package main import ( "fmt" "reflect" ) type Fooer interface { Foo() } type Fooo struct{} func (f *Fooo) Foo() { if f == nil { fmt.Println("nil!!") } else { fmt.Println("not nil!!") } } func newFooer() Fooer { return &Fooo{} } func bar(f Fooer) { f.Foo() } func main() { // 型を代入したあとnilを入れても型情報は消えない z := &Fooo{} fmt.Println(reflect.TypeOf(z)) // *main.Fooo z = nil fmt.Println(reflect.TypeOf(z)) // *
![Goでオブジェクト生成の返り値にinterfaceを使うとnil Pointer Receiverができないという話 - Qiita](https://cdn-ak-scissors.b.st-hatena.com/image/square/1526fab5297b7fac586e384f9633c1ac9bb770cf/height=288;version=1;width=512/https%3A%2F%2Fqiita-user-contents.imgix.net%2Fhttps%253A%252F%252Fcdn.qiita.com%252Fassets%252Fpublic%252Farticle-ogp-background-412672c5f0600ab9a64263b751f1bc81.png%3Fixlib%3Drb-4.0.0%26w%3D1200%26mark64%3DaHR0cHM6Ly9xaWl0YS11c2VyLWNvbnRlbnRzLmltZ2l4Lm5ldC9-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%26mark-x%3D142%26mark-y%3D57%26blend64%3DaHR0cHM6Ly9xaWl0YS11c2VyLWNvbnRlbnRzLmltZ2l4Lm5ldC9-dGV4dD9peGxpYj1yYi00LjAuMCZoPTc2Jnc9NzcwJnR4dD0lNDB0MTA0NzEmdHh0LWNvbG9yPSUyMzIxMjEyMSZ0eHQtZm9udD1IaXJhZ2lubyUyMFNhbnMlMjBXNiZ0eHQtc2l6ZT0zNiZ0eHQtYWxpZ249bGVmdCUyQ3RvcCZzPTU0ZTE5ZWNiMDk5MDAyYzFmNTE4MWI0MmQ2MWZlNTAz%26blend-x%3D142%26blend-y%3D436%26blend-mode%3Dnormal%26txt64%3DaW4gTWVyY2FyaQ%26txt-width%3D770%26txt-clip%3Dend%252Cellipsis%26txt-color%3D%2523212121%26txt-font%3DHiragino%2520Sans%2520W6%26txt-size%3D36%26txt-x%3D156%26txt-y%3D536%26s%3Db788b5cfc70e400caca0c6c28cae26ea)