Quick info doesn't show index signature information when it's declared on the interface with a base type

[Andarist]

Bug Report

🔎 Search Terms

quick info index signature base type interface

🕗 Version & Regression Information

• This is the behavior in every version I tried

⏯ Playground Link

Playground link with relevant code

💻 Code

interface A {
  [k: string]: number;
}

declare const a: A;
a.test = 10; // quickInfo: (index) A[string]: number

interface P {}
interface B extends P {
  [k: string]: number;
}
declare const b: B;
b.test = 10; // quickInfo: number

🙁 Actual behavior

The first quick info has an index symbol information in it but the second on doesn't.

🙂 Expected behavior

I expect both to disp;ay roughly the same information