ts2536 thrown when use key remapping to filter out some keys

[gulewei]

Bug Report

🔎 Search Terms

key remapping
ts2536

🕗 Version & Regression Information

• This is a crash
• v4.3.5

⏯ Playground Link

Playground link with relevant code

💻 Code

type Methods<T> = { [P in keyof T as T[P] extends Function ? P : never]: T[P] };
type H<T> = T[keyof Methods<T>]; // here it throws

🙁 Actual behavior

Type keyof Methods<T> cannot be used to index type T. (2536)

🙂 Expected behavior

key remapping in type Methods<T> dose not make new keys, only filter out some of it. I think it could be used to type T in this case.

[andrewbranch]

I agree, though type H<T> = Methods<T>[keyof Methods<T>] is a pretty straightforward workaround.