| //! Contains the logic to lower rustc types into Chalk types |
| //! |
| //! In many cases there is a 1:1 relationship between a rustc type and a Chalk type. |
| //! For example, a `SubstsRef` maps almost directly to a `Substitution`. In some |
| //! other cases, such as `Param`s, there is no Chalk type, so we have to handle |
| //! accordingly. |
| //! |
| //! ## `Ty` lowering |
| //! Much of the `Ty` lowering is 1:1 with Chalk. (Or will be eventually). A |
| //! helpful table for what types lower to what can be found in the |
| //! [Chalk book](http://rust-lang.github.io/chalk/book/types/rust_types.html). |
| //! The most notable difference lies with `Param`s. To convert from rustc to |
| //! Chalk, we eagerly and deeply convert `Param`s to placeholders (in goals) or |
| //! bound variables (for clause generation through functions in `db`). |
| //! |
| //! ## `Region` lowering |
| //! Regions are handled in rustc and Chalk is quite differently. In rustc, there |
| //! is a difference between "early bound" and "late bound" regions, where only |
| //! the late bound regions have a `DebruijnIndex`. Moreover, in Chalk all |
| //! regions (Lifetimes) have an associated index. In rustc, only `BrAnon`s have |
| //! an index, whereas `BrNamed` don't. In order to lower regions to Chalk, we |
| //! convert all regions into `BrAnon` late-bound regions. |
| //! |
| //! ## `Const` lowering |
| //! Chalk doesn't handle consts currently, so consts are currently lowered to |
| //! an empty tuple. |
| //! |
| //! ## Bound variable collection |
| //! Another difference between rustc and Chalk lies in the handling of binders. |
| //! Chalk requires that we store the bound parameter kinds, whereas rustc does |
| //! not. To lower anything wrapped in a `Binder`, we first deeply find any bound |
| //! variables from the current `Binder`. |
| |
| use rustc_middle::traits::{ |
| ChalkEnvironmentAndGoal, ChalkEnvironmentClause, ChalkRustInterner as RustInterner, |
| }; |
| use rustc_middle::ty::fold::TypeFolder; |
| use rustc_middle::ty::subst::{GenericArg, GenericArgKind, SubstsRef}; |
| use rustc_middle::ty::{ |
| self, Binder, BoundRegion, Region, RegionKind, Ty, TyCtxt, TyKind, TypeFoldable, TypeVisitor, |
| }; |
| use rustc_span::def_id::DefId; |
| |
| use std::collections::btree_map::{BTreeMap, Entry}; |
| |
| use chalk_ir::fold::shift::Shift; |
| |
| /// Essentially an `Into` with a `&RustInterner` parameter |
| crate trait LowerInto<'tcx, T> { |
| /// Lower a rustc construct (e.g., `ty::TraitPredicate`) to a chalk type, consuming `self`. |
| fn lower_into(self, interner: &RustInterner<'tcx>) -> T; |
| } |
| |
| impl<'tcx> LowerInto<'tcx, chalk_ir::Substitution<RustInterner<'tcx>>> for SubstsRef<'tcx> { |
| fn lower_into( |
| self, |
| interner: &RustInterner<'tcx>, |
| ) -> chalk_ir::Substitution<RustInterner<'tcx>> { |
| chalk_ir::Substitution::from(interner, self.iter().map(|s| s.lower_into(interner))) |
| } |
| } |
| |
| impl<'tcx> LowerInto<'tcx, chalk_ir::AliasTy<RustInterner<'tcx>>> for ty::ProjectionTy<'tcx> { |
| fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::AliasTy<RustInterner<'tcx>> { |
| chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy { |
| associated_ty_id: chalk_ir::AssocTypeId(self.item_def_id), |
| substitution: self.substs.lower_into(interner), |
| }) |
| } |
| } |
| |
| impl<'tcx> LowerInto<'tcx, chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'tcx>>>> |
| for ChalkEnvironmentAndGoal<'tcx> |
| { |
| fn lower_into( |
| self, |
| interner: &RustInterner<'tcx>, |
| ) -> chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'tcx>>> { |
| let clauses = self.environment.into_iter().filter_map(|clause| match clause { |
| ChalkEnvironmentClause::Predicate(predicate) => { |
| match predicate.kind() { |
| ty::PredicateKind::Trait(predicate, _) => { |
| let (predicate, binders, _named_regions) = |
| collect_bound_vars(interner, interner.tcx, predicate); |
| |
| Some( |
| chalk_ir::ProgramClauseData(chalk_ir::Binders::new( |
| binders, |
| chalk_ir::ProgramClauseImplication { |
| consequence: chalk_ir::DomainGoal::FromEnv( |
| chalk_ir::FromEnv::Trait( |
| predicate.trait_ref.lower_into(interner), |
| ), |
| ), |
| conditions: chalk_ir::Goals::new(interner), |
| priority: chalk_ir::ClausePriority::High, |
| }, |
| )) |
| .intern(interner), |
| ) |
| } |
| ty::PredicateKind::RegionOutlives(predicate) => { |
| let (predicate, binders, _named_regions) = |
| collect_bound_vars(interner, interner.tcx, predicate); |
| |
| Some( |
| chalk_ir::ProgramClauseData(chalk_ir::Binders::new( |
| binders, |
| chalk_ir::ProgramClauseImplication { |
| consequence: chalk_ir::DomainGoal::Holds( |
| chalk_ir::WhereClause::LifetimeOutlives( |
| chalk_ir::LifetimeOutlives { |
| a: predicate.0.lower_into(interner), |
| b: predicate.1.lower_into(interner), |
| }, |
| ), |
| ), |
| conditions: chalk_ir::Goals::new(interner), |
| priority: chalk_ir::ClausePriority::High, |
| }, |
| )) |
| .intern(interner), |
| ) |
| } |
| // FIXME(chalk): need to add TypeOutlives |
| ty::PredicateKind::TypeOutlives(_) => None, |
| ty::PredicateKind::Projection(predicate) => { |
| let (predicate, binders, _named_regions) = |
| collect_bound_vars(interner, interner.tcx, predicate); |
| |
| Some( |
| chalk_ir::ProgramClauseData(chalk_ir::Binders::new( |
| binders, |
| chalk_ir::ProgramClauseImplication { |
| consequence: chalk_ir::DomainGoal::Holds( |
| chalk_ir::WhereClause::AliasEq( |
| predicate.lower_into(interner), |
| ), |
| ), |
| conditions: chalk_ir::Goals::new(interner), |
| priority: chalk_ir::ClausePriority::High, |
| }, |
| )) |
| .intern(interner), |
| ) |
| } |
| ty::PredicateKind::WellFormed(..) |
| | ty::PredicateKind::ObjectSafe(..) |
| | ty::PredicateKind::ClosureKind(..) |
| | ty::PredicateKind::Subtype(..) |
| | ty::PredicateKind::ConstEvaluatable(..) |
| | ty::PredicateKind::ConstEquate(..) => { |
| bug!("unexpected predicate {}", predicate) |
| } |
| } |
| } |
| ChalkEnvironmentClause::TypeFromEnv(ty) => Some( |
| chalk_ir::ProgramClauseData(chalk_ir::Binders::new( |
| chalk_ir::VariableKinds::new(interner), |
| chalk_ir::ProgramClauseImplication { |
| consequence: chalk_ir::DomainGoal::FromEnv(chalk_ir::FromEnv::Ty( |
| ty.lower_into(interner).shifted_in(interner), |
| )), |
| conditions: chalk_ir::Goals::new(interner), |
| priority: chalk_ir::ClausePriority::High, |
| }, |
| )) |
| .intern(interner), |
| ), |
| }); |
| |
| let goal: chalk_ir::GoalData<RustInterner<'tcx>> = self.goal.lower_into(&interner); |
| chalk_ir::InEnvironment { |
| environment: chalk_ir::Environment { |
| clauses: chalk_ir::ProgramClauses::from(&interner, clauses), |
| }, |
| goal: goal.intern(&interner), |
| } |
| } |
| } |
| |
| impl<'tcx> LowerInto<'tcx, chalk_ir::GoalData<RustInterner<'tcx>>> for ty::Predicate<'tcx> { |
| fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GoalData<RustInterner<'tcx>> { |
| match self.kind() { |
| ty::PredicateKind::Trait(predicate, _) => predicate.lower_into(interner), |
| ty::PredicateKind::RegionOutlives(predicate) => { |
| let (predicate, binders, _named_regions) = |
| collect_bound_vars(interner, interner.tcx, predicate); |
| |
| chalk_ir::GoalData::Quantified( |
| chalk_ir::QuantifierKind::ForAll, |
| chalk_ir::Binders::new( |
| binders, |
| chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds( |
| chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives { |
| a: predicate.0.lower_into(interner), |
| b: predicate.1.lower_into(interner), |
| }), |
| )) |
| .intern(interner), |
| ), |
| ) |
| } |
| // FIXME(chalk): TypeOutlives |
| ty::PredicateKind::TypeOutlives(_predicate) => { |
| chalk_ir::GoalData::All(chalk_ir::Goals::new(interner)) |
| } |
| ty::PredicateKind::Projection(predicate) => predicate.lower_into(interner), |
| ty::PredicateKind::WellFormed(arg) => match arg.unpack() { |
| GenericArgKind::Type(ty) => match ty.kind { |
| // FIXME(chalk): In Chalk, a placeholder is WellFormed if it |
| // `FromEnv`. However, when we "lower" Params, we don't update |
| // the environment. |
| ty::Placeholder(..) => chalk_ir::GoalData::All(chalk_ir::Goals::new(interner)), |
| |
| _ => chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::WellFormed( |
| chalk_ir::WellFormed::Ty(ty.lower_into(interner)), |
| )), |
| }, |
| // FIXME(chalk): handle well formed consts |
| GenericArgKind::Const(..) => { |
| chalk_ir::GoalData::All(chalk_ir::Goals::new(interner)) |
| } |
| GenericArgKind::Lifetime(lt) => bug!("unexpect well formed predicate: {:?}", lt), |
| }, |
| |
| ty::PredicateKind::ObjectSafe(t) => chalk_ir::GoalData::DomainGoal( |
| chalk_ir::DomainGoal::ObjectSafe(chalk_ir::TraitId(*t)), |
| ), |
| |
| // FIXME(chalk): other predicates |
| // |
| // We can defer this, but ultimately we'll want to express |
| // some of these in terms of chalk operations. |
| ty::PredicateKind::ClosureKind(..) |
| | ty::PredicateKind::Subtype(..) |
| | ty::PredicateKind::ConstEvaluatable(..) |
| | ty::PredicateKind::ConstEquate(..) => { |
| chalk_ir::GoalData::All(chalk_ir::Goals::new(interner)) |
| } |
| } |
| } |
| } |
| |
| impl<'tcx> LowerInto<'tcx, chalk_ir::TraitRef<RustInterner<'tcx>>> |
| for rustc_middle::ty::TraitRef<'tcx> |
| { |
| fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::TraitRef<RustInterner<'tcx>> { |
| chalk_ir::TraitRef { |
| trait_id: chalk_ir::TraitId(self.def_id), |
| substitution: self.substs.lower_into(interner), |
| } |
| } |
| } |
| |
| impl<'tcx> LowerInto<'tcx, chalk_ir::GoalData<RustInterner<'tcx>>> |
| for ty::PolyTraitPredicate<'tcx> |
| { |
| fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GoalData<RustInterner<'tcx>> { |
| let (ty, binders, _named_regions) = collect_bound_vars(interner, interner.tcx, &self); |
| |
| chalk_ir::GoalData::Quantified( |
| chalk_ir::QuantifierKind::ForAll, |
| chalk_ir::Binders::new( |
| binders, |
| chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds( |
| chalk_ir::WhereClause::Implemented(ty.trait_ref.lower_into(interner)), |
| )) |
| .intern(interner), |
| ), |
| ) |
| } |
| } |
| |
| impl<'tcx> LowerInto<'tcx, chalk_ir::AliasEq<RustInterner<'tcx>>> |
| for rustc_middle::ty::ProjectionPredicate<'tcx> |
| { |
| fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::AliasEq<RustInterner<'tcx>> { |
| chalk_ir::AliasEq { |
| ty: self.ty.lower_into(interner), |
| alias: self.projection_ty.lower_into(interner), |
| } |
| } |
| } |
| |
| impl<'tcx> LowerInto<'tcx, chalk_ir::GoalData<RustInterner<'tcx>>> |
| for ty::PolyProjectionPredicate<'tcx> |
| { |
| fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GoalData<RustInterner<'tcx>> { |
| let (ty, binders, _named_regions) = collect_bound_vars(interner, interner.tcx, &self); |
| |
| chalk_ir::GoalData::Quantified( |
| chalk_ir::QuantifierKind::ForAll, |
| chalk_ir::Binders::new( |
| binders, |
| chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds( |
| chalk_ir::WhereClause::AliasEq(ty.lower_into(interner)), |
| )) |
| .intern(interner), |
| ), |
| ) |
| } |
| } |
| |
| impl<'tcx> LowerInto<'tcx, chalk_ir::Ty<RustInterner<'tcx>>> for Ty<'tcx> { |
| fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::Ty<RustInterner<'tcx>> { |
| use chalk_ir::TyData; |
| use rustc_ast::ast; |
| use TyKind::*; |
| |
| let empty = || chalk_ir::Substitution::empty(interner); |
| let struct_ty = |
| |def_id| chalk_ir::TypeName::Adt(chalk_ir::AdtId(interner.tcx.adt_def(def_id))); |
| let apply = |name, substitution| { |
| TyData::Apply(chalk_ir::ApplicationTy { name, substitution }).intern(interner) |
| }; |
| let int = |i| apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Int(i)), empty()); |
| let uint = |i| apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Uint(i)), empty()); |
| let float = |f| apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Float(f)), empty()); |
| |
| match self.kind { |
| Bool => apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Bool), empty()), |
| Char => apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Char), empty()), |
| Int(ty) => match ty { |
| ast::IntTy::Isize => int(chalk_ir::IntTy::Isize), |
| ast::IntTy::I8 => int(chalk_ir::IntTy::I8), |
| ast::IntTy::I16 => int(chalk_ir::IntTy::I16), |
| ast::IntTy::I32 => int(chalk_ir::IntTy::I32), |
| ast::IntTy::I64 => int(chalk_ir::IntTy::I64), |
| ast::IntTy::I128 => int(chalk_ir::IntTy::I128), |
| }, |
| Uint(ty) => match ty { |
| ast::UintTy::Usize => uint(chalk_ir::UintTy::Usize), |
| ast::UintTy::U8 => uint(chalk_ir::UintTy::U8), |
| ast::UintTy::U16 => uint(chalk_ir::UintTy::U16), |
| ast::UintTy::U32 => uint(chalk_ir::UintTy::U32), |
| ast::UintTy::U64 => uint(chalk_ir::UintTy::U64), |
| ast::UintTy::U128 => uint(chalk_ir::UintTy::U128), |
| }, |
| Float(ty) => match ty { |
| ast::FloatTy::F32 => float(chalk_ir::FloatTy::F32), |
| ast::FloatTy::F64 => float(chalk_ir::FloatTy::F64), |
| }, |
| Adt(def, substs) => apply(struct_ty(def.did), substs.lower_into(interner)), |
| Foreign(_def_id) => unimplemented!(), |
| Str => apply(chalk_ir::TypeName::Str, empty()), |
| Array(ty, len) => { |
| let value = match len.val { |
| ty::ConstKind::Value(val) => { |
| chalk_ir::ConstValue::Concrete(chalk_ir::ConcreteConst { interned: val }) |
| } |
| ty::ConstKind::Bound(db, bound) => { |
| chalk_ir::ConstValue::BoundVar(chalk_ir::BoundVar::new( |
| chalk_ir::DebruijnIndex::new(db.as_u32()), |
| bound.index(), |
| )) |
| } |
| _ => unimplemented!("Const not implemented. {:?}", len.val), |
| }; |
| apply( |
| chalk_ir::TypeName::Array, |
| chalk_ir::Substitution::from( |
| interner, |
| &[ |
| chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner), |
| chalk_ir::GenericArgData::Const( |
| chalk_ir::ConstData { ty: len.ty.lower_into(interner), value } |
| .intern(interner), |
| ) |
| .intern(interner), |
| ], |
| ), |
| ) |
| } |
| Slice(ty) => apply( |
| chalk_ir::TypeName::Slice, |
| chalk_ir::Substitution::from1( |
| interner, |
| chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner), |
| ), |
| ), |
| RawPtr(ptr) => { |
| let name = match ptr.mutbl { |
| ast::Mutability::Mut => chalk_ir::TypeName::Raw(chalk_ir::Mutability::Mut), |
| ast::Mutability::Not => chalk_ir::TypeName::Raw(chalk_ir::Mutability::Not), |
| }; |
| apply(name, chalk_ir::Substitution::from1(interner, ptr.ty.lower_into(interner))) |
| } |
| Ref(region, ty, mutability) => { |
| let name = match mutability { |
| ast::Mutability::Mut => chalk_ir::TypeName::Ref(chalk_ir::Mutability::Mut), |
| ast::Mutability::Not => chalk_ir::TypeName::Ref(chalk_ir::Mutability::Not), |
| }; |
| apply( |
| name, |
| chalk_ir::Substitution::from( |
| interner, |
| &[ |
| chalk_ir::GenericArgData::Lifetime(region.lower_into(interner)) |
| .intern(interner), |
| chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner), |
| ], |
| ), |
| ) |
| } |
| FnDef(def_id, substs) => apply( |
| chalk_ir::TypeName::FnDef(chalk_ir::FnDefId(def_id)), |
| substs.lower_into(interner), |
| ), |
| FnPtr(sig) => { |
| let (inputs_and_outputs, binders, _named_regions) = |
| collect_bound_vars(interner, interner.tcx, &sig.inputs_and_output()); |
| TyData::Function(chalk_ir::Fn { |
| num_binders: binders.len(interner), |
| substitution: chalk_ir::Substitution::from( |
| interner, |
| inputs_and_outputs.iter().map(|ty| { |
| chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner) |
| }), |
| ), |
| }) |
| .intern(interner) |
| } |
| Dynamic(predicates, region) => TyData::Dyn(chalk_ir::DynTy { |
| bounds: predicates.lower_into(interner), |
| lifetime: region.lower_into(interner), |
| }) |
| .intern(interner), |
| Closure(def_id, substs) => apply( |
| chalk_ir::TypeName::Closure(chalk_ir::ClosureId(def_id)), |
| substs.lower_into(interner), |
| ), |
| Generator(_def_id, _substs, _) => unimplemented!(), |
| GeneratorWitness(_) => unimplemented!(), |
| Never => apply(chalk_ir::TypeName::Never, empty()), |
| Tuple(substs) => { |
| apply(chalk_ir::TypeName::Tuple(substs.len()), substs.lower_into(interner)) |
| } |
| Projection(proj) => TyData::Alias(proj.lower_into(interner)).intern(interner), |
| Opaque(def_id, substs) => { |
| TyData::Alias(chalk_ir::AliasTy::Opaque(chalk_ir::OpaqueTy { |
| opaque_ty_id: chalk_ir::OpaqueTyId(def_id), |
| substitution: substs.lower_into(interner), |
| })) |
| .intern(interner) |
| } |
| // This should have been done eagerly prior to this, and all Params |
| // should have been substituted to placeholders |
| Param(_) => panic!("Lowering Param when not expected."), |
| Bound(db, bound) => TyData::BoundVar(chalk_ir::BoundVar::new( |
| chalk_ir::DebruijnIndex::new(db.as_u32()), |
| bound.var.index(), |
| )) |
| .intern(interner), |
| Placeholder(_placeholder) => TyData::Placeholder(chalk_ir::PlaceholderIndex { |
| ui: chalk_ir::UniverseIndex { counter: _placeholder.universe.as_usize() }, |
| idx: _placeholder.name.as_usize(), |
| }) |
| .intern(interner), |
| Infer(_infer) => unimplemented!(), |
| Error(_) => apply(chalk_ir::TypeName::Error, empty()), |
| } |
| } |
| } |
| |
| impl<'tcx> LowerInto<'tcx, chalk_ir::Lifetime<RustInterner<'tcx>>> for Region<'tcx> { |
| fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::Lifetime<RustInterner<'tcx>> { |
| use rustc_middle::ty::RegionKind::*; |
| |
| match self { |
| ReEarlyBound(_) => { |
| panic!("Should have already been substituted."); |
| } |
| ReLateBound(db, br) => match br { |
| ty::BoundRegion::BrAnon(var) => { |
| chalk_ir::LifetimeData::BoundVar(chalk_ir::BoundVar::new( |
| chalk_ir::DebruijnIndex::new(db.as_u32()), |
| *var as usize, |
| )) |
| .intern(interner) |
| } |
| ty::BoundRegion::BrNamed(_def_id, _name) => unimplemented!(), |
| ty::BrEnv => unimplemented!(), |
| }, |
| ReFree(_) => unimplemented!(), |
| // FIXME(chalk): need to handle ReStatic |
| ReStatic => unimplemented!(), |
| ReVar(_) => unimplemented!(), |
| RePlaceholder(placeholder_region) => { |
| chalk_ir::LifetimeData::Placeholder(chalk_ir::PlaceholderIndex { |
| ui: chalk_ir::UniverseIndex { counter: placeholder_region.universe.index() }, |
| idx: 0, |
| }) |
| .intern(interner) |
| } |
| ReEmpty(_) => unimplemented!(), |
| // FIXME(chalk): need to handle ReErased |
| ReErased => unimplemented!(), |
| } |
| } |
| } |
| |
| impl<'tcx> LowerInto<'tcx, chalk_ir::GenericArg<RustInterner<'tcx>>> for GenericArg<'tcx> { |
| fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GenericArg<RustInterner<'tcx>> { |
| match self.unpack() { |
| ty::subst::GenericArgKind::Type(ty) => { |
| chalk_ir::GenericArgData::Ty(ty.lower_into(interner)) |
| } |
| ty::subst::GenericArgKind::Lifetime(lifetime) => { |
| chalk_ir::GenericArgData::Lifetime(lifetime.lower_into(interner)) |
| } |
| ty::subst::GenericArgKind::Const(_) => chalk_ir::GenericArgData::Ty( |
| chalk_ir::TyData::Apply(chalk_ir::ApplicationTy { |
| name: chalk_ir::TypeName::Tuple(0), |
| substitution: chalk_ir::Substitution::empty(interner), |
| }) |
| .intern(interner), |
| ), |
| } |
| .intern(interner) |
| } |
| } |
| |
| // We lower into an Option here since there are some predicates which Chalk |
| // doesn't have a representation for yet (as a `WhereClause`), but are so common |
| // that we just are accepting the unsoundness for now. The `Option` will |
| // eventually be removed. |
| impl<'tcx> LowerInto<'tcx, Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>> |
| for ty::Predicate<'tcx> |
| { |
| fn lower_into( |
| self, |
| interner: &RustInterner<'tcx>, |
| ) -> Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>> { |
| match &self.kind() { |
| ty::PredicateKind::Trait(predicate, _) => { |
| let (predicate, binders, _named_regions) = |
| collect_bound_vars(interner, interner.tcx, predicate); |
| |
| Some(chalk_ir::Binders::new( |
| binders, |
| chalk_ir::WhereClause::Implemented(predicate.trait_ref.lower_into(interner)), |
| )) |
| } |
| ty::PredicateKind::RegionOutlives(predicate) => { |
| let (predicate, binders, _named_regions) = |
| collect_bound_vars(interner, interner.tcx, predicate); |
| |
| Some(chalk_ir::Binders::new( |
| binders, |
| chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives { |
| a: predicate.0.lower_into(interner), |
| b: predicate.1.lower_into(interner), |
| }), |
| )) |
| } |
| ty::PredicateKind::TypeOutlives(_predicate) => None, |
| ty::PredicateKind::Projection(_predicate) => None, |
| ty::PredicateKind::WellFormed(_ty) => None, |
| |
| ty::PredicateKind::ObjectSafe(..) |
| | ty::PredicateKind::ClosureKind(..) |
| | ty::PredicateKind::Subtype(..) |
| | ty::PredicateKind::ConstEvaluatable(..) |
| | ty::PredicateKind::ConstEquate(..) => bug!("unexpected predicate {}", &self), |
| } |
| } |
| } |
| |
| impl<'tcx> LowerInto<'tcx, chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>>> |
| for Binder<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>> |
| { |
| fn lower_into( |
| self, |
| interner: &RustInterner<'tcx>, |
| ) -> chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>> { |
| let (predicates, binders, _named_regions) = |
| collect_bound_vars(interner, interner.tcx, &self); |
| let where_clauses = predicates.into_iter().map(|predicate| match predicate { |
| ty::ExistentialPredicate::Trait(ty::ExistentialTraitRef { def_id, substs }) => { |
| chalk_ir::Binders::new( |
| chalk_ir::VariableKinds::new(interner), |
| chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef { |
| trait_id: chalk_ir::TraitId(def_id), |
| substitution: substs.lower_into(interner), |
| }), |
| ) |
| } |
| ty::ExistentialPredicate::Projection(_predicate) => unimplemented!(), |
| ty::ExistentialPredicate::AutoTrait(def_id) => chalk_ir::Binders::new( |
| chalk_ir::VariableKinds::new(interner), |
| chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef { |
| trait_id: chalk_ir::TraitId(def_id), |
| substitution: chalk_ir::Substitution::empty(interner), |
| }), |
| ), |
| }); |
| let value = chalk_ir::QuantifiedWhereClauses::from(interner, where_clauses); |
| chalk_ir::Binders::new(binders, value) |
| } |
| } |
| |
| /// To collect bound vars, we have to do two passes. In the first pass, we |
| /// collect all `BoundRegion`s and `ty::Bound`s. In the second pass, we then |
| /// replace `BrNamed` into `BrAnon`. The two separate passes are important, |
| /// since we can only replace `BrNamed` with `BrAnon`s with indices *after* all |
| /// "real" `BrAnon`s. |
| /// |
| /// It's important to note that because of prior substitution, we may have |
| /// late-bound regions, even outside of fn contexts, since this is the best way |
| /// to prep types for chalk lowering. |
| crate fn collect_bound_vars<'a, 'tcx, T: TypeFoldable<'tcx>>( |
| interner: &RustInterner<'tcx>, |
| tcx: TyCtxt<'tcx>, |
| ty: &'a Binder<T>, |
| ) -> (T, chalk_ir::VariableKinds<RustInterner<'tcx>>, BTreeMap<DefId, u32>) { |
| let mut bound_vars_collector = BoundVarsCollector::new(); |
| ty.as_ref().skip_binder().visit_with(&mut bound_vars_collector); |
| let mut parameters = bound_vars_collector.parameters; |
| let named_parameters: BTreeMap<DefId, u32> = bound_vars_collector |
| .named_parameters |
| .into_iter() |
| .enumerate() |
| .map(|(i, def_id)| (def_id, (i + parameters.len()) as u32)) |
| .collect(); |
| |
| let mut bound_var_substitutor = NamedBoundVarSubstitutor::new(tcx, &named_parameters); |
| let new_ty = ty.as_ref().skip_binder().fold_with(&mut bound_var_substitutor); |
| |
| for var in named_parameters.values() { |
| parameters.insert(*var, chalk_ir::VariableKind::Lifetime); |
| } |
| |
| (0..parameters.len()).for_each(|i| { |
| parameters.get(&(i as u32)).expect(&format!("Skipped bound var index `{:?}`.", i)); |
| }); |
| |
| let binders = chalk_ir::VariableKinds::from(interner, parameters.into_iter().map(|(_, v)| v)); |
| |
| (new_ty, binders, named_parameters) |
| } |
| |
| crate struct BoundVarsCollector<'tcx> { |
| binder_index: ty::DebruijnIndex, |
| crate parameters: BTreeMap<u32, chalk_ir::VariableKind<RustInterner<'tcx>>>, |
| crate named_parameters: Vec<DefId>, |
| } |
| |
| impl<'tcx> BoundVarsCollector<'tcx> { |
| crate fn new() -> Self { |
| BoundVarsCollector { |
| binder_index: ty::INNERMOST, |
| parameters: BTreeMap::new(), |
| named_parameters: vec![], |
| } |
| } |
| } |
| |
| impl<'tcx> TypeVisitor<'tcx> for BoundVarsCollector<'tcx> { |
| fn visit_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> bool { |
| self.binder_index.shift_in(1); |
| let result = t.super_visit_with(self); |
| self.binder_index.shift_out(1); |
| result |
| } |
| |
| fn visit_ty(&mut self, t: Ty<'tcx>) -> bool { |
| match t.kind { |
| ty::Bound(debruijn, bound_ty) if debruijn == self.binder_index => { |
| match self.parameters.entry(bound_ty.var.as_u32()) { |
| Entry::Vacant(entry) => { |
| entry.insert(chalk_ir::VariableKind::Ty(chalk_ir::TyKind::General)); |
| } |
| Entry::Occupied(entry) => match entry.get() { |
| chalk_ir::VariableKind::Ty(_) => {} |
| _ => panic!(), |
| }, |
| } |
| } |
| |
| _ => (), |
| }; |
| |
| t.super_visit_with(self) |
| } |
| |
| fn visit_region(&mut self, r: Region<'tcx>) -> bool { |
| match r { |
| ty::ReLateBound(index, br) if *index == self.binder_index => match br { |
| ty::BoundRegion::BrNamed(def_id, _name) => { |
| if self.named_parameters.iter().find(|d| *d == def_id).is_none() { |
| self.named_parameters.push(*def_id); |
| } |
| } |
| |
| ty::BoundRegion::BrAnon(var) => match self.parameters.entry(*var) { |
| Entry::Vacant(entry) => { |
| entry.insert(chalk_ir::VariableKind::Lifetime); |
| } |
| Entry::Occupied(entry) => match entry.get() { |
| chalk_ir::VariableKind::Lifetime => {} |
| _ => panic!(), |
| }, |
| }, |
| |
| ty::BrEnv => unimplemented!(), |
| }, |
| |
| ty::ReEarlyBound(_re) => { |
| // FIXME(chalk): jackh726 - I think we should always have already |
| // substituted away `ReEarlyBound`s for `ReLateBound`s, but need to confirm. |
| unimplemented!(); |
| } |
| |
| _ => (), |
| }; |
| |
| r.super_visit_with(self) |
| } |
| } |
| |
| /// This is used to replace `BoundRegion::BrNamed` with `BoundRegion::BrAnon`. |
| /// Note: we assume that we will always have room for more bound vars. (i.e. we |
| /// won't ever hit the `u32` limit in `BrAnon`s). |
| struct NamedBoundVarSubstitutor<'a, 'tcx> { |
| tcx: TyCtxt<'tcx>, |
| binder_index: ty::DebruijnIndex, |
| named_parameters: &'a BTreeMap<DefId, u32>, |
| } |
| |
| impl<'a, 'tcx> NamedBoundVarSubstitutor<'a, 'tcx> { |
| fn new(tcx: TyCtxt<'tcx>, named_parameters: &'a BTreeMap<DefId, u32>) -> Self { |
| NamedBoundVarSubstitutor { tcx, binder_index: ty::INNERMOST, named_parameters } |
| } |
| } |
| |
| impl<'a, 'tcx> TypeFolder<'tcx> for NamedBoundVarSubstitutor<'a, 'tcx> { |
| fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { |
| self.tcx |
| } |
| |
| fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> Binder<T> { |
| self.binder_index.shift_in(1); |
| let result = t.super_fold_with(self); |
| self.binder_index.shift_out(1); |
| result |
| } |
| |
| fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { |
| t.super_fold_with(self) |
| } |
| |
| fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> { |
| match r { |
| ty::ReLateBound(index, br) if *index == self.binder_index => match br { |
| ty::BoundRegion::BrNamed(def_id, _name) => { |
| match self.named_parameters.get(def_id) { |
| Some(idx) => { |
| return self.tcx.mk_region(RegionKind::ReLateBound( |
| *index, |
| BoundRegion::BrAnon(*idx), |
| )); |
| } |
| None => panic!("Missing `BrNamed`."), |
| } |
| } |
| ty::BrEnv => unimplemented!(), |
| ty::BoundRegion::BrAnon(_) => {} |
| }, |
| _ => (), |
| }; |
| |
| r.super_fold_with(self) |
| } |
| } |
| |
| /// Used to substitute `Param`s with placeholders. We do this since Chalk |
| /// have a notion of `Param`s. |
| crate struct ParamsSubstitutor<'tcx> { |
| tcx: TyCtxt<'tcx>, |
| binder_index: ty::DebruijnIndex, |
| list: Vec<rustc_middle::ty::ParamTy>, |
| crate params: rustc_data_structures::fx::FxHashMap<usize, rustc_middle::ty::ParamTy>, |
| crate named_regions: BTreeMap<DefId, u32>, |
| } |
| |
| impl<'tcx> ParamsSubstitutor<'tcx> { |
| crate fn new(tcx: TyCtxt<'tcx>) -> Self { |
| ParamsSubstitutor { |
| tcx, |
| binder_index: ty::INNERMOST, |
| list: vec![], |
| params: rustc_data_structures::fx::FxHashMap::default(), |
| named_regions: BTreeMap::default(), |
| } |
| } |
| } |
| |
| impl<'tcx> TypeFolder<'tcx> for ParamsSubstitutor<'tcx> { |
| fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { |
| self.tcx |
| } |
| |
| fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> Binder<T> { |
| self.binder_index.shift_in(1); |
| let result = t.super_fold_with(self); |
| self.binder_index.shift_out(1); |
| result |
| } |
| |
| fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { |
| match t.kind { |
| // FIXME(chalk): currently we convert params to placeholders starting at |
| // index `0`. To support placeholders, we'll actually need to do a |
| // first pass to collect placeholders. Then we can insert params after. |
| ty::Placeholder(_) => unimplemented!(), |
| ty::Param(param) => match self.list.iter().position(|r| r == ¶m) { |
| Some(_idx) => self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType { |
| universe: ty::UniverseIndex::from_usize(0), |
| name: ty::BoundVar::from_usize(_idx), |
| })), |
| None => { |
| self.list.push(param); |
| let idx = self.list.len() - 1; |
| self.params.insert(idx, param); |
| self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType { |
| universe: ty::UniverseIndex::from_usize(0), |
| name: ty::BoundVar::from_usize(idx), |
| })) |
| } |
| }, |
| |
| _ => t.super_fold_with(self), |
| } |
| } |
| |
| fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> { |
| match r { |
| // FIXME(chalk) - jackh726 - this currently isn't hit in any tests. |
| // This covers any region variables in a goal, right? |
| ty::ReEarlyBound(_re) => match self.named_regions.get(&_re.def_id) { |
| Some(idx) => self.tcx.mk_region(RegionKind::ReLateBound( |
| self.binder_index, |
| BoundRegion::BrAnon(*idx), |
| )), |
| None => { |
| let idx = self.named_regions.len() as u32; |
| self.named_regions.insert(_re.def_id, idx); |
| self.tcx.mk_region(RegionKind::ReLateBound( |
| self.binder_index, |
| BoundRegion::BrAnon(idx), |
| )) |
| } |
| }, |
| |
| _ => r.super_fold_with(self), |
| } |
| } |
| } |
