Use Vec<u8> for the equihash solution instead of [u8; 1344] for now

zebra-chain/src/block.rs

@@ -107,8 +107,11 @@ pub struct BlockHeader {
     nonce: [u8; 32],
 
     /// The Equihash solution.
-    // The solution size when serialized should be in bytes ('always 1344').
-    solution: [u8; 1344],
+    // The solution size when serialized should be in bytes ('always
+    // 1344').  I first tried this as a [u8; 1344] but until const
+    // generics land we'd have to implement all our common traits
+    // manually, like in pzec.
+    solution: Vec<u8>,
 }
 
 impl BlockHeader {

zebra-chain/src/note_commitment_tree.rs

@@ -13,7 +13,6 @@
 use std::io;
 
 use crate::serialization::{SerializationError, ZcashDeserialize, ZcashSerialize};
-use crate::sha256d_writer::Sha256dWriter;
 
 // XXX: Depending on if we implement SproutNoteCommitmentTree or
 // similar, it may be worth it to define a NoteCommitmentTree trait.

zebra-network/src/protocol/message.rs

@@ -164,7 +164,7 @@ pub enum Message {
         nonce: [u8; 32],
 
         /// The Equihash solution.
-        solution: [u8; 1344],
+        solution: Vec<u8>,
 
         /// Transactions.
         txns: Vec<Transaction>,