2 files changed, 20 insertions, 0 deletions

diff --git a/crates/ra_hir_ty/src/db.rs b/crates/ra_hir_ty/src/db.rs
index 11fc2ac3d..1462b053f 100644
--- a/crates/ra_hir_ty/src/db.rs
+++ b/crates/ra_hir_ty/src/db.rs
@@ -22,6 +22,7 @@ use hir_expand::name::Name;
 #[salsa::requires(salsa::Database)]
 pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
     #[salsa::invoke(infer_wait)]
+    #[salsa::transparent]
     fn infer(&self, def: DefWithBodyId) -> Arc<InferenceResult>;
 
     #[salsa::invoke(crate::infer::infer_query)]
diff --git a/crates/ra_hir_ty/src/tests/macros.rs b/crates/ra_hir_ty/src/tests/macros.rs
index 2e309a379..eb97288f1 100644
--- a/crates/ra_hir_ty/src/tests/macros.rs
+++ b/crates/ra_hir_ty/src/tests/macros.rs
@@ -639,3 +639,22 @@ mod clone {
     );
     assert_eq!("(Wrapper<S>, {unknown})", type_at_pos(&db, pos));
 }
+
+#[test]
+fn infer_custom_derive_simple() {
+    // FIXME: this test current now do nothing
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main
+use foo::Foo;
+
+#[derive(Foo)]
+struct S{}
+
+fn test() {
+    S{}<|>;
+}
+"#,
+    );
+    assert_eq!("S", type_at_pos(&db, pos));
+}