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Roundtrip not possible when using identical array twice

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评估

难度
5/5
预计耗时
一周以上
新手友好度
35/100
Issue 类型
缺陷
描述清晰度
需要澄清
活跃度
冷清
技术栈
ruby
领域
backend

调研方向

首先重现 YAML.load(YAML.dump({ a: a, b: a })) 示例,并检查 Psych 中 YAML.load、YAML.dump 和别名处理的路径。该 issue 未指明文件或测试,也未定义是否应更改转储或加载行为,因此需要在实现之前确定验收标准。

由索引模型根据 Issue 内容生成。

描述

tl;dr:

require "yaml"
a = [1,2,3]
YAML.load(YAML.dump({ a: a, b: a }))
# raises 'Psych::Visitors::NoAliasRuby#visit_Psych_Nodes_Alias': Alias parsing was not enabled. To enable it, pass `aliases: true` to `Psych::load` or `Psych::safe_load`. (Psych::AliasesNotEnabled)

Long form

Hey there, today I noticed an error that surprised me quite a lot. Essentially as soon as you include the same array twice in a structure that you dump through Psych, it will not be loadable using a default YAML.load. You'd have to pass specific options to make it loadable.

The problem is that dump will generate YAML in the form:

---
:a: &1
- 1
- 2
- 3
:b: *1

This preserves the array identity for the hashes stored under a and b.

That's surprising to me. I'd have expected that if load disables certain YAML features by default, that dump would also only use those on an opt-in basis. Even worse: I don't see a setting documented that would allow me to disable the alias creation. The two fixes available to me right now:

  • enable alias deserialization (which I believed to be disabled by default for security considerations; though I fail to find a source for that now)
  • duplicate values in my dump input to avoid alias generation

Second solution shown in code:

YAML.load(YAML.dump({ a: a, b: a.dup }))
=> {a: [1, 2, 3], b: [1, 2, 3]}
主要语言
Ruby
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环境准备

  • 没有 Dockerfile 或 Docker Compose 文件
  • 没有 Pull Request 模板
  • 阅读贡献指南

从这里开始

  1. 先读完整个 Issue,再读项目的贡献指南。
  2. 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
  3. Fork 仓库,在一个分支上完成修改。
  4. 提交 Pull Request,并在描述里引用这个 Issue 编号。

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