Generic class expression broken if duplicate constructor is removed

[JeanMeche]

Bug Report

🔎 Search Terms

Generic Class Express, constructor

🕗 Version & Regression Information

Tested on latest 4.8.4 & nightly

This has never worked.

⏯ Playground Link

Playground

💻 Code

type Foo<T> = {
  [S in keyof T]: T[S]
}

interface IFoo {
  new <T>(): Foo<T>;
  new <T>(): Foo<T>; // KO if removed
}

const Foo: IFoo = (class {
  constructor() { }
})

const foo = new Foo();

---

Edit
I seems, the 2nd constructor is actually disabling a corect error, this following code work well.

type Foo<T> = {
  [S in keyof T]: T[S]
}

type Bar = {
  bar: string;
}

interface IFoo {
  new (): Bar;
}

const Foo: IFoo = (class {
  bar: string = ''
})

🙂 Expected behavior

1. Why would the compiler trigger an error if the 2nd constructor is removed ?
2. The empty class doesn't satisfy the constructor signature

[JeanMeche]

This might actually be a dupe of #26631 and A. Hejlsberg gives a reason of why this happens in #50050