--- /dev/null
+//! 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_data_structures::vec_map::VecMap;
+use rustc_errors::struct_span_err;
+use rustc_hir as hir;
+use rustc_hir::def_id::LocalDefId;
+use rustc_hir::lang_items::LangItem;
+use rustc_index::vec::{Idx, IndexVec};
+use rustc_infer::infer::canonical::QueryRegionConstraints;
+use rustc_infer::infer::opaque_types::OpaqueTypeDecl;
+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, SubstsRef, UserSubsts};
+use rustc_middle::ty::{
+ self, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, OpaqueTypeKey, RegionVid,
+ ToPredicate, Ty, TyCtxt, UserType, UserTypeAnnotationIndex, WithConstness,
+};
+use rustc_span::def_id::CRATE_DEF_ID;
+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;
+use rustc_trait_selection::traits::{self, ObligationCause, PredicateObligations};
+
+use rustc_const_eval::transform::{
+ check_consts::ConstCx, promote_consts::is_const_fn_in_array_repeat_expression,
+};
+use rustc_mir_dataflow::impls::MaybeInitializedPlaces;
+use rustc_mir_dataflow::move_paths::MoveData;
+use rustc_mir_dataflow::ResultsCursor;
+
+use crate::{
+ borrow_set::BorrowSet,
+ constraints::{OutlivesConstraint, OutlivesConstraintSet},
+ diagnostics::UniverseInfo,
+ facts::AllFacts,
+ location::LocationTable,
+ member_constraints::MemberConstraintSet,
+ nll::ToRegionVid,
+ path_utils,
+ region_infer::values::{
+ LivenessValues, PlaceholderIndex, PlaceholderIndices, RegionValueElements,
+ },
+ region_infer::{ClosureRegionRequirementsExt, TypeTest},
+ type_check::free_region_relations::{CreateResult, UniversalRegionRelations},
+ universal_regions::{DefiningTy, UniversalRegions},
+ Upvar,
+};
+
+macro_rules! span_mirbug {
+ ($context:expr, $elem:expr, $($message:tt)*) => ({
+ $crate::type_check::mirbug(
+ $context.tcx(),
+ $context.last_span,
+ &format!(
+ "broken MIR in {:?} ({:?}): {}",
+ $context.body.source.def_id(),
+ $elem,
+ format_args!($($message)*),
+ ),
+ )
+ })
+}
+
+macro_rules! span_mirbug_and_err {
+ ($context:expr, $elem:expr, $($message:tt)*) => ({
+ {
+ span_mirbug!($context, $elem, $($message)*);
+ $context.error()
+ }
+ })
+}
+
+mod canonical;
+mod constraint_conversion;
+pub mod free_region_relations;
+mod input_output;
+crate mod liveness;
+mod relate_tys;
+
+/// Type checks the given `mir` in the context of the inference
+/// context `infcx`. Returns any region constraints that have yet to
+/// be proven. This result includes liveness constraints that
+/// ensure that regions appearing in the types of all local variables
+/// are live at all points where that local variable may later be
+/// used.
+///
+/// This phase of type-check ought to be infallible -- this is because
+/// the original, HIR-based type-check succeeded. So if any errors
+/// occur here, we will get a `bug!` reported.
+///
+/// # Parameters
+///
+/// - `infcx` -- inference context to use
+/// - `param_env` -- parameter environment to use for trait solving
+/// - `body` -- MIR body to type-check
+/// - `promoted` -- map of promoted constants within `body`
+/// - `universal_regions` -- the universal regions from `body`s function signature
+/// - `location_table` -- MIR location map of `body`
+/// - `borrow_set` -- information about borrows occurring in `body`
+/// - `all_facts` -- when using Polonius, this is the generated set of Polonius facts
+/// - `flow_inits` -- results of a maybe-init dataflow analysis
+/// - `move_data` -- move-data constructed when performing the maybe-init dataflow analysis
+/// - `elements` -- MIR region map
+pub(crate) fn type_check<'mir, 'tcx>(
+ infcx: &InferCtxt<'_, 'tcx>,
+ param_env: ty::ParamEnv<'tcx>,
+ body: &Body<'tcx>,
+ promoted: &IndexVec<Promoted, Body<'tcx>>,
+ universal_regions: &Rc<UniversalRegions<'tcx>>,
+ location_table: &LocationTable,
+ borrow_set: &BorrowSet<'tcx>,
+ all_facts: &mut Option<AllFacts>,
+ flow_inits: &mut ResultsCursor<'mir, 'tcx, MaybeInitializedPlaces<'mir, 'tcx>>,
+ move_data: &MoveData<'tcx>,
+ elements: &Rc<RegionValueElements>,
+ upvars: &[Upvar<'tcx>],
+) -> MirTypeckResults<'tcx> {
+ let implicit_region_bound = infcx.tcx.mk_region(ty::ReVar(universal_regions.fr_fn_body));
+ let mut universe_causes = FxHashMap::default();
+ universe_causes.insert(ty::UniverseIndex::from_u32(0), UniverseInfo::other());
+ 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(),
+ universe_causes,
+ };
+
+ 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,
+ );
+
+ for u in ty::UniverseIndex::ROOT..infcx.universe() {
+ let info = UniverseInfo::other();
+ constraints.universe_causes.insert(u, info);
+ }
+
+ 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,
+ 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);
+ let opaque_type_values = mem::take(&mut infcx.inner.borrow_mut().opaque_types);
+
+ opaque_type_values
+ .into_iter()
+ .filter_map(|(opaque_type_key, mut decl)| {
+ decl.concrete_ty = infcx.resolve_vars_if_possible(decl.concrete_ty);
+ trace!(
+ "finalized opaque type {:?} to {:#?}",
+ opaque_type_key,
+ decl.concrete_ty.kind()
+ );
+ if decl.concrete_ty.has_infer_types_or_consts() {
+ infcx.tcx.sess.delay_span_bug(
+ body.span,
+ &format!("could not resolve {:#?}", decl.concrete_ty.kind()),
+ );
+ decl.concrete_ty = infcx.tcx.ty_error();
+ }
+ let concrete_is_opaque = if let ty::Opaque(def_id, _) = decl.concrete_ty.kind()
+ {
+ *def_id == opaque_type_key.def_id
+ } else {
+ false
+ };
+
+ if concrete_is_opaque {
+ // 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_type_key.def_id,
+ );
+ None
+ } else {
+ Some((opaque_type_key, decl))
+ }
+ })
+ .collect()
+ },
+ );
+
+ MirTypeckResults { constraints, universal_region_relations, opaque_type_values }
+}
+
+#[instrument(
+ skip(
+ infcx,
+ body,
+ promoted,
+ region_bound_pairs,
+ borrowck_context,
+ universal_region_relations,
+ extra
+ ),
+ level = "debug"
+)]
+fn type_check_internal<'a, 'tcx, R>(
+ infcx: &'a InferCtxt<'a, 'tcx>,
+ param_env: ty::ParamEnv<'tcx>,
+ body: &'a Body<'tcx>,
+ promoted: &'a IndexVec<Promoted, Body<'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>,
+ extra: impl FnOnce(TypeChecker<'a, 'tcx>) -> R,
+) -> R {
+ let mut checker = TypeChecker::new(
+ infcx,
+ body,
+ 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.subset_base.extend(cx.constraints.outlives_constraints.outlives().iter().flat_map(
+ |constraint: &OutlivesConstraint<'_>| {
+ if let Some(from_location) = constraint.locations.from_location() {
+ Either::Left(iter::once((
+ constraint.sup,
+ constraint.sub,
+ location_table.mid_index(from_location),
+ )))
+ } else {
+ Either::Right(
+ location_table
+ .all_points()
+ .map(move |location| (constraint.sup, constraint.sub, location)),
+ )
+ }
+ },
+ ));
+ }
+}
+
+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<Promoted, Body<'tcx>>,
+ last_span: Span,
+ errors_reported: bool,
+}
+
+impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> {
+ fn visit_span(&mut self, span: &Span) {
+ if !span.is_dummy() {
+ self.last_span = *span;
+ }
+ }
+
+ fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, location: Location) {
+ self.sanitize_place(place, location, context);
+ }
+
+ fn visit_constant(&mut self, constant: &Constant<'tcx>, location: Location) {
+ 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();
+ let maybe_uneval = match constant.literal {
+ ConstantKind::Ty(ct) => match ct.val {
+ ty::ConstKind::Unevaluated(uv) => Some(uv),
+ _ => None,
+ },
+ _ => None,
+ };
+ if let Some(uv) = maybe_uneval {
+ if let Some(promoted) = uv.promoted {
+ let check_err = |verifier: &mut TypeVerifier<'a, 'b, 'tcx>,
+ promoted: &Body<'tcx>,
+ ty,
+ san_ty| {
+ if let Err(terr) = verifier.cx.eq_types(
+ ty,
+ san_ty,
+ 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(),
+ uv.def.did,
+ UserSubsts { substs: uv.substs(self.tcx()), 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(
+ literal_ty,
+ normalized_ty,
+ locations,
+ ConstraintCategory::Boring,
+ ) {
+ span_mirbug!(self, constant, "bad static type {:?} ({:?})", constant, terr);
+ }
+ }
+
+ if let ty::FnDef(def_id, substs) = *constant.literal.ty().kind() {
+ let instantiated_predicates = tcx.predicates_of(def_id).instantiate(tcx, substs);
+ self.cx.normalize_and_prove_instantiated_predicates(
+ def_id,
+ 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<Promoted, Body<'tcx>>,
+ ) -> Self {
+ TypeVerifier { body, promoted, 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(LangItem::Copy, 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.clone();
+ constraint.locations = locations;
+ if let ConstraintCategory::Return(_)
+ | ConstraintCategory::UseAsConst
+ | ConstraintCategory::UseAsStatic = constraint.category
+ {
+ // "Returning" from a promoted is an assignment to a
+ // temporary from the user's point of view.
+ constraint.category = ConstraintCategory::Boring;
+ }
+ self.cx.borrowck_context.constraints.outlives_constraints.push(constraint)
+ }
+ for region in liveness_constraints.rows() {
+ // If the region is live at at least one location in the promoted MIR,
+ // then add a liveness constraint to the main MIR for this region
+ // at the location provided as an argument to this method
+ if let Some(_) = liveness_constraints.get_elements(region).next() {
+ self.cx
+ .borrowck_context
+ .constraints
+ .liveness_constraints
+ .add_element(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)
+ }
+ 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<Ty<'tcx>, 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()
+ .tupled_upvars_ty()
+ .tuple_element_ty(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>,
+ 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>,
+}
+
+struct BorrowCheckContext<'a, 'tcx> {
+ universal_regions: &'a UniversalRegions<'tcx>,
+ location_table: &'a LocationTable,
+ all_facts: &'a mut Option<AllFacts>,
+ borrow_set: &'a BorrowSet<'tcx>,
+ constraints: &'a mut MirTypeckRegionConstraints<'tcx>,
+ upvars: &'a [Upvar<'tcx>],
+}
+
+crate struct MirTypeckResults<'tcx> {
+ crate constraints: MirTypeckRegionConstraints<'tcx>,
+ crate universal_region_relations: Frozen<UniversalRegionRelations<'tcx>>,
+ crate opaque_type_values: VecMap<OpaqueTypeKey<'tcx>, OpaqueTypeDecl<'tcx>>,
+}
+
+/// 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<PlaceholderIndex, ty::Region<'tcx>>,
+
+ /// 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<RegionVid>,
+
+ crate outlives_constraints: OutlivesConstraintSet<'tcx>,
+
+ crate member_constraints: MemberConstraintSet<'tcx, RegionVid>,
+
+ crate closure_bounds_mapping:
+ FxHashMap<Location, FxHashMap<(RegionVid, RegionVid), (ConstraintCategory, Span)>>,
+
+ crate universe_causes: FxHashMap<ty::UniverseIndex, UniverseInfo<'tcx>>,
+
+ crate type_tests: Vec<TypeTest<'tcx>>,
+}
+
+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<Location> {
+ 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>,
+ 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,
+ 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,
+ };
+ checker.check_user_type_annotations();
+ checker
+ }
+
+ fn unsized_feature_enabled(&self) -> bool {
+ let features = self.tcx().features();
+ features.unsized_locals || features.unsized_fn_params
+ }
+
+ /// Equate the inferred type and the annotated type for user type annotations
+ 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 inferred_ty = self.normalize(inferred_ty, Locations::All(span));
+ let annotation = self.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::Binder::dummy(ty::PredicateKind::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({:?}, {:?} {:?}, type_of={:?}): {:?}",
+ inferred_ty,
+ def_id,
+ user_substs,
+ self.tcx().type_of(def_id),
+ terr,
+ );
+ }
+ }
+ }
+ }
+ }
+
+ #[instrument(skip(self, data), level = "debug")]
+ fn push_region_constraints(
+ &mut self,
+ locations: Locations,
+ category: ConstraintCategory,
+ data: &QueryRegionConstraints<'tcx>,
+ ) {
+ debug!("constraints generated: {:#?}", 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);
+ }
+
+ /// Try to relate `sub <: sup`
+ fn sub_types(
+ &mut self,
+ sub: Ty<'tcx>,
+ sup: Ty<'tcx>,
+ locations: Locations,
+ category: ConstraintCategory,
+ ) -> Fallible<()> {
+ // Use this order of parameters because the sup type is usually the
+ // "expected" type in diagnostics.
+ self.relate_types(sup, ty::Variance::Contravariant, sub, locations, category)
+ }
+
+ fn eq_types(
+ &mut self,
+ expected: Ty<'tcx>,
+ found: Ty<'tcx>,
+ locations: Locations,
+ category: ConstraintCategory,
+ ) -> Fallible<()> {
+ self.relate_types(expected, ty::Variance::Invariant, found, locations, category)
+ }
+
+ #[instrument(skip(self), level = "debug")]
+ fn relate_type_and_user_type(
+ &mut self,
+ a: Ty<'tcx>,
+ v: ty::Variance,
+ user_ty: &UserTypeProjection,
+ locations: Locations,
+ category: ConstraintCategory,
+ ) -> Fallible<()> {
+ 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(ty, v.xform(ty::Variance::Contravariant), a, locations, category)?;
+
+ Ok(())
+ }
+
+ /// Equates a type `anon_ty` that may contain opaque types whose
+ /// values are to be inferred by the MIR.
+ ///
+ /// The type `revealed_ty` contains the same type as `anon_ty`, but with the
+ /// hidden types for impl traits revealed.
+ ///
+ /// # Example
+ ///
+ /// Consider a piece of code like
+ ///
+ /// ```rust
+ /// type Foo<U> = impl Debug;
+ ///
+ /// fn foo<T: Debug>(t: T) -> Box<Foo<T>> {
+ /// Box::new((t, 22_u32))
+ /// }
+ /// ```
+ ///
+ /// Here, the function signature would be something like
+ /// `fn(T) -> Box<impl Debug>`. The MIR return slot would have
+ /// the type with the opaque type revealed, so `Box<(T, u32)>`.
+ ///
+ /// In terms of our function parameters:
+ ///
+ /// * `anon_ty` would be `Box<Foo<T>>` where `Foo<T>` is an opaque type
+ /// scoped to this function (note that it is parameterized by the
+ /// generics of `foo`). Note that `anon_ty` is not just the opaque type,
+ /// but the entire return type (which may contain opaque types within it).
+ /// * `revealed_ty` would be `Box<(T, u32)>`
+ #[instrument(skip(self), level = "debug")]
+ fn eq_opaque_type_and_type(
+ &mut self,
+ revealed_ty: Ty<'tcx>,
+ anon_ty: Ty<'tcx>,
+ locations: Locations,
+ category: ConstraintCategory,
+ ) -> Fallible<()> {
+ // 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 param_env = self.param_env;
+ let body = self.body;
+ let mir_def_id = body.source.def_id().expect_local();
+
+ debug!(?mir_def_id);
+ self.fully_perform_op(
+ locations,
+ category,
+ CustomTypeOp::new(
+ |infcx| {
+ let mut obligations = ObligationAccumulator::default();
+
+ let dummy_body_id = hir::CRATE_HIR_ID;
+
+ // Replace the opaque types defined by this function with
+ // inference variables, creating a map. In our example above,
+ // this would transform the type `Box<Foo<T>>` (where `Foo` is an opaque type)
+ // to `Box<?T>`, returning an `opaque_type_map` mapping `{Foo<T> -> ?T}`.
+ // (Note that the key of the map is both the def-id of `Foo` along with
+ // any generic parameters.)
+ let output_ty = obligations.add(infcx.instantiate_opaque_types(
+ dummy_body_id,
+ param_env,
+ anon_ty,
+ locations.span(body),
+ ));
+ debug!(?output_ty, ?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::Binder::dummy(ty::PredicateKind::WellFormed(revealed_ty.into()))
+ .to_predicate(infcx.tcx),
+ ));
+ obligations.add(
+ infcx
+ .at(&ObligationCause::dummy(), param_env)
+ .eq(output_ty, revealed_ty)?,
+ );
+
+ debug!("equated");
+
+ Ok(InferOk { value: (), obligations: obligations.into_vec() })
+ },
+ || "input_output".to_string(),
+ ),
+ )?;
+
+ 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).
+ let opaque_type_map = self.infcx.inner.borrow().opaque_types.clone();
+ for (opaque_type_key, opaque_decl) in opaque_type_map {
+ self.fully_perform_op(
+ locations,
+ ConstraintCategory::OpaqueType,
+ CustomTypeOp::new(
+ |infcx| {
+ infcx.constrain_opaque_type(
+ opaque_type_key,
+ &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
+ }
+
+ #[instrument(skip(self, body, location), level = "debug")]
+ fn check_stmt(&mut self, body: &Body<'tcx>, stmt: &Statement<'tcx>, location: Location) {
+ 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 matches!(
+ body.local_decls[l].local_info,
+ Some(box LocalInfo::AggregateTemp)
+ ) =>
+ {
+ ConstraintCategory::Usage
+ }
+ Some(l) if !body.local_decls[l].is_user_variable() => {
+ ConstraintCategory::Boring
+ }
+ _ => ConstraintCategory::Assignment,
+ };
+ debug!(
+ "assignment category: {:?} {:?}",
+ category,
+ place.as_local().map(|l| &body.local_decls[l])
+ );
+
+ let place_ty = place.ty(body, tcx).ty;
+ 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(rv_ty, place_ty, location.to_locations(), category)
+ {
+ span_mirbug!(
+ self,
+ stmt,
+ "bad assignment ({:?} = {:?}): {:?}",
+ place_ty,
+ rv_ty,
+ terr
+ );
+ }
+
+ if let Some(annotation_index) = self.rvalue_user_ty(rv) {
+ if let Err(terr) = self.relate_type_and_user_type(
+ rv_ty,
+ ty::Variance::Invariant,
+ &UserTypeProjection { base: annotation_index, projs: vec![] },
+ location.to_locations(),
+ ConstraintCategory::Boring,
+ ) {
+ let annotation = &self.user_type_annotations[annotation_index];
+ span_mirbug!(
+ self,
+ stmt,
+ "bad user type on rvalue ({:?} = {:?}): {:?}",
+ annotation,
+ rv_ty,
+ terr
+ );
+ }
+ }
+
+ self.check_rvalue(body, rv, location);
+ if !self.unsized_feature_enabled() {
+ let trait_ref = ty::TraitRef {
+ def_id: tcx.require_lang_item(LangItem::Sized, 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::CopyNonOverlapping(box rustc_middle::mir::CopyNonOverlapping {
+ ..
+ }) => span_bug!(
+ stmt.source_info.span,
+ "Unexpected StatementKind::CopyNonOverlapping, should only appear after lowering_intrinsics",
+ ),
+ StatementKind::FakeRead(..)
+ | StatementKind::StorageLive(..)
+ | StatementKind::StorageDead(..)
+ | StatementKind::LlvmInlineAsm { .. }
+ | StatementKind::Retag { .. }
+ | StatementKind::Coverage(..)
+ | StatementKind::Nop => {}
+ }
+ }
+
+ #[instrument(skip(self, body, term_location), level = "debug")]
+ fn check_terminator(
+ &mut self,
+ body: &Body<'tcx>,
+ term: &Terminator<'tcx>,
+ term_location: Location,
+ ) {
+ let tcx = self.tcx();
+ 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::Binder::dummy(ty::PredicateKind::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(sig.output(), dest_ty, locations, category) {
+ span_mirbug!(
+ self,
+ term,
+ "call dest mismatch ({:?} <- {:?}): {:?}",
+ dest_ty,
+ sig.output(),
+ terr
+ );
+ }
+
+ // When `unsized_fn_params` and `unsized_locals` are both not enabled,
+ // this check is done at `check_local`.
+ if self.unsized_feature_enabled() {
+ let span = term.source_info.span;
+ self.ensure_place_sized(dest_ty, span);
+ }
+ }
+ None => {
+ if !self
+ .tcx()
+ .conservative_is_privately_uninhabited(self.param_env.and(sig.output()))
+ {
+ 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 iter::zip(sig.inputs(), args).enumerate() {
+ let op_arg_ty = op_arg.ty(body, self.tcx());
+ let op_arg_ty = self.normalize(op_arg_ty, term_location);
+ let category = if from_hir_call {
+ ConstraintCategory::CallArgument
+ } else {
+ ConstraintCategory::Boring
+ };
+ if let Err(terr) =
+ self.sub_types(op_arg_ty, fn_arg, term_location.to_locations(), category)
+ {
+ span_mirbug!(
+ self,
+ term,
+ "bad arg #{:?} ({:?} <- {:?}): {:?}",
+ n,
+ fn_arg,
+ op_arg_ty,
+ terr
+ );
+ }
+ }
+ }
+
+ fn check_iscleanup(&mut self, body: &Body<'tcx>, block_data: &BasicBlockData<'tcx>) {
+ let is_cleanup = block_data.is_cleanup;
+ self.last_span = block_data.terminator().source_info.span;
+ match block_data.terminator().kind {
+ TerminatorKind::Goto { target } => {
+ self.assert_iscleanup(body, block_data, target, is_cleanup)
+ }
+ TerminatorKind::SwitchInt { ref targets, .. } => {
+ for target in targets.all_targets() {
+ self.assert_iscleanup(body, block_data, *target, is_cleanup);
+ }
+ }
+ TerminatorKind::Resume => {
+ if !is_cleanup {
+ span_mirbug!(self, block_data, "resume on non-cleanup block!")
+ }
+ }
+ TerminatorKind::Abort => {
+ if !is_cleanup {
+ span_mirbug!(self, block_data, "abort on non-cleanup block!")
+ }
+ }
+ TerminatorKind::Return => {
+ if is_cleanup {
+ span_mirbug!(self, block_data, "return on cleanup block")
+ }
+ }
+ TerminatorKind::GeneratorDrop { .. } => {
+ if is_cleanup {
+ span_mirbug!(self, block_data, "generator_drop in cleanup block")
+ }
+ }
+ TerminatorKind::Yield { resume, drop, .. } => {
+ if is_cleanup {
+ span_mirbug!(self, block_data, "yield in cleanup block")
+ }
+ self.assert_iscleanup(body, block_data, resume, is_cleanup);
+ if let Some(drop) = drop {
+ self.assert_iscleanup(body, block_data, drop, is_cleanup);
+ }
+ }
+ TerminatorKind::Unreachable => {}
+ TerminatorKind::Drop { target, unwind, .. }
+ | TerminatorKind::DropAndReplace { target, unwind, .. }
+ | TerminatorKind::Assert { target, cleanup: unwind, .. } => {
+ self.assert_iscleanup(body, block_data, target, is_cleanup);
+ if let Some(unwind) = unwind {
+ if is_cleanup {
+ span_mirbug!(self, block_data, "unwind on cleanup block")
+ }
+ self.assert_iscleanup(body, block_data, unwind, true);
+ }
+ }
+ TerminatorKind::Call { ref 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 { 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 `unsized_fn_params` or `unsized_locals` is enabled, only function calls
+ // and nullary ops are checked in `check_call_dest`.
+ if !self.unsized_feature_enabled() {
+ let span = local_decl.source_info.span;
+ let ty = local_decl.ty;
+ self.ensure_place_sized(ty, span);
+ }
+ }
+
+ fn ensure_place_sized(&mut self, ty: Ty<'tcx>, span: Span) {
+ let tcx = self.tcx();
+
+ // Erase the regions from `ty` to get a global type. The
+ // `Sized` bound in no way depends on precise regions, so this
+ // shouldn't affect `is_sized`.
+ let erased_ty = tcx.erase_regions(ty);
+ if !erased_ty.is_sized(tcx.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 a call expression.
+ diag.emit();
+ }
+ }
+ }
+
+ fn aggregate_field_ty(
+ &mut self,
+ ak: &AggregateKind<'tcx>,
+ field_index: usize,
+ location: Location,
+ ) -> Result<Ty<'tcx>, 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) {
+ match operand {
+ Operand::Copy(..) | Operand::Constant(..) => {
+ // These are always okay: direct use of a const, or a value that can evidently be copied.
+ }
+ Operand::Move(place) => {
+ // Make sure that repeated elements implement `Copy`.
+ let 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, body, self.param_env);
+ let is_const_fn =
+ is_const_fn_in_array_repeat_expression(&ccx, &place, &body);
+
+ debug!("check_rvalue: is_const_fn={:?}", is_const_fn);
+
+ let def_id = body.source.def_id().expect_local();
+ let obligation = traits::Obligation::new(
+ ObligationCause::new(
+ span,
+ self.tcx().hir().local_def_id_to_hir_id(def_id),
+ traits::ObligationCauseCode::RepeatVec(is_const_fn),
+ ),
+ self.param_env,
+ ty::Binder::dummy(ty::TraitRef::new(
+ self.tcx().require_lang_item(
+ LangItem::Copy,
+ Some(self.last_span),
+ ),
+ tcx.mk_substs_trait(ty, &[]),
+ ))
+ .without_const()
+ .to_predicate(self.tcx()),
+ );
+ self.infcx.report_selection_error(
+ obligation.clone(),
+ &obligation,
+ &traits::SelectionError::Unimplemented,
+ false,
+ );
+ }
+ }
+ }
+ }
+ }
+
+ Rvalue::NullaryOp(_, ty) | Rvalue::ShallowInitBox(_, ty) => {
+ let trait_ref = ty::TraitRef {
+ def_id: tcx.require_lang_item(LangItem::Sized, 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,
+ ty_fn_ptr_from,
+ location.to_locations(),
+ ConstraintCategory::Cast,
+ ) {
+ span_mirbug!(
+ self,
+ rvalue,
+ "equating {:?} with {:?} yields {:?}",
+ ty_fn_ptr_from,
+ ty,
+ terr
+ );
+ }
+ }
+
+ CastKind::Pointer(PointerCast::ClosureFnPointer(unsafety)) => {
+ let sig = match op.ty(body, tcx).kind() {
+ ty::Closure(_, substs) => substs.as_closure().sig(),
+ _ => bug!(),
+ };
+ let ty_fn_ptr_from = tcx.mk_fn_ptr(tcx.signature_unclosure(sig, *unsafety));
+
+ if let Err(terr) = self.eq_types(
+ ty,
+ ty_fn_ptr_from,
+ location.to_locations(),
+ ConstraintCategory::Cast,
+ ) {
+ span_mirbug!(
+ self,
+ rvalue,
+ "equating {:?} with {:?} yields {:?}",
+ ty_fn_ptr_from,
+ ty,
+ terr
+ );
+ }
+ }
+
+ CastKind::Pointer(PointerCast::UnsafeFnPointer) => {
+ let fn_sig = op.ty(body, tcx).fn_sig(tcx);
+
+ // The type that we see in the fcx is like
+ // `foo::<'a, 'b>`, where `foo` is the path to a
+ // function definition. When we extract the
+ // signature, it comes from the `fn_sig` query,
+ // and hence may contain unnormalized results.
+ let fn_sig = self.normalize(fn_sig, location);
+
+ let ty_fn_ptr_from = tcx.safe_to_unsafe_fn_ty(fn_sig);
+
+ if let Err(terr) = self.eq_types(
+ ty,
+ ty_fn_ptr_from,
+ location.to_locations(),
+ ConstraintCategory::Cast,
+ ) {
+ span_mirbug!(
+ self,
+ rvalue,
+ "equating {:?} with {:?} yields {:?}",
+ ty_fn_ptr_from,
+ ty,
+ terr
+ );
+ }
+ }
+
+ CastKind::Pointer(PointerCast::Unsize) => {
+ let &ty = ty;
+ let trait_ref = ty::TraitRef {
+ def_id: tcx
+ .require_lang_item(LangItem::CoerceUnsized, 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_mut = match ty_from.kind() {
+ ty::RawPtr(ty::TypeAndMut { mutbl: array_mut, ty: array_ty }) => {
+ match array_ty.kind() {
+ ty::Array(ty_elem, _) => Some((ty_elem, *array_mut)),
+ _ => None,
+ }
+ }
+ _ => None,
+ };
+
+ let (ty_elem, ty_mut) = match opt_ty_elem_mut {
+ Some(ty_elem_mut) => ty_elem_mut,
+ None => {
+ span_mirbug!(
+ self,
+ rvalue,
+ "ArrayToPointer cast from unexpected type {:?}",
+ ty_from,
+ );
+ return;
+ }
+ };
+
+ let (ty_to, ty_to_mut) = match ty.kind() {
+ ty::RawPtr(ty::TypeAndMut { mutbl: ty_to_mut, ty: ty_to }) => {
+ (ty_to, *ty_to_mut)
+ }
+ _ => {
+ span_mirbug!(
+ self,
+ rvalue,
+ "ArrayToPointer cast to unexpected type {:?}",
+ ty,
+ );
+ return;
+ }
+ };
+
+ if ty_to_mut == Mutability::Mut && ty_mut == Mutability::Not {
+ span_mirbug!(
+ self,
+ rvalue,
+ "ArrayToPointer cast from const {:?} to mut {:?}",
+ ty,
+ ty_to
+ );
+ return;
+ }
+
+ if let Err(terr) = self.sub_types(
+ ty_elem,
+ ty_to,
+ location.to_locations(),
+ ConstraintCategory::Cast,
+ ) {
+ span_mirbug!(
+ self,
+ rvalue,
+ "relating {:?} with {:?} yields {:?}",
+ ty_elem,
+ ty_to,
+ terr
+ )
+ }
+ }
+
+ CastKind::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,
+ box (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.sub_types(
+ ty_left,
+ common_ty,
+ location.to_locations(),
+ ConstraintCategory::Boring,
+ )
+ .unwrap_or_else(|err| {
+ bug!("Could not equate type variable with {:?}: {:?}", ty_left, err)
+ });
+ if let Err(terr) = self.sub_types(
+ ty_right,
+ common_ty,
+ location.to_locations(),
+ ConstraintCategory::Boring,
+ ) {
+ span_mirbug!(
+ self,
+ rvalue,
+ "unexpected comparison types {:?} and {:?} yields {:?}",
+ ty_left,
+ ty_right,
+ terr
+ )
+ }
+ }
+ // For types with no regions we can just check that the
+ // both operands have the same type.
+ ty::Int(_) | ty::Uint(_) | ty::Bool | ty::Char | ty::Float(_)
+ if ty_left == right.ty(body, tcx) => {}
+ // Other types are compared by trait methods, not by
+ // `Rvalue::BinaryOp`.
+ _ => span_mirbug!(
+ self,
+ rvalue,
+ "unexpected comparison types {:?} and {:?}",
+ ty_left,
+ right.ty(body, tcx)
+ ),
+ }
+ }
+
+ Rvalue::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<UserTypeAnnotationIndex> {
+ match rvalue {
+ Rvalue::Use(_)
+ | Rvalue::ThreadLocalRef(_)
+ | Rvalue::Repeat(..)
+ | Rvalue::Ref(..)
+ | Rvalue::AddressOf(..)
+ | Rvalue::Len(..)
+ | Rvalue::Cast(..)
+ | Rvalue::ShallowInitBox(..)
+ | Rvalue::BinaryOp(..)
+ | Rvalue::CheckedBinaryOp(..)
+ | Rvalue::NullaryOp(..)
+ | Rvalue::UnaryOp(..)
+ | Rvalue::Discriminant(..) => None,
+
+ Rvalue::Aggregate(aggregate, _) => match **aggregate {
+ AggregateKind::Adt(_, _, _, user_ty, _) => user_ty,
+ AggregateKind::Array(_) => None,
+ AggregateKind::Tuple => None,
+ AggregateKind::Closure(_, _) => None,
+ AggregateKind::Generator(_, _, _) => None,
+ },
+ }
+ }
+
+ fn check_aggregate_rvalue(
+ &mut self,
+ body: &Body<'tcx>,
+ rvalue: &Rvalue<'tcx>,
+ aggregate_kind: &AggregateKind<'tcx>,
+ operands: &[Operand<'tcx>],
+ location: Location,
+ ) {
+ let tcx = self.tcx();
+
+ self.prove_aggregate_predicates(aggregate_kind, location);
+
+ if *aggregate_kind == AggregateKind::Tuple {
+ // tuple rvalue field type is always the type of the op. Nothing to check here.
+ return;
+ }
+
+ for (i, operand) in operands.iter().enumerate() {
+ let field_ty = match self.aggregate_field_ty(aggregate_kind, i, location) {
+ Ok(field_ty) => field_ty,
+ Err(FieldAccessError::OutOfRange { field_count }) => {
+ span_mirbug!(
+ self,
+ rvalue,
+ "accessed field #{} but variant only has {}",
+ i,
+ field_count
+ );
+ continue;
+ }
+ };
+ let operand_ty = operand.ty(body, tcx);
+ let operand_ty = self.normalize(operand_ty, location);
+
+ if let Err(terr) = self.sub_types(
+ operand_ty,
+ field_ty,
+ location.to_locations(),
+ ConstraintCategory::Boring,
+ ) {
+ span_mirbug!(
+ self,
+ rvalue,
+ "{:?} is not a subtype of {:?}: {:?}",
+ operand_ty,
+ field_ty,
+ terr
+ );
+ }
+ }
+ }
+
+ /// Adds the constraints that arise from a borrow expression `&'a P` at the location `L`.
+ ///
+ /// # Parameters
+ ///
+ /// - `location`: the location `L` where the borrow expression occurs
+ /// - `borrow_region`: the region `'a` associated with the borrow
+ /// - `borrowed_place`: the place `P` being borrowed
+ fn add_reborrow_constraint(
+ &mut self,
+ body: &Body<'tcx>,
+ location: Location,
+ borrow_region: ty::Region<'tcx>,
+ borrowed_place: &Place<'tcx>,
+ ) {
+ // These constraints are only meaningful during borrowck:
+ let BorrowCheckContext { borrow_set, location_table, all_facts, constraints, .. } =
+ self.borrowck_context;
+
+ // In Polonius mode, we also push a `loan_issued_at` fact
+ // linking the loan to the region (in some cases, though,
+ // there is no loan associated with this borrow expression --
+ // that occurs when we are borrowing an unsafe place, for
+ // example).
+ if let Some(all_facts) = all_facts {
+ let _prof_timer = self.infcx.tcx.prof.generic_activity("polonius_fact_generation");
+ if let Some(borrow_index) = borrow_set.get_index_of(&location) {
+ let region_vid = borrow_region.to_region_vid();
+ all_facts.loan_issued_at.push((
+ region_vid,
+ borrow_index,
+ location_table.mid_index(location),
+ ));
+ }
+ }
+
+ // If we are reborrowing the referent of another reference, we
+ // need to add outlives relationships. In a case like `&mut
+ // *p`, where the `p` has type `&'b mut Foo`, for example, we
+ // need to ensure that `'b: 'a`.
+
+ debug!(
+ "add_reborrow_constraint({:?}, {:?}, {:?})",
+ location, borrow_region, borrowed_place
+ );
+
+ let mut cursor = borrowed_place.projection.as_ref();
+ let tcx = self.infcx.tcx;
+ let field = path_utils::is_upvar_field_projection(
+ tcx,
+ &self.borrowck_context.upvars,
+ borrowed_place.as_ref(),
+ body,
+ );
+ let category = if let Some(field) = field {
+ let var_hir_id = self.borrowck_context.upvars[field.index()].place.get_root_variable();
+ // FIXME(project-rfc-2229#8): Use Place for better diagnostics
+ ConstraintCategory::ClosureUpvar(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,
+ variance_info: ty::VarianceDiagInfo::default(),
+ });
+
+ 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 (def_id, instantiated_predicates) = match aggregate_kind {
+ AggregateKind::Adt(def, _, substs, _, _) => {
+ (def.did, 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, _) => {
+ (*def_id, self.prove_closure_bounds(tcx, def_id.expect_local(), substs, location))
+ }
+
+ AggregateKind::Array(_) | AggregateKind::Tuple => {
+ (CRATE_DEF_ID.to_def_id(), ty::InstantiatedPredicates::empty())
+ }
+ };
+
+ self.normalize_and_prove_instantiated_predicates(
+ def_id,
+ instantiated_predicates,
+ location.to_locations(),
+ );
+ }
+
+ fn prove_closure_bounds(
+ &mut self,
+ tcx: TyCtxt<'tcx>,
+ def_id: LocalDefId,
+ substs: SubstsRef<'tcx>,
+ location: Location,
+ ) -> ty::InstantiatedPredicates<'tcx> {
+ if let Some(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)
+ }
+
+ #[instrument(skip(self, body), level = "debug")]
+ fn typeck_mir(&mut self, body: &Body<'tcx>) {
+ self.last_span = body.span;
+ debug!(?body.span);
+
+ for (local, local_decl) in body.local_decls.iter_enumerated() {
+ self.check_local(&body, local, local_decl);
+ }
+
+ for (block, block_data) in body.basic_blocks().iter_enumerated() {
+ let mut location = Location { block, statement_index: 0 };
+ for stmt in &block_data.statements {
+ if !stmt.source_info.span.is_dummy() {
+ self.last_span = stmt.source_info.span;
+ }
+ self.check_stmt(body, stmt, location);
+ location.statement_index += 1;
+ }
+
+ self.check_terminator(&body, block_data.terminator(), location);
+ self.check_iscleanup(&body, block_data);
+ }
+ }
+}
+
+trait NormalizeLocation: fmt::Debug + Copy {
+ fn to_locations(self) -> Locations;
+}
+
+impl NormalizeLocation for Locations {
+ fn to_locations(self) -> Locations {
+ self
+ }
+}
+
+impl NormalizeLocation for Location {
+ fn to_locations(self) -> Locations {
+ Locations::Single(self)
+ }
+}
+
+#[derive(Debug, Default)]
+struct ObligationAccumulator<'tcx> {
+ obligations: PredicateObligations<'tcx>,
+}
+
+impl<'tcx> ObligationAccumulator<'tcx> {
+ fn add<T>(&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
+ }
+}
projects / rustc.git / blobdiff