python / python/mypy

(🐞) Heterogeneous `Enum`'s `.value` is `Any` & Union of homogeneous `Enum`s `.value` is `Any`

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bug topic-enum
Dominant language
Python
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Description

from enum import Enum


class Homo1(Enum):
    A = 1
    B = 2
class Homo2(Enum):
    A = 1
    B = 2
class Hetero(Enum):
    A = 1
    B = ""

homo: Homo1
reveal_type(homo.value)  # 1 | 2
hetero: Hetero
reveal_type(hetero.value)  # Any
homo_union: Homo1 | Homo2
reveal_type(homo_union.value)  # Any
  • possibly related #14092

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the provided Enum examples and tracing mypy's inference for heterogeneous Enum values and unions of homogeneous Enums. Determine the intended non-Any revealed types and add focused regression coverage; done means these cases no longer reveal Any.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
devtools
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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