//! 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 rustc_data_structures::frozen::Frozen; use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_errors::struct_span_err; use rustc_hir as hir; use rustc_hir::def_id::{DefId, LocalDefId}; use rustc_hir::lang_items::{CoerceUnsizedTraitLangItem, CopyTraitLangItem, SizedTraitLangItem}; use rustc_index::vec::{Idx, IndexVec}; use rustc_infer::infer::canonical::QueryRegionConstraints; use rustc_infer::infer::outlives::env::RegionBoundPairs; use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; use rustc_infer::infer::{ InferCtxt, InferOk, 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::fold::TypeFoldable; use rustc_middle::ty::subst::{GenericArgKind, Subst, SubstsRef, UserSubsts}; use rustc_middle::ty::{ self, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, RegionVid, ToPredicate, Ty, TyCtxt, UserType, UserTypeAnnotationIndex, WithConstness, }; use rustc_span::{Span, DUMMY_SP}; use rustc_target::abi::VariantIdx; use rustc_trait_selection::infer::InferCtxtExt as _; use rustc_trait_selection::opaque_types::{GenerateMemberConstraints, InferCtxtExt}; use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _; use rustc_trait_selection::traits::query::type_op; use rustc_trait_selection::traits::query::type_op::custom::CustomTypeOp; use rustc_trait_selection::traits::query::{Fallible, NoSolution}; use rustc_trait_selection::traits::{self, ObligationCause, PredicateObligations}; use crate::dataflow::impls::MaybeInitializedPlaces; use crate::dataflow::move_paths::MoveData; use crate::dataflow::ResultsCursor; use crate::transform::{ check_consts::ConstCx, promote_consts::should_suggest_const_in_array_repeat_expressions_attribute, }; use crate::borrow_check::{ borrow_set::BorrowSet, constraints::{OutlivesConstraint, OutlivesConstraintSet}, facts::AllFacts, location::LocationTable, member_constraints::MemberConstraintSet, nll::ToRegionVid, path_utils, region_infer::values::{ LivenessValues, PlaceholderIndex, PlaceholderIndices, RegionValueElements, }, region_infer::{ClosureRegionRequirementsExt, TypeTest}, renumber, type_check::free_region_relations::{CreateResult, UniversalRegionRelations}, universal_regions::{DefiningTy, UniversalRegions}, Upvar, }; macro_rules! span_mirbug { ($context:expr, $elem:expr, $($message:tt)*) => ({ $crate::borrow_check::type_check::mirbug( $context.tcx(), $context.last_span, &format!( "broken MIR in {:?} ({:?}): {}", $context.mir_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 constraint_conversion; pub mod free_region_relations; mod input_output; 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 is 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` /// - `mir_def_id` -- `LocalDefId` from which the MIR is derived /// - `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>, mir_def_id: LocalDefId, 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], ) -> 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(), closure_bounds_mapping: Default::default(), type_tests: Vec::default(), }; let CreateResult { universal_region_relations, region_bound_pairs, normalized_inputs_and_output, } = free_region_relations::create( infcx, param_env, Some(implicit_region_bound), universal_regions, &mut constraints, ); let mut borrowck_context = BorrowCheckContext { universal_regions, location_table, borrow_set, all_facts, constraints: &mut constraints, upvars, }; let opaque_type_values = type_check_internal( infcx, mir_def_id, param_env, body, promoted, ®ion_bound_pairs, implicit_region_bound, &mut borrowck_context, &universal_region_relations, |mut cx| { cx.equate_inputs_and_outputs(&body, universal_regions, &normalized_inputs_and_output); liveness::generate(&mut cx, body, elements, flow_inits, move_data, location_table); translate_outlives_facts(&mut cx); cx.opaque_type_values }, ); MirTypeckResults { constraints, universal_region_relations, opaque_type_values } } fn type_check_internal<'a, 'tcx, R>( infcx: &'a InferCtxt<'a, 'tcx>, mir_def_id: LocalDefId, param_env: ty::ParamEnv<'tcx>, body: &'a Body<'tcx>, promoted: &'a IndexVec>, region_bound_pairs: &'a RegionBoundPairs<'tcx>, implicit_region_bound: ty::Region<'tcx>, borrowck_context: &'a mut BorrowCheckContext<'a, 'tcx>, universal_region_relations: &'a UniversalRegionRelations<'tcx>, extra: impl FnOnce(TypeChecker<'a, 'tcx>) -> R, ) -> R { let mut checker = TypeChecker::new( infcx, body, mir_def_id, param_env, region_bound_pairs, implicit_region_bound, borrowck_context, universal_region_relations, ); let errors_reported = { let mut verifier = TypeVerifier::new(&mut checker, body, 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); } extra(checker) } 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.outlives.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)), ) } }, )); } } 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>, body: &'b Body<'tcx>, promoted: &'b IndexVec>, last_span: Span, mir_def_id: LocalDefId, 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) { 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); }); 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![] }, location.to_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(); if let ty::ConstKind::Unevaluated(def, substs, promoted) = constant.literal.val { if let Some(promoted) = promoted { let check_err = |verifier: &mut TypeVerifier<'a, 'b, 'tcx>, promoted: &Body<'tcx>, ty, san_ty| { if let Err(terr) = verifier.cx.eq_types( san_ty, ty, location.to_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 { if let Err(terr) = self.cx.fully_perform_op( location.to_locations(), ConstraintCategory::Boring, self.cx.param_env.and(type_op::ascribe_user_type::AscribeUserType::new( constant.literal.ty, def.did, UserSubsts { substs, user_self_ty: None }, )), ) { span_mirbug!( self, constant, "bad constant type {:?} ({:?})", constant, terr ); } } } else if let Some(static_def_id) = constant.check_static_ptr(tcx) { let unnormalized_ty = tcx.type_of(static_def_id); let locations = location.to_locations(); 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( normalized_ty, literal_ty, locations, ConstraintCategory::Boring, ) { span_mirbug!(self, constant, "bad static type {:?} ({:?})", constant, terr); } } if let ty::FnDef(def_id, substs) = constant.literal.ty.kind { let instantiated_predicates = tcx.predicates_of(def_id).instantiate(tcx, substs); self.cx.normalize_and_prove_instantiated_predicates( instantiated_predicates, location.to_locations(), ); } } } 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>, body: &'b Body<'tcx>, promoted: &'b IndexVec>, ) -> Self { TypeVerifier { body, promoted, mir_def_id: cx.mir_def_id, cx, last_span: body.span, errors_reported: false, } } 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 = ty::TraitRef { def_id: tcx.require_lang_item(CopyTraitLangItem, Some(self.last_span)), substs: tcx.mk_substs_trait(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.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 closure_bounds = 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.closure_bounds_mapping, &mut closure_bounds, ); 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.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 live_region in liveness_constraints.rows() { self.cx .borrowck_context .constraints .liveness_constraints .add_element(live_region, location); } if !closure_bounds.is_empty() { let combined_bounds_mapping = closure_bounds.into_iter().flat_map(|(_, value)| value).collect(); let existing = self .cx .borrowck_context .constraints .closure_bounds_mapping .insert(location, combined_bounds_mapping); assert!(existing.is_none(), "Multiple promoteds/closures at the same 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) as u64) } 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); 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) } } } 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.variants[variant_index], substs), ty::Generator(def_id, substs, _) => { let mut variants = substs.as_generator().state_tys(def_id, tcx); let mut variant = match variants.nth(variant_index.into()) { Some(v) => v, None => 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.variants[VariantIdx::new(0)], substs) } ty::Closure(_, substs) => { return 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(), }), }; } 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.expect_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<'a, '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>, mir_def_id: LocalDefId, 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>, universal_region_relations: &'a UniversalRegionRelations<'tcx>, opaque_type_values: FxHashMap>, } struct BorrowCheckContext<'a, 'tcx> { universal_regions: &'a UniversalRegions<'tcx>, location_table: &'a LocationTable, all_facts: &'a mut Option, borrow_set: &'a BorrowSet<'tcx>, constraints: &'a mut MirTypeckRegionConstraints<'tcx>, upvars: &'a [Upvar], } crate struct MirTypeckResults<'tcx> { crate constraints: MirTypeckRegionConstraints<'tcx>, pub(in crate::borrow_check) universal_region_relations: Frozen>, crate opaque_type_values: FxHashMap>, } /// A collection of region constraints that must be satisfied for the /// program to be considered well-typed. 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. 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`. 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. crate liveness_constraints: LivenessValues, crate outlives_constraints: OutlivesConstraintSet, crate member_constraints: MemberConstraintSet<'tcx, RegionVid>, crate closure_bounds_mapping: FxHashMap>, crate type_tests: Vec>, } impl 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: /// /// ``` /// 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<'a, 'tcx>, body: &'a Body<'tcx>, mir_def_id: LocalDefId, param_env: ty::ParamEnv<'tcx>, region_bound_pairs: &'a RegionBoundPairs<'tcx>, implicit_region_bound: ty::Region<'tcx>, borrowck_context: &'a mut BorrowCheckContext<'a, 'tcx>, universal_region_relations: &'a UniversalRegionRelations<'tcx>, ) -> Self { let mut checker = Self { infcx, last_span: DUMMY_SP, mir_def_id, body, user_type_annotations: &body.user_type_annotations, param_env, region_bound_pairs, implicit_region_bound, borrowck_context, reported_errors: Default::default(), universal_region_relations, opaque_type_values: FxHashMap::default(), }; checker.check_user_type_annotations(); checker } /// Equate the inferred type and the annotated type for user type annotations fn check_user_type_annotations(&mut self) { debug!( "check_user_type_annotations: user_type_annotations={:?}", 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.infcx.instantiate_canonical_with_fresh_inference_vars(span, user_ty); match annotation { UserType::Ty(mut ty) => { ty = self.normalize(ty, Locations::All(span)); if let Err(terr) = self.eq_types( ty, inferred_ty, Locations::All(span), ConstraintCategory::BoringNoLocation, ) { span_mirbug!( self, user_annotation, "bad user type ({:?} = {:?}): {:?}", ty, inferred_ty, terr ); } self.prove_predicate( ty::PredicateAtom::WellFormed(inferred_ty.into()).to_predicate(self.tcx()), Locations::All(span), ConstraintCategory::TypeAnnotation, ); } UserType::TypeOf(def_id, user_substs) => { if let Err(terr) = self.fully_perform_op( Locations::All(span), ConstraintCategory::BoringNoLocation, self.param_env.and(type_op::ascribe_user_type::AscribeUserType::new( inferred_ty, def_id, user_substs, )), ) { span_mirbug!( self, user_annotation, "bad user type AscribeUserType({:?}, {:?} {:?}): {:?}", inferred_ty, def_id, user_substs, terr ); } } } } } /// Given some operation `op` that manipulates types, proves /// predicates, or otherwise uses the inference context, executes /// `op` and then executes all the further obligations that `op` /// returns. This will yield a set of outlives constraints amongst /// regions which are extracted and stored as having occurred at /// `locations`. /// /// **Any `rustc_infer::infer` operations that might generate region /// constraints should occur within this method so that those /// constraints can be properly localized!** fn fully_perform_op( &mut self, locations: Locations, category: ConstraintCategory, op: impl type_op::TypeOp<'tcx, Output = R>, ) -> Fallible { let (r, opt_data) = op.fully_perform(self.infcx)?; if let Some(data) = &opt_data { self.push_region_constraints(locations, category, data); } Ok(r) } fn push_region_constraints( &mut self, locations: Locations, category: ConstraintCategory, data: &QueryRegionConstraints<'tcx>, ) { debug!("push_region_constraints: constraints generated at {:?} are {:#?}", locations, data); constraint_conversion::ConstraintConversion::new( self.infcx, self.borrowck_context.universal_regions, self.region_bound_pairs, Some(self.implicit_region_bound), self.param_env, locations, category, &mut self.borrowck_context.constraints, ) .convert_all(data); } /// Convenient wrapper around `relate_tys::relate_types` -- see /// that fn for docs. fn relate_types( &mut self, a: Ty<'tcx>, v: ty::Variance, b: Ty<'tcx>, locations: Locations, category: ConstraintCategory, ) -> Fallible<()> { relate_tys::relate_types( self.infcx, a, v, b, locations, category, Some(self.borrowck_context), ) } fn sub_types( &mut self, sub: Ty<'tcx>, sup: Ty<'tcx>, locations: Locations, category: ConstraintCategory, ) -> Fallible<()> { self.relate_types(sub, ty::Variance::Covariant, sup, locations, category) } /// Try to relate `sub <: sup`; if this fails, instantiate opaque /// variables in `sub` with their inferred definitions and try /// again. This is used for opaque types in places (e.g., `let x: /// impl Foo = ..`). fn sub_types_or_anon( &mut self, sub: Ty<'tcx>, sup: Ty<'tcx>, locations: Locations, category: ConstraintCategory, ) -> Fallible<()> { if let Err(terr) = self.sub_types(sub, sup, locations, category) { if let ty::Opaque(..) = sup.kind { // When you have `let x: impl Foo = ...` in a closure, // the resulting inferend values are stored with the // def-id of the base function. let parent_def_id = self.tcx().closure_base_def_id(self.mir_def_id.to_def_id()).expect_local(); return self.eq_opaque_type_and_type(sub, sup, parent_def_id, locations, category); } else { return Err(terr); } } Ok(()) } fn eq_types( &mut self, a: Ty<'tcx>, b: Ty<'tcx>, locations: Locations, category: ConstraintCategory, ) -> Fallible<()> { self.relate_types(a, ty::Variance::Invariant, b, locations, category) } fn relate_type_and_user_type( &mut self, a: Ty<'tcx>, v: ty::Variance, user_ty: &UserTypeProjection, locations: Locations, category: ConstraintCategory, ) -> Fallible<()> { debug!( "relate_type_and_user_type(a={:?}, v={:?}, user_ty={:?}, locations={:?})", a, v, user_ty, locations, ); let annotated_type = self.user_type_annotations[user_ty.base].inferred_ty; let mut curr_projected_ty = PlaceTy::from_ty(annotated_type); let tcx = self.infcx.tcx; for proj in &user_ty.projs { 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) }, ); curr_projected_ty = projected_ty; } debug!( "user_ty base: {:?} freshened: {:?} projs: {:?} yields: {:?}", user_ty.base, annotated_type, user_ty.projs, curr_projected_ty ); let ty = curr_projected_ty.ty; self.relate_types(a, v, ty, locations, category)?; Ok(()) } fn eq_opaque_type_and_type( &mut self, revealed_ty: Ty<'tcx>, anon_ty: Ty<'tcx>, anon_owner_def_id: LocalDefId, locations: Locations, category: ConstraintCategory, ) -> Fallible<()> { debug!( "eq_opaque_type_and_type( \ revealed_ty={:?}, \ anon_ty={:?})", revealed_ty, anon_ty ); // Fast path for the common case. if !anon_ty.has_opaque_types() { if let Err(terr) = self.eq_types(anon_ty, revealed_ty, locations, category) { span_mirbug!( self, locations, "eq_opaque_type_and_type: `{:?}=={:?}` failed with `{:?}`", revealed_ty, anon_ty, terr ); } return Ok(()); } let infcx = self.infcx; let tcx = infcx.tcx; let param_env = self.param_env; let body = self.body; let concrete_opaque_types = &tcx.typeck(anon_owner_def_id).concrete_opaque_types; let mut opaque_type_values = Vec::new(); debug!("eq_opaque_type_and_type: mir_def_id={:?}", self.mir_def_id); let opaque_type_map = self.fully_perform_op( locations, category, CustomTypeOp::new( |infcx| { let mut obligations = ObligationAccumulator::default(); let dummy_body_id = hir::CRATE_HIR_ID; let (output_ty, opaque_type_map) = obligations.add(infcx.instantiate_opaque_types( anon_owner_def_id, dummy_body_id, param_env, &anon_ty, locations.span(body), )); debug!( "eq_opaque_type_and_type: \ instantiated output_ty={:?} \ opaque_type_map={:#?} \ revealed_ty={:?}", output_ty, opaque_type_map, revealed_ty ); // Make sure that the inferred types are well-formed. I'm // not entirely sure this is needed (the HIR type check // didn't do this) but it seems sensible to prevent opaque // types hiding ill-formed types. obligations.obligations.push(traits::Obligation::new( ObligationCause::dummy(), param_env, ty::PredicateAtom::WellFormed(revealed_ty.into()).to_predicate(infcx.tcx), )); obligations.add( infcx .at(&ObligationCause::dummy(), param_env) .eq(output_ty, revealed_ty)?, ); for (&opaque_def_id, opaque_decl) in &opaque_type_map { let resolved_ty = infcx.resolve_vars_if_possible(&opaque_decl.concrete_ty); let concrete_is_opaque = if let ty::Opaque(def_id, _) = resolved_ty.kind { def_id == opaque_def_id } else { false }; let opaque_defn_ty = match concrete_opaque_types.get(&opaque_def_id) { None => { if !concrete_is_opaque { tcx.sess.delay_span_bug( body.span, &format!( "Non-defining use of {:?} with revealed type", opaque_def_id, ), ); } continue; } Some(opaque_defn_ty) => opaque_defn_ty, }; debug!("opaque_defn_ty = {:?}", opaque_defn_ty); let subst_opaque_defn_ty = opaque_defn_ty.concrete_type.subst(tcx, opaque_decl.substs); let renumbered_opaque_defn_ty = renumber::renumber_regions(infcx, &subst_opaque_defn_ty); debug!( "eq_opaque_type_and_type: concrete_ty={:?}={:?} opaque_defn_ty={:?}", opaque_decl.concrete_ty, resolved_ty, renumbered_opaque_defn_ty, ); if !concrete_is_opaque { // Equate concrete_ty (an inference variable) with // the renumbered type from typeck. obligations.add( infcx .at(&ObligationCause::dummy(), param_env) .eq(opaque_decl.concrete_ty, renumbered_opaque_defn_ty)?, ); opaque_type_values.push(( opaque_def_id, ty::ResolvedOpaqueTy { concrete_type: renumbered_opaque_defn_ty, substs: opaque_decl.substs, }, )); } else { // We're using an opaque `impl Trait` type without // 'revealing' it. For example, code like this: // // type Foo = impl Debug; // fn foo1() -> Foo { ... } // fn foo2() -> Foo { foo1() } // // In `foo2`, we're not revealing the type of `Foo` - we're // just treating it as the opaque type. // // When this occurs, we do *not* want to try to equate // the concrete type with the underlying defining type // of the opaque type - this will always fail, since // the defining type of an opaque type is always // some other type (e.g. not itself) // Essentially, none of the normal obligations apply here - // we're just passing around some unknown opaque type, // without actually looking at the underlying type it // gets 'revealed' into debug!( "eq_opaque_type_and_type: non-defining use of {:?}", opaque_def_id, ); } } debug!("eq_opaque_type_and_type: equated"); Ok(InferOk { value: Some(opaque_type_map), obligations: obligations.into_vec(), }) }, || "input_output".to_string(), ), )?; self.opaque_type_values.extend(opaque_type_values); let universal_region_relations = self.universal_region_relations; // Finally, if we instantiated the anon types successfully, we // have to solve any bounds (e.g., `-> impl Iterator` needs to // prove that `T: Iterator` where `T` is the type we // instantiated it with). if let Some(opaque_type_map) = opaque_type_map { for (opaque_def_id, opaque_decl) in opaque_type_map { self.fully_perform_op( locations, ConstraintCategory::OpaqueType, CustomTypeOp::new( |_cx| { infcx.constrain_opaque_type( opaque_def_id, &opaque_decl, GenerateMemberConstraints::IfNoStaticBound, universal_region_relations, ); Ok(InferOk { value: (), obligations: vec![] }) }, || "opaque_type_map".to_string(), ), )?; } } Ok(()) } fn tcx(&self) -> TyCtxt<'tcx> { self.infcx.tcx } fn check_stmt(&mut self, body: &Body<'tcx>, stmt: &Statement<'tcx>, location: Location) { debug!("check_stmt: {:?}", stmt); let tcx = self.tcx(); match stmt.kind { StatementKind::Assign(box (ref place, ref 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) => { if let BorrowCheckContext { universal_regions: UniversalRegions { defining_ty: DefiningTy::Const(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 place_ty = place.ty(body, tcx).ty; let place_ty = self.normalize(place_ty, location); let rv_ty = rv.ty(body, tcx); let rv_ty = self.normalize(rv_ty, location); if let Err(terr) = self.sub_types_or_anon(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.tcx().features().unsized_locals { let trait_ref = ty::TraitRef { def_id: tcx.require_lang_item(SizedTraitLangItem, Some(self.last_span)), substs: tcx.mk_substs_trait(place_ty, &[]), }; self.prove_trait_ref( trait_ref, location.to_locations(), ConstraintCategory::SizedBound, ); } } StatementKind::SetDiscriminant { ref place, variant_index } => { let place_type = place.ty(body, tcx).ty; let adt = match place_type.kind { ty::Adt(adt, _) if adt.is_enum() => adt, _ => { span_bug!( stmt.source_info.span, "bad set discriminant ({:?} = {:?}): lhs is not an enum", place, variant_index ); } }; if variant_index.as_usize() >= adt.variants.len() { span_bug!( stmt.source_info.span, "bad set discriminant ({:?} = {:?}): value of of range", place, variant_index ); }; } StatementKind::AscribeUserType(box (ref place, ref 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::FakeRead(..) | StatementKind::StorageLive(..) | StatementKind::StorageDead(..) | StatementKind::LlvmInlineAsm { .. } | StatementKind::Retag { .. } | StatementKind::Coverage(..) | StatementKind::Nop => {} } } fn check_terminator( &mut self, body: &Body<'tcx>, term: &Terminator<'tcx>, term_location: Location, ) { debug!("check_terminator: {:?}", term); let tcx = self.tcx(); 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 { ref place, ref 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 { ref discr, switch_ty, .. } => { let discr_ty = discr.ty(body, tcx); if let Err(terr) = self.sub_types( discr_ty, switch_ty, term_location.to_locations(), ConstraintCategory::Assignment, ) { span_mirbug!( self, term, "bad SwitchInt ({:?} on {:?}): {:?}", switch_ty, discr_ty, terr ); } 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 { ref func, ref args, ref destination, from_hir_call, .. } => { let func_ty = func.ty(body, tcx); debug!("check_terminator: call, func_ty={:?}", func_ty); 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) = self.infcx.replace_bound_vars_with_fresh_vars( term.source_info.span, LateBoundRegionConversionTime::FnCall, &sig, ); let sig = self.normalize(sig, term_location); self.check_call_dest(body, term, &sig, destination, term_location); self.prove_predicates( sig.inputs_and_output.iter().map(|ty| ty::PredicateAtom::WellFormed(ty.into())), term_location.to_locations(), ConstraintCategory::Boring, ); // 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 { ref cond, ref msg, .. } => { 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 { ref len, ref 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 { ref value, .. } => { 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: &Option<(Place<'tcx>, BasicBlock)>, term_location: Location, ) { let tcx = self.tcx(); match *destination { Some((ref dest, _target_block)) => { let dest_ty = dest.ty(body, tcx).ty; let dest_ty = self.normalize(dest_ty, term_location); let category = match dest.as_local() { Some(RETURN_PLACE) => { if let BorrowCheckContext { universal_regions: UniversalRegions { defining_ty: DefiningTy::Const(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_or_anon(sig.output(), dest_ty, locations, category) { span_mirbug!( self, term, "call dest mismatch ({:?} <- {:?}): {:?}", dest_ty, sig.output(), terr ); } // When `#![feature(unsized_locals)]` is not enabled, // this check is done at `check_local`. if self.tcx().features().unsized_locals { let span = term.source_info.span; self.ensure_place_sized(dest_ty, span); } } None => { if !sig.output().conservative_is_privately_uninhabited(self.tcx()) { 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); } for (n, (fn_arg, op_arg)) in sig.inputs().iter().zip(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 } 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 { 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 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); } } 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 { ref destination, .. } => { if let &Some(target) = destination { self.assert_iscleanup(body, block_data, target, is_cleanup); } } } } 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 `#![feature(unsized_locals)]` is enabled, only function calls // and nullary ops are checked in `check_call_dest`. if !self.tcx().features().unsized_locals { 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.at(span), 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() { let mut diag = struct_span_err!( self.tcx().sess, span, E0161, "cannot move a value of type {0}: the size of {0} \ cannot be statically determined", ty ); // 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 certain cases: // * operand of a box expression // * callee in a call expression diag.emit(); } } } fn aggregate_field_ty( &mut self, ak: &AggregateKind<'tcx>, field_index: usize, location: Location, ) -> Result, FieldAccessError> { let tcx = self.tcx(); match *ak { AggregateKind::Adt(def, variant_index, substs, _, active_field_index) => { let variant = &def.variants[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_rvalue(&mut self, body: &Body<'tcx>, rvalue: &Rvalue<'tcx>, location: Location) { let tcx = self.tcx(); match rvalue { Rvalue::Aggregate(ak, ops) => { self.check_aggregate_rvalue(&body, rvalue, ak, ops, location) } Rvalue::Repeat(operand, len) => { // 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) { if let Operand::Move(_) = operand { // While this is located in `nll::typeck` this error is not an NLL error, it's // a required check to make sure that repeated elements implement `Copy`. let span = body.source_info(location).span; let ty = operand.ty(body, tcx); if !self.infcx.type_is_copy_modulo_regions(self.param_env, ty, span) { let ccx = ConstCx::new_with_param_env( tcx, self.mir_def_id, body, self.param_env, ); // To determine if `const_in_array_repeat_expressions` feature gate should // be mentioned, need to check if the rvalue is promotable. let should_suggest = should_suggest_const_in_array_repeat_expressions_attribute( &ccx, operand, ); debug!("check_rvalue: should_suggest={:?}", should_suggest); self.infcx.report_selection_error( &traits::Obligation::new( ObligationCause::new( span, self.tcx().hir().local_def_id_to_hir_id(self.mir_def_id), traits::ObligationCauseCode::RepeatVec(should_suggest), ), self.param_env, ty::Binder::bind(ty::TraitRef::new( self.tcx().require_lang_item( CopyTraitLangItem, Some(self.last_span), ), tcx.mk_substs_trait(ty, &[]), )) .without_const() .to_predicate(self.tcx()), ), &traits::SelectionError::Unimplemented, false, false, ); } } } } Rvalue::NullaryOp(_, ty) => { // Even with unsized locals cannot box an unsized value. if self.tcx().features().unsized_locals { let span = body.source_info(location).span; self.ensure_place_sized(ty, span); } let trait_ref = ty::TraitRef { def_id: tcx.require_lang_item(SizedTraitLangItem, Some(self.last_span)), substs: tcx.mk_substs_trait(ty, &[]), }; self.prove_trait_ref( trait_ref, location.to_locations(), ConstraintCategory::SizedBound, ); } Rvalue::Cast(cast_kind, op, ty) => { 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_fn_ptr_from, ty, 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_fn_ptr_from, ty, 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_fn_ptr_from, ty, 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 = ty::TraitRef { def_id: tcx.require_lang_item( CoerceUnsizedTraitLangItem, Some(self.last_span), ), substs: tcx.mk_substs_trait(op.ty(body, tcx), &[ty.into()]), }; self.prove_trait_ref( trait_ref, location.to_locations(), ConstraintCategory::Cast, ); } CastKind::Pointer(PointerCast::MutToConstPointer) => { let ty_from = match op.ty(body, tcx).kind { ty::RawPtr(ty::TypeAndMut { ty: ty_from, mutbl: hir::Mutability::Mut, }) => ty_from, _ => { span_mirbug!( self, rvalue, "unexpected base type for cast {:?}", ty, ); return; } }; let ty_to = match ty.kind { ty::RawPtr(ty::TypeAndMut { ty: ty_to, mutbl: hir::Mutability::Not, }) => ty_to, _ => { 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 = match ty_from.kind { ty::RawPtr(ty::TypeAndMut { mutbl: hir::Mutability::Not, ty: array_ty, }) => match array_ty.kind { ty::Array(ty_elem, _) => Some(ty_elem), _ => None, }, _ => None, }; let ty_elem = match opt_ty_elem { Some(ty_elem) => ty_elem, None => { span_mirbug!( self, rvalue, "ArrayToPointer cast from unexpected type {:?}", ty_from, ); return; } }; let ty_to = match ty.kind { ty::RawPtr(ty::TypeAndMut { mutbl: hir::Mutability::Not, ty: ty_to, }) => ty_to, _ => { span_mirbug!( self, rvalue, "ArrayToPointer cast to unexpected type {:?}", ty, ); 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::Misc => { 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) { (None, _) | (_, None | Some(CastTy::FnPtr)) | (Some(CastTy::Float), Some(CastTy::Ptr(_))) | (Some(CastTy::Ptr(_) | CastTy::FnPtr), Some(CastTy::Float)) => { span_mirbug!(self, rvalue, "Invalid cast {:?} -> {:?}", ty_from, ty,) } ( Some(CastTy::Int(_)), Some(CastTy::Int(_) | CastTy::Float | CastTy::Ptr(_)), ) | (Some(CastTy::Float), Some(CastTy::Int(_) | CastTy::Float)) | (Some(CastTy::Ptr(_)), Some(CastTy::Int(_) | CastTy::Ptr(_))) | (Some(CastTy::FnPtr), Some(CastTy::Int(_) | CastTy::Ptr(_))) => (), } } } } 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, left, right, ) => { 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.relate_types( common_ty, ty::Variance::Contravariant, ty_left, location.to_locations(), ConstraintCategory::Boring, ) .unwrap_or_else(|err| { bug!("Could not equate type variable with {:?}: {:?}", ty_left, err) }); if let Err(terr) = self.relate_types( common_ty, ty::Variance::Contravariant, ty_right, 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::AddressOf(..) | Rvalue::ThreadLocalRef(..) | Rvalue::Use(..) | Rvalue::Len(..) | Rvalue::BinaryOp(..) | Rvalue::CheckedBinaryOp(..) | Rvalue::UnaryOp(..) | 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::BinaryOp(..) | Rvalue::CheckedBinaryOp(..) | Rvalue::NullaryOp(..) | 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 `borrow_region` 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.borrow_region.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(self.borrowck_context.upvars[field.index()].var_hir_id) } 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(), category, }); 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::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 instantiated_predicates = match aggregate_kind { AggregateKind::Adt(def, _, substs, _, _) => { tcx.predicates_of(def.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 parapgrah, 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, _) => { self.prove_closure_bounds(tcx, def_id.expect_local(), substs, location) } AggregateKind::Array(_) | AggregateKind::Tuple => ty::InstantiatedPredicates::empty(), }; self.normalize_and_prove_instantiated_predicates( 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(ref closure_region_requirements) = tcx.mir_borrowck(def_id).closure_requirements { let closure_constraints = QueryRegionConstraints { outlives: closure_region_requirements.apply_requirements( tcx, def_id.to_def_id(), substs, ), // Presently, closures never propagate member // constraints to their parents -- they are enforced // locally. This is largely a non-issue as member // constraints only come from `-> impl Trait` and // friends which don't appear (thus far...) in // closures. member_constraints: vec![], }; let bounds_mapping = closure_constraints .outlives .iter() .enumerate() .filter_map(|(idx, constraint)| { let ty::OutlivesPredicate(k1, r2) = constraint.no_bound_vars().unwrap_or_else(|| { bug!("query_constraint {:?} contained bound vars", constraint,); }); match k1.unpack() { GenericArgKind::Lifetime(r1) => { // constraint is r1: r2 let r1_vid = self.borrowck_context.universal_regions.to_region_vid(r1); let r2_vid = self.borrowck_context.universal_regions.to_region_vid(r2); let outlives_requirements = &closure_region_requirements.outlives_requirements[idx]; Some(( (r1_vid, r2_vid), (outlives_requirements.category, outlives_requirements.blame_span), )) } GenericArgKind::Type(_) | GenericArgKind::Const(_) => None, } }) .collect(); let existing = self .borrowck_context .constraints .closure_bounds_mapping .insert(location, bounds_mapping); assert!(existing.is_none(), "Multiple closures at the same location."); self.push_region_constraints( location.to_locations(), ConstraintCategory::ClosureBounds, &closure_constraints, ); } tcx.predicates_of(def_id).instantiate(tcx, substs) } fn prove_trait_ref( &mut self, trait_ref: ty::TraitRef<'tcx>, locations: Locations, category: ConstraintCategory, ) { self.prove_predicates( Some(ty::PredicateAtom::Trait( ty::TraitPredicate { trait_ref }, hir::Constness::NotConst, )), locations, category, ); } fn normalize_and_prove_instantiated_predicates( &mut self, instantiated_predicates: ty::InstantiatedPredicates<'tcx>, locations: Locations, ) { for predicate in instantiated_predicates.predicates { let predicate = self.normalize(predicate, locations); self.prove_predicate(predicate, locations, ConstraintCategory::Boring); } } fn prove_predicates( &mut self, predicates: impl IntoIterator>, locations: Locations, category: ConstraintCategory, ) { for predicate in predicates { let predicate = predicate.to_predicate(self.tcx()); debug!("prove_predicates(predicate={:?}, locations={:?})", predicate, locations,); self.prove_predicate(predicate, locations, category); } } fn prove_predicate( &mut self, predicate: ty::Predicate<'tcx>, locations: Locations, category: ConstraintCategory, ) { debug!("prove_predicate(predicate={:?}, location={:?})", predicate, locations,); let param_env = self.param_env; self.fully_perform_op( locations, category, param_env.and(type_op::prove_predicate::ProvePredicate::new(predicate)), ) .unwrap_or_else(|NoSolution| { span_mirbug!(self, NoSolution, "could not prove {:?}", predicate); }) } fn typeck_mir(&mut self, body: &Body<'tcx>) { self.last_span = body.span; debug!("run_on_mir: {:?}", 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); } } fn normalize(&mut self, value: T, location: impl NormalizeLocation) -> T where T: type_op::normalize::Normalizable<'tcx> + Copy + 'tcx, { debug!("normalize(value={:?}, location={:?})", value, location); let param_env = self.param_env; self.fully_perform_op( location.to_locations(), ConstraintCategory::Boring, param_env.and(type_op::normalize::Normalize::new(value)), ) .unwrap_or_else(|NoSolution| { span_mirbug!(self, NoSolution, "failed to normalize `{:?}`", value); value }) } } 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) } } #[derive(Debug, Default)] struct ObligationAccumulator<'tcx> { obligations: PredicateObligations<'tcx>, } impl<'tcx> ObligationAccumulator<'tcx> { fn add(&mut self, value: InferOk<'tcx, T>) -> T { let InferOk { value, obligations } = value; self.obligations.extend(obligations); value } fn into_vec(self) -> PredicateObligations<'tcx> { self.obligations } }