Turn qApp into a normal Python variable, finally

After a long odyssey of more or less unpythonic compromizes,
the qApp "macro" would finally be moved into a normal
variable without surprizes.

This was only possible since we removed qApp from QtWidgets
and other modules. Otherwise,

    from PySide2.QtWidgets import *

would pull qApp, being the constant "None", into main and
shadow the true qApp variable in the builtins.

By inserting qApp into the builtins, only, we make sure that
this variable is always freshly looked up, without making it
change its contents.

DONE...
+ change the singleton code to normal
+ rename to MakeQAppWrapper
+ simplify the implementation
+ fix new bug concerning duplicate applications
+ check very much for refcounting bugs
+ review the rest of the implementation and further simplify

Note... The Q*Application variable will not be turned back into
a GC variable. This is not worth the effort.

Fixes: PYSIDE-571
Change-Id: Idbd158c083318e6b0dfe48d62485c68c90e944de
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>

1 files changed, 2 insertions, 2 deletions

diff --git a/sources/pyside2/PySide2/glue/qtcore.cpp b/sources/pyside2/PySide2/glue/qtcore.cpp
index d99a150ad..e54fa1846 100644
--- a/sources/pyside2/PySide2/glue/qtcore.cpp
+++ b/sources/pyside2/PySide2/glue/qtcore.cpp
@@ -1430,8 +1430,8 @@ if (qApp) {
         // this will keep app live after python exit (extra ref)
 }
 // PYSIDE-571: make sure that we return the singleton "None"
-if (pyApp == Py_None)
-    Py_DECREF(MakeSingletonQAppWrapper(nullptr)); // here qApp and instance() diverge
+if (Py_TYPE(pyApp) == Py_TYPE(Py_None))
+    Py_DECREF(MakeQAppWrapper(nullptr));
 %PYARG_0 = pyApp;
 Py_XINCREF(%PYARG_0);
 // @snippet qcoreapplication-instance