rustc lint: Remove or ignore some dead code (#8148)

zebra-chain/src/orchard/note.rs

@@ -20,8 +20,13 @@ pub use nullifiers::Nullifier;
 #[cfg(any(test, feature = "proptest-impl"))]
 mod arbitrary;
 
-#[derive(Clone, Copy, Debug)]
 /// A random seed (rseed) used in the Orchard note creation.
+#[derive(Clone, Copy, Debug)]
+// At the moment this field is never read.
+//
+// TODO: consider replacing this code with the equivalent `orchard` crate code,
+//       which is better tested.
+#[allow(dead_code)]
 pub struct SeedRandomness(pub(crate) [u8; 32]);
 
 impl SeedRandomness {

zebra-chain/src/sprout/tree.rs

@@ -83,12 +83,6 @@ lazy_static! {
     };
 }
 
-/// The index of a note's commitment at the leafmost layer of its Note
-/// Commitment Tree.
-///
-/// <https://zips.z.cash/protocol/protocol.pdf#merkletree>
-pub struct Position(pub(crate) u64);
-
 /// Sprout note commitment tree root node hash.
 ///
 /// The root hash in LEBS2OSP256(rt) encoding of the Sprout note