Primitives are assignable to Partial<T>

[Eyas]

TypeScript Version: Since at least 2.5.3 (repros in 2.7.0)

Code

const v: Partial<Window> = 5;

Expected behavior: Compilation fails saying 5 is not assignable to Partial.
Actual behavior: Compiles.

More thoughts:

While {} is assignable to Partial types, types which have no overlap in properties are not. This is helpful in catching many errors. As an extension of that, I think primitives such as number and string should not be assignable to Partials.

[RyanCavanaugh]

Previously #14224

[Eyas]

I did see that, but I think given the work done on weak type detection in TS 2.4. Hope you agree!