Cpp: Fix AttributeNode.analyse_as_type_attribute overloaded alternatives

Cython/Compiler/ExprNodes.py

@@ -6954,6 +6954,8 @@ class AttributeNode(ExprNode):
                         ubcm_entry.func_cname = entry.func_cname
                         ubcm_entry.is_unbound_cmethod = 1
                         ubcm_entry.scope = entry.scope
+                        if type.is_cpp_class:
+                            ubcm_entry.overloaded_alternatives = [Symtab.Entry(entry.name, entry.func_cname, entry.type) for entry in entry.overloaded_alternatives]
                     return self.as_name_node(env, ubcm_entry, target=False)
             elif type.is_enum:
                 if self.attribute in type.values: