microsoft / microsoft/TypeScript

ReferenceError caused by const enum

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Bug Domain: enum Help Wanted
Dominant language
Go
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Description

Bug Report

🔎 Search Terms
  • const enum
🕗 Version & Regression Information
  • This is a runtime crash
  • This changed between versions 4.4.4 and 4.3.5
  • This is the behavior in every version I tried, and I reviewed the FAQ for entries about _________
  • I was unable to test this on prior versions because _________
⏯ Playground Link

Playground link with relevant code

💻 Code
const enum Foo {
    a = 1,
}

console.log(Foo["1"])
🙁 Actual behavior
console.log(Foo["1"]);
🙂 Expected behavior
console.log("a");

or report error.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the issue from the linked TypeScript Playground using the const enum example, then inspect the compiler path that emits the shown JavaScript. Compare the generated output with the expected reverse lookup behavior and ensure completion either reports an error or prevents the runtime ReferenceError.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, typescript
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
42/100

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