Doesn't correctly handle T types.

[ToborWinner]

This code seems to cause issues, I had to manually fix my guard check.

export interface BaseVideo<T extends VideoType = VideoType> {
    type: T;
    data: T extends "MOTIVATIONAL" ? MotivationalVideoData :
        T extends "SHOWER_THOUGHTS" ? ShowerThoughtsVideoData :
        T extends "QUIZ" ? QuizVideoData :
        T extends "QUIZ_SHORT" ? QuizShortVideoData :
        T extends "SUMMARY" ? any : never;
}

(Yes isVideoType is included in the guards, and the other types not included in this code too)

Apart the data part, which is understandable if it gets it wrong, the guard checks if the type is equal to "T" and typescript gives me an error there.

[download13]

It looks like you're trying to make a discriminated union, that looks like a java base type?

type Video =
  | MotivationalVideo
  | ShowerThoughtsVideo
  ...

type MotivationalVideo = {
  type: 'MOTIVATIONAL'
  data: MotivationalVideoData
}

type ShowerThoughtsVideo = {
  type: 'SHOWER_THOUGHTS'
  data: ShowerThoughtsVideoData
}

...

If it's possible to use that pattern in your codebase, you can likely generate guards for the constituent types and the union.

[rhys-vdw]

Please provide expected output.

Although you should know that whatever it is, it's extremely unlikely to be easy to support.