Skip to content

Literal tested as key of a certain type cannot be used as an index typeΒ #57109

Open
@ghostinpeace

Description

@ghostinpeace

πŸ”Ž Search Terms

"literal", "extends", "keyof", "cannot be used to index type", "conditional"

πŸ•— Version & Regression Information

Versions: ^5.0 (regression)

⏯ Playground Link

https://www.typescriptlang.org/play?ts=5.3.3&ssl=7&ssc=54&pln=1&pc=1#code/C4TwDgpgBAKlC8UDeBYAUFKBrAXFAziALYBGA9gDYA06mZwAFhAE57mUQCGAdlVAPT8oPek2bYIIAhAhF8UZhACOAVwCWigCZQAZmXGNoJFQHMowMsLCROzdAF906QbHDQA5ACIsn91ADGPNz0UCTQKvgQ2pzyPFBq3JoQAB7mbgB0ABQATACsAMwAHACU6KCQUADCCFDuWH4pwBCJ8liSZDqwUAD8sADade4AulB43BAAbiwA3AJCPCBAA

πŸ’» Code

type T = {
  k: symbol,
  other: boolean, // another key seems required for the bug to appear
}

// Type '"k"' cannot be used as an index type.(2538)
type C = 'k' extends keyof T ? T['k'] : never; // any

πŸ™ Actual behavior

An error is produced in the positive clause of the conditional type.
The resulting type is incorrect.

πŸ™‚ Expected behavior

No error.

Additional information about the issue

No response

Metadata

Metadata

Assignees

No one assigned

    Labels

    BugA bug in TypeScriptHelp WantedYou can do this

    Type

    No type

    Projects

    No projects

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions