Failure to narrow conditional type after guard

[schuelermine]

Bug Report

🔎 Search Terms

conditional type guard

🕗 Version & Regression Information

This seems to not be a regression at all.

⏯ Playground Link

Playground link with relevant code

💻 Code

type X<T> = A<T> | B<T>
type A<T> = {type: "a", value: T}
type B<T> = {type: "b", value: T}
type R<T,Y extends X<T>> = Y extends B<T> ? T : void
function f<T,Y extends X<T>>(y: Y): R<T,Y> {
    if (y.type === "b") {
        return y.value
    } else return
}

🙁 Actual behavior

TS complains about y.value and else return.

🙂 Expected behavior

They should be accepted.

[jcalz]

Duplicate of #33912

[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.