Mypy issue with python scoping rule
Open
Nobody has claimed this yet.
bug
priority-1-normal
topic-runtime-semantics
topic-variable-scope
- Dominant language
- Python
- Stars
- 20.6k
- Forks
- 3.3k
- PR merge metrics
- PR metrics pending
Description
Mypy pass following code as valid:
def now() -> str:
return "now"
def usage() -> None:
now = now()
print(now + "!")
usage()
Snippet will raise UnboundLocalError error.
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 provided Python snippet and inspecting mypy's handling of local name binding and scope analysis. Done means mypy detects and reports the invalid reference where the local now is used before assignment; the issue names no source file or test to begin with.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 35/100