Fix new clippy lints in clippy nightly (#3176)

zebra-chain/src/block.rs

@@ -132,24 +132,21 @@ impl Block {
     pub fn sprout_nullifiers(&self) -> impl Iterator<Item = &sprout::Nullifier> {
         self.transactions
             .iter()
-            .map(|transaction| transaction.sprout_nullifiers())
-            .flatten()
+            .flat_map(|transaction| transaction.sprout_nullifiers())
     }
 
     /// Access the [`sapling::Nullifier`]s from all transactions in this block.
     pub fn sapling_nullifiers(&self) -> impl Iterator<Item = &sapling::Nullifier> {
         self.transactions
             .iter()
-            .map(|transaction| transaction.sapling_nullifiers())
-            .flatten()
+            .flat_map(|transaction| transaction.sapling_nullifiers())
     }
 
     /// Access the [`orchard::Nullifier`]s from all transactions in this block.
     pub fn orchard_nullifiers(&self) -> impl Iterator<Item = &orchard::Nullifier> {
         self.transactions
             .iter()
-            .map(|transaction| transaction.orchard_nullifiers())
-            .flatten()
+            .flat_map(|transaction| transaction.orchard_nullifiers())
     }
 
     /// Count how many Sapling transactions exist in a block,

zebra-chain/src/block/merkle.rs

@@ -184,7 +184,7 @@ where
             .map(|tx| {
                 tx.as_ref()
                     .auth_digest()
-                    .unwrap_or_else(|| transaction::AuthDigest([0xFF; 32]))
+                    .unwrap_or(transaction::AuthDigest([0xFF; 32]))
             })
             .collect()
     }

zebra-chain/src/primitives/redpallas/scalar_mul.rs

@@ -92,14 +92,13 @@ impl NonAdjacentForm for pallas::Scalar {
             // Construct a buffer of bits of the scalar, starting at bit `pos`
             let u64_idx = pos / 64;
             let bit_idx = pos % 64;
-            let bit_buf: u64;
-            if bit_idx < 64 - w {
+            let bit_buf: u64 = if bit_idx < 64 - w {
                 // This window's bits are contained in a single u64
-                bit_buf = x_u64[u64_idx] >> bit_idx;
+                x_u64[u64_idx] >> bit_idx
             } else {
                 // Combine the current u64's bits with the bits from the next u64
-                bit_buf = (x_u64[u64_idx] >> bit_idx) | (x_u64[1 + u64_idx] << (64 - bit_idx));
-            }
+                (x_u64[u64_idx] >> bit_idx) | (x_u64[1 + u64_idx] << (64 - bit_idx))
+            };
 
             // Add the carry into the current window
             let window = carry + (bit_buf & window_mask);

zebra-chain/src/sapling/commitment.rs

@@ -116,12 +116,12 @@ impl NoteCommitment {
         //
         // The `TryFrom<Diversifier>` impls for the `jubjub::*Point`s handles
         // calling `DiversifyHash` implicitly.
-        let g_d_bytes: [u8; 32];
-        if let Ok(g_d) = jubjub::AffinePoint::try_from(diversifier) {
-            g_d_bytes = g_d.to_bytes();
+
+        let g_d_bytes: [u8; 32] = if let Ok(g_d) = jubjub::AffinePoint::try_from(diversifier) {
+            g_d.to_bytes()
         } else {
             return None;
-        }
+        };
 
         let pk_d_bytes = <[u8; 32]>::from(transmission_key);
         let v_bytes = value.to_bytes();

zebra-chain/src/transaction.rs

@@ -871,8 +871,7 @@ impl Transaction {
     pub fn orchard_actions(&self) -> impl Iterator<Item = &orchard::Action> {
         self.orchard_shielded_data()
             .into_iter()
-            .map(orchard::ShieldedData::actions)
-            .flatten()
+            .flat_map(orchard::ShieldedData::actions)
     }
 
     /// Access the [`orchard::Nullifier`]s in this transaction, if there are any,
@@ -880,8 +879,7 @@ impl Transaction {
     pub fn orchard_nullifiers(&self) -> impl Iterator<Item = &orchard::Nullifier> {
         self.orchard_shielded_data()
             .into_iter()
-            .map(orchard::ShieldedData::nullifiers)
-            .flatten()
+            .flat_map(orchard::ShieldedData::nullifiers)
     }
 
     /// Access the note commitments in this transaction, if there are any,
@@ -889,8 +887,7 @@ impl Transaction {
     pub fn orchard_note_commitments(&self) -> impl Iterator<Item = &pallas::Base> {
         self.orchard_shielded_data()
             .into_iter()
-            .map(orchard::ShieldedData::note_commitments)
-            .flatten()
+            .flat_map(orchard::ShieldedData::note_commitments)
     }
 
     /// Access the [`orchard::Flags`] in this transaction, if there is any,

zebra-chain/src/transaction/arbitrary.rs

@@ -847,8 +847,7 @@ pub fn transaction_to_fake_v5(
             expiry_height: height,
             sapling_shielded_data: sapling_shielded_data
                 .clone()
-                .map(sapling_shielded_v4_to_fake_v5)
-                .flatten(),
+                .and_then(sapling_shielded_v4_to_fake_v5),
             orchard_shielded_data: None,
         },
         v5 @ V5 { .. } => v5.clone(),

zebra-chain/src/transaction/memo.rs

@@ -34,15 +34,13 @@ impl<'a> TryFrom<&'a [u8]> for Memo {
 
 impl fmt::Debug for Memo {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let output: String;
-
         // This saves work but if the 'valid utf8 string' is just a
         // bunch of numbers, it prints them out like
         // 'Memo("\u{0}\u{0}..")', so. ¯\_(ツ)_/¯
-        match std::str::from_utf8(&self.0[..]) {
-            Ok(memo) => output = String::from(memo),
-            _ => output = hex::encode(&self.0[..]),
-        }
+        let output: String = match std::str::from_utf8(&self.0[..]) {
+            Ok(memo) => String::from(memo),
+            _ => hex::encode(&self.0[..]),
+        };
 
         f.debug_tuple("Memo").field(&output).finish()
     }

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

@@ -7,7 +7,7 @@ fn parse_coinbase_height_mins() {
     // examples with height 1:
 
     let case1 = vec![0x51];
-    assert!(!parse_coinbase_height(case1.clone()).is_err());
+    assert!(parse_coinbase_height(case1.clone()).is_ok());
     assert_eq!(parse_coinbase_height(case1).unwrap().0 .0, 1);
 
     let case2 = vec![0x01, 0x01];
@@ -25,7 +25,7 @@ fn parse_coinbase_height_mins() {
     // examples with height 17:
 
     let case1 = vec![0x01, 0x11];
-    assert!(!parse_coinbase_height(case1.clone()).is_err());
+    assert!(parse_coinbase_height(case1.clone()).is_ok());
     assert_eq!(parse_coinbase_height(case1).unwrap().0 .0, 17);
 
     let case2 = vec![0x02, 0x11, 0x00];

zebra-network/src/meta_addr/tests/prop.rs

@@ -344,9 +344,7 @@ proptest! {
 
                     // If `change` is invalid for the current MetaAddr state, skip it.
                     // If we've run out of changes for this addr, do nothing.
-                    if let Some(changed_addr) = change
-                        .map(|change| change.apply_to_meta_addr(*addr))
-                        .flatten()
+                    if let Some(changed_addr) = change.and_then(|change| change.apply_to_meta_addr(*addr))
                     {
                         prop_assert_eq!(changed_addr.addr, addr.addr);
                         *addr = changed_addr;

zebra-state/src/config.rs

@@ -157,9 +157,8 @@ impl Config {
         }
 
         // Try the hard limit or the minimum, whichever is greater
-        let min_limit = if let Some(hard_limit) =
-            hard_rlimit.map(TryInto::try_into).map(Result::ok).flatten()
-        {
+        let min_limit =
+            if let Some(hard_limit) = hard_rlimit.map(TryInto::try_into).and_then(Result::ok) {
                 std::cmp::max(Config::MIN_OPEN_FILE_LIMIT, hard_limit)
             } else {
                 Config::MIN_OPEN_FILE_LIMIT

zebra-state/src/service.rs

@@ -473,7 +473,7 @@ impl StateService {
             (max_height - 1).expect("max_len is at least 1")
         };
 
-        let stop_height = stop.map(|hash| self.best_height_by_hash(hash)).flatten();
+        let stop_height = stop.and_then(|hash| self.best_height_by_hash(hash));
 
         // Compute the final height, making sure it is:
         //   * at or below our chain tip, and

zebra-state/src/service/finalized_state.rs

@@ -542,8 +542,7 @@ impl FinalizedState {
         let (finalized, rsp_tx) = queued_block;
         let result = self.commit_finalized_direct(finalized.clone(), "CommitFinalized request");
 
-        let block_result;
-        if result.is_ok() {
+        let block_result = if result.is_ok() {
             metrics::counter!("state.checkpoint.finalized.block.count", 1);
             metrics::gauge!(
                 "state.checkpoint.finalized.block.height",
@@ -556,7 +555,7 @@ impl FinalizedState {
             metrics::gauge!("zcash.chain.verified.block.height", finalized.height.0 as _);
             metrics::counter!("zcash.chain.verified.block.total", 1);
 
-            block_result = Ok(finalized);
+            Ok(finalized)
         } else {
             metrics::counter!("state.checkpoint.error.block.count", 1);
             metrics::gauge!(
@@ -564,8 +563,8 @@ impl FinalizedState {
                 finalized.height.0 as _
             );
 
-            block_result = Err(());
-        }
+            Err(())
+        };
 
         let _ = rsp_tx.send(result.map_err(Into::into));