Closed
Description
The following code:
from copy import deepcopy
from typing import Literal, Union
def f(a: str, b: bool) -> Union[Literal[True], str]:
return b or deepcopy(a)
print(f("abc", False))
print(f("abc", True))produces the following output:
$ python3 test.py
abc
True
$ mypy test.py
test.py: note: In function "f":
test.py:5:12: error: Incompatible return value type (got "bool", expected "Union[Literal[True], str]") [return-value]
return b or deepcopy(a)
^
test.py:5:26: error: Argument 1 to "deepcopy" has incompatible type "str"; expected "bool" [arg-type]
return b or deepcopy(a)
^
Found 2 errors in 1 file (checked 1 source file)
$ python3 --version
Python 3.8.10
$ mypy --version
mypy 0.931
$ cat /etc/issue
Ubuntu 20.04.3 LTS \n \l
$ uname -a
Linux ubuntu 5.4.0-94-generic #106-Ubuntu SMP Thu Jan 6 23:58:14 UTC 2022 x86_64 x86_64 x86_64 GNU/LinuxIf deepcopy() call is removed, warnings go away.
In some similar cases only the second warning appears, which looks even weirder.