*: improve for loop syntax

Mostly it's about Go 1.22+ syntax with ranging over integers, but it also
prefers ranging over slices where possible (it makes code a little better to
read).

Notice that we have a number of dangerous loops where slices are mutated
during loop execution, many of these can't be converted since we need proper
length evalutation at every iteration.

Signed-off-by: Roman Khimov <[email protected]>

cli/nep_test/nep17_test.go

@@ -81,7 +81,7 @@ func TestNEP17Balance(t *testing.T) {
 
 		e.CheckNextLine(t, "^Account "+testcli.TestWalletMultiAccount1)
 		// The order of assets is undefined.
-		for i := 0; i < 2; i++ {
+		for range 2 {
 			line := e.GetNextLine(t)
 			if strings.Contains(line, "GAS") {
 				e.CheckLine(t, line, "^\\s*GAS:\\s+GasToken \\("+e.Chain.UtilityTokenHash().StringLE()+"\\)")

cli/wallet/nep17.go

@@ -362,7 +362,7 @@ func getMatchingTokenRPC(ctx *cli.Context, c *rpcclient.Client, addr util.Uint16
 func getMatchingTokenAux(ctx *cli.Context, get func(i int) *wallet.Token, n int, name string, standard string) (*wallet.Token, error) {
 	var token *wallet.Token
 	var count int
-	for i := 0; i < n; i++ {
+	for i := range n {
 		t := get(i)
 		if t != nil && (t.Hash.StringLE() == name || t.Address() == name || t.Symbol == name || t.Name == name) && t.Standard == standard {
 			if count == 1 {
@@ -540,7 +540,7 @@ func multiTransferNEP17(ctx *cli.Context) error {
 		recipients      []transferTarget
 		cosignersSepPos = ctx.NArg() // `--` position.
 	)
-	for i := 0; i < ctx.NArg(); i++ {
+	for i := range ctx.NArg() {
 		arg := ctx.Args().Get(i)
 		if arg == cmdargs.CosignersSeparator {
 			cosignersSepPos = i
@@ -561,7 +561,7 @@ func multiTransferNEP17(ctx *cli.Context) error {
 	}
 
 	cache := make(map[string]*wallet.Token)
-	for i := 0; i < cosignersSepPos; i++ {
+	for i := range cosignersSepPos {
 		arg := ctx.Args().Get(i)
 		ss := strings.SplitN(arg, ":", 3)
 		if len(ss) != 3 {

cli/wallet/wallet_test.go

@@ -1062,7 +1062,7 @@ func TestWalletDumpKeys(t *testing.T) {
 		e.CheckNextLine(t, pubRegex)
 		e.CheckNextLine(t, "^\\s*$")
 		e.CheckNextLine(t, "NVTiAjNgagDkTr5HTzDmQP9kPwPHN5BgVq")
-		for i := 0; i < 4; i++ {
+		for range 4 {
 			e.CheckNextLine(t, pubRegex)
 		}
 		e.CheckNextLine(t, "^\\s*$")
@@ -1085,7 +1085,7 @@ func TestWalletDumpKeys(t *testing.T) {
 		cmd := append(cmd, "-a", "NVTiAjNgagDkTr5HTzDmQP9kPwPHN5BgVq")
 		e.Run(t, cmd...)
 		e.CheckNextLine(t, "3 out of 4 multisig contract")
-		for i := 0; i < 4; i++ {
+		for range 4 {
 			e.CheckNextLine(t, pubRegex)
 		}
 		e.CheckEOF(t)

examples/nft-nd-nns/nns_test.go

@@ -158,7 +158,7 @@ func TestRegisterAndRenew(t *testing.T) {
 	c.InvokeWithFeeFail(t, "GAS limit exceeded", defaultNameServiceSysfee, "register", "neo.org", e.CommitteeHash)
 	c.InvokeWithFeeFail(t, "GAS limit exceeded", defaultNameServiceDomainPrice, "register", "neo.com", e.CommitteeHash)
 	var maxLenFragment string
-	for i := 0; i < maxDomainNameFragmentLength; i++ {
+	for i := range maxDomainNameFragmentLength {
 		maxLenFragment += "q"
 	}
 	c.Invoke(t, true, "isAvailable", maxLenFragment+".com")

examples/zkp/cubic_circuit/main_test.go

@@ -315,7 +315,7 @@ func setup(t *testing.T, ccs constraint.ConstraintSystem, phase1ResponsePath str
 	// receive a []byte, deserialize it, add his contribution and send back to
 	// coordinator, like it is done in https://github.com/bnb-chain/zkbnb-setup
 	// for BN254 elliptic curve.
-	for i := 0; i < nContributionsPhase2; i++ {
+	for i := range nContributionsPhase2 {
 		srs2.Contribute()
 	}
 

internal/basicchain/testdata/storage/storage_contract.go

@@ -19,7 +19,7 @@ var valuesPrefix = []byte{0x01}
 func _deploy(data any, isUpdate bool) {
 	if !isUpdate {
 		ctx := storage.GetContext()
-		for i := 0; i < valuesCount; i++ {
+		for i := range valuesCount {
 			key := append(valuesPrefix, byte(i))
 			storage.Put(ctx, key, i)
 		}

internal/testchain/address.go

@@ -128,7 +128,7 @@ func CommitteeAddress() string {
 // Sign signs data by all consensus nodes and returns invocation script.
 func Sign(h hash.Hashable) []byte {
 	buf := io.NewBufBinWriter()
-	for i := 0; i < 3; i++ {
+	for i := range 3 {
 		pKey := PrivateKey(i)
 		sig := pKey.SignHashable(uint32(Network()), h)
 		if len(sig) != 64 {

internal/testcli/executor.go

@@ -377,7 +377,7 @@ func (e *Executor) CheckTxTestInvokeOutput(t *testing.T, scriptSize int) {
 
 func (e *Executor) CheckScriptDump(t *testing.T, scriptSize int) {
 	e.CheckNextLine(t, `INDEX\s+`)
-	for i := 0; i < scriptSize; i++ {
+	for range scriptSize {
 		e.CheckNextLine(t, `\d+\s+\w+`)
 	}
 }

pkg/compiler/analysis.go

@@ -229,7 +229,7 @@ func isExprNil(e ast.Expr) bool {
 // indexOfStruct returns the index of the given field inside that struct.
 // If the struct does not contain that field, it will return -1.
 func indexOfStruct(strct *types.Struct, fldName string) int {
-	for i := 0; i < strct.NumFields(); i++ {
+	for i := range strct.NumFields() {
 		if strct.Field(i).Name() == fldName {
 			return i
 		}

pkg/compiler/codegen.go

@@ -383,7 +383,7 @@ func (c *codegen) isVerifyFunc(decl *ast.FuncDecl) bool {
 }
 
 func (c *codegen) clearSlots(n int) {
-	for i := 0; i < n; i++ {
+	for i := range n {
 		emit.Opcodes(c.prog.BinWriter, opcode.PUSHNULL)
 		c.emitStoreByIndex(varLocal, i)
 	}
@@ -680,7 +680,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 			ast.Walk(c, n.Rhs[0])
 			c.emitToken(n.Tok, c.typeOf(n.Rhs[0]))
 		}
-		for i := 0; i < len(n.Lhs); i++ {
+		for i := range n.Lhs {
 			switch t := n.Lhs[i].(type) {
 			case *ast.Ident:
 				if n.Tok == token.DEFINE {
@@ -1099,7 +1099,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 				f := c.typeOf(n.Fun).Underlying().(*types.Signature)
 				sz = f.Results().Len()
 			}
-			for i := 0; i < sz; i++ {
+			for range sz {
 				emit.Opcodes(c.prog.BinWriter, opcode.DROP)
 			}
 		}
@@ -1662,7 +1662,7 @@ func (c *codegen) dropStackLabel() {
 
 func (c *codegen) dropItems(n int) {
 	if n < 4 {
-		for i := 0; i < n; i++ {
+		for range n {
 			emit.Opcodes(c.prog.BinWriter, opcode.DROP)
 		}
 		return
@@ -1930,7 +1930,7 @@ func (c *codegen) convertBuiltin(expr *ast.CallExpr) {
 					opcode.INC)      // x y cnt+1
 				emit.Jmp(c.prog.BinWriter, opcode.JMPL, start)
 				c.setLabel(after)
-				for i := 0; i < 4; i++ { // leave x on stack
+				for range 4 { // leave x on stack
 					emit.Opcodes(c.prog.BinWriter, opcode.DROP)
 				}
 			} else {
@@ -2012,7 +2012,7 @@ func (c *codegen) emitConvert(typ stackitem.Type) {
 func (c *codegen) convertByteArray(elems []ast.Expr) {
 	buf := make([]byte, len(elems))
 	varIndices := []int{}
-	for i := 0; i < len(elems); i++ {
+	for i := range elems {
 		t := c.typeAndValueOf(elems[i])
 		if t.Value != nil {
 			val, _ := constant.Int64Val(t.Value)
@@ -2508,7 +2508,7 @@ func removeNOPs(b []byte, nopOffsets []int, sequencePoints map[string][]DebugSeq
 	// 2. Convert instructions.
 	copyOffset := 0
 	l := len(nopOffsets)
-	for i := 0; i < l; i++ {
+	for i := range l {
 		start := nopOffsets[i]
 		end := len(b)
 		if i != l-1 {

pkg/compiler/global_test.go

@@ -883,11 +883,11 @@ func TestMultipleFuncSameName(t *testing.T) {
 func TestConstDontUseSlots(t *testing.T) {
 	const count = 256
 	buf := bytes.NewBufferString("package foo\n")
-	for i := 0; i < count; i++ {
+	for i := range count {
 		buf.WriteString(fmt.Sprintf("const n%d = 1\n", i))
 	}
 	buf.WriteString("func Main() int { sum := 0\n")
-	for i := 0; i < count; i++ {
+	for i := range count {
 		buf.WriteString(fmt.Sprintf("sum += n%d\n", i))
 	}
 	buf.WriteString("return sum }")
@@ -899,11 +899,11 @@ func TestConstDontUseSlots(t *testing.T) {
 func TestUnderscoreVarsDontUseSlots(t *testing.T) {
 	const count = 128
 	buf := bytes.NewBufferString("package foo\n")
-	for i := 0; i < count; i++ {
+	for i := range count {
 		buf.WriteString(fmt.Sprintf("var _, n%d = 1, 1\n", i))
 	}
 	buf.WriteString("func Main() int { sum := 0\n")
-	for i := 0; i < count; i++ {
+	for i := range count {
 		buf.WriteString(fmt.Sprintf("sum += n%d\n", i))
 	}
 	buf.WriteString("return sum }")

pkg/compiler/inline.go

@@ -124,7 +124,7 @@ func (c *codegen) inlineCall(f *funcScope, n *ast.CallExpr) {
 	ast.Walk(c, f.decl.Body)
 	c.setLabel(c.inlineContext[offSz].returnLabel)
 	if c.scope.voidCalls[n] {
-		for i := 0; i < f.decl.Type.Results.NumFields(); i++ {
+		for range f.decl.Type.Results.NumFields() {
 			emit.Opcodes(c.prog.BinWriter, opcode.DROP)
 		}
 	}

pkg/compiler/limit_test.go

@@ -15,7 +15,7 @@ func TestManyVariables(t *testing.T) {
 	const count = 155
 
 	buf := bytes.NewBufferString("package main\n")
-	for i := 0; i < count; i++ {
+	for i := range count {
 		buf.WriteString(fmt.Sprintf("var a%d = %d\n", i, i))
 	}
 	buf.WriteString("func Main() int {\nreturn 7\n}\n")

pkg/compiler/native_test.go

@@ -361,7 +361,7 @@ func runNativeTestCase(t *testing.T, b *nef.File, di *compiler.DebugInfo, ctr in
 		if t.CallFlag != md.RequiredFlags {
 			return fmt.Errorf("wrong flags %v", t.CallFlag)
 		}
-		for i := 0; i < int(t.ParamCount); i++ {
+		for range t.ParamCount {
 			_ = v.Estack().Pop()
 		}
 		if v.Estack().Len() != 0 {

pkg/compiler/syscall_test.go

@@ -151,7 +151,7 @@ func runSyscallTestCase(t *testing.T, ic *interop.Context, realName string,
 		if ic.VM.Estack().Len() < f.ParamCount {
 			return errors.New("not enough parameters")
 		}
-		for i := 0; i < f.ParamCount; i++ {
+		for range f.ParamCount {
 			ic.VM.Estack().Pop()
 		}
 		if !tc.isVoid {
@@ -385,7 +385,7 @@ func TestInteropTypesComparison(t *testing.T) {
 	typeCheck := func(t *testing.T, typeName string, typeLen int) {
 		t.Run(typeName, func(t *testing.T) {
 			var ha, hb string
-			for i := 0; i < typeLen; i++ {
+			for i := range typeLen {
 				if i == typeLen-1 {
 					ha += "2"
 					hb += "3"

pkg/consensus/consensus_test.go

@@ -195,7 +195,7 @@ func TestService_GetVerified(t *testing.T) {
 	srv := newTestService(t)
 	srv.dbft.Start(0)
 	var txs []*transaction.Transaction
-	for i := 0; i < 4; i++ {
+	for i := range 4 {
 		tx := transaction.New([]byte{byte(opcode.PUSH1)}, 100000)
 		tx.Nonce = 123 + uint32(i)
 		tx.ValidUntilBlock = 1
@@ -208,7 +208,7 @@ func TestService_GetVerified(t *testing.T) {
 	hashes := []util.Uint256{txs[0].Hash(), txs[1].Hash(), txs[2].Hash()}
 
 	// Everyone sends a message.
-	for i := 0; i < 4; i++ {
+	for i := range 4 {
 		p := new(Payload)
 		// One PrepareRequest and three ChangeViews.
 		if i == 1 {
@@ -578,7 +578,7 @@ func addSender(t *testing.T, txs ...*transaction.Transaction) {
 func signTx(t *testing.T, bc Ledger, txs ...*transaction.Transaction) {
 	validators := make([]*keys.PublicKey, 4)
 	privNetKeys := make([]*keys.PrivateKey, 4)
-	for i := 0; i < 4; i++ {
+	for i := range 4 {
 		privNetKeys[i] = testchain.PrivateKey(i)
 		validators[i] = privNetKeys[i].PublicKey()
 	}

pkg/consensus/payload_test.go

@@ -200,7 +200,7 @@ func randomPrepareRequest(t *testing.T) *prepareRequest {
 		transactionHashes: make([]util.Uint256, txCount),
 	}
 
-	for i := 0; i < txCount; i++ {
+	for i := range txCount {
 		req.transactionHashes[i] = random.Uint256()
 	}
 

pkg/consensus/recovery_message_test.go

@@ -23,7 +23,7 @@ func testRecoveryMessageSetters(t *testing.T, enableStateRoot bool) {
 	srv := newTestServiceWithState(t, enableStateRoot)
 	privs := make([]*privateKey, testchain.Size())
 	pubs := make([]dbft.PublicKey, testchain.Size())
-	for i := 0; i < testchain.Size(); i++ {
+	for i := range testchain.Size() {
 		privs[i], pubs[i] = getTestValidator(i)
 	}
 

pkg/core/bench_test.go

@@ -27,7 +27,7 @@ func BenchmarkBlockchain_VerifyWitness(t *testing.B) {
 	tx := e.NewTx(t, []neotest.Signer{acc}, e.NativeHash(t, nativenames.Gas), "transfer", acc.ScriptHash(), acc.Script(), 1, nil)
 
 	t.ResetTimer()
-	for n := 0; n < t.N; n++ {
+	for range t.N {
 		_, err := bc.VerifyWitness(tx.Signers[0].Account, tx, &tx.Scripts[0], 100000000)
 		require.NoError(t, err)
 	}
@@ -92,9 +92,9 @@ func benchmarkForEachNEP17Transfer(t *testing.B, ps storage.Store, startFromBloc
 	acc := random.Uint160()
 	from := e.Validator.ScriptHash()
 
-	for j := 0; j < chainHeight; j++ {
+	for range chainHeight {
 		b := smartcontract.NewBuilder()
-		for i := 0; i < transfersPerBlock; i++ {
+		for range transfersPerBlock {
 			b.InvokeWithAssert(gasHash, "transfer", from, acc, 1, nil)
 		}
 		script, err := b.Script()
@@ -119,7 +119,7 @@ func benchmarkForEachNEP17Transfer(t *testing.B, ps storage.Store, startFromBloc
 	t.ResetTimer()
 	t.ReportAllocs()
 	t.StartTimer()
-	for i := 0; i < t.N; i++ {
+	for range t.N {
 		require.NoError(t, bc.ForEachNEP17Transfer(acc, newestTimestamp, func(t *state.NEP17Transfer) (bool, error) {
 			if t.Timestamp < oldestTimestamp {
 				// iterating from newest to oldest, already have reached the needed height
@@ -165,7 +165,7 @@ func benchmarkGasPerVote(t *testing.B, ps storage.Store, nRewardRecords int, rew
 	voters := make([]*wallet.Account, sz)
 	candidates := make(keys.PublicKeys, sz)
 	txs := make([]*transaction.Transaction, 0, len(voters)*3)
-	for i := 0; i < sz; i++ {
+	for i := range sz {
 		priv, err := keys.NewPrivateKey()
 		require.NoError(t, err)
 		candidates[i] = priv.PublicKey()
@@ -186,7 +186,7 @@ func benchmarkGasPerVote(t *testing.B, ps storage.Store, nRewardRecords int, rew
 		e.CheckHalt(t, tx.Hash())
 	}
 	voteTxs := make([]*transaction.Transaction, 0, sz)
-	for i := 0; i < sz; i++ {
+	for i := range sz {
 		priv := voters[i].PrivateKey()
 		h := priv.GetScriptHash()
 		voteTx := e.NewTx(t, []neotest.Signer{neotest.NewSingleSigner(voters[i])}, neoHash, "vote", h, candidates[i].Bytes())
@@ -211,7 +211,7 @@ func benchmarkGasPerVote(t *testing.B, ps storage.Store, nRewardRecords int, rew
 	t.ResetTimer()
 	t.ReportAllocs()
 	t.StartTimer()
-	for i := 0; i < t.N; i++ {
+	for range t.N {
 		_, err := bc.CalculateClaimable(to, end)
 		require.NoError(t, err)
 	}

pkg/core/block/block.go

@@ -83,7 +83,7 @@ func NewTrimmedFromReader(stateRootEnabled bool, br *io.BinReader) (*Block, erro
 	}
 	if lenHashes > 0 {
 		block.Transactions = make([]*transaction.Transaction, lenHashes)
-		for i := 0; i < int(lenHashes); i++ {
+		for i := range lenHashes {
 			var hash util.Uint256
 			hash.DecodeBinary(br)
 			block.Transactions[i] = transaction.NewTrimmedTX(hash)
@@ -124,7 +124,7 @@ func (b *Block) DecodeBinary(br *io.BinReader) {
 		return
 	}
 	txes := make([]*transaction.Transaction, contentsCount)
-	for i := 0; i < int(contentsCount); i++ {
+	for i := range txes {
 		tx := &transaction.Transaction{}
 		tx.DecodeBinary(br)
 		txes[i] = tx
@@ -140,7 +140,7 @@ func (b *Block) DecodeBinary(br *io.BinReader) {
 func (b *Block) EncodeBinary(bw *io.BinWriter) {
 	b.Header.EncodeBinary(bw)
 	bw.WriteVarUint(uint64(len(b.Transactions)))
-	for i := 0; i < len(b.Transactions); i++ {
+	for i := range b.Transactions {
 		b.Transactions[i].EncodeBinary(bw)
 	}
 }

pkg/core/block/block_test.go

@@ -73,7 +73,7 @@ func TestTrimmedBlock(t *testing.T) {
 
 	assert.Equal(t, block.Script, trimmedBlock.Script)
 	assert.Equal(t, len(block.Transactions), len(trimmedBlock.Transactions))
-	for i := 0; i < len(block.Transactions); i++ {
+	for i := range block.Transactions {
 		assert.Equal(t, block.Transactions[i].Hash(), trimmedBlock.Transactions[i].Hash())
 		assert.True(t, trimmedBlock.Transactions[i].Trimmed)
 	}

pkg/core/blockchain.go

@@ -1203,7 +1203,7 @@ func (bc *Blockchain) resetTransfers(cache *dao.Simple, height uint32) error {
 				oldBatchSize = v[0]
 				newBatchSize byte
 			)
-			for i := byte(0); i < v[0]; i++ { // From oldest to newest transfer of the batch.
+			for range v[0] { // From oldest to newest transfer of the batch.
 				var t *state.NEP17Transfer
 				if k[0] == byte(storage.STNEP11Transfers) {
 					tr := new(state.NEP11Transfer)