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bool |= bool complains about incompatible assignment type #1793
Description
From python/mypy#4386
I couldn't find any definitive specification on this other than PEP 285
Here's the input program (which I expect to cause no linting errors)
x = True
x |= FalseHowever it results in the following:
$ mypy test.py
test.py:2: error: Incompatible types in assignment (expression has type "int", variable has type "bool")
$ pip freeze -l
mypy==0.560
psutil==5.4.2
typed-ast==1.1.0
It seems that PEP 285 is implemented faithfully in the versions of python I was able to check:
$ echo -n '2.6 2.7 3.4 3.5 3.6' | xargs -d' ' --replace -- bash -xc "python{} -c 'assert type(False | True) is bool'"
+ python2.6 -c 'assert type(False | True) is bool'
+ python2.7 -c 'assert type(False | True) is bool'
+ python3.4 -c 'assert type(False | True) is bool'
+ python3.5 -c 'assert type(False | True) is bool'
+ python3.6 -c 'assert type(False | True) is bool'
This patch to typeshed makes the above pass:
$ git diff stdlib/3
diff --git a/stdlib/3/builtins.pyi b/stdlib/3/builtins.pyi
index f2cea0f..74eb806 100644
--- a/stdlib/3/builtins.pyi
+++ b/stdlib/3/builtins.pyi
@@ -537,6 +537,30 @@ class memoryview(Sized, Container[bytes]):
class bool(int):
def __init__(self, o: object = ...) -> None: ...
+ @overload # type: ignore
+ def __and__(self, x: bool) -> bool: ...
+ @overload # type: ignore
+ def __and__(self, x: int) -> int: ...
+ @overload # type: ignore
+ def __or__(self, x: bool) -> bool: ...
+ @overload # type: ignore
+ def __or__(self, x: int) -> int: ...
+ @overload # type: ignore
+ def __xor__(self, x: bool) -> bool: ...
+ @overload # type: ignore
+ def __xor__(self, x: int) -> int: ...
+ @overload # type: ignore
+ def __rand__(self, x: bool) -> bool: ...
+ @overload # type: ignore
+ def __rand__(self, x: int) -> int: ...
+ @overload # type: ignore
+ def __ror__(self, x: bool) -> bool: ...
+ @overload # type: ignore
+ def __ror__(self, x: int) -> int: ...
+ @overload # type: ignore
+ def __rxor__(self, x: bool) -> bool: ...
+ @overload # type: ignore
+ def __rxor__(self, x: int) -> int: ...
class slice:
start = ... # type: Optional[int]though I'm concerned about the # type: ignore (bool does after all violate LSP ala python/mypy#1237 so maybe this is correct?)
If this seems OK, I'll turn it into a PR :)
Activity
JelleZijlstra commentedon Dec 19, 2017
This sounds reasonable (if slightly unfortunate). Presumably you'll need the same change in the Python 2 stubs.
asottile commentedon Dec 19, 2017
yep -- I had that patch for python2 as well (just showed the
git diff -- stdlib/3in the issue so it was less noisy). I'll submit a PR