#![deny(rustc::untranslatable_diagnostic)] #![deny(rustc::diagnostic_outside_of_impl)] //! This pass type-checks the MIR to ensure it is not broken. use std::rc::Rc; use std::{fmt, iter, mem}; use either::Either; use hir::OpaqueTyOrigin; use rustc_data_structures::frozen::Frozen; use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_data_structures::vec_map::VecMap; use rustc_hir as hir; use rustc_hir::def::DefKind; use rustc_hir::def_id::LocalDefId; use rustc_hir::lang_items::LangItem; use rustc_index::vec::{Idx, IndexVec}; use rustc_infer::infer::canonical::QueryRegionConstraints; use rustc_infer::infer::outlives::env::RegionBoundPairs; use rustc_infer::infer::region_constraints::RegionConstraintData; use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; use rustc_infer::infer::{ InferCtxt, InferOk, LateBoundRegion, LateBoundRegionConversionTime, NllRegionVariableOrigin, }; use rustc_middle::mir::tcx::PlaceTy; use rustc_middle::mir::visit::{NonMutatingUseContext, PlaceContext, Visitor}; use rustc_middle::mir::AssertKind; use rustc_middle::mir::*; use rustc_middle::ty::adjustment::PointerCast; use rustc_middle::ty::cast::CastTy; use rustc_middle::ty::subst::{SubstsRef, UserSubsts}; use rustc_middle::ty::visit::TypeVisitable; use rustc_middle::ty::{ self, Binder, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, Dynamic, OpaqueHiddenType, OpaqueTypeKey, RegionVid, Ty, TyCtxt, UserType, UserTypeAnnotationIndex, }; use rustc_span::def_id::CRATE_DEF_ID; use rustc_span::{Span, DUMMY_SP}; use rustc_target::abi::VariantIdx; use rustc_trait_selection::traits::query::type_op::custom::scrape_region_constraints; use rustc_trait_selection::traits::query::type_op::custom::CustomTypeOp; use rustc_trait_selection::traits::query::type_op::{TypeOp, TypeOpOutput}; use rustc_trait_selection::traits::query::Fallible; use rustc_trait_selection::traits::PredicateObligation; use rustc_mir_dataflow::impls::MaybeInitializedPlaces; use rustc_mir_dataflow::move_paths::MoveData; use rustc_mir_dataflow::ResultsCursor; use crate::session_diagnostics::MoveUnsized; use crate::{ borrow_set::BorrowSet, constraints::{OutlivesConstraint, OutlivesConstraintSet}, diagnostics::UniverseInfo, facts::AllFacts, location::LocationTable, member_constraints::MemberConstraintSet, nll::ToRegionVid, path_utils, region_infer::values::{ LivenessValues, PlaceholderIndex, PlaceholderIndices, RegionValueElements, }, region_infer::TypeTest, type_check::free_region_relations::{CreateResult, UniversalRegionRelations}, universal_regions::{DefiningTy, UniversalRegions}, Upvar, }; macro_rules! span_mirbug { ($context:expr, $elem:expr, $($message:tt)*) => ({ $crate::type_check::mirbug( $context.tcx(), $context.last_span, &format!( "broken MIR in {:?} ({:?}): {}", $context.body().source.def_id(), $elem, format_args!($($message)*), ), ) }) } macro_rules! span_mirbug_and_err { ($context:expr, $elem:expr, $($message:tt)*) => ({ { span_mirbug!($context, $elem, $($message)*); $context.error() } }) } mod canonical; mod constraint_conversion; pub mod free_region_relations; mod input_output; pub(crate) mod liveness; mod relate_tys; /// Type checks the given `mir` in the context of the inference /// context `infcx`. Returns any region constraints that have yet to /// be proven. This result includes liveness constraints that /// ensure that regions appearing in the types of all local variables /// are live at all points where that local variable may later be /// used. /// /// This phase of type-check ought to be infallible -- this is because /// the original, HIR-based type-check succeeded. So if any errors /// occur here, we will get a `bug!` reported. /// /// # Parameters /// /// - `infcx` -- inference context to use /// - `param_env` -- parameter environment to use for trait solving /// - `body` -- MIR body to type-check /// - `promoted` -- map of promoted constants within `body` /// - `universal_regions` -- the universal regions from `body`s function signature /// - `location_table` -- MIR location map of `body` /// - `borrow_set` -- information about borrows occurring in `body` /// - `all_facts` -- when using Polonius, this is the generated set of Polonius facts /// - `flow_inits` -- results of a maybe-init dataflow analysis /// - `move_data` -- move-data constructed when performing the maybe-init dataflow analysis /// - `elements` -- MIR region map pub(crate) fn type_check<'mir, 'tcx>( infcx: &InferCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, body: &Body<'tcx>, promoted: &IndexVec>, universal_regions: &Rc>, location_table: &LocationTable, borrow_set: &BorrowSet<'tcx>, all_facts: &mut Option, flow_inits: &mut ResultsCursor<'mir, 'tcx, MaybeInitializedPlaces<'mir, 'tcx>>, move_data: &MoveData<'tcx>, elements: &Rc, upvars: &[Upvar<'tcx>], use_polonius: bool, ) -> MirTypeckResults<'tcx> { let implicit_region_bound = infcx.tcx.mk_region(ty::ReVar(universal_regions.fr_fn_body)); let mut constraints = MirTypeckRegionConstraints { placeholder_indices: PlaceholderIndices::default(), placeholder_index_to_region: IndexVec::default(), liveness_constraints: LivenessValues::new(elements.clone()), outlives_constraints: OutlivesConstraintSet::default(), member_constraints: MemberConstraintSet::default(), type_tests: Vec::default(), universe_causes: FxHashMap::default(), }; let CreateResult { universal_region_relations, region_bound_pairs, normalized_inputs_and_output, } = free_region_relations::create( infcx, param_env, implicit_region_bound, universal_regions, &mut constraints, ); debug!(?normalized_inputs_and_output); for u in ty::UniverseIndex::ROOT..=infcx.universe() { constraints.universe_causes.insert(u, UniverseInfo::other()); } let mut borrowck_context = BorrowCheckContext { universal_regions, location_table, borrow_set, all_facts, constraints: &mut constraints, upvars, }; let mut checker = TypeChecker::new( infcx, body, param_env, ®ion_bound_pairs, implicit_region_bound, &mut borrowck_context, ); let errors_reported = { let mut verifier = TypeVerifier::new(&mut checker, promoted); verifier.visit_body(&body); verifier.errors_reported }; if !errors_reported { // if verifier failed, don't do further checks to avoid ICEs checker.typeck_mir(body); } checker.equate_inputs_and_outputs(&body, universal_regions, &normalized_inputs_and_output); checker.check_signature_annotation(&body); liveness::generate( &mut checker, body, elements, flow_inits, move_data, location_table, use_polonius, ); translate_outlives_facts(&mut checker); let opaque_type_values = infcx.take_opaque_types(); let opaque_type_values = opaque_type_values .into_iter() .map(|(opaque_type_key, decl)| { checker .fully_perform_op( Locations::All(body.span), ConstraintCategory::OpaqueType, CustomTypeOp::new( |infcx| { infcx.register_member_constraints( param_env, opaque_type_key, decl.hidden_type.ty, decl.hidden_type.span, ); Ok(InferOk { value: (), obligations: vec![] }) }, || "opaque_type_map".to_string(), ), ) .unwrap(); let mut hidden_type = infcx.resolve_vars_if_possible(decl.hidden_type); trace!("finalized opaque type {:?} to {:#?}", opaque_type_key, hidden_type.ty.kind()); if hidden_type.has_non_region_infer() { let reported = infcx.tcx.sess.delay_span_bug( decl.hidden_type.span, &format!("could not resolve {:#?}", hidden_type.ty.kind()), ); hidden_type.ty = infcx.tcx.ty_error_with_guaranteed(reported); } (opaque_type_key, (hidden_type, decl.origin)) }) .collect(); MirTypeckResults { constraints, universal_region_relations, opaque_type_values } } fn translate_outlives_facts(typeck: &mut TypeChecker<'_, '_>) { let cx = &mut typeck.borrowck_context; if let Some(facts) = cx.all_facts { let _prof_timer = typeck.infcx.tcx.prof.generic_activity("polonius_fact_generation"); let location_table = cx.location_table; facts.subset_base.extend(cx.constraints.outlives_constraints.outlives().iter().flat_map( |constraint: &OutlivesConstraint<'_>| { if let Some(from_location) = constraint.locations.from_location() { Either::Left(iter::once(( constraint.sup, constraint.sub, location_table.mid_index(from_location), ))) } else { Either::Right( location_table .all_points() .map(move |location| (constraint.sup, constraint.sub, location)), ) } }, )); } } #[track_caller] fn mirbug(tcx: TyCtxt<'_>, span: Span, msg: &str) { // We sometimes see MIR failures (notably predicate failures) due to // the fact that we check rvalue sized predicates here. So use `delay_span_bug` // to avoid reporting bugs in those cases. tcx.sess.diagnostic().delay_span_bug(span, msg); } enum FieldAccessError { OutOfRange { field_count: usize }, } /// Verifies that MIR types are sane to not crash further checks. /// /// The sanitize_XYZ methods here take an MIR object and compute its /// type, calling `span_mirbug` and returning an error type if there /// is a problem. struct TypeVerifier<'a, 'b, 'tcx> { cx: &'a mut TypeChecker<'b, 'tcx>, promoted: &'b IndexVec>, last_span: Span, errors_reported: bool, } impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> { fn visit_span(&mut self, span: Span) { if !span.is_dummy() { self.last_span = span; } } fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, location: Location) { self.sanitize_place(place, location, context); } fn visit_constant(&mut self, constant: &Constant<'tcx>, location: Location) { debug!(?constant, ?location, "visit_constant"); self.super_constant(constant, location); let ty = self.sanitize_type(constant, constant.literal.ty()); self.cx.infcx.tcx.for_each_free_region(&ty, |live_region| { let live_region_vid = self.cx.borrowck_context.universal_regions.to_region_vid(live_region); self.cx .borrowck_context .constraints .liveness_constraints .add_element(live_region_vid, location); }); // HACK(compiler-errors): Constants that are gathered into Body.required_consts // have their locations erased... let locations = if location != Location::START { location.to_locations() } else { Locations::All(constant.span) }; if let Some(annotation_index) = constant.user_ty { if let Err(terr) = self.cx.relate_type_and_user_type( constant.literal.ty(), ty::Variance::Invariant, &UserTypeProjection { base: annotation_index, projs: vec![] }, locations, ConstraintCategory::Boring, ) { let annotation = &self.cx.user_type_annotations[annotation_index]; span_mirbug!( self, constant, "bad constant user type {:?} vs {:?}: {:?}", annotation, constant.literal.ty(), terr, ); } } else { let tcx = self.tcx(); let maybe_uneval = match constant.literal { ConstantKind::Ty(ct) => match ct.kind() { ty::ConstKind::Unevaluated(_) => { bug!("should not encounter unevaluated ConstantKind::Ty here, got {:?}", ct) } _ => None, }, ConstantKind::Unevaluated(uv, _) => Some(uv), _ => None, }; if let Some(uv) = maybe_uneval { if let Some(promoted) = uv.promoted { let check_err = |verifier: &mut TypeVerifier<'a, 'b, 'tcx>, promoted: &Body<'tcx>, ty, san_ty| { if let Err(terr) = verifier.cx.eq_types(ty, san_ty, locations, ConstraintCategory::Boring) { span_mirbug!( verifier, promoted, "bad promoted type ({:?}: {:?}): {:?}", ty, san_ty, terr ); }; }; if !self.errors_reported { let promoted_body = &self.promoted[promoted]; self.sanitize_promoted(promoted_body, location); let promoted_ty = promoted_body.return_ty(); check_err(self, promoted_body, ty, promoted_ty); } } else { self.cx.ascribe_user_type( constant.literal.ty(), UserType::TypeOf( uv.def.did, UserSubsts { substs: uv.substs, user_self_ty: None }, ), locations.span(&self.cx.body), ); } } else if let Some(static_def_id) = constant.check_static_ptr(tcx) { let unnormalized_ty = tcx.type_of(static_def_id); let normalized_ty = self.cx.normalize(unnormalized_ty, locations); let literal_ty = constant.literal.ty().builtin_deref(true).unwrap().ty; if let Err(terr) = self.cx.eq_types( literal_ty, normalized_ty, locations, ConstraintCategory::Boring, ) { span_mirbug!(self, constant, "bad static type {:?} ({:?})", constant, terr); } } if let ty::FnDef(def_id, substs) = *constant.literal.ty().kind() { // const_trait_impl: use a non-const param env when checking that a FnDef type is well formed. // this is because the well-formedness of the function does not need to be proved to have `const` // impls for trait bounds. let instantiated_predicates = tcx.predicates_of(def_id).instantiate(tcx, substs); let prev = self.cx.param_env; self.cx.param_env = prev.without_const(); self.cx.normalize_and_prove_instantiated_predicates( def_id, instantiated_predicates, locations, ); self.cx.param_env = prev; } } } fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) { self.super_rvalue(rvalue, location); let rval_ty = rvalue.ty(self.body(), self.tcx()); self.sanitize_type(rvalue, rval_ty); } fn visit_local_decl(&mut self, local: Local, local_decl: &LocalDecl<'tcx>) { self.super_local_decl(local, local_decl); self.sanitize_type(local_decl, local_decl.ty); if let Some(user_ty) = &local_decl.user_ty { for (user_ty, span) in user_ty.projections_and_spans() { let ty = if !local_decl.is_nonref_binding() { // If we have a binding of the form `let ref x: T = ..` // then remove the outermost reference so we can check the // type annotation for the remaining type. if let ty::Ref(_, rty, _) = local_decl.ty.kind() { *rty } else { bug!("{:?} with ref binding has wrong type {}", local, local_decl.ty); } } else { local_decl.ty }; if let Err(terr) = self.cx.relate_type_and_user_type( ty, ty::Variance::Invariant, user_ty, Locations::All(*span), ConstraintCategory::TypeAnnotation, ) { span_mirbug!( self, local, "bad user type on variable {:?}: {:?} != {:?} ({:?})", local, local_decl.ty, local_decl.user_ty, terr, ); } } } } fn visit_body(&mut self, body: &Body<'tcx>) { self.sanitize_type(&"return type", body.return_ty()); for local_decl in &body.local_decls { self.sanitize_type(local_decl, local_decl.ty); } if self.errors_reported { return; } self.super_body(body); } } impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> { fn new( cx: &'a mut TypeChecker<'b, 'tcx>, promoted: &'b IndexVec>, ) -> Self { TypeVerifier { promoted, last_span: cx.body.span, cx, errors_reported: false } } fn body(&self) -> &Body<'tcx> { self.cx.body } fn tcx(&self) -> TyCtxt<'tcx> { self.cx.infcx.tcx } fn sanitize_type(&mut self, parent: &dyn fmt::Debug, ty: Ty<'tcx>) -> Ty<'tcx> { if ty.has_escaping_bound_vars() || ty.references_error() { span_mirbug_and_err!(self, parent, "bad type {:?}", ty) } else { ty } } /// Checks that the types internal to the `place` match up with /// what would be expected. fn sanitize_place( &mut self, place: &Place<'tcx>, location: Location, context: PlaceContext, ) -> PlaceTy<'tcx> { debug!("sanitize_place: {:?}", place); let mut place_ty = PlaceTy::from_ty(self.body().local_decls[place.local].ty); for elem in place.projection.iter() { if place_ty.variant_index.is_none() { if place_ty.ty.references_error() { assert!(self.errors_reported); return PlaceTy::from_ty(self.tcx().ty_error()); } } place_ty = self.sanitize_projection(place_ty, elem, place, location); } if let PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy) = context { let tcx = self.tcx(); let trait_ref = tcx.at(self.last_span).mk_trait_ref(LangItem::Copy, [place_ty.ty]); // To have a `Copy` operand, the type `T` of the // value must be `Copy`. Note that we prove that `T: Copy`, // rather than using the `is_copy_modulo_regions` // test. This is important because // `is_copy_modulo_regions` ignores the resulting region // obligations and assumes they pass. This can result in // bounds from `Copy` impls being unsoundly ignored (e.g., // #29149). Note that we decide to use `Copy` before knowing // whether the bounds fully apply: in effect, the rule is // that if a value of some type could implement `Copy`, then // it must. self.cx.prove_trait_ref( trait_ref, location.to_locations(), ConstraintCategory::CopyBound, ); } place_ty } fn sanitize_promoted(&mut self, promoted_body: &'b Body<'tcx>, location: Location) { // Determine the constraints from the promoted MIR by running the type // checker on the promoted MIR, then transfer the constraints back to // the main MIR, changing the locations to the provided location. let parent_body = mem::replace(&mut self.cx.body, promoted_body); // Use new sets of constraints and closure bounds so that we can // modify their locations. let all_facts = &mut None; let mut constraints = Default::default(); let mut liveness_constraints = LivenessValues::new(Rc::new(RegionValueElements::new(&promoted_body))); // Don't try to add borrow_region facts for the promoted MIR let mut swap_constraints = |this: &mut Self| { mem::swap(this.cx.borrowck_context.all_facts, all_facts); mem::swap( &mut this.cx.borrowck_context.constraints.outlives_constraints, &mut constraints, ); mem::swap( &mut this.cx.borrowck_context.constraints.liveness_constraints, &mut liveness_constraints, ); }; swap_constraints(self); self.visit_body(&promoted_body); if !self.errors_reported { // if verifier failed, don't do further checks to avoid ICEs self.cx.typeck_mir(promoted_body); } self.cx.body = parent_body; // Merge the outlives constraints back in, at the given location. swap_constraints(self); let locations = location.to_locations(); for constraint in constraints.outlives().iter() { let mut constraint = *constraint; constraint.locations = locations; if let ConstraintCategory::Return(_) | ConstraintCategory::UseAsConst | ConstraintCategory::UseAsStatic = constraint.category { // "Returning" from a promoted is an assignment to a // temporary from the user's point of view. constraint.category = ConstraintCategory::Boring; } self.cx.borrowck_context.constraints.outlives_constraints.push(constraint) } for region in liveness_constraints.rows() { // If the region is live at at least one location in the promoted MIR, // then add a liveness constraint to the main MIR for this region // at the location provided as an argument to this method if liveness_constraints.get_elements(region).next().is_some() { self.cx .borrowck_context .constraints .liveness_constraints .add_element(region, location); } } } fn sanitize_projection( &mut self, base: PlaceTy<'tcx>, pi: PlaceElem<'tcx>, place: &Place<'tcx>, location: Location, ) -> PlaceTy<'tcx> { debug!("sanitize_projection: {:?} {:?} {:?}", base, pi, place); let tcx = self.tcx(); let base_ty = base.ty; match pi { ProjectionElem::Deref => { let deref_ty = base_ty.builtin_deref(true); PlaceTy::from_ty(deref_ty.map(|t| t.ty).unwrap_or_else(|| { span_mirbug_and_err!(self, place, "deref of non-pointer {:?}", base_ty) })) } ProjectionElem::Index(i) => { let index_ty = Place::from(i).ty(self.body(), tcx).ty; if index_ty != tcx.types.usize { PlaceTy::from_ty(span_mirbug_and_err!(self, i, "index by non-usize {:?}", i)) } else { PlaceTy::from_ty(base_ty.builtin_index().unwrap_or_else(|| { span_mirbug_and_err!(self, place, "index of non-array {:?}", base_ty) })) } } ProjectionElem::ConstantIndex { .. } => { // consider verifying in-bounds PlaceTy::from_ty(base_ty.builtin_index().unwrap_or_else(|| { span_mirbug_and_err!(self, place, "index of non-array {:?}", base_ty) })) } ProjectionElem::Subslice { from, to, from_end } => { PlaceTy::from_ty(match base_ty.kind() { ty::Array(inner, _) => { assert!(!from_end, "array subslices should not use from_end"); tcx.mk_array(*inner, to - from) } ty::Slice(..) => { assert!(from_end, "slice subslices should use from_end"); base_ty } _ => span_mirbug_and_err!(self, place, "slice of non-array {:?}", base_ty), }) } ProjectionElem::Downcast(maybe_name, index) => match base_ty.kind() { ty::Adt(adt_def, _substs) if adt_def.is_enum() => { if index.as_usize() >= adt_def.variants().len() { PlaceTy::from_ty(span_mirbug_and_err!( self, place, "cast to variant #{:?} but enum only has {:?}", index, adt_def.variants().len() )) } else { PlaceTy { ty: base_ty, variant_index: Some(index) } } } // We do not need to handle generators here, because this runs // before the generator transform stage. _ => { let ty = if let Some(name) = maybe_name { span_mirbug_and_err!( self, place, "can't downcast {:?} as {:?}", base_ty, name ) } else { span_mirbug_and_err!(self, place, "can't downcast {:?}", base_ty) }; PlaceTy::from_ty(ty) } }, ProjectionElem::Field(field, fty) => { let fty = self.sanitize_type(place, fty); let fty = self.cx.normalize(fty, location); match self.field_ty(place, base, field, location) { Ok(ty) => { let ty = self.cx.normalize(ty, location); if let Err(terr) = self.cx.eq_types( ty, fty, location.to_locations(), ConstraintCategory::Boring, ) { span_mirbug!( self, place, "bad field access ({:?}: {:?}): {:?}", ty, fty, terr ); } } Err(FieldAccessError::OutOfRange { field_count }) => span_mirbug!( self, place, "accessed field #{} but variant only has {}", field.index(), field_count ), } PlaceTy::from_ty(fty) } ProjectionElem::OpaqueCast(ty) => { let ty = self.sanitize_type(place, ty); let ty = self.cx.normalize(ty, location); self.cx .eq_types( base.ty, ty, location.to_locations(), ConstraintCategory::TypeAnnotation, ) .unwrap(); PlaceTy::from_ty(ty) } } } fn error(&mut self) -> Ty<'tcx> { self.errors_reported = true; self.tcx().ty_error() } fn field_ty( &mut self, parent: &dyn fmt::Debug, base_ty: PlaceTy<'tcx>, field: Field, location: Location, ) -> Result, FieldAccessError> { let tcx = self.tcx(); let (variant, substs) = match base_ty { PlaceTy { ty, variant_index: Some(variant_index) } => match *ty.kind() { ty::Adt(adt_def, substs) => (adt_def.variant(variant_index), substs), ty::Generator(def_id, substs, _) => { let mut variants = substs.as_generator().state_tys(def_id, tcx); let Some(mut variant) = variants.nth(variant_index.into()) else { bug!( "variant_index of generator out of range: {:?}/{:?}", variant_index, substs.as_generator().state_tys(def_id, tcx).count() ); }; return match variant.nth(field.index()) { Some(ty) => Ok(ty), None => Err(FieldAccessError::OutOfRange { field_count: variant.count() }), }; } _ => bug!("can't have downcast of non-adt non-generator type"), }, PlaceTy { ty, variant_index: None } => match *ty.kind() { ty::Adt(adt_def, substs) if !adt_def.is_enum() => { (adt_def.variant(VariantIdx::new(0)), substs) } ty::Closure(_, substs) => { return match substs .as_closure() .tupled_upvars_ty() .tuple_fields() .get(field.index()) { Some(&ty) => Ok(ty), None => Err(FieldAccessError::OutOfRange { field_count: substs.as_closure().upvar_tys().count(), }), }; } ty::Generator(_, substs, _) => { // Only prefix fields (upvars and current state) are // accessible without a variant index. return match substs.as_generator().prefix_tys().nth(field.index()) { Some(ty) => Ok(ty), None => Err(FieldAccessError::OutOfRange { field_count: substs.as_generator().prefix_tys().count(), }), }; } ty::Tuple(tys) => { return match tys.get(field.index()) { Some(&ty) => Ok(ty), None => Err(FieldAccessError::OutOfRange { field_count: tys.len() }), }; } _ => { return Ok(span_mirbug_and_err!( self, parent, "can't project out of {:?}", base_ty )); } }, }; if let Some(field) = variant.fields.get(field.index()) { Ok(self.cx.normalize(field.ty(tcx, substs), location)) } else { Err(FieldAccessError::OutOfRange { field_count: variant.fields.len() }) } } } /// The MIR type checker. Visits the MIR and enforces all the /// constraints needed for it to be valid and well-typed. Along the /// way, it accrues region constraints -- these can later be used by /// NLL region checking. struct TypeChecker<'a, 'tcx> { infcx: &'a InferCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, last_span: Span, body: &'a Body<'tcx>, /// User type annotations are shared between the main MIR and the MIR of /// all of the promoted items. user_type_annotations: &'a CanonicalUserTypeAnnotations<'tcx>, region_bound_pairs: &'a RegionBoundPairs<'tcx>, implicit_region_bound: ty::Region<'tcx>, reported_errors: FxHashSet<(Ty<'tcx>, Span)>, borrowck_context: &'a mut BorrowCheckContext<'a, 'tcx>, } struct BorrowCheckContext<'a, 'tcx> { pub(crate) universal_regions: &'a UniversalRegions<'tcx>, location_table: &'a LocationTable, all_facts: &'a mut Option, borrow_set: &'a BorrowSet<'tcx>, pub(crate) constraints: &'a mut MirTypeckRegionConstraints<'tcx>, upvars: &'a [Upvar<'tcx>], } pub(crate) struct MirTypeckResults<'tcx> { pub(crate) constraints: MirTypeckRegionConstraints<'tcx>, pub(crate) universal_region_relations: Frozen>, pub(crate) opaque_type_values: VecMap, (OpaqueHiddenType<'tcx>, OpaqueTyOrigin)>, } /// A collection of region constraints that must be satisfied for the /// program to be considered well-typed. pub(crate) struct MirTypeckRegionConstraints<'tcx> { /// Maps from a `ty::Placeholder` to the corresponding /// `PlaceholderIndex` bit that we will use for it. /// /// To keep everything in sync, do not insert this set /// directly. Instead, use the `placeholder_region` helper. pub(crate) placeholder_indices: PlaceholderIndices, /// Each time we add a placeholder to `placeholder_indices`, we /// also create a corresponding "representative" region vid for /// that wraps it. This vector tracks those. This way, when we /// convert the same `ty::RePlaceholder(p)` twice, we can map to /// the same underlying `RegionVid`. pub(crate) placeholder_index_to_region: IndexVec>, /// In general, the type-checker is not responsible for enforcing /// liveness constraints; this job falls to the region inferencer, /// which performs a liveness analysis. However, in some limited /// cases, the MIR type-checker creates temporary regions that do /// not otherwise appear in the MIR -- in particular, the /// late-bound regions that it instantiates at call-sites -- and /// hence it must report on their liveness constraints. pub(crate) liveness_constraints: LivenessValues, pub(crate) outlives_constraints: OutlivesConstraintSet<'tcx>, pub(crate) member_constraints: MemberConstraintSet<'tcx, RegionVid>, pub(crate) universe_causes: FxHashMap>, pub(crate) type_tests: Vec>, } impl<'tcx> MirTypeckRegionConstraints<'tcx> { fn placeholder_region( &mut self, infcx: &InferCtxt<'tcx>, placeholder: ty::PlaceholderRegion, ) -> ty::Region<'tcx> { let placeholder_index = self.placeholder_indices.insert(placeholder); match self.placeholder_index_to_region.get(placeholder_index) { Some(&v) => v, None => { let origin = NllRegionVariableOrigin::Placeholder(placeholder); let region = infcx.next_nll_region_var_in_universe(origin, placeholder.universe); self.placeholder_index_to_region.push(region); region } } } } /// The `Locations` type summarizes *where* region constraints are /// required to hold. Normally, this is at a particular point which /// created the obligation, but for constraints that the user gave, we /// want the constraint to hold at all points. #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)] pub enum Locations { /// Indicates that a type constraint should always be true. This /// is particularly important in the new borrowck analysis for /// things like the type of the return slot. Consider this /// example: /// /// ```compile_fail,E0515 /// fn foo<'a>(x: &'a u32) -> &'a u32 { /// let y = 22; /// return &y; // error /// } /// ``` /// /// Here, we wind up with the signature from the return type being /// something like `&'1 u32` where `'1` is a universal region. But /// the type of the return slot `_0` is something like `&'2 u32` /// where `'2` is an existential region variable. The type checker /// requires that `&'2 u32 = &'1 u32` -- but at what point? In the /// older NLL analysis, we required this only at the entry point /// to the function. By the nature of the constraints, this wound /// up propagating to all points reachable from start (because /// `'1` -- as a universal region -- is live everywhere). In the /// newer analysis, though, this doesn't work: `_0` is considered /// dead at the start (it has no usable value) and hence this type /// equality is basically a no-op. Then, later on, when we do `_0 /// = &'3 y`, that region `'3` never winds up related to the /// universal region `'1` and hence no error occurs. Therefore, we /// use Locations::All instead, which ensures that the `'1` and /// `'2` are equal everything. We also use this for other /// user-given type annotations; e.g., if the user wrote `let mut /// x: &'static u32 = ...`, we would ensure that all values /// assigned to `x` are of `'static` lifetime. /// /// The span points to the place the constraint arose. For example, /// it points to the type in a user-given type annotation. If /// there's no sensible span then it's DUMMY_SP. All(Span), /// An outlives constraint that only has to hold at a single location, /// usually it represents a point where references flow from one spot to /// another (e.g., `x = y`) Single(Location), } impl Locations { pub fn from_location(&self) -> Option { match self { Locations::All(_) => None, Locations::Single(from_location) => Some(*from_location), } } /// Gets a span representing the location. pub fn span(&self, body: &Body<'_>) -> Span { match self { Locations::All(span) => *span, Locations::Single(l) => body.source_info(*l).span, } } } impl<'a, 'tcx> TypeChecker<'a, 'tcx> { fn new( infcx: &'a InferCtxt<'tcx>, body: &'a Body<'tcx>, param_env: ty::ParamEnv<'tcx>, region_bound_pairs: &'a RegionBoundPairs<'tcx>, implicit_region_bound: ty::Region<'tcx>, borrowck_context: &'a mut BorrowCheckContext<'a, 'tcx>, ) -> Self { let mut checker = Self { infcx, last_span: DUMMY_SP, body, user_type_annotations: &body.user_type_annotations, param_env, region_bound_pairs, implicit_region_bound, borrowck_context, reported_errors: Default::default(), }; checker.check_user_type_annotations(); checker } fn body(&self) -> &Body<'tcx> { self.body } fn unsized_feature_enabled(&self) -> bool { let features = self.tcx().features(); features.unsized_locals || features.unsized_fn_params } /// Equate the inferred type and the annotated type for user type annotations #[instrument(skip(self), level = "debug")] fn check_user_type_annotations(&mut self) { debug!(?self.user_type_annotations); for user_annotation in self.user_type_annotations { let CanonicalUserTypeAnnotation { span, ref user_ty, inferred_ty } = *user_annotation; let annotation = self.instantiate_canonical_with_fresh_inference_vars(span, user_ty); self.ascribe_user_type(inferred_ty, annotation, span); } } #[instrument(skip(self, data), level = "debug")] fn push_region_constraints( &mut self, locations: Locations, category: ConstraintCategory<'tcx>, data: &QueryRegionConstraints<'tcx>, ) { debug!("constraints generated: {:#?}", data); constraint_conversion::ConstraintConversion::new( self.infcx, self.borrowck_context.universal_regions, self.region_bound_pairs, self.implicit_region_bound, self.param_env, locations, locations.span(self.body), category, &mut self.borrowck_context.constraints, ) .convert_all(data); } /// Try to relate `sub <: sup` fn sub_types( &mut self, sub: Ty<'tcx>, sup: Ty<'tcx>, locations: Locations, category: ConstraintCategory<'tcx>, ) -> Fallible<()> { // Use this order of parameters because the sup type is usually the // "expected" type in diagnostics. self.relate_types(sup, ty::Variance::Contravariant, sub, locations, category) } #[instrument(skip(self, category), level = "debug")] fn eq_types( &mut self, expected: Ty<'tcx>, found: Ty<'tcx>, locations: Locations, category: ConstraintCategory<'tcx>, ) -> Fallible<()> { self.relate_types(expected, ty::Variance::Invariant, found, locations, category) } #[instrument(skip(self), level = "debug")] fn relate_type_and_user_type( &mut self, a: Ty<'tcx>, v: ty::Variance, user_ty: &UserTypeProjection, locations: Locations, category: ConstraintCategory<'tcx>, ) -> Fallible<()> { let annotated_type = self.user_type_annotations[user_ty.base].inferred_ty; trace!(?annotated_type); let mut curr_projected_ty = PlaceTy::from_ty(annotated_type); let tcx = self.infcx.tcx; for proj in &user_ty.projs { if let ty::Alias(ty::Opaque, ..) = curr_projected_ty.ty.kind() { // There is nothing that we can compare here if we go through an opaque type. // We're always in its defining scope as we can otherwise not project through // it, so we're constraining it anyways. return Ok(()); } let projected_ty = curr_projected_ty.projection_ty_core( tcx, self.param_env, proj, |this, field, ()| { let ty = this.field_ty(tcx, field); self.normalize(ty, locations) }, |_, _| unreachable!(), ); curr_projected_ty = projected_ty; } trace!(?curr_projected_ty); let ty = curr_projected_ty.ty; self.relate_types(ty, v.xform(ty::Variance::Contravariant), a, locations, category)?; Ok(()) } fn tcx(&self) -> TyCtxt<'tcx> { self.infcx.tcx } #[instrument(skip(self, body, location), level = "debug")] fn check_stmt(&mut self, body: &Body<'tcx>, stmt: &Statement<'tcx>, location: Location) { let tcx = self.tcx(); debug!("stmt kind: {:?}", stmt.kind); match &stmt.kind { StatementKind::Assign(box (place, rv)) => { // Assignments to temporaries are not "interesting"; // they are not caused by the user, but rather artifacts // of lowering. Assignments to other sorts of places *are* interesting // though. let category = match place.as_local() { Some(RETURN_PLACE) => { let defining_ty = &self.borrowck_context.universal_regions.defining_ty; if defining_ty.is_const() { if tcx.is_static(defining_ty.def_id()) { ConstraintCategory::UseAsStatic } else { ConstraintCategory::UseAsConst } } else { ConstraintCategory::Return(ReturnConstraint::Normal) } } Some(l) if matches!( body.local_decls[l].local_info, Some(box LocalInfo::AggregateTemp) ) => { ConstraintCategory::Usage } Some(l) if !body.local_decls[l].is_user_variable() => { ConstraintCategory::Boring } _ => ConstraintCategory::Assignment, }; debug!( "assignment category: {:?} {:?}", category, place.as_local().map(|l| &body.local_decls[l]) ); let place_ty = place.ty(body, tcx).ty; debug!(?place_ty); let place_ty = self.normalize(place_ty, location); debug!("place_ty normalized: {:?}", place_ty); let rv_ty = rv.ty(body, tcx); debug!(?rv_ty); let rv_ty = self.normalize(rv_ty, location); debug!("normalized rv_ty: {:?}", rv_ty); if let Err(terr) = self.sub_types(rv_ty, place_ty, location.to_locations(), category) { span_mirbug!( self, stmt, "bad assignment ({:?} = {:?}): {:?}", place_ty, rv_ty, terr ); } if let Some(annotation_index) = self.rvalue_user_ty(rv) { if let Err(terr) = self.relate_type_and_user_type( rv_ty, ty::Variance::Invariant, &UserTypeProjection { base: annotation_index, projs: vec![] }, location.to_locations(), ConstraintCategory::Boring, ) { let annotation = &self.user_type_annotations[annotation_index]; span_mirbug!( self, stmt, "bad user type on rvalue ({:?} = {:?}): {:?}", annotation, rv_ty, terr ); } } self.check_rvalue(body, rv, location); if !self.unsized_feature_enabled() { let trait_ref = tcx.at(self.last_span).mk_trait_ref(LangItem::Sized, [place_ty]); self.prove_trait_ref( trait_ref, location.to_locations(), ConstraintCategory::SizedBound, ); } } StatementKind::AscribeUserType(box (place, projection), variance) => { let place_ty = place.ty(body, tcx).ty; if let Err(terr) = self.relate_type_and_user_type( place_ty, *variance, projection, Locations::All(stmt.source_info.span), ConstraintCategory::TypeAnnotation, ) { let annotation = &self.user_type_annotations[projection.base]; span_mirbug!( self, stmt, "bad type assert ({:?} <: {:?} with projections {:?}): {:?}", place_ty, annotation, projection.projs, terr ); } } StatementKind::Intrinsic(box kind) => match kind { NonDivergingIntrinsic::Assume(op) => self.check_operand(op, location), NonDivergingIntrinsic::CopyNonOverlapping(..) => span_bug!( stmt.source_info.span, "Unexpected NonDivergingIntrinsic::CopyNonOverlapping, should only appear after lowering_intrinsics", ), }, StatementKind::FakeRead(..) | StatementKind::StorageLive(..) | StatementKind::StorageDead(..) | StatementKind::Retag { .. } | StatementKind::Coverage(..) | StatementKind::Nop => {} StatementKind::Deinit(..) | StatementKind::SetDiscriminant { .. } => { bug!("Statement not allowed in this MIR phase") } } } #[instrument(skip(self, body, term_location), level = "debug")] fn check_terminator( &mut self, body: &Body<'tcx>, term: &Terminator<'tcx>, term_location: Location, ) { let tcx = self.tcx(); debug!("terminator kind: {:?}", term.kind); match &term.kind { TerminatorKind::Goto { .. } | TerminatorKind::Resume | TerminatorKind::Abort | TerminatorKind::Return | TerminatorKind::GeneratorDrop | TerminatorKind::Unreachable | TerminatorKind::Drop { .. } | TerminatorKind::FalseEdge { .. } | TerminatorKind::FalseUnwind { .. } | TerminatorKind::InlineAsm { .. } => { // no checks needed for these } TerminatorKind::DropAndReplace { place, value, target: _, unwind: _ } => { let place_ty = place.ty(body, tcx).ty; let rv_ty = value.ty(body, tcx); let locations = term_location.to_locations(); if let Err(terr) = self.sub_types(rv_ty, place_ty, locations, ConstraintCategory::Assignment) { span_mirbug!( self, term, "bad DropAndReplace ({:?} = {:?}): {:?}", place_ty, rv_ty, terr ); } } TerminatorKind::SwitchInt { discr, .. } => { self.check_operand(discr, term_location); let switch_ty = discr.ty(body, tcx); if !switch_ty.is_integral() && !switch_ty.is_char() && !switch_ty.is_bool() { span_mirbug!(self, term, "bad SwitchInt discr ty {:?}", switch_ty); } // FIXME: check the values } TerminatorKind::Call { func, args, destination, from_hir_call, target, .. } => { self.check_operand(func, term_location); for arg in args { self.check_operand(arg, term_location); } let func_ty = func.ty(body, tcx); debug!("func_ty.kind: {:?}", func_ty.kind()); let sig = match func_ty.kind() { ty::FnDef(..) | ty::FnPtr(_) => func_ty.fn_sig(tcx), _ => { span_mirbug!(self, term, "call to non-function {:?}", func_ty); return; } }; let (sig, map) = tcx.replace_late_bound_regions(sig, |br| { self.infcx.next_region_var(LateBoundRegion( term.source_info.span, br.kind, LateBoundRegionConversionTime::FnCall, )) }); debug!(?sig); // IMPORTANT: We have to prove well formed for the function signature before // we normalize it, as otherwise types like `<&'a &'b () as Trait>::Assoc` // get normalized away, causing us to ignore the `'b: 'a` bound used by the function. // // Normalization results in a well formed type if the input is well formed, so we // don't have to check it twice. // // See #91068 for an example. self.prove_predicates( sig.inputs_and_output .iter() .map(|ty| ty::Binder::dummy(ty::PredicateKind::WellFormed(ty.into()))), term_location.to_locations(), ConstraintCategory::Boring, ); let sig = self.normalize(sig, term_location); self.check_call_dest(body, term, &sig, *destination, *target, term_location); // The ordinary liveness rules will ensure that all // regions in the type of the callee are live here. We // then further constrain the late-bound regions that // were instantiated at the call site to be live as // well. The resulting is that all the input (and // output) types in the signature must be live, since // all the inputs that fed into it were live. for &late_bound_region in map.values() { let region_vid = self.borrowck_context.universal_regions.to_region_vid(late_bound_region); self.borrowck_context .constraints .liveness_constraints .add_element(region_vid, term_location); } self.check_call_inputs(body, term, &sig, args, term_location, *from_hir_call); } TerminatorKind::Assert { cond, msg, .. } => { self.check_operand(cond, term_location); let cond_ty = cond.ty(body, tcx); if cond_ty != tcx.types.bool { span_mirbug!(self, term, "bad Assert ({:?}, not bool", cond_ty); } if let AssertKind::BoundsCheck { len, index } = msg { if len.ty(body, tcx) != tcx.types.usize { span_mirbug!(self, len, "bounds-check length non-usize {:?}", len) } if index.ty(body, tcx) != tcx.types.usize { span_mirbug!(self, index, "bounds-check index non-usize {:?}", index) } } } TerminatorKind::Yield { value, .. } => { self.check_operand(value, term_location); let value_ty = value.ty(body, tcx); match body.yield_ty() { None => span_mirbug!(self, term, "yield in non-generator"), Some(ty) => { if let Err(terr) = self.sub_types( value_ty, ty, term_location.to_locations(), ConstraintCategory::Yield, ) { span_mirbug!( self, term, "type of yield value is {:?}, but the yield type is {:?}: {:?}", value_ty, ty, terr ); } } } } } } fn check_call_dest( &mut self, body: &Body<'tcx>, term: &Terminator<'tcx>, sig: &ty::FnSig<'tcx>, destination: Place<'tcx>, target: Option, term_location: Location, ) { let tcx = self.tcx(); match target { Some(_) => { let dest_ty = destination.ty(body, tcx).ty; let dest_ty = self.normalize(dest_ty, term_location); let category = match destination.as_local() { Some(RETURN_PLACE) => { if let BorrowCheckContext { universal_regions: UniversalRegions { defining_ty: DefiningTy::Const(def_id, _) | DefiningTy::InlineConst(def_id, _), .. }, .. } = self.borrowck_context { if tcx.is_static(*def_id) { ConstraintCategory::UseAsStatic } else { ConstraintCategory::UseAsConst } } else { ConstraintCategory::Return(ReturnConstraint::Normal) } } Some(l) if !body.local_decls[l].is_user_variable() => { ConstraintCategory::Boring } _ => ConstraintCategory::Assignment, }; let locations = term_location.to_locations(); if let Err(terr) = self.sub_types(sig.output(), dest_ty, locations, category) { span_mirbug!( self, term, "call dest mismatch ({:?} <- {:?}): {:?}", dest_ty, sig.output(), terr ); } // When `unsized_fn_params` and `unsized_locals` are both not enabled, // this check is done at `check_local`. if self.unsized_feature_enabled() { let span = term.source_info.span; self.ensure_place_sized(dest_ty, span); } } None => { if !sig.output().is_privately_uninhabited(self.tcx(), self.param_env) { span_mirbug!(self, term, "call to converging function {:?} w/o dest", sig); } } } } fn check_call_inputs( &mut self, body: &Body<'tcx>, term: &Terminator<'tcx>, sig: &ty::FnSig<'tcx>, args: &[Operand<'tcx>], term_location: Location, from_hir_call: bool, ) { debug!("check_call_inputs({:?}, {:?})", sig, args); if args.len() < sig.inputs().len() || (args.len() > sig.inputs().len() && !sig.c_variadic) { span_mirbug!(self, term, "call to {:?} with wrong # of args", sig); } let func_ty = if let TerminatorKind::Call { func, .. } = &term.kind { Some(func.ty(body, self.infcx.tcx)) } else { None }; debug!(?func_ty); for (n, (fn_arg, op_arg)) in iter::zip(sig.inputs(), args).enumerate() { let op_arg_ty = op_arg.ty(body, self.tcx()); let op_arg_ty = self.normalize(op_arg_ty, term_location); let category = if from_hir_call { ConstraintCategory::CallArgument(self.infcx.tcx.erase_regions(func_ty)) } else { ConstraintCategory::Boring }; if let Err(terr) = self.sub_types(op_arg_ty, *fn_arg, term_location.to_locations(), category) { span_mirbug!( self, term, "bad arg #{:?} ({:?} <- {:?}): {:?}", n, fn_arg, op_arg_ty, terr ); } } } fn check_iscleanup(&mut self, body: &Body<'tcx>, block_data: &BasicBlockData<'tcx>) { let is_cleanup = block_data.is_cleanup; self.last_span = block_data.terminator().source_info.span; match block_data.terminator().kind { TerminatorKind::Goto { target } => { self.assert_iscleanup(body, block_data, target, is_cleanup) } TerminatorKind::SwitchInt { ref targets, .. } => { for target in targets.all_targets() { self.assert_iscleanup(body, block_data, *target, is_cleanup); } } TerminatorKind::Resume => { if !is_cleanup { span_mirbug!(self, block_data, "resume on non-cleanup block!") } } TerminatorKind::Abort => { if !is_cleanup { span_mirbug!(self, block_data, "abort on non-cleanup block!") } } TerminatorKind::Return => { if is_cleanup { span_mirbug!(self, block_data, "return on cleanup block") } } TerminatorKind::GeneratorDrop { .. } => { if is_cleanup { span_mirbug!(self, block_data, "generator_drop in cleanup block") } } TerminatorKind::Yield { resume, drop, .. } => { if is_cleanup { span_mirbug!(self, block_data, "yield in cleanup block") } self.assert_iscleanup(body, block_data, resume, is_cleanup); if let Some(drop) = drop { self.assert_iscleanup(body, block_data, drop, is_cleanup); } } TerminatorKind::Unreachable => {} TerminatorKind::Drop { target, unwind, .. } | TerminatorKind::DropAndReplace { target, unwind, .. } | TerminatorKind::Assert { target, cleanup: unwind, .. } => { self.assert_iscleanup(body, block_data, target, is_cleanup); if let Some(unwind) = unwind { if is_cleanup { span_mirbug!(self, block_data, "unwind on cleanup block") } self.assert_iscleanup(body, block_data, unwind, true); } } TerminatorKind::Call { ref target, cleanup, .. } => { if let &Some(target) = target { self.assert_iscleanup(body, block_data, target, is_cleanup); } if let Some(cleanup) = cleanup { if is_cleanup { span_mirbug!(self, block_data, "cleanup on cleanup block") } self.assert_iscleanup(body, block_data, cleanup, true); } } TerminatorKind::FalseEdge { real_target, imaginary_target } => { self.assert_iscleanup(body, block_data, real_target, is_cleanup); self.assert_iscleanup(body, block_data, imaginary_target, is_cleanup); } TerminatorKind::FalseUnwind { real_target, unwind } => { self.assert_iscleanup(body, block_data, real_target, is_cleanup); if let Some(unwind) = unwind { if is_cleanup { span_mirbug!(self, block_data, "cleanup in cleanup block via false unwind"); } self.assert_iscleanup(body, block_data, unwind, true); } } TerminatorKind::InlineAsm { destination, cleanup, .. } => { if let Some(target) = destination { self.assert_iscleanup(body, block_data, target, is_cleanup); } if let Some(cleanup) = cleanup { if is_cleanup { span_mirbug!(self, block_data, "cleanup on cleanup block") } self.assert_iscleanup(body, block_data, cleanup, true); } } } } fn assert_iscleanup( &mut self, body: &Body<'tcx>, ctxt: &dyn fmt::Debug, bb: BasicBlock, iscleanuppad: bool, ) { if body[bb].is_cleanup != iscleanuppad { span_mirbug!(self, ctxt, "cleanuppad mismatch: {:?} should be {:?}", bb, iscleanuppad); } } fn check_local(&mut self, body: &Body<'tcx>, local: Local, local_decl: &LocalDecl<'tcx>) { match body.local_kind(local) { LocalKind::ReturnPointer | LocalKind::Arg => { // return values of normal functions are required to be // sized by typeck, but return values of ADT constructors are // not because we don't include a `Self: Sized` bounds on them. // // Unbound parts of arguments were never required to be Sized // - maybe we should make that a warning. return; } LocalKind::Var | LocalKind::Temp => {} } // When `unsized_fn_params` or `unsized_locals` is enabled, only function calls // and nullary ops are checked in `check_call_dest`. if !self.unsized_feature_enabled() { let span = local_decl.source_info.span; let ty = local_decl.ty; self.ensure_place_sized(ty, span); } } fn ensure_place_sized(&mut self, ty: Ty<'tcx>, span: Span) { let tcx = self.tcx(); // Erase the regions from `ty` to get a global type. The // `Sized` bound in no way depends on precise regions, so this // shouldn't affect `is_sized`. let erased_ty = tcx.erase_regions(ty); if !erased_ty.is_sized(tcx, self.param_env) { // in current MIR construction, all non-control-flow rvalue // expressions evaluate through `as_temp` or `into` a return // slot or local, so to find all unsized rvalues it is enough // to check all temps, return slots and locals. if self.reported_errors.replace((ty, span)).is_none() { // While this is located in `nll::typeck` this error is not // an NLL error, it's a required check to prevent creation // of unsized rvalues in a call expression. self.tcx().sess.emit_err(MoveUnsized { ty, span }); } } } fn aggregate_field_ty( &mut self, ak: &AggregateKind<'tcx>, field_index: usize, location: Location, ) -> Result, FieldAccessError> { let tcx = self.tcx(); match *ak { AggregateKind::Adt(adt_did, variant_index, substs, _, active_field_index) => { let def = tcx.adt_def(adt_did); let variant = &def.variant(variant_index); let adj_field_index = active_field_index.unwrap_or(field_index); if let Some(field) = variant.fields.get(adj_field_index) { Ok(self.normalize(field.ty(tcx, substs), location)) } else { Err(FieldAccessError::OutOfRange { field_count: variant.fields.len() }) } } AggregateKind::Closure(_, substs) => { match substs.as_closure().upvar_tys().nth(field_index) { Some(ty) => Ok(ty), None => Err(FieldAccessError::OutOfRange { field_count: substs.as_closure().upvar_tys().count(), }), } } AggregateKind::Generator(_, substs, _) => { // It doesn't make sense to look at a field beyond the prefix; // these require a variant index, and are not initialized in // aggregate rvalues. match substs.as_generator().prefix_tys().nth(field_index) { Some(ty) => Ok(ty), None => Err(FieldAccessError::OutOfRange { field_count: substs.as_generator().prefix_tys().count(), }), } } AggregateKind::Array(ty) => Ok(ty), AggregateKind::Tuple => { unreachable!("This should have been covered in check_rvalues"); } } } fn check_operand(&mut self, op: &Operand<'tcx>, location: Location) { debug!(?op, ?location, "check_operand"); if let Operand::Constant(constant) = op { let maybe_uneval = match constant.literal { ConstantKind::Val(..) | ConstantKind::Ty(_) => None, ConstantKind::Unevaluated(uv, _) => Some(uv), }; if let Some(uv) = maybe_uneval { if uv.promoted.is_none() { let tcx = self.tcx(); let def_id = uv.def.def_id_for_type_of(); if tcx.def_kind(def_id) == DefKind::InlineConst { let def_id = def_id.expect_local(); let predicates = self.prove_closure_bounds(tcx, def_id, uv.substs, location); self.normalize_and_prove_instantiated_predicates( def_id.to_def_id(), predicates, location.to_locations(), ); } } } } } #[instrument(skip(self, body), level = "debug")] fn check_rvalue(&mut self, body: &Body<'tcx>, rvalue: &Rvalue<'tcx>, location: Location) { let tcx = self.tcx(); let span = body.source_info(location).span; match rvalue { Rvalue::Aggregate(ak, ops) => { for op in ops { self.check_operand(op, location); } self.check_aggregate_rvalue(&body, rvalue, ak, ops, location) } Rvalue::Repeat(operand, len) => { self.check_operand(operand, location); // If the length cannot be evaluated we must assume that the length can be larger // than 1. // If the length is larger than 1, the repeat expression will need to copy the // element, so we require the `Copy` trait. if len.try_eval_usize(tcx, self.param_env).map_or(true, |len| len > 1) { match operand { Operand::Copy(..) | Operand::Constant(..) => { // These are always okay: direct use of a const, or a value that can evidently be copied. } Operand::Move(place) => { // Make sure that repeated elements implement `Copy`. let ty = place.ty(body, tcx).ty; let trait_ref = tcx.at(span).mk_trait_ref(LangItem::Copy, [ty]); self.prove_trait_ref( trait_ref, Locations::Single(location), ConstraintCategory::CopyBound, ); } } } } &Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf, ty) => { let trait_ref = tcx.at(span).mk_trait_ref(LangItem::Sized, [ty]); self.prove_trait_ref( trait_ref, location.to_locations(), ConstraintCategory::SizedBound, ); } Rvalue::ShallowInitBox(operand, ty) => { self.check_operand(operand, location); let trait_ref = tcx.at(span).mk_trait_ref(LangItem::Sized, [*ty]); self.prove_trait_ref( trait_ref, location.to_locations(), ConstraintCategory::SizedBound, ); } Rvalue::Cast(cast_kind, op, ty) => { self.check_operand(op, location); match cast_kind { CastKind::Pointer(PointerCast::ReifyFnPointer) => { let fn_sig = op.ty(body, tcx).fn_sig(tcx); // The type that we see in the fcx is like // `foo::<'a, 'b>`, where `foo` is the path to a // function definition. When we extract the // signature, it comes from the `fn_sig` query, // and hence may contain unnormalized results. let fn_sig = self.normalize(fn_sig, location); let ty_fn_ptr_from = tcx.mk_fn_ptr(fn_sig); if let Err(terr) = self.eq_types( *ty, ty_fn_ptr_from, location.to_locations(), ConstraintCategory::Cast, ) { span_mirbug!( self, rvalue, "equating {:?} with {:?} yields {:?}", ty_fn_ptr_from, ty, terr ); } } CastKind::Pointer(PointerCast::ClosureFnPointer(unsafety)) => { let sig = match op.ty(body, tcx).kind() { ty::Closure(_, substs) => substs.as_closure().sig(), _ => bug!(), }; let ty_fn_ptr_from = tcx.mk_fn_ptr(tcx.signature_unclosure(sig, *unsafety)); if let Err(terr) = self.eq_types( *ty, ty_fn_ptr_from, location.to_locations(), ConstraintCategory::Cast, ) { span_mirbug!( self, rvalue, "equating {:?} with {:?} yields {:?}", ty_fn_ptr_from, ty, terr ); } } CastKind::Pointer(PointerCast::UnsafeFnPointer) => { let fn_sig = op.ty(body, tcx).fn_sig(tcx); // The type that we see in the fcx is like // `foo::<'a, 'b>`, where `foo` is the path to a // function definition. When we extract the // signature, it comes from the `fn_sig` query, // and hence may contain unnormalized results. let fn_sig = self.normalize(fn_sig, location); let ty_fn_ptr_from = tcx.safe_to_unsafe_fn_ty(fn_sig); if let Err(terr) = self.eq_types( *ty, ty_fn_ptr_from, location.to_locations(), ConstraintCategory::Cast, ) { span_mirbug!( self, rvalue, "equating {:?} with {:?} yields {:?}", ty_fn_ptr_from, ty, terr ); } } CastKind::Pointer(PointerCast::Unsize) => { let &ty = ty; let trait_ref = tcx .at(span) .mk_trait_ref(LangItem::CoerceUnsized, [op.ty(body, tcx), ty]); self.prove_trait_ref( trait_ref, location.to_locations(), ConstraintCategory::Cast, ); } CastKind::DynStar => { // get the constraints from the target type (`dyn* Clone`) // // apply them to prove that the source type `Foo` implements `Clone` etc let (existential_predicates, region) = match ty.kind() { Dynamic(predicates, region, ty::DynStar) => (predicates, region), _ => panic!("Invalid dyn* cast_ty"), }; let self_ty = op.ty(body, tcx); self.prove_predicates( existential_predicates .iter() .map(|predicate| predicate.with_self_ty(tcx, self_ty)), location.to_locations(), ConstraintCategory::Cast, ); let outlives_predicate = tcx.mk_predicate(Binder::dummy(ty::PredicateKind::Clause( ty::Clause::TypeOutlives(ty::OutlivesPredicate(self_ty, *region)), ))); self.prove_predicate( outlives_predicate, location.to_locations(), ConstraintCategory::Cast, ); } CastKind::Pointer(PointerCast::MutToConstPointer) => { let ty::RawPtr(ty::TypeAndMut { ty: ty_from, mutbl: hir::Mutability::Mut, }) = op.ty(body, tcx).kind() else { span_mirbug!( self, rvalue, "unexpected base type for cast {:?}", ty, ); return; }; let ty::RawPtr(ty::TypeAndMut { ty: ty_to, mutbl: hir::Mutability::Not, }) = ty.kind() else { span_mirbug!( self, rvalue, "unexpected target type for cast {:?}", ty, ); return; }; if let Err(terr) = self.sub_types( *ty_from, *ty_to, location.to_locations(), ConstraintCategory::Cast, ) { span_mirbug!( self, rvalue, "relating {:?} with {:?} yields {:?}", ty_from, ty_to, terr ); } } CastKind::Pointer(PointerCast::ArrayToPointer) => { let ty_from = op.ty(body, tcx); let opt_ty_elem_mut = match ty_from.kind() { ty::RawPtr(ty::TypeAndMut { mutbl: array_mut, ty: array_ty }) => { match array_ty.kind() { ty::Array(ty_elem, _) => Some((ty_elem, *array_mut)), _ => None, } } _ => None, }; let Some((ty_elem, ty_mut)) = opt_ty_elem_mut else { span_mirbug!( self, rvalue, "ArrayToPointer cast from unexpected type {:?}", ty_from, ); return; }; let (ty_to, ty_to_mut) = match ty.kind() { ty::RawPtr(ty::TypeAndMut { mutbl: ty_to_mut, ty: ty_to }) => { (ty_to, *ty_to_mut) } _ => { span_mirbug!( self, rvalue, "ArrayToPointer cast to unexpected type {:?}", ty, ); return; } }; if ty_to_mut == Mutability::Mut && ty_mut == Mutability::Not { span_mirbug!( self, rvalue, "ArrayToPointer cast from const {:?} to mut {:?}", ty, ty_to ); return; } if let Err(terr) = self.sub_types( *ty_elem, *ty_to, location.to_locations(), ConstraintCategory::Cast, ) { span_mirbug!( self, rvalue, "relating {:?} with {:?} yields {:?}", ty_elem, ty_to, terr ) } } CastKind::PointerExposeAddress => { let ty_from = op.ty(body, tcx); let cast_ty_from = CastTy::from_ty(ty_from); let cast_ty_to = CastTy::from_ty(*ty); match (cast_ty_from, cast_ty_to) { (Some(CastTy::Ptr(_) | CastTy::FnPtr), Some(CastTy::Int(_))) => (), _ => { span_mirbug!( self, rvalue, "Invalid PointerExposeAddress cast {:?} -> {:?}", ty_from, ty ) } } } CastKind::PointerFromExposedAddress => { let ty_from = op.ty(body, tcx); let cast_ty_from = CastTy::from_ty(ty_from); let cast_ty_to = CastTy::from_ty(*ty); match (cast_ty_from, cast_ty_to) { (Some(CastTy::Int(_)), Some(CastTy::Ptr(_))) => (), _ => { span_mirbug!( self, rvalue, "Invalid PointerFromExposedAddress cast {:?} -> {:?}", ty_from, ty ) } } } CastKind::IntToInt => { let ty_from = op.ty(body, tcx); let cast_ty_from = CastTy::from_ty(ty_from); let cast_ty_to = CastTy::from_ty(*ty); match (cast_ty_from, cast_ty_to) { (Some(CastTy::Int(_)), Some(CastTy::Int(_))) => (), _ => { span_mirbug!( self, rvalue, "Invalid IntToInt cast {:?} -> {:?}", ty_from, ty ) } } } CastKind::IntToFloat => { let ty_from = op.ty(body, tcx); let cast_ty_from = CastTy::from_ty(ty_from); let cast_ty_to = CastTy::from_ty(*ty); match (cast_ty_from, cast_ty_to) { (Some(CastTy::Int(_)), Some(CastTy::Float)) => (), _ => { span_mirbug!( self, rvalue, "Invalid IntToFloat cast {:?} -> {:?}", ty_from, ty ) } } } CastKind::FloatToInt => { let ty_from = op.ty(body, tcx); let cast_ty_from = CastTy::from_ty(ty_from); let cast_ty_to = CastTy::from_ty(*ty); match (cast_ty_from, cast_ty_to) { (Some(CastTy::Float), Some(CastTy::Int(_))) => (), _ => { span_mirbug!( self, rvalue, "Invalid FloatToInt cast {:?} -> {:?}", ty_from, ty ) } } } CastKind::FloatToFloat => { let ty_from = op.ty(body, tcx); let cast_ty_from = CastTy::from_ty(ty_from); let cast_ty_to = CastTy::from_ty(*ty); match (cast_ty_from, cast_ty_to) { (Some(CastTy::Float), Some(CastTy::Float)) => (), _ => { span_mirbug!( self, rvalue, "Invalid FloatToFloat cast {:?} -> {:?}", ty_from, ty ) } } } CastKind::FnPtrToPtr => { let ty_from = op.ty(body, tcx); let cast_ty_from = CastTy::from_ty(ty_from); let cast_ty_to = CastTy::from_ty(*ty); match (cast_ty_from, cast_ty_to) { (Some(CastTy::FnPtr), Some(CastTy::Ptr(_))) => (), _ => { span_mirbug!( self, rvalue, "Invalid FnPtrToPtr cast {:?} -> {:?}", ty_from, ty ) } } } CastKind::PtrToPtr => { let ty_from = op.ty(body, tcx); let cast_ty_from = CastTy::from_ty(ty_from); let cast_ty_to = CastTy::from_ty(*ty); match (cast_ty_from, cast_ty_to) { (Some(CastTy::Ptr(_)), Some(CastTy::Ptr(_))) => (), _ => { span_mirbug!( self, rvalue, "Invalid PtrToPtr cast {:?} -> {:?}", ty_from, ty ) } } } } } Rvalue::Ref(region, _borrow_kind, borrowed_place) => { self.add_reborrow_constraint(&body, location, *region, borrowed_place); } Rvalue::BinaryOp( BinOp::Eq | BinOp::Ne | BinOp::Lt | BinOp::Le | BinOp::Gt | BinOp::Ge, box (left, right), ) => { self.check_operand(left, location); self.check_operand(right, location); let ty_left = left.ty(body, tcx); match ty_left.kind() { // Types with regions are comparable if they have a common super-type. ty::RawPtr(_) | ty::FnPtr(_) => { let ty_right = right.ty(body, tcx); let common_ty = self.infcx.next_ty_var(TypeVariableOrigin { kind: TypeVariableOriginKind::MiscVariable, span: body.source_info(location).span, }); self.sub_types( ty_left, common_ty, location.to_locations(), ConstraintCategory::Boring, ) .unwrap_or_else(|err| { bug!("Could not equate type variable with {:?}: {:?}", ty_left, err) }); if let Err(terr) = self.sub_types( ty_right, common_ty, location.to_locations(), ConstraintCategory::Boring, ) { span_mirbug!( self, rvalue, "unexpected comparison types {:?} and {:?} yields {:?}", ty_left, ty_right, terr ) } } // For types with no regions we can just check that the // both operands have the same type. ty::Int(_) | ty::Uint(_) | ty::Bool | ty::Char | ty::Float(_) if ty_left == right.ty(body, tcx) => {} // Other types are compared by trait methods, not by // `Rvalue::BinaryOp`. _ => span_mirbug!( self, rvalue, "unexpected comparison types {:?} and {:?}", ty_left, right.ty(body, tcx) ), } } Rvalue::Use(operand) | Rvalue::UnaryOp(_, operand) => { self.check_operand(operand, location); } Rvalue::CopyForDeref(place) => { let op = &Operand::Copy(*place); self.check_operand(op, location); } Rvalue::BinaryOp(_, box (left, right)) | Rvalue::CheckedBinaryOp(_, box (left, right)) => { self.check_operand(left, location); self.check_operand(right, location); } Rvalue::AddressOf(..) | Rvalue::ThreadLocalRef(..) | Rvalue::Len(..) | Rvalue::Discriminant(..) => {} } } /// If this rvalue supports a user-given type annotation, then /// extract and return it. This represents the final type of the /// rvalue and will be unified with the inferred type. fn rvalue_user_ty(&self, rvalue: &Rvalue<'tcx>) -> Option { match rvalue { Rvalue::Use(_) | Rvalue::ThreadLocalRef(_) | Rvalue::Repeat(..) | Rvalue::Ref(..) | Rvalue::AddressOf(..) | Rvalue::Len(..) | Rvalue::Cast(..) | Rvalue::ShallowInitBox(..) | Rvalue::BinaryOp(..) | Rvalue::CheckedBinaryOp(..) | Rvalue::NullaryOp(..) | Rvalue::CopyForDeref(..) | Rvalue::UnaryOp(..) | Rvalue::Discriminant(..) => None, Rvalue::Aggregate(aggregate, _) => match **aggregate { AggregateKind::Adt(_, _, _, user_ty, _) => user_ty, AggregateKind::Array(_) => None, AggregateKind::Tuple => None, AggregateKind::Closure(_, _) => None, AggregateKind::Generator(_, _, _) => None, }, } } fn check_aggregate_rvalue( &mut self, body: &Body<'tcx>, rvalue: &Rvalue<'tcx>, aggregate_kind: &AggregateKind<'tcx>, operands: &[Operand<'tcx>], location: Location, ) { let tcx = self.tcx(); self.prove_aggregate_predicates(aggregate_kind, location); if *aggregate_kind == AggregateKind::Tuple { // tuple rvalue field type is always the type of the op. Nothing to check here. return; } for (i, operand) in operands.iter().enumerate() { let field_ty = match self.aggregate_field_ty(aggregate_kind, i, location) { Ok(field_ty) => field_ty, Err(FieldAccessError::OutOfRange { field_count }) => { span_mirbug!( self, rvalue, "accessed field #{} but variant only has {}", i, field_count ); continue; } }; let operand_ty = operand.ty(body, tcx); let operand_ty = self.normalize(operand_ty, location); if let Err(terr) = self.sub_types( operand_ty, field_ty, location.to_locations(), ConstraintCategory::Boring, ) { span_mirbug!( self, rvalue, "{:?} is not a subtype of {:?}: {:?}", operand_ty, field_ty, terr ); } } } /// Adds the constraints that arise from a borrow expression `&'a P` at the location `L`. /// /// # Parameters /// /// - `location`: the location `L` where the borrow expression occurs /// - `borrow_region`: the region `'a` associated with the borrow /// - `borrowed_place`: the place `P` being borrowed fn add_reborrow_constraint( &mut self, body: &Body<'tcx>, location: Location, borrow_region: ty::Region<'tcx>, borrowed_place: &Place<'tcx>, ) { // These constraints are only meaningful during borrowck: let BorrowCheckContext { borrow_set, location_table, all_facts, constraints, .. } = self.borrowck_context; // In Polonius mode, we also push a `loan_issued_at` fact // linking the loan to the region (in some cases, though, // there is no loan associated with this borrow expression -- // that occurs when we are borrowing an unsafe place, for // example). if let Some(all_facts) = all_facts { let _prof_timer = self.infcx.tcx.prof.generic_activity("polonius_fact_generation"); if let Some(borrow_index) = borrow_set.get_index_of(&location) { let region_vid = borrow_region.to_region_vid(); all_facts.loan_issued_at.push(( region_vid, borrow_index, location_table.mid_index(location), )); } } // If we are reborrowing the referent of another reference, we // need to add outlives relationships. In a case like `&mut // *p`, where the `p` has type `&'b mut Foo`, for example, we // need to ensure that `'b: 'a`. debug!( "add_reborrow_constraint({:?}, {:?}, {:?})", location, borrow_region, borrowed_place ); let mut cursor = borrowed_place.projection.as_ref(); let tcx = self.infcx.tcx; let field = path_utils::is_upvar_field_projection( tcx, &self.borrowck_context.upvars, borrowed_place.as_ref(), body, ); let category = if let Some(field) = field { ConstraintCategory::ClosureUpvar(field) } else { ConstraintCategory::Boring }; while let [proj_base @ .., elem] = cursor { cursor = proj_base; debug!("add_reborrow_constraint - iteration {:?}", elem); match elem { ProjectionElem::Deref => { let base_ty = Place::ty_from(borrowed_place.local, proj_base, body, tcx).ty; debug!("add_reborrow_constraint - base_ty = {:?}", base_ty); match base_ty.kind() { ty::Ref(ref_region, _, mutbl) => { constraints.outlives_constraints.push(OutlivesConstraint { sup: ref_region.to_region_vid(), sub: borrow_region.to_region_vid(), locations: location.to_locations(), span: location.to_locations().span(body), category, variance_info: ty::VarianceDiagInfo::default(), from_closure: false, }); match mutbl { hir::Mutability::Not => { // Immutable reference. We don't need the base // to be valid for the entire lifetime of // the borrow. break; } hir::Mutability::Mut => { // Mutable reference. We *do* need the base // to be valid, because after the base becomes // invalid, someone else can use our mutable deref. // This is in order to make the following function // illegal: // ``` // fn unsafe_deref<'a, 'b>(x: &'a &'b mut T) -> &'b mut T { // &mut *x // } // ``` // // As otherwise you could clone `&mut T` using the // following function: // ``` // fn bad(x: &mut T) -> (&mut T, &mut T) { // let my_clone = unsafe_deref(&'a x); // ENDREGION 'a; // (my_clone, x) // } // ``` } } } ty::RawPtr(..) => { // deref of raw pointer, guaranteed to be valid break; } ty::Adt(def, _) if def.is_box() => { // deref of `Box`, need the base to be valid - propagate } _ => bug!("unexpected deref ty {:?} in {:?}", base_ty, borrowed_place), } } ProjectionElem::Field(..) | ProjectionElem::Downcast(..) | ProjectionElem::OpaqueCast(..) | ProjectionElem::Index(..) | ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => { // other field access } } } } fn prove_aggregate_predicates( &mut self, aggregate_kind: &AggregateKind<'tcx>, location: Location, ) { let tcx = self.tcx(); debug!( "prove_aggregate_predicates(aggregate_kind={:?}, location={:?})", aggregate_kind, location ); let (def_id, instantiated_predicates) = match *aggregate_kind { AggregateKind::Adt(adt_did, _, substs, _, _) => { (adt_did, tcx.predicates_of(adt_did).instantiate(tcx, substs)) } // For closures, we have some **extra requirements** we // have to check. In particular, in their upvars and // signatures, closures often reference various regions // from the surrounding function -- we call those the // closure's free regions. When we borrow-check (and hence // region-check) closures, we may find that the closure // requires certain relationships between those free // regions. However, because those free regions refer to // portions of the CFG of their caller, the closure is not // in a position to verify those relationships. In that // case, the requirements get "propagated" to us, and so // we have to solve them here where we instantiate the // closure. // // Despite the opacity of the previous paragraph, this is // actually relatively easy to understand in terms of the // desugaring. A closure gets desugared to a struct, and // these extra requirements are basically like where // clauses on the struct. AggregateKind::Closure(def_id, substs) | AggregateKind::Generator(def_id, substs, _) => { (def_id.to_def_id(), self.prove_closure_bounds(tcx, def_id, substs, location)) } AggregateKind::Array(_) | AggregateKind::Tuple => { (CRATE_DEF_ID.to_def_id(), ty::InstantiatedPredicates::empty()) } }; self.normalize_and_prove_instantiated_predicates( def_id, instantiated_predicates, location.to_locations(), ); } fn prove_closure_bounds( &mut self, tcx: TyCtxt<'tcx>, def_id: LocalDefId, substs: SubstsRef<'tcx>, location: Location, ) -> ty::InstantiatedPredicates<'tcx> { if let Some(closure_requirements) = &tcx.mir_borrowck(def_id).closure_requirements { constraint_conversion::ConstraintConversion::new( self.infcx, self.borrowck_context.universal_regions, self.region_bound_pairs, self.implicit_region_bound, self.param_env, location.to_locations(), DUMMY_SP, // irrelevant; will be overrided. ConstraintCategory::Boring, // same as above. &mut self.borrowck_context.constraints, ) .apply_closure_requirements( &closure_requirements, def_id.to_def_id(), substs, ); } // Now equate closure substs to regions inherited from `typeck_root_def_id`. Fixes #98589. let typeck_root_def_id = tcx.typeck_root_def_id(self.body.source.def_id()); let typeck_root_substs = ty::InternalSubsts::identity_for_item(tcx, typeck_root_def_id); let parent_substs = match tcx.def_kind(def_id) { DefKind::Closure => substs.as_closure().parent_substs(), DefKind::Generator => substs.as_generator().parent_substs(), DefKind::InlineConst => substs.as_inline_const().parent_substs(), other => bug!("unexpected item {:?}", other), }; let parent_substs = tcx.mk_substs(parent_substs.iter()); assert_eq!(typeck_root_substs.len(), parent_substs.len()); if let Err(_) = self.eq_substs( typeck_root_substs, parent_substs, location.to_locations(), ConstraintCategory::BoringNoLocation, ) { span_mirbug!( self, def_id, "could not relate closure to parent {:?} != {:?}", typeck_root_substs, parent_substs ); } tcx.predicates_of(def_id).instantiate(tcx, substs) } #[instrument(skip(self, body), level = "debug")] fn typeck_mir(&mut self, body: &Body<'tcx>) { self.last_span = body.span; debug!(?body.span); for (local, local_decl) in body.local_decls.iter_enumerated() { self.check_local(&body, local, local_decl); } for (block, block_data) in body.basic_blocks.iter_enumerated() { let mut location = Location { block, statement_index: 0 }; for stmt in &block_data.statements { if !stmt.source_info.span.is_dummy() { self.last_span = stmt.source_info.span; } self.check_stmt(body, stmt, location); location.statement_index += 1; } self.check_terminator(&body, block_data.terminator(), location); self.check_iscleanup(&body, block_data); } } } trait NormalizeLocation: fmt::Debug + Copy { fn to_locations(self) -> Locations; } impl NormalizeLocation for Locations { fn to_locations(self) -> Locations { self } } impl NormalizeLocation for Location { fn to_locations(self) -> Locations { Locations::Single(self) } } /// Runs `infcx.instantiate_opaque_types`. Unlike other `TypeOp`s, /// this is not canonicalized - it directly affects the main `InferCtxt` /// that we use during MIR borrowchecking. #[derive(Debug)] pub(super) struct InstantiateOpaqueType<'tcx> { pub base_universe: Option, pub region_constraints: Option>, pub obligations: Vec>, } impl<'tcx> TypeOp<'tcx> for InstantiateOpaqueType<'tcx> { type Output = (); /// We use this type itself to store the information used /// when reporting errors. Since this is not a query, we don't /// re-run anything during error reporting - we just use the information /// we saved to help extract an error from the already-existing region /// constraints in our `InferCtxt` type ErrorInfo = InstantiateOpaqueType<'tcx>; fn fully_perform(mut self, infcx: &InferCtxt<'tcx>) -> Fallible> { let (mut output, region_constraints) = scrape_region_constraints(infcx, || { Ok(InferOk { value: (), obligations: self.obligations.clone() }) })?; self.region_constraints = Some(region_constraints); output.error_info = Some(self); Ok(output) } }