[Python-Dev] PyErr_NoMemory

[Vladimir Marangozov]

The current PyErr_NoMemory() function reads:

PyObject *
PyErr_NoMemory(void)
{
        /* raise the pre-allocated instance if it still exists */
        if (PyExc_MemoryErrorInst)
                PyErr_SetObject(PyExc_MemoryError, PyExc_MemoryErrorInst);
        else
                /* this will probably fail since there's no memory and hee,
                   hee, we have to instantiate this class
                */
                PyErr_SetNone(PyExc_MemoryError);

        return NULL;
}

thus overriding any previous exceptions unconditionally. This is a
problem when the current exception already *is* PyExc_MemoryError,
notably when we have a chain (cascade) of memory errors. It is a
problem because the original memory error and eventually its error
message is lost.

I suggest to make this code look like:

PyObject *
PyErr_NoMemory(void)
{
	if (PyErr_ExceptionMatches(PyExc_MemoryError))
		/* already current */
		return NULL;

        /* raise the pre-allocated instance if it still exists */
        if (PyExc_MemoryErrorInst)
                PyErr_SetObject(PyExc_MemoryError, PyExc_MemoryErrorInst);
...


If nobody sees a problem with this, I'm very tempted to check it in.
Any objections?

-- 
       Vladimir MARANGOZOV          | Vladimir.Marangozov@inrialpes.fr
http://sirac.inrialpes.fr/~marangoz | tel:(+33-4)76615277 fax:76615252