Enable prealloc linter (#607)

.golangci.yml

@@ -23,7 +23,7 @@ linters:
     - bodyclose # go1.18
     - gosec
 #    - forcetypeassert
-#    - prealloc
+    - prealloc
 #    - contextcheck
 #    - goerr113
 #    - revive

aggregator/aggregator.go

@@ -1426,8 +1426,7 @@ func (cvt *CommitmentValTransform) commitmentValTransform(val, transValBuf commi
 	if err != nil {
 		return nil, err
 	}
-	var transAccountPks [][]byte
-	var transStoragePks [][]byte
+	transAccountPks := make([][]byte, 0, len(accountPlainKeys))
 	var apkBuf, spkBuf []byte
 	for _, accountPlainKey := range accountPlainKeys {
 		if len(accountPlainKey) == length.Addr {
@@ -1463,6 +1462,8 @@ func (cvt *CommitmentValTransform) commitmentValTransform(val, transValBuf commi
 		}
 		transAccountPks = append(transAccountPks, accountPlainKey)
 	}
+
+	transStoragePks := make([][]byte, 0, len(storagePlainKeys))
 	for _, storagePlainKey := range storagePlainKeys {
 		if len(storagePlainKey) == length.Addr+length.Hash {
 			// Non-optimised key originating from a database record

commitment/bin_patricia_hashed_test.go

@@ -141,7 +141,7 @@ func Test_BinPatriciaTrie_EmptyState(t *testing.T) {
 }
 
 func renderUpdates(branchNodeUpdates map[string]BranchData) {
-	var keys []string
+	keys := make([]string, 0, len(branchNodeUpdates))
 	for key := range branchNodeUpdates {
 		keys = append(keys, key)
 	}

commitment/patricia_state_mock_test.go

@@ -487,7 +487,7 @@ func (ub *UpdateBuilder) DeleteStorage(addr string, loc string) *UpdateBuilder {
 // 2. Corresponding hashed keys
 // 3. Corresponding updates
 func (ub *UpdateBuilder) Build() (plainKeys, hashedKeys [][]byte, updates []Update) {
-	var hashed []string
+	hashed := make([]string, 0, len(ub.keyset)+len(ub.keyset2))
 	preimages := make(map[string][]byte)
 	preimages2 := make(map[string][]byte)
 	keccak := sha3.NewLegacyKeccak256()

compress/compress.go

@@ -1003,8 +1003,8 @@ func (c *CompressorSequential) optimiseCodes() error {
 		}
 		//fmt.Printf("[comp] depth=%d, code=[%b], pattern=[%x]\n", p.depth, p.code, p.word)
 	}
-	var positionList PositionList
-	pos2code := make(map[uint64]*Position)
+	positionList := make(PositionList, 0, len(c.posMap))
+	pos2code := make(map[uint64]*Position, len(c.posMap))
 	for pos, uses := range c.posMap {
 		p := &Position{pos: pos, uses: uses, code: pos, codeBits: 0}
 		positionList = append(positionList, p)

kv/kvcache/cache.go

@@ -500,7 +500,7 @@ func (c *Coherent) evictRoots() {
 		return
 	}
 	to := c.latestViewID - ViewID(c.cfg.KeepViews)
-	var toDel []ViewID
+	toDel := make([]ViewID, 0, len(c.roots))
 	for txID := range c.roots {
 		if txID > to {
 			continue