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Diffstat (limited to '')
-rw-r--r-- | compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs | 1510 |
1 files changed, 1510 insertions, 0 deletions
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs new file mode 100644 index 000000000..3a8093345 --- /dev/null +++ b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs @@ -0,0 +1,1510 @@ +use crate::astconv::{ + AstConv, CreateSubstsForGenericArgsCtxt, ExplicitLateBound, GenericArgCountMismatch, + GenericArgCountResult, IsMethodCall, PathSeg, +}; +use crate::check::callee::{self, DeferredCallResolution}; +use crate::check::method::{self, MethodCallee, SelfSource}; +use crate::check::rvalue_scopes; +use crate::check::{BreakableCtxt, Diverges, Expectation, FnCtxt, LocalTy}; + +use rustc_data_structures::captures::Captures; +use rustc_data_structures::fx::FxHashSet; +use rustc_errors::{Applicability, Diagnostic, ErrorGuaranteed, MultiSpan}; +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::visit::TypeVisitable; +use rustc_middle::ty::{ + self, AdtKind, CanonicalUserType, DefIdTree, EarlyBinder, GenericParamDefKind, ToPolyTraitRef, + ToPredicate, Ty, UserType, +}; +use rustc_session::lint; +use rustc_span::def_id::LocalDefId; +use rustc_span::hygiene::DesugaringKind; +use rustc_span::symbol::{kw, sym, Ident}; +use rustc_span::{Span, DUMMY_SP}; +use rustc_trait_selection::infer::InferCtxtExt as _; +use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _; +use rustc_trait_selection::traits::{ + self, ObligationCause, 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, ty: Ty<'tcx>) -> Ty<'tcx> { + self.resolve_vars_with_obligations_and_mutate_fulfillment(ty, |_| {}) + } + + #[instrument(skip(self, mutate_fulfillment_errors), level = "debug")] + pub(in super::super) fn resolve_vars_with_obligations_and_mutate_fulfillment( + &self, + mut ty: Ty<'tcx>, + mutate_fulfillment_errors: impl Fn(&mut Vec<traits::FulfillmentError<'tcx>>), + ) -> Ty<'tcx> { + // No Infer()? Nothing needs doing. + if !ty.has_infer_types_or_consts() { + debug!("no inference var, nothing needs doing"); + 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!(?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, mutate_fulfillment_errors); + ty = self.resolve_vars_if_possible(ty); + + debug!(?ty); + ty + } + + pub(in super::super) fn record_deferred_call_resolution( + &self, + closure_def_id: LocalDefId, + 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: LocalDefId, + ) -> Vec<DeferredCallResolution<'tcx>> { + let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut(); + deferred_call_resolutions.remove(&closure_def_id).unwrap_or_default() + } + + 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); + } + + #[instrument(level = "debug", skip(self))] + pub(in super::super) fn write_resolution( + &self, + hir_id: hir::HirId, + r: Result<(DefKind, DefId), ErrorGuaranteed>, + ) { + self.typeck_results.borrow_mut().type_dependent_defs_mut().insert(hir_id, r); + } + + #[instrument(level = "debug", skip(self))] + pub fn write_method_call(&self, hir_id: hir::HirId, method: MethodCallee<'tcx>) { + 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_empty() { + let method_generics = self.tcx.generics_of(method.def_id); + if !method_generics.params.is_empty() { + let user_type_annotation = self.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.var_for_def(DUMMY_SP, param) + } else { + method.substs[i] + } + }), + user_self_ty: None, // not relevant here + }; + + self.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_empty() { + 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. + #[instrument(skip(self), level = "debug")] + 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!("fcx {}", self.tag()); + + if Self::can_contain_user_lifetime_bounds((substs, user_self_ty)) { + let canonicalized = self.canonicalize_user_type_annotation(UserType::TypeOf( + def_id, + UserSubsts { substs, user_self_ty }, + )); + debug!(?canonicalized); + self.write_user_type_annotation(hir_id, canonicalized); + } + } + + #[instrument(skip(self), level = "debug")] + pub fn write_user_type_annotation( + &self, + hir_id: hir::HirId, + canonical_user_type_annotation: CanonicalUserType<'tcx>, + ) { + debug!("fcx {}", 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!("skipping identity substs"); + } + } + + #[instrument(skip(self, expr), level = "debug")] + pub fn apply_adjustments(&self, expr: &hir::Expr<'_>, adj: Vec<Adjustment<'tcx>>) { + debug!("expr = {:#?}", expr); + + if adj.is_empty() { + return; + } + + for a in &adj { + if let Adjust::NeverToAny = a.kind { + if a.target.is_ty_var() { + self.diverging_type_vars.borrow_mut().insert(a.target); + debug!("apply_adjustments: adding `{:?}` as diverging type var", a.target); + } + } + } + + 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. + _ => { + self.tcx.sess.delay_span_bug( + expr.span, + &format!( + "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>, + { + debug!("instantiate_type_scheme(value={:?}, substs={:?})", value, substs); + let value = EarlyBinder(value).subst(self.tcx, substs); + let result = self.normalize_associated_types_in(span, value); + debug!("instantiate_type_scheme = {:?}", 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) + } + + 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( + ObligationCause::misc(span, self.body_id), + self.param_env, + value, + ) + } + + pub(in super::super) fn normalize_op_associated_types_in_as_infer_ok<T>( + &self, + span: Span, + value: T, + opt_input_expr: Option<&hir::Expr<'_>>, + ) -> InferOk<'tcx, T> + where + T: TypeFoldable<'tcx>, + { + self.inh.partially_normalize_associated_types_in( + ObligationCause::new( + span, + self.body_id, + traits::BinOp { + rhs_span: opt_input_expr.map(|expr| expr.span), + is_lit: opt_input_expr + .map_or(false, |expr| matches!(expr.kind, ExprKind::Lit(_))), + output_pred: None, + }, + ), + 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 = <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_t); + self.register_wf_obligation(t.into(), ast_t.span, traits::WellFormed(None)); + 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.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 array_length_to_const(&self, length: &hir::ArrayLen) -> ty::Const<'tcx> { + match length { + &hir::ArrayLen::Infer(_, span) => self.ct_infer(self.tcx.types.usize, None, span), + hir::ArrayLen::Body(anon_const) => self.to_const(anon_const), + } + } + + pub fn to_const(&self, ast_c: &hir::AnonConst) -> 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::WellFormed(None), + ); + c + } + + pub fn const_arg_to_const( + &self, + ast_c: &hir::AnonConst, + param_def_id: DefId, + ) -> 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::WellFormed(None), + ); + 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: TypeVisitable<'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() + ); + } + } + } + + pub fn node_ty_opt(&self, id: hir::HirId) -> Option<Ty<'tcx>> { + match self.typeck_results.borrow().node_types().get(id) { + Some(&t) => Some(t), + None if self.is_tainted_by_errors() => Some(self.tcx.ty_error()), + None => None, + } + } + + /// 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::Binder::dummy(ty::PredicateKind::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::WellFormed(None)); + } + } + + // 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_rvalue_scopes(&self, def_id: DefId) { + let scope_tree = self.tcx.region_scope_tree(def_id); + let rvalue_scopes = { rvalue_scopes::resolve_rvalue_scopes(self, &scope_tree, def_id) }; + let mut typeck_results = self.inh.typeck_results.borrow_mut(); + typeck_results.rvalue_scopes = rvalue_scopes; + } + + 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, + ); + } + } + + #[instrument(skip(self), level = "debug")] + pub(in super::super) fn select_all_obligations_or_error(&self) { + let errors = self.fulfillment_cx.borrow_mut().select_all_or_error(&self); + + if !errors.is_empty() { + 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_fulfillment_errors: impl Fn(&mut Vec<traits::FulfillmentError<'tcx>>), + ) { + let mut result = self.fulfillment_cx.borrow_mut().select_where_possible(self); + if !result.is_empty() { + mutate_fulfillment_errors(&mut result); + self.report_fulfillment_errors(&result, 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() + } + + #[instrument(skip(self), level = "debug")] + 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_ty); + + 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, + } + } + + #[instrument(skip(self), level = "debug")] + 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); + trace!("pending_obligations = {:#?}", self.fulfillment_cx.borrow().pending_obligations()); + + self.fulfillment_cx + .borrow() + .pending_obligations() + .into_iter() + .filter_map(move |obligation| { + let bound_predicate = obligation.predicate.kind(); + match bound_predicate.skip_binder() { + ty::PredicateKind::Projection(data) => Some(( + bound_predicate.rebind(data).required_poly_trait_ref(self.tcx), + obligation, + )), + ty::PredicateKind::Trait(data) => { + Some((bound_predicate.rebind(data).to_poly_trait_ref(), obligation)) + } + ty::PredicateKind::Subtype(..) => None, + ty::PredicateKind::Coerce(..) => None, + ty::PredicateKind::RegionOutlives(..) => None, + ty::PredicateKind::TypeOutlives(..) => None, + ty::PredicateKind::WellFormed(..) => None, + ty::PredicateKind::ObjectSafe(..) => None, + ty::PredicateKind::ConstEvaluatable(..) => None, + ty::PredicateKind::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 an unresolved + // inference variable. + ty::PredicateKind::ClosureKind(..) => None, + ty::PredicateKind::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. + #[instrument(skip(self, call_span), level = "debug")] + 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>], + ) -> Option<Vec<Ty<'tcx>>> { + let formal_ret = self.resolve_vars_with_obligations(formal_ret); + let ret_ty = expected_ret.only_has_type(self)?; + + // HACK(oli-obk): This is a hack to keep RPIT and TAIT in sync wrt their behaviour. + // Without it, the inference + // variable will get instantiated with the opaque type. The inference variable often + // has various helpful obligations registered for it that help closures figure out their + // signature. If we infer the inference var to the opaque type, the closure won't be able + // to find those obligations anymore, and it can't necessarily find them from the opaque + // type itself. We could be more powerful with inference if we *combined* the obligations + // so that we got both the obligations from the opaque type and the ones from the inference + // variable. That will accept more code than we do right now, so we need to carefully consider + // the implications. + // Note: this check is pessimistic, as the inference type could be matched with something other + // than the opaque type, but then we need a new `TypeRelation` just for this specific case and + // can't re-use `sup` below. + // See src/test/ui/impl-trait/hidden-type-is-opaque.rs and + // src/test/ui/impl-trait/hidden-type-is-opaque-2.rs for examples that hit this path. + if formal_ret.has_infer_types() { + for ty in ret_ty.walk() { + if let ty::subst::GenericArgKind::Type(ty) = ty.unpack() + && let ty::Opaque(def_id, _) = *ty.kind() + && let Some(def_id) = def_id.as_local() + && self.opaque_type_origin(def_id, DUMMY_SP).is_some() { + return None; + } + } + } + + 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. + let errors = self.save_and_restore_in_snapshot_flag(|_| { + let mut fulfill = <dyn TraitEngine<'_>>::new(self.tcx); + for obligation in ok.obligations { + fulfill.register_predicate_obligation(self, obligation); + } + fulfill.select_where_possible(self) + }); + + if !errors.is_empty() { + return Err(()); + } + } + Err(_) => return Err(()), + } + + // Record all the argument types, with the substitutions + // produced from the above subtyping unification. + Ok(Some(formal_args.iter().map(|&ty| self.resolve_vars_if_possible(ty)).collect())) + }) + .unwrap_or_default(); + debug!(?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, + expr_hir_id: Option<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.bound_type_of(self.tcx.parent(def_id)) + } else { + self.tcx.bound_type_of(def_id) + }; + let substs = self.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_with_code( + span, + def_id, + &substs, + match lang_item { + hir::LangItem::IntoFutureIntoFuture => { + ObligationCauseCode::AwaitableExpr(expr_hir_id) + } + hir::LangItem::IteratorNext | hir::LangItem::IntoIterIntoIter => { + ObligationCauseCode::ForLoopIterator + } + hir::LangItem::TryTraitFromOutput + | hir::LangItem::TryTraitFromResidual + | hir::LangItem::TryTraitBranch => ObligationCauseCode::QuestionMark, + _ => traits::ItemObligation(def_id), + }, + ); + (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_fully_qualified_call( + &self, + qpath: &'tcx QPath<'tcx>, + hir_id: hir::HirId, + span: Span, + ) -> (Res, Option<Ty<'tcx>>, &'tcx [hir::PathSegment<'tcx>]) { + debug!( + "resolve_ty_and_res_fully_qualified_call: 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) => { + // Don't use `self.to_ty`, since this will register a WF obligation. + // If we're trying to call a non-existent method on a trait + // (e.g. `MyTrait::missing_method`), then resolution will + // give us a `QPath::TypeRelative` with a trait object as + // `qself`. In that case, we want to avoid registering a WF obligation + // for `dyn MyTrait`, since we don't actually need the trait + // to be object-safe. + // We manually call `register_wf_obligation` in the success path + // below. + (<dyn AstConv<'_>>::ast_ty_to_ty_in_path(self, qself), qself, segment) + } + QPath::LangItem(..) => { + bug!("`resolve_ty_and_res_fully_qualified_call` called on `LangItem`") + } + }; + if let Some(&cached_result) = self.typeck_results.borrow().type_dependent_defs().get(hir_id) + { + self.register_wf_obligation(ty.into(), qself.span, traits::WellFormed(None)); + // 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_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)); + return (def, Some(ty), slice::from_ref(&**item_segment)); + } + let item_name = item_segment.ident; + let result = self + .resolve_fully_qualified_call(span, item_name, ty, qself.span, hir_id) + .or_else(|error| { + let result = match error { + method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)), + _ => Err(ErrorGuaranteed::unchecked_claim_error_was_emitted()), + }; + + // If we have a path like `MyTrait::missing_method`, then don't register + // a WF obligation for `dyn MyTrait` when method lookup fails. Otherwise, + // register a WF obligation so that we can detect any additional + // errors in the self type. + if !(matches!(error, method::MethodError::NoMatch(_)) && ty.is_trait()) { + self.register_wf_obligation(ty.into(), qself.span, traits::WellFormed(None)); + } + if item_name.name != kw::Empty { + if let Some(mut e) = self.report_method_error( + span, + ty, + item_name, + SelfSource::QPath(qself), + error, + None, + ) { + e.emit(); + } + } + result + }); + + if result.is_ok() { + self.register_wf_obligation(ty.into(), qself.span, traits::WellFormed(None)); + } + + // Write back the new resolution. + self.write_resolution(hir_id, result); + ( + result.map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)), + 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 Diagnostic, + 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...", + ); + 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 Diagnostic, + 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.bound_fn_sig(*did1).subst(self.tcx, substs1); + let sig2 = self.tcx.bound_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.bound_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 + )); + } + + // Instantiates the given path, which must refer to an item with the given + // number of type parameters and type. + #[instrument(skip(self, span), level = "debug")] + 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) { + let tcx = self.tcx; + + let path_segs = match res { + Res::Local(_) | Res::SelfCtor(_) => vec![], + Res::Def(kind, def_id) => <dyn 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 assoc_item = tcx.associated_item(def_id); + let container = assoc_item.container; + let container_id = assoc_item.container_id(tcx); + debug!(?def_id, ?container, ?container_id); + match container { + ty::TraitContainer => { + callee::check_legal_trait_for_method_call(tcx, span, None, span, container_id) + } + ty::ImplContainer => { + 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: container_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 = <dyn 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(); + + let mut explicit_late_bound = ExplicitLateBound::No; + 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. + let arg_count = <dyn AstConv<'_>>::check_generic_arg_count_for_call( + tcx, + span, + def_id, + &generics, + seg, + IsMethodCall::No, + ); + + if let ExplicitLateBound::Yes = arg_count.explicit_late_bound { + explicit_late_bound = ExplicitLateBound::Yes; + } + + if let Err(GenericArgCountMismatch { reported: Some(_), .. }) = arg_count.correct { + 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", + "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, + correct: if infer_args_for_err.is_empty() { + Ok(()) + } else { + Err(GenericArgCountMismatch::default()) + }, + }; + + struct CreateCtorSubstsContext<'a, 'tcx> { + fcx: &'a FnCtxt<'a, 'tcx>, + span: Span, + path_segs: &'a [PathSeg], + infer_args_for_err: &'a FxHashSet<usize>, + segments: &'a [hir::PathSegment<'a>], + } + impl<'tcx, 'a> CreateSubstsForGenericArgsCtxt<'a, 'tcx> for CreateCtorSubstsContext<'a, 'tcx> { + fn args_for_def_id( + &mut self, + def_id: DefId, + ) -> (Option<&'a hir::GenericArgs<'a>>, bool) { + if let Some(&PathSeg(_, index)) = + self.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 !self.infer_args_for_err.contains(&index) { + // Check whether the user has provided generic arguments. + if let Some(ref data) = self.segments[index].args { + return (Some(data), self.segments[index].infer_args); + } + } + return (None, self.segments[index].infer_args); + } + + (None, true) + } + + fn provided_kind( + &mut self, + param: &ty::GenericParamDef, + arg: &GenericArg<'_>, + ) -> subst::GenericArg<'tcx> { + match (¶m.kind, arg) { + (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => { + <dyn AstConv<'_>>::ast_region_to_region(self.fcx, lt, Some(param)).into() + } + (GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => { + self.fcx.to_ty(ty).into() + } + (GenericParamDefKind::Const { .. }, GenericArg::Const(ct)) => { + self.fcx.const_arg_to_const(&ct.value, param.def_id).into() + } + (GenericParamDefKind::Type { .. }, GenericArg::Infer(inf)) => { + self.fcx.ty_infer(Some(param), inf.span).into() + } + (GenericParamDefKind::Const { .. }, GenericArg::Infer(inf)) => { + let tcx = self.fcx.tcx(); + self.fcx.ct_infer(tcx.type_of(param.def_id), Some(param), inf.span).into() + } + _ => unreachable!(), + } + } + + fn inferred_kind( + &mut self, + substs: Option<&[subst::GenericArg<'tcx>]>, + param: &ty::GenericParamDef, + infer_args: bool, + ) -> subst::GenericArg<'tcx> { + let tcx = self.fcx.tcx(); + match param.kind { + GenericParamDefKind::Lifetime => { + self.fcx.re_infer(Some(param), self.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.bound_type_of(param.def_id); + self.fcx + .normalize_ty(self.span, default.subst(tcx, substs.unwrap())) + .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.fcx.var_for_def(self.span, param) + } + } + GenericParamDefKind::Const { has_default } => { + if !infer_args && has_default { + tcx.bound_const_param_default(param.def_id) + .subst(tcx, substs.unwrap()) + .into() + } else { + self.fcx.var_for_def(self.span, param) + } + } + } + } + } + + let substs = self_ctor_substs.unwrap_or_else(|| { + <dyn AstConv<'_>>::create_substs_for_generic_args( + tcx, + def_id, + &[], + has_self, + self_ty, + &arg_count, + &mut CreateCtorSubstsContext { + fcx: self, + span, + path_segs: &path_segs, + infer_args_for_err: &infer_args_for_err, + segments, + }, + ) + }); + 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).eq(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, + ), + ); + } + } + } + + 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. + pub(crate) fn add_required_obligations( + &self, + span: Span, + def_id: DefId, + substs: &SubstsRef<'tcx>, + ) { + self.add_required_obligations_with_code( + span, + def_id, + substs, + traits::ItemObligation(def_id), + ) + } + + #[tracing::instrument(level = "debug", skip(self, span, def_id, substs))] + fn add_required_obligations_with_code( + &self, + span: Span, + def_id: DefId, + substs: &SubstsRef<'tcx>, + code: ObligationCauseCode<'tcx>, + ) { + let (bounds, _) = self.instantiate_bounds(span, def_id, &substs); + + for obligation in traits::predicates_for_generics( + traits::ObligationCause::new(span, self.body_id, code), + self.param_env, + bounds, + ) { + 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, true) + .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 + } +} |