Enable prealloc linter (#5177)

* Enable prealloc linter

* Set inital slice len to 0

.golangci.yml

@@ -16,6 +16,7 @@ linters:
     - bodyclose
     - gosec
 #    - forcetypeassert
+    - prealloc
 
 linters-settings:
   gocritic:

cmd/downloader/downloader/util.go

@@ -42,7 +42,7 @@ func AllTorrentPaths(dir string) ([]string, error) {
 	if err != nil {
 		return nil, err
 	}
-	var res []string
+	res := make([]string, 0, len(files))
 	for _, f := range files {
 		torrentFilePath := filepath.Join(dir, f)
 		res = append(res, torrentFilePath)
@@ -55,7 +55,7 @@ func AllTorrentFiles(dir string) ([]string, error) {
 	if err != nil {
 		return nil, err
 	}
-	var res []string
+	res := make([]string, 0, len(files))
 	for _, f := range files {
 		if !snap.IsCorrectFileName(f.Name()) {
 			continue
@@ -79,7 +79,7 @@ func seedableSegmentFiles(dir string) ([]string, error) {
 	if err != nil {
 		return nil, err
 	}
-	var res []string
+	res := make([]string, 0, len(files))
 	for _, f := range files {
 		if !snap.IsCorrectFileName(f.Name()) {
 			continue

cmd/rpcdaemon/commands/bor_helper.go

@@ -131,7 +131,7 @@ func getUpdatedValidatorSet(oldValidatorSet *ValidatorSet, newVals []*bor.Valida
 	v := oldValidatorSet
 	oldVals := v.Validators
 
-	var changes []*bor.Validator
+	changes := make([]*bor.Validator, 0, len(oldVals))
 	for _, ov := range oldVals {
 		if f, ok := validatorContains(newVals, ov); ok {
 			ov.VotingPower = f.VotingPower

cmd/rpcdaemon/commands/call_traces_test.go

@@ -34,7 +34,7 @@ func blockNumbersFromTraces(t *testing.T, b []byte) []int {
 	if elems, err = v.Array(); err != nil {
 		t.Fatalf("expected array in the response: %v", err)
 	}
-	var numbers []int
+	numbers := make([]int, 0, len(elems))
 	for _, elem := range elems {
 		bn := elem.GetInt("blockNumber")
 		numbers = append(numbers, bn)

cmd/rpcdaemon/commands/starknet_call.go

@@ -86,7 +86,7 @@ func (api *StarknetImpl) Call(ctx context.Context, request StarknetCallRequest,
 		return nil, err
 	}
 
-	var result []string
+	result := make([]string, 0, len(response.Result))
 	for _, v := range response.Result {
 		s := wrapperspb.String("")
 		v.UnmarshalTo(s)

cmd/rpcdaemon22/commands/bor_helper.go

@@ -131,7 +131,7 @@ func getUpdatedValidatorSet(oldValidatorSet *ValidatorSet, newVals []*bor.Valida
 	v := oldValidatorSet
 	oldVals := v.Validators
 
-	var changes []*bor.Validator
+	changes := make([]*bor.Validator, 0, len(oldVals))
 	for _, ov := range oldVals {
 		if f, ok := validatorContains(newVals, ov); ok {
 			ov.VotingPower = f.VotingPower

cmd/rpcdaemon22/commands/call_traces_test.go

@@ -34,7 +34,7 @@ func blockNumbersFromTraces(t *testing.T, b []byte) []int {
 	if elems, err = v.Array(); err != nil {
 		t.Fatalf("expected array in the response: %v", err)
 	}
-	var numbers []int
+	numbers := make([]int, 0, len(elems))
 	for _, elem := range elems {
 		bn := elem.GetInt("blockNumber")
 		numbers = append(numbers, bn)

cmd/rpcdaemon22/commands/starknet_call.go

@@ -86,7 +86,7 @@ func (api *StarknetImpl) Call(ctx context.Context, request StarknetCallRequest,
 		return nil, err
 	}
 
-	var result []string
+	result := make([]string, 0, len(response.Result))
 	for _, v := range response.Result {
 		s := wrapperspb.String("")
 		v.UnmarshalTo(s)

cmd/utils/flags.go

@@ -1604,9 +1604,9 @@ func MakeConsolePreloads(ctx *cli.Context) []string {
 		return nil
 	}
 	// Otherwise resolve absolute paths and return them
-	var preloads []string
-
-	for _, file := range strings.Split(ctx.GlobalString(PreloadJSFlag.Name), ",") {
+	files := strings.Split(ctx.GlobalString(PreloadJSFlag.Name), ",")
+	preloads := make([]string, 0, len(files))
+	for _, file := range files {
 		preloads = append(preloads, strings.TrimSpace(file))
 	}
 	return preloads

consensus/aura/aura.go

@@ -417,7 +417,7 @@ func NewAuRa(config *params.AuRaConfig, db kv.RwDB, ourSigningAddress common.Add
 	if auraParams.StartStep != nil {
 		initialStep = *auraParams.StartStep
 	}
-	var durations []StepDurationInfo
+	durations := make([]StepDurationInfo, 0, 1+len(auraParams.StepDurations))
 	durInfo := StepDurationInfo{
 		TransitionStep:      0,
 		TransitionTimestamp: 0,

consensus/bor/bor.go

@@ -1137,7 +1137,7 @@ func (c *Bor) fetchAndCommitSpan(
 	}
 
 	// get validators bytes
-	var validators []MinimalVal
+	validators := make([]MinimalVal, 0, len(heimdallSpan.ValidatorSet.Validators))
 	for _, val := range heimdallSpan.ValidatorSet.Validators {
 		validators = append(validators, val.MinimalVal())
 	}
@@ -1147,7 +1147,7 @@ func (c *Bor) fetchAndCommitSpan(
 	}
 
 	// get producers bytes
-	var producers []MinimalVal
+	producers := make([]MinimalVal, 0, len(heimdallSpan.SelectedProducers))
 	for _, val := range heimdallSpan.SelectedProducers {
 		producers = append(producers, val.MinimalVal())
 	}
@@ -1330,7 +1330,7 @@ func getUpdatedValidatorSet(oldValidatorSet *ValidatorSet, newVals []*Validator)
 	v := oldValidatorSet
 	oldVals := v.Validators
 
-	var changes []*Validator
+	changes := make([]*Validator, 0, len(oldVals))
 	for _, ov := range oldVals {
 		if f, ok := validatorContains(newVals, ov); ok {
 			ov.VotingPower = f.VotingPower

consensus/bor/merkle.go

@@ -37,7 +37,7 @@ func ConvertTo32(input []byte) (output [32]byte, err error) {
 }
 
 func Convert(input [][32]byte) [][]byte {
-	var output [][]byte
+	output := make([][]byte, 0, len(input))
 	for _, in := range input {
 		newInput := make([]byte, len(in[:]))
 		copy(newInput, in[:])

core/asm/lex_test.go

@@ -24,7 +24,7 @@ import (
 func lexAll(src string) []token {
 	ch := Lex([]byte(src), false)
 
-	var tokens []token
+	var tokens []token // nolint:prealloc
 	for i := range ch {
 		tokens = append(tokens, i)
 	}

core/state/access_list_test.go

@@ -10,7 +10,7 @@ import (
 func verifyAddrs(t *testing.T, s *IntraBlockState, astrings ...string) {
 	t.Helper()
 	// convert to common.Address form
-	var addresses []common.Address
+	addresses := make([]common.Address, 0, len(astrings))
 	var addressMap = make(map[common.Address]struct{})
 	for _, astring := range astrings {
 		address := common.HexToAddress(astring)
@@ -37,7 +37,7 @@ func verifySlots(t *testing.T, s *IntraBlockState, addrString string, slotString
 	}
 	var address = common.HexToAddress(addrString)
 	// convert to common.Hash form
-	var slots []common.Hash
+	slots := make([]common.Hash, 0, len(slotStrings))
 	var slotMap = make(map[common.Hash]struct{})
 	for _, slotString := range slotStrings {
 		s := common.HexToHash(slotString)

eth/backend.go

@@ -866,7 +866,7 @@ func (s *Ethereum) Peers(ctx context.Context) (*remote.PeersReply, error) {
 // Protocols returns all the currently configured
 // network protocols to start.
 func (s *Ethereum) Protocols() []p2p.Protocol {
-	var protocols []p2p.Protocol
+	protocols := make([]p2p.Protocol, 0, len(s.sentryServers))
 	for i := range s.sentryServers {
 		protocols = append(protocols, s.sentryServers[i].Protocol)
 	}

eth/filters/filter.go

@@ -66,7 +66,7 @@ func NewRangeFilter(backend Backend, begin, end int64, addresses []common.Addres
 	// Flatten the address and topic filter clauses into a single bloombits filter
 	// system. Since the bloombits are not positional, nil topics are permitted,
 	// which get flattened into a nil byte slice.
-	var filters [][][]byte
+	filters := make([][][]byte, 0, len(topics))
 	if len(addresses) > 0 {
 		filter := make([][]byte, len(addresses))
 		for i, address := range addresses {

eth/protocols/eth/handlers.go

@@ -133,10 +133,9 @@ func AnswerGetBlockHeadersQuery(db kv.Tx, query *GetBlockHeadersPacket, blockRea
 
 func AnswerGetBlockBodiesQuery(db kv.Tx, query GetBlockBodiesPacket) []rlp.RawValue { //nolint:unparam
 	// Gather blocks until the fetch or network limits is reached
-	var (
-		bytes  int
-		bodies []rlp.RawValue
-	)
+	var bytes int
+	bodies := make([]rlp.RawValue, 0, len(query))
+
 	for lookups, hash := range query {
 		if bytes >= softResponseLimit || len(bodies) >= MaxBodiesServe ||
 			lookups >= 2*MaxBodiesServe {

eth/stagedsync/stage_headers.go

@@ -1326,7 +1326,7 @@ func WaitForDownloader(ctx context.Context, cfg HeadersCfg, tx kv.RwTx) error {
 
 	// send all hashes to the Downloader service
 	preverified := snapcfg.KnownCfg(cfg.chainConfig.ChainName, snInDB).Preverified
-	var downloadRequest []snapshotsync.DownloadRequest
+	downloadRequest := make([]snapshotsync.DownloadRequest, 0, len(preverified)+len(missingSnapshots))
 	// build all download requests
 	// builds preverified snapshots request
 	for _, p := range preverified {

ethstats/ethstats.go

@@ -365,7 +365,7 @@ func (s *Service) login(conn *connWrapper) error {
 	// Construct and send the login authentication
 	// infos := s.server.NodeInfo()
 
-	var protocols []string
+	protocols := make([]string, 0, len(s.servers))
 	for _, srv := range s.servers {
 		protocols = append(protocols, fmt.Sprintf("%s/%d", srv.Protocol.Name, srv.Protocol.Version))
 	}
@@ -542,9 +542,7 @@ func (s *Service) assembleBlockStats(block *types.Block, td *big.Int) *blockStat
 		td = common.Big0
 	}
 	// Gather the block infos from the local blockchain
-	var (
-		txs []txStats
-	)
+	txs := make([]txStats, 0, len(block.Transactions()))
 	for _, tx := range block.Transactions() {
 		txs = append(txs, txStats{tx.Hash()})
 	}

node/nodecfg/config.go

@@ -313,7 +313,7 @@ func (c *Config) parsePersistentNodes(w *bool, path string) []*enode.Node {
 		return nil
 	}
 	// Interpret the list as a discovery node array
-	var nodes []*enode.Node
+	nodes := make([]*enode.Node, 0, len(nodelist))
 	for _, url := range nodelist {
 		if url == "" {
 			continue

p2p/discover/table.go

@@ -159,7 +159,7 @@ func (tab *Table) ReadRandomNodes(buf []*enode.Node) (n int) {
 	tab.mutex.Lock()
 	defer tab.mutex.Unlock()
 
-	var nodes []*enode.Node
+	nodes := make([]*enode.Node, 0, len(&tab.buckets))
 	for _, b := range &tab.buckets {
 		for _, n := range b.entries {
 			nodes = append(nodes, unwrapNode(n))

p2p/discover/v5_udp.go

@@ -790,7 +790,7 @@ func (t *UDPv5) handleFindnode(p *v5wire.Findnode, fromID enode.ID, fromAddr *ne
 
 // collectTableNodes creates a FINDNODE result set for the given distances.
 func (t *UDPv5) collectTableNodes(rip net.IP, distances []uint, limit int) []*enode.Node {
-	var nodes []*enode.Node
+	nodes := make([]*enode.Node, 0, len(distances))
 	var processed = make(map[uint]struct{})
 	for _, dist := range distances {
 		// Reject duplicate / invalid distances.

p2p/discover/v5_udp_test.go

@@ -172,7 +172,7 @@ func TestUDPv5_findnodeHandling(t *testing.T) {
 	// This request gets all the distance-249 nodes and some more at 248 because
 	// the bucket at 249 is not full.
 	test.packetIn(&v5wire.Findnode{ReqID: []byte{5}, Distances: []uint{249, 248}})
-	var nodes []*enode.Node
+	nodes := make([]*enode.Node, 0, len(nodes249)+len(nodes248[:10]))
 	nodes = append(nodes, nodes249...)
 	nodes = append(nodes, nodes248[:10]...)
 	test.expectNodes([]byte{5}, 5, nodes)

p2p/dnsdisc/tree.go

@@ -104,7 +104,7 @@ func (t *Tree) Links() []string {
 
 // Nodes returns all nodes contained in the tree.
 func (t *Tree) Nodes() []*enode.Node {
-	var nodes []*enode.Node
+	nodes := make([]*enode.Node, 0, len(t.entries))
 	for _, e := range t.entries {
 		if ee, ok := e.(*enrEntry); ok {
 			nodes = append(nodes, ee.node)

p2p/peer.go

@@ -490,7 +490,7 @@ type PeerInfo struct {
 // Info gathers and returns a collection of metadata known about a peer.
 func (p *Peer) Info() *PeerInfo {
 	// Gather the protocol capabilities
-	var caps []string
+	caps := make([]string, 0, len(p.Caps()))
 	for _, cap := range p.Caps() {
 		caps = append(caps, cap.String())
 	}

turbo/snapshotsync/block_snapshots.go

@@ -598,7 +598,7 @@ func (s *RoSnapshots) ReopenFolder() error {
 	if err != nil {
 		return err
 	}
-	var list []string
+	list := make([]string, 0, len(files))
 	for _, f := range files {
 		_, fName := filepath.Split(f.Path)
 		list = append(list, fName)
@@ -1085,7 +1085,7 @@ func retireBlocks(ctx context.Context, blockFrom, blockTo uint64, chainID uint25
 		notifier.OnNewSnapshot()
 	}
 
-	var downloadRequest []DownloadRequest
+	downloadRequest := make([]DownloadRequest, 0, len(rangesToMerge))
 	for i := range rangesToMerge {
 		downloadRequest = append(downloadRequest, NewDownloadRequest(&rangesToMerge[i], "", ""))
 	}