sys.platform checks assigned to variables are not handled correctly
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Description
When doing a sys.platform check, mypy seems to only recognise this when the check is done directly in the if statement, but not when the check is assigned to a variable.
e.g. https://github.com/kuwv/invoke/blob/typing/invoke/terminals.py#L33
This produces:
invoke/terminals.py:33:5: error: Module "ctypes" has no attribute "windll" [attr-defined]
from ctypes import (
But, if you change if WINDOWS to if sys.platform == "win32", then the error disappears.
I'm pretty sure I've seen mypy work correctly when sys.version_info checks are assigned to a variable, so not sure why sys.platform checks would be any different.
Tested with 0.991.
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Research direction
Reproduce the report using the example in invoke/terminals.py around line 33, comparing the assigned-variable check with the direct sys.platform check. Trace mypy's handling of sys.platform conditions and add coverage for the assigned form; done means the ctypes.windll error is no longer reported for that case.
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
- Mostly clear
- Newbie friendliness
- 45/100