Time.AddDate()
AddDate()
func (t Time) AddDate(years int, months int, days int) Time

例:

t := time.Now()
fmt.Println(t)
t2 := t.AddDate(-3, 0, 0)
fmt.Println(t2)

输出(在Go Playground上尝试):

2009-11-10 23:00:00 +0000 UTC
2006-11-10 23:00:00 +0000 UTC