使用类型联合时“arg-type”键入错误，单独使用类型时没有错误

Question

我想了解为什么float和np.float64类型的联合会在这里产生[arg-type]键入错误，但单独使用类型就可以了：

import numpy as np
from numpy.typing import ArrayLike
from typing import Any, Union


def as_float_array(a: ArrayLike) -> Any:
    ...


w: float = float(4)
as_float_array([w])

x: np.float64 = np.float64(4)
as_float_array([x])

y: Union[float, np.float64] = float(4)
as_float_array([y])

z: Union[float, np.float64] = np.float64(4)
as_float_array([z])

/.../scratch.py:17: error: Argument 1 to "as_float_array" has incompatible type "List[Union[float, floating[_64Bit]]]"; expected "Union[Sequence[Sequence[Sequence[Sequence[Sequence[Any]]]]], Union[Union[_SupportsArray[dtype[Any]], Sequence[_SupportsArray[dtype[Any]]], Sequence[Sequence[_SupportsArray[dtype[Any]]]], Sequence[Sequence[Sequence[_SupportsArray[dtype[Any]]]]], Sequence[Sequence[Sequence[Sequence[_SupportsArray[dtype[Any]]]]]]], Union[bool, int, float, complex, str, bytes, Sequence[Union[bool, int, float, complex, str, bytes]], Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]], Sequence[Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]]], Sequence[Sequence[Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]]]]]]]"
/.../scratch.py:20: error: Argument 1 to "as_float_array" has incompatible type "List[Union[float, floating[_64Bit]]]"; expected "Union[Sequence[Sequence[Sequence[Sequence[Sequence[Any]]]]], Union[Union[_SupportsArray[dtype[Any]], Sequence[_SupportsArray[dtype[Any]]], Sequence[Sequence[_SupportsArray[dtype[Any]]]], Sequence[Sequence[Sequence[_SupportsArray[dtype[Any]]]]], Sequence[Sequence[Sequence[Sequence[_SupportsArray[dtype[Any]]]]]]], Union[bool, int, float, complex, str, bytes, Sequence[Union[bool, int, float, complex, str, bytes]], Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]], Sequence[Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]]], Sequence[Sequence[Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]]]]]]]"
Found 2 errors in 1 file (checked 1 source file)

预期格式：

Union[
    Sequence[Sequence[Sequence[Sequence[Sequence[Any]]]]],
    Union[
        Union[
            _SupportsArray[dtype[Any]],
            Sequence[_SupportsArray[dtype[Any]]],
            Sequence[Sequence[_SupportsArray[dtype[Any]]]],
            Sequence[Sequence[Sequence[_SupportsArray[dtype[Any]]]]],
            Sequence[Sequence[Sequence[Sequence[_SupportsArray[dtype[Any]]]]]]
        ],
        Union[
            bool, int, float, complex, str, bytes,
            Sequence[Union[bool, int, float, complex, str, bytes]],
            Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]],
            Sequence[Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]]],
            Sequence[Sequence[Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]]]]
        ]
    ]
]

值得注意的是，按如下方式定义新类型可以消除错误：

/.../scratch.py:17: error: Argument 1 to "as_float_array" has incompatible type "List[Union[float, floating[_64Bit]]]"; expected "Union[Sequence[Sequence[Sequence[Sequence[Sequence[Any]]]]], Union[Union[_SupportsArray[dtype[Any]], Sequence[_SupportsArray[dtype[Any]]], Sequence[Sequence[_SupportsArray[dtype[Any]]]], Sequence[Sequence[Sequence[_SupportsArray[dtype[Any]]]]], Sequence[Sequence[Sequence[Sequence[_SupportsArray[dtype[Any]]]]]]], Union[bool, int, float, complex, str, bytes, Sequence[Union[bool, int, float, complex, str, bytes]], Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]], Sequence[Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]]], Sequence[Sequence[Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]]]]]]]"
/.../scratch.py:20: error: Argument 1 to "as_float_array" has incompatible type "List[Union[float, floating[_64Bit]]]"; expected "Union[Sequence[Sequence[Sequence[Sequence[Sequence[Any]]]]], Union[Union[_SupportsArray[dtype[Any]], Sequence[_SupportsArray[dtype[Any]]], Sequence[Sequence[_SupportsArray[dtype[Any]]]], Sequence[Sequence[Sequence[_SupportsArray[dtype[Any]]]]], Sequence[Sequence[Sequence[Sequence[_SupportsArray[dtype[Any]]]]]]], Union[bool, int, float, complex, str, bytes, Sequence[Union[bool, int, float, complex, str, bytes]], Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]], Sequence[Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]]], Sequence[Sequence[Sequence[Sequence[Union[bool, int, float, complex, str, bytes]]]]]]]]"
Found 2 errors in 1 file (checked 1 source file)