(🎁) Report unreachable when `TypeGuard[Never]`
Open
Nobody has claimed this yet.
feature
topic-reachability
topic-typeguard-typeis
- Dominant language
- Python
- Stars
- 20.6k
- Forks
- 3.3k
- PR merge metrics
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Description
def guard(a: object) -> TypeGuard[Never]: ...
a: object
assert guard(a)
print("hi") # expected error unreachable
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 provided TypeGuard[Never] example through mypy and confirm that the print statement is not reported as unreachable. Trace the reachability analysis for TypeGuard results, add a regression test for this example, and verify that the expected unreachable diagnostic is produced.
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
- Clearly specified
- Newbie friendliness
- 52/100