input type for lambda with union of `Callable`s is inferred as `Any`
Open
Nobody has claimed this yet.
bug
- Dominant language
- Python
- Stars
- 20.6k
- Forks
- 3.3k
- PR merge metrics
- PR metrics pending
Description
from typing import Callable
def foo(fn: Callable[[int, str], None] | Callable[[int], None]) -> None:
...
foo(lambda value: reveal_type(value)) #revealed type is Any
https://mypy-play.net/?mypy=latest&python=3.10&gist=d73f588945031c9fb8192dcf83c030fa
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 reproducing the example in the linked mypy-play playground and confirm that the lambda parameter is revealed as Any. Trace mypy's inference for a lambda passed to a union of Callable types; done means the parameter receives the appropriate inferred type and the regression is covered by a test.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100