On Mon, Aug 21, 2023 at 11:04 AM David Malcolm <dmalc...@redhat.com> wrote: > > On Mon, 2023-08-21 at 10:05 -0400, Eric Feng wrote: > > Hi Dave, > > > > Just wanted to give you and everyone else a short update on how > > reference count checking is going — we can now observe the refcnt > > diagnostic being emitted: > > > > rc3.c:22:10: warning: REF COUNT PROBLEM > > 22 | return list; > > | ^~~~ > > ‘create_py_object’: events 1-4 > > | > > | 4 | PyObject* item = PyLong_FromLong(3); > > | | ^~~~~~~~~~~~~~~~~~ > > | | | > > | | (1) when ‘PyLong_FromLong’ succeeds > > | 5 | PyObject* list = PyList_New(1); > > | | ~~~~~~~~~~~~~ > > | | | > > | | (2) when ‘PyList_New’ succeeds > > |...... > > | 14 | PyList_Append(list, item); > > | | ~~~~~~~~~~~~~~~~~~~~~~~~~ > > | | | > > | | (3) when ‘PyList_Append’ fails > > |...... > > | 22 | return list; > > | | ~~~~ > > | | | > > | | (4) here > > | > > > > I will fix up and refactor the logic for counting the actual ref > > count > > before coming back and refining the diagnostic to give much more > > detailed information. > > Excellent! Thanks for the update. > > Dave >
Hi Dave, I've since fixed up the logic to count the actual reference counts of the PyObject* instances. Now, I'm contemplating the specific diagnostics we'd want to issue and the appropriate conditions for emitting them. With this in mind, I wanted to check in with you on the appropriate approach: To start, I'm adopting the same assumptions as cpychecker for functions returning a PyObject*. That is, I'm operating under the premise that by default such functions return a new reference upon success rather than, for example, a borrowed reference (which we can tackle later on). Given this, it's my understanding that the reference count of the returned object should be 1 if the object is newly created within the function body and incremented by 1 from what it was previously if not newly created (e.g passed in as an argument). Furthermore, the reference count for any PyObject* instances created within the function should be 0, barring situations where we're returning a collection, like a list, that includes references to these objects. Let me know what you think; thanks! Best, Eric
