Object literal in async function should only specify known properties

[ghost]

TypeScript Version: nightly (2.2.0-dev.20161121 )

Code

function foo(): { x: number } {
    return { x: 1, y: 2 };
}

async function bar(): Promise<{ x: number }> {
    return { x: 1, y: 2 };
}

Expected behavior:

Both are errors.

Actual behavior:

Only the first is an error.

[yortus]

A third variant that currently gives no errors:

function baz(): Promise<{ x: number }> {
    return Promise.resolve({ x: 1, y: 2 });
}

That's semantically identical to bar. So if bar should be an error, what about baz?

[mhegazy]

the last one is not related. the last one is about using the return type as an inference location, see #11152

[Andarist]

This one works OK today, so the issue could be closed :) cc @RyanCavanaugh