No type checking when generic class/interface do not have any properties and '{}' is used as generic type variable

[alhugone]

TypeScript Version: 2.1.1 / nightly (2.2.0-dev.201xxxxx)
with strictNullChecks

Code

//example 1:
interface MyInterface<T> {
    someMethod: (param1: T) => MyInterface<T>;
}

class MyInterfaceImpl<T> implements MyInterface<T>{
    someMethod = function (param1: T) {
        return new MyInterfaceImpl<T>();
    }
}

let getMyInterface: () => MyInterface<{}> = () => { return new MyInterfaceImpl<{}>(); };

let getString: () => MyInterface<string> = getMyInterface;
let getDate: () => MyInterface<Date> = getMyInterface;
let getNumber: () => MyInterface<number> = getMyInterface;


//example 2:
let getPromise1: () => Promise<{} | number> = () => { return Promise.resolve({}) };

let getStringP1: () => Promise<string> = getPromise1
let getDateP1: () => Promise<Date> = getPromise1
let getNumberP1: () => Promise<number> = getPromise1


//example 3:
let getPromise2: () => Promise<{} | number| undefined | null> = () => { return Promise.resolve({}) };

let getStringP2: () => Promise<string> = getPromise2
let getDateP2: () => Promise<Date> = getPromise2
let getNumberP2: () => Promise<number> = getPromise2

Expected behavior:
Should not compile with error like 'Type () =>Promise<X> is not assignable to type '() => Promise<Y>'.
Actual behavior:
Compiles.

[alhugone]

#14298 - I think it is related.

[mhegazy]

Duplicate of #13970