Use chalk_ir::AssocTypeId

9 files changed, 82 insertions, 74 deletions

diff --git a/crates/hir_ty/src/autoderef.rs b/crates/hir_ty/src/autoderef.rs
index 09009a3d8..d739d5d60 100644
--- a/crates/hir_ty/src/autoderef.rs
+++ b/crates/hir_ty/src/autoderef.rs
@@ -12,6 +12,7 @@ use log::{info, warn};
 
 use crate::{
     db::HirDatabase,
+    to_assoc_type_id,
     traits::{InEnvironment, Solution},
     utils::generics,
     BoundVar, Canonical, DebruijnIndex, Interner, Obligation, Substs, TraitRef, Ty, TyKind,
@@ -83,7 +84,7 @@ fn deref_by_trait(
     let projection = super::traits::ProjectionPredicate {
         ty: TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, ty.value.kinds.len()))
             .intern(&Interner),
-        projection_ty: super::ProjectionTy { associated_ty: target, parameters },
+        projection_ty: super::ProjectionTy { associated_ty: to_assoc_type_id(target), parameters },
     };
 
     let obligation = super::Obligation::Projection(projection);
diff --git a/crates/hir_ty/src/display.rs b/crates/hir_ty/src/display.rs
index 9b1e2ad05..2022069d8 100644
--- a/crates/hir_ty/src/display.rs
+++ b/crates/hir_ty/src/display.rs
@@ -11,9 +11,9 @@ use hir_def::{
 use hir_expand::name::Name;
 
 use crate::{
-    db::HirDatabase, from_foreign_def_id, primitive, utils::generics, AdtId, AliasTy,
-    CallableDefId, CallableSig, GenericPredicate, Interner, Lifetime, Obligation, OpaqueTy,
-    OpaqueTyId, ProjectionTy, Scalar, Substs, TraitRef, Ty, TyKind,
+    db::HirDatabase, from_assoc_type_id, from_foreign_def_id, primitive, to_assoc_type_id,
+    utils::generics, AdtId, AliasTy, CallableDefId, CallableSig, GenericPredicate, Interner,
+    Lifetime, Obligation, OpaqueTy, OpaqueTyId, ProjectionTy, Scalar, Substs, TraitRef, Ty, TyKind,
 };
 
 pub struct HirFormatter<'a> {
@@ -256,7 +256,7 @@ impl HirDisplay for ProjectionTy {
             f.write_joined(&self.parameters[1..], ", ")?;
             write!(f, ">")?;
         }
-        write!(f, ">::{}", f.db.type_alias_data(self.associated_ty).name)?;
+        write!(f, ">::{}", f.db.type_alias_data(from_assoc_type_id(self.associated_ty)).name)?;
         Ok(())
     }
 }
@@ -467,13 +467,14 @@ impl HirDisplay for Ty {
                     }
                 }
             }
-            TyKind::AssociatedType(type_alias, parameters) => {
+            TyKind::AssociatedType(assoc_type_id, parameters) => {
+                let type_alias = from_assoc_type_id(*assoc_type_id);
                 let trait_ = match type_alias.lookup(f.db.upcast()).container {
                     AssocContainerId::TraitId(it) => it,
                     _ => panic!("not an associated type"),
                 };
                 let trait_ = f.db.trait_data(trait_);
-                let type_alias_data = f.db.type_alias_data(*type_alias);
+                let type_alias_data = f.db.type_alias_data(type_alias);
 
                 // Use placeholder associated types when the target is test (https://rust-lang.github.io/chalk/book/clauses/type_equality.html#placeholder-associated-types)
                 if f.display_target.is_test() {
@@ -484,8 +485,10 @@ impl HirDisplay for Ty {
                         write!(f, ">")?;
                     }
                 } else {
-                    let projection_ty =
-                        ProjectionTy { associated_ty: *type_alias, parameters: parameters.clone() };
+                    let projection_ty = ProjectionTy {
+                        associated_ty: to_assoc_type_id(type_alias),
+                        parameters: parameters.clone(),
+                    };
 
                     projection_ty.hir_fmt(f)?;
                 }
@@ -697,7 +700,9 @@ fn write_bounds_like_dyn_trait(
                     write!(f, "<")?;
                     angle_open = true;
                 }
-                let type_alias = f.db.type_alias_data(projection_pred.projection_ty.associated_ty);
+                let type_alias = f.db.type_alias_data(from_assoc_type_id(
+                    projection_pred.projection_ty.associated_ty,
+                ));
                 write!(f, "{} = ", type_alias.name)?;
                 projection_pred.ty.hir_fmt(f)?;
             }
@@ -768,7 +773,10 @@ impl HirDisplay for GenericPredicate {
                 write!(
                     f,
                     ">::{} = ",
-                    f.db.type_alias_data(projection_pred.projection_ty.associated_ty).name,
+                    f.db.type_alias_data(from_assoc_type_id(
+                        projection_pred.projection_ty.associated_ty
+                    ))
+                    .name,
                 )?;
                 projection_pred.ty.hir_fmt(f)?;
             }
diff --git a/crates/hir_ty/src/infer.rs b/crates/hir_ty/src/infer.rs
index acde99b04..9d9bf549c 100644
--- a/crates/hir_ty/src/infer.rs
+++ b/crates/hir_ty/src/infer.rs
@@ -42,7 +42,7 @@ use super::{
 };
 use crate::{
     db::HirDatabase, infer::diagnostics::InferenceDiagnostic, lower::ImplTraitLoweringMode,
-    AliasTy, Interner, TyKind,
+    to_assoc_type_id, AliasTy, Interner, TyKind,
 };
 
 pub(crate) use unify::unify;
@@ -382,7 +382,10 @@ impl<'a> InferenceContext<'a> {
                 let trait_ref = TraitRef { trait_, substs: substs.clone() };
                 let projection = ProjectionPredicate {
                     ty: ty.clone(),
-                    projection_ty: ProjectionTy { associated_ty: res_assoc_ty, parameters: substs },
+                    projection_ty: ProjectionTy {
+                        associated_ty: to_assoc_type_id(res_assoc_ty),
+                        parameters: substs,
+                    },
                 };
                 self.obligations.push(Obligation::Trait(trait_ref));
                 self.obligations.push(Obligation::Projection(projection));
diff --git a/crates/hir_ty/src/infer/expr.rs b/crates/hir_ty/src/infer/expr.rs
index 4e77f22fd..a72424dc7 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs
@@ -18,6 +18,7 @@ use crate::{
     lower::lower_to_chalk_mutability,
     method_resolution, op,
     primitive::{self, UintTy},
+    to_assoc_type_id,
     traits::{FnTrait, InEnvironment},
     utils::{generics, variant_data, Generics},
     AdtId, Binders, CallableDefId, FnPointer, FnSig, Interner, Obligation, OpaqueTyId, Rawness,
@@ -97,8 +98,10 @@ impl<'a> InferenceContext<'a> {
         });
         if self.db.trait_solve(krate, goal.value).is_some() {
             self.obligations.push(implements_fn_trait);
-            let output_proj_ty =
-                crate::ProjectionTy { associated_ty: output_assoc_type, parameters: substs };
+            let output_proj_ty = crate::ProjectionTy {
+                associated_ty: to_assoc_type_id(output_assoc_type),
+                parameters: substs,
+            };
             let return_ty = self.normalize_projection_ty(output_proj_ty);
             Some((arg_tys, return_ty))
         } else {
diff --git a/crates/hir_ty/src/lib.rs b/crates/hir_ty/src/lib.rs
index 94cbb21ca..5752ddc4e 100644
--- a/crates/hir_ty/src/lib.rs
+++ b/crates/hir_ty/src/lib.rs
@@ -52,6 +52,7 @@ pub use chalk_ir::{AdtId, BoundVar, DebruijnIndex, Mutability, Scalar, TyVariabl
 pub use crate::traits::chalk::Interner;
 
 pub type ForeignDefId = chalk_ir::ForeignDefId<Interner>;
+pub type AssocTypeId = chalk_ir::AssocTypeId<Interner>;
 
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub enum Lifetime {
@@ -70,7 +71,7 @@ pub struct OpaqueTy {
 /// trait and all its parameters are fully known.
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub struct ProjectionTy {
-    pub associated_ty: TypeAliasId,
+    pub associated_ty: AssocTypeId,
     pub parameters: Substs,
 }
 
@@ -80,7 +81,7 @@ impl ProjectionTy {
     }
 
     fn trait_(&self, db: &dyn HirDatabase) -> TraitId {
-        match self.associated_ty.lookup(db.upcast()).container {
+        match from_assoc_type_id(self.associated_ty).lookup(db.upcast()).container {
             AssocContainerId::TraitId(it) => it,
             _ => panic!("projection ty without parent trait"),
         }
@@ -141,7 +142,7 @@ pub enum TyKind {
     /// when we have tried to normalize a projection like `T::Item` but
     /// couldn't find a better representation.  In that case, we generate
     /// an **application type** like `(Iterator::Item)<T>`.
-    AssociatedType(TypeAliasId, Substs),
+    AssociatedType(AssocTypeId, Substs),
 
     /// a scalar type like `bool` or `u32`
     Scalar(Scalar),
@@ -706,7 +707,7 @@ impl Ty {
         match *self.interned(&Interner) {
             TyKind::Adt(AdtId(adt), ..) => Some(adt.into()),
             TyKind::FnDef(callable, ..) => Some(callable.into()),
-            TyKind::AssociatedType(type_alias, ..) => Some(type_alias.into()),
+            TyKind::AssociatedType(type_alias, ..) => Some(from_assoc_type_id(type_alias).into()),
             TyKind::ForeignType(type_alias, ..) => Some(from_foreign_def_id(type_alias).into()),
             _ => None,
         }
@@ -920,14 +921,15 @@ impl Ty {
 
     pub fn associated_type_parent_trait(&self, db: &dyn HirDatabase) -> Option<TraitId> {
         match self.interned(&Interner) {
-            TyKind::AssociatedType(type_alias_id, ..) => {
-                match type_alias_id.lookup(db.upcast()).container {
+            TyKind::AssociatedType(id, ..) => {
+                match from_assoc_type_id(*id).lookup(db.upcast()).container {
                     AssocContainerId::TraitId(trait_id) => Some(trait_id),
                     _ => None,
                 }
             }
             TyKind::Alias(AliasTy::Projection(projection_ty)) => {
-                match projection_ty.associated_ty.lookup(db.upcast()).container {
+                match from_assoc_type_id(projection_ty.associated_ty).lookup(db.upcast()).container
+                {
                     AssocContainerId::TraitId(trait_id) => Some(trait_id),
                     _ => None,
                 }
@@ -1121,10 +1123,18 @@ pub(crate) struct ReturnTypeImplTrait {
     pub(crate) bounds: Binders<Vec<GenericPredicate>>,
 }
 
-pub(crate) fn to_foreign_def_id(id: TypeAliasId) -> chalk_ir::ForeignDefId<Interner> {
+pub fn to_foreign_def_id(id: TypeAliasId) -> ForeignDefId {
     chalk_ir::ForeignDefId(salsa::InternKey::as_intern_id(&id))
 }
 
-pub(crate) fn from_foreign_def_id(id: chalk_ir::ForeignDefId<Interner>) -> TypeAliasId {
+pub fn from_foreign_def_id(id: ForeignDefId) -> TypeAliasId {
+    salsa::InternKey::from_intern_id(id.0)
+}
+
+pub fn to_assoc_type_id(id: TypeAliasId) -> AssocTypeId {
+    chalk_ir::AssocTypeId(salsa::InternKey::as_intern_id(&id))
+}
+
+pub fn from_assoc_type_id(id: AssocTypeId) -> TypeAliasId {
     salsa::InternKey::from_intern_id(id.0)
 }
diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index a35d7266d..a5ab1ff70 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -27,6 +27,7 @@ use stdx::impl_from;
 
 use crate::{
     db::HirDatabase,
+    to_assoc_type_id,
     traits::chalk::{Interner, ToChalk},
     utils::{
         all_super_trait_refs, associated_type_by_name_including_super_traits, generics,
@@ -358,7 +359,7 @@ impl Ty {
                         Some((super_trait_ref, associated_ty)) => {
                             // FIXME handle type parameters on the segment
                             TyKind::Alias(AliasTy::Projection(ProjectionTy {
-                                associated_ty,
+                                associated_ty: to_assoc_type_id(associated_ty),
                                 parameters: super_trait_ref.substs,
                             }))
                             .intern(&Interner)
@@ -487,7 +488,7 @@ impl Ty {
                         // FIXME handle type parameters on the segment
                         return Some(
                             TyKind::Alias(AliasTy::Projection(ProjectionTy {
-                                associated_ty,
+                                associated_ty: to_assoc_type_id(associated_ty),
                                 parameters: substs,
                             }))
                             .intern(&Interner),
@@ -753,7 +754,10 @@ fn assoc_type_bindings_from_type_bound<'a>(
                 None => return SmallVec::<[GenericPredicate; 1]>::new(),
                 Some(t) => t,
             };
-            let projection_ty = ProjectionTy { associated_ty, parameters: super_trait_ref.substs };
+            let projection_ty = ProjectionTy {
+                associated_ty: to_assoc_type_id(associated_ty),
+                parameters: super_trait_ref.substs,
+            };
             let mut preds = SmallVec::with_capacity(
                 binding.type_ref.as_ref().map_or(0, |_| 1) + binding.bounds.len(),
             );
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,