Object strict literal assigment checking is omitted for the empty type

[zpdDG4gta8XKpMCd]

in #3823

interface A {
}
var a : A = { // valid code, but expected a problem in 1.6, since x, y, z don't belong to A 
    x: 1,
    y: 2,
    z: 3
};

[danquirk]

Ryan had proposed a rule that would error here if A at least had some optional members, but not if it was empty. I'm not sure what the rationale was for not erroring against empty types as well: #3842

[RyanCavanaugh]

Lots of people use {} in place of any because they don't want accidental anys creeping in, but still want something that's assignable from anything. Erroring on object literals assigned to {} is kind of pointless because, if we did, there would be nothing valid you could have written -- if you really wanted a type that couldn't be assigned from any non-null/undefined value, void is there.

[zpdDG4gta8XKpMCd]

Are values of void now officially a part of the language? Thought they were leaving.

[RyanCavanaugh]

The void type isn't going anywhere. The only thing we've been warning people of using the crazy number|void thing to fake non-nullability.

[zpdDG4gta8XKpMCd]

Can's say I see your point:

The void type isn't going anywhere.

Fine, since it's just a type let's keep it. I was talking about values of type void which sort of don't make sense since void by definition represents a lack of value. The only type that doesn't have a value yet is assignable from null and undefined (what might this mean?).

warning people of using the crazy number|void thing

Why would you warn? With all what's above number|void seems 100% legit (void is just another type that, hm, has values, remember?). Although I agree as far as making sense it fails, just like the idea of a legit value of void does.

thing to fake non-nullability

Business sees value in it and wants it. I would not call it faking unless proven otherwise. If number|void gives hard feelings how about a memberless enum?

const enum Nothing {}

Ugh, Nothing | number don't play nice together, dang, lets go back to void.

[zpdDG4gta8XKpMCd]

just thought you guys might be interested https://github.com/aleksey-bykov/by-design-script/blob/master/README.md#literal-strictness