Always bind Cython functions (#3106)

* Special-case setting __new__ in class

* Always bind Cython functions

Cython/Utility/CythonFunction.c

@@ -552,21 +552,6 @@ static int __Pyx_CyFunction_traverse(__pyx_CyFunctionObject *m, visitproc visit,
 
 static PyObject *__Pyx_CyFunction_descr_get(PyObject *func, PyObject *obj, PyObject *type)
 {
-    __pyx_CyFunctionObject *m = (__pyx_CyFunctionObject *) func;
-
-    if (m->flags & __Pyx_CYFUNCTION_STATICMETHOD) {
-        Py_INCREF(func);
-        return func;
-    }
-
-    if (m->flags & __Pyx_CYFUNCTION_CLASSMETHOD) {
-        if (type == NULL)
-            type = (PyObject *)(Py_TYPE(obj));
-        return __Pyx_PyMethod_New(func, type, (PyObject *)(Py_TYPE(type)));
-    }
-
-    if (obj == Py_None)
-        obj = NULL;
     return __Pyx_PyMethod_New(func, obj, type);
 }
 

tests/run/cyfunction.pyx

@@ -376,6 +376,18 @@ class TestUnboundMethod:
     def meth(self): pass
 
 
+class TestStaticmethod(object):
+    """
+    >>> x = TestStaticmethod()
+    >>> x.staticmeth(42)
+    42
+    >>> x.staticmeth.__get__(42)()
+    42
+    """
+    @staticmethod
+    def staticmeth(arg): return arg
+
+
 cdef class TestOptimisedBuiltinMethod:
     """
     >>> obj = TestOptimisedBuiltinMethod()