Fix undefined behaviour (left shift of negative value) in long_hash. Also,
rewrap a line of length > 79, and update comments.
diff --git a/Objects/longobject.c b/Objects/longobject.c
index 0a320e6..fdb5664 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -1962,7 +1962,7 @@
static long
long_hash(PyLongObject *v)
{
- long x;
+ unsigned long x;
Py_ssize_t i;
int sign;
@@ -1977,17 +1977,18 @@
i = -(i);
}
#define LONG_BIT_PyLong_SHIFT (8*sizeof(long) - PyLong_SHIFT)
- /* The following loop produces a C long x such that (unsigned long)x
- is congruent to the absolute value of v modulo ULONG_MAX. The
- resulting x is nonzero if and only if v is. */
+ /* The following loop produces a C long x such that x is congruent to
+ the absolute value of v modulo ULONG_MAX. The resulting x is
+ nonzero if and only if v is. */
while (--i >= 0) {
/* Force a native long #-bits (32 or 64) circular shift */
- x = ((x << PyLong_SHIFT) & ~PyLong_MASK) | ((x >> LONG_BIT_PyLong_SHIFT) & PyLong_MASK);
+ x = ((x << PyLong_SHIFT) & ~PyLong_MASK) |
+ ((x >> LONG_BIT_PyLong_SHIFT) & PyLong_MASK);
x += v->ob_digit[i];
- /* If the addition above overflowed (thinking of x as
- unsigned), we compensate by incrementing. This preserves
- the value modulo ULONG_MAX. */
- if ((unsigned long)x < v->ob_digit[i])
+ /* If the addition above overflowed we compensate by
+ incrementing. This preserves the value modulo
+ ULONG_MAX. */
+ if (x < v->ob_digit[i])
x++;
}
#undef LONG_BIT_PyLong_SHIFT