modernize for Go 1.22

benchmark_test.go

@@ -93,7 +93,7 @@ func benchmarkQueryHelper(b *testing.B, compr bool) {
 	defer wg.Wait()
 	b.StartTimer()
 
-	for i := 0; i < concurrencyLevel; i++ {
+	for range concurrencyLevel {
 		go func() {
 			for {
 				if atomic.AddInt64(&remain, -1) < 0 {
@@ -130,7 +130,7 @@ func BenchmarkExec(b *testing.B) {
 	defer wg.Wait()
 	b.StartTimer()
 
-	for i := 0; i < concurrencyLevel; i++ {
+	for range concurrencyLevel {
 		go func() {
 			for {
 				if atomic.AddInt64(&remain, -1) < 0 {
@@ -345,7 +345,7 @@ func BenchmarkQueryRawBytes(b *testing.B) {
 	for i := range blob {
 		blob[i] = 42
 	}
-	for i := 0; i < 100; i++ {
+	for i := range 100 {
 		_, err := db.Exec("INSERT INTO bench_rawbytes VALUES (?, ?)", i, blob)
 		if err != nil {
 			b.Fatal(err)
@@ -401,7 +401,7 @@ func BenchmarkReceiveMassiveRows(b *testing.B) {
 	}
 	for i := 0; i < 10000; i += 100 {
 		args := make([]any, 200)
-		for j := 0; j < 100; j++ {
+		for j := range 100 {
 			args[j*2] = i + j
 			args[j*2+1] = sval
 		}

connection_test.go

@@ -141,7 +141,7 @@ func TestCleanCancel(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	cancel()
 
-	for i := 0; i < 3; i++ { // Repeat same behavior
+	for range 3 { // Repeat same behavior
 		err := mc.Ping(ctx)
 		if err != context.Canceled {
 			t.Errorf("expected context.Canceled, got %#v", err)

driver_test.go

@@ -26,6 +26,7 @@ import (
 	"os"
 	"reflect"
 	"runtime"
+	"slices"
 	"strconv"
 	"strings"
 	"sync"
@@ -1926,7 +1927,7 @@ func TestPreparedManyCols(t *testing.T) {
 		rows.Close()
 
 		// Create 0byte string which we can't send via STMT_LONG_DATA.
-		for i := 0; i < numParams; i++ {
+		for i := range numParams {
 			params[i] = ""
 		}
 		rows, err = stmt.Query(params...)
@@ -1971,7 +1972,7 @@ func TestConcurrent(t *testing.T) {
 			})
 		}
 
-		for i := 0; i < max; i++ {
+		for i := range max {
 			go func(id int) {
 				defer wg.Done()
 
@@ -2355,7 +2356,7 @@ func TestPing(t *testing.T) {
 			q.Close()
 
 			// Verify that Ping() clears both fields.
-			for i := 0; i < 2; i++ {
+			for range 2 {
 				if err := c.Ping(ctx); err != nil {
 					dbt.fail("Pinger", "Ping", err)
 				}
@@ -2558,7 +2559,7 @@ func TestMultiResultSet(t *testing.T) {
 			}
 			defer stmt.Close()
 
-			for j := 0; j < 2; j++ {
+			for j := range 2 {
 				rows, err := stmt.Query()
 				if err != nil {
 					dbt.Fatalf("%v (i=%d) (j=%d)", err, i, j)
@@ -2665,7 +2666,7 @@ func TestQueryMultipleResults(t *testing.T) {
 			c := conn.(*mysqlConn)
 
 			// Demonstrate that repeated queries reset the affectedRows
-			for i := 0; i < 2; i++ {
+			for range 2 {
 				_, err := qr.Query(`
 				INSERT INTO test (value) VALUES ('a'), ('b');
 				INSERT INTO test (value) VALUES ('c'), ('d'), ('e');
@@ -3293,11 +3294,11 @@ func TestRawBytesAreNotModified(t *testing.T) {
 
 	runTests(t, dsn, func(dbt *DBTest) {
 		dbt.mustExec("CREATE TABLE test (id int, value BLOB) CHARACTER SET utf8")
-		for i := 0; i < insertRows; i++ {
+		for i := range insertRows {
 			dbt.mustExec("INSERT INTO test VALUES (?, ?)", i+1, sqlBlobs[i&1])
 		}
 
-		for i := 0; i < contextRaceIterations; i++ {
+		for i := range contextRaceIterations {
 			func() {
 				ctx, cancel := context.WithCancel(context.Background())
 				defer cancel()
@@ -3552,8 +3553,8 @@ func TestConnectionAttributes(t *testing.T) {
 		rowsMap[attrName] = attrValue
 	}
 
-	connAttrs := append(append([]string{}, defaultAttrs...), customAttrs...)
-	expectedAttrValues := append(append([]string{}, defaultAttrValues...), customAttrValues...)
+	connAttrs := slices.Concat(defaultAttrs, customAttrs)
+	expectedAttrValues := slices.Concat(defaultAttrValues, customAttrValues)
 	for i := range connAttrs {
 		if gotValue := rowsMap[connAttrs[i]]; gotValue != expectedAttrValues[i] {
 			dbt.Errorf("expected %q, got %q", expectedAttrValues[i], gotValue)
@@ -3637,7 +3638,7 @@ func TestIssue1567(t *testing.T) {
 			count = max
 		}
 
-		for i := 0; i < count; i++ {
+		for range count {
 			timeout := time.Duration(mrand.Int63n(int64(rtt)))
 			ctx, cancel := context.WithTimeout(context.Background(), timeout)
 			dbt.db.PingContext(ctx)

dsn.go

@@ -414,7 +414,7 @@ func ParseDSN(dsn string) (cfg *Config, err error) {
 					if dsn[j] == '@' {
 						// username[:password]
 						// Find the first ':' in dsn[:j]
-						for k = 0; k < j; k++ {
+						for k = 0; k < j; k++ { // We cannot use k = range j here, because we use dsn[:k] below
 							if dsn[k] == ':' {
 								cfg.Passwd = dsn[k+1 : j]
 								break

infile.go

@@ -95,10 +95,7 @@ const defaultPacketSize = 16 * 1024 // 16KB is small enough for disk readahead a
 
 func (mc *okHandler) handleInFileRequest(name string) (err error) {
 	var rdr io.Reader
-	packetSize := defaultPacketSize
-	if mc.maxWriteSize < packetSize {
-		packetSize = mc.maxWriteSize
-	}
+	packetSize := min(mc.maxWriteSize, defaultPacketSize)
 
 	if idx := strings.Index(name, "Reader::"); idx == 0 || (idx > 0 && name[idx-1] == '/') { // io.Reader
 		// The server might return an an absolute path. See issue #355.

packets.go

@@ -984,10 +984,7 @@ func (stmt *mysqlStmt) writeExecutePacket(args []driver.Value) error {
 	mc := stmt.mc
 
 	// Determine threshold dynamically to avoid packet size shortage.
-	longDataSize := mc.maxAllowedPacket / (stmt.paramCount + 1)
-	if longDataSize < 64 {
-		longDataSize = 64
-	}
+	longDataSize := max(mc.maxAllowedPacket/(stmt.paramCount+1), 64)
 
 	// Reset packet-sequence
 	mc.resetSequence()

result.go

@@ -8,6 +8,8 @@
 
 package mysql
 
+import "slices"
+
 import "database/sql/driver"
 
 // Result exposes data not available through *connection.Result.
@@ -42,9 +44,9 @@ func (res *mysqlResult) RowsAffected() (int64, error) {
 }
 
 func (res *mysqlResult) AllLastInsertIds() []int64 {
-	return append([]int64{}, res.insertIds...) // defensive copy
+	return slices.Clone(res.insertIds) // defensive copy
 }
 
 func (res *mysqlResult) AllRowsAffected() []int64 {
-	return append([]int64{}, res.affectedRows...) // defensive copy
+	return slices.Clone(res.affectedRows) // defensive copy
 }

utils.go

@@ -182,7 +182,7 @@ func parseDateTime(b []byte, loc *time.Location) (time.Time, error) {
 
 func parseByteYear(b []byte) (int, error) {
 	year, n := 0, 1000
-	for i := 0; i < 4; i++ {
+	for i := range 4 {
 		v, err := bToi(b[i])
 		if err != nil {
 			return 0, err
@@ -207,7 +207,7 @@ func parseByte2Digits(b1, b2 byte) (int, error) {
 
 func parseByteNanoSec(b []byte) (int, error) {
 	ns, digit := 0, 100000 // max is 6-digits
-	for i := 0; i < len(b); i++ {
+	for i := range b {
 		v, err := bToi(b[i])
 		if err != nil {
 			return 0, err
@@ -678,7 +678,7 @@ func escapeStringBackslash(buf []byte, v string) []byte {
 	pos := len(buf)
 	buf = reserveBuffer(buf, len(v)*2)
 
-	for i := 0; i < len(v); i++ {
+	for i := range len(v) {
 		c := v[i]
 		switch c {
 		case '\x00':
@@ -746,7 +746,7 @@ func escapeStringQuotes(buf []byte, v string) []byte {
 	pos := len(buf)
 	buf = reserveBuffer(buf, len(v)*2)
 
-	for i := 0; i < len(v); i++ {
+	for i := range len(v) {
 		c := v[i]
 		if c == '\'' {
 			buf[pos+1] = '\''