Issue #25604: Fix bug in integer true division that could have resulted in off-by-one-ulp results in unusual cases.
diff --git a/Misc/NEWS b/Misc/NEWS
index e393d32..392e9e7 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,10 @@
Core and Builtins
-----------------
+- Issue #25604: Fix a minor bug in integer true division; this bug could
+ potentially have caused off-by-one-ulp results on platforms with
+ unreliable ldexp implementations.
+
- Issue #27473: Fixed possible integer overflow in str, unicode and bytearray
concatenations and repetitions. Based on patch by Xiang Zhang.
diff --git a/Objects/longobject.c b/Objects/longobject.c
index ead8f28..6f469bf 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -3315,9 +3315,9 @@
/* Round by directly modifying the low digit of x. */
mask = (digit)1 << (extra_bits - 1);
low = x->ob_digit[0] | inexact;
- if (low & mask && low & (3*mask-1))
+ if ((low & mask) && (low & (3U*mask-1U)))
low += mask;
- x->ob_digit[0] = low & ~(mask-1U);
+ x->ob_digit[0] = low & ~(2U*mask-1U);
/* Convert x to a double dx; the conversion is exact. */
dx = x->ob_digit[--x_size];