changeset:   104611:7c3ec24f4582
parent:      104609:2119cb0beace
parent:      104610:f7e1e39ccddd
user:        Serhiy Storchaka <storchaka@gmail.com>
date:        Fri Oct 21 17:15:20 2016 +0300
files:       Misc/NEWS
description:
Issue #28214: Improved exception reporting for problematic __set_name__
attributes.


diff -r 2119cb0beace -r 7c3ec24f4582 Lib/test/test_subclassinit.py
--- a/Lib/test/test_subclassinit.py	Fri Oct 21 17:10:42 2016 +0300
+++ b/Lib/test/test_subclassinit.py	Fri Oct 21 17:15:20 2016 +0300
@@ -133,20 +133,32 @@
     def test_set_name_error(self):
         class Descriptor:
             def __set_name__(self, owner, name):
-                raise RuntimeError
+                1/0
+
+        with self.assertRaises(RuntimeError) as cm:
+            class NotGoingToWork:
+                attr = Descriptor()
 
-        with self.assertRaises(RuntimeError):
-            class A:
-                d = Descriptor()
+        exc = cm.exception
+        self.assertRegex(str(exc), r'\bNotGoingToWork\b')
+        self.assertRegex(str(exc), r'\battr\b')
+        self.assertRegex(str(exc), r'\bDescriptor\b')
+        self.assertIsInstance(exc.__cause__, ZeroDivisionError)
 
     def test_set_name_wrong(self):
         class Descriptor:
             def __set_name__(self):
                 pass
 
-        with self.assertRaises(TypeError):
-            class A:
-                d = Descriptor()
+        with self.assertRaises(RuntimeError) as cm:
+            class NotGoingToWork:
+                attr = Descriptor()
+
+        exc = cm.exception
+        self.assertRegex(str(exc), r'\bNotGoingToWork\b')
+        self.assertRegex(str(exc), r'\battr\b')
+        self.assertRegex(str(exc), r'\bDescriptor\b')
+        self.assertIsInstance(exc.__cause__, TypeError)
 
     def test_set_name_lookup(self):
         resolved = []
diff -r 2119cb0beace -r 7c3ec24f4582 Misc/NEWS
--- a/Misc/NEWS	Fri Oct 21 17:10:42 2016 +0300
+++ b/Misc/NEWS	Fri Oct 21 17:15:20 2016 +0300
@@ -10,6 +10,9 @@
 Core and Builtins
 -----------------
 
+- Issue #28214: Improved exception reporting for problematic __set_name__
+  attributes.
+
 - Issue #23782: Fixed possible memory leak in _PyTraceback_Add() and exception
   loss in PyTraceBack_Here().
 
diff -r 2119cb0beace -r 7c3ec24f4582 Objects/typeobject.c
--- a/Objects/typeobject.c	Fri Oct 21 17:10:42 2016 +0300
+++ b/Objects/typeobject.c	Fri Oct 21 17:15:20 2016 +0300
@@ -7022,8 +7022,13 @@
         if (set_name != NULL) {
             tmp = PyObject_CallFunctionObjArgs(set_name, type, key, NULL);
             Py_DECREF(set_name);
-            if (tmp == NULL)
+            if (tmp == NULL) {
+                _PyErr_FormatFromCause(PyExc_RuntimeError,
+                    "Error calling __set_name__ on '%.100s' instance %R "
+                    "in '%.100s'",
+                    value->ob_type->tp_name, key, type->tp_name);
                 return -1;
+            }
             else
                 Py_DECREF(tmp);
         }