From 3b65acf8d66e7e42ad25746976b55dc0bd7d71d8 Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Fri, 27 Sep 2024 19:56:36 +0200
Subject: [PATCH 01/17] Improve zero argument support for `super()` in
 dataclasses

---
 Lib/dataclasses.py                            | 64 +++++++++++++++----
 Lib/test/test_dataclasses/__init__.py         | 41 ++++++++++++
 ...4-09-27-19-50-30.gh-issue-90562.HeL_JA.rst |  2 +
 3 files changed, 94 insertions(+), 13 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2024-09-27-19-50-30.gh-issue-90562.HeL_JA.rst

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index bdda7cc6c00f5d..5d2088d7cf9b6c 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1222,11 +1222,6 @@ def _get_slots(cls):
 
 
 def _update_func_cell_for__class__(f, oldcls, newcls):
-    # Returns True if we update a cell, else False.
-    if f is None:
-        # f will be None in the case of a property where not all of
-        # fget, fset, and fdel are used.  Nothing to do in that case.
-        return False
     try:
         idx = f.__code__.co_freevars.index("__class__")
     except ValueError:
@@ -1235,13 +1230,36 @@ def _update_func_cell_for__class__(f, oldcls, newcls):
     # Fix the cell to point to the new class, if it's already pointing
     # at the old class.  I'm not convinced that the "is oldcls" test
     # is needed, but other than performance can't hurt.
-    closure = f.__closure__[idx]
-    if closure.cell_contents is oldcls:
-        closure.cell_contents = newcls
+    cell = f.__closure__[idx]
+    if cell.cell_contents is oldcls:
+        cell.cell_contents = newcls
         return True
     return False
 
 
+def _find_inner_functions(obj, _seen=None, _depth=0):
+    if _seen is None:
+        _seen = set()
+    if id(obj) in _seen:
+        return None
+    _seen.add(id(obj))
+
+    _depth += 1
+    if _depth > 2:
+        return None
+
+    obj = inspect.unwrap(obj)
+
+    for attr in dir(obj):
+        value = getattr(obj, attr, None)
+        if value is None:
+            continue
+        if isinstance(obj, types.FunctionType):
+            yield obj
+            return
+        yield from _find_inner_functions(value, _seen, _depth)
+
+
 def _create_slots(defined_fields, inherited_slots, field_names, weakref_slot):
     # The slots for our class.  Remove slots from our base classes.  Add
     # '__weakref__' if weakref_slot was given, unless it is already present.
@@ -1317,7 +1335,10 @@ def _add_slots(cls, is_frozen, weakref_slot, defined_fields):
     # (the newly created one, which we're returning) and not the
     # original class.  We can break out of this loop as soon as we
     # make an update, since all closures for a class will share a
-    # given cell.
+    # given cell.  First we try to find a pure function/properties,
+    # and then fallback to inspecting custom descriptors.
+
+    custom_descriptors_to_check = []
     for member in newcls.__dict__.values():
         # If this is a wrapped function, unwrap it.
         member = inspect.unwrap(member)
@@ -1326,10 +1347,27 @@ def _add_slots(cls, is_frozen, weakref_slot, defined_fields):
             if _update_func_cell_for__class__(member, cls, newcls):
                 break
         elif isinstance(member, property):
-            if (_update_func_cell_for__class__(member.fget, cls, newcls)
-                or _update_func_cell_for__class__(member.fset, cls, newcls)
-                or _update_func_cell_for__class__(member.fdel, cls, newcls)):
-                break
+            for f in member.fget, member.fset, member.fdel:
+                if f is None:
+                    continue
+                # unwrap once more in case function
+                # was wrapped before it became property
+                f = inspect.unwrap(f)
+                if _update_func_cell_for__class__(f, cls, newcls):
+                    break
+        elif hasattr(member, "__get__") and not inspect.ismemberdescriptor(
+            member
+        ):
+            # we don't want to inspect custom descriptors just yet
+            # there's still a chance we'll encounter a pure function
+            # or a property
+            custom_descriptors_to_check.append(member)
+    else:
+        # now let's ensure custom descriptors won't be left out
+        for descriptor in custom_descriptors_to_check:
+            for f in _find_inner_functions(descriptor):
+                if _update_func_cell_for__class__(f, cls, newcls):
+                    break
 
     return newcls
 
diff --git a/Lib/test/test_dataclasses/__init__.py b/Lib/test/test_dataclasses/__init__.py
index 2984f4261bd2c4..8611cb3dbf7f87 100644
--- a/Lib/test/test_dataclasses/__init__.py
+++ b/Lib/test/test_dataclasses/__init__.py
@@ -5031,6 +5031,47 @@ def foo(self):
 
         A().foo()
 
+    def test_wrapped_property(self):
+        def mydecorator(f):
+            @wraps(f)
+            def wrapper(*args, **kwargs):
+                return f(*args, **kwargs)
+            return wrapper
+
+        class B:
+            @property
+            def foo(self):
+                return "bar"
+
+        @dataclass(slots=True)
+        class A(B):
+            @property
+            @mydecorator
+            def foo(self):
+                return super().foo
+
+        self.assertEqual(A().foo, "bar")
+
+    def test_custom_descriptor(self):
+        class CustomDescriptor:
+            def __init__(self, f):
+                self._f = f
+
+            def __get__(self, instance, owner):
+                return self._f(instance)
+
+        class B:
+            def foo(self):
+                return "bar"
+
+        @dataclass(slots=True)
+        class A(B):
+            @CustomDescriptor
+            def foo(cls):
+                return super().foo()
+
+        self.assertEqual(A().foo, "bar")
+
     def test_remembered_class(self):
         # Apply the dataclass decorator manually (not when the class
         # is created), so that we can keep a reference to the
diff --git a/Misc/NEWS.d/next/Library/2024-09-27-19-50-30.gh-issue-90562.HeL_JA.rst b/Misc/NEWS.d/next/Library/2024-09-27-19-50-30.gh-issue-90562.HeL_JA.rst
new file mode 100644
index 00000000000000..56f2e1109ce5f5
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-09-27-19-50-30.gh-issue-90562.HeL_JA.rst
@@ -0,0 +1,2 @@
+Modify dataclasses to enable zero argument support for ``super()``  when ``slots=True`` is
+specified and custom descriptor is used or `property` function is wrapped.

From efb60954f1dfec5855a53b2369ef6b4232782b86 Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Sat, 28 Sep 2024 00:41:47 +0200
Subject: [PATCH 02/17] Fix NEWS.d formatting

---
 .../next/Library/2024-09-27-19-50-30.gh-issue-90562.HeL_JA.rst  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/Library/2024-09-27-19-50-30.gh-issue-90562.HeL_JA.rst b/Misc/NEWS.d/next/Library/2024-09-27-19-50-30.gh-issue-90562.HeL_JA.rst
index 56f2e1109ce5f5..b0bbdd406f63c7 100644
--- a/Misc/NEWS.d/next/Library/2024-09-27-19-50-30.gh-issue-90562.HeL_JA.rst
+++ b/Misc/NEWS.d/next/Library/2024-09-27-19-50-30.gh-issue-90562.HeL_JA.rst
@@ -1,2 +1,2 @@
 Modify dataclasses to enable zero argument support for ``super()``  when ``slots=True`` is
-specified and custom descriptor is used or `property` function is wrapped.
+specified and custom descriptor is used or ``property`` function is wrapped.

From 3654f51b8295e88b062c691a88b130fb6b90052a Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Sat, 28 Sep 2024 00:42:26 +0200
Subject: [PATCH 03/17] Add explanation for _depth use and tests

---
 Lib/dataclasses.py                    |  3 ++
 Lib/test/test_dataclasses/__init__.py | 68 +++++++++++++++++++++++++++
 2 files changed, 71 insertions(+)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 5d2088d7cf9b6c..215c91858465aa 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1245,6 +1245,9 @@ def _find_inner_functions(obj, _seen=None, _depth=0):
     _seen.add(id(obj))
 
     _depth += 1
+    # we don't want to dive too deep in an object in search for a function.
+    # usually it will be stored on outer levels of nesting, but in just
+    # for sake of special cases when
     if _depth > 2:
         return None
 
diff --git a/Lib/test/test_dataclasses/__init__.py b/Lib/test/test_dataclasses/__init__.py
index 8611cb3dbf7f87..052e3b97df4aa6 100644
--- a/Lib/test/test_dataclasses/__init__.py
+++ b/Lib/test/test_dataclasses/__init__.py
@@ -5072,6 +5072,74 @@ def foo(cls):
 
         self.assertEqual(A().foo, "bar")
 
+    def test_custom_nested_descriptor(self):
+        class CustomFunctionWrapper:
+            def __init__(self, f):
+                self._f = f
+
+            def __call__(self, *args, **kwargs):
+                return self._f(*args, **kwargs)
+
+        class CustomDescriptor:
+            def __init__(self, f):
+                self._wrapper = CustomFunctionWrapper(f)
+
+            def __get__(self, instance, owner):
+                return self._wrapper(instance)
+
+        class B:
+            def foo(self):
+                return "bar"
+
+        @dataclass(slots=True)
+        class A(B):
+            @CustomDescriptor
+            def foo(cls):
+                return super().foo()
+
+        self.assertEqual(A().foo, "bar")
+
+    def test_custom_too_nested_descriptor(self):
+        class UnnecessaryNestedWrapper:
+            def __init__(self, wrapper):
+                self._wrapper = wrapper
+
+            def __call__(self, *args, **kwargs):
+                return self._wrapper(*args, **kwargs)
+
+        class CustomFunctionWrapper:
+            def __init__(self, f):
+                self._f = f
+
+            def __call__(self, *args, **kwargs):
+                return self._f(*args, **kwargs)
+
+        class CustomDescriptor:
+            def __init__(self, f):
+                self._wrapper = UnnecessaryNestedWrapper(CustomFunctionWrapper(f))
+
+            def __get__(self, instance, owner):
+                return self._wrapper(instance)
+
+        class B:
+            def foo(self):
+                return "bar"
+
+        @dataclass(slots=True)
+        class A(B):
+            @CustomDescriptor
+            def foo(cls):
+                return super().foo()
+
+        with self.assertRaises(TypeError) as context:
+            A().foo
+
+        expected_error_message = (
+            'super(type, obj): obj (instance of A) is not '
+            'an instance or subtype of type (A).'
+        )
+        self.assertEqual(context.exception.args, (expected_error_message,))
+
     def test_remembered_class(self):
         # Apply the dataclass decorator manually (not when the class
         # is created), so that we can keep a reference to the

From 19297bc9ee6d8cbfa2c29643f60a544b9155afa6 Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Sat, 28 Sep 2024 00:42:42 +0200
Subject: [PATCH 04/17] Fix incorrect variable reference

---
 Lib/dataclasses.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 215c91858465aa..ea276f761b0f23 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1257,8 +1257,8 @@ def _find_inner_functions(obj, _seen=None, _depth=0):
         value = getattr(obj, attr, None)
         if value is None:
             continue
-        if isinstance(obj, types.FunctionType):
-            yield obj
+        if isinstance(value, types.FunctionType):
+            yield value
             return
         yield from _find_inner_functions(value, _seen, _depth)
 

From 2606480ffa4ac986cf532d1a1778281d4f1d8446 Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Sat, 28 Sep 2024 00:55:01 +0200
Subject: [PATCH 05/17] Correctly unwrap descriptor function

---
 Lib/dataclasses.py                    |  4 +---
 Lib/test/test_dataclasses/__init__.py | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index ea276f761b0f23..8413c7c09438ec 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1251,14 +1251,12 @@ def _find_inner_functions(obj, _seen=None, _depth=0):
     if _depth > 2:
         return None
 
-    obj = inspect.unwrap(obj)
-
     for attr in dir(obj):
         value = getattr(obj, attr, None)
         if value is None:
             continue
         if isinstance(value, types.FunctionType):
-            yield value
+            yield inspect.unwrap(value)
             return
         yield from _find_inner_functions(value, _seen, _depth)
 
diff --git a/Lib/test/test_dataclasses/__init__.py b/Lib/test/test_dataclasses/__init__.py
index 052e3b97df4aa6..45f291d7aa6ad7 100644
--- a/Lib/test/test_dataclasses/__init__.py
+++ b/Lib/test/test_dataclasses/__init__.py
@@ -13,6 +13,7 @@
 import weakref
 import traceback
 import unittest
+from functools import update_wrapper
 from unittest.mock import Mock
 from typing import ClassVar, Any, List, Union, Tuple, Dict, Generic, TypeVar, Optional, Protocol, DefaultDict
 from typing import get_type_hints
@@ -5072,6 +5073,26 @@ def foo(cls):
 
         self.assertEqual(A().foo, "bar")
 
+    def test_custom_descriptor_wrapped(self):
+        class CustomDescriptor:
+            def __init__(self, f):
+                self._f = update_wrapper(lambda *args, **kwargs: f(*args, **kwargs), f)
+
+            def __get__(self, instance, owner):
+                return self._f(instance)
+
+        class B:
+            def foo(self):
+                return "bar"
+
+        @dataclass(slots=True)
+        class A(B):
+            @CustomDescriptor
+            def foo(cls):
+                return super().foo()
+
+        self.assertEqual(A().foo, "bar")
+
     def test_custom_nested_descriptor(self):
         class CustomFunctionWrapper:
             def __init__(self, f):

From 42f9dc3f8f5e5ce1502d3e7b6059f34908249d79 Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Sat, 28 Sep 2024 00:55:48 +0200
Subject: [PATCH 06/17] Add test with using partial as custom wrapper

---
 Lib/test/test_dataclasses/__init__.py | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Lib/test/test_dataclasses/__init__.py b/Lib/test/test_dataclasses/__init__.py
index 45f291d7aa6ad7..84f049d1f67ff3 100644
--- a/Lib/test/test_dataclasses/__init__.py
+++ b/Lib/test/test_dataclasses/__init__.py
@@ -13,6 +13,7 @@
 import weakref
 import traceback
 import unittest
+from functools import partial
 from functools import update_wrapper
 from unittest.mock import Mock
 from typing import ClassVar, Any, List, Union, Tuple, Dict, Generic, TypeVar, Optional, Protocol, DefaultDict
@@ -5120,6 +5121,26 @@ def foo(cls):
 
         self.assertEqual(A().foo, "bar")
 
+    def test_custom_nested_descriptor_with_partial(self):
+        class CustomDescriptor:
+            def __init__(self, f):
+                self._wrapper = partial(f, value="bar")
+
+            def __get__(self, instance, owner):
+                return self._wrapper(instance)
+
+        class B:
+            def foo(self, value):
+                return value
+
+        @dataclass(slots=True)
+        class A(B):
+            @CustomDescriptor
+            def foo(self, value):
+                return super().foo(value)
+
+        self.assertEqual(A().foo, "bar")
+
     def test_custom_too_nested_descriptor(self):
         class UnnecessaryNestedWrapper:
             def __init__(self, wrapper):

From 53c18d114b34c847247013a1e3e6f2b54cdbf707 Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Sat, 28 Sep 2024 01:03:03 +0200
Subject: [PATCH 07/17] Rephrase comment explaining _depth argument

---
 Lib/dataclasses.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 8413c7c09438ec..7f6e55112b44b6 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1245,9 +1245,10 @@ def _find_inner_functions(obj, _seen=None, _depth=0):
     _seen.add(id(obj))
 
     _depth += 1
-    # we don't want to dive too deep in an object in search for a function.
-    # usually it will be stored on outer levels of nesting, but in just
-    # for sake of special cases when
+    # normally just inspection of a descriptor object itself should be enough,
+    # and we should encounter the function as its attribute,
+    # but in case function was wrapped (e.g. functools.partition was used),
+    # we want to dive at least one level deeper
     if _depth > 2:
         return None
 

From 96d5315531573932f9fa99a722c14d1d2d952121 Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Sat, 28 Sep 2024 01:18:02 +0200
Subject: [PATCH 08/17] Add clarification for function search priority

---
 Lib/dataclasses.py | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 7f6e55112b44b6..826e2c97903117 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1337,8 +1337,9 @@ def _add_slots(cls, is_frozen, weakref_slot, defined_fields):
     # (the newly created one, which we're returning) and not the
     # original class.  We can break out of this loop as soon as we
     # make an update, since all closures for a class will share a
-    # given cell.  First we try to find a pure function/properties,
-    # and then fallback to inspecting custom descriptors.
+    # given cell.  First we try to find a pure function or a property,
+    # and then fallback to inspecting custom descriptors
+    # if no pure function or property is found.
 
     custom_descriptors_to_check = []
     for member in newcls.__dict__.values():
@@ -1360,9 +1361,9 @@ def _add_slots(cls, is_frozen, weakref_slot, defined_fields):
         elif hasattr(member, "__get__") and not inspect.ismemberdescriptor(
             member
         ):
-            # we don't want to inspect custom descriptors just yet
+            # We don't want to inspect custom descriptors just yet
             # there's still a chance we'll encounter a pure function
-            # or a property
+            # or a property and won't have to use slower recursive search.
             custom_descriptors_to_check.append(member)
     else:
         # now let's ensure custom descriptors won't be left out

From 22eeb8f762e1819762843e5f5b725ae89b2af26f Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Sat, 28 Sep 2024 01:21:52 +0200
Subject: [PATCH 09/17] Ues consistent grammar throughout comments

---
 Lib/dataclasses.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 826e2c97903117..5587acffcf28b3 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1245,10 +1245,10 @@ def _find_inner_functions(obj, _seen=None, _depth=0):
     _seen.add(id(obj))
 
     _depth += 1
-    # normally just inspection of a descriptor object itself should be enough,
+    # Normally just inspection of a descriptor object itself should be enough,
     # and we should encounter the function as its attribute,
     # but in case function was wrapped (e.g. functools.partition was used),
-    # we want to dive at least one level deeper
+    # we want to dive at least one level deeper.
     if _depth > 2:
         return None
 
@@ -1353,8 +1353,8 @@ def _add_slots(cls, is_frozen, weakref_slot, defined_fields):
             for f in member.fget, member.fset, member.fdel:
                 if f is None:
                     continue
-                # unwrap once more in case function
-                # was wrapped before it became property
+                # Unwrap once more in case function
+                # was wrapped before it became property.
                 f = inspect.unwrap(f)
                 if _update_func_cell_for__class__(f, cls, newcls):
                     break
@@ -1366,7 +1366,7 @@ def _add_slots(cls, is_frozen, weakref_slot, defined_fields):
             # or a property and won't have to use slower recursive search.
             custom_descriptors_to_check.append(member)
     else:
-        # now let's ensure custom descriptors won't be left out
+        # Now let's ensure custom descriptors won't be left out.
         for descriptor in custom_descriptors_to_check:
             for f in _find_inner_functions(descriptor):
                 if _update_func_cell_for__class__(f, cls, newcls):

From e91c28bcafcd2efc26be3c1822b40920b71cc6c7 Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Sat, 28 Sep 2024 01:35:46 +0200
Subject: [PATCH 10/17] Fix breaking out from outer loop when handling property

---
 Lib/dataclasses.py                    |  3 ++
 Lib/test/test_dataclasses/__init__.py | 46 +++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 5587acffcf28b3..4883cff2cd4f46 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1358,6 +1358,9 @@ def _add_slots(cls, is_frozen, weakref_slot, defined_fields):
                 f = inspect.unwrap(f)
                 if _update_func_cell_for__class__(f, cls, newcls):
                     break
+            else:
+                continue
+            break
         elif hasattr(member, "__get__") and not inspect.ismemberdescriptor(
             member
         ):
diff --git a/Lib/test/test_dataclasses/__init__.py b/Lib/test/test_dataclasses/__init__.py
index 84f049d1f67ff3..09aeb0077ce4cc 100644
--- a/Lib/test/test_dataclasses/__init__.py
+++ b/Lib/test/test_dataclasses/__init__.py
@@ -5141,6 +5141,52 @@ def foo(self, value):
 
         self.assertEqual(A().foo, "bar")
 
+    def test_pure_functions_preferred_to_custom_descriptors(self):
+        class CustomDescriptor:
+            def __init__(self, f):
+                self._wrapper = partial(f, value="bar")
+
+            def __get__(self, instance, owner):
+                return self._wrapper(instance)
+
+            def __dir__(self):
+                raise RuntimeError("Never should be accessed")
+
+        class B:
+            def foo(self, value):
+                return value
+
+        with self.assertRaises(RuntimeError) as context:
+            @dataclass(slots=True)
+            class A(B):
+                @CustomDescriptor
+                def foo(self, value): ...
+
+        self.assertEqual(context.exception.args, ("Never should be accessed",))
+
+        @dataclass(slots=True)
+        class A(B):
+            @CustomDescriptor
+            def foo(self, value):
+                return super().foo(value)
+
+            @property
+            def bar(self):
+                return super()
+
+        self.assertEqual(A().foo, "bar")
+
+        @dataclass(slots=True)
+        class A(B):
+            @CustomDescriptor
+            def foo(self, value):
+                return super().foo(value)
+
+            def bar(self):
+                return super()
+
+        self.assertEqual(A().foo, "bar")
+
     def test_custom_too_nested_descriptor(self):
         class UnnecessaryNestedWrapper:
             def __init__(self, wrapper):

From 4941a3fdb2d1f23c55b8d45968a78dc2e074ebd1 Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Sat, 28 Sep 2024 01:39:39 +0200
Subject: [PATCH 11/17] Use generator expression with any() instead of classic
 loop

---
 Lib/dataclasses.py | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 4883cff2cd4f46..65891c0c00e8eb 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1349,17 +1349,15 @@ def _add_slots(cls, is_frozen, weakref_slot, defined_fields):
         if isinstance(member, types.FunctionType):
             if _update_func_cell_for__class__(member, cls, newcls):
                 break
-        elif isinstance(member, property):
-            for f in member.fget, member.fset, member.fdel:
-                if f is None:
-                    continue
+        elif isinstance(member, property) and (
+            any(
                 # Unwrap once more in case function
                 # was wrapped before it became property.
-                f = inspect.unwrap(f)
-                if _update_func_cell_for__class__(f, cls, newcls):
-                    break
-            else:
-                continue
+                _update_func_cell_for__class__(inspect.unwrap(f), cls, newcls)
+                for f in (member.fget, member.fset, member.fdel)
+                if f is not None
+            )
+        ):
             break
         elif hasattr(member, "__get__") and not inspect.ismemberdescriptor(
             member

From d33070f21ef0d393e57d88ce246bc3d9b1c493cf Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Sat, 28 Sep 2024 13:03:14 +0200
Subject: [PATCH 12/17] Apply suggestions from code review

Co-authored-by: sobolevn <mail@sobolevn.me>
---
 Lib/dataclasses.py                    | 4 ++--
 Lib/test/test_dataclasses/__init__.py | 3 +--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 65891c0c00e8eb..ed68a61ede1582 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1245,9 +1245,9 @@ def _find_inner_functions(obj, _seen=None, _depth=0):
     _seen.add(id(obj))
 
     _depth += 1
-    # Normally just inspection of a descriptor object itself should be enough,
+    # Normally just an inspection of a descriptor object itself should be enough,
     # and we should encounter the function as its attribute,
-    # but in case function was wrapped (e.g. functools.partition was used),
+    # but in case function was wrapped (e.g. functools.partial was used),
     # we want to dive at least one level deeper.
     if _depth > 2:
         return None
diff --git a/Lib/test/test_dataclasses/__init__.py b/Lib/test/test_dataclasses/__init__.py
index 09aeb0077ce4cc..889a669f94780d 100644
--- a/Lib/test/test_dataclasses/__init__.py
+++ b/Lib/test/test_dataclasses/__init__.py
@@ -13,8 +13,7 @@
 import weakref
 import traceback
 import unittest
-from functools import partial
-from functools import update_wrapper
+from functools import partial, update_wrapper
 from unittest.mock import Mock
 from typing import ClassVar, Any, List, Union, Tuple, Dict, Generic, TypeVar, Optional, Protocol, DefaultDict
 from typing import get_type_hints

From c26e978cce86e079a6c0fdfb4ab615952536955f Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Sat, 28 Sep 2024 13:09:13 +0200
Subject: [PATCH 13/17] Remove leading underscores from seen and depth args

---
 Lib/dataclasses.py | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index ed68a61ede1582..d9832f42b6cdbe 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1237,19 +1237,19 @@ def _update_func_cell_for__class__(f, oldcls, newcls):
     return False
 
 
-def _find_inner_functions(obj, _seen=None, _depth=0):
-    if _seen is None:
-        _seen = set()
-    if id(obj) in _seen:
+def _find_inner_functions(obj, seen=None, depth=0):
+    if seen is None:
+        seen = set()
+    if id(obj) in seen:
         return None
-    _seen.add(id(obj))
+    seen.add(id(obj))
 
-    _depth += 1
+    depth += 1
     # Normally just an inspection of a descriptor object itself should be enough,
     # and we should encounter the function as its attribute,
     # but in case function was wrapped (e.g. functools.partial was used),
     # we want to dive at least one level deeper.
-    if _depth > 2:
+    if depth > 2:
         return None
 
     for attr in dir(obj):
@@ -1259,7 +1259,7 @@ def _find_inner_functions(obj, _seen=None, _depth=0):
         if isinstance(value, types.FunctionType):
             yield inspect.unwrap(value)
             return
-        yield from _find_inner_functions(value, _seen, _depth)
+        yield from _find_inner_functions(value, seen, depth)
 
 
 def _create_slots(defined_fields, inherited_slots, field_names, weakref_slot):

From d0173d8e39bf6d2b91995aba774bf744bb7ce193 Mon Sep 17 00:00:00 2001
From: Arseny Boykov <36469655+Bobronium@users.noreply.github.com>
Date: Sat, 28 Sep 2024 22:37:06 +0200
Subject: [PATCH 14/17] Prevent user-defined code execution during attribute
 scanning

---
 Lib/dataclasses.py                    | 24 +++++++++++---
 Lib/test/test_dataclasses/__init__.py | 46 ---------------------------
 2 files changed, 20 insertions(+), 50 deletions(-)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index d9832f42b6cdbe..b381bd07f1b7d6 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1237,6 +1237,25 @@ def _update_func_cell_for__class__(f, oldcls, newcls):
     return False
 
 
+def _safe_get_attributes(obj):
+    # we should avoid triggering any user-defined code
+    # when inspecting attributes if possible
+
+    # look for __slots__ descriptors
+    type_dict = object.__getattribute__(type(obj), "__dict__")
+    for value in type_dict.values():
+        if isinstance(value, types.MemberDescriptorType):
+            yield value.__get__(obj)
+
+    instance_dict_descriptor = type_dict.get("__dict__", None)
+    if not isinstance(instance_dict_descriptor, types.GetSetDescriptorType):
+        # __dict__ is either not present, or redefined by user
+        # as custom descriptor, either way, we're done here
+        return
+
+    yield from instance_dict_descriptor.__get__(obj).values()
+
+
 def _find_inner_functions(obj, seen=None, depth=0):
     if seen is None:
         seen = set()
@@ -1252,10 +1271,7 @@ def _find_inner_functions(obj, seen=None, depth=0):
     if depth > 2:
         return None
 
-    for attr in dir(obj):
-        value = getattr(obj, attr, None)
-        if value is None:
-            continue
+    for value in _safe_get_attributes(obj):
         if isinstance(value, types.FunctionType):
             yield inspect.unwrap(value)
             return
diff --git a/Lib/test/test_dataclasses/__init__.py b/Lib/test/test_dataclasses/__init__.py
index 889a669f94780d..57622f77029668 100644
--- a/Lib/test/test_dataclasses/__init__.py
+++ b/Lib/test/test_dataclasses/__init__.py
@@ -5140,52 +5140,6 @@ def foo(self, value):
 
         self.assertEqual(A().foo, "bar")
 
-    def test_pure_functions_preferred_to_custom_descriptors(self):
-        class CustomDescriptor:
-            def __init__(self, f):
-                self._wrapper = partial(f, value="bar")
-
-            def __get__(self, instance, owner):
-                return self._wrapper(instance)
-
-            def __dir__(self):
-                raise RuntimeError("Never should be accessed")
-
-        class B:
-            def foo(self, value):
-                return value
-
-        with self.assertRaises(RuntimeError) as context:
-            @dataclass(slots=True)
-            class A(B):
-                @CustomDescriptor
-                def foo(self, value): ...
-
-        self.assertEqual(context.exception.args, ("Never should be accessed",))
-
-        @dataclass(slots=True)
-        class A(B):
-            @CustomDescriptor
-            def foo(self, value):
-                return super().foo(value)
-
-            @property
-            def bar(self):
-                return super()
-
-        self.assertEqual(A().foo, "bar")
-
-        @dataclass(slots=True)
-        class A(B):
-            @CustomDescriptor
-            def foo(self, value):
-                return super().foo(value)
-
-            def bar(self):
-                return super()
-
-        self.assertEqual(A().foo, "bar")
-
     def test_custom_too_nested_descriptor(self):
         class UnnecessaryNestedWrapper:
             def __init__(self, wrapper):

From c68b4cc08f3048703c92422071afa8977eae0a47 Mon Sep 17 00:00:00 2001
From: Arseny Boykov <appkiller16@gmail.com>
Date: Sat, 5 Oct 2024 14:41:17 +0200
Subject: [PATCH 15/17] Use inspect.getattr_static instead of
 _safe_get_attributes

This uses builtins.dir, which will trigger custom __getattibute__ if any, and will trigger __get__ on __dict__ descriptor.
---
 Lib/dataclasses.py                    | 39 ++++++++++++---------------
 Lib/test/test_dataclasses/__init__.py | 39 +++++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 22 deletions(-)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index b381bd07f1b7d6..bf5f095b3292f0 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1237,25 +1237,6 @@ def _update_func_cell_for__class__(f, oldcls, newcls):
     return False
 
 
-def _safe_get_attributes(obj):
-    # we should avoid triggering any user-defined code
-    # when inspecting attributes if possible
-
-    # look for __slots__ descriptors
-    type_dict = object.__getattribute__(type(obj), "__dict__")
-    for value in type_dict.values():
-        if isinstance(value, types.MemberDescriptorType):
-            yield value.__get__(obj)
-
-    instance_dict_descriptor = type_dict.get("__dict__", None)
-    if not isinstance(instance_dict_descriptor, types.GetSetDescriptorType):
-        # __dict__ is either not present, or redefined by user
-        # as custom descriptor, either way, we're done here
-        return
-
-    yield from instance_dict_descriptor.__get__(obj).values()
-
-
 def _find_inner_functions(obj, seen=None, depth=0):
     if seen is None:
         seen = set()
@@ -1271,11 +1252,25 @@ def _find_inner_functions(obj, seen=None, depth=0):
     if depth > 2:
         return None
 
-    for value in _safe_get_attributes(obj):
+    for attribute in dir(obj):
+        try:
+            value = inspect.getattr_static(obj, attribute)
+        except AttributeError:
+            continue
+        builtin_value = inspect.getattr_static(object, attribute, None)
+        if value is builtin_value:
+            # don't waste time on builtin objects
+            continue
+        if (
+            # isinstance() would trigger `value.__getattribute__("__class__")`
+            type(value) is types.MemberDescriptorType
+            and type not in inspect._static_getmro(type(obj))
+        ):
+            value = value.__get__(obj)
         if isinstance(value, types.FunctionType):
             yield inspect.unwrap(value)
-            return
-        yield from _find_inner_functions(value, seen, depth)
+        else:
+            yield from _find_inner_functions(value, seen, depth)
 
 
 def _create_slots(defined_fields, inherited_slots, field_names, weakref_slot):
diff --git a/Lib/test/test_dataclasses/__init__.py b/Lib/test/test_dataclasses/__init__.py
index 57622f77029668..3cb2dc8ce5e0f5 100644
--- a/Lib/test/test_dataclasses/__init__.py
+++ b/Lib/test/test_dataclasses/__init__.py
@@ -5181,6 +5181,45 @@ def foo(cls):
         )
         self.assertEqual(context.exception.args, (expected_error_message,))
 
+    def test_user_defined_code_execution(self):
+        class CustomDescriptor:
+            def __init__(self, f):
+                self._wrapper = partial(f, value="bar")
+
+            def __get__(self, instance, owner):
+                return object.__getattribute__(self, "_wrapper")(instance)
+
+            def __getattribute__(self, name):
+                if name in {
+                    # these are the bare minimum for the feature to work
+                    "__class__",  # accessed on `isinstance(value, Field)`
+                    "__wrapped__",  # accessed by unwrap
+                    "__get__",  # is required for the descriptor protocol
+                    "__dict__",  # is accessed by dir() to work
+                }:
+                   return object.__getattribute__(self, name)
+                raise RuntimeError(f"Never should be accessed: {name}")
+
+        class B:
+            def foo(self, value):
+                return value
+
+        @dataclass(slots=True)
+        class A(B):
+            @CustomDescriptor
+            def foo(self, value):
+                return super().foo(value)
+
+        self.assertEqual(A().foo, "bar")
+
+        @dataclass(slots=True)
+        class A(B):
+            @CustomDescriptor
+            def foo(self, value):
+                return super().foo(value)
+
+        self.assertEqual(A().foo, "bar")
+
     def test_remembered_class(self):
         # Apply the dataclass decorator manually (not when the class
         # is created), so that we can keep a reference to the

From 7d679f226d74975a2c4498873a52fe0c1d5e0818 Mon Sep 17 00:00:00 2001
From: Arseny Boykov <appkiller16@gmail.com>
Date: Sat, 5 Oct 2024 14:51:01 +0200
Subject: [PATCH 16/17] Put back the comment in _update_func_cell_for__class__

---
 Lib/dataclasses.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index bf5f095b3292f0..8c8cd49218c21f 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1222,6 +1222,7 @@ def _get_slots(cls):
 
 
 def _update_func_cell_for__class__(f, oldcls, newcls):
+    # Returns True if we update a cell, else False.
     try:
         idx = f.__code__.co_freevars.index("__class__")
     except ValueError:

From 5bfea4d299566099b780f0bd17e616b157d41046 Mon Sep 17 00:00:00 2001
From: Arseny Boykov <appkiller16@gmail.com>
Date: Sat, 5 Oct 2024 15:16:54 +0200
Subject: [PATCH 17/17] Rely on inspect.getmembers_static()

---
 Lib/dataclasses.py | 38 +++++++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 8c8cd49218c21f..9aa84d0fa15718 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1238,6 +1238,22 @@ def _update_func_cell_for__class__(f, oldcls, newcls):
     return False
 
 
+_object_members_values = {
+    value for name, value in
+    (
+        *inspect.getmembers_static(object),
+        *inspect.getmembers_static(object())
+     )
+}
+
+
+def _is_not_object_member(v):
+    try:
+        return v not in _object_members_values
+    except TypeError:
+        return True
+
+
 def _find_inner_functions(obj, seen=None, depth=0):
     if seen is None:
         seen = set()
@@ -1253,22 +1269,14 @@ def _find_inner_functions(obj, seen=None, depth=0):
     if depth > 2:
         return None
 
-    for attribute in dir(obj):
-        try:
-            value = inspect.getattr_static(obj, attribute)
-        except AttributeError:
-            continue
-        builtin_value = inspect.getattr_static(object, attribute, None)
-        if value is builtin_value:
-            # don't waste time on builtin objects
-            continue
-        if (
-            # isinstance() would trigger `value.__getattribute__("__class__")`
-            type(value) is types.MemberDescriptorType
-            and type not in inspect._static_getmro(type(obj))
-        ):
+    obj_is_type_instance = type in inspect._static_getmro(type(obj))
+    for _, value in inspect.getmembers_static(obj, _is_not_object_member):
+        value_type = type(value)
+        if value_type is types.MemberDescriptorType and not obj_is_type_instance:
             value = value.__get__(obj)
-        if isinstance(value, types.FunctionType):
+            value_type = type(value)
+
+        if value_type is types.FunctionType:
             yield inspect.unwrap(value)
         else:
             yield from _find_inner_functions(value, seen, depth)