clippy: Replaces .get(0) with .first() (solana-labs#34048)

accounts-db/src/accounts_db.rs

@@ -10937,7 +10937,7 @@ pub mod tests {
                 expected[0].push(raw_expected[index]);
             }
             let mut result2 = (0..range).map(|_| Vec::default()).collect::<Vec<_>>();
-            if let Some(m) = result.get(0) {
+            if let Some(m) = result.first() {
                 m.load_all(&mut result2, bin, &PubkeyBinCalculator24::new(bins));
             } else {
                 result2 = vec![];

banks-server/src/banks_server.rs

@@ -217,7 +217,7 @@ impl Banks for BanksServer {
             .root_bank()
             .get_blockhash_last_valid_block_height(blockhash)
             .unwrap();
-        let signature = transaction.signatures.get(0).cloned().unwrap_or_default();
+        let signature = transaction.signatures.first().cloned().unwrap_or_default();
         let info = TransactionInfo::new(
             signature,
             serialize(&transaction).unwrap(),

cli/src/program.rs

@@ -2104,7 +2104,7 @@ fn check_payer(
     }
     if !write_messages.is_empty() {
         // Assume all write messages cost the same
-        if let Some(message) = write_messages.get(0) {
+        if let Some(message) = write_messages.first() {
             fee += rpc_client.get_fee_for_message(message)? * (write_messages.len() as u64);
         }
     }

cli/src/program_v4.rs

@@ -795,7 +795,7 @@ fn check_payer(
     }
     if !write_messages.is_empty() {
         // Assume all write messages cost the same
-        if let Some(message) = write_messages.get(0) {
+        if let Some(message) = write_messages.first() {
             fee += rpc_client.get_fee_for_message(message)? * (write_messages.len() as u64);
         }
     }

cli/src/stake.rs

@@ -2603,8 +2603,8 @@ pub fn process_delegate_stake(
         // filter should return at most one result
         let rpc_vote_account =
             current
-                .get(0)
-                .or_else(|| delinquent.get(0))
+                .first()
+                .or_else(|| delinquent.first())
                 .ok_or(CliError::RpcRequestError(format!(
                     "Vote account not found: {vote_account_pubkey}"
                 )))?;

core/src/banking_stage/consumer.rs

@@ -1264,7 +1264,7 @@ mod tests {
             let commit_transactions_result = commit_transactions_result.unwrap();
             assert_eq!(commit_transactions_result.len(), 2);
             assert_matches!(
-                commit_transactions_result.get(0),
+                commit_transactions_result.first(),
                 Some(CommitTransactionDetails::Committed { .. })
             );
             assert_matches!(
@@ -1274,7 +1274,7 @@ mod tests {
             assert_eq!(retryable_transaction_indexes, vec![1]);
 
             let expected_block_cost = if !apply_cost_tracker_during_replay_enabled {
-                let actual_bpf_execution_cost = match commit_transactions_result.get(0).unwrap() {
+                let actual_bpf_execution_cost = match commit_transactions_result.first().unwrap() {
                     CommitTransactionDetails::Committed { compute_units } => *compute_units,
                     CommitTransactionDetails::NotCommitted => {
                         unreachable!()

core/src/banking_stage/latest_unprocessed_votes.rs

@@ -64,7 +64,7 @@ impl LatestValidatorVotePacket {
                 let &pubkey = message
                     .message
                     .static_account_keys()
-                    .get(0)
+                    .first()
                     .ok_or(DeserializedPacketError::VoteTransactionError)?;
                 let slot = vote_state_update_instruction.last_voted_slot().unwrap_or(0);
                 let timestamp = vote_state_update_instruction.timestamp();

core/src/consensus/tower_storage.rs

@@ -317,7 +317,7 @@ impl TowerStorage for EtcdTowerStorage {
 
         for op_response in response.op_responses() {
             if let etcd_client::TxnOpResponse::Get(get_response) = op_response {
-                if let Some(kv) = get_response.kvs().get(0) {
+                if let Some(kv) = get_response.kvs().first() {
                     return bincode::deserialize_from(kv.value())
                         .map_err(|e| e.into())
                         .and_then(|t: SavedTowerVersions| t.try_into_tower(node_pubkey));

ledger/src/blockstore/blockstore_purge.rs

@@ -401,7 +401,7 @@ impl Blockstore {
                 .into_iter()
                 .flat_map(|entry| entry.transactions);
             for (i, transaction) in transactions.enumerate() {
-                if let Some(&signature) = transaction.signatures.get(0) {
+                if let Some(&signature) = transaction.signatures.first() {
                     batch.delete::<cf::TransactionStatus>((signature, slot))?;
                     batch.delete::<cf::TransactionMemos>((signature, slot))?;
                     if !primary_indexes.is_empty() {

program-runtime/src/invoke_context.rs

@@ -984,7 +984,7 @@ mod tests {
             (solana_sdk::pubkey::new_rand(), loader_account),
         ];
         let metas = vec![
-            AccountMeta::new(transaction_accounts.get(0).unwrap().0, false),
+            AccountMeta::new(transaction_accounts.first().unwrap().0, false),
             AccountMeta::new(transaction_accounts.get(1).unwrap().0, false),
             AccountMeta::new_readonly(transaction_accounts.get(2).unwrap().0, false),
         ];

program-runtime/src/loaded_programs.rs

@@ -1382,7 +1382,7 @@ mod tests {
             .get(&program1)
             .expect("Failed to find the entry");
         assert_eq!(second_level.len(), 1);
-        assert!(second_level.get(0).unwrap().is_tombstone());
+        assert!(second_level.first().unwrap().is_tombstone());
         assert_eq!(tombstone.deployment_slot, 10);
         assert_eq!(tombstone.effective_slot, 10);
 
@@ -1398,7 +1398,7 @@ mod tests {
             .get(&program2)
             .expect("Failed to find the entry");
         assert_eq!(second_level.len(), 1);
-        assert!(!second_level.get(0).unwrap().is_tombstone());
+        assert!(!second_level.first().unwrap().is_tombstone());
 
         let tombstone = set_tombstone(
             &mut cache,
@@ -1411,7 +1411,7 @@ mod tests {
             .get(&program2)
             .expect("Failed to find the entry");
         assert_eq!(second_level.len(), 2);
-        assert!(!second_level.get(0).unwrap().is_tombstone());
+        assert!(!second_level.first().unwrap().is_tombstone());
         assert!(second_level.get(1).unwrap().is_tombstone());
         assert!(tombstone.is_tombstone());
         assert_eq!(tombstone.deployment_slot, 60);

programs/bpf_loader/src/lib.rs

@@ -2687,7 +2687,7 @@ mod tests {
             &elf_orig,
             &elf_new,
         );
-        *instruction_accounts.get_mut(3).unwrap() = instruction_accounts.get(0).unwrap().clone();
+        *instruction_accounts.get_mut(3).unwrap() = instruction_accounts.first().unwrap().clone();
         process_instruction(
             transaction_accounts,
             instruction_accounts,

programs/bpf_loader/src/syscalls/mod.rs

@@ -1644,7 +1644,7 @@ declare_builtin_function!(
             invoke_context.get_check_aligned(),
             invoke_context.get_check_size(),
         )?
-        .get(0)
+        .first()
         .ok_or(SyscallError::InvalidLength)?;
 
         if params.base_len > 512 || params.exponent_len > 512 || params.modulus_len > 512 {

remote-wallet/src/locator.rs

@@ -124,7 +124,7 @@ impl Locator {
         let host = uri.host().map(|h| h.to_string());
         match (scheme, host) {
             (Some(scheme), Some(host)) if scheme == "usb" => {
-                let path = uri.path().segments().get(0).and_then(|s| {
+                let path = uri.path().segments().first().and_then(|s| {
                     if !s.is_empty() {
                         Some(s.as_str())
                     } else {

rpc-test/tests/nonblocking.rs

@@ -40,7 +40,7 @@ async fn test_tpu_send_transaction() {
             .get_signature_statuses(&signatures)
             .await
             .unwrap();
-        if statuses.value.get(0).is_some() {
+        if statuses.value.first().is_some() {
             break;
         }
     }

rpc-test/tests/rpc.rs

@@ -496,7 +496,7 @@ fn run_tpu_send_transaction(tpu_use_quic: bool) {
     loop {
         assert!(now.elapsed() < timeout);
         let statuses = rpc_client.get_signature_statuses(&signatures).unwrap();
-        if statuses.value.get(0).is_some() {
+        if statuses.value.first().is_some() {
             return;
         }
     }

runtime/src/bank.rs

@@ -6384,7 +6384,7 @@ impl Bank {
     pub fn process_transaction(&self, tx: &Transaction) -> Result<()> {
         self.try_process_transactions(std::iter::once(tx))?[0].clone()?;
         tx.signatures
-            .get(0)
+            .first()
             .map_or(Ok(()), |sig| self.get_signature_status(sig).unwrap())
     }
 

runtime/src/bank_client.rs

@@ -44,7 +44,7 @@ impl AsyncClient for BankClient {
         &self,
         transaction: VersionedTransaction,
     ) -> Result<Signature> {
-        let signature = transaction.signatures.get(0).cloned().unwrap_or_default();
+        let signature = transaction.signatures.first().cloned().unwrap_or_default();
         let transaction_sender = self.transaction_sender.lock().unwrap();
         transaction_sender.send(transaction).unwrap();
         Ok(signature)
@@ -60,7 +60,7 @@ impl SyncClient for BankClient {
         let blockhash = self.bank.last_blockhash();
         let transaction = Transaction::new(keypairs, message, blockhash);
         self.bank.process_transaction(&transaction)?;
-        Ok(transaction.signatures.get(0).cloned().unwrap_or_default())
+        Ok(transaction.signatures.first().cloned().unwrap_or_default())
     }
 
     /// Create and process a transaction from a single instruction.

sdk/cargo-build-bpf/src/main.rs

@@ -16,7 +16,7 @@ fn main() {
             s.replace("--bpf", "--sbf")
         })
         .collect::<Vec<_>>();
-    let program = if let Some(arg0) = args.get(0) {
+    let program = if let Some(arg0) = args.first() {
         let arg0 = arg0.replace("build-bpf", "build-sbf");
         args.remove(0);
         PathBuf::from(arg0)
@@ -25,7 +25,7 @@ fn main() {
     };
     // When run as a cargo subcommand, the first program argument is the subcommand name.
     // Remove it
-    if let Some(arg0) = args.get(0) {
+    if let Some(arg0) = args.first() {
         if arg0 == "build-bpf" {
             args.remove(0);
         }

sdk/cargo-test-bpf/src/main.rs

@@ -16,7 +16,7 @@ fn main() {
         let cargo_build_sbf = cargo_build_bpf.replace("build-bpf", "build-sbf");
         env::set_var("CARGO_BUILD_SBF", cargo_build_sbf);
     }
-    let program = if let Some(arg0) = args.get(0) {
+    let program = if let Some(arg0) = args.first() {
         let cargo_test_sbf = arg0.replace("test-bpf", "test-sbf");
         let cargo_build_sbf = cargo_test_sbf.replace("test-sbf", "build-sbf");
         env::set_var("CARGO_BUILD_SBF", cargo_build_sbf);
@@ -27,7 +27,7 @@ fn main() {
     };
     // When run as a cargo subcommand, the first program argument is the subcommand name.
     // Remove it
-    if let Some(arg0) = args.get(0) {
+    if let Some(arg0) = args.first() {
         if arg0 == "test-bpf" {
             args.remove(0);
         }

turbine/src/broadcast_stage/standard_broadcast_run.rs

@@ -580,7 +580,7 @@ mod test {
         // Slot 2 interrupted slot 1
         let shreds = run.finish_prev_slot(&keypair, 0, &mut ProcessShredsStats::default());
         let shred = shreds
-            .get(0)
+            .first()
             .expect("Expected a shred that signals an interrupt");
 
         // Validate the shred

validator/src/main.rs

@@ -244,7 +244,7 @@ fn wait_for_restart_window(
                     Err("Current epoch is almost complete".to_string())
                 } else {
                     while leader_schedule
-                        .get(0)
+                        .front()
                         .map(|slot| *slot < epoch_info.absolute_slot)
                         .unwrap_or(false)
                     {
@@ -258,7 +258,7 @@ fn wait_for_restart_window(
                         upcoming_idle_windows.pop();
                     }
 
-                    match leader_schedule.get(0) {
+                    match leader_schedule.front() {
                         None => {
                             Ok(()) // Validator has no leader slots
                         }

vote/src/vote_parser.rs

@@ -23,7 +23,7 @@ pub fn parse_sanitized_vote_transaction(tx: &SanitizedTransaction) -> Option<Par
     let first_account = usize::from(*first_instruction.accounts.first()?);
     let key = message.account_keys().get(first_account)?;
     let (vote, switch_proof_hash) = parse_vote_instruction_data(&first_instruction.data)?;
-    let signature = tx.signatures().get(0).cloned().unwrap_or_default();
+    let signature = tx.signatures().first().cloned().unwrap_or_default();
     Some((*key, vote, switch_proof_hash, signature))
 }
 
@@ -40,7 +40,7 @@ pub fn parse_vote_transaction(tx: &Transaction) -> Option<ParsedVote> {
     let first_account = usize::from(*first_instruction.accounts.first()?);
     let key = message.account_keys.get(first_account)?;
     let (vote, switch_proof_hash) = parse_vote_instruction_data(&first_instruction.data)?;
-    let signature = tx.signatures.get(0).cloned().unwrap_or_default();
+    let signature = tx.signatures.first().cloned().unwrap_or_default();
     Some((*key, vote, switch_proof_hash, signature))
 }
 

zk-token-sdk/src/instruction/batched_grouped_ciphertext_validity.rs

@@ -116,10 +116,10 @@ impl ZkProofData<BatchedGroupedCiphertext2HandlesValidityProofContext>
         let grouped_ciphertext_hi: GroupedElGamalCiphertext<2> =
             self.context.grouped_ciphertext_hi.try_into()?;
 
-        let destination_handle_lo = grouped_ciphertext_lo.handles.get(0).unwrap();
+        let destination_handle_lo = grouped_ciphertext_lo.handles.first().unwrap();
         let auditor_handle_lo = grouped_ciphertext_lo.handles.get(1).unwrap();
 
-        let destination_handle_hi = grouped_ciphertext_hi.handles.get(0).unwrap();
+        let destination_handle_hi = grouped_ciphertext_hi.handles.first().unwrap();
         let auditor_handle_hi = grouped_ciphertext_hi.handles.get(1).unwrap();
 
         let proof: BatchedGroupedCiphertext2HandlesValidityProof = self.proof.try_into()?;

zk-token-sdk/src/instruction/grouped_ciphertext_validity.rs

@@ -105,7 +105,7 @@ impl ZkProofData<GroupedCiphertext2HandlesValidityProofContext>
         let grouped_ciphertext: GroupedElGamalCiphertext<2> =
             self.context.grouped_ciphertext.try_into()?;
 
-        let destination_handle = grouped_ciphertext.handles.get(0).unwrap();
+        let destination_handle = grouped_ciphertext.handles.first().unwrap();
         let auditor_handle = grouped_ciphertext.handles.get(1).unwrap();
 
         let proof: GroupedCiphertext2HandlesValidityProof = self.proof.try_into()?;

zk-token-sdk/src/instruction/transfer/encryption.rs

@@ -35,7 +35,7 @@ impl TransferAmountCiphertext {
     pub fn get_source_handle(&self) -> &DecryptHandle {
         // `TransferAmountCiphertext` is a wrapper for `GroupedElGamalCiphertext<3>`, which
         // holds exactly three decryption handles.
-        self.0.handles.get(0).unwrap()
+        self.0.handles.first().unwrap()
     }
 
     pub fn get_destination_handle(&self) -> &DecryptHandle {
@@ -80,7 +80,7 @@ impl FeeEncryption {
     pub fn get_destination_handle(&self) -> &DecryptHandle {
         // `FeeEncryption` is a wrapper for `GroupedElGamalCiphertext<2>`, which holds
         // exactly two decryption handles.
-        self.0.handles.get(0).unwrap()
+        self.0.handles.first().unwrap()
     }
 
     pub fn get_withdraw_withheld_authority_handle(&self) -> &DecryptHandle {