Expando properties of function declarations don't get emitted in .d.ts emit

[DanielRosenwasser]

export function Foo({ x, y, z }: { x: number, y: string, z: boolean }) {
}

Foo.defaultProps = {
    x: 0,
};

Foo.defaultProps = {
    y: ""
};

Expected

Either

export declare function Foo({ x, y, z }: {
    x: number;
    y: string;
    z: boolean;
}): void;

export namespace Foo {
    export let defaultProps: { y: string };
}

or

export declare function Foo({ x, y, z }: {
    x: number;
    y: string;
    z: boolean;
}): void;

export namespace Foo {
    export let defaultProps: { x: number };
}

[sandersn]

Couple of notes:

1. Function and arrow expressions work fine, but not function declarations.
2. I think the emit should be of the form { (): void, p: number, ... } instead of a merge.
3. Multiple assigments to a property create a union type.

Combining (2) and (3), I would expect

export declare const Foo: {
  ({ x, y, z }: { x: number, y: string, z: boolean }): void;
  defaultProps: { x: number, y?: string } | { x?: number, y: string }
}