In a modular context, when an enum uses another-enum as its value, the enum be Reverse mappings

[shaddollxz]

🔎 Search Terms

"enum" "revers mappings" "module"

🕗 Version & Regression Information

typescript: 5.2.2
vite: 4.4.7 or nextjs: 13.5.6
react: 18.2.0
vue: 3.3.4

⏯ Playground Link

https://codesandbox.io/s/amazing-mcclintock-j6s48r?file=/src/App.tsx

💻 Code

// enum.ts
export enum Map {
  A = 'a',
  B = 'b',
}
// index.ts
import { Map } from './enum'
enum NewMap {
  KeyA = Map.A
}

console.log(NewMap) // { KeyA: "a", a: "KeyA" }

🙁 Actual behavior

NewMap is a reverse mappings enum

🙂 Expected behavior

NewMap not revers, like { keyA: 'a' }

Additional information about the issue

No response

[RyanCavanaugh]

#56153 (comment)

[fatcerberus]

Hmm, but that comment only says this would be an error under isolatedModules. Here, even without isolatedModules (where this will presumably continue to be allowed), it's emitting a reverse mapping for a string-valued member, which seems wrong.

[RyanCavanaugh]

Codesandbox appears to be using single-file transpile and thus should turn on isolatedModules. The whole-program tsc emit is correctly unidirectional.

[typescript-bot]

This issue has been marked as "Duplicate" and has seen no recent activity. It has been automatically closed for house-keeping purposes.