Remove chalk from the compiler

4 files changed, 1 insertions, 2203 deletions

diff --git a/compiler/rustc_traits/src/chalk/db.rs b/compiler/rustc_traits/src/chalk/db.rs
deleted file mode 100644
index 0435cd63e80..00000000000
--- a/compiler/rustc_traits/src/chalk/db.rs
+++ /dev/null
@@ -1,796 +0,0 @@
-//! Provides the `RustIrDatabase` implementation for `chalk-solve`
-//!
-//! The purpose of the `chalk_solve::RustIrDatabase` is to get data about
-//! specific types, such as bounds, where clauses, or fields. This file contains
-//! the minimal logic to assemble the types for `chalk-solve` by calling out to
-//! either the `TyCtxt` (for information about types) or
-//! `crate::chalk::lowering` (to lower rustc types into Chalk types).
-
-use rustc_middle::traits::ChalkRustInterner as RustInterner;
-use rustc_middle::ty::{self, AssocKind, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable};
-use rustc_middle::ty::{InternalSubsts, SubstsRef};
-use rustc_target::abi::{Integer, IntegerType};
-
-use rustc_ast::ast;
-
-use rustc_hir::def_id::DefId;
-
-use rustc_span::symbol::sym;
-
-use std::fmt;
-use std::sync::Arc;
-
-use crate::chalk::lowering::LowerInto;
-
-pub struct RustIrDatabase<'tcx> {
-    pub(crate) interner: RustInterner<'tcx>,
-}
-
-impl fmt::Debug for RustIrDatabase<'_> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "RustIrDatabase")
-    }
-}
-
-impl<'tcx> RustIrDatabase<'tcx> {
-    fn where_clauses_for(
-        &self,
-        def_id: DefId,
-        bound_vars: SubstsRef<'tcx>,
-    ) -> Vec<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>> {
-        self.interner
-            .tcx
-            .predicates_defined_on(def_id)
-            .instantiate_own(self.interner.tcx, bound_vars)
-            .filter_map(|(wc, _)| LowerInto::lower_into(wc.as_predicate(), self.interner))
-            .collect()
-    }
-
-    fn bounds_for<T>(&self, def_id: DefId, bound_vars: SubstsRef<'tcx>) -> Vec<T>
-    where
-        ty::Predicate<'tcx>: LowerInto<'tcx, std::option::Option<T>>,
-    {
-        self.interner
-            .tcx
-            .explicit_item_bounds(def_id)
-            .subst_iter_copied(self.interner.tcx, &bound_vars)
-            .filter_map(|(bound, _)| {
-                LowerInto::<Option<_>>::lower_into(bound.as_predicate(), self.interner)
-            })
-            .collect()
-    }
-}
-
-impl<'tcx> chalk_solve::RustIrDatabase<RustInterner<'tcx>> for RustIrDatabase<'tcx> {
-    fn interner(&self) -> RustInterner<'tcx> {
-        self.interner
-    }
-
-    fn associated_ty_data(
-        &self,
-        assoc_type_id: chalk_ir::AssocTypeId<RustInterner<'tcx>>,
-    ) -> Arc<chalk_solve::rust_ir::AssociatedTyDatum<RustInterner<'tcx>>> {
-        let def_id = assoc_type_id.0;
-        let assoc_item = self.interner.tcx.associated_item(def_id);
-        let Some(trait_def_id) = assoc_item.trait_container(self.interner.tcx) else {
-            unimplemented!("Not possible??");
-        };
-        match assoc_item.kind {
-            AssocKind::Type => {}
-            _ => unimplemented!("Not possible??"),
-        }
-        let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
-        let binders = binders_for(self.interner, bound_vars);
-
-        let where_clauses = self.where_clauses_for(def_id, bound_vars);
-        let bounds = self.bounds_for(def_id, bound_vars);
-
-        Arc::new(chalk_solve::rust_ir::AssociatedTyDatum {
-            trait_id: chalk_ir::TraitId(trait_def_id),
-            id: assoc_type_id,
-            name: (),
-            binders: chalk_ir::Binders::new(
-                binders,
-                chalk_solve::rust_ir::AssociatedTyDatumBound { bounds, where_clauses },
-            ),
-        })
-    }
-
-    fn trait_datum(
-        &self,
-        trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
-    ) -> Arc<chalk_solve::rust_ir::TraitDatum<RustInterner<'tcx>>> {
-        use chalk_solve::rust_ir::WellKnownTrait::*;
-
-        let def_id = trait_id.0;
-        let trait_def = self.interner.tcx.trait_def(def_id);
-
-        let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
-        let binders = binders_for(self.interner, bound_vars);
-
-        let where_clauses = self.where_clauses_for(def_id, bound_vars);
-
-        let associated_ty_ids: Vec<_> = self
-            .interner
-            .tcx
-            .associated_items(def_id)
-            .in_definition_order()
-            .filter(|i| i.kind == AssocKind::Type)
-            .map(|i| chalk_ir::AssocTypeId(i.def_id))
-            .collect();
-
-        let lang_items = self.interner.tcx.lang_items();
-        let well_known = if lang_items.sized_trait() == Some(def_id) {
-            Some(Sized)
-        } else if lang_items.copy_trait() == Some(def_id) {
-            Some(Copy)
-        } else if lang_items.clone_trait() == Some(def_id) {
-            Some(Clone)
-        } else if lang_items.drop_trait() == Some(def_id) {
-            Some(Drop)
-        } else if lang_items.fn_trait() == Some(def_id) {
-            Some(Fn)
-        } else if lang_items.fn_once_trait() == Some(def_id) {
-            Some(FnOnce)
-        } else if lang_items.fn_mut_trait() == Some(def_id) {
-            Some(FnMut)
-        } else if lang_items.unsize_trait() == Some(def_id) {
-            Some(Unsize)
-        } else if lang_items.unpin_trait() == Some(def_id) {
-            Some(Unpin)
-        } else if lang_items.coerce_unsized_trait() == Some(def_id) {
-            Some(CoerceUnsized)
-        } else if lang_items.dispatch_from_dyn_trait() == Some(def_id) {
-            Some(DispatchFromDyn)
-        } else if lang_items.tuple_trait() == Some(def_id) {
-            Some(Tuple)
-        } else {
-            None
-        };
-        Arc::new(chalk_solve::rust_ir::TraitDatum {
-            id: trait_id,
-            binders: chalk_ir::Binders::new(
-                binders,
-                chalk_solve::rust_ir::TraitDatumBound { where_clauses },
-            ),
-            flags: chalk_solve::rust_ir::TraitFlags {
-                auto: trait_def.has_auto_impl,
-                marker: trait_def.is_marker,
-                upstream: !def_id.is_local(),
-                fundamental: self.interner.tcx.has_attr(def_id, sym::fundamental),
-                non_enumerable: true,
-                coinductive: false,
-            },
-            associated_ty_ids,
-            well_known,
-        })
-    }
-
-    fn adt_datum(
-        &self,
-        adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
-    ) -> Arc<chalk_solve::rust_ir::AdtDatum<RustInterner<'tcx>>> {
-        let adt_def = adt_id.0;
-
-        let bound_vars = bound_vars_for_item(self.interner.tcx, adt_def.did());
-        let binders = binders_for(self.interner, bound_vars);
-
-        let where_clauses = self.where_clauses_for(adt_def.did(), bound_vars);
-
-        let variants: Vec<_> = adt_def
-            .variants()
-            .iter()
-            .map(|variant| chalk_solve::rust_ir::AdtVariantDatum {
-                fields: variant
-                    .fields
-                    .iter()
-                    .map(|field| field.ty(self.interner.tcx, bound_vars).lower_into(self.interner))
-                    .collect(),
-            })
-            .collect();
-        Arc::new(chalk_solve::rust_ir::AdtDatum {
-            id: adt_id,
-            binders: chalk_ir::Binders::new(
-                binders,
-                chalk_solve::rust_ir::AdtDatumBound { variants, where_clauses },
-            ),
-            flags: chalk_solve::rust_ir::AdtFlags {
-                upstream: !adt_def.did().is_local(),
-                fundamental: adt_def.is_fundamental(),
-                phantom_data: adt_def.is_phantom_data(),
-            },
-            kind: match adt_def.adt_kind() {
-                ty::AdtKind::Struct => chalk_solve::rust_ir::AdtKind::Struct,
-                ty::AdtKind::Union => chalk_solve::rust_ir::AdtKind::Union,
-                ty::AdtKind::Enum => chalk_solve::rust_ir::AdtKind::Enum,
-            },
-        })
-    }
-
-    fn adt_repr(
-        &self,
-        adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
-    ) -> Arc<chalk_solve::rust_ir::AdtRepr<RustInterner<'tcx>>> {
-        let adt_def = adt_id.0;
-        let int = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(i)).intern(self.interner);
-        let uint = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Uint(i)).intern(self.interner);
-        Arc::new(chalk_solve::rust_ir::AdtRepr {
-            c: adt_def.repr().c(),
-            packed: adt_def.repr().packed(),
-            int: adt_def.repr().int.map(|i| match i {
-                IntegerType::Pointer(true) => int(chalk_ir::IntTy::Isize),
-                IntegerType::Pointer(false) => uint(chalk_ir::UintTy::Usize),
-                IntegerType::Fixed(i, true) => match i {
-                    Integer::I8 => int(chalk_ir::IntTy::I8),
-                    Integer::I16 => int(chalk_ir::IntTy::I16),
-                    Integer::I32 => int(chalk_ir::IntTy::I32),
-                    Integer::I64 => int(chalk_ir::IntTy::I64),
-                    Integer::I128 => int(chalk_ir::IntTy::I128),
-                },
-                IntegerType::Fixed(i, false) => match i {
-                    Integer::I8 => uint(chalk_ir::UintTy::U8),
-                    Integer::I16 => uint(chalk_ir::UintTy::U16),
-                    Integer::I32 => uint(chalk_ir::UintTy::U32),
-                    Integer::I64 => uint(chalk_ir::UintTy::U64),
-                    Integer::I128 => uint(chalk_ir::UintTy::U128),
-                },
-            }),
-        })
-    }
-
-    fn adt_size_align(
-        &self,
-        adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
-    ) -> Arc<chalk_solve::rust_ir::AdtSizeAlign> {
-        let tcx = self.interner.tcx;
-        let did = adt_id.0.did();
-
-        // Grab the ADT and the param we might need to calculate its layout
-        let param_env = tcx.param_env(did);
-        let adt_ty = tcx.type_of(did).subst_identity();
-
-        // The ADT is a 1-zst if it's a ZST and its alignment is 1.
-        // Mark the ADT as _not_ a 1-zst if there was a layout error.
-        let one_zst = if let Ok(layout) = tcx.layout_of(param_env.and(adt_ty)) {
-            layout.is_zst() && layout.align.abi.bytes() == 1
-        } else {
-            false
-        };
-
-        Arc::new(chalk_solve::rust_ir::AdtSizeAlign::from_one_zst(one_zst))
-    }
-
-    fn fn_def_datum(
-        &self,
-        fn_def_id: chalk_ir::FnDefId<RustInterner<'tcx>>,
-    ) -> Arc<chalk_solve::rust_ir::FnDefDatum<RustInterner<'tcx>>> {
-        let def_id = fn_def_id.0;
-        let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
-        let binders = binders_for(self.interner, bound_vars);
-
-        let where_clauses = self.where_clauses_for(def_id, bound_vars);
-
-        let sig = self.interner.tcx.fn_sig(def_id);
-        let (inputs_and_output, iobinders, _) = crate::chalk::lowering::collect_bound_vars(
-            self.interner,
-            self.interner.tcx,
-            sig.map_bound(|s| s.inputs_and_output()).subst(self.interner.tcx, bound_vars),
-        );
-
-        let argument_types = inputs_and_output[..inputs_and_output.len() - 1]
-            .iter()
-            .map(|t| sig.rebind(*t).subst(self.interner.tcx, &bound_vars).lower_into(self.interner))
-            .collect();
-
-        let return_type = sig
-            .rebind(inputs_and_output[inputs_and_output.len() - 1])
-            .subst(self.interner.tcx, &bound_vars)
-            .lower_into(self.interner);
-
-        let bound = chalk_solve::rust_ir::FnDefDatumBound {
-            inputs_and_output: chalk_ir::Binders::new(
-                iobinders,
-                chalk_solve::rust_ir::FnDefInputsAndOutputDatum { argument_types, return_type },
-            ),
-            where_clauses,
-        };
-        Arc::new(chalk_solve::rust_ir::FnDefDatum {
-            id: fn_def_id,
-            sig: sig.skip_binder().lower_into(self.interner),
-            binders: chalk_ir::Binders::new(binders, bound),
-        })
-    }
-
-    fn impl_datum(
-        &self,
-        impl_id: chalk_ir::ImplId<RustInterner<'tcx>>,
-    ) -> Arc<chalk_solve::rust_ir::ImplDatum<RustInterner<'tcx>>> {
-        let def_id = impl_id.0;
-        let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
-        let binders = binders_for(self.interner, bound_vars);
-
-        let trait_ref = self.interner.tcx.impl_trait_ref(def_id).expect("not an impl");
-        let trait_ref = trait_ref.subst(self.interner.tcx, bound_vars);
-
-        let where_clauses = self.where_clauses_for(def_id, bound_vars);
-
-        let value = chalk_solve::rust_ir::ImplDatumBound {
-            trait_ref: trait_ref.lower_into(self.interner),
-            where_clauses,
-        };
-
-        let associated_ty_value_ids: Vec<_> = self
-            .interner
-            .tcx
-            .associated_items(def_id)
-            .in_definition_order()
-            .filter(|i| i.kind == AssocKind::Type)
-            .map(|i| chalk_solve::rust_ir::AssociatedTyValueId(i.def_id))
-            .collect();
-
-        Arc::new(chalk_solve::rust_ir::ImplDatum {
-            polarity: self.interner.tcx.impl_polarity(def_id).lower_into(self.interner),
-            binders: chalk_ir::Binders::new(binders, value),
-            impl_type: chalk_solve::rust_ir::ImplType::Local,
-            associated_ty_value_ids,
-        })
-    }
-
-    fn impls_for_trait(
-        &self,
-        trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
-        parameters: &[chalk_ir::GenericArg<RustInterner<'tcx>>],
-        _binders: &chalk_ir::CanonicalVarKinds<RustInterner<'tcx>>,
-    ) -> Vec<chalk_ir::ImplId<RustInterner<'tcx>>> {
-        let def_id = trait_id.0;
-
-        // FIXME(chalk): use TraitDef::for_each_relevant_impl, but that will
-        // require us to be able to interconvert `Ty<'tcx>`, and we're
-        // not there yet.
-
-        let all_impls = self.interner.tcx.all_impls(def_id);
-        let matched_impls = all_impls.filter(|impl_def_id| {
-            use chalk_ir::could_match::CouldMatch;
-            let trait_ref = self.interner.tcx.impl_trait_ref(*impl_def_id).unwrap();
-            let bound_vars = bound_vars_for_item(self.interner.tcx, *impl_def_id);
-
-            let self_ty = trait_ref.map_bound(|t| t.self_ty());
-            let self_ty = self_ty.subst(self.interner.tcx, bound_vars);
-            let lowered_ty = self_ty.lower_into(self.interner);
-
-            parameters[0].assert_ty_ref(self.interner).could_match(
-                self.interner,
-                self.unification_database(),
-                &lowered_ty,
-            )
-        });
-
-        let impls = matched_impls.map(chalk_ir::ImplId).collect();
-        impls
-    }
-
-    fn impl_provided_for(
-        &self,
-        auto_trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
-        chalk_ty: &chalk_ir::TyKind<RustInterner<'tcx>>,
-    ) -> bool {
-        use chalk_ir::Scalar::*;
-        use chalk_ir::TyKind::*;
-
-        let trait_def_id = auto_trait_id.0;
-        let all_impls = self.interner.tcx.all_impls(trait_def_id);
-        for impl_def_id in all_impls {
-            let trait_ref = self.interner.tcx.impl_trait_ref(impl_def_id).unwrap().subst_identity();
-            let self_ty = trait_ref.self_ty();
-            let provides = match (self_ty.kind(), chalk_ty) {
-                (&ty::Adt(impl_adt_def, ..), Adt(id, ..)) => impl_adt_def.did() == id.0.did(),
-                (_, AssociatedType(_ty_id, ..)) => {
-                    // FIXME(chalk): See https://github.com/rust-lang/rust/pull/77152#discussion_r494484774
-                    false
-                }
-                (ty::Bool, Scalar(Bool)) => true,
-                (ty::Char, Scalar(Char)) => true,
-                (ty::Int(ty1), Scalar(Int(ty2))) => matches!(
-                    (ty1, ty2),
-                    (ty::IntTy::Isize, chalk_ir::IntTy::Isize)
-                        | (ty::IntTy::I8, chalk_ir::IntTy::I8)
-                        | (ty::IntTy::I16, chalk_ir::IntTy::I16)
-                        | (ty::IntTy::I32, chalk_ir::IntTy::I32)
-                        | (ty::IntTy::I64, chalk_ir::IntTy::I64)
-                        | (ty::IntTy::I128, chalk_ir::IntTy::I128)
-                ),
-                (ty::Uint(ty1), Scalar(Uint(ty2))) => matches!(
-                    (ty1, ty2),
-                    (ty::UintTy::Usize, chalk_ir::UintTy::Usize)
-                        | (ty::UintTy::U8, chalk_ir::UintTy::U8)
-                        | (ty::UintTy::U16, chalk_ir::UintTy::U16)
-                        | (ty::UintTy::U32, chalk_ir::UintTy::U32)
-                        | (ty::UintTy::U64, chalk_ir::UintTy::U64)
-                        | (ty::UintTy::U128, chalk_ir::UintTy::U128)
-                ),
-                (ty::Float(ty1), Scalar(Float(ty2))) => matches!(
-                    (ty1, ty2),
-                    (ty::FloatTy::F32, chalk_ir::FloatTy::F32)
-                        | (ty::FloatTy::F64, chalk_ir::FloatTy::F64)
-                ),
-                (&ty::Tuple(substs), Tuple(len, _)) => substs.len() == *len,
-                (&ty::Array(..), Array(..)) => true,
-                (&ty::Slice(..), Slice(..)) => true,
-                (&ty::RawPtr(type_and_mut), Raw(mutability, _)) => {
-                    match (type_and_mut.mutbl, mutability) {
-                        (ast::Mutability::Mut, chalk_ir::Mutability::Mut) => true,
-                        (ast::Mutability::Mut, chalk_ir::Mutability::Not) => false,
-                        (ast::Mutability::Not, chalk_ir::Mutability::Mut) => false,
-                        (ast::Mutability::Not, chalk_ir::Mutability::Not) => true,
-                    }
-                }
-                (&ty::Ref(.., mutability1), Ref(mutability2, ..)) => {
-                    match (mutability1, mutability2) {
-                        (ast::Mutability::Mut, chalk_ir::Mutability::Mut) => true,
-                        (ast::Mutability::Mut, chalk_ir::Mutability::Not) => false,
-                        (ast::Mutability::Not, chalk_ir::Mutability::Mut) => false,
-                        (ast::Mutability::Not, chalk_ir::Mutability::Not) => true,
-                    }
-                }
-                (
-                    &ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }),
-                    OpaqueType(opaque_ty_id, ..),
-                ) => def_id == opaque_ty_id.0,
-                (&ty::FnDef(def_id, ..), FnDef(fn_def_id, ..)) => def_id == fn_def_id.0,
-                (&ty::Str, Str) => true,
-                (&ty::Never, Never) => true,
-                (&ty::Closure(def_id, ..), Closure(closure_id, _)) => def_id == closure_id.0,
-                (&ty::Foreign(def_id), Foreign(foreign_def_id)) => def_id == foreign_def_id.0,
-                (&ty::Error(..), Error) => false,
-                _ => false,
-            };
-            if provides {
-                return true;
-            }
-        }
-        false
-    }
-
-    fn associated_ty_value(
-        &self,
-        associated_ty_id: chalk_solve::rust_ir::AssociatedTyValueId<RustInterner<'tcx>>,
-    ) -> Arc<chalk_solve::rust_ir::AssociatedTyValue<RustInterner<'tcx>>> {
-        let def_id = associated_ty_id.0;
-        let assoc_item = self.interner.tcx.associated_item(def_id);
-        let impl_id = assoc_item.container_id(self.interner.tcx);
-        match assoc_item.kind {
-            AssocKind::Type => {}
-            _ => unimplemented!("Not possible??"),
-        }
-
-        let trait_item_id = assoc_item.trait_item_def_id.expect("assoc_ty with no trait version");
-        let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
-        let binders = binders_for(self.interner, bound_vars);
-        let ty = self
-            .interner
-            .tcx
-            .type_of(def_id)
-            .subst(self.interner.tcx, bound_vars)
-            .lower_into(self.interner);
-
-        Arc::new(chalk_solve::rust_ir::AssociatedTyValue {
-            impl_id: chalk_ir::ImplId(impl_id),
-            associated_ty_id: chalk_ir::AssocTypeId(trait_item_id),
-            value: chalk_ir::Binders::new(
-                binders,
-                chalk_solve::rust_ir::AssociatedTyValueBound { ty },
-            ),
-        })
-    }
-
-    fn custom_clauses(&self) -> Vec<chalk_ir::ProgramClause<RustInterner<'tcx>>> {
-        vec![]
-    }
-
-    fn local_impls_to_coherence_check(
-        &self,
-        _trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
-    ) -> Vec<chalk_ir::ImplId<RustInterner<'tcx>>> {
-        unimplemented!()
-    }
-
-    fn opaque_ty_data(
-        &self,
-        opaque_ty_id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>,
-    ) -> Arc<chalk_solve::rust_ir::OpaqueTyDatum<RustInterner<'tcx>>> {
-        let bound_vars = ty::fold::shift_vars(
-            self.interner.tcx,
-            bound_vars_for_item(self.interner.tcx, opaque_ty_id.0),
-            1,
-        );
-        let where_clauses = self.where_clauses_for(opaque_ty_id.0, bound_vars);
-
-        let identity_substs = InternalSubsts::identity_for_item(self.interner.tcx, opaque_ty_id.0);
-
-        let explicit_item_bounds = self.interner.tcx.explicit_item_bounds(opaque_ty_id.0);
-        let bounds =
-            explicit_item_bounds
-                .subst_iter_copied(self.interner.tcx, &bound_vars)
-                .map(|(bound, _)| {
-                    bound.fold_with(&mut ReplaceOpaqueTyFolder {
-                        tcx: self.interner.tcx,
-                        opaque_ty_id,
-                        identity_substs,
-                        binder_index: ty::INNERMOST,
-                    })
-                })
-                .filter_map(|bound| {
-                    LowerInto::<
-                    Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>
-                >::lower_into(bound.as_predicate(), self.interner)
-                })
-                .collect();
-
-        // Binder for the bound variable representing the concrete impl Trait type.
-        let existential_binder = chalk_ir::VariableKinds::from1(
-            self.interner,
-            chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General),
-        );
-
-        let value = chalk_solve::rust_ir::OpaqueTyDatumBound {
-            bounds: chalk_ir::Binders::new(existential_binder.clone(), bounds),
-            where_clauses: chalk_ir::Binders::new(existential_binder, where_clauses),
-        };
-
-        let binders = binders_for(self.interner, bound_vars);
-        Arc::new(chalk_solve::rust_ir::OpaqueTyDatum {
-            opaque_ty_id,
-            bound: chalk_ir::Binders::new(binders, value),
-        })
-    }
-
-    fn program_clauses_for_env(
-        &self,
-        environment: &chalk_ir::Environment<RustInterner<'tcx>>,
-    ) -> chalk_ir::ProgramClauses<RustInterner<'tcx>> {
-        chalk_solve::program_clauses_for_env(self, environment)
-    }
-
-    fn well_known_trait_id(
-        &self,
-        well_known_trait: chalk_solve::rust_ir::WellKnownTrait,
-    ) -> Option<chalk_ir::TraitId<RustInterner<'tcx>>> {
-        use chalk_solve::rust_ir::WellKnownTrait::*;
-        let lang_items = self.interner.tcx.lang_items();
-        let def_id = match well_known_trait {
-            Sized => lang_items.sized_trait(),
-            Copy => lang_items.copy_trait(),
-            Clone => lang_items.clone_trait(),
-            Drop => lang_items.drop_trait(),
-            Fn => lang_items.fn_trait(),
-            FnMut => lang_items.fn_mut_trait(),
-            FnOnce => lang_items.fn_once_trait(),
-            Generator => lang_items.gen_trait(),
-            Unsize => lang_items.unsize_trait(),
-            Unpin => lang_items.unpin_trait(),
-            CoerceUnsized => lang_items.coerce_unsized_trait(),
-            DiscriminantKind => lang_items.discriminant_kind_trait(),
-            DispatchFromDyn => lang_items.dispatch_from_dyn_trait(),
-            Tuple => lang_items.tuple_trait(),
-            Pointee => lang_items.pointee_trait(),
-            FnPtr => lang_items.fn_ptr_trait(),
-        };
-        def_id.map(chalk_ir::TraitId)
-    }
-
-    fn is_object_safe(&self, trait_id: chalk_ir::TraitId<RustInterner<'tcx>>) -> bool {
-        self.interner.tcx.check_is_object_safe(trait_id.0)
-    }
-
-    fn hidden_opaque_type(
-        &self,
-        _id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>,
-    ) -> chalk_ir::Ty<RustInterner<'tcx>> {
-        // FIXME(chalk): actually get hidden ty
-        self.interner.tcx.types.unit.lower_into(self.interner)
-    }
-
-    fn closure_kind(
-        &self,
-        _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
-        substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
-    ) -> chalk_solve::rust_ir::ClosureKind {
-        let kind = &substs.as_slice(self.interner)[substs.len(self.interner) - 3];
-        match kind.assert_ty_ref(self.interner).kind(self.interner) {
-            chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(int_ty)) => match int_ty {
-                chalk_ir::IntTy::I8 => chalk_solve::rust_ir::ClosureKind::Fn,
-                chalk_ir::IntTy::I16 => chalk_solve::rust_ir::ClosureKind::FnMut,
-                chalk_ir::IntTy::I32 => chalk_solve::rust_ir::ClosureKind::FnOnce,
-                _ => bug!("bad closure kind"),
-            },
-            _ => bug!("bad closure kind"),
-        }
-    }
-
-    fn closure_inputs_and_output(
-        &self,
-        _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
-        substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
-    ) -> chalk_ir::Binders<chalk_solve::rust_ir::FnDefInputsAndOutputDatum<RustInterner<'tcx>>>
-    {
-        let sig = &substs.as_slice(self.interner)[substs.len(self.interner) - 2];
-        match sig.assert_ty_ref(self.interner).kind(self.interner) {
-            chalk_ir::TyKind::Function(f) => {
-                let substitution = f.substitution.0.as_slice(self.interner);
-                let return_type = substitution.last().unwrap().assert_ty_ref(self.interner).clone();
-                // Closure arguments are tupled
-                let argument_tuple = substitution[0].assert_ty_ref(self.interner);
-                let argument_types = match argument_tuple.kind(self.interner) {
-                    chalk_ir::TyKind::Tuple(_len, substitution) => substitution
-                        .iter(self.interner)
-                        .map(|arg| arg.assert_ty_ref(self.interner))
-                        .cloned()
-                        .collect(),
-                    _ => bug!("Expecting closure FnSig args to be tupled."),
-                };
-
-                chalk_ir::Binders::new(
-                    chalk_ir::VariableKinds::from_iter(
-                        self.interner,
-                        (0..f.num_binders).map(|_| chalk_ir::VariableKind::Lifetime),
-                    ),
-                    chalk_solve::rust_ir::FnDefInputsAndOutputDatum { argument_types, return_type },
-                )
-            }
-            _ => panic!("Invalid sig."),
-        }
-    }
-
-    fn closure_upvars(
-        &self,
-        _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
-        substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
-    ) -> chalk_ir::Binders<chalk_ir::Ty<RustInterner<'tcx>>> {
-        let inputs_and_output = self.closure_inputs_and_output(_closure_id, substs);
-        let tuple = substs.as_slice(self.interner).last().unwrap().assert_ty_ref(self.interner);
-        inputs_and_output.map_ref(|_| tuple.clone())
-    }
-
-    fn closure_fn_substitution(
-        &self,
-        _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
-        substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
-    ) -> chalk_ir::Substitution<RustInterner<'tcx>> {
-        let substitution = &substs.as_slice(self.interner)[0..substs.len(self.interner) - 3];
-        chalk_ir::Substitution::from_iter(self.interner, substitution)
-    }
-
-    fn generator_datum(
-        &self,
-        _generator_id: chalk_ir::GeneratorId<RustInterner<'tcx>>,
-    ) -> Arc<chalk_solve::rust_ir::GeneratorDatum<RustInterner<'tcx>>> {
-        unimplemented!()
-    }
-
-    fn generator_witness_datum(
-        &self,
-        _generator_id: chalk_ir::GeneratorId<RustInterner<'tcx>>,
-    ) -> Arc<chalk_solve::rust_ir::GeneratorWitnessDatum<RustInterner<'tcx>>> {
-        unimplemented!()
-    }
-
-    fn unification_database(&self) -> &dyn chalk_ir::UnificationDatabase<RustInterner<'tcx>> {
-        self
-    }
-
-    fn discriminant_type(
-        &self,
-        _: chalk_ir::Ty<RustInterner<'tcx>>,
-    ) -> chalk_ir::Ty<RustInterner<'tcx>> {
-        unimplemented!()
-    }
-}
-
-impl<'tcx> chalk_ir::UnificationDatabase<RustInterner<'tcx>> for RustIrDatabase<'tcx> {
-    fn fn_def_variance(
-        &self,
-        def_id: chalk_ir::FnDefId<RustInterner<'tcx>>,
-    ) -> chalk_ir::Variances<RustInterner<'tcx>> {
-        let variances = self.interner.tcx.variances_of(def_id.0);
-        chalk_ir::Variances::from_iter(
-            self.interner,
-            variances.iter().map(|v| v.lower_into(self.interner)),
-        )
-    }
-
-    fn adt_variance(
-        &self,
-        adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
-    ) -> chalk_ir::Variances<RustInterner<'tcx>> {
-        let variances = self.interner.tcx.variances_of(adt_id.0.did());
-        chalk_ir::Variances::from_iter(
-            self.interner,
-            variances.iter().map(|v| v.lower_into(self.interner)),
-        )
-    }
-}
-
-/// Creates an `InternalSubsts` that maps each generic parameter to a higher-ranked
-/// var bound at index `0`. For types, we use a `BoundVar` index equal to
-/// the type parameter index. For regions, we use the `BoundRegionKind::BrNamed`
-/// variant (which has a `DefId`).
-fn bound_vars_for_item(tcx: TyCtxt<'_>, def_id: DefId) -> SubstsRef<'_> {
-    InternalSubsts::for_item(tcx, def_id, |param, substs| match param.kind {
-        ty::GenericParamDefKind::Type { .. } => tcx
-            .mk_bound(
-                ty::INNERMOST,
-                ty::BoundTy {
-                    var: ty::BoundVar::from(param.index),
-                    kind: ty::BoundTyKind::Param(param.def_id, param.name),
-                },
-            )
-            .into(),
-
-        ty::GenericParamDefKind::Lifetime => {
-            let br = ty::BoundRegion {
-                var: ty::BoundVar::from_usize(substs.len()),
-                kind: ty::BrAnon(None),
-            };
-            ty::Region::new_late_bound(tcx, ty::INNERMOST, br).into()
-        }
-
-        ty::GenericParamDefKind::Const { .. } => tcx
-            .mk_const(
-                ty::ConstKind::Bound(ty::INNERMOST, ty::BoundVar::from(param.index)),
-                tcx.type_of(param.def_id).subst_identity(),
-            )
-            .into(),
-    })
-}
-
-fn binders_for<'tcx>(
-    interner: RustInterner<'tcx>,
-    bound_vars: SubstsRef<'tcx>,
-) -> chalk_ir::VariableKinds<RustInterner<'tcx>> {
-    chalk_ir::VariableKinds::from_iter(
-        interner,
-        bound_vars.iter().map(|arg| match arg.unpack() {
-            ty::subst::GenericArgKind::Lifetime(_re) => chalk_ir::VariableKind::Lifetime,
-            ty::subst::GenericArgKind::Type(_ty) => {
-                chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General)
-            }
-            ty::subst::GenericArgKind::Const(c) => {
-                chalk_ir::VariableKind::Const(c.ty().lower_into(interner))
-            }
-        }),
-    )
-}
-
-struct ReplaceOpaqueTyFolder<'tcx> {
-    tcx: TyCtxt<'tcx>,
-    opaque_ty_id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>,
-    identity_substs: SubstsRef<'tcx>,
-    binder_index: ty::DebruijnIndex,
-}
-
-impl<'tcx> ty::TypeFolder<TyCtxt<'tcx>> for ReplaceOpaqueTyFolder<'tcx> {
-    fn interner(&self) -> TyCtxt<'tcx> {
-        self.tcx
-    }
-
-    fn fold_binder<T: TypeFoldable<TyCtxt<'tcx>>>(
-        &mut self,
-        t: ty::Binder<'tcx, T>,
-    ) -> ty::Binder<'tcx, T> {
-        self.binder_index.shift_in(1);
-        let t = t.super_fold_with(self);
-        self.binder_index.shift_out(1);
-        t
-    }
-
-    fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
-        if let ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs, .. }) = *ty.kind() {
-            if def_id == self.opaque_ty_id.0 && substs == self.identity_substs {
-                return self
-                    .tcx
-                    .mk_bound(self.binder_index, ty::BoundTy::from(ty::BoundVar::from_u32(0)));
-            }
-        }
-        ty
-    }
-}
diff --git a/compiler/rustc_traits/src/chalk/lowering.rs b/compiler/rustc_traits/src/chalk/lowering.rs
deleted file mode 100644
index b7db56d3db8..00000000000
--- a/compiler/rustc_traits/src/chalk/lowering.rs
+++ /dev/null
@@ -1,1234 +0,0 @@
-//! 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](https://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_ast::ast;
-use rustc_middle::traits::{ChalkEnvironmentAndGoal, ChalkRustInterner as RustInterner};
-use rustc_middle::ty::subst::{GenericArg, GenericArgKind, SubstsRef};
-use rustc_middle::ty::{
-    self, Binder, Region, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable,
-    TypeSuperVisitable, TypeVisitable, TypeVisitor,
-};
-use rustc_span::def_id::DefId;
-
-use chalk_ir::{FnSig, ForeignDefId};
-use rustc_hir::Unsafety;
-use std::collections::btree_map::{BTreeMap, Entry};
-use std::ops::ControlFlow;
-
-/// Essentially an `Into` with a `&RustInterner` parameter
-pub(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_iter(interner, self.iter().map(|s| s.lower_into(interner)))
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, chalk_ir::Substitution<RustInterner<'tcx>>>
-    for &'tcx ty::List<Ty<'tcx>>
-{
-    fn lower_into(
-        self,
-        interner: RustInterner<'tcx>,
-    ) -> chalk_ir::Substitution<RustInterner<'tcx>> {
-        chalk_ir::Substitution::from_iter(
-            interner,
-            self.iter().map(|ty| GenericArg::from(ty).lower_into(interner)),
-        )
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, SubstsRef<'tcx>> for &chalk_ir::Substitution<RustInterner<'tcx>> {
-    fn lower_into(self, interner: RustInterner<'tcx>) -> SubstsRef<'tcx> {
-        interner
-            .tcx
-            .mk_substs_from_iter(self.iter(interner).map(|subst| subst.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().map(|predicate| {
-            let (predicate, binders, _named_regions) =
-                collect_bound_vars(interner, interner.tcx, predicate.kind());
-            let consequence = match predicate {
-                ty::ClauseKind::TypeWellFormedFromEnv(ty) => {
-                    chalk_ir::DomainGoal::FromEnv(chalk_ir::FromEnv::Ty(ty.lower_into(interner)))
-                }
-                ty::ClauseKind::Trait(predicate) => chalk_ir::DomainGoal::FromEnv(
-                    chalk_ir::FromEnv::Trait(predicate.trait_ref.lower_into(interner)),
-                ),
-                ty::ClauseKind::RegionOutlives(predicate) => chalk_ir::DomainGoal::Holds(
-                    chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives {
-                        a: predicate.0.lower_into(interner),
-                        b: predicate.1.lower_into(interner),
-                    }),
-                ),
-                ty::ClauseKind::TypeOutlives(predicate) => chalk_ir::DomainGoal::Holds(
-                    chalk_ir::WhereClause::TypeOutlives(chalk_ir::TypeOutlives {
-                        ty: predicate.0.lower_into(interner),
-                        lifetime: predicate.1.lower_into(interner),
-                    }),
-                ),
-                ty::ClauseKind::Projection(predicate) => chalk_ir::DomainGoal::Holds(
-                    chalk_ir::WhereClause::AliasEq(predicate.lower_into(interner)),
-                ),
-                ty::ClauseKind::WellFormed(arg) => match arg.unpack() {
-                    ty::GenericArgKind::Type(ty) => chalk_ir::DomainGoal::WellFormed(
-                        chalk_ir::WellFormed::Ty(ty.lower_into(interner)),
-                    ),
-                    // FIXME(chalk): we need to change `WellFormed` in Chalk to take a `GenericArg`
-                    _ => chalk_ir::DomainGoal::WellFormed(chalk_ir::WellFormed::Ty(
-                        interner.tcx.types.unit.lower_into(interner),
-                    )),
-                },
-                ty::ClauseKind::ConstArgHasType(..) | ty::ClauseKind::ConstEvaluatable(_) => {
-                    bug!("unexpected predicate {}", predicate)
-                }
-            };
-            let value = chalk_ir::ProgramClauseImplication {
-                consequence,
-                conditions: chalk_ir::Goals::empty(interner),
-                priority: chalk_ir::ClausePriority::High,
-                constraints: chalk_ir::Constraints::empty(interner),
-            };
-            chalk_ir::ProgramClauseData(chalk_ir::Binders::new(binders, value)).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_iter(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>> {
-        let (predicate, binders, _named_regions) =
-            collect_bound_vars(interner, interner.tcx, self.kind());
-
-        let value = match predicate {
-            ty::PredicateKind::Clause(ty::ClauseKind::Trait(predicate)) => {
-                chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
-                    chalk_ir::WhereClause::Implemented(predicate.trait_ref.lower_into(interner)),
-                ))
-            }
-            ty::PredicateKind::Clause(ty::ClauseKind::RegionOutlives(predicate)) => {
-                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),
-                    }),
-                ))
-            }
-            ty::PredicateKind::Clause(ty::ClauseKind::TypeOutlives(predicate)) => {
-                chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
-                    chalk_ir::WhereClause::TypeOutlives(chalk_ir::TypeOutlives {
-                        ty: predicate.0.lower_into(interner),
-                        lifetime: predicate.1.lower_into(interner),
-                    }),
-                ))
-            }
-            ty::PredicateKind::Clause(ty::ClauseKind::Projection(predicate)) => {
-                chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
-                    chalk_ir::WhereClause::AliasEq(predicate.lower_into(interner)),
-                ))
-            }
-            ty::PredicateKind::Clause(ty::ClauseKind::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::empty(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::empty(interner))
-                }
-                GenericArgKind::Lifetime(lt) => bug!("unexpected well formed predicate: {:?}", lt),
-            },
-
-            ty::PredicateKind::ObjectSafe(t) => chalk_ir::GoalData::DomainGoal(
-                chalk_ir::DomainGoal::ObjectSafe(chalk_ir::TraitId(t)),
-            ),
-
-            ty::PredicateKind::Subtype(ty::SubtypePredicate { a, b, a_is_expected: _ }) => {
-                chalk_ir::GoalData::SubtypeGoal(chalk_ir::SubtypeGoal {
-                    a: a.lower_into(interner),
-                    b: b.lower_into(interner),
-                })
-            }
-
-            // 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::Clause(ty::ClauseKind::ConstArgHasType(..))
-            | ty::PredicateKind::AliasRelate(..)
-            | ty::PredicateKind::Coerce(..)
-            | ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(..))
-            | ty::PredicateKind::Ambiguous
-            | ty::PredicateKind::ConstEquate(..) => {
-                chalk_ir::GoalData::All(chalk_ir::Goals::empty(interner))
-            }
-            ty::PredicateKind::Clause(ty::ClauseKind::TypeWellFormedFromEnv(ty)) => {
-                chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::FromEnv(
-                    chalk_ir::FromEnv::Ty(ty.lower_into(interner)),
-                ))
-            }
-        };
-
-        chalk_ir::GoalData::Quantified(
-            chalk_ir::QuantifierKind::ForAll,
-            chalk_ir::Binders::new(binders, value.intern(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::AliasEq<RustInterner<'tcx>>>
-    for rustc_middle::ty::ProjectionPredicate<'tcx>
-{
-    fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::AliasEq<RustInterner<'tcx>> {
-        // FIXME(associated_const_equality): teach chalk about terms for alias eq.
-        chalk_ir::AliasEq {
-            ty: self.term.ty().unwrap().lower_into(interner),
-            alias: chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy {
-                associated_ty_id: chalk_ir::AssocTypeId(self.projection_ty.def_id),
-                substitution: self.projection_ty.substs.lower_into(interner),
-            }),
-        }
-    }
-}
-
-/*
-// FIXME(...): Where do I add this to Chalk? I can't find it in the rustc repo anywhere.
-impl<'tcx> LowerInto<'tcx, chalk_ir::Term<RustInterner<'tcx>>> for rustc_middle::ty::Term<'tcx> {
-  fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::Term<RustInterner<'tcx>> {
-    match self {
-      ty::Term::Ty(ty) => ty.lower_into(interner).into(),
-      ty::Term::Const(c) => c.lower_into(interner).into(),
-    }
-  }
-}
-*/
-
-impl<'tcx> LowerInto<'tcx, chalk_ir::Ty<RustInterner<'tcx>>> for Ty<'tcx> {
-    fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::Ty<RustInterner<'tcx>> {
-        let int = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(i));
-        let uint = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Uint(i));
-        let float = |f| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Float(f));
-
-        match *self.kind() {
-            ty::Bool => chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Bool),
-            ty::Char => chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Char),
-            ty::Int(ty) => match ty {
-                ty::IntTy::Isize => int(chalk_ir::IntTy::Isize),
-                ty::IntTy::I8 => int(chalk_ir::IntTy::I8),
-                ty::IntTy::I16 => int(chalk_ir::IntTy::I16),
-                ty::IntTy::I32 => int(chalk_ir::IntTy::I32),
-                ty::IntTy::I64 => int(chalk_ir::IntTy::I64),
-                ty::IntTy::I128 => int(chalk_ir::IntTy::I128),
-            },
-            ty::Uint(ty) => match ty {
-                ty::UintTy::Usize => uint(chalk_ir::UintTy::Usize),
-                ty::UintTy::U8 => uint(chalk_ir::UintTy::U8),
-                ty::UintTy::U16 => uint(chalk_ir::UintTy::U16),
-                ty::UintTy::U32 => uint(chalk_ir::UintTy::U32),
-                ty::UintTy::U64 => uint(chalk_ir::UintTy::U64),
-                ty::UintTy::U128 => uint(chalk_ir::UintTy::U128),
-            },
-            ty::Float(ty) => match ty {
-                ty::FloatTy::F32 => float(chalk_ir::FloatTy::F32),
-                ty::FloatTy::F64 => float(chalk_ir::FloatTy::F64),
-            },
-            ty::Adt(def, substs) => {
-                chalk_ir::TyKind::Adt(chalk_ir::AdtId(def), substs.lower_into(interner))
-            }
-            ty::Foreign(def_id) => chalk_ir::TyKind::Foreign(ForeignDefId(def_id)),
-            ty::Str => chalk_ir::TyKind::Str,
-            ty::Array(ty, len) => {
-                chalk_ir::TyKind::Array(ty.lower_into(interner), len.lower_into(interner))
-            }
-            ty::Slice(ty) => chalk_ir::TyKind::Slice(ty.lower_into(interner)),
-
-            ty::RawPtr(ptr) => {
-                chalk_ir::TyKind::Raw(ptr.mutbl.lower_into(interner), ptr.ty.lower_into(interner))
-            }
-            ty::Ref(region, ty, mutability) => chalk_ir::TyKind::Ref(
-                mutability.lower_into(interner),
-                region.lower_into(interner),
-                ty.lower_into(interner),
-            ),
-            ty::FnDef(def_id, substs) => {
-                chalk_ir::TyKind::FnDef(chalk_ir::FnDefId(def_id), substs.lower_into(interner))
-            }
-            ty::FnPtr(sig) => {
-                let (inputs_and_outputs, binders, _named_regions) =
-                    collect_bound_vars(interner, interner.tcx, sig.inputs_and_output());
-                chalk_ir::TyKind::Function(chalk_ir::FnPointer {
-                    num_binders: binders.len(interner),
-                    sig: sig.lower_into(interner),
-                    substitution: chalk_ir::FnSubst(chalk_ir::Substitution::from_iter(
-                        interner,
-                        inputs_and_outputs.iter().map(|ty| {
-                            chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner)
-                        }),
-                    )),
-                })
-            }
-            // FIXME(dyn-star): handle the dynamic kind (dyn or dyn*)
-            ty::Dynamic(predicates, region, _kind) => chalk_ir::TyKind::Dyn(chalk_ir::DynTy {
-                bounds: predicates.lower_into(interner),
-                lifetime: region.lower_into(interner),
-            }),
-            ty::Closure(def_id, substs) => {
-                chalk_ir::TyKind::Closure(chalk_ir::ClosureId(def_id), substs.lower_into(interner))
-            }
-            ty::Generator(def_id, substs, _) => chalk_ir::TyKind::Generator(
-                chalk_ir::GeneratorId(def_id),
-                substs.lower_into(interner),
-            ),
-            ty::GeneratorWitness(_) => unimplemented!(),
-            ty::GeneratorWitnessMIR(..) => unimplemented!(),
-            ty::Never => chalk_ir::TyKind::Never,
-            ty::Tuple(types) => chalk_ir::TyKind::Tuple(types.len(), types.lower_into(interner)),
-            ty::Alias(ty::Projection, ty::AliasTy { def_id, substs, .. }) => {
-                chalk_ir::TyKind::Alias(chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy {
-                    associated_ty_id: chalk_ir::AssocTypeId(def_id),
-                    substitution: substs.lower_into(interner),
-                }))
-            }
-            ty::Alias(ty::Weak, ty::AliasTy { .. }) => unimplemented!(),
-            ty::Alias(ty::Inherent, _) => unimplemented!(),
-            ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs, .. }) => {
-                chalk_ir::TyKind::Alias(chalk_ir::AliasTy::Opaque(chalk_ir::OpaqueTy {
-                    opaque_ty_id: chalk_ir::OpaqueTyId(def_id),
-                    substitution: substs.lower_into(interner),
-                }))
-            }
-            // This should have been done eagerly prior to this, and all Params
-            // should have been substituted to placeholders
-            ty::Param(_) => panic!("Lowering Param when not expected."),
-            ty::Bound(db, bound) => chalk_ir::TyKind::BoundVar(chalk_ir::BoundVar::new(
-                chalk_ir::DebruijnIndex::new(db.as_u32()),
-                bound.var.index(),
-            )),
-            ty::Placeholder(_placeholder) => {
-                chalk_ir::TyKind::Placeholder(chalk_ir::PlaceholderIndex {
-                    ui: chalk_ir::UniverseIndex { counter: _placeholder.universe.as_usize() },
-                    idx: _placeholder.bound.var.as_usize(),
-                })
-            }
-            ty::Infer(_infer) => unimplemented!(),
-            ty::Error(_) => chalk_ir::TyKind::Error,
-        }
-        .intern(interner)
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, Ty<'tcx>> for &chalk_ir::Ty<RustInterner<'tcx>> {
-    fn lower_into(self, interner: RustInterner<'tcx>) -> Ty<'tcx> {
-        use chalk_ir::TyKind;
-
-        let kind = match self.kind(interner) {
-            TyKind::Adt(struct_id, substitution) => {
-                ty::Adt(struct_id.0, substitution.lower_into(interner))
-            }
-            TyKind::Scalar(scalar) => match scalar {
-                chalk_ir::Scalar::Bool => ty::Bool,
-                chalk_ir::Scalar::Char => ty::Char,
-                chalk_ir::Scalar::Int(int_ty) => match int_ty {
-                    chalk_ir::IntTy::Isize => ty::Int(ty::IntTy::Isize),
-                    chalk_ir::IntTy::I8 => ty::Int(ty::IntTy::I8),
-                    chalk_ir::IntTy::I16 => ty::Int(ty::IntTy::I16),
-                    chalk_ir::IntTy::I32 => ty::Int(ty::IntTy::I32),
-                    chalk_ir::IntTy::I64 => ty::Int(ty::IntTy::I64),
-                    chalk_ir::IntTy::I128 => ty::Int(ty::IntTy::I128),
-                },
-                chalk_ir::Scalar::Uint(int_ty) => match int_ty {
-                    chalk_ir::UintTy::Usize => ty::Uint(ty::UintTy::Usize),
-                    chalk_ir::UintTy::U8 => ty::Uint(ty::UintTy::U8),
-                    chalk_ir::UintTy::U16 => ty::Uint(ty::UintTy::U16),
-                    chalk_ir::UintTy::U32 => ty::Uint(ty::UintTy::U32),
-                    chalk_ir::UintTy::U64 => ty::Uint(ty::UintTy::U64),
-                    chalk_ir::UintTy::U128 => ty::Uint(ty::UintTy::U128),
-                },
-                chalk_ir::Scalar::Float(float_ty) => match float_ty {
-                    chalk_ir::FloatTy::F32 => ty::Float(ty::FloatTy::F32),
-                    chalk_ir::FloatTy::F64 => ty::Float(ty::FloatTy::F64),
-                },
-            },
-            TyKind::Array(ty, c) => {
-                let ty = ty.lower_into(interner);
-                let c = c.lower_into(interner);
-                ty::Array(ty, c)
-            }
-            TyKind::FnDef(id, substitution) => ty::FnDef(id.0, substitution.lower_into(interner)),
-            TyKind::Closure(closure, substitution) => {
-                ty::Closure(closure.0, substitution.lower_into(interner))
-            }
-            TyKind::Generator(generator, substitution) => ty::Generator(
-                generator.0,
-                substitution.lower_into(interner),
-                ast::Movability::Static,
-            ),
-            TyKind::GeneratorWitness(..) => unimplemented!(),
-            TyKind::Never => ty::Never,
-            TyKind::Tuple(_len, substitution) => {
-                ty::Tuple(substitution.lower_into(interner).into_type_list(interner.tcx))
-            }
-            TyKind::Slice(ty) => ty::Slice(ty.lower_into(interner)),
-            TyKind::Raw(mutbl, ty) => ty::RawPtr(ty::TypeAndMut {
-                ty: ty.lower_into(interner),
-                mutbl: mutbl.lower_into(interner),
-            }),
-            TyKind::Ref(mutbl, lifetime, ty) => ty::Ref(
-                lifetime.lower_into(interner),
-                ty.lower_into(interner),
-                mutbl.lower_into(interner),
-            ),
-            TyKind::Str => ty::Str,
-            TyKind::OpaqueType(opaque_ty, substitution) => ty::Alias(
-                ty::Opaque,
-                interner.tcx.mk_alias_ty(opaque_ty.0, substitution.lower_into(interner)),
-            ),
-            TyKind::AssociatedType(assoc_ty, substitution) => ty::Alias(
-                ty::Projection,
-                interner.tcx.mk_alias_ty(assoc_ty.0, substitution.lower_into(interner)),
-            ),
-            TyKind::Foreign(def_id) => ty::Foreign(def_id.0),
-            TyKind::Error => return interner.tcx.ty_error_misc(),
-            TyKind::Alias(alias_ty) => match alias_ty {
-                chalk_ir::AliasTy::Projection(projection) => ty::Alias(
-                    ty::Projection,
-                    interner.tcx.mk_alias_ty(
-                        projection.associated_ty_id.0,
-                        projection.substitution.lower_into(interner),
-                    ),
-                ),
-                chalk_ir::AliasTy::Opaque(opaque) => ty::Alias(
-                    ty::Opaque,
-                    interner.tcx.mk_alias_ty(
-                        opaque.opaque_ty_id.0,
-                        opaque.substitution.lower_into(interner),
-                    ),
-                ),
-            },
-            TyKind::Function(_quantified_ty) => unimplemented!(),
-            TyKind::BoundVar(bound) => ty::Bound(
-                ty::DebruijnIndex::from_usize(bound.debruijn.depth() as usize),
-                ty::BoundTy {
-                    var: ty::BoundVar::from_usize(bound.index),
-                    kind: ty::BoundTyKind::Anon,
-                },
-            ),
-            TyKind::Placeholder(placeholder) => ty::Placeholder(ty::Placeholder {
-                universe: ty::UniverseIndex::from_usize(placeholder.ui.counter),
-                bound: ty::BoundTy {
-                    var: ty::BoundVar::from_usize(placeholder.idx),
-                    kind: ty::BoundTyKind::Anon,
-                },
-            }),
-            TyKind::InferenceVar(_, _) => unimplemented!(),
-            TyKind::Dyn(_) => unimplemented!(),
-        };
-        interner.tcx.mk_ty_from_kind(kind)
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, chalk_ir::Lifetime<RustInterner<'tcx>>> for Region<'tcx> {
-    fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::Lifetime<RustInterner<'tcx>> {
-        match *self {
-            ty::ReEarlyBound(_) => {
-                panic!("Should have already been substituted.");
-            }
-            ty::ReError(_) => {
-                panic!("Error lifetime should not have already been lowered.");
-            }
-            ty::ReLateBound(db, br) => chalk_ir::LifetimeData::BoundVar(chalk_ir::BoundVar::new(
-                chalk_ir::DebruijnIndex::new(db.as_u32()),
-                br.var.as_usize(),
-            ))
-            .intern(interner),
-            ty::ReFree(_) => unimplemented!(),
-            ty::ReStatic => chalk_ir::LifetimeData::Static.intern(interner),
-            ty::ReVar(_) => unimplemented!(),
-            ty::RePlaceholder(placeholder_region) => {
-                chalk_ir::LifetimeData::Placeholder(chalk_ir::PlaceholderIndex {
-                    ui: chalk_ir::UniverseIndex { counter: placeholder_region.universe.index() },
-                    idx: 0, // FIXME: This `idx: 0` is sus.
-                })
-                .intern(interner)
-            }
-            ty::ReErased => chalk_ir::LifetimeData::Erased.intern(interner),
-        }
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, Region<'tcx>> for &chalk_ir::Lifetime<RustInterner<'tcx>> {
-    fn lower_into(self, interner: RustInterner<'tcx>) -> Region<'tcx> {
-        let tcx = interner.tcx;
-        match self.data(interner) {
-            chalk_ir::LifetimeData::BoundVar(var) => ty::Region::new_late_bound(
-                tcx,
-                ty::DebruijnIndex::from_u32(var.debruijn.depth()),
-                ty::BoundRegion {
-                    var: ty::BoundVar::from_usize(var.index),
-                    kind: ty::BrAnon(None),
-                },
-            ),
-            chalk_ir::LifetimeData::InferenceVar(_var) => unimplemented!(),
-            chalk_ir::LifetimeData::Placeholder(p) => ty::Region::new_placeholder(
-                tcx,
-                ty::Placeholder {
-                    universe: ty::UniverseIndex::from_usize(p.ui.counter),
-                    bound: ty::BoundRegion {
-                        var: ty::BoundVar::from_usize(p.idx),
-                        kind: ty::BoundRegionKind::BrAnon(None),
-                    },
-                },
-            ),
-            chalk_ir::LifetimeData::Static => tcx.lifetimes.re_static,
-            chalk_ir::LifetimeData::Erased => tcx.lifetimes.re_erased,
-            chalk_ir::LifetimeData::Phantom(void, _) => match *void {},
-        }
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, chalk_ir::Const<RustInterner<'tcx>>> for ty::Const<'tcx> {
-    fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::Const<RustInterner<'tcx>> {
-        let ty = self.ty().lower_into(interner);
-        let value = match self.kind() {
-            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. {:?}", self),
-        };
-        chalk_ir::ConstData { ty, value }.intern(interner)
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, ty::Const<'tcx>> for &chalk_ir::Const<RustInterner<'tcx>> {
-    fn lower_into(self, interner: RustInterner<'tcx>) -> ty::Const<'tcx> {
-        let data = self.data(interner);
-        let ty = data.ty.lower_into(interner);
-        let kind = match data.value {
-            chalk_ir::ConstValue::BoundVar(var) => ty::ConstKind::Bound(
-                ty::DebruijnIndex::from_u32(var.debruijn.depth()),
-                ty::BoundVar::from_u32(var.index as u32),
-            ),
-            chalk_ir::ConstValue::InferenceVar(_var) => unimplemented!(),
-            chalk_ir::ConstValue::Placeholder(_p) => unimplemented!(),
-            chalk_ir::ConstValue::Concrete(c) => ty::ConstKind::Value(c.interned),
-        };
-        interner.tcx.mk_const(kind, ty)
-    }
-}
-
-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(c) => {
-                chalk_ir::GenericArgData::Const(c.lower_into(interner))
-            }
-        }
-        .intern(interner)
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, ty::subst::GenericArg<'tcx>>
-    for &chalk_ir::GenericArg<RustInterner<'tcx>>
-{
-    fn lower_into(self, interner: RustInterner<'tcx>) -> ty::subst::GenericArg<'tcx> {
-        match self.data(interner) {
-            chalk_ir::GenericArgData::Ty(ty) => {
-                let t: Ty<'tcx> = ty.lower_into(interner);
-                t.into()
-            }
-            chalk_ir::GenericArgData::Lifetime(lifetime) => {
-                let r: Region<'tcx> = lifetime.lower_into(interner);
-                r.into()
-            }
-            chalk_ir::GenericArgData::Const(c) => {
-                let c: ty::Const<'tcx> = c.lower_into(interner);
-                c.into()
-            }
-        }
-    }
-}
-
-// 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>>> {
-        let (predicate, binders, _named_regions) =
-            collect_bound_vars(interner, interner.tcx, self.kind());
-        let value = match predicate {
-            ty::PredicateKind::Clause(ty::ClauseKind::Trait(predicate)) => {
-                Some(chalk_ir::WhereClause::Implemented(predicate.trait_ref.lower_into(interner)))
-            }
-            ty::PredicateKind::Clause(ty::ClauseKind::RegionOutlives(predicate)) => {
-                Some(chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives {
-                    a: predicate.0.lower_into(interner),
-                    b: predicate.1.lower_into(interner),
-                }))
-            }
-            ty::PredicateKind::Clause(ty::ClauseKind::TypeOutlives(predicate)) => {
-                Some(chalk_ir::WhereClause::TypeOutlives(chalk_ir::TypeOutlives {
-                    ty: predicate.0.lower_into(interner),
-                    lifetime: predicate.1.lower_into(interner),
-                }))
-            }
-            ty::PredicateKind::Clause(ty::ClauseKind::Projection(predicate)) => {
-                Some(chalk_ir::WhereClause::AliasEq(predicate.lower_into(interner)))
-            }
-            ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(_ty)) => None,
-            ty::PredicateKind::Clause(ty::ClauseKind::ConstArgHasType(..)) => None,
-
-            ty::PredicateKind::ObjectSafe(..)
-            | ty::PredicateKind::AliasRelate(..)
-            | ty::PredicateKind::ClosureKind(..)
-            | ty::PredicateKind::Subtype(..)
-            | ty::PredicateKind::Coerce(..)
-            | ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(..))
-            | ty::PredicateKind::ConstEquate(..)
-            | ty::PredicateKind::Ambiguous
-            | ty::PredicateKind::Clause(ty::ClauseKind::TypeWellFormedFromEnv(..)) => {
-                bug!("unexpected predicate {self}")
-            }
-        };
-        value.map(|value| chalk_ir::Binders::new(binders, value))
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>>>
-    for &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>
-{
-    fn lower_into(
-        self,
-        interner: RustInterner<'tcx>,
-    ) -> chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>> {
-        // `Self` has one binder:
-        // Binder<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>>
-        // The return type has two:
-        // Binders<&[Binders<WhereClause<I>>]>
-        // This means that any variables that are escaping `self` need to be
-        // shifted in by one so that they are still escaping.
-        let predicates = ty::fold::shift_vars(interner.tcx, self, 1);
-
-        let self_ty = interner.tcx.mk_bound(
-            // This is going to be wrapped in a binder
-            ty::DebruijnIndex::from_usize(1),
-            ty::BoundTy { var: ty::BoundVar::from_usize(0), kind: ty::BoundTyKind::Anon },
-        );
-        let where_clauses = predicates.into_iter().map(|predicate| {
-            let (predicate, binders, _named_regions) =
-                collect_bound_vars(interner, interner.tcx, predicate);
-            match predicate {
-                ty::ExistentialPredicate::Trait(ty::ExistentialTraitRef { def_id, substs }) => {
-                    chalk_ir::Binders::new(
-                        binders.clone(),
-                        chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef {
-                            trait_id: chalk_ir::TraitId(def_id),
-                            substitution: interner
-                                .tcx
-                                .mk_substs_trait(self_ty, substs)
-                                .lower_into(interner),
-                        }),
-                    )
-                }
-                ty::ExistentialPredicate::Projection(predicate) => chalk_ir::Binders::new(
-                    binders.clone(),
-                    chalk_ir::WhereClause::AliasEq(chalk_ir::AliasEq {
-                        alias: chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy {
-                            associated_ty_id: chalk_ir::AssocTypeId(predicate.def_id),
-                            substitution: interner
-                                .tcx
-                                .mk_substs_trait(self_ty, predicate.substs)
-                                .lower_into(interner),
-                        }),
-                        // FIXME(associated_const_equality): teach chalk about terms for alias eq.
-                        ty: predicate.term.ty().unwrap().lower_into(interner),
-                    }),
-                ),
-                ty::ExistentialPredicate::AutoTrait(def_id) => chalk_ir::Binders::new(
-                    binders.clone(),
-                    chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef {
-                        trait_id: chalk_ir::TraitId(def_id),
-                        substitution: interner
-                            .tcx
-                            .mk_substs_trait(self_ty, [])
-                            .lower_into(interner),
-                    }),
-                ),
-            }
-        });
-
-        // Binder for the bound variable representing the concrete underlying type.
-        let existential_binder = chalk_ir::VariableKinds::from1(
-            interner,
-            chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General),
-        );
-        let value = chalk_ir::QuantifiedWhereClauses::from_iter(interner, where_clauses);
-        chalk_ir::Binders::new(existential_binder, value)
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, chalk_ir::FnSig<RustInterner<'tcx>>>
-    for ty::Binder<'tcx, ty::FnSig<'tcx>>
-{
-    fn lower_into(self, _interner: RustInterner<'_>) -> FnSig<RustInterner<'tcx>> {
-        chalk_ir::FnSig {
-            abi: self.abi(),
-            safety: match self.unsafety() {
-                Unsafety::Normal => chalk_ir::Safety::Safe,
-                Unsafety::Unsafe => chalk_ir::Safety::Unsafe,
-            },
-            variadic: self.c_variadic(),
-        }
-    }
-}
-
-// We lower into an Option here since there are some predicates which Chalk
-// doesn't have a representation for yet (as an `InlineBound`). The `Option` will
-// eventually be removed.
-impl<'tcx> LowerInto<'tcx, Option<chalk_solve::rust_ir::QuantifiedInlineBound<RustInterner<'tcx>>>>
-    for ty::Predicate<'tcx>
-{
-    fn lower_into(
-        self,
-        interner: RustInterner<'tcx>,
-    ) -> Option<chalk_solve::rust_ir::QuantifiedInlineBound<RustInterner<'tcx>>> {
-        let (predicate, binders, _named_regions) =
-            collect_bound_vars(interner, interner.tcx, self.kind());
-        match predicate {
-            ty::PredicateKind::Clause(ty::ClauseKind::Trait(predicate)) => {
-                Some(chalk_ir::Binders::new(
-                    binders,
-                    chalk_solve::rust_ir::InlineBound::TraitBound(
-                        predicate.trait_ref.lower_into(interner),
-                    ),
-                ))
-            }
-            ty::PredicateKind::Clause(ty::ClauseKind::Projection(predicate)) => {
-                Some(chalk_ir::Binders::new(
-                    binders,
-                    chalk_solve::rust_ir::InlineBound::AliasEqBound(predicate.lower_into(interner)),
-                ))
-            }
-            ty::PredicateKind::Clause(ty::ClauseKind::TypeOutlives(_predicate)) => None,
-            ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(_ty)) => None,
-            ty::PredicateKind::Clause(ty::ClauseKind::ConstArgHasType(..)) => None,
-
-            ty::PredicateKind::Clause(ty::ClauseKind::RegionOutlives(..))
-            | ty::PredicateKind::AliasRelate(..)
-            | ty::PredicateKind::ObjectSafe(..)
-            | ty::PredicateKind::ClosureKind(..)
-            | ty::PredicateKind::Subtype(..)
-            | ty::PredicateKind::Coerce(..)
-            | ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(..))
-            | ty::PredicateKind::ConstEquate(..)
-            | ty::PredicateKind::Ambiguous
-            | ty::PredicateKind::Clause(ty::ClauseKind::TypeWellFormedFromEnv(..)) => {
-                bug!("unexpected predicate {}", &self)
-            }
-        }
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, chalk_solve::rust_ir::TraitBound<RustInterner<'tcx>>>
-    for ty::TraitRef<'tcx>
-{
-    fn lower_into(
-        self,
-        interner: RustInterner<'tcx>,
-    ) -> chalk_solve::rust_ir::TraitBound<RustInterner<'tcx>> {
-        chalk_solve::rust_ir::TraitBound {
-            trait_id: chalk_ir::TraitId(self.def_id),
-            args_no_self: self.substs[1..].iter().map(|arg| arg.lower_into(interner)).collect(),
-        }
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, chalk_ir::Mutability> for ast::Mutability {
-    fn lower_into(self, _interner: RustInterner<'tcx>) -> chalk_ir::Mutability {
-        match self {
-            rustc_ast::Mutability::Mut => chalk_ir::Mutability::Mut,
-            rustc_ast::Mutability::Not => chalk_ir::Mutability::Not,
-        }
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, ast::Mutability> for chalk_ir::Mutability {
-    fn lower_into(self, _interner: RustInterner<'tcx>) -> ast::Mutability {
-        match self {
-            chalk_ir::Mutability::Mut => ast::Mutability::Mut,
-            chalk_ir::Mutability::Not => ast::Mutability::Not,
-        }
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, chalk_solve::rust_ir::Polarity> for ty::ImplPolarity {
-    fn lower_into(self, _interner: RustInterner<'tcx>) -> chalk_solve::rust_ir::Polarity {
-        match self {
-            ty::ImplPolarity::Positive => chalk_solve::rust_ir::Polarity::Positive,
-            ty::ImplPolarity::Negative => chalk_solve::rust_ir::Polarity::Negative,
-            // FIXME(chalk) reservation impls
-            ty::ImplPolarity::Reservation => chalk_solve::rust_ir::Polarity::Negative,
-        }
-    }
-}
-impl<'tcx> LowerInto<'tcx, chalk_ir::Variance> for ty::Variance {
-    fn lower_into(self, _interner: RustInterner<'tcx>) -> chalk_ir::Variance {
-        match self {
-            ty::Variance::Covariant => chalk_ir::Variance::Covariant,
-            ty::Variance::Invariant => chalk_ir::Variance::Invariant,
-            ty::Variance::Contravariant => chalk_ir::Variance::Contravariant,
-            ty::Variance::Bivariant => unimplemented!(),
-        }
-    }
-}
-
-impl<'tcx> LowerInto<'tcx, chalk_solve::rust_ir::AliasEqBound<RustInterner<'tcx>>>
-    for ty::ProjectionPredicate<'tcx>
-{
-    fn lower_into(
-        self,
-        interner: RustInterner<'tcx>,
-    ) -> chalk_solve::rust_ir::AliasEqBound<RustInterner<'tcx>> {
-        let (trait_ref, own_substs) = self.projection_ty.trait_ref_and_own_substs(interner.tcx);
-        chalk_solve::rust_ir::AliasEqBound {
-            trait_bound: trait_ref.lower_into(interner),
-            associated_ty_id: chalk_ir::AssocTypeId(self.projection_ty.def_id),
-            parameters: own_substs.iter().map(|arg| arg.lower_into(interner)).collect(),
-            value: self.term.ty().unwrap().lower_into(interner),
-        }
-    }
-}
-
-/// To collect bound vars, we have to do two passes. In the first pass, we
-/// collect all `BoundRegionKind`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.
-pub(crate) fn collect_bound_vars<'tcx, T: TypeFoldable<TyCtxt<'tcx>>>(
-    interner: RustInterner<'tcx>,
-    tcx: TyCtxt<'tcx>,
-    ty: Binder<'tcx, 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.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))
-            .or_else(|| bug!("Skipped bound var index: parameters={:?}", parameters));
-    });
-
-    let binders = chalk_ir::VariableKinds::from_iter(interner, parameters.into_values());
-
-    (new_ty, binders, named_parameters)
-}
-
-pub(crate) struct BoundVarsCollector<'tcx> {
-    binder_index: ty::DebruijnIndex,
-    pub(crate) parameters: BTreeMap<u32, chalk_ir::VariableKind<RustInterner<'tcx>>>,
-    pub(crate) named_parameters: Vec<DefId>,
-}
-
-impl<'tcx> BoundVarsCollector<'tcx> {
-    pub(crate) fn new() -> Self {
-        BoundVarsCollector {
-            binder_index: ty::INNERMOST,
-            parameters: BTreeMap::new(),
-            named_parameters: vec![],
-        }
-    }
-}
-
-impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for BoundVarsCollector<'tcx> {
-    fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(
-        &mut self,
-        t: &Binder<'tcx, T>,
-    ) -> ControlFlow<Self::BreakTy> {
-        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>) -> ControlFlow<Self::BreakTy> {
-        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::TyVariableKind::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>) -> ControlFlow<Self::BreakTy> {
-        match *r {
-            ty::ReLateBound(index, br) if index == self.binder_index => match br.kind {
-                ty::BoundRegionKind::BrNamed(def_id, _name) => {
-                    if !self.named_parameters.iter().any(|d| *d == def_id) {
-                        self.named_parameters.push(def_id);
-                    }
-                }
-
-                ty::BoundRegionKind::BrAnon(_) => match self.parameters.entry(br.var.as_u32()) {
-                    Entry::Vacant(entry) => {
-                        entry.insert(chalk_ir::VariableKind::Lifetime);
-                    }
-                    Entry::Occupied(entry) => match entry.get() {
-                        chalk_ir::VariableKind::Lifetime => {}
-                        _ => panic!(),
-                    },
-                },
-
-                ty::BoundRegionKind::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!();
-            }
-
-            _ => (),
-        };
-
-        ControlFlow::Continue(())
-    }
-}
-
-/// This is used to replace `BoundRegionKind::BrNamed` with `BoundRegionKind::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<TyCtxt<'tcx>> for NamedBoundVarSubstitutor<'a, 'tcx> {
-    fn interner(&self) -> TyCtxt<'tcx> {
-        self.tcx
-    }
-
-    fn fold_binder<T: TypeFoldable<TyCtxt<'tcx>>>(
-        &mut self,
-        t: Binder<'tcx, T>,
-    ) -> Binder<'tcx, T> {
-        self.binder_index.shift_in(1);
-        let result = t.super_fold_with(self);
-        self.binder_index.shift_out(1);
-        result
-    }
-
-    fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> {
-        match *r {
-            ty::ReLateBound(index, br) if index == self.binder_index => match br.kind {
-                ty::BrNamed(def_id, _name) => match self.named_parameters.get(&def_id) {
-                    Some(_) => {
-                        let new_br = ty::BoundRegion { var: br.var, kind: ty::BrAnon(None) };
-                        return ty::Region::new_late_bound(self.tcx, index, new_br);
-                    }
-                    None => panic!("Missing `BrNamed`."),
-                },
-                ty::BrEnv => unimplemented!(),
-                ty::BrAnon(..) => {}
-            },
-            _ => (),
-        };
-
-        r
-    }
-}
-
-/// Used to substitute `Param`s with placeholders. We do this since Chalk
-/// have a notion of `Param`s.
-pub(crate) struct ParamsSubstitutor<'tcx> {
-    tcx: TyCtxt<'tcx>,
-    binder_index: ty::DebruijnIndex,
-    list: Vec<rustc_middle::ty::ParamTy>,
-    next_ty_placeholder: usize,
-    pub(crate) params: rustc_data_structures::fx::FxHashMap<u32, rustc_middle::ty::ParamTy>,
-    pub(crate) named_regions: BTreeMap<DefId, u32>,
-}
-
-impl<'tcx> ParamsSubstitutor<'tcx> {
-    pub(crate) fn new(tcx: TyCtxt<'tcx>, next_ty_placeholder: usize) -> Self {
-        ParamsSubstitutor {
-            tcx,
-            binder_index: ty::INNERMOST,
-            list: vec![],
-            next_ty_placeholder,
-            params: rustc_data_structures::fx::FxHashMap::default(),
-            named_regions: BTreeMap::default(),
-        }
-    }
-}
-
-impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ParamsSubstitutor<'tcx> {
-    fn interner(&self) -> TyCtxt<'tcx> {
-        self.tcx
-    }
-
-    fn fold_binder<T: TypeFoldable<TyCtxt<'tcx>>>(
-        &mut self,
-        t: Binder<'tcx, T>,
-    ) -> Binder<'tcx, 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() {
-            ty::Param(param) => match self.list.iter().position(|r| r == &param) {
-                Some(idx) => self.tcx.mk_placeholder(ty::PlaceholderType {
-                    universe: ty::UniverseIndex::from_usize(0),
-                    bound: ty::BoundTy {
-                        var: ty::BoundVar::from_usize(idx),
-                        kind: ty::BoundTyKind::Anon,
-                    },
-                }),
-                None => {
-                    self.list.push(param);
-                    let idx = self.list.len() - 1 + self.next_ty_placeholder;
-                    self.params.insert(idx as u32, param);
-                    self.tcx.mk_placeholder(ty::PlaceholderType {
-                        universe: ty::UniverseIndex::from_usize(0),
-                        bound: ty::BoundTy {
-                            var: ty::BoundVar::from_usize(idx),
-                            kind: ty::BoundTyKind::Anon,
-                        },
-                    })
-                }
-            },
-            _ => 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,
-            // since canonicalization will already change these to canonical
-            // variables (ty::ReLateBound).
-            ty::ReEarlyBound(_re) => match self.named_regions.get(&_re.def_id) {
-                Some(idx) => {
-                    let br = ty::BoundRegion {
-                        var: ty::BoundVar::from_u32(*idx),
-                        kind: ty::BrAnon(None),
-                    };
-                    ty::Region::new_late_bound(self.tcx, self.binder_index, br)
-                }
-                None => {
-                    let idx = self.named_regions.len() as u32;
-                    let br = ty::BoundRegion {
-                        var: ty::BoundVar::from_u32(idx),
-                        kind: ty::BrAnon(None),
-                    };
-                    self.named_regions.insert(_re.def_id, idx);
-                    ty::Region::new_late_bound(self.tcx, self.binder_index, br)
-                }
-            },
-
-            _ => r,
-        }
-    }
-}
-
-pub(crate) struct ReverseParamsSubstitutor<'tcx> {
-    tcx: TyCtxt<'tcx>,
-    params: rustc_data_structures::fx::FxHashMap<u32, rustc_middle::ty::ParamTy>,
-}
-
-impl<'tcx> ReverseParamsSubstitutor<'tcx> {
-    pub(crate) fn new(
-        tcx: TyCtxt<'tcx>,
-        params: rustc_data_structures::fx::FxHashMap<u32, rustc_middle::ty::ParamTy>,
-    ) -> Self {
-        Self { tcx, params }
-    }
-}
-
-impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ReverseParamsSubstitutor<'tcx> {
-    fn interner(&self) -> TyCtxt<'tcx> {
-        self.tcx
-    }
-
-    fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
-        match *t.kind() {
-            ty::Placeholder(ty::PlaceholderType { universe: ty::UniverseIndex::ROOT, bound }) => {
-                match self.params.get(&bound.var.as_u32()) {
-                    Some(&ty::ParamTy { index, name }) => self.tcx.mk_ty_param(index, name),
-                    None => t,
-                }
-            }
-
-            _ => t.super_fold_with(self),
-        }
-    }
-}
-
-/// Used to collect `Placeholder`s.
-pub(crate) struct PlaceholdersCollector {
-    universe_index: ty::UniverseIndex,
-    pub(crate) next_ty_placeholder: usize,
-    pub(crate) next_anon_region_placeholder: u32,
-}
-
-impl PlaceholdersCollector {
-    pub(crate) fn new() -> Self {
-        PlaceholdersCollector {
-            universe_index: ty::UniverseIndex::ROOT,
-            next_ty_placeholder: 0,
-            next_anon_region_placeholder: 0,
-        }
-    }
-}
-
-impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for PlaceholdersCollector {
-    fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
-        match t.kind() {
-            ty::Placeholder(p) if p.universe == self.universe_index => {
-                self.next_ty_placeholder = self.next_ty_placeholder.max(p.bound.var.as_usize() + 1);
-            }
-
-            _ => (),
-        };
-
-        t.super_visit_with(self)
-    }
-
-    fn visit_region(&mut self, r: Region<'tcx>) -> ControlFlow<Self::BreakTy> {
-        match *r {
-            ty::RePlaceholder(p) if p.universe == self.universe_index => {
-                if let ty::BoundRegionKind::BrAnon(_) = p.bound.kind {
-                    self.next_anon_region_placeholder =
-                        self.next_anon_region_placeholder.max(p.bound.var.as_u32());
-                }
-                // FIXME: This doesn't seem to handle BrNamed at all?
-            }
-
-            _ => (),
-        };
-
-        ControlFlow::Continue(())
-    }
-}
diff --git a/compiler/rustc_traits/src/chalk/mod.rs b/compiler/rustc_traits/src/chalk/mod.rs
deleted file mode 100644
index 8834449c9a4..00000000000
--- a/compiler/rustc_traits/src/chalk/mod.rs
+++ /dev/null
@@ -1,169 +0,0 @@
-//! Calls `chalk-solve` to solve a `ty::Predicate`
-//!
-//! In order to call `chalk-solve`, this file must convert a `CanonicalChalkEnvironmentAndGoal` into
-//! a Chalk uncanonical goal. It then calls Chalk, and converts the answer back into rustc solution.
-
-pub(crate) mod db;
-pub(crate) mod lowering;
-
-use rustc_middle::infer::canonical::{CanonicalTyVarKind, CanonicalVarKind};
-use rustc_middle::query::Providers;
-use rustc_middle::traits::ChalkRustInterner;
-use rustc_middle::ty::{self, TyCtxt, TypeFoldable, TypeVisitable};
-
-use rustc_infer::infer::canonical::{
-    Canonical, CanonicalVarValues, Certainty, QueryRegionConstraints, QueryResponse,
-};
-use rustc_infer::traits::{self, CanonicalChalkEnvironmentAndGoal};
-
-use crate::chalk::db::RustIrDatabase as ChalkRustIrDatabase;
-use crate::chalk::lowering::LowerInto;
-use crate::chalk::lowering::{ParamsSubstitutor, PlaceholdersCollector, ReverseParamsSubstitutor};
-
-use chalk_solve::Solution;
-
-pub(crate) fn provide(p: &mut Providers) {
-    *p = Providers { evaluate_goal, ..*p };
-}
-
-pub(crate) fn evaluate_goal<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    obligation: CanonicalChalkEnvironmentAndGoal<'tcx>,
-) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, ()>>, traits::query::NoSolution> {
-    let interner = ChalkRustInterner { tcx };
-
-    // Chalk doesn't have a notion of `Params`, so instead we use placeholders.
-    let mut placeholders_collector = PlaceholdersCollector::new();
-    obligation.visit_with(&mut placeholders_collector);
-
-    let mut params_substitutor =
-        ParamsSubstitutor::new(tcx, placeholders_collector.next_ty_placeholder);
-    let obligation = obligation.fold_with(&mut params_substitutor);
-    let params = params_substitutor.params;
-
-    let max_universe = obligation.max_universe.index();
-
-    let lowered_goal: chalk_ir::UCanonical<
-        chalk_ir::InEnvironment<chalk_ir::Goal<ChalkRustInterner<'tcx>>>,
-    > = chalk_ir::UCanonical {
-        canonical: chalk_ir::Canonical {
-            binders: chalk_ir::CanonicalVarKinds::from_iter(
-                interner,
-                obligation.variables.iter().map(|v| match v.kind {
-                    CanonicalVarKind::PlaceholderTy(_ty) => unimplemented!(),
-                    CanonicalVarKind::PlaceholderRegion(_ui) => unimplemented!(),
-                    CanonicalVarKind::Ty(ty) => match ty {
-                        CanonicalTyVarKind::General(ui) => chalk_ir::WithKind::new(
-                            chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General),
-                            chalk_ir::UniverseIndex { counter: ui.index() },
-                        ),
-                        CanonicalTyVarKind::Int => chalk_ir::WithKind::new(
-                            chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::Integer),
-                            chalk_ir::UniverseIndex::root(),
-                        ),
-                        CanonicalTyVarKind::Float => chalk_ir::WithKind::new(
-                            chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::Float),
-                            chalk_ir::UniverseIndex::root(),
-                        ),
-                    },
-                    CanonicalVarKind::Region(ui) => chalk_ir::WithKind::new(
-                        chalk_ir::VariableKind::Lifetime,
-                        chalk_ir::UniverseIndex { counter: ui.index() },
-                    ),
-                    CanonicalVarKind::Const(_ui, _ty) => unimplemented!(),
-                    CanonicalVarKind::PlaceholderConst(_pc, _ty) => unimplemented!(),
-                }),
-            ),
-            value: obligation.value.lower_into(interner),
-        },
-        universes: max_universe + 1,
-    };
-
-    use chalk_solve::Solver;
-    let mut solver = chalk_engine::solve::SLGSolver::new(32, None);
-    let db = ChalkRustIrDatabase { interner };
-    debug!(?lowered_goal);
-    let solution = solver.solve(&db, &lowered_goal);
-    debug!(?obligation, ?solution, "evaluate goal");
-
-    // Ideally, the code to convert *back* to rustc types would live close to
-    // the code to convert *from* rustc types. Right now though, we don't
-    // really need this and so it's really minimal.
-    // Right now, we also treat a `Unique` solution the same as
-    // `Ambig(Definite)`. This really isn't right.
-    let make_solution = |subst: chalk_ir::Substitution<_>,
-                         binders: chalk_ir::CanonicalVarKinds<_>| {
-        use rustc_middle::infer::canonical::CanonicalVarInfo;
-
-        let mut reverse_param_substitutor = ReverseParamsSubstitutor::new(tcx, params);
-        let var_values = tcx.mk_substs_from_iter(
-            subst
-                .as_slice(interner)
-                .iter()
-                .map(|p| p.lower_into(interner).fold_with(&mut reverse_param_substitutor)),
-        );
-        let variables = binders.iter(interner).map(|var| {
-            let kind = match var.kind {
-                chalk_ir::VariableKind::Ty(ty_kind) => CanonicalVarKind::Ty(match ty_kind {
-                    chalk_ir::TyVariableKind::General => CanonicalTyVarKind::General(
-                        ty::UniverseIndex::from_usize(var.skip_kind().counter),
-                    ),
-                    chalk_ir::TyVariableKind::Integer => CanonicalTyVarKind::Int,
-                    chalk_ir::TyVariableKind::Float => CanonicalTyVarKind::Float,
-                }),
-                chalk_ir::VariableKind::Lifetime => {
-                    CanonicalVarKind::Region(ty::UniverseIndex::from_usize(var.skip_kind().counter))
-                }
-                // FIXME(compiler-errors): We don't currently have a way of turning
-                // a Chalk ty back into a rustc ty, right?
-                chalk_ir::VariableKind::Const(_) => todo!(),
-            };
-            CanonicalVarInfo { kind }
-        });
-        let max_universe = binders.iter(interner).map(|v| v.skip_kind().counter).max().unwrap_or(0);
-        let sol = Canonical {
-            max_universe: ty::UniverseIndex::from_usize(max_universe),
-            variables: tcx.mk_canonical_var_infos_from_iter(variables),
-            value: QueryResponse {
-                var_values: CanonicalVarValues { var_values },
-                region_constraints: QueryRegionConstraints::default(),
-                certainty: Certainty::Proven,
-                opaque_types: vec![],
-                value: (),
-            },
-        };
-        tcx.arena.alloc(sol)
-    };
-    solution
-        .map(|s| match s {
-            Solution::Unique(subst) => {
-                // FIXME(chalk): handle constraints
-                make_solution(subst.value.subst, subst.binders)
-            }
-            Solution::Ambig(guidance) => {
-                match guidance {
-                    chalk_solve::Guidance::Definite(subst) => {
-                        make_solution(subst.value, subst.binders)
-                    }
-                    chalk_solve::Guidance::Suggested(_) => unimplemented!(),
-                    chalk_solve::Guidance::Unknown => {
-                        // chalk_fulfill doesn't use the var_values here, so
-                        // let's just ignore that
-                        let sol = Canonical {
-                            max_universe: ty::UniverseIndex::from_usize(0),
-                            variables: obligation.variables,
-                            value: QueryResponse {
-                                var_values: CanonicalVarValues::dummy(),
-                                region_constraints: QueryRegionConstraints::default(),
-                                certainty: Certainty::Ambiguous,
-                                opaque_types: vec![],
-                                value: (),
-                            },
-                        };
-                        &*tcx.arena.alloc(sol)
-                    }
-                }
-            }
-        })
-        .ok_or(traits::query::NoSolution)
-}
diff --git a/compiler/rustc_traits/src/lib.rs b/compiler/rustc_traits/src/lib.rs
index 590d0bd0e42..dfa5814219b 100644
--- a/compiler/rustc_traits/src/lib.rs
+++ b/compiler/rustc_traits/src/lib.rs
@@ -1,5 +1,4 @@
-//! New recursive solver modeled on Chalk's recursive solver. Most of
-//! the guts are broken up into modules; see the comments in those modules.
+//! Queries that are independent from the main solver code.
 
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
@@ -11,7 +10,6 @@ extern crate tracing;
 #[macro_use]
 extern crate rustc_middle;
 
-mod chalk;
 mod codegen;
 mod dropck_outlives;
 mod evaluate_obligation;
@@ -29,7 +27,6 @@ pub fn provide(p: &mut Providers) {
     dropck_outlives::provide(p);
     evaluate_obligation::provide(p);
     implied_outlives_bounds::provide(p);
-    chalk::provide(p);
     normalize_projection_ty::provide(p);
     normalize_erasing_regions::provide(p);
     type_op::provide(p);