| //! Conversion from AST representation of types to the `ty.rs` representation. |
| //! The main routine here is `ast_ty_to_ty()`; each use is parameterized by an |
| //! instance of `AstConv`. |
| |
| mod errors; |
| mod generics; |
| |
| use crate::bounds::Bounds; |
| use crate::collect::PlaceholderHirTyCollector; |
| use crate::errors::{ |
| AmbiguousLifetimeBound, MultipleRelaxedDefaultBounds, TraitObjectDeclaredWithNoTraits, |
| TypeofReservedKeywordUsed, ValueOfAssociatedStructAlreadySpecified, |
| }; |
| use crate::middle::resolve_lifetime as rl; |
| use crate::require_c_abi_if_c_variadic; |
| use rustc_ast::util::lev_distance::find_best_match_for_name; |
| use rustc_data_structures::fx::{FxHashMap, FxHashSet}; |
| use rustc_errors::{struct_span_err, Applicability, ErrorReported, FatalError}; |
| use rustc_hir as hir; |
| use rustc_hir::def::{CtorOf, DefKind, Namespace, Res}; |
| use rustc_hir::def_id::{DefId, LocalDefId}; |
| use rustc_hir::intravisit::{walk_generics, Visitor as _}; |
| use rustc_hir::lang_items::LangItem; |
| use rustc_hir::{Constness, GenericArg, GenericArgs}; |
| use rustc_middle::ty::subst::{self, InternalSubsts, Subst, SubstsRef}; |
| use rustc_middle::ty::GenericParamDefKind; |
| use rustc_middle::ty::{self, Const, DefIdTree, Ty, TyCtxt, TypeFoldable}; |
| use rustc_session::lint::builtin::AMBIGUOUS_ASSOCIATED_ITEMS; |
| use rustc_span::symbol::{Ident, Symbol}; |
| use rustc_span::{Span, DUMMY_SP}; |
| use rustc_target::spec::abi; |
| use rustc_trait_selection::traits; |
| use rustc_trait_selection::traits::astconv_object_safety_violations; |
| use rustc_trait_selection::traits::error_reporting::report_object_safety_error; |
| use rustc_trait_selection::traits::wf::object_region_bounds; |
| |
| use smallvec::SmallVec; |
| use std::array; |
| use std::collections::BTreeSet; |
| use std::slice; |
| |
| #[derive(Debug)] |
| pub struct PathSeg(pub DefId, pub usize); |
| |
| pub trait AstConv<'tcx> { |
| fn tcx<'a>(&'a self) -> TyCtxt<'tcx>; |
| |
| fn item_def_id(&self) -> Option<DefId>; |
| |
| fn default_constness_for_trait_bounds(&self) -> Constness; |
| |
| /// Returns predicates in scope of the form `X: Foo`, where `X` is |
| /// a type parameter `X` with the given id `def_id`. This is a |
| /// subset of the full set of predicates. |
| /// |
| /// This is used for one specific purpose: resolving "short-hand" |
| /// associated type references like `T::Item`. In principle, we |
| /// would do that by first getting the full set of predicates in |
| /// scope and then filtering down to find those that apply to `T`, |
| /// but this can lead to cycle errors. The problem is that we have |
| /// to do this resolution *in order to create the predicates in |
| /// the first place*. Hence, we have this "special pass". |
| fn get_type_parameter_bounds(&self, span: Span, def_id: DefId) -> ty::GenericPredicates<'tcx>; |
| |
| /// Returns the lifetime to use when a lifetime is omitted (and not elided). |
| fn re_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) |
| -> Option<ty::Region<'tcx>>; |
| |
| /// Returns the type to use when a type is omitted. |
| fn ty_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx>; |
| |
| /// Returns `true` if `_` is allowed in type signatures in the current context. |
| fn allow_ty_infer(&self) -> bool; |
| |
| /// Returns the const to use when a const is omitted. |
| fn ct_infer( |
| &self, |
| ty: Ty<'tcx>, |
| param: Option<&ty::GenericParamDef>, |
| span: Span, |
| ) -> &'tcx Const<'tcx>; |
| |
| /// Projecting an associated type from a (potentially) |
| /// higher-ranked trait reference is more complicated, because of |
| /// the possibility of late-bound regions appearing in the |
| /// associated type binding. This is not legal in function |
| /// signatures for that reason. In a function body, we can always |
| /// handle it because we can use inference variables to remove the |
| /// late-bound regions. |
| fn projected_ty_from_poly_trait_ref( |
| &self, |
| span: Span, |
| item_def_id: DefId, |
| item_segment: &hir::PathSegment<'_>, |
| poly_trait_ref: ty::PolyTraitRef<'tcx>, |
| ) -> Ty<'tcx>; |
| |
| /// Normalize an associated type coming from the user. |
| fn normalize_ty(&self, span: Span, ty: Ty<'tcx>) -> Ty<'tcx>; |
| |
| /// Invoked when we encounter an error from some prior pass |
| /// (e.g., resolve) that is translated into a ty-error. This is |
| /// used to help suppress derived errors typeck might otherwise |
| /// report. |
| fn set_tainted_by_errors(&self); |
| |
| fn record_ty(&self, hir_id: hir::HirId, ty: Ty<'tcx>, span: Span); |
| } |
| |
| pub enum SizedByDefault { |
| Yes, |
| No, |
| } |
| |
| struct ConvertedBinding<'a, 'tcx> { |
| item_name: Ident, |
| kind: ConvertedBindingKind<'a, 'tcx>, |
| span: Span, |
| } |
| |
| enum ConvertedBindingKind<'a, 'tcx> { |
| Equality(Ty<'tcx>), |
| Constraint(&'a [hir::GenericBound<'a>]), |
| } |
| |
| /// New-typed boolean indicating whether explicit late-bound lifetimes |
| /// are present in a set of generic arguments. |
| /// |
| /// For example if we have some method `fn f<'a>(&'a self)` implemented |
| /// for some type `T`, although `f` is generic in the lifetime `'a`, `'a` |
| /// is late-bound so should not be provided explicitly. Thus, if `f` is |
| /// instantiated with some generic arguments providing `'a` explicitly, |
| /// we taint those arguments with `ExplicitLateBound::Yes` so that we |
| /// can provide an appropriate diagnostic later. |
| #[derive(Copy, Clone, PartialEq)] |
| pub enum ExplicitLateBound { |
| Yes, |
| No, |
| } |
| |
| /// Denotes the "position" of a generic argument, indicating if it is a generic type, |
| /// generic function or generic method call. |
| #[derive(Copy, Clone, PartialEq)] |
| pub(crate) enum GenericArgPosition { |
| Type, |
| Value, // e.g., functions |
| MethodCall, |
| } |
| |
| /// A marker denoting that the generic arguments that were |
| /// provided did not match the respective generic parameters. |
| #[derive(Clone, Default)] |
| pub struct GenericArgCountMismatch { |
| /// Indicates whether a fatal error was reported (`Some`), or just a lint (`None`). |
| pub reported: Option<ErrorReported>, |
| /// A list of spans of arguments provided that were not valid. |
| pub invalid_args: Vec<Span>, |
| } |
| |
| /// Decorates the result of a generic argument count mismatch |
| /// check with whether explicit late bounds were provided. |
| #[derive(Clone)] |
| pub struct GenericArgCountResult { |
| pub explicit_late_bound: ExplicitLateBound, |
| pub correct: Result<(), GenericArgCountMismatch>, |
| } |
| |
| impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { |
| pub fn ast_region_to_region( |
| &self, |
| lifetime: &hir::Lifetime, |
| def: Option<&ty::GenericParamDef>, |
| ) -> ty::Region<'tcx> { |
| let tcx = self.tcx(); |
| let lifetime_name = |def_id| tcx.hir().name(tcx.hir().local_def_id_to_hir_id(def_id)); |
| |
| let r = match tcx.named_region(lifetime.hir_id) { |
| Some(rl::Region::Static) => tcx.lifetimes.re_static, |
| |
| Some(rl::Region::LateBound(debruijn, id, _)) => { |
| let name = lifetime_name(id.expect_local()); |
| tcx.mk_region(ty::ReLateBound(debruijn, ty::BrNamed(id, name))) |
| } |
| |
| Some(rl::Region::LateBoundAnon(debruijn, index)) => { |
| tcx.mk_region(ty::ReLateBound(debruijn, ty::BrAnon(index))) |
| } |
| |
| Some(rl::Region::EarlyBound(index, id, _)) => { |
| let name = lifetime_name(id.expect_local()); |
| tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion { def_id: id, index, name })) |
| } |
| |
| Some(rl::Region::Free(scope, id)) => { |
| let name = lifetime_name(id.expect_local()); |
| tcx.mk_region(ty::ReFree(ty::FreeRegion { |
| scope, |
| bound_region: ty::BrNamed(id, name), |
| })) |
| |
| // (*) -- not late-bound, won't change |
| } |
| |
| None => { |
| self.re_infer(def, lifetime.span).unwrap_or_else(|| { |
| // This indicates an illegal lifetime |
| // elision. `resolve_lifetime` should have |
| // reported an error in this case -- but if |
| // not, let's error out. |
| tcx.sess.delay_span_bug(lifetime.span, "unelided lifetime in signature"); |
| |
| // Supply some dummy value. We don't have an |
| // `re_error`, annoyingly, so use `'static`. |
| tcx.lifetimes.re_static |
| }) |
| } |
| }; |
| |
| debug!("ast_region_to_region(lifetime={:?}) yields {:?}", lifetime, r); |
| |
| r |
| } |
| |
| /// Given a path `path` that refers to an item `I` with the declared generics `decl_generics`, |
| /// returns an appropriate set of substitutions for this particular reference to `I`. |
| pub fn ast_path_substs_for_ty( |
| &self, |
| span: Span, |
| def_id: DefId, |
| item_segment: &hir::PathSegment<'_>, |
| ) -> SubstsRef<'tcx> { |
| let (substs, assoc_bindings, _) = self.create_substs_for_ast_path( |
| span, |
| def_id, |
| &[], |
| item_segment.generic_args(), |
| item_segment.infer_args, |
| None, |
| ); |
| |
| if let Some(b) = assoc_bindings.first() { |
| Self::prohibit_assoc_ty_binding(self.tcx(), b.span); |
| } |
| |
| substs |
| } |
| |
| /// Given the type/lifetime/const arguments provided to some path (along with |
| /// an implicit `Self`, if this is a trait reference), returns the complete |
| /// set of substitutions. This may involve applying defaulted type parameters. |
| /// Also returns back constraints on associated types. |
| /// |
| /// Example: |
| /// |
| /// ``` |
| /// T: std::ops::Index<usize, Output = u32> |
| /// ^1 ^^^^^^^^^^^^^^2 ^^^^3 ^^^^^^^^^^^4 |
| /// ``` |
| /// |
| /// 1. The `self_ty` here would refer to the type `T`. |
| /// 2. The path in question is the path to the trait `std::ops::Index`, |
| /// which will have been resolved to a `def_id` |
| /// 3. The `generic_args` contains info on the `<...>` contents. The `usize` type |
| /// parameters are returned in the `SubstsRef`, the associated type bindings like |
| /// `Output = u32` are returned in the `Vec<ConvertedBinding...>` result. |
| /// |
| /// Note that the type listing given here is *exactly* what the user provided. |
| /// |
| /// For (generic) associated types |
| /// |
| /// ``` |
| /// <Vec<u8> as Iterable<u8>>::Iter::<'a> |
| /// ``` |
| /// |
| /// We have the parent substs are the substs for the parent trait: |
| /// `[Vec<u8>, u8]` and `generic_args` are the arguments for the associated |
| /// type itself: `['a]`. The returned `SubstsRef` concatenates these two |
| /// lists: `[Vec<u8>, u8, 'a]`. |
| fn create_substs_for_ast_path<'a>( |
| &self, |
| span: Span, |
| def_id: DefId, |
| parent_substs: &[subst::GenericArg<'tcx>], |
| generic_args: &'a hir::GenericArgs<'_>, |
| infer_args: bool, |
| self_ty: Option<Ty<'tcx>>, |
| ) -> (SubstsRef<'tcx>, Vec<ConvertedBinding<'a, 'tcx>>, GenericArgCountResult) { |
| // If the type is parameterized by this region, then replace this |
| // region with the current anon region binding (in other words, |
| // whatever & would get replaced with). |
| debug!( |
| "create_substs_for_ast_path(def_id={:?}, self_ty={:?}, \ |
| generic_args={:?})", |
| def_id, self_ty, generic_args |
| ); |
| |
| let tcx = self.tcx(); |
| let generic_params = tcx.generics_of(def_id); |
| |
| if generic_params.has_self { |
| if generic_params.parent.is_some() { |
| // The parent is a trait so it should have at least one subst |
| // for the `Self` type. |
| assert!(!parent_substs.is_empty()) |
| } else { |
| // This item (presumably a trait) needs a self-type. |
| assert!(self_ty.is_some()); |
| } |
| } else { |
| assert!(self_ty.is_none() && parent_substs.is_empty()); |
| } |
| |
| let arg_count = Self::check_generic_arg_count( |
| tcx, |
| span, |
| &generic_params, |
| &generic_args, |
| GenericArgPosition::Type, |
| self_ty.is_some(), |
| infer_args, |
| ); |
| |
| let is_object = self_ty.map_or(false, |ty| ty == self.tcx().types.trait_object_dummy_self); |
| let default_needs_object_self = |param: &ty::GenericParamDef| { |
| if let GenericParamDefKind::Type { has_default, .. } = param.kind { |
| if is_object && has_default { |
| let default_ty = tcx.at(span).type_of(param.def_id); |
| let self_param = tcx.types.self_param; |
| if default_ty.walk().any(|arg| arg == self_param.into()) { |
| // There is no suitable inference default for a type parameter |
| // that references self, in an object type. |
| return true; |
| } |
| } |
| } |
| |
| false |
| }; |
| |
| let mut missing_type_params = vec![]; |
| let mut inferred_params = vec![]; |
| let substs = Self::create_substs_for_generic_args( |
| tcx, |
| def_id, |
| parent_substs, |
| self_ty.is_some(), |
| self_ty, |
| arg_count.clone(), |
| // Provide the generic args, and whether types should be inferred. |
| |did| { |
| if did == def_id { |
| (Some(generic_args), infer_args) |
| } else { |
| // The last component of this tuple is unimportant. |
| (None, false) |
| } |
| }, |
| // Provide substitutions for parameters for which (valid) arguments have been provided. |
| |param, arg| match (¶m.kind, arg) { |
| (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => { |
| self.ast_region_to_region(<, Some(param)).into() |
| } |
| (GenericParamDefKind::Type { has_default, .. }, GenericArg::Type(ty)) => { |
| if *has_default { |
| tcx.check_optional_stability( |
| param.def_id, |
| Some(arg.id()), |
| arg.span(), |
| |_, _| { |
| // Default generic parameters may not be marked |
| // with stability attributes, i.e. when the |
| // default parameter was defined at the same time |
| // as the rest of the type. As such, we ignore missing |
| // stability attributes. |
| }, |
| ) |
| } |
| if let (hir::TyKind::Infer, false) = (&ty.kind, self.allow_ty_infer()) { |
| inferred_params.push(ty.span); |
| tcx.ty_error().into() |
| } else { |
| self.ast_ty_to_ty(&ty).into() |
| } |
| } |
| (GenericParamDefKind::Const, GenericArg::Const(ct)) => { |
| ty::Const::from_opt_const_arg_anon_const( |
| tcx, |
| ty::WithOptConstParam { |
| did: tcx.hir().local_def_id(ct.value.hir_id), |
| const_param_did: Some(param.def_id), |
| }, |
| ) |
| .into() |
| } |
| _ => unreachable!(), |
| }, |
| // Provide substitutions for parameters for which arguments are inferred. |
| |substs, param, infer_args| { |
| match param.kind { |
| GenericParamDefKind::Lifetime => tcx.lifetimes.re_static.into(), |
| GenericParamDefKind::Type { has_default, .. } => { |
| if !infer_args && has_default { |
| // No type parameter provided, but a default exists. |
| |
| // If we are converting an object type, then the |
| // `Self` parameter is unknown. However, some of the |
| // other type parameters may reference `Self` in their |
| // defaults. This will lead to an ICE if we are not |
| // careful! |
| if default_needs_object_self(param) { |
| missing_type_params.push(param.name.to_string()); |
| tcx.ty_error().into() |
| } else { |
| // This is a default type parameter. |
| self.normalize_ty( |
| span, |
| tcx.at(span).type_of(param.def_id).subst_spanned( |
| tcx, |
| substs.unwrap(), |
| Some(span), |
| ), |
| ) |
| .into() |
| } |
| } else if infer_args { |
| // No type parameters were provided, we can infer all. |
| let param = |
| if !default_needs_object_self(param) { Some(param) } else { None }; |
| self.ty_infer(param, span).into() |
| } else { |
| // We've already errored above about the mismatch. |
| tcx.ty_error().into() |
| } |
| } |
| GenericParamDefKind::Const => { |
| let ty = tcx.at(span).type_of(param.def_id); |
| // FIXME(const_generics:defaults) |
| if infer_args { |
| // No const parameters were provided, we can infer all. |
| self.ct_infer(ty, Some(param), span).into() |
| } else { |
| // We've already errored above about the mismatch. |
| tcx.const_error(ty).into() |
| } |
| } |
| } |
| }, |
| ); |
| |
| self.complain_about_missing_type_params( |
| missing_type_params, |
| def_id, |
| span, |
| generic_args.args.is_empty(), |
| ); |
| |
| // Convert associated-type bindings or constraints into a separate vector. |
| // Example: Given this: |
| // |
| // T: Iterator<Item = u32> |
| // |
| // The `T` is passed in as a self-type; the `Item = u32` is |
| // not a "type parameter" of the `Iterator` trait, but rather |
| // a restriction on `<T as Iterator>::Item`, so it is passed |
| // back separately. |
| let assoc_bindings = generic_args |
| .bindings |
| .iter() |
| .map(|binding| { |
| let kind = match binding.kind { |
| hir::TypeBindingKind::Equality { ref ty } => { |
| ConvertedBindingKind::Equality(self.ast_ty_to_ty(ty)) |
| } |
| hir::TypeBindingKind::Constraint { ref bounds } => { |
| ConvertedBindingKind::Constraint(bounds) |
| } |
| }; |
| ConvertedBinding { item_name: binding.ident, kind, span: binding.span } |
| }) |
| .collect(); |
| |
| debug!( |
| "create_substs_for_ast_path(generic_params={:?}, self_ty={:?}) -> {:?}", |
| generic_params, self_ty, substs |
| ); |
| |
| (substs, assoc_bindings, arg_count) |
| } |
| |
| crate fn create_substs_for_associated_item( |
| &self, |
| tcx: TyCtxt<'tcx>, |
| span: Span, |
| item_def_id: DefId, |
| item_segment: &hir::PathSegment<'_>, |
| parent_substs: SubstsRef<'tcx>, |
| ) -> SubstsRef<'tcx> { |
| if tcx.generics_of(item_def_id).params.is_empty() { |
| self.prohibit_generics(slice::from_ref(item_segment)); |
| |
| parent_substs |
| } else { |
| self.create_substs_for_ast_path( |
| span, |
| item_def_id, |
| parent_substs, |
| item_segment.generic_args(), |
| item_segment.infer_args, |
| None, |
| ) |
| .0 |
| } |
| } |
| |
| /// Instantiates the path for the given trait reference, assuming that it's |
| /// bound to a valid trait type. Returns the `DefId` of the defining trait. |
| /// The type _cannot_ be a type other than a trait type. |
| /// |
| /// If the `projections` argument is `None`, then assoc type bindings like `Foo<T = X>` |
| /// are disallowed. Otherwise, they are pushed onto the vector given. |
| pub fn instantiate_mono_trait_ref( |
| &self, |
| trait_ref: &hir::TraitRef<'_>, |
| self_ty: Ty<'tcx>, |
| ) -> ty::TraitRef<'tcx> { |
| self.prohibit_generics(trait_ref.path.segments.split_last().unwrap().1); |
| |
| self.ast_path_to_mono_trait_ref( |
| trait_ref.path.span, |
| trait_ref.trait_def_id().unwrap_or_else(|| FatalError.raise()), |
| self_ty, |
| trait_ref.path.segments.last().unwrap(), |
| ) |
| } |
| |
| /// The given trait-ref must actually be a trait. |
| pub(super) fn instantiate_poly_trait_ref_inner( |
| &self, |
| trait_ref: &hir::TraitRef<'_>, |
| span: Span, |
| constness: Constness, |
| self_ty: Ty<'tcx>, |
| bounds: &mut Bounds<'tcx>, |
| speculative: bool, |
| ) -> GenericArgCountResult { |
| let trait_def_id = trait_ref.trait_def_id().unwrap_or_else(|| FatalError.raise()); |
| |
| debug!("instantiate_poly_trait_ref({:?}, def_id={:?})", trait_ref, trait_def_id); |
| |
| self.prohibit_generics(trait_ref.path.segments.split_last().unwrap().1); |
| |
| let (substs, assoc_bindings, arg_count) = self.create_substs_for_ast_trait_ref( |
| trait_ref.path.span, |
| trait_def_id, |
| self_ty, |
| trait_ref.path.segments.last().unwrap(), |
| ); |
| let poly_trait_ref = ty::Binder::bind(ty::TraitRef::new(trait_def_id, substs)); |
| |
| bounds.trait_bounds.push((poly_trait_ref, span, constness)); |
| |
| let mut dup_bindings = FxHashMap::default(); |
| for binding in &assoc_bindings { |
| // Specify type to assert that error was already reported in `Err` case. |
| let _: Result<_, ErrorReported> = self.add_predicates_for_ast_type_binding( |
| trait_ref.hir_ref_id, |
| poly_trait_ref, |
| binding, |
| bounds, |
| speculative, |
| &mut dup_bindings, |
| binding.span, |
| ); |
| // Okay to ignore `Err` because of `ErrorReported` (see above). |
| } |
| |
| debug!( |
| "instantiate_poly_trait_ref({:?}, bounds={:?}) -> {:?}", |
| trait_ref, bounds, poly_trait_ref |
| ); |
| |
| arg_count |
| } |
| |
| /// Given a trait bound like `Debug`, applies that trait bound the given self-type to construct |
| /// a full trait reference. The resulting trait reference is returned. This may also generate |
| /// auxiliary bounds, which are added to `bounds`. |
| /// |
| /// Example: |
| /// |
| /// ``` |
| /// poly_trait_ref = Iterator<Item = u32> |
| /// self_ty = Foo |
| /// ``` |
| /// |
| /// this would return `Foo: Iterator` and add `<Foo as Iterator>::Item = u32` into `bounds`. |
| /// |
| /// **A note on binders:** against our usual convention, there is an implied bounder around |
| /// the `self_ty` and `poly_trait_ref` parameters here. So they may reference bound regions. |
| /// If for example you had `for<'a> Foo<'a>: Bar<'a>`, then the `self_ty` would be `Foo<'a>` |
| /// where `'a` is a bound region at depth 0. Similarly, the `poly_trait_ref` would be |
| /// `Bar<'a>`. The returned poly-trait-ref will have this binder instantiated explicitly, |
| /// however. |
| pub fn instantiate_poly_trait_ref( |
| &self, |
| poly_trait_ref: &hir::PolyTraitRef<'_>, |
| constness: Constness, |
| self_ty: Ty<'tcx>, |
| bounds: &mut Bounds<'tcx>, |
| ) -> GenericArgCountResult { |
| self.instantiate_poly_trait_ref_inner( |
| &poly_trait_ref.trait_ref, |
| poly_trait_ref.span, |
| constness, |
| self_ty, |
| bounds, |
| false, |
| ) |
| } |
| |
| pub fn instantiate_lang_item_trait_ref( |
| &self, |
| lang_item: hir::LangItem, |
| span: Span, |
| hir_id: hir::HirId, |
| args: &GenericArgs<'_>, |
| self_ty: Ty<'tcx>, |
| bounds: &mut Bounds<'tcx>, |
| ) { |
| let trait_def_id = self.tcx().require_lang_item(lang_item, Some(span)); |
| |
| let (substs, assoc_bindings, _) = |
| self.create_substs_for_ast_path(span, trait_def_id, &[], args, false, Some(self_ty)); |
| let poly_trait_ref = ty::Binder::bind(ty::TraitRef::new(trait_def_id, substs)); |
| bounds.trait_bounds.push((poly_trait_ref, span, Constness::NotConst)); |
| |
| let mut dup_bindings = FxHashMap::default(); |
| for binding in assoc_bindings { |
| let _: Result<_, ErrorReported> = self.add_predicates_for_ast_type_binding( |
| hir_id, |
| poly_trait_ref, |
| &binding, |
| bounds, |
| false, |
| &mut dup_bindings, |
| span, |
| ); |
| } |
| } |
| |
| fn ast_path_to_mono_trait_ref( |
| &self, |
| span: Span, |
| trait_def_id: DefId, |
| self_ty: Ty<'tcx>, |
| trait_segment: &hir::PathSegment<'_>, |
| ) -> ty::TraitRef<'tcx> { |
| let (substs, assoc_bindings, _) = |
| self.create_substs_for_ast_trait_ref(span, trait_def_id, self_ty, trait_segment); |
| if let Some(b) = assoc_bindings.first() { |
| Self::prohibit_assoc_ty_binding(self.tcx(), b.span); |
| } |
| ty::TraitRef::new(trait_def_id, substs) |
| } |
| |
| fn create_substs_for_ast_trait_ref<'a>( |
| &self, |
| span: Span, |
| trait_def_id: DefId, |
| self_ty: Ty<'tcx>, |
| trait_segment: &'a hir::PathSegment<'a>, |
| ) -> (SubstsRef<'tcx>, Vec<ConvertedBinding<'a, 'tcx>>, GenericArgCountResult) { |
| debug!("create_substs_for_ast_trait_ref(trait_segment={:?})", trait_segment); |
| |
| self.complain_about_internal_fn_trait(span, trait_def_id, trait_segment); |
| |
| self.create_substs_for_ast_path( |
| span, |
| trait_def_id, |
| &[], |
| trait_segment.generic_args(), |
| trait_segment.infer_args, |
| Some(self_ty), |
| ) |
| } |
| |
| fn trait_defines_associated_type_named(&self, trait_def_id: DefId, assoc_name: Ident) -> bool { |
| self.tcx() |
| .associated_items(trait_def_id) |
| .find_by_name_and_kind(self.tcx(), assoc_name, ty::AssocKind::Type, trait_def_id) |
| .is_some() |
| } |
| |
| // Returns `true` if a bounds list includes `?Sized`. |
| pub fn is_unsized(&self, ast_bounds: &[hir::GenericBound<'_>], span: Span) -> bool { |
| let tcx = self.tcx(); |
| |
| // Try to find an unbound in bounds. |
| let mut unbound = None; |
| for ab in ast_bounds { |
| if let &hir::GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = ab { |
| if unbound.is_none() { |
| unbound = Some(&ptr.trait_ref); |
| } else { |
| tcx.sess.emit_err(MultipleRelaxedDefaultBounds { span }); |
| } |
| } |
| } |
| |
| let kind_id = tcx.lang_items().require(LangItem::Sized); |
| match unbound { |
| Some(tpb) => { |
| // FIXME(#8559) currently requires the unbound to be built-in. |
| if let Ok(kind_id) = kind_id { |
| if tpb.path.res != Res::Def(DefKind::Trait, kind_id) { |
| tcx.sess.span_warn( |
| span, |
| "default bound relaxed for a type parameter, but \ |
| this does nothing because the given bound is not \ |
| a default; only `?Sized` is supported", |
| ); |
| } |
| } |
| } |
| _ if kind_id.is_ok() => { |
| return false; |
| } |
| // No lang item for `Sized`, so we can't add it as a bound. |
| None => {} |
| } |
| |
| true |
| } |
| |
| /// This helper takes a *converted* parameter type (`param_ty`) |
| /// and an *unconverted* list of bounds: |
| /// |
| /// ```text |
| /// fn foo<T: Debug> |
| /// ^ ^^^^^ `ast_bounds` parameter, in HIR form |
| /// | |
| /// `param_ty`, in ty form |
| /// ``` |
| /// |
| /// It adds these `ast_bounds` into the `bounds` structure. |
| /// |
| /// **A note on binders:** there is an implied binder around |
| /// `param_ty` and `ast_bounds`. See `instantiate_poly_trait_ref` |
| /// for more details. |
| fn add_bounds( |
| &self, |
| param_ty: Ty<'tcx>, |
| ast_bounds: &[hir::GenericBound<'_>], |
| bounds: &mut Bounds<'tcx>, |
| ) { |
| let mut trait_bounds = Vec::new(); |
| let mut region_bounds = Vec::new(); |
| |
| let constness = self.default_constness_for_trait_bounds(); |
| for ast_bound in ast_bounds { |
| match *ast_bound { |
| hir::GenericBound::Trait(ref b, hir::TraitBoundModifier::None) => { |
| trait_bounds.push((b, constness)) |
| } |
| hir::GenericBound::Trait(ref b, hir::TraitBoundModifier::MaybeConst) => { |
| trait_bounds.push((b, Constness::NotConst)) |
| } |
| hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => {} |
| hir::GenericBound::LangItemTrait(lang_item, span, hir_id, args) => self |
| .instantiate_lang_item_trait_ref( |
| lang_item, span, hir_id, args, param_ty, bounds, |
| ), |
| hir::GenericBound::Outlives(ref l) => region_bounds.push(l), |
| } |
| } |
| |
| for (bound, constness) in trait_bounds { |
| let _ = self.instantiate_poly_trait_ref(bound, constness, param_ty, bounds); |
| } |
| |
| bounds.region_bounds.extend( |
| region_bounds.into_iter().map(|r| (self.ast_region_to_region(r, None), r.span)), |
| ); |
| } |
| |
| /// Translates a list of bounds from the HIR into the `Bounds` data structure. |
| /// The self-type for the bounds is given by `param_ty`. |
| /// |
| /// Example: |
| /// |
| /// ``` |
| /// fn foo<T: Bar + Baz>() { } |
| /// ^ ^^^^^^^^^ ast_bounds |
| /// param_ty |
| /// ``` |
| /// |
| /// The `sized_by_default` parameter indicates if, in this context, the `param_ty` should be |
| /// considered `Sized` unless there is an explicit `?Sized` bound. This would be true in the |
| /// example above, but is not true in supertrait listings like `trait Foo: Bar + Baz`. |
| /// |
| /// `span` should be the declaration size of the parameter. |
| pub fn compute_bounds( |
| &self, |
| param_ty: Ty<'tcx>, |
| ast_bounds: &[hir::GenericBound<'_>], |
| sized_by_default: SizedByDefault, |
| span: Span, |
| ) -> Bounds<'tcx> { |
| let mut bounds = Bounds::default(); |
| |
| self.add_bounds(param_ty, ast_bounds, &mut bounds); |
| bounds.trait_bounds.sort_by_key(|(t, _, _)| t.def_id()); |
| |
| bounds.implicitly_sized = if let SizedByDefault::Yes = sized_by_default { |
| if !self.is_unsized(ast_bounds, span) { Some(span) } else { None } |
| } else { |
| None |
| }; |
| |
| bounds |
| } |
| |
| /// Given an HIR binding like `Item = Foo` or `Item: Foo`, pushes the corresponding predicates |
| /// onto `bounds`. |
| /// |
| /// **A note on binders:** given something like `T: for<'a> Iterator<Item = &'a u32>`, the |
| /// `trait_ref` here will be `for<'a> T: Iterator`. The `binding` data however is from *inside* |
| /// the binder (e.g., `&'a u32`) and hence may reference bound regions. |
| fn add_predicates_for_ast_type_binding( |
| &self, |
| hir_ref_id: hir::HirId, |
| trait_ref: ty::PolyTraitRef<'tcx>, |
| binding: &ConvertedBinding<'_, 'tcx>, |
| bounds: &mut Bounds<'tcx>, |
| speculative: bool, |
| dup_bindings: &mut FxHashMap<DefId, Span>, |
| path_span: Span, |
| ) -> Result<(), ErrorReported> { |
| let tcx = self.tcx(); |
| |
| if !speculative { |
| // Given something like `U: SomeTrait<T = X>`, we want to produce a |
| // predicate like `<U as SomeTrait>::T = X`. This is somewhat |
| // subtle in the event that `T` is defined in a supertrait of |
| // `SomeTrait`, because in that case we need to upcast. |
| // |
| // That is, consider this case: |
| // |
| // ``` |
| // trait SubTrait: SuperTrait<i32> { } |
| // trait SuperTrait<A> { type T; } |
| // |
| // ... B: SubTrait<T = foo> ... |
| // ``` |
| // |
| // We want to produce `<B as SuperTrait<i32>>::T == foo`. |
| |
| // Find any late-bound regions declared in `ty` that are not |
| // declared in the trait-ref. These are not well-formed. |
| // |
| // Example: |
| // |
| // for<'a> <T as Iterator>::Item = &'a str // <-- 'a is bad |
| // for<'a> <T as FnMut<(&'a u32,)>>::Output = &'a str // <-- 'a is ok |
| if let ConvertedBindingKind::Equality(ty) = binding.kind { |
| let late_bound_in_trait_ref = |
| tcx.collect_constrained_late_bound_regions(&trait_ref); |
| let late_bound_in_ty = |
| tcx.collect_referenced_late_bound_regions(&ty::Binder::bind(ty)); |
| debug!("late_bound_in_trait_ref = {:?}", late_bound_in_trait_ref); |
| debug!("late_bound_in_ty = {:?}", late_bound_in_ty); |
| |
| // FIXME: point at the type params that don't have appropriate lifetimes: |
| // struct S1<F: for<'a> Fn(&i32, &i32) -> &'a i32>(F); |
| // ---- ---- ^^^^^^^ |
| self.validate_late_bound_regions( |
| late_bound_in_trait_ref, |
| late_bound_in_ty, |
| |br_name| { |
| struct_span_err!( |
| tcx.sess, |
| binding.span, |
| E0582, |
| "binding for associated type `{}` references {}, \ |
| which does not appear in the trait input types", |
| binding.item_name, |
| br_name |
| ) |
| }, |
| ); |
| } |
| } |
| |
| let candidate = |
| if self.trait_defines_associated_type_named(trait_ref.def_id(), binding.item_name) { |
| // Simple case: X is defined in the current trait. |
| trait_ref |
| } else { |
| // Otherwise, we have to walk through the supertraits to find |
| // those that do. |
| self.one_bound_for_assoc_type( |
| || traits::supertraits(tcx, trait_ref), |
| || trait_ref.print_only_trait_path().to_string(), |
| binding.item_name, |
| path_span, |
| || match binding.kind { |
| ConvertedBindingKind::Equality(ty) => Some(ty.to_string()), |
| _ => None, |
| }, |
| )? |
| }; |
| |
| let (assoc_ident, def_scope) = |
| tcx.adjust_ident_and_get_scope(binding.item_name, candidate.def_id(), hir_ref_id); |
| |
| // We have already adjusted the item name above, so compare with `ident.normalize_to_macros_2_0()` instead |
| // of calling `filter_by_name_and_kind`. |
| let assoc_ty = tcx |
| .associated_items(candidate.def_id()) |
| .filter_by_name_unhygienic(assoc_ident.name) |
| .find(|i| { |
| i.kind == ty::AssocKind::Type && i.ident.normalize_to_macros_2_0() == assoc_ident |
| }) |
| .expect("missing associated type"); |
| |
| if !assoc_ty.vis.is_accessible_from(def_scope, tcx) { |
| tcx.sess |
| .struct_span_err( |
| binding.span, |
| &format!("associated type `{}` is private", binding.item_name), |
| ) |
| .span_label(binding.span, "private associated type") |
| .emit(); |
| } |
| tcx.check_stability(assoc_ty.def_id, Some(hir_ref_id), binding.span); |
| |
| if !speculative { |
| dup_bindings |
| .entry(assoc_ty.def_id) |
| .and_modify(|prev_span| { |
| self.tcx().sess.emit_err(ValueOfAssociatedStructAlreadySpecified { |
| span: binding.span, |
| prev_span: *prev_span, |
| item_name: binding.item_name, |
| def_path: tcx.def_path_str(assoc_ty.container.id()), |
| }); |
| }) |
| .or_insert(binding.span); |
| } |
| |
| match binding.kind { |
| ConvertedBindingKind::Equality(ref ty) => { |
| // "Desugar" a constraint like `T: Iterator<Item = u32>` this to |
| // the "projection predicate" for: |
| // |
| // `<T as Iterator>::Item = u32` |
| bounds.projection_bounds.push(( |
| candidate.map_bound(|trait_ref| ty::ProjectionPredicate { |
| projection_ty: ty::ProjectionTy::from_ref_and_name( |
| tcx, |
| trait_ref, |
| binding.item_name, |
| ), |
| ty, |
| }), |
| binding.span, |
| )); |
| } |
| ConvertedBindingKind::Constraint(ast_bounds) => { |
| // "Desugar" a constraint like `T: Iterator<Item: Debug>` to |
| // |
| // `<T as Iterator>::Item: Debug` |
| // |
| // Calling `skip_binder` is okay, because `add_bounds` expects the `param_ty` |
| // parameter to have a skipped binder. |
| let param_ty = tcx.mk_projection(assoc_ty.def_id, candidate.skip_binder().substs); |
| self.add_bounds(param_ty, ast_bounds, bounds); |
| } |
| } |
| Ok(()) |
| } |
| |
| fn ast_path_to_ty( |
| &self, |
| span: Span, |
| did: DefId, |
| item_segment: &hir::PathSegment<'_>, |
| ) -> Ty<'tcx> { |
| let substs = self.ast_path_substs_for_ty(span, did, item_segment); |
| self.normalize_ty(span, self.tcx().at(span).type_of(did).subst(self.tcx(), substs)) |
| } |
| |
| fn conv_object_ty_poly_trait_ref( |
| &self, |
| span: Span, |
| trait_bounds: &[hir::PolyTraitRef<'_>], |
| lifetime: &hir::Lifetime, |
| borrowed: bool, |
| ) -> Ty<'tcx> { |
| let tcx = self.tcx(); |
| |
| let mut bounds = Bounds::default(); |
| let mut potential_assoc_types = Vec::new(); |
| let dummy_self = self.tcx().types.trait_object_dummy_self; |
| for trait_bound in trait_bounds.iter().rev() { |
| if let GenericArgCountResult { |
| correct: |
| Err(GenericArgCountMismatch { invalid_args: cur_potential_assoc_types, .. }), |
| .. |
| } = self.instantiate_poly_trait_ref( |
| trait_bound, |
| Constness::NotConst, |
| dummy_self, |
| &mut bounds, |
| ) { |
| potential_assoc_types.extend(cur_potential_assoc_types.into_iter()); |
| } |
| } |
| |
| // Expand trait aliases recursively and check that only one regular (non-auto) trait |
| // is used and no 'maybe' bounds are used. |
| let expanded_traits = |
| traits::expand_trait_aliases(tcx, bounds.trait_bounds.iter().map(|&(a, b, _)| (a, b))); |
| let (mut auto_traits, regular_traits): (Vec<_>, Vec<_>) = |
| expanded_traits.partition(|i| tcx.trait_is_auto(i.trait_ref().def_id())); |
| if regular_traits.len() > 1 { |
| let first_trait = ®ular_traits[0]; |
| let additional_trait = ®ular_traits[1]; |
| let mut err = struct_span_err!( |
| tcx.sess, |
| additional_trait.bottom().1, |
| E0225, |
| "only auto traits can be used as additional traits in a trait object" |
| ); |
| additional_trait.label_with_exp_info( |
| &mut err, |
| "additional non-auto trait", |
| "additional use", |
| ); |
| first_trait.label_with_exp_info(&mut err, "first non-auto trait", "first use"); |
| err.help(&format!( |
| "consider creating a new trait with all of these as super-traits and using that \ |
| trait here instead: `trait NewTrait: {} {{}}`", |
| regular_traits |
| .iter() |
| .map(|t| t.trait_ref().print_only_trait_path().to_string()) |
| .collect::<Vec<_>>() |
| .join(" + "), |
| )); |
| err.note( |
| "auto-traits like `Send` and `Sync` are traits that have special properties; \ |
| for more information on them, visit \ |
| <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>", |
| ); |
| err.emit(); |
| } |
| |
| if regular_traits.is_empty() && auto_traits.is_empty() { |
| tcx.sess.emit_err(TraitObjectDeclaredWithNoTraits { span }); |
| return tcx.ty_error(); |
| } |
| |
| // Check that there are no gross object safety violations; |
| // most importantly, that the supertraits don't contain `Self`, |
| // to avoid ICEs. |
| for item in ®ular_traits { |
| let object_safety_violations = |
| astconv_object_safety_violations(tcx, item.trait_ref().def_id()); |
| if !object_safety_violations.is_empty() { |
| report_object_safety_error( |
| tcx, |
| span, |
| item.trait_ref().def_id(), |
| &object_safety_violations[..], |
| ) |
| .emit(); |
| return tcx.ty_error(); |
| } |
| } |
| |
| // Use a `BTreeSet` to keep output in a more consistent order. |
| let mut associated_types: FxHashMap<Span, BTreeSet<DefId>> = FxHashMap::default(); |
| |
| let regular_traits_refs_spans = bounds |
| .trait_bounds |
| .into_iter() |
| .filter(|(trait_ref, _, _)| !tcx.trait_is_auto(trait_ref.def_id())); |
| |
| for (base_trait_ref, span, constness) in regular_traits_refs_spans { |
| assert_eq!(constness, Constness::NotConst); |
| |
| for obligation in traits::elaborate_trait_ref(tcx, base_trait_ref) { |
| debug!( |
| "conv_object_ty_poly_trait_ref: observing object predicate `{:?}`", |
| obligation.predicate |
| ); |
| |
| let bound_predicate = obligation.predicate.bound_atom(); |
| match bound_predicate.skip_binder() { |
| ty::PredicateAtom::Trait(pred, _) => { |
| let pred = bound_predicate.rebind(pred); |
| associated_types.entry(span).or_default().extend( |
| tcx.associated_items(pred.def_id()) |
| .in_definition_order() |
| .filter(|item| item.kind == ty::AssocKind::Type) |
| .map(|item| item.def_id), |
| ); |
| } |
| ty::PredicateAtom::Projection(pred) => { |
| let pred = bound_predicate.rebind(pred); |
| // A `Self` within the original bound will be substituted with a |
| // `trait_object_dummy_self`, so check for that. |
| let references_self = |
| pred.skip_binder().ty.walk().any(|arg| arg == dummy_self.into()); |
| |
| // If the projection output contains `Self`, force the user to |
| // elaborate it explicitly to avoid a lot of complexity. |
| // |
| // The "classicaly useful" case is the following: |
| // ``` |
| // trait MyTrait: FnMut() -> <Self as MyTrait>::MyOutput { |
| // type MyOutput; |
| // } |
| // ``` |
| // |
| // Here, the user could theoretically write `dyn MyTrait<Output = X>`, |
| // but actually supporting that would "expand" to an infinitely-long type |
| // `fix $ τ → dyn MyTrait<MyOutput = X, Output = <τ as MyTrait>::MyOutput`. |
| // |
| // Instead, we force the user to write |
| // `dyn MyTrait<MyOutput = X, Output = X>`, which is uglier but works. See |
| // the discussion in #56288 for alternatives. |
| if !references_self { |
| // Include projections defined on supertraits. |
| bounds.projection_bounds.push((pred, span)); |
| } |
| } |
| _ => (), |
| } |
| } |
| } |
| |
| for (projection_bound, _) in &bounds.projection_bounds { |
| for def_ids in associated_types.values_mut() { |
| def_ids.remove(&projection_bound.projection_def_id()); |
| } |
| } |
| |
| self.complain_about_missing_associated_types( |
| associated_types, |
| potential_assoc_types, |
| trait_bounds, |
| ); |
| |
| // De-duplicate auto traits so that, e.g., `dyn Trait + Send + Send` is the same as |
| // `dyn Trait + Send`. |
| auto_traits.sort_by_key(|i| i.trait_ref().def_id()); |
| auto_traits.dedup_by_key(|i| i.trait_ref().def_id()); |
| debug!("regular_traits: {:?}", regular_traits); |
| debug!("auto_traits: {:?}", auto_traits); |
| |
| // Transform a `PolyTraitRef` into a `PolyExistentialTraitRef` by |
| // removing the dummy `Self` type (`trait_object_dummy_self`). |
| let trait_ref_to_existential = |trait_ref: ty::TraitRef<'tcx>| { |
| if trait_ref.self_ty() != dummy_self { |
| // FIXME: There appears to be a missing filter on top of `expand_trait_aliases`, |
| // which picks up non-supertraits where clauses - but also, the object safety |
| // completely ignores trait aliases, which could be object safety hazards. We |
| // `delay_span_bug` here to avoid an ICE in stable even when the feature is |
| // disabled. (#66420) |
| tcx.sess.delay_span_bug( |
| DUMMY_SP, |
| &format!( |
| "trait_ref_to_existential called on {:?} with non-dummy Self", |
| trait_ref, |
| ), |
| ); |
| } |
| ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref) |
| }; |
| |
| // Erase the `dummy_self` (`trait_object_dummy_self`) used above. |
| let existential_trait_refs = |
| regular_traits.iter().map(|i| i.trait_ref().map_bound(trait_ref_to_existential)); |
| let existential_projections = bounds.projection_bounds.iter().map(|(bound, _)| { |
| bound.map_bound(|b| { |
| let trait_ref = trait_ref_to_existential(b.projection_ty.trait_ref(tcx)); |
| ty::ExistentialProjection { |
| ty: b.ty, |
| item_def_id: b.projection_ty.item_def_id, |
| substs: trait_ref.substs, |
| } |
| }) |
| }); |
| |
| // Calling `skip_binder` is okay because the predicates are re-bound. |
| let regular_trait_predicates = existential_trait_refs |
| .map(|trait_ref| ty::ExistentialPredicate::Trait(trait_ref.skip_binder())); |
| let auto_trait_predicates = auto_traits |
| .into_iter() |
| .map(|trait_ref| ty::ExistentialPredicate::AutoTrait(trait_ref.trait_ref().def_id())); |
| let mut v = regular_trait_predicates |
| .chain(auto_trait_predicates) |
| .chain( |
| existential_projections |
| .map(|x| ty::ExistentialPredicate::Projection(x.skip_binder())), |
| ) |
| .collect::<SmallVec<[_; 8]>>(); |
| v.sort_by(|a, b| a.stable_cmp(tcx, b)); |
| v.dedup(); |
| let existential_predicates = ty::Binder::bind(tcx.mk_existential_predicates(v.into_iter())); |
| |
| // Use explicitly-specified region bound. |
| let region_bound = if !lifetime.is_elided() { |
| self.ast_region_to_region(lifetime, None) |
| } else { |
| self.compute_object_lifetime_bound(span, existential_predicates).unwrap_or_else(|| { |
| if tcx.named_region(lifetime.hir_id).is_some() { |
| self.ast_region_to_region(lifetime, None) |
| } else { |
| self.re_infer(None, span).unwrap_or_else(|| { |
| let mut err = struct_span_err!( |
| tcx.sess, |
| span, |
| E0228, |
| "the lifetime bound for this object type cannot be deduced \ |
| from context; please supply an explicit bound" |
| ); |
| if borrowed { |
| // We will have already emitted an error E0106 complaining about a |
| // missing named lifetime in `&dyn Trait`, so we elide this one. |
| err.delay_as_bug(); |
| } else { |
| err.emit(); |
| } |
| tcx.lifetimes.re_static |
| }) |
| } |
| }) |
| }; |
| debug!("region_bound: {:?}", region_bound); |
| |
| let ty = tcx.mk_dynamic(existential_predicates, region_bound); |
| debug!("trait_object_type: {:?}", ty); |
| ty |
| } |
| |
| fn report_ambiguous_associated_type( |
| &self, |
| span: Span, |
| type_str: &str, |
| trait_str: &str, |
| name: Symbol, |
| ) { |
| let mut err = struct_span_err!(self.tcx().sess, span, E0223, "ambiguous associated type"); |
| if let (Some(_), Ok(snippet)) = ( |
| self.tcx().sess.confused_type_with_std_module.borrow().get(&span), |
| self.tcx().sess.source_map().span_to_snippet(span), |
| ) { |
| err.span_suggestion( |
| span, |
| "you are looking for the module in `std`, not the primitive type", |
| format!("std::{}", snippet), |
| Applicability::MachineApplicable, |
| ); |
| } else { |
| err.span_suggestion( |
| span, |
| "use fully-qualified syntax", |
| format!("<{} as {}>::{}", type_str, trait_str, name), |
| Applicability::HasPlaceholders, |
| ); |
| } |
| err.emit(); |
| } |
| |
| // Search for a bound on a type parameter which includes the associated item |
| // given by `assoc_name`. `ty_param_def_id` is the `DefId` of the type parameter |
| // This function will fail if there are no suitable bounds or there is |
| // any ambiguity. |
| fn find_bound_for_assoc_item( |
| &self, |
| ty_param_def_id: LocalDefId, |
| assoc_name: Ident, |
| span: Span, |
| ) -> Result<ty::PolyTraitRef<'tcx>, ErrorReported> { |
| let tcx = self.tcx(); |
| |
| debug!( |
| "find_bound_for_assoc_item(ty_param_def_id={:?}, assoc_name={:?}, span={:?})", |
| ty_param_def_id, assoc_name, span, |
| ); |
| |
| let predicates = |
| &self.get_type_parameter_bounds(span, ty_param_def_id.to_def_id()).predicates; |
| |
| debug!("find_bound_for_assoc_item: predicates={:#?}", predicates); |
| |
| let param_hir_id = tcx.hir().local_def_id_to_hir_id(ty_param_def_id); |
| let param_name = tcx.hir().ty_param_name(param_hir_id); |
| self.one_bound_for_assoc_type( |
| || { |
| traits::transitive_bounds( |
| tcx, |
| predicates.iter().filter_map(|(p, _)| p.to_opt_poly_trait_ref()), |
| ) |
| }, |
| || param_name.to_string(), |
| assoc_name, |
| span, |
| || None, |
| ) |
| } |
| |
| // Checks that `bounds` contains exactly one element and reports appropriate |
| // errors otherwise. |
| fn one_bound_for_assoc_type<I>( |
| &self, |
| all_candidates: impl Fn() -> I, |
| ty_param_name: impl Fn() -> String, |
| assoc_name: Ident, |
| span: Span, |
| is_equality: impl Fn() -> Option<String>, |
| ) -> Result<ty::PolyTraitRef<'tcx>, ErrorReported> |
| where |
| I: Iterator<Item = ty::PolyTraitRef<'tcx>>, |
| { |
| let mut matching_candidates = all_candidates() |
| .filter(|r| self.trait_defines_associated_type_named(r.def_id(), assoc_name)); |
| |
| let bound = match matching_candidates.next() { |
| Some(bound) => bound, |
| None => { |
| self.complain_about_assoc_type_not_found( |
| all_candidates, |
| &ty_param_name(), |
| assoc_name, |
| span, |
| ); |
| return Err(ErrorReported); |
| } |
| }; |
| |
| debug!("one_bound_for_assoc_type: bound = {:?}", bound); |
| |
| if let Some(bound2) = matching_candidates.next() { |
| debug!("one_bound_for_assoc_type: bound2 = {:?}", bound2); |
| |
| let is_equality = is_equality(); |
| let bounds = array::IntoIter::new([bound, bound2]).chain(matching_candidates); |
| let mut err = if is_equality.is_some() { |
| // More specific Error Index entry. |
| struct_span_err!( |
| self.tcx().sess, |
| span, |
| E0222, |
| "ambiguous associated type `{}` in bounds of `{}`", |
| assoc_name, |
| ty_param_name() |
| ) |
| } else { |
| struct_span_err!( |
| self.tcx().sess, |
| span, |
| E0221, |
| "ambiguous associated type `{}` in bounds of `{}`", |
| assoc_name, |
| ty_param_name() |
| ) |
| }; |
| err.span_label(span, format!("ambiguous associated type `{}`", assoc_name)); |
| |
| let mut where_bounds = vec![]; |
| for bound in bounds { |
| let bound_id = bound.def_id(); |
| let bound_span = self |
| .tcx() |
| .associated_items(bound_id) |
| .find_by_name_and_kind(self.tcx(), assoc_name, ty::AssocKind::Type, bound_id) |
| .and_then(|item| self.tcx().hir().span_if_local(item.def_id)); |
| |
| if let Some(bound_span) = bound_span { |
| err.span_label( |
| bound_span, |
| format!( |
| "ambiguous `{}` from `{}`", |
| assoc_name, |
| bound.print_only_trait_path(), |
| ), |
| ); |
| if let Some(constraint) = &is_equality { |
| where_bounds.push(format!( |
| " T: {trait}::{assoc} = {constraint}", |
| trait=bound.print_only_trait_path(), |
| assoc=assoc_name, |
| constraint=constraint, |
| )); |
| } else { |
| err.span_suggestion( |
| span, |
| "use fully qualified syntax to disambiguate", |
| format!( |
| "<{} as {}>::{}", |
| ty_param_name(), |
| bound.print_only_trait_path(), |
| assoc_name, |
| ), |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| } else { |
| err.note(&format!( |
| "associated type `{}` could derive from `{}`", |
| ty_param_name(), |
| bound.print_only_trait_path(), |
| )); |
| } |
| } |
| if !where_bounds.is_empty() { |
| err.help(&format!( |
| "consider introducing a new type parameter `T` and adding `where` constraints:\ |
| \n where\n T: {},\n{}", |
| ty_param_name(), |
| where_bounds.join(",\n"), |
| )); |
| } |
| err.emit(); |
| if !where_bounds.is_empty() { |
| return Err(ErrorReported); |
| } |
| } |
| Ok(bound) |
| } |
| |
| // Create a type from a path to an associated type. |
| // For a path `A::B::C::D`, `qself_ty` and `qself_def` are the type and def for `A::B::C` |
| // and item_segment is the path segment for `D`. We return a type and a def for |
| // the whole path. |
| // Will fail except for `T::A` and `Self::A`; i.e., if `qself_ty`/`qself_def` are not a type |
| // parameter or `Self`. |
| pub fn associated_path_to_ty( |
| &self, |
| hir_ref_id: hir::HirId, |
| span: Span, |
| qself_ty: Ty<'tcx>, |
| qself_res: Res, |
| assoc_segment: &hir::PathSegment<'_>, |
| permit_variants: bool, |
| ) -> Result<(Ty<'tcx>, DefKind, DefId), ErrorReported> { |
| let tcx = self.tcx(); |
| let assoc_ident = assoc_segment.ident; |
| |
| debug!("associated_path_to_ty: {:?}::{}", qself_ty, assoc_ident); |
| |
| // Check if we have an enum variant. |
| let mut variant_resolution = None; |
| if let ty::Adt(adt_def, _) = qself_ty.kind() { |
| if adt_def.is_enum() { |
| let variant_def = adt_def |
| .variants |
| .iter() |
| .find(|vd| tcx.hygienic_eq(assoc_ident, vd.ident, adt_def.did)); |
| if let Some(variant_def) = variant_def { |
| if permit_variants { |
| tcx.check_stability(variant_def.def_id, Some(hir_ref_id), span); |
| self.prohibit_generics(slice::from_ref(assoc_segment)); |
| return Ok((qself_ty, DefKind::Variant, variant_def.def_id)); |
| } else { |
| variant_resolution = Some(variant_def.def_id); |
| } |
| } |
| } |
| } |
| |
| // Find the type of the associated item, and the trait where the associated |
| // item is declared. |
| let bound = match (&qself_ty.kind(), qself_res) { |
| (_, Res::SelfTy(Some(_), Some((impl_def_id, _)))) => { |
| // `Self` in an impl of a trait -- we have a concrete self type and a |
| // trait reference. |
| let trait_ref = match tcx.impl_trait_ref(impl_def_id) { |
| Some(trait_ref) => trait_ref, |
| None => { |
| // A cycle error occurred, most likely. |
| return Err(ErrorReported); |
| } |
| }; |
| |
| self.one_bound_for_assoc_type( |
| || traits::supertraits(tcx, ty::Binder::bind(trait_ref)), |
| || "Self".to_string(), |
| assoc_ident, |
| span, |
| || None, |
| )? |
| } |
| ( |
| &ty::Param(_), |
| Res::SelfTy(Some(param_did), None) | Res::Def(DefKind::TyParam, param_did), |
| ) => self.find_bound_for_assoc_item(param_did.expect_local(), assoc_ident, span)?, |
| _ => { |
| if variant_resolution.is_some() { |
| // Variant in type position |
| let msg = format!("expected type, found variant `{}`", assoc_ident); |
| tcx.sess.span_err(span, &msg); |
| } else if qself_ty.is_enum() { |
| let mut err = struct_span_err!( |
| tcx.sess, |
| assoc_ident.span, |
| E0599, |
| "no variant named `{}` found for enum `{}`", |
| assoc_ident, |
| qself_ty, |
| ); |
| |
| let adt_def = qself_ty.ty_adt_def().expect("enum is not an ADT"); |
| if let Some(suggested_name) = find_best_match_for_name( |
| adt_def.variants.iter().map(|variant| &variant.ident.name), |
| assoc_ident.name, |
| None, |
| ) { |
| err.span_suggestion( |
| assoc_ident.span, |
| "there is a variant with a similar name", |
| suggested_name.to_string(), |
| Applicability::MaybeIncorrect, |
| ); |
| } else { |
| err.span_label( |
| assoc_ident.span, |
| format!("variant not found in `{}`", qself_ty), |
| ); |
| } |
| |
| if let Some(sp) = tcx.hir().span_if_local(adt_def.did) { |
| let sp = tcx.sess.source_map().guess_head_span(sp); |
| err.span_label(sp, format!("variant `{}` not found here", assoc_ident)); |
| } |
| |
| err.emit(); |
| } else if !qself_ty.references_error() { |
| // Don't print `TyErr` to the user. |
| self.report_ambiguous_associated_type( |
| span, |
| &qself_ty.to_string(), |
| "Trait", |
| assoc_ident.name, |
| ); |
| } |
| return Err(ErrorReported); |
| } |
| }; |
| |
| let trait_did = bound.def_id(); |
| let (assoc_ident, def_scope) = |
| tcx.adjust_ident_and_get_scope(assoc_ident, trait_did, hir_ref_id); |
| |
| // We have already adjusted the item name above, so compare with `ident.normalize_to_macros_2_0()` instead |
| // of calling `filter_by_name_and_kind`. |
| let item = tcx |
| .associated_items(trait_did) |
| .in_definition_order() |
| .find(|i| { |
| i.kind.namespace() == Namespace::TypeNS |
| && i.ident.normalize_to_macros_2_0() == assoc_ident |
| }) |
| .expect("missing associated type"); |
| |
| let ty = self.projected_ty_from_poly_trait_ref(span, item.def_id, assoc_segment, bound); |
| let ty = self.normalize_ty(span, ty); |
| |
| let kind = DefKind::AssocTy; |
| if !item.vis.is_accessible_from(def_scope, tcx) { |
| let kind = kind.descr(item.def_id); |
| let msg = format!("{} `{}` is private", kind, assoc_ident); |
| tcx.sess |
| .struct_span_err(span, &msg) |
| .span_label(span, &format!("private {}", kind)) |
| .emit(); |
| } |
| tcx.check_stability(item.def_id, Some(hir_ref_id), span); |
| |
| if let Some(variant_def_id) = variant_resolution { |
| tcx.struct_span_lint_hir(AMBIGUOUS_ASSOCIATED_ITEMS, hir_ref_id, span, |lint| { |
| let mut err = lint.build("ambiguous associated item"); |
| let mut could_refer_to = |kind: DefKind, def_id, also| { |
| let note_msg = format!( |
| "`{}` could{} refer to the {} defined here", |
| assoc_ident, |
| also, |
| kind.descr(def_id) |
| ); |
| err.span_note(tcx.def_span(def_id), ¬e_msg); |
| }; |
| |
| could_refer_to(DefKind::Variant, variant_def_id, ""); |
| could_refer_to(kind, item.def_id, " also"); |
| |
| err.span_suggestion( |
| span, |
| "use fully-qualified syntax", |
| format!("<{} as {}>::{}", qself_ty, tcx.item_name(trait_did), assoc_ident), |
| Applicability::MachineApplicable, |
| ); |
| |
| err.emit(); |
| }); |
| } |
| Ok((ty, kind, item.def_id)) |
| } |
| |
| fn qpath_to_ty( |
| &self, |
| span: Span, |
| opt_self_ty: Option<Ty<'tcx>>, |
| item_def_id: DefId, |
| trait_segment: &hir::PathSegment<'_>, |
| item_segment: &hir::PathSegment<'_>, |
| ) -> Ty<'tcx> { |
| let tcx = self.tcx(); |
| |
| let trait_def_id = tcx.parent(item_def_id).unwrap(); |
| |
| debug!("qpath_to_ty: trait_def_id={:?}", trait_def_id); |
| |
| let self_ty = if let Some(ty) = opt_self_ty { |
| ty |
| } else { |
| let path_str = tcx.def_path_str(trait_def_id); |
| |
| let def_id = self.item_def_id(); |
| |
| debug!("qpath_to_ty: self.item_def_id()={:?}", def_id); |
| |
| let parent_def_id = def_id |
| .and_then(|def_id| { |
| def_id.as_local().map(|def_id| tcx.hir().local_def_id_to_hir_id(def_id)) |
| }) |
| .map(|hir_id| tcx.hir().get_parent_did(hir_id).to_def_id()); |
| |
| debug!("qpath_to_ty: parent_def_id={:?}", parent_def_id); |
| |
| // If the trait in segment is the same as the trait defining the item, |
| // use the `<Self as ..>` syntax in the error. |
| let is_part_of_self_trait_constraints = def_id == Some(trait_def_id); |
| let is_part_of_fn_in_self_trait = parent_def_id == Some(trait_def_id); |
| |
| let type_name = if is_part_of_self_trait_constraints || is_part_of_fn_in_self_trait { |
| "Self" |
| } else { |
| "Type" |
| }; |
| |
| self.report_ambiguous_associated_type( |
| span, |
| type_name, |
| &path_str, |
| item_segment.ident.name, |
| ); |
| return tcx.ty_error(); |
| }; |
| |
| debug!("qpath_to_ty: self_type={:?}", self_ty); |
| |
| let trait_ref = self.ast_path_to_mono_trait_ref(span, trait_def_id, self_ty, trait_segment); |
| |
| let item_substs = self.create_substs_for_associated_item( |
| tcx, |
| span, |
| item_def_id, |
| item_segment, |
| trait_ref.substs, |
| ); |
| |
| debug!("qpath_to_ty: trait_ref={:?}", trait_ref); |
| |
| self.normalize_ty(span, tcx.mk_projection(item_def_id, item_substs)) |
| } |
| |
| pub fn prohibit_generics<'a, T: IntoIterator<Item = &'a hir::PathSegment<'a>>>( |
| &self, |
| segments: T, |
| ) -> bool { |
| let mut has_err = false; |
| for segment in segments { |
| let (mut err_for_lt, mut err_for_ty, mut err_for_ct) = (false, false, false); |
| for arg in segment.generic_args().args { |
| let (span, kind) = match arg { |
| hir::GenericArg::Lifetime(lt) => { |
| if err_for_lt { |
| continue; |
| } |
| err_for_lt = true; |
| has_err = true; |
| (lt.span, "lifetime") |
| } |
| hir::GenericArg::Type(ty) => { |
| if err_for_ty { |
| continue; |
| } |
| err_for_ty = true; |
| has_err = true; |
| (ty.span, "type") |
| } |
| hir::GenericArg::Const(ct) => { |
| if err_for_ct { |
| continue; |
| } |
| err_for_ct = true; |
| has_err = true; |
| (ct.span, "const") |
| } |
| }; |
| let mut err = struct_span_err!( |
| self.tcx().sess, |
| span, |
| E0109, |
| "{} arguments are not allowed for this type", |
| kind, |
| ); |
| err.span_label(span, format!("{} argument not allowed", kind)); |
| err.emit(); |
| if err_for_lt && err_for_ty && err_for_ct { |
| break; |
| } |
| } |
| |
| // Only emit the first error to avoid overloading the user with error messages. |
| if let [binding, ..] = segment.generic_args().bindings { |
| has_err = true; |
| Self::prohibit_assoc_ty_binding(self.tcx(), binding.span); |
| } |
| } |
| has_err |
| } |
| |
| // FIXME(eddyb, varkor) handle type paths here too, not just value ones. |
| pub fn def_ids_for_value_path_segments( |
| &self, |
| segments: &[hir::PathSegment<'_>], |
| self_ty: Option<Ty<'tcx>>, |
| kind: DefKind, |
| def_id: DefId, |
| ) -> Vec<PathSeg> { |
| // We need to extract the type parameters supplied by the user in |
| // the path `path`. Due to the current setup, this is a bit of a |
| // tricky-process; the problem is that resolve only tells us the |
| // end-point of the path resolution, and not the intermediate steps. |
| // Luckily, we can (at least for now) deduce the intermediate steps |
| // just from the end-point. |
| // |
| // There are basically five cases to consider: |
| // |
| // 1. Reference to a constructor of a struct: |
| // |
| // struct Foo<T>(...) |
| // |
| // In this case, the parameters are declared in the type space. |
| // |
| // 2. Reference to a constructor of an enum variant: |
| // |
| // enum E<T> { Foo(...) } |
| // |
| // In this case, the parameters are defined in the type space, |
| // but may be specified either on the type or the variant. |
| // |
| // 3. Reference to a fn item or a free constant: |
| // |
| // fn foo<T>() { } |
| // |
| // In this case, the path will again always have the form |
| // `a::b::foo::<T>` where only the final segment should have |
| // type parameters. However, in this case, those parameters are |
| // declared on a value, and hence are in the `FnSpace`. |
| // |
| // 4. Reference to a method or an associated constant: |
| // |
| // impl<A> SomeStruct<A> { |
| // fn foo<B>(...) |
| // } |
| // |
| // Here we can have a path like |
| // `a::b::SomeStruct::<A>::foo::<B>`, in which case parameters |
| // may appear in two places. The penultimate segment, |
| // `SomeStruct::<A>`, contains parameters in TypeSpace, and the |
| // final segment, `foo::<B>` contains parameters in fn space. |
| // |
| // The first step then is to categorize the segments appropriately. |
| |
| let tcx = self.tcx(); |
| |
| assert!(!segments.is_empty()); |
| let last = segments.len() - 1; |
| |
| let mut path_segs = vec![]; |
| |
| match kind { |
| // Case 1. Reference to a struct constructor. |
| DefKind::Ctor(CtorOf::Struct, ..) => { |
| // Everything but the final segment should have no |
| // parameters at all. |
| let generics = tcx.generics_of(def_id); |
| // Variant and struct constructors use the |
| // generics of their parent type definition. |
| let generics_def_id = generics.parent.unwrap_or(def_id); |
| path_segs.push(PathSeg(generics_def_id, last)); |
| } |
| |
| // Case 2. Reference to a variant constructor. |
| DefKind::Ctor(CtorOf::Variant, ..) | DefKind::Variant => { |
| let adt_def = self_ty.map(|t| t.ty_adt_def().unwrap()); |
| let (generics_def_id, index) = if let Some(adt_def) = adt_def { |
| debug_assert!(adt_def.is_enum()); |
| (adt_def.did, last) |
| } else if last >= 1 && segments[last - 1].args.is_some() { |
| // Everything but the penultimate segment should have no |
| // parameters at all. |
| let mut def_id = def_id; |
| |
| // `DefKind::Ctor` -> `DefKind::Variant` |
| if let DefKind::Ctor(..) = kind { |
| def_id = tcx.parent(def_id).unwrap() |
| } |
| |
| // `DefKind::Variant` -> `DefKind::Enum` |
| let enum_def_id = tcx.parent(def_id).unwrap(); |
| (enum_def_id, last - 1) |
| } else { |
| // FIXME: lint here recommending `Enum::<...>::Variant` form |
| // instead of `Enum::Variant::<...>` form. |
| |
| // Everything but the final segment should have no |
| // parameters at all. |
| let generics = tcx.generics_of(def_id); |
| // Variant and struct constructors use the |
| // generics of their parent type definition. |
| (generics.parent.unwrap_or(def_id), last) |
| }; |
| path_segs.push(PathSeg(generics_def_id, index)); |
| } |
| |
| // Case 3. Reference to a top-level value. |
| DefKind::Fn | DefKind::Const | DefKind::ConstParam | DefKind::Static => { |
| path_segs.push(PathSeg(def_id, last)); |
| } |
| |
| // Case 4. Reference to a method or associated const. |
| DefKind::AssocFn | DefKind::AssocConst => { |
| if segments.len() >= 2 { |
| let generics = tcx.generics_of(def_id); |
| path_segs.push(PathSeg(generics.parent.unwrap(), last - 1)); |
| } |
| path_segs.push(PathSeg(def_id, last)); |
| } |
| |
| kind => bug!("unexpected definition kind {:?} for {:?}", kind, def_id), |
| } |
| |
| debug!("path_segs = {:?}", path_segs); |
| |
| path_segs |
| } |
| |
| // Check a type `Path` and convert it to a `Ty`. |
| pub fn res_to_ty( |
| &self, |
| opt_self_ty: Option<Ty<'tcx>>, |
| path: &hir::Path<'_>, |
| permit_variants: bool, |
| ) -> Ty<'tcx> { |
| let tcx = self.tcx(); |
| |
| debug!( |
| "res_to_ty(res={:?}, opt_self_ty={:?}, path_segments={:?})", |
| path.res, opt_self_ty, path.segments |
| ); |
| |
| let span = path.span; |
| match path.res { |
| Res::Def(DefKind::OpaqueTy, did) => { |
| // Check for desugared `impl Trait`. |
| assert!(ty::is_impl_trait_defn(tcx, did).is_none()); |
| let item_segment = path.segments.split_last().unwrap(); |
| self.prohibit_generics(item_segment.1); |
| let substs = self.ast_path_substs_for_ty(span, did, item_segment.0); |
| self.normalize_ty(span, tcx.mk_opaque(did, substs)) |
| } |
| Res::Def( |
| DefKind::Enum |
| | DefKind::TyAlias |
| | DefKind::Struct |
| | DefKind::Union |
| | DefKind::ForeignTy, |
| did, |
| ) => { |
| assert_eq!(opt_self_ty, None); |
| self.prohibit_generics(path.segments.split_last().unwrap().1); |
| self.ast_path_to_ty(span, did, path.segments.last().unwrap()) |
| } |
| Res::Def(kind @ DefKind::Variant, def_id) if permit_variants => { |
| // Convert "variant type" as if it were a real type. |
| // The resulting `Ty` is type of the variant's enum for now. |
| assert_eq!(opt_self_ty, None); |
| |
| let path_segs = |
| self.def_ids_for_value_path_segments(&path.segments, None, kind, def_id); |
| let generic_segs: FxHashSet<_> = |
| path_segs.iter().map(|PathSeg(_, index)| index).collect(); |
| self.prohibit_generics(path.segments.iter().enumerate().filter_map( |
| |(index, seg)| { |
| if !generic_segs.contains(&index) { Some(seg) } else { None } |
| }, |
| )); |
| |
| let PathSeg(def_id, index) = path_segs.last().unwrap(); |
| self.ast_path_to_ty(span, *def_id, &path.segments[*index]) |
| } |
| Res::Def(DefKind::TyParam, def_id) => { |
| assert_eq!(opt_self_ty, None); |
| self.prohibit_generics(path.segments); |
| |
| let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local()); |
| let item_id = tcx.hir().get_parent_node(hir_id); |
| let item_def_id = tcx.hir().local_def_id(item_id); |
| let generics = tcx.generics_of(item_def_id); |
| let index = generics.param_def_id_to_index[&def_id]; |
| tcx.mk_ty_param(index, tcx.hir().name(hir_id)) |
| } |
| Res::SelfTy(Some(_), None) => { |
| // `Self` in trait or type alias. |
| assert_eq!(opt_self_ty, None); |
| self.prohibit_generics(path.segments); |
| tcx.types.self_param |
| } |
| Res::SelfTy(_, Some((def_id, forbid_generic))) => { |
| // `Self` in impl (we know the concrete type). |
| assert_eq!(opt_self_ty, None); |
| self.prohibit_generics(path.segments); |
| // Try to evaluate any array length constants. |
| let normalized_ty = self.normalize_ty(span, tcx.at(span).type_of(def_id)); |
| if forbid_generic && normalized_ty.needs_subst() { |
| let mut err = tcx.sess.struct_span_err( |
| path.span, |
| "generic `Self` types are currently not permitted in anonymous constants", |
| ); |
| if let Some(hir::Node::Item(&hir::Item { |
| kind: hir::ItemKind::Impl { self_ty, .. }, |
| .. |
| })) = tcx.hir().get_if_local(def_id) |
| { |
| err.span_note(self_ty.span, "not a concrete type"); |
| } |
| err.emit(); |
| tcx.ty_error() |
| } else { |
| normalized_ty |
| } |
| } |
| Res::Def(DefKind::AssocTy, def_id) => { |
| debug_assert!(path.segments.len() >= 2); |
| self.prohibit_generics(&path.segments[..path.segments.len() - 2]); |
| self.qpath_to_ty( |
| span, |
| opt_self_ty, |
| def_id, |
| &path.segments[path.segments.len() - 2], |
| path.segments.last().unwrap(), |
| ) |
| } |
| Res::PrimTy(prim_ty) => { |
| assert_eq!(opt_self_ty, None); |
| self.prohibit_generics(path.segments); |
| match prim_ty { |
| hir::PrimTy::Bool => tcx.types.bool, |
| hir::PrimTy::Char => tcx.types.char, |
| hir::PrimTy::Int(it) => tcx.mk_mach_int(it), |
| hir::PrimTy::Uint(uit) => tcx.mk_mach_uint(uit), |
| hir::PrimTy::Float(ft) => tcx.mk_mach_float(ft), |
| hir::PrimTy::Str => tcx.types.str_, |
| } |
| } |
| Res::Err => { |
| self.set_tainted_by_errors(); |
| self.tcx().ty_error() |
| } |
| _ => span_bug!(span, "unexpected resolution: {:?}", path.res), |
| } |
| } |
| |
| /// Parses the programmer's textual representation of a type into our |
| /// internal notion of a type. |
| pub fn ast_ty_to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> { |
| self.ast_ty_to_ty_inner(ast_ty, false) |
| } |
| |
| /// Turns a `hir::Ty` into a `Ty`. For diagnostics' purposes we keep track of whether trait |
| /// objects are borrowed like `&dyn Trait` to avoid emitting redundant errors. |
| fn ast_ty_to_ty_inner(&self, ast_ty: &hir::Ty<'_>, borrowed: bool) -> Ty<'tcx> { |
| debug!("ast_ty_to_ty(id={:?}, ast_ty={:?} ty_ty={:?})", ast_ty.hir_id, ast_ty, ast_ty.kind); |
| |
| let tcx = self.tcx(); |
| |
| let result_ty = match ast_ty.kind { |
| hir::TyKind::Slice(ref ty) => tcx.mk_slice(self.ast_ty_to_ty(&ty)), |
| hir::TyKind::Ptr(ref mt) => { |
| tcx.mk_ptr(ty::TypeAndMut { ty: self.ast_ty_to_ty(&mt.ty), mutbl: mt.mutbl }) |
| } |
| hir::TyKind::Rptr(ref region, ref mt) => { |
| let r = self.ast_region_to_region(region, None); |
| debug!("ast_ty_to_ty: r={:?}", r); |
| let t = self.ast_ty_to_ty_inner(&mt.ty, true); |
| tcx.mk_ref(r, ty::TypeAndMut { ty: t, mutbl: mt.mutbl }) |
| } |
| hir::TyKind::Never => tcx.types.never, |
| hir::TyKind::Tup(ref fields) => { |
| tcx.mk_tup(fields.iter().map(|t| self.ast_ty_to_ty(&t))) |
| } |
| hir::TyKind::BareFn(ref bf) => { |
| require_c_abi_if_c_variadic(tcx, &bf.decl, bf.abi, ast_ty.span); |
| tcx.mk_fn_ptr(self.ty_of_fn( |
| bf.unsafety, |
| bf.abi, |
| &bf.decl, |
| &hir::Generics::empty(), |
| None, |
| )) |
| } |
| hir::TyKind::TraitObject(ref bounds, ref lifetime) => { |
| self.conv_object_ty_poly_trait_ref(ast_ty.span, bounds, lifetime, borrowed) |
| } |
| hir::TyKind::Path(hir::QPath::Resolved(ref maybe_qself, ref path)) => { |
| debug!("ast_ty_to_ty: maybe_qself={:?} path={:?}", maybe_qself, path); |
| let opt_self_ty = maybe_qself.as_ref().map(|qself| self.ast_ty_to_ty(qself)); |
| self.res_to_ty(opt_self_ty, path, false) |
| } |
| hir::TyKind::OpaqueDef(item_id, ref lifetimes) => { |
| let opaque_ty = tcx.hir().expect_item(item_id.id); |
| let def_id = tcx.hir().local_def_id(item_id.id).to_def_id(); |
| |
| match opaque_ty.kind { |
| hir::ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => { |
| self.impl_trait_ty_to_ty(def_id, lifetimes, impl_trait_fn.is_some()) |
| } |
| ref i => bug!("`impl Trait` pointed to non-opaque type?? {:#?}", i), |
| } |
| } |
| hir::TyKind::Path(hir::QPath::TypeRelative(ref qself, ref segment)) => { |
| debug!("ast_ty_to_ty: qself={:?} segment={:?}", qself, segment); |
| let ty = self.ast_ty_to_ty(qself); |
| |
| let res = if let hir::TyKind::Path(hir::QPath::Resolved(_, ref path)) = qself.kind { |
| path.res |
| } else { |
| Res::Err |
| }; |
| self.associated_path_to_ty(ast_ty.hir_id, ast_ty.span, ty, res, segment, false) |
| .map(|(ty, _, _)| ty) |
| .unwrap_or_else(|_| tcx.ty_error()) |
| } |
| hir::TyKind::Path(hir::QPath::LangItem(lang_item, span)) => { |
| let def_id = tcx.require_lang_item(lang_item, Some(span)); |
| let (substs, _, _) = self.create_substs_for_ast_path( |
| span, |
| def_id, |
| &[], |
| &GenericArgs::none(), |
| true, |
| None, |
| ); |
| self.normalize_ty(span, tcx.at(span).type_of(def_id).subst(tcx, substs)) |
| } |
| hir::TyKind::Array(ref ty, ref length) => { |
| let length_def_id = tcx.hir().local_def_id(length.hir_id); |
| let length = ty::Const::from_anon_const(tcx, length_def_id); |
| let array_ty = tcx.mk_ty(ty::Array(self.ast_ty_to_ty(&ty), length)); |
| self.normalize_ty(ast_ty.span, array_ty) |
| } |
| hir::TyKind::Typeof(ref _e) => { |
| tcx.sess.emit_err(TypeofReservedKeywordUsed { span: ast_ty.span }); |
| tcx.ty_error() |
| } |
| hir::TyKind::Infer => { |
| // Infer also appears as the type of arguments or return |
| // values in a ExprKind::Closure, or as |
| // the type of local variables. Both of these cases are |
| // handled specially and will not descend into this routine. |
| self.ty_infer(None, ast_ty.span) |
| } |
| hir::TyKind::Err => tcx.ty_error(), |
| }; |
| |
| debug!("ast_ty_to_ty: result_ty={:?}", result_ty); |
| |
| self.record_ty(ast_ty.hir_id, result_ty, ast_ty.span); |
| result_ty |
| } |
| |
| pub fn impl_trait_ty_to_ty( |
| &self, |
| def_id: DefId, |
| lifetimes: &[hir::GenericArg<'_>], |
| replace_parent_lifetimes: bool, |
| ) -> Ty<'tcx> { |
| debug!("impl_trait_ty_to_ty(def_id={:?}, lifetimes={:?})", def_id, lifetimes); |
| let tcx = self.tcx(); |
| |
| let generics = tcx.generics_of(def_id); |
| |
| debug!("impl_trait_ty_to_ty: generics={:?}", generics); |
| let substs = InternalSubsts::for_item(tcx, def_id, |param, _| { |
| if let Some(i) = (param.index as usize).checked_sub(generics.parent_count) { |
| // Our own parameters are the resolved lifetimes. |
| match param.kind { |
| GenericParamDefKind::Lifetime => { |
| if let hir::GenericArg::Lifetime(lifetime) = &lifetimes[i] { |
| self.ast_region_to_region(lifetime, None).into() |
| } else { |
| bug!() |
| } |
| } |
| _ => bug!(), |
| } |
| } else { |
| match param.kind { |
| // For RPIT (return position impl trait), only lifetimes |
| // mentioned in the impl Trait predicate are captured by |
| // the opaque type, so the lifetime parameters from the |
| // parent item need to be replaced with `'static`. |
| // |
| // For `impl Trait` in the types of statics, constants, |
| // locals and type aliases. These capture all parent |
| // lifetimes, so they can use their identity subst. |
| GenericParamDefKind::Lifetime if replace_parent_lifetimes => { |
| tcx.lifetimes.re_static.into() |
| } |
| _ => tcx.mk_param_from_def(param), |
| } |
| } |
| }); |
| debug!("impl_trait_ty_to_ty: substs={:?}", substs); |
| |
| let ty = tcx.mk_opaque(def_id, substs); |
| debug!("impl_trait_ty_to_ty: {}", ty); |
| ty |
| } |
| |
| pub fn ty_of_arg(&self, ty: &hir::Ty<'_>, expected_ty: Option<Ty<'tcx>>) -> Ty<'tcx> { |
| match ty.kind { |
| hir::TyKind::Infer if expected_ty.is_some() => { |
| self.record_ty(ty.hir_id, expected_ty.unwrap(), ty.span); |
| expected_ty.unwrap() |
| } |
| _ => self.ast_ty_to_ty(ty), |
| } |
| } |
| |
| pub fn ty_of_fn( |
| &self, |
| unsafety: hir::Unsafety, |
| abi: abi::Abi, |
| decl: &hir::FnDecl<'_>, |
| generics: &hir::Generics<'_>, |
| ident_span: Option<Span>, |
| ) -> ty::PolyFnSig<'tcx> { |
| debug!("ty_of_fn"); |
| |
| let tcx = self.tcx(); |
| |
| // We proactively collect all the inferred type params to emit a single error per fn def. |
| let mut visitor = PlaceholderHirTyCollector::default(); |
| for ty in decl.inputs { |
| visitor.visit_ty(ty); |
| } |
| walk_generics(&mut visitor, generics); |
| |
| let input_tys = decl.inputs.iter().map(|a| self.ty_of_arg(a, None)); |
| let output_ty = match decl.output { |
| hir::FnRetTy::Return(ref output) => { |
| visitor.visit_ty(output); |
| self.ast_ty_to_ty(output) |
| } |
| hir::FnRetTy::DefaultReturn(..) => tcx.mk_unit(), |
| }; |
| |
| debug!("ty_of_fn: output_ty={:?}", output_ty); |
| |
| let bare_fn_ty = |
| ty::Binder::bind(tcx.mk_fn_sig(input_tys, output_ty, decl.c_variadic, unsafety, abi)); |
| |
| if !self.allow_ty_infer() { |
| // We always collect the spans for placeholder types when evaluating `fn`s, but we |
| // only want to emit an error complaining about them if infer types (`_`) are not |
| // allowed. `allow_ty_infer` gates this behavior. We check for the presence of |
| // `ident_span` to not emit an error twice when we have `fn foo(_: fn() -> _)`. |
| crate::collect::placeholder_type_error( |
| tcx, |
| ident_span.map(|sp| sp.shrink_to_hi()), |
| &generics.params[..], |
| visitor.0, |
| true, |
| ); |
| } |
| |
| // Find any late-bound regions declared in return type that do |
| // not appear in the arguments. These are not well-formed. |
| // |
| // Example: |
| // for<'a> fn() -> &'a str <-- 'a is bad |
| // for<'a> fn(&'a String) -> &'a str <-- 'a is ok |
| let inputs = bare_fn_ty.inputs(); |
| let late_bound_in_args = |
| tcx.collect_constrained_late_bound_regions(&inputs.map_bound(|i| i.to_owned())); |
| let output = bare_fn_ty.output(); |
| let late_bound_in_ret = tcx.collect_referenced_late_bound_regions(&output); |
| |
| self.validate_late_bound_regions(late_bound_in_args, late_bound_in_ret, |br_name| { |
| struct_span_err!( |
| tcx.sess, |
| decl.output.span(), |
| E0581, |
| "return type references {}, which is not constrained by the fn input types", |
| br_name |
| ) |
| }); |
| |
| bare_fn_ty |
| } |
| |
| fn validate_late_bound_regions( |
| &self, |
| constrained_regions: FxHashSet<ty::BoundRegion>, |
| referenced_regions: FxHashSet<ty::BoundRegion>, |
| generate_err: impl Fn(&str) -> rustc_errors::DiagnosticBuilder<'tcx>, |
| ) { |
| for br in referenced_regions.difference(&constrained_regions) { |
| let br_name = match *br { |
| ty::BrNamed(_, name) => format!("lifetime `{}`", name), |
| ty::BrAnon(_) | ty::BrEnv => "an anonymous lifetime".to_string(), |
| }; |
| |
| let mut err = generate_err(&br_name); |
| |
| if let ty::BrAnon(_) = *br { |
| // The only way for an anonymous lifetime to wind up |
| // in the return type but **also** be unconstrained is |
| // if it only appears in "associated types" in the |
| // input. See #47511 and #62200 for examples. In this case, |
| // though we can easily give a hint that ought to be |
| // relevant. |
| err.note( |
| "lifetimes appearing in an associated type are not considered constrained", |
| ); |
| } |
| |
| err.emit(); |
| } |
| } |
| |
| /// Given the bounds on an object, determines what single region bound (if any) we can |
| /// use to summarize this type. The basic idea is that we will use the bound the user |
| /// provided, if they provided one, and otherwise search the supertypes of trait bounds |
| /// for region bounds. It may be that we can derive no bound at all, in which case |
| /// we return `None`. |
| fn compute_object_lifetime_bound( |
| &self, |
| span: Span, |
| existential_predicates: ty::Binder<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>>, |
| ) -> Option<ty::Region<'tcx>> // if None, use the default |
| { |
| let tcx = self.tcx(); |
| |
| debug!("compute_opt_region_bound(existential_predicates={:?})", existential_predicates); |
| |
| // No explicit region bound specified. Therefore, examine trait |
| // bounds and see if we can derive region bounds from those. |
| let derived_region_bounds = object_region_bounds(tcx, existential_predicates); |
| |
| // If there are no derived region bounds, then report back that we |
| // can find no region bound. The caller will use the default. |
| if derived_region_bounds.is_empty() { |
| return None; |
| } |
| |
| // If any of the derived region bounds are 'static, that is always |
| // the best choice. |
| if derived_region_bounds.iter().any(|&r| ty::ReStatic == *r) { |
| return Some(tcx.lifetimes.re_static); |
| } |
| |
| // Determine whether there is exactly one unique region in the set |
| // of derived region bounds. If so, use that. Otherwise, report an |
| // error. |
| let r = derived_region_bounds[0]; |
| if derived_region_bounds[1..].iter().any(|r1| r != *r1) { |
| tcx.sess.emit_err(AmbiguousLifetimeBound { span }); |
| } |
| Some(r) |
| } |
| } |