Issue #9856: Replace deprecation warinigs to raising TypeError in object.__format__

Patch by Florent Xicluna.

Lib/test/test_builtin.py

@@ -1479,17 +1479,11 @@ class BuiltinTest(unittest.TestCase):
         # --------------------------------------------------------------------
         # Issue #7994: object.__format__ with a non-empty format string is
         #  deprecated
-        def test_deprecated_format_string(obj, fmt_str, should_raise_warning):
-            with warnings.catch_warnings(record=True) as w:
-                warnings.simplefilter("always", DeprecationWarning)
-                format(obj, fmt_str)
-            if should_raise_warning:
-                self.assertEqual(len(w), 1)
-                self.assertIsInstance(w[0].message, DeprecationWarning)
-                self.assertIn('object.__format__ with a non-empty format '
-                              'string', str(w[0].message))
+        def test_deprecated_format_string(obj, fmt_str, should_raise):
+            if should_raise:
+                self.assertRaises(TypeError, format, obj, fmt_str)
             else:
-                self.assertEqual(len(w), 0)
+                format(obj, fmt_str)
 
         fmt_strs = ['', 's']
 

Lib/test/test_unicode.py

@@ -842,11 +842,9 @@ class UnicodeTest(string_tests.CommonTest,
         self.assertEqual('{0:d}'.format(G('data')), 'G(data)')
         self.assertEqual('{0!s}'.format(G('data')), 'string is data')
 
-        msg = 'object.__format__ with a non-empty format string is deprecated'
-        with support.check_warnings((msg, DeprecationWarning)):
-            self.assertEqual('{0:^10}'.format(E('data')), ' E(data)  ')
-            self.assertEqual('{0:^10s}'.format(E('data')), ' E(data)  ')
-            self.assertEqual('{0:>15s}'.format(G('data')), ' string is data')
+        self.assertRaises(TypeError, '{0:^10}'.format, E('data'))
+        self.assertRaises(TypeError, '{0:^10s}'.format, E('data'))
+        self.assertRaises(TypeError, '{0:>15s}'.format, G('data'))
 
         self.assertEqual("{0:date: %Y-%m-%d}".format(I(year=2007,
                                                        month=8,

Objects/typeobject.c

@@ -3654,16 +3654,9 @@ object_format(PyObject *self, PyObject *args)
         /* Issue 7994: If we're converting to a string, we
            should reject format specifications */
         if (PyUnicode_GET_LENGTH(format_spec) > 0) {
-            if (PyErr_WarnEx(PyExc_DeprecationWarning,
-                             "object.__format__ with a non-empty format "
-                             "string is deprecated", 1) < 0) {
-              goto done;
-            }
-            /* Eventually this will become an error:
-               PyErr_Format(PyExc_TypeError,
+            PyErr_SetString(PyExc_TypeError,
                "non-empty format string passed to object.__format__");
             goto done;
-            */
         }
 
         result = PyObject_Format(self_as_str, format_spec);
@@ -4288,12 +4281,10 @@ PyType_Ready(PyTypeObject *type)
     /* Warn for a type that implements tp_compare (now known as
        tp_reserved) but not tp_richcompare. */
     if (type->tp_reserved && !type->tp_richcompare) {
-        int error;
-        error = PyErr_WarnFormat(PyExc_DeprecationWarning, 1,
+        PyErr_Format(PyExc_TypeError,
             "Type %.100s defines tp_reserved (formerly tp_compare) "
             "but not tp_richcompare. Comparisons may not behave as intended.",
             type->tp_name);
-        if (error == -1)
         goto error;
     }