Fix chunk index bug with structs

eth2/types/src/test_utils/macros.rs

@@ -44,16 +44,14 @@ macro_rules! cached_tree_hash_tests {
 
             let mut rng = XorShiftRng::from_seed([42; 16]);
 
+            // Test the original hash
             let original = $type::random_for_test(&mut rng);
-
             let mut hasher = cached_tree_hash::CachedTreeHasher::new(&original).unwrap();
-
             assert_eq!(hasher.tree_hash_root().unwrap(), original.tree_hash_root());
 
+            // Test the updated hash
             let modified = $type::random_for_test(&mut rng);
-
             hasher.update(&modified).unwrap();
-
             assert_eq!(hasher.tree_hash_root().unwrap(), modified.tree_hash_root());
         }
     };

eth2/utils/cached_tree_hash/src/lib.rs

@@ -28,7 +28,7 @@ pub trait CachedTreeHash<Item>: TreeHash {
 
 #[derive(Debug, PartialEq)]
 pub struct CachedTreeHasher {
-    cache: TreeHashCache,
+    pub cache: TreeHashCache,
 }
 
 impl CachedTreeHasher {

eth2/utils/cached_tree_hash/tests/tests.rs

@@ -423,6 +423,45 @@ fn test_struct_with_two_vecs() {
     }
 }
 
+#[derive(Clone, Debug, TreeHash, CachedTreeHash)]
+pub struct U64AndTwoStructs {
+    pub a: u64,
+    pub b: Inner,
+    pub c: Inner,
+}
+
+#[test]
+fn test_u64_and_two_structs() {
+    let inners = get_inners();
+
+    let variants = vec![
+        U64AndTwoStructs {
+            a: 99,
+            b: inners[0].clone(),
+            c: inners[1].clone(),
+        },
+        U64AndTwoStructs {
+            a: 10,
+            b: inners[2].clone(),
+            c: inners[3].clone(),
+        },
+        U64AndTwoStructs {
+            a: 0,
+            b: inners[1].clone(),
+            c: inners[1].clone(),
+        },
+        U64AndTwoStructs {
+            a: 0,
+            b: inners[1].clone(),
+            c: inners[1].clone(),
+        },
+    ];
+
+    for v in &variants {
+        test_routine(v.clone(), variants.clone());
+    }
+}
+
 #[derive(Clone, Debug, TreeHash, CachedTreeHash)]
 pub struct Inner {
     pub a: u64,

eth2/utils/tree_hash_derive/src/lib.rs

@@ -102,6 +102,8 @@ pub fn subtree_derive(input: TokenStream) -> TokenStream {
                 // Iterate through the internal nodes, updating them if their children have changed.
                 cache.update_internal_nodes(&overlay)?;
 
+                cache.chunk_index = overlay.next_node();
+
                 Ok(())
             }
         }