signature: Fix a refcount bug in SetError_Argument

When a real error occurs in `SetError_Argument`, there is
an open PyErr_Fetch call that will not be closed because
we redirect the whole exception to the `seterror_argument`
function in errorhandler.py .

This is a similar case as the refcounting leak in
`mangled_type_getattro` PYSIDE-2169 . I did not know
that PyErr_Fetch/PyErr_Restore use refcounting.

Change-Id: I042c1d858c57834d707139f7290bc15b9dd5cc0e
Task-number: PYSIDE-1564
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
(cherry picked from commit 5599354825bf767a87dfc22cbd260e419d92ef0d)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/sources/shiboken6/libshiboken/signature/signature.cpp b/sources/shiboken6/libshiboken/signature/signature.cpp
index f83618779..b9e1fec40 100644
--- a/sources/shiboken6/libshiboken/signature/signature.cpp
+++ b/sources/shiboken6/libshiboken/signature/signature.cpp
@@ -583,7 +583,9 @@ void SetError_Argument(PyObject *args, const char *func_name, PyObject *info)
         PyObject *e, *v, *t;
         // Note: These references are all borrowed.
         PyErr_Fetch(&e, &v, &t);
+        Py_DECREF(e);
         info = v;
+        Py_XDECREF(t);
     }
     // PYSIDE-1019: Modify the function name expression according to feature.
     AutoDecRef new_func_name(adjustFuncName(func_name));