Lambda as RHS for operator always gets inferred as Any

When a lambda is given as the RHS in an operator (example uses >>, but also occurs with others), the lambda’s type is always inferred as Any. Whereas calling the operator function directly, or passing an explicit function, does not.

from typing import Callable, Generic, TypeVar

_T = TypeVar('_T')
_U = TypeVar('_U')

class A(Generic[_T]):
    _value: _T
    def __init__(self, val: _T) -> None: ...
    def __rshift__(self, f: Callable[[_T], _U]) -> _U: ...

def inc(x: int) -> int: ...

A(1) >> inc  # No error
A(1).__rshift__(lambda x: x + 1)  # No error
A(1) >> (lambda x: x + 1)
#        │         └ Expression has type "Any"
#        └ Expression type contains "Any" (has type Callable[[Any], Any])

• Python 3.7.0
• mypy 0.641
• mypy config:

  [mypy]
  check_untyped_defs = True
  disallow_any_decorated = True
  disallow_any_expr = True
  disallow_any_unimported = True
  disallow_incomplete_defs = True
  disallow_subclassing_any = True
  disallow_untyped_calls = True
  disallow_untyped_decorators = True
  disallow_untyped_defs = True
  warn_return_any = True
  warn_unused_ignores = True
  

Esegui la riproduzione Python fornita con la configurazione mypy indicata e confronta la forma dell’operatore con la chiamata diretta al metodo e la funzione denominata. Traccia l’inferenza del tipo dell’espressione dell’operatore a partire da quel punto di ingresso; il lavoro è completato quando la lambda tra parentesi viene inferita dal tipo dell’operando invece di produrre Any.