Pick allows any computed properties of type number

[AlexGalays]

TypeScript Version: 2.1.5 and 2.2.0-dev.20170206

If we take the code meant to solve React's setState typings from here #12793

Code

function setState<T, K extends keyof T>(obj: T, state: Pick<T, K>) {
    for (let k in state) {
        obj[k] = state[k]
    }
}

interface Foo {
  a: string
  b: number
}

let foo: Foo = { a: "hello", b: 42 }

const someIndex = 8000
setState(foo, { [someIndex]: 'whatever' })

Expected behavior:
This should not compile. 8000 is not part of the keys of Foo

[AlexGalays]

Any chance this could make it for 2.3?

[RyanCavanaugh]

@ahejlsberg bug or something else going on here?

[AlexGalays]

Good news, this is now fixed in TS 2.6.1