Merge remote-tracking branch 'origin/5.15' into dev

 Conflicts:
	src/corelib/text/qstringliteral.h

Change-Id: I1665af3ce537471b249def5e080b39bd4105189e

1 files changed, 4 insertions, 2 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoabackingstore.mm b/src/plugins/platforms/cocoa/qcocoabackingstore.mm
index c734be09b6..97bb4e8bed 100644
--- a/src/plugins/platforms/cocoa/qcocoabackingstore.mm
+++ b/src/plugins/platforms/cocoa/qcocoabackingstore.mm
@@ -536,8 +536,10 @@ void QCALayerBackingStore::flush(QWindow *flushedWindow, const QRegion &region,
         flushedView.layer.contentsScale = m_buffers.back()->devicePixelRatio();
     }
 
+    const bool isSingleBuffered = window()->format().swapBehavior() == QSurfaceFormat::SingleBuffer;
+
     id backBufferSurface = (__bridge id)m_buffers.back()->surface();
-    if (flushedView.layer.contents == backBufferSurface) {
+    if (!isSingleBuffered && flushedView.layer.contents == backBufferSurface) {
         // We've managed to paint to the back buffer again before Core Animation had time
         // to flush the transaction and persist the layer changes to the window server, or
         // we've been asked to flush without painting anything. The layer already knows about
@@ -554,7 +556,7 @@ void QCALayerBackingStore::flush(QWindow *flushedWindow, const QRegion &region,
     // with other pending view and layer updates.
     flushedView.window.viewsNeedDisplay = YES;
 
-    if (window()->format().swapBehavior() == QSurfaceFormat::SingleBuffer) {
+    if (isSingleBuffered) {
         // The private API [CALayer reloadValueForKeyPath:@"contents"] would be preferable,
         // but barring any side effects or performance issues we opt for the hammer for now.
         flushedView.layer.contents = nil;