Correct typing of CaseReducerWithPrepare

[medihack]

For some shared functionality, I need to create a function that creates a reducer function.

This works fine in case of a minimal example CaseReducer and the state is correctly inferred:

export const withFoo =
  <S, P extends PayloadAction<any>>(recipe: (state: Draft<S>) => void): CaseReducer<S, P> =>
  (state) => {
    recipe(state)
  }

But I can't get the same to work with a CaseReducerWithPrepare (which is what I need):

export const withFoo = <S, P extends PayloadAction<any>>(
  recipe: (state: Draft<S>) => void
): CaseReducerWithPrepare<S, P> => {
  return {
    reducer(state) {
      recipe(state)
    },
    prepare(payload: any) {
      return { payload }
    },
  }
}

When I try to add the above to my slice by

...
reducers: {
  foo: withFoo((state) => {}),
...
}

I get the following error for foo:

Type 'CaseReducerWithPrepare<unknown, PayloadAction<any, string, any, any>>' is not assignable to type 'CaseReducer<LanguagesState, { payload: any; type: string; }> | CaseReducerWithPrepare<LanguagesState, PayloadAction<any, string, any, any>>'.
  Type 'CaseReducerWithPrepare<unknown, PayloadAction<any, string, any, any>>' is not assignable to type 'CaseReducerWithPrepare<LanguagesState, PayloadAction<any, string, any, any>>'.
    Type 'unknown' is not assignable to type 'LanguagesState'.ts(2322)

It seems that with CaseReducer the state is inferred correctly, but with CaseReducerWithPrepare it isn't.

[medihack]

Just found out that it seems to be a known problem, see #1288