2 files changed, 31 insertions, 4 deletions

diff --git a/crates/ra_hir_def/src/db.rs b/crates/ra_hir_def/src/db.rs
index c6cd4369b..844f8bbe8 100644
--- a/crates/ra_hir_def/src/db.rs
+++ b/crates/ra_hir_def/src/db.rs
@@ -8,13 +8,14 @@ use ra_syntax::ast;
 use crate::{
     adt::{EnumData, StructData},
     body::{scope::ExprScopes, Body, BodySourceMap},
+    generics::GenericParams,
     impls::ImplData,
     nameres::{
         raw::{ImportSourceMap, RawItems},
         CrateDefMap,
     },
     traits::TraitData,
-    DefWithBodyId, EnumId, ImplId, ItemLoc, StructOrUnionId, TraitId,
+    DefWithBodyId, EnumId, GenericDefId, ImplId, ItemLoc, StructOrUnionId, TraitId,
 };
 
 #[salsa::query_group(InternDatabaseStorage)]
@@ -71,4 +72,7 @@ pub trait DefDatabase2: InternDatabase + AstDatabase {
 
     #[salsa::invoke(ExprScopes::expr_scopes_query)]
     fn expr_scopes(&self, def: DefWithBodyId) -> Arc<ExprScopes>;
+
+    #[salsa::invoke(GenericParams::generic_params_query)]
+    fn generic_params(&self, def: GenericDefId) -> Arc<GenericParams>;
 }
diff --git a/crates/ra_hir_def/src/generics.rs b/crates/ra_hir_def/src/generics.rs
index 17a5d5f43..f794eefbc 100644
--- a/crates/ra_hir_def/src/generics.rs
+++ b/crates/ra_hir_def/src/generics.rs
@@ -5,13 +5,12 @@
 use std::sync::Arc;
 
 use hir_expand::name::{self, AsName, Name};
-
 use ra_syntax::ast::{self, NameOwner, TypeBoundsOwner, TypeParamsOwner};
 
 use crate::{
     db::DefDatabase2,
     type_ref::{TypeBound, TypeRef},
-    AdtId, AstItemDef, GenericDefId, HasSource, Lookup,
+    AdtId, AstItemDef, ContainerId, GenericDefId, HasSource, Lookup,
 };
 
 /// Data about a generic parameter (to a function, struct, impl, ...).
@@ -43,7 +42,15 @@ pub struct WherePredicate {
 }
 
 impl GenericParams {
-    pub fn new(
+    pub(crate) fn generic_params_query(
+        db: &impl DefDatabase2,
+        def: GenericDefId,
+    ) -> Arc<GenericParams> {
+        let parent_generics = parent_generic_def(db, def).map(|it| db.generic_params(it));
+        Arc::new(GenericParams::new(db, def.into(), parent_generics))
+    }
+
+    fn new(
         db: &impl DefDatabase2,
         def: GenericDefId,
         parent_params: Option<Arc<GenericParams>>,
@@ -161,3 +168,19 @@ impl GenericParams {
         vec
     }
 }
+
+fn parent_generic_def(db: &impl DefDatabase2, def: GenericDefId) -> Option<GenericDefId> {
+    let container = match def {
+        GenericDefId::FunctionId(it) => it.lookup(db).container,
+        GenericDefId::TypeAliasId(it) => it.lookup(db).container,
+        GenericDefId::ConstId(it) => it.lookup(db).container,
+        GenericDefId::EnumVariantId(it) => return Some(it.parent.into()),
+        GenericDefId::AdtId(_) | GenericDefId::TraitId(_) | GenericDefId::ImplId(_) => return None,
+    };
+
+    match container {
+        ContainerId::ImplId(it) => Some(it.into()),
+        ContainerId::TraitId(it) => Some(it.into()),
+        ContainerId::ModuleId(_) => None,
+    }
+}