Deprecate QString::null

It's a Qt 3 compatibility vehicle, and as such inherits the now-alien
property to distinguish empty and null strings. Particularly worrisome
is the following asymmetry:

   QString("") == QString::null          // false
   QString("") == QString(QString::null) // true

Instead of fixing this behavior, recognize that people might use it as
a weird way to call isNull(), albeit one that once was idiomatic, and
simply deprecate everything that deals with QString::null.

[ChangeLog][QtCore][QString] QString::null is now deprecated. When
used to construct a QString, use QString() instead. When used to
compare to a QString, replace with QString::isNull().

Change-Id: I9f7e84a92522c75666da15f49324c500ae93af42
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Anton Kudryavtsev <antkudr@mail.ru>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/widgets/widgets/qmdisubwindow.cpp b/src/widgets/widgets/qmdisubwindow.cpp
index a627c86871..a8cdca1719 100644
--- a/src/widgets/widgets/qmdisubwindow.cpp
+++ b/src/widgets/widgets/qmdisubwindow.cpp
@@ -1863,7 +1863,7 @@ void QMdiSubWindowPrivate::removeButtonsFromMenuBar()
     topLevelWindow->removeEventFilter(q);
     if (baseWidget && !drawTitleBarWhenMaximized())
         topLevelWindow->setWindowModified(false);
-    originalTitle = QString::null;
+    originalTitle.clear();
 }
 
 #endif // QT_NO_MENUBAR
@@ -2769,7 +2769,7 @@ bool QMdiSubWindow::eventFilter(QObject *object, QEvent *event)
 #ifndef QT_NO_MENUBAR
         } else if (maximizedButtonsWidget() && d->controlContainer->menuBar() && d->controlContainer->menuBar()
                    ->cornerWidget(Qt::TopRightCorner) == maximizedButtonsWidget()) {
-            d->originalTitle = QString::null;
+            d->originalTitle.clear();
             if (d->baseWidget && d->baseWidget->windowTitle() == windowTitle())
                 d->updateWindowTitle(true);
             else