From e46fb8611867fa3b407a813f53137929b7cb4a10 Mon Sep 17 00:00:00 2001
From: 4kir4 <4kir4.1i@gmail.com>
Date: Mon, 20 Mar 2017 09:44:46 +0300
Subject: [PATCH] bpo-28876: bool of large range raises OverflowError (#699)

---
 Lib/test/test_range.py | 17 +++++++++++++----
 Misc/NEWS              |  3 +++
 Objects/rangeobject.c  | 12 +++++++++++-
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/Lib/test/test_range.py b/Lib/test/test_range.py
index 3675f250af8..ce1584748d7 100644
--- a/Lib/test/test_range.py
+++ b/Lib/test/test_range.py
@@ -98,20 +98,24 @@ class RangeTest(unittest.TestCase):
         x = range(10**20+10, 10**20, 3)
         self.assertEqual(len(x), 0)
         self.assertEqual(len(list(x)), 0)
+        self.assertFalse(x)
 
         x = range(10**20, 10**20+10, -3)
         self.assertEqual(len(x), 0)
         self.assertEqual(len(list(x)), 0)
+        self.assertFalse(x)
 
         x = range(10**20+10, 10**20, -3)
         self.assertEqual(len(x), 4)
         self.assertEqual(len(list(x)), 4)
+        self.assertTrue(x)
 
         # Now test range() with longs
-        self.assertEqual(list(range(-2**100)), [])
-        self.assertEqual(list(range(0, -2**100)), [])
-        self.assertEqual(list(range(0, 2**100, -1)), [])
-        self.assertEqual(list(range(0, 2**100, -1)), [])
+        for x in [range(-2**100),
+                  range(0, -2**100),
+                  range(0, 2**100, -1)]:
+            self.assertEqual(list(x), [])
+            self.assertFalse(x)
 
         a = int(10 * sys.maxsize)
         b = int(100 * sys.maxsize)
@@ -152,6 +156,7 @@ class RangeTest(unittest.TestCase):
                 step = x[1] - x[0]
                 length = 1 + ((x[-1] - x[0]) // step)
             return length
+
         a = -sys.maxsize
         b = sys.maxsize
         expected_len = b - a
@@ -159,6 +164,7 @@ class RangeTest(unittest.TestCase):
         self.assertIn(a, x)
         self.assertNotIn(b, x)
         self.assertRaises(OverflowError, len, x)
+        self.assertTrue(x)
         self.assertEqual(_range_len(x), expected_len)
         self.assertEqual(x[0], a)
         idx = sys.maxsize+1
@@ -176,6 +182,7 @@ class RangeTest(unittest.TestCase):
         self.assertIn(a, x)
         self.assertNotIn(b, x)
         self.assertRaises(OverflowError, len, x)
+        self.assertTrue(x)
         self.assertEqual(_range_len(x), expected_len)
         self.assertEqual(x[0], a)
         idx = sys.maxsize+1
@@ -194,6 +201,7 @@ class RangeTest(unittest.TestCase):
         self.assertIn(a, x)
         self.assertNotIn(b, x)
         self.assertRaises(OverflowError, len, x)
+        self.assertTrue(x)
         self.assertEqual(_range_len(x), expected_len)
         self.assertEqual(x[0], a)
         idx = sys.maxsize+1
@@ -212,6 +220,7 @@ class RangeTest(unittest.TestCase):
         self.assertIn(a, x)
         self.assertNotIn(b, x)
         self.assertRaises(OverflowError, len, x)
+        self.assertTrue(x)
         self.assertEqual(_range_len(x), expected_len)
         self.assertEqual(x[0], a)
         idx = sys.maxsize+1
diff --git a/Misc/NEWS b/Misc/NEWS
index 8509f52692d..6de87943442 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -35,6 +35,9 @@ Core and Builtins
 - bpo-28893: Set correct __cause__ for errors about invalid awaitables
   returned from __aiter__ and __anext__.
 
+- bpo-28876: ``bool(range)`` works even if ``len(range)``
+  raises :exc:`OverflowError`.
+
 - bpo-29683: Fixes to memory allocation in _PyCode_SetExtra.  Patch by
   Brian Coleman.
 
diff --git a/Objects/rangeobject.c b/Objects/rangeobject.c
index 45c557ff57b..820fea56234 100644
--- a/Objects/rangeobject.c
+++ b/Objects/rangeobject.c
@@ -668,6 +668,16 @@ static PyMappingMethods range_as_mapping = {
         (objobjargproc)0,            /* mp_ass_subscript */
 };
 
+static int
+range_bool(rangeobject* self)
+{
+    return PyObject_IsTrue(self->length);
+}
+
+static PyNumberMethods range_as_number = {
+    .nb_bool = (inquiry)range_bool,
+};
+
 static PyObject * range_iter(PyObject *seq);
 static PyObject * range_reverse(PyObject *seq);
 
@@ -707,7 +717,7 @@ PyTypeObject PyRange_Type = {
         0,                      /* tp_setattr */
         0,                      /* tp_reserved */
         (reprfunc)range_repr,   /* tp_repr */
-        0,                      /* tp_as_number */
+        &range_as_number,       /* tp_as_number */
         &range_as_sequence,     /* tp_as_sequence */
         &range_as_mapping,      /* tp_as_mapping */
         (hashfunc)range_hash,   /* tp_hash */