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[3.11] GH-94822: Don't specialize when metaclasses are involved (GH-94892) #94980

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merged 1 commit into from
Jul 18, 2022
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[3.11] GH-94822: Don't specialize when metaclasses are involved (GH-94892) #94980

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344 changes: 344 additions & 0 deletions Lib/test/test_opcache.py
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
import unittest


class TestLoadAttrCache(unittest.TestCase):
def test_descriptor_added_after_optimization(self):
class Descriptor:
Expand All @@ -21,3 +22,346 @@ def f(o):
Descriptor.__set__ = lambda *args: None

self.assertEqual(f(o), 2)

def test_metaclass_descriptor_added_after_optimization(self):
class Descriptor:
pass

class Metaclass(type):
attribute = Descriptor()

class Class(metaclass=Metaclass):
attribute = True

def __get__(self, instance, owner):
return False

def __set__(self, instance, value):
return None

def f():
return Class.attribute

for _ in range(1025):
self.assertTrue(f())

Descriptor.__get__ = __get__
Descriptor.__set__ = __set__

for _ in range(1025):
self.assertFalse(f())

def test_metaclass_descriptor_shadows_class_attribute(self):
class Metaclass(type):
@property
def attribute(self):
return True

class Class(metaclass=Metaclass):
attribute = False

def f():
return Class.attribute

for _ in range(1025):
self.assertTrue(f())

def test_metaclass_set_descriptor_after_optimization(self):
class Metaclass(type):
pass

class Class(metaclass=Metaclass):
attribute = True

@property
def attribute(self):
return False

def f():
return Class.attribute

for _ in range(1025):
self.assertTrue(f())

Metaclass.attribute = attribute

for _ in range(1025):
self.assertFalse(f())

def test_metaclass_del_descriptor_after_optimization(self):
class Metaclass(type):
@property
def attribute(self):
return True

class Class(metaclass=Metaclass):
attribute = False

def f():
return Class.attribute

for _ in range(1025):
self.assertTrue(f())

del Metaclass.attribute

for _ in range(1025):
self.assertFalse(f())

def test_type_descriptor_shadows_attribute_method(self):
class Class:
mro = None

def f():
return Class.mro

for _ in range(1025):
self.assertIsNone(f())

def test_type_descriptor_shadows_attribute_member(self):
class Class:
__base__ = None

def f():
return Class.__base__

for _ in range(1025):
self.assertIs(f(), object)

def test_type_descriptor_shadows_attribute_getset(self):
class Class:
__name__ = "Spam"

def f():
return Class.__name__

for _ in range(1025):
self.assertEqual(f(), "Class")

def test_metaclass_getattribute(self):
class Metaclass(type):
def __getattribute__(self, name):
return True

class Class(metaclass=Metaclass):
attribute = False

def f():
return Class.attribute

for _ in range(1025):
self.assertTrue(f())

def test_metaclass_swap(self):
class OldMetaclass(type):
@property
def attribute(self):
return True

class NewMetaclass(type):
@property
def attribute(self):
return False

class Class(metaclass=OldMetaclass):
pass

def f():
return Class.attribute

for _ in range(1025):
self.assertTrue(f())

Class.__class__ = NewMetaclass

for _ in range(1025):
self.assertFalse(f())


class TestLoadMethodCache(unittest.TestCase):
def test_descriptor_added_after_optimization(self):
class Descriptor:
pass

class Class:
attribute = Descriptor()

def __get__(self, instance, owner):
return lambda: False

def __set__(self, instance, value):
return None

def attribute():
return True

instance = Class()
instance.attribute = attribute

def f():
return instance.attribute()

for _ in range(1025):
self.assertTrue(f())

Descriptor.__get__ = __get__
Descriptor.__set__ = __set__

for _ in range(1025):
self.assertFalse(f())

def test_metaclass_descriptor_added_after_optimization(self):
class Descriptor:
pass

class Metaclass(type):
attribute = Descriptor()

class Class(metaclass=Metaclass):
def attribute():
return True

def __get__(self, instance, owner):
return lambda: False

def __set__(self, instance, value):
return None

def f():
return Class.attribute()

for _ in range(1025):
self.assertTrue(f())

Descriptor.__get__ = __get__
Descriptor.__set__ = __set__

for _ in range(1025):
self.assertFalse(f())

def test_metaclass_descriptor_shadows_class_attribute(self):
class Metaclass(type):
@property
def attribute(self):
return lambda: True

class Class(metaclass=Metaclass):
def attribute():
return False

def f():
return Class.attribute()

for _ in range(1025):
self.assertTrue(f())

def test_metaclass_set_descriptor_after_optimization(self):
class Metaclass(type):
pass

class Class(metaclass=Metaclass):
def attribute():
return True

@property
def attribute(self):
return lambda: False

def f():
return Class.attribute()

for _ in range(1025):
self.assertTrue(f())

Metaclass.attribute = attribute

for _ in range(1025):
self.assertFalse(f())

def test_metaclass_del_descriptor_after_optimization(self):
class Metaclass(type):
@property
def attribute(self):
return lambda: True

class Class(metaclass=Metaclass):
def attribute():
return False

def f():
return Class.attribute()

for _ in range(1025):
self.assertTrue(f())

del Metaclass.attribute

for _ in range(1025):
self.assertFalse(f())

def test_type_descriptor_shadows_attribute_method(self):
class Class:
def mro():
return ["Spam", "eggs"]

def f():
return Class.mro()

for _ in range(1025):
self.assertEqual(f(), ["Spam", "eggs"])

def test_type_descriptor_shadows_attribute_member(self):
class Class:
def __base__():
return "Spam"

def f():
return Class.__base__()

for _ in range(1025):
self.assertNotEqual(f(), "Spam")

def test_metaclass_getattribute(self):
class Metaclass(type):
def __getattribute__(self, name):
return lambda: True

class Class(metaclass=Metaclass):
def attribute():
return False

def f():
return Class.attribute()

for _ in range(1025):
self.assertTrue(f())

def test_metaclass_swap(self):
class OldMetaclass(type):
@property
def attribute(self):
return lambda: True

class NewMetaclass(type):
@property
def attribute(self):
return lambda: False

class Class(metaclass=OldMetaclass):
pass

def f():
return Class.attribute()

for _ in range(1025):
self.assertTrue(f())

Class.__class__ = NewMetaclass

for _ in range(1025):
self.assertFalse(f())


if __name__ == "__main__":
import unittest
unittest.main()
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2022-07-15-22-16-08.gh-issue-94822.zRRzBN.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix an issue where lookups of metaclass descriptors may be ignored when an
identically-named attribute also exists on the class itself.
11 changes: 5 additions & 6 deletions Python/specialize.c
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Original file line number Diff line number Diff line change
Expand Up @@ -871,6 +871,10 @@ specialize_class_load_method(PyObject *owner, _Py_CODEUNIT *instr,
PyObject *name)
{
_PyLoadMethodCache *cache = (_PyLoadMethodCache *)(instr + 1);
if (!PyType_CheckExact(owner) || _PyType_Lookup(Py_TYPE(owner), name)) {
SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_LOAD_METHOD_METACLASS_ATTRIBUTE);
return -1;
}
PyObject *descr = NULL;
DescriptorClassification kind = 0;
kind = analyze_descriptor((PyTypeObject *)owner, name, &descr, 0);
Expand All @@ -883,12 +887,7 @@ specialize_class_load_method(PyObject *owner, _Py_CODEUNIT *instr,
return 0;
#ifdef Py_STATS
case ABSENT:
if (_PyType_Lookup(Py_TYPE(owner), name) != NULL) {
SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_LOAD_METHOD_METACLASS_ATTRIBUTE);
}
else {
SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_EXPECTED_ERROR);
}
SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_EXPECTED_ERROR);
return -1;
#endif
default:
Expand Down