Accept NULL in Add() and AddSteal()

vstinner · Oct 7, 2025 · Oct 10, 2025 · Oct 10, 2025 · Oct 10, 2025 · Oct 10, 2025
commit 8e7025fd6650605763ef6f0d33541238b173b6d7
@@ -203,8 +203,9 @@ object.
 
    Add an item to *writer*.
 
-   On success, return ``0``.
-   On error, set an exception and return ``-1``.
+   * On success, return ``0``.
+   * If *item* is ``NULL``, return ``-1`` with an exception set.
+   * On error, set an exception and return ``-1``.
 
 .. c:function:: int PyTupleWriter_AddSteal(PyTupleWriter *writer, PyObject *item)
 

diff --git a/Lib/test/test_capi/test_tuple.py b/Lib/test/test_capi/test_tuple.py
@@ -330,6 +330,11 @@ def check_add(self, name):
              add(i)
          self.assertEqual(writer.finish(), tuple(range(1024)))
 
+         writer = self.create_writer(1)
+         add = getattr(writer, name)
+         with self.assertRaises(SystemError):
+             add(NULL)
+
     def test_add(self):
          # Test PyTupleWriter_Add()
          self.check_add('add')

diff --git a/Modules/_testcapi/tuple.c b/Modules/_testcapi/tuple.c
@@ -207,6 +207,8 @@ writer_check(WriterObject *self)
 static PyObject*
 writer_add(PyObject *self_raw, PyObject *item)
 {
+    NULLABLE(item);
+
     WriterObject *self = (WriterObject *)self_raw;
     if (writer_check(self) < 0) {
         return NULL;
@@ -222,12 +224,14 @@ writer_add(PyObject *self_raw, PyObject *item)
 static PyObject*
 writer_add_steal(PyObject *self_raw, PyObject *item)
 {
+    NULLABLE(item);
+
     WriterObject *self = (WriterObject *)self_raw;
     if (writer_check(self) < 0) {
         return NULL;
     }
 
-    if (PyTupleWriter_AddSteal(self->writer, Py_NewRef(item)) < 0) {
+    if (PyTupleWriter_AddSteal(self->writer, Py_XNewRef(item)) < 0) {
         return NULL;
     }
     Py_RETURN_NONE;

diff --git a/Objects/abstract.c b/Objects/abstract.c
@@ -2024,11 +2024,8 @@ PySequence_Tuple(PyObject *v)
     }
 
     for (;;) {
-        PyObject *item = PyIter_Next(it);
-        if (item == NULL) {
-            if (PyErr_Occurred()) {
-                goto fail;
-            }
+        PyObject *item;
+        if (PyIter_NextItem(it, &item) == 0) {
             break;
         }
         if (PyTupleWriter_AddSteal(writer, item) < 0) {

diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
@@ -1308,6 +1308,13 @@ PyTupleWriter_Create(Py_ssize_t size)
 int
 PyTupleWriter_Add(PyTupleWriter *writer, PyObject *item)
 {
+    if (item == NULL) {
+        if (!PyErr_Occurred()) {
+            PyErr_BadInternalCall();
+        }
+        return -1;
+    }
+
     if (writer->size >= writer->allocated) {
         if (_PyTupleWriter_SetSize(writer, writer->size + 1, 1) < 0) {
             return -1;
@@ -1323,6 +1330,13 @@ PyTupleWriter_Add(PyTupleWriter *writer, PyObject *item)
 int
 PyTupleWriter_AddSteal(PyTupleWriter *writer, PyObject *item)
 {
+    if (item == NULL) {
+        if (!PyErr_Occurred()) {
+            PyErr_BadInternalCall();
+        }
+        return -1;
+    }
+
     if (writer->size >= writer->allocated) {
         if (_PyTupleWriter_SetSize(writer, writer->size + 1, 1) < 0) {
             Py_DECREF(item);