1 files changed, 4 insertions, 0 deletions

diff --git a/crates/ra_db/src/lib.rs b/crates/ra_db/src/lib.rs
index d500d5e85..bac24e218 100644
--- a/crates/ra_db/src/lib.rs
+++ b/crates/ra_db/src/lib.rs
@@ -32,6 +32,10 @@ macro_rules! impl_intern_key {
     };
 }
 
+pub trait Upcast<T: ?Sized> {
+    fn upcast(&self) -> &T;
+}
+
 pub trait CheckCanceled {
     /// Aborts current query if there are pending changes.
     ///