Can't extend WeakMap in type-checked JS files

[zombie]

🔎 Search Terms

WeakMap constructors return type JSDoc

🕗 Version & Regression Information

• This is the behavior in every version I tried. I opened Can't extend WeakMap in type-checked JS files #23551 5 years ago, but it got closed in error, as it was never fixed.

⏯ Playground Link

https://www.typescriptlang.org/play?filetype=js#code/MYGwhgzhAEDCD2J4CcCyYAO0CmAPALtgHYAmMA6tmANbpYDeAUNNMPERPsgK7D4oAKAJTQmLFhG4ZsyYQG5m0AL6MlQA

💻 Code

class ColorMap extends WeakMap {
  constructor() {
    super();
  }
}

🙁 Actual behavior

color.js(1,24): error TS2510: Base constructors must all have the same return type.

I tried a few different workarounds, like adding Template (@template) generic params, or forcing types using Type (@type) JSDoc, but nothing seems to work.

🙂 Expected behavior

No error.

Additional information about the issue

No response

[MartinJohns]

but it got closed in error, as it was never fixed.

It was fixed, but then subsequently broken by #28052 (as mentioned in this comment). ExE Boss (@ExE-Boss) opened the PR #41635, but it was never completed.

[fatcerberus]

Looks like an exact duplicate of #23551?

[MartinJohns]

Bruce Pascoe (@fatcerberus) He mentioned that issue in the "Version & Regress Information" section. The issue was fixed, but then broken and not fixed again: #56664 (comment)

[ExE-Boss]

I’ve now opened #56713 (which is the result of rebasing and fixing #41635).