General cleanup (Part 2) (#32998)

* bucket-map: remove unused `mut`

* remove unnecessary explicit `into_iter()` calls

* don't default-construct unit-structs

* prefer `or_default()` to `or_insert_with(T::default())`

* replace "slow zero-filled vec initialization"

---------

Co-authored-by: Trent Nelson <trent@solana.com>

bucket_map/src/bucket.rs

@@ -183,7 +183,7 @@ impl<'b, T: Clone + Copy + 'static> Bucket<T> {
     /// if entry does not exist, return just the index of an empty entry appropriate for this key
     /// returns (existing entry, index of the found or empty entry)
     fn find_index_entry_mut(
-        index: &mut BucketStorage<IndexBucket<T>>,
+        index: &BucketStorage<IndexBucket<T>>,
         key: &Pubkey,
         random: u64,
     ) -> Result<(Option<IndexEntryPlaceInBucket<T>>, u64), BucketMapError> {
@@ -410,7 +410,7 @@ impl<'b, T: Clone + Copy + 'static> Bucket<T> {
             return Err(BucketMapError::DataNoSpace((best_fit_bucket, 0)));
         }
         let max_search = self.index.max_search();
-        let (elem, elem_ix) = Self::find_index_entry_mut(&mut self.index, key, self.random)?;
+        let (elem, elem_ix) = Self::find_index_entry_mut(&self.index, key, self.random)?;
         let elem = if let Some(elem) = elem {
             elem
         } else {

program-runtime/src/loaded_programs.rs

@@ -443,7 +443,7 @@ impl LoadedPrograms {
         key: Pubkey,
         entry: Arc<LoadedProgram>,
     ) -> (bool, Arc<LoadedProgram>) {
-        let second_level = self.entries.entry(key).or_insert_with(Vec::new);
+        let second_level = self.entries.entry(key).or_default();
         let index = second_level
             .iter()
             .position(|at| at.effective_slot >= entry.effective_slot);

programs/system/src/system_processor.rs

@@ -621,8 +621,7 @@ mod tests {
     fn create_default_recent_blockhashes_account() -> AccountSharedData {
         #[allow(deprecated)]
         recent_blockhashes_account::create_account_with_data_for_test(
-            vec![IterItem(0u64, &Hash::default(), 0); sysvar::recent_blockhashes::MAX_ENTRIES]
-                .into_iter(),
+            vec![IterItem(0u64, &Hash::default(), 0); sysvar::recent_blockhashes::MAX_ENTRIES],
         )
     }
     fn create_default_rent_account() -> AccountSharedData {
@@ -1577,8 +1576,7 @@ mod tests {
         #[allow(deprecated)]
         let new_recent_blockhashes_account =
             solana_sdk::recent_blockhashes_account::create_account_with_data_for_test(
-                vec![IterItem(0u64, &blockhash, 0); sysvar::recent_blockhashes::MAX_ENTRIES]
-                    .into_iter(),
+                vec![IterItem(0u64, &blockhash, 0); sysvar::recent_blockhashes::MAX_ENTRIES],
             );
         mock_process_instruction(
             &system_program::id(),
@@ -1863,9 +1861,7 @@ mod tests {
         let blockhash_id = sysvar::recent_blockhashes::id();
         #[allow(deprecated)]
         let new_recent_blockhashes_account =
-            solana_sdk::recent_blockhashes_account::create_account_with_data_for_test(
-                vec![].into_iter(),
-            );
+            solana_sdk::recent_blockhashes_account::create_account_with_data_for_test(vec![]);
         process_instruction(
             &serialize(&SystemInstruction::InitializeNonceAccount(nonce_address)).unwrap(),
             vec![
@@ -1928,9 +1924,7 @@ mod tests {
         );
         #[allow(deprecated)]
         let new_recent_blockhashes_account =
-            solana_sdk::recent_blockhashes_account::create_account_with_data_for_test(
-                vec![].into_iter(),
-            );
+            solana_sdk::recent_blockhashes_account::create_account_with_data_for_test(vec![]);
         mock_process_instruction(
             &system_program::id(),
             Vec::new(),

runtime/src/serde_snapshot.rs

@@ -516,7 +516,7 @@ where
     (SerializableBankAndStorage::<newer::Context> {
         bank,
         snapshot_storages: storage,
-        phantom: std::marker::PhantomData::default(),
+        phantom: std::marker::PhantomData,
     })
     .serialize(s)
 }

sdk/src/recent_blockhashes_account.rs

@@ -97,7 +97,7 @@ mod tests {
 
     #[test]
     fn test_create_account_empty() {
-        let account = create_account_with_data_for_test(vec![].into_iter());
+        let account = create_account_with_data_for_test(vec![]);
         let recent_blockhashes = from_account::<RecentBlockhashes, _>(&account).unwrap();
         assert_eq!(recent_blockhashes, RecentBlockhashes::default());
     }
@@ -106,9 +106,14 @@ mod tests {
     fn test_create_account_full() {
         let def_hash = Hash::default();
         let def_lamports_per_signature = 0;
-        let account = create_account_with_data_for_test(
-            vec![IterItem(0u64, &def_hash, def_lamports_per_signature); MAX_ENTRIES].into_iter(),
-        );
+        let account = create_account_with_data_for_test(vec![
+            IterItem(
+                0u64,
+                &def_hash,
+                def_lamports_per_signature
+            );
+            MAX_ENTRIES
+        ]);
         let recent_blockhashes = from_account::<RecentBlockhashes, _>(&account).unwrap();
         assert_eq!(recent_blockhashes.len(), MAX_ENTRIES);
     }
@@ -117,10 +122,14 @@ mod tests {
     fn test_create_account_truncate() {
         let def_hash = Hash::default();
         let def_lamports_per_signature = 0;
-        let account = create_account_with_data_for_test(
-            vec![IterItem(0u64, &def_hash, def_lamports_per_signature); MAX_ENTRIES + 1]
-                .into_iter(),
-        );
+        let account = create_account_with_data_for_test(vec![
+            IterItem(
+                0u64,
+                &def_hash,
+                def_lamports_per_signature
+            );
+            MAX_ENTRIES + 1
+        ]);
         let recent_blockhashes = from_account::<RecentBlockhashes, _>(&account).unwrap();
         assert_eq!(recent_blockhashes.len(), MAX_ENTRIES);
     }

sdk/src/secp256k1_instruction.rs

@@ -860,15 +860,13 @@ pub fn new_secp256k1_instruction(
     let signature_arr = signature.serialize();
     assert_eq!(signature_arr.len(), SIGNATURE_SERIALIZED_SIZE);
 
-    let mut instruction_data = vec![];
-    instruction_data.resize(
-        DATA_START
-            .saturating_add(eth_pubkey.len())
-            .saturating_add(signature_arr.len())
-            .saturating_add(message_arr.len())
-            .saturating_add(1),
-        0,
-    );
+    let instruction_data_len = DATA_START
+        .saturating_add(eth_pubkey.len())
+        .saturating_add(signature_arr.len())
+        .saturating_add(message_arr.len())
+        .saturating_add(1);
+    let mut instruction_data = vec![0; instruction_data_len];
+
     let eth_address_offset = DATA_START;
     instruction_data[eth_address_offset..eth_address_offset.saturating_add(eth_pubkey.len())]
         .copy_from_slice(&eth_pubkey);