`export` modifier on `enum` disables `This condition will always return * ts2845`

🔎 Search Terms

export enum ts2845

🕗 Version & Regression Information

5.4 doesn't flag it without the export modifier either.

⏯ Playground Link

https://www.typescriptlang.org/play/?target=99&module=0&ts=6.0.0-dev.20260416#code/KYDwDg9gTgLgBMAdgVwLZwIIBMCGYbBQDyyMYpAKgJ5jBwDeAUHJgAqsD6rGA4gKIAaZnG78AykIC+jRlmABjADY4odeREQBneDBrAAXJlz5CJMpT0z1W+AGsAloixwAvMN21XLl0bwFipOQw1LQAdBjsXLx8cAA+sb4mAebBeqGifGLCLAD0OSwFhUXFJaUUABb2mnDWWPYw9hpwAO72iopwOIrNOFTVqjDIUIhwAOQwUMjAo6EAFABMABwALACsAJTZcAD8Y4rAAGYwo1uGo1D2AOblxwDcQA

💻 Code

// remove `export` modifier 
export enum AdapterOutputType {
  APP_PAGE,
  PAGES,
}

declare const type: AdapterOutputType

const kind =
  type === AdapterOutputType.APP_PAGE || AdapterOutputType.PAGES
    //                                   ~ should be flagged with: This condition will always return 'true'.(2845)
    ? 'left'
    : 'right';

🙁 Actual behavior

No typechecking error

🙂 Expected behavior

ts2845 because the condition is always true.

Additional information about the issue

No response

首先复现链接的 TypeScript Playground 案例，然后比较 AdapterOutputType 带有和不带有 export 修饰符时的诊断行为。跟踪枚举成员比较的类型检查路径，并验证错误条件会收到 TS2845，同时不会为有效案例引入诊断。