断言后是copy还是refer.go

package main

import "fmt"

type in5 interface {
}
type st struct {
	x int
}

func main() {
	//是复制
	var i1 in5 = st{1}
	s1, ok := i1.(st)
	if ok {
		//...
	}
	s1.x = 10
	fmt.Println(i1, s1)
}