Repository: TypeScript
Issue: Template decorators.
Labels: Needs Investigation

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For npm: `typescript@next`
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**TypeScript Version:**  3.7.5

<!-- Search terms you tried before logging this (so others can find this issue more easily) -->
**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**

```ts
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

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