[mypyc] Incref items before releasing tuple (#21245)

hauntsaninja · web-flow · commit ef03ccd9b31b · 2026-04-17T10:14:38.000-07:00
diff --git a/mypyc/lib-rt/dict_ops.c b/mypyc/lib-rt/dict_ops.c
@@ -408,6 +408,7 @@ tuple_T4CIOO CPyDict_NextItem(PyObject *dict_or_iter, CPyTagged offset) {
         if (item == NULL || !PyTuple_Check(item) || PyTuple_GET_SIZE(item) != 2) {
             if (item != NULL) {
                 PyErr_SetString(PyExc_TypeError, "a tuple of length 2 expected");
+                Py_DECREF(item);
             }
             ret.f0 = 0;
             ret.f2 = Py_None;
@@ -416,7 +417,10 @@ tuple_T4CIOO CPyDict_NextItem(PyObject *dict_or_iter, CPyTagged offset) {
             ret.f0 = 1;
             ret.f2 = PyTuple_GET_ITEM(item, 0);
             ret.f3 = PyTuple_GET_ITEM(item, 1);
+            Py_INCREF(ret.f2);
+            Py_INCREF(ret.f3);
             Py_DECREF(item);
+            return ret;
         }
     }
     // PyDict_Next() returns borrowed references.

Original file line number	Diff line number	Diff line change
`@@ -408,6 +408,7 @@ tuple_T4CIOO CPyDict_NextItem(PyObject *dict_or_iter, CPyTagged offset) {`
`408`	`408`	`if (item == NULL \|\| !PyTuple_Check(item) \|\| PyTuple_GET_SIZE(item) != 2) {`
`409`	`409`	`if (item != NULL) {`
`410`	`410`	`PyErr_SetString(PyExc_TypeError, "a tuple of length 2 expected");`
	`411`	`+ Py_DECREF(item);`
`411`	`412`	`}`
`412`	`413`	`ret.f0 = 0;`
`413`	`414`	`ret.f2 = Py_None;`
`@@ -416,7 +417,10 @@ tuple_T4CIOO CPyDict_NextItem(PyObject *dict_or_iter, CPyTagged offset) {`
`416`	`417`	`ret.f0 = 1;`
`417`	`418`	`ret.f2 = PyTuple_GET_ITEM(item, 0);`
`418`	`419`	`ret.f3 = PyTuple_GET_ITEM(item, 1);`
	`420`	`+ Py_INCREF(ret.f2);`
	`421`	`+ Py_INCREF(ret.f3);`
`419`	`422`	`Py_DECREF(item);`
	`423`	`+ return ret;`
`420`	`424`	`}`
`421`	`425`	`}`
`422`	`426`	`// PyDict_Next() returns borrowed references.`