Incorrect type in error message when unpacking generator into list
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bug
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- Python
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Description
This is with mypy 0.670 on Python 3.7.2.
When checking the file foo.py:
from typing import List
x: List[List[str]] = [*([1] for i in range(10))]
mypy reports the error:
foo.py:4: error: List item 0 has incompatible type "Generator[List[int], None, None]"; expected "List[str]"
The correct error message should be:
foo.py:4: error: List item 0 has incompatible type "List[int]"; expected "List[str]"
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Research direction
Reproduce the report from foo.py using the generator unpacking example and inspect the diagnostic produced for the list item. Trace where the generator element type is rendered in the error, then verify that the diagnostic reports List[int] rather than Generator[List[int], None, None] while still expecting List[str].
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
- Clearly specified
- Newbie friendliness
- 32/100