Fix string to empty string comparison and len zero warnings

stackslib/src/burnchains/affirmation.rs

@@ -378,6 +378,10 @@ impl AffirmationMap {
         self.affirmations.len()
     }
 
+    pub fn is_empty(&self) -> bool {
+        self.affirmations.is_empty()
+    }
+
     pub fn as_slice(&self) -> &[AffirmationMapEntry] {
         &self.affirmations
     }
@@ -876,7 +880,7 @@ fn inner_find_heaviest_block_commit_ptr(
     test_debug!("ancestors = {:?}", &ancestors);
     test_debug!("ancestor_confirmations = {:?}", &ancestor_confirmations);
 
-    if ancestor_confirmations.len() == 0 {
+    if ancestor_confirmations.is_empty() {
         // empty prepare phase
         test_debug!("Prepare-phase has no block-commits");
         return None;

stackslib/src/burnchains/bitcoin/address.rs

@@ -317,7 +317,7 @@ impl SegwitBitcoinAddress {
             None
         }?;
 
-        if quintets.len() == 0 || quintets.len() > 65 {
+        if quintets.is_empty() || quintets.len() > 65 {
             test_debug!("Invalid prog length: {}", quintets.len());
             return None;
         }

stackslib/src/burnchains/bitcoin/bits.rs

@@ -93,7 +93,7 @@ impl BitcoinTxInputStructured {
         segwit: bool,
         input_txid: (Txid, u32),
     ) -> Option<BitcoinTxInputStructured> {
-        if num_sigs < 1 || pubkey_pushbytes.len() < 1 || pubkey_pushbytes.len() < num_sigs {
+        if num_sigs < 1 || pubkey_pushbytes.is_empty() || pubkey_pushbytes.len() < num_sigs {
             test_debug!(
                 "Not a multisig script: num_sigs = {}, num_pubkeys <= {}",
                 num_sigs,
@@ -153,7 +153,7 @@ impl BitcoinTxInputStructured {
         pubkey_vecs: &[Vec<u8>],
         input_txid: (Txid, u32),
     ) -> Option<BitcoinTxInputStructured> {
-        if num_sigs < 1 || pubkey_vecs.len() < 1 || pubkey_vecs.len() < num_sigs {
+        if num_sigs < 1 || pubkey_vecs.is_empty() || pubkey_vecs.len() < num_sigs {
             test_debug!(
                 "Not a multisig script: num_sigs = {}, num_pubkeys <= {}",
                 num_sigs,

stackslib/src/burnchains/bitcoin/blocks.rs

@@ -381,7 +381,7 @@ impl BitcoinBlockParser {
         tx: &Transaction,
         epoch_id: StacksEpochId,
     ) -> Option<Vec<BitcoinTxOutput>> {
-        if tx.output.len() == 0 {
+        if tx.output.is_empty() {
             return None;
         }
 

stackslib/src/burnchains/bitcoin/indexer.rs

@@ -705,7 +705,7 @@ impl BitcoinIndexer {
                     e
                 })?;
 
-            if reorg_headers.len() == 0 {
+            if reorg_headers.is_empty() {
                 // chain shrank considerably
                 info!(
                     "Missing Bitcoin headers in block range {}-{} -- did the Bitcoin chain shrink?",
@@ -736,7 +736,7 @@ impl BitcoinIndexer {
                 })?;
 
             assert!(
-                canonical_headers.len() > 0,
+                !canonical_headers.is_empty(),
                 "BUG: uninitialized canonical SPV headers DB"
             );
 
@@ -1379,7 +1379,7 @@ mod test {
                         spv_client
                             .insert_block_headers_before(start_block - 1, hdrs)
                             .unwrap();
-                    } else if hdrs.len() > 0 {
+                    } else if !hdrs.is_empty() {
                         test_debug!("insert at {}: {:?}", 0, &hdrs);
                         spv_client.test_write_block_headers(0, hdrs).unwrap();
                     }
@@ -1552,7 +1552,7 @@ mod test {
                         spv_client
                             .insert_block_headers_before(start_block - 1, hdrs)
                             .unwrap();
-                    } else if hdrs.len() > 0 {
+                    } else if !hdrs.is_empty() {
                         test_debug!("insert at {}: {:?}", 0, &hdrs);
                         spv_client.test_write_block_headers(0, hdrs).unwrap();
                     }

stackslib/src/burnchains/bitcoin/network.rs

@@ -355,7 +355,7 @@ impl BitcoinIndexer {
 
     /// Send a GetData message
     pub fn send_getdata(&mut self, block_hashes: &Vec<Sha256dHash>) -> Result<(), btc_error> {
-        assert!(block_hashes.len() > 0);
+        assert!(!block_hashes.is_empty());
         let getdata_invs = block_hashes
             .iter()
             .map(|h| btc_message_blockdata::Inventory {

stackslib/src/burnchains/bitcoin/spv.rs

@@ -529,7 +529,7 @@ impl SpvClient {
         headers: &Vec<LoneBlockHeader>,
         check_txcount: bool,
     ) -> Result<(), btc_error> {
-        if headers.len() == 0 {
+        if headers.is_empty() {
             return Ok(());
         }
 
@@ -945,7 +945,7 @@ impl SpvClient {
     ) -> Result<(), btc_error> {
         assert!(self.readwrite, "SPV header DB is open read-only");
 
-        if block_headers.len() == 0 {
+        if block_headers.is_empty() {
             // no-op
             return Ok(());
         }
@@ -996,7 +996,7 @@ impl SpvClient {
         block_headers: Vec<LoneBlockHeader>,
     ) -> Result<(), btc_error> {
         assert!(self.readwrite, "SPV header DB is open read-only");
-        if block_headers.len() == 0 {
+        if block_headers.is_empty() {
             // no-op
             return Ok(());
         }
@@ -1137,7 +1137,7 @@ impl SpvClient {
         ]);
         let max_target_bits = BlockHeader::compact_target_from_u256(&max_target);
 
-        let parent_header = if headers_in_range.len() > 0 {
+        let parent_header = if !headers_in_range.is_empty() {
             headers_in_range[0]
         } else {
             match self.read_block_header(current_header_height - 1)? {

stackslib/src/burnchains/burnchain.rs

@@ -130,7 +130,7 @@ impl BurnchainStateTransition {
 
         block_total_burns.sort();
 
-        if block_total_burns.len() == 0 {
+        if block_total_burns.is_empty() {
             return Some(0);
         } else if block_total_burns.len() == 1 {
             return Some(block_total_burns[0]);

stackslib/src/burnchains/db.rs

@@ -452,7 +452,7 @@ impl<'a> BurnchainDBTransaction<'a> {
                 })
                 .collect()
         };
-        if commits.len() == 0 {
+        if commits.is_empty() {
             test_debug!("No block-commits for block {}", hdr.block_height);
             return Ok(());
         }

stackslib/src/burnchains/tests/burnchain.rs

@@ -574,7 +574,7 @@ fn test_process_block_ops() {
             acc
         });
 
-        let next_sortition = block_ops_124.len() > 0 && burn_total > 0;
+        let next_sortition = !block_ops_124.is_empty() && burn_total > 0;
 
         let mut block_124_snapshot = BlockSnapshot {
             accumulated_coinbase_ustx: 400_000_000,

stackslib/src/burnchains/tests/mod.rs

@@ -178,7 +178,7 @@ impl TestMiner {
     }
 
     pub fn next_VRF_key(&mut self) -> VRFPrivateKey {
-        let pk = if self.vrf_keys.len() == 0 {
+        let pk = if self.vrf_keys.is_empty() {
             // first key is simply the 32-byte hash of the secret state
             let mut buf: Vec<u8> = vec![];
             for i in 0..self.privks.len() {
@@ -204,7 +204,7 @@ impl TestMiner {
     }
 
     pub fn next_microblock_privkey(&mut self) -> StacksPrivateKey {
-        let pk = if self.microblock_privks.len() == 0 {
+        let pk = if self.microblock_privks.is_empty() {
             // first key is simply the 32-byte hash of the secret state
             let mut buf: Vec<u8> = vec![];
             for i in 0..self.privks.len() {
@@ -858,7 +858,7 @@ fn process_next_sortition(
     let mut next_commits = vec![];
     let mut next_prev_keys = vec![];
 
-    if prev_keys.len() > 0 {
+    if !prev_keys.is_empty() {
         assert_eq!(miners.len(), prev_keys.len());
 
         // make a Stacks block (hash) for each of the prior block's keys

stackslib/src/chainstate/burn/db/sortdb.rs

@@ -1604,7 +1604,7 @@ impl<'a> SortitionHandleTx<'a> {
                     anchor_block,
                     reward_set.rewarded_addresses.len()
                 );
-                if reward_set.rewarded_addresses.len() == 0 {
+                if reward_set.rewarded_addresses.is_empty() {
                     return Ok(None);
                 }
 
@@ -3587,7 +3587,7 @@ impl SortitionDB {
             NO_PARAMS,
         )?;
 
-        assert!(ast_rule_sets.len() > 0);
+        assert!(!ast_rule_sets.is_empty());
         let mut last_height = ast_rule_sets[0].1;
         let mut last_rules = ast_rule_sets[0].0;
         for (ast_rules, ast_rule_height) in ast_rule_sets.into_iter() {
@@ -4049,7 +4049,7 @@ impl SortitionDB {
 
     fn parse_last_anchor_block_hash(s: Option<String>) -> Option<BlockHeaderHash> {
         s.map(|s| {
-            if s == "" {
+            if s.is_empty() {
                 None
             } else {
                 Some(BlockHeaderHash::from_hex(&s).expect("BUG: Bad BlockHeaderHash stored in DB"))
@@ -4060,7 +4060,7 @@ impl SortitionDB {
 
     fn parse_last_anchor_block_txid(s: Option<String>) -> Option<Txid> {
         s.map(|s| {
-            if s == "" {
+            if s.is_empty() {
                 None
             } else {
                 Some(Txid::from_hex(&s).expect("BUG: Bad Txid stored in DB"))
@@ -4593,10 +4593,10 @@ impl SortitionDB {
 
         // remove the first entry -- it's always `n` based on the way we construct it, while the
         // heaviest affirmation map just has nothing.
-        if am.len() > 0 {
-            Ok(AffirmationMap::new(am.as_slice()[1..].to_vec()))
-        } else {
+        if am.is_empty() {
             Ok(AffirmationMap::empty())
+        } else {
+            Ok(AffirmationMap::new(am.as_slice()[1..].to_vec()))
         }
     }
 
@@ -5239,7 +5239,7 @@ impl SortitionDB {
         cache: &mut BlockHeaderCache,
         header_data: &Vec<(ConsensusHash, Option<BlockHeaderHash>)>,
     ) -> () {
-        if header_data.len() > 0 {
+        if !header_data.is_empty() {
             let mut i = header_data.len() - 1;
             while i > 0 {
                 let cur_consensus_hash = &header_data[i].0;
@@ -5881,7 +5881,7 @@ impl<'a> SortitionHandleTx<'a> {
                 "SELECT 1 FROM snapshots WHERE burn_header_hash = ?1 AND pox_valid = 1 LIMIT 1",
                 &[&snapshot.burn_header_hash],
             )?;
-            if all_valid_sortitions.len() > 0 {
+            if !all_valid_sortitions.is_empty() {
                 error!("FATAL: Tried to insert snapshot {:?}, but already have pox-valid sortition for {:?}", &snapshot, &snapshot.burn_header_hash);
                 panic!();
             }
@@ -6118,7 +6118,10 @@ impl<'a> SortitionHandleTx<'a> {
                 if let Some(mut reward_set) = reward_info.known_selected_anchor_block_owned() {
                     // record payouts separately from the remaining addresses, since some of them
                     // could have just been consumed.
-                    if reward_set.rewarded_addresses.len() > 0 {
+                    if reward_set.rewarded_addresses.is_empty() {
+                        // no payouts
+                        pox_payout_addrs = vec![];
+                    } else {
                         // if we have a reward set, then we must also have produced a recipient
                         //   info for this block
                         let mut recipients_to_remove: Vec<_> = recipient_info
@@ -6136,9 +6139,6 @@ impl<'a> SortitionHandleTx<'a> {
                                        "BUG: Attempted to remove used address from reward set, but failed to do so safely");
                         }
                         pox_payout_addrs = addrs;
-                    } else {
-                        // no payouts
-                        pox_payout_addrs = vec![];
                     }
 
                     keys.push(db_keys::pox_reward_set_size().to_string());
@@ -6321,7 +6321,7 @@ impl<'a> SortitionHandleTx<'a> {
             }
         }
 
-        if tied.len() == 0 {
+        if tied.is_empty() {
             return None;
         }
         if tied.len() == 1 {
@@ -10635,10 +10635,10 @@ pub mod tests {
                         .map(|op| BlockstackOperationType::LeaderBlockCommit(op.clone()))
                 })
                 .collect();
-            let winner = if commit_set.len() > 0 {
-                commit_set[0].clone()
-            } else {
+            let winner = if commit_set.is_empty() {
                 None
+            } else {
+                commit_set[0].clone()
             };
             let burn_header_hash = headers[i + 1].block_hash.clone();
             let burn_block_height = headers[i + 1].block_height;

stackslib/src/chainstate/burn/distribution.rs

@@ -366,7 +366,7 @@ impl BurnSamplePoint {
     /// Calculate the ranges between 0 and 2**256 - 1 over which each point in the burn sample
     /// applies, so we can later select which block to use.
     fn make_sortition_ranges(burn_sample: &mut Vec<BurnSamplePoint>) -> () {
-        if burn_sample.len() == 0 {
+        if burn_sample.is_empty() {
             // empty sample
             return;
         }

stackslib/src/chainstate/burn/operations/delegate_stx.rs

@@ -136,7 +136,7 @@ impl DelegateStxOp {
             return Err(op_error::InvalidInput);
         }
 
-        if outputs.len() == 0 {
+        if outputs.is_empty() {
             warn!(
                 "Invalid tx: inputs: {}, outputs: {}",
                 tx.num_signers(),

stackslib/src/chainstate/burn/operations/leader_block_commit.rs

@@ -293,7 +293,7 @@ impl LeaderBlockCommitOp {
             return Err(op_error::InvalidInput);
         }
 
-        if outputs.len() == 0 {
+        if outputs.is_empty() {
             warn!(
                 "Invalid tx: inputs: {}, outputs: {}",
                 tx.num_signers(),
@@ -832,7 +832,7 @@ impl LeaderBlockCommitOp {
     /// Check the epoch marker in a block-commit to make sure it matches the right epoch.
     /// Valid in Stacks 2.05+
     fn check_epoch_commit_marker(&self, marker: u8) -> Result<(), op_error> {
-        if self.memo.len() < 1 {
+        if self.memo.is_empty() {
             debug!(
                 "Invalid block commit";
                 "reason" => "no epoch marker byte given",
@@ -860,7 +860,7 @@ impl LeaderBlockCommitOp {
             }
             StacksEpochId::Epoch20 => {
                 // no-op, but log for helping node operators watch for old nodes
-                if self.memo.len() < 1 {
+                if self.memo.is_empty() {
                     debug!(
                         "Soon-to-be-invalid block commit";
                         "reason" => "no epoch marker byte given",

stackslib/src/chainstate/burn/operations/stack_stx.rs

@@ -119,7 +119,7 @@ impl PreStxOp {
         };
 
         let outputs = tx.get_recipients();
-        assert!(outputs.len() > 0);
+        assert!(!outputs.is_empty());
 
         let output = outputs[0]
             .as_ref()
@@ -317,7 +317,7 @@ impl StackStxOp {
         })?;
 
         let outputs = tx.get_recipients();
-        assert!(outputs.len() > 0);
+        assert!(!outputs.is_empty());
 
         let first_output = outputs[0].as_ref().ok_or_else(|| {
             warn!("Invalid tx: failed to decode first output");

stackslib/src/chainstate/burn/operations/transfer_stx.rs

@@ -177,7 +177,7 @@ impl TransferStxOp {
         })?;
 
         let outputs = tx.get_recipients();
-        assert!(outputs.len() > 0);
+        assert!(!outputs.is_empty());
 
         let output = outputs[0]
             .as_ref()

stackslib/src/chainstate/burn/sortition.rs

@@ -132,7 +132,7 @@ impl BlockSnapshot {
         VRF_seed: &VRFSeed,
         sortition_hash: &SortitionHash,
     ) -> Option<usize> {
-        if dist.len() == 0 {
+        if dist.is_empty() {
             // no winners
             return None;
         }
@@ -592,7 +592,7 @@ impl BlockSnapshot {
             )
         };
 
-        if state_transition.burn_dist.len() == 0 {
+        if state_transition.burn_dist.is_empty() {
             // no burns happened
             debug!(
                 "No burns happened in block";