[numpy] mypy does not raise type-var when NDArray with incompatible dtype is used as a generic.

[randolf-scholz]

To Reproduce

import numpy as np
from numpy.typing import NDArray

class A: ...

def foo() -> NDArray[A]:  # ✅ raises type-var (true positive)
    return np.array([A()])

def bar() -> list[NDArray[A]]:  # ❌ does not raise type-var (false negative)
    return [np.array([A()])]

Expected Behavior

mypy should raise error: Type argument "A" of "NDArray" must be a subtype of "generic" [type-var] in both instances.

Your Environment

• Mypy version used: 1.10
• numpy version: 1.26.4
• Mypy configuration options: plugins = ["numpy.typing.mypy_plugin"]
• Python version used: 3.11.7