PyList_GetItem not idempotent

Question

I'm trying out Swig and have the following C code and interface respectively:

// example.c
#include <Python/Python.h>
PyObject *test ( PyObject *self, int i) {
    PyObject **x;
    x = malloc(sizeof(PyObject *));
    *x = PyList_GetItem(self, i);
    return *x;
}

// example.i
%module example
%{
/* Put header files here or function declarations like below */
extern PyObject* test(PyObject *self, int i);
%}

extern PyObject* test(PyObject *self, int i);

It compiles properly and I can import the extension module fine. In fact, when I define a variable a to be [{1:1},{2:2}] and do example.test(a, 0) for the first time, it properly returns {1,1}. When I enter a into the Python shell, I get [{1:1},{2:2}] as expected. When I try example.test(a,0) again, I get a segmentation fault. Any ideas why this is happening?

Answer 1

PyObject* PyList_GetItem(PyObject *list, Py_ssize_t index)
Return value: Borrowed reference.

Incref the object before returning it.