Forcing excess-property checking on variable passed to TypeScript function

Question

Is there a way to force excess-property checking to happen, not just for an inlined object literal but one that derives from a variable?

For example, suppos

Answer 1

I needed this to enforce an object shape in Redux.

I have combined the answer in this great article and Shannon's answer in this thread here. I think this gives a tiny bit more concise way to implement this:

export type StrictPropertyCheck = T extends TExpected
  ? Exclude extends never
    ? T
    : TError
  : TExpected

Here ^^ I put the T extends TExpected in the StrictPropertyCheck, that is all the difference actually but I thought linking the article above would help others landing on this thread.

Usage for redux action creator:

export type Credentials = {
  email: string
  password: string
}

export type StrictCreds = T &
  StrictPropertyCheck<
    T,
    Credentials,
    'ERROR: THERE ARE EXCESS PROPERTIES IN CREDENTIALS OBJECT'
  >

export type AuthActionType =
  | {
      type: AuthAction.LOGIN
      payload: StrictCreds
    }
  | { type: AuthAction.LOGOUT 

export const login = (credentials: StrictCreds): AuthActionType => {
  return {
    type: AuthAction.LOGIN,
    payload: credentials as Credentials,
  }
}