python / python/mypy

`Final` nested inside `ClassVar` results in `Any`

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bug topic-final
Dominant language
Python
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Description

Bug Report

According to the Python 3.13 ClassVar documentation, ClassVar can be nested within Final, and Final can likewise be nested within ClassVar.

Changed in version 3.13: ClassVar can now be nested in Final, and vice versa.

However, Mypy seems to type-check only the case where ClassVar is nested inside Final, not the reverse.

To Reproduce

https://mypy-play.net/?mypy=latest&python=3.13&flags=strict&gist=996a968ac738badee42e71c23bd5f539

Expected Behavior

Success: no issues found in 1 source file

Actual Behavior

main.py:7: error: Returning Any from function declared to return "int"  [no-any-return]
Found 1 error in 1 file (checked 1 source file)

Your Environment

  • Mypy version used: mypy 1.17.1 (compiled: yes)
  • Mypy command-line flags: --strict
  • Python version used: Python 3.13.3

Contributor guide

Open the contributing guide

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 running the linked mypy-play reproducer with Python 3.13 and --strict, then trace how mypy handles the two nesting orders of ClassVar and Final. Add a regression test for Final nested inside ClassVar and verify that the example reports no errors, including no-any-return.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
devtools
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
48/100

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