Fix clippy warnings (#813)

* Clippy account manager

* Clippy account_manager

* Clippy beacon_node/beacon_chain

* Clippy beacon_node/client

* Clippy beacon_node/eth1

* Clippy beacon_node/eth2-libp2p

* Clippy beacon_node/genesis

* Clippy beacon_node/network

* Clippy beacon_node/rest_api

* Clippy beacon_node/src

* Clippy beacon_node/store

* Clippy eth2/lmd_ghost

* Clippy eth2/operation_pool

* Clippy eth2/state_processing

* Clippy eth2/types

* Clippy eth2/utils/bls

* Clippy eth2/utils/cahced_tree_hash

* Clippy eth2/utils/deposit_contract

* Clippy eth2/utils/eth2_interop_keypairs

* Clippy eth2/utils/eth2_testnet_config

* Clippy eth2/utils/lighthouse_metrics

* Clippy eth2/utils/ssz

* Clippy eth2/utils/ssz_types

* Clippy eth2/utils/tree_hash_derive

* Clippy lcli

* Clippy tests/beacon_chain_sim

* Clippy validator_client

* Cargo fmt

account_manager/src/lib.rs

@@ -156,7 +156,7 @@ fn run_new_validator_subcommand<T: EthSpec>(
                     })
                     .map(|password| {
                         // Trim the line feed from the end of the password file, if present.
-                        if password.ends_with("\n") {
+                        if password.ends_with('\n') {
                             password[0..password.len() - 1].to_string()
                         } else {
                             password
@@ -337,7 +337,7 @@ fn deposit_validators<E: EthSpec>(
                 .map(|_| event_loop)
         })
         // Web3 gives errors if the event loop is dropped whilst performing requests.
-        .map(|event_loop| drop(event_loop))
+        .map(drop)
 }
 
 /// For the given `ValidatorDirectory`, submit a deposit transaction to the `web3` node.
@@ -367,7 +367,7 @@ fn deposit_validator(
         .into_future()
         .and_then(move |(voting_keypair, deposit_data)| {
             let pubkey_1 = voting_keypair.pk.clone();
-            let pubkey_2 = voting_keypair.pk.clone();
+            let pubkey_2 = voting_keypair.pk;
 
             let web3_1 = web3.clone();
             let web3_2 = web3.clone();
@@ -421,7 +421,7 @@ fn deposit_validator(
                         to: Some(deposit_contract),
                         gas: Some(U256::from(DEPOSIT_GAS)),
                         gas_price: None,
-                        value: Some(U256::from(from_gwei(deposit_amount))),
+                        value: Some(from_gwei(deposit_amount)),
                         data: Some(deposit_data.into()),
                         nonce: None,
                         condition: None,

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -25,6 +25,7 @@ use state_processing::{
     per_block_processing, per_slot_processing, BlockProcessingError, BlockSignatureStrategy,
 };
 use std::borrow::Cow;
+use std::cmp::Ordering;
 use std::fs;
 use std::io::prelude::*;
 use std::sync::Arc;
@@ -512,9 +513,9 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     pub fn state_at_slot(&self, slot: Slot) -> Result<BeaconState<T::EthSpec>, Error> {
         let head_state = self.head()?.beacon_state;
 
-        if slot == head_state.slot {
+        match slot.cmp(&head_state.slot) {
-            Ok(head_state)
+            Ordering::Equal => Ok(head_state),
-        } else if slot > head_state.slot {
+            Ordering::Greater => {
                 if slot > head_state.slot + T::EthSpec::slots_per_epoch() {
                     warn!(
                         self.log,
@@ -560,7 +561,8 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                     };
                 }
                 Ok(state)
-        } else {
+            }
+            Ordering::Less => {
                 let state_root = self
                     .rev_iter_state_roots()?
                     .take_while(|(_root, current_slot)| *current_slot >= slot)
@@ -573,6 +575,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                     .ok_or_else(|| Error::NoStateForSlot(slot))?)
             }
         }
+    }
 
     /// Returns the `BeaconState` the current slot (viz., `self.slot()`).
     ///
@@ -638,7 +641,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         let head_state = &self.head()?.beacon_state;
 
         let mut state = if epoch(slot) == epoch(head_state.slot) {
-            self.head()?.beacon_state.clone()
+            self.head()?.beacon_state
         } else {
             self.state_at_slot(slot)?
         };
@@ -671,7 +674,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         let head_state = &self.head()?.beacon_state;
 
         let mut state = if epoch == as_epoch(head_state.slot) {
-            self.head()?.beacon_state.clone()
+            self.head()?.beacon_state
         } else {
             self.state_at_slot(epoch.start_slot(T::EthSpec::slots_per_epoch()))?
         };
@@ -1754,9 +1757,9 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         let mut dump = vec![];
 
         let mut last_slot = CheckPoint {
-            beacon_block: self.head()?.beacon_block.clone(),
+            beacon_block: self.head()?.beacon_block,
             beacon_block_root: self.head()?.beacon_block_root,
-            beacon_state: self.head()?.beacon_state.clone(),
+            beacon_state: self.head()?.beacon_state,
             beacon_state_root: self.head()?.beacon_state_root,
         };
 

beacon_node/beacon_chain/src/builder.rs

@@ -448,7 +448,7 @@ where
         let fork_choice = if let Some(persisted_beacon_chain) = &self.persisted_beacon_chain {
             ForkChoice::from_ssz_container(
                 persisted_beacon_chain.fork_choice.clone(),
-                store.clone(),
+                store,
                 block_root_tree,
             )
             .map_err(|e| format!("Unable to decode fork choice from db: {:?}", e))?
@@ -462,7 +462,7 @@ where
                 .ok_or_else(|| "fork_choice_backend requires a genesis_block_root")?;
 
             let backend = ThreadSafeReducedTree::new(
-                store.clone(),
+                store,
                 block_root_tree,
                 &finalized_checkpoint.beacon_block,
                 finalized_checkpoint.beacon_block_root,
@@ -626,7 +626,7 @@ mod test {
     #[test]
     fn recent_genesis() {
         let validator_count = 8;
-        let genesis_time = 13371337;
+        let genesis_time = 13_371_337;
 
         let log = get_logger();
         let store = Arc::new(MemoryStore::open());
@@ -641,7 +641,7 @@ mod test {
 
         let chain = BeaconChainBuilder::new(MinimalEthSpec)
             .logger(log.clone())
-            .store(store.clone())
+            .store(store)
             .store_migrator(NullMigrator)
             .genesis_state(genesis_state)
             .expect("should build state using recent genesis")
@@ -662,7 +662,7 @@ mod test {
 
         assert_eq!(state.slot, Slot::new(0), "should start from genesis");
         assert_eq!(
-            state.genesis_time, 13371337,
+            state.genesis_time, 13_371_337,
             "should have the correct genesis time"
         );
         assert_eq!(

beacon_node/beacon_chain/src/eth1_chain.rs

@@ -8,6 +8,7 @@ use rand::prelude::*;
 use slog::{crit, debug, error, trace, Logger};
 use ssz_derive::{Decode, Encode};
 use state_processing::per_block_processing::get_new_eth1_data;
+use std::cmp::Ordering;
 use std::collections::HashMap;
 use std::iter::DoubleEndedIterator;
 use std::iter::FromIterator;
@@ -343,8 +344,7 @@ impl<T: EthSpec, S: Store<T>> Eth1ChainBackend<T, S> for CachingEth1Backend<T, S
                 .iter()
                 .rev()
                 .skip_while(|eth1_block| eth1_block.timestamp > voting_period_start_seconds)
-                .skip(eth1_follow_distance as usize)
+                .nth(eth1_follow_distance as usize)
-                .next()
                 .map(|block| {
                     trace!(
                         self.log,
@@ -392,11 +392,10 @@ impl<T: EthSpec, S: Store<T>> Eth1ChainBackend<T, S> for CachingEth1Backend<T, S
             state.eth1_data.deposit_count
         };
 
-        if deposit_index > deposit_count {
+        match deposit_index.cmp(&deposit_count) {
-            Err(Error::DepositIndexTooHigh)
+            Ordering::Greater => Err(Error::DepositIndexTooHigh),
-        } else if deposit_index == deposit_count {
+            Ordering::Equal => Ok(vec![]),
-            Ok(vec![])
+            Ordering::Less => {
-        } else {
                 let next = deposit_index;
                 let last = std::cmp::min(deposit_count, next + T::MaxDeposits::to_u64());
 
@@ -409,6 +408,7 @@ impl<T: EthSpec, S: Store<T>> Eth1ChainBackend<T, S> for CachingEth1Backend<T, S
                     .map(|(_deposit_root, deposits)| deposits)
             }
         }
+    }
 
     /// Return encoded byte representation of the block and deposit caches.
     fn as_bytes(&self) -> Vec<u8> {
@@ -775,7 +775,7 @@ mod test {
 
                     let deposits_for_inclusion = eth1_chain
                         .deposits_for_block_inclusion(&state, &random_eth1_data(), spec)
-                        .expect(&format!("should find deposit for {}", i));
+                        .unwrap_or_else(|_| panic!("should find deposit for {}", i));
 
                     let expected_len =
                         std::cmp::min(i - initial_deposit_index, max_deposits as usize);
@@ -853,7 +853,7 @@ mod test {
             state.slot = Slot::new(period * 1_000 + period / 2);
 
             // Add 50% of the votes so a lookup is required.
-            for _ in 0..period / 2 + 1 {
+            for _ in 0..=period / 2 {
                 state
                     .eth1_data_votes
                     .push(random_eth1_data())
@@ -932,7 +932,7 @@ mod test {
             state.slot = Slot::new(period / 2);
 
             // Add 50% of the votes so a lookup is required.
-            for _ in 0..period / 2 + 1 {
+            for _ in 0..=period / 2 {
                 state
                     .eth1_data_votes
                     .push(random_eth1_data())
@@ -1090,7 +1090,7 @@ mod test {
                         eth1_block.number,
                         *new_eth1_data
                             .get(&eth1_block.clone().eth1_data().unwrap())
-                            .expect(&format!(
+                            .unwrap_or_else(|| panic!(
                                 "new_eth1_data should have expected block #{}",
                                 eth1_block.number
                             ))
@@ -1135,8 +1135,8 @@ mod test {
 
             let votes = collect_valid_votes(
                 &state,
-                HashMap::from_iter(new_eth1_data.clone().into_iter()),
+                HashMap::from_iter(new_eth1_data.into_iter()),
-                HashMap::from_iter(all_eth1_data.clone().into_iter()),
+                HashMap::from_iter(all_eth1_data.into_iter()),
             );
             assert_eq!(
                 votes.len(),
@@ -1164,7 +1164,7 @@ mod test {
             let votes = collect_valid_votes(
                 &state,
                 HashMap::from_iter(new_eth1_data.clone().into_iter()),
-                HashMap::from_iter(all_eth1_data.clone().into_iter()),
+                HashMap::from_iter(all_eth1_data.into_iter()),
             );
             assert_votes!(
                 votes,
@@ -1196,8 +1196,8 @@ mod test {
 
             let votes = collect_valid_votes(
                 &state,
-                HashMap::from_iter(new_eth1_data.clone().into_iter()),
+                HashMap::from_iter(new_eth1_data.into_iter()),
-                HashMap::from_iter(all_eth1_data.clone().into_iter()),
+                HashMap::from_iter(all_eth1_data.into_iter()),
             );
             assert_votes!(
                 votes,
@@ -1230,12 +1230,12 @@ mod test {
                 .expect("should have some eth1 data")
                 .clone();
 
-            state.eth1_data_votes = vec![non_new_eth1_data.0.clone()].into();
+            state.eth1_data_votes = vec![non_new_eth1_data.0].into();
 
             let votes = collect_valid_votes(
                 &state,
-                HashMap::from_iter(new_eth1_data.clone().into_iter()),
+                HashMap::from_iter(new_eth1_data.into_iter()),
-                HashMap::from_iter(all_eth1_data.clone().into_iter()),
+                HashMap::from_iter(all_eth1_data.into_iter()),
             );
 
             assert_votes!(
@@ -1268,8 +1268,8 @@ mod test {
 
             let votes = collect_valid_votes(
                 &state,
-                HashMap::from_iter(new_eth1_data.clone().into_iter()),
+                HashMap::from_iter(new_eth1_data.into_iter()),
-                HashMap::from_iter(all_eth1_data.clone().into_iter()),
+                HashMap::from_iter(all_eth1_data.into_iter()),
             );
 
             assert_votes!(

beacon_node/beacon_chain/src/fork_choice.rs

@@ -294,7 +294,7 @@ impl<T: BeaconChainTypes> ForkChoice<T> {
     /// Returns a `SszForkChoice` which contains the current state of `Self`.
     pub fn as_ssz_container(&self) -> SszForkChoice {
         SszForkChoice {
-            genesis_block_root: self.genesis_block_root.clone(),
+            genesis_block_root: self.genesis_block_root,
             justified_checkpoint: self.justified_checkpoint.read().clone(),
             best_justified_checkpoint: self.best_justified_checkpoint.read().clone(),
             backend_bytes: self.backend.as_bytes(),

beacon_node/beacon_chain/src/head_tracker.rs

@@ -59,10 +59,10 @@ impl HeadTracker {
         let slots_len = ssz_container.slots.len();
 
         if roots_len != slots_len {
-            return Err(Error::MismatchingLengths {
+            Err(Error::MismatchingLengths {
                 roots_len,
                 slots_len,
-            });
+            })
         } else {
             let map = HashMap::from_iter(
                 ssz_container

beacon_node/beacon_chain/src/test_utils.rs

@@ -173,7 +173,7 @@ impl<E: EthSpec> BeaconChainHarness<DiskHarnessType<E>> {
 
         let chain = BeaconChainBuilder::new(eth_spec_instance)
             .logger(log.clone())
-            .custom_spec(spec.clone())
+            .custom_spec(spec)
             .store(store.clone())
             .store_migrator(<BlockingMigrator<_> as Migrate<_, E>>::new(store))
             .resume_from_db(Eth1Config::default())
@@ -236,7 +236,6 @@ where
             self.chain
                 .state_at_slot(state_slot)
                 .expect("should find state for slot")
-                .clone()
         };
 
         // Determine the first slot where a block should be built.

beacon_node/client/src/builder.rs

@@ -151,7 +151,7 @@ where
 
                 let builder = BeaconChainBuilder::new(eth_spec_instance)
                     .logger(context.log.clone())
-                    .store(store.clone())
+                    .store(store)
                     .store_migrator(store_migrator)
                     .custom_spec(spec.clone());
 
@@ -223,7 +223,7 @@ where
                             Box::new(future)
                         }
                         ClientGenesis::RemoteNode { server, .. } => {
-                            let future = Bootstrapper::connect(server.to_string(), &context.log)
+                            let future = Bootstrapper::connect(server, &context.log)
                                 .map_err(|e| {
                                     format!("Failed to initialize bootstrap client: {}", e)
                                 })
@@ -306,14 +306,14 @@ where
             .ok_or_else(|| "http_server requires a libp2p network sender")?;
 
         let network_info = rest_api::NetworkInfo {
-            network_service: network.clone(),
+            network_service: network,
-            network_chan: network_send.clone(),
+            network_chan: network_send,
         };
 
         let (exit_signal, listening_addr) = rest_api::start_server(
             &client_config.rest_api,
             &context.executor,
-            beacon_chain.clone(),
+            beacon_chain,
             network_info,
             client_config
                 .create_db_path()
@@ -529,7 +529,7 @@ where
             spec,
             context.log,
         )
-        .map_err(|e| format!("Unable to open database: {:?}", e).to_string())?;
+        .map_err(|e| format!("Unable to open database: {:?}", e))?;
         self.store = Some(Arc::new(store));
         Ok(self)
     }
@@ -557,8 +557,8 @@ where
 {
     /// Specifies that the `Client` should use a `DiskStore` database.
     pub fn simple_disk_store(mut self, path: &Path) -> Result<Self, String> {
-        let store = SimpleDiskStore::open(path)
+        let store =
-            .map_err(|e| format!("Unable to open database: {:?}", e).to_string())?;
+            SimpleDiskStore::open(path).map_err(|e| format!("Unable to open database: {:?}", e))?;
         self.store = Some(Arc::new(store));
         Ok(self)
     }
@@ -660,7 +660,7 @@ where
             .ok_or_else(|| "caching_eth1_backend requires a store".to_string())?;
 
         let backend = if let Some(eth1_service_from_genesis) = self.eth1_service {
-            eth1_service_from_genesis.update_config(config.clone())?;
+            eth1_service_from_genesis.update_config(config)?;
 
             // This cache is not useful because it's first (earliest) block likely the block that
             // triggered genesis.

beacon_node/client/src/notifier.rs

@@ -17,7 +17,7 @@ pub const WARN_PEER_COUNT: usize = 1;
 const SECS_PER_MINUTE: f64 = 60.0;
 const SECS_PER_HOUR: f64 = 3600.0;
 const SECS_PER_DAY: f64 = 86400.0; // non-leap
-const SECS_PER_WEEK: f64 = 604800.0; // non-leap
+const SECS_PER_WEEK: f64 = 604_800.0; // non-leap
 const DAYS_PER_WEEK: f64 = 7.0;
 const HOURS_PER_DAY: f64 = 24.0;
 const MINUTES_PER_HOUR: f64 = 60.0;
@@ -166,13 +166,14 @@ pub fn spawn_notifier<T: BeaconChainTypes>(
         .then(move |result| {
             match result {
                 Ok(()) => Ok(()),
-                Err(e) => Ok(error!(
+                Err(e) => {
+                    error!(
                     log_3,
                     "Notifier failed to notify";
                     "error" => format!("{:?}", e)
-                ))
+                );
-            }
+                Ok(())
-        });
+            } } });
 
     let (exit_signal, exit) = exit_future::signal();
     context

beacon_node/eth1/src/block_cache.rs

@@ -224,7 +224,7 @@ mod tests {
             );
         }
 
-        let mut cache_2 = cache.clone();
+        let mut cache_2 = cache;
         cache_2.truncate(17);
         assert_eq!(
             cache_2.blocks.len(),

beacon_node/eth1/src/deposit_cache.rs

@@ -1,6 +1,7 @@
 use crate::DepositLog;
 use eth2_hashing::hash;
 use ssz_derive::{Decode, Encode};
+use std::cmp::Ordering;
 use tree_hash::TreeHash;
 use types::{Deposit, Hash256, DEPOSIT_TREE_DEPTH};
 
@@ -196,24 +197,26 @@ impl DepositCache {
     /// - If a log with index `log.index - 1` is not already present in `self` (ignored when empty).
     /// - If a log with `log.index` is already known, but the given `log` is distinct to it.
     pub fn insert_log(&mut self, log: DepositLog) -> Result<(), Error> {
-        if log.index == self.logs.len() as u64 {
+        match log.index.cmp(&(self.logs.len() as u64)) {
+            Ordering::Equal => {
                 let deposit = Hash256::from_slice(&log.deposit_data.tree_hash_root());
                 self.leaves.push(deposit);
                 self.logs.push(log);
                 self.deposit_tree.push_leaf(deposit)?;
                 self.deposit_roots.push(self.deposit_tree.root());
                 Ok(())
-        } else if log.index < self.logs.len() as u64 {
+            }
+            Ordering::Less => {
                 if self.logs[log.index as usize] == log {
                     Ok(())
                 } else {
                     Err(Error::DuplicateDistinctLog(log.index))
                 }
-        } else {
+            }
-            Err(Error::NonConsecutive {
+            Ordering::Greater => Err(Error::NonConsecutive {
                 log_index: log.index,
                 expected: self.logs.len(),
-            })
+            }),
         }
     }
 
@@ -312,14 +315,12 @@ impl DepositCache {
             .logs
             .binary_search_by(|deposit| deposit.block_number.cmp(&block_number));
         match index {
-            Ok(index) => return self.logs.get(index).map(|x| x.index + 1),
+            Ok(index) => self.logs.get(index).map(|x| x.index + 1),
-            Err(next) => {
+            Err(next) => Some(
-                return Some(
                 self.logs
                     .get(next.saturating_sub(1))
                     .map_or(0, |x| x.index + 1),
-                )
+            ),
-            }
         }
     }
 
@@ -329,7 +330,7 @@ impl DepositCache {
     /// and queries the `deposit_roots` map to get the corresponding `deposit_root`.
     pub fn get_deposit_root_from_cache(&self, block_number: u64) -> Option<Hash256> {
         let index = self.get_deposit_count_from_cache(block_number)?;
-        Some(self.deposit_roots.get(index as usize)?.clone())
+        Some(*self.deposit_roots.get(index as usize)?)
     }
 }
 

beacon_node/eth1/src/http.rs

@@ -136,7 +136,7 @@ pub fn get_deposit_count(
         timeout,
     )
     .and_then(|result| match result {
-        None => Err(format!("Deposit root response was none")),
+        None => Err("Deposit root response was none".to_string()),
         Some(bytes) => {
             if bytes.is_empty() {
                 Ok(None)
@@ -173,7 +173,7 @@ pub fn get_deposit_root(
         timeout,
     )
     .and_then(|result| match result {
-        None => Err(format!("Deposit root response was none")),
+        None => Err("Deposit root response was none".to_string()),
         Some(bytes) => {
             if bytes.is_empty() {
                 Ok(None)

beacon_node/eth1/src/service.rs

@@ -613,7 +613,7 @@ impl Service {
 
             Ok(BlockCacheUpdateOutcome::Success {
                 blocks_imported,
-                head_block_number: cache_4.clone().block_cache.read().highest_block_number(),
+                head_block_number: cache_4.block_cache.read().highest_block_number(),
             })
         })
     }

beacon_node/eth1/tests/test.rs

@@ -758,7 +758,7 @@ mod fast {
             log,
         );
         let n = 10;
-        let deposits: Vec<_> = (0..n).into_iter().map(|_| random_deposit_data()).collect();
+        let deposits: Vec<_> = (0..n).map(|_| random_deposit_data()).collect();
         for deposit in &deposits {
             deposit_contract
                 .deposit(runtime, deposit.clone())

beacon_node/eth2-libp2p/src/behaviour.rs

@@ -57,7 +57,7 @@ impl<TSubstream: AsyncRead + AsyncWrite> Behaviour<TSubstream> {
         net_conf: &NetworkConfig,
         log: &slog::Logger,
     ) -> error::Result<Self> {
-        let local_peer_id = local_key.public().clone().into_peer_id();
+        let local_peer_id = local_key.public().into_peer_id();
         let behaviour_log = log.new(o!());
 
         let ping_config = PingConfig::new()
@@ -74,7 +74,7 @@ impl<TSubstream: AsyncRead + AsyncWrite> Behaviour<TSubstream> {
 
         Ok(Behaviour {
             eth2_rpc: RPC::new(log.clone()),
-            gossipsub: Gossipsub::new(local_peer_id.clone(), net_conf.gs_config.clone()),
+            gossipsub: Gossipsub::new(local_peer_id, net_conf.gs_config.clone()),
             discovery: Discovery::new(local_key, net_conf, log)?,
             ping: Ping::new(ping_config),
             identify,

beacon_node/eth2-libp2p/src/rpc/handler.rs

@@ -145,7 +145,7 @@ where
         // When terminating a stream, report the stream termination to the requesting user via
         // an RPC error
         let error = RPCErrorResponse::ServerError(ErrorMessage {
-            error_message: "Request timed out".as_bytes().to_vec(),
+            error_message: b"Request timed out".to_vec(),
         });
 
         // The stream termination type is irrelevant, this will terminate the
@@ -510,7 +510,7 @@ where
             // notify the user
             return Ok(Async::Ready(ProtocolsHandlerEvent::Custom(
                 RPCEvent::Error(
-                    stream_id.get_ref().clone(),
+                    *stream_id.get_ref(),
                     RPCError::Custom("Stream timed out".into()),
                 ),
             )));

beacon_node/eth2-libp2p/tests/common/mod.rs

@@ -43,8 +43,7 @@ pub fn build_libp2p_instance(
 ) -> LibP2PService {
     let config = build_config(port, boot_nodes, secret_key);
     // launch libp2p service
-    let libp2p_service = LibP2PService::new(config.clone(), log.clone()).unwrap();
+    LibP2PService::new(config, log.clone()).unwrap()
-    libp2p_service
 }
 
 #[allow(dead_code)]
@@ -64,10 +63,10 @@ pub fn build_full_mesh(log: slog::Logger, n: usize, start_port: Option<u16>) ->
         .map(|x| get_enr(&x).multiaddr()[1].clone())
         .collect();
 
-    for i in 0..n {
+    for (i, node) in nodes.iter_mut().enumerate().take(n) {
-        for j in i..n {
+        for (j, multiaddr) in multiaddrs.iter().enumerate().skip(i) {
             if i != j {
-                match libp2p::Swarm::dial_addr(&mut nodes[i].swarm, multiaddrs[j].clone()) {
+                match libp2p::Swarm::dial_addr(&mut node.swarm, multiaddr.clone()) {
                     Ok(()) => debug!(log, "Connected"),
                     Err(_) => error!(log, "Failed to connect"),
                 };

beacon_node/eth2-libp2p/tests/gossipsub_tests.rs

@@ -62,7 +62,7 @@ fn test_gossipsub_forward() {
                             // Every node except the corner nodes are connected to 2 nodes.
                             if subscribed_count == (num_nodes * 2) - 2 {
                                 node.swarm.publish(
-                                    &vec![Topic::new(topic.into_string())],
+                                    &[Topic::new(topic.into_string())],
                                     pubsub_message.clone(),
                                 );
                             }
@@ -96,11 +96,10 @@ fn test_gossipsub_full_mesh_publish() {
     let mut received_count = 0;
     tokio::run(futures::future::poll_fn(move || -> Result<_, ()> {
         for node in nodes.iter_mut() {
-            loop {
+            while let Async::Ready(Some(Libp2pEvent::PubsubMessage {
-                match node.poll().unwrap() {
-                    Async::Ready(Some(Libp2pEvent::PubsubMessage {
                 topics, message, ..
-                    })) => {
+            })) = node.poll().unwrap()
+            {
                 assert_eq!(topics.len(), 1);
                 // Assert topic is the published topic
                 assert_eq!(
@@ -114,29 +113,22 @@ fn test_gossipsub_full_mesh_publish() {
                     return Ok(Async::Ready(()));
                 }
             }
-                    _ => break,
         }
-            }
+        while let Async::Ready(Some(Libp2pEvent::PeerSubscribed(_, topic))) =
-        }
+            publishing_node.poll().unwrap()
-        loop {
+        {
-            match publishing_node.poll().unwrap() {
-                Async::Ready(Some(Libp2pEvent::PeerSubscribed(_, topic))) => {
             // Received topics is one of subscribed eth2 topics
             assert!(topic.clone().into_string().starts_with("/eth2/"));
             // Publish on beacon block topic
             if topic == TopicHash::from_raw("/eth2/beacon_block/ssz") {
                 subscribed_count += 1;
                 if subscribed_count == num_nodes - 1 {
-                            publishing_node.swarm.publish(
+                    publishing_node
-                                &vec![Topic::new(topic.into_string())],
+                        .swarm
-                                pubsub_message.clone(),
+                        .publish(&[Topic::new(topic.into_string())], pubsub_message.clone());
-                            );
                 }
             }
         }
-                _ => break,
-            }
-        }
         Ok(Async::NotReady)
     }))
 }

beacon_node/eth2-libp2p/tests/rpc_tests.rs

@@ -3,6 +3,7 @@ use eth2_libp2p::rpc::methods::*;
 use eth2_libp2p::rpc::*;
 use eth2_libp2p::{Libp2pEvent, RPCEvent};
 use slog::{warn, Level};
+use std::sync::atomic::{AtomicBool, Ordering::Relaxed};
 use std::sync::{Arc, Mutex};
 use std::time::Duration;
 use tokio::prelude::*;
@@ -106,20 +107,19 @@ fn test_status_rpc() {
     });
 
     // execute the futures and check the result
-    let test_result = Arc::new(Mutex::new(false));
+    let test_result = Arc::new(AtomicBool::new(false));
     let error_result = test_result.clone();
     let thread_result = test_result.clone();
     tokio::run(
         sender_future
             .select(receiver_future)
             .timeout(Duration::from_millis(1000))
-            .map_err(move |_| *error_result.lock().unwrap() = false)
+            .map_err(move |_| error_result.store(false, Relaxed))
             .map(move |result| {
-                *thread_result.lock().unwrap() = result.0;
+                thread_result.store(result.0, Relaxed);
-                ()
             }),
     );
-    assert!(*test_result.lock().unwrap());
+    assert!(test_result.load(Relaxed));
 }
 
 #[test]
@@ -236,20 +236,19 @@ fn test_blocks_by_range_chunked_rpc() {
     });
 
     // execute the futures and check the result
-    let test_result = Arc::new(Mutex::new(false));
+    let test_result = Arc::new(AtomicBool::new(false));
     let error_result = test_result.clone();
     let thread_result = test_result.clone();
     tokio::run(
         sender_future
             .select(receiver_future)
             .timeout(Duration::from_millis(1000))
-            .map_err(move |_| *error_result.lock().unwrap() = false)
+            .map_err(move |_| error_result.store(false, Relaxed))
             .map(move |result| {
-                *thread_result.lock().unwrap() = result.0;
+                thread_result.store(result.0, Relaxed);
-                ()
             }),
     );
-    assert!(*test_result.lock().unwrap());
+    assert!(test_result.load(Relaxed));
 }
 
 #[test]
@@ -359,20 +358,19 @@ fn test_blocks_by_range_single_empty_rpc() {
     });
 
     // execute the futures and check the result
-    let test_result = Arc::new(Mutex::new(false));
+    let test_result = Arc::new(AtomicBool::new(false));
     let error_result = test_result.clone();
     let thread_result = test_result.clone();
     tokio::run(
         sender_future
             .select(receiver_future)
             .timeout(Duration::from_millis(1000))
-            .map_err(move |_| *error_result.lock().unwrap() = false)
+            .map_err(move |_| error_result.store(false, Relaxed))
             .map(move |result| {
-                *thread_result.lock().unwrap() = result.0;
+                thread_result.store(result.0, Relaxed);
-                ()
             }),
     );
-    assert!(*test_result.lock().unwrap());
+    assert!(test_result.load(Relaxed));
 }
 
 #[test]
@@ -486,20 +484,19 @@ fn test_blocks_by_root_chunked_rpc() {
     });
 
     // execute the futures and check the result
-    let test_result = Arc::new(Mutex::new(false));
+    let test_result = Arc::new(AtomicBool::new(false));
     let error_result = test_result.clone();
     let thread_result = test_result.clone();
     tokio::run(
         sender_future
             .select(receiver_future)
             .timeout(Duration::from_millis(1000))
-            .map_err(move |_| *error_result.lock().unwrap() = false)
+            .map_err(move |_| error_result.store(false, Relaxed))
             .map(move |result| {
-                *thread_result.lock().unwrap() = result.0;
+                thread_result.store(result.0, Relaxed);
-                ()
             }),
     );
-    assert!(*test_result.lock().unwrap());
+    assert!(test_result.load(Relaxed));
 }
 
 #[test]
@@ -558,18 +555,17 @@ fn test_goodbye_rpc() {
     });
 
     // execute the futures and check the result
-    let test_result = Arc::new(Mutex::new(false));
+    let test_result = Arc::new(AtomicBool::new(false));
     let error_result = test_result.clone();
     let thread_result = test_result.clone();
     tokio::run(
         sender_future
             .select(receiver_future)
             .timeout(Duration::from_millis(1000))
-            .map_err(move |_| *error_result.lock().unwrap() = false)
+            .map_err(move |_| error_result.store(false, Relaxed))
             .map(move |result| {
-                *thread_result.lock().unwrap() = result.0;
+                thread_result.store(result.0, Relaxed);
-                ()
             }),
     );
-    assert!(*test_result.lock().unwrap());
+    assert!(test_result.load(Relaxed));
 }

beacon_node/genesis/src/common.rs

@@ -19,7 +19,7 @@ pub fn genesis_deposits(
     let depth = spec.deposit_contract_tree_depth as usize;
     let mut tree = MerkleTree::create(&[], depth);
     for (i, deposit_leaf) in deposit_root_leaves.iter().enumerate() {
-        if let Err(_) = tree.push_leaf(*deposit_leaf, depth) {
+        if tree.push_leaf(*deposit_leaf, depth).is_err() {
             return Err(String::from("Failed to push leaf"));
         }
 

beacon_node/genesis/tests/tests.rs

@@ -59,7 +59,6 @@ fn basic() {
     spec.min_genesis_active_validator_count = 8;
 
     let deposits = (0..spec.min_genesis_active_validator_count + 2)
-        .into_iter()
         .map(|i| {
             deposit_contract.deposit_helper::<MinimalEthSpec>(
                 generate_deterministic_keypair(i as usize),
@@ -73,7 +72,7 @@ fn basic() {
         })
         .collect::<Vec<_>>();
 
-    let deposit_future = deposit_contract.deposit_multiple(deposits.clone());
+    let deposit_future = deposit_contract.deposit_multiple(deposits);
 
     let wait_future =
         service.wait_for_genesis_state::<MinimalEthSpec>(update_interval, spec.clone());

beacon_node/network/src/message_handler.rs

@@ -229,7 +229,7 @@ impl<T: BeaconChainTypes> MessageHandler<T> {
                         .on_block_gossip(peer_id.clone(), block);
                     // TODO: Apply more sophisticated validation and decoding logic
                     if should_forward_on {
-                        self.propagate_message(id, peer_id.clone());
+                        self.propagate_message(id, peer_id);
                     }
                 }
                 Err(e) => {

beacon_node/network/src/message_processor.rs

@@ -203,7 +203,7 @@ impl<T: BeaconChainTypes> MessageProcessor<T> {
             );
 
             self.network
-                .disconnect(peer_id.clone(), GoodbyeReason::IrrelevantNetwork);
+                .disconnect(peer_id, GoodbyeReason::IrrelevantNetwork);
         } else if remote.head_slot
             > self.chain.slot().unwrap_or_else(|_| Slot::from(0u64)) + FUTURE_SLOT_TOLERANCE
         {
@@ -219,7 +219,7 @@ impl<T: BeaconChainTypes> MessageProcessor<T> {
             "reason" => "different system clocks or genesis time"
             );
             self.network
-                .disconnect(peer_id.clone(), GoodbyeReason::IrrelevantNetwork);
+                .disconnect(peer_id, GoodbyeReason::IrrelevantNetwork);
         } else if remote.finalized_epoch <= local.finalized_epoch
             && remote.finalized_root != Hash256::zero()
             && local.finalized_root != Hash256::zero()
@@ -239,7 +239,7 @@ impl<T: BeaconChainTypes> MessageProcessor<T> {
                 "reason" => "different finalized chain"
             );
             self.network
-                .disconnect(peer_id.clone(), GoodbyeReason::IrrelevantNetwork);
+                .disconnect(peer_id, GoodbyeReason::IrrelevantNetwork);
         } else if remote.finalized_epoch < local.finalized_epoch {
             // The node has a lower finalized epoch, their chain is not useful to us. There are two
             // cases where a node can have a lower finalized epoch:
@@ -512,7 +512,7 @@ impl<T: BeaconChainTypes> MessageProcessor<T> {
                     // Inform the sync manager to find parents for this block
                     trace!(self.log, "Block with unknown parent received";
                             "peer_id" => format!("{:?}",peer_id));
-                    self.send_to_sync(SyncMessage::UnknownBlock(peer_id, Box::new(block.clone())));
+                    self.send_to_sync(SyncMessage::UnknownBlock(peer_id, Box::new(block)));
                     SHOULD_FORWARD_GOSSIP_BLOCK
                 }
                 BlockProcessingOutcome::FutureSlot {

beacon_node/network/src/service.rs

@@ -263,7 +263,7 @@ fn network_service(
                         id,
                         source,
                         message,
-                        topics: _,
+                        ..
                     } => {
                         message_handler_send
                             .try_send(HandlerMessage::PubsubMessage(id, source, message))

beacon_node/network/src/sync/network_context.rs

@@ -66,7 +66,7 @@ impl SyncNetworkContext {
             "count" => request.count,
             "peer" => format!("{:?}", peer_id)
         );
-        self.send_rpc_request(peer_id.clone(), RPCRequest::BlocksByRange(request))
+        self.send_rpc_request(peer_id, RPCRequest::BlocksByRange(request))
     }
 
     pub fn blocks_by_root_request(
@@ -81,7 +81,7 @@ impl SyncNetworkContext {
             "count" => request.block_roots.len(),
             "peer" => format!("{:?}", peer_id)
         );
-        self.send_rpc_request(peer_id.clone(), RPCRequest::BlocksByRoot(request))
+        self.send_rpc_request(peer_id, RPCRequest::BlocksByRoot(request))
     }
 
     pub fn downvote_peer(&mut self, peer_id: PeerId) {
@@ -91,7 +91,7 @@ impl SyncNetworkContext {
             "peer" => format!("{:?}", peer_id)
         );
         // TODO: Implement reputation
-        self.disconnect(peer_id.clone(), GoodbyeReason::Fault);
+        self.disconnect(peer_id, GoodbyeReason::Fault);
     }
 
     fn disconnect(&mut self, peer_id: PeerId, reason: GoodbyeReason) {

beacon_node/network/src/sync/range_sync/batch.rs

@@ -62,16 +62,16 @@ impl<T: EthSpec> PendingBatches<T> {
         let peer_request = batch.current_peer.clone();
         self.peer_requests
             .entry(peer_request)
-            .or_insert_with(|| HashSet::new())
+            .or_insert_with(HashSet::new)
             .insert(request_id);
         self.batches.insert(request_id, batch)
     }
 
-    pub fn remove(&mut self, request_id: &RequestId) -> Option<Batch<T>> {
+    pub fn remove(&mut self, request_id: RequestId) -> Option<Batch<T>> {
-        if let Some(batch) = self.batches.remove(request_id) {
+        if let Some(batch) = self.batches.remove(&request_id) {
             if let Entry::Occupied(mut entry) = self.peer_requests.entry(batch.current_peer.clone())
             {
-                entry.get_mut().remove(request_id);
+                entry.get_mut().remove(&request_id);
 
                 if entry.get().is_empty() {
                     entry.remove();
@@ -85,8 +85,8 @@ impl<T: EthSpec> PendingBatches<T> {
 
     /// Adds a block to the batches if the request id exists. Returns None if there is no batch
     /// matching the request id.
-    pub fn add_block(&mut self, request_id: &RequestId, block: BeaconBlock<T>) -> Option<()> {
+    pub fn add_block(&mut self, request_id: RequestId, block: BeaconBlock<T>) -> Option<()> {
-        let batch = self.batches.get_mut(request_id)?;
+        let batch = self.batches.get_mut(&request_id)?;
         batch.downloaded_blocks.push(block);
         Some(())
     }
@@ -101,7 +101,7 @@ impl<T: EthSpec> PendingBatches<T> {
     pub fn remove_batch_by_peer(&mut self, peer_id: &PeerId) -> Option<Batch<T>> {
         let request_ids = self.peer_requests.get(peer_id)?;
 
-        let request_id = request_ids.iter().next()?.clone();
+        let request_id = *request_ids.iter().next()?;
-        self.remove(&request_id)
+        self.remove(request_id)
     }
 }

beacon_node/network/src/sync/range_sync/chain.rs

@@ -144,11 +144,11 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
     ) -> Option<ProcessingResult> {
         if let Some(block) = beacon_block {
             // This is not a stream termination, simply add the block to the request
-            self.pending_batches.add_block(&request_id, block.clone())?;
+            self.pending_batches.add_block(request_id, block.clone())?;
-            return Some(ProcessingResult::KeepChain);
+            Some(ProcessingResult::KeepChain)
         } else {
             // A stream termination has been sent. This batch has ended. Process a completed batch.
-            let batch = self.pending_batches.remove(&request_id)?;
+            let batch = self.pending_batches.remove(request_id)?;
             Some(self.process_completed_batch(chain.clone(), network, batch, log))
         }
     }
@@ -433,7 +433,7 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
                 return true;
             }
         }
-        return false;
+        false
     }
 
     /// Returns a peer if there exists a peer which does not currently have a pending request.
@@ -500,10 +500,10 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
         &mut self,
         network: &mut SyncNetworkContext,
         peer_id: &PeerId,
-        request_id: &RequestId,
+        request_id: RequestId,
         log: &slog::Logger,
     ) -> Option<ProcessingResult> {
-        if let Some(batch) = self.pending_batches.remove(&request_id) {
+        if let Some(batch) = self.pending_batches.remove(request_id) {
             warn!(log, "Batch failed. RPC Error"; "id" => batch.id, "retries" => batch.retries, "peer" => format!("{:?}", peer_id));
 
             Some(self.failed_batch(network, batch, log))

beacon_node/network/src/sync/range_sync/range.rs

@@ -188,7 +188,7 @@ impl<T: BeaconChainTypes> RangeSync<T> {
                 debug!(self.log, "Adding peer to the existing head chain peer pool"; "head_root" => format!("{}",remote.head_root), "head_slot" => remote.head_slot, "peer_id" => format!("{:?}", peer_id));
 
                 // add the peer to the head's pool
-                chain.add_peer(network, peer_id.clone(), &self.log);
+                chain.add_peer(network, peer_id, &self.log);
             } else {
                 // There are no other head chains that match this peer's status, create a new one, and
                 let start_slot = std::cmp::min(local_info.head_slot, remote_finalized_slot);
@@ -305,7 +305,8 @@ impl<T: BeaconChainTypes> RangeSync<T> {
     /// retries. In this case, we need to remove the chain and re-status all the peers.
     fn remove_peer(&mut self, network: &mut SyncNetworkContext, peer_id: &PeerId) {
         let log_ref = &self.log;
-        match self.chains.head_finalized_request(|chain| {
+        if let Some((index, ProcessingResult::RemoveChain)) =
+            self.chains.head_finalized_request(|chain| {
                 if chain.peer_pool.remove(peer_id) {
                     // this chain contained the peer
                     while let Some(batch) = chain.pending_batches.remove_batch_by_peer(peer_id) {
@@ -321,14 +322,12 @@ impl<T: BeaconChainTypes> RangeSync<T> {
                 } else {
                     None
                 }
-        }) {
+            })
-            Some((index, ProcessingResult::RemoveChain)) => {
+        {
             // the chain needed to be removed
             debug!(self.log, "Chain being removed due to failed batch");
             self.chains.remove_chain(network, index, &self.log);
         }
-            _ => {} // chain didn't need to be removed, ignore
-        }
     }
 
     /// An RPC error has occurred.
@@ -344,7 +343,7 @@ impl<T: BeaconChainTypes> RangeSync<T> {
         // check that this request is pending
         let log_ref = &self.log;
         match self.chains.head_finalized_request(|chain| {
-            chain.inject_error(network, &peer_id, &request_id, log_ref)
+            chain.inject_error(network, &peer_id, request_id, log_ref)
         }) {
             Some((_, ProcessingResult::KeepChain)) => {} // error handled chain persists
             Some((index, ProcessingResult::RemoveChain)) => {

beacon_node/rest_api/src/helpers.rs

@@ -145,7 +145,7 @@ pub fn state_at_slot<T: BeaconChainTypes>(
         // I'm not sure if this `.clone()` will be optimized out. If not, it seems unnecessary.
         Ok((
             beacon_chain.head()?.beacon_state_root,
-            beacon_chain.head()?.beacon_state.clone(),
+            beacon_chain.head()?.beacon_state,
         ))
     } else {
         let root = state_root_at_slot(beacon_chain, slot)?;
@@ -209,7 +209,7 @@ pub fn state_root_at_slot<T: BeaconChainTypes>(
         //
         // Use `per_slot_processing` to advance the head state to the present slot,
         // assuming that all slots do not contain a block (i.e., they are skipped slots).
-        let mut state = beacon_chain.head()?.beacon_state.clone();
+        let mut state = beacon_chain.head()?.beacon_state;
         let spec = &T::EthSpec::default_spec();
 
         for _ in state.slot.as_u64()..slot.as_u64() {

beacon_node/rest_api/src/lib.rs

@@ -54,6 +54,8 @@ pub struct NetworkInfo<T: BeaconChainTypes> {
     pub network_chan: mpsc::UnboundedSender<NetworkMessage>,
 }
 
+// Allowing more than 7 arguments.
+#[allow(clippy::too_many_arguments)]
 pub fn start_server<T: BeaconChainTypes>(
     config: &Config,
     executor: &TaskExecutor,

beacon_node/rest_api/src/router.rs

@@ -19,6 +19,8 @@ where
     Box::new(item.into_future())
 }
 
+// Allowing more than 7 arguments.
+#[allow(clippy::too_many_arguments)]
 pub fn route<T: BeaconChainTypes>(
     req: Request<Body>,
     beacon_chain: Arc<BeaconChain<T>>,

beacon_node/rest_api/tests/test.rs

@@ -47,8 +47,7 @@ fn get_randao_reveal<T: BeaconChainTypes>(
         .head()
         .expect("should get head")
         .beacon_state
-        .fork
+        .fork;
-        .clone();
     let proposer_index = beacon_chain
         .block_proposer(slot)
         .expect("should get proposer index");
@@ -69,8 +68,7 @@ fn sign_block<T: BeaconChainTypes>(
         .head()
         .expect("should get head")
         .beacon_state
-        .fork
+        .fork;
-        .clone();
     let proposer_index = beacon_chain
         .block_proposer(block.slot)
         .expect("should get proposer index");
@@ -91,11 +89,7 @@ fn validator_produce_attestation() {
         .client
         .beacon_chain()
         .expect("client should have beacon chain");
-    let state = beacon_chain
+    let state = beacon_chain.head().expect("should get head").beacon_state;
-        .head()
-        .expect("should get head")
-        .beacon_state
-        .clone();
 
     let validator_index = 0;
     let duties = state
@@ -169,7 +163,7 @@ fn validator_produce_attestation() {
             remote_node
                 .http
                 .validator()
-                .publish_attestation(attestation.clone()),
+                .publish_attestation(attestation),
         )
         .expect("should publish attestation");
     assert!(
@@ -344,7 +338,7 @@ fn validator_block_post() {
             remote_node
                 .http
                 .validator()
-                .produce_block(slot, randao_reveal.clone()),
+                .produce_block(slot, randao_reveal),
         )
         .expect("should fetch block from http api");
 
@@ -360,12 +354,12 @@ fn validator_block_post() {
         );
     }
 
-    sign_block(beacon_chain.clone(), &mut block, spec);
+    sign_block(beacon_chain, &mut block, spec);
     let block_root = block.canonical_root();
 
     let publish_status = env
         .runtime()
-        .block_on(remote_node.http.validator().publish_block(block.clone()))
+        .block_on(remote_node.http.validator().publish_block(block))
         .expect("should publish block");
 
     if cfg!(not(feature = "fake_crypto")) {
@@ -419,7 +413,7 @@ fn validator_block_get() {
         .expect("client should have beacon chain");
 
     let slot = Slot::new(1);
-    let randao_reveal = get_randao_reveal(beacon_chain.clone(), slot, spec);
+    let randao_reveal = get_randao_reveal(beacon_chain, slot, spec);
 
     let block = env
         .runtime()

beacon_node/src/config.rs

@@ -268,7 +268,7 @@ pub fn get_configs<E: EthSpec>(
     if eth2_config.spec_constants != client_config.spec_constants {
         crit!(log, "Specification constants do not match.";
               "client_config" => client_config.spec_constants.to_string(),
-              "eth2_config" => eth2_config.spec_constants.to_string()
+              "eth2_config" => eth2_config.spec_constants
         );
         return Err("Specification constant mismatch".into());
     }

beacon_node/store/benches/benches.rs

@@ -24,7 +24,6 @@ fn get_state<E: EthSpec>(validator_count: usize) -> BeaconState<E> {
     }
 
     state.validators = (0..validator_count)
-        .into_iter()
         .collect::<Vec<_>>()
         .par_iter()
         .map(|&i| Validator {
@@ -77,7 +76,7 @@ fn all_benches(c: &mut Criterion) {
         .sample_size(10),
     );
 
-    let inner_state = state.clone();
+    let inner_state = state;
     c.bench(
         &format!("{}_validators", validator_count),
         Benchmark::new("encode/beacon_state/committee_cache[0]", move |b| {

beacon_node/store/examples/ssz_encode_state_container.rs

@@ -27,7 +27,6 @@ fn get_state<E: EthSpec>(validator_count: usize) -> BeaconState<E> {
     }
 
     state.validators = (0..validator_count)
-        .into_iter()
         .collect::<Vec<_>>()
         .par_iter()
         .map(|&i| Validator {

beacon_node/store/src/block_at_slot.rs

@@ -1,5 +1,6 @@
 use super::*;
 use ssz::{Decode, DecodeError};
+use std::cmp::Ordering;
 
 fn get_block_bytes<T: Store<E>, E: EthSpec>(
     store: &T,
@@ -45,12 +46,10 @@ fn get_at_preceeding_slot<T: Store<E>, E: EthSpec>(
         if let Some(bytes) = get_block_bytes::<_, E>(store, root)? {
             let this_slot = read_slot_from_block_bytes(&bytes)?;
 
-            if this_slot == slot {
+            match this_slot.cmp(&slot) {
-                break Ok(Some((root, bytes)));
+                Ordering::Equal => break Ok(Some((root, bytes))),
-            } else if this_slot < slot {
+                Ordering::Less => break Ok(None),
-                break Ok(None);
+                Ordering::Greater => root = read_parent_root_from_block_bytes(&bytes)?,
-            } else {
-                root = read_parent_root_from_block_bytes(&bytes)?;
             }
         } else {
             break Ok(None);

beacon_node/store/src/block_root_tree.rs

@@ -237,7 +237,7 @@ mod test {
                 .add_block_root(int_hash(i), int_hash(i - 1), Slot::new(i))
                 .expect("add_block_root ok");
 
-            let expected = (1..i + 1)
+            let expected = (1..=i)
                 .rev()
                 .map(|j| (int_hash(j), Slot::new(j)))
                 .collect::<Vec<_>>();
@@ -262,12 +262,12 @@ mod test {
                 .add_block_root(int_hash(i), int_hash(i - step_length), Slot::new(i))
                 .expect("add_block_root ok");
 
-            let sparse_expected = (1..i + 1)
+            let sparse_expected = (1..=i)
                 .rev()
                 .step_by(step_length as usize)
                 .map(|j| (int_hash(j), Slot::new(j)))
                 .collect_vec();
-            let every_slot_expected = (1..i + 1)
+            let every_slot_expected = (1..=i)
                 .rev()
                 .map(|j| {
                     let nearest = 1 + (j - 1) / step_length * step_length;
@@ -343,10 +343,9 @@ mod test {
 
         // Check that advancing the finalized root onto one side completely removes the other
         // side.
-        let fin_tree = tree.clone();
+        let fin_tree = tree;
         let prune_point = num_blocks / 2;
         let remaining_fork1_blocks = all_fork1_blocks
-            .clone()
             .into_iter()
             .take_while(|(_, slot)| *slot >= prune_point)
             .collect_vec();

beacon_node/store/src/chunked_vector.rs

@@ -185,7 +185,7 @@ pub trait Field<E: EthSpec>: Copy {
             .values
             .first()
             .cloned()
-            .ok_or(ChunkError::MissingGenesisValue.into())
+            .ok_or_else(|| ChunkError::MissingGenesisValue.into())
     }
 
     /// Store the given `value` as the genesis value for this field, unless stored already.
@@ -685,7 +685,7 @@ mod test {
         ];
 
         assert_eq!(
-            stitch(chunks.clone(), 2, 6, chunk_size, 12, 99).unwrap(),
+            stitch(chunks, 2, 6, chunk_size, 12, 99).unwrap(),
             vec![99, 99, 2, 3, 4, 5, 99, 99, 99, 99, 99, 99]
         );
     }
@@ -707,7 +707,7 @@ mod test {
         );
 
         assert_eq!(
-            stitch(chunks.clone(), 2, 10, chunk_size, 8, default).unwrap(),
+            stitch(chunks, 2, 10, chunk_size, 8, default).unwrap(),
             vec![v(8), v(9), v(2), v(3), v(4), v(5), v(6), v(7)]
         );
     }

beacon_node/store/src/forwards_iter.rs

@@ -20,9 +20,9 @@ pub struct SimpleForwardsBlockRootsIterator {
 /// Fusion of the above two approaches to forwards iteration. Fast and efficient.
 pub enum HybridForwardsBlockRootsIterator<E: EthSpec> {
     PreFinalization {
-        iter: FrozenForwardsBlockRootsIterator<E>,
+        iter: Box<FrozenForwardsBlockRootsIterator<E>>,
         /// Data required by the `PostFinalization` iterator when we get to it.
-        continuation_data: Option<(BeaconState<E>, Hash256)>,
+        continuation_data: Box<Option<(BeaconState<E>, Hash256)>>,
     },
     PostFinalization {
         iter: SimpleForwardsBlockRootsIterator,
@@ -99,13 +99,13 @@ impl<E: EthSpec> HybridForwardsBlockRootsIterator<E> {
 
         if start_slot < latest_restore_point_slot {
             PreFinalization {
-                iter: FrozenForwardsBlockRootsIterator::new(
+                iter: Box::new(FrozenForwardsBlockRootsIterator::new(
                     store,
                     start_slot,
                     latest_restore_point_slot,
                     spec,
-                ),
+                )),
-                continuation_data: Some((end_state, end_block_root)),
+                continuation_data: Box::new(Some((end_state, end_block_root))),
             }
         } else {
             PostFinalization {

beacon_node/store/src/hot_cold_store.rs

@@ -145,14 +145,15 @@ impl<E: EthSpec> Store<E> for HotColdDB<E> {
         let current_split_slot = store.get_split_slot();
 
         if frozen_head.slot < current_split_slot {
-            Err(HotColdDBError::FreezeSlotError {
+            return Err(HotColdDBError::FreezeSlotError {
                 current_split_slot,
                 proposed_split_slot: frozen_head.slot,
-            })?;
+            }
+            .into());
         }
 
         if frozen_head.slot % E::slots_per_epoch() != 0 {
-            Err(HotColdDBError::FreezeSlotUnaligned(frozen_head.slot))?;
+            return Err(HotColdDBError::FreezeSlotUnaligned(frozen_head.slot).into());
         }
 
         // 1. Copy all of the states between the head and the split slot, from the hot DB
@@ -574,7 +575,7 @@ impl<E: EthSpec> HotColdDB<E> {
         let key = Self::restore_point_key(restore_point_index);
         RestorePointHash::db_get(&self.cold_db, &key)?
             .map(|r| r.state_root)
-            .ok_or(HotColdDBError::MissingRestorePointHash(restore_point_index).into())
+            .ok_or_else(|| HotColdDBError::MissingRestorePointHash(restore_point_index).into())
     }
 
     /// Store the state root of a restore point.

beacon_node/store/src/iter.rs

@@ -345,7 +345,7 @@ mod test {
         state_b.state_roots[0] = state_a_root;
         store.put_state(&state_a_root, &state_a).unwrap();
 
-        let iter = BlockRootsIterator::new(store.clone(), &state_b);
+        let iter = BlockRootsIterator::new(store, &state_b);
 
         assert!(
             iter.clone().any(|(_root, slot)| slot == 0),
@@ -394,7 +394,7 @@ mod test {
         store.put_state(&state_a_root, &state_a).unwrap();
         store.put_state(&state_b_root, &state_b).unwrap();
 
-        let iter = StateRootsIterator::new(store.clone(), &state_b);
+        let iter = StateRootsIterator::new(store, &state_b);
 
         assert!(
             iter.clone().any(|(_root, slot)| slot == 0),

beacon_node/store/src/memory_store.rs

@@ -47,11 +47,7 @@ impl<E: EthSpec> Store<E> for MemoryStore<E> {
     fn get_bytes(&self, col: &str, key: &[u8]) -> Result<Option<Vec<u8>>, Error> {
         let column_key = Self::get_key_for_col(col, key);
 
-        Ok(self
+        Ok(self.db.read().get(&column_key).cloned())
-            .db
-            .read()
-            .get(&column_key)
-            .and_then(|val| Some(val.clone())))
     }
 
     /// Puts a key in the database.

beacon_node/store/src/migrate.rs

@@ -60,13 +60,12 @@ impl<E: EthSpec, S: Store<E>> Migrate<S, E> for BlockingMigrator<S> {
     }
 }
 
+type MpscSender<E> = mpsc::Sender<(Hash256, BeaconState<E>)>;
+
 /// Migrator that runs a background thread to migrate state from the hot to the cold database.
 pub struct BackgroundMigrator<E: EthSpec> {
     db: Arc<DiskStore<E>>,
-    tx_thread: Mutex<(
+    tx_thread: Mutex<(MpscSender<E>, thread::JoinHandle<()>)>,
-        mpsc::Sender<(Hash256, BeaconState<E>)>,
-        thread::JoinHandle<()>,
-    )>,
 }
 
 impl<E: EthSpec> Migrate<DiskStore<E>, E> for BackgroundMigrator<E> {

eth2/lmd_ghost/src/reduced_tree.rs

@@ -8,6 +8,7 @@ use itertools::Itertools;
 use parking_lot::RwLock;
 use ssz::{Decode, Encode};
 use ssz_derive::{Decode, Encode};
+use std::cmp::Ordering;
 use std::collections::HashMap;
 use std::fmt;
 use std::marker::PhantomData;
@@ -182,13 +183,15 @@ impl ReducedTreeSsz {
         }
     }
 
-    pub fn to_reduced_tree<T, E>(
+    pub fn into_reduced_tree<T, E>(
         self,
         store: Arc<T>,
         block_root_tree: Arc<BlockRootTree>,
     ) -> Result<ReducedTree<T, E>> {
         if self.node_hashes.len() != self.nodes.len() {
-            Error::InvalidReducedTreeSsz("node_hashes and nodes should have equal length".into());
+            return Err(Error::InvalidReducedTreeSsz(
+                "node_hashes and nodes should have equal length".to_string(),
+            ));
         }
         let nodes: HashMap<_, _> = self
             .node_hashes
@@ -740,16 +743,19 @@ where
                     if a_slot < self.root.1 || b_slot < self.root.1 {
                         None
                     } else {
-                        if a_slot < b_slot {
+                        match a_slot.cmp(&b_slot) {
+                            Ordering::Less => {
                                 for _ in a_slot.as_u64()..b_slot.as_u64() {
                                     b_root = b_iter.next()?.0;
                                 }
-                        } else if a_slot > b_slot {
+                            }
+                            Ordering::Greater => {
                                 for _ in b_slot.as_u64()..a_slot.as_u64() {
                                     a_root = a_iter.next()?.0;
                                 }
                             }
-
+                            Ordering::Equal => (),
+                        }
                         Some((a_root, b_root))
                     }
                 }
@@ -876,7 +882,7 @@ where
         block_root_tree: Arc<BlockRootTree>,
     ) -> Result<Self> {
         let reduced_tree_ssz = ReducedTreeSsz::from_ssz_bytes(bytes)?;
-        Ok(reduced_tree_ssz.to_reduced_tree(store, block_root_tree)?)
+        Ok(reduced_tree_ssz.into_reduced_tree(store, block_root_tree)?)
     }
 }
 
@@ -1013,8 +1019,7 @@ mod tests {
         );
         let ssz_tree = ReducedTreeSsz::from_reduced_tree(&tree);
         let bytes = tree.as_bytes();
-        let recovered_tree =
+        let recovered_tree = ReducedTree::from_bytes(&bytes, store, block_root_tree).unwrap();
-            ReducedTree::from_bytes(&bytes, store.clone(), block_root_tree).unwrap();
 
         let recovered_ssz = ReducedTreeSsz::from_reduced_tree(&recovered_tree);
         assert_eq!(ssz_tree, recovered_ssz);

eth2/operation_pool/src/max_cover.rs

@@ -167,7 +167,7 @@ mod test {
             HashSet::from_iter(vec![5, 6, 7, 8]),      // 4, 4*
             HashSet::from_iter(vec![0, 1, 2, 3, 4]),   // 5*
         ];
-        let cover = maximum_cover(sets.clone(), 3);
+        let cover = maximum_cover(sets, 3);
         assert_eq!(quality(&cover), 11);
     }
 
@@ -182,7 +182,7 @@ mod test {
             HashSet::from_iter(vec![1, 5, 6, 8]),
             HashSet::from_iter(vec![1, 7, 11, 19]),
         ];
-        let cover = maximum_cover(sets.clone(), 5);
+        let cover = maximum_cover(sets, 5);
         assert_eq!(quality(&cover), 19);
         assert_eq!(cover.len(), 5);
     }

eth2/state_processing/benches/benches.rs

@@ -311,11 +311,7 @@ fn bench_block<T: EthSpec>(
                     )
                     .expect("should get indexed attestation");
 
-                    (
+                    (local_spec.clone(), local_state.clone(), indexed_attestation)
-                        local_spec.clone(),
-                        local_state.clone(),
-                        indexed_attestation.clone(),
-                    )
                 },
                 |(spec, ref mut state, indexed_attestation)| {
                     black_box(
@@ -349,11 +345,7 @@ fn bench_block<T: EthSpec>(
                     )
                     .expect("should get indexed attestation");
 
-                    (
+                    (local_spec.clone(), local_state.clone(), indexed_attestation)
-                        local_spec.clone(),
-                        local_state.clone(),
-                        indexed_attestation.clone(),
-                    )
                 },
                 |(spec, ref mut state, indexed_attestation)| {
                     black_box(
@@ -373,7 +365,7 @@ fn bench_block<T: EthSpec>(
     );
 
     let local_block = block.clone();
-    let local_state = state.clone();
+    let local_state = state;
     c.bench(
         &title,
         Benchmark::new("get_attesting_indices", move |b| {
@@ -409,7 +401,7 @@ fn bench_block<T: EthSpec>(
         .sample_size(10),
     );
 
-    let local_block = block.clone();
+    let local_block = block;
     c.bench(
         &title,
         Benchmark::new("ssz_block_len", move |b| {

eth2/state_processing/tests/tests.rs

@@ -29,7 +29,7 @@ where
     F: FnMut(&mut BlockBuilder<T>),
     G: FnMut(&mut BeaconBlock<T>),
 {
-    let (mut block, state) = get_block::<T, _>(mutate_builder);
+    let (mut block, mut state) = get_block::<T, _>(mutate_builder);
 
     /*
      * Control check to ensure the valid block should pass verification.
@@ -79,7 +79,7 @@ where
 
     assert_eq!(
         per_block_processing(
-            &mut state.clone(),
+            &mut state,
             &block,
             None,
             BlockSignatureStrategy::VerifyBulk,

eth2/types/benches/benches.rs

@@ -22,7 +22,6 @@ fn get_state<E: EthSpec>(validator_count: usize) -> BeaconState<E> {
     }
 
     state.validators = (0..validator_count)
-        .into_iter()
         .collect::<Vec<_>>()
         .par_iter()
         .map(|&i| Validator {
@@ -91,7 +90,7 @@ fn all_benches(c: &mut Criterion) {
         .sample_size(10),
     );
 
-    let inner_state = state.clone();
+    let inner_state = state;
     c.bench(
         &format!("{}_validators", validator_count),
         Benchmark::new("clone_without_caches/beacon_state", move |b| {

eth2/types/src/attestation.rs

@@ -71,13 +71,13 @@ impl<T: EthSpec> Attestation<T> {
         if self
             .aggregation_bits
             .get(committee_position)
-            .map_err(|e| Error::SszTypesError(e))?
+            .map_err(Error::SszTypesError)?
         {
             Err(Error::AlreadySigned(committee_position))
         } else {
             self.aggregation_bits
                 .set(committee_position, true)
-                .map_err(|e| Error::SszTypesError(e))?;
+                .map_err(Error::SszTypesError)?;
 
             let message = self.data.tree_hash_root();
             let domain = spec.get_domain(self.data.target.epoch, Domain::BeaconAttester, fork);

eth2/types/src/beacon_state.rs

@@ -897,7 +897,7 @@ impl<T: EthSpec> BeaconState<T> {
             .enumerate()
             .skip(self.pubkey_cache.len())
         {
-            let success = self.pubkey_cache.insert(validator.pubkey.clone().into(), i);
+            let success = self.pubkey_cache.insert(validator.pubkey.clone(), i);
             if !success {
                 return Err(Error::PubkeyCacheInconsistent);
             }
@@ -957,7 +957,7 @@ impl<T: EthSpec> BeaconState<T> {
                 validator
                     .pubkey
                     .decompress()
-                    .map_err(|e| Error::InvalidValidatorPubkey(e))
+                    .map_err(Error::InvalidValidatorPubkey)
             } else {
                 Ok(())
             }

eth2/types/src/test_utils/builders/testing_attestation_builder.rs

@@ -24,9 +24,8 @@ impl<T: EthSpec> TestingAttestationBuilder<T> {
 
         let mut aggregation_bits_len = committee.len();
 
-        match test_task {
+        if test_task == AttestationTestTask::BadAggregationBitfieldLen {
-            AttestationTestTask::BadAggregationBitfieldLen => aggregation_bits_len += 1,
+            aggregation_bits_len += 1
-            _ => (),
         }
 
         let mut aggregation_bits = BitList::with_capacity(aggregation_bits_len).unwrap();

eth2/types/src/test_utils/builders/testing_beacon_state_builder.rs

@@ -15,7 +15,7 @@ pub const KEYPAIRS_FILE: &str = "keypairs.raw_keypairs";
 /// `./keypairs.raw_keypairs`.
 pub fn keypairs_path() -> PathBuf {
     let dir = dirs::home_dir()
-        .and_then(|home| Some(home.join(".lighthouse")))
+        .map(|home| (home.join(".lighthouse")))
         .unwrap_or_else(|| PathBuf::from(""));
     dir.join(KEYPAIRS_FILE)
 }
@@ -42,7 +42,7 @@ impl<T: EthSpec> TestingBeaconStateBuilder<T> {
     /// If the file does not contain enough keypairs or is invalid.
     pub fn from_default_keypairs_file_if_exists(validator_count: usize, spec: &ChainSpec) -> Self {
         let dir = dirs::home_dir()
-            .and_then(|home| Some(home.join(".lighthouse")))
+            .map(|home| home.join(".lighthouse"))
             .unwrap_or_else(|| PathBuf::from(""));
         let file = dir.join(KEYPAIRS_FILE);
 

eth2/types/src/test_utils/builders/testing_proposer_slashing_builder.rs

@@ -30,7 +30,7 @@ impl TestingProposerSlashingBuilder {
         let slot = Slot::new(0);
         let hash_1 = Hash256::from([1; 32]);
         let hash_2 = if test_task == ProposerSlashingTestTask::ProposalsIdentical {
-            hash_1.clone()
+            hash_1
         } else {
             Hash256::from([2; 32])
         };

eth2/utils/bls/src/aggregate_signature.rs

@@ -99,9 +99,10 @@ impl AggregateSignature {
         for byte in bytes {
             if *byte != 0 {
                 let sig = RawAggregateSignature::from_bytes(&bytes).map_err(|_| {
-                    DecodeError::BytesInvalid(
+                    DecodeError::BytesInvalid(format!(
-                        format!("Invalid AggregateSignature bytes: {:?}", bytes).to_string(),
+                        "Invalid AggregateSignature bytes: {:?}",
-                    )
+                        bytes
+                    ))
                 })?;
 
                 return Ok(Self {

eth2/utils/bls/src/public_key.rs

@@ -39,7 +39,7 @@ impl PublicKey {
     /// Converts compressed bytes to PublicKey
     pub fn from_bytes(bytes: &[u8]) -> Result<Self, DecodeError> {
         let pubkey = RawPublicKey::from_bytes(&bytes).map_err(|_| {
-            DecodeError::BytesInvalid(format!("Invalid PublicKey bytes: {:?}", bytes).to_string())
+            DecodeError::BytesInvalid(format!("Invalid PublicKey bytes: {:?}", bytes))
         })?;
 
         Ok(PublicKey(pubkey))

eth2/utils/bls/src/signature.rs

@@ -81,9 +81,7 @@ impl Signature {
         for byte in bytes {
             if *byte != 0 {
                 let raw_signature = RawSignature::from_bytes(&bytes).map_err(|_| {
-                    DecodeError::BytesInvalid(
+                    DecodeError::BytesInvalid(format!("Invalid Signature bytes: {:?}", bytes))
-                        format!("Invalid Signature bytes: {:?}", bytes).to_string(),
-                    )
                 })?;
                 return Ok(Signature {
                     signature: raw_signature,

eth2/utils/bls/src/signature_set.rs

@@ -158,17 +158,17 @@ fn aggregate_public_keys<'a>(public_keys: &'a [Cow<'a, G1Point>]) -> G1Point {
 }
 
 pub trait G1Ref {
-    fn g1_ref<'a>(&'a self) -> Cow<'a, G1Point>;
+    fn g1_ref(&self) -> Cow<'_, G1Point>;
 }
 
 impl G1Ref for AggregatePublicKey {
-    fn g1_ref<'a>(&'a self) -> Cow<'a, G1Point> {
+    fn g1_ref(&self) -> Cow<'_, G1Point> {
         Cow::Borrowed(&self.as_raw().point)
     }
 }
 
 impl G1Ref for PublicKey {
-    fn g1_ref<'a>(&'a self) -> Cow<'a, G1Point> {
+    fn g1_ref(&self) -> Cow<'_, G1Point> {
         Cow::Borrowed(&self.as_raw().point)
     }
 }

eth2/utils/cached_tree_hash/src/test.rs

@@ -131,8 +131,8 @@ fn variable_list_h256_test<Len: Unsigned>(leaves_and_skips: Vec<(u64, bool)>) ->
     for (end, (_, update_cache)) in leaves_and_skips.into_iter().enumerate() {
         list = VariableList::new(leaves[..end].to_vec()).unwrap();
 
-        if update_cache {
+        if update_cache
-            if list
+            && list
                 .recalculate_tree_hash_root(&mut cache)
                 .unwrap()
                 .as_bytes()
@@ -141,7 +141,5 @@ fn variable_list_h256_test<Len: Unsigned>(leaves_and_skips: Vec<(u64, bool)>) ->
             return false;
         }
     }
-    }
-
     true
 }

eth2/utils/deposit_contract/src/lib.rs

@@ -58,7 +58,7 @@ mod tests {
         let spec = &E::default_spec();
 
         let keypair = generate_deterministic_keypair(42);
-        let deposit = get_deposit(keypair.clone(), spec);
+        let deposit = get_deposit(keypair, spec);
 
         let data = eth1_tx_data(&deposit).expect("should produce tx data");
 

eth2/utils/eth2_interop_keypairs/src/lib.rs

@@ -123,8 +123,7 @@ fn string_to_bytes(string: &str) -> Result<Vec<u8>, String> {
 /// Uses this as reference:
 /// https://github.com/ethereum/eth2.0-pm/blob/9a9dbcd95e2b8e10287797bd768014ab3d842e99/interop/mocked_start/keygen_10_validators.yaml
 pub fn keypairs_from_yaml_file(path: PathBuf) -> Result<Vec<Keypair>, String> {
-    let file =
+    let file = File::open(path).map_err(|e| format!("Unable to open YAML key file: {}", e))?;
-        File::open(path.clone()).map_err(|e| format!("Unable to open YAML key file: {}", e))?;
 
     serde_yaml::from_reader::<_, Vec<YamlKeypair>>(file)
         .map_err(|e| format!("Could not parse YAML: {:?}", e))?

eth2/utils/eth2_testnet_config/src/lib.rs

@@ -227,7 +227,7 @@ mod tests {
         let genesis_state = Some(BeaconState::new(42, eth1_data, spec));
         let yaml_config = Some(YamlConfig::from_spec::<E>(spec));
 
-        do_test::<E>(boot_enr, genesis_state.clone(), yaml_config.clone());
+        do_test::<E>(boot_enr, genesis_state, yaml_config);
         do_test::<E>(None, None, None);
     }
 
@@ -237,13 +237,13 @@ mod tests {
         yaml_config: Option<YamlConfig>,
     ) {
         let temp_dir = TempDir::new("eth2_testnet_test").expect("should create temp dir");
-        let base_dir = PathBuf::from(temp_dir.path().join("my_testnet"));
+        let base_dir = temp_dir.path().join("my_testnet");
         let deposit_contract_address = "0xBB9bc244D798123fDe783fCc1C72d3Bb8C189413".to_string();
         let deposit_contract_deploy_block = 42;
 
         let testnet: Eth2TestnetConfig<E> = Eth2TestnetConfig {
-            deposit_contract_address: deposit_contract_address.clone(),
+            deposit_contract_address,
-            deposit_contract_deploy_block: deposit_contract_deploy_block,
+            deposit_contract_deploy_block,
             boot_enr,
             genesis_state,
             yaml_config,

eth2/utils/lighthouse_metrics/src/lib.rs

@@ -1,3 +1,4 @@
+#![allow(clippy::needless_doctest_main)]
 //! A wrapper around the `prometheus` crate that provides a global, `lazy_static` metrics registry
 //! and functions to add and use the following components (more info at
 //! [Prometheus docs](https://prometheus.io/docs/concepts/metric_types/)):

eth2/utils/ssz/src/decode.rs

@@ -99,7 +99,7 @@ impl<'a> SszDecoderBuilder<'a> {
             let previous_offset = self
                 .offsets
                 .last()
-                .and_then(|o| Some(o.offset))
+                .map(|o| o.offset)
                 .unwrap_or_else(|| BYTES_PER_LENGTH_OFFSET);
 
             if (previous_offset > offset) || (offset > self.bytes.len()) {
@@ -179,7 +179,7 @@ impl<'a> SszDecoderBuilder<'a> {
 ///     b: Vec<u16>,
 /// }
 ///
-/// fn main() {
+/// fn ssz_decoding_example() {
 ///     let foo = Foo {
 ///         a: 42,
 ///         b: vec![1, 3, 3, 7]

eth2/utils/ssz/src/decode/impls.rs

@@ -207,9 +207,10 @@ impl Decode for bool {
             match bytes[0] {
                 0b0000_0000 => Ok(false),
                 0b0000_0001 => Ok(true),
-                _ => Err(DecodeError::BytesInvalid(
+                _ => Err(DecodeError::BytesInvalid(format!(
-                    format!("Out-of-range for boolean: {}", bytes[0]).to_string(),
+                    "Out-of-range for boolean: {}",
-                )),
+                    bytes[0]
+                ))),
             }
         }
     }

eth2/utils/ssz/src/encode.rs

@@ -64,7 +64,7 @@ pub trait Encode {
 ///     b: Vec<u16>,
 /// }
 ///
-/// fn main() {
+/// fn ssz_encode_example() {
 ///     let foo = Foo {
 ///         a: 42,
 ///         b: vec![1, 3, 3, 7]

eth2/utils/ssz/src/lib.rs

@@ -17,7 +17,7 @@
 //!     b: Vec<u16>,
 //! }
 //!
-//! fn main() {
+//! fn ssz_encode_decode_example() {
 //!     let foo = Foo {
 //!         a: 42,
 //!         b: vec![1, 3, 3, 7]

eth2/utils/ssz/tests/tests.rs

@@ -2,6 +2,7 @@ use ethereum_types::H256;
 use ssz::{Decode, DecodeError, Encode};
 use ssz_derive::{Decode, Encode};
 
+#[allow(clippy::zero_prefixed_literal)]
 mod round_trip {
     use super::*;
 

eth2/utils/ssz_types/src/bitfield.rs

@@ -739,6 +739,7 @@ mod bitvector {
 }
 
 #[cfg(test)]
+#[allow(clippy::cognitive_complexity)]
 mod bitlist {
     use super::*;
     use crate::BitList;
@@ -937,7 +938,7 @@ mod bitlist {
     fn test_set_unset(num_bits: usize) {
         let mut bitfield = BitList1024::with_capacity(num_bits).unwrap();
 
-        for i in 0..num_bits + 1 {
+        for i in 0..=num_bits {
             if i < num_bits {
                 // Starts as false
                 assert_eq!(bitfield.get(i), Ok(false));
@@ -1023,10 +1024,7 @@ mod bitlist {
             vec![0b1111_1111, 0b0000_0000]
         );
         bitfield.set(8, true).unwrap();
-        assert_eq!(
+        assert_eq!(bitfield.into_raw_bytes(), vec![0b1111_1111, 0b0000_0001]);
-            bitfield.clone().into_raw_bytes(),
-            vec![0b1111_1111, 0b0000_0001]
-        );
     }
 
     #[test]

eth2/utils/ssz_types/src/fixed_vector.rs

@@ -261,15 +261,15 @@ mod test {
     #[test]
     fn new() {
         let vec = vec![42; 5];
-        let fixed: Result<FixedVector<u64, U4>, _> = FixedVector::new(vec.clone());
+        let fixed: Result<FixedVector<u64, U4>, _> = FixedVector::new(vec);
         assert!(fixed.is_err());
 
         let vec = vec![42; 3];
-        let fixed: Result<FixedVector<u64, U4>, _> = FixedVector::new(vec.clone());
+        let fixed: Result<FixedVector<u64, U4>, _> = FixedVector::new(vec);
         assert!(fixed.is_err());
 
         let vec = vec![42; 4];
-        let fixed: Result<FixedVector<u64, U4>, _> = FixedVector::new(vec.clone());
+        let fixed: Result<FixedVector<u64, U4>, _> = FixedVector::new(vec);
         assert!(fixed.is_ok());
     }
 
@@ -299,7 +299,7 @@ mod test {
         assert_eq!(&fixed[..], &vec![42, 42, 42, 0][..]);
 
         let vec = vec![];
-        let fixed: FixedVector<u64, U4> = FixedVector::from(vec.clone());
+        let fixed: FixedVector<u64, U4> = FixedVector::from(vec);
         assert_eq!(&fixed[..], &vec![0, 0, 0, 0][..]);
     }
 

eth2/utils/ssz_types/src/variable_list.rs

@@ -247,15 +247,15 @@ mod test {
     #[test]
     fn new() {
         let vec = vec![42; 5];
-        let fixed: Result<VariableList<u64, U4>, _> = VariableList::new(vec.clone());
+        let fixed: Result<VariableList<u64, U4>, _> = VariableList::new(vec);
         assert!(fixed.is_err());
 
         let vec = vec![42; 3];
-        let fixed: Result<VariableList<u64, U4>, _> = VariableList::new(vec.clone());
+        let fixed: Result<VariableList<u64, U4>, _> = VariableList::new(vec);
         assert!(fixed.is_ok());
 
         let vec = vec![42; 4];
-        let fixed: Result<VariableList<u64, U4>, _> = VariableList::new(vec.clone());
+        let fixed: Result<VariableList<u64, U4>, _> = VariableList::new(vec);
         assert!(fixed.is_ok());
     }
 
@@ -285,7 +285,7 @@ mod test {
         assert_eq!(&fixed[..], &vec![42, 42, 42][..]);
 
         let vec = vec![];
-        let fixed: VariableList<u64, U4> = VariableList::from(vec.clone());
+        let fixed: VariableList<u64, U4> = VariableList::from(vec);
         assert_eq!(&fixed[..], &vec![][..]);
     }
 

eth2/utils/tree_hash_derive/src/lib.rs

@@ -46,7 +46,7 @@ fn get_hashable_fields_and_their_caches<'a>(
 ///
 /// Return `Some(cache_field_name)` if the field has a cached tree hash attribute,
 /// or `None` otherwise.
-fn get_cache_field_for<'a>(field: &'a syn::Field) -> Option<syn::Ident> {
+fn get_cache_field_for(field: &syn::Field) -> Option<syn::Ident> {
     use syn::{MetaList, NestedMeta};
 
     let parsed_attrs = cached_tree_hash_attr_metas(&field.attrs);

lcli/src/deploy_deposit_contract.rs

@@ -94,12 +94,12 @@ pub fn run<T: EthSpec>(mut env: Environment<T>, matches: &ArgMatches) -> Result<
 
     info!("Writing config to {:?}", output_dir);
 
-    let mut spec = lighthouse_testnet_spec(env.core_context().eth2_config.spec.clone());
+    let mut spec = lighthouse_testnet_spec(env.core_context().eth2_config.spec);
     spec.min_genesis_time = min_genesis_time;
     spec.min_genesis_active_validator_count = min_genesis_active_validator_count;
 
     let testnet_config: Eth2TestnetConfig<T> = Eth2TestnetConfig {
-        deposit_contract_address: format!("{}", deposit_contract.address()),
+        deposit_contract_address: deposit_contract.address(),
         deposit_contract_deploy_block: deploy_block.as_u64(),
         boot_enr: None,
         genesis_state: None,
@@ -152,7 +152,7 @@ pub fn parse_password(matches: &ArgMatches) -> Result<Option<String>, String> {
                 })
                 .map(|password| {
                     // Trim the linefeed from the end.
-                    if password.ends_with("\n") {
+                    if password.ends_with('\n') {
                         password[0..password.len() - 1].to_string()
                     } else {
                         password

lcli/src/refund_deposit_contract.rs

@@ -110,7 +110,7 @@ pub fn run<T: EthSpec>(mut env: Environment<T>, matches: &ArgMatches) -> Result<
 
     env.runtime()
         .block_on(future)
-        .map_err(|()| format!("Failed to send transaction"))?;
+        .map_err(|()| "Failed to send transaction".to_string())?;
 
     Ok(())
 }

lcli/src/transition_blocks.rs

@@ -34,8 +34,8 @@ pub fn run_transition_blocks<T: EthSpec>(matches: &ArgMatches) -> Result<(), Str
 
     let post_state = do_transition(pre_state, block)?;
 
-    let mut output_file = File::create(output_path.clone())
+    let mut output_file =
-        .map_err(|e| format!("Unable to create output file: {:?}", e))?;
+        File::create(output_path).map_err(|e| format!("Unable to create output file: {:?}", e))?;
 
     output_file
         .write_all(&post_state.as_ssz_bytes())

tests/beacon_chain_sim/src/main.rs

@@ -78,7 +78,7 @@ fn async_sim(
 
     let spec = &mut env.eth2_config.spec;
 
-    spec.milliseconds_per_slot = spec.milliseconds_per_slot / speed_up_factor;
+    spec.milliseconds_per_slot /= speed_up_factor;
     spec.eth1_follow_distance = 16;
     spec.seconds_per_day = eth1_block_time.as_secs() * spec.eth1_follow_distance * 2;
     spec.min_genesis_time = 0;

validator_client/src/attestation_service.rs

@@ -194,8 +194,9 @@ impl<T: SlotClock + 'static, E: EthSpec> AttestationService<T, E> {
             .into_iter()
             .for_each(|duty| {
                 if let Some(committee_index) = duty.attestation_committee_index {
-                    let validator_duties =
+                    let validator_duties = committee_indices
-                        committee_indices.entry(committee_index).or_insert(vec![]);
+                        .entry(committee_index)
+                        .or_insert_with(|| vec![]);
 
                     validator_duties.push(duty);
                 }

validator_client/src/duties_service.rs

@@ -443,7 +443,7 @@ impl<T: SlotClock + 'static, E: EthSpec> DutiesService<T, E> {
     /// Attempt to download the duties of all managed validators for the given `epoch`.
     fn update_epoch(self, epoch: Epoch) -> impl Future<Item = (), Error = String> {
         let service_1 = self.clone();
-        let service_2 = self.clone();
+        let service_2 = self;
 
         let pubkeys = service_1.validator_store.voting_pubkeys();
         service_1

validator_client/src/validator_directory.rs

@@ -384,12 +384,11 @@ mod tests {
             "withdrawal keypair should be as expected"
         );
         assert!(
-            created_dir
+            !created_dir
                 .deposit_data
                 .clone()
                 .expect("should have data")
-                .len()
+                .is_empty(),
-                > 0,
             "should have some deposit data"
         );