import (
	"bytes"
	"math"
	"runtime"
	"runtime/debug"
	"sync"
	"sync/atomic"
	"testing"
	_ "unsafe"
)

// We assume that the Once.Do tests have already covered parallelism.

func TestOnceFunc(t *testing.T) {
	calls := 0
	f := sync.OnceFunc(func() { calls++ })
	allocs := testing.AllocsPerRun(10, f)
	if calls != 1 {
		t.Errorf("want calls==1, got %d", calls)
	}
	if allocs != 0 {