Calling conventions of some Python foreign functions mismatch with their C implementations

[Elaphurus]

For example, Python foreign function ImagingCore.isblock() takes no arguments, as in its C implementation, arguments passed from the Python side will not be used:

Pillow/src/_imaging.c

Lines 2097 to 2100 in d393cfb

	static PyObject *
	_isblock(ImagingObject *self, PyObject *args) {
	return PyBool_FromLong(self->image->block != NULL);
	}

parameter args is not used in the function body.

However, its calling convention given by Python/C API when declaring the foreign function is METH_VARARGS (0x0001), which should be METH_NOARGS instead in this case:

Pillow/src/_imaging.c

Line 3460 in d393cfb

{"isblock", (PyCFunction)_isblock, 1},

This mismatch makes parameter of any type can be passed to this foreign function designed to be parameter free without getting a TypeError:

from PIL import Image
im = Image.open("./test.png")
ic = im.getdata()
ic.isblock('str', 1) # passing anything is legal because of the mismatch

The same mismatch can be found for foreign functions ImagingCore.split(), ImagingCore.getbbox(), ImagingCore.chop_invert(), ImagingCore.getextrema(), ImagingCore.getpalettemode(), ImagingCore.getprojection().

We also found a mismatch in NumPy, which has been fixed in numpy/numpy#18679.

Please let me know if I miss something or get something wrong here.

[radarhere]

I've created #5488 to resolve this.