2 files changed, 145 insertions, 141 deletions

diff --git a/crates/hir_ty/src/traits/chalk.rs b/crates/hir_ty/src/traits/chalk.rs
index bef6e7e9c..4019fdf17 100644
--- a/crates/hir_ty/src/traits/chalk.rs
+++ b/crates/hir_ty/src/traits/chalk.rs
@@ -19,10 +19,10 @@ use crate::{
     display::HirDisplay,
     from_assoc_type_id,
     method_resolution::{TyFingerprint, ALL_FLOAT_FPS, ALL_INT_FPS},
-    to_assoc_type_id,
+    to_assoc_type_id, to_chalk_trait_id,
     utils::generics,
-    BoundVar, CallableDefId, CallableSig, DebruijnIndex, FnDefId, GenericPredicate,
-    ProjectionPredicate, ProjectionTy, Substitution, TraitRef, Ty, TyKind,
+    AliasEq, AliasTy, BoundVar, CallableDefId, CallableSig, DebruijnIndex, FnDefId, ProjectionTy,
+    Substitution, TraitRef, Ty, TyKind, WhereClause,
 };
 use mapping::{
     convert_where_clauses, generic_predicate_to_inline_bound, make_binders, TypeAliasAsValue,
@@ -187,13 +187,7 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
                 let data = &datas.value.impl_traits[idx as usize];
                 let bound = OpaqueTyDatumBound {
                     bounds: make_binders(
-                        data.bounds
-                            .value
-                            .iter()
-                            .cloned()
-                            .filter(|b| !b.is_error())
-                            .map(|b| b.to_chalk(self.db))
-                            .collect(),
+                        data.bounds.value.iter().cloned().map(|b| b.to_chalk(self.db)).collect(),
                         1,
                     ),
                     where_clauses: make_binders(vec![], 0),
@@ -218,10 +212,10 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
                     //        |-------------OpaqueTyDatumBound--------------|
                     // for<T> <Self> [Future<Self>, Future::Output<Self> = T]
                     //     ^1  ^0            ^0                    ^0      ^1
-                    let impl_bound = GenericPredicate::Implemented(TraitRef {
-                        trait_: future_trait,
+                    let impl_bound = WhereClause::Implemented(TraitRef {
+                        trait_id: to_chalk_trait_id(future_trait),
                         // Self type as the first parameter.
-                        substs: Substitution::single(
+                        substitution: Substitution::single(
                             TyKind::BoundVar(BoundVar {
                                 debruijn: DebruijnIndex::INNERMOST,
                                 index: 0,
@@ -229,22 +223,25 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
                             .intern(&Interner),
                         ),
                     });
-                    let proj_bound = GenericPredicate::Projection(ProjectionPredicate {
-                        // The parameter of the opaque type.
-                        ty: TyKind::BoundVar(BoundVar { debruijn: DebruijnIndex::ONE, index: 0 })
-                            .intern(&Interner),
-                        projection_ty: ProjectionTy {
+                    let proj_bound = WhereClause::AliasEq(AliasEq {
+                        alias: AliasTy::Projection(ProjectionTy {
                             associated_ty_id: to_assoc_type_id(future_output),
                             // Self type as the first parameter.
                             substitution: Substitution::single(
                                 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0))
                                     .intern(&Interner),
                             ),
-                        },
+                        }),
+                        // The parameter of the opaque type.
+                        ty: TyKind::BoundVar(BoundVar { debruijn: DebruijnIndex::ONE, index: 0 })
+                            .intern(&Interner),
                     });
                     let bound = OpaqueTyDatumBound {
                         bounds: make_binders(
-                            vec![impl_bound.to_chalk(self.db), proj_bound.to_chalk(self.db)],
+                            vec![
+                                wrap_in_empty_binders(impl_bound).to_chalk(self.db),
+                                wrap_in_empty_binders(proj_bound).to_chalk(self.db),
+                            ],
                             1,
                         ),
                         where_clauses: make_binders(vec![], 0),
@@ -401,9 +398,8 @@ pub(crate) fn associated_ty_data_query(
     let bounds = type_alias_data
         .bounds
         .iter()
-        .flat_map(|bound| ctx.lower_type_bound(bound, self_ty.clone()))
+        .flat_map(|bound| ctx.lower_type_bound(bound, self_ty.clone(), false))
         .filter_map(|pred| generic_predicate_to_inline_bound(db, &pred, &self_ty))
-        .map(|bound| make_binders(bound.shifted_in(&Interner), 0))
         .collect();
 
     let where_clauses = convert_where_clauses(db, type_alias.into(), &bound_vars);
@@ -546,7 +542,7 @@ fn impl_def_datum(
 
     let generic_params = generics(db.upcast(), impl_id.into());
     let bound_vars = Substitution::bound_vars(&generic_params, DebruijnIndex::INNERMOST);
-    let trait_ = trait_ref.trait_;
+    let trait_ = trait_ref.hir_trait_id();
     let impl_type = if impl_id.lookup(db.upcast()).container.krate() == krate {
         rust_ir::ImplType::Local
     } else {
@@ -614,7 +610,7 @@ fn type_alias_associated_ty_value(
     let trait_ref = db.impl_trait(impl_id).expect("assoc ty value should not exist").value; // we don't return any assoc ty values if the impl'd trait can't be resolved
 
     let assoc_ty = db
-        .trait_data(trait_ref.trait_)
+        .trait_data(trait_ref.hir_trait_id())
         .associated_type_by_name(&type_alias_data.name)
         .expect("assoc ty value should not exist"); // validated when building the impl data as well
     let ty = db.ty(type_alias.into());
@@ -726,3 +722,7 @@ impl From<crate::db::InternedClosureId> for chalk_ir::ClosureId<Interner> {
         chalk_ir::ClosureId(id.as_intern_id())
     }
 }
+
+fn wrap_in_empty_binders<T: crate::TypeWalk>(value: T) -> crate::Binders<T> {
+    crate::Binders::wrap_empty(value)
+}
diff --git a/crates/hir_ty/src/traits/chalk/mapping.rs b/crates/hir_ty/src/traits/chalk/mapping.rs
index d969527dc..aef6b8a15 100644
--- a/crates/hir_ty/src/traits/chalk/mapping.rs
+++ b/crates/hir_ty/src/traits/chalk/mapping.rs
@@ -7,15 +7,14 @@ use chalk_ir::{cast::Cast, fold::shift::Shift, interner::HasInterner, LifetimeDa
 use chalk_solve::rust_ir;
 
 use base_db::salsa::InternKey;
-use hir_def::{AssocContainerId, GenericDefId, Lookup, TypeAliasId};
+use hir_def::{GenericDefId, TypeAliasId};
 
 use crate::{
     db::HirDatabase,
-    from_assoc_type_id,
     primitive::UintTy,
-    traits::{Canonical, Obligation},
-    AliasTy, CallableDefId, FnPointer, GenericPredicate, InEnvironment, OpaqueTy,
-    ProjectionPredicate, ProjectionTy, Scalar, Substitution, TraitRef, Ty,
+    traits::{Canonical, DomainGoal},
+    AliasTy, CallableDefId, FnPointer, InEnvironment, OpaqueTy, ProjectionTy,
+    QuantifiedWhereClause, Scalar, Substitution, TraitRef, Ty, TypeWalk, WhereClause,
 };
 
 use super::interner::*;
@@ -95,10 +94,10 @@ impl ToChalk for Ty {
             TyKind::Placeholder(idx) => idx.to_ty::<Interner>(&Interner),
             TyKind::BoundVar(idx) => chalk_ir::TyKind::BoundVar(idx).intern(&Interner),
             TyKind::InferenceVar(..) => panic!("uncanonicalized infer ty"),
-            TyKind::Dyn(predicates) => {
+            TyKind::Dyn(dyn_ty) => {
                 let where_clauses = chalk_ir::QuantifiedWhereClauses::from_iter(
                     &Interner,
-                    predicates.iter().filter(|p| !p.is_error()).cloned().map(|p| p.to_chalk(db)),
+                    dyn_ty.bounds.value.interned().iter().cloned().map(|p| p.to_chalk(db)),
                 );
                 let bounded_ty = chalk_ir::DynTy {
                     bounds: make_binders(where_clauses, 1),
@@ -144,13 +143,17 @@ impl ToChalk for Ty {
             chalk_ir::TyKind::InferenceVar(_iv, _kind) => TyKind::Unknown,
             chalk_ir::TyKind::Dyn(where_clauses) => {
                 assert_eq!(where_clauses.bounds.binders.len(&Interner), 1);
-                let predicates = where_clauses
+                let bounds = where_clauses
                     .bounds
                     .skip_binders()
                     .iter(&Interner)
-                    .map(|c| from_chalk(db, c.clone()))
-                    .collect();
-                TyKind::Dyn(predicates)
+                    .map(|c| from_chalk(db, c.clone()));
+                TyKind::Dyn(crate::DynTy {
+                    bounds: crate::Binders::new(
+                        1,
+                        crate::QuantifiedWhereClauses::from_iter(&Interner, bounds),
+                    ),
+                })
             }
 
             chalk_ir::TyKind::Adt(adt_id, subst) => TyKind::Adt(adt_id, from_chalk(db, subst)),
@@ -239,15 +242,15 @@ impl ToChalk for TraitRef {
     type Chalk = chalk_ir::TraitRef<Interner>;
 
     fn to_chalk(self: TraitRef, db: &dyn HirDatabase) -> chalk_ir::TraitRef<Interner> {
-        let trait_id = self.trait_.to_chalk(db);
-        let substitution = self.substs.to_chalk(db);
+        let trait_id = self.trait_id;
+        let substitution = self.substitution.to_chalk(db);
         chalk_ir::TraitRef { trait_id, substitution }
     }
 
     fn from_chalk(db: &dyn HirDatabase, trait_ref: chalk_ir::TraitRef<Interner>) -> Self {
-        let trait_ = from_chalk(db, trait_ref.trait_id);
+        let trait_id = trait_ref.trait_id;
         let substs = from_chalk(db, trait_ref.substitution);
-        TraitRef { trait_, substs }
+        TraitRef { trait_id, substitution: substs }
     }
 }
 
@@ -304,50 +307,26 @@ impl ToChalk for TypeAliasAsValue {
     }
 }
 
-impl ToChalk for GenericPredicate {
-    type Chalk = chalk_ir::QuantifiedWhereClause<Interner>;
+impl ToChalk for WhereClause {
+    type Chalk = chalk_ir::WhereClause<Interner>;
 
-    fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::QuantifiedWhereClause<Interner> {
+    fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::WhereClause<Interner> {
         match self {
-            GenericPredicate::Implemented(trait_ref) => {
-                let chalk_trait_ref = trait_ref.to_chalk(db);
-                let chalk_trait_ref = chalk_trait_ref.shifted_in(&Interner);
-                make_binders(chalk_ir::WhereClause::Implemented(chalk_trait_ref), 0)
-            }
-            GenericPredicate::Projection(projection_pred) => {
-                let ty = projection_pred.ty.to_chalk(db).shifted_in(&Interner);
-                let projection = projection_pred.projection_ty.to_chalk(db).shifted_in(&Interner);
-                let alias = chalk_ir::AliasTy::Projection(projection);
-                make_binders(chalk_ir::WhereClause::AliasEq(chalk_ir::AliasEq { alias, ty }), 0)
+            WhereClause::Implemented(trait_ref) => {
+                chalk_ir::WhereClause::Implemented(trait_ref.to_chalk(db))
             }
-            GenericPredicate::Error => panic!("tried passing GenericPredicate::Error to Chalk"),
+            WhereClause::AliasEq(alias_eq) => chalk_ir::WhereClause::AliasEq(alias_eq.to_chalk(db)),
         }
     }
 
     fn from_chalk(
         db: &dyn HirDatabase,
-        where_clause: chalk_ir::QuantifiedWhereClause<Interner>,
-    ) -> GenericPredicate {
-        // we don't produce any where clauses with binders and can't currently deal with them
-        match where_clause
-            .skip_binders()
-            .clone()
-            .shifted_out(&Interner)
-            .expect("unexpected bound vars in where clause")
-        {
-            chalk_ir::WhereClause::Implemented(tr) => {
-                GenericPredicate::Implemented(from_chalk(db, tr))
-            }
-            chalk_ir::WhereClause::AliasEq(projection_eq) => {
-                let projection_ty = from_chalk(
-                    db,
-                    match projection_eq.alias {
-                        chalk_ir::AliasTy::Projection(p) => p,
-                        _ => unimplemented!(),
-                    },
-                );
-                let ty = from_chalk(db, projection_eq.ty);
-                GenericPredicate::Projection(ProjectionPredicate { projection_ty, ty })
+        where_clause: chalk_ir::WhereClause<Interner>,
+    ) -> WhereClause {
+        match where_clause {
+            chalk_ir::WhereClause::Implemented(tr) => WhereClause::Implemented(from_chalk(db, tr)),
+            chalk_ir::WhereClause::AliasEq(alias_eq) => {
+                WhereClause::AliasEq(from_chalk(db, alias_eq))
             }
 
             chalk_ir::WhereClause::LifetimeOutlives(_) => {
@@ -383,29 +362,67 @@ impl ToChalk for ProjectionTy {
         }
     }
 }
+impl ToChalk for OpaqueTy {
+    type Chalk = chalk_ir::OpaqueTy<Interner>;
+
+    fn to_chalk(self, db: &dyn HirDatabase) -> Self::Chalk {
+        chalk_ir::OpaqueTy {
+            opaque_ty_id: self.opaque_ty_id,
+            substitution: self.substitution.to_chalk(db),
+        }
+    }
+
+    fn from_chalk(db: &dyn HirDatabase, chalk: Self::Chalk) -> Self {
+        OpaqueTy {
+            opaque_ty_id: chalk.opaque_ty_id,
+            substitution: from_chalk(db, chalk.substitution),
+        }
+    }
+}
+
+impl ToChalk for AliasTy {
+    type Chalk = chalk_ir::AliasTy<Interner>;
+
+    fn to_chalk(self, db: &dyn HirDatabase) -> Self::Chalk {
+        match self {
+            AliasTy::Projection(projection_ty) => {
+                chalk_ir::AliasTy::Projection(projection_ty.to_chalk(db))
+            }
+            AliasTy::Opaque(opaque_ty) => chalk_ir::AliasTy::Opaque(opaque_ty.to_chalk(db)),
+        }
+    }
+
+    fn from_chalk(db: &dyn HirDatabase, chalk: Self::Chalk) -> Self {
+        match chalk {
+            chalk_ir::AliasTy::Projection(projection_ty) => {
+                AliasTy::Projection(from_chalk(db, projection_ty))
+            }
+            chalk_ir::AliasTy::Opaque(opaque_ty) => AliasTy::Opaque(from_chalk(db, opaque_ty)),
+        }
+    }
+}
 
-impl ToChalk for ProjectionPredicate {
+impl ToChalk for AliasEq {
     type Chalk = chalk_ir::AliasEq<Interner>;
 
     fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::AliasEq<Interner> {
-        chalk_ir::AliasEq {
-            alias: chalk_ir::AliasTy::Projection(self.projection_ty.to_chalk(db)),
-            ty: self.ty.to_chalk(db),
-        }
+        chalk_ir::AliasEq { alias: self.alias.to_chalk(db), ty: self.ty.to_chalk(db) }
     }
 
-    fn from_chalk(_db: &dyn HirDatabase, _normalize: chalk_ir::AliasEq<Interner>) -> Self {
-        unimplemented!()
+    fn from_chalk(db: &dyn HirDatabase, alias_eq: chalk_ir::AliasEq<Interner>) -> Self {
+        AliasEq { alias: from_chalk(db, alias_eq.alias), ty: from_chalk(db, alias_eq.ty) }
     }
 }
 
-impl ToChalk for Obligation {
+impl ToChalk for DomainGoal {
     type Chalk = chalk_ir::DomainGoal<Interner>;
 
     fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::DomainGoal<Interner> {
         match self {
-            Obligation::Trait(tr) => tr.to_chalk(db).cast(&Interner),
-            Obligation::Projection(pr) => pr.to_chalk(db).cast(&Interner),
+            DomainGoal::Holds(WhereClause::Implemented(tr)) => tr.to_chalk(db).cast(&Interner),
+            DomainGoal::Holds(WhereClause::AliasEq(alias_eq)) => {
+                alias_eq.to_chalk(db).cast(&Interner)
+            }
         }
     }
 
@@ -422,35 +439,12 @@ where
     type Chalk = chalk_ir::Canonical<T::Chalk>;
 
     fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::Canonical<T::Chalk> {
-        let kinds = self.kinds.iter().map(|&tk| {
-            chalk_ir::CanonicalVarKind::new(
-                chalk_ir::VariableKind::Ty(tk),
-                chalk_ir::UniverseIndex::ROOT,
-            )
-        });
         let value = self.value.to_chalk(db);
-        chalk_ir::Canonical {
-            value,
-            binders: chalk_ir::CanonicalVarKinds::from_iter(&Interner, kinds),
-        }
+        chalk_ir::Canonical { value, binders: self.binders }
     }
 
     fn from_chalk(db: &dyn HirDatabase, canonical: chalk_ir::Canonical<T::Chalk>) -> Canonical<T> {
-        let kinds = canonical
-            .binders
-            .iter(&Interner)
-            .map(|k| match k.kind {
-                chalk_ir::VariableKind::Ty(tk) => tk,
-                // HACK: Chalk can sometimes return new lifetime variables. We
-                // want to just skip them, but to not mess up the indices of
-                // other variables, we'll just create a new type variable in
-                // their place instead. This should not matter (we never see the
-                // actual *uses* of the lifetime variable).
-                chalk_ir::VariableKind::Lifetime => chalk_ir::TyVariableKind::General,
-                chalk_ir::VariableKind::Const(_) => panic!("unexpected const from Chalk"),
-            })
-            .collect();
-        Canonical { kinds, value: from_chalk(db, canonical.value) }
+        Canonical { binders: canonical.binders, value: from_chalk(db, canonical.value) }
     }
 }
 
@@ -461,10 +455,7 @@ where
     type Chalk = chalk_ir::InEnvironment<T::Chalk>;
 
     fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::InEnvironment<T::Chalk> {
-        chalk_ir::InEnvironment {
-            environment: self.environment.env.clone(),
-            goal: self.value.to_chalk(db),
-        }
+        chalk_ir::InEnvironment { environment: self.environment, goal: self.goal.to_chalk(db) }
     }
 
     fn from_chalk(
@@ -475,6 +466,29 @@ where
     }
 }
 
+impl<T: ToChalk> ToChalk for crate::Binders<T>
+where
+    T::Chalk: chalk_ir::interner::HasInterner<Interner = Interner>,
+{
+    type Chalk = chalk_ir::Binders<T::Chalk>;
+
+    fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::Binders<T::Chalk> {
+        chalk_ir::Binders::new(
+            chalk_ir::VariableKinds::from_iter(
+                &Interner,
+                std::iter::repeat(chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General))
+                    .take(self.num_binders),
+            ),
+            self.value.to_chalk(db),
+        )
+    }
+
+    fn from_chalk(db: &dyn HirDatabase, binders: chalk_ir::Binders<T::Chalk>) -> crate::Binders<T> {
+        let (v, b) = binders.into_value_and_skipped_binders();
+        crate::Binders::new(b.len(&Interner), from_chalk(db, v))
+    }
+}
+
 pub(super) fn make_binders<T>(value: T, num_vars: usize) -> chalk_ir::Binders<T>
 where
     T: HasInterner<Interner = Interner>,
@@ -497,10 +511,6 @@ pub(super) fn convert_where_clauses(
     let generic_predicates = db.generic_predicates(def);
     let mut result = Vec::with_capacity(generic_predicates.len());
     for pred in generic_predicates.iter() {
-        if pred.value.is_error() {
-            // skip errored predicates completely
-            continue;
-        }
         result.push(pred.clone().subst(substs).to_chalk(db));
     }
     result
@@ -508,49 +518,43 @@ pub(super) fn convert_where_clauses(
 
 pub(super) fn generic_predicate_to_inline_bound(
     db: &dyn HirDatabase,
-    pred: &GenericPredicate,
+    pred: &QuantifiedWhereClause,
     self_ty: &Ty,
-) -> Option<rust_ir::InlineBound<Interner>> {
+) -> Option<chalk_ir::Binders<rust_ir::InlineBound<Interner>>> {
     // An InlineBound is like a GenericPredicate, except the self type is left out.
     // We don't have a special type for this, but Chalk does.
-    match pred {
-        GenericPredicate::Implemented(trait_ref) => {
-            if &trait_ref.substs[0] != self_ty {
+    let self_ty_shifted_in = self_ty.clone().shift_bound_vars(DebruijnIndex::ONE);
+    match &pred.value {
+        WhereClause::Implemented(trait_ref) => {
+            if trait_ref.self_type_parameter() != &self_ty_shifted_in {
                 // we can only convert predicates back to type bounds if they
                 // have the expected self type
                 return None;
             }
-            let args_no_self = trait_ref.substs[1..]
+            let args_no_self = trait_ref.substitution[1..]
                 .iter()
                 .map(|ty| ty.clone().to_chalk(db).cast(&Interner))
                 .collect();
-            let trait_bound =
-                rust_ir::TraitBound { trait_id: trait_ref.trait_.to_chalk(db), args_no_self };
-            Some(rust_ir::InlineBound::TraitBound(trait_bound))
+            let trait_bound = rust_ir::TraitBound { trait_id: trait_ref.trait_id, args_no_self };
+            Some(make_binders(rust_ir::InlineBound::TraitBound(trait_bound), pred.num_binders))
         }
-        GenericPredicate::Projection(proj) => {
-            if &proj.projection_ty.substitution[0] != self_ty {
+        WhereClause::AliasEq(AliasEq { alias: AliasTy::Projection(projection_ty), ty }) => {
+            if projection_ty.self_type_parameter() != &self_ty_shifted_in {
                 return None;
             }
-            let trait_ = match from_assoc_type_id(proj.projection_ty.associated_ty_id)
-                .lookup(db.upcast())
-                .container
-            {
-                AssocContainerId::TraitId(t) => t,
-                _ => panic!("associated type not in trait"),
-            };
-            let args_no_self = proj.projection_ty.substitution[1..]
+            let trait_ = projection_ty.trait_(db);
+            let args_no_self = projection_ty.substitution[1..]
                 .iter()
                 .map(|ty| ty.clone().to_chalk(db).cast(&Interner))
                 .collect();
             let alias_eq_bound = rust_ir::AliasEqBound {
-                value: proj.ty.clone().to_chalk(db),
+                value: ty.clone().to_chalk(db),
                 trait_bound: rust_ir::TraitBound { trait_id: trait_.to_chalk(db), args_no_self },
-                associated_ty_id: proj.projection_ty.associated_ty_id,
+                associated_ty_id: projection_ty.associated_ty_id,
                 parameters: Vec::new(), // FIXME we don't support generic associated types yet
             };
-            Some(rust_ir::InlineBound::AliasEqBound(alias_eq_bound))
+            Some(make_binders(rust_ir::InlineBound::AliasEqBound(alias_eq_bound), pred.num_binders))
         }
-        GenericPredicate::Error => None,
+        _ => None,
     }
 }