Open
Description
Bug Report
Unpacking a tuple in the below scenario results in wrong assumed types.
To Reproduce
import typing as t
def spam(val: t.Union[t.Type, None] = None) -> None:
def eggs(type_: t.Type) -> None:
pass
reveal_type(val)
if isinstance(val, type):
reveal_type(val)
val, foo = None, val
reveal_type(val)
reveal_type(foo)
return eggs(foo)
Expected Behavior
After the line val, foo = None, val
, I would expect that
val
has typeNone
(ok)foo
has typeType[Any]
- the call to
eggs()
passes
Actual Behavior
$ mypy test.py
test.py:9: note: Revealed type is 'Union[Type[Any], None]'
test.py:11: note: Revealed type is 'Type[Any]'
test.py:13: note: Revealed type is 'None'
test.py:14: note: Revealed type is 'None'
test.py:15: error: Argument 1 to "eggs" has incompatible type "None"; expected "Type[Any]"
Found 1 error in 1 file (checked 1 source file)
This does not match with my expectations 2 and 3.
Your Environment
Python 3.9
Mypy 0.790
MacOS 10.14.6