Make readonly members defined in C throw an AttributeError on modification. This brings them into sync with Python-level attributes. Fixes bug #1687163.

Lib/test/test_csv.py

@@ -53,8 +53,8 @@ class Test_Csv(unittest.TestCase):
         self.assertEqual(obj.dialect.skipinitialspace, False)
         self.assertEqual(obj.dialect.strict, False)
         # Try deleting or changing attributes (they are read-only)
-        self.assertRaises(TypeError, delattr, obj.dialect, 'delimiter')
-        self.assertRaises(TypeError, setattr, obj.dialect, 'delimiter', ':')
+        self.assertRaises(AttributeError, delattr, obj.dialect, 'delimiter')
+        self.assertRaises(AttributeError, setattr, obj.dialect, 'delimiter', ':')
         self.assertRaises(AttributeError, delattr, obj.dialect, 'quoting')
         self.assertRaises(AttributeError, setattr, obj.dialect,
                           'quoting', None)

Lib/test/test_descr.py

@@ -1857,13 +1857,13 @@ def properties():
     for attr in "__doc__", "fget", "fset", "fdel":
         try:
             setattr(raw, attr, 42)
-        except TypeError as msg:
+        except AttributeError as msg:
             if str(msg).find('readonly') < 0:
                 raise TestFailed("when setting readonly attr %r on a "
-                                 "property, got unexpected TypeError "
+                                 "property, got unexpected AttributeError "
                                  "msg %r" % (attr, str(msg)))
         else:
-            raise TestFailed("expected TypeError from trying to set "
+            raise TestFailed("expected AttributeError from trying to set "
                              "readonly %r attr on a property" % attr)
 
     class D(object):

Lib/test/test_generators.py

@@ -400,7 +400,7 @@ And more, added later.
 >>> i.gi_running = 42
 Traceback (most recent call last):
   ...
-TypeError: readonly attribute
+AttributeError: readonly attribute
 >>> def g():
 ...     yield me.gi_running
 >>> me = g()

Lib/test/test_os.py

@@ -143,7 +143,7 @@ class StatAttributeTests(unittest.TestCase):
         try:
             result.st_mode = 1
             self.fail("No exception thrown")
-        except TypeError:
+        except AttributeError:
             pass
 
         try:
@@ -201,7 +201,7 @@ class StatAttributeTests(unittest.TestCase):
         try:
             result.f_bfree = 1
             self.fail("No exception thrown")
-        except TypeError:
+        except AttributeError:
             pass
 
         try:

Python/structmember.c

@@ -164,7 +164,7 @@ PyMember_SetOne(char *addr, PyMemberDef *l, PyObject *v)
 
 	if ((l->flags & READONLY) || l->type == T_STRING)
 	{
-		PyErr_SetString(PyExc_TypeError, "readonly attribute");
+		PyErr_SetString(PyExc_AttributeError, "readonly attribute");
 		return -1;
 	}
 	if ((l->flags & WRITE_RESTRICTED) && PyEval_GetRestricted()) {