TypedDict as default_factory in dataclasses is not inferred correctly

[iddan]

• Are you reporting a bug, or opening a feature request? 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 dataclasses import dataclass, field
from mypy_extensions import TypedDict

class Person(TypedDict, total=False):
 name: str

@dataclass
class Job:
 person: Person = field(default_factory=Person)

• What is the actual behavior/output?

main.py:9: error: Incompatible types in assignment (expression has type "main.Person", variable has type "Person")

• What is the behavior/output you expect? To pass
• What are the versions of mypy and Python you are using? latest
  Do you see the same issue after installing mypy from Git master? yes
• What are the mypy flags you are using? (For example --strict-optional) none

[ilevkivskyi]

This is actually not specific to dataclasses. It looks like typed dict class objects are never analyzed properly. There is a hack in visit_call_expr in type checker, that checks them specially, but if they appear in any other context, the corresponding CallableType is not created correctly.

[tsangwpx]

In mypy 1.6.1, the output is

error: Argument "default_factory" to "field" has incompatible type "Type[Person]"; expected "Callable[[], Person]" [arg-type]

workaround:

@dataclass
class Job:
 person: Person = field(default_factory=lambda: Person())