3 files changed, 26 insertions, 47 deletions

diff --git a/crates/hir_ty/src/traits/chalk.rs b/crates/hir_ty/src/traits/chalk.rs
index 55181cc49..2d3cd6719 100644
--- a/crates/hir_ty/src/traits/chalk.rs
+++ b/crates/hir_ty/src/traits/chalk.rs
@@ -17,14 +17,15 @@ use super::ChalkContext;
 use crate::{
     db::HirDatabase,
     display::HirDisplay,
+    from_assoc_type_id,
     method_resolution::{TyFingerprint, ALL_FLOAT_FPS, ALL_INT_FPS},
+    to_assoc_type_id,
     utils::generics,
     BoundVar, CallableDefId, CallableSig, DebruijnIndex, GenericPredicate, ProjectionPredicate,
     ProjectionTy, Substs, TraitRef, Ty, TyKind,
 };
 use mapping::{
-    convert_where_clauses, generic_predicate_to_inline_bound, make_binders, TypeAliasAsAssocType,
-    TypeAliasAsValue,
+    convert_where_clauses, generic_predicate_to_inline_bound, make_binders, TypeAliasAsValue,
 };
 
 pub use self::interner::Interner;
@@ -234,7 +235,7 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
                         ty: TyKind::BoundVar(BoundVar { debruijn: DebruijnIndex::ONE, index: 0 })
                             .intern(&Interner),
                         projection_ty: ProjectionTy {
-                            associated_ty: future_output,
+                            associated_ty: to_assoc_type_id(future_output),
                             // Self type as the first parameter.
                             parameters: Substs::single(
                                 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0))
@@ -383,7 +384,7 @@ pub(crate) fn associated_ty_data_query(
     id: AssocTypeId,
 ) -> Arc<AssociatedTyDatum> {
     debug!("associated_ty_data {:?}", id);
-    let type_alias: TypeAliasId = from_chalk::<TypeAliasAsAssocType, _>(db, id).0;
+    let type_alias: TypeAliasId = from_assoc_type_id(id);
     let trait_ = match type_alias.lookup(db.upcast()).container {
         AssocContainerId::TraitId(t) => t,
         _ => panic!("associated type not in trait"),
@@ -438,10 +439,8 @@ pub(crate) fn trait_datum_query(
         fundamental: false,
     };
     let where_clauses = convert_where_clauses(db, trait_.into(), &bound_vars);
-    let associated_ty_ids = trait_data
-        .associated_types()
-        .map(|type_alias| TypeAliasAsAssocType(type_alias).to_chalk(db))
-        .collect();
+    let associated_ty_ids =
+        trait_data.associated_types().map(|type_alias| to_assoc_type_id(type_alias)).collect();
     let trait_datum_bound = rust_ir::TraitDatumBound { where_clauses };
     let well_known =
         lang_attr(db.upcast(), trait_).and_then(|name| well_known_trait_from_lang_attr(&name));
@@ -623,7 +622,7 @@ fn type_alias_associated_ty_value(
     let value_bound = rust_ir::AssociatedTyValueBound { ty: ty.value.to_chalk(db) };
     let value = rust_ir::AssociatedTyValue {
         impl_id: impl_id.to_chalk(db),
-        associated_ty_id: TypeAliasAsAssocType(assoc_ty).to_chalk(db),
+        associated_ty_id: to_assoc_type_id(assoc_ty),
         value: make_binders(value_bound, ty.num_binders),
     };
     Arc::new(value)
diff --git a/crates/hir_ty/src/traits/chalk/mapping.rs b/crates/hir_ty/src/traits/chalk/mapping.rs
index cf490f9c5..67ac95a0e 100644
--- a/crates/hir_ty/src/traits/chalk/mapping.rs
+++ b/crates/hir_ty/src/traits/chalk/mapping.rs
@@ -14,6 +14,7 @@ use hir_def::{AssocContainerId, GenericDefId, Lookup, TypeAliasId};
 
 use crate::{
     db::HirDatabase,
+    from_assoc_type_id,
     primitive::UintTy,
     traits::{Canonical, Obligation},
     AliasTy, CallableDefId, FnPointer, FnSig, GenericPredicate, InEnvironment, OpaqueTy,
@@ -38,9 +39,7 @@ impl ToChalk for Ty {
                 })
                 .intern(&Interner)
             }
-            TyKind::AssociatedType(type_alias, substs) => {
-                let assoc_type = TypeAliasAsAssocType(type_alias);
-                let assoc_type_id = assoc_type.to_chalk(db);
+            TyKind::AssociatedType(assoc_type_id, substs) => {
                 let substitution = substs.to_chalk(db);
                 chalk_ir::TyKind::AssociatedType(assoc_type_id, substitution).intern(&Interner)
             }
@@ -85,7 +84,7 @@ impl ToChalk for Ty {
                 chalk_ir::TyKind::Adt(adt_id, substitution).intern(&Interner)
             }
             TyKind::Alias(AliasTy::Projection(proj_ty)) => {
-                let associated_ty_id = TypeAliasAsAssocType(proj_ty.associated_ty).to_chalk(db);
+                let associated_ty_id = proj_ty.associated_ty;
                 let substitution = proj_ty.parameters.to_chalk(db);
                 chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy {
                     associated_ty_id,
@@ -139,8 +138,7 @@ impl ToChalk for Ty {
                 TyKind::Placeholder(db.lookup_intern_type_param_id(interned_id))
             }
             chalk_ir::TyKind::Alias(chalk_ir::AliasTy::Projection(proj)) => {
-                let associated_ty =
-                    from_chalk::<TypeAliasAsAssocType, _>(db, proj.associated_ty_id).0;
+                let associated_ty = proj.associated_ty_id;
                 let parameters = from_chalk(db, proj.substitution);
                 TyKind::Alias(AliasTy::Projection(ProjectionTy { associated_ty, parameters }))
             }
@@ -180,10 +178,9 @@ impl ToChalk for Ty {
             }
 
             chalk_ir::TyKind::Adt(adt_id, subst) => TyKind::Adt(adt_id, from_chalk(db, subst)),
-            chalk_ir::TyKind::AssociatedType(type_id, subst) => TyKind::AssociatedType(
-                from_chalk::<TypeAliasAsAssocType, _>(db, type_id).0,
-                from_chalk(db, subst),
-            ),
+            chalk_ir::TyKind::AssociatedType(type_id, subst) => {
+                TyKind::AssociatedType(type_id, from_chalk(db, subst))
+            }
 
             chalk_ir::TyKind::OpaqueType(opaque_type_id, subst) => {
                 TyKind::OpaqueType(from_chalk(db, opaque_type_id), from_chalk(db, subst))
@@ -332,20 +329,6 @@ impl ToChalk for CallableDefId {
     }
 }
 
-pub(crate) struct TypeAliasAsAssocType(pub(crate) TypeAliasId);
-
-impl ToChalk for TypeAliasAsAssocType {
-    type Chalk = AssocTypeId;
-
-    fn to_chalk(self, _db: &dyn HirDatabase) -> AssocTypeId {
-        chalk_ir::AssocTypeId(self.0.as_intern_id())
-    }
-
-    fn from_chalk(_db: &dyn HirDatabase, assoc_type_id: AssocTypeId) -> TypeAliasAsAssocType {
-        TypeAliasAsAssocType(InternKey::from_intern_id(assoc_type_id.0))
-    }
-}
-
 pub(crate) struct TypeAliasAsValue(pub(crate) TypeAliasId);
 
 impl ToChalk for TypeAliasAsValue {
@@ -427,7 +410,7 @@ impl ToChalk for ProjectionTy {
 
     fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::ProjectionTy<Interner> {
         chalk_ir::ProjectionTy {
-            associated_ty_id: TypeAliasAsAssocType(self.associated_ty).to_chalk(db),
+            associated_ty_id: self.associated_ty,
             substitution: self.parameters.to_chalk(db),
         }
     }
@@ -437,11 +420,7 @@ impl ToChalk for ProjectionTy {
         projection_ty: chalk_ir::ProjectionTy<Interner>,
     ) -> ProjectionTy {
         ProjectionTy {
-            associated_ty: from_chalk::<TypeAliasAsAssocType, _>(
-                db,
-                projection_ty.associated_ty_id,
-            )
-            .0,
+            associated_ty: projection_ty.associated_ty_id,
             parameters: from_chalk(db, projection_ty.substitution),
         }
     }
@@ -595,7 +574,10 @@ pub(super) fn generic_predicate_to_inline_bound(
             if &proj.projection_ty.parameters[0] != self_ty {
                 return None;
             }
-            let trait_ = match proj.projection_ty.associated_ty.lookup(db.upcast()).container {
+            let trait_ = match from_assoc_type_id(proj.projection_ty.associated_ty)
+                .lookup(db.upcast())
+                .container
+            {
                 AssocContainerId::TraitId(t) => t,
                 _ => panic!("associated type not in trait"),
             };
@@ -606,8 +588,7 @@ pub(super) fn generic_predicate_to_inline_bound(
             let alias_eq_bound = rust_ir::AliasEqBound {
                 value: proj.ty.clone().to_chalk(db),
                 trait_bound: rust_ir::TraitBound { trait_id: trait_.to_chalk(db), args_no_self },
-                associated_ty_id: TypeAliasAsAssocType(proj.projection_ty.associated_ty)
-                    .to_chalk(db),
+                associated_ty_id: proj.projection_ty.associated_ty,
                 parameters: Vec::new(), // FIXME we don't support generic associated types yet
             };
             Some(rust_ir::InlineBound::AliasEqBound(alias_eq_bound))
diff --git a/crates/hir_ty/src/traits/chalk/tls.rs b/crates/hir_ty/src/traits/chalk/tls.rs
index 75b16172e..8892a63a9 100644
--- a/crates/hir_ty/src/traits/chalk/tls.rs
+++ b/crates/hir_ty/src/traits/chalk/tls.rs
@@ -4,8 +4,8 @@ use std::fmt;
 use chalk_ir::{AliasTy, GenericArg, Goal, Goals, Lifetime, ProgramClauseImplication};
 use itertools::Itertools;
 
-use super::{from_chalk, Interner, TypeAliasAsAssocType};
-use crate::{db::HirDatabase, CallableDefId};
+use super::{from_chalk, Interner};
+use crate::{db::HirDatabase, from_assoc_type_id, CallableDefId};
 use hir_def::{AdtId, AssocContainerId, Lookup, TypeAliasId};
 
 pub(crate) use unsafe_tls::{set_current_program, with_current_program};
@@ -41,7 +41,7 @@ impl DebugContext<'_> {
         id: super::AssocTypeId,
         fmt: &mut fmt::Formatter<'_>,
     ) -> Result<(), fmt::Error> {
-        let type_alias: TypeAliasId = from_chalk::<TypeAliasAsAssocType, _>(self.0, id).0;
+        let type_alias: TypeAliasId = from_assoc_type_id(id);
         let type_alias_data = self.0.type_alias_data(type_alias);
         let trait_ = match type_alias.lookup(self.0.upcast()).container {
             AssocContainerId::TraitId(t) => t,
@@ -75,8 +75,7 @@ impl DebugContext<'_> {
         projection_ty: &chalk_ir::ProjectionTy<Interner>,
         fmt: &mut fmt::Formatter<'_>,
     ) -> Result<(), fmt::Error> {
-        let type_alias: TypeAliasId =
-            from_chalk::<TypeAliasAsAssocType, _>(self.0, projection_ty.associated_ty_id).0;
+        let type_alias = from_assoc_type_id(projection_ty.associated_ty_id);
         let type_alias_data = self.0.type_alias_data(type_alias);
         let trait_ = match type_alias.lookup(self.0.upcast()).container {
             AssocContainerId::TraitId(t) => t,