Use a more specific type for mapped types

[OpportunityLiu]

I'm submitting a...

[ ] Regression 
[ ] Bug report
[X] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

class A {
    constructor(a: string) {}
}

class B {
    constructor(b: number) {}
}

class C extends IntersectionType(A, B) {
    constructor() {
        super();// <- hint `Type(...args: any[]): A & B` shown here
    }
}

I've checked the source code, found that for each mapped type, a new class with no constructor is created, and "base"(?) classes's constructor are never called.

Expected behavior

Add a new type

export type MappedType<T> = new () => T

as return type of mapped types.

Minimal reproduction of the problem with instructions

What is the motivation / use case for changing the behavior?

This can clearify the constuctor parameter of mapped types, implies that constructors of base classes will not be called.

Environment

Nest version: 7.1.3

 
For Tooling issues:
- Node version: XX  
- Platform:  

Others:

[kamilmysliwiec]

Would you like to create a PR for this issue @OpportunityLiu? :)

[OpportunityLiu]

I'll have a try in weekend.