Overload Typescript arrow function without causing error Duplicate identifier and Function implementation is missing or not immediately following

We use the following code to enable compile check and IntelliSense for our redux reducers:

It is in a .ts file and not .tsx (https://stackoverflow.com/a/45576880/3850405)

export function typedAction<T extends string>(type: T): { type: T };
export function typedAction<T extends string, P extends any>(
    type: T,
    payload: P
): { type: T; payload: P };

export function typedAction(type: string, payload?: any) {
    return { type, payload };
}

This means that our reducers knows what Actions are available:

Sources:

https://levelup.gitconnected.com/set-up-a-typescript-react-redux-project-35d65f14b869

https://stackoverflow.com/a/61276522/3850405

If the below functions are removed no check is done:

export function typedAction<T extends string>(type: T): { type: T };
export function typedAction<T extends string, P extends any>(
    type: T,
    payload: P
): { type: T; payload: P };

The project recently decided to prefer arrow functions instead of function declarations.

https://www.npmjs.com/package/eslint-plugin-prefer-arrow

https://eslint.org/docs/rules/func-style

Our eslint config looks like this:

"plugins": [
  "prefer-arrow"
],
"rules": {
  "prefer-arrow/prefer-arrow-functions": [
    "error",
    {
      "disallowPrototype": true,
      "singleReturnOnly": false,
      "classPropertiesAllowed": false
    }
  ],
  "prefer-arrow-callback": [
    "error",
    { "allowNamedFunctions": true }
  ],
  "func-style": [
    "error",
    "expression",
    { "allowArrowFunctions": true }
  ]
}

This meant that we got the following linting errors:

7:8   error    Expected a function expression                              func-style
7:8   error    Use const or class constructors instead of named functions  prefer-arrow/prefer-arrow-functions

If the typedAction function is converted to an arrow function the following errors are received:

export const typedAction = (type: string, payload?: any) => {
    return { type, payload };
}

TS2300 (TS) Duplicate identifier 'typedAction'.

TS2391 (TS) Function implementation is missing or not immediately following the declaration.

To be able to continue it is solved like this but a more permanent solution would be preferable:

export function typedAction<T extends string>(type: T): { type: T };
export function typedAction<T extends string, P extends any>(
    type: T,
    payload: P
): { type: T; payload: P };

// eslint-disable-next-line func-style, prefer-arrow/prefer-arrow-functions
export function typedAction(type: string, payload?: any) {
    return { type, payload };
}