Duplicated documentation from common properties in union types

[SimonSiefke]

TS template added by @mjbvz

TypeScript Version: 3.8.0-dev.20191116

Search Terms:

• suggest / suggestions
• jsdoc

---

• VSCode Version: 1.41.0-insider
• OS Version: Ubuntu 19.04

Steps to Reproduce:

1. Create a typescript union type with descriptions for each type, e.g.

export type DocumentFilter = {
    /** A language id, like `typescript`. */
    language: string;
    /** A Uri [scheme](#Uri.scheme), like `file` or `untitled`. */
    scheme?: string;
    /** A glob pattern, like `*.{ts,js}`. */
    pattern?: string;
} | {
    /** A language id, like `typescript`. */
    language?: string;
    /** A Uri [scheme](#Uri.scheme), like `file` or `untitled`. */
    scheme: string;
    /** A glob pattern, like `*.{ts,js}`. */
    pattern?: string;
} | {
    /** A language id, like `typescript`. */
    language?: string;
    /** A Uri [scheme](#Uri.scheme), like `file` or `untitled`. */
    scheme?: string;
    /** A glob pattern, like `*.{ts,js}`. */
    pattern: string;
};

2. When using intellisense, it shows duplicate descriptions

Does this issue occur when all extensions are disabled?: Yes

[lucashtc]

I've had this problem because of more than one installed extension that makes this work

[SimonSiefke]

For me it reproduces consistently in VSCode and VSCode Insiders with extensions disabled.

[nmain]

This reproduces in the playground as well

[AnyhowStep]

Related? (This one was fixed already, though)

#32708

[minestarks]

In theory the doc comment above for each declaration of language could be different. What would we want to show in that case?

In this case since they're exactly the same we could probably collapse them into one.