bpo-24766: doc= argument to subclasses of property not handled correc…

…tly (GH-2487)
python · serhiy-storchaka · Jun 10, 2024 · Jun 29, 2017 · Oct 9, 2018 · Oct 9, 2018
commit 349f3099e0208a3693b926ba254ba0275b9cd0fb
diff --git a/Lib/test/test_property.py b/Lib/test/test_property.py
@@ -239,6 +239,28 @@ def spam(self):
             Foo.spam.__doc__,
             "spam wrapped in property subclass")
 
+    @unittest.skipIf(sys.flags.optimize >= 2,
+                     "Docstrings are omitted with -O2 and above")
+    def test_prefer_explicit_doc(self):
+        # Issue 25757: subclasses of property lose docstring
+        self.assertEqual(property(doc="explicit doc").__doc__, "explicit doc")
+        self.assertEqual(PropertySub(doc="explicit doc").__doc__, "explicit doc")
+
+        class Foo:
+            spam = PropertySub(doc="spam explicit doc")
+
+            @spam.getter
+            def spam(self):
+                """ignored as doc already set"""
+                return 1
+
+            def _stuff_getter(self):
+                """ignored as doc set directly"""
+            stuff = PropertySub(doc="stuff doc argument", fget=_stuff_getter)
+
+        self.assertEqual(Foo.spam.__doc__, "spam explicit doc")
+        self.assertEqual(Foo.stuff.__doc__, "stuff doc argument")
+
     @unittest.skipIf(sys.flags.optimize >= 2,
                      "Docstrings are omitted with -O2 and above")
     def test_property_setter_copies_getter_docstring(self):

diff --git a/Objects/descrobject.c b/Objects/descrobject.c
@@ -1679,6 +1679,8 @@ property_init_impl(propertyobject *self, PyObject *fget, PyObject *fset,
                    PyObject *fdel, PyObject *doc)
 /*[clinic end generated code: output=01a960742b692b57 input=dfb5dbbffc6932d5]*/
 {
+    _Py_IDENTIFIER(__doc__);
+
     if (fget == Py_None)
         fget = NULL;
     if (fset == Py_None)
@@ -1699,28 +1701,26 @@ property_init_impl(propertyobject *self, PyObject *fget, PyObject *fset,
 
     /* if no docstring given and the getter has one, use that one */
     if ((doc == NULL || doc == Py_None) && fget != NULL) {
-        _Py_IDENTIFIER(__doc__);
         PyObject *get_doc;
         int rc = _PyObject_LookupAttrId(fget, &PyId___doc__, &get_doc);
         if (rc <= 0) {
             return rc;
         }
-        if (Py_IS_TYPE(self, &PyProperty_Type)) {
-            Py_XSETREF(self->prop_doc, get_doc);
-        }
-        else {
-            /* If this is a property subclass, put __doc__
-               in dict of the subclass instance instead,
-               otherwise it gets shadowed by __doc__ in the
-               class's dict. */
-            int err = _PyObject_SetAttrId((PyObject *)self, &PyId___doc__, get_doc);
-            Py_DECREF(get_doc);
-            if (err < 0)
-                return -1;
-        }
+        Py_XSETREF(self->prop_doc, get_doc);
         self->getter_doc = 1;
     }
 
+    /* If this is a property subclass, put __doc__ in dict of the subclass
+       instance as well, otherwise it gets shadowed by __doc__ in the
+       class's dict. */
+    if (Py_IS_TYPE(self, &PyProperty_Type)) {
+        int err = _PyObject_SetAttrId((PyObject *)self, &PyId___doc__,
+                                      self->prop_doc);
+        if (err < 0) {
+            return -1;
+        }
+    }
+
     return 0;
 }