Typescript: Parameters with rest readonly array give never [duplicate]

Question

I am seeing a weird (maybe 🤷‍♂️) behavior of Parameters utility type. Given code:

const testFn = (...args: readonly number[]) => args;
type l = typeof testFn;
type e = Parameters<l>;

It doesn't change if I use ReadonlyArray<number> instead, though that is to be expected since they are synonyms.

Why does TypeScript say that type of e is never? This was tested on TypeScript v4.3.5. Link to the playground.

Answer 1

This is a known issue: Inference from rest parameters has strange inconsistent results #37193.