Callable dataclass member flags

[JuliusDegesys]

• Are you reporting a bug, or opening a feature request?
  Reporting a bug

• Please insert below the code you are checking with mypy,
  or a mock-up repro if the source is private. We would appreciate
  if you try to simplify your case to a minimal repro.

from typing import *
from dataclasses import dataclass

class Foo:
    pass

FooProducer = Callable[..., Foo]

@dataclass(frozen=True)
class Bar:
    wrapped: FooProducer

def unpack_bar(x: Bar) -> FooProducer:
    return x.wrapped # This line flags

class Baz:
    def __init__(self, wrapped: FooProducer) -> None:
        self.wrapped = wrapped

def unpack_baz(x: Baz) -> FooProducer:
    return x.wrapped # This line is ok

• What is the actual behavior/output?
  src/debug_mypy.py:18: error: Incompatible return value type (got "Foo", expected "Callable[..., Foo]")
  Found 1 error in 1 file (checked 1 source file)

• What is the behavior/output you expect?
  No error.

• What are the versions of mypy and Python you are using?

$ mypy --version
mypy 0.770

$ python --version
Python 3.8.2

Do you see the same issue after installing mypy from Git master?
Yes

$ mypy src/debug_mypy.py 
src/debug_mypy.py:18: error: Incompatible return value type (got "Foo", expected "Callable[..., Foo]")
Found 1 error in 1 file (checked 1 source file)

$ mypy --version
mypy 0.770+dev.2c8d76efee7f6419654f0a913d29d9f4edb49574

• What are the mypy flags you are using? (For example --strict-optional)
  None

• If mypy crashed with a traceback, please paste
  the full traceback below.

[JelleZijlstra]

This feels similar to #5485 (previously reported dupes include #8618), but the error message sounds a bit different.

[JukkaL]

Let's keep this open, as this may be slightly different from previously reported issues.

[Akuli]

No longer errors on master:

(env310) akuli@akuli-desktop:~/mypy$ cat >a.py
from typing import *
from dataclasses import dataclass

class Foo:
    pass

FooProducer = Callable[..., Foo]

@dataclass(frozen=True)
class Bar:
    wrapped: FooProducer

def unpack_bar(x: Bar) -> FooProducer:
    return x.wrapped # This line flags

class Baz:
    def __init__(self, wrapped: FooProducer) -> None:
        self.wrapped = wrapped

def unpack_baz(x: Baz) -> FooProducer:
    return x.wrapped # This line is ok


(env310) akuli@akuli-desktop:~/mypy$ python3 -m mypy a.py
Success: no issues found in 1 source file

[ethanhs]

This does seem to be fixed in master.