[BUG] classmethods don't compile using the limited api

[ap--]

Describe the bug

Hello everyone,

When compiling a class with a classmethod using the limited API I get the following error:

clang -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX14.sdk -DCYTHON_LIMITED_API=1 -DPy_LIMITED_API=0x030B0000 -I/private/var/folders/l4/gpyzwv455hzbmbv78x05555h0000gn/T/build-env-ok8opy1u/include -I/opt/homebrew/opt/python@3.11/Frameworks/Python.framework/Versions/3.11/include/python3.11 -c limited_classmethod.cpp -o build/temp.macosx-14-arm64-cpython-311/limited_classmethod.o
limited_classmethod.cpp:6876:5: error: no matching function for call to 'Py_TYPE'
    __Pyx_PyHeapTypeObject_GC_Del(m);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
limited_classmethod.cpp:971:26: note: expanded from macro '__Pyx_PyHeapTypeObject_GC_Del'
    PyTypeObject *type = Py_TYPE(obj);\
                         ^~~~~~~
/opt/homebrew/opt/python@3.11/Frameworks/Python.framework/Versions/3.11/include/python3.11/object.h:132:29: note: candidate function not viable: no known conversion from '__pyx_CyFunctionObject *' to 'PyObject *' (aka '_object *') for 1st argument
static inline PyTypeObject* Py_TYPE(PyObject *ob) {
                            ^
limited_classmethod.cpp:7396:9: error: use of undeclared identifier 'PyMethodDescrObject'; did you mean 'PyMethodDescr_Type'?
        PyMethodDescrObject *descr = (PyMethodDescrObject *)method;
        ^~~~~~~~~~~~~~~~~~~
        PyMethodDescr_Type
/opt/homebrew/opt/python@3.11/Frameworks/Python.framework/Versions/3.11/include/python3.11/descrobject.h:22:26: note: 'PyMethodDescr_Type' declared here
PyAPI_DATA(PyTypeObject) PyMethodDescr_Type;
                         ^
limited_classmethod.cpp:7396:39: error: use of undeclared identifier 'PyMethodDescrObject'; did you mean 'PyMethodDescr_Type'?
        PyMethodDescrObject *descr = (PyMethodDescrObject *)method;
                                      ^~~~~~~~~~~~~~~~~~~
                                      PyMethodDescr_Type
/opt/homebrew/opt/python@3.11/Frameworks/Python.framework/Versions/3.11/include/python3.11/descrobject.h:22:26: note: 'PyMethodDescr_Type' declared here
PyAPI_DATA(PyTypeObject) PyMethodDescr_Type;
                         ^
limited_classmethod.cpp:7396:60: error: expected expression
        PyMethodDescrObject *descr = (PyMethodDescrObject *)method;
                                                           ^
limited_classmethod.cpp:7396:30: error: use of undeclared identifier 'descr'
        PyMethodDescrObject *descr = (PyMethodDescrObject *)method;
                             ^
limited_classmethod.cpp:7400:32: error: use of undeclared identifier 'descr'
        PyTypeObject *d_type = descr->d_common.d_type;
                               ^
limited_classmethod.cpp:7402:47: error: use of undeclared identifier 'descr'
        return PyDescr_NewClassMethod(d_type, descr->d_method);
                                              ^
limited_classmethod.cpp:7405:14: error: use of undeclared identifier 'PyMethod_Check'
    else if (PyMethod_Check(method)) {
             ^
limited_classmethod.cpp:7406:34: error: use of undeclared identifier 'PyMethod_GET_FUNCTION'
        return PyClassMethod_New(PyMethod_GET_FUNCTION(method));
                                 ^
limited_classmethod.cpp:7409:16: error: use of undeclared identifier 'PyClassMethod_New'
        return PyClassMethod_New(method);
               ^
10 errors generated.

Code to reproduce the behaviour:

# limited_classmethod.pyx

cdef class A:
    @classmethod
    def method(cls):
        pass

Expected behaviour

It should compile.

OS

No response

Python version

No response

Cython version

No response

Additional context

classmethod implementation:

cython/Cython/Utility/CythonFunction.c

Lines 1754 to 1804 in 0f2a0d3

	//////////////////// ClassMethod.proto ////////////////////
	#include "descrobject.h"
	CYTHON_UNUSED static PyObject* __Pyx_Method_ClassMethod(PyObject *method); /*proto*/
	//////////////////// ClassMethod ////////////////////
	static PyObject* __Pyx_Method_ClassMethod(PyObject *method) {
	#if CYTHON_COMPILING_IN_PYPY && PYPY_VERSION_NUM <= 0x05080000
	if (PyObject_TypeCheck(method, &PyWrapperDescr_Type)) {
	// cdef classes
	return PyClassMethod_New(method);
	}
	#else
	#if CYTHON_COMPILING_IN_PYPY
	// special C-API function only in PyPy >= 5.9
	if (PyMethodDescr_Check(method))
	#else
	#if PY_MAJOR_VERSION == 2
	// PyMethodDescr_Type is not exposed in the CPython C-API in Py2.
	static PyTypeObject *methoddescr_type = NULL;
	if (unlikely(methoddescr_type == NULL)) {
	PyObject *meth = PyObject_GetAttrString((PyObject*)&PyList_Type, "append");
	if (unlikely(!meth)) return NULL;
	methoddescr_type = Py_TYPE(meth);
	Py_DECREF(meth);
	}
	#else
	PyTypeObject *methoddescr_type = &PyMethodDescr_Type;
	#endif
	if (__Pyx_TypeCheck(method, methoddescr_type))
	#endif
	{
	// cdef classes
	PyMethodDescrObject *descr = (PyMethodDescrObject *)method;
	#if PY_VERSION_HEX < 0x03020000
	PyTypeObject *d_type = descr->d_type;
	#else
	PyTypeObject *d_type = descr->d_common.d_type;
	#endif
	return PyDescr_NewClassMethod(d_type, descr->d_method);
	}
	#endif
	else if (PyMethod_Check(method)) {
	// python classes
	return PyClassMethod_New(PyMethod_GET_FUNCTION(method));
	}
	else {
	return PyClassMethod_New(method);
	}
	}