package main

type Hello interface {
	hello() string
}

type HelloImpl struct {
}

func (*HelloImpl) hello() string {
	return "hello"
}

type HelloNotImpl struct {
}

func main() {
	var _ Hello = new(HelloImpl)
	var _ Hello = (*HelloImpl)(nil)

	// var _ Hello = new(HelloNotImpl)
	// var _ Hello = (*HelloNotImpl)(nil)

}

推荐使用
var _ Hello = (*HelloImpl)(nil)