`take_ownership` may erroneously clear MemoryError exceptions

[mpage]

Bug report

Bug description:

take_ownership clears any MemoryError exceptions when getting the previous frame fails (even if they were not raised by the call to _PyFrame_GetFrameObject):

cpython/Python/frame.c

Lines 74 to 79 in 1e4a434

	PyFrameObject *back = _PyFrame_GetFrameObject(prev);
	if (back == NULL) {
	/* Memory error here. */
	assert(PyErr_ExceptionMatches(PyExc_MemoryError));
	/* Nothing we can do about it */
	PyErr_Clear();

I think we should save and restore the exception around the call to _PyFrame_GetFrameObject(prev). Something like:

PyObject *exc = PyErr_GetRaisedException();
PyFrameObject *back = _PyFrame_GetFrameObject(prev);
if (back == NULL) {
    /* Memory error here. */
    assert(PyErr_ExceptionMatches(PyExc_MemoryError));
    /* Nothing we can do about it */
    PyErr_Clear();
}
else {
    f->f_back = (PyFrameObject *)Py_NewRef(back);
}
PyErr_SetRaisedException(exc);

CPython versions tested on:

3.14, CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-131173: Improve exception handling during take_ownership processing #132620