From de0962bb5693043e6cad75567668417366c31675 Mon Sep 17 00:00:00 2001
From: Yurii Karabas <1998uriyyo@gmail.com>
Date: Sun, 27 Dec 2020 18:16:15 +0200
Subject: [PATCH 1/8] Add `name` attribute to `property` class

---
 Doc/howto/descriptor.rst                      | 29 ++++++---
 Lib/test/test_property.py                     | 40 +++++++++++++
 Lib/test/test_sys.py                          |  2 +-
 .../2020-12-27-18-07-43.bpo-27794.sxgfGi.rst  |  2 +
 Objects/clinic/descrobject.c.h                | 25 +++++---
 Objects/descrobject.c                         | 60 ++++++++++++++++---
 6 files changed, 133 insertions(+), 25 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2020-12-27-18-07-43.bpo-27794.sxgfGi.rst

diff --git a/Doc/howto/descriptor.rst b/Doc/howto/descriptor.rst
index ab5a573c6a06d1..9d128a6fe582ec 100644
--- a/Doc/howto/descriptor.rst
+++ b/Doc/howto/descriptor.rst
@@ -907,7 +907,7 @@ Properties
 Calling :func:`property` is a succinct way of building a data descriptor that
 triggers a function call upon access to an attribute.  Its signature is::
 
-    property(fget=None, fset=None, fdel=None, doc=None) -> property
+    property(fget=None, fset=None, fdel=None, doc=None, name=None) -> property
 
 The documentation shows a typical use to define a managed attribute ``x``:
 
@@ -927,39 +927,52 @@ here is a pure Python equivalent:
     class Property:
         "Emulate PyProperty_Type() in Objects/descrobject.c"
 
-        def __init__(self, fget=None, fset=None, fdel=None, doc=None):
+        def __init__(self, fget=None, fset=None, fdel=None, doc=None, name=None):
             self.fget = fget
             self.fset = fset
             self.fdel = fdel
             if doc is None and fget is not None:
                 doc = fget.__doc__
             self.__doc__ = doc
+            self.name = name
+
+        def __set_name__(self, owner, name):
+            self.name = name
 
         def __get__(self, obj, objtype=None):
             if obj is None:
                 return self
             if self.fget is None:
-                raise AttributeError("unreadable attribute")
+                raise AttributeError(
+                    "unreadable attribute" +
+                    (" " + self.name if self.name is not None else "")
+                )
             return self.fget(obj)
 
         def __set__(self, obj, value):
             if self.fset is None:
-                raise AttributeError("can't set attribute")
+                raise AttributeError(
+                    "can't set attribute" +
+                    (" " + self.name if self.name is not None else "")
+                )
             self.fset(obj, value)
 
         def __delete__(self, obj):
             if self.fdel is None:
-                raise AttributeError("can't delete attribute")
+                raise AttributeError(
+                    "can't delete attribute" +
+                    (" " + self.name if self.name is not None else "")
+                )
             self.fdel(obj)
 
         def getter(self, fget):
-            return type(self)(fget, self.fset, self.fdel, self.__doc__)
+            return type(self)(fget, self.fset, self.fdel, self.__doc__, self.name)
 
         def setter(self, fset):
-            return type(self)(self.fget, fset, self.fdel, self.__doc__)
+            return type(self)(self.fget, fset, self.fdel, self.__doc__, self.name)
 
         def deleter(self, fdel):
-            return type(self)(self.fget, self.fset, fdel, self.__doc__)
+            return type(self)(self.fget, self.fset, fdel, self.__doc__, self.name)
 
 .. testcode::
     :hide:
diff --git a/Lib/test/test_property.py b/Lib/test/test_property.py
index 172737ade143fa..c7a4bdc3165f75 100644
--- a/Lib/test/test_property.py
+++ b/Lib/test/test_property.py
@@ -299,6 +299,46 @@ def spam(self):
         self.assertEqual(Foo.spam.__doc__, "a new docstring")
 
 
+class _PropertyUnreachableAttribute:
+    obj = None
+    prop = None
+
+    def _format_exc_msg(self, msg):
+        if self.prop.name is None:
+            return msg
+
+        return "{} {}".format(msg, self.prop.name)
+
+    def setUpClass(self):
+        class TestCls:
+            foo = self.prop
+
+        self.obj = TestCls()
+
+    def test_get_property(self):
+        with self.assertRaisesRegex(AttributeError, self._format_exc_msg("unreadable attribute")):
+            self.obj.foo
+
+    def test_set_property(self):
+        with self.assertRaisesRegex(AttributeError, self._format_exc_msg("can't set attribute")):
+            self.obj.foo = None
+
+    def test_del_property(self):
+        with self.assertRaisesRegex(AttributeError, self._format_exc_msg("can't delete attribute")):
+            del self.obj.foo
+
+
+class PropertyUnreachableAttributeWithName(_PropertyUnreachableAttribute, unittest.TestCase):
+    def setUpClass(self):
+        self.prop = property(name='foo')
+        super().setUpClass()
+
+
+class PropertyUnreachableAttributeNoName(_PropertyUnreachableAttribute, unittest.TestCase):
+    def setUpClass(self):
+        self.prop = property()
+        super().setUpClass()
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 3860656c181c2b..3af5b117affde6 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -1329,7 +1329,7 @@ def getx(self): return self.__x
             def setx(self, value): self.__x = value
             def delx(self): del self.__x
             x = property(getx, setx, delx, "")
-            check(x, size('4Pi'))
+            check(x, size('5Pi'))
         # PyCapsule
         # XXX
         # rangeiterator
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-12-27-18-07-43.bpo-27794.sxgfGi.rst b/Misc/NEWS.d/next/Core and Builtins/2020-12-27-18-07-43.bpo-27794.sxgfGi.rst
new file mode 100644
index 00000000000000..4c125ba80a5669
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-12-27-18-07-43.bpo-27794.sxgfGi.rst	
@@ -0,0 +1,2 @@
+Add ``name`` attribute to ``property`` class to add more information when
+``AttributeError`` exception raised. Patch provided by Yurii Karabas.
diff --git a/Objects/clinic/descrobject.c.h b/Objects/clinic/descrobject.c.h
index d248b91bf48da2..4eaa19c07107a0 100644
--- a/Objects/clinic/descrobject.c.h
+++ b/Objects/clinic/descrobject.c.h
@@ -28,7 +28,7 @@ mappingproxy_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
 }
 
 PyDoc_STRVAR(property_init__doc__,
-"property(fget=None, fset=None, fdel=None, doc=None)\n"
+"property(fget=None, fset=None, fdel=None, doc=None, name=None)\n"
 "--\n"
 "\n"
 "Property attribute.\n"
@@ -41,6 +41,8 @@ PyDoc_STRVAR(property_init__doc__,
 "    function to be used for del\'ing an attribute\n"
 "  doc\n"
 "    docstring\n"
+"  name\n"
+"    name of a property\n"
 "\n"
 "Typical use is to define a managed attribute x:\n"
 "\n"
@@ -66,15 +68,15 @@ PyDoc_STRVAR(property_init__doc__,
 
 static int
 property_init_impl(propertyobject *self, PyObject *fget, PyObject *fset,
-                   PyObject *fdel, PyObject *doc);
+                   PyObject *fdel, PyObject *doc, PyObject *name);
 
 static int
 property_init(PyObject *self, PyObject *args, PyObject *kwargs)
 {
     int return_value = -1;
-    static const char * const _keywords[] = {"fget", "fset", "fdel", "doc", NULL};
+    static const char * const _keywords[] = {"fget", "fset", "fdel", "doc", "name", NULL};
     static _PyArg_Parser _parser = {NULL, _keywords, "property", 0};
-    PyObject *argsbuf[4];
+    PyObject *argsbuf[5];
     PyObject * const *fastargs;
     Py_ssize_t nargs = PyTuple_GET_SIZE(args);
     Py_ssize_t noptargs = nargs + (kwargs ? PyDict_GET_SIZE(kwargs) : 0) - 0;
@@ -82,8 +84,9 @@ property_init(PyObject *self, PyObject *args, PyObject *kwargs)
     PyObject *fset = NULL;
     PyObject *fdel = NULL;
     PyObject *doc = NULL;
+    PyObject *name = NULL;
 
-    fastargs = _PyArg_UnpackKeywords(_PyTuple_CAST(args)->ob_item, nargs, kwargs, NULL, &_parser, 0, 4, 0, argsbuf);
+    fastargs = _PyArg_UnpackKeywords(_PyTuple_CAST(args)->ob_item, nargs, kwargs, NULL, &_parser, 0, 5, 0, argsbuf);
     if (!fastargs) {
         goto exit;
     }
@@ -108,11 +111,17 @@ property_init(PyObject *self, PyObject *args, PyObject *kwargs)
             goto skip_optional_pos;
         }
     }
-    doc = fastargs[3];
+    if (fastargs[3]) {
+        doc = fastargs[3];
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
+    name = fastargs[4];
 skip_optional_pos:
-    return_value = property_init_impl((propertyobject *)self, fget, fset, fdel, doc);
+    return_value = property_init_impl((propertyobject *)self, fget, fset, fdel, doc, name);
 
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=916624e717862abc input=a9049054013a1b77]*/
+/*[clinic end generated code: output=562ff56bb7a4dbf0 input=a9049054013a1b77]*/
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index a8ce13c7aa4bab..2329bd4ad34e50 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -1457,13 +1457,14 @@ PyWrapper_New(PyObject *d, PyObject *self)
 /*
 class property(object):
 
-    def __init__(self, fget=None, fset=None, fdel=None, doc=None):
+    def __init__(self, fget=None, fset=None, fdel=None, doc=None, name=None):
         if doc is None and fget is not None and hasattr(fget, "__doc__"):
             doc = fget.__doc__
         self.__get = fget
         self.__set = fset
         self.__del = fdel
         self.__doc__ = doc
+        self.name = name
 
     def __get__(self, inst, type=None):
         if inst is None:
@@ -1490,6 +1491,7 @@ typedef struct {
     PyObject *prop_set;
     PyObject *prop_del;
     PyObject *prop_doc;
+    PyObject *prop_name;
     int getter_doc;
 } propertyobject;
 
@@ -1501,6 +1503,7 @@ static PyMemberDef property_members[] = {
     {"fset", T_OBJECT, offsetof(propertyobject, prop_set), READONLY},
     {"fdel", T_OBJECT, offsetof(propertyobject, prop_del), READONLY},
     {"__doc__",  T_OBJECT, offsetof(propertyobject, prop_doc), 0},
+    {"name",  T_OBJECT, offsetof(propertyobject, prop_name), READONLY},
     {0}
 };
 
@@ -1535,10 +1538,30 @@ property_deleter(PyObject *self, PyObject *deleter)
 }
 
 
+PyDoc_STRVAR(set_name_doc,
+             "Method to set name of a property.");
+
+static PyObject *
+property_set_name(PyObject *self, PyObject *args) {
+    propertyobject *prop = (propertyobject *)self;
+    PyObject *name = PyTuple_GetItem(args, 1);
+
+    if (name == NULL) {
+        return NULL;
+    }
+
+    Py_XINCREF(name);
+    Py_XSETREF(prop->prop_name, name);
+
+    Py_RETURN_NONE;
+}
+
+
 static PyMethodDef property_methods[] = {
     {"getter", property_getter, METH_O, getter_doc},
     {"setter", property_setter, METH_O, setter_doc},
     {"deleter", property_deleter, METH_O, deleter_doc},
+    {"__set_name__", property_set_name, METH_VARARGS, set_name_doc},
     {0}
 };
 
@@ -1553,6 +1576,7 @@ property_dealloc(PyObject *self)
     Py_XDECREF(gs->prop_set);
     Py_XDECREF(gs->prop_del);
     Py_XDECREF(gs->prop_doc);
+    Py_XDECREF(gs->prop_name);
     Py_TYPE(self)->tp_free(self);
 }
 
@@ -1566,7 +1590,12 @@ property_descr_get(PyObject *self, PyObject *obj, PyObject *type)
 
     propertyobject *gs = (propertyobject *)self;
     if (gs->prop_get == NULL) {
-        PyErr_SetString(PyExc_AttributeError, "unreadable attribute");
+        if (gs->prop_name != Py_None) {
+            PyErr_Format(PyExc_AttributeError, "unreadable attribute %S", gs->prop_name);
+        } else {
+            PyErr_SetString(PyExc_AttributeError, "unreadable attribute");
+        }
+
         return NULL;
     }
 
@@ -1584,10 +1613,18 @@ property_descr_set(PyObject *self, PyObject *obj, PyObject *value)
     else
         func = gs->prop_set;
     if (func == NULL) {
-        PyErr_SetString(PyExc_AttributeError,
+        if (gs->prop_name != Py_None) {
+            PyErr_Format(PyExc_AttributeError,
                         value == NULL ?
-                        "can't delete attribute" :
-                "can't set attribute");
+                        "can't delete attribute %S" :
+                        "can't set attribute %S",
+                        gs->prop_name);
+        } else {
+            PyErr_SetString(PyExc_AttributeError,
+                            value == NULL ?
+                            "can't delete attribute" :
+                            "can't set attribute");
+        }
         return -1;
     }
     if (value == NULL)
@@ -1630,7 +1667,7 @@ property_copy(PyObject *old, PyObject *get, PyObject *set, PyObject *del)
         doc = pold->prop_doc ? pold->prop_doc : Py_None;
     }
 
-    new =  PyObject_CallFunctionObjArgs(type, get, set, del, doc, NULL);
+    new =  PyObject_CallFunctionObjArgs(type, get, set, del, doc, pold->prop_name, NULL);
     Py_DECREF(type);
     if (new == NULL)
         return NULL;
@@ -1648,6 +1685,8 @@ property.__init__ as property_init
         function to be used for del'ing an attribute
     doc: object(c_default="NULL") = None
         docstring
+    name: object(c_default="NULL") = None
+        name of a property
 
 Property attribute.
 
@@ -1676,8 +1715,8 @@ class C(object):
 
 static int
 property_init_impl(propertyobject *self, PyObject *fget, PyObject *fset,
-                   PyObject *fdel, PyObject *doc)
-/*[clinic end generated code: output=01a960742b692b57 input=dfb5dbbffc6932d5]*/
+                   PyObject *fdel, PyObject *doc, PyObject *name)
+/*[clinic end generated code: output=e9a13f227c218be9 input=fa7a7e0378f4e253]*/
 {
     if (fget == Py_None)
         fget = NULL;
@@ -1685,16 +1724,20 @@ property_init_impl(propertyobject *self, PyObject *fget, PyObject *fset,
         fset = NULL;
     if (fdel == Py_None)
         fdel = NULL;
+    if (name == Py_None)
+        name = NULL;
 
     Py_XINCREF(fget);
     Py_XINCREF(fset);
     Py_XINCREF(fdel);
     Py_XINCREF(doc);
+    Py_XINCREF(name);
 
     Py_XSETREF(self->prop_get, fget);
     Py_XSETREF(self->prop_set, fset);
     Py_XSETREF(self->prop_del, fdel);
     Py_XSETREF(self->prop_doc, doc);
+    Py_XSETREF(self->prop_name, name);
     self->getter_doc = 0;
 
     /* if no docstring given and the getter has one, use that one */
@@ -1769,6 +1812,7 @@ property_traverse(PyObject *self, visitproc visit, void *arg)
     Py_VISIT(pp->prop_set);
     Py_VISIT(pp->prop_del);
     Py_VISIT(pp->prop_doc);
+    Py_VISIT(pp->prop_name);
     return 0;
 }
 

From a0414666d9b3c958729e0ab3e23621c6e9b95a1e Mon Sep 17 00:00:00 2001
From: Yurii Karabas <1998uriyyo@gmail.com>
Date: Sun, 27 Dec 2020 18:58:32 +0200
Subject: [PATCH 2/8] Fix property test cases

---
 Lib/test/test_property.py | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/Lib/test/test_property.py b/Lib/test/test_property.py
index c7a4bdc3165f75..385b05d7453947 100644
--- a/Lib/test/test_property.py
+++ b/Lib/test/test_property.py
@@ -304,16 +304,19 @@ class _PropertyUnreachableAttribute:
     prop = None
 
     def _format_exc_msg(self, msg):
-        if self.prop.name is None:
+        name = self.prop[0].name
+
+        if name is None:
             return msg
 
-        return "{} {}".format(msg, self.prop.name)
+        return "{} {}".format(msg, name)
 
-    def setUpClass(self):
+    @classmethod
+    def setUpClass(cls):
         class TestCls:
-            foo = self.prop
+            foo, = cls.prop
 
-        self.obj = TestCls()
+        cls.obj = TestCls()
 
     def test_get_property(self):
         with self.assertRaisesRegex(AttributeError, self._format_exc_msg("unreadable attribute")):
@@ -329,15 +332,11 @@ def test_del_property(self):
 
 
 class PropertyUnreachableAttributeWithName(_PropertyUnreachableAttribute, unittest.TestCase):
-    def setUpClass(self):
-        self.prop = property(name='foo')
-        super().setUpClass()
+    prop = property(name='foo'),
 
 
 class PropertyUnreachableAttributeNoName(_PropertyUnreachableAttribute, unittest.TestCase):
-    def setUpClass(self):
-        self.prop = property()
-        super().setUpClass()
+    prop = property(),
 
 
 if __name__ == '__main__':

From 89b5b2193f4fbb1c451e67770fbebb40f1cefe4b Mon Sep 17 00:00:00 2001
From: Yurii Karabas <1998uriyyo@gmail.com>
Date: Mon, 28 Dec 2020 00:00:09 +0200
Subject: [PATCH 3/8] Fix issue with incorrect exc message

---
 Lib/test/test_property.py | 4 ++--
 Objects/descrobject.c     | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/Lib/test/test_property.py b/Lib/test/test_property.py
index 385b05d7453947..5c81e20b0f8bd4 100644
--- a/Lib/test/test_property.py
+++ b/Lib/test/test_property.py
@@ -307,9 +307,9 @@ def _format_exc_msg(self, msg):
         name = self.prop[0].name
 
         if name is None:
-            return msg
+            return '^{}$'.format(msg)
 
-        return "{} {}".format(msg, name)
+        return "^{} {}$".format(msg, name)
 
     @classmethod
     def setUpClass(cls):
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index 2329bd4ad34e50..46e470482b8bb9 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -1590,7 +1590,7 @@ property_descr_get(PyObject *self, PyObject *obj, PyObject *type)
 
     propertyobject *gs = (propertyobject *)self;
     if (gs->prop_get == NULL) {
-        if (gs->prop_name != Py_None) {
+        if (gs->prop_name != NULL) {
             PyErr_Format(PyExc_AttributeError, "unreadable attribute %S", gs->prop_name);
         } else {
             PyErr_SetString(PyExc_AttributeError, "unreadable attribute");
@@ -1613,7 +1613,7 @@ property_descr_set(PyObject *self, PyObject *obj, PyObject *value)
     else
         func = gs->prop_set;
     if (func == NULL) {
-        if (gs->prop_name != Py_None) {
+        if (gs->prop_name != NULL) {
             PyErr_Format(PyExc_AttributeError,
                         value == NULL ?
                         "can't delete attribute %S" :

From f02f68ceb2bc27b979eff516c74f6cfc9117c555 Mon Sep 17 00:00:00 2001
From: Yurii Karabas <1998uriyyo@gmail.com>
Date: Mon, 28 Dec 2020 01:18:29 +0200
Subject: [PATCH 4/8] remove `name` from `property` init method

---
 Doc/howto/descriptor.rst       | 18 ++++++++++++------
 Lib/test/test_property.py      | 17 +++++++++--------
 Objects/clinic/descrobject.c.h | 25 ++++++++-----------------
 Objects/descrobject.c          | 19 ++++++++-----------
 4 files changed, 37 insertions(+), 42 deletions(-)

diff --git a/Doc/howto/descriptor.rst b/Doc/howto/descriptor.rst
index 9d128a6fe582ec..4a922568be0620 100644
--- a/Doc/howto/descriptor.rst
+++ b/Doc/howto/descriptor.rst
@@ -907,7 +907,7 @@ Properties
 Calling :func:`property` is a succinct way of building a data descriptor that
 triggers a function call upon access to an attribute.  Its signature is::
 
-    property(fget=None, fset=None, fdel=None, doc=None, name=None) -> property
+    property(fget=None, fset=None, fdel=None, doc=None) -> property
 
 The documentation shows a typical use to define a managed attribute ``x``:
 
@@ -927,14 +927,14 @@ here is a pure Python equivalent:
     class Property:
         "Emulate PyProperty_Type() in Objects/descrobject.c"
 
-        def __init__(self, fget=None, fset=None, fdel=None, doc=None, name=None):
+        def __init__(self, fget=None, fset=None, fdel=None, doc=None):
             self.fget = fget
             self.fset = fset
             self.fdel = fdel
             if doc is None and fget is not None:
                 doc = fget.__doc__
             self.__doc__ = doc
-            self.name = name
+            self.name = None
 
         def __set_name__(self, owner, name):
             self.name = name
@@ -966,13 +966,19 @@ here is a pure Python equivalent:
             self.fdel(obj)
 
         def getter(self, fget):
-            return type(self)(fget, self.fset, self.fdel, self.__doc__, self.name)
+            prop = type(self)(fget, self.fset, self.fdel, self.__doc__)
+            prop.name = self.name
+            return prop
 
         def setter(self, fset):
-            return type(self)(self.fget, fset, self.fdel, self.__doc__, self.name)
+            prop = type(self)(self.fget, fset, self.fdel, self.__doc__)
+            prop.name = self.name
+            return prop
 
         def deleter(self, fdel):
-            return type(self)(self.fget, self.fset, fdel, self.__doc__, self.name)
+            prop = type(self)(self.fget, self.fset, fdel, self.__doc__)
+            prop.name = self.name
+            return prop
 
 .. testcode::
     :hide:
diff --git a/Lib/test/test_property.py b/Lib/test/test_property.py
index 5c81e20b0f8bd4..963e30ae96c782 100644
--- a/Lib/test/test_property.py
+++ b/Lib/test/test_property.py
@@ -301,10 +301,10 @@ def spam(self):
 
 class _PropertyUnreachableAttribute:
     obj = None
-    prop = None
+    cls = None
 
     def _format_exc_msg(self, msg):
-        name = self.prop[0].name
+        name = self.cls.foo.name
 
         if name is None:
             return '^{}$'.format(msg)
@@ -313,10 +313,7 @@ def _format_exc_msg(self, msg):
 
     @classmethod
     def setUpClass(cls):
-        class TestCls:
-            foo, = cls.prop
-
-        cls.obj = TestCls()
+        cls.obj = cls.cls()
 
     def test_get_property(self):
         with self.assertRaisesRegex(AttributeError, self._format_exc_msg("unreadable attribute")):
@@ -332,11 +329,15 @@ def test_del_property(self):
 
 
 class PropertyUnreachableAttributeWithName(_PropertyUnreachableAttribute, unittest.TestCase):
-    prop = property(name='foo'),
+    class cls:
+        foo = property()
 
 
 class PropertyUnreachableAttributeNoName(_PropertyUnreachableAttribute, unittest.TestCase):
-    prop = property(),
+    class cls:
+        pass
+
+    cls.foo = property()
 
 
 if __name__ == '__main__':
diff --git a/Objects/clinic/descrobject.c.h b/Objects/clinic/descrobject.c.h
index 4eaa19c07107a0..d248b91bf48da2 100644
--- a/Objects/clinic/descrobject.c.h
+++ b/Objects/clinic/descrobject.c.h
@@ -28,7 +28,7 @@ mappingproxy_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
 }
 
 PyDoc_STRVAR(property_init__doc__,
-"property(fget=None, fset=None, fdel=None, doc=None, name=None)\n"
+"property(fget=None, fset=None, fdel=None, doc=None)\n"
 "--\n"
 "\n"
 "Property attribute.\n"
@@ -41,8 +41,6 @@ PyDoc_STRVAR(property_init__doc__,
 "    function to be used for del\'ing an attribute\n"
 "  doc\n"
 "    docstring\n"
-"  name\n"
-"    name of a property\n"
 "\n"
 "Typical use is to define a managed attribute x:\n"
 "\n"
@@ -68,15 +66,15 @@ PyDoc_STRVAR(property_init__doc__,
 
 static int
 property_init_impl(propertyobject *self, PyObject *fget, PyObject *fset,
-                   PyObject *fdel, PyObject *doc, PyObject *name);
+                   PyObject *fdel, PyObject *doc);
 
 static int
 property_init(PyObject *self, PyObject *args, PyObject *kwargs)
 {
     int return_value = -1;
-    static const char * const _keywords[] = {"fget", "fset", "fdel", "doc", "name", NULL};
+    static const char * const _keywords[] = {"fget", "fset", "fdel", "doc", NULL};
     static _PyArg_Parser _parser = {NULL, _keywords, "property", 0};
-    PyObject *argsbuf[5];
+    PyObject *argsbuf[4];
     PyObject * const *fastargs;
     Py_ssize_t nargs = PyTuple_GET_SIZE(args);
     Py_ssize_t noptargs = nargs + (kwargs ? PyDict_GET_SIZE(kwargs) : 0) - 0;
@@ -84,9 +82,8 @@ property_init(PyObject *self, PyObject *args, PyObject *kwargs)
     PyObject *fset = NULL;
     PyObject *fdel = NULL;
     PyObject *doc = NULL;
-    PyObject *name = NULL;
 
-    fastargs = _PyArg_UnpackKeywords(_PyTuple_CAST(args)->ob_item, nargs, kwargs, NULL, &_parser, 0, 5, 0, argsbuf);
+    fastargs = _PyArg_UnpackKeywords(_PyTuple_CAST(args)->ob_item, nargs, kwargs, NULL, &_parser, 0, 4, 0, argsbuf);
     if (!fastargs) {
         goto exit;
     }
@@ -111,17 +108,11 @@ property_init(PyObject *self, PyObject *args, PyObject *kwargs)
             goto skip_optional_pos;
         }
     }
-    if (fastargs[3]) {
-        doc = fastargs[3];
-        if (!--noptargs) {
-            goto skip_optional_pos;
-        }
-    }
-    name = fastargs[4];
+    doc = fastargs[3];
 skip_optional_pos:
-    return_value = property_init_impl((propertyobject *)self, fget, fset, fdel, doc, name);
+    return_value = property_init_impl((propertyobject *)self, fget, fset, fdel, doc);
 
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=562ff56bb7a4dbf0 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=916624e717862abc input=a9049054013a1b77]*/
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index 46e470482b8bb9..4bcd0036f5a48f 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -1457,14 +1457,13 @@ PyWrapper_New(PyObject *d, PyObject *self)
 /*
 class property(object):
 
-    def __init__(self, fget=None, fset=None, fdel=None, doc=None, name=None):
+    def __init__(self, fget=None, fset=None, fdel=None, doc=None):
         if doc is None and fget is not None and hasattr(fget, "__doc__"):
             doc = fget.__doc__
         self.__get = fget
         self.__set = fset
         self.__del = fdel
         self.__doc__ = doc
-        self.name = name
 
     def __get__(self, inst, type=None):
         if inst is None:
@@ -1667,10 +1666,12 @@ property_copy(PyObject *old, PyObject *get, PyObject *set, PyObject *del)
         doc = pold->prop_doc ? pold->prop_doc : Py_None;
     }
 
-    new =  PyObject_CallFunctionObjArgs(type, get, set, del, doc, pold->prop_name, NULL);
+    new =  PyObject_CallFunctionObjArgs(type, get, set, del, doc, NULL);
     Py_DECREF(type);
     if (new == NULL)
         return NULL;
+
+    Py_XSETREF(((propertyobject *) new)->prop_name, pold->prop_name);
     return new;
 }
 
@@ -1685,8 +1686,6 @@ property.__init__ as property_init
         function to be used for del'ing an attribute
     doc: object(c_default="NULL") = None
         docstring
-    name: object(c_default="NULL") = None
-        name of a property
 
 Property attribute.
 
@@ -1715,8 +1714,8 @@ class C(object):
 
 static int
 property_init_impl(propertyobject *self, PyObject *fget, PyObject *fset,
-                   PyObject *fdel, PyObject *doc, PyObject *name)
-/*[clinic end generated code: output=e9a13f227c218be9 input=fa7a7e0378f4e253]*/
+                   PyObject *fdel, PyObject *doc)
+/*[clinic end generated code: output=01a960742b692b57 input=dfb5dbbffc6932d5]*/
 {
     if (fget == Py_None)
         fget = NULL;
@@ -1724,20 +1723,18 @@ property_init_impl(propertyobject *self, PyObject *fget, PyObject *fset,
         fset = NULL;
     if (fdel == Py_None)
         fdel = NULL;
-    if (name == Py_None)
-        name = NULL;
 
     Py_XINCREF(fget);
     Py_XINCREF(fset);
     Py_XINCREF(fdel);
     Py_XINCREF(doc);
-    Py_XINCREF(name);
 
     Py_XSETREF(self->prop_get, fget);
     Py_XSETREF(self->prop_set, fset);
     Py_XSETREF(self->prop_del, fdel);
     Py_XSETREF(self->prop_doc, doc);
-    Py_XSETREF(self->prop_name, name);
+    Py_XSETREF(self->prop_name, NULL);
+
     self->getter_doc = 0;
 
     /* if no docstring given and the getter has one, use that one */

From b5029073fa337f3bbc1b35e60f7fe4e214b8c668 Mon Sep 17 00:00:00 2001
From: Yurii Karabas <1998uriyyo@gmail.com>
Date: Mon, 28 Dec 2020 10:38:44 +0200
Subject: [PATCH 5/8] Make name attribute private

---
 Doc/howto/descriptor.rst                      | 25 ++++++-------------
 Lib/test/test_property.py                     | 12 ++++-----
 .../2020-12-27-18-07-43.bpo-27794.sxgfGi.rst  |  5 ++--
 Objects/descrobject.c                         |  2 +-
 4 files changed, 18 insertions(+), 26 deletions(-)

diff --git a/Doc/howto/descriptor.rst b/Doc/howto/descriptor.rst
index 4a922568be0620..2821e80d3e5d2d 100644
--- a/Doc/howto/descriptor.rst
+++ b/Doc/howto/descriptor.rst
@@ -934,50 +934,41 @@ here is a pure Python equivalent:
             if doc is None and fget is not None:
                 doc = fget.__doc__
             self.__doc__ = doc
-            self.name = None
+            self._name = ''
 
         def __set_name__(self, owner, name):
-            self.name = name
+            self._name = name
 
         def __get__(self, obj, objtype=None):
             if obj is None:
                 return self
             if self.fget is None:
-                raise AttributeError(
-                    "unreadable attribute" +
-                    (" " + self.name if self.name is not None else "")
-                )
+                raise AttributeError(f'unreadable attribute {self._name}'.strip())
             return self.fget(obj)
 
         def __set__(self, obj, value):
             if self.fset is None:
-                raise AttributeError(
-                    "can't set attribute" +
-                    (" " + self.name if self.name is not None else "")
-                )
+                raise AttributeError(f'can't set attribute {self._name}'.strip())
             self.fset(obj, value)
 
         def __delete__(self, obj):
             if self.fdel is None:
-                raise AttributeError(
-                    "can't delete attribute" +
-                    (" " + self.name if self.name is not None else "")
-                )
+                raise AttributeError(f'can't delete attribute {self._name}'.strip())
             self.fdel(obj)
 
         def getter(self, fget):
             prop = type(self)(fget, self.fset, self.fdel, self.__doc__)
-            prop.name = self.name
+            prop._name = self._name
             return prop
 
         def setter(self, fset):
             prop = type(self)(self.fget, fset, self.fdel, self.__doc__)
-            prop.name = self.name
+            prop._name = self._name
             return prop
 
         def deleter(self, fdel):
             prop = type(self)(self.fget, self.fset, fdel, self.__doc__)
-            prop.name = self.name
+            prop._name = self._name
             return prop
 
 .. testcode::
diff --git a/Lib/test/test_property.py b/Lib/test/test_property.py
index 963e30ae96c782..7bab64b747847c 100644
--- a/Lib/test/test_property.py
+++ b/Lib/test/test_property.py
@@ -300,16 +300,12 @@ def spam(self):
 
 
 class _PropertyUnreachableAttribute:
+    msg_format = None
     obj = None
     cls = None
 
     def _format_exc_msg(self, msg):
-        name = self.cls.foo.name
-
-        if name is None:
-            return '^{}$'.format(msg)
-
-        return "^{} {}$".format(msg, name)
+        return self.msg_format.format(msg)
 
     @classmethod
     def setUpClass(cls):
@@ -329,11 +325,15 @@ def test_del_property(self):
 
 
 class PropertyUnreachableAttributeWithName(_PropertyUnreachableAttribute, unittest.TestCase):
+    msg_format = "^{} foo$"
+
     class cls:
         foo = property()
 
 
 class PropertyUnreachableAttributeNoName(_PropertyUnreachableAttribute, unittest.TestCase):
+    msg_format = "^{}$"
+
     class cls:
         pass
 
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-12-27-18-07-43.bpo-27794.sxgfGi.rst b/Misc/NEWS.d/next/Core and Builtins/2020-12-27-18-07-43.bpo-27794.sxgfGi.rst
index 4c125ba80a5669..0f66b4effc5df2 100644
--- a/Misc/NEWS.d/next/Core and Builtins/2020-12-27-18-07-43.bpo-27794.sxgfGi.rst	
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-12-27-18-07-43.bpo-27794.sxgfGi.rst	
@@ -1,2 +1,3 @@
-Add ``name`` attribute to ``property`` class to add more information when
-``AttributeError`` exception raised. Patch provided by Yurii Karabas.
+Improve the error message for failed writes/deletes to property objects.
+When possible, the attribute name is now shown. Patch provided by
+Yurii Karabas.
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index 4bcd0036f5a48f..ef64ce270988fb 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -1502,7 +1502,6 @@ static PyMemberDef property_members[] = {
     {"fset", T_OBJECT, offsetof(propertyobject, prop_set), READONLY},
     {"fdel", T_OBJECT, offsetof(propertyobject, prop_del), READONLY},
     {"__doc__",  T_OBJECT, offsetof(propertyobject, prop_doc), 0},
-    {"name",  T_OBJECT, offsetof(propertyobject, prop_name), READONLY},
     {0}
 };
 
@@ -1671,6 +1670,7 @@ property_copy(PyObject *old, PyObject *get, PyObject *set, PyObject *del)
     if (new == NULL)
         return NULL;
 
+    Py_XINCREF(pold->prop_name);
     Py_XSETREF(((propertyobject *) new)->prop_name, pold->prop_name);
     return new;
 }

From 6aa55bda52b4d0ef78bc0cc37e18b9388018cd02 Mon Sep 17 00:00:00 2001
From: Yurii Karabas <1998uriyyo@gmail.com>
Date: Mon, 28 Dec 2020 10:49:17 +0200
Subject: [PATCH 6/8] fix docs

---
 Doc/howto/descriptor.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Doc/howto/descriptor.rst b/Doc/howto/descriptor.rst
index 2821e80d3e5d2d..9caacb671243a0 100644
--- a/Doc/howto/descriptor.rst
+++ b/Doc/howto/descriptor.rst
@@ -948,12 +948,12 @@ here is a pure Python equivalent:
 
         def __set__(self, obj, value):
             if self.fset is None:
-                raise AttributeError(f'can't set attribute {self._name}'.strip())
+                raise AttributeError(f'can\'t set attribute {self._name}'.strip())
             self.fset(obj, value)
 
         def __delete__(self, obj):
             if self.fdel is None:
-                raise AttributeError(f'can't delete attribute {self._name}'.strip())
+                raise AttributeError(f'can\'t delete attribute {self._name}'.strip())
             self.fdel(obj)
 
         def getter(self, fget):

From 2c8376932dea5cd30166b48353a5800f612930ca Mon Sep 17 00:00:00 2001
From: Yurii Karabas <1998uriyyo@gmail.com>
Date: Tue, 29 Dec 2020 10:34:45 +0200
Subject: [PATCH 7/8] Remove strip call from docs, remove extra blank line

---
 Doc/howto/descriptor.rst | 6 +++---
 Objects/descrobject.c    | 1 -
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/Doc/howto/descriptor.rst b/Doc/howto/descriptor.rst
index 9caacb671243a0..b47e016eb14c27 100644
--- a/Doc/howto/descriptor.rst
+++ b/Doc/howto/descriptor.rst
@@ -943,17 +943,17 @@ here is a pure Python equivalent:
             if obj is None:
                 return self
             if self.fget is None:
-                raise AttributeError(f'unreadable attribute {self._name}'.strip())
+                raise AttributeError(f'unreadable attribute {self._name}')
             return self.fget(obj)
 
         def __set__(self, obj, value):
             if self.fset is None:
-                raise AttributeError(f'can\'t set attribute {self._name}'.strip())
+                raise AttributeError(f'can\'t set attribute {self._name}')
             self.fset(obj, value)
 
         def __delete__(self, obj):
             if self.fdel is None:
-                raise AttributeError(f'can\'t delete attribute {self._name}'.strip())
+                raise AttributeError(f'can\'t delete attribute {self._name}')
             self.fdel(obj)
 
         def getter(self, fget):
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index ef64ce270988fb..2b142ad09597bd 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -1554,7 +1554,6 @@ property_set_name(PyObject *self, PyObject *args) {
     Py_RETURN_NONE;
 }
 
-
 static PyMethodDef property_methods[] = {
     {"getter", property_getter, METH_O, getter_doc},
     {"setter", property_setter, METH_O, setter_doc},

From d2b4e63aaa35920c7fce6436ff0ad6c3f07fa05c Mon Sep 17 00:00:00 2001
From: Yurii Karabas <1998uriyyo@gmail.com>
Date: Tue, 29 Dec 2020 22:28:37 +0200
Subject: [PATCH 8/8] Update docs and property __set_name__ method

---
 Doc/howto/descriptor.rst  |  4 ++--
 Lib/test/test_property.py | 12 +++++++++++-
 Objects/descrobject.c     | 18 +++++++++++-------
 3 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/Doc/howto/descriptor.rst b/Doc/howto/descriptor.rst
index b47e016eb14c27..d172c9b181c1ce 100644
--- a/Doc/howto/descriptor.rst
+++ b/Doc/howto/descriptor.rst
@@ -948,12 +948,12 @@ here is a pure Python equivalent:
 
         def __set__(self, obj, value):
             if self.fset is None:
-                raise AttributeError(f'can\'t set attribute {self._name}')
+                raise AttributeError(f"can't set attribute {self._name}")
             self.fset(obj, value)
 
         def __delete__(self, obj):
             if self.fdel is None:
-                raise AttributeError(f'can\'t delete attribute {self._name}')
+                raise AttributeError(f"can't delete attribute {self._name}")
             self.fdel(obj)
 
         def getter(self, fget):
diff --git a/Lib/test/test_property.py b/Lib/test/test_property.py
index 7bab64b747847c..7f3813fc8cd15e 100644
--- a/Lib/test/test_property.py
+++ b/Lib/test/test_property.py
@@ -204,6 +204,16 @@ def __doc__(cls):
                 return 'Second'
         self.assertEqual(A.__doc__, 'Second')
 
+    def test_property_set_name_incorrect_args(self):
+        p = property()
+
+        for i in (0, 1, 3):
+            with self.assertRaisesRegex(
+                TypeError,
+                fr'^__set_name__\(\) takes 2 positional arguments but {i} were given$'
+            ):
+                p.__set_name__(*([0] * i))
+
 
 # Issue 5890: subclasses of property do not preserve method __doc__ strings
 class PropertySub(property):
@@ -325,7 +335,7 @@ def test_del_property(self):
 
 
 class PropertyUnreachableAttributeWithName(_PropertyUnreachableAttribute, unittest.TestCase):
-    msg_format = "^{} foo$"
+    msg_format = "^{} 'foo'$"
 
     class cls:
         foo = property()
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index 2b142ad09597bd..16c695a08f47d9 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -1541,13 +1541,17 @@ PyDoc_STRVAR(set_name_doc,
 
 static PyObject *
 property_set_name(PyObject *self, PyObject *args) {
-    propertyobject *prop = (propertyobject *)self;
-    PyObject *name = PyTuple_GetItem(args, 1);
-
-    if (name == NULL) {
+    if (PyTuple_GET_SIZE(args) != 2) {
+        PyErr_Format(
+                PyExc_TypeError,
+                "__set_name__() takes 2 positional arguments but %d were given",
+                PyTuple_GET_SIZE(args));
         return NULL;
     }
 
+    propertyobject *prop = (propertyobject *)self;
+    PyObject *name = PyTuple_GET_ITEM(args, 1);
+
     Py_XINCREF(name);
     Py_XSETREF(prop->prop_name, name);
 
@@ -1588,7 +1592,7 @@ property_descr_get(PyObject *self, PyObject *obj, PyObject *type)
     propertyobject *gs = (propertyobject *)self;
     if (gs->prop_get == NULL) {
         if (gs->prop_name != NULL) {
-            PyErr_Format(PyExc_AttributeError, "unreadable attribute %S", gs->prop_name);
+            PyErr_Format(PyExc_AttributeError, "unreadable attribute %R", gs->prop_name);
         } else {
             PyErr_SetString(PyExc_AttributeError, "unreadable attribute");
         }
@@ -1613,8 +1617,8 @@ property_descr_set(PyObject *self, PyObject *obj, PyObject *value)
         if (gs->prop_name != NULL) {
             PyErr_Format(PyExc_AttributeError,
                         value == NULL ?
-                        "can't delete attribute %S" :
-                        "can't set attribute %S",
+                        "can't delete attribute %R" :
+                        "can't set attribute %R",
                         gs->prop_name);
         } else {
             PyErr_SetString(PyExc_AttributeError,