Fix various Rust warnings

src/main/rust/lib.rs

@@ -40,7 +40,7 @@ use zcash_primitives::{
     consensus::BranchId,
     note_encryption::Memo,
     transaction::{components::Amount, Transaction},
-    zip32::{ExtendedFullViewingKey, ExtendedSpendingKey},
+    zip32::ExtendedFullViewingKey,
 };
 use zcash_proofs::prover::LocalTxProver;
 
@@ -67,16 +67,13 @@ use zcash_client_backend::constants::testnet::{
 // Temporary Imports
 mod local_rpc_types;
 use base58::ToBase58;
-use jni::errors::Result as JniResult;
 use local_rpc_types::{TransactionDataList, TransparentTransaction, TransparentTransactionList};
 use protobuf::{parse_from_bytes, Message};
 use sha2::{Digest, Sha256};
-use zcash_client_backend::constants::{mainnet, testnet};
-use zcash_primitives::legacy::{Script, TransparentAddress};
+use zcash_primitives::legacy::TransparentAddress;
 
-use bs58::{self, decode::Error as Bs58Error};
 use hdwallet::{ExtendedPrivKey, KeyIndex};
-use secp256k1::{PublicKey, Secp256k1, SecretKey, SignOnly, VerifyOnly};
+use secp256k1::{PublicKey, Secp256k1};
 use zcash_client_backend::constants::mainnet::B58_PUBKEY_ADDRESS_PREFIX;
 
 // use crate::extended_key::{key_index::KeyIndex, ExtendedPrivKey, ExtendedPubKey, KeySeed};
@@ -648,8 +645,8 @@ pub unsafe extern "C" fn Java_cash_z_ecc_android_sdk_jni_RustBackend_parseTransa
     _: JClass<'_>,
     tx_data_list: jbyteArray,
 ) -> jbyteArray {
-    let mut err_val: Vec<u8> = Vec::new();
-    let mut res_err = env.byte_array_from_slice(&err_val).unwrap();
+    let err_val: Vec<u8> = Vec::new();
+    let res_err = env.byte_array_from_slice(&err_val).unwrap();
     let res = panic::catch_unwind(|| {
         let tx_data_bytes = env.convert_byte_array(tx_data_list)?;
         let input_tx_data = parse_from_bytes::<TransactionDataList>(&tx_data_bytes)?;
@@ -664,7 +661,7 @@ pub unsafe extern "C" fn Java_cash_z_ecc_android_sdk_jni_RustBackend_parseTransa
             tx.set_hasShieldedSpends(parsed.shielded_spends.len() > 0);
             tx.set_hasShieldedOutputs(parsed.shielded_outputs.len() > 0);
 
-            for (n, vout) in parsed.vout.iter().enumerate() {
+            for (_n, vout) in parsed.vout.iter().enumerate() {
                 match vout.script_pubkey.address() {
                     // NOTE : this logic below doesn't work. No address is parsed.
                     Some(TransparentAddress::PublicKey(hash)) => {

src/main/rust/utils/exception.rs

@@ -78,7 +78,7 @@ pub fn any_to_string(any: &Box<dyn Any + Send>) -> String {
     } else if let Some(s) = any.downcast_ref::<String>() {
         s.clone()
     } else if let Some(error) = any.downcast_ref::<Box<dyn std::error::Error + Send>>() {
-        error.description().to_string()
+        error.to_string()
     } else {
         "Unknown error occurred".to_string()
     }
@@ -106,8 +106,8 @@ mod tests {
 
     #[test]
     fn box_error_any() {
-        let error: Box<Error + Send> = Box::new("e".parse::<i32>().unwrap_err());
-        let description = error.description().to_owned();
+        let error: Box<dyn Error + Send> = Box::new("e".parse::<i32>().unwrap_err());
+        let description = error.to_string();
         let error = panic_error(error);
         assert_eq!(description, any_to_string(&error));
     }
@@ -118,7 +118,7 @@ mod tests {
         assert_eq!("Unknown error occurred", any_to_string(&error));
     }
 
-    fn panic_error<T: Send + 'static>(val: T) -> Box<Any + Send> {
+    fn panic_error<T: Send + 'static>(val: T) -> Box<dyn Any + Send> {
         panic::catch_unwind(panic::AssertUnwindSafe(|| panic!(val))).unwrap_err()
     }
 }