microsoft / microsoft/TypeScript

add an option to report an error when `Symbol.dispose`/`Symbol.asyncDispose` objects are used without the `using` keyword

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描述

### 🔍 Search Terms

dispose using error

### ✅ Viability Checklist

- [x] This wouldn't be a breaking change in existing TypeScript/JavaScript code
- [x] This wouldn't change the runtime behavior of existing JavaScript code
- [x] This could be implemented without emitting different JS based on the types of the expressions
- [x] This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
- [x] This isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
- [x] This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals

### ⭐ Suggestion

i was surprised to learn that using disposables without the `using` keyword are not reported as an error:

```ts
const foo = {
[Symbol.dispose]: () => {
console.log("disposed"); // never called
},
};

{
const bar = foo;
console.log(bar);
}
```

### 📃 Motivating Example

[the documentation compares it to python `with` statements](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-5-2.html#:~:text=that%2E-,You,scope). but the whole point of context managers is to enforce that an object is always properly cleaned up. if you forget to use `with`, then the object's setup is never run so its cleanup doesn't need to run either.

since this is not the case with the `using` keyword, it should be a type error to use it in an unsafe way

### 💻 Use Cases

i have an API that i need to log out of when i'm finished using it, otherwise the session remains active

```ts
const login = () => {
// ...
return {
[Symbol.asyncDispose]: () => {
// important cleanup code that MUST be run no matter what
}
}
}
```

in python i would do this with a context manager, and i'd be confident that the cleanup code would always be executed. it's not up to the caller to remember to use the `with` statement. however in typescript, the caller could easily do this by mistake:

```ts
const sesion = await login()
// cleanup code never gets called
```

this is extremely surprising behavior coming from a language with a similar feature. is this is intentional, the docs should have a clear warning that `Symbol.dispose` and `Symbol.asyncDispose` functions have no guarantee to actually be called.

贡献指南

打开贡献指南

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。

调研方向

未指定实现文件或测试。先从链接的 TypeScript 5.2 发布说明文档以及 issue 中的同步和异步示例开始,然后确定对于未使用 using 而使用的 disposable 对象,预期的诊断和选项行为。完成的标准是报告所要求的误用,同时不改变生成的 JavaScript。

由索引模型根据 Issue 内容生成。

评估

技术栈
typescript
领域
compilers
Issue 类型
功能
难度
5/5
预计耗时
一周以上
活跃度
冷清
描述清晰度
基本清楚
新手友好度
42/100

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