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Description
Bug Report
I think I've uncovered a false positive in mypy's type-checking of is operator with Enums. See below for details.
I know that Enums are a bit funky, so it's possible this is expected behavior (actually, there's a related bug report here #9817).
To Reproduce
# test.py
from enum import Enum
class Food(Enum):
SPAM = "spam"
HAM = "ham"
def is_spam(self) -> bool:
return self is self.SPAM
print(Food.SPAM.is_spam())
print(Food.HAM.is_spam())$ python3 test.py
True
False$ mypy test.py
test.py: note: In member "is_spam" of class "Food":
test.py:8:16: error: Non-overlapping identity check (left operand type: "Food", right operand type: "str")
[comparison-overlap]
return self is self.SPAM
^
Found 1 error in 1 file (checked 1 source file)This goes away if I write it as
def is_spam(self) -> bool:
return self is Food.SPAMthough I'd like to avoid having to duplicate the name of the class a bunch of times in methods with lots of branching on the variant.
Your Environment
$ mypy --version
mypy 0.910$ cat .mypy.ini
[mypy]
# https://mypy.readthedocs.io/en/stable/index.html
python_version = 3.6
pretty = True
show_column_numbers = True
show_error_codes = True
show_error_context = True
check_untyped_defs = True
disallow_any_generics = True
disallow_incomplete_defs = True
disallow_subclassing_any = True
disallow_untyped_calls = True
disallow_untyped_decorators = True
disallow_untyped_defs = True
no_implicit_optional = True
no_implicit_reexport = True
strict_equality = True
warn_redundant_casts = True
warn_return_any = True
warn_unused_configs = True
warn_unused_ignores = True$ python3 --version
Python 3.6.9$ lsb_release -ds
Ubuntu 18.04.5 LTS