Optional parameter - assignment problem

[lluzak]

Problem comes from react-redux package when using ```connect`` function.

TypeScript Version: 2.6.2

Code

interface F {
  a?: number;
}

interface P {
  a?: number;
}

const u: P = { a: undefined };
const v = { a: u.a };

class C extends React.Component<F, {}> {
  constructor(p: F) {
    super(p);
  }

  render() {
    return <div>Hello</div>;
  }
}

interface IGC<Y> {
  <P extends Y>(component: React.ComponentClass<P>): React.ComponentClass<P>;
}

interface IGB<K extends any = any> {
  <K>(p: K): IGC<K>;
}

const gb: IGB = p => {
  return function(Componentklass) {
    return Componentklass;
  };
};

let y = gb(v);
y(C);

Expected behavior:

Allow to assign optional property into it equivalent number | undefined

Actual behavior:

    TS2345: Argument of type 'typeof C' is not assignable to parameter of type 'ComponentClass<{ a: number | undefined; }>'.
        Type 'C' is not assignable to type 'Component<{ a: number | undefined; }, ComponentState>'.
            Types of property 'props' are incompatible.
                  Type 'Readonly<{ children?: ReactNode; }> & Readonly<F>' is not assignable to type 'Readonly<{ children?: ReactNode; }> & Readonly<{ a: number | undefined; }>'.
                          Type 'Readonly<{ children?: ReactNode; }> & Readonly<F>' is not assignable to type 'Readonly<{ a: number | undefined; }>'.
                                    Property 'a' is optional in type 'Readonly<{ children?: ReactNode; }> & Readonly<F>' but required in type 'Readonly<{ a: number | undefined; }>'.

[j-oliveras]

Duplicate of #12400? (seams like will be solved into typescript 2.8)