fix(clippy): resolve or disable new nightly clippy lints (#4739)

* Fix new dead_code lints in generated pin-project code

* Fix and ignore new needless_borrow lints

tower-fallback/src/future.rs

@@ -1,5 +1,8 @@
 //! Future types for the `Fallback` middleware.
 
+// TODO: remove this lint exception after upgrading to pin-project 1.0.11 or later (#2355)
+#![allow(dead_code)]
+
 use std::{
     fmt::Debug,
     future::Future,

zebra-chain/src/amount/tests/vectors.rs

@@ -167,6 +167,8 @@ fn add_with_diff_constraints() -> Result<()> {
 }
 
 #[test]
+// The borrows are actually needed to call the correct trait impl
+#[allow(clippy::needless_borrow)]
 fn deserialize_checks_bounds() -> Result<()> {
     zebra_test::init();
 

zebra-chain/src/block.rs

@@ -1,5 +1,21 @@
 //! Blocks and block-related structures (heights, headers, etc.)
 
+use std::{collections::HashMap, fmt, ops::Neg};
+
+use crate::{
+    amount::NegativeAllowed,
+    block::merkle::AuthDataRoot,
+    fmt::DisplayToDebug,
+    orchard,
+    parameters::{Network, NetworkUpgrade},
+    sapling,
+    serialization::{TrustedPreallocate, MAX_PROTOCOL_MESSAGE_LEN},
+    sprout,
+    transaction::Transaction,
+    transparent,
+    value_balance::{ValueBalance, ValueBalanceError},
+};
+
 mod commitment;
 mod error;
 mod hash;
@@ -14,8 +30,6 @@ pub mod arbitrary;
 #[cfg(any(test, feature = "bench", feature = "proptest-impl"))]
 pub mod tests;
 
-use std::{collections::HashMap, fmt, ops::Neg};
-
 pub use commitment::{
     ChainHistoryBlockTxAuthCommitmentHash, ChainHistoryMmrRootHash, Commitment, CommitmentError,
 };
@@ -27,20 +41,6 @@ pub use serialize::{SerializedBlock, MAX_BLOCK_BYTES};
 #[cfg(any(test, feature = "proptest-impl"))]
 pub use arbitrary::LedgerState;
 
-use crate::{
-    amount::NegativeAllowed,
-    block::merkle::AuthDataRoot,
-    fmt::DisplayToDebug,
-    orchard,
-    parameters::{Network, NetworkUpgrade},
-    sapling,
-    serialization::{TrustedPreallocate, MAX_PROTOCOL_MESSAGE_LEN},
-    sprout,
-    transaction::Transaction,
-    transparent,
-    value_balance::{ValueBalance, ValueBalanceError},
-};
-
 /// A Zcash block, containing a header and a list of transactions.
 #[derive(Clone, Debug, Eq, PartialEq)]
 #[cfg_attr(any(test, feature = "proptest-impl"), derive(Serialize))]
@@ -219,7 +219,7 @@ impl Block {
 
 impl<'a> From<&'a Block> for Hash {
     fn from(block: &'a Block) -> Hash {
-        (&block.header).into()
+        block.header.into()
     }
 }
 

zebra-chain/src/block/hash.rs

@@ -97,6 +97,14 @@ impl<'a> From<&'a Header> for Hash {
     }
 }
 
+impl From<Header> for Hash {
+    // The borrow is actually needed to use From<&Header>
+    #[allow(clippy::needless_borrow)]
+    fn from(block_header: Header) -> Self {
+        (&block_header).into()
+    }
+}
+
 impl ZcashSerialize for Hash {
     fn zcash_serialize<W: io::Write>(&self, mut writer: W) -> Result<(), io::Error> {
         writer.write_all(&self.0)?;

zebra-chain/src/parameters/network.rs

@@ -56,18 +56,18 @@ pub enum Network {
     Testnet,
 }
 
-impl From<&Network> for &'static str {
-    fn from(network: &Network) -> &'static str {
+impl From<Network> for &'static str {
+    fn from(network: Network) -> &'static str {
         match network {
             Network::Mainnet => "Mainnet",
             Network::Testnet => "Testnet",
         }
     }
 }
 
-impl From<Network> for &'static str {
-    fn from(network: Network) -> &'static str {
-        (&network).into()
+impl From<&Network> for &'static str {
+    fn from(network: &Network) -> &'static str {
+        (*network).into()
     }
 }
 

zebra-chain/src/primitives/zcash_primitives.rs

@@ -198,6 +198,15 @@ impl From<&Script> for zcash_primitives::legacy::Script {
     }
 }
 
+/// Convert a Zebra Script into a librustzcash one.
+impl From<Script> for zcash_primitives::legacy::Script {
+    // The borrow is actually needed to use From<&Script>
+    #[allow(clippy::needless_borrow)]
+    fn from(script: Script) -> Self {
+        (&script).into()
+    }
+}
+
 /// Compute a signature hash using librustzcash.
 ///
 /// # Inputs
@@ -223,7 +232,7 @@ pub(crate) fn sighash(
     let signable_input = match input_index {
         Some(input_index) => {
             let output = all_previous_outputs[input_index].clone();
-            script = (&output.lock_script).into();
+            script = output.lock_script.into();
             zp_tx::sighash::SignableInput::Transparent {
                 hash_type: hash_type.bits() as _,
                 index: input_index,

zebra-chain/src/sprout/joinsplit.rs

@@ -1,3 +1,5 @@
+//! Sprout funds transfers using [`JoinSplit`]s.
+
 use std::io;
 
 use serde::{Deserialize, Serialize};
@@ -82,18 +84,25 @@ impl<P: ZkSnarkProof> ZcashSerialize for JoinSplit<P> {
     fn zcash_serialize<W: io::Write>(&self, mut writer: W) -> Result<(), io::Error> {
         self.vpub_old.zcash_serialize(&mut writer)?;
         self.vpub_new.zcash_serialize(&mut writer)?;
+
         writer.write_32_bytes(&self.anchor.into())?;
         writer.write_32_bytes(&self.nullifiers[0].into())?;
         writer.write_32_bytes(&self.nullifiers[1].into())?;
         writer.write_32_bytes(&self.commitments[0].into())?;
         writer.write_32_bytes(&self.commitments[1].into())?;
+
         writer.write_all(&self.ephemeral_key.as_bytes()[..])?;
+        // The borrow is actually needed to avoid taking ownership
+        #[allow(clippy::needless_borrow)]
         writer.write_32_bytes(&(&self.random_seed).into())?;
+
         self.vmacs[0].zcash_serialize(&mut writer)?;
         self.vmacs[1].zcash_serialize(&mut writer)?;
         self.zkproof.zcash_serialize(&mut writer)?;
+
         self.enc_ciphertexts[0].zcash_serialize(&mut writer)?;
         self.enc_ciphertexts[1].zcash_serialize(&mut writer)?;
+
         Ok(())
     }
 }

zebra-chain/src/transaction/arbitrary.rs

@@ -959,7 +959,7 @@ pub fn fake_v5_transactions_for_network<'b>(
             .transactions
             .into_iter()
             .map(move |transaction| {
-                transaction_to_fake_v5(&*transaction, network, block::Height(*height))
+                transaction_to_fake_v5(&transaction, network, block::Height(*height))
             })
             .map(Transaction::from)
     })

zebra-chain/src/transaction/tests/vectors.rs

@@ -1,4 +1,4 @@
-use std::convert::{TryFrom, TryInto};
+//! Fixed test vectors for transactions.
 
 use chrono::{DateTime, NaiveDateTime, Utc};
 use color_eyre::eyre::Result;
@@ -275,7 +275,7 @@ fn deserialize_large_transaction() {
 fn empty_v5_round_trip() {
     zebra_test::init();
 
-    let tx: &Transaction = &*EMPTY_V5_TX;
+    let tx: &Transaction = &EMPTY_V5_TX;
 
     let data = tx.zcash_serialize_to_vec().expect("tx should serialize");
     let tx2: &Transaction = &data
@@ -327,7 +327,7 @@ fn empty_v4_round_trip() {
 fn empty_v5_librustzcash_round_trip() {
     zebra_test::init();
 
-    let tx: &Transaction = &*EMPTY_V5_TX;
+    let tx: &Transaction = &EMPTY_V5_TX;
     let _alt_tx: zcash_primitives::transaction::Transaction = tx.try_into().expect(
         "librustzcash deserialization might work for empty zebra serialized transactions. \
         Hint: if empty transactions fail, but other transactions work, delete this test",
@@ -572,6 +572,8 @@ fn zip244_round_trip() -> Result<()> {
         let reencoded = transaction.zcash_serialize_to_vec()?;
         assert_eq!(test.tx, reencoded);
 
+        // The borrow is actually needed to call the correct trait impl
+        #[allow(clippy::needless_borrow)]
         let _alt_tx: zcash_primitives::transaction::Transaction = (&transaction)
             .try_into()
             .expect("librustzcash deserialization must work for zebra serialized transactions");

zebra-chain/src/transaction/unmined.rs

@@ -221,6 +221,8 @@ impl From<Transaction> for UnminedTx {
             "unexpected serialization failure: all structurally valid transactions have a size",
         );
 
+        // The borrow is actually needed to avoid taking ownership
+        #[allow(clippy::needless_borrow)]
         Self {
             id: (&transaction).into(),
             size,

zebra-consensus/src/primitives/groth16.rs

@@ -251,6 +251,9 @@ impl Description for (&JoinSplit<Groth16Proof>, &ed25519::VerificationKeyBytes)
     /// This is not yet officially documented; see the reference implementation:
     /// <https://github.com/zcash/librustzcash/blob/0ec7f97c976d55e1a194a37b27f247e8887fca1d/zcash_proofs/src/sprout.rs#L152-L166>
     /// <https://zips.z.cash/protocol/protocol.pdf#joinsplitdesc>
+    //
+    // The borrows are actually needed to avoid taking ownership
+    #[allow(clippy::needless_borrow)]
     fn primary_inputs(&self) -> Vec<jubjub::Fq> {
         let (joinsplit, joinsplit_pub_key) = self;