all: use Go 1.22 range-over-int

Updates #11058

Change-Id: I35e7ef9b90e83cac04ca93fd964ad00ed5b48430
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

util/deephash/deephash.go

@@ -47,7 +47,7 @@
 //
 //	var big *Item = ... // some large data structure that is slow to hash
 //	var manyBig []*Item
-//	for i := 0; i < 1000; i++ {
+//	for i := range 1000 {
 //		manyBig = append(manyBig, &big)
 //	}
 //	deephash.Hash(manyBig)
@@ -208,7 +208,7 @@ type Sum struct {
 }
 
 func (s1 *Sum) xor(s2 Sum) {
-	for i := 0; i < sha256.Size; i++ {
+	for i := range sha256.Size {
 		s1.sum[i] ^= s2.sum[i]
 	}
 }
@@ -492,7 +492,7 @@ func makeArrayHasher(t reflect.Type) typeHasherFunc {
 	nb := t.Elem().Size() // byte size of each array element
 	return func(h *hasher, p pointer) {
 		once.Do(init)
-		for i := 0; i < n; i++ {
+		for i := range n {
 			hashElem(h, p.arrayIndex(i, nb))
 		}
 	}
@@ -545,7 +545,7 @@ func makeSliceHasher(t reflect.Type) typeHasherFunc {
 		h.HashUint8(1) // indicates visiting slice
 		n := p.sliceLen()
 		h.HashUint64(uint64(n))
-		for i := 0; i < n; i++ {
+		for i := range n {
 			pe := pa.arrayIndex(i, nb)
 			hashElem(h, pe)
 		}

util/deephash/deephash_test.go

@@ -202,7 +202,7 @@ func TestDeepHash(t *testing.T) {
 	v := getVal()
 	hash1 := Hash(v)
 	t.Logf("hash: %v", hash1)
-	for i := 0; i < 20; i++ {
+	for range 20 {
 		v := getVal()
 		hash2 := Hash(v)
 		if hash1 != hash2 {
@@ -760,7 +760,7 @@ var sink Sum
 func BenchmarkHash(b *testing.B) {
 	b.ReportAllocs()
 	v := getVal()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		sink = Hash(v)
 	}
 }
@@ -809,14 +809,14 @@ var filterRules = []tailcfg.FilterRule{
 func BenchmarkHashPacketFilter(b *testing.B) {
 	b.ReportAllocs()
 
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		sink = Hash(&filterRules)
 	}
 }
 
 func TestHashMapAcyclic(t *testing.T) {
 	m := map[int]string{}
-	for i := 0; i < 100; i++ {
+	for i := range 100 {
 		m[i] = fmt.Sprint(i)
 	}
 	got := map[string]bool{}
@@ -824,7 +824,7 @@ func TestHashMapAcyclic(t *testing.T) {
 	hb := &hashBuffer{Hash: sha256.New()}
 
 	hash := lookupTypeHasher(reflect.TypeFor[map[int]string]())
-	for i := 0; i < 20; i++ {
+	for range 20 {
 		va := reflect.ValueOf(&m).Elem()
 		hb.Reset()
 		h := new(hasher)
@@ -862,7 +862,7 @@ func TestPrintArray(t *testing.T) {
 func BenchmarkHashMapAcyclic(b *testing.B) {
 	b.ReportAllocs()
 	m := map[int]string{}
-	for i := 0; i < 100; i++ {
+	for i := range 100 {
 		m[i] = fmt.Sprint(i)
 	}
 
@@ -873,7 +873,7 @@ func BenchmarkHashMapAcyclic(b *testing.B) {
 	h := new(hasher)
 	h.Block512.Hash = hb
 
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		h.Reset()
 		hash(h, pointerOf(va.Addr()))
 	}
@@ -883,14 +883,14 @@ func BenchmarkTailcfgNode(b *testing.B) {
 	b.ReportAllocs()
 
 	node := new(tailcfg.Node)
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		sink = Hash(node)
 	}
 }
 
 func TestExhaustive(t *testing.T) {
 	seen := make(map[Sum]bool)
-	for i := 0; i < 100000; i++ {
+	for i := range 100000 {
 		s := Hash(&i)
 		if seen[s] {
 			t.Fatalf("hash collision %v", i)
@@ -971,7 +971,7 @@ func BenchmarkHashArray(b *testing.B) {
 	}
 	x := &T{X: [32]byte{1: 1, 2: 2, 3: 3, 4: 4}}
 
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		sink = Hash(x)
 	}
 }
@@ -1134,7 +1134,7 @@ func BenchmarkAppendTo(b *testing.B) {
 
 	hashBuf := make([]byte, 0, 100)
 	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
+	for range b.N {
 		hashBuf = h.AppendTo(hashBuf[:0])
 	}
 }