Template decorators.

TypeScript Version: 3.7.5

Search Terms: Decorators, Templates

I know decorators a experimental feature, so this issue is just to push it closer to production ready status.
Notice, I tried typescript version 3.8 beta in the playground.
For local check with tsc only two following flags are essential: "--experimentalDecorators --strict".

It seems like typescript cant pass complex props type. Instead of passing A | B, it just pass A. Using a more simple type A will not produce any errors.

Code

import { Component, ComponentClass } from "react"

const components = new Set<ComponentClass<any, any>>()

function dec<P, S>(component: ComponentClass<P, S>)
{
    components.add(component)
}

type Props = { x: number } & ( { y: number } | { z: number } )

@dec
class C extends Component<Props>
{
}

Expected behavior:
Everything works.

Actual behavior:
Following error:

Argument of type 'typeof C' is not assignable to parameter of type 'ComponentClass<{ x: number; } & { y: number; }, {}>'.
  Construct signature return types 'C' and 'Component<{ x: number; } & { y: number; }, {}, any>' are incompatible.
    The types of 'props' are incompatible between these types.
      Type '(Readonly<{ x: number; } & { y: number; }> & Readonly<{ children?: ReactNode; }>) | (Readonly<{ x: number; } & { z: number; }> & Readonly<{ children?: ReactNode; }>)' is not assignable to type 'Readonly<{ x: number; } & { y: number; }> & Readonly<{ children?: ReactNode; }>'.
        Type 'Readonly<{ x: number; } & { z: number; }> & Readonly<{ children?: ReactNode; }>' is not assignable to type 'Readonly<{ x: number; } & { y: number; }> & Readonly<{ children?: ReactNode; }>'.
          Property 'y' is missing in type 'Readonly<{ x: number; } & { z: number; }> & Readonly<{ children?: ReactNode; }>' but required in type 'Readonly<{ x: number; } & { y: number; }>'.(2345)

Playground Link:
http://www.typescriptlang.org/play/?experimentalDecorators=true&ts=3.8-Beta#code/JYWwDg9gTgLgBAbzgYQuCA7AphmAaFNSbXZAGwEMBnKuAXzgDMo04AiKLCgYxjYCh+3TFXjD0JGLQC8cbAHc4AZSwwAPKgk4Y5alTUUMATwKGjAPnMAKAJSDGAVwy9gmOABMs3NQAUCS63FibQAuQi1SShpff3M7BH44JLggzG0qADoKd3crVMk7OkEYIzAsOB8WMBlEOAAPMIwHEAAjLCh6OAAyOCtao0bmto6GAB9agC9B1vbOu34AAU9uISjaZDgsOpgcd3WiNNxfKqpzfgT+OiA

Related Issues:

Reproduce the provided example with tsc using --experimentalDecorators and --strict, then compare it with the linked TypeScript Playground using the 3.8 beta. Start from decorator type checking and the ComponentClass generic in the example. Done means determining whether the reported 2345 diagnostic is incorrect for the union props case and validating the expected behavior.