mv compiler to compiler/

10 files changed, 2602 insertions, 0 deletions

diff --git a/compiler/rustc_traits/src/chalk/db.rs b/compiler/rustc_traits/src/chalk/db.rs
new file mode 100644
index 00000000000..4c8be8eb610
--- /dev/null
+++ b/compiler/rustc_traits/src/chalk/db.rs
@@ -0,0 +1,588 @@
+//! 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::subst::{InternalSubsts, Subst, SubstsRef};
+use rustc_middle::ty::{self, AssocItemContainer, AssocKind, TyCtxt};
+
+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 tcx: TyCtxt<'tcx>,
+    pub interner: RustInterner<'tcx>,
+}
+
+impl fmt::Debug for RustIrDatabase<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "RustIrDatabase")
+    }
+}
+
+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.tcx.associated_item(def_id);
+        let trait_def_id = match assoc_item.container {
+            AssocItemContainer::TraitContainer(def_id) => def_id,
+            _ => unimplemented!("Not possible??"),
+        };
+        match assoc_item.kind {
+            AssocKind::Type => {}
+            _ => unimplemented!("Not possible??"),
+        }
+        let bound_vars = bound_vars_for_item(self.tcx, def_id);
+        let binders = binders_for(&self.interner, bound_vars);
+        // FIXME(chalk): this really isn't right I don't think. The functions
+        // for GATs are a bit hard to figure out. Are these supposed to be where
+        // clauses or bounds?
+        let predicates = self.tcx.predicates_defined_on(def_id).predicates;
+        let where_clauses: Vec<_> = predicates
+            .iter()
+            .map(|(wc, _)| wc.subst(self.tcx, &bound_vars))
+            .filter_map(|wc| LowerInto::<Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>::lower_into(wc, &self.interner)).collect();
+
+        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: vec![], where_clauses },
+            ),
+        })
+    }
+
+    fn trait_datum(
+        &self,
+        trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
+    ) -> Arc<chalk_solve::rust_ir::TraitDatum<RustInterner<'tcx>>> {
+        let def_id = trait_id.0;
+        let trait_def = self.tcx.trait_def(def_id);
+
+        let bound_vars = bound_vars_for_item(self.tcx, def_id);
+        let binders = binders_for(&self.interner, bound_vars);
+        let predicates = self.tcx.predicates_defined_on(def_id).predicates;
+        let where_clauses: Vec<_> = predicates
+            .iter()
+            .map(|(wc, _)| wc.subst(self.tcx, &bound_vars))
+            .filter_map(|wc| LowerInto::<Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>::lower_into(wc, &self.interner)).collect();
+        let associated_ty_ids: Vec<_> = self
+            .tcx
+            .associated_items(def_id)
+            .in_definition_order()
+            .filter(|i| i.kind == AssocKind::Type)
+            .map(|i| chalk_ir::AssocTypeId(i.def_id))
+            .collect();
+
+        let well_known =
+            if self.tcx.lang_items().sized_trait().map(|t| def_id == t).unwrap_or(false) {
+                Some(chalk_solve::rust_ir::WellKnownTrait::Sized)
+            } else if self.tcx.lang_items().copy_trait().map(|t| def_id == t).unwrap_or(false) {
+                Some(chalk_solve::rust_ir::WellKnownTrait::Copy)
+            } else if self.tcx.lang_items().clone_trait().map(|t| def_id == t).unwrap_or(false) {
+                Some(chalk_solve::rust_ir::WellKnownTrait::Clone)
+            } else if self.tcx.lang_items().drop_trait().map(|t| def_id == t).unwrap_or(false) {
+                Some(chalk_solve::rust_ir::WellKnownTrait::Drop)
+            } else if self.tcx.lang_items().fn_trait().map(|t| def_id == t).unwrap_or(false) {
+                Some(chalk_solve::rust_ir::WellKnownTrait::Fn)
+            } else if self.tcx.lang_items().fn_once_trait().map(|t| def_id == t).unwrap_or(false) {
+                Some(chalk_solve::rust_ir::WellKnownTrait::FnOnce)
+            } else if self.tcx.lang_items().fn_mut_trait().map(|t| def_id == t).unwrap_or(false) {
+                Some(chalk_solve::rust_ir::WellKnownTrait::FnMut)
+            } 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.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.tcx, adt_def.did);
+        let binders = binders_for(&self.interner, bound_vars);
+
+        let predicates = self.tcx.predicates_of(adt_def.did).predicates;
+        let where_clauses: Vec<_> = predicates
+            .iter()
+            .map(|(wc, _)| wc.subst(self.tcx, bound_vars))
+            .filter_map(|wc| LowerInto::<Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>::lower_into(wc, &self.interner))
+            .collect();
+        let fields = match adt_def.adt_kind() {
+            ty::AdtKind::Struct | ty::AdtKind::Union => {
+                let variant = adt_def.non_enum_variant();
+                variant
+                    .fields
+                    .iter()
+                    .map(|field| {
+                        self.tcx
+                            .type_of(field.did)
+                            .subst(self.tcx, bound_vars)
+                            .lower_into(&self.interner)
+                    })
+                    .collect()
+            }
+            // FIXME(chalk): handle enums; force_impl_for requires this
+            ty::AdtKind::Enum => vec![],
+        };
+        let struct_datum = Arc::new(chalk_solve::rust_ir::AdtDatum {
+            id: adt_id,
+            binders: chalk_ir::Binders::new(
+                binders,
+                chalk_solve::rust_ir::AdtDatumBound { fields, 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(),
+            },
+        });
+        struct_datum
+    }
+
+    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.tcx, def_id);
+        let binders = binders_for(&self.interner, bound_vars);
+
+        let predicates = self.tcx.predicates_defined_on(def_id).predicates;
+        let where_clauses: Vec<_> = predicates
+            .iter()
+            .map(|(wc, _)| wc.subst(self.tcx, &bound_vars))
+            .filter_map(|wc| LowerInto::<Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>::lower_into(wc, &self.interner)).collect();
+
+        let sig = self.tcx.fn_sig(def_id);
+        let inputs_and_output = sig.inputs_and_output();
+        let (inputs_and_output, iobinders, _) = crate::chalk::lowering::collect_bound_vars(
+            &self.interner,
+            self.tcx,
+            &inputs_and_output,
+        );
+
+        let argument_types = inputs_and_output[..inputs_and_output.len() - 1]
+            .iter()
+            .map(|t| t.subst(self.tcx, &bound_vars).lower_into(&self.interner))
+            .collect();
+
+        let return_type = inputs_and_output[inputs_and_output.len() - 1]
+            .subst(self.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,
+            abi: sig.abi(),
+            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.tcx, def_id);
+        let binders = binders_for(&self.interner, bound_vars);
+
+        let trait_ref = self.tcx.impl_trait_ref(def_id).expect("not an impl");
+        let trait_ref = trait_ref.subst(self.tcx, bound_vars);
+
+        let predicates = self.tcx.predicates_of(def_id).predicates;
+        let where_clauses: Vec<_> = predicates
+            .iter()
+            .map(|(wc, _)| wc.subst(self.tcx, bound_vars))
+            .filter_map(|wc| LowerInto::<Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>::lower_into(wc, &self.interner)).collect();
+
+        let value = chalk_solve::rust_ir::ImplDatumBound {
+            trait_ref: trait_ref.lower_into(&self.interner),
+            where_clauses,
+        };
+
+        Arc::new(chalk_solve::rust_ir::ImplDatum {
+            polarity: chalk_solve::rust_ir::Polarity::Positive,
+            binders: chalk_ir::Binders::new(binders, value),
+            impl_type: chalk_solve::rust_ir::ImplType::Local,
+            associated_ty_value_ids: vec![],
+        })
+    }
+
+    fn impls_for_trait(
+        &self,
+        trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
+        parameters: &[chalk_ir::GenericArg<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.tcx.all_impls(def_id);
+        let matched_impls = all_impls.filter(|impl_def_id| {
+            use chalk_ir::could_match::CouldMatch;
+            let trait_ref = self.tcx.impl_trait_ref(*impl_def_id).unwrap();
+            let bound_vars = bound_vars_for_item(self.tcx, *impl_def_id);
+
+            let self_ty = trait_ref.self_ty();
+            let self_ty = self_ty.subst(self.tcx, bound_vars);
+            let lowered_ty = self_ty.lower_into(&self.interner);
+
+            parameters[0].assert_ty_ref(&self.interner).could_match(&self.interner, &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>>,
+        adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
+    ) -> bool {
+        let trait_def_id = auto_trait_id.0;
+        let adt_def = adt_id.0;
+        let all_impls = self.tcx.all_impls(trait_def_id);
+        for impl_def_id in all_impls {
+            let trait_ref = self.tcx.impl_trait_ref(impl_def_id).unwrap();
+            let self_ty = trait_ref.self_ty();
+            match self_ty.kind {
+                ty::Adt(impl_adt_def, _) => {
+                    if impl_adt_def == adt_def {
+                        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.tcx.associated_item(def_id);
+        let impl_id = match assoc_item.container {
+            AssocItemContainer::TraitContainer(def_id) => def_id,
+            _ => unimplemented!("Not possible??"),
+        };
+        match assoc_item.kind {
+            AssocKind::Type => {}
+            _ => unimplemented!("Not possible??"),
+        }
+        let bound_vars = bound_vars_for_item(self.tcx, def_id);
+        let binders = binders_for(&self.interner, bound_vars);
+        let ty = self.tcx.type_of(def_id);
+
+        Arc::new(chalk_solve::rust_ir::AssociatedTyValue {
+            impl_id: chalk_ir::ImplId(impl_id),
+            associated_ty_id: chalk_ir::AssocTypeId(def_id),
+            value: chalk_ir::Binders::new(
+                binders,
+                chalk_solve::rust_ir::AssociatedTyValueBound { ty: ty.lower_into(&self.interner) },
+            ),
+        })
+    }
+
+    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 = bound_vars_for_item(self.tcx, opaque_ty_id.0);
+        let binders = binders_for(&self.interner, bound_vars);
+        let predicates = self.tcx.predicates_defined_on(opaque_ty_id.0).predicates;
+        let where_clauses: Vec<_> = predicates
+            .iter()
+            .map(|(wc, _)| wc.subst(self.tcx, &bound_vars))
+            .filter_map(|wc| LowerInto::<Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>::lower_into(wc, &self.interner)).collect();
+
+        let value = chalk_solve::rust_ir::OpaqueTyDatumBound {
+            bounds: chalk_ir::Binders::new(binders, where_clauses),
+        };
+        Arc::new(chalk_solve::rust_ir::OpaqueTyDatum {
+            opaque_ty_id,
+            bound: chalk_ir::Binders::new(chalk_ir::VariableKinds::new(&self.interner), value),
+        })
+    }
+
+    /// Since Chalk can't handle all Rust types currently, we have to handle
+    /// some specially for now. Over time, these `Some` returns will change to
+    /// `None` and eventually this function will be removed.
+    fn force_impl_for(
+        &self,
+        well_known: chalk_solve::rust_ir::WellKnownTrait,
+        ty: &chalk_ir::TyData<RustInterner<'tcx>>,
+    ) -> Option<bool> {
+        use chalk_ir::TyData::*;
+        match well_known {
+            chalk_solve::rust_ir::WellKnownTrait::Sized => match ty {
+                Apply(apply) => match apply.name {
+                    chalk_ir::TypeName::Adt(chalk_ir::AdtId(adt_def)) => match adt_def.adt_kind() {
+                        ty::AdtKind::Struct | ty::AdtKind::Union => None,
+                        ty::AdtKind::Enum => {
+                            let constraint = self.tcx.adt_sized_constraint(adt_def.did);
+                            if !constraint.0.is_empty() { unimplemented!() } else { Some(true) }
+                        }
+                    },
+                    _ => None,
+                },
+                Dyn(_)
+                | Alias(_)
+                | Placeholder(_)
+                | Function(_)
+                | InferenceVar(_, _)
+                | BoundVar(_) => None,
+            },
+            chalk_solve::rust_ir::WellKnownTrait::Copy
+            | chalk_solve::rust_ir::WellKnownTrait::Clone => match ty {
+                Apply(apply) => match apply.name {
+                    chalk_ir::TypeName::Adt(chalk_ir::AdtId(adt_def)) => match adt_def.adt_kind() {
+                        ty::AdtKind::Struct | ty::AdtKind::Union => None,
+                        ty::AdtKind::Enum => {
+                            let constraint = self.tcx.adt_sized_constraint(adt_def.did);
+                            if !constraint.0.is_empty() { unimplemented!() } else { Some(true) }
+                        }
+                    },
+                    _ => None,
+                },
+                Dyn(_)
+                | Alias(_)
+                | Placeholder(_)
+                | Function(_)
+                | InferenceVar(_, _)
+                | BoundVar(_) => None,
+            },
+            chalk_solve::rust_ir::WellKnownTrait::Drop => None,
+            chalk_solve::rust_ir::WellKnownTrait::Fn => None,
+            chalk_solve::rust_ir::WellKnownTrait::FnMut => None,
+            chalk_solve::rust_ir::WellKnownTrait::FnOnce => None,
+            chalk_solve::rust_ir::WellKnownTrait::Unsize => None,
+        }
+    }
+
+    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 def_id = match well_known_trait {
+            Sized => self.tcx.lang_items().sized_trait(),
+            Copy => self.tcx.lang_items().copy_trait(),
+            Clone => self.tcx.lang_items().clone_trait(),
+            Drop => self.tcx.lang_items().drop_trait(),
+            Fn => self.tcx.lang_items().fn_trait(),
+            FnMut => self.tcx.lang_items().fn_mut_trait(),
+            FnOnce => self.tcx.lang_items().fn_once_trait(),
+            Unsize => self.tcx.lang_items().unsize_trait(),
+        };
+        def_id.map(chalk_ir::TraitId)
+    }
+
+    fn is_object_safe(&self, trait_id: chalk_ir::TraitId<RustInterner<'tcx>>) -> bool {
+        self.tcx.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.tcx.mk_ty(ty::Tuple(self.tcx.intern_substs(&[]))).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.parameters(&self.interner)[substs.len(&self.interner) - 3];
+        match kind.assert_ty_ref(&self.interner).data(&self.interner) {
+            chalk_ir::TyData::Apply(apply) => match apply.name {
+                chalk_ir::TypeName::Scalar(scalar) => match 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"),
+                },
+                _ => 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.parameters(&self.interner)[substs.len(&self.interner) - 2];
+        match sig.assert_ty_ref(&self.interner).data(&self.interner) {
+            chalk_ir::TyData::Function(f) => {
+                let substitution = f.substitution.parameters(&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.data(&self.interner) {
+                    chalk_ir::TyData::Apply(apply) => match apply.name {
+                        chalk_ir::TypeName::Tuple(_) => apply
+                            .substitution
+                            .iter(&self.interner)
+                            .map(|arg| arg.assert_ty_ref(&self.interner))
+                            .cloned()
+                            .collect(),
+                        _ => bug!("Expecting closure FnSig args to be tupled."),
+                    },
+                    _ => bug!("Expecting closure FnSig args to be tupled."),
+                };
+
+                chalk_ir::Binders::new(
+                    chalk_ir::VariableKinds::from(
+                        &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.parameters(&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.parameters(&self.interner)[0..substs.len(&self.interner) - 3];
+        chalk_ir::Substitution::from(&self.interner, substitution)
+    }
+}
+
+/// Creates a `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 `BoundRegion::BrNamed`
+/// variant (which has a `DefId`).
+fn bound_vars_for_item(tcx: TyCtxt<'tcx>, def_id: DefId) -> SubstsRef<'tcx> {
+    InternalSubsts::for_item(tcx, def_id, |param, substs| match param.kind {
+        ty::GenericParamDefKind::Type { .. } => tcx
+            .mk_ty(ty::Bound(
+                ty::INNERMOST,
+                ty::BoundTy {
+                    var: ty::BoundVar::from(param.index),
+                    kind: ty::BoundTyKind::Param(param.name),
+                },
+            ))
+            .into(),
+
+        ty::GenericParamDefKind::Lifetime => tcx
+            .mk_region(ty::RegionKind::ReLateBound(
+                ty::INNERMOST,
+                ty::BoundRegion::BrAnon(substs.len() as u32),
+            ))
+            .into(),
+
+        ty::GenericParamDefKind::Const => tcx
+            .mk_const(ty::Const {
+                val: ty::ConstKind::Bound(ty::INNERMOST, ty::BoundVar::from(param.index)),
+                ty: tcx.type_of(param.def_id),
+            })
+            .into(),
+    })
+}
+
+fn binders_for<'tcx>(
+    interner: &RustInterner<'tcx>,
+    bound_vars: SubstsRef<'tcx>,
+) -> chalk_ir::VariableKinds<RustInterner<'tcx>> {
+    chalk_ir::VariableKinds::from(
+        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::TyKind::General)
+            }
+            ty::subst::GenericArgKind::Const(c) => {
+                chalk_ir::VariableKind::Const(c.ty.lower_into(interner))
+            }
+        }),
+    )
+}
diff --git a/compiler/rustc_traits/src/chalk/lowering.rs b/compiler/rustc_traits/src/chalk/lowering.rs
new file mode 100644
index 00000000000..a043fa3f4c8
--- /dev/null
+++ b/compiler/rustc_traits/src/chalk/lowering.rs
@@ -0,0 +1,886 @@
+//! Contains the logic to lower rustc types into Chalk types
+//!
+//! In many cases there is a 1:1 relationship between a rustc type and a Chalk type.
+//! For example, a `SubstsRef` maps almost directly to a `Substitution`. In some
+//! other cases, such as `Param`s, there is no Chalk type, so we have to handle
+//! accordingly.
+//!
+//! ## `Ty` lowering
+//! Much of the `Ty` lowering is 1:1 with Chalk. (Or will be eventually). A
+//! helpful table for what types lower to what can be found in the
+//! [Chalk book](http://rust-lang.github.io/chalk/book/types/rust_types.html).
+//! The most notable difference lies with `Param`s. To convert from rustc to
+//! Chalk, we eagerly and deeply convert `Param`s to placeholders (in goals) or
+//! bound variables (for clause generation through functions in `db`).
+//!
+//! ## `Region` lowering
+//! Regions are handled in rustc and Chalk is quite differently. In rustc, there
+//! is a difference between "early bound" and "late bound" regions, where only
+//! the late bound regions have a `DebruijnIndex`. Moreover, in Chalk all
+//! regions (Lifetimes) have an associated index. In rustc, only `BrAnon`s have
+//! an index, whereas `BrNamed` don't. In order to lower regions to Chalk, we
+//! convert all regions into `BrAnon` late-bound regions.
+//!
+//! ## `Const` lowering
+//! Chalk doesn't handle consts currently, so consts are currently lowered to
+//! an empty tuple.
+//!
+//! ## Bound variable collection
+//! Another difference between rustc and Chalk lies in the handling of binders.
+//! Chalk requires that we store the bound parameter kinds, whereas rustc does
+//! not. To lower anything wrapped in a `Binder`, we first deeply find any bound
+//! variables from the current `Binder`.
+
+use rustc_middle::traits::{
+    ChalkEnvironmentAndGoal, ChalkEnvironmentClause, ChalkRustInterner as RustInterner,
+};
+use rustc_middle::ty::fold::TypeFolder;
+use rustc_middle::ty::subst::{GenericArg, GenericArgKind, SubstsRef};
+use rustc_middle::ty::{
+    self, Binder, BoundRegion, Region, RegionKind, Ty, TyCtxt, TyKind, TypeFoldable, TypeVisitor,
+};
+use rustc_span::def_id::DefId;
+
+use std::collections::btree_map::{BTreeMap, Entry};
+
+use chalk_ir::fold::shift::Shift;
+
+/// Essentially an `Into` with a `&RustInterner` parameter
+crate trait LowerInto<'tcx, T> {
+    /// Lower a rustc construct (e.g., `ty::TraitPredicate`) to a chalk type, consuming `self`.
+    fn lower_into(self, interner: &RustInterner<'tcx>) -> T;
+}
+
+impl<'tcx> LowerInto<'tcx, chalk_ir::Substitution<RustInterner<'tcx>>> for SubstsRef<'tcx> {
+    fn lower_into(
+        self,
+        interner: &RustInterner<'tcx>,
+    ) -> chalk_ir::Substitution<RustInterner<'tcx>> {
+        chalk_ir::Substitution::from(interner, self.iter().map(|s| s.lower_into(interner)))
+    }
+}
+
+impl<'tcx> LowerInto<'tcx, chalk_ir::AliasTy<RustInterner<'tcx>>> for ty::ProjectionTy<'tcx> {
+    fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::AliasTy<RustInterner<'tcx>> {
+        chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy {
+            associated_ty_id: chalk_ir::AssocTypeId(self.item_def_id),
+            substitution: self.substs.lower_into(interner),
+        })
+    }
+}
+
+impl<'tcx> LowerInto<'tcx, chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'tcx>>>>
+    for ChalkEnvironmentAndGoal<'tcx>
+{
+    fn lower_into(
+        self,
+        interner: &RustInterner<'tcx>,
+    ) -> chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'tcx>>> {
+        let clauses = self.environment.into_iter().filter_map(|clause| match clause {
+            ChalkEnvironmentClause::Predicate(predicate) => {
+                // FIXME(chalk): forall
+                match predicate.bound_atom(interner.tcx).skip_binder() {
+                    ty::PredicateAtom::Trait(predicate, _) => {
+                        let predicate = ty::Binder::bind(predicate);
+                        let (predicate, binders, _named_regions) =
+                            collect_bound_vars(interner, interner.tcx, &predicate);
+
+                        Some(
+                            chalk_ir::ProgramClauseData(chalk_ir::Binders::new(
+                                binders,
+                                chalk_ir::ProgramClauseImplication {
+                                    consequence: chalk_ir::DomainGoal::FromEnv(
+                                        chalk_ir::FromEnv::Trait(
+                                            predicate.trait_ref.lower_into(interner),
+                                        ),
+                                    ),
+                                    conditions: chalk_ir::Goals::new(interner),
+                                    priority: chalk_ir::ClausePriority::High,
+                                },
+                            ))
+                            .intern(interner),
+                        )
+                    }
+                    ty::PredicateAtom::RegionOutlives(predicate) => {
+                        let predicate = ty::Binder::bind(predicate);
+                        let (predicate, binders, _named_regions) =
+                            collect_bound_vars(interner, interner.tcx, &predicate);
+
+                        Some(
+                            chalk_ir::ProgramClauseData(chalk_ir::Binders::new(
+                                binders,
+                                chalk_ir::ProgramClauseImplication {
+                                    consequence: chalk_ir::DomainGoal::Holds(
+                                        chalk_ir::WhereClause::LifetimeOutlives(
+                                            chalk_ir::LifetimeOutlives {
+                                                a: predicate.0.lower_into(interner),
+                                                b: predicate.1.lower_into(interner),
+                                            },
+                                        ),
+                                    ),
+                                    conditions: chalk_ir::Goals::new(interner),
+                                    priority: chalk_ir::ClausePriority::High,
+                                },
+                            ))
+                            .intern(interner),
+                        )
+                    }
+                    // FIXME(chalk): need to add TypeOutlives
+                    ty::PredicateAtom::TypeOutlives(_) => None,
+                    ty::PredicateAtom::Projection(predicate) => {
+                        let predicate = ty::Binder::bind(predicate);
+                        let (predicate, binders, _named_regions) =
+                            collect_bound_vars(interner, interner.tcx, &predicate);
+
+                        Some(
+                            chalk_ir::ProgramClauseData(chalk_ir::Binders::new(
+                                binders,
+                                chalk_ir::ProgramClauseImplication {
+                                    consequence: chalk_ir::DomainGoal::Holds(
+                                        chalk_ir::WhereClause::AliasEq(
+                                            predicate.lower_into(interner),
+                                        ),
+                                    ),
+                                    conditions: chalk_ir::Goals::new(interner),
+                                    priority: chalk_ir::ClausePriority::High,
+                                },
+                            ))
+                            .intern(interner),
+                        )
+                    }
+                    ty::PredicateAtom::WellFormed(..)
+                    | ty::PredicateAtom::ObjectSafe(..)
+                    | ty::PredicateAtom::ClosureKind(..)
+                    | ty::PredicateAtom::Subtype(..)
+                    | ty::PredicateAtom::ConstEvaluatable(..)
+                    | ty::PredicateAtom::ConstEquate(..) => {
+                        bug!("unexpected predicate {}", predicate)
+                    }
+                }
+            }
+            ChalkEnvironmentClause::TypeFromEnv(ty) => Some(
+                chalk_ir::ProgramClauseData(chalk_ir::Binders::new(
+                    chalk_ir::VariableKinds::new(interner),
+                    chalk_ir::ProgramClauseImplication {
+                        consequence: chalk_ir::DomainGoal::FromEnv(chalk_ir::FromEnv::Ty(
+                            ty.lower_into(interner).shifted_in(interner),
+                        )),
+                        conditions: chalk_ir::Goals::new(interner),
+                        priority: chalk_ir::ClausePriority::High,
+                    },
+                ))
+                .intern(interner),
+            ),
+        });
+
+        let goal: chalk_ir::GoalData<RustInterner<'tcx>> = self.goal.lower_into(&interner);
+        chalk_ir::InEnvironment {
+            environment: chalk_ir::Environment {
+                clauses: chalk_ir::ProgramClauses::from(&interner, clauses),
+            },
+            goal: goal.intern(&interner),
+        }
+    }
+}
+
+impl<'tcx> LowerInto<'tcx, chalk_ir::GoalData<RustInterner<'tcx>>> for ty::Predicate<'tcx> {
+    fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GoalData<RustInterner<'tcx>> {
+        // FIXME(chalk): forall
+        match self.bound_atom(interner.tcx).skip_binder() {
+            ty::PredicateAtom::Trait(predicate, _) => {
+                ty::Binder::bind(predicate).lower_into(interner)
+            }
+            ty::PredicateAtom::RegionOutlives(predicate) => {
+                let predicate = ty::Binder::bind(predicate);
+                let (predicate, binders, _named_regions) =
+                    collect_bound_vars(interner, interner.tcx, &predicate);
+
+                chalk_ir::GoalData::Quantified(
+                    chalk_ir::QuantifierKind::ForAll,
+                    chalk_ir::Binders::new(
+                        binders,
+                        chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
+                            chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives {
+                                a: predicate.0.lower_into(interner),
+                                b: predicate.1.lower_into(interner),
+                            }),
+                        ))
+                        .intern(interner),
+                    ),
+                )
+            }
+            // FIXME(chalk): TypeOutlives
+            ty::PredicateAtom::TypeOutlives(_predicate) => {
+                chalk_ir::GoalData::All(chalk_ir::Goals::new(interner))
+            }
+            ty::PredicateAtom::Projection(predicate) => {
+                ty::Binder::bind(predicate).lower_into(interner)
+            }
+            ty::PredicateAtom::WellFormed(arg) => match arg.unpack() {
+                GenericArgKind::Type(ty) => match ty.kind {
+                    // FIXME(chalk): In Chalk, a placeholder is WellFormed if it
+                    // `FromEnv`. However, when we "lower" Params, we don't update
+                    // the environment.
+                    ty::Placeholder(..) => chalk_ir::GoalData::All(chalk_ir::Goals::new(interner)),
+
+                    _ => {
+                        let (ty, binders, _named_regions) =
+                            collect_bound_vars(interner, interner.tcx, &ty::Binder::bind(ty));
+
+                        chalk_ir::GoalData::Quantified(
+                            chalk_ir::QuantifierKind::ForAll,
+                            chalk_ir::Binders::new(
+                                binders,
+                                chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::WellFormed(
+                                    chalk_ir::WellFormed::Ty(ty.lower_into(interner)),
+                                ))
+                                .intern(interner),
+                            ),
+                        )
+                    }
+                },
+                // FIXME(chalk): handle well formed consts
+                GenericArgKind::Const(..) => {
+                    chalk_ir::GoalData::All(chalk_ir::Goals::new(interner))
+                }
+                GenericArgKind::Lifetime(lt) => bug!("unexpect well formed predicate: {:?}", lt),
+            },
+
+            ty::PredicateAtom::ObjectSafe(t) => chalk_ir::GoalData::DomainGoal(
+                chalk_ir::DomainGoal::ObjectSafe(chalk_ir::TraitId(t)),
+            ),
+
+            // FIXME(chalk): other predicates
+            //
+            // We can defer this, but ultimately we'll want to express
+            // some of these in terms of chalk operations.
+            ty::PredicateAtom::ClosureKind(..)
+            | ty::PredicateAtom::Subtype(..)
+            | ty::PredicateAtom::ConstEvaluatable(..)
+            | ty::PredicateAtom::ConstEquate(..) => {
+                chalk_ir::GoalData::All(chalk_ir::Goals::new(interner))
+            }
+        }
+    }
+}
+
+impl<'tcx> LowerInto<'tcx, chalk_ir::TraitRef<RustInterner<'tcx>>>
+    for rustc_middle::ty::TraitRef<'tcx>
+{
+    fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::TraitRef<RustInterner<'tcx>> {
+        chalk_ir::TraitRef {
+            trait_id: chalk_ir::TraitId(self.def_id),
+            substitution: self.substs.lower_into(interner),
+        }
+    }
+}
+
+impl<'tcx> LowerInto<'tcx, chalk_ir::GoalData<RustInterner<'tcx>>>
+    for ty::PolyTraitPredicate<'tcx>
+{
+    fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GoalData<RustInterner<'tcx>> {
+        let (ty, binders, _named_regions) = collect_bound_vars(interner, interner.tcx, &self);
+
+        chalk_ir::GoalData::Quantified(
+            chalk_ir::QuantifierKind::ForAll,
+            chalk_ir::Binders::new(
+                binders,
+                chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
+                    chalk_ir::WhereClause::Implemented(ty.trait_ref.lower_into(interner)),
+                ))
+                .intern(interner),
+            ),
+        )
+    }
+}
+
+impl<'tcx> LowerInto<'tcx, chalk_ir::AliasEq<RustInterner<'tcx>>>
+    for rustc_middle::ty::ProjectionPredicate<'tcx>
+{
+    fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::AliasEq<RustInterner<'tcx>> {
+        chalk_ir::AliasEq {
+            ty: self.ty.lower_into(interner),
+            alias: self.projection_ty.lower_into(interner),
+        }
+    }
+}
+
+impl<'tcx> LowerInto<'tcx, chalk_ir::GoalData<RustInterner<'tcx>>>
+    for ty::PolyProjectionPredicate<'tcx>
+{
+    fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GoalData<RustInterner<'tcx>> {
+        let (ty, binders, _named_regions) = collect_bound_vars(interner, interner.tcx, &self);
+
+        chalk_ir::GoalData::Quantified(
+            chalk_ir::QuantifierKind::ForAll,
+            chalk_ir::Binders::new(
+                binders,
+                chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
+                    chalk_ir::WhereClause::AliasEq(ty.lower_into(interner)),
+                ))
+                .intern(interner),
+            ),
+        )
+    }
+}
+
+impl<'tcx> LowerInto<'tcx, chalk_ir::Ty<RustInterner<'tcx>>> for Ty<'tcx> {
+    fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::Ty<RustInterner<'tcx>> {
+        use chalk_ir::TyData;
+        use rustc_ast as ast;
+        use TyKind::*;
+
+        let empty = || chalk_ir::Substitution::empty(interner);
+        let struct_ty =
+            |def_id| chalk_ir::TypeName::Adt(chalk_ir::AdtId(interner.tcx.adt_def(def_id)));
+        let apply = |name, substitution| {
+            TyData::Apply(chalk_ir::ApplicationTy { name, substitution }).intern(interner)
+        };
+        let int = |i| apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Int(i)), empty());
+        let uint = |i| apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Uint(i)), empty());
+        let float = |f| apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Float(f)), empty());
+
+        match self.kind {
+            Bool => apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Bool), empty()),
+            Char => apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Char), empty()),
+            Int(ty) => match ty {
+                ast::IntTy::Isize => int(chalk_ir::IntTy::Isize),
+                ast::IntTy::I8 => int(chalk_ir::IntTy::I8),
+                ast::IntTy::I16 => int(chalk_ir::IntTy::I16),
+                ast::IntTy::I32 => int(chalk_ir::IntTy::I32),
+                ast::IntTy::I64 => int(chalk_ir::IntTy::I64),
+                ast::IntTy::I128 => int(chalk_ir::IntTy::I128),
+            },
+            Uint(ty) => match ty {
+                ast::UintTy::Usize => uint(chalk_ir::UintTy::Usize),
+                ast::UintTy::U8 => uint(chalk_ir::UintTy::U8),
+                ast::UintTy::U16 => uint(chalk_ir::UintTy::U16),
+                ast::UintTy::U32 => uint(chalk_ir::UintTy::U32),
+                ast::UintTy::U64 => uint(chalk_ir::UintTy::U64),
+                ast::UintTy::U128 => uint(chalk_ir::UintTy::U128),
+            },
+            Float(ty) => match ty {
+                ast::FloatTy::F32 => float(chalk_ir::FloatTy::F32),
+                ast::FloatTy::F64 => float(chalk_ir::FloatTy::F64),
+            },
+            Adt(def, substs) => apply(struct_ty(def.did), substs.lower_into(interner)),
+            Foreign(_def_id) => unimplemented!(),
+            Str => apply(chalk_ir::TypeName::Str, empty()),
+            Array(ty, len) => {
+                let value = match len.val {
+                    ty::ConstKind::Value(val) => {
+                        chalk_ir::ConstValue::Concrete(chalk_ir::ConcreteConst { interned: val })
+                    }
+                    ty::ConstKind::Bound(db, bound) => {
+                        chalk_ir::ConstValue::BoundVar(chalk_ir::BoundVar::new(
+                            chalk_ir::DebruijnIndex::new(db.as_u32()),
+                            bound.index(),
+                        ))
+                    }
+                    _ => unimplemented!("Const not implemented. {:?}", len.val),
+                };
+                apply(
+                    chalk_ir::TypeName::Array,
+                    chalk_ir::Substitution::from(
+                        interner,
+                        &[
+                            chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner),
+                            chalk_ir::GenericArgData::Const(
+                                chalk_ir::ConstData { ty: len.ty.lower_into(interner), value }
+                                    .intern(interner),
+                            )
+                            .intern(interner),
+                        ],
+                    ),
+                )
+            }
+            Slice(ty) => apply(
+                chalk_ir::TypeName::Slice,
+                chalk_ir::Substitution::from1(
+                    interner,
+                    chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner),
+                ),
+            ),
+            RawPtr(ptr) => {
+                let name = match ptr.mutbl {
+                    ast::Mutability::Mut => chalk_ir::TypeName::Raw(chalk_ir::Mutability::Mut),
+                    ast::Mutability::Not => chalk_ir::TypeName::Raw(chalk_ir::Mutability::Not),
+                };
+                apply(name, chalk_ir::Substitution::from1(interner, ptr.ty.lower_into(interner)))
+            }
+            Ref(region, ty, mutability) => {
+                let name = match mutability {
+                    ast::Mutability::Mut => chalk_ir::TypeName::Ref(chalk_ir::Mutability::Mut),
+                    ast::Mutability::Not => chalk_ir::TypeName::Ref(chalk_ir::Mutability::Not),
+                };
+                apply(
+                    name,
+                    chalk_ir::Substitution::from(
+                        interner,
+                        &[
+                            chalk_ir::GenericArgData::Lifetime(region.lower_into(interner))
+                                .intern(interner),
+                            chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner),
+                        ],
+                    ),
+                )
+            }
+            FnDef(def_id, substs) => apply(
+                chalk_ir::TypeName::FnDef(chalk_ir::FnDefId(def_id)),
+                substs.lower_into(interner),
+            ),
+            FnPtr(sig) => {
+                let (inputs_and_outputs, binders, _named_regions) =
+                    collect_bound_vars(interner, interner.tcx, &sig.inputs_and_output());
+                TyData::Function(chalk_ir::Fn {
+                    num_binders: binders.len(interner),
+                    substitution: chalk_ir::Substitution::from(
+                        interner,
+                        inputs_and_outputs.iter().map(|ty| {
+                            chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner)
+                        }),
+                    ),
+                })
+                .intern(interner)
+            }
+            Dynamic(predicates, region) => TyData::Dyn(chalk_ir::DynTy {
+                bounds: predicates.lower_into(interner),
+                lifetime: region.lower_into(interner),
+            })
+            .intern(interner),
+            Closure(def_id, substs) => apply(
+                chalk_ir::TypeName::Closure(chalk_ir::ClosureId(def_id)),
+                substs.lower_into(interner),
+            ),
+            Generator(_def_id, _substs, _) => unimplemented!(),
+            GeneratorWitness(_) => unimplemented!(),
+            Never => apply(chalk_ir::TypeName::Never, empty()),
+            Tuple(substs) => {
+                apply(chalk_ir::TypeName::Tuple(substs.len()), substs.lower_into(interner))
+            }
+            Projection(proj) => TyData::Alias(proj.lower_into(interner)).intern(interner),
+            Opaque(def_id, substs) => {
+                TyData::Alias(chalk_ir::AliasTy::Opaque(chalk_ir::OpaqueTy {
+                    opaque_ty_id: chalk_ir::OpaqueTyId(def_id),
+                    substitution: substs.lower_into(interner),
+                }))
+                .intern(interner)
+            }
+            // This should have been done eagerly prior to this, and all Params
+            // should have been substituted to placeholders
+            Param(_) => panic!("Lowering Param when not expected."),
+            Bound(db, bound) => TyData::BoundVar(chalk_ir::BoundVar::new(
+                chalk_ir::DebruijnIndex::new(db.as_u32()),
+                bound.var.index(),
+            ))
+            .intern(interner),
+            Placeholder(_placeholder) => TyData::Placeholder(chalk_ir::PlaceholderIndex {
+                ui: chalk_ir::UniverseIndex { counter: _placeholder.universe.as_usize() },
+                idx: _placeholder.name.as_usize(),
+            })
+            .intern(interner),
+            Infer(_infer) => unimplemented!(),
+            Error(_) => apply(chalk_ir::TypeName::Error, empty()),
+        }
+    }
+}
+
+impl<'tcx> LowerInto<'tcx, chalk_ir::Lifetime<RustInterner<'tcx>>> for Region<'tcx> {
+    fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::Lifetime<RustInterner<'tcx>> {
+        use rustc_middle::ty::RegionKind::*;
+
+        match self {
+            ReEarlyBound(_) => {
+                panic!("Should have already been substituted.");
+            }
+            ReLateBound(db, br) => match br {
+                ty::BoundRegion::BrAnon(var) => {
+                    chalk_ir::LifetimeData::BoundVar(chalk_ir::BoundVar::new(
+                        chalk_ir::DebruijnIndex::new(db.as_u32()),
+                        *var as usize,
+                    ))
+                    .intern(interner)
+                }
+                ty::BoundRegion::BrNamed(_def_id, _name) => unimplemented!(),
+                ty::BrEnv => unimplemented!(),
+            },
+            ReFree(_) => unimplemented!(),
+            // FIXME(chalk): need to handle ReStatic
+            ReStatic => unimplemented!(),
+            ReVar(_) => unimplemented!(),
+            RePlaceholder(placeholder_region) => {
+                chalk_ir::LifetimeData::Placeholder(chalk_ir::PlaceholderIndex {
+                    ui: chalk_ir::UniverseIndex { counter: placeholder_region.universe.index() },
+                    idx: 0,
+                })
+                .intern(interner)
+            }
+            ReEmpty(_) => unimplemented!(),
+            // FIXME(chalk): need to handle ReErased
+            ReErased => unimplemented!(),
+        }
+    }
+}
+
+impl<'tcx> LowerInto<'tcx, chalk_ir::GenericArg<RustInterner<'tcx>>> for GenericArg<'tcx> {
+    fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GenericArg<RustInterner<'tcx>> {
+        match self.unpack() {
+            ty::subst::GenericArgKind::Type(ty) => {
+                chalk_ir::GenericArgData::Ty(ty.lower_into(interner))
+            }
+            ty::subst::GenericArgKind::Lifetime(lifetime) => {
+                chalk_ir::GenericArgData::Lifetime(lifetime.lower_into(interner))
+            }
+            ty::subst::GenericArgKind::Const(_) => chalk_ir::GenericArgData::Ty(
+                chalk_ir::TyData::Apply(chalk_ir::ApplicationTy {
+                    name: chalk_ir::TypeName::Tuple(0),
+                    substitution: chalk_ir::Substitution::empty(interner),
+                })
+                .intern(interner),
+            ),
+        }
+        .intern(interner)
+    }
+}
+
+// We lower into an Option here since there are some predicates which Chalk
+// doesn't have a representation for yet (as a `WhereClause`), but are so common
+// that we just are accepting the unsoundness for now. The `Option` will
+// eventually be removed.
+impl<'tcx> LowerInto<'tcx, Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>
+    for ty::Predicate<'tcx>
+{
+    fn lower_into(
+        self,
+        interner: &RustInterner<'tcx>,
+    ) -> Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>> {
+        // FIXME(chalk): forall
+        match self.bound_atom(interner.tcx).skip_binder() {
+            ty::PredicateAtom::Trait(predicate, _) => {
+                let predicate = ty::Binder::bind(predicate);
+                let (predicate, binders, _named_regions) =
+                    collect_bound_vars(interner, interner.tcx, &predicate);
+
+                Some(chalk_ir::Binders::new(
+                    binders,
+                    chalk_ir::WhereClause::Implemented(predicate.trait_ref.lower_into(interner)),
+                ))
+            }
+            ty::PredicateAtom::RegionOutlives(predicate) => {
+                let predicate = ty::Binder::bind(predicate);
+                let (predicate, binders, _named_regions) =
+                    collect_bound_vars(interner, interner.tcx, &predicate);
+
+                Some(chalk_ir::Binders::new(
+                    binders,
+                    chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives {
+                        a: predicate.0.lower_into(interner),
+                        b: predicate.1.lower_into(interner),
+                    }),
+                ))
+            }
+            ty::PredicateAtom::TypeOutlives(_predicate) => None,
+            ty::PredicateAtom::Projection(_predicate) => None,
+            ty::PredicateAtom::WellFormed(_ty) => None,
+
+            ty::PredicateAtom::ObjectSafe(..)
+            | ty::PredicateAtom::ClosureKind(..)
+            | ty::PredicateAtom::Subtype(..)
+            | ty::PredicateAtom::ConstEvaluatable(..)
+            | ty::PredicateAtom::ConstEquate(..) => bug!("unexpected predicate {}", &self),
+        }
+    }
+}
+
+impl<'tcx> LowerInto<'tcx, chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>>>
+    for Binder<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>>
+{
+    fn lower_into(
+        self,
+        interner: &RustInterner<'tcx>,
+    ) -> chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>> {
+        let (predicates, binders, _named_regions) =
+            collect_bound_vars(interner, interner.tcx, &self);
+        let where_clauses = predicates.into_iter().map(|predicate| match predicate {
+            ty::ExistentialPredicate::Trait(ty::ExistentialTraitRef { def_id, substs }) => {
+                chalk_ir::Binders::new(
+                    chalk_ir::VariableKinds::new(interner),
+                    chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef {
+                        trait_id: chalk_ir::TraitId(def_id),
+                        substitution: substs.lower_into(interner),
+                    }),
+                )
+            }
+            ty::ExistentialPredicate::Projection(_predicate) => unimplemented!(),
+            ty::ExistentialPredicate::AutoTrait(def_id) => chalk_ir::Binders::new(
+                chalk_ir::VariableKinds::new(interner),
+                chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef {
+                    trait_id: chalk_ir::TraitId(def_id),
+                    substitution: chalk_ir::Substitution::empty(interner),
+                }),
+            ),
+        });
+        let value = chalk_ir::QuantifiedWhereClauses::from(interner, where_clauses);
+        chalk_ir::Binders::new(binders, value)
+    }
+}
+
+/// To collect bound vars, we have to do two passes. In the first pass, we
+/// collect all `BoundRegion`s and `ty::Bound`s. In the second pass, we then
+/// replace `BrNamed` into `BrAnon`. The two separate passes are important,
+/// since we can only replace `BrNamed` with `BrAnon`s with indices *after* all
+/// "real" `BrAnon`s.
+///
+/// It's important to note that because of prior substitution, we may have
+/// late-bound regions, even outside of fn contexts, since this is the best way
+/// to prep types for chalk lowering.
+crate fn collect_bound_vars<'a, 'tcx, T: TypeFoldable<'tcx>>(
+    interner: &RustInterner<'tcx>,
+    tcx: TyCtxt<'tcx>,
+    ty: &'a Binder<T>,
+) -> (T, chalk_ir::VariableKinds<RustInterner<'tcx>>, BTreeMap<DefId, u32>) {
+    let mut bound_vars_collector = BoundVarsCollector::new();
+    ty.as_ref().skip_binder().visit_with(&mut bound_vars_collector);
+    let mut parameters = bound_vars_collector.parameters;
+    let named_parameters: BTreeMap<DefId, u32> = bound_vars_collector
+        .named_parameters
+        .into_iter()
+        .enumerate()
+        .map(|(i, def_id)| (def_id, (i + parameters.len()) as u32))
+        .collect();
+
+    let mut bound_var_substitutor = NamedBoundVarSubstitutor::new(tcx, &named_parameters);
+    let new_ty = ty.as_ref().skip_binder().fold_with(&mut bound_var_substitutor);
+
+    for var in named_parameters.values() {
+        parameters.insert(*var, chalk_ir::VariableKind::Lifetime);
+    }
+
+    (0..parameters.len()).for_each(|i| {
+        parameters
+            .get(&(i as u32))
+            .or_else(|| bug!("Skipped bound var index: ty={:?}, parameters={:?}", ty, parameters));
+    });
+
+    let binders = chalk_ir::VariableKinds::from(interner, parameters.into_iter().map(|(_, v)| v));
+
+    (new_ty, binders, named_parameters)
+}
+
+crate struct BoundVarsCollector<'tcx> {
+    binder_index: ty::DebruijnIndex,
+    crate parameters: BTreeMap<u32, chalk_ir::VariableKind<RustInterner<'tcx>>>,
+    crate named_parameters: Vec<DefId>,
+}
+
+impl<'tcx> BoundVarsCollector<'tcx> {
+    crate fn new() -> Self {
+        BoundVarsCollector {
+            binder_index: ty::INNERMOST,
+            parameters: BTreeMap::new(),
+            named_parameters: vec![],
+        }
+    }
+}
+
+impl<'tcx> TypeVisitor<'tcx> for BoundVarsCollector<'tcx> {
+    fn visit_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> bool {
+        self.binder_index.shift_in(1);
+        let result = t.super_visit_with(self);
+        self.binder_index.shift_out(1);
+        result
+    }
+
+    fn visit_ty(&mut self, t: Ty<'tcx>) -> bool {
+        match t.kind {
+            ty::Bound(debruijn, bound_ty) if debruijn == self.binder_index => {
+                match self.parameters.entry(bound_ty.var.as_u32()) {
+                    Entry::Vacant(entry) => {
+                        entry.insert(chalk_ir::VariableKind::Ty(chalk_ir::TyKind::General));
+                    }
+                    Entry::Occupied(entry) => match entry.get() {
+                        chalk_ir::VariableKind::Ty(_) => {}
+                        _ => panic!(),
+                    },
+                }
+            }
+
+            _ => (),
+        };
+
+        t.super_visit_with(self)
+    }
+
+    fn visit_region(&mut self, r: Region<'tcx>) -> bool {
+        match r {
+            ty::ReLateBound(index, br) if *index == self.binder_index => match br {
+                ty::BoundRegion::BrNamed(def_id, _name) => {
+                    if self.named_parameters.iter().find(|d| *d == def_id).is_none() {
+                        self.named_parameters.push(*def_id);
+                    }
+                }
+
+                ty::BoundRegion::BrAnon(var) => match self.parameters.entry(*var) {
+                    Entry::Vacant(entry) => {
+                        entry.insert(chalk_ir::VariableKind::Lifetime);
+                    }
+                    Entry::Occupied(entry) => match entry.get() {
+                        chalk_ir::VariableKind::Lifetime => {}
+                        _ => panic!(),
+                    },
+                },
+
+                ty::BrEnv => unimplemented!(),
+            },
+
+            ty::ReEarlyBound(_re) => {
+                // FIXME(chalk): jackh726 - I think we should always have already
+                // substituted away `ReEarlyBound`s for `ReLateBound`s, but need to confirm.
+                unimplemented!();
+            }
+
+            _ => (),
+        };
+
+        r.super_visit_with(self)
+    }
+}
+
+/// This is used to replace `BoundRegion::BrNamed` with `BoundRegion::BrAnon`.
+/// Note: we assume that we will always have room for more bound vars. (i.e. we
+/// won't ever hit the `u32` limit in `BrAnon`s).
+struct NamedBoundVarSubstitutor<'a, 'tcx> {
+    tcx: TyCtxt<'tcx>,
+    binder_index: ty::DebruijnIndex,
+    named_parameters: &'a BTreeMap<DefId, u32>,
+}
+
+impl<'a, 'tcx> NamedBoundVarSubstitutor<'a, 'tcx> {
+    fn new(tcx: TyCtxt<'tcx>, named_parameters: &'a BTreeMap<DefId, u32>) -> Self {
+        NamedBoundVarSubstitutor { tcx, binder_index: ty::INNERMOST, named_parameters }
+    }
+}
+
+impl<'a, 'tcx> TypeFolder<'tcx> for NamedBoundVarSubstitutor<'a, 'tcx> {
+    fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
+        self.tcx
+    }
+
+    fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> Binder<T> {
+        self.binder_index.shift_in(1);
+        let result = t.super_fold_with(self);
+        self.binder_index.shift_out(1);
+        result
+    }
+
+    fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
+        t.super_fold_with(self)
+    }
+
+    fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> {
+        match r {
+            ty::ReLateBound(index, br) if *index == self.binder_index => match br {
+                ty::BoundRegion::BrNamed(def_id, _name) => {
+                    match self.named_parameters.get(def_id) {
+                        Some(idx) => {
+                            return self.tcx.mk_region(RegionKind::ReLateBound(
+                                *index,
+                                BoundRegion::BrAnon(*idx),
+                            ));
+                        }
+                        None => panic!("Missing `BrNamed`."),
+                    }
+                }
+                ty::BrEnv => unimplemented!(),
+                ty::BoundRegion::BrAnon(_) => {}
+            },
+            _ => (),
+        };
+
+        r.super_fold_with(self)
+    }
+}
+
+/// Used to substitute `Param`s with placeholders. We do this since Chalk
+/// have a notion of `Param`s.
+crate struct ParamsSubstitutor<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    binder_index: ty::DebruijnIndex,
+    list: Vec<rustc_middle::ty::ParamTy>,
+    crate params: rustc_data_structures::fx::FxHashMap<usize, rustc_middle::ty::ParamTy>,
+    crate named_regions: BTreeMap<DefId, u32>,
+}
+
+impl<'tcx> ParamsSubstitutor<'tcx> {
+    crate fn new(tcx: TyCtxt<'tcx>) -> Self {
+        ParamsSubstitutor {
+            tcx,
+            binder_index: ty::INNERMOST,
+            list: vec![],
+            params: rustc_data_structures::fx::FxHashMap::default(),
+            named_regions: BTreeMap::default(),
+        }
+    }
+}
+
+impl<'tcx> TypeFolder<'tcx> for ParamsSubstitutor<'tcx> {
+    fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
+        self.tcx
+    }
+
+    fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> Binder<T> {
+        self.binder_index.shift_in(1);
+        let result = t.super_fold_with(self);
+        self.binder_index.shift_out(1);
+        result
+    }
+
+    fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
+        match t.kind {
+            // FIXME(chalk): currently we convert params to placeholders starting at
+            // index `0`. To support placeholders, we'll actually need to do a
+            // first pass to collect placeholders. Then we can insert params after.
+            ty::Placeholder(_) => unimplemented!(),
+            ty::Param(param) => match self.list.iter().position(|r| r == &param) {
+                Some(_idx) => self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
+                    universe: ty::UniverseIndex::from_usize(0),
+                    name: ty::BoundVar::from_usize(_idx),
+                })),
+                None => {
+                    self.list.push(param);
+                    let idx = self.list.len() - 1;
+                    self.params.insert(idx, param);
+                    self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
+                        universe: ty::UniverseIndex::from_usize(0),
+                        name: ty::BoundVar::from_usize(idx),
+                    }))
+                }
+            },
+
+            _ => t.super_fold_with(self),
+        }
+    }
+
+    fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> {
+        match r {
+            // FIXME(chalk) - jackh726 - this currently isn't hit in any tests.
+            // This covers any region variables in a goal, right?
+            ty::ReEarlyBound(_re) => match self.named_regions.get(&_re.def_id) {
+                Some(idx) => self.tcx.mk_region(RegionKind::ReLateBound(
+                    self.binder_index,
+                    BoundRegion::BrAnon(*idx),
+                )),
+                None => {
+                    let idx = self.named_regions.len() as u32;
+                    self.named_regions.insert(_re.def_id, idx);
+                    self.tcx.mk_region(RegionKind::ReLateBound(
+                        self.binder_index,
+                        BoundRegion::BrAnon(idx),
+                    ))
+                }
+            },
+
+            _ => r.super_fold_with(self),
+        }
+    }
+}
diff --git a/compiler/rustc_traits/src/chalk/mod.rs b/compiler/rustc_traits/src/chalk/mod.rs
new file mode 100644
index 00000000000..f18b4ca65f6
--- /dev/null
+++ b/compiler/rustc_traits/src/chalk/mod.rs
@@ -0,0 +1,229 @@
+//! Calls `chalk-solve` to solve a `ty::Predicate`
+//!
+//! In order to call `chalk-solve`, this file must convert a
+//! `ChalkCanonicalGoal` into a Chalk ucanonical goal. It then calls Chalk, and
+//! converts the answer back into rustc solution.
+
+crate mod db;
+crate mod lowering;
+
+use rustc_data_structures::fx::FxHashMap;
+
+use rustc_index::vec::IndexVec;
+
+use rustc_middle::infer::canonical::{CanonicalTyVarKind, CanonicalVarKind};
+use rustc_middle::traits::ChalkRustInterner;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::subst::GenericArg;
+use rustc_middle::ty::{
+    self, Bound, BoundVar, ParamTy, Region, RegionKind, Ty, TyCtxt, TypeFoldable,
+};
+
+use rustc_infer::infer::canonical::{
+    Canonical, CanonicalVarValues, Certainty, QueryRegionConstraints, QueryResponse,
+};
+use rustc_infer::traits::{self, ChalkCanonicalGoal};
+
+use crate::chalk::db::RustIrDatabase as ChalkRustIrDatabase;
+use crate::chalk::lowering::{LowerInto, ParamsSubstitutor};
+
+use chalk_solve::Solution;
+
+crate fn provide(p: &mut Providers) {
+    *p = Providers { evaluate_goal, ..*p };
+}
+
+crate fn evaluate_goal<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    obligation: ChalkCanonicalGoal<'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 params_substitutor = ParamsSubstitutor::new(tcx);
+    let obligation = obligation.fold_with(&mut params_substitutor);
+    let _params: FxHashMap<usize, ParamTy> = 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(
+                &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::TyKind::General),
+                            chalk_ir::UniverseIndex { counter: ui.index() },
+                        ),
+                        CanonicalTyVarKind::Int => chalk_ir::WithKind::new(
+                            chalk_ir::VariableKind::Ty(chalk_ir::TyKind::Integer),
+                            chalk_ir::UniverseIndex::root(),
+                        ),
+                        CanonicalTyVarKind::Float => chalk_ir::WithKind::new(
+                            chalk_ir::VariableKind::Ty(chalk_ir::TyKind::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) => unimplemented!(),
+                    CanonicalVarKind::PlaceholderConst(_pc) => unimplemented!(),
+                }),
+            ),
+            value: obligation.value.lower_into(&interner),
+        },
+        universes: max_universe + 1,
+    };
+
+    let solver_choice = chalk_solve::SolverChoice::SLG { max_size: 32, expected_answers: None };
+    let mut solver = solver_choice.into_solver::<ChalkRustInterner<'tcx>>();
+
+    let db = ChalkRustIrDatabase { tcx, interner };
+    let solution = solver.solve(&db, &_lowered_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<_>| {
+        let mut var_values: IndexVec<BoundVar, GenericArg<'tcx>> = IndexVec::new();
+        _subst.parameters(&interner).iter().for_each(|p| {
+            // FIXME(chalk): we should move this elsewhere, since this is
+            // essentially inverse of lowering a `GenericArg`.
+            let _data = p.data(&interner);
+            match _data {
+                chalk_ir::GenericArgData::Ty(_t) => {
+                    use chalk_ir::TyData;
+                    use rustc_ast as ast;
+
+                    let _data = _t.data(&interner);
+                    let kind = match _data {
+                        TyData::Apply(_application_ty) => match _application_ty.name {
+                            chalk_ir::TypeName::Adt(_struct_id) => unimplemented!(),
+                            chalk_ir::TypeName::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(ast::IntTy::Isize),
+                                    chalk_ir::IntTy::I8 => ty::Int(ast::IntTy::I8),
+                                    chalk_ir::IntTy::I16 => ty::Int(ast::IntTy::I16),
+                                    chalk_ir::IntTy::I32 => ty::Int(ast::IntTy::I32),
+                                    chalk_ir::IntTy::I64 => ty::Int(ast::IntTy::I64),
+                                    chalk_ir::IntTy::I128 => ty::Int(ast::IntTy::I128),
+                                },
+                                chalk_ir::Scalar::Uint(int_ty) => match int_ty {
+                                    chalk_ir::UintTy::Usize => ty::Uint(ast::UintTy::Usize),
+                                    chalk_ir::UintTy::U8 => ty::Uint(ast::UintTy::U8),
+                                    chalk_ir::UintTy::U16 => ty::Uint(ast::UintTy::U16),
+                                    chalk_ir::UintTy::U32 => ty::Uint(ast::UintTy::U32),
+                                    chalk_ir::UintTy::U64 => ty::Uint(ast::UintTy::U64),
+                                    chalk_ir::UintTy::U128 => ty::Uint(ast::UintTy::U128),
+                                },
+                                chalk_ir::Scalar::Float(float_ty) => match float_ty {
+                                    chalk_ir::FloatTy::F32 => ty::Float(ast::FloatTy::F32),
+                                    chalk_ir::FloatTy::F64 => ty::Float(ast::FloatTy::F64),
+                                },
+                            },
+                            chalk_ir::TypeName::Array => unimplemented!(),
+                            chalk_ir::TypeName::FnDef(_) => unimplemented!(),
+                            chalk_ir::TypeName::Closure(_) => unimplemented!(),
+                            chalk_ir::TypeName::Never => unimplemented!(),
+                            chalk_ir::TypeName::Tuple(_size) => unimplemented!(),
+                            chalk_ir::TypeName::Slice => unimplemented!(),
+                            chalk_ir::TypeName::Raw(_) => unimplemented!(),
+                            chalk_ir::TypeName::Ref(_) => unimplemented!(),
+                            chalk_ir::TypeName::Str => unimplemented!(),
+                            chalk_ir::TypeName::OpaqueType(_ty) => unimplemented!(),
+                            chalk_ir::TypeName::AssociatedType(_assoc_ty) => unimplemented!(),
+                            chalk_ir::TypeName::Error => unimplemented!(),
+                        },
+                        TyData::Placeholder(_placeholder) => {
+                            unimplemented!();
+                        }
+                        TyData::Alias(_alias_ty) => unimplemented!(),
+                        TyData::Function(_quantified_ty) => unimplemented!(),
+                        TyData::BoundVar(_bound) => Bound(
+                            ty::DebruijnIndex::from_usize(_bound.debruijn.depth() as usize),
+                            ty::BoundTy {
+                                var: ty::BoundVar::from_usize(_bound.index),
+                                kind: ty::BoundTyKind::Anon,
+                            },
+                        ),
+                        TyData::InferenceVar(_, _) => unimplemented!(),
+                        TyData::Dyn(_) => unimplemented!(),
+                    };
+                    let _ty: Ty<'_> = tcx.mk_ty(kind);
+                    let _arg: GenericArg<'_> = _ty.into();
+                    var_values.push(_arg);
+                }
+                chalk_ir::GenericArgData::Lifetime(_l) => {
+                    let _data = _l.data(&interner);
+                    let _lifetime: Region<'_> = match _data {
+                        chalk_ir::LifetimeData::BoundVar(_var) => {
+                            tcx.mk_region(RegionKind::ReLateBound(
+                                rustc_middle::ty::DebruijnIndex::from_usize(
+                                    _var.debruijn.depth() as usize
+                                ),
+                                rustc_middle::ty::BoundRegion::BrAnon(_var.index as u32),
+                            ))
+                        }
+                        chalk_ir::LifetimeData::InferenceVar(_var) => unimplemented!(),
+                        chalk_ir::LifetimeData::Placeholder(_index) => unimplemented!(),
+                        chalk_ir::LifetimeData::Phantom(_, _) => unimplemented!(),
+                    };
+                    let _arg: GenericArg<'_> = _lifetime.into();
+                    var_values.push(_arg);
+                }
+                chalk_ir::GenericArgData::Const(_) => unimplemented!(),
+            }
+        });
+        let sol = Canonical {
+            max_universe: ty::UniverseIndex::from_usize(0),
+            variables: obligation.variables.clone(),
+            value: QueryResponse {
+                var_values: CanonicalVarValues { var_values },
+                region_constraints: QueryRegionConstraints::default(),
+                certainty: Certainty::Proven,
+                value: (),
+            },
+        };
+        &*tcx.arena.alloc(sol)
+    };
+    solution
+        .map(|s| match s {
+            Solution::Unique(_subst) => {
+                // FIXME(chalk): handle constraints
+                make_solution(_subst.value.subst)
+            }
+            Solution::Ambig(_guidance) => {
+                match _guidance {
+                    chalk_solve::Guidance::Definite(_subst) => make_solution(_subst.value),
+                    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.clone(),
+                            value: QueryResponse {
+                                var_values: CanonicalVarValues { var_values: IndexVec::new() }
+                                    .make_identity(tcx),
+                                region_constraints: QueryRegionConstraints::default(),
+                                certainty: Certainty::Ambiguous,
+                                value: (),
+                            },
+                        };
+                        &*tcx.arena.alloc(sol)
+                    }
+                }
+            }
+        })
+        .ok_or(traits::query::NoSolution)
+}
diff --git a/compiler/rustc_traits/src/dropck_outlives.rs b/compiler/rustc_traits/src/dropck_outlives.rs
new file mode 100644
index 00000000000..ce00060b9b1
--- /dev/null
+++ b/compiler/rustc_traits/src/dropck_outlives.rs
@@ -0,0 +1,326 @@
+use rustc_data_structures::fx::FxHashSet;
+use rustc_hir::def_id::DefId;
+use rustc_infer::infer::canonical::{Canonical, QueryResponse};
+use rustc_infer::infer::TyCtxtInferExt;
+use rustc_infer::traits::TraitEngineExt as _;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::subst::{InternalSubsts, Subst};
+use rustc_middle::ty::{self, ParamEnvAnd, Ty, TyCtxt};
+use rustc_span::source_map::{Span, DUMMY_SP};
+use rustc_trait_selection::traits::query::dropck_outlives::trivial_dropck_outlives;
+use rustc_trait_selection::traits::query::dropck_outlives::{
+    DropckOutlivesResult, DtorckConstraint,
+};
+use rustc_trait_selection::traits::query::normalize::AtExt;
+use rustc_trait_selection::traits::query::{CanonicalTyGoal, NoSolution};
+use rustc_trait_selection::traits::{
+    Normalized, ObligationCause, TraitEngine, TraitEngineExt as _,
+};
+
+crate fn provide(p: &mut Providers) {
+    *p = Providers { dropck_outlives, adt_dtorck_constraint, ..*p };
+}
+
+fn dropck_outlives<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    canonical_goal: CanonicalTyGoal<'tcx>,
+) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, DropckOutlivesResult<'tcx>>>, NoSolution> {
+    debug!("dropck_outlives(goal={:#?})", canonical_goal);
+
+    tcx.infer_ctxt().enter_with_canonical(
+        DUMMY_SP,
+        &canonical_goal,
+        |ref infcx, goal, canonical_inference_vars| {
+            let tcx = infcx.tcx;
+            let ParamEnvAnd { param_env, value: for_ty } = goal;
+
+            let mut result = DropckOutlivesResult { kinds: vec![], overflows: vec![] };
+
+            // A stack of types left to process. Each round, we pop
+            // something from the stack and invoke
+            // `dtorck_constraint_for_ty`. This may produce new types that
+            // have to be pushed on the stack. This continues until we have explored
+            // all the reachable types from the type `for_ty`.
+            //
+            // Example: Imagine that we have the following code:
+            //
+            // ```rust
+            // struct A {
+            //     value: B,
+            //     children: Vec<A>,
+            // }
+            //
+            // struct B {
+            //     value: u32
+            // }
+            //
+            // fn f() {
+            //   let a: A = ...;
+            //   ..
+            // } // here, `a` is dropped
+            // ```
+            //
+            // at the point where `a` is dropped, we need to figure out
+            // which types inside of `a` contain region data that may be
+            // accessed by any destructors in `a`. We begin by pushing `A`
+            // onto the stack, as that is the type of `a`. We will then
+            // invoke `dtorck_constraint_for_ty` which will expand `A`
+            // into the types of its fields `(B, Vec<A>)`. These will get
+            // pushed onto the stack. Eventually, expanding `Vec<A>` will
+            // lead to us trying to push `A` a second time -- to prevent
+            // infinite recursion, we notice that `A` was already pushed
+            // once and stop.
+            let mut ty_stack = vec![(for_ty, 0)];
+
+            // Set used to detect infinite recursion.
+            let mut ty_set = FxHashSet::default();
+
+            let mut fulfill_cx = TraitEngine::new(infcx.tcx);
+
+            let cause = ObligationCause::dummy();
+            let mut constraints = DtorckConstraint::empty();
+            while let Some((ty, depth)) = ty_stack.pop() {
+                info!(
+                    "{} kinds, {} overflows, {} ty_stack",
+                    result.kinds.len(),
+                    result.overflows.len(),
+                    ty_stack.len()
+                );
+                dtorck_constraint_for_ty(tcx, DUMMY_SP, for_ty, depth, ty, &mut constraints)?;
+
+                // "outlives" represent types/regions that may be touched
+                // by a destructor.
+                result.kinds.extend(constraints.outlives.drain(..));
+                result.overflows.extend(constraints.overflows.drain(..));
+
+                // If we have even one overflow, we should stop trying to evaluate further --
+                // chances are, the subsequent overflows for this evaluation won't provide useful
+                // information and will just decrease the speed at which we can emit these errors
+                // (since we'll be printing for just that much longer for the often enormous types
+                // that result here).
+                if !result.overflows.is_empty() {
+                    break;
+                }
+
+                // dtorck types are "types that will get dropped but which
+                // do not themselves define a destructor", more or less. We have
+                // to push them onto the stack to be expanded.
+                for ty in constraints.dtorck_types.drain(..) {
+                    match infcx.at(&cause, param_env).normalize(&ty) {
+                        Ok(Normalized { value: ty, obligations }) => {
+                            fulfill_cx.register_predicate_obligations(infcx, obligations);
+
+                            debug!("dropck_outlives: ty from dtorck_types = {:?}", ty);
+
+                            match ty.kind {
+                                // All parameters live for the duration of the
+                                // function.
+                                ty::Param(..) => {}
+
+                                // A projection that we couldn't resolve - it
+                                // might have a destructor.
+                                ty::Projection(..) | ty::Opaque(..) => {
+                                    result.kinds.push(ty.into());
+                                }
+
+                                _ => {
+                                    if ty_set.insert(ty) {
+                                        ty_stack.push((ty, depth + 1));
+                                    }
+                                }
+                            }
+                        }
+
+                        // We don't actually expect to fail to normalize.
+                        // That implies a WF error somewhere else.
+                        Err(NoSolution) => {
+                            return Err(NoSolution);
+                        }
+                    }
+                }
+            }
+
+            debug!("dropck_outlives: result = {:#?}", result);
+
+            infcx.make_canonicalized_query_response(
+                canonical_inference_vars,
+                result,
+                &mut *fulfill_cx,
+            )
+        },
+    )
+}
+
+/// Returns a set of constraints that needs to be satisfied in
+/// order for `ty` to be valid for destruction.
+fn dtorck_constraint_for_ty<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    span: Span,
+    for_ty: Ty<'tcx>,
+    depth: usize,
+    ty: Ty<'tcx>,
+    constraints: &mut DtorckConstraint<'tcx>,
+) -> Result<(), NoSolution> {
+    debug!("dtorck_constraint_for_ty({:?}, {:?}, {:?}, {:?})", span, for_ty, depth, ty);
+
+    if !tcx.sess.recursion_limit().value_within_limit(depth) {
+        constraints.overflows.push(ty);
+        return Ok(());
+    }
+
+    if trivial_dropck_outlives(tcx, ty) {
+        return Ok(());
+    }
+
+    match ty.kind {
+        ty::Bool
+        | ty::Char
+        | ty::Int(_)
+        | ty::Uint(_)
+        | ty::Float(_)
+        | ty::Str
+        | ty::Never
+        | ty::Foreign(..)
+        | ty::RawPtr(..)
+        | ty::Ref(..)
+        | ty::FnDef(..)
+        | ty::FnPtr(_)
+        | ty::GeneratorWitness(..) => {
+            // these types never have a destructor
+        }
+
+        ty::Array(ety, _) | ty::Slice(ety) => {
+            // single-element containers, behave like their element
+            rustc_data_structures::stack::ensure_sufficient_stack(|| {
+                dtorck_constraint_for_ty(tcx, span, for_ty, depth + 1, ety, constraints)
+            })?;
+        }
+
+        ty::Tuple(tys) => rustc_data_structures::stack::ensure_sufficient_stack(|| {
+            for ty in tys.iter() {
+                dtorck_constraint_for_ty(
+                    tcx,
+                    span,
+                    for_ty,
+                    depth + 1,
+                    ty.expect_ty(),
+                    constraints,
+                )?;
+            }
+            Ok::<_, NoSolution>(())
+        })?,
+
+        ty::Closure(_, substs) => rustc_data_structures::stack::ensure_sufficient_stack(|| {
+            for ty in substs.as_closure().upvar_tys() {
+                dtorck_constraint_for_ty(tcx, span, for_ty, depth + 1, ty, constraints)?;
+            }
+            Ok::<_, NoSolution>(())
+        })?,
+
+        ty::Generator(_, substs, _movability) => {
+            // rust-lang/rust#49918: types can be constructed, stored
+            // in the interior, and sit idle when generator yields
+            // (and is subsequently dropped).
+            //
+            // It would be nice to descend into interior of a
+            // generator to determine what effects dropping it might
+            // have (by looking at any drop effects associated with
+            // its interior).
+            //
+            // However, the interior's representation uses things like
+            // GeneratorWitness that explicitly assume they are not
+            // traversed in such a manner. So instead, we will
+            // simplify things for now by treating all generators as
+            // if they were like trait objects, where its upvars must
+            // all be alive for the generator's (potential)
+            // destructor.
+            //
+            // In particular, skipping over `_interior` is safe
+            // because any side-effects from dropping `_interior` can
+            // only take place through references with lifetimes
+            // derived from lifetimes attached to the upvars and resume
+            // argument, and we *do* incorporate those here.
+
+            constraints.outlives.extend(
+                substs
+                    .as_generator()
+                    .upvar_tys()
+                    .map(|t| -> ty::subst::GenericArg<'tcx> { t.into() }),
+            );
+            constraints.outlives.push(substs.as_generator().resume_ty().into());
+        }
+
+        ty::Adt(def, substs) => {
+            let DtorckConstraint { dtorck_types, outlives, overflows } =
+                tcx.at(span).adt_dtorck_constraint(def.did)?;
+            // FIXME: we can try to recursively `dtorck_constraint_on_ty`
+            // there, but that needs some way to handle cycles.
+            constraints.dtorck_types.extend(dtorck_types.subst(tcx, substs));
+            constraints.outlives.extend(outlives.subst(tcx, substs));
+            constraints.overflows.extend(overflows.subst(tcx, substs));
+        }
+
+        // Objects must be alive in order for their destructor
+        // to be called.
+        ty::Dynamic(..) => {
+            constraints.outlives.push(ty.into());
+        }
+
+        // Types that can't be resolved. Pass them forward.
+        ty::Projection(..) | ty::Opaque(..) | ty::Param(..) => {
+            constraints.dtorck_types.push(ty);
+        }
+
+        ty::Placeholder(..) | ty::Bound(..) | ty::Infer(..) | ty::Error(_) => {
+            // By the time this code runs, all type variables ought to
+            // be fully resolved.
+            return Err(NoSolution);
+        }
+    }
+
+    Ok(())
+}
+
+/// Calculates the dtorck constraint for a type.
+crate fn adt_dtorck_constraint(
+    tcx: TyCtxt<'_>,
+    def_id: DefId,
+) -> Result<DtorckConstraint<'_>, NoSolution> {
+    let def = tcx.adt_def(def_id);
+    let span = tcx.def_span(def_id);
+    debug!("dtorck_constraint: {:?}", def);
+
+    if def.is_phantom_data() {
+        // The first generic parameter here is guaranteed to be a type because it's
+        // `PhantomData`.
+        let substs = InternalSubsts::identity_for_item(tcx, def_id);
+        assert_eq!(substs.len(), 1);
+        let result = DtorckConstraint {
+            outlives: vec![],
+            dtorck_types: vec![substs.type_at(0)],
+            overflows: vec![],
+        };
+        debug!("dtorck_constraint: {:?} => {:?}", def, result);
+        return Ok(result);
+    }
+
+    let mut result = DtorckConstraint::empty();
+    for field in def.all_fields() {
+        let fty = tcx.type_of(field.did);
+        dtorck_constraint_for_ty(tcx, span, fty, 0, fty, &mut result)?;
+    }
+    result.outlives.extend(tcx.destructor_constraints(def));
+    dedup_dtorck_constraint(&mut result);
+
+    debug!("dtorck_constraint: {:?} => {:?}", def, result);
+
+    Ok(result)
+}
+
+fn dedup_dtorck_constraint(c: &mut DtorckConstraint<'_>) {
+    let mut outlives = FxHashSet::default();
+    let mut dtorck_types = FxHashSet::default();
+
+    c.outlives.retain(|&val| outlives.replace(val).is_none());
+    c.dtorck_types.retain(|&val| dtorck_types.replace(val).is_none());
+}
diff --git a/compiler/rustc_traits/src/evaluate_obligation.rs b/compiler/rustc_traits/src/evaluate_obligation.rs
new file mode 100644
index 00000000000..2404b7ff4b5
--- /dev/null
+++ b/compiler/rustc_traits/src/evaluate_obligation.rs
@@ -0,0 +1,32 @@
+use rustc_infer::infer::TyCtxtInferExt;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::{ParamEnvAnd, TyCtxt};
+use rustc_span::source_map::DUMMY_SP;
+use rustc_trait_selection::traits::query::CanonicalPredicateGoal;
+use rustc_trait_selection::traits::{
+    EvaluationResult, Obligation, ObligationCause, OverflowError, SelectionContext, TraitQueryMode,
+};
+
+crate fn provide(p: &mut Providers) {
+    *p = Providers { evaluate_obligation, ..*p };
+}
+
+fn evaluate_obligation<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    canonical_goal: CanonicalPredicateGoal<'tcx>,
+) -> Result<EvaluationResult, OverflowError> {
+    debug!("evaluate_obligation(canonical_goal={:#?})", canonical_goal);
+    tcx.infer_ctxt().enter_with_canonical(
+        DUMMY_SP,
+        &canonical_goal,
+        |ref infcx, goal, _canonical_inference_vars| {
+            debug!("evaluate_obligation: goal={:#?}", goal);
+            let ParamEnvAnd { param_env, value: predicate } = goal;
+
+            let mut selcx = SelectionContext::with_query_mode(&infcx, TraitQueryMode::Canonical);
+            let obligation = Obligation::new(ObligationCause::dummy(), param_env, predicate);
+
+            selcx.evaluate_root_obligation(&obligation)
+        },
+    )
+}
diff --git a/compiler/rustc_traits/src/implied_outlives_bounds.rs b/compiler/rustc_traits/src/implied_outlives_bounds.rs
new file mode 100644
index 00000000000..de3096eac9b
--- /dev/null
+++ b/compiler/rustc_traits/src/implied_outlives_bounds.rs
@@ -0,0 +1,166 @@
+//! Provider for the `implied_outlives_bounds` query.
+//! Do not call this query directory. See
+//! [`rustc_trait_selection::traits::query::type_op::implied_outlives_bounds`].
+
+use rustc_hir as hir;
+use rustc_infer::infer::canonical::{self, Canonical};
+use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
+use rustc_infer::traits::TraitEngineExt as _;
+use rustc_middle::ty::outlives::Component;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
+use rustc_span::source_map::DUMMY_SP;
+use rustc_trait_selection::infer::InferCtxtBuilderExt;
+use rustc_trait_selection::traits::query::outlives_bounds::OutlivesBound;
+use rustc_trait_selection::traits::query::{CanonicalTyGoal, Fallible, NoSolution};
+use rustc_trait_selection::traits::wf;
+use rustc_trait_selection::traits::FulfillmentContext;
+use rustc_trait_selection::traits::TraitEngine;
+use smallvec::{smallvec, SmallVec};
+
+crate fn provide(p: &mut Providers) {
+    *p = Providers { implied_outlives_bounds, ..*p };
+}
+
+fn implied_outlives_bounds<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    goal: CanonicalTyGoal<'tcx>,
+) -> Result<
+    &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, Vec<OutlivesBound<'tcx>>>>,
+    NoSolution,
+> {
+    tcx.infer_ctxt().enter_canonical_trait_query(&goal, |infcx, _fulfill_cx, key| {
+        let (param_env, ty) = key.into_parts();
+        compute_implied_outlives_bounds(&infcx, param_env, ty)
+    })
+}
+
+fn compute_implied_outlives_bounds<'tcx>(
+    infcx: &InferCtxt<'_, 'tcx>,
+    param_env: ty::ParamEnv<'tcx>,
+    ty: Ty<'tcx>,
+) -> Fallible<Vec<OutlivesBound<'tcx>>> {
+    let tcx = infcx.tcx;
+
+    // Sometimes when we ask what it takes for T: WF, we get back that
+    // U: WF is required; in that case, we push U onto this stack and
+    // process it next. Currently (at least) these resulting
+    // predicates are always guaranteed to be a subset of the original
+    // type, so we need not fear non-termination.
+    let mut wf_args = vec![ty.into()];
+
+    let mut implied_bounds = vec![];
+
+    let mut fulfill_cx = FulfillmentContext::new();
+
+    while let Some(arg) = wf_args.pop() {
+        // Compute the obligations for `arg` to be well-formed. If `arg` is
+        // an unresolved inference variable, just substituted an empty set
+        // -- because the return type here is going to be things we *add*
+        // to the environment, it's always ok for this set to be smaller
+        // than the ultimate set. (Note: normally there won't be
+        // unresolved inference variables here anyway, but there might be
+        // during typeck under some circumstances.)
+        let obligations =
+            wf::obligations(infcx, param_env, hir::CRATE_HIR_ID, arg, DUMMY_SP).unwrap_or(vec![]);
+
+        // N.B., all of these predicates *ought* to be easily proven
+        // true. In fact, their correctness is (mostly) implied by
+        // other parts of the program. However, in #42552, we had
+        // an annoying scenario where:
+        //
+        // - Some `T::Foo` gets normalized, resulting in a
+        //   variable `_1` and a `T: Trait<Foo=_1>` constraint
+        //   (not sure why it couldn't immediately get
+        //   solved). This result of `_1` got cached.
+        // - These obligations were dropped on the floor here,
+        //   rather than being registered.
+        // - Then later we would get a request to normalize
+        //   `T::Foo` which would result in `_1` being used from
+        //   the cache, but hence without the `T: Trait<Foo=_1>`
+        //   constraint. As a result, `_1` never gets resolved,
+        //   and we get an ICE (in dropck).
+        //
+        // Therefore, we register any predicates involving
+        // inference variables. We restrict ourselves to those
+        // involving inference variables both for efficiency and
+        // to avoids duplicate errors that otherwise show up.
+        fulfill_cx.register_predicate_obligations(
+            infcx,
+            obligations.iter().filter(|o| o.predicate.has_infer_types_or_consts()).cloned(),
+        );
+
+        // From the full set of obligations, just filter down to the
+        // region relationships.
+        implied_bounds.extend(obligations.into_iter().flat_map(|obligation| {
+            assert!(!obligation.has_escaping_bound_vars());
+            match obligation.predicate.kind() {
+                &ty::PredicateKind::ForAll(..) => vec![],
+                &ty::PredicateKind::Atom(atom) => match atom {
+                    ty::PredicateAtom::Trait(..)
+                    | ty::PredicateAtom::Subtype(..)
+                    | ty::PredicateAtom::Projection(..)
+                    | ty::PredicateAtom::ClosureKind(..)
+                    | ty::PredicateAtom::ObjectSafe(..)
+                    | ty::PredicateAtom::ConstEvaluatable(..)
+                    | ty::PredicateAtom::ConstEquate(..) => vec![],
+                    ty::PredicateAtom::WellFormed(arg) => {
+                        wf_args.push(arg);
+                        vec![]
+                    }
+
+                    ty::PredicateAtom::RegionOutlives(ty::OutlivesPredicate(r_a, r_b)) => {
+                        vec![OutlivesBound::RegionSubRegion(r_b, r_a)]
+                    }
+
+                    ty::PredicateAtom::TypeOutlives(ty::OutlivesPredicate(ty_a, r_b)) => {
+                        let ty_a = infcx.resolve_vars_if_possible(&ty_a);
+                        let mut components = smallvec![];
+                        tcx.push_outlives_components(ty_a, &mut components);
+                        implied_bounds_from_components(r_b, components)
+                    }
+                },
+            }
+        }));
+    }
+
+    // Ensure that those obligations that we had to solve
+    // get solved *here*.
+    match fulfill_cx.select_all_or_error(infcx) {
+        Ok(()) => Ok(implied_bounds),
+        Err(_) => Err(NoSolution),
+    }
+}
+
+/// When we have an implied bound that `T: 'a`, we can further break
+/// this down to determine what relationships would have to hold for
+/// `T: 'a` to hold. We get to assume that the caller has validated
+/// those relationships.
+fn implied_bounds_from_components(
+    sub_region: ty::Region<'tcx>,
+    sup_components: SmallVec<[Component<'tcx>; 4]>,
+) -> Vec<OutlivesBound<'tcx>> {
+    sup_components
+        .into_iter()
+        .filter_map(|component| {
+            match component {
+                Component::Region(r) => Some(OutlivesBound::RegionSubRegion(sub_region, r)),
+                Component::Param(p) => Some(OutlivesBound::RegionSubParam(sub_region, p)),
+                Component::Projection(p) => Some(OutlivesBound::RegionSubProjection(sub_region, p)),
+                Component::EscapingProjection(_) =>
+                // If the projection has escaping regions, don't
+                // try to infer any implied bounds even for its
+                // free components. This is conservative, because
+                // the caller will still have to prove that those
+                // free components outlive `sub_region`. But the
+                // idea is that the WAY that the caller proves
+                // that may change in the future and we want to
+                // give ourselves room to get smarter here.
+                {
+                    None
+                }
+                Component::UnresolvedInferenceVariable(..) => None,
+            }
+        })
+        .collect()
+}
diff --git a/compiler/rustc_traits/src/lib.rs b/compiler/rustc_traits/src/lib.rs
new file mode 100644
index 00000000000..6fea4732dda
--- /dev/null
+++ b/compiler/rustc_traits/src/lib.rs
@@ -0,0 +1,33 @@
+//! New recursive solver modeled on Chalk's recursive solver. Most of
+//! the guts are broken up into modules; see the comments in those modules.
+
+#![feature(crate_visibility_modifier)]
+#![feature(in_band_lifetimes)]
+#![feature(nll)]
+#![feature(or_patterns)]
+#![recursion_limit = "256"]
+
+#[macro_use]
+extern crate tracing;
+#[macro_use]
+extern crate rustc_middle;
+
+mod chalk;
+mod dropck_outlives;
+mod evaluate_obligation;
+mod implied_outlives_bounds;
+mod normalize_erasing_regions;
+mod normalize_projection_ty;
+mod type_op;
+
+use rustc_middle::ty::query::Providers;
+
+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);
+}
diff --git a/compiler/rustc_traits/src/normalize_erasing_regions.rs b/compiler/rustc_traits/src/normalize_erasing_regions.rs
new file mode 100644
index 00000000000..83aee31a39f
--- /dev/null
+++ b/compiler/rustc_traits/src/normalize_erasing_regions.rs
@@ -0,0 +1,54 @@
+use rustc_infer::infer::TyCtxtInferExt;
+use rustc_middle::traits::query::NoSolution;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::subst::GenericArg;
+use rustc_middle::ty::{self, ParamEnvAnd, TyCtxt};
+use rustc_trait_selection::traits::query::normalize::AtExt;
+use rustc_trait_selection::traits::{Normalized, ObligationCause};
+use std::sync::atomic::Ordering;
+
+crate fn provide(p: &mut Providers) {
+    *p = Providers { normalize_generic_arg_after_erasing_regions, ..*p };
+}
+
+fn normalize_generic_arg_after_erasing_regions<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    goal: ParamEnvAnd<'tcx, GenericArg<'tcx>>,
+) -> GenericArg<'tcx> {
+    debug!("normalize_generic_arg_after_erasing_regions(goal={:#?})", goal);
+
+    let ParamEnvAnd { param_env, value } = goal;
+    tcx.sess.perf_stats.normalize_generic_arg_after_erasing_regions.fetch_add(1, Ordering::Relaxed);
+    tcx.infer_ctxt().enter(|infcx| {
+        let cause = ObligationCause::dummy();
+        match infcx.at(&cause, param_env).normalize(&value) {
+            Ok(Normalized { value: normalized_value, obligations: normalized_obligations }) => {
+                // We don't care about the `obligations`; they are
+                // always only region relations, and we are about to
+                // erase those anyway:
+                debug_assert_eq!(
+                    normalized_obligations.iter().find(|p| not_outlives_predicate(&p.predicate)),
+                    None,
+                );
+
+                let normalized_value = infcx.resolve_vars_if_possible(&normalized_value);
+                infcx.tcx.erase_regions(&normalized_value)
+            }
+            Err(NoSolution) => bug!("could not fully normalize `{:?}`", value),
+        }
+    })
+}
+
+fn not_outlives_predicate(p: &ty::Predicate<'tcx>) -> bool {
+    match p.skip_binders() {
+        ty::PredicateAtom::RegionOutlives(..) | ty::PredicateAtom::TypeOutlives(..) => false,
+        ty::PredicateAtom::Trait(..)
+        | ty::PredicateAtom::Projection(..)
+        | ty::PredicateAtom::WellFormed(..)
+        | ty::PredicateAtom::ObjectSafe(..)
+        | ty::PredicateAtom::ClosureKind(..)
+        | ty::PredicateAtom::Subtype(..)
+        | ty::PredicateAtom::ConstEvaluatable(..)
+        | ty::PredicateAtom::ConstEquate(..) => true,
+    }
+}
diff --git a/compiler/rustc_traits/src/normalize_projection_ty.rs b/compiler/rustc_traits/src/normalize_projection_ty.rs
new file mode 100644
index 00000000000..a8e376838e2
--- /dev/null
+++ b/compiler/rustc_traits/src/normalize_projection_ty.rs
@@ -0,0 +1,42 @@
+use rustc_infer::infer::canonical::{Canonical, QueryResponse};
+use rustc_infer::infer::TyCtxtInferExt;
+use rustc_infer::traits::TraitEngineExt as _;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::{ParamEnvAnd, TyCtxt};
+use rustc_trait_selection::infer::InferCtxtBuilderExt;
+use rustc_trait_selection::traits::query::{
+    normalize::NormalizationResult, CanonicalProjectionGoal, NoSolution,
+};
+use rustc_trait_selection::traits::{self, ObligationCause, SelectionContext};
+use std::sync::atomic::Ordering;
+
+crate fn provide(p: &mut Providers) {
+    *p = Providers { normalize_projection_ty, ..*p };
+}
+
+fn normalize_projection_ty<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    goal: CanonicalProjectionGoal<'tcx>,
+) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution> {
+    debug!("normalize_provider(goal={:#?})", goal);
+
+    tcx.sess.perf_stats.normalize_projection_ty.fetch_add(1, Ordering::Relaxed);
+    tcx.infer_ctxt().enter_canonical_trait_query(
+        &goal,
+        |infcx, fulfill_cx, ParamEnvAnd { param_env, value: goal }| {
+            let selcx = &mut SelectionContext::new(infcx);
+            let cause = ObligationCause::dummy();
+            let mut obligations = vec![];
+            let answer = traits::normalize_projection_type(
+                selcx,
+                param_env,
+                goal,
+                cause,
+                0,
+                &mut obligations,
+            );
+            fulfill_cx.register_predicate_obligations(infcx, obligations);
+            Ok(NormalizationResult { normalized_ty: answer })
+        },
+    )
+}
diff --git a/compiler/rustc_traits/src/type_op.rs b/compiler/rustc_traits/src/type_op.rs
new file mode 100644
index 00000000000..139ed6dcd35
--- /dev/null
+++ b/compiler/rustc_traits/src/type_op.rs
@@ -0,0 +1,246 @@
+use rustc_hir as hir;
+use rustc_hir::def_id::DefId;
+use rustc_infer::infer::at::ToTrace;
+use rustc_infer::infer::canonical::{Canonical, QueryResponse};
+use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
+use rustc_infer::traits::TraitEngineExt as _;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::subst::{GenericArg, Subst, UserSelfTy, UserSubsts};
+use rustc_middle::ty::{self, FnSig, Lift, PolyFnSig, Ty, TyCtxt, TypeFoldable, Variance};
+use rustc_middle::ty::{ParamEnv, ParamEnvAnd, Predicate, ToPredicate};
+use rustc_span::DUMMY_SP;
+use rustc_trait_selection::infer::InferCtxtBuilderExt;
+use rustc_trait_selection::infer::InferCtxtExt;
+use rustc_trait_selection::traits::query::normalize::AtExt;
+use rustc_trait_selection::traits::query::type_op::ascribe_user_type::AscribeUserType;
+use rustc_trait_selection::traits::query::type_op::eq::Eq;
+use rustc_trait_selection::traits::query::type_op::normalize::Normalize;
+use rustc_trait_selection::traits::query::type_op::prove_predicate::ProvePredicate;
+use rustc_trait_selection::traits::query::type_op::subtype::Subtype;
+use rustc_trait_selection::traits::query::{Fallible, NoSolution};
+use rustc_trait_selection::traits::{Normalized, Obligation, ObligationCause, TraitEngine};
+use std::fmt;
+
+crate fn provide(p: &mut Providers) {
+    *p = Providers {
+        type_op_ascribe_user_type,
+        type_op_eq,
+        type_op_prove_predicate,
+        type_op_subtype,
+        type_op_normalize_ty,
+        type_op_normalize_predicate,
+        type_op_normalize_fn_sig,
+        type_op_normalize_poly_fn_sig,
+        ..*p
+    };
+}
+
+fn type_op_ascribe_user_type<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, AscribeUserType<'tcx>>>,
+) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, ()>>, NoSolution> {
+    tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, |infcx, fulfill_cx, key| {
+        let (param_env, AscribeUserType { mir_ty, def_id, user_substs }) = key.into_parts();
+
+        debug!(
+            "type_op_ascribe_user_type: mir_ty={:?} def_id={:?} user_substs={:?}",
+            mir_ty, def_id, user_substs
+        );
+
+        let mut cx = AscribeUserTypeCx { infcx, param_env, fulfill_cx };
+        cx.relate_mir_and_user_ty(mir_ty, def_id, user_substs)?;
+
+        Ok(())
+    })
+}
+
+struct AscribeUserTypeCx<'me, 'tcx> {
+    infcx: &'me InferCtxt<'me, 'tcx>,
+    param_env: ParamEnv<'tcx>,
+    fulfill_cx: &'me mut dyn TraitEngine<'tcx>,
+}
+
+impl AscribeUserTypeCx<'me, 'tcx> {
+    fn normalize<T>(&mut self, value: T) -> T
+    where
+        T: TypeFoldable<'tcx>,
+    {
+        self.infcx
+            .partially_normalize_associated_types_in(
+                DUMMY_SP,
+                hir::CRATE_HIR_ID,
+                self.param_env,
+                &value,
+            )
+            .into_value_registering_obligations(self.infcx, self.fulfill_cx)
+    }
+
+    fn relate<T>(&mut self, a: T, variance: Variance, b: T) -> Result<(), NoSolution>
+    where
+        T: ToTrace<'tcx>,
+    {
+        self.infcx
+            .at(&ObligationCause::dummy(), self.param_env)
+            .relate(a, variance, b)?
+            .into_value_registering_obligations(self.infcx, self.fulfill_cx);
+        Ok(())
+    }
+
+    fn prove_predicate(&mut self, predicate: Predicate<'tcx>) {
+        self.fulfill_cx.register_predicate_obligation(
+            self.infcx,
+            Obligation::new(ObligationCause::dummy(), self.param_env, predicate),
+        );
+    }
+
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        self.infcx.tcx
+    }
+
+    fn subst<T>(&self, value: T, substs: &[GenericArg<'tcx>]) -> T
+    where
+        T: TypeFoldable<'tcx>,
+    {
+        value.subst(self.tcx(), substs)
+    }
+
+    fn relate_mir_and_user_ty(
+        &mut self,
+        mir_ty: Ty<'tcx>,
+        def_id: DefId,
+        user_substs: UserSubsts<'tcx>,
+    ) -> Result<(), NoSolution> {
+        let UserSubsts { user_self_ty, substs } = user_substs;
+        let tcx = self.tcx();
+
+        let ty = tcx.type_of(def_id);
+        let ty = self.subst(ty, substs);
+        debug!("relate_type_and_user_type: ty of def-id is {:?}", ty);
+        let ty = self.normalize(ty);
+
+        self.relate(mir_ty, Variance::Invariant, ty)?;
+
+        // Prove the predicates coming along with `def_id`.
+        //
+        // Also, normalize the `instantiated_predicates`
+        // because otherwise we wind up with duplicate "type
+        // outlives" error messages.
+        let instantiated_predicates =
+            self.tcx().predicates_of(def_id).instantiate(self.tcx(), substs);
+        for instantiated_predicate in instantiated_predicates.predicates {
+            let instantiated_predicate = self.normalize(instantiated_predicate);
+            self.prove_predicate(instantiated_predicate);
+        }
+
+        if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty {
+            let impl_self_ty = self.tcx().type_of(impl_def_id);
+            let impl_self_ty = self.subst(impl_self_ty, &substs);
+            let impl_self_ty = self.normalize(impl_self_ty);
+
+            self.relate(self_ty, Variance::Invariant, impl_self_ty)?;
+
+            self.prove_predicate(
+                ty::PredicateAtom::WellFormed(impl_self_ty.into()).to_predicate(self.tcx()),
+            );
+        }
+
+        // In addition to proving the predicates, we have to
+        // prove that `ty` is well-formed -- this is because
+        // the WF of `ty` is predicated on the substs being
+        // well-formed, and we haven't proven *that*. We don't
+        // want to prove the WF of types from  `substs` directly because they
+        // haven't been normalized.
+        //
+        // FIXME(nmatsakis): Well, perhaps we should normalize
+        // them?  This would only be relevant if some input
+        // type were ill-formed but did not appear in `ty`,
+        // which...could happen with normalization...
+        self.prove_predicate(ty::PredicateAtom::WellFormed(ty.into()).to_predicate(self.tcx()));
+        Ok(())
+    }
+}
+
+fn type_op_eq<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Eq<'tcx>>>,
+) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, ()>>, NoSolution> {
+    tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, |infcx, fulfill_cx, key| {
+        let (param_env, Eq { a, b }) = key.into_parts();
+        infcx
+            .at(&ObligationCause::dummy(), param_env)
+            .eq(a, b)?
+            .into_value_registering_obligations(infcx, fulfill_cx);
+        Ok(())
+    })
+}
+
+fn type_op_normalize<T>(
+    infcx: &InferCtxt<'_, 'tcx>,
+    fulfill_cx: &mut dyn TraitEngine<'tcx>,
+    key: ParamEnvAnd<'tcx, Normalize<T>>,
+) -> Fallible<T>
+where
+    T: fmt::Debug + TypeFoldable<'tcx> + Lift<'tcx>,
+{
+    let (param_env, Normalize { value }) = key.into_parts();
+    let Normalized { value, obligations } =
+        infcx.at(&ObligationCause::dummy(), param_env).normalize(&value)?;
+    fulfill_cx.register_predicate_obligations(infcx, obligations);
+    Ok(value)
+}
+
+fn type_op_normalize_ty(
+    tcx: TyCtxt<'tcx>,
+    canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Normalize<Ty<'tcx>>>>,
+) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>, NoSolution> {
+    tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, type_op_normalize)
+}
+
+fn type_op_normalize_predicate(
+    tcx: TyCtxt<'tcx>,
+    canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Normalize<Predicate<'tcx>>>>,
+) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, Predicate<'tcx>>>, NoSolution> {
+    tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, type_op_normalize)
+}
+
+fn type_op_normalize_fn_sig(
+    tcx: TyCtxt<'tcx>,
+    canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Normalize<FnSig<'tcx>>>>,
+) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, FnSig<'tcx>>>, NoSolution> {
+    tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, type_op_normalize)
+}
+
+fn type_op_normalize_poly_fn_sig(
+    tcx: TyCtxt<'tcx>,
+    canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Normalize<PolyFnSig<'tcx>>>>,
+) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, PolyFnSig<'tcx>>>, NoSolution> {
+    tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, type_op_normalize)
+}
+
+fn type_op_subtype<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Subtype<'tcx>>>,
+) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, ()>>, NoSolution> {
+    tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, |infcx, fulfill_cx, key| {
+        let (param_env, Subtype { sub, sup }) = key.into_parts();
+        infcx
+            .at(&ObligationCause::dummy(), param_env)
+            .sup(sup, sub)?
+            .into_value_registering_obligations(infcx, fulfill_cx);
+        Ok(())
+    })
+}
+
+fn type_op_prove_predicate<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, ProvePredicate<'tcx>>>,
+) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, ()>>, NoSolution> {
+    tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, |infcx, fulfill_cx, key| {
+        let (param_env, ProvePredicate { predicate }) = key.into_parts();
+        fulfill_cx.register_predicate_obligation(
+            infcx,
+            Obligation::new(ObligationCause::dummy(), param_env, predicate),
+        );
+        Ok(())
+    })
+}