empty enum got undefined

[fixiabis]

Describe the bug

I am using typescript module augmentation for enum, but got error if enum is empty at the beginning (enum would be undefined)

Reproduction

https://stackblitz.com/edit/vitejs-vite-abyiyv?file=main.js&terminal=dev

Steps to reproduce

just check reproduction link, enum would be undefined after compilation

System Info

not so important

Used Package Manager

npm

Logs

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
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• The provided reproduction is a minimal reproducible example of the bug.

[stackblitz]

Start a new pull request in StackBlitz Codeflow.

• vitejs-vite-abyiyv (Open reproduction)

[sapphi-red]

For this input,

export enum Opcode {}

export function extendOpcode(key: string, value: string) {
  Object.assign(Opcode, { [key]: value });
}

TypeScript outputs (ts playground):

export var Opcode;
(function (Opcode) {
})(Opcode || (Opcode = {}));
export function extendOpcode(key, value) {
    Object.assign(Opcode, { [key]: value });
}

and esbuild outputs (esbuild try):

export var Opcode = /* @__PURE__ */ ((Opcode2) => {
})(Opcode || {});
export function extendOpcode(key, value) {
  Object.assign(Opcode, { [key]: value });
}

I don't find any bug in esbuild here. The code is working as expected (Opcode should be undefined).
If you think it's a bug, please report to TypeScript instead.

[fixiabis]

It looks like esbuild's bug, I'll report it to esbuild, Thanks 🙏

[sapphi-red]

Ah, I overlooked the Opcode = {} part 😅
Since the fix is likely to be released in esbuild 0.20.x, it won't be included in Vite 5.1.x (uses esbuild 0.19.x). It would be included in 5.2.x.

[fixiabis]

Ah, I overlooked the Opcode = {} part 😅 Since the fix is likely to be released in esbuild 0.20.x, it won't be included in Vite 5.1.x (uses esbuild 0.19.x). It would be included in 5.2.x.

Thank you for your information! 🙏