Static member added by class decorator is not emitted in types

[yoursunny]

🔎 Search Terms

class decorator, static member

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about decorators

⏯ Playground Link

https://www.typescriptlang.org/play?ts=5.5.0-dev.20240226#code/GYVwdgxgLglg9mABAQwCaoPrADwBUB8AFFMgE4DmAplAFyJiUDuhAlALz64A0i0AHnWRgAnizqEGzdpxaIAZIgDeiYONkd6IALYAjSqUQBfJQChEiUtRCkkAeR0ArStAB0yAM7uY5MMTJUoHmVVRFYOAEYjFhNDExMAATRMYBMIABsPd0QAZVNY1IR3ODTKFzS4ckJsl2BWFgBuEyA

💻 Code

function add_f<T>(target: new()=>T, ctx: any): (new()=>T) & { f: () => number } {
  return Object.assign(target, { f: ()=>1 })
}

@add_f
class S {
}

console.log(S.f());

🙁 Actual behavior

.d.ts emits:

declare class S {
}

Errors include:

Property 'f' does not exist on type 'typeof S'.

Runtime behavior is correct: it prints 1.

🙂 Expected behavior

.d.ts emits:

declare class S {
  static f(): number;
}

No error.

Additional information about the issue

No response

[fatcerberus]

Looks like #4881