SignalInstance: Fix another very old bug

When a SignalInstance is initialized with wrong arguments, it is
immediately deallocated. The deallocation was not aware that
certain structures were not initialized.

Task-number: PYSIDE-79
Change-Id: I4999bfc3eac1239cfbe8216d5ad574ba17b3ac85
Pick-to: 6.4
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

1 files changed, 8 insertions, 7 deletions

diff --git a/sources/pyside6/libpyside/pysidesignal.cpp b/sources/pyside6/libpyside/pysidesignal.cpp
index f7c9073c2..291de73d8 100644
--- a/sources/pyside6/libpyside/pysidesignal.cpp
+++ b/sources/pyside6/libpyside/pysidesignal.cpp
@@ -334,15 +334,16 @@ static void signalInstanceFree(void *vself)
     auto self = reinterpret_cast<PySideSignalInstance *>(vself);
 
     PySideSignalInstancePrivate *dataPvt = self->d;
+    if (dataPvt) {
+        Py_XDECREF(dataPvt->homonymousMethod);
 
-    Py_XDECREF(dataPvt->homonymousMethod);
-
-    if (dataPvt->next) {
-        Py_DECREF(dataPvt->next);
-        dataPvt->next = nullptr;
+        if (dataPvt->next) {
+            Py_DECREF(dataPvt->next);
+            dataPvt->next = nullptr;
+        }
+        delete dataPvt;
+        self->d = nullptr;
     }
-    delete dataPvt;
-    self->d = nullptr;
     self->deleted = true;
     Py_TYPE(pySelf)->tp_base->tp_free(self);
 }