Python list unpacking trigger pylint ' No value for argument' warning

Question

This question is the same as Pylint false positive when unpacking sys.argv but it had no answer.

I have the following function:

def join(*paths_to_join: str) -> str:
    """Join and returns a normalized path

    Args:
        *paths_to_join (str): All paths to be joined, as an arbitrary number of strings

    Returns:
        The normalized joined path
    """

    return os.path.normpath((os.path.join(*paths_to_join))

This triggers the following pylint warning:

E1120: No value for argument 'a' in function call (no-value-for-parameter)

Is it a real warning or a false positive? Can I do something else than disable it?

Answer 1

This is a valid warning. os.path.join() requires at least one argument, but your function doesn't. So paths_to_join could be empty.

Change your function to be similar to os.path.join()

def join(first: str, rest: List[str]): -> str:
    return os.path.normpath(os.path.join(first, *rest))