[Bug]: TypeScript string enum members based on an imported enum should not have a reverse mapping

[MohammadYounes]

💻

• Would you like to work on a fix?

How are you using Babel?

babel-loader (webpack)

Input code

// enum.ts
export enum MainEnum {
  itemA = 'A',
  itemB = 'B',
  itemC = 'C'
}
export enum SameFileSubEnum {
  itemA = MainEnum.itemA,
  itemB = MainEnum.itemB
}

//another-file.ts
import { MainEnum } from './enum'
export enum AnotherFileSubEnum {
  itemA = MainEnum.itemA,
  itemB = MainEnum.itemB
}

//main.ts
import { SameFileSubEnum } from './enum'
import { AnotherFileSubEnum } from './another-file'
console.log('SameFileSubEnum [No Reverse Mapping]', SameFileSubEnum)
console.log('AnotherFileSubEnum [Reverse Mapping Applied]', AnotherFileSubEnum)

Configuration file name

.babelrc

Configuration

{
  "presets": [["@babel/preset-env"], "babel-preset-typescript-vue3", "@babel/preset-typescript"],
  "plugins": [
    "@babel/transform-typescript",
    "@babel/plugin-transform-async-to-generator",
    "@babel/proposal-object-rest-spread",
    ["@babel/plugin-proposal-decorators", { "legacy": true }],
    ["@babel/plugin-proposal-class-properties", { "loose": true }],
    ["@babel/plugin-proposal-private-property-in-object", { "loose": true }],
    ["@babel/plugin-proposal-private-methods", { "loose": true }],
    "@babel/plugin-syntax-dynamic-import"
  ]
}

Current and expected behavior

Current

Expected
Both enums to be the same without reverse mapping

Environment

  System:
    OS: Windows 11 10.0.22631
  Binaries:
    Node: 14.21.3 - C:\Program Files\nodejs\node.EXE
    npm: 6.14.18 - C:\Program Files\nodejs\npm.CMD
  npmPackages:
    @babel/core: ^7.23.7 => 7.23.9
    @babel/plugin-proposal-decorators: ^7.23.9 => 7.23.9
    @babel/plugin-syntax-dynamic-import: ^7.8.3 => 7.8.3
    @babel/plugin-transform-async-to-generator: ^7.23.3 => 7.23.3
    @babel/plugin-transform-class-properties: ^7.23.3 => 7.23.3
    @babel/plugin-transform-object-rest-spread: ^7.23.4 => 7.23.4
    @babel/plugin-transform-private-methods: ^7.23.3 => 7.23.3
    @babel/plugin-transform-private-property-in-object: ^7.23.4 => 7.23.4
    @babel/preset-env: ^7.23.8 => 7.23.9
    @babel/preset-typescript: ^7.23.3 => 7.23.3
    babel-loader: ^9.1.3 => 9.1.3
    babel-plugin-add-module-exports: ^1.0.4 => 1.0.4
    babel-plugin-dynamic-import-node: ^2.3.3 => 2.3.3
    babel-preset-typescript-vue: ^1.1.1 => 1.1.1
    babel-preset-typescript-vue3: ^2.0.17 => 2.0.17
    webpack: ^5.89.0 => 5.90.0

Possible solution

No response

Additional context

No response

[babel-bot]

Hey @MohammadYounes! We really appreciate you taking the time to report an issue. The collaborators on this project attempt to help as many people as possible, but we're a limited number of volunteers, so it's possible this won't be addressed swiftly.

If you need any help, or just have general Babel or JavaScript questions, we have a vibrant Slack community that typically always has someone willing to help. You can sign-up here for an invite.

[MohammadYounes]

Sample https://playcode.io/1743524

[nicolo-ribaudo]

Let's wait for microsoft/TypeScript#56153 to be solved before changing Babel's behavior here.