fix more qApp crashes

When building PySide with a debug Python, a lot more problems
become visible.

They were triggered by some malicious ordering of the shutdown code,
which must come *after* the refcounts of the variables are adjusted.

The initial issue PYSIDE-585 was caused because the shutdown code
is not only used for every created Q*Application, but also for the
module shutdown, which deletes qApp_contents too often.
Instead of special-casing that or adding some refcount, it was much
more intuitive in that context to set  qApp_content's refcount to the
same value as Py_None, which also is not supposed to be garbage
collected.

Btw., the reason for the error message is that Py_None has it, too.
When we set qApp_content's type to Py_None's type, it inherits
the protection code that prevents someone from garbage collecting
Py_None.

Task-number: PYSIDE-585
Change-Id: I4af9de1192730f06054a5aca099a32e2392e367d
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

1 files changed, 1 insertions, 1 deletions

diff --git a/sources/pyside2/libpyside/pyside.cpp b/sources/pyside2/libpyside/pyside.cpp
index b223edc6c..4c7e6471c 100644
--- a/sources/pyside2/libpyside/pyside.cpp
+++ b/sources/pyside2/libpyside/pyside.cpp
@@ -162,10 +162,10 @@ static void destructionVisitor(SbkObject* pyObj, void* data)
 
 void destroyQCoreApplication()
 {
-    SignalManager::instance().clear();
     QCoreApplication* app = QCoreApplication::instance();
     if (!app)
         return;
+    SignalManager::instance().clear();
 
     Shiboken::BindingManager& bm = Shiboken::BindingManager::instance();
     SbkObject* pyQApp = bm.retrieveWrapper(app);