behavior of noUncheckedIndexedAccess is inconsistent.

[13OnTheCode]

🔎 Search Terms

"noUncheckedIndexedAccess" "undefined"

🕗 Version & Regression Information

5.4.2

⏯ Playground Link

https://www.typescriptlang.org/play?noUncheckedIndexedAccess=true&exactOptionalPropertyTypes=false&noPropertyAccessFromIndexSignature=false#code/C4TwDgpgBAggTnKBeKBnYcCWA7A5gbQF0AoY0SKAFQEZlYF8AGEgehag4D0B+UgEwgBjADYBDONEEB7bOiji4ALnpxS02cCjBaKBU1bsOUHsSA

💻 Code

type Arr = string[]

type T1 = Arr[0]
//     ^?  type T1 = string

declare const arr: Arr

const t1 = arr[0]
//      ^?  const t1: string | undefined

🙁 Actual behavior

behavior of noUncheckedIndexedAccess is inconsistent.

🙂 Expected behavior

The type obtained from type T1 = Arr[0] should be string | undefined.

Additional information about the issue

No response

[RyanCavanaugh]

Intentional; see discussion on this at #39560

[MartinJohns]

Duplicate of #42471.

edit: awww, too slow.