The spec doesn't describe the newest cast semantics

[dimvar]

When casting from a type A to a type B, the spec says that either A is assignable to B, or B is assignable to A. But the playground allows something more general: in some cases, as long as A and B have a common subtype, it doesn’t warn. The next example is valid.

function f(x: number | string) {
    return <number | boolean>(x);
}

The playground uses the comparable relation. The spec should be updated to include it.

[RyanCavanaugh]

The spec is now an "archived" artifact and we won't be tracking defects against it anymore.