Promise<number> is Promise<string>

[falsandtru]

Is there any way to resolve the following weak typings?

type A = boolean;
type AB = boolean|number;
class C<T> {
    g: T;
}

var c: C<A> = <C<AB>>null; // error
var p: PromiseLike<A> = <PromiseLike<AB>>null; // should be an error

[mhegazy]

not that i can think of.

[falsandtru]

TypeScript said, Promise<number> is Promise<string>.

var s: PromiseLike<number | string> = <PromiseLike<string>>null;
var n: PromiseLike<number> = <PromiseLike<number | string>>s; // should be an error

[RyanCavanaugh]

Title is not accurate:

let x: PromiseLike<string>;
let y: PromiseLike<number>;
x = y; // Error

The behavior around string|number happens because of function parameter bivariance; see any number of issues around this already, e.g. #222