Condition can't be inferred, unable to merge overloads
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Description
Bug Report
I don't know how to describe it, but mypy throws the Condition can't be inferred, unable to merge overloads error
To Reproduce
Gist URL: https://gist.github.com/mypy-play/db2fda335634c93b6c2b044b98fd5c71
Playground URL: https://mypy-play.net/?mypy=master&python=3.13&gist=db2fda335634c93b6c2b044b98fd5c71
def any_function() -> None: ...
if 'Any expression':
@any_function
def _(): ...
def _(): ...
Expected Behavior
Works fine, at least without this misc
Actual Behavior
❯ mypy mypy.py
mypy.py:4: error: Condition can't be inferred, unable to merge overloads [misc]
Found 1 error in 1 file (checked 1 source file)
Your Environment
- Mypy version used: mypy 1.17.0 (compiled: yes)
- Mypy command-line flags: mypy mypy.py
- Mypy configuration options from
mypy.ini(and other config files): nope - Python version used: 3.10.18
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by running the minimal reproducer from the issue with mypy 1.17.0 and compare the diagnostic around the conditional and overload merging. Trace where Condition can't be inferred, unable to merge overloads is emitted, then add regression coverage showing that this example no longer reports the misc error while preserving relevant overload diagnostics.
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