__esDecorate transpiled code uses "Symbol" even of this is shadowed by a local variable

🔎 Search Terms

helper symbol tslib

🕗 Version & Regression Information

• This changed between versions 5.1.6 and 5.2.2

Tested via playground and reading its debug output.

⏯ Playground Link

https://www.typescriptlang.org/play/?ts=5.9.0-dev.20250617#code/GYVwdgxgLglg9mABMOcAiBTCcBOBDKXAClxgHMYw8AbAWQygAs4ATALkTzAE8AaRbGCgYAHlA5duASkQBvAL4AoRaIAOuKAOp4AzjsQBlbgFsARnGpyBCHVBwhoxGbMTzXygAIp0WXAVwqIuo4mhDaeojG3ADC4fqyiohJgrb2jjhEzoiJSbkpmgD6YBgA7kbGiAC8iMUlhibm1JkA3DnuSkA

💻 Code

function fooDecorator(originalMethod: any, context: any) {}

export class Symbol { constructor() { } }

@fooDecorator
export class myClass {
   constructor() { 
      const _newSym = new Symbol();
   }
}

🙁 Actual behavior

The generated js code for myClass contains

const _metadata = typeof Symbol === "function" && Symbol.metadata ? Object.create(null) : void 0;

Which will access my local variable Symbol instead of window.Symbol/globalThis.Symbol.

🙂 Expected behavior

The generated code should access globalThis.Symbol in any case or perhaps only if the file contains a local variable (from class, const or import) with a colliding name.

Additional information about the issue

I found this with an import { Symbol } from "./service"; call (roughly modelled via this Bug Workbench) but this should not change the main problem.

We started to use the class name Symbol in our code (and public API) since 2014.

Right now we circumvent this issue by using different names inside the local file via alias names in import/export
But this is hard to understand and maintain.

从链接的 TypeScript playground 开始，检查生成的 __esDecorate 代码中是否存在本地 Symbol 声明或导入。跟踪 decorator metadata helper 如何选择 Symbol 引用，然后验证生成的代码不再解析本地绑定，并且仍能处理所示的 decorator 示例。