| use crate::astconv::{ |
| AstConv, ExplicitLateBound, GenericArgCountMismatch, GenericArgCountResult, PathSeg, |
| }; |
| use crate::check::callee::{self, DeferredCallResolution}; |
| use crate::check::method::{self, MethodCallee, SelfSource}; |
| use crate::check::{BreakableCtxt, Diverges, Expectation, FallbackMode, FnCtxt, LocalTy}; |
| |
| use rustc_data_structures::captures::Captures; |
| use rustc_data_structures::fx::FxHashSet; |
| use rustc_errors::{Applicability, DiagnosticBuilder, ErrorReported}; |
| use rustc_hir as hir; |
| use rustc_hir::def::{CtorOf, DefKind, Res}; |
| use rustc_hir::def_id::DefId; |
| use rustc_hir::lang_items::LangItem; |
| use rustc_hir::{ExprKind, GenericArg, Node, QPath}; |
| use rustc_infer::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse}; |
| use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282; |
| use rustc_infer::infer::{InferOk, InferResult}; |
| use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability}; |
| use rustc_middle::ty::fold::TypeFoldable; |
| use rustc_middle::ty::subst::{ |
| self, GenericArgKind, InternalSubsts, Subst, SubstsRef, UserSelfTy, UserSubsts, |
| }; |
| use rustc_middle::ty::{ |
| self, AdtKind, CanonicalUserType, DefIdTree, GenericParamDefKind, ToPolyTraitRef, ToPredicate, |
| Ty, UserType, |
| }; |
| use rustc_session::lint; |
| use rustc_span::hygiene::DesugaringKind; |
| use rustc_span::source_map::{original_sp, DUMMY_SP}; |
| use rustc_span::symbol::{kw, sym, Ident}; |
| use rustc_span::{self, BytePos, MultiSpan, Span}; |
| use rustc_trait_selection::infer::InferCtxtExt as _; |
| use rustc_trait_selection::opaque_types::InferCtxtExt as _; |
| use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _; |
| use rustc_trait_selection::traits::{self, ObligationCauseCode, TraitEngine, TraitEngineExt}; |
| |
| use std::collections::hash_map::Entry; |
| use std::slice; |
| |
| impl<'a, 'tcx> FnCtxt<'a, 'tcx> { |
| /// Produces warning on the given node, if the current point in the |
| /// function is unreachable, and there hasn't been another warning. |
| pub(in super::super) fn warn_if_unreachable(&self, id: hir::HirId, span: Span, kind: &str) { |
| // FIXME: Combine these two 'if' expressions into one once |
| // let chains are implemented |
| if let Diverges::Always { span: orig_span, custom_note } = self.diverges.get() { |
| // If span arose from a desugaring of `if` or `while`, then it is the condition itself, |
| // which diverges, that we are about to lint on. This gives suboptimal diagnostics. |
| // Instead, stop here so that the `if`- or `while`-expression's block is linted instead. |
| if !span.is_desugaring(DesugaringKind::CondTemporary) |
| && !span.is_desugaring(DesugaringKind::Async) |
| && !orig_span.is_desugaring(DesugaringKind::Await) |
| { |
| self.diverges.set(Diverges::WarnedAlways); |
| |
| debug!("warn_if_unreachable: id={:?} span={:?} kind={}", id, span, kind); |
| |
| self.tcx().struct_span_lint_hir(lint::builtin::UNREACHABLE_CODE, id, span, |lint| { |
| let msg = format!("unreachable {}", kind); |
| lint.build(&msg) |
| .span_label(span, &msg) |
| .span_label( |
| orig_span, |
| custom_note |
| .unwrap_or("any code following this expression is unreachable"), |
| ) |
| .emit(); |
| }) |
| } |
| } |
| } |
| |
| /// Resolves type and const variables in `ty` if possible. Unlike the infcx |
| /// version (resolve_vars_if_possible), this version will |
| /// also select obligations if it seems useful, in an effort |
| /// to get more type information. |
| pub(in super::super) fn resolve_vars_with_obligations(&self, mut ty: Ty<'tcx>) -> Ty<'tcx> { |
| debug!("resolve_vars_with_obligations(ty={:?})", ty); |
| |
| // No Infer()? Nothing needs doing. |
| if !ty.has_infer_types_or_consts() { |
| debug!("resolve_vars_with_obligations: ty={:?}", ty); |
| return ty; |
| } |
| |
| // If `ty` is a type variable, see whether we already know what it is. |
| ty = self.resolve_vars_if_possible(&ty); |
| if !ty.has_infer_types_or_consts() { |
| debug!("resolve_vars_with_obligations: ty={:?}", ty); |
| return ty; |
| } |
| |
| // If not, try resolving pending obligations as much as |
| // possible. This can help substantially when there are |
| // indirect dependencies that don't seem worth tracking |
| // precisely. |
| self.select_obligations_where_possible(false, |_| {}); |
| ty = self.resolve_vars_if_possible(&ty); |
| |
| debug!("resolve_vars_with_obligations: ty={:?}", ty); |
| ty |
| } |
| |
| pub(in super::super) fn record_deferred_call_resolution( |
| &self, |
| closure_def_id: DefId, |
| r: DeferredCallResolution<'tcx>, |
| ) { |
| let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut(); |
| deferred_call_resolutions.entry(closure_def_id).or_default().push(r); |
| } |
| |
| pub(in super::super) fn remove_deferred_call_resolutions( |
| &self, |
| closure_def_id: DefId, |
| ) -> Vec<DeferredCallResolution<'tcx>> { |
| let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut(); |
| deferred_call_resolutions.remove(&closure_def_id).unwrap_or(vec![]) |
| } |
| |
| pub fn tag(&self) -> String { |
| format!("{:p}", self) |
| } |
| |
| pub fn local_ty(&self, span: Span, nid: hir::HirId) -> LocalTy<'tcx> { |
| self.locals.borrow().get(&nid).cloned().unwrap_or_else(|| { |
| span_bug!(span, "no type for local variable {}", self.tcx.hir().node_to_string(nid)) |
| }) |
| } |
| |
| #[inline] |
| pub fn write_ty(&self, id: hir::HirId, ty: Ty<'tcx>) { |
| debug!( |
| "write_ty({:?}, {:?}) in fcx {}", |
| id, |
| self.resolve_vars_if_possible(&ty), |
| self.tag() |
| ); |
| self.typeck_results.borrow_mut().node_types_mut().insert(id, ty); |
| |
| if ty.references_error() { |
| self.has_errors.set(true); |
| self.set_tainted_by_errors(); |
| } |
| } |
| |
| pub fn write_field_index(&self, hir_id: hir::HirId, index: usize) { |
| self.typeck_results.borrow_mut().field_indices_mut().insert(hir_id, index); |
| } |
| |
| pub(in super::super) fn write_resolution( |
| &self, |
| hir_id: hir::HirId, |
| r: Result<(DefKind, DefId), ErrorReported>, |
| ) { |
| self.typeck_results.borrow_mut().type_dependent_defs_mut().insert(hir_id, r); |
| } |
| |
| pub fn write_method_call(&self, hir_id: hir::HirId, method: MethodCallee<'tcx>) { |
| debug!("write_method_call(hir_id={:?}, method={:?})", hir_id, method); |
| self.write_resolution(hir_id, Ok((DefKind::AssocFn, method.def_id))); |
| self.write_substs(hir_id, method.substs); |
| |
| // When the method is confirmed, the `method.substs` includes |
| // parameters from not just the method, but also the impl of |
| // the method -- in particular, the `Self` type will be fully |
| // resolved. However, those are not something that the "user |
| // specified" -- i.e., those types come from the inferred type |
| // of the receiver, not something the user wrote. So when we |
| // create the user-substs, we want to replace those earlier |
| // types with just the types that the user actually wrote -- |
| // that is, those that appear on the *method itself*. |
| // |
| // As an example, if the user wrote something like |
| // `foo.bar::<u32>(...)` -- the `Self` type here will be the |
| // type of `foo` (possibly adjusted), but we don't want to |
| // include that. We want just the `[_, u32]` part. |
| if !method.substs.is_noop() { |
| let method_generics = self.tcx.generics_of(method.def_id); |
| if !method_generics.params.is_empty() { |
| let user_type_annotation = self.infcx.probe(|_| { |
| let user_substs = UserSubsts { |
| substs: InternalSubsts::for_item(self.tcx, method.def_id, |param, _| { |
| let i = param.index as usize; |
| if i < method_generics.parent_count { |
| self.infcx.var_for_def(DUMMY_SP, param) |
| } else { |
| method.substs[i] |
| } |
| }), |
| user_self_ty: None, // not relevant here |
| }; |
| |
| self.infcx.canonicalize_user_type_annotation(&UserType::TypeOf( |
| method.def_id, |
| user_substs, |
| )) |
| }); |
| |
| debug!("write_method_call: user_type_annotation={:?}", user_type_annotation); |
| self.write_user_type_annotation(hir_id, user_type_annotation); |
| } |
| } |
| } |
| |
| pub fn write_substs(&self, node_id: hir::HirId, substs: SubstsRef<'tcx>) { |
| if !substs.is_noop() { |
| debug!("write_substs({:?}, {:?}) in fcx {}", node_id, substs, self.tag()); |
| |
| self.typeck_results.borrow_mut().node_substs_mut().insert(node_id, substs); |
| } |
| } |
| |
| /// Given the substs that we just converted from the HIR, try to |
| /// canonicalize them and store them as user-given substitutions |
| /// (i.e., substitutions that must be respected by the NLL check). |
| /// |
| /// This should be invoked **before any unifications have |
| /// occurred**, so that annotations like `Vec<_>` are preserved |
| /// properly. |
| pub fn write_user_type_annotation_from_substs( |
| &self, |
| hir_id: hir::HirId, |
| def_id: DefId, |
| substs: SubstsRef<'tcx>, |
| user_self_ty: Option<UserSelfTy<'tcx>>, |
| ) { |
| debug!( |
| "write_user_type_annotation_from_substs: hir_id={:?} def_id={:?} substs={:?} \ |
| user_self_ty={:?} in fcx {}", |
| hir_id, |
| def_id, |
| substs, |
| user_self_ty, |
| self.tag(), |
| ); |
| |
| if Self::can_contain_user_lifetime_bounds((substs, user_self_ty)) { |
| let canonicalized = self.infcx.canonicalize_user_type_annotation(&UserType::TypeOf( |
| def_id, |
| UserSubsts { substs, user_self_ty }, |
| )); |
| debug!("write_user_type_annotation_from_substs: canonicalized={:?}", canonicalized); |
| self.write_user_type_annotation(hir_id, canonicalized); |
| } |
| } |
| |
| pub fn write_user_type_annotation( |
| &self, |
| hir_id: hir::HirId, |
| canonical_user_type_annotation: CanonicalUserType<'tcx>, |
| ) { |
| debug!( |
| "write_user_type_annotation: hir_id={:?} canonical_user_type_annotation={:?} tag={}", |
| hir_id, |
| canonical_user_type_annotation, |
| self.tag(), |
| ); |
| |
| if !canonical_user_type_annotation.is_identity() { |
| self.typeck_results |
| .borrow_mut() |
| .user_provided_types_mut() |
| .insert(hir_id, canonical_user_type_annotation); |
| } else { |
| debug!("write_user_type_annotation: skipping identity substs"); |
| } |
| } |
| |
| pub fn apply_adjustments(&self, expr: &hir::Expr<'_>, adj: Vec<Adjustment<'tcx>>) { |
| debug!("apply_adjustments(expr={:?}, adj={:?})", expr, adj); |
| |
| if adj.is_empty() { |
| return; |
| } |
| |
| let autoborrow_mut = adj.iter().any(|adj| { |
| matches!(adj, &Adjustment { |
| kind: Adjust::Borrow(AutoBorrow::Ref(_, AutoBorrowMutability::Mut { .. })), |
| .. |
| }) |
| }); |
| |
| match self.typeck_results.borrow_mut().adjustments_mut().entry(expr.hir_id) { |
| Entry::Vacant(entry) => { |
| entry.insert(adj); |
| } |
| Entry::Occupied(mut entry) => { |
| debug!(" - composing on top of {:?}", entry.get()); |
| match (&entry.get()[..], &adj[..]) { |
| // Applying any adjustment on top of a NeverToAny |
| // is a valid NeverToAny adjustment, because it can't |
| // be reached. |
| (&[Adjustment { kind: Adjust::NeverToAny, .. }], _) => return, |
| (&[ |
| Adjustment { kind: Adjust::Deref(_), .. }, |
| Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(..)), .. }, |
| ], &[ |
| Adjustment { kind: Adjust::Deref(_), .. }, |
| .. // Any following adjustments are allowed. |
| ]) => { |
| // A reborrow has no effect before a dereference. |
| } |
| // FIXME: currently we never try to compose autoderefs |
| // and ReifyFnPointer/UnsafeFnPointer, but we could. |
| _ => |
| bug!("while adjusting {:?}, can't compose {:?} and {:?}", |
| expr, entry.get(), adj) |
| }; |
| *entry.get_mut() = adj; |
| } |
| } |
| |
| // If there is an mutable auto-borrow, it is equivalent to `&mut <expr>`. |
| // In this case implicit use of `Deref` and `Index` within `<expr>` should |
| // instead be `DerefMut` and `IndexMut`, so fix those up. |
| if autoborrow_mut { |
| self.convert_place_derefs_to_mutable(expr); |
| } |
| } |
| |
| /// Basically whenever we are converting from a type scheme into |
| /// the fn body space, we always want to normalize associated |
| /// types as well. This function combines the two. |
| fn instantiate_type_scheme<T>(&self, span: Span, substs: SubstsRef<'tcx>, value: &T) -> T |
| where |
| T: TypeFoldable<'tcx>, |
| { |
| let value = value.subst(self.tcx, substs); |
| let result = self.normalize_associated_types_in(span, &value); |
| debug!("instantiate_type_scheme(value={:?}, substs={:?}) = {:?}", value, substs, result); |
| result |
| } |
| |
| /// As `instantiate_type_scheme`, but for the bounds found in a |
| /// generic type scheme. |
| pub(in super::super) fn instantiate_bounds( |
| &self, |
| span: Span, |
| def_id: DefId, |
| substs: SubstsRef<'tcx>, |
| ) -> (ty::InstantiatedPredicates<'tcx>, Vec<Span>) { |
| let bounds = self.tcx.predicates_of(def_id); |
| let spans: Vec<Span> = bounds.predicates.iter().map(|(_, span)| *span).collect(); |
| let result = bounds.instantiate(self.tcx, substs); |
| let result = self.normalize_associated_types_in(span, &result); |
| debug!( |
| "instantiate_bounds(bounds={:?}, substs={:?}) = {:?}, {:?}", |
| bounds, substs, result, spans, |
| ); |
| (result, spans) |
| } |
| |
| /// Replaces the opaque types from the given value with type variables, |
| /// and records the `OpaqueTypeMap` for later use during writeback. See |
| /// `InferCtxt::instantiate_opaque_types` for more details. |
| pub(in super::super) fn instantiate_opaque_types_from_value<T: TypeFoldable<'tcx>>( |
| &self, |
| parent_id: hir::HirId, |
| value: &T, |
| value_span: Span, |
| ) -> T { |
| let parent_def_id = self.tcx.hir().local_def_id(parent_id); |
| debug!( |
| "instantiate_opaque_types_from_value(parent_def_id={:?}, value={:?})", |
| parent_def_id, value |
| ); |
| |
| let (value, opaque_type_map) = |
| self.register_infer_ok_obligations(self.instantiate_opaque_types( |
| parent_def_id, |
| self.body_id, |
| self.param_env, |
| value, |
| value_span, |
| )); |
| |
| let mut opaque_types = self.opaque_types.borrow_mut(); |
| let mut opaque_types_vars = self.opaque_types_vars.borrow_mut(); |
| for (ty, decl) in opaque_type_map { |
| let _ = opaque_types.insert(ty, decl); |
| let _ = opaque_types_vars.insert(decl.concrete_ty, decl.opaque_type); |
| } |
| |
| value |
| } |
| |
| pub(in super::super) fn normalize_associated_types_in<T>(&self, span: Span, value: &T) -> T |
| where |
| T: TypeFoldable<'tcx>, |
| { |
| self.inh.normalize_associated_types_in(span, self.body_id, self.param_env, value) |
| } |
| |
| pub(in super::super) fn normalize_associated_types_in_as_infer_ok<T>( |
| &self, |
| span: Span, |
| value: &T, |
| ) -> InferOk<'tcx, T> |
| where |
| T: TypeFoldable<'tcx>, |
| { |
| self.inh.partially_normalize_associated_types_in(span, self.body_id, self.param_env, value) |
| } |
| |
| pub fn require_type_meets( |
| &self, |
| ty: Ty<'tcx>, |
| span: Span, |
| code: traits::ObligationCauseCode<'tcx>, |
| def_id: DefId, |
| ) { |
| self.register_bound(ty, def_id, traits::ObligationCause::new(span, self.body_id, code)); |
| } |
| |
| pub fn require_type_is_sized( |
| &self, |
| ty: Ty<'tcx>, |
| span: Span, |
| code: traits::ObligationCauseCode<'tcx>, |
| ) { |
| if !ty.references_error() { |
| let lang_item = self.tcx.require_lang_item(LangItem::Sized, None); |
| self.require_type_meets(ty, span, code, lang_item); |
| } |
| } |
| |
| pub fn require_type_is_sized_deferred( |
| &self, |
| ty: Ty<'tcx>, |
| span: Span, |
| code: traits::ObligationCauseCode<'tcx>, |
| ) { |
| if !ty.references_error() { |
| self.deferred_sized_obligations.borrow_mut().push((ty, span, code)); |
| } |
| } |
| |
| pub fn register_bound( |
| &self, |
| ty: Ty<'tcx>, |
| def_id: DefId, |
| cause: traits::ObligationCause<'tcx>, |
| ) { |
| if !ty.references_error() { |
| self.fulfillment_cx.borrow_mut().register_bound( |
| self, |
| self.param_env, |
| ty, |
| def_id, |
| cause, |
| ); |
| } |
| } |
| |
| pub fn to_ty(&self, ast_t: &hir::Ty<'_>) -> Ty<'tcx> { |
| let t = AstConv::ast_ty_to_ty(self, ast_t); |
| self.register_wf_obligation(t.into(), ast_t.span, traits::MiscObligation); |
| t |
| } |
| |
| pub fn to_ty_saving_user_provided_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> { |
| let ty = self.to_ty(ast_ty); |
| debug!("to_ty_saving_user_provided_ty: ty={:?}", ty); |
| |
| if Self::can_contain_user_lifetime_bounds(ty) { |
| let c_ty = self.infcx.canonicalize_response(&UserType::Ty(ty)); |
| debug!("to_ty_saving_user_provided_ty: c_ty={:?}", c_ty); |
| self.typeck_results.borrow_mut().user_provided_types_mut().insert(ast_ty.hir_id, c_ty); |
| } |
| |
| ty |
| } |
| |
| pub fn to_const(&self, ast_c: &hir::AnonConst) -> &'tcx ty::Const<'tcx> { |
| let const_def_id = self.tcx.hir().local_def_id(ast_c.hir_id); |
| let c = ty::Const::from_anon_const(self.tcx, const_def_id); |
| self.register_wf_obligation( |
| c.into(), |
| self.tcx.hir().span(ast_c.hir_id), |
| ObligationCauseCode::MiscObligation, |
| ); |
| c |
| } |
| |
| pub fn const_arg_to_const( |
| &self, |
| ast_c: &hir::AnonConst, |
| param_def_id: DefId, |
| ) -> &'tcx ty::Const<'tcx> { |
| let const_def = ty::WithOptConstParam { |
| did: self.tcx.hir().local_def_id(ast_c.hir_id), |
| const_param_did: Some(param_def_id), |
| }; |
| let c = ty::Const::from_opt_const_arg_anon_const(self.tcx, const_def); |
| self.register_wf_obligation( |
| c.into(), |
| self.tcx.hir().span(ast_c.hir_id), |
| ObligationCauseCode::MiscObligation, |
| ); |
| c |
| } |
| |
| // If the type given by the user has free regions, save it for later, since |
| // NLL would like to enforce those. Also pass in types that involve |
| // projections, since those can resolve to `'static` bounds (modulo #54940, |
| // which hopefully will be fixed by the time you see this comment, dear |
| // reader, although I have my doubts). Also pass in types with inference |
| // types, because they may be repeated. Other sorts of things are already |
| // sufficiently enforced with erased regions. =) |
| fn can_contain_user_lifetime_bounds<T>(t: T) -> bool |
| where |
| T: TypeFoldable<'tcx>, |
| { |
| t.has_free_regions() || t.has_projections() || t.has_infer_types() |
| } |
| |
| pub fn node_ty(&self, id: hir::HirId) -> Ty<'tcx> { |
| match self.typeck_results.borrow().node_types().get(id) { |
| Some(&t) => t, |
| None if self.is_tainted_by_errors() => self.tcx.ty_error(), |
| None => { |
| bug!( |
| "no type for node {}: {} in fcx {}", |
| id, |
| self.tcx.hir().node_to_string(id), |
| self.tag() |
| ); |
| } |
| } |
| } |
| |
| /// Registers an obligation for checking later, during regionck, that `arg` is well-formed. |
| pub fn register_wf_obligation( |
| &self, |
| arg: subst::GenericArg<'tcx>, |
| span: Span, |
| code: traits::ObligationCauseCode<'tcx>, |
| ) { |
| // WF obligations never themselves fail, so no real need to give a detailed cause: |
| let cause = traits::ObligationCause::new(span, self.body_id, code); |
| self.register_predicate(traits::Obligation::new( |
| cause, |
| self.param_env, |
| ty::PredicateAtom::WellFormed(arg).to_predicate(self.tcx), |
| )); |
| } |
| |
| /// Registers obligations that all `substs` are well-formed. |
| pub fn add_wf_bounds(&self, substs: SubstsRef<'tcx>, expr: &hir::Expr<'_>) { |
| for arg in substs.iter().filter(|arg| { |
| matches!(arg.unpack(), GenericArgKind::Type(..) | GenericArgKind::Const(..)) |
| }) { |
| self.register_wf_obligation(arg, expr.span, traits::MiscObligation); |
| } |
| } |
| |
| /// Given a fully substituted set of bounds (`generic_bounds`), and the values with which each |
| /// type/region parameter was instantiated (`substs`), creates and registers suitable |
| /// trait/region obligations. |
| /// |
| /// For example, if there is a function: |
| /// |
| /// ``` |
| /// fn foo<'a,T:'a>(...) |
| /// ``` |
| /// |
| /// and a reference: |
| /// |
| /// ``` |
| /// let f = foo; |
| /// ``` |
| /// |
| /// Then we will create a fresh region variable `'$0` and a fresh type variable `$1` for `'a` |
| /// and `T`. This routine will add a region obligation `$1:'$0` and register it locally. |
| pub fn add_obligations_for_parameters( |
| &self, |
| cause: traits::ObligationCause<'tcx>, |
| predicates: ty::InstantiatedPredicates<'tcx>, |
| ) { |
| assert!(!predicates.has_escaping_bound_vars()); |
| |
| debug!("add_obligations_for_parameters(predicates={:?})", predicates); |
| |
| for obligation in traits::predicates_for_generics(cause, self.param_env, predicates) { |
| self.register_predicate(obligation); |
| } |
| } |
| |
| // FIXME(arielb1): use this instead of field.ty everywhere |
| // Only for fields! Returns <none> for methods> |
| // Indifferent to privacy flags |
| pub fn field_ty( |
| &self, |
| span: Span, |
| field: &'tcx ty::FieldDef, |
| substs: SubstsRef<'tcx>, |
| ) -> Ty<'tcx> { |
| self.normalize_associated_types_in(span, &field.ty(self.tcx, substs)) |
| } |
| |
| pub(in super::super) fn resolve_generator_interiors(&self, def_id: DefId) { |
| let mut generators = self.deferred_generator_interiors.borrow_mut(); |
| for (body_id, interior, kind) in generators.drain(..) { |
| self.select_obligations_where_possible(false, |_| {}); |
| crate::check::generator_interior::resolve_interior( |
| self, def_id, body_id, interior, kind, |
| ); |
| } |
| } |
| |
| // Tries to apply a fallback to `ty` if it is an unsolved variable. |
| // |
| // - Unconstrained ints are replaced with `i32`. |
| // |
| // - Unconstrained floats are replaced with with `f64`. |
| // |
| // - Non-numerics get replaced with `!` when `#![feature(never_type_fallback)]` |
| // is enabled. Otherwise, they are replaced with `()`. |
| // |
| // Fallback becomes very dubious if we have encountered type-checking errors. |
| // In that case, fallback to Error. |
| // The return value indicates whether fallback has occurred. |
| pub(in super::super) fn fallback_if_possible(&self, ty: Ty<'tcx>, mode: FallbackMode) -> bool { |
| use rustc_middle::ty::error::UnconstrainedNumeric::Neither; |
| use rustc_middle::ty::error::UnconstrainedNumeric::{UnconstrainedFloat, UnconstrainedInt}; |
| |
| assert!(ty.is_ty_infer()); |
| let fallback = match self.type_is_unconstrained_numeric(ty) { |
| _ if self.is_tainted_by_errors() => self.tcx().ty_error(), |
| UnconstrainedInt => self.tcx.types.i32, |
| UnconstrainedFloat => self.tcx.types.f64, |
| Neither if self.type_var_diverges(ty) => self.tcx.mk_diverging_default(), |
| Neither => { |
| // This type variable was created from the instantiation of an opaque |
| // type. The fact that we're attempting to perform fallback for it |
| // means that the function neither constrained it to a concrete |
| // type, nor to the opaque type itself. |
| // |
| // For example, in this code: |
| // |
| //``` |
| // type MyType = impl Copy; |
| // fn defining_use() -> MyType { true } |
| // fn other_use() -> MyType { defining_use() } |
| // ``` |
| // |
| // `defining_use` will constrain the instantiated inference |
| // variable to `bool`, while `other_use` will constrain |
| // the instantiated inference variable to `MyType`. |
| // |
| // When we process opaque types during writeback, we |
| // will handle cases like `other_use`, and not count |
| // them as defining usages |
| // |
| // However, we also need to handle cases like this: |
| // |
| // ```rust |
| // pub type Foo = impl Copy; |
| // fn produce() -> Option<Foo> { |
| // None |
| // } |
| // ``` |
| // |
| // In the above snippet, the inference variable created by |
| // instantiating `Option<Foo>` will be completely unconstrained. |
| // We treat this as a non-defining use by making the inference |
| // variable fall back to the opaque type itself. |
| if let FallbackMode::All = mode { |
| if let Some(opaque_ty) = self.opaque_types_vars.borrow().get(ty) { |
| debug!( |
| "fallback_if_possible: falling back opaque type var {:?} to {:?}", |
| ty, opaque_ty |
| ); |
| *opaque_ty |
| } else { |
| return false; |
| } |
| } else { |
| return false; |
| } |
| } |
| }; |
| debug!("fallback_if_possible: defaulting `{:?}` to `{:?}`", ty, fallback); |
| self.demand_eqtype(rustc_span::DUMMY_SP, ty, fallback); |
| true |
| } |
| |
| pub(in super::super) fn select_all_obligations_or_error(&self) { |
| debug!("select_all_obligations_or_error"); |
| if let Err(errors) = self.fulfillment_cx.borrow_mut().select_all_or_error(&self) { |
| self.report_fulfillment_errors(&errors, self.inh.body_id, false); |
| } |
| } |
| |
| /// Select as many obligations as we can at present. |
| pub(in super::super) fn select_obligations_where_possible( |
| &self, |
| fallback_has_occurred: bool, |
| mutate_fullfillment_errors: impl Fn(&mut Vec<traits::FulfillmentError<'tcx>>), |
| ) { |
| let result = self.fulfillment_cx.borrow_mut().select_where_possible(self); |
| if let Err(mut errors) = result { |
| mutate_fullfillment_errors(&mut errors); |
| self.report_fulfillment_errors(&errors, self.inh.body_id, fallback_has_occurred); |
| } |
| } |
| |
| /// For the overloaded place expressions (`*x`, `x[3]`), the trait |
| /// returns a type of `&T`, but the actual type we assign to the |
| /// *expression* is `T`. So this function just peels off the return |
| /// type by one layer to yield `T`. |
| pub(in super::super) fn make_overloaded_place_return_type( |
| &self, |
| method: MethodCallee<'tcx>, |
| ) -> ty::TypeAndMut<'tcx> { |
| // extract method return type, which will be &T; |
| let ret_ty = method.sig.output(); |
| |
| // method returns &T, but the type as visible to user is T, so deref |
| ret_ty.builtin_deref(true).unwrap() |
| } |
| |
| fn self_type_matches_expected_vid( |
| &self, |
| trait_ref: ty::PolyTraitRef<'tcx>, |
| expected_vid: ty::TyVid, |
| ) -> bool { |
| let self_ty = self.shallow_resolve(trait_ref.skip_binder().self_ty()); |
| debug!( |
| "self_type_matches_expected_vid(trait_ref={:?}, self_ty={:?}, expected_vid={:?})", |
| trait_ref, self_ty, expected_vid |
| ); |
| match *self_ty.kind() { |
| ty::Infer(ty::TyVar(found_vid)) => { |
| // FIXME: consider using `sub_root_var` here so we |
| // can see through subtyping. |
| let found_vid = self.root_var(found_vid); |
| debug!("self_type_matches_expected_vid - found_vid={:?}", found_vid); |
| expected_vid == found_vid |
| } |
| _ => false, |
| } |
| } |
| |
| pub(in super::super) fn obligations_for_self_ty<'b>( |
| &'b self, |
| self_ty: ty::TyVid, |
| ) -> impl Iterator<Item = (ty::PolyTraitRef<'tcx>, traits::PredicateObligation<'tcx>)> |
| + Captures<'tcx> |
| + 'b { |
| // FIXME: consider using `sub_root_var` here so we |
| // can see through subtyping. |
| let ty_var_root = self.root_var(self_ty); |
| debug!( |
| "obligations_for_self_ty: self_ty={:?} ty_var_root={:?} pending_obligations={:?}", |
| self_ty, |
| ty_var_root, |
| self.fulfillment_cx.borrow().pending_obligations() |
| ); |
| |
| self.fulfillment_cx |
| .borrow() |
| .pending_obligations() |
| .into_iter() |
| .filter_map(move |obligation| { |
| match obligation.predicate.skip_binders() { |
| ty::PredicateAtom::Projection(data) => { |
| Some((ty::Binder::bind(data).to_poly_trait_ref(self.tcx), obligation)) |
| } |
| ty::PredicateAtom::Trait(data, _) => { |
| Some((ty::Binder::bind(data).to_poly_trait_ref(), obligation)) |
| } |
| ty::PredicateAtom::Subtype(..) => None, |
| ty::PredicateAtom::RegionOutlives(..) => None, |
| ty::PredicateAtom::TypeOutlives(..) => None, |
| ty::PredicateAtom::WellFormed(..) => None, |
| ty::PredicateAtom::ObjectSafe(..) => None, |
| ty::PredicateAtom::ConstEvaluatable(..) => None, |
| ty::PredicateAtom::ConstEquate(..) => None, |
| // N.B., this predicate is created by breaking down a |
| // `ClosureType: FnFoo()` predicate, where |
| // `ClosureType` represents some `Closure`. It can't |
| // possibly be referring to the current closure, |
| // because we haven't produced the `Closure` for |
| // this closure yet; this is exactly why the other |
| // code is looking for a self type of a unresolved |
| // inference variable. |
| ty::PredicateAtom::ClosureKind(..) => None, |
| ty::PredicateAtom::TypeWellFormedFromEnv(..) => None, |
| } |
| }) |
| .filter(move |(tr, _)| self.self_type_matches_expected_vid(*tr, ty_var_root)) |
| } |
| |
| pub(in super::super) fn type_var_is_sized(&self, self_ty: ty::TyVid) -> bool { |
| self.obligations_for_self_ty(self_ty) |
| .any(|(tr, _)| Some(tr.def_id()) == self.tcx.lang_items().sized_trait()) |
| } |
| |
| pub(in super::super) fn err_args(&self, len: usize) -> Vec<Ty<'tcx>> { |
| vec![self.tcx.ty_error(); len] |
| } |
| |
| /// Unifies the output type with the expected type early, for more coercions |
| /// and forward type information on the input expressions. |
| pub(in super::super) fn expected_inputs_for_expected_output( |
| &self, |
| call_span: Span, |
| expected_ret: Expectation<'tcx>, |
| formal_ret: Ty<'tcx>, |
| formal_args: &[Ty<'tcx>], |
| ) -> Vec<Ty<'tcx>> { |
| let formal_ret = self.resolve_vars_with_obligations(formal_ret); |
| let ret_ty = match expected_ret.only_has_type(self) { |
| Some(ret) => ret, |
| None => return Vec::new(), |
| }; |
| let expect_args = self |
| .fudge_inference_if_ok(|| { |
| // Attempt to apply a subtyping relationship between the formal |
| // return type (likely containing type variables if the function |
| // is polymorphic) and the expected return type. |
| // No argument expectations are produced if unification fails. |
| let origin = self.misc(call_span); |
| let ures = self.at(&origin, self.param_env).sup(ret_ty, &formal_ret); |
| |
| // FIXME(#27336) can't use ? here, Try::from_error doesn't default |
| // to identity so the resulting type is not constrained. |
| match ures { |
| Ok(ok) => { |
| // Process any obligations locally as much as |
| // we can. We don't care if some things turn |
| // out unconstrained or ambiguous, as we're |
| // just trying to get hints here. |
| self.save_and_restore_in_snapshot_flag(|_| { |
| let mut fulfill = TraitEngine::new(self.tcx); |
| for obligation in ok.obligations { |
| fulfill.register_predicate_obligation(self, obligation); |
| } |
| fulfill.select_where_possible(self) |
| }) |
| .map_err(|_| ())?; |
| } |
| Err(_) => return Err(()), |
| } |
| |
| // Record all the argument types, with the substitutions |
| // produced from the above subtyping unification. |
| Ok(formal_args.iter().map(|ty| self.resolve_vars_if_possible(ty)).collect()) |
| }) |
| .unwrap_or_default(); |
| debug!( |
| "expected_inputs_for_expected_output(formal={:?} -> {:?}, expected={:?} -> {:?})", |
| formal_args, formal_ret, expect_args, expected_ret |
| ); |
| expect_args |
| } |
| |
| pub(in super::super) fn resolve_lang_item_path( |
| &self, |
| lang_item: hir::LangItem, |
| span: Span, |
| hir_id: hir::HirId, |
| ) -> (Res, Ty<'tcx>) { |
| let def_id = self.tcx.require_lang_item(lang_item, Some(span)); |
| let def_kind = self.tcx.def_kind(def_id); |
| |
| let item_ty = if let DefKind::Variant = def_kind { |
| self.tcx.type_of(self.tcx.parent(def_id).expect("variant w/out parent")) |
| } else { |
| self.tcx.type_of(def_id) |
| }; |
| let substs = self.infcx.fresh_substs_for_item(span, def_id); |
| let ty = item_ty.subst(self.tcx, substs); |
| |
| self.write_resolution(hir_id, Ok((def_kind, def_id))); |
| self.add_required_obligations(span, def_id, &substs); |
| (Res::Def(def_kind, def_id), ty) |
| } |
| |
| /// Resolves an associated value path into a base type and associated constant, or method |
| /// resolution. The newly resolved definition is written into `type_dependent_defs`. |
| pub fn resolve_ty_and_res_ufcs<'b>( |
| &self, |
| qpath: &'b QPath<'b>, |
| hir_id: hir::HirId, |
| span: Span, |
| ) -> (Res, Option<Ty<'tcx>>, &'b [hir::PathSegment<'b>]) { |
| debug!("resolve_ty_and_res_ufcs: qpath={:?} hir_id={:?} span={:?}", qpath, hir_id, span); |
| let (ty, qself, item_segment) = match *qpath { |
| QPath::Resolved(ref opt_qself, ref path) => { |
| return ( |
| path.res, |
| opt_qself.as_ref().map(|qself| self.to_ty(qself)), |
| &path.segments[..], |
| ); |
| } |
| QPath::TypeRelative(ref qself, ref segment) => (self.to_ty(qself), qself, segment), |
| QPath::LangItem(..) => bug!("`resolve_ty_and_res_ufcs` called on `LangItem`"), |
| }; |
| if let Some(&cached_result) = self.typeck_results.borrow().type_dependent_defs().get(hir_id) |
| { |
| // Return directly on cache hit. This is useful to avoid doubly reporting |
| // errors with default match binding modes. See #44614. |
| let def = |
| cached_result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err); |
| return (def, Some(ty), slice::from_ref(&**item_segment)); |
| } |
| let item_name = item_segment.ident; |
| let result = self.resolve_ufcs(span, item_name, ty, hir_id).or_else(|error| { |
| let result = match error { |
| method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)), |
| _ => Err(ErrorReported), |
| }; |
| if item_name.name != kw::Invalid { |
| if let Some(mut e) = self.report_method_error( |
| span, |
| ty, |
| item_name, |
| SelfSource::QPath(qself), |
| error, |
| None, |
| ) { |
| e.emit(); |
| } |
| } |
| result |
| }); |
| |
| // Write back the new resolution. |
| self.write_resolution(hir_id, result); |
| ( |
| result.map(|(kind, def_id)| Res::Def(kind, def_id)).unwrap_or(Res::Err), |
| Some(ty), |
| slice::from_ref(&**item_segment), |
| ) |
| } |
| |
| /// Given a function `Node`, return its `FnDecl` if it exists, or `None` otherwise. |
| pub(in super::super) fn get_node_fn_decl( |
| &self, |
| node: Node<'tcx>, |
| ) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident, bool)> { |
| match node { |
| Node::Item(&hir::Item { ident, kind: hir::ItemKind::Fn(ref sig, ..), .. }) => { |
| // This is less than ideal, it will not suggest a return type span on any |
| // method called `main`, regardless of whether it is actually the entry point, |
| // but it will still present it as the reason for the expected type. |
| Some((&sig.decl, ident, ident.name != sym::main)) |
| } |
| Node::TraitItem(&hir::TraitItem { |
| ident, |
| kind: hir::TraitItemKind::Fn(ref sig, ..), |
| .. |
| }) => Some((&sig.decl, ident, true)), |
| Node::ImplItem(&hir::ImplItem { |
| ident, |
| kind: hir::ImplItemKind::Fn(ref sig, ..), |
| .. |
| }) => Some((&sig.decl, ident, false)), |
| _ => None, |
| } |
| } |
| |
| /// Given a `HirId`, return the `FnDecl` of the method it is enclosed by and whether a |
| /// suggestion can be made, `None` otherwise. |
| pub fn get_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, bool)> { |
| // Get enclosing Fn, if it is a function or a trait method, unless there's a `loop` or |
| // `while` before reaching it, as block tail returns are not available in them. |
| self.tcx.hir().get_return_block(blk_id).and_then(|blk_id| { |
| let parent = self.tcx.hir().get(blk_id); |
| self.get_node_fn_decl(parent).map(|(fn_decl, _, is_main)| (fn_decl, is_main)) |
| }) |
| } |
| |
| pub(in super::super) fn note_internal_mutation_in_method( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| expr: &hir::Expr<'_>, |
| expected: Ty<'tcx>, |
| found: Ty<'tcx>, |
| ) { |
| if found != self.tcx.types.unit { |
| return; |
| } |
| if let ExprKind::MethodCall(path_segment, _, [rcvr, ..], _) = expr.kind { |
| if self |
| .typeck_results |
| .borrow() |
| .expr_ty_adjusted_opt(rcvr) |
| .map_or(true, |ty| expected.peel_refs() != ty.peel_refs()) |
| { |
| return; |
| } |
| let mut sp = MultiSpan::from_span(path_segment.ident.span); |
| sp.push_span_label( |
| path_segment.ident.span, |
| format!( |
| "this call modifies {} in-place", |
| match rcvr.kind { |
| ExprKind::Path(QPath::Resolved( |
| None, |
| hir::Path { segments: [segment], .. }, |
| )) => format!("`{}`", segment.ident), |
| _ => "its receiver".to_string(), |
| } |
| ), |
| ); |
| sp.push_span_label( |
| rcvr.span, |
| "you probably want to use this value after calling the method...".to_string(), |
| ); |
| err.span_note( |
| sp, |
| &format!("method `{}` modifies its receiver in-place", path_segment.ident), |
| ); |
| err.note(&format!("...instead of the `()` output of method `{}`", path_segment.ident)); |
| } |
| } |
| |
| pub(in super::super) fn note_need_for_fn_pointer( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| expected: Ty<'tcx>, |
| found: Ty<'tcx>, |
| ) { |
| let (sig, did, substs) = match (&expected.kind(), &found.kind()) { |
| (ty::FnDef(did1, substs1), ty::FnDef(did2, substs2)) => { |
| let sig1 = self.tcx.fn_sig(*did1).subst(self.tcx, substs1); |
| let sig2 = self.tcx.fn_sig(*did2).subst(self.tcx, substs2); |
| if sig1 != sig2 { |
| return; |
| } |
| err.note( |
| "different `fn` items always have unique types, even if their signatures are \ |
| the same", |
| ); |
| (sig1, *did1, substs1) |
| } |
| (ty::FnDef(did, substs), ty::FnPtr(sig2)) => { |
| let sig1 = self.tcx.fn_sig(*did).subst(self.tcx, substs); |
| if sig1 != *sig2 { |
| return; |
| } |
| (sig1, *did, substs) |
| } |
| _ => return, |
| }; |
| err.help(&format!("change the expected type to be function pointer `{}`", sig)); |
| err.help(&format!( |
| "if the expected type is due to type inference, cast the expected `fn` to a function \ |
| pointer: `{} as {}`", |
| self.tcx.def_path_str_with_substs(did, substs), |
| sig |
| )); |
| } |
| |
| pub(in super::super) fn could_remove_semicolon( |
| &self, |
| blk: &'tcx hir::Block<'tcx>, |
| expected_ty: Ty<'tcx>, |
| ) -> Option<Span> { |
| // Be helpful when the user wrote `{... expr;}` and |
| // taking the `;` off is enough to fix the error. |
| let last_stmt = blk.stmts.last()?; |
| let last_expr = match last_stmt.kind { |
| hir::StmtKind::Semi(ref e) => e, |
| _ => return None, |
| }; |
| let last_expr_ty = self.node_ty(last_expr.hir_id); |
| if matches!(last_expr_ty.kind(), ty::Error(_)) |
| || self.can_sub(self.param_env, last_expr_ty, expected_ty).is_err() |
| { |
| return None; |
| } |
| let original_span = original_sp(last_stmt.span, blk.span); |
| Some(original_span.with_lo(original_span.hi() - BytePos(1))) |
| } |
| |
| // Instantiates the given path, which must refer to an item with the given |
| // number of type parameters and type. |
| pub fn instantiate_value_path( |
| &self, |
| segments: &[hir::PathSegment<'_>], |
| self_ty: Option<Ty<'tcx>>, |
| res: Res, |
| span: Span, |
| hir_id: hir::HirId, |
| ) -> (Ty<'tcx>, Res) { |
| debug!( |
| "instantiate_value_path(segments={:?}, self_ty={:?}, res={:?}, hir_id={})", |
| segments, self_ty, res, hir_id, |
| ); |
| |
| let tcx = self.tcx; |
| |
| let path_segs = match res { |
| Res::Local(_) | Res::SelfCtor(_) => vec![], |
| Res::Def(kind, def_id) => { |
| AstConv::def_ids_for_value_path_segments(self, segments, self_ty, kind, def_id) |
| } |
| _ => bug!("instantiate_value_path on {:?}", res), |
| }; |
| |
| let mut user_self_ty = None; |
| let mut is_alias_variant_ctor = false; |
| match res { |
| Res::Def(DefKind::Ctor(CtorOf::Variant, _), _) => { |
| if let Some(self_ty) = self_ty { |
| let adt_def = self_ty.ty_adt_def().unwrap(); |
| user_self_ty = Some(UserSelfTy { impl_def_id: adt_def.did, self_ty }); |
| is_alias_variant_ctor = true; |
| } |
| } |
| Res::Def(DefKind::AssocFn | DefKind::AssocConst, def_id) => { |
| let container = tcx.associated_item(def_id).container; |
| debug!("instantiate_value_path: def_id={:?} container={:?}", def_id, container); |
| match container { |
| ty::TraitContainer(trait_did) => { |
| callee::check_legal_trait_for_method_call(tcx, span, None, trait_did) |
| } |
| ty::ImplContainer(impl_def_id) => { |
| if segments.len() == 1 { |
| // `<T>::assoc` will end up here, and so |
| // can `T::assoc`. It this came from an |
| // inherent impl, we need to record the |
| // `T` for posterity (see `UserSelfTy` for |
| // details). |
| let self_ty = self_ty.expect("UFCS sugared assoc missing Self"); |
| user_self_ty = Some(UserSelfTy { impl_def_id, self_ty }); |
| } |
| } |
| } |
| } |
| _ => {} |
| } |
| |
| // Now that we have categorized what space the parameters for each |
| // segment belong to, let's sort out the parameters that the user |
| // provided (if any) into their appropriate spaces. We'll also report |
| // errors if type parameters are provided in an inappropriate place. |
| |
| let generic_segs: FxHashSet<_> = path_segs.iter().map(|PathSeg(_, index)| index).collect(); |
| let generics_has_err = AstConv::prohibit_generics( |
| self, |
| segments.iter().enumerate().filter_map(|(index, seg)| { |
| if !generic_segs.contains(&index) || is_alias_variant_ctor { |
| Some(seg) |
| } else { |
| None |
| } |
| }), |
| ); |
| |
| if let Res::Local(hid) = res { |
| let ty = self.local_ty(span, hid).decl_ty; |
| let ty = self.normalize_associated_types_in(span, &ty); |
| self.write_ty(hir_id, ty); |
| return (ty, res); |
| } |
| |
| if generics_has_err { |
| // Don't try to infer type parameters when prohibited generic arguments were given. |
| user_self_ty = None; |
| } |
| |
| // Now we have to compare the types that the user *actually* |
| // provided against the types that were *expected*. If the user |
| // did not provide any types, then we want to substitute inference |
| // variables. If the user provided some types, we may still need |
| // to add defaults. If the user provided *too many* types, that's |
| // a problem. |
| |
| let mut infer_args_for_err = FxHashSet::default(); |
| for &PathSeg(def_id, index) in &path_segs { |
| let seg = &segments[index]; |
| let generics = tcx.generics_of(def_id); |
| // Argument-position `impl Trait` is treated as a normal generic |
| // parameter internally, but we don't allow users to specify the |
| // parameter's value explicitly, so we have to do some error- |
| // checking here. |
| if let GenericArgCountResult { |
| correct: Err(GenericArgCountMismatch { reported: Some(ErrorReported), .. }), |
| .. |
| } = AstConv::check_generic_arg_count_for_call( |
| tcx, span, &generics, &seg, false, // `is_method_call` |
| ) { |
| infer_args_for_err.insert(index); |
| self.set_tainted_by_errors(); // See issue #53251. |
| } |
| } |
| |
| let has_self = path_segs |
| .last() |
| .map(|PathSeg(def_id, _)| tcx.generics_of(*def_id).has_self) |
| .unwrap_or(false); |
| |
| let (res, self_ctor_substs) = if let Res::SelfCtor(impl_def_id) = res { |
| let ty = self.normalize_ty(span, tcx.at(span).type_of(impl_def_id)); |
| match *ty.kind() { |
| ty::Adt(adt_def, substs) if adt_def.has_ctor() => { |
| let variant = adt_def.non_enum_variant(); |
| let ctor_def_id = variant.ctor_def_id.unwrap(); |
| ( |
| Res::Def(DefKind::Ctor(CtorOf::Struct, variant.ctor_kind), ctor_def_id), |
| Some(substs), |
| ) |
| } |
| _ => { |
| let mut err = tcx.sess.struct_span_err( |
| span, |
| "the `Self` constructor can only be used with tuple or unit structs", |
| ); |
| if let Some(adt_def) = ty.ty_adt_def() { |
| match adt_def.adt_kind() { |
| AdtKind::Enum => { |
| err.help("did you mean to use one of the enum's variants?"); |
| } |
| AdtKind::Struct | AdtKind::Union => { |
| err.span_suggestion( |
| span, |
| "use curly brackets", |
| String::from("Self { /* fields */ }"), |
| Applicability::HasPlaceholders, |
| ); |
| } |
| } |
| } |
| err.emit(); |
| |
| return (tcx.ty_error(), res); |
| } |
| } |
| } else { |
| (res, None) |
| }; |
| let def_id = res.def_id(); |
| |
| // The things we are substituting into the type should not contain |
| // escaping late-bound regions, and nor should the base type scheme. |
| let ty = tcx.type_of(def_id); |
| |
| let arg_count = GenericArgCountResult { |
| explicit_late_bound: ExplicitLateBound::No, |
| correct: if infer_args_for_err.is_empty() { |
| Ok(()) |
| } else { |
| Err(GenericArgCountMismatch::default()) |
| }, |
| }; |
| |
| let substs = self_ctor_substs.unwrap_or_else(|| { |
| AstConv::create_substs_for_generic_args( |
| tcx, |
| def_id, |
| &[][..], |
| has_self, |
| self_ty, |
| arg_count, |
| // Provide the generic args, and whether types should be inferred. |
| |def_id| { |
| if let Some(&PathSeg(_, index)) = |
| path_segs.iter().find(|&PathSeg(did, _)| *did == def_id) |
| { |
| // If we've encountered an `impl Trait`-related error, we're just |
| // going to infer the arguments for better error messages. |
| if !infer_args_for_err.contains(&index) { |
| // Check whether the user has provided generic arguments. |
| if let Some(ref data) = segments[index].args { |
| return (Some(data), segments[index].infer_args); |
| } |
| } |
| return (None, segments[index].infer_args); |
| } |
| |
| (None, true) |
| }, |
| // Provide substitutions for parameters for which (valid) arguments have been provided. |
| |param, arg| match (¶m.kind, arg) { |
| (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => { |
| AstConv::ast_region_to_region(self, lt, Some(param)).into() |
| } |
| (GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => { |
| self.to_ty(ty).into() |
| } |
| (GenericParamDefKind::Const, GenericArg::Const(ct)) => { |
| self.const_arg_to_const(&ct.value, param.def_id).into() |
| } |
| _ => unreachable!(), |
| }, |
| // Provide substitutions for parameters for which arguments are inferred. |
| |substs, param, infer_args| { |
| match param.kind { |
| GenericParamDefKind::Lifetime => { |
| self.re_infer(Some(param), span).unwrap().into() |
| } |
| GenericParamDefKind::Type { has_default, .. } => { |
| if !infer_args && has_default { |
| // If we have a default, then we it doesn't matter that we're not |
| // inferring the type arguments: we provide the default where any |
| // is missing. |
| let default = tcx.type_of(param.def_id); |
| self.normalize_ty( |
| span, |
| default.subst_spanned(tcx, substs.unwrap(), Some(span)), |
| ) |
| .into() |
| } else { |
| // If no type arguments were provided, we have to infer them. |
| // This case also occurs as a result of some malformed input, e.g. |
| // a lifetime argument being given instead of a type parameter. |
| // Using inference instead of `Error` gives better error messages. |
| self.var_for_def(span, param) |
| } |
| } |
| GenericParamDefKind::Const => { |
| // FIXME(const_generics:defaults) |
| // No const parameters were provided, we have to infer them. |
| self.var_for_def(span, param) |
| } |
| } |
| }, |
| ) |
| }); |
| assert!(!substs.has_escaping_bound_vars()); |
| assert!(!ty.has_escaping_bound_vars()); |
| |
| // First, store the "user substs" for later. |
| self.write_user_type_annotation_from_substs(hir_id, def_id, substs, user_self_ty); |
| |
| self.add_required_obligations(span, def_id, &substs); |
| |
| // Substitute the values for the type parameters into the type of |
| // the referenced item. |
| let ty_substituted = self.instantiate_type_scheme(span, &substs, &ty); |
| |
| if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty { |
| // In the case of `Foo<T>::method` and `<Foo<T>>::method`, if `method` |
| // is inherent, there is no `Self` parameter; instead, the impl needs |
| // type parameters, which we can infer by unifying the provided `Self` |
| // with the substituted impl type. |
| // This also occurs for an enum variant on a type alias. |
| let ty = tcx.type_of(impl_def_id); |
| |
| let impl_ty = self.instantiate_type_scheme(span, &substs, &ty); |
| match self.at(&self.misc(span), self.param_env).sup(impl_ty, self_ty) { |
| Ok(ok) => self.register_infer_ok_obligations(ok), |
| Err(_) => { |
| self.tcx.sess.delay_span_bug( |
| span, |
| &format!( |
| "instantiate_value_path: (UFCS) {:?} was a subtype of {:?} but now is not?", |
| self_ty, |
| impl_ty, |
| ), |
| ); |
| } |
| } |
| } |
| |
| self.check_rustc_args_require_const(def_id, hir_id, span); |
| |
| debug!("instantiate_value_path: type of {:?} is {:?}", hir_id, ty_substituted); |
| self.write_substs(hir_id, substs); |
| |
| (ty_substituted, res) |
| } |
| |
| /// Add all the obligations that are required, substituting and normalized appropriately. |
| fn add_required_obligations(&self, span: Span, def_id: DefId, substs: &SubstsRef<'tcx>) { |
| let (bounds, spans) = self.instantiate_bounds(span, def_id, &substs); |
| |
| for (i, mut obligation) in traits::predicates_for_generics( |
| traits::ObligationCause::new(span, self.body_id, traits::ItemObligation(def_id)), |
| self.param_env, |
| bounds, |
| ) |
| .enumerate() |
| { |
| // This makes the error point at the bound, but we want to point at the argument |
| if let Some(span) = spans.get(i) { |
| obligation.cause.make_mut().code = traits::BindingObligation(def_id, *span); |
| } |
| self.register_predicate(obligation); |
| } |
| } |
| |
| /// Resolves `typ` by a single level if `typ` is a type variable. |
| /// If no resolution is possible, then an error is reported. |
| /// Numeric inference variables may be left unresolved. |
| pub fn structurally_resolved_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> { |
| let ty = self.resolve_vars_with_obligations(ty); |
| if !ty.is_ty_var() { |
| ty |
| } else { |
| if !self.is_tainted_by_errors() { |
| self.emit_inference_failure_err((**self).body_id, sp, ty.into(), E0282) |
| .note("type must be known at this point") |
| .emit(); |
| } |
| let err = self.tcx.ty_error(); |
| self.demand_suptype(sp, err, ty); |
| err |
| } |
| } |
| |
| pub(in super::super) fn with_breakable_ctxt<F: FnOnce() -> R, R>( |
| &self, |
| id: hir::HirId, |
| ctxt: BreakableCtxt<'tcx>, |
| f: F, |
| ) -> (BreakableCtxt<'tcx>, R) { |
| let index; |
| { |
| let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); |
| index = enclosing_breakables.stack.len(); |
| enclosing_breakables.by_id.insert(id, index); |
| enclosing_breakables.stack.push(ctxt); |
| } |
| let result = f(); |
| let ctxt = { |
| let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); |
| debug_assert!(enclosing_breakables.stack.len() == index + 1); |
| enclosing_breakables.by_id.remove(&id).expect("missing breakable context"); |
| enclosing_breakables.stack.pop().expect("missing breakable context") |
| }; |
| (ctxt, result) |
| } |
| |
| /// Instantiate a QueryResponse in a probe context, without a |
| /// good ObligationCause. |
| pub(in super::super) fn probe_instantiate_query_response( |
| &self, |
| span: Span, |
| original_values: &OriginalQueryValues<'tcx>, |
| query_result: &Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>, |
| ) -> InferResult<'tcx, Ty<'tcx>> { |
| self.instantiate_query_response_and_region_obligations( |
| &traits::ObligationCause::misc(span, self.body_id), |
| self.param_env, |
| original_values, |
| query_result, |
| ) |
| } |
| |
| /// Returns `true` if an expression is contained inside the LHS of an assignment expression. |
| pub(in super::super) fn expr_in_place(&self, mut expr_id: hir::HirId) -> bool { |
| let mut contained_in_place = false; |
| |
| while let hir::Node::Expr(parent_expr) = |
| self.tcx.hir().get(self.tcx.hir().get_parent_node(expr_id)) |
| { |
| match &parent_expr.kind { |
| hir::ExprKind::Assign(lhs, ..) | hir::ExprKind::AssignOp(_, lhs, ..) => { |
| if lhs.hir_id == expr_id { |
| contained_in_place = true; |
| break; |
| } |
| } |
| _ => (), |
| } |
| expr_id = parent_expr.hir_id; |
| } |
| |
| contained_in_place |
| } |
| } |
