Don't consider a branch unreachable if there is possible promotion #14077
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| x: Union[float, complex] | ||
| if isinstance(x, int): | ||
| # Most likely this was an error, but we still type-check this branch | ||
| reveal_type(x) # N: Revealed type is "<nothing>" |
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hm, I'd expected this to also give int. What happens if x is a union with an unrelated type, like complex | str?
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It will be also <nothing>. It is not easy to change. I however discovered couple more bugs while playing with this, so I will try to figure out something.
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Diff from mypy_primer, showing the effect of this PR on open source code: flake8-pyi (https://github.com/PyCQA/flake8-pyi)
- pyi.py:1126: error: Subclass of "complex" and "int" cannot exist: would have incompatible method signatures [unreachable]
- pyi.py:1275: error: Subclass of "complex" and "int" cannot exist: would have incompatible method signatures [unreachable]
- pyi.py:1275: error: Right operand of "and" is never evaluated [unreachable]
- pyi.py:1276: error: Statement is unreachable [unreachable]
- pyi.py:1287: error: Subclass of "complex" and "int" cannot exist: would have incompatible method signatures [unreachable]
- pyi.py:1288: error: Right operand of "and" is never evaluated [unreachable]
- pyi.py:1290: error: Statement is unreachable [unreachable]
- pyi.py:1313: error: Subclass of "complex" and "int" cannot exist: would have incompatible method signatures [unreachable]
core (https://github.com/home-assistant/core)
+ homeassistant/components/gios/__init__.py:33: error: Unused "type: ignore" comment
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JelleZijlstra
approved these changes
Nov 13, 2022
|
If there are no more comments, I am going to merge this later today or tomorrow. |
This was referenced Nov 14, 2022
Merged
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Fixes #14030
FWIW this looks like an acceptable compromise after discussions in the issue. Also it is easy to implement. Let's see what
mypy_primerwill show.