https://github.com/DefinitelyTyped/DefinitelyTyped/pull/53633

[icecream17]

I'm super tired of debugging today.^{Feel like I have the most complicated bugs in the world}
I'll update this later.^Sorry

(See DefinitelyTyped/DefinitelyTyped#53633 (comment) for now)

Bug Report

🔎 Search Terms

intersection
pick / setState

This issue is similar: #44315
I found this: #28080 but it's different since the first line in the code below seems to work. But the issue code doesn't work? Weird.

🕗 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 code below

💻 Code

// React setState handler is typed like this:
function setState<State, Props, K extends keyof State> (
    state: 
        ((prevState: Readonly<State>, props: Readonly<Props>) => (Pick<State, K> | State | null))
      | (Pick<State, K> | State | null),
    callback?: () => void
) {}

type ThisState = { a: number, b: number }

setState({ a: 7 }) // ok
setState(() => ({ a: 7 })) // ok
setState((prevState: ThisState) => Math.random() > 0.5 ? prevState : {}) // ok
setState((prevState: ThisState) => Math.random() > 0.5 ? prevState : { a: 7 }) // error

🙁 Actual behavior

The last call has an error

🙂 Expected behavior

No error

[MartinJohns]

You forgot to fill out the issue template.

[icecream17]

screenshot

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I didn't forget, I just procrastinated. It's now filled out

[RyanCavanaugh]

Everything here is proceeding according to the declaration of the function. I don't see any defect being demonstrated here.

[icecream17]

I don't understand...
If { a: 7 } works and prevState | {} works then why not prevState | { a: 7 }?

[typescript-bot]

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

[icecream17]

Wait, no one responded to my question, what should I do?

Update: I realized something, nevermind, the close was valid