Override String function not works with anonymous struct param

[rsgok]

example code

func main() {
	a := A{
		Tag: "tag-A",
		Num: 1,
		InA: InA{
			Id:   100,
			Type: "test",
		},
	}
	spew.Dump(a)
}

type A struct {
	Tag string
	Num int
	InA
}

type InA struct {
	Id   int
	Type string
}

func (t InA) String() string {
	return t.Type
}

unexpected output

(main.A) test

[rsgok]

and if struct member not anonymous, go-spew works