Incorrect nil copy

[alresvor]

https://go.dev/play/p/DwZgPX8HhBs

package main

import (
	"fmt"

	"golang.design/x/reflect"
)

type ListNode struct {
	Val  int
	Next *ListNode
}

func main() {
	n := ListNode{Val: 1}
	n2 := reflect.DeepCopy(n)
	fmt.Printf("%+v %+v\n", n, n2)
	fmt.Println(n2.Next.Val) // 0
}

n.Next is nil, but becomes &ListNode{} after the deep copy.

[changkun]

Interesting, perhaps the recursive processing was not correct engouth.

[alresvor]

最简单的:

	var n4 *ListNode
	n5 := reflect.DeepCopy(n4)
	fmt.Println(n4, n5) // <nil> &{0 <nil>}

[alresvor]

这里还有一个 deepCopy 的库，倒是没有这个问题，而且实现简单粗暴
https://github.com/darkgopher/darkness/blob/master/deepcopy.go

[changkun]

I don't yet have time to look deeper into this. Hence it is greatly welcome if there is a PR to fix this