warn about ignored freelist() decorator on subtypes

Cython/Compiler/Nodes.py

@@ -4189,6 +4189,9 @@ class CClassDefNode(ClassDefNode):
                               % base_class_entry.type.name)
                     else:
                         self.base_type = base_class_entry.type
+                if env.directives.get('freelist', 0) > 0:
+                    warning(self.pos, "freelists are not currently supported for subtypes", 1)
+
         has_body = self.body is not None
         if self.module_name and self.visibility != 'extern':
             module_path = self.module_name.split(".")

tests/errors/e_exttype_freelist.pyx

+# mode: error
+# tag: freelist, werror
+
+cimport cython
+
+@cython.freelist(8)
+cdef class ExtType:
+    pass
+
+@cython.freelist(8)
+cdef class ExtTypeObject(object):
+    pass
+
+cdef class ExtSubTypeOk(ExtType):
+    pass
+
+@cython.freelist(8)
+cdef class ExtSubTypeFail(ExtType):
+    pass
+
+
+_ERRORS = """
+18:5: freelists are not currently supported for subtypes
+"""

tests/run/exttype_freelist.pyx

+# mode: run
+# tag: freelist
 
 cimport cython