14 files changed, 158 insertions, 135 deletions

diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index 7b9de11ed..7f8f936d3 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -51,7 +51,7 @@ use hir_expand::{diagnostics::DiagnosticSink, name::name, MacroDefKind};
 use hir_ty::{
     autoderef,
     display::{write_bounds_like_dyn_trait_with_prefix, HirDisplayError, HirFormatter},
-    method_resolution,
+    method_resolution, to_assoc_type_id,
     traits::{FnTrait, Solution, SolutionVariables},
     AliasTy, BoundVar, CallableDefId, CallableSig, Canonical, DebruijnIndex, GenericPredicate,
     InEnvironment, Interner, Obligation, ProjectionPredicate, ProjectionTy, Scalar, Substs,
@@ -1683,7 +1683,10 @@ impl Type {
             .fill(args.iter().map(|t| t.ty.value.clone()))
             .build();
         let predicate = ProjectionPredicate {
-            projection_ty: ProjectionTy { associated_ty: alias.id, parameters: subst },
+            projection_ty: ProjectionTy {
+                associated_ty: to_assoc_type_id(alias.id),
+                parameters: subst,
+            },
             ty: TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(&Interner),
         };
         let goal = Canonical {
@@ -1712,10 +1715,7 @@ impl Type {
     }
 
     pub fn as_callable(&self, db: &dyn HirDatabase) -> Option<Callable> {
-        let def = match self.ty.value.interned(&Interner) {
-            &TyKind::FnDef(def, _) => Some(def),
-            _ => None,
-        };
+        let def = self.ty.value.callable_def(db);
 
         let sig = self.ty.value.callable_sig(db)?;
         Some(Callable { ty: self.clone(), sig, def, is_bound_method: false })
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/db.rs b/crates/hir_ty/src/db.rs
index 06714409f..a038674cf 100644
--- a/crates/hir_ty/src/db.rs
+++ b/crates/hir_ty/src/db.rs
@@ -12,7 +12,7 @@ use la_arena::ArenaMap;
 use crate::{
     method_resolution::{InherentImpls, TraitImpls},
     traits::chalk,
-    Binders, CallableDefId, GenericPredicate, InferenceResult, OpaqueTyId, PolyFnSig,
+    Binders, CallableDefId, FnDefId, GenericPredicate, InferenceResult, OpaqueTyId, PolyFnSig,
     ReturnTypeImplTraits, TraitRef, Ty, TyDefId, ValueTyDefId,
 };
 use hir_expand::name::Name;
@@ -100,10 +100,10 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
     fn impl_datum(&self, krate: CrateId, impl_id: chalk::ImplId) -> Arc<chalk::ImplDatum>;
 
     #[salsa::invoke(crate::traits::chalk::fn_def_datum_query)]
-    fn fn_def_datum(&self, krate: CrateId, fn_def_id: chalk::FnDefId) -> Arc<chalk::FnDefDatum>;
+    fn fn_def_datum(&self, krate: CrateId, fn_def_id: FnDefId) -> Arc<chalk::FnDefDatum>;
 
     #[salsa::invoke(crate::traits::chalk::fn_def_variance_query)]
-    fn fn_def_variance(&self, krate: CrateId, fn_def_id: chalk::FnDefId) -> chalk::Variances;
+    fn fn_def_variance(&self, krate: CrateId, fn_def_id: FnDefId) -> chalk::Variances;
 
     #[salsa::invoke(crate::traits::chalk::adt_variance_query)]
     fn adt_variance(&self, krate: CrateId, adt_id: chalk::AdtId) -> chalk::Variances;
diff --git a/crates/hir_ty/src/diagnostics/unsafe_check.rs b/crates/hir_ty/src/diagnostics/unsafe_check.rs
index e095bee28..20bb64827 100644
--- a/crates/hir_ty/src/diagnostics/unsafe_check.rs
+++ b/crates/hir_ty/src/diagnostics/unsafe_check.rs
@@ -85,7 +85,7 @@ fn walk_unsafe(
     let expr = &body.exprs[current];
     match expr {
         &Expr::Call { callee, .. } => {
-            if let Some(func) = infer[callee].as_fn_def() {
+            if let Some(func) = infer[callee].as_fn_def(db) {
                 if db.function_data(func).is_unsafe {
                     unsafe_exprs.push(UnsafeExpr { expr: current, inside_unsafe_block });
                 }
diff --git a/crates/hir_ty/src/display.rs b/crates/hir_ty/src/display.rs
index ee15f4f52..b7e85e024 100644
--- a/crates/hir_ty/src/display.rs
+++ b/crates/hir_ty/src/display.rs
@@ -11,7 +11,8 @@ use hir_def::{
 use hir_expand::name::Name;
 
 use crate::{
-    db::HirDatabase, primitive, utils::generics, AdtId, AliasTy, CallableDefId, CallableSig,
+    db::HirDatabase, from_assoc_type_id, from_foreign_def_id, primitive, to_assoc_type_id,
+    traits::chalk::from_chalk, utils::generics, AdtId, AliasTy, CallableDefId, CallableSig,
     GenericPredicate, Interner, Lifetime, Obligation, OpaqueTy, OpaqueTyId, ProjectionTy, Scalar,
     Substs, TraitRef, Ty, TyKind,
 };
@@ -256,7 +257,7 @@ 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(())
     }
 }
@@ -363,7 +364,7 @@ impl HirDisplay for Ty {
                 sig.hir_fmt(f)?;
             }
             TyKind::FnDef(def, parameters) => {
-                let def = *def;
+                let def = from_chalk(f.db, *def);
                 let sig = f.db.callable_item_signature(def).subst(parameters);
                 match def {
                     CallableDefId::FunctionId(ff) => {
@@ -431,7 +432,7 @@ impl HirDisplay for Ty {
                         || f.omit_verbose_types()
                     {
                         match self
-                            .as_generic_def()
+                            .as_generic_def(f.db)
                             .map(|generic_def_id| f.db.generic_defaults(generic_def_id))
                             .filter(|defaults| !defaults.is_empty())
                         {
@@ -467,13 +468,14 @@ 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() {
@@ -484,14 +486,16 @@ 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)?;
                 }
             }
             TyKind::ForeignType(type_alias) => {
-                let type_alias = f.db.type_alias_data(*type_alias);
+                let type_alias = f.db.type_alias_data(from_foreign_def_id(*type_alias));
                 write!(f, "{}", type_alias.name)?;
             }
             TyKind::OpaqueType(opaque_ty_id, parameters) => {
@@ -697,7 +701,9 @@ 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 +774,10 @@ 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..153f22f25 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs
@@ -18,7 +18,8 @@ use crate::{
     lower::lower_to_chalk_mutability,
     method_resolution, op,
     primitive::{self, UintTy},
-    traits::{FnTrait, InEnvironment},
+    to_assoc_type_id,
+    traits::{chalk::from_chalk, FnTrait, InEnvironment},
     utils::{generics, variant_data, Generics},
     AdtId, Binders, CallableDefId, FnPointer, FnSig, Interner, Obligation, OpaqueTyId, Rawness,
     Scalar, Substs, TraitRef, Ty, TyKind,
@@ -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 {
@@ -929,8 +932,9 @@ impl<'a> InferenceContext<'a> {
     }
 
     fn register_obligations_for_call(&mut self, callable_ty: &Ty) {
-        if let TyKind::FnDef(def, parameters) = callable_ty.interned(&Interner) {
-            let generic_predicates = self.db.generic_predicates((*def).into());
+        if let TyKind::FnDef(fn_def, parameters) = callable_ty.interned(&Interner) {
+            let def: CallableDefId = from_chalk(self.db, *fn_def);
+            let generic_predicates = self.db.generic_predicates(def.into());
             for predicate in generic_predicates.iter() {
                 let predicate = predicate.clone().subst(parameters);
                 if let Some(obligation) = Obligation::from_predicate(predicate) {
diff --git a/crates/hir_ty/src/lib.rs b/crates/hir_ty/src/lib.rs
index 2309db492..6b3485264 100644
--- a/crates/hir_ty/src/lib.rs
+++ b/crates/hir_ty/src/lib.rs
@@ -51,6 +51,10 @@ 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>;
+pub(crate) type FnDefId = chalk_ir::FnDefId<Interner>;
+
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub enum Lifetime {
     Parameter(LifetimeParamId),
@@ -68,7 +72,7 @@ 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,
 }
 
@@ -78,7 +82,7 @@ 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"),
         }
@@ -139,7 +143,7 @@ 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),
@@ -179,7 +183,7 @@ pub enum TyKind {
     /// fn foo() -> i32 { 1 }
     /// let bar = foo; // bar: fn() -> i32 {foo}
     /// ```
-    FnDef(CallableDefId, Substs),
+    FnDef(FnDefId, Substs),
 
     /// The pointee of a string slice. Written as `str`.
     Str,
@@ -194,7 +198,7 @@ pub enum TyKind {
     Closure(DefWithBodyId, ExprId, Substs),
 
     /// Represents a foreign type declared in external blocks.
-    ForeignType(TypeAliasId),
+    ForeignType(ForeignDefId),
 
     /// A pointer to a function.  Written as `fn() -> i32`.
     ///
@@ -700,12 +704,14 @@ impl Ty {
         }
     }
 
-    pub fn as_generic_def(&self) -> Option<GenericDefId> {
+    pub fn as_generic_def(&self, db: &dyn HirDatabase) -> Option<GenericDefId> {
         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::ForeignType(type_alias, ..) => Some(type_alias.into()),
+            TyKind::FnDef(callable, ..) => {
+                Some(db.lookup_intern_callable_def(callable.into()).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,
         }
     }
@@ -724,8 +730,10 @@ impl Ty {
             (TyKind::Slice(_), TyKind::Slice(_)) | (TyKind::Array(_), TyKind::Array(_)) => true,
             (TyKind::FnDef(def_id, ..), TyKind::FnDef(def_id2, ..)) => def_id == def_id2,
             (TyKind::OpaqueType(ty_id, ..), TyKind::OpaqueType(ty_id2, ..)) => ty_id == ty_id2,
-            (TyKind::AssociatedType(ty_id, ..), TyKind::AssociatedType(ty_id2, ..))
-            | (TyKind::ForeignType(ty_id, ..), TyKind::ForeignType(ty_id2, ..)) => ty_id == ty_id2,
+            (TyKind::AssociatedType(ty_id, ..), TyKind::AssociatedType(ty_id2, ..)) => {
+                ty_id == ty_id2
+            }
+            (TyKind::ForeignType(ty_id, ..), TyKind::ForeignType(ty_id2, ..)) => ty_id == ty_id2,
             (TyKind::Closure(def, expr, _), TyKind::Closure(def2, expr2, _)) => {
                 expr == expr2 && def == def2
             }
@@ -770,18 +778,27 @@ impl Ty {
         }
     }
 
-    pub fn as_fn_def(&self) -> Option<FunctionId> {
+    pub fn callable_def(&self, db: &dyn HirDatabase) -> Option<CallableDefId> {
         match self.interned(&Interner) {
-            &TyKind::FnDef(CallableDefId::FunctionId(func), ..) => Some(func),
+            &TyKind::FnDef(def, ..) => Some(db.lookup_intern_callable_def(def.into())),
             _ => None,
         }
     }
 
+    pub fn as_fn_def(&self, db: &dyn HirDatabase) -> Option<FunctionId> {
+        if let Some(CallableDefId::FunctionId(func)) = self.callable_def(db) {
+            Some(func)
+        } else {
+            None
+        }
+    }
+
     pub fn callable_sig(&self, db: &dyn HirDatabase) -> Option<CallableSig> {
         match self.interned(&Interner) {
             TyKind::Function(fn_ptr) => Some(CallableSig::from_fn_ptr(fn_ptr)),
             TyKind::FnDef(def, parameters) => {
-                let sig = db.callable_item_signature(*def);
+                let callable_def = db.lookup_intern_callable_def((*def).into());
+                let sig = db.callable_item_signature(callable_def);
                 Some(sig.subst(&parameters))
             }
             TyKind::Closure(.., substs) => {
@@ -916,14 +933,15 @@ 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,
                 }
@@ -1116,3 +1134,19 @@ pub struct ReturnTypeImplTraits {
 pub(crate) struct ReturnTypeImplTrait {
     pub(crate) bounds: Binders<Vec<GenericPredicate>>,
 }
+
+pub fn to_foreign_def_id(id: TypeAliasId) -> ForeignDefId {
+    chalk_ir::ForeignDefId(salsa::InternKey::as_intern_id(&id))
+}
+
+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 9fe7e3dce..b8b1400eb 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(),
             );
@@ -1060,7 +1064,10 @@ fn fn_sig_for_fn(db: &dyn HirDatabase, def: FunctionId) -> PolyFnSig {
 fn type_for_fn(db: &dyn HirDatabase, def: FunctionId) -> Binders<Ty> {
     let generics = generics(db.upcast(), def.into());
     let substs = Substs::bound_vars(&generics, DebruijnIndex::INNERMOST);
-    Binders::new(substs.len(), TyKind::FnDef(def.into(), substs).intern(&Interner))
+    Binders::new(
+        substs.len(),
+        TyKind::FnDef(CallableDefId::FunctionId(def).to_chalk(db), substs).intern(&Interner),
+    )
 }
 
 /// Build the declared type of a const.
@@ -1103,7 +1110,10 @@ fn type_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> Binders<T
     }
     let generics = generics(db.upcast(), def.into());
     let substs = Substs::bound_vars(&generics, DebruijnIndex::INNERMOST);
-    Binders::new(substs.len(), TyKind::FnDef(def.into(), substs).intern(&Interner))
+    Binders::new(
+        substs.len(),
+        TyKind::FnDef(CallableDefId::StructId(def).to_chalk(db), substs).intern(&Interner),
+    )
 }
 
 fn fn_sig_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -> PolyFnSig {
@@ -1128,7 +1138,10 @@ fn type_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -
     }
     let generics = generics(db.upcast(), def.parent.into());
     let substs = Substs::bound_vars(&generics, DebruijnIndex::INNERMOST);
-    Binders::new(substs.len(), TyKind::FnDef(def.into(), substs).intern(&Interner))
+    Binders::new(
+        substs.len(),
+        TyKind::FnDef(CallableDefId::EnumVariantId(def).to_chalk(db), substs).intern(&Interner),
+    )
 }
 
 fn type_for_adt(db: &dyn HirDatabase, adt: AdtId) -> Binders<Ty> {
@@ -1143,7 +1156,7 @@ fn type_for_type_alias(db: &dyn HirDatabase, t: TypeAliasId) -> Binders<Ty> {
     let ctx =
         TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
     if db.type_alias_data(t).is_extern {
-        Binders::new(0, TyKind::ForeignType(t).intern(&Interner))
+        Binders::new(0, TyKind::ForeignType(crate::to_foreign_def_id(t)).intern(&Interner))
     } else {
         let substs = Substs::bound_vars(&generics, DebruijnIndex::INNERMOST);
         let type_ref = &db.type_alias_data(t).type_ref;
diff --git a/crates/hir_ty/src/method_resolution.rs b/crates/hir_ty/src/method_resolution.rs
index f9877e760..c7055bee5 100644
--- a/crates/hir_ty/src/method_resolution.rs
+++ b/crates/hir_ty/src/method_resolution.rs
@@ -9,7 +9,7 @@ use base_db::CrateId;
 use chalk_ir::Mutability;
 use hir_def::{
     lang_item::LangItemTarget, AssocContainerId, AssocItemId, FunctionId, GenericDefId, HasModule,
-    ImplId, Lookup, ModuleId, TraitId, TypeAliasId,
+    ImplId, Lookup, ModuleId, TraitId,
 };
 use hir_expand::name::Name;
 use rustc_hash::{FxHashMap, FxHashSet};
@@ -17,10 +17,11 @@ use rustc_hash::{FxHashMap, FxHashSet};
 use crate::{
     autoderef,
     db::HirDatabase,
+    from_foreign_def_id,
     primitive::{self, FloatTy, IntTy, UintTy},
     utils::all_super_traits,
-    AdtId, Canonical, DebruijnIndex, FnPointer, FnSig, InEnvironment, Interner, Scalar, Substs,
-    TraitEnvironment, TraitRef, Ty, TyKind, TypeWalk,
+    AdtId, Canonical, DebruijnIndex, FnPointer, FnSig, ForeignDefId, InEnvironment, Interner,
+    Scalar, Substs, TraitEnvironment, TraitRef, Ty, TyKind, TypeWalk,
 };
 
 /// This is used as a key for indexing impls.
@@ -35,7 +36,7 @@ pub enum TyFingerprint {
     Adt(hir_def::AdtId),
     Dyn(TraitId),
     Tuple(usize),
-    ForeignType(TypeAliasId),
+    ForeignType(ForeignDefId),
     FnPtr(usize, FnSig),
 }
 
@@ -236,8 +237,10 @@ impl Ty {
             TyKind::Adt(AdtId(def_id), _) => {
                 return mod_to_crate_ids(def_id.module(db.upcast()));
             }
-            TyKind::ForeignType(type_alias_id) => {
-                return mod_to_crate_ids(type_alias_id.lookup(db.upcast()).module(db.upcast()));
+            TyKind::ForeignType(id) => {
+                return mod_to_crate_ids(
+                    from_foreign_def_id(*id).lookup(db.upcast()).module(db.upcast()),
+                );
             }
             TyKind::Scalar(Scalar::Bool) => lang_item_crate!("bool"),
             TyKind::Scalar(Scalar::Char) => lang_item_crate!("char"),
diff --git a/crates/hir_ty/src/traits/chalk.rs b/crates/hir_ty/src/traits/chalk.rs
index 55181cc49..bb92d8e2a 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,
+    BoundVar, CallableDefId, CallableSig, DebruijnIndex, FnDefId, 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/interner.rs b/crates/hir_ty/src/traits/chalk/interner.rs
index 54bd1c724..1dc3f497d 100644
--- a/crates/hir_ty/src/traits/chalk/interner.rs
+++ b/crates/hir_ty/src/traits/chalk/interner.rs
@@ -12,7 +12,6 @@ pub struct Interner;
 
 pub(crate) type AssocTypeId = chalk_ir::AssocTypeId<Interner>;
 pub(crate) type AssociatedTyDatum = chalk_solve::rust_ir::AssociatedTyDatum<Interner>;
-pub(crate) type ForeignDefId = chalk_ir::ForeignDefId<Interner>;
 pub(crate) type TraitId = chalk_ir::TraitId<Interner>;
 pub(crate) type TraitDatum = chalk_solve::rust_ir::TraitDatum<Interner>;
 pub(crate) type AdtId = chalk_ir::AdtId<Interner>;
@@ -21,7 +20,6 @@ pub(crate) type ImplId = chalk_ir::ImplId<Interner>;
 pub(crate) type ImplDatum = chalk_solve::rust_ir::ImplDatum<Interner>;
 pub(crate) type AssociatedTyValueId = chalk_solve::rust_ir::AssociatedTyValueId<Interner>;
 pub(crate) type AssociatedTyValue = chalk_solve::rust_ir::AssociatedTyValue<Interner>;
-pub(crate) type FnDefId = chalk_ir::FnDefId<Interner>;
 pub(crate) type FnDefDatum = chalk_solve::rust_ir::FnDefDatum<Interner>;
 pub(crate) type OpaqueTyId = chalk_ir::OpaqueTyId<Interner>;
 pub(crate) type OpaqueTyDatum = chalk_solve::rust_ir::OpaqueTyDatum<Interner>;
diff --git a/crates/hir_ty/src/traits/chalk/mapping.rs b/crates/hir_ty/src/traits/chalk/mapping.rs
index 44cfb9359..23ef07d77 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)
             }
@@ -51,11 +50,7 @@ impl ToChalk for Ty {
                 chalk_ir::TyKind::OpaqueType(id, substitution).intern(&Interner)
             }
 
-            TyKind::ForeignType(type_alias) => {
-                let foreign_type = TypeAliasAsForeignType(type_alias);
-                let foreign_type_id = foreign_type.to_chalk(db);
-                chalk_ir::TyKind::Foreign(foreign_type_id).intern(&Interner)
-            }
+            TyKind::ForeignType(id) => chalk_ir::TyKind::Foreign(id).intern(&Interner),
 
             TyKind::Scalar(scalar) => chalk_ir::TyKind::Scalar(scalar).intern(&Interner),
 
@@ -71,8 +66,7 @@ impl ToChalk for Ty {
                 chalk_ir::TyKind::Slice(substs[0].clone().to_chalk(db)).intern(&Interner)
             }
             TyKind::Str => chalk_ir::TyKind::Str.intern(&Interner),
-            TyKind::FnDef(callable_def, substs) => {
-                let id = callable_def.to_chalk(db);
+            TyKind::FnDef(id, substs) => {
                 let substitution = substs.to_chalk(db);
                 chalk_ir::TyKind::FnDef(id, substitution).intern(&Interner)
             }
@@ -89,7 +83,7 @@ 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,
@@ -143,8 +137,7 @@ 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 }))
             }
@@ -184,10 +177,9 @@ 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))
@@ -208,7 +200,7 @@ impl ToChalk for Ty {
             chalk_ir::TyKind::Never => TyKind::Never,
 
             chalk_ir::TyKind::FnDef(fn_def_id, subst) => {
-                TyKind::FnDef(from_chalk(db, fn_def_id), from_chalk(db, subst))
+                TyKind::FnDef(fn_def_id, from_chalk(db, subst))
             }
 
             chalk_ir::TyKind::Closure(id, subst) => {
@@ -217,9 +209,7 @@ impl ToChalk for Ty {
                 TyKind::Closure(def, expr, from_chalk(db, subst))
             }
 
-            chalk_ir::TyKind::Foreign(foreign_def_id) => {
-                TyKind::ForeignType(from_chalk::<TypeAliasAsForeignType, _>(db, foreign_def_id).0)
-            }
+            chalk_ir::TyKind::Foreign(foreign_def_id) => TyKind::ForeignType(foreign_def_id),
             chalk_ir::TyKind::Generator(_, _) => unimplemented!(), // FIXME
             chalk_ir::TyKind::GeneratorWitness(_, _) => unimplemented!(), // FIXME
         }
@@ -338,34 +328,6 @@ 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 TypeAliasAsForeignType(pub(crate) TypeAliasId);
-
-impl ToChalk for TypeAliasAsForeignType {
-    type Chalk = ForeignDefId;
-
-    fn to_chalk(self, _db: &dyn HirDatabase) -> ForeignDefId {
-        chalk_ir::ForeignDefId(self.0.as_intern_id())
-    }
-
-    fn from_chalk(_db: &dyn HirDatabase, foreign_def_id: ForeignDefId) -> TypeAliasAsForeignType {
-        TypeAliasAsForeignType(InternKey::from_intern_id(foreign_def_id.0))
-    }
-}
-
 pub(crate) struct TypeAliasAsValue(pub(crate) TypeAliasId);
 
 impl ToChalk for TypeAliasAsValue {
@@ -447,7 +409,7 @@ 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),
         }
     }
@@ -457,11 +419,7 @@ 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),
         }
     }
@@ -615,7 +573,10 @@ 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"),
             };
@@ -626,8 +587,7 @@ 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,