QWidget: replace manual memory management with unique_ptr [3/N]: topextra->shareContext

Despite the name, it's fully owned by an individual QWidget object.

Also make the member mutable, so we can remove the const_cast hack in
QWidgetPrivate::shareContext(), and protect QT_NO_OPENGL builds, since
the naked pointer compiled by chance due to some unguarded forward
declarations while a unique_ptr will somewhere want to call the dtor,
which doesn't compile on an object of merely forward-declared type.

Change-Id: If8027b55d303822236fcdc1a79e4f3010967b4d2
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 4 insertions, 7 deletions

diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 68ce8d5d15..78a8af62df 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -1799,7 +1799,6 @@ void QWidgetPrivate::createTLExtra()
         x->inTopLevelResize = false;
         x->embedded = 0;
         x->window = 0;
-        x->shareContext = 0;
         x->initialScreenIndex = -1;
 #if 0 // Used to be included in Qt4 for Q_WS_MAC
         x->wasMaximized = false;
@@ -1903,8 +1902,7 @@ void QWidgetPrivate::deleteTLSysExtra()
         deleteBackingStore(this);
 #ifndef QT_NO_OPENGL
         extra->topextra->widgetTextures.clear();
-        delete extra->topextra->shareContext;
-        extra->topextra->shareContext = 0;
+        extra->topextra->shareContext.reset();
 #endif
 
         //the toplevel might have a context with a "qglcontext associated with it. We need to
@@ -12413,16 +12411,15 @@ QOpenGLContext *QWidgetPrivate::shareContext() const
     if (Q_UNLIKELY(!extra || !extra->topextra || !extra->topextra->window))
         return 0;
 
-    QWidgetPrivate *that = const_cast<QWidgetPrivate *>(this);
     if (!extra->topextra->shareContext) {
-        QOpenGLContext *ctx = new QOpenGLContext;
+        auto ctx = qt_make_unique<QOpenGLContext>();
         ctx->setShareContext(qt_gl_global_share_context());
         ctx->setFormat(extra->topextra->window->format());
         ctx->setScreen(extra->topextra->window->screen());
         ctx->create();
-        that->extra->topextra->shareContext = ctx;
+        extra->topextra->shareContext = std::move(ctx);
     }
-    return that->extra->topextra->shareContext;
+    return extra->topextra->shareContext.get();
 #endif // QT_NO_OPENGL
 }