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JukkaL opened this issue Jan 18, 2018 · 0 comments · Fixed by #4486
Closed

Forward reference to decorated class method has type Any #4485

JukkaL opened this issue Jan 18, 2018 · 0 comments · Fixed by #4486
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@JukkaL
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topic-fine-grained-incremental

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@JukkaL
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JukkaL commented Jan 18, 2018

In the program below, the type inferred for cls.g in A.f is Any, even though it should be def (x: builtins.str):

from typing import TypeVar, Callable

T = TypeVar('T')
def dec() -> Callable[[T], T]: pass

class A:
    @classmethod
    def f(cls) -> None:
        reveal_type(cls.g)  # Any  <-- unexpected

    @classmethod
    @dec()
    def g(cls, x: str) -> None:
        pass

    @classmethod
    def h(cls) -> None:
        reveal_type(cls.g)  # def (x: builtins.str)  <-- ok

This works correctly when the decorated method is accessed using an instance type (such as self).

In fine-grained incremental mode the types can be more precise, which can result in additional errors in fine-grained incremental mode.
@JukkaL JukkaL self-assigned this Jan 18, 2018
JukkaL added a commit that referenced this issue Jan 18, 2018
@JukkaL
Fix type of forward reference to a decorated class method
5a3109c 
The case wasn't properly handled before when accessing through a type
object -- the type of the forward reference defaulted to `Any`.

The fix doesn't work at module top level since module top levels can't
be deferred, but the reference would generally fail at runtime anyway.

Fixes #4485.
@JukkaL JukkaL mentioned this issue Jan 18, 2018
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JukkaL added a commit that referenced this issue Feb 19, 2018
@JukkaL
Fix type of forward reference to a decorated class method (#4486)
3545a71 
The case wasn't properly handled before when accessing through a type
object -- the type of the forward reference defaulted to `Any`.

The fix doesn't work at module top level since module top levels can't
be deferred, but the reference would generally fail at runtime anyway.

Fixes #4485.
yedpodtrzitko pushed a commit to kiwicom/mypy that referenced this issue Mar 15, 2018
@JukkaL @yedpodtrzitko
Fix type of forward reference to a decorated class method (python#4486)
7f3cbf3 
The case wasn't properly handled before when accessing through a type
object -- the type of the forward reference defaulted to `Any`.

The fix doesn't work at module top level since module top levels can't
be deferred, but the reference would generally fail at runtime anyway.

Fixes python#4485.
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Fix type of forward reference to a decorated class method python/mypy
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