Simplify some pattern-matches (#16402)

When those match an exact combinator on Option / Result.

Tool-aided by [comby-rust](https://github.com/huitseeker/comby-rust).

accounts-cluster-bench/src/main.rs

@@ -189,14 +189,13 @@ impl TransactionExecutor {
                         let mut start = Measure::start("sig_status");
                         let statuses: Vec<_> = sigs_w
                             .chunks(200)
-                            .map(|sig_chunk| {
+                            .flat_map(|sig_chunk| {
                                 let only_sigs: Vec<_> = sig_chunk.iter().map(|s| s.0).collect();
                                 client
                                     .get_signature_statuses(&only_sigs)
                                     .expect("status fail")
                                     .value
                             })
-                            .flatten()
                             .collect();
                         let mut num_cleared = 0;
                         let start_len = sigs_w.len();

cli/src/program.rs

@@ -386,22 +386,17 @@ pub fn parse_program_subcommand(
                 default_signer.signer_from_path(matches, wallet_manager)?,
             )];
 
-            let program_location = if let Some(location) = matches.value_of("program_location") {
+            let program_location = matches
-                Some(location.to_string())
+                .value_of("program_location")
-            } else {
+                .map(|location| location.to_string());
-                None
-            };
 
             let buffer_pubkey = if let Ok((buffer_signer, Some(buffer_pubkey))) =
                 signer_of(matches, "buffer", wallet_manager)
             {
                 bulk_signers.push(buffer_signer);
                 Some(buffer_pubkey)
-            } else if let Some(buffer_pubkey) = pubkey_of_signer(matches, "buffer", wallet_manager)?
-            {
-                Some(buffer_pubkey)
             } else {
-                None
+                pubkey_of_signer(matches, "buffer", wallet_manager)?
             };
 
             let program_pubkey = if let Ok((program_signer, Some(program_pubkey))) =
@@ -409,12 +404,8 @@ pub fn parse_program_subcommand(
             {
                 bulk_signers.push(program_signer);
                 Some(program_pubkey)
-            } else if let Some(program_pubkey) =
-                pubkey_of_signer(matches, "program_id", wallet_manager)?
-            {
-                Some(program_pubkey)
             } else {
-                None
+                pubkey_of_signer(matches, "program_id", wallet_manager)?
             };
 
             let upgrade_authority_pubkey =
@@ -463,11 +454,8 @@ pub fn parse_program_subcommand(
             {
                 bulk_signers.push(buffer_signer);
                 Some(buffer_pubkey)
-            } else if let Some(buffer_pubkey) = pubkey_of_signer(matches, "buffer", wallet_manager)?
-            {
-                Some(buffer_pubkey)
             } else {
-                None
+                pubkey_of_signer(matches, "buffer", wallet_manager)?
             };
 
             let buffer_authority_pubkey =

client/src/nonce_utils.rs

@@ -48,10 +48,7 @@ pub fn get_account_with_commitment(
                 .value
                 .ok_or_else(|| Error::Client(format!("AccountNotFound: pubkey={}", nonce_pubkey)))
         })
-        .and_then(|a| match account_identity_ok(&a) {
+        .and_then(|a| account_identity_ok(&a).map(|()| a))
-            Ok(()) => Ok(a),
-            Err(e) => Err(e),
-        })
 }
 
 pub fn account_identity_ok<T: ReadableAccount>(account: &T) -> Result<(), Error> {

core/src/cluster_slots.rs

@@ -191,8 +191,7 @@ impl ClusterSlots {
             .read()
             .unwrap()
             .keys()
-            .filter(|x| **x > root)
+            .filter(|x| **x > root && !my_slots.contains(*x))
-            .filter(|x| !my_slots.contains(*x))
             .map(|x| RepairType::HighestShred(*x, 0))
             .collect()
     }

core/src/crds.rs

@@ -747,8 +747,10 @@ mod test {
                 let num_epoch_slots = crds
                     .table
                     .values()
-                    .filter(|value| value.insert_timestamp >= since)
+                    .filter(|value| {
-                    .filter(|value| matches!(value.value.data, CrdsData::EpochSlots(_, _)))
+                        value.insert_timestamp >= since
+                            && matches!(value.value.data, CrdsData::EpochSlots(_, _))
+                    })
                     .count();
                 assert_eq!(num_epoch_slots, crds.get_epoch_slots_since(since).count());
                 for value in crds.get_epoch_slots_since(since) {

core/src/duplicate_shred.rs

@@ -226,10 +226,7 @@ pub fn into_shreds(
         chunk_index,
         chunk,
         ..
-    } = match chunks.next() {
+    } = chunks.next().ok_or(Error::InvalidDuplicateShreds)?;
-        None => return Err(Error::InvalidDuplicateShreds),
-        Some(chunk) => chunk,
-    };
     let slot_leader = leader(slot).ok_or(Error::UnknownSlotLeader)?;
     let check_chunk = check_chunk(slot, shred_index, shred_type, num_chunks);
     let mut data = HashMap::new();

core/src/rpc.rs

@@ -3185,16 +3185,14 @@ pub mod rpc_full {
             let address = verify_pubkey(address)?;
 
             let config = config.unwrap_or_default();
-            let before = if let Some(before) = config.before {
+            let before = config
-                Some(verify_signature(&before)?)
+                .before
-            } else {
+                .map(|ref before| verify_signature(before))
-                None
+                .transpose()?;
-            };
+            let until = config
-            let until = if let Some(until) = config.until {
+                .until
-                Some(verify_signature(&until)?)
+                .map(|ref until| verify_signature(until))
-            } else {
+                .transpose()?;
-                None
-            };
             let limit = config
                 .limit
                 .unwrap_or(MAX_GET_CONFIRMED_SIGNATURES_FOR_ADDRESS2_LIMIT);

ledger-tool/src/main.rs

@@ -1661,10 +1661,11 @@ fn main() {
                     let parse_results = {
                         if let Some(slot_string) = frozen_regex.captures_iter(&line).next() {
                             Some((slot_string, &mut frozen))
-                        } else if let Some(slot_string) = full_regex.captures_iter(&line).next() {
-                            Some((slot_string, &mut full))
                         } else {
-                            None
+                            full_regex
+                                .captures_iter(&line)
+                                .next()
+                                .map(|slot_string| (slot_string, &mut full))
                         }
                     };
 

ledger/src/blockstore.rs

@@ -2424,10 +2424,7 @@ impl Blockstore {
         for (slot, signature) in address_signatures.into_iter() {
             let transaction_status =
                 self.get_transaction_status(signature, &confirmed_unrooted_slots)?;
-            let err = match transaction_status {
+            let err = transaction_status.and_then(|(_slot, status)| status.status.err());
-                None => None,
-                Some((_slot, status)) => status.status.err(),
-            };
             let block_time = self.get_block_time(slot)?;
             infos.push(ConfirmedTransactionStatusWithSignature {
                 signature,
@@ -3185,10 +3182,8 @@ fn find_slot_meta_in_cached_state<'a>(
 ) -> Option<Rc<RefCell<SlotMeta>>> {
     if let Some(entry) = working_set.get(&slot) {
         Some(entry.new_slot_meta.clone())
-    } else if let Some(entry) = chained_slots.get(&slot) {
-        Some(entry.clone())
     } else {
-        None
+        chained_slots.get(&slot).cloned()
     }
 }
 

ledger/src/leader_schedule_cache.rs

@@ -212,10 +212,8 @@ impl LeaderScheduleCache {
         let epoch_schedule = self.get_epoch_leader_schedule(epoch);
         if epoch_schedule.is_some() {
             epoch_schedule
-        } else if let Some(epoch_schedule) = self.compute_epoch_schedule(epoch, bank) {
-            Some(epoch_schedule)
         } else {
-            None
+            self.compute_epoch_schedule(epoch, bank)
         }
     }
 

net-utils/src/lib.rs

@@ -198,8 +198,7 @@ fn do_verify_reachable_ports(
                     .collect::<Vec<_>>(),
                 checked_ports_and_sockets
                     .iter()
-                    .map(|(_, sockets)| sockets)
+                    .flat_map(|(_, sockets)| sockets),
-                    .flatten(),
             );
 
             let _ = ip_echo_server_request(

programs/bpf_loader/src/syscalls.rs

@@ -297,10 +297,8 @@ fn translate_type_inner<'a, T>(
         Err(SyscallError::UnalignedPointer.into())
     } else {
         unsafe {
-            match translate(memory_mapping, access_type, vm_addr, size_of::<T>() as u64) {
+            translate(memory_mapping, access_type, vm_addr, size_of::<T>() as u64)
-                Ok(value) => Ok(&mut *(value as *mut T)),
+                .map(|value| &mut *(value as *mut T))
-                Err(e) => Err(e),
-            }
         }
     }
 }
@@ -316,10 +314,8 @@ fn translate_type<'a, T>(
     vm_addr: u64,
     loader_id: &Pubkey,
 ) -> Result<&'a T, EbpfError<BpfError>> {
-    match translate_type_inner::<T>(memory_mapping, AccessType::Load, vm_addr, loader_id) {
+    translate_type_inner::<T>(memory_mapping, AccessType::Load, vm_addr, loader_id)
-        Ok(value) => Ok(&*value),
+        .map(|value| &*value)
-        Err(e) => Err(e),
-    }
 }
 
 fn translate_slice_inner<'a, T>(
@@ -361,10 +357,8 @@ fn translate_slice<'a, T>(
     len: u64,
     loader_id: &Pubkey,
 ) -> Result<&'a [T], EbpfError<BpfError>> {
-    match translate_slice_inner::<T>(memory_mapping, AccessType::Load, vm_addr, len, loader_id) {
+    translate_slice_inner::<T>(memory_mapping, AccessType::Load, vm_addr, len, loader_id)
-        Ok(value) => Ok(&*value),
+        .map(|value| &*value)
-        Err(e) => Err(e),
-    }
 }
 
 /// Take a virtual pointer to a string (points to BPF VM memory space), translate it

runtime/src/accounts_hash.rs

@@ -1861,11 +1861,10 @@ pub mod tests {
         // handle fanout^x -1, +0, +1 for a few 'x's
         const FANOUT: usize = 3;
         let mut hash_counts: Vec<_> = (1..6)
-            .map(|x| {
+            .flat_map(|x| {
                 let mark = FANOUT.pow(x);
                 vec![mark - 1, mark, mark + 1]
             })
-            .flatten()
             .collect();
 
         // saturate the test space for threshold to threshold + target

runtime/src/message_processor.rs

@@ -379,10 +379,11 @@ impl<'a> InvokeContext for ThisInvokeContext<'a> {
                 self.account_deps.iter().find(|(key, _)| key == pubkey)
             {
                 Some(account.clone())
-            } else if let Some(pre) = self.pre_accounts.iter().find(|pre| pre.key == *pubkey) {
-                Some(pre.account.clone())
             } else {
-                None
+                self.pre_accounts
+                    .iter()
+                    .find(|pre| pre.key == *pubkey)
+                    .map(|pre| pre.account.clone())
             }
         } else {
             if let Some(account) = self.pre_accounts.iter().find_map(|pre| {

sdk/program/src/instruction.rs

@@ -272,10 +272,7 @@ impl Instruction {
 }
 
 pub fn checked_add(a: u64, b: u64) -> Result<u64, InstructionError> {
-    match a.checked_add(b) {
+    a.checked_add(b).ok_or(InstructionError::InsufficientFunds)
-        Some(sum) => Ok(sum),
-        None => Err(InstructionError::InsufficientFunds),
-    }
 }
 
 /// Account metadata used to define Instructions

storage-bigtable/src/bigtable.rs

@@ -611,10 +611,7 @@ where
             _ => return Err(err),
         },
     }
-    match deserialize_bincode_cell_data(row_data, table, key) {
+    deserialize_bincode_cell_data(row_data, table, key).map(CellData::Bincode)
-        Ok(result) => Ok(CellData::Bincode(result)),
-        Err(err) => Err(err),
-    }
 }
 
 pub(crate) fn deserialize_protobuf_cell_data<T>(

storage-proto/src/convert.rs

@@ -161,11 +161,7 @@ impl TryFrom<generated::ConfirmedBlock> for ConfirmedBlock {
 
 impl From<TransactionWithStatusMeta> for generated::ConfirmedTransaction {
     fn from(value: TransactionWithStatusMeta) -> Self {
-        let meta = if let Some(meta) = value.meta {
+        let meta = value.meta.map(|meta| meta.into());
-            Some(meta.into())
-        } else {
-            None
-        };
         Self {
             transaction: Some(value.transaction.into()),
             meta,
@@ -176,11 +172,7 @@ impl From<TransactionWithStatusMeta> for generated::ConfirmedTransaction {
 impl TryFrom<generated::ConfirmedTransaction> for TransactionWithStatusMeta {
     type Error = bincode::Error;
     fn try_from(value: generated::ConfirmedTransaction) -> std::result::Result<Self, Self::Error> {
-        let meta = if let Some(meta) = value.meta {
+        let meta = value.meta.map(|meta| meta.try_into()).transpose()?;
-            Some(meta.try_into()?)
-        } else {
-            None
-        };
         Ok(Self {
             transaction: value.transaction.expect("transaction is required").into(),
             meta,
@@ -770,10 +762,7 @@ impl From<TransactionByAddrInfo> for tx_by_addr::TransactionByAddrInfo {
 
         Self {
             signature: <Signature as AsRef<[u8]>>::as_ref(&signature).into(),
-            err: match err {
+            err: err.map(|e| e.into()),
-                None => None,
-                Some(e) => Some(e.into()),
-            },
             index,
             memo: memo.map(|memo| tx_by_addr::Memo { memo }),
             block_time: block_time.map(|timestamp| tx_by_addr::UnixTimestamp { timestamp }),
@@ -787,11 +776,10 @@ impl TryFrom<tx_by_addr::TransactionByAddrInfo> for TransactionByAddrInfo {
     fn try_from(
         transaction_by_addr: tx_by_addr::TransactionByAddrInfo,
     ) -> Result<Self, Self::Error> {
-        let err = if let Some(err) = transaction_by_addr.err {
+        let err = transaction_by_addr
-            Some(err.try_into()?)
+            .err
-        } else {
+            .map(|err| err.try_into())
-            None
+            .transpose()?;
-        };
 
         Ok(Self {
             signature: Signature::new(&transaction_by_addr.signature),

tokens/src/arg_parser.rs

@@ -410,15 +410,16 @@ fn parse_distribute_stake_args(
     )?;
 
     let lockup_authority_str = value_t!(matches, "lockup_authority", String).ok();
-    let lockup_authority = match lockup_authority_str {
+    let lockup_authority = lockup_authority_str
-        Some(path) => Some(signer_from_path(
+        .map(|path| {
-            &signer_matches,
+            signer_from_path(
-            &path,
+                &signer_matches,
-            "lockup authority",
+                &path,
-            &mut wallet_manager,
+                "lockup authority",
-        )?),
+                &mut wallet_manager,
-        None => None,
+            )
-    };
+        })
+        .transpose()?;
 
     let stake_args = StakeArgs {
         stake_account_address,