Allow re-defined variables to span different scopes with `allow-redefinition`
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feature
topic-usability
- Dominant language
- Python
- Stars
- 20.6k
- Forks
- 3.3k
- PR merge metrics
- PR metrics pending
Description
foo: int
foo = str(foo) # no error
try:
bar: int
bar = str(bar) # error: Incompatible types in assignment (expression has type "str", variable has type "int") [assignment]
except Exception as e:
reveal_type(bar) # should be `int | str`
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 issue with the linked mypy-play example and the allow-redefinition option. Trace how redefinitions are handled across the try scope, then add or update coverage so the assignment is accepted and reveal_type(bar) reports int | str.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- compilers, devtools
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100