Object.keys' returntype should be specified

[HomyeeKing]

Bug Report

when you get keys of some object by Object.keys, then assign value to it, will get an error like
Element implicitly has an 'any' type because expression of type 'string' can't be used to index type

🔎 Search Terms

🕗 Version & Regression Information

• This is a crash
• This changed between versions ______ and _______
• This is the behavior in every version I tried, and I reviewed the FAQ for entries about _________
• I was unable to test this on prior versions because _______

⏯ Playground Link

Playground link with relevant code

💻 Code

const obj = {a:1,b: 2}
for(const key of Object.keys(obj)){
  obj[key] = 3
}

🙁 Actual behavior

obj[key] will report error

🙂 Expected behavior

narrow Object.keys return type like

type Keys<T extends object> = (o:T) =>  UnionToTuple<keyof T>

maybe we coule implement UnionToTuple like thing

[jcalz]

Duplicate of #45390 and a bunch of others. (Also see #13298 for why there is no union-to-tuple) Did you search for existing issues?

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.

[HomyeeKing]

@jcalz yes I have searched and still no solution, just wanna get more attenion about this

[RyanCavanaugh]

This is the intended behavior and we're not changing it.