Slice replication problem

[w22296437978]

type Dto struct {
	Name string
}

func main() {
	list1 := []Dto{{"你好"}}
	list2 := []Dto{}

	copier.Copy(&list2, &list1)
	fmt.Printf("list2 length = %d\r\n", len(list2)) // 1

	list2 = []Dto{}
	list1Interface := method(list1)
	copier.Copy(&list2, &list1Interface)
	fmt.Printf("list2 length = %d\n", len(list2)) // 0 ???

	list2 = []Dto{}
	list1Interface = method(list1)
	copier.Copy(&list2, list1Interface)
	fmt.Printf("list2 length = %d\n", len(list2)) // 1 ???
}

func method(a interface{}) interface{} {
	return a
}