(|bound| match bound { |
| hir::GenericBound::Use(args, ..) => { |
| Some(&*tcx.arena.alloc_from_iter(args.iter().map(|arg| arg.name()))) |
| } |
| _ => None, |
| }) |
| } |
