bpo-30281: Fix the default value for stop in PySlice_Unpack() (#1480) (#1529)
diff --git a/Objects/sliceobject.c b/Objects/sliceobject.c
index 6a69021..4e4b32d 100644
--- a/Objects/sliceobject.c
+++ b/Objects/sliceobject.c
@@ -197,6 +197,8 @@
PySliceObject *r = (PySliceObject*)_r;
/* this is harder to get right than you might think */
+ Py_BUILD_ASSERT(PY_SSIZE_T_MIN + 1 <= -PY_SSIZE_T_MAX);
+
if (r->step == Py_None) {
*step = 1;
}
@@ -217,14 +219,14 @@
}
if (r->start == Py_None) {
- *start = *step < 0 ? PY_SSIZE_T_MAX-1 : 0;;
+ *start = *step < 0 ? PY_SSIZE_T_MAX : 0;
}
else {
if (!_PyEval_SliceIndex(r->start, start)) return -1;
}
if (r->stop == Py_None) {
- *stop = *step < 0 ? -PY_SSIZE_T_MAX : PY_SSIZE_T_MAX;
+ *stop = *step < 0 ? PY_SSIZE_T_MIN : PY_SSIZE_T_MAX;
}
else {
if (!_PyEval_SliceIndex(r->stop, stop)) return -1;
@@ -258,7 +260,7 @@
*stop = (step < 0) ? -1 : 0;
}
}
- else if (*stop >= length) {
+ else if (*stop >= length) {
*stop = (step < 0) ? length - 1 : length;
}
diff --git a/Python/ceval.c b/Python/ceval.c
index bce86ab..5dc0444 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -5071,7 +5071,7 @@
/* Extract a slice index from a PyLong or an object with the
nb_index slot defined, and store in *pi.
Silently reduce values larger than PY_SSIZE_T_MAX to PY_SSIZE_T_MAX,
- and silently boost values less than -PY_SSIZE_T_MAX-1 to -PY_SSIZE_T_MAX-1.
+ and silently boost values less than PY_SSIZE_T_MIN to PY_SSIZE_T_MIN.
Return 0 on error, 1 on success.
*/
int