Don't leak references

Author: markshannon

Include/internal/pycore_list.h

@@ -55,6 +55,7 @@ typedef struct {
 } _PyListIterObject;
 
 PyAPI_FUNC(PyObject *)_PyList_FromArraySteal(PyObject *const *src, Py_ssize_t n);
+PyObject *_PyList_AsTupleStealItems(PyObject *);
 
 #ifdef __cplusplus
 }

Objects/abstract.c

@@ -2069,7 +2069,7 @@ PySequence_Tuple(PyObject *v)
     if (temp == NULL)
         goto Fail;
 
-    /* Fill the tuple. */
+    /* Fill the temporary list. */
     for (;;) {
         PyObject *item = PyIter_Next(it);
         if (item == NULL) {
@@ -2085,7 +2085,7 @@ PySequence_Tuple(PyObject *v)
         }
     }
     Py_DECREF(it);
-    PyObject *result = PyList_AsTuple(temp);
+    PyObject *result = _PyList_AsTupleStealItems(temp);
     Py_DECREF(temp);
     return result;
 

Objects/listobject.c

@@ -3174,6 +3174,25 @@ PyList_AsTuple(PyObject *v)
     return ret;
 }
 
+PyObject *
+_PyList_AsTupleStealItems(PyObject *v)
+{
+    if (v == NULL || !PyList_Check(v)) {
+        PyErr_BadInternalCall();
+        return NULL;
+    }
+    PyObject *ret;
+    PyListObject *self = (PyListObject *)v;
+    if (Py_SIZE(v) == 0) {
+        return PyTuple_New(0);
+    }
+    Py_BEGIN_CRITICAL_SECTION(self);
+    ret = _PyTuple_FromNonEmptyArraySteal(self->ob_item, Py_SIZE(v));
+    Py_SET_SIZE(v, 0);
+    Py_END_CRITICAL_SECTION();
+    return ret;
+}
+
 PyObject *
 _PyList_FromArraySteal(PyObject *const *src, Py_ssize_t n)
 {