ctypes nested array constructor doesn't work with sequences

[alanhdu]

Using Python 3.7 and mypy 0.660 on the following code:

import ctypes

Quaternion = ctypes.c_int * 4
Pair = Quaternion * 2

quat = Quaternion(1, 2, 3, 4)
p = Pair((1, 2, 3, 4), (2, 3, 4, 5))

returns

$ mypy ctypes_nested.py 
ctypes_nested.py:7: error: Array constructor argument 1 of type "Tuple[builtins.int, builtins.int, builtins.int, builtins.int]" is not convertible to the array element type "ctypes.Array[ctypes.c_int]"
ctypes_nested.py:7: error: Array constructor argument 2 of type "Tuple[builtins.int, builtins.int, builtins.int, builtins.int]" is not convertible to the array element type "ctypes.Array[ctypes.c_int]"

even though at runtime this constructor works just fine. Of course, changing the constructor to Pair(Quaternion(1, 2, 3, 4), Quaternion(2, 3, 4, 5)) works just fine.

[jameslamb]

Using Python 3.11.5 and mypy 1.6.1, I experienced what I think is a related issue today.

I'm fairly confident the following is valid ctypes code. It follows the pattern for array construction recommended by https://docs.python.org/3/library/ctypes.html#arrays.

The recommended way to create array types is by multiplying a data type with a positive integer

And follows the docs for ctypes.c_char_p at https://docs.python.org/3/library/ctypes.html#ctypes.c_char_p ctypes.c_char_p, which say

The constructor accepts an integer address

import ctypes

buffers = [
    ctypes.create_string_buffer(255),
    ctypes.create_string_buffer(255)
]

CharArray = ctypes.c_char_p * 2

array_of_buffer_pointers = CharArray(
    ctypes.addressof(buffers[0]),
    ctypes.addressof(buffers[1])
)

That code runs without error and works the way I'd expect, but mypy is unhappy about it.

mypy ./test-ctypes.py

# test-ctypes.py:10: error: Array constructor argument 1 of type "int" is not convertible to the array element type "c_char_p"  [misc]
# test-ctypes.py:10: error: Array constructor argument 2 of type "int" is not convertible to the array element type "c_char_p"  [misc]
# Found 2 errors in 1 file (checked 1 source file)

Searching for that error message in this project, I found this test:

mypy/test-data/unit/check-ctypes.test

Lines 170 to 172 in c6cb3c6

	float_values = [1.0, 2.0, 3.0, 4.0]
	intarr4(*float_values) # E: Array constructor argument 1 of type "List[float]" is not convertible to the array element type "Iterable[c_int]"
	[builtins fixtures/floatdict.pyi]

It and similar tests in that file appear to all check how the case where literal values in Python objects are provided to fill ctypes arrays, but not the cases where integers representing addresses are used.

I apologize if I've made some mistake in my use of ctypes here or if this is not related the original post above. I hope this report will help narrow down the issue if there is one.

Thanks for your time and consideration.