Added Typescript casting support for oneOfType

[victorgarciaesgi]

This PR is targeted for oneOfType.

Problem before:

Before vue-types

props: {
   foo: { type: [String, Object] as PropType<RawLocation> }
}

With vue-types ☹️

With these changes, we can now cast the type we want and still have the default behaviour!

type RawLocation = string | { name: string }
const ctor = oneOfType([String, Object]) // Valid
const route = oneOfType<RawLocation>([String, Object]) // Valid

[victorgarciaesgi]

Also worth notting, it could be better if U and V could still be infered to check the liability of the casting, but Typescript is blocking us since 2016 microsoft/TypeScript#10571 😩

[dwightjack]

Thanks!

I've changed the base branch to ts-args-for-natives so that I can merge it and add the related documentation.

[dwightjack]

@victorgarciaesgi Sorry for commenting on a closed PR.

After merging, I found that these changes create some type issues with the .def() method:

const ctor = oneOfType([String, Object]) // Valid
ctor.def('hello') // Argument of type 'string' is not assignable to parameter of type 'StringConstructor | ObjectConstructor'

Any hint on how to fix it?

[victorgarciaesgi]

@dwightjack Oh shit sorry I will look at it right now!

[victorgarciaesgi]

@dwightjack I fixed it on this branch

[victorgarciaesgi]

Do you want me to make another PR?