Target signature provides too few arguments. Expected 1 or more, but got 0

[seafronthu]

🔎 Search Terms

ts(2345)

🕗 Version & Regression Information

• This is a crash
• This changed between versions 5.4.5__ and _______
• This changed in commit or PR _______
• 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

No response

💻 Code

interface RegisterFnDepINF  {
  close: Array<() => void>
  error:  Array<() => void>
  message: Array<(msg: string) => void>
  open:  Array<() => void>
}
type EventType = keyof RegisterFnDepINF
class WebSocketCommunication {
  #registerFnDep: RegisterFnDepINF = {
      close: [],
      error: [],
      message: [],
      open: []
    }
    $on<T extends EventType>(type: T, callback:  RegisterFnDepINF[T][number]) {
      this.#registerFnDep[type].push(callback)
    }
// errors
// Argument of type '(() => void) | (() => void) | ((msg: string) => void) | (() => void)' is not assignable to parameter of type '() => void'.Type '(msg: string) => void' is not assignable to type '() => void'.Target signature provides too few arguments. Expected 1 or more, but got 0.
}

🙁 Actual behavior

Argument of type '(() => void) | (() => void) | (() => void) | ((msg: string) => void)' is not assignable to parameter of type '() => void'.
Type '(msg: string) => void' is not assignable to type '() => void'.
Target signature provides too few arguments. Expected 1 or more, but got 0.

🙂 Expected behavior

not error

Additional information about the issue

interface RegisterFnDepINF  {
  close: Array<() => void>
  error:  Array<() => void>
  message: Array<(msg: string) => void>
  open:  Array<() => void>
}
type EventType = keyof RegisterFnDepINF
class WebSocketCommunication {
  #registerFnDep: RegisterFnDepINF = {
      close: [],
      error: [],
      message: [],
      open: []
    }
    $on<T extends EventType>(type: T, callback:  RegisterFnDepINF[T][number]) {
      this.#registerFnDep[type].push(callback)
    }
}

https://www.typescriptlang.org/play/?#code/JYOwLgpgTgZghgYwgAgEoQObAM6SgMRABEIAHASQDl9lkBvAKFoQBsB7bCALmQEEoocAJ4AeABQBKZAF4AfMgBubYABNZTZNChsoPPgOHipcxcrUaAthGzY4GbvsGixF7Bh64ooDMflLV6rRspBAgevxORjJ+ZuoAvgxgQiHIAKIKoWAAKsko0sgA1hBCbDBomDh4hCQU1AyscDbIAOoQAEYAymwIRWAAwmwWFgCuIMAIcGDAbCD0GgDEUBW40NVkPOhYKwTEZFQ0+Yy0x8isHA4A2gC6ADQaJ1o6PNd3J7RWNnaXt-fHwaHPK6-BInAAkMxEWU0AA9ICAVNg0hlwDkQrIxEkQjwsjdTnAWCw2ogCnpNpVVrtavgLlkrhcQMMLG1oFcpEc3mAABY4AB0i2WVUpF0xECuPNIw2wnLEEwJRJ6EmBDDiQA
version: 5.4.5

[MartinJohns]

You wrongly assume that T extends EventType means that T can only be one specific key, but it can also be a union of keys. This is very known design limitation.

This is an example that demonstrates the problem:

// Passing type "message", but callback without an argument
$on<"close" | "message">("message", () => {})

You would need #27808 for this.

[typescript-bot]

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