Apply go fix to simplify using modern features

This patch contains the result of running `go fix ./...`, which applies
simplifications that make use of modern language features.

There are no logic or behaviour changes.

internal/nettrace/bench_test.go

@@ -9,9 +9,9 @@ import (
 func runBench(b *testing.B, events int) {
 	nTraces := (b.N + events + 1) / events
 
-	for i := 0; i < nTraces; i++ {
+	for range nTraces {
 		tr := New("bench", "test")
-		for j := 0; j < events; j++ {
+		for j := range events {
 			tr.Printf("%d", j)
 		}
 		tr.Finish()

internal/nettrace/histogram.go

@@ -53,7 +53,7 @@ func (h *histogram) Snapshot() *histSnapshot {
 	}
 
 	var cumCount uint64
-	for i := 0; i < nBuckets; i++ {
+	for i := range nBuckets {
 		cumCount += h.count[i]
 		l := line{
 			Start:     buckets[i],

internal/nettrace/http_test.go

@@ -141,7 +141,7 @@ func TestHTTP(t *testing.T) {
 func TestHTTPLong(t *testing.T) {
 	// Test a long trace.
 	tr := New("TestHTTPLong", "verbose")
-	for i := 0; i < 1000; i++ {
+	for i := range 1000 {
 		tr.Printf("entry #%d", i)
 	}
 	tr.Finish()

internal/nettrace/trace.go

@@ -5,6 +5,7 @@ package nettrace
 import (
 	"container/ring"
 	"fmt"
+	"maps"
 	"math/rand/v2"
 	"sort"
 	"strconv"
@@ -51,11 +52,11 @@ type Trace interface {
 	SetError()
 
 	// Printf adds a message to the trace.
-	Printf(format string, a ...interface{})
+	Printf(format string, a ...any)
 
 	// Errorf adds a message to the trace, marks it as an error, and returns
 	// an error for it.
-	Errorf(format string, a ...interface{}) error
+	Errorf(format string, a ...any) error
 
 	// Finish marks the trace as complete.
 	// The trace should not be used after calling this method.
@@ -220,7 +221,7 @@ func (tr *trace) SetError() {
 	tr.mu.Unlock()
 }
 
-func (tr *trace) Printf(format string, a ...interface{}) {
+func (tr *trace) Printf(format string, a ...any) {
 	evt := &event{
 		When: time.Now(),
 		Type: evtLOG,
@@ -230,7 +231,7 @@ func (tr *trace) Printf(format string, a ...interface{}) {
 	tr.append(evt)
 }
 
-func (tr *trace) Errorf(format string, a ...interface{}) error {
+func (tr *trace) Errorf(format string, a ...any) error {
 	tr.SetError()
 	err := fmt.Errorf(format, a...)
 	tr.Printf("%s", err.Error())
@@ -354,7 +355,7 @@ func (r *traceRing) Len() int {
 }
 
 func (r *traceRing) Do(f func(tr *trace)) {
-	r.ring.Do(func(x interface{}) {
+	r.ring.Do(func(x any) {
 		if x == nil {
 			return
 		}
@@ -382,7 +383,7 @@ type familyTraces struct {
 func newFamilyTraces() *familyTraces {
 	ft := &familyTraces{}
 	ft.active = map[id]*trace{}
-	for i := 0; i < nBuckets; i++ {
+	for i := range nBuckets {
 		ft.finished[i] = newTraceRing(tracesInBucket)
 	}
 	ft.errors = newTraceRing(tracesInBucket)
@@ -512,9 +513,7 @@ func copyFamilies() map[string]*familyTraces {
 	n := map[string]*familyTraces{}
 
 	familiesMu.Lock()
-	for f, trs := range families {
-		n[f] = trs
-	}
+	maps.Copy(n, families)
 	familiesMu.Unlock()
 
 	return n

internal/nettrace/trace_test.go

@@ -37,13 +37,13 @@ func TestLong(t *testing.T) {
 	tr.SetMaxEvents(100)
 
 	// First 90 events, no drop.
-	for i := 0; i < 90; i++ {
+	for i := range 90 {
 		tr.Printf("evt %d", i)
 	}
 	expectEvents(t, tr, 90)
 
 	// Up to 99, still no drop.
-	for i := 0; i < 9; i++ {
+	for i := range 9 {
 		tr.Printf("evt %d", i)
 	}
 	expectEvents(t, tr, 99)
@@ -57,7 +57,7 @@ func TestLong(t *testing.T) {
 	expectEvents(t, tr, 101)
 
 	// Add more events, expect none of them to exceed 101.
-	for i := 0; i < 9; i++ {
+	for i := range 9 {
 		tr.Printf("evt %d", i)
 		expectEvents(t, tr, 101)
 	}