False positive error "incompatible type" on bound TypeVar

Originally posted on gitter july 29th, where it was suggested I open a bug report

Bug Report
For this code:

from typing import Generic, TypeVar, Union

ListT = TypeVar("ListT", str, float)


class TestListA(Generic[ListT]):
    def __init__(self, device: ListT) -> None:
        self._device: ListT = device


class TestListB(TestListA[ListT]):
    def __init__(self, device: ListT) -> None:
        super().__init__(device)

mypy outputs error:

test.py:13: error: Argument 1 to "__init__" of "TestListA" has incompatible type "str"; expected "ListT"  [arg-type]
test.py:13: error: Argument 1 to "__init__" of "TestListA" has incompatible type "float"; expected "ListT"  [arg-type]

which is false positive.

Please note that when using a TypeVar with bound=Union, then mypy doesn't complain.

ListT = TypeVar("ListT", bound=Union[str, float])

Your Environment

• Mypy version used: mypy 0.971 (compiled: yes)
• Mypy command-line flags:
• Mypy configuration options from mypy.ini (and other config files):
• Python version used: Python 3.9.12
• Operating system and version:

Inizia riproducendo l'esempio TestVar fornito con mypy 0.971, quindi confronta il comportamento del suo TypeVar vincolato con la variante bound=Union. Individua il percorso del controllo dei tipi per TestListB.init e aggiungi una copertura di regressione per le diagnosi di falsi positivi. Il lavoro è completato quando l'esempio vincolato passa senza errori, mentre le chiamate incompatibili continuano a essere diagnosticate.