Re: [PATCH] analyzer: implement reference count checking for CPython plugin [PR107646]

[David Malcolm <dmalcolm@redhat.com>]

On Tue, 2023-08-29 at 13:28 -0400, Eric Feng wrote:
> Additionally, by using the old model and the pointer per your
> suggestion,
> we are able to find the representative tree and emit a more accurate
> diagnostic!
> 
> rc3.c:23:10: warning: expected ‘item’ to have reference count: ‘1’
> but ob_refcnt field is: ‘2’
>    23 |   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’ succeeds, moving buffer
>     |......
>     |   23 |   return list;
>     |      |          ~~~~
>     |      |          |
>     |      |          (4) here
>     |

Excellent, that's a big improvement.

> 
> If a representative tree is not found, I decided we should just bail
> out
> of emitting a diagnostic for now, to avoid confusing the user on what
> the problem is.

Fair enough.

> 
> I've attached the patch for this (on top of the previous one) below.
> If
> it also looks good, I can merge it with the last patch and push it in
> at
> the same time.

I don't mind either way, but please can you update the tests so that we
have some automated test coverage that the correct name is being
printed in the warning.

Thanks
Dave