1 //! This pass type-checks the MIR to ensure it is not broken.
4 use std::{fmt, iter, mem};
8 use hir::OpaqueTyOrigin;
9 use rustc_data_structures::frozen::Frozen;
10 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
11 use rustc_data_structures::vec_map::VecMap;
12 use rustc_errors::struct_span_err;
14 use rustc_hir::def::DefKind;
15 use rustc_hir::def_id::LocalDefId;
16 use rustc_hir::lang_items::LangItem;
17 use rustc_index::vec::{Idx, IndexVec};
18 use rustc_infer::infer::canonical::QueryRegionConstraints;
19 use rustc_infer::infer::outlives::env::RegionBoundPairs;
20 use rustc_infer::infer::region_constraints::RegionConstraintData;
21 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
22 use rustc_infer::infer::{
23 InferCtxt, InferOk, LateBoundRegionConversionTime, NllRegionVariableOrigin,
25 use rustc_middle::mir::tcx::PlaceTy;
26 use rustc_middle::mir::visit::{NonMutatingUseContext, PlaceContext, Visitor};
27 use rustc_middle::mir::AssertKind;
28 use rustc_middle::mir::*;
29 use rustc_middle::ty::adjustment::PointerCast;
30 use rustc_middle::ty::cast::CastTy;
31 use rustc_middle::ty::fold::TypeFoldable;
32 use rustc_middle::ty::subst::{GenericArgKind, SubstsRef, UserSubsts};
33 use rustc_middle::ty::{
34 self, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, OpaqueHiddenType,
35 OpaqueTypeKey, RegionVid, ToPredicate, Ty, TyCtxt, UserType, UserTypeAnnotationIndex,
37 use rustc_span::def_id::CRATE_DEF_ID;
38 use rustc_span::{Span, DUMMY_SP};
39 use rustc_target::abi::VariantIdx;
40 use rustc_trait_selection::traits::query::type_op;
41 use rustc_trait_selection::traits::query::type_op::custom::scrape_region_constraints;
42 use rustc_trait_selection::traits::query::type_op::custom::CustomTypeOp;
43 use rustc_trait_selection::traits::query::type_op::{TypeOp, TypeOpOutput};
44 use rustc_trait_selection::traits::query::Fallible;
45 use rustc_trait_selection::traits::PredicateObligation;
47 use rustc_mir_dataflow::impls::MaybeInitializedPlaces;
48 use rustc_mir_dataflow::move_paths::MoveData;
49 use rustc_mir_dataflow::ResultsCursor;
52 borrow_set::BorrowSet,
53 constraints::{OutlivesConstraint, OutlivesConstraintSet},
54 diagnostics::UniverseInfo,
56 location::LocationTable,
57 member_constraints::MemberConstraintSet,
60 region_infer::values::{
61 LivenessValues, PlaceholderIndex, PlaceholderIndices, RegionValueElements,
63 region_infer::{ClosureRegionRequirementsExt, TypeTest},
64 type_check::free_region_relations::{CreateResult, UniversalRegionRelations},
65 universal_regions::{DefiningTy, UniversalRegions},
69 macro_rules! span_mirbug {
70 ($context:expr, $elem:expr, $($message:tt)*) => ({
71 $crate::type_check::mirbug(
75 "broken MIR in {:?} ({:?}): {}",
76 $context.body().source.def_id(),
78 format_args!($($message)*),
84 macro_rules! span_mirbug_and_err {
85 ($context:expr, $elem:expr, $($message:tt)*) => ({
87 span_mirbug!($context, $elem, $($message)*);
94 mod constraint_conversion;
95 pub mod free_region_relations;
97 pub(crate) mod liveness;
100 /// Type checks the given `mir` in the context of the inference
101 /// context `infcx`. Returns any region constraints that have yet to
102 /// be proven. This result includes liveness constraints that
103 /// ensure that regions appearing in the types of all local variables
104 /// are live at all points where that local variable may later be
107 /// This phase of type-check ought to be infallible -- this is because
108 /// the original, HIR-based type-check succeeded. So if any errors
109 /// occur here, we will get a `bug!` reported.
113 /// - `infcx` -- inference context to use
114 /// - `param_env` -- parameter environment to use for trait solving
115 /// - `body` -- MIR body to type-check
116 /// - `promoted` -- map of promoted constants within `body`
117 /// - `universal_regions` -- the universal regions from `body`s function signature
118 /// - `location_table` -- MIR location map of `body`
119 /// - `borrow_set` -- information about borrows occurring in `body`
120 /// - `all_facts` -- when using Polonius, this is the generated set of Polonius facts
121 /// - `flow_inits` -- results of a maybe-init dataflow analysis
122 /// - `move_data` -- move-data constructed when performing the maybe-init dataflow analysis
123 /// - `elements` -- MIR region map
124 pub(crate) fn type_check<'mir, 'tcx>(
125 infcx: &InferCtxt<'_, 'tcx>,
126 param_env: ty::ParamEnv<'tcx>,
128 promoted: &IndexVec<Promoted, Body<'tcx>>,
129 universal_regions: &Rc<UniversalRegions<'tcx>>,
130 location_table: &LocationTable,
131 borrow_set: &BorrowSet<'tcx>,
132 all_facts: &mut Option<AllFacts>,
133 flow_inits: &mut ResultsCursor<'mir, 'tcx, MaybeInitializedPlaces<'mir, 'tcx>>,
134 move_data: &MoveData<'tcx>,
135 elements: &Rc<RegionValueElements>,
136 upvars: &[Upvar<'tcx>],
138 ) -> MirTypeckResults<'tcx> {
139 let implicit_region_bound = infcx.tcx.mk_region(ty::ReVar(universal_regions.fr_fn_body));
140 let mut universe_causes = FxHashMap::default();
141 universe_causes.insert(ty::UniverseIndex::from_u32(0), UniverseInfo::other());
142 let mut constraints = MirTypeckRegionConstraints {
143 placeholder_indices: PlaceholderIndices::default(),
144 placeholder_index_to_region: IndexVec::default(),
145 liveness_constraints: LivenessValues::new(elements.clone()),
146 outlives_constraints: OutlivesConstraintSet::default(),
147 member_constraints: MemberConstraintSet::default(),
148 closure_bounds_mapping: Default::default(),
149 type_tests: Vec::default(),
154 universal_region_relations,
156 normalized_inputs_and_output,
157 } = free_region_relations::create(
160 Some(implicit_region_bound),
165 for u in ty::UniverseIndex::ROOT..infcx.universe() {
166 let info = UniverseInfo::other();
167 constraints.universe_causes.insert(u, info);
170 let mut borrowck_context = BorrowCheckContext {
175 constraints: &mut constraints,
179 let opaque_type_values = type_check_internal(
185 implicit_region_bound,
186 &mut borrowck_context,
188 cx.equate_inputs_and_outputs(&body, universal_regions, &normalized_inputs_and_output);
199 translate_outlives_facts(&mut cx);
200 let opaque_type_values =
201 infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
205 .map(|(opaque_type_key, decl)| {
207 Locations::All(body.span),
208 ConstraintCategory::OpaqueType,
211 infcx.register_member_constraints(
215 decl.hidden_type.span,
217 Ok(InferOk { value: (), obligations: vec![] })
219 || "opaque_type_map".to_string(),
223 let mut hidden_type = infcx.resolve_vars_if_possible(decl.hidden_type);
225 "finalized opaque type {:?} to {:#?}",
227 hidden_type.ty.kind()
229 if hidden_type.has_infer_types_or_consts() {
230 infcx.tcx.sess.delay_span_bug(
231 decl.hidden_type.span,
232 &format!("could not resolve {:#?}", hidden_type.ty.kind()),
234 hidden_type.ty = infcx.tcx.ty_error();
237 (opaque_type_key, (hidden_type, decl.origin))
243 MirTypeckResults { constraints, universal_region_relations, opaque_type_values }
247 skip(infcx, body, promoted, region_bound_pairs, borrowck_context, extra),
250 fn type_check_internal<'a, 'tcx, R>(
251 infcx: &'a InferCtxt<'a, 'tcx>,
252 param_env: ty::ParamEnv<'tcx>,
253 body: &'a Body<'tcx>,
254 promoted: &'a IndexVec<Promoted, Body<'tcx>>,
255 region_bound_pairs: &'a RegionBoundPairs<'tcx>,
256 implicit_region_bound: ty::Region<'tcx>,
257 borrowck_context: &'a mut BorrowCheckContext<'a, 'tcx>,
258 extra: impl FnOnce(TypeChecker<'a, 'tcx>) -> R,
260 let mut checker = TypeChecker::new(
265 implicit_region_bound,
268 let errors_reported = {
269 let mut verifier = TypeVerifier::new(&mut checker, promoted);
270 verifier.visit_body(&body);
271 verifier.errors_reported
274 if !errors_reported {
275 // if verifier failed, don't do further checks to avoid ICEs
276 checker.typeck_mir(body);
282 fn translate_outlives_facts(typeck: &mut TypeChecker<'_, '_>) {
283 let cx = &mut typeck.borrowck_context;
284 if let Some(facts) = cx.all_facts {
285 let _prof_timer = typeck.infcx.tcx.prof.generic_activity("polonius_fact_generation");
286 let location_table = cx.location_table;
287 facts.subset_base.extend(cx.constraints.outlives_constraints.outlives().iter().flat_map(
288 |constraint: &OutlivesConstraint<'_>| {
289 if let Some(from_location) = constraint.locations.from_location() {
290 Either::Left(iter::once((
293 location_table.mid_index(from_location),
299 .map(move |location| (constraint.sup, constraint.sub, location)),
308 fn mirbug(tcx: TyCtxt<'_>, span: Span, msg: &str) {
309 // We sometimes see MIR failures (notably predicate failures) due to
310 // the fact that we check rvalue sized predicates here. So use `delay_span_bug`
311 // to avoid reporting bugs in those cases.
312 tcx.sess.diagnostic().delay_span_bug(span, msg);
315 enum FieldAccessError {
316 OutOfRange { field_count: usize },
319 /// Verifies that MIR types are sane to not crash further checks.
321 /// The sanitize_XYZ methods here take an MIR object and compute its
322 /// type, calling `span_mirbug` and returning an error type if there
324 struct TypeVerifier<'a, 'b, 'tcx> {
325 cx: &'a mut TypeChecker<'b, 'tcx>,
326 promoted: &'b IndexVec<Promoted, Body<'tcx>>,
328 errors_reported: bool,
331 impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> {
332 fn visit_span(&mut self, span: &Span) {
333 if !span.is_dummy() {
334 self.last_span = *span;
338 fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, location: Location) {
339 self.sanitize_place(place, location, context);
342 fn visit_constant(&mut self, constant: &Constant<'tcx>, location: Location) {
343 self.super_constant(constant, location);
344 let ty = self.sanitize_type(constant, constant.literal.ty());
346 self.cx.infcx.tcx.for_each_free_region(&ty, |live_region| {
347 let live_region_vid =
348 self.cx.borrowck_context.universal_regions.to_region_vid(live_region);
352 .liveness_constraints
353 .add_element(live_region_vid, location);
356 if let Some(annotation_index) = constant.user_ty {
357 if let Err(terr) = self.cx.relate_type_and_user_type(
358 constant.literal.ty(),
359 ty::Variance::Invariant,
360 &UserTypeProjection { base: annotation_index, projs: vec![] },
361 location.to_locations(),
362 ConstraintCategory::Boring,
364 let annotation = &self.cx.user_type_annotations[annotation_index];
368 "bad constant user type {:?} vs {:?}: {:?}",
370 constant.literal.ty(),
375 let tcx = self.tcx();
376 let maybe_uneval = match constant.literal {
377 ConstantKind::Ty(ct) => match ct.val() {
378 ty::ConstKind::Unevaluated(uv) => Some(uv),
383 if let Some(uv) = maybe_uneval {
384 if let Some(promoted) = uv.promoted {
385 let check_err = |verifier: &mut TypeVerifier<'a, 'b, 'tcx>,
386 promoted: &Body<'tcx>,
389 if let Err(terr) = verifier.cx.eq_types(
392 location.to_locations(),
393 ConstraintCategory::Boring,
398 "bad promoted type ({:?}: {:?}): {:?}",
406 if !self.errors_reported {
407 let promoted_body = &self.promoted[promoted];
408 self.sanitize_promoted(promoted_body, location);
410 let promoted_ty = promoted_body.return_ty();
411 check_err(self, promoted_body, ty, promoted_ty);
414 if let Err(terr) = self.cx.fully_perform_op(
415 location.to_locations(),
416 ConstraintCategory::Boring,
417 self.cx.param_env.and(type_op::ascribe_user_type::AscribeUserType::new(
418 constant.literal.ty(),
420 UserSubsts { substs: uv.substs, user_self_ty: None },
426 "bad constant type {:?} ({:?})",
432 } else if let Some(static_def_id) = constant.check_static_ptr(tcx) {
433 let unnormalized_ty = tcx.type_of(static_def_id);
434 let locations = location.to_locations();
435 let normalized_ty = self.cx.normalize(unnormalized_ty, locations);
436 let literal_ty = constant.literal.ty().builtin_deref(true).unwrap().ty;
438 if let Err(terr) = self.cx.eq_types(
442 ConstraintCategory::Boring,
444 span_mirbug!(self, constant, "bad static type {:?} ({:?})", constant, terr);
448 if let ty::FnDef(def_id, substs) = *constant.literal.ty().kind() {
449 let instantiated_predicates = tcx.predicates_of(def_id).instantiate(tcx, substs);
450 self.cx.normalize_and_prove_instantiated_predicates(
452 instantiated_predicates,
453 location.to_locations(),
459 fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
460 self.super_rvalue(rvalue, location);
461 let rval_ty = rvalue.ty(self.body(), self.tcx());
462 self.sanitize_type(rvalue, rval_ty);
465 fn visit_local_decl(&mut self, local: Local, local_decl: &LocalDecl<'tcx>) {
466 self.super_local_decl(local, local_decl);
467 self.sanitize_type(local_decl, local_decl.ty);
469 if let Some(user_ty) = &local_decl.user_ty {
470 for (user_ty, span) in user_ty.projections_and_spans() {
471 let ty = if !local_decl.is_nonref_binding() {
472 // If we have a binding of the form `let ref x: T = ..`
473 // then remove the outermost reference so we can check the
474 // type annotation for the remaining type.
475 if let ty::Ref(_, rty, _) = local_decl.ty.kind() {
478 bug!("{:?} with ref binding has wrong type {}", local, local_decl.ty);
484 if let Err(terr) = self.cx.relate_type_and_user_type(
486 ty::Variance::Invariant,
488 Locations::All(*span),
489 ConstraintCategory::TypeAnnotation,
494 "bad user type on variable {:?}: {:?} != {:?} ({:?})",
505 fn visit_body(&mut self, body: &Body<'tcx>) {
506 self.sanitize_type(&"return type", body.return_ty());
507 for local_decl in &body.local_decls {
508 self.sanitize_type(local_decl, local_decl.ty);
510 if self.errors_reported {
513 self.super_body(body);
517 impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
519 cx: &'a mut TypeChecker<'b, 'tcx>,
520 promoted: &'b IndexVec<Promoted, Body<'tcx>>,
522 TypeVerifier { promoted, last_span: cx.body.span, cx, errors_reported: false }
525 fn body(&self) -> &Body<'tcx> {
529 fn tcx(&self) -> TyCtxt<'tcx> {
533 fn sanitize_type(&mut self, parent: &dyn fmt::Debug, ty: Ty<'tcx>) -> Ty<'tcx> {
534 if ty.has_escaping_bound_vars() || ty.references_error() {
535 span_mirbug_and_err!(self, parent, "bad type {:?}", ty)
541 /// Checks that the types internal to the `place` match up with
542 /// what would be expected.
547 context: PlaceContext,
549 debug!("sanitize_place: {:?}", place);
551 let mut place_ty = PlaceTy::from_ty(self.body().local_decls[place.local].ty);
553 for elem in place.projection.iter() {
554 if place_ty.variant_index.is_none() {
555 if place_ty.ty.references_error() {
556 assert!(self.errors_reported);
557 return PlaceTy::from_ty(self.tcx().ty_error());
560 place_ty = self.sanitize_projection(place_ty, elem, place, location);
563 if let PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy) = context {
564 let tcx = self.tcx();
565 let trait_ref = ty::TraitRef {
566 def_id: tcx.require_lang_item(LangItem::Copy, Some(self.last_span)),
567 substs: tcx.mk_substs_trait(place_ty.ty, &[]),
570 // To have a `Copy` operand, the type `T` of the
571 // value must be `Copy`. Note that we prove that `T: Copy`,
572 // rather than using the `is_copy_modulo_regions`
573 // test. This is important because
574 // `is_copy_modulo_regions` ignores the resulting region
575 // obligations and assumes they pass. This can result in
576 // bounds from `Copy` impls being unsoundly ignored (e.g.,
577 // #29149). Note that we decide to use `Copy` before knowing
578 // whether the bounds fully apply: in effect, the rule is
579 // that if a value of some type could implement `Copy`, then
581 self.cx.prove_trait_ref(
583 location.to_locations(),
584 ConstraintCategory::CopyBound,
591 fn sanitize_promoted(&mut self, promoted_body: &'b Body<'tcx>, location: Location) {
592 // Determine the constraints from the promoted MIR by running the type
593 // checker on the promoted MIR, then transfer the constraints back to
594 // the main MIR, changing the locations to the provided location.
596 let parent_body = mem::replace(&mut self.cx.body, promoted_body);
598 // Use new sets of constraints and closure bounds so that we can
599 // modify their locations.
600 let all_facts = &mut None;
601 let mut constraints = Default::default();
602 let mut closure_bounds = Default::default();
603 let mut liveness_constraints =
604 LivenessValues::new(Rc::new(RegionValueElements::new(&promoted_body)));
605 // Don't try to add borrow_region facts for the promoted MIR
607 let mut swap_constraints = |this: &mut Self| {
608 mem::swap(this.cx.borrowck_context.all_facts, all_facts);
610 &mut this.cx.borrowck_context.constraints.outlives_constraints,
614 &mut this.cx.borrowck_context.constraints.closure_bounds_mapping,
618 &mut this.cx.borrowck_context.constraints.liveness_constraints,
619 &mut liveness_constraints,
623 swap_constraints(self);
625 self.visit_body(&promoted_body);
627 if !self.errors_reported {
628 // if verifier failed, don't do further checks to avoid ICEs
629 self.cx.typeck_mir(promoted_body);
632 self.cx.body = parent_body;
633 // Merge the outlives constraints back in, at the given location.
634 swap_constraints(self);
636 let locations = location.to_locations();
637 for constraint in constraints.outlives().iter() {
638 let mut constraint = constraint.clone();
639 constraint.locations = locations;
640 if let ConstraintCategory::Return(_)
641 | ConstraintCategory::UseAsConst
642 | ConstraintCategory::UseAsStatic = constraint.category
644 // "Returning" from a promoted is an assignment to a
645 // temporary from the user's point of view.
646 constraint.category = ConstraintCategory::Boring;
648 self.cx.borrowck_context.constraints.outlives_constraints.push(constraint)
650 for region in liveness_constraints.rows() {
651 // If the region is live at at least one location in the promoted MIR,
652 // then add a liveness constraint to the main MIR for this region
653 // at the location provided as an argument to this method
654 if liveness_constraints.get_elements(region).next().is_some() {
658 .liveness_constraints
659 .add_element(region, location);
663 if !closure_bounds.is_empty() {
664 let combined_bounds_mapping =
665 closure_bounds.into_iter().flat_map(|(_, value)| value).collect();
670 .closure_bounds_mapping
671 .insert(location, combined_bounds_mapping);
672 assert!(existing.is_none(), "Multiple promoteds/closures at the same location.");
676 fn sanitize_projection(
683 debug!("sanitize_projection: {:?} {:?} {:?}", base, pi, place);
684 let tcx = self.tcx();
685 let base_ty = base.ty;
687 ProjectionElem::Deref => {
688 let deref_ty = base_ty.builtin_deref(true);
689 PlaceTy::from_ty(deref_ty.map(|t| t.ty).unwrap_or_else(|| {
690 span_mirbug_and_err!(self, place, "deref of non-pointer {:?}", base_ty)
693 ProjectionElem::Index(i) => {
694 let index_ty = Place::from(i).ty(self.body(), tcx).ty;
695 if index_ty != tcx.types.usize {
696 PlaceTy::from_ty(span_mirbug_and_err!(self, i, "index by non-usize {:?}", i))
698 PlaceTy::from_ty(base_ty.builtin_index().unwrap_or_else(|| {
699 span_mirbug_and_err!(self, place, "index of non-array {:?}", base_ty)
703 ProjectionElem::ConstantIndex { .. } => {
704 // consider verifying in-bounds
705 PlaceTy::from_ty(base_ty.builtin_index().unwrap_or_else(|| {
706 span_mirbug_and_err!(self, place, "index of non-array {:?}", base_ty)
709 ProjectionElem::Subslice { from, to, from_end } => {
710 PlaceTy::from_ty(match base_ty.kind() {
711 ty::Array(inner, _) => {
712 assert!(!from_end, "array subslices should not use from_end");
713 tcx.mk_array(*inner, to - from)
716 assert!(from_end, "slice subslices should use from_end");
719 _ => span_mirbug_and_err!(self, place, "slice of non-array {:?}", base_ty),
722 ProjectionElem::Downcast(maybe_name, index) => match base_ty.kind() {
723 ty::Adt(adt_def, _substs) if adt_def.is_enum() => {
724 if index.as_usize() >= adt_def.variants().len() {
725 PlaceTy::from_ty(span_mirbug_and_err!(
728 "cast to variant #{:?} but enum only has {:?}",
730 adt_def.variants().len()
733 PlaceTy { ty: base_ty, variant_index: Some(index) }
736 // We do not need to handle generators here, because this runs
737 // before the generator transform stage.
739 let ty = if let Some(name) = maybe_name {
740 span_mirbug_and_err!(
743 "can't downcast {:?} as {:?}",
748 span_mirbug_and_err!(self, place, "can't downcast {:?}", base_ty)
753 ProjectionElem::Field(field, fty) => {
754 let fty = self.sanitize_type(place, fty);
755 let fty = self.cx.normalize(fty, location);
756 match self.field_ty(place, base, field, location) {
758 let ty = self.cx.normalize(ty, location);
759 if let Err(terr) = self.cx.eq_types(
762 location.to_locations(),
763 ConstraintCategory::Boring,
768 "bad field access ({:?}: {:?}): {:?}",
775 Err(FieldAccessError::OutOfRange { field_count }) => span_mirbug!(
778 "accessed field #{} but variant only has {}",
783 PlaceTy::from_ty(fty)
788 fn error(&mut self) -> Ty<'tcx> {
789 self.errors_reported = true;
790 self.tcx().ty_error()
795 parent: &dyn fmt::Debug,
796 base_ty: PlaceTy<'tcx>,
799 ) -> Result<Ty<'tcx>, FieldAccessError> {
800 let tcx = self.tcx();
802 let (variant, substs) = match base_ty {
803 PlaceTy { ty, variant_index: Some(variant_index) } => match *ty.kind() {
804 ty::Adt(adt_def, substs) => (adt_def.variant(variant_index), substs),
805 ty::Generator(def_id, substs, _) => {
806 let mut variants = substs.as_generator().state_tys(def_id, tcx);
807 let Some(mut variant) = variants.nth(variant_index.into()) else {
809 "variant_index of generator out of range: {:?}/{:?}",
811 substs.as_generator().state_tys(def_id, tcx).count()
814 return match variant.nth(field.index()) {
816 None => Err(FieldAccessError::OutOfRange { field_count: variant.count() }),
819 _ => bug!("can't have downcast of non-adt non-generator type"),
821 PlaceTy { ty, variant_index: None } => match *ty.kind() {
822 ty::Adt(adt_def, substs) if !adt_def.is_enum() => {
823 (adt_def.variant(VariantIdx::new(0)), substs)
825 ty::Closure(_, substs) => {
833 None => Err(FieldAccessError::OutOfRange {
834 field_count: substs.as_closure().upvar_tys().count(),
838 ty::Generator(_, substs, _) => {
839 // Only prefix fields (upvars and current state) are
840 // accessible without a variant index.
841 return match substs.as_generator().prefix_tys().nth(field.index()) {
843 None => Err(FieldAccessError::OutOfRange {
844 field_count: substs.as_generator().prefix_tys().count(),
849 return match tys.get(field.index()) {
851 None => Err(FieldAccessError::OutOfRange { field_count: tys.len() }),
855 return Ok(span_mirbug_and_err!(
858 "can't project out of {:?}",
865 if let Some(field) = variant.fields.get(field.index()) {
866 Ok(self.cx.normalize(field.ty(tcx, substs), location))
868 Err(FieldAccessError::OutOfRange { field_count: variant.fields.len() })
873 /// The MIR type checker. Visits the MIR and enforces all the
874 /// constraints needed for it to be valid and well-typed. Along the
875 /// way, it accrues region constraints -- these can later be used by
876 /// NLL region checking.
877 struct TypeChecker<'a, 'tcx> {
878 infcx: &'a InferCtxt<'a, 'tcx>,
879 param_env: ty::ParamEnv<'tcx>,
881 body: &'a Body<'tcx>,
882 /// User type annotations are shared between the main MIR and the MIR of
883 /// all of the promoted items.
884 user_type_annotations: &'a CanonicalUserTypeAnnotations<'tcx>,
885 region_bound_pairs: &'a RegionBoundPairs<'tcx>,
886 implicit_region_bound: ty::Region<'tcx>,
887 reported_errors: FxHashSet<(Ty<'tcx>, Span)>,
888 borrowck_context: &'a mut BorrowCheckContext<'a, 'tcx>,
891 struct BorrowCheckContext<'a, 'tcx> {
892 pub(crate) universal_regions: &'a UniversalRegions<'tcx>,
893 location_table: &'a LocationTable,
894 all_facts: &'a mut Option<AllFacts>,
895 borrow_set: &'a BorrowSet<'tcx>,
896 pub(crate) constraints: &'a mut MirTypeckRegionConstraints<'tcx>,
897 upvars: &'a [Upvar<'tcx>],
900 pub(crate) struct MirTypeckResults<'tcx> {
901 pub(crate) constraints: MirTypeckRegionConstraints<'tcx>,
902 pub(crate) universal_region_relations: Frozen<UniversalRegionRelations<'tcx>>,
903 pub(crate) opaque_type_values:
904 VecMap<OpaqueTypeKey<'tcx>, (OpaqueHiddenType<'tcx>, OpaqueTyOrigin)>,
907 /// A collection of region constraints that must be satisfied for the
908 /// program to be considered well-typed.
909 pub(crate) struct MirTypeckRegionConstraints<'tcx> {
910 /// Maps from a `ty::Placeholder` to the corresponding
911 /// `PlaceholderIndex` bit that we will use for it.
913 /// To keep everything in sync, do not insert this set
914 /// directly. Instead, use the `placeholder_region` helper.
915 pub(crate) placeholder_indices: PlaceholderIndices,
917 /// Each time we add a placeholder to `placeholder_indices`, we
918 /// also create a corresponding "representative" region vid for
919 /// that wraps it. This vector tracks those. This way, when we
920 /// convert the same `ty::RePlaceholder(p)` twice, we can map to
921 /// the same underlying `RegionVid`.
922 pub(crate) placeholder_index_to_region: IndexVec<PlaceholderIndex, ty::Region<'tcx>>,
924 /// In general, the type-checker is not responsible for enforcing
925 /// liveness constraints; this job falls to the region inferencer,
926 /// which performs a liveness analysis. However, in some limited
927 /// cases, the MIR type-checker creates temporary regions that do
928 /// not otherwise appear in the MIR -- in particular, the
929 /// late-bound regions that it instantiates at call-sites -- and
930 /// hence it must report on their liveness constraints.
931 pub(crate) liveness_constraints: LivenessValues<RegionVid>,
933 pub(crate) outlives_constraints: OutlivesConstraintSet<'tcx>,
935 pub(crate) member_constraints: MemberConstraintSet<'tcx, RegionVid>,
937 pub(crate) closure_bounds_mapping:
938 FxHashMap<Location, FxHashMap<(RegionVid, RegionVid), (ConstraintCategory, Span)>>,
940 pub(crate) universe_causes: FxHashMap<ty::UniverseIndex, UniverseInfo<'tcx>>,
942 pub(crate) type_tests: Vec<TypeTest<'tcx>>,
945 impl<'tcx> MirTypeckRegionConstraints<'tcx> {
946 fn placeholder_region(
948 infcx: &InferCtxt<'_, 'tcx>,
949 placeholder: ty::PlaceholderRegion,
950 ) -> ty::Region<'tcx> {
951 let placeholder_index = self.placeholder_indices.insert(placeholder);
952 match self.placeholder_index_to_region.get(placeholder_index) {
955 let origin = NllRegionVariableOrigin::Placeholder(placeholder);
956 let region = infcx.next_nll_region_var_in_universe(origin, placeholder.universe);
957 self.placeholder_index_to_region.push(region);
964 /// The `Locations` type summarizes *where* region constraints are
965 /// required to hold. Normally, this is at a particular point which
966 /// created the obligation, but for constraints that the user gave, we
967 /// want the constraint to hold at all points.
968 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
970 /// Indicates that a type constraint should always be true. This
971 /// is particularly important in the new borrowck analysis for
972 /// things like the type of the return slot. Consider this
975 /// ```compile_fail,E0515
976 /// fn foo<'a>(x: &'a u32) -> &'a u32 {
978 /// return &y; // error
982 /// Here, we wind up with the signature from the return type being
983 /// something like `&'1 u32` where `'1` is a universal region. But
984 /// the type of the return slot `_0` is something like `&'2 u32`
985 /// where `'2` is an existential region variable. The type checker
986 /// requires that `&'2 u32 = &'1 u32` -- but at what point? In the
987 /// older NLL analysis, we required this only at the entry point
988 /// to the function. By the nature of the constraints, this wound
989 /// up propagating to all points reachable from start (because
990 /// `'1` -- as a universal region -- is live everywhere). In the
991 /// newer analysis, though, this doesn't work: `_0` is considered
992 /// dead at the start (it has no usable value) and hence this type
993 /// equality is basically a no-op. Then, later on, when we do `_0
994 /// = &'3 y`, that region `'3` never winds up related to the
995 /// universal region `'1` and hence no error occurs. Therefore, we
996 /// use Locations::All instead, which ensures that the `'1` and
997 /// `'2` are equal everything. We also use this for other
998 /// user-given type annotations; e.g., if the user wrote `let mut
999 /// x: &'static u32 = ...`, we would ensure that all values
1000 /// assigned to `x` are of `'static` lifetime.
1002 /// The span points to the place the constraint arose. For example,
1003 /// it points to the type in a user-given type annotation. If
1004 /// there's no sensible span then it's DUMMY_SP.
1007 /// An outlives constraint that only has to hold at a single location,
1008 /// usually it represents a point where references flow from one spot to
1009 /// another (e.g., `x = y`)
1014 pub fn from_location(&self) -> Option<Location> {
1016 Locations::All(_) => None,
1017 Locations::Single(from_location) => Some(*from_location),
1021 /// Gets a span representing the location.
1022 pub fn span(&self, body: &Body<'_>) -> Span {
1024 Locations::All(span) => *span,
1025 Locations::Single(l) => body.source_info(*l).span,
1030 impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
1032 infcx: &'a InferCtxt<'a, 'tcx>,
1033 body: &'a Body<'tcx>,
1034 param_env: ty::ParamEnv<'tcx>,
1035 region_bound_pairs: &'a RegionBoundPairs<'tcx>,
1036 implicit_region_bound: ty::Region<'tcx>,
1037 borrowck_context: &'a mut BorrowCheckContext<'a, 'tcx>,
1039 let mut checker = Self {
1041 last_span: DUMMY_SP,
1043 user_type_annotations: &body.user_type_annotations,
1046 implicit_region_bound,
1048 reported_errors: Default::default(),
1050 checker.check_user_type_annotations();
1054 fn body(&self) -> &Body<'tcx> {
1058 fn unsized_feature_enabled(&self) -> bool {
1059 let features = self.tcx().features();
1060 features.unsized_locals || features.unsized_fn_params
1063 /// Equate the inferred type and the annotated type for user type annotations
1064 #[instrument(skip(self), level = "debug")]
1065 fn check_user_type_annotations(&mut self) {
1066 debug!(?self.user_type_annotations);
1067 for user_annotation in self.user_type_annotations {
1068 let CanonicalUserTypeAnnotation { span, ref user_ty, inferred_ty } = *user_annotation;
1069 let inferred_ty = self.normalize(inferred_ty, Locations::All(span));
1070 let annotation = self.instantiate_canonical_with_fresh_inference_vars(span, user_ty);
1072 UserType::Ty(mut ty) => {
1073 ty = self.normalize(ty, Locations::All(span));
1075 if let Err(terr) = self.eq_types(
1078 Locations::All(span),
1079 ConstraintCategory::BoringNoLocation,
1084 "bad user type ({:?} = {:?}): {:?}",
1091 self.prove_predicate(
1092 ty::Binder::dummy(ty::PredicateKind::WellFormed(inferred_ty.into()))
1093 .to_predicate(self.tcx()),
1094 Locations::All(span),
1095 ConstraintCategory::TypeAnnotation,
1098 UserType::TypeOf(def_id, user_substs) => {
1099 if let Err(terr) = self.fully_perform_op(
1100 Locations::All(span),
1101 ConstraintCategory::BoringNoLocation,
1102 self.param_env.and(type_op::ascribe_user_type::AscribeUserType::new(
1111 "bad user type AscribeUserType({:?}, {:?} {:?}, type_of={:?}): {:?}",
1115 self.tcx().type_of(def_id),
1124 #[instrument(skip(self, data), level = "debug")]
1125 fn push_region_constraints(
1127 locations: Locations,
1128 category: ConstraintCategory,
1129 data: &QueryRegionConstraints<'tcx>,
1131 debug!("constraints generated: {:#?}", data);
1133 constraint_conversion::ConstraintConversion::new(
1135 self.borrowck_context.universal_regions,
1136 self.region_bound_pairs,
1137 Some(self.implicit_region_bound),
1140 locations.span(self.body),
1142 &mut self.borrowck_context.constraints,
1147 /// Try to relate `sub <: sup`
1152 locations: Locations,
1153 category: ConstraintCategory,
1155 // Use this order of parameters because the sup type is usually the
1156 // "expected" type in diagnostics.
1157 self.relate_types(sup, ty::Variance::Contravariant, sub, locations, category)
1160 #[instrument(skip(self, category), level = "debug")]
1165 locations: Locations,
1166 category: ConstraintCategory,
1168 self.relate_types(expected, ty::Variance::Invariant, found, locations, category)
1171 #[instrument(skip(self), level = "debug")]
1172 fn relate_type_and_user_type(
1176 user_ty: &UserTypeProjection,
1177 locations: Locations,
1178 category: ConstraintCategory,
1180 let annotated_type = self.user_type_annotations[user_ty.base].inferred_ty;
1181 let mut curr_projected_ty = PlaceTy::from_ty(annotated_type);
1183 let tcx = self.infcx.tcx;
1185 for proj in &user_ty.projs {
1186 let projected_ty = curr_projected_ty.projection_ty_core(
1191 let ty = this.field_ty(tcx, field);
1192 self.normalize(ty, locations)
1195 curr_projected_ty = projected_ty;
1198 "user_ty base: {:?} freshened: {:?} projs: {:?} yields: {:?}",
1199 user_ty.base, annotated_type, user_ty.projs, curr_projected_ty
1202 let ty = curr_projected_ty.ty;
1203 self.relate_types(ty, v.xform(ty::Variance::Contravariant), a, locations, category)?;
1208 fn tcx(&self) -> TyCtxt<'tcx> {
1212 #[instrument(skip(self, body, location), level = "debug")]
1213 fn check_stmt(&mut self, body: &Body<'tcx>, stmt: &Statement<'tcx>, location: Location) {
1214 let tcx = self.tcx();
1216 StatementKind::Assign(box (ref place, ref rv)) => {
1217 // Assignments to temporaries are not "interesting";
1218 // they are not caused by the user, but rather artifacts
1219 // of lowering. Assignments to other sorts of places *are* interesting
1221 let category = match place.as_local() {
1222 Some(RETURN_PLACE) => {
1223 let defining_ty = &self.borrowck_context.universal_regions.defining_ty;
1224 if defining_ty.is_const() {
1225 if tcx.is_static(defining_ty.def_id()) {
1226 ConstraintCategory::UseAsStatic
1228 ConstraintCategory::UseAsConst
1231 ConstraintCategory::Return(ReturnConstraint::Normal)
1236 body.local_decls[l].local_info,
1237 Some(box LocalInfo::AggregateTemp)
1240 ConstraintCategory::Usage
1242 Some(l) if !body.local_decls[l].is_user_variable() => {
1243 ConstraintCategory::Boring
1245 _ => ConstraintCategory::Assignment,
1248 "assignment category: {:?} {:?}",
1250 place.as_local().map(|l| &body.local_decls[l])
1253 let place_ty = place.ty(body, tcx).ty;
1254 let place_ty = self.normalize(place_ty, location);
1255 let rv_ty = rv.ty(body, tcx);
1256 let rv_ty = self.normalize(rv_ty, location);
1258 self.sub_types(rv_ty, place_ty, location.to_locations(), category)
1263 "bad assignment ({:?} = {:?}): {:?}",
1270 if let Some(annotation_index) = self.rvalue_user_ty(rv) {
1271 if let Err(terr) = self.relate_type_and_user_type(
1273 ty::Variance::Invariant,
1274 &UserTypeProjection { base: annotation_index, projs: vec![] },
1275 location.to_locations(),
1276 ConstraintCategory::Boring,
1278 let annotation = &self.user_type_annotations[annotation_index];
1282 "bad user type on rvalue ({:?} = {:?}): {:?}",
1290 self.check_rvalue(body, rv, location);
1291 if !self.unsized_feature_enabled() {
1292 let trait_ref = ty::TraitRef {
1293 def_id: tcx.require_lang_item(LangItem::Sized, Some(self.last_span)),
1294 substs: tcx.mk_substs_trait(place_ty, &[]),
1296 self.prove_trait_ref(
1298 location.to_locations(),
1299 ConstraintCategory::SizedBound,
1303 StatementKind::AscribeUserType(box (ref place, ref projection), variance) => {
1304 let place_ty = place.ty(body, tcx).ty;
1305 if let Err(terr) = self.relate_type_and_user_type(
1309 Locations::All(stmt.source_info.span),
1310 ConstraintCategory::TypeAnnotation,
1312 let annotation = &self.user_type_annotations[projection.base];
1316 "bad type assert ({:?} <: {:?} with projections {:?}): {:?}",
1324 StatementKind::CopyNonOverlapping(box rustc_middle::mir::CopyNonOverlapping {
1327 stmt.source_info.span,
1328 "Unexpected StatementKind::CopyNonOverlapping, should only appear after lowering_intrinsics",
1330 StatementKind::FakeRead(..)
1331 | StatementKind::StorageLive(..)
1332 | StatementKind::StorageDead(..)
1333 | StatementKind::Retag { .. }
1334 | StatementKind::Coverage(..)
1335 | StatementKind::Nop => {}
1336 StatementKind::Deinit(..) | StatementKind::SetDiscriminant { .. } => {
1337 bug!("Statement not allowed in this MIR phase")
1342 #[instrument(skip(self, body, term_location), level = "debug")]
1343 fn check_terminator(
1346 term: &Terminator<'tcx>,
1347 term_location: Location,
1349 let tcx = self.tcx();
1351 TerminatorKind::Goto { .. }
1352 | TerminatorKind::Resume
1353 | TerminatorKind::Abort
1354 | TerminatorKind::Return
1355 | TerminatorKind::GeneratorDrop
1356 | TerminatorKind::Unreachable
1357 | TerminatorKind::Drop { .. }
1358 | TerminatorKind::FalseEdge { .. }
1359 | TerminatorKind::FalseUnwind { .. }
1360 | TerminatorKind::InlineAsm { .. } => {
1361 // no checks needed for these
1364 TerminatorKind::DropAndReplace { ref place, ref value, target: _, unwind: _ } => {
1365 let place_ty = place.ty(body, tcx).ty;
1366 let rv_ty = value.ty(body, tcx);
1368 let locations = term_location.to_locations();
1370 self.sub_types(rv_ty, place_ty, locations, ConstraintCategory::Assignment)
1375 "bad DropAndReplace ({:?} = {:?}): {:?}",
1382 TerminatorKind::SwitchInt { ref discr, switch_ty, .. } => {
1383 self.check_operand(discr, term_location);
1385 let discr_ty = discr.ty(body, tcx);
1386 if let Err(terr) = self.sub_types(
1389 term_location.to_locations(),
1390 ConstraintCategory::Assignment,
1395 "bad SwitchInt ({:?} on {:?}): {:?}",
1401 if !switch_ty.is_integral() && !switch_ty.is_char() && !switch_ty.is_bool() {
1402 span_mirbug!(self, term, "bad SwitchInt discr ty {:?}", switch_ty);
1404 // FIXME: check the values
1406 TerminatorKind::Call {
1407 ref func, ref args, destination, target, from_hir_call, ..
1409 self.check_operand(func, term_location);
1411 self.check_operand(arg, term_location);
1414 let func_ty = func.ty(body, tcx);
1415 debug!("check_terminator: call, func_ty={:?}", func_ty);
1416 let sig = match func_ty.kind() {
1417 ty::FnDef(..) | ty::FnPtr(_) => func_ty.fn_sig(tcx),
1419 span_mirbug!(self, term, "call to non-function {:?}", func_ty);
1423 let (sig, map) = self.infcx.replace_bound_vars_with_fresh_vars(
1424 term.source_info.span,
1425 LateBoundRegionConversionTime::FnCall,
1428 let sig = self.normalize(sig, term_location);
1429 self.check_call_dest(body, term, &sig, destination, target, term_location);
1431 self.prove_predicates(
1432 sig.inputs_and_output
1434 .map(|ty| ty::Binder::dummy(ty::PredicateKind::WellFormed(ty.into()))),
1435 term_location.to_locations(),
1436 ConstraintCategory::Boring,
1439 // The ordinary liveness rules will ensure that all
1440 // regions in the type of the callee are live here. We
1441 // then further constrain the late-bound regions that
1442 // were instantiated at the call site to be live as
1443 // well. The resulting is that all the input (and
1444 // output) types in the signature must be live, since
1445 // all the inputs that fed into it were live.
1446 for &late_bound_region in map.values() {
1448 self.borrowck_context.universal_regions.to_region_vid(late_bound_region);
1449 self.borrowck_context
1451 .liveness_constraints
1452 .add_element(region_vid, term_location);
1455 self.check_call_inputs(body, term, &sig, args, term_location, from_hir_call);
1457 TerminatorKind::Assert { ref cond, ref msg, .. } => {
1458 self.check_operand(cond, term_location);
1460 let cond_ty = cond.ty(body, tcx);
1461 if cond_ty != tcx.types.bool {
1462 span_mirbug!(self, term, "bad Assert ({:?}, not bool", cond_ty);
1465 if let AssertKind::BoundsCheck { ref len, ref index } = *msg {
1466 if len.ty(body, tcx) != tcx.types.usize {
1467 span_mirbug!(self, len, "bounds-check length non-usize {:?}", len)
1469 if index.ty(body, tcx) != tcx.types.usize {
1470 span_mirbug!(self, index, "bounds-check index non-usize {:?}", index)
1474 TerminatorKind::Yield { ref value, .. } => {
1475 self.check_operand(value, term_location);
1477 let value_ty = value.ty(body, tcx);
1478 match body.yield_ty() {
1479 None => span_mirbug!(self, term, "yield in non-generator"),
1481 if let Err(terr) = self.sub_types(
1484 term_location.to_locations(),
1485 ConstraintCategory::Yield,
1490 "type of yield value is {:?}, but the yield type is {:?}: {:?}",
1505 term: &Terminator<'tcx>,
1506 sig: &ty::FnSig<'tcx>,
1507 destination: Place<'tcx>,
1508 target: Option<BasicBlock>,
1509 term_location: Location,
1511 let tcx = self.tcx();
1514 let dest_ty = destination.ty(body, tcx).ty;
1515 let dest_ty = self.normalize(dest_ty, term_location);
1516 let category = match destination.as_local() {
1517 Some(RETURN_PLACE) => {
1518 if let BorrowCheckContext {
1522 DefiningTy::Const(def_id, _)
1523 | DefiningTy::InlineConst(def_id, _),
1527 } = self.borrowck_context
1529 if tcx.is_static(*def_id) {
1530 ConstraintCategory::UseAsStatic
1532 ConstraintCategory::UseAsConst
1535 ConstraintCategory::Return(ReturnConstraint::Normal)
1538 Some(l) if !body.local_decls[l].is_user_variable() => {
1539 ConstraintCategory::Boring
1541 _ => ConstraintCategory::Assignment,
1544 let locations = term_location.to_locations();
1546 if let Err(terr) = self.sub_types(sig.output(), dest_ty, locations, category) {
1550 "call dest mismatch ({:?} <- {:?}): {:?}",
1557 // When `unsized_fn_params` and `unsized_locals` are both not enabled,
1558 // this check is done at `check_local`.
1559 if self.unsized_feature_enabled() {
1560 let span = term.source_info.span;
1561 self.ensure_place_sized(dest_ty, span);
1567 .conservative_is_privately_uninhabited(self.param_env.and(sig.output()))
1569 span_mirbug!(self, term, "call to converging function {:?} w/o dest", sig);
1575 fn check_call_inputs(
1578 term: &Terminator<'tcx>,
1579 sig: &ty::FnSig<'tcx>,
1580 args: &[Operand<'tcx>],
1581 term_location: Location,
1582 from_hir_call: bool,
1584 debug!("check_call_inputs({:?}, {:?})", sig, args);
1585 if args.len() < sig.inputs().len() || (args.len() > sig.inputs().len() && !sig.c_variadic) {
1586 span_mirbug!(self, term, "call to {:?} with wrong # of args", sig);
1588 for (n, (fn_arg, op_arg)) in iter::zip(sig.inputs(), args).enumerate() {
1589 let op_arg_ty = op_arg.ty(body, self.tcx());
1590 let op_arg_ty = self.normalize(op_arg_ty, term_location);
1591 let category = if from_hir_call {
1592 ConstraintCategory::CallArgument
1594 ConstraintCategory::Boring
1597 self.sub_types(op_arg_ty, *fn_arg, term_location.to_locations(), category)
1602 "bad arg #{:?} ({:?} <- {:?}): {:?}",
1612 fn check_iscleanup(&mut self, body: &Body<'tcx>, block_data: &BasicBlockData<'tcx>) {
1613 let is_cleanup = block_data.is_cleanup;
1614 self.last_span = block_data.terminator().source_info.span;
1615 match block_data.terminator().kind {
1616 TerminatorKind::Goto { target } => {
1617 self.assert_iscleanup(body, block_data, target, is_cleanup)
1619 TerminatorKind::SwitchInt { ref targets, .. } => {
1620 for target in targets.all_targets() {
1621 self.assert_iscleanup(body, block_data, *target, is_cleanup);
1624 TerminatorKind::Resume => {
1626 span_mirbug!(self, block_data, "resume on non-cleanup block!")
1629 TerminatorKind::Abort => {
1631 span_mirbug!(self, block_data, "abort on non-cleanup block!")
1634 TerminatorKind::Return => {
1636 span_mirbug!(self, block_data, "return on cleanup block")
1639 TerminatorKind::GeneratorDrop { .. } => {
1641 span_mirbug!(self, block_data, "generator_drop in cleanup block")
1644 TerminatorKind::Yield { resume, drop, .. } => {
1646 span_mirbug!(self, block_data, "yield in cleanup block")
1648 self.assert_iscleanup(body, block_data, resume, is_cleanup);
1649 if let Some(drop) = drop {
1650 self.assert_iscleanup(body, block_data, drop, is_cleanup);
1653 TerminatorKind::Unreachable => {}
1654 TerminatorKind::Drop { target, unwind, .. }
1655 | TerminatorKind::DropAndReplace { target, unwind, .. }
1656 | TerminatorKind::Assert { target, cleanup: unwind, .. } => {
1657 self.assert_iscleanup(body, block_data, target, is_cleanup);
1658 if let Some(unwind) = unwind {
1660 span_mirbug!(self, block_data, "unwind on cleanup block")
1662 self.assert_iscleanup(body, block_data, unwind, true);
1665 TerminatorKind::Call { ref target, cleanup, .. } => {
1666 if let &Some(target) = target {
1667 self.assert_iscleanup(body, block_data, target, is_cleanup);
1669 if let Some(cleanup) = cleanup {
1671 span_mirbug!(self, block_data, "cleanup on cleanup block")
1673 self.assert_iscleanup(body, block_data, cleanup, true);
1676 TerminatorKind::FalseEdge { real_target, imaginary_target } => {
1677 self.assert_iscleanup(body, block_data, real_target, is_cleanup);
1678 self.assert_iscleanup(body, block_data, imaginary_target, is_cleanup);
1680 TerminatorKind::FalseUnwind { real_target, unwind } => {
1681 self.assert_iscleanup(body, block_data, real_target, is_cleanup);
1682 if let Some(unwind) = unwind {
1684 span_mirbug!(self, block_data, "cleanup in cleanup block via false unwind");
1686 self.assert_iscleanup(body, block_data, unwind, true);
1689 TerminatorKind::InlineAsm { destination, cleanup, .. } => {
1690 if let Some(target) = destination {
1691 self.assert_iscleanup(body, block_data, target, is_cleanup);
1693 if let Some(cleanup) = cleanup {
1695 span_mirbug!(self, block_data, "cleanup on cleanup block")
1697 self.assert_iscleanup(body, block_data, cleanup, true);
1703 fn assert_iscleanup(
1706 ctxt: &dyn fmt::Debug,
1710 if body[bb].is_cleanup != iscleanuppad {
1711 span_mirbug!(self, ctxt, "cleanuppad mismatch: {:?} should be {:?}", bb, iscleanuppad);
1715 fn check_local(&mut self, body: &Body<'tcx>, local: Local, local_decl: &LocalDecl<'tcx>) {
1716 match body.local_kind(local) {
1717 LocalKind::ReturnPointer | LocalKind::Arg => {
1718 // return values of normal functions are required to be
1719 // sized by typeck, but return values of ADT constructors are
1720 // not because we don't include a `Self: Sized` bounds on them.
1722 // Unbound parts of arguments were never required to be Sized
1723 // - maybe we should make that a warning.
1726 LocalKind::Var | LocalKind::Temp => {}
1729 // When `unsized_fn_params` or `unsized_locals` is enabled, only function calls
1730 // and nullary ops are checked in `check_call_dest`.
1731 if !self.unsized_feature_enabled() {
1732 let span = local_decl.source_info.span;
1733 let ty = local_decl.ty;
1734 self.ensure_place_sized(ty, span);
1738 fn ensure_place_sized(&mut self, ty: Ty<'tcx>, span: Span) {
1739 let tcx = self.tcx();
1741 // Erase the regions from `ty` to get a global type. The
1742 // `Sized` bound in no way depends on precise regions, so this
1743 // shouldn't affect `is_sized`.
1744 let erased_ty = tcx.erase_regions(ty);
1745 if !erased_ty.is_sized(tcx.at(span), self.param_env) {
1746 // in current MIR construction, all non-control-flow rvalue
1747 // expressions evaluate through `as_temp` or `into` a return
1748 // slot or local, so to find all unsized rvalues it is enough
1749 // to check all temps, return slots and locals.
1750 if self.reported_errors.replace((ty, span)).is_none() {
1751 let mut diag = struct_span_err!(
1755 "cannot move a value of type {0}: the size of {0} \
1756 cannot be statically determined",
1760 // While this is located in `nll::typeck` this error is not
1761 // an NLL error, it's a required check to prevent creation
1762 // of unsized rvalues in a call expression.
1768 fn aggregate_field_ty(
1770 ak: &AggregateKind<'tcx>,
1773 ) -> Result<Ty<'tcx>, FieldAccessError> {
1774 let tcx = self.tcx();
1777 AggregateKind::Adt(adt_did, variant_index, substs, _, active_field_index) => {
1778 let def = tcx.adt_def(adt_did);
1779 let variant = &def.variant(variant_index);
1780 let adj_field_index = active_field_index.unwrap_or(field_index);
1781 if let Some(field) = variant.fields.get(adj_field_index) {
1782 Ok(self.normalize(field.ty(tcx, substs), location))
1784 Err(FieldAccessError::OutOfRange { field_count: variant.fields.len() })
1787 AggregateKind::Closure(_, substs) => {
1788 match substs.as_closure().upvar_tys().nth(field_index) {
1790 None => Err(FieldAccessError::OutOfRange {
1791 field_count: substs.as_closure().upvar_tys().count(),
1795 AggregateKind::Generator(_, substs, _) => {
1796 // It doesn't make sense to look at a field beyond the prefix;
1797 // these require a variant index, and are not initialized in
1798 // aggregate rvalues.
1799 match substs.as_generator().prefix_tys().nth(field_index) {
1801 None => Err(FieldAccessError::OutOfRange {
1802 field_count: substs.as_generator().prefix_tys().count(),
1806 AggregateKind::Array(ty) => Ok(ty),
1807 AggregateKind::Tuple => {
1808 unreachable!("This should have been covered in check_rvalues");
1813 fn check_operand(&mut self, op: &Operand<'tcx>, location: Location) {
1814 if let Operand::Constant(constant) = op {
1815 let maybe_uneval = match constant.literal {
1816 ConstantKind::Ty(ct) => match ct.val() {
1817 ty::ConstKind::Unevaluated(uv) => Some(uv),
1822 if let Some(uv) = maybe_uneval {
1823 if uv.promoted.is_none() {
1824 let tcx = self.tcx();
1825 let def_id = uv.def.def_id_for_type_of();
1826 if tcx.def_kind(def_id) == DefKind::InlineConst {
1827 let predicates = self.prove_closure_bounds(
1829 def_id.expect_local(),
1833 self.normalize_and_prove_instantiated_predicates(
1836 location.to_locations(),
1844 fn check_rvalue(&mut self, body: &Body<'tcx>, rvalue: &Rvalue<'tcx>, location: Location) {
1845 let tcx = self.tcx();
1848 Rvalue::Aggregate(ak, ops) => {
1850 self.check_operand(op, location);
1852 self.check_aggregate_rvalue(&body, rvalue, ak, ops, location)
1855 Rvalue::Repeat(operand, len) => {
1856 self.check_operand(operand, location);
1858 // If the length cannot be evaluated we must assume that the length can be larger
1860 // If the length is larger than 1, the repeat expression will need to copy the
1861 // element, so we require the `Copy` trait.
1862 if len.try_eval_usize(tcx, self.param_env).map_or(true, |len| len > 1) {
1864 Operand::Copy(..) | Operand::Constant(..) => {
1865 // These are always okay: direct use of a const, or a value that can evidently be copied.
1867 Operand::Move(place) => {
1868 // Make sure that repeated elements implement `Copy`.
1869 let span = body.source_info(location).span;
1870 let ty = place.ty(body, tcx).ty;
1871 let trait_ref = ty::TraitRef::new(
1872 tcx.require_lang_item(LangItem::Copy, Some(span)),
1873 tcx.mk_substs_trait(ty, &[]),
1876 self.prove_trait_ref(
1878 Locations::Single(location),
1879 ConstraintCategory::CopyBound,
1886 &Rvalue::NullaryOp(_, ty) => {
1887 let trait_ref = ty::TraitRef {
1888 def_id: tcx.require_lang_item(LangItem::Sized, Some(self.last_span)),
1889 substs: tcx.mk_substs_trait(ty, &[]),
1892 self.prove_trait_ref(
1894 location.to_locations(),
1895 ConstraintCategory::SizedBound,
1899 Rvalue::ShallowInitBox(operand, ty) => {
1900 self.check_operand(operand, location);
1902 let trait_ref = ty::TraitRef {
1903 def_id: tcx.require_lang_item(LangItem::Sized, Some(self.last_span)),
1904 substs: tcx.mk_substs_trait(*ty, &[]),
1907 self.prove_trait_ref(
1909 location.to_locations(),
1910 ConstraintCategory::SizedBound,
1914 Rvalue::Cast(cast_kind, op, ty) => {
1915 self.check_operand(op, location);
1918 CastKind::Pointer(PointerCast::ReifyFnPointer) => {
1919 let fn_sig = op.ty(body, tcx).fn_sig(tcx);
1921 // The type that we see in the fcx is like
1922 // `foo::<'a, 'b>`, where `foo` is the path to a
1923 // function definition. When we extract the
1924 // signature, it comes from the `fn_sig` query,
1925 // and hence may contain unnormalized results.
1926 let fn_sig = self.normalize(fn_sig, location);
1928 let ty_fn_ptr_from = tcx.mk_fn_ptr(fn_sig);
1930 if let Err(terr) = self.eq_types(
1933 location.to_locations(),
1934 ConstraintCategory::Cast,
1939 "equating {:?} with {:?} yields {:?}",
1947 CastKind::Pointer(PointerCast::ClosureFnPointer(unsafety)) => {
1948 let sig = match op.ty(body, tcx).kind() {
1949 ty::Closure(_, substs) => substs.as_closure().sig(),
1952 let ty_fn_ptr_from = tcx.mk_fn_ptr(tcx.signature_unclosure(sig, *unsafety));
1954 if let Err(terr) = self.eq_types(
1957 location.to_locations(),
1958 ConstraintCategory::Cast,
1963 "equating {:?} with {:?} yields {:?}",
1971 CastKind::Pointer(PointerCast::UnsafeFnPointer) => {
1972 let fn_sig = op.ty(body, tcx).fn_sig(tcx);
1974 // The type that we see in the fcx is like
1975 // `foo::<'a, 'b>`, where `foo` is the path to a
1976 // function definition. When we extract the
1977 // signature, it comes from the `fn_sig` query,
1978 // and hence may contain unnormalized results.
1979 let fn_sig = self.normalize(fn_sig, location);
1981 let ty_fn_ptr_from = tcx.safe_to_unsafe_fn_ty(fn_sig);
1983 if let Err(terr) = self.eq_types(
1986 location.to_locations(),
1987 ConstraintCategory::Cast,
1992 "equating {:?} with {:?} yields {:?}",
2000 CastKind::Pointer(PointerCast::Unsize) => {
2002 let trait_ref = ty::TraitRef {
2004 .require_lang_item(LangItem::CoerceUnsized, Some(self.last_span)),
2005 substs: tcx.mk_substs_trait(op.ty(body, tcx), &[ty.into()]),
2008 self.prove_trait_ref(
2010 location.to_locations(),
2011 ConstraintCategory::Cast,
2015 CastKind::Pointer(PointerCast::MutToConstPointer) => {
2016 let ty::RawPtr(ty::TypeAndMut {
2018 mutbl: hir::Mutability::Mut,
2019 }) = op.ty(body, tcx).kind() else {
2023 "unexpected base type for cast {:?}",
2028 let ty::RawPtr(ty::TypeAndMut {
2030 mutbl: hir::Mutability::Not,
2031 }) = ty.kind() else {
2035 "unexpected target type for cast {:?}",
2040 if let Err(terr) = self.sub_types(
2043 location.to_locations(),
2044 ConstraintCategory::Cast,
2049 "relating {:?} with {:?} yields {:?}",
2057 CastKind::Pointer(PointerCast::ArrayToPointer) => {
2058 let ty_from = op.ty(body, tcx);
2060 let opt_ty_elem_mut = match ty_from.kind() {
2061 ty::RawPtr(ty::TypeAndMut { mutbl: array_mut, ty: array_ty }) => {
2062 match array_ty.kind() {
2063 ty::Array(ty_elem, _) => Some((ty_elem, *array_mut)),
2070 let Some((ty_elem, ty_mut)) = opt_ty_elem_mut else {
2074 "ArrayToPointer cast from unexpected type {:?}",
2080 let (ty_to, ty_to_mut) = match ty.kind() {
2081 ty::RawPtr(ty::TypeAndMut { mutbl: ty_to_mut, ty: ty_to }) => {
2088 "ArrayToPointer cast to unexpected type {:?}",
2095 if ty_to_mut == Mutability::Mut && ty_mut == Mutability::Not {
2099 "ArrayToPointer cast from const {:?} to mut {:?}",
2106 if let Err(terr) = self.sub_types(
2109 location.to_locations(),
2110 ConstraintCategory::Cast,
2115 "relating {:?} with {:?} yields {:?}",
2124 let ty_from = op.ty(body, tcx);
2125 let cast_ty_from = CastTy::from_ty(ty_from);
2126 let cast_ty_to = CastTy::from_ty(*ty);
2127 match (cast_ty_from, cast_ty_to) {
2129 | (_, None | Some(CastTy::FnPtr))
2130 | (Some(CastTy::Float), Some(CastTy::Ptr(_)))
2131 | (Some(CastTy::Ptr(_) | CastTy::FnPtr), Some(CastTy::Float)) => {
2132 span_mirbug!(self, rvalue, "Invalid cast {:?} -> {:?}", ty_from, ty,)
2135 Some(CastTy::Int(_)),
2136 Some(CastTy::Int(_) | CastTy::Float | CastTy::Ptr(_)),
2138 | (Some(CastTy::Float), Some(CastTy::Int(_) | CastTy::Float))
2139 | (Some(CastTy::Ptr(_)), Some(CastTy::Int(_) | CastTy::Ptr(_)))
2140 | (Some(CastTy::FnPtr), Some(CastTy::Int(_) | CastTy::Ptr(_))) => (),
2146 Rvalue::Ref(region, _borrow_kind, borrowed_place) => {
2147 self.add_reborrow_constraint(&body, location, *region, borrowed_place);
2151 BinOp::Eq | BinOp::Ne | BinOp::Lt | BinOp::Le | BinOp::Gt | BinOp::Ge,
2154 self.check_operand(left, location);
2155 self.check_operand(right, location);
2157 let ty_left = left.ty(body, tcx);
2158 match ty_left.kind() {
2159 // Types with regions are comparable if they have a common super-type.
2160 ty::RawPtr(_) | ty::FnPtr(_) => {
2161 let ty_right = right.ty(body, tcx);
2162 let common_ty = self.infcx.next_ty_var(TypeVariableOrigin {
2163 kind: TypeVariableOriginKind::MiscVariable,
2164 span: body.source_info(location).span,
2169 location.to_locations(),
2170 ConstraintCategory::Boring,
2172 .unwrap_or_else(|err| {
2173 bug!("Could not equate type variable with {:?}: {:?}", ty_left, err)
2175 if let Err(terr) = self.sub_types(
2178 location.to_locations(),
2179 ConstraintCategory::Boring,
2184 "unexpected comparison types {:?} and {:?} yields {:?}",
2191 // For types with no regions we can just check that the
2192 // both operands have the same type.
2193 ty::Int(_) | ty::Uint(_) | ty::Bool | ty::Char | ty::Float(_)
2194 if ty_left == right.ty(body, tcx) => {}
2195 // Other types are compared by trait methods, not by
2196 // `Rvalue::BinaryOp`.
2200 "unexpected comparison types {:?} and {:?}",
2207 Rvalue::Use(operand) | Rvalue::UnaryOp(_, operand) => {
2208 self.check_operand(operand, location);
2211 Rvalue::BinaryOp(_, box (left, right))
2212 | Rvalue::CheckedBinaryOp(_, box (left, right)) => {
2213 self.check_operand(left, location);
2214 self.check_operand(right, location);
2217 Rvalue::AddressOf(..)
2218 | Rvalue::ThreadLocalRef(..)
2220 | Rvalue::Discriminant(..) => {}
2224 /// If this rvalue supports a user-given type annotation, then
2225 /// extract and return it. This represents the final type of the
2226 /// rvalue and will be unified with the inferred type.
2227 fn rvalue_user_ty(&self, rvalue: &Rvalue<'tcx>) -> Option<UserTypeAnnotationIndex> {
2230 | Rvalue::ThreadLocalRef(_)
2231 | Rvalue::Repeat(..)
2233 | Rvalue::AddressOf(..)
2236 | Rvalue::ShallowInitBox(..)
2237 | Rvalue::BinaryOp(..)
2238 | Rvalue::CheckedBinaryOp(..)
2239 | Rvalue::NullaryOp(..)
2240 | Rvalue::UnaryOp(..)
2241 | Rvalue::Discriminant(..) => None,
2243 Rvalue::Aggregate(aggregate, _) => match **aggregate {
2244 AggregateKind::Adt(_, _, _, user_ty, _) => user_ty,
2245 AggregateKind::Array(_) => None,
2246 AggregateKind::Tuple => None,
2247 AggregateKind::Closure(_, _) => None,
2248 AggregateKind::Generator(_, _, _) => None,
2253 fn check_aggregate_rvalue(
2256 rvalue: &Rvalue<'tcx>,
2257 aggregate_kind: &AggregateKind<'tcx>,
2258 operands: &[Operand<'tcx>],
2261 let tcx = self.tcx();
2263 self.prove_aggregate_predicates(aggregate_kind, location);
2265 if *aggregate_kind == AggregateKind::Tuple {
2266 // tuple rvalue field type is always the type of the op. Nothing to check here.
2270 for (i, operand) in operands.iter().enumerate() {
2271 let field_ty = match self.aggregate_field_ty(aggregate_kind, i, location) {
2272 Ok(field_ty) => field_ty,
2273 Err(FieldAccessError::OutOfRange { field_count }) => {
2277 "accessed field #{} but variant only has {}",
2284 let operand_ty = operand.ty(body, tcx);
2285 let operand_ty = self.normalize(operand_ty, location);
2287 if let Err(terr) = self.sub_types(
2290 location.to_locations(),
2291 ConstraintCategory::Boring,
2296 "{:?} is not a subtype of {:?}: {:?}",
2305 /// Adds the constraints that arise from a borrow expression `&'a P` at the location `L`.
2309 /// - `location`: the location `L` where the borrow expression occurs
2310 /// - `borrow_region`: the region `'a` associated with the borrow
2311 /// - `borrowed_place`: the place `P` being borrowed
2312 fn add_reborrow_constraint(
2316 borrow_region: ty::Region<'tcx>,
2317 borrowed_place: &Place<'tcx>,
2319 // These constraints are only meaningful during borrowck:
2320 let BorrowCheckContext { borrow_set, location_table, all_facts, constraints, .. } =
2321 self.borrowck_context;
2323 // In Polonius mode, we also push a `loan_issued_at` fact
2324 // linking the loan to the region (in some cases, though,
2325 // there is no loan associated with this borrow expression --
2326 // that occurs when we are borrowing an unsafe place, for
2328 if let Some(all_facts) = all_facts {
2329 let _prof_timer = self.infcx.tcx.prof.generic_activity("polonius_fact_generation");
2330 if let Some(borrow_index) = borrow_set.get_index_of(&location) {
2331 let region_vid = borrow_region.to_region_vid();
2332 all_facts.loan_issued_at.push((
2335 location_table.mid_index(location),
2340 // If we are reborrowing the referent of another reference, we
2341 // need to add outlives relationships. In a case like `&mut
2342 // *p`, where the `p` has type `&'b mut Foo`, for example, we
2343 // need to ensure that `'b: 'a`.
2346 "add_reborrow_constraint({:?}, {:?}, {:?})",
2347 location, borrow_region, borrowed_place
2350 let mut cursor = borrowed_place.projection.as_ref();
2351 let tcx = self.infcx.tcx;
2352 let field = path_utils::is_upvar_field_projection(
2354 &self.borrowck_context.upvars,
2355 borrowed_place.as_ref(),
2358 let category = if let Some(field) = field {
2359 ConstraintCategory::ClosureUpvar(field)
2361 ConstraintCategory::Boring
2364 while let [proj_base @ .., elem] = cursor {
2367 debug!("add_reborrow_constraint - iteration {:?}", elem);
2370 ProjectionElem::Deref => {
2371 let base_ty = Place::ty_from(borrowed_place.local, proj_base, body, tcx).ty;
2373 debug!("add_reborrow_constraint - base_ty = {:?}", base_ty);
2374 match base_ty.kind() {
2375 ty::Ref(ref_region, _, mutbl) => {
2376 constraints.outlives_constraints.push(OutlivesConstraint {
2377 sup: ref_region.to_region_vid(),
2378 sub: borrow_region.to_region_vid(),
2379 locations: location.to_locations(),
2380 span: location.to_locations().span(body),
2382 variance_info: ty::VarianceDiagInfo::default(),
2386 hir::Mutability::Not => {
2387 // Immutable reference. We don't need the base
2388 // to be valid for the entire lifetime of
2392 hir::Mutability::Mut => {
2393 // Mutable reference. We *do* need the base
2394 // to be valid, because after the base becomes
2395 // invalid, someone else can use our mutable deref.
2397 // This is in order to make the following function
2400 // fn unsafe_deref<'a, 'b>(x: &'a &'b mut T) -> &'b mut T {
2405 // As otherwise you could clone `&mut T` using the
2406 // following function:
2408 // fn bad(x: &mut T) -> (&mut T, &mut T) {
2409 // let my_clone = unsafe_deref(&'a x);
2418 // deref of raw pointer, guaranteed to be valid
2421 ty::Adt(def, _) if def.is_box() => {
2422 // deref of `Box`, need the base to be valid - propagate
2424 _ => bug!("unexpected deref ty {:?} in {:?}", base_ty, borrowed_place),
2427 ProjectionElem::Field(..)
2428 | ProjectionElem::Downcast(..)
2429 | ProjectionElem::Index(..)
2430 | ProjectionElem::ConstantIndex { .. }
2431 | ProjectionElem::Subslice { .. } => {
2432 // other field access
2438 fn prove_aggregate_predicates(
2440 aggregate_kind: &AggregateKind<'tcx>,
2443 let tcx = self.tcx();
2446 "prove_aggregate_predicates(aggregate_kind={:?}, location={:?})",
2447 aggregate_kind, location
2450 let (def_id, instantiated_predicates) = match aggregate_kind {
2451 AggregateKind::Adt(adt_did, _, substs, _, _) => {
2452 (*adt_did, tcx.predicates_of(*adt_did).instantiate(tcx, substs))
2455 // For closures, we have some **extra requirements** we
2457 // have to check. In particular, in their upvars and
2458 // signatures, closures often reference various regions
2459 // from the surrounding function -- we call those the
2460 // closure's free regions. When we borrow-check (and hence
2461 // region-check) closures, we may find that the closure
2462 // requires certain relationships between those free
2463 // regions. However, because those free regions refer to
2464 // portions of the CFG of their caller, the closure is not
2465 // in a position to verify those relationships. In that
2466 // case, the requirements get "propagated" to us, and so
2467 // we have to solve them here where we instantiate the
2470 // Despite the opacity of the previous paragraph, this is
2471 // actually relatively easy to understand in terms of the
2472 // desugaring. A closure gets desugared to a struct, and
2473 // these extra requirements are basically like where
2474 // clauses on the struct.
2475 AggregateKind::Closure(def_id, substs)
2476 | AggregateKind::Generator(def_id, substs, _) => {
2477 (*def_id, self.prove_closure_bounds(tcx, def_id.expect_local(), substs, location))
2480 AggregateKind::Array(_) | AggregateKind::Tuple => {
2481 (CRATE_DEF_ID.to_def_id(), ty::InstantiatedPredicates::empty())
2485 self.normalize_and_prove_instantiated_predicates(
2487 instantiated_predicates,
2488 location.to_locations(),
2492 fn prove_closure_bounds(
2496 substs: SubstsRef<'tcx>,
2498 ) -> ty::InstantiatedPredicates<'tcx> {
2499 if let Some(ref closure_region_requirements) = tcx.mir_borrowck(def_id).closure_requirements
2501 let closure_constraints = QueryRegionConstraints {
2502 outlives: closure_region_requirements.apply_requirements(
2508 // Presently, closures never propagate member
2509 // constraints to their parents -- they are enforced
2510 // locally. This is largely a non-issue as member
2511 // constraints only come from `-> impl Trait` and
2512 // friends which don't appear (thus far...) in
2514 member_constraints: vec![],
2517 let bounds_mapping = closure_constraints
2521 .filter_map(|(idx, constraint)| {
2522 let ty::OutlivesPredicate(k1, r2) =
2523 constraint.no_bound_vars().unwrap_or_else(|| {
2524 bug!("query_constraint {:?} contained bound vars", constraint,);
2528 GenericArgKind::Lifetime(r1) => {
2529 // constraint is r1: r2
2530 let r1_vid = self.borrowck_context.universal_regions.to_region_vid(r1);
2531 let r2_vid = self.borrowck_context.universal_regions.to_region_vid(r2);
2532 let outlives_requirements =
2533 &closure_region_requirements.outlives_requirements[idx];
2536 (outlives_requirements.category, outlives_requirements.blame_span),
2539 GenericArgKind::Type(_) | GenericArgKind::Const(_) => None,
2547 .closure_bounds_mapping
2548 .insert(location, bounds_mapping);
2549 assert!(existing.is_none(), "Multiple closures at the same location.");
2551 self.push_region_constraints(
2552 location.to_locations(),
2553 ConstraintCategory::ClosureBounds,
2554 &closure_constraints,
2558 tcx.predicates_of(def_id).instantiate(tcx, substs)
2561 #[instrument(skip(self, body), level = "debug")]
2562 fn typeck_mir(&mut self, body: &Body<'tcx>) {
2563 self.last_span = body.span;
2566 for (local, local_decl) in body.local_decls.iter_enumerated() {
2567 self.check_local(&body, local, local_decl);
2570 for (block, block_data) in body.basic_blocks().iter_enumerated() {
2571 let mut location = Location { block, statement_index: 0 };
2572 for stmt in &block_data.statements {
2573 if !stmt.source_info.span.is_dummy() {
2574 self.last_span = stmt.source_info.span;
2576 self.check_stmt(body, stmt, location);
2577 location.statement_index += 1;
2580 self.check_terminator(&body, block_data.terminator(), location);
2581 self.check_iscleanup(&body, block_data);
2586 trait NormalizeLocation: fmt::Debug + Copy {
2587 fn to_locations(self) -> Locations;
2590 impl NormalizeLocation for Locations {
2591 fn to_locations(self) -> Locations {
2596 impl NormalizeLocation for Location {
2597 fn to_locations(self) -> Locations {
2598 Locations::Single(self)
2602 /// Runs `infcx.instantiate_opaque_types`. Unlike other `TypeOp`s,
2603 /// this is not canonicalized - it directly affects the main `InferCtxt`
2604 /// that we use during MIR borrowchecking.
2606 pub(super) struct InstantiateOpaqueType<'tcx> {
2607 pub base_universe: Option<ty::UniverseIndex>,
2608 pub region_constraints: Option<RegionConstraintData<'tcx>>,
2609 pub obligations: Vec<PredicateObligation<'tcx>>,
2612 impl<'tcx> TypeOp<'tcx> for InstantiateOpaqueType<'tcx> {
2614 /// We use this type itself to store the information used
2615 /// when reporting errors. Since this is not a query, we don't
2616 /// re-run anything during error reporting - we just use the information
2617 /// we saved to help extract an error from the already-existing region
2618 /// constraints in our `InferCtxt`
2619 type ErrorInfo = InstantiateOpaqueType<'tcx>;
2621 fn fully_perform(mut self, infcx: &InferCtxt<'_, 'tcx>) -> Fallible<TypeOpOutput<'tcx, Self>> {
2622 let (mut output, region_constraints) = scrape_region_constraints(infcx, || {
2623 Ok(InferOk { value: (), obligations: self.obligations.clone() })
2625 self.region_constraints = Some(region_constraints);
2626 output.error_info = Some(self);