Allow calling builtin_method objects by default (#112)

The type of these objects is a subclass of `types.BuiltinMethodType`, but not
identical to it.  This caused downstream failures on Python >= 3.12 due to
refactoring of the `io` module, such as
zopefoundation/zope.file#13.

CHANGES.rst

@@ -5,6 +5,12 @@
 7.1 (unreleased)
 ----------------
 
+- Allow calling methods of type ``<class 'builtin_method'>`` by default. In
+ particular, Python 3.12 refactored the ``io`` module in such a way as to
+ slightly change the types of some methods, causing ``zope.security`` to no
+ longer consider them callable. See `zope.file issue #13
+ <https:/zopefoundation/zope.file/issues/13>`.
+
 
 7.0 (2024-05-30)
 ----------------

src/zope/security/checker.py

@@ -60,6 +60,7 @@
 import abc
 import datetime
 import decimal
+import io
 import os
 import sys
 import types
@@ -879,6 +880,14 @@ def f(): # pragma: no cover
  types.MethodType: _callableChecker,
  types.BuiltinFunctionType: _callableChecker,
  types.BuiltinMethodType: _callableChecker,
+ # At least on Python 3.5-3.12, types.BuiltinFunctionType and
+ # types.BuiltinMethodType are both <class 'builtin_function_or_method'>,
+ # or PyCFunctionType. However, some builtin methods are <class
+ # 'builtin_method'> instead, or PyCMethodType, which is a subclass of
+ # PyCFunctionType but not identical to it. As of Python 3.12, the io
+ # module makes more use of PyCMethodType, so we can use it to identify
+ # that type.
+ type(io.BytesIO().getbuffer): _callableChecker,
  # method-wrapper
  type(().__repr__): _callableChecker,
  type: _typeChecker,

src/zope/security/tests/test_proxy.py

@@ -13,6 +13,8 @@
 ##############################################################################
 """Security proxy tests
 """
+import io
+import os
 import unittest
 
 from zope.security._compat import PURE_PYTHON
@@ -1815,6 +1817,11 @@ def test_method_wrapper(self):
 
  self.assertEqual(ProxyFactory({}).__repr__(), '{}')
 
+ def test_builtin_method(self):
+ from zope.security.proxy import ProxyFactory
+
+ self.assertEqual(ProxyFactory(io.FileIO(os.devnull, 'rb').read)(), b'')
+
 
 def test_using_mapping_slots_hack():
  """The security proxy will use mapping slots, on the checker to go faster