Weird error when using enum(val1, val2)

[wimglenn]

Using the example from the docs:

class Color(Enum):
    RED = 1
    GREEN = 2
    BLUE = 3

Actual output (py 3.11):

>>> Color(0, 1)
TypeError: <enum 0> cannot extend <enum 'Color'>

Expected output- not 100% sure but, something along the lines of:

• TypeError saying "... takes 1 positional argument but 2 were given" like Color() does, or
• ValueError saying "... is not a valid Color" like Color(0) does

The current metaclass error message is a bit confusing.

[JimZhouZZY]

The error message is correct.
Color(0, 1) calls for creating a new enum subclass with value 0 and names 1. See enum.py line700

    def __call__(cls, value, names=None, *, module=None, qualname=None, type=None, start=1):
        """
        Either returns an existing member, or creates a new enum class.

        This method is used both when an enum class is given a value to match
        to an enumeration member (i.e. Color(3)) and for the functional API
        (i.e. Color = Enum('Color', names='RED GREEN BLUE')).

        When used for the functional API:

        `value` will be the name of the new class.

        `names` should be either a string of white-space/comma delimited names
        (values will start at `start`), or an iterator/mapping of name, value pairs.

        ...
        """
        if names is None:  # simple value lookup
            return cls.__new__(cls, value)
        # otherwise, functional API: we're creating a new Enum type
        return cls._create_(value, names, ...)

According to the doc, subclassing an enumeration is allowed only if the enumeration does not define any members. So in enum.py line930 it raised the error.

[wimglenn]

I see that, but it's a leaky abstraction.

[ethanfurman]

This is fixed in 3.13:

ValueError: (0, 1) is not a valid Color

[wimglenn]

Right, apologies for not checking main before reporting. Looks fixed in 3.12.0rc1 too, git bisected the fix to 65dab15. Closing as duplicate of [Enum] call syntax error message is confusing #92647.