1 files changed, 32 insertions, 7 deletions

diff --git a/sources/shiboken6/libshiboken/basewrapper.cpp b/sources/shiboken6/libshiboken/basewrapper.cpp
index 62e2df2cf..7f927523a 100644
--- a/sources/shiboken6/libshiboken/basewrapper.cpp
+++ b/sources/shiboken6/libshiboken/basewrapper.cpp
@@ -95,6 +95,13 @@ static void SbkObjectTypeDealloc(PyObject *pyObj);
 static PyObject *SbkObjectTypeTpNew(PyTypeObject *metatype, PyObject *args, PyObject *kwds);
 
 static SelectableFeatureHook SelectFeatureSet = nullptr;
+static DestroyQAppHook DestroyQApplication = nullptr;
+
+// PYSIDE-1470: Provide a hook to kill an Application from Shiboken.
+void setDestroyQApplication(DestroyQAppHook func)
+{
+    DestroyQApplication = func;
+}
 
 static PyObject *Sbk_TypeGet___dict__(PyTypeObject *type, void *context);   // forward
 
@@ -457,6 +464,12 @@ PyObject *MakeQAppWrapper(PyTypeObject *type)
     // object already has a reference from PyObject_GC_New. But this is
     // exactly the needed reference that keeps qApp alive from alone!
     Py_INCREF(qApp_curr);
+    // PYSIDE-1470: As a side effect, the interactive "_" variable tends to
+    // create reference cycles. It was found when using gc.collect(). But using
+    // PyGC_collect() inside the C code had no effect in the interactive shell.
+    // The cycle exists only in the eval loop of the interpreter!
+    if (PyDict_GetItem(builtins, Shiboken::PyName::underscore()))
+        PyDict_SetItem(builtins, Shiboken::PyName::underscore(), Py_None);
     return qApp_curr;
 }
 
@@ -673,7 +686,12 @@ PyObject *SbkObjectTpNew(PyTypeObject *subtype, PyObject *, PyObject *)
 PyObject *SbkQAppTpNew(PyTypeObject *subtype, PyObject *, PyObject *)
 {
     auto self = reinterpret_cast<SbkObject *>(MakeQAppWrapper(subtype));
-    return self == nullptr ? nullptr : _setupNew(self, subtype);
+    if (self == nullptr)
+        return nullptr;
+    auto ret = _setupNew(self, subtype);
+    auto priv = self->d;
+    priv->isQAppSingleton = 1;
+    return ret;
 }
 
 PyObject *SbkDummyNew(PyTypeObject *type, PyObject *, PyObject *)
@@ -1154,6 +1172,12 @@ bool wasCreatedByPython(SbkObject *pyObj)
 
 void callCppDestructors(SbkObject *pyObj)
 {
+    auto priv = pyObj->d;
+    if (priv->isQAppSingleton && DestroyQApplication) {
+        // PYSIDE-1470: Allow to destroy the application from Shiboken.
+        DestroyQApplication();
+        return;
+    }
     PyTypeObject *type = Py_TYPE(pyObj);
     SbkObjectTypePrivate *sotp = PepType_SOTP(type);
     if (sotp->is_multicpp) {
@@ -1166,18 +1190,19 @@ void callCppDestructors(SbkObject *pyObj)
         sotp->cpp_dtor(pyObj->d->cptr[0]);
     }
 
+    if (priv->validCppObject && priv->containsCppWrapper) {
+        BindingManager::instance().releaseWrapper(pyObj);
+    }
+
     /* invalidate needs to be called before deleting pointer array because
        it needs to delete entries for them from the BindingManager hash table;
        also release wrapper explicitly if object contains C++ wrapper because
        invalidate doesn't */
     invalidate(pyObj);
-    if (pyObj->d->validCppObject && pyObj->d->containsCppWrapper) {
-      BindingManager::instance().releaseWrapper(pyObj);
-    }
 
-    delete[] pyObj->d->cptr;
-    pyObj->d->cptr = nullptr;
-    pyObj->d->validCppObject = false;
+    delete[] priv->cptr;
+    priv->cptr = nullptr;
+    priv->validCppObject = false;
 }
 
 bool hasOwnership(SbkObject *pyObj)