`callable()` fails to narrow type to `Callable`
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Description
Bug Report
I'm sorry if this is a duplicate; it's possible it's covered by one of the existing issues about type narrowing, but I couldn't find anything that explicitly covers this case.
https://mypy.readthedocs.io/en/stable/type_narrowing.html#type-narrowing-expressions explicitly says that callable(obj) will narrow obj to a callable type. However, in my code this doesn't seem to work; the argument to callable is still left as Any.
To Reproduce
With mypy 1.19.1 and --strict:
from collections.abc import Callable
class A:
def get_callback(self, name: str) -> Callable[[], bool]:
callback = getattr(self, name)
assert callable(callback)
return callback
Also demonstrated in this playground.
Actual Behavior
t.py:7: error: Returning Any from function declared to return "Callable[[], bool]" [no-any-return]
Your Environment
- Mypy version used: 1.19.1
- Mypy command-line flags:
--strict - Python version used: 3.13
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 with the t.py reproducer under mypy 1.19.1 and --strict, then read the type-narrowing expressions documentation linked in the report, focusing on callable(obj). Trace how the callable assertion is handled and verify that the example no longer reports no-any-return while returning Callable[[], bool].
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