Invalid Enum Member Annotation

What it does

Checks for enum members that have explicit type annotations.

Why is this bad?

The typing spec states that type checkers should infer a literal type for all enum members. An explicit type annotation on an enum member is misleading because the annotated type will be incorrect — the actual runtime type is the enum class itself, not the annotated type.

In CPython's enum module, annotated assignments with values are still treated as members at runtime, but the annotation will confuse readers of the code.

Examples

from enum import Enum


class Pet(Enum):
    CAT = 1  # OK
    # enum members should not be annotated
    DOG: int = 2  # error

Use instead:

from enum import Enum


class Pet(Enum):
    CAT = 1
    DOG = 2

References

• Typing spec: Enum members