5 files changed, 249 insertions, 289 deletions

diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index cda050a7d..10b8171be 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -802,7 +802,7 @@ impl Function {
         let krate = self.id.lookup(db.upcast()).container.module(db.upcast()).krate();
         let ret_type = &db.function_data(self.id).ret_type;
         let ctx = hir_ty::TyLoweringContext::new(db, &resolver);
-        let ty = Ty::from_hir_ext(&ctx, ret_type).0;
+        let ty = ctx.lower_ty(ret_type);
         Type::new_with_resolver_inner(db, krate, &resolver, ty)
     }
 
@@ -825,7 +825,7 @@ impl Function {
                 let ty = Type {
                     krate,
                     ty: InEnvironment {
-                        value: Ty::from_hir_ext(&ctx, type_ref).0,
+                        value: ctx.lower_ty(type_ref),
                         environment: environment.clone(),
                     },
                 };
@@ -1499,7 +1499,7 @@ impl Impl {
         let resolver = self.id.resolver(db.upcast());
         let krate = self.id.lookup(db.upcast()).container.krate();
         let ctx = hir_ty::TyLoweringContext::new(db, &resolver);
-        let ty = Ty::from_hir(&ctx, &impl_data.target_type);
+        let ty = ctx.lower_ty(&impl_data.target_type);
         Type::new_with_resolver_inner(db, krate, &resolver, ty)
     }
 
diff --git a/crates/hir_ty/src/infer.rs b/crates/hir_ty/src/infer.rs
index bc52f447d..8cf59821f 100644
--- a/crates/hir_ty/src/infer.rs
+++ b/crates/hir_ty/src/infer.rs
@@ -294,7 +294,7 @@ impl<'a> InferenceContext<'a> {
         // FIXME use right resolver for block
         let ctx = crate::lower::TyLoweringContext::new(self.db, &self.resolver)
             .with_impl_trait_mode(impl_trait_mode);
-        let ty = Ty::from_hir(&ctx, type_ref);
+        let ty = ctx.lower_ty(type_ref);
         let ty = self.insert_type_vars(ty);
         self.normalize_associated_types_in(ty)
     }
@@ -437,19 +437,19 @@ impl<'a> InferenceContext<'a> {
             };
         return match resolution {
             TypeNs::AdtId(AdtId::StructId(strukt)) => {
-                let substs = Ty::substs_from_path(&ctx, path, strukt.into(), true);
+                let substs = ctx.substs_from_path(path, strukt.into(), true);
                 let ty = self.db.ty(strukt.into());
                 let ty = self.insert_type_vars(ty.subst(&substs));
                 forbid_unresolved_segments((ty, Some(strukt.into())), unresolved)
             }
             TypeNs::AdtId(AdtId::UnionId(u)) => {
-                let substs = Ty::substs_from_path(&ctx, path, u.into(), true);
+                let substs = ctx.substs_from_path(path, u.into(), true);
                 let ty = self.db.ty(u.into());
                 let ty = self.insert_type_vars(ty.subst(&substs));
                 forbid_unresolved_segments((ty, Some(u.into())), unresolved)
             }
             TypeNs::EnumVariantId(var) => {
-                let substs = Ty::substs_from_path(&ctx, path, var.into(), true);
+                let substs = ctx.substs_from_path(path, var.into(), true);
                 let ty = self.db.ty(var.parent.into());
                 let ty = self.insert_type_vars(ty.subst(&substs));
                 forbid_unresolved_segments((ty, Some(var.into())), unresolved)
@@ -541,7 +541,7 @@ impl<'a> InferenceContext<'a> {
         let ctx = crate::lower::TyLoweringContext::new(self.db, &self.resolver)
             .with_impl_trait_mode(ImplTraitLoweringMode::Param);
         let param_tys =
-            data.params.iter().map(|type_ref| Ty::from_hir(&ctx, type_ref)).collect::<Vec<_>>();
+            data.params.iter().map(|type_ref| ctx.lower_ty(type_ref)).collect::<Vec<_>>();
         for (ty, pat) in param_tys.into_iter().zip(body.params.iter()) {
             let ty = self.insert_type_vars(ty);
             let ty = self.normalize_associated_types_in(ty);
diff --git a/crates/hir_ty/src/infer/path.rs b/crates/hir_ty/src/infer/path.rs
index c6681834c..af108fb6c 100644
--- a/crates/hir_ty/src/infer/path.rs
+++ b/crates/hir_ty/src/infer/path.rs
@@ -40,7 +40,7 @@ impl<'a> InferenceContext<'a> {
             let ty = self.make_ty(type_ref);
             let remaining_segments_for_ty = path.segments().take(path.segments().len() - 1);
             let ctx = crate::lower::TyLoweringContext::new(self.db, &resolver);
-            let (ty, _) = Ty::from_type_relative_path(&ctx, ty, None, remaining_segments_for_ty);
+            let (ty, _) = ctx.lower_ty_relative_path(ty, None, remaining_segments_for_ty);
             self.resolve_ty_assoc_item(
                 ty,
                 &path.segments().last().expect("path had at least one segment").name,
@@ -96,7 +96,7 @@ impl<'a> InferenceContext<'a> {
         // self_subst is just for the parent
         let parent_substs = self_subst.unwrap_or_else(Substs::empty);
         let ctx = crate::lower::TyLoweringContext::new(self.db, &self.resolver);
-        let substs = Ty::substs_from_path(&ctx, path, typable, true);
+        let substs = ctx.substs_from_path(path, typable, true);
         let full_substs = Substs::builder(substs.len())
             .use_parent_substs(&parent_substs)
             .fill(substs.0[parent_substs.len()..].iter().cloned())
@@ -126,7 +126,8 @@ impl<'a> InferenceContext<'a> {
                 let segment =
                     remaining_segments.last().expect("there should be at least one segment here");
                 let ctx = crate::lower::TyLoweringContext::new(self.db, &self.resolver);
-                let trait_ref = TraitRef::from_resolved_path(&ctx, trait_, resolved_segment, None);
+                let trait_ref =
+                    ctx.lower_trait_ref_from_resolved_path(trait_, resolved_segment, None);
                 self.resolve_trait_assoc_item(trait_ref, segment, id)
             }
             (def, _) => {
@@ -137,8 +138,7 @@ impl<'a> InferenceContext<'a> {
                 let remaining_segments_for_ty =
                     remaining_segments.take(remaining_segments.len() - 1);
                 let ctx = crate::lower::TyLoweringContext::new(self.db, &self.resolver);
-                let (ty, _) = Ty::from_partly_resolved_hir_path(
-                    &ctx,
+                let (ty, _) = ctx.lower_partly_resolved_path(
                     def,
                     resolved_segment,
                     remaining_segments_for_ty,
diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index 3b0706530..c32dca9d7 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -140,44 +140,45 @@ pub enum TypeParamLoweringMode {
     Variable,
 }
 
-impl Ty {
-    pub fn from_hir(ctx: &TyLoweringContext<'_>, type_ref: &TypeRef) -> Self {
-        Ty::from_hir_ext(ctx, type_ref).0
+impl<'a> TyLoweringContext<'a> {
+    pub fn lower_ty(&self, type_ref: &TypeRef) -> Ty {
+        self.lower_ty_ext(type_ref).0
     }
-    pub fn from_hir_ext(ctx: &TyLoweringContext<'_>, type_ref: &TypeRef) -> (Self, Option<TypeNs>) {
+
+    fn lower_ty_ext(&self, type_ref: &TypeRef) -> (Ty, Option<TypeNs>) {
         let mut res = None;
         let ty = match type_ref {
             TypeRef::Never => TyKind::Never.intern(&Interner),
             TypeRef::Tuple(inner) => {
-                let inner_tys: Arc<[Ty]> = inner.iter().map(|tr| Ty::from_hir(ctx, tr)).collect();
+                let inner_tys: Arc<[Ty]> = inner.iter().map(|tr| self.lower_ty(tr)).collect();
                 TyKind::Tuple(inner_tys.len(), Substs(inner_tys)).intern(&Interner)
             }
             TypeRef::Path(path) => {
-                let (ty, res_) = Ty::from_hir_path(ctx, path);
+                let (ty, res_) = self.lower_path(path);
                 res = res_;
                 ty
             }
             TypeRef::RawPtr(inner, mutability) => {
-                let inner_ty = Ty::from_hir(ctx, inner);
+                let inner_ty = self.lower_ty(inner);
                 TyKind::Raw(lower_to_chalk_mutability(*mutability), Substs::single(inner_ty))
                     .intern(&Interner)
             }
             TypeRef::Array(inner) => {
-                let inner_ty = Ty::from_hir(ctx, inner);
+                let inner_ty = self.lower_ty(inner);
                 TyKind::Array(Substs::single(inner_ty)).intern(&Interner)
             }
             TypeRef::Slice(inner) => {
-                let inner_ty = Ty::from_hir(ctx, inner);
+                let inner_ty = self.lower_ty(inner);
                 TyKind::Slice(Substs::single(inner_ty)).intern(&Interner)
             }
             TypeRef::Reference(inner, _, mutability) => {
-                let inner_ty = Ty::from_hir(ctx, inner);
+                let inner_ty = self.lower_ty(inner);
                 TyKind::Ref(lower_to_chalk_mutability(*mutability), Substs::single(inner_ty))
                     .intern(&Interner)
             }
             TypeRef::Placeholder => TyKind::Unknown.intern(&Interner),
             TypeRef::Fn(params, is_varargs) => {
-                let substs = Substs(params.iter().map(|tr| Ty::from_hir(ctx, tr)).collect());
+                let substs = Substs(params.iter().map(|tr| self.lower_ty(tr)).collect());
                 TyKind::Function(FnPointer {
                     num_args: substs.len() - 1,
                     sig: FnSig { variadic: *is_varargs },
@@ -188,25 +189,22 @@ impl Ty {
             TypeRef::DynTrait(bounds) => {
                 let self_ty =
                     TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(&Interner);
-                let predicates = ctx.with_shifted_in(DebruijnIndex::ONE, |ctx| {
-                    bounds
-                        .iter()
-                        .flat_map(|b| GenericPredicate::from_type_bound(ctx, b, self_ty.clone()))
-                        .collect()
+                let predicates = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
+                    bounds.iter().flat_map(|b| ctx.lower_type_bound(b, self_ty.clone())).collect()
                 });
                 TyKind::Dyn(predicates).intern(&Interner)
             }
             TypeRef::ImplTrait(bounds) => {
-                match ctx.impl_trait_mode {
+                match self.impl_trait_mode {
                     ImplTraitLoweringMode::Opaque => {
-                        let idx = ctx.impl_trait_counter.get();
-                        ctx.impl_trait_counter.set(idx + 1);
+                        let idx = self.impl_trait_counter.get();
+                        self.impl_trait_counter.set(idx + 1);
 
-                        assert!(idx as usize == ctx.opaque_type_data.borrow().len());
+                        assert!(idx as usize == self.opaque_type_data.borrow().len());
                         // this dance is to make sure the data is in the right
                         // place even if we encounter more opaque types while
                         // lowering the bounds
-                        ctx.opaque_type_data
+                        self.opaque_type_data
                             .borrow_mut()
                             .push(ReturnTypeImplTrait { bounds: Binders::new(1, Vec::new()) });
                         // We don't want to lower the bounds inside the binders
@@ -218,29 +216,29 @@ impl Ty {
                         // other, but separately. So if the `T` refers to a type
                         // parameter of the outer function, it's just one binder
                         // away instead of two.
-                        let actual_opaque_type_data = ctx
+                        let actual_opaque_type_data = self
                             .with_debruijn(DebruijnIndex::INNERMOST, |ctx| {
-                                ReturnTypeImplTrait::from_hir(ctx, &bounds)
+                                ctx.lower_impl_trait(&bounds)
                             });
-                        ctx.opaque_type_data.borrow_mut()[idx as usize] = actual_opaque_type_data;
+                        self.opaque_type_data.borrow_mut()[idx as usize] = actual_opaque_type_data;
 
-                        let func = match ctx.resolver.generic_def() {
+                        let func = match self.resolver.generic_def() {
                             Some(GenericDefId::FunctionId(f)) => f,
                             _ => panic!("opaque impl trait lowering in non-function"),
                         };
                         let impl_trait_id = ImplTraitId::ReturnTypeImplTrait(func, idx);
-                        let opaque_ty_id = ctx.db.intern_impl_trait_id(impl_trait_id).into();
-                        let generics = generics(ctx.db.upcast(), func.into());
-                        let parameters = Substs::bound_vars(&generics, ctx.in_binders);
+                        let opaque_ty_id = self.db.intern_impl_trait_id(impl_trait_id).into();
+                        let generics = generics(self.db.upcast(), func.into());
+                        let parameters = Substs::bound_vars(&generics, self.in_binders);
                         TyKind::Alias(AliasTy::Opaque(OpaqueTy { opaque_ty_id, parameters }))
                             .intern(&Interner)
                     }
                     ImplTraitLoweringMode::Param => {
-                        let idx = ctx.impl_trait_counter.get();
+                        let idx = self.impl_trait_counter.get();
                         // FIXME we're probably doing something wrong here
-                        ctx.impl_trait_counter.set(idx + count_impl_traits(type_ref) as u16);
-                        if let Some(def) = ctx.resolver.generic_def() {
-                            let generics = generics(ctx.db.upcast(), def);
+                        self.impl_trait_counter.set(idx + count_impl_traits(type_ref) as u16);
+                        if let Some(def) = self.resolver.generic_def() {
+                            let generics = generics(self.db.upcast(), def);
                             let param = generics
                                 .iter()
                                 .filter(|(_, data)| {
@@ -248,7 +246,7 @@ impl Ty {
                                 })
                                 .nth(idx as usize)
                                 .map_or(TyKind::Unknown, |(id, _)| {
-                                    TyKind::Placeholder(to_placeholder_idx(ctx.db, id))
+                                    TyKind::Placeholder(to_placeholder_idx(self.db, id))
                                 });
                             param.intern(&Interner)
                         } else {
@@ -256,18 +254,18 @@ impl Ty {
                         }
                     }
                     ImplTraitLoweringMode::Variable => {
-                        let idx = ctx.impl_trait_counter.get();
+                        let idx = self.impl_trait_counter.get();
                         // FIXME we're probably doing something wrong here
-                        ctx.impl_trait_counter.set(idx + count_impl_traits(type_ref) as u16);
+                        self.impl_trait_counter.set(idx + count_impl_traits(type_ref) as u16);
                         let (parent_params, self_params, list_params, _impl_trait_params) =
-                            if let Some(def) = ctx.resolver.generic_def() {
-                                let generics = generics(ctx.db.upcast(), def);
+                            if let Some(def) = self.resolver.generic_def() {
+                                let generics = generics(self.db.upcast(), def);
                                 generics.provenance_split()
                             } else {
                                 (0, 0, 0, 0)
                             };
                         TyKind::BoundVar(BoundVar::new(
-                            ctx.in_binders,
+                            self.in_binders,
                             idx as usize + parent_params + self_params + list_params,
                         ))
                         .intern(&Interner)
@@ -286,7 +284,7 @@ impl Ty {
     /// This is only for `generic_predicates_for_param`, where we can't just
     /// lower the self types of the predicates since that could lead to cycles.
     /// So we just check here if the `type_ref` resolves to a generic param, and which.
-    fn from_hir_only_param(ctx: &TyLoweringContext<'_>, type_ref: &TypeRef) -> Option<TypeParamId> {
+    fn lower_ty_only_param(&self, type_ref: &TypeRef) -> Option<TypeParamId> {
         let path = match type_ref {
             TypeRef::Path(path) => path,
             _ => return None,
@@ -298,7 +296,7 @@ impl Ty {
             return None;
         }
         let resolution =
-            match ctx.resolver.resolve_path_in_type_ns(ctx.db.upcast(), path.mod_path()) {
+            match self.resolver.resolve_path_in_type_ns(self.db.upcast(), path.mod_path()) {
                 Some((it, None)) => it,
                 _ => return None,
             };
@@ -309,8 +307,8 @@ impl Ty {
         }
     }
 
-    pub(crate) fn from_type_relative_path(
-        ctx: &TyLoweringContext<'_>,
+    pub(crate) fn lower_ty_relative_path(
+        &self,
         ty: Ty,
         // We need the original resolution to lower `Self::AssocTy` correctly
         res: Option<TypeNs>,
@@ -319,7 +317,7 @@ impl Ty {
         if remaining_segments.len() == 1 {
             // resolve unselected assoc types
             let segment = remaining_segments.first().unwrap();
-            (Ty::select_associated_type(ctx, res, segment), None)
+            (self.select_associated_type(res, segment), None)
         } else if remaining_segments.len() > 1 {
             // FIXME report error (ambiguous associated type)
             (TyKind::Unknown.intern(&Interner), None)
@@ -328,8 +326,8 @@ impl Ty {
         }
     }
 
-    pub(crate) fn from_partly_resolved_hir_path(
-        ctx: &TyLoweringContext<'_>,
+    pub(crate) fn lower_partly_resolved_path(
+        &self,
         resolution: TypeNs,
         resolved_segment: PathSegment<'_>,
         remaining_segments: PathSegments<'_>,
@@ -347,11 +345,11 @@ impl Ty {
                     None
                 };
                 let trait_ref =
-                    TraitRef::from_resolved_path(ctx, trait_, resolved_segment, self_ty);
+                    self.lower_trait_ref_from_resolved_path(trait_, resolved_segment, self_ty);
                 let ty = if remaining_segments.len() == 1 {
                     let segment = remaining_segments.first().unwrap();
                     let found = associated_type_by_name_including_super_traits(
-                        ctx.db,
+                        self.db,
                         trait_ref,
                         &segment.name,
                     );
@@ -380,68 +378,66 @@ impl Ty {
             }
             TypeNs::GenericParam(param_id) => {
                 let generics = generics(
-                    ctx.db.upcast(),
-                    ctx.resolver.generic_def().expect("generics in scope"),
+                    self.db.upcast(),
+                    self.resolver.generic_def().expect("generics in scope"),
                 );
-                match ctx.type_param_mode {
+                match self.type_param_mode {
                     TypeParamLoweringMode::Placeholder => {
-                        TyKind::Placeholder(to_placeholder_idx(ctx.db, param_id))
+                        TyKind::Placeholder(to_placeholder_idx(self.db, param_id))
                     }
                     TypeParamLoweringMode::Variable => {
                         let idx = generics.param_idx(param_id).expect("matching generics");
-                        TyKind::BoundVar(BoundVar::new(ctx.in_binders, idx))
+                        TyKind::BoundVar(BoundVar::new(self.in_binders, idx))
                     }
                 }
                 .intern(&Interner)
             }
             TypeNs::SelfType(impl_id) => {
-                let generics = generics(ctx.db.upcast(), impl_id.into());
-                let substs = match ctx.type_param_mode {
+                let generics = generics(self.db.upcast(), impl_id.into());
+                let substs = match self.type_param_mode {
                     TypeParamLoweringMode::Placeholder => {
-                        Substs::type_params_for_generics(ctx.db, &generics)
+                        Substs::type_params_for_generics(self.db, &generics)
                     }
                     TypeParamLoweringMode::Variable => {
-                        Substs::bound_vars(&generics, ctx.in_binders)
+                        Substs::bound_vars(&generics, self.in_binders)
                     }
                 };
-                ctx.db.impl_self_ty(impl_id).subst(&substs)
+                self.db.impl_self_ty(impl_id).subst(&substs)
             }
             TypeNs::AdtSelfType(adt) => {
-                let generics = generics(ctx.db.upcast(), adt.into());
-                let substs = match ctx.type_param_mode {
+                let generics = generics(self.db.upcast(), adt.into());
+                let substs = match self.type_param_mode {
                     TypeParamLoweringMode::Placeholder => {
-                        Substs::type_params_for_generics(ctx.db, &generics)
+                        Substs::type_params_for_generics(self.db, &generics)
                     }
                     TypeParamLoweringMode::Variable => {
-                        Substs::bound_vars(&generics, ctx.in_binders)
+                        Substs::bound_vars(&generics, self.in_binders)
                     }
                 };
-                ctx.db.ty(adt.into()).subst(&substs)
+                self.db.ty(adt.into()).subst(&substs)
             }
 
-            TypeNs::AdtId(it) => {
-                Ty::from_hir_path_inner(ctx, resolved_segment, it.into(), infer_args)
-            }
+            TypeNs::AdtId(it) => self.lower_path_inner(resolved_segment, it.into(), infer_args),
             TypeNs::BuiltinType(it) => {
-                Ty::from_hir_path_inner(ctx, resolved_segment, it.into(), infer_args)
+                self.lower_path_inner(resolved_segment, it.into(), infer_args)
             }
             TypeNs::TypeAliasId(it) => {
-                Ty::from_hir_path_inner(ctx, resolved_segment, it.into(), infer_args)
+                self.lower_path_inner(resolved_segment, it.into(), infer_args)
             }
             // FIXME: report error
             TypeNs::EnumVariantId(_) => return (TyKind::Unknown.intern(&Interner), None),
         };
-        Ty::from_type_relative_path(ctx, ty, Some(resolution), remaining_segments)
+        self.lower_ty_relative_path(ty, Some(resolution), remaining_segments)
     }
 
-    pub(crate) fn from_hir_path(ctx: &TyLoweringContext<'_>, path: &Path) -> (Ty, Option<TypeNs>) {
+    pub(crate) fn lower_path(&self, path: &Path) -> (Ty, Option<TypeNs>) {
         // Resolve the path (in type namespace)
         if let Some(type_ref) = path.type_anchor() {
-            let (ty, res) = Ty::from_hir_ext(ctx, &type_ref);
-            return Ty::from_type_relative_path(ctx, ty, res, path.segments());
+            let (ty, res) = self.lower_ty_ext(&type_ref);
+            return self.lower_ty_relative_path(ty, res, path.segments());
         }
         let (resolution, remaining_index) =
-            match ctx.resolver.resolve_path_in_type_ns(ctx.db.upcast(), path.mod_path()) {
+            match self.resolver.resolve_path_in_type_ns(self.db.upcast(), path.mod_path()) {
                 Some(it) => it,
                 None => return (TyKind::Unknown.intern(&Interner), None),
             };
@@ -452,31 +448,23 @@ impl Ty {
             ),
             Some(i) => (path.segments().get(i - 1).unwrap(), path.segments().skip(i)),
         };
-        Ty::from_partly_resolved_hir_path(
-            ctx,
-            resolution,
-            resolved_segment,
-            remaining_segments,
-            false,
-        )
+        self.lower_partly_resolved_path(resolution, resolved_segment, remaining_segments, false)
     }
 
-    fn select_associated_type(
-        ctx: &TyLoweringContext<'_>,
-        res: Option<TypeNs>,
-        segment: PathSegment<'_>,
-    ) -> Ty {
+    fn select_associated_type(&self, res: Option<TypeNs>, segment: PathSegment<'_>) -> Ty {
         if let Some(res) = res {
-            let ty =
-                associated_type_shorthand_candidates(ctx.db, res, move |name, t, associated_ty| {
+            let ty = associated_type_shorthand_candidates(
+                self.db,
+                res,
+                move |name, t, associated_ty| {
                     if name == segment.name {
-                        let substs = match ctx.type_param_mode {
+                        let substs = match self.type_param_mode {
                             TypeParamLoweringMode::Placeholder => {
                                 // if we're lowering to placeholders, we have to put
                                 // them in now
                                 let s = Substs::type_params(
-                                    ctx.db,
-                                    ctx.resolver.generic_def().expect(
+                                    self.db,
+                                    self.resolver.generic_def().expect(
                                         "there should be generics if there's a generic param",
                                     ),
                                 );
@@ -486,7 +474,7 @@ impl Ty {
                         };
                         // We need to shift in the bound vars, since
                         // associated_type_shorthand_candidates does not do that
-                        let substs = substs.shift_bound_vars(ctx.in_binders);
+                        let substs = substs.shift_bound_vars(self.in_binders);
                         // FIXME handle type parameters on the segment
                         return Some(
                             TyKind::Alias(AliasTy::Projection(ProjectionTy {
@@ -498,7 +486,8 @@ impl Ty {
                     }
 
                     None
-                });
+                },
+            );
 
             ty.unwrap_or(TyKind::Unknown.intern(&Interner))
         } else {
@@ -506,8 +495,8 @@ impl Ty {
         }
     }
 
-    fn from_hir_path_inner(
-        ctx: &TyLoweringContext<'_>,
+    fn lower_path_inner(
+        &self,
         segment: PathSegment<'_>,
         typeable: TyDefId,
         infer_args: bool,
@@ -517,14 +506,14 @@ impl Ty {
             TyDefId::AdtId(it) => Some(it.into()),
             TyDefId::TypeAliasId(it) => Some(it.into()),
         };
-        let substs = substs_from_path_segment(ctx, segment, generic_def, infer_args);
-        ctx.db.ty(typeable).subst(&substs)
+        let substs = self.substs_from_path_segment(segment, generic_def, infer_args);
+        self.db.ty(typeable).subst(&substs)
     }
 
     /// Collect generic arguments from a path into a `Substs`. See also
     /// `create_substs_for_ast_path` and `def_to_ty` in rustc.
     pub(super) fn substs_from_path(
-        ctx: &TyLoweringContext<'_>,
+        &self,
         path: &Path,
         // Note that we don't call `db.value_type(resolved)` here,
         // `ValueTyDefId` is just a convenient way to pass generics and
@@ -554,145 +543,137 @@ impl Ty {
                 (segment, Some(var.parent.into()))
             }
         };
-        substs_from_path_segment(ctx, segment, generic_def, infer_args)
+        self.substs_from_path_segment(segment, generic_def, infer_args)
     }
-}
 
-fn substs_from_path_segment(
-    ctx: &TyLoweringContext<'_>,
-    segment: PathSegment<'_>,
-    def_generic: Option<GenericDefId>,
-    infer_args: bool,
-) -> Substs {
-    let mut substs = Vec::new();
-    let def_generics = def_generic.map(|def| generics(ctx.db.upcast(), def));
+    fn substs_from_path_segment(
+        &self,
+        segment: PathSegment<'_>,
+        def_generic: Option<GenericDefId>,
+        infer_args: bool,
+    ) -> Substs {
+        let mut substs = Vec::new();
+        let def_generics = def_generic.map(|def| generics(self.db.upcast(), def));
 
-    let (parent_params, self_params, type_params, impl_trait_params) =
-        def_generics.map_or((0, 0, 0, 0), |g| g.provenance_split());
-    let total_len = parent_params + self_params + type_params + impl_trait_params;
+        let (parent_params, self_params, type_params, impl_trait_params) =
+            def_generics.map_or((0, 0, 0, 0), |g| g.provenance_split());
+        let total_len = parent_params + self_params + type_params + impl_trait_params;
 
-    substs.extend(iter::repeat(TyKind::Unknown.intern(&Interner)).take(parent_params));
+        substs.extend(iter::repeat(TyKind::Unknown.intern(&Interner)).take(parent_params));
 
-    let mut had_explicit_type_args = false;
+        let mut had_explicit_type_args = false;
 
-    if let Some(generic_args) = &segment.args_and_bindings {
-        if !generic_args.has_self_type {
-            substs.extend(iter::repeat(TyKind::Unknown.intern(&Interner)).take(self_params));
-        }
-        let expected_num =
-            if generic_args.has_self_type { self_params + type_params } else { type_params };
-        let skip = if generic_args.has_self_type && self_params == 0 { 1 } else { 0 };
-        // if args are provided, it should be all of them, but we can't rely on that
-        for arg in generic_args
-            .args
-            .iter()
-            .filter(|arg| matches!(arg, GenericArg::Type(_)))
-            .skip(skip)
-            .take(expected_num)
-        {
-            match arg {
-                GenericArg::Type(type_ref) => {
-                    had_explicit_type_args = true;
-                    let ty = Ty::from_hir(ctx, type_ref);
-                    substs.push(ty);
+        if let Some(generic_args) = &segment.args_and_bindings {
+            if !generic_args.has_self_type {
+                substs.extend(iter::repeat(TyKind::Unknown.intern(&Interner)).take(self_params));
+            }
+            let expected_num =
+                if generic_args.has_self_type { self_params + type_params } else { type_params };
+            let skip = if generic_args.has_self_type && self_params == 0 { 1 } else { 0 };
+            // if args are provided, it should be all of them, but we can't rely on that
+            for arg in generic_args
+                .args
+                .iter()
+                .filter(|arg| matches!(arg, GenericArg::Type(_)))
+                .skip(skip)
+                .take(expected_num)
+            {
+                match arg {
+                    GenericArg::Type(type_ref) => {
+                        had_explicit_type_args = true;
+                        let ty = self.lower_ty(type_ref);
+                        substs.push(ty);
+                    }
+                    GenericArg::Lifetime(_) => {}
                 }
-                GenericArg::Lifetime(_) => {}
             }
         }
-    }
 
-    // handle defaults. In expression or pattern path segments without
-    // explicitly specified type arguments, missing type arguments are inferred
-    // (i.e. defaults aren't used).
-    if !infer_args || had_explicit_type_args {
-        if let Some(def_generic) = def_generic {
-            let defaults = ctx.db.generic_defaults(def_generic);
-            assert_eq!(total_len, defaults.len());
-
-            for default_ty in defaults.iter().skip(substs.len()) {
-                // each default can depend on the previous parameters
-                let substs_so_far = Substs(substs.clone().into());
-                substs.push(default_ty.clone().subst(&substs_so_far));
+        // handle defaults. In expression or pattern path segments without
+        // explicitly specified type arguments, missing type arguments are inferred
+        // (i.e. defaults aren't used).
+        if !infer_args || had_explicit_type_args {
+            if let Some(def_generic) = def_generic {
+                let defaults = self.db.generic_defaults(def_generic);
+                assert_eq!(total_len, defaults.len());
+
+                for default_ty in defaults.iter().skip(substs.len()) {
+                    // each default can depend on the previous parameters
+                    let substs_so_far = Substs(substs.clone().into());
+                    substs.push(default_ty.clone().subst(&substs_so_far));
+                }
             }
         }
-    }
 
-    // add placeholders for args that were not provided
-    // FIXME: emit diagnostics in contexts where this is not allowed
-    for _ in substs.len()..total_len {
-        substs.push(TyKind::Unknown.intern(&Interner));
-    }
-    assert_eq!(substs.len(), total_len);
+        // add placeholders for args that were not provided
+        // FIXME: emit diagnostics in contexts where this is not allowed
+        for _ in substs.len()..total_len {
+            substs.push(TyKind::Unknown.intern(&Interner));
+        }
+        assert_eq!(substs.len(), total_len);
 
-    Substs(substs.into())
-}
+        Substs(substs.into())
+    }
 
-impl TraitRef {
-    fn from_path(
-        ctx: &TyLoweringContext<'_>,
+    fn lower_trait_ref_from_path(
+        &self,
         path: &Path,
         explicit_self_ty: Option<Ty>,
-    ) -> Option<Self> {
+    ) -> Option<TraitRef> {
         let resolved =
-            match ctx.resolver.resolve_path_in_type_ns_fully(ctx.db.upcast(), path.mod_path())? {
+            match self.resolver.resolve_path_in_type_ns_fully(self.db.upcast(), path.mod_path())? {
                 TypeNs::TraitId(tr) => tr,
                 _ => return None,
             };
         let segment = path.segments().last().expect("path should have at least one segment");
-        Some(TraitRef::from_resolved_path(ctx, resolved, segment, explicit_self_ty))
+        Some(self.lower_trait_ref_from_resolved_path(resolved, segment, explicit_self_ty))
     }
 
-    pub(crate) fn from_resolved_path(
-        ctx: &TyLoweringContext<'_>,
+    pub(crate) fn lower_trait_ref_from_resolved_path(
+        &self,
         resolved: TraitId,
         segment: PathSegment<'_>,
         explicit_self_ty: Option<Ty>,
-    ) -> Self {
-        let mut substs = TraitRef::substs_from_path(ctx, segment, resolved);
+    ) -> TraitRef {
+        let mut substs = self.trait_ref_substs_from_path(segment, resolved);
         if let Some(self_ty) = explicit_self_ty {
             make_mut_slice(&mut substs.0)[0] = self_ty;
         }
         TraitRef { trait_: resolved, substs }
     }
 
-    fn from_hir(
-        ctx: &TyLoweringContext<'_>,
+    fn lower_trait_ref(
+        &self,
         type_ref: &TypeRef,
         explicit_self_ty: Option<Ty>,
-    ) -> Option<Self> {
+    ) -> Option<TraitRef> {
         let path = match type_ref {
             TypeRef::Path(path) => path,
             _ => return None,
         };
-        TraitRef::from_path(ctx, path, explicit_self_ty)
+        self.lower_trait_ref_from_path(path, explicit_self_ty)
     }
 
-    fn substs_from_path(
-        ctx: &TyLoweringContext<'_>,
-        segment: PathSegment<'_>,
-        resolved: TraitId,
-    ) -> Substs {
-        substs_from_path_segment(ctx, segment, Some(resolved.into()), false)
+    fn trait_ref_substs_from_path(&self, segment: PathSegment<'_>, resolved: TraitId) -> Substs {
+        self.substs_from_path_segment(segment, Some(resolved.into()), false)
     }
-}
 
-impl GenericPredicate {
-    pub(crate) fn from_where_predicate<'a>(
-        ctx: &'a TyLoweringContext<'a>,
+    pub(crate) fn lower_where_predicate(
+        &'a self,
         where_predicate: &'a WherePredicate,
     ) -> impl Iterator<Item = GenericPredicate> + 'a {
         match where_predicate {
             WherePredicate::ForLifetime { target, bound, .. }
             | WherePredicate::TypeBound { target, bound } => {
                 let self_ty = match target {
-                    WherePredicateTypeTarget::TypeRef(type_ref) => Ty::from_hir(ctx, type_ref),
+                    WherePredicateTypeTarget::TypeRef(type_ref) => self.lower_ty(type_ref),
                     WherePredicateTypeTarget::TypeParam(param_id) => {
-                        let generic_def = ctx.resolver.generic_def().expect("generics in scope");
-                        let generics = generics(ctx.db.upcast(), generic_def);
+                        let generic_def = self.resolver.generic_def().expect("generics in scope");
+                        let generics = generics(self.db.upcast(), generic_def);
                         let param_id =
                             hir_def::TypeParamId { parent: generic_def, local_id: *param_id };
-                        let placeholder = to_placeholder_idx(ctx.db, param_id);
-                        match ctx.type_param_mode {
+                        let placeholder = to_placeholder_idx(self.db, param_id);
+                        match self.type_param_mode {
                             TypeParamLoweringMode::Placeholder => TyKind::Placeholder(placeholder),
                             TypeParamLoweringMode::Variable => {
                                 let idx = generics.param_idx(param_id).expect("matching generics");
@@ -702,23 +683,21 @@ impl GenericPredicate {
                         .intern(&Interner)
                     }
                 };
-                GenericPredicate::from_type_bound(ctx, bound, self_ty)
-                    .collect::<Vec<_>>()
-                    .into_iter()
+                self.lower_type_bound(bound, self_ty).collect::<Vec<_>>().into_iter()
             }
             WherePredicate::Lifetime { .. } => vec![].into_iter(),
         }
     }
 
-    pub(crate) fn from_type_bound<'a>(
-        ctx: &'a TyLoweringContext<'a>,
+    pub(crate) fn lower_type_bound(
+        &'a self,
         bound: &'a TypeBound,
         self_ty: Ty,
     ) -> impl Iterator<Item = GenericPredicate> + 'a {
         let mut bindings = None;
         let trait_ref = match bound {
             TypeBound::Path(path) => {
-                bindings = TraitRef::from_path(ctx, path, Some(self_ty));
+                bindings = self.lower_trait_ref_from_path(path, Some(self_ty));
                 Some(
                     bindings.clone().map_or(GenericPredicate::Error, GenericPredicate::Implemented),
                 )
@@ -729,68 +708,62 @@ impl GenericPredicate {
         trait_ref.into_iter().chain(
             bindings
                 .into_iter()
-                .flat_map(move |tr| assoc_type_bindings_from_type_bound(ctx, bound, tr)),
+                .flat_map(move |tr| self.assoc_type_bindings_from_type_bound(bound, tr)),
         )
     }
-}
 
-fn assoc_type_bindings_from_type_bound<'a>(
-    ctx: &'a TyLoweringContext<'a>,
-    bound: &'a TypeBound,
-    trait_ref: TraitRef,
-) -> impl Iterator<Item = GenericPredicate> + 'a {
-    let last_segment = match bound {
-        TypeBound::Path(path) => path.segments().last(),
-        TypeBound::Error | TypeBound::Lifetime(_) => None,
-    };
-    last_segment
-        .into_iter()
-        .flat_map(|segment| segment.args_and_bindings.into_iter())
-        .flat_map(|args_and_bindings| args_and_bindings.bindings.iter())
-        .flat_map(move |binding| {
-            let found = associated_type_by_name_including_super_traits(
-                ctx.db,
-                trait_ref.clone(),
-                &binding.name,
-            );
-            let (super_trait_ref, associated_ty) = match found {
-                None => return SmallVec::<[GenericPredicate; 1]>::new(),
-                Some(t) => t,
-            };
-            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(),
-            );
-            if let Some(type_ref) = &binding.type_ref {
-                let ty = Ty::from_hir(ctx, type_ref);
-                let projection_predicate =
-                    ProjectionPredicate { projection_ty: projection_ty.clone(), ty };
-                preds.push(GenericPredicate::Projection(projection_predicate));
-            }
-            for bound in &binding.bounds {
-                preds.extend(GenericPredicate::from_type_bound(
-                    ctx,
-                    bound,
-                    TyKind::Alias(AliasTy::Projection(projection_ty.clone())).intern(&Interner),
-                ));
-            }
-            preds
-        })
-}
+    fn assoc_type_bindings_from_type_bound(
+        &'a self,
+        bound: &'a TypeBound,
+        trait_ref: TraitRef,
+    ) -> impl Iterator<Item = GenericPredicate> + 'a {
+        let last_segment = match bound {
+            TypeBound::Path(path) => path.segments().last(),
+            TypeBound::Error | TypeBound::Lifetime(_) => None,
+        };
+        last_segment
+            .into_iter()
+            .flat_map(|segment| segment.args_and_bindings.into_iter())
+            .flat_map(|args_and_bindings| args_and_bindings.bindings.iter())
+            .flat_map(move |binding| {
+                let found = associated_type_by_name_including_super_traits(
+                    self.db,
+                    trait_ref.clone(),
+                    &binding.name,
+                );
+                let (super_trait_ref, associated_ty) = match found {
+                    None => return SmallVec::<[GenericPredicate; 1]>::new(),
+                    Some(t) => t,
+                };
+                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(),
+                );
+                if let Some(type_ref) = &binding.type_ref {
+                    let ty = self.lower_ty(type_ref);
+                    let projection_predicate =
+                        ProjectionPredicate { projection_ty: projection_ty.clone(), ty };
+                    preds.push(GenericPredicate::Projection(projection_predicate));
+                }
+                for bound in &binding.bounds {
+                    preds.extend(self.lower_type_bound(
+                        bound,
+                        TyKind::Alias(AliasTy::Projection(projection_ty.clone())).intern(&Interner),
+                    ));
+                }
+                preds
+            })
+    }
 
-impl ReturnTypeImplTrait {
-    fn from_hir(ctx: &TyLoweringContext, bounds: &[TypeBound]) -> Self {
+    fn lower_impl_trait(&self, bounds: &[TypeBound]) -> ReturnTypeImplTrait {
         cov_mark::hit!(lower_rpit);
         let self_ty =
             TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(&Interner);
-        let predicates = ctx.with_shifted_in(DebruijnIndex::ONE, |ctx| {
-            bounds
-                .iter()
-                .flat_map(|b| GenericPredicate::from_type_bound(ctx, b, self_ty.clone()))
-                .collect()
+        let predicates = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
+            bounds.iter().flat_map(|b| ctx.lower_type_bound(b, self_ty.clone())).collect()
         });
         ReturnTypeImplTrait { bounds: Binders::new(1, predicates) }
     }
@@ -886,7 +859,7 @@ pub(crate) fn field_types_query(
     let ctx =
         TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
     for (field_id, field_data) in var_data.fields().iter() {
-        res.insert(field_id, Binders::new(generics.len(), Ty::from_hir(&ctx, &field_data.type_ref)))
+        res.insert(field_id, Binders::new(generics.len(), ctx.lower_ty(&field_data.type_ref)))
     }
     Arc::new(res)
 }
@@ -914,16 +887,13 @@ pub(crate) fn generic_predicates_for_param_query(
             WherePredicate::ForLifetime { target, .. }
             | WherePredicate::TypeBound { target, .. } => match target {
                 WherePredicateTypeTarget::TypeRef(type_ref) => {
-                    Ty::from_hir_only_param(&ctx, type_ref) == Some(param_id)
+                    ctx.lower_ty_only_param(type_ref) == Some(param_id)
                 }
                 WherePredicateTypeTarget::TypeParam(local_id) => *local_id == param_id.local_id,
             },
             WherePredicate::Lifetime { .. } => false,
         })
-        .flat_map(|pred| {
-            GenericPredicate::from_where_predicate(&ctx, pred)
-                .map(|p| Binders::new(generics.len(), p))
-        })
+        .flat_map(|pred| ctx.lower_where_predicate(pred).map(|p| Binders::new(generics.len(), p)))
         .collect()
 }
 
@@ -945,7 +915,7 @@ pub(crate) fn trait_environment_query(
     let mut traits_in_scope = Vec::new();
     let mut clauses = Vec::new();
     for pred in resolver.where_predicates_in_scope() {
-        for pred in GenericPredicate::from_where_predicate(&ctx, pred) {
+        for pred in ctx.lower_where_predicate(pred) {
             if pred.is_error() {
                 continue;
             }
@@ -997,10 +967,7 @@ pub(crate) fn generic_predicates_query(
     let generics = generics(db.upcast(), def);
     resolver
         .where_predicates_in_scope()
-        .flat_map(|pred| {
-            GenericPredicate::from_where_predicate(&ctx, pred)
-                .map(|p| Binders::new(generics.len(), p))
-        })
+        .flat_map(|pred| ctx.lower_where_predicate(pred).map(|p| Binders::new(generics.len(), p)))
         .collect()
 }
 
@@ -1018,10 +985,8 @@ pub(crate) fn generic_defaults_query(
         .iter()
         .enumerate()
         .map(|(idx, (_, p))| {
-            let mut ty = p
-                .default
-                .as_ref()
-                .map_or(TyKind::Unknown.intern(&Interner), |t| Ty::from_hir(&ctx, t));
+            let mut ty =
+                p.default.as_ref().map_or(TyKind::Unknown.intern(&Interner), |t| ctx.lower_ty(t));
 
             // Each default can only refer to previous parameters.
             ty.walk_mut_binders(
@@ -1052,11 +1017,11 @@ fn fn_sig_for_fn(db: &dyn HirDatabase, def: FunctionId) -> PolyFnSig {
     let ctx_params = TyLoweringContext::new(db, &resolver)
         .with_impl_trait_mode(ImplTraitLoweringMode::Variable)
         .with_type_param_mode(TypeParamLoweringMode::Variable);
-    let params = data.params.iter().map(|tr| Ty::from_hir(&ctx_params, tr)).collect::<Vec<_>>();
+    let params = data.params.iter().map(|tr| (&ctx_params).lower_ty(tr)).collect::<Vec<_>>();
     let ctx_ret = TyLoweringContext::new(db, &resolver)
         .with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
         .with_type_param_mode(TypeParamLoweringMode::Variable);
-    let ret = Ty::from_hir(&ctx_ret, &data.ret_type);
+    let ret = (&ctx_ret).lower_ty(&data.ret_type);
     let generics = generics(db.upcast(), def.into());
     let num_binders = generics.len();
     Binders::new(num_binders, CallableSig::from_params_and_return(params, ret, data.is_varargs))
@@ -1081,7 +1046,7 @@ fn type_for_const(db: &dyn HirDatabase, def: ConstId) -> Binders<Ty> {
     let ctx =
         TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
 
-    Binders::new(generics.len(), Ty::from_hir(&ctx, &data.type_ref))
+    Binders::new(generics.len(), ctx.lower_ty(&data.type_ref))
 }
 
 /// Build the declared type of a static.
@@ -1090,7 +1055,7 @@ fn type_for_static(db: &dyn HirDatabase, def: StaticId) -> Binders<Ty> {
     let resolver = def.resolver(db.upcast());
     let ctx = TyLoweringContext::new(db, &resolver);
 
-    Binders::new(0, Ty::from_hir(&ctx, &data.type_ref))
+    Binders::new(0, ctx.lower_ty(&data.type_ref))
 }
 
 fn fn_sig_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> PolyFnSig {
@@ -1099,8 +1064,7 @@ fn fn_sig_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> PolyFnS
     let resolver = def.resolver(db.upcast());
     let ctx =
         TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
-    let params =
-        fields.iter().map(|(_, field)| Ty::from_hir(&ctx, &field.type_ref)).collect::<Vec<_>>();
+    let params = fields.iter().map(|(_, field)| ctx.lower_ty(&field.type_ref)).collect::<Vec<_>>();
     let ret = type_for_adt(db, def.into());
     Binders::new(ret.num_binders, CallableSig::from_params_and_return(params, ret.value, false))
 }
@@ -1126,8 +1090,7 @@ fn fn_sig_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId)
     let resolver = def.parent.resolver(db.upcast());
     let ctx =
         TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
-    let params =
-        fields.iter().map(|(_, field)| Ty::from_hir(&ctx, &field.type_ref)).collect::<Vec<_>>();
+    let params = fields.iter().map(|(_, field)| ctx.lower_ty(&field.type_ref)).collect::<Vec<_>>();
     let ret = type_for_adt(db, def.parent.into());
     Binders::new(ret.num_binders, CallableSig::from_params_and_return(params, ret.value, false))
 }
@@ -1163,7 +1126,7 @@ fn type_for_type_alias(db: &dyn HirDatabase, t: TypeAliasId) -> Binders<Ty> {
     } else {
         let substs = Substs::bound_vars(&generics, DebruijnIndex::INNERMOST);
         let type_ref = &db.type_alias_data(t).type_ref;
-        let inner = Ty::from_hir(&ctx, type_ref.as_ref().unwrap_or(&TypeRef::Error));
+        let inner = ctx.lower_ty(type_ref.as_ref().unwrap_or(&TypeRef::Error));
         Binders::new(substs.len(), inner)
     }
 }
@@ -1255,7 +1218,7 @@ pub(crate) fn impl_self_ty_query(db: &dyn HirDatabase, impl_id: ImplId) -> Binde
     let generics = generics(db.upcast(), impl_id.into());
     let ctx =
         TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
-    Binders::new(generics.len(), Ty::from_hir(&ctx, &impl_data.target_type))
+    Binders::new(generics.len(), ctx.lower_ty(&impl_data.target_type))
 }
 
 pub(crate) fn const_param_ty_query(db: &dyn HirDatabase, def: ConstParamId) -> Ty {
@@ -1264,7 +1227,7 @@ pub(crate) fn const_param_ty_query(db: &dyn HirDatabase, def: ConstParamId) -> T
     let resolver = def.parent.resolver(db.upcast());
     let ctx = TyLoweringContext::new(db, &resolver);
 
-    Ty::from_hir(&ctx, &data.ty)
+    ctx.lower_ty(&data.ty)
 }
 
 pub(crate) fn impl_self_ty_recover(
@@ -1283,10 +1246,7 @@ pub(crate) fn impl_trait_query(db: &dyn HirDatabase, impl_id: ImplId) -> Option<
         TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
     let self_ty = db.impl_self_ty(impl_id);
     let target_trait = impl_data.target_trait.as_ref()?;
-    Some(Binders::new(
-        self_ty.num_binders,
-        TraitRef::from_hir(&ctx, target_trait, Some(self_ty.value))?,
-    ))
+    Some(Binders::new(self_ty.num_binders, ctx.lower_trait_ref(target_trait, Some(self_ty.value))?))
 }
 
 pub(crate) fn return_type_impl_traits(
@@ -1299,7 +1259,7 @@ pub(crate) fn return_type_impl_traits(
     let ctx_ret = TyLoweringContext::new(db, &resolver)
         .with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
         .with_type_param_mode(TypeParamLoweringMode::Variable);
-    let _ret = Ty::from_hir(&ctx_ret, &data.ret_type);
+    let _ret = (&ctx_ret).lower_ty(&data.ret_type);
     let generics = generics(db.upcast(), def.into());
     let num_binders = generics.len();
     let return_type_impl_traits =
diff --git a/crates/hir_ty/src/traits/chalk.rs b/crates/hir_ty/src/traits/chalk.rs
index 1f3e1c07a..ef1e6b2df 100644
--- a/crates/hir_ty/src/traits/chalk.rs
+++ b/crates/hir_ty/src/traits/chalk.rs
@@ -401,7 +401,7 @@ pub(crate) fn associated_ty_data_query(
     let bounds = type_alias_data
         .bounds
         .iter()
-        .flat_map(|bound| GenericPredicate::from_type_bound(&ctx, bound, self_ty.clone()))
+        .flat_map(|bound| ctx.lower_type_bound(bound, self_ty.clone()))
         .filter_map(|pred| generic_predicate_to_inline_bound(db, &pred, &self_ty))
         .map(|bound| make_binders(bound.shifted_in(&Interner), 0))
         .collect();