TypeGuard may spuriously narrow Any -> object
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bug
topic-typeguard-typeis
- Dominant language
- Python
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Description
I haven't had time to fully reduce this, but in the Sphinx code at https://github.com/sphinx-doc/sphinx/blob/1d4c414319598320f95eed245e4a2f9ad3e5a668/sphinx/ext/coverage.py#L218, the TypeGuards introduced by python/typeshed#5473 lead to an incorrect error:
+ sphinx/ext/coverage.py: note: In member "build_py_coverage" of class "CoverageBuilder":
+ sphinx/ext/coverage.py:218:51: error: Item "object" of "Union[object, object]" has no attribute "__doc__"
Seems like some bad interaction with the negative case for the TypeGuards produced by ismethod and isfunction a few lines up.
Contributor guide
First steps
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Research direction
Start with sphinx/ext/coverage.py around line 218 and reproduce the reported error involving the TypeGuards from ismethod and isfunction. Reduce the Sphinx case to a focused example of Any narrowing; done means the valid doc access no longer reports an object-member error.
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
- Needs clarification
- Newbie friendliness
- 30/100