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Cannot inference common base class when root of hierarchy is Any #5134
Description
I believe this to be a bug
code
(this has been boiled down from a more complete example)
from typing import Type
from external import ExtBase
class Base(ExtBase):
pass
class Concrete1(Base):
pass
class Concrete2(Concrete1):
pass
def f(x: Type[Base]) -> None:
pass
def g(x: bool) -> None:
#reveal_type(Base)
#reveal_type(Concrete1)
#reveal_type(Concrete2)
#reveal_type(Concrete1 if x else Concrete2)
f(Concrete1 if x else Concrete2)output
$ mypy t2.py --ignore-missing-imports
t2.py:27: error: Argument 1 to "f" has incompatible type "Type[object]"; expected "Type[Base]"
output with types revealed
$ mypy t2.py --ignore-missing-imports
t2.py:23: error: Revealed type is 'def (*_args: Any, **_kwds: Any) -> t2.Base'
t2.py:24: error: Revealed type is 'def (*_args: Any, **_kwds: Any) -> t2.Concrete1'
t2.py:25: error: Revealed type is 'def (*_args: Any, **_kwds: Any) -> t2.Concrete2'
t2.py:26: error: Revealed type is 'def (*_args: Any, **_kwds: Any) -> builtins.object'
t2.py:27: error: Argument 1 to "f" has incompatible type "Type[object]"; expected "Type[Base]"
version information
$ mypy --version
mypy 0.600
against master
same error
peculiarly working
diff --git a/t2.py b/t2.py
index 91a8309..6f35532 100644
--- a/t2.py
+++ b/t2.py
@@ -24,4 +24,8 @@ def g(x: bool) -> None:
#reveal_type(Concrete1)
#reveal_type(Concrete2)
#reveal_type(Concrete1 if x else Concrete2)
- f(Concrete1 if x else Concrete2)
+ if x:
+ t = Concrete1
+ else:
+ t = Concrete2
+ f(t)
Activity
asottile commentedon Jun 1, 2018
Note that this also passes (why I believe to be ~related to
Anyhere):gvanrossum commentedon Jun 1, 2018
This looks like another case where the conditional expression should take the context into account. I wonder if it works as expected when #5095 is reverted?
asottile commentedon Jun 1, 2018
Seems to work as expected when reverting that, yes:
gvanrossum commentedon Jun 1, 2018
OK, then the fix would entail improving on that diff (it partially reverted #5041, which would have the desired effect here but not in general). Perhaps we should always try the make_simplified_union() call and accept the return value if it's not a Union -- that seems to be the case here.
ilevkivskyi commentedon Jun 1, 2018
TBH, I would also allow
Optional[...]as a result ofmake_simplified_union, so that the rules would be:make_simplified_unionif the result is a non-union, or a union of two types one of which isNoneThe point is that
Anycan "swallow"None, so thatunimported if x else Noneresults in justAny, notOptional[Any](this however reveals few dozens of real errors in our internal codebases).hauntsaninja commentedon Aug 13, 2023
I fixed this in #14404