JSDoc apparently taking effect in TypeScript code

TypeScript Version: nightly (2.3.0-dev.20170320)

Code

import {} from "fs"; // Make it a module

class X {
    foo: Y;
    /** @typedef {function} Y */
    bar: number;
}

class Y {
    baz: number;
}

const x = new X();
x.foo.baz;

Expected behavior:

No error.

Actual behavior:

src/a.ts(14,7): error TS2339: Property 'baz' does not exist on type '() => any'.

[Jessidhia]

More strangely, it's a @typedef, which makes no sense in that position even when used as a salsa jsdoc o_O