3 files changed, 35 insertions, 2 deletions

diff --git a/crates/ra_hir_def/src/generics.rs b/crates/ra_hir_def/src/generics.rs
index 0df5a20f5..159f9034b 100644
--- a/crates/ra_hir_def/src/generics.rs
+++ b/crates/ra_hir_def/src/generics.rs
@@ -14,11 +14,14 @@ use ra_db::FileId;
 use ra_syntax::ast::{self, NameOwner, TypeBoundsOwner, TypeParamsOwner};
 
 use crate::{
+    child_by_source::ChildBySource,
     db::DefDatabase,
+    dyn_map::DynMap,
+    keys,
     src::HasChildSource,
     src::HasSource,
     type_ref::{TypeBound, TypeRef},
-    AdtId, AstItemDef, GenericDefId, LocalGenericParamId, Lookup,
+    AdtId, AstItemDef, GenericDefId, GenericParamId, LocalGenericParamId, Lookup,
 };
 
 /// Data about a generic parameter (to a function, struct, impl, ...).
@@ -183,3 +186,18 @@ impl HasChildSource for GenericDefId {
         sm
     }
 }
+
+impl ChildBySource for GenericDefId {
+    fn child_by_source(&self, db: &impl DefDatabase) -> DynMap {
+        let mut res = DynMap::default();
+        let arena_map = self.child_source(db);
+        let arena_map = arena_map.as_ref();
+        for (local_id, src) in arena_map.value.iter() {
+            let id = GenericParamId { parent: *self, local_id };
+            if let Either::Right(type_param) = src {
+                res[keys::TYPE_PARAM].insert(arena_map.with_value(type_param.clone()), id)
+            }
+        }
+        res
+    }
+}
diff --git a/crates/ra_hir_def/src/keys.rs b/crates/ra_hir_def/src/keys.rs
index 447b7e3ba..ca5630c80 100644
--- a/crates/ra_hir_def/src/keys.rs
+++ b/crates/ra_hir_def/src/keys.rs
@@ -8,7 +8,7 @@ use rustc_hash::FxHashMap;
 
 use crate::{
     dyn_map::{DynMap, Policy},
-    ConstId, EnumVariantId, FunctionId, StaticId, StructFieldId, TypeAliasId,
+    ConstId, EnumVariantId, FunctionId, GenericParamId, StaticId, StructFieldId, TypeAliasId,
 };
 
 type Key<K, V> = crate::dyn_map::Key<InFile<K>, V, AstPtrPolicy<K, V>>;
@@ -20,6 +20,7 @@ pub const ENUM_VARIANT: Key<ast::EnumVariant, EnumVariantId> = Key::new();
 pub const TYPE_ALIAS: Key<ast::TypeAliasDef, TypeAliasId> = Key::new();
 pub const TUPLE_FIELD: Key<ast::TupleFieldDef, StructFieldId> = Key::new();
 pub const RECORD_FIELD: Key<ast::RecordFieldDef, StructFieldId> = Key::new();
+pub const TYPE_PARAM: Key<ast::TypeParam, GenericParamId> = Key::new();
 
 /// XXX: AST Nodes and SyntaxNodes have identity equality semantics: nodes are
 /// equal if they point to exactly the same object.
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
index b8dfc0ab1..6dfb3c03d 100644
--- a/crates/ra_hir_def/src/lib.rs
+++ b/crates/ra_hir_def/src/lib.rs
@@ -525,6 +525,20 @@ impl HasModule for DefWithBodyId {
     }
 }
 
+impl HasModule for GenericDefId {
+    fn module(&self, db: &impl db::DefDatabase) -> ModuleId {
+        match self {
+            GenericDefId::FunctionId(it) => it.lookup(db).module(db),
+            GenericDefId::AdtId(it) => it.module(db),
+            GenericDefId::TraitId(it) => it.module(db),
+            GenericDefId::TypeAliasId(it) => it.lookup(db).module(db),
+            GenericDefId::ImplId(it) => it.module(db),
+            GenericDefId::EnumVariantId(it) => it.parent.module(db),
+            GenericDefId::ConstId(it) => it.lookup(db).module(db),
+        }
+    }
+}
+
 impl HasModule for StaticLoc {
     fn module(&self, _db: &impl db::DefDatabase) -> ModuleId {
         self.container