TypeVar bound to Callable confuses Mypy

# test_case.py
from typing import Callable, Optional, TypeVar, Union, overload

class Foo: pass

class Bar: pass

ReturnsFooOrBarT = Callable[..., Union[Foo, Bar]]
TermT = TypeVar("TermT", bound=ReturnsFooOrBarT)

def returns_foo() -> Foo:
    return Foo()

def returns_bar() -> Bar:
    return Bar()

@overload
def do_something_or_something_else(
    *,
    something_else: Union[int, TermT] = 0,
) -> None:
    ...

@overload
def do_something_or_something_else(
    something: TermT,
    *,
    something_else: Union[int, TermT] = 0,
) -> None:
    ...

def do_something_or_something_else(
    something: Optional[TermT] = None,
    *,
    something_else: Union[int, TermT] = 0,
) -> None:
    pass

do_something_or_something_else(something_else=1)
do_something_or_something_else(something_else=returns_bar)
do_something_or_something_else(something_else=returns_foo)

do_something_or_something_else(returns_foo, something_else=1)
do_something_or_something_else(returns_foo, something_else=returns_foo)

do_something_or_something_else(returns_bar, something_else=1)
do_something_or_something_else(returns_bar, something_else=returns_bar)

returns_foo_or_bar: ReturnsFooOrBarT

# These should all validate, no?
returns_foo_or_bar = returns_foo
do_something_or_something_else(returns_foo_or_bar, something_else=1)
do_something_or_something_else(returns_foo_or_bar, something_else=returns_bar)  # <-- false negative?
do_something_or_something_else(returns_foo, something_else=returns_bar)  # <-- false negative?

# These should all validate, no?
returns_foo_or_bar = returns_bar
do_something_or_something_else(returns_foo_or_bar, something_else=1)
do_something_or_something_else(returns_foo_or_bar, something_else=returns_foo)  # <-- false negative?
do_something_or_something_else(returns_bar, something_else=returns_foo)  # <-- false negative?

% mypy --config=/dev/null test_case.py
/dev/null: No [mypy] section in config file
test_case.py:54: error: Value of type variable "TermT" of "do_something_or_something_else" cannot be "Callable[[], object]"
test_case.py:55: error: Value of type variable "TermT" of "do_something_or_something_else" cannot be "Callable[[], object]"
test_case.py:60: error: Value of type variable "TermT" of "do_something_or_something_else" cannot be "Callable[[], object]"
test_case.py:61: error: Value of type variable "TermT" of "do_something_or_something_else" cannot be "Callable[[], object]"
Found 4 errors in 1 file (checked 1 source file)
% python --version
Python 3.9.10
% mypy --version
mypy 0.931
% mypy --config=/dev/null test_case.py

If I s/TermT/ReturnsFooOrBarT/g, the errors go away. The above is a contrived example, but having a TypeVar is helpful when returning a function of the same type that was provided (e.g., with a decorator).

Possibly related to #8922 or #9075?

Riproduci il comportamento segnalato con l’esempio autonomo test_case.py usando mypy --config=/dev/null e confrontalo con la versione in cui TermT viene sostituito da ReturnsFooOrBarT. Traccia l’inferenza del bound di Callable TypeVar e il controllo degli overload; il lavoro è completato quando i quattro false negatives segnalati non si verificano più, mentre l’esempio continua a essere verificato dal type checker come previsto.