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bpo-27145: small_ints[x] could be returned in long_add and long_sub (GH-15716)

This commit is contained in:
HongWeipeng 2019-11-26 15:54:49 +08:00 committed by Inada Naoki
parent 386d00cc34
commit 036fe85bd3
3 changed files with 18 additions and 7 deletions
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8
Lib/test/test_long.py
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@ -956,6 +956,14 @@ class LongTest(unittest.TestCase):
self.assertEqual(huge >> (sys.maxsize + 1), (1 << 499) + 5)
self.assertEqual(huge >> (sys.maxsize + 1000), 0)
@support.cpython_only
def test_small_ints_in_huge_calculation(self):
a = 2 ** 100
b = -a + 1
c = a + 1
self.assertIs(a + b, 1)
self.assertIs(c - a, 1)
def test_small_ints(self):
for i in range(-5, 257):
self.assertIs(i, i + 0)

1
Misc/NEWS.d/next/Core and Builtins/2019-09-06-16-40-12.bpo-27145.njuCXU.rst Normal file
View File

@ -0,0 +1 @@
int + int and int - int operators can now return small integer singletons. Patch by hongweipeng.

10
Objects/longobject.c
View File

@ -3206,7 +3206,7 @@ x_sub(PyLongObject *a, PyLongObject *b)
if (sign < 0) {
Py_SIZE(z) = -Py_SIZE(z);
}
return long_normalize(z);
return maybe_small_long(long_normalize(z));
}
static PyObject *
@ -3254,15 +3254,17 @@ long_sub(PyLongObject *a, PyLongObject *b)
return PyLong_FromLong(MEDIUM_VALUE(a) - MEDIUM_VALUE(b));
}
if (Py_SIZE(a) < 0) {
if (Py_SIZE(b) < 0)
z = x_sub(a, b);
else
if (Py_SIZE(b) < 0) {
z = x_sub(b, a);
}
else {
z = x_add(a, b);
if (z != NULL) {
assert(Py_SIZE(z) == 0 || Py_REFCNT(z) == 1);
Py_SIZE(z) = -(Py_SIZE(z));
}
}
}
else {
if (Py_SIZE(b) < 0)
z = x_add(a, b);