BUG: np.dtype(ctypes.Structure) does not respect _pack_ field

class Foo(ctypes.Structure):
    _fields_ = [('one', ctypes.c_uint8), ('two', ctypes.c_uint32)]
    _pack_ = 2

>>> ctypes.sizeof(Foo())  # packed to alignment 2
6
>>> np.dtype(Foo).itemsize  # default alignment incorrectly used
8

Fix should be fairly straightforward by changing:

numpy/numpy/core/_dtype_ctypes.py

Lines 35 to 46 in 44810f0

    
           def _from_ctypes_structure(t): 
        
               # TODO: gh-10533, gh-10532 
        
               fields = [] 
        
               for item in t._fields_: 
        
                   if len(item) > 2: 
        
                       raise TypeError( 
        
                           "ctypes bitfields have no dtype equivalent") 
        
                   fname, ftyp = item 
        
                   fields.append((fname, dtype_from_ctypes_type(ftyp))) 
        
               # by default, ctypes structs are aligned 
        
               return np.dtype(fields, align=True)

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BUG: np.dtype(ctypes.Structure) does not respect _pack_ field #10532

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	def _from_ctypes_structure(t):
	# TODO: gh-10533, gh-10532
	fields = []
	for item in t._fields_:
	if len(item) > 2:
	raise TypeError(
	"ctypes bitfields have no dtype equivalent")
	fname, ftyp = item
	fields.append((fname, dtype_from_ctypes_type(ftyp)))

	# by default, ctypes structs are aligned
	return np.dtype(fields, align=True)

Uh oh!

BUG: np.dtype(ctypes.Structure) does not respect _pack_ field #10532

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