1 files changed, 6 insertions, 1 deletions
diff --git a/compiler/rustc_query_system/src/cache.rs b/compiler/rustc_query_system/src/cache.rs
index 7cc885be2..6e862db0b 100644
--- a/compiler/rustc_query_system/src/cache.rs
+++ b/compiler/rustc_query_system/src/cache.rs
@@ -7,11 +7,16 @@ use rustc_data_structures::sync::Lock;
 
 use std::hash::Hash;
 
-#[derive(Clone)]
 pub struct Cache<Key, Value> {
     hashmap: Lock<FxHashMap<Key, WithDepNode<Value>>>,
 }
 
+impl<Key: Clone, Value: Clone> Clone for Cache<Key, Value> {
+    fn clone(&self) -> Self {
+        Self { hashmap: Lock::new(self.hashmap.borrow().clone()) }
+    }
+}
+
 impl<Key, Value> Default for Cache<Key, Value> {
     fn default() -> Self {
         Self { hashmap: Default::default() }