15 files changed, 99 insertions, 73 deletions

diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index 95cfde61c..67ec8e82a 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -1462,7 +1462,7 @@ impl TypeParam {
             .into_iter()
             .filter_map(|pred| match &pred.value {
                 hir_ty::GenericPredicate::Implemented(trait_ref) => {
-                    Some(Trait::from(trait_ref.trait_))
+                    Some(Trait::from(trait_ref.hir_trait_id()))
                 }
                 _ => None,
             })
@@ -1757,8 +1757,8 @@ impl Type {
 
     pub fn impls_trait(&self, db: &dyn HirDatabase, trait_: Trait, args: &[Type]) -> bool {
         let trait_ref = hir_ty::TraitRef {
-            trait_: trait_.id,
-            substs: Substitution::build_for_def(db, trait_.id)
+            trait_id: hir_ty::to_chalk_trait_id(trait_.id),
+            substitution: Substitution::build_for_def(db, trait_.id)
                 .push(self.ty.value.clone())
                 .fill(args.iter().map(|t| t.ty.value.clone()))
                 .build(),
@@ -2023,7 +2023,7 @@ impl Type {
             it.into_iter()
                 .filter_map(|pred| match pred {
                     hir_ty::GenericPredicate::Implemented(trait_ref) => {
-                        Some(Trait::from(trait_ref.trait_))
+                        Some(Trait::from(trait_ref.hir_trait_id()))
                     }
                     _ => None,
                 })
@@ -2067,7 +2067,7 @@ impl Type {
                 match pred {
                     GenericPredicate::Implemented(trait_ref) => {
                         cb(type_.clone());
-                        walk_substs(db, type_, &trait_ref.substs, cb);
+                        walk_substs(db, type_, &trait_ref.substitution, cb);
                     }
                     _ => (),
                 }
diff --git a/crates/hir_ty/src/autoderef.rs b/crates/hir_ty/src/autoderef.rs
index bd2ff5d38..ad4e6f23b 100644
--- a/crates/hir_ty/src/autoderef.rs
+++ b/crates/hir_ty/src/autoderef.rs
@@ -12,7 +12,7 @@ use log::{info, warn};
 
 use crate::{
     db::HirDatabase,
-    to_assoc_type_id,
+    to_assoc_type_id, to_chalk_trait_id,
     traits::{InEnvironment, Solution},
     utils::generics,
     BoundVar, Canonical, DebruijnIndex, Interner, Obligation, Substitution, TraitRef, Ty, TyKind,
@@ -68,7 +68,8 @@ fn deref_by_trait(
         Substitution::build_for_generics(&generic_params).push(ty.value.value.clone()).build();
 
     // Check that the type implements Deref at all
-    let trait_ref = TraitRef { trait_: deref_trait, substs: parameters.clone() };
+    let trait_ref =
+        TraitRef { trait_id: to_chalk_trait_id(deref_trait), substitution: parameters.clone() };
     let implements_goal = Canonical {
         kinds: ty.value.kinds.clone(),
         value: InEnvironment {
diff --git a/crates/hir_ty/src/display.rs b/crates/hir_ty/src/display.rs
index 7ce0f864c..c6b4f37e5 100644
--- a/crates/hir_ty/src/display.rs
+++ b/crates/hir_ty/src/display.rs
@@ -344,7 +344,7 @@ impl HirDisplay for Ty {
                 };
 
                 if let [GenericPredicate::Implemented(trait_ref), _] = predicates.as_ref() {
-                    let trait_ = trait_ref.trait_;
+                    let trait_ = trait_ref.hir_trait_id();
                     if fn_traits(f.db.upcast(), trait_).any(|it| it == trait_) {
                         return write!(f, "{}", ty_display);
                     }
@@ -670,7 +670,7 @@ fn write_bounds_like_dyn_trait(
     for p in predicates.iter() {
         match p {
             GenericPredicate::Implemented(trait_ref) => {
-                let trait_ = trait_ref.trait_;
+                let trait_ = trait_ref.hir_trait_id();
                 if !is_fn_trait {
                     is_fn_trait = fn_traits(f.db.upcast(), trait_).any(|it| it == trait_);
                 }
@@ -685,7 +685,7 @@ fn write_bounds_like_dyn_trait(
                 // existential) here, which is the only thing that's
                 // possible in actual Rust, and hence don't print it
                 write!(f, "{}", f.db.trait_data(trait_).name)?;
-                if let [_, params @ ..] = &*trait_ref.substs.0 {
+                if let [_, params @ ..] = &*trait_ref.substitution.0 {
                     if is_fn_trait {
                         if let Some(args) = params.first().and_then(|it| it.as_tuple()) {
                             write!(f, "(")?;
@@ -745,16 +745,16 @@ impl TraitRef {
             return write!(f, "{}", TYPE_HINT_TRUNCATION);
         }
 
-        self.substs[0].hir_fmt(f)?;
+        self.substitution[0].hir_fmt(f)?;
         if use_as {
             write!(f, " as ")?;
         } else {
             write!(f, ": ")?;
         }
-        write!(f, "{}", f.db.trait_data(self.trait_).name)?;
-        if self.substs.len() > 1 {
+        write!(f, "{}", f.db.trait_data(self.hir_trait_id()).name)?;
+        if self.substitution.len() > 1 {
             write!(f, "<")?;
-            f.write_joined(&self.substs[1..], ", ")?;
+            f.write_joined(&self.substitution[1..], ", ")?;
             write!(f, ">")?;
         }
         Ok(())
diff --git a/crates/hir_ty/src/infer.rs b/crates/hir_ty/src/infer.rs
index 2610c9279..b6ae4fc65 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,
-    to_assoc_type_id, AliasTy, Interner, TyKind,
+    to_assoc_type_id, to_chalk_trait_id, AliasTy, Interner, TyKind,
 };
 
 pub(crate) use unify::unify;
@@ -394,7 +394,8 @@ impl<'a> InferenceContext<'a> {
                     .push(inner_ty)
                     .fill(params.iter().cloned())
                     .build();
-                let trait_ref = TraitRef { trait_, substs: substs.clone() };
+                let trait_ref =
+                    TraitRef { trait_id: to_chalk_trait_id(trait_), substitution: substs.clone() };
                 let projection = ProjectionPredicate {
                     ty: ty.clone(),
                     projection_ty: ProjectionTy {
diff --git a/crates/hir_ty/src/infer/coerce.rs b/crates/hir_ty/src/infer/coerce.rs
index b1f98c507..b86474ed4 100644
--- a/crates/hir_ty/src/infer/coerce.rs
+++ b/crates/hir_ty/src/infer/coerce.rs
@@ -8,7 +8,8 @@ use chalk_ir::{Mutability, TyVariableKind};
 use hir_def::lang_item::LangItemTarget;
 
 use crate::{
-    autoderef, traits::Solution, Interner, Obligation, Substitution, TraitRef, Ty, TyKind,
+    autoderef, to_chalk_trait_id, traits::Solution, Interner, Obligation, Substitution, TraitRef,
+    Ty, TyKind,
 };
 
 use super::{InEnvironment, InferenceContext};
@@ -140,7 +141,8 @@ impl<'a> InferenceContext<'a> {
             .push(from_ty.clone())
             .push(to_ty.clone())
             .build();
-        let trait_ref = TraitRef { trait_: coerce_unsized_trait, substs };
+        let trait_ref =
+            TraitRef { trait_id: to_chalk_trait_id(coerce_unsized_trait), substitution: substs };
         let goal = InEnvironment::new(self.trait_env.clone(), Obligation::Trait(trait_ref));
 
         let canonicalizer = self.canonicalizer();
diff --git a/crates/hir_ty/src/infer/expr.rs b/crates/hir_ty/src/infer/expr.rs
index 0be8c5a90..93548b6c0 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs
@@ -18,7 +18,7 @@ use crate::{
     lower::lower_to_chalk_mutability,
     method_resolution, op,
     primitive::{self, UintTy},
-    to_assoc_type_id,
+    to_assoc_type_id, to_chalk_trait_id,
     traits::{chalk::from_chalk, FnTrait, InEnvironment},
     utils::{generics, variant_data, Generics},
     AdtId, Binders, CallableDefId, FnPointer, FnSig, Interner, Obligation, Rawness, Scalar,
@@ -90,8 +90,10 @@ impl<'a> InferenceContext<'a> {
             Substitution::build_for_generics(&generic_params).push(ty.clone()).push(arg_ty).build();
 
         let trait_env = Arc::clone(&self.trait_env);
-        let implements_fn_trait =
-            Obligation::Trait(TraitRef { trait_: fn_once_trait, substs: substs.clone() });
+        let implements_fn_trait = Obligation::Trait(TraitRef {
+            trait_id: to_chalk_trait_id(fn_once_trait),
+            substitution: substs.clone(),
+        });
         let goal = self.canonicalizer().canonicalize_obligation(InEnvironment {
             value: implements_fn_trait.clone(),
             environment: trait_env,
@@ -948,7 +950,10 @@ impl<'a> InferenceContext<'a> {
                         // construct a TraitDef
                         let substs =
                             parameters.prefix(generics(self.db.upcast(), trait_.into()).len());
-                        self.obligations.push(Obligation::Trait(TraitRef { trait_, substs }));
+                        self.obligations.push(Obligation::Trait(TraitRef {
+                            trait_id: to_chalk_trait_id(trait_),
+                            substitution: substs,
+                        }));
                     }
                 }
                 CallableDefId::StructId(_) | CallableDefId::EnumVariantId(_) => {}
diff --git a/crates/hir_ty/src/infer/path.rs b/crates/hir_ty/src/infer/path.rs
index ea01d6238..e15135fc1 100644
--- a/crates/hir_ty/src/infer/path.rs
+++ b/crates/hir_ty/src/infer/path.rs
@@ -9,7 +9,9 @@ use hir_def::{
 };
 use hir_expand::name::Name;
 
-use crate::{method_resolution, Interner, Substitution, Ty, TyKind, ValueTyDefId};
+use crate::{
+    method_resolution, to_chalk_trait_id, Interner, Substitution, Ty, TyKind, ValueTyDefId,
+};
 
 use super::{ExprOrPatId, InferenceContext, TraitRef};
 
@@ -165,7 +167,7 @@ impl<'a> InferenceContext<'a> {
         segment: PathSegment<'_>,
         id: ExprOrPatId,
     ) -> Option<(ValueNs, Option<Substitution>)> {
-        let trait_ = trait_ref.trait_;
+        let trait_ = trait_ref.hir_trait_id();
         let item =
             self.db.trait_data(trait_).items.iter().map(|(_name, id)| (*id)).find_map(|item| {
                 match item {
@@ -200,7 +202,7 @@ impl<'a> InferenceContext<'a> {
         };
 
         self.write_assoc_resolution(id, item);
-        Some((def, Some(trait_ref.substs)))
+        Some((def, Some(trait_ref.substitution)))
     }
 
     fn resolve_ty_assoc_item(
@@ -255,8 +257,8 @@ impl<'a> InferenceContext<'a> {
                             .fill(std::iter::repeat_with(|| self.table.new_type_var()))
                             .build();
                         self.obligations.push(super::Obligation::Trait(TraitRef {
-                            trait_,
-                            substs: trait_substs.clone(),
+                            trait_id: to_chalk_trait_id(trait_),
+                            substitution: trait_substs.clone(),
                         }));
                         Some(trait_substs)
                     }
diff --git a/crates/hir_ty/src/infer/unify.rs b/crates/hir_ty/src/infer/unify.rs
index b2d4f67b3..f5ea09698 100644
--- a/crates/hir_ty/src/infer/unify.rs
+++ b/crates/hir_ty/src/infer/unify.rs
@@ -390,9 +390,9 @@ impl InferenceTable {
     ) -> bool {
         match (pred1, pred2) {
             (GenericPredicate::Implemented(tr1), GenericPredicate::Implemented(tr2))
-                if tr1.trait_ == tr2.trait_ =>
+                if tr1.trait_id == tr2.trait_id =>
             {
-                self.unify_substs(&tr1.substs, &tr2.substs, depth + 1)
+                self.unify_substs(&tr1.substitution, &tr2.substitution, depth + 1)
             }
             (GenericPredicate::Projection(proj1), GenericPredicate::Projection(proj2))
                 if proj1.projection_ty.associated_ty_id == proj2.projection_ty.associated_ty_id =>
diff --git a/crates/hir_ty/src/lib.rs b/crates/hir_ty/src/lib.rs
index 52b498ff7..3859dbfa1 100644
--- a/crates/hir_ty/src/lib.rs
+++ b/crates/hir_ty/src/lib.rs
@@ -58,6 +58,8 @@ pub type ClosureId = chalk_ir::ClosureId<Interner>;
 pub type OpaqueTyId = chalk_ir::OpaqueTyId<Interner>;
 pub type PlaceholderIndex = chalk_ir::PlaceholderIndex;
 
+pub type ChalkTraitId = chalk_ir::TraitId<Interner>;
+
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub enum Lifetime {
     Parameter(LifetimeParamId),
@@ -81,7 +83,10 @@ pub struct ProjectionTy {
 
 impl ProjectionTy {
     pub fn trait_ref(&self, db: &dyn HirDatabase) -> TraitRef {
-        TraitRef { trait_: self.trait_(db), substs: self.substitution.clone() }
+        TraitRef {
+            trait_id: to_chalk_trait_id(self.trait_(db)),
+            substitution: self.substitution.clone(),
+        }
     }
 
     fn trait_(&self, db: &dyn HirDatabase) -> TraitId {
@@ -493,23 +498,25 @@ impl<T: TypeWalk> TypeWalk for Binders<T> {
 }
 
 /// A trait with type parameters. This includes the `Self`, so this represents a concrete type implementing the trait.
-/// Name to be bikeshedded: TraitBound? TraitImplements?
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub struct TraitRef {
-    /// FIXME name?
-    pub trait_: TraitId,
-    pub substs: Substitution,
+    pub trait_id: ChalkTraitId,
+    pub substitution: Substitution,
 }
 
 impl TraitRef {
-    pub fn self_ty(&self) -> &Ty {
-        &self.substs[0]
+    pub fn self_type_parameter(&self) -> &Ty {
+        &self.substitution[0]
+    }
+
+    pub fn hir_trait_id(&self) -> TraitId {
+        from_chalk_trait_id(self.trait_id)
     }
 }
 
 impl TypeWalk for TraitRef {
     fn walk(&self, f: &mut impl FnMut(&Ty)) {
-        self.substs.walk(f);
+        self.substitution.walk(f);
     }
 
     fn walk_mut_binders(
@@ -517,7 +524,7 @@ impl TypeWalk for TraitRef {
         f: &mut impl FnMut(&mut Ty, DebruijnIndex),
         binders: DebruijnIndex,
     ) {
-        self.substs.walk_mut_binders(f, binders);
+        self.substitution.walk_mut_binders(f, binders);
     }
 }
 
@@ -784,7 +791,7 @@ impl Ty {
 
     /// If this is a `dyn Trait`, returns that trait.
     pub fn dyn_trait(&self) -> Option<TraitId> {
-        self.dyn_trait_ref().map(|it| it.trait_)
+        self.dyn_trait_ref().map(|it| it.trait_id).map(from_chalk_trait_id)
     }
 
     fn builtin_deref(&self) -> Option<Ty> {
@@ -868,8 +875,8 @@ impl Ty {
                             // Parameters will be walked outside, and projection predicate is not used.
                             // So just provide the Future trait.
                             let impl_bound = GenericPredicate::Implemented(TraitRef {
-                                trait_: future_trait,
-                                substs: Substitution::empty(),
+                                trait_id: to_chalk_trait_id(future_trait),
+                                substitution: Substitution::empty(),
                             });
                             Some(vec![impl_bound])
                         } else {
@@ -1158,3 +1165,11 @@ pub fn to_placeholder_idx(db: &dyn HirDatabase, id: TypeParamId) -> PlaceholderI
         idx: salsa::InternKey::as_intern_id(&interned_id).as_usize(),
     }
 }
+
+pub fn to_chalk_trait_id(id: TraitId) -> ChalkTraitId {
+    chalk_ir::TraitId(salsa::InternKey::as_intern_id(&id))
+}
+
+pub fn from_chalk_trait_id(id: ChalkTraitId) -> TraitId {
+    salsa::InternKey::from_intern_id(id.0)
+}
diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index 462882b2b..5d950a017 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -27,7 +27,7 @@ use stdx::impl_from;
 
 use crate::{
     db::HirDatabase,
-    to_assoc_type_id, to_placeholder_idx,
+    to_assoc_type_id, to_chalk_trait_id, to_placeholder_idx,
     traits::chalk::{Interner, ToChalk},
     utils::{
         all_super_trait_refs, associated_type_by_name_including_super_traits, generics,
@@ -360,7 +360,7 @@ impl<'a> TyLoweringContext<'a> {
                             // FIXME handle type parameters on the segment
                             TyKind::Alias(AliasTy::Projection(ProjectionTy {
                                 associated_ty_id: to_assoc_type_id(associated_ty),
-                                substitution: super_trait_ref.substs,
+                                substitution: super_trait_ref.substitution,
                             }))
                             .intern(&Interner)
                         }
@@ -470,9 +470,9 @@ impl<'a> TyLoweringContext<'a> {
                                         "there should be generics if there's a generic param",
                                     ),
                                 );
-                                t.substs.clone().subst_bound_vars(&s)
+                                t.substitution.clone().subst_bound_vars(&s)
                             }
-                            TypeParamLoweringMode::Variable => t.substs.clone(),
+                            TypeParamLoweringMode::Variable => t.substitution.clone(),
                         };
                         // We need to shift in the bound vars, since
                         // associated_type_shorthand_candidates does not do that
@@ -641,7 +641,7 @@ impl<'a> TyLoweringContext<'a> {
         if let Some(self_ty) = explicit_self_ty {
             substs.0[0] = self_ty;
         }
-        TraitRef { trait_: resolved, substs }
+        TraitRef { trait_id: to_chalk_trait_id(resolved), substitution: substs }
     }
 
     fn lower_trait_ref(
@@ -743,7 +743,7 @@ impl<'a> TyLoweringContext<'a> {
                 };
                 let projection_ty = ProjectionTy {
                     associated_ty_id: to_assoc_type_id(associated_ty),
-                    substitution: super_trait_ref.substs,
+                    substitution: super_trait_ref.substitution,
                 };
                 let mut preds = SmallVec::with_capacity(
                     binding.type_ref.as_ref().map_or(0, |_| 1) + binding.bounds.len(),
@@ -820,8 +820,8 @@ pub fn associated_type_shorthand_candidates<R>(
                     == TypeParamProvenance::TraitSelf
                 {
                     let trait_ref = TraitRef {
-                        trait_: trait_id,
-                        substs: Substitution::bound_vars(&generics, DebruijnIndex::INNERMOST),
+                        trait_id: to_chalk_trait_id(trait_id),
+                        substitution: Substitution::bound_vars(&generics, DebruijnIndex::INNERMOST),
                     };
                     traits_.push(trait_ref);
                 }
@@ -832,7 +832,7 @@ pub fn associated_type_shorthand_candidates<R>(
     };
 
     for t in traits_from_env.into_iter().flat_map(move |t| all_super_trait_refs(db, t)) {
-        let data = db.trait_data(t.trait_);
+        let data = db.trait_data(t.hir_trait_id());
 
         for (name, assoc_id) in &data.items {
             match assoc_id {
@@ -926,7 +926,7 @@ pub(crate) fn trait_environment_query(
                 continue;
             }
             if let GenericPredicate::Implemented(tr) = &pred {
-                traits_in_scope.push((tr.self_ty().clone(), tr.trait_));
+                traits_in_scope.push((tr.self_type_parameter().clone(), tr.hir_trait_id()));
             }
             let program_clause: chalk_ir::ProgramClause<Interner> =
                 pred.clone().to_chalk(db).cast(&Interner);
@@ -950,7 +950,7 @@ pub(crate) fn trait_environment_query(
         // inside consts or type aliases)
         cov_mark::hit!(trait_self_implements_self);
         let substs = Substitution::type_params(db, trait_id);
-        let trait_ref = TraitRef { trait_: trait_id, substs };
+        let trait_ref = TraitRef { trait_id: to_chalk_trait_id(trait_id), substitution: substs };
         let pred = GenericPredicate::Implemented(trait_ref);
         let program_clause: chalk_ir::ProgramClause<Interner> =
             pred.clone().to_chalk(db).cast(&Interner);
diff --git a/crates/hir_ty/src/method_resolution.rs b/crates/hir_ty/src/method_resolution.rs
index 943d3339b..01b78fb44 100644
--- a/crates/hir_ty/src/method_resolution.rs
+++ b/crates/hir_ty/src/method_resolution.rs
@@ -19,6 +19,7 @@ use crate::{
     db::HirDatabase,
     from_foreign_def_id,
     primitive::{self, FloatTy, IntTy, UintTy},
+    to_chalk_trait_id,
     utils::all_super_traits,
     AdtId, Canonical, DebruijnIndex, FnPointer, FnSig, ForeignDefId, InEnvironment, Interner,
     Scalar, Substitution, TraitEnvironment, TraitRef, Ty, TyKind, TypeWalk,
@@ -101,7 +102,7 @@ impl TraitImpls {
         for (_module_id, module_data) in crate_def_map.modules() {
             for impl_id in module_data.scope.impls() {
                 let target_trait = match db.impl_trait(impl_id) {
-                    Some(tr) => tr.value.trait_,
+                    Some(tr) => tr.value.hir_trait_id(),
                     None => continue,
                 };
                 let self_ty = db.impl_self_ty(impl_id);
@@ -773,7 +774,7 @@ fn generic_implements_goal(
         .fill_with_bound_vars(DebruijnIndex::INNERMOST, kinds.len())
         .build();
     kinds.extend(iter::repeat(chalk_ir::TyVariableKind::General).take(substs.len() - 1));
-    let trait_ref = TraitRef { trait_, substs };
+    let trait_ref = TraitRef { trait_id: to_chalk_trait_id(trait_), substitution: substs };
     let obligation = super::Obligation::Trait(trait_ref);
     Canonical { kinds: kinds.into(), value: InEnvironment::new(env, obligation) }
 }
diff --git a/crates/hir_ty/src/traits.rs b/crates/hir_ty/src/traits.rs
index 40eb1034e..a7287dea1 100644
--- a/crates/hir_ty/src/traits.rs
+++ b/crates/hir_ty/src/traits.rs
@@ -137,7 +137,7 @@ pub(crate) fn trait_solve_query(
     goal: Canonical<InEnvironment<Obligation>>,
 ) -> Option<Solution> {
     let _p = profile::span("trait_solve_query").detail(|| match &goal.value.value {
-        Obligation::Trait(it) => db.trait_data(it.trait_).name.to_string(),
+        Obligation::Trait(it) => db.trait_data(it.hir_trait_id()).name.to_string(),
         Obligation::Projection(_) => "projection".to_string(),
     });
     log::info!("trait_solve_query({})", goal.value.value.display(db));
diff --git a/crates/hir_ty/src/traits/chalk.rs b/crates/hir_ty/src/traits/chalk.rs
index bef6e7e9c..bac70f5aa 100644
--- a/crates/hir_ty/src/traits/chalk.rs
+++ b/crates/hir_ty/src/traits/chalk.rs
@@ -19,7 +19,7 @@ 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,
@@ -219,9 +219,9 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
                     // for<T> <Self> [Future<Self>, Future::Output<Self> = T]
                     //     ^1  ^0            ^0                    ^0      ^1
                     let impl_bound = GenericPredicate::Implemented(TraitRef {
-                        trait_: future_trait,
+                        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,
@@ -546,7 +546,7 @@ 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 +614,7 @@ 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());
diff --git a/crates/hir_ty/src/traits/chalk/mapping.rs b/crates/hir_ty/src/traits/chalk/mapping.rs
index d969527dc..0086ce1e9 100644
--- a/crates/hir_ty/src/traits/chalk/mapping.rs
+++ b/crates/hir_ty/src/traits/chalk/mapping.rs
@@ -239,15 +239,15 @@ 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 }
     }
 }
 
@@ -515,17 +515,16 @@ pub(super) fn generic_predicate_to_inline_bound(
     // 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 {
+            if &trait_ref.substitution[0] != self_ty {
                 // 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 };
+            let trait_bound = rust_ir::TraitBound { trait_id: trait_ref.trait_id, args_no_self };
             Some(rust_ir::InlineBound::TraitBound(trait_bound))
         }
         GenericPredicate::Projection(proj) => {
diff --git a/crates/hir_ty/src/utils.rs b/crates/hir_ty/src/utils.rs
index 7351e4e54..b66243d48 100644
--- a/crates/hir_ty/src/utils.rs
+++ b/crates/hir_ty/src/utils.rs
@@ -55,9 +55,9 @@ fn direct_super_trait_refs(db: &dyn HirDatabase, trait_ref: &TraitRef) -> Vec<Tr
     // lifetime problems, but since there usually shouldn't be more than a
     // few direct traits this should be fine (we could even use some kind of
     // SmallVec if performance is a concern)
-    let generic_params = db.generic_params(trait_ref.trait_.into());
+    let generic_params = db.generic_params(trait_ref.hir_trait_id().into());
     let trait_self = match generic_params.find_trait_self_param() {
-        Some(p) => TypeParamId { parent: trait_ref.trait_.into(), local_id: p },
+        Some(p) => TypeParamId { parent: trait_ref.hir_trait_id().into(), local_id: p },
         None => return Vec::new(),
     };
     db.generic_predicates_for_param(trait_self)
@@ -68,7 +68,7 @@ fn direct_super_trait_refs(db: &dyn HirDatabase, trait_ref: &TraitRef) -> Vec<Tr
                 _ => None,
             })
         })
-        .map(|pred| pred.subst(&trait_ref.substs))
+        .map(|pred| pred.subst(&trait_ref.substitution))
         .collect()
 }
 
@@ -108,7 +108,7 @@ pub(super) fn all_super_trait_refs(db: &dyn HirDatabase, trait_ref: TraitRef) ->
         // yeah this is quadratic, but trait hierarchies should be flat
         // enough that this doesn't matter
         for tt in direct_super_trait_refs(db, t) {
-            if !result.iter().any(|tr| tr.trait_ == tt.trait_) {
+            if !result.iter().any(|tr| tr.trait_id == tt.trait_id) {
                 result.push(tt);
             }
         }
@@ -123,7 +123,7 @@ pub(super) fn associated_type_by_name_including_super_traits(
     name: &Name,
 ) -> Option<(TraitRef, TypeAliasId)> {
     all_super_trait_refs(db, trait_ref).into_iter().find_map(|t| {
-        let assoc_type = db.trait_data(t.trait_).associated_type_by_name(name)?;
+        let assoc_type = db.trait_data(t.hir_trait_id()).associated_type_by_name(name)?;
         Some((t, assoc_type))
     })
 }