1 files changed, 16 insertions, 13 deletions

diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index b8b1400eb..e57d5970f 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -27,14 +27,14 @@ use stdx::impl_from;
 
 use crate::{
     db::HirDatabase,
-    to_assoc_type_id,
+    to_assoc_type_id, to_placeholder_idx,
     traits::chalk::{Interner, ToChalk},
     utils::{
         all_super_trait_refs, associated_type_by_name_including_super_traits, generics,
         make_mut_slice, variant_data,
     },
     AliasTy, Binders, BoundVar, CallableSig, DebruijnIndex, FnPointer, FnSig, GenericPredicate,
-    OpaqueTy, OpaqueTyId, PolyFnSig, ProjectionPredicate, ProjectionTy, ReturnTypeImplTrait,
+    ImplTraitId, OpaqueTy, PolyFnSig, ProjectionPredicate, ProjectionTy, ReturnTypeImplTrait,
     ReturnTypeImplTraits, Substs, TraitEnvironment, TraitRef, Ty, TyKind, TypeWalk,
 };
 
@@ -228,14 +228,12 @@ impl Ty {
                             Some(GenericDefId::FunctionId(f)) => f,
                             _ => panic!("opaque impl trait lowering in non-function"),
                         };
-                        let impl_trait_id = OpaqueTyId::ReturnTypeImplTrait(func, idx);
+                        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);
-                        TyKind::Alias(AliasTy::Opaque(OpaqueTy {
-                            opaque_ty_id: impl_trait_id,
-                            parameters,
-                        }))
-                        .intern(&Interner)
+                        TyKind::Alias(AliasTy::Opaque(OpaqueTy { opaque_ty_id, parameters }))
+                            .intern(&Interner)
                     }
                     ImplTraitLoweringMode::Param => {
                         let idx = ctx.impl_trait_counter.get();
@@ -249,7 +247,9 @@ impl Ty {
                                     data.provenance == TypeParamProvenance::ArgumentImplTrait
                                 })
                                 .nth(idx as usize)
-                                .map_or(TyKind::Unknown, |(id, _)| TyKind::Placeholder(id));
+                                .map_or(TyKind::Unknown, |(id, _)| {
+                                    TyKind::Placeholder(to_placeholder_idx(ctx.db, id))
+                                });
                             param.intern(&Interner)
                         } else {
                             TyKind::Unknown.intern(&Interner)
@@ -384,7 +384,9 @@ impl Ty {
                     ctx.resolver.generic_def().expect("generics in scope"),
                 );
                 match ctx.type_param_mode {
-                    TypeParamLoweringMode::Placeholder => TyKind::Placeholder(param_id),
+                    TypeParamLoweringMode::Placeholder => {
+                        TyKind::Placeholder(to_placeholder_idx(ctx.db, param_id))
+                    }
                     TypeParamLoweringMode::Variable => {
                         let idx = generics.param_idx(param_id).expect("matching generics");
                         TyKind::BoundVar(BoundVar::new(ctx.in_binders, idx))
@@ -396,7 +398,7 @@ impl Ty {
                 let generics = generics(ctx.db.upcast(), impl_id.into());
                 let substs = match ctx.type_param_mode {
                     TypeParamLoweringMode::Placeholder => {
-                        Substs::type_params_for_generics(&generics)
+                        Substs::type_params_for_generics(ctx.db, &generics)
                     }
                     TypeParamLoweringMode::Variable => {
                         Substs::bound_vars(&generics, ctx.in_binders)
@@ -408,7 +410,7 @@ impl Ty {
                 let generics = generics(ctx.db.upcast(), adt.into());
                 let substs = match ctx.type_param_mode {
                     TypeParamLoweringMode::Placeholder => {
-                        Substs::type_params_for_generics(&generics)
+                        Substs::type_params_for_generics(ctx.db, &generics)
                     }
                     TypeParamLoweringMode::Variable => {
                         Substs::bound_vars(&generics, ctx.in_binders)
@@ -689,8 +691,9 @@ impl GenericPredicate {
                         let generics = generics(ctx.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 {
-                            TypeParamLoweringMode::Placeholder => TyKind::Placeholder(param_id),
+                            TypeParamLoweringMode::Placeholder => TyKind::Placeholder(placeholder),
                             TypeParamLoweringMode::Variable => {
                                 let idx = generics.param_idx(param_id).expect("matching generics");
                                 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, idx))