if f == nil {
		panic("missing callback function")
	}
	f()
}

func testCallback(t *testing.T) {
	var x = false
	nestedCall(func() { x = true })
	if !x {
		t.Fatal("nestedCall did not call func")
	}
}

func testCallbackGC(t *testing.T) {
	nestedCall(runtime.GC)
}

func testCallbackPanic(t *testing.T) {
	// Make sure panic during callback unwinds properly.
	if lockedOSThread() {

pkg syscall (windows-amd64), type TCPKeepalive struct, OnOff uint32
pkg syscall (windows-amd64), type TCPKeepalive struct, Time uint32
pkg testing, method (*B) RunParallel(func(*PB))
pkg testing, method (*B) SetParallelism(int)
pkg testing, method (*PB) Next() bool
pkg testing, type PB struct