https://github.com/python/cpython/commit/66bca383bd3b12d21e879d991d77b37a4c638f88
commit: 66bca383bd3b12d21e879d991d77b37a4c638f88
branch: main
author: Serhiy Storchaka <[email protected]>
committer: serhiy-storchaka <[email protected]>
date: 2026-01-09T19:06:45+02:00
summary:
gh-143006: Fix and optimize mixed comparison of float and int (GH-143084)
When comparing negative non-integer float and int with the same number
of bits in the integer part, __neg__() in the int subclass returning
not an int caused an assertion error.
Now the integer is no longer negated. Also, reduced the number of
temporary created Python objects.
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2025-12-22-22-37-53.gh-issue-143006.ZBQwbN.rst
M Lib/test/test_float.py
M Objects/floatobject.c
diff --git a/Lib/test/test_float.py b/Lib/test/test_float.py
index 00518abcb11b46..c03b0a09f71889 100644
--- a/Lib/test/test_float.py
+++ b/Lib/test/test_float.py
@@ -651,6 +651,24 @@ class F(float, H):
value = F('nan')
self.assertEqual(hash(value), object.__hash__(value))
+ def test_issue_gh143006(self):
+ # When comparing negative non-integer float and int with the
+ # same number of bits in the integer part, __neg__() in the
+ # int subclass returning not an int caused an assertion error.
+ class EvilInt(int):
+ def __neg__(self):
+ return ""
+
+ i = -1 << 50
+ f = float(i) - 0.5
+ i = EvilInt(i)
+ self.assertFalse(f == i)
+ self.assertTrue(f != i)
+ self.assertTrue(f < i)
+ self.assertTrue(f <= i)
+ self.assertFalse(f > i)
+ self.assertFalse(f >= i)
+
@unittest.skipUnless(hasattr(float, "__getformat__"), "requires __getformat__")
class FormatFunctionsTestCase(unittest.TestCase):
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2025-12-22-22-37-53.gh-issue-143006.ZBQwbN.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2025-12-22-22-37-53.gh-issue-143006.ZBQwbN.rst
new file mode 100644
index 00000000000000..f25620389fd5cd
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2025-12-22-22-37-53.gh-issue-143006.ZBQwbN.rst
@@ -0,0 +1,2 @@
+Fix a possible assertion error when comparing negative non-integer ``float``
+and ``int`` with the same number of bits in the integer part.
diff --git a/Objects/floatobject.c b/Objects/floatobject.c
index 2cb690748d9de4..579765281ca484 100644
--- a/Objects/floatobject.c
+++ b/Objects/floatobject.c
@@ -435,82 +435,67 @@ float_richcompare(PyObject *v, PyObject *w, int op)
assert(vsign != 0); /* if vsign were 0, then since wsign is
* not 0, we would have taken the
* vsign != wsign branch at the start */
- /* We want to work with non-negative numbers. */
- if (vsign < 0) {
- /* "Multiply both sides" by -1; this also swaps the
- * comparator.
- */
- i = -i;
- op = _Py_SwappedOp[op];
- }
- assert(i > 0.0);
(void) frexp(i, &exponent);
/* exponent is the # of bits in v before the radix point;
* we know that nbits (the # of bits in w) > 48 at this point
*/
if (exponent < nbits) {
- i = 1.0;
- j = 2.0;
+ j = i;
+ i = 0.0;
goto Compare;
}
if (exponent > nbits) {
- i = 2.0;
- j = 1.0;
+ j = 0.0;
goto Compare;
}
/* v and w have the same number of bits before the radix
- * point. Construct two ints that have the same comparison
- * outcome.
+ * point. Construct an int from the integer part of v and
+ * update op if necessary, so comparing two ints has the same outcome.
*/
{
double fracpart;
double intpart;
PyObject *result = NULL;
PyObject *vv = NULL;
- PyObject *ww = w;
- if (wsign < 0) {
- ww = PyNumber_Negative(w);
- if (ww == NULL)
- goto Error;
+ fracpart = modf(i, &intpart);
+ if (fracpart != 0.0) {
+ switch (op) {
+ /* Non-integer float never equals to an int. */
+ case Py_EQ:
+ Py_RETURN_FALSE;
+ case Py_NE:
+ Py_RETURN_TRUE;
+ /* For non-integer float, v <= w <=> v < w.
+ * If v > 0: trunc(v) < v < trunc(v) + 1
+ * v < w => trunc(v) < w
+ * trunc(v) < w => trunc(v) + 1 <= w => v < w
+ * If v < 0: trunc(v) - 1 < v < trunc(v)
+ * v < w => trunc(v) - 1 < w => trunc(v) <= w
+ * trunc(v) <= w => v < w
+ */
+ case Py_LT:
+ case Py_LE:
+ op = vsign > 0 ? Py_LT : Py_LE;
+ break;
+ /* The same as above, but with opposite directions. */
+ case Py_GT:
+ case Py_GE:
+ op = vsign > 0 ? Py_GE : Py_GT;
+ break;
+ }
}
- else
- Py_INCREF(ww);
- fracpart = modf(i, &intpart);
vv = PyLong_FromDouble(intpart);
if (vv == NULL)
goto Error;
- if (fracpart != 0.0) {
- /* Shift left, and or a 1 bit into vv
- * to represent the lost fraction.
- */
- PyObject *temp;
-
- temp = _PyLong_Lshift(ww, 1);
- if (temp == NULL)
- goto Error;
- Py_SETREF(ww, temp);
-
- temp = _PyLong_Lshift(vv, 1);
- if (temp == NULL)
- goto Error;
- Py_SETREF(vv, temp);
-
- temp = PyNumber_Or(vv, _PyLong_GetOne());
- if (temp == NULL)
- goto Error;
- Py_SETREF(vv, temp);
- }
-
- r = PyObject_RichCompareBool(vv, ww, op);
+ r = PyObject_RichCompareBool(vv, w, op);
if (r < 0)
goto Error;
result = PyBool_FromLong(r);
Error:
Py_XDECREF(vv);
- Py_XDECREF(ww);
return result;
}
} /* else if (PyLong_Check(w)) */
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