xcb: eradicate Q_FOREACH loops [needing qAsConst()]

... by replacing them with C++11 range-for loops.
To avoid detaches of these mutable Qt containers,
wrap the container in qAsConst().

Saves more than 2KiB in text size on optimized GCC 6.0
Linux AMD64 builds.

Change-Id: I9610e711edc01d2a1ba19fef65d6b000ffc77255
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>

src/plugins/platforms/xcb/qxcbconnection.cpp

@@ -522,7 +522,7 @@ void QXcbConnection::initializeScreens()
         ++xcbScreenNumber;
     } // for each xcb screen
 
-    foreach (QXcbVirtualDesktop *virtualDesktop, m_virtualDesktops)
+    for (QXcbVirtualDesktop *virtualDesktop : qAsConst(m_virtualDesktops))
         virtualDesktop->subscribeToXFixesSelectionNotify();
 
     if (m_virtualDesktops.isEmpty()) {
@@ -537,7 +537,7 @@ void QXcbConnection::initializeScreens()
         }
 
         // Push the screens to QGuiApplication
-        foreach (QXcbScreen *screen, m_screens) {
+        for (QXcbScreen *screen : qAsConst(m_screens)) {
             qCDebug(lcQpaScreen) << "adding" << screen << "(Primary:" << screen->isPrimary() << ")";
             QXcbIntegration::instance()->screenAdded(screen, screen->isPrimary());
         }
@@ -1236,7 +1236,7 @@ void QXcbConnection::handleXcbEvent(xcb_generic_event_t *event)
 #ifndef QT_NO_CLIPBOARD
             m_clipboard->handleXFixesSelectionRequest(notify_event);
 #endif
-            foreach (QXcbVirtualDesktop *virtualDesktop, m_virtualDesktops)
+            for (QXcbVirtualDesktop *virtualDesktop : qAsConst(m_virtualDesktops))
                 virtualDesktop->handleXFixesSelectionNotify(notify_event);
 
             handled = true;
@@ -1245,7 +1245,7 @@ void QXcbConnection::handleXcbEvent(xcb_generic_event_t *event)
             handled = true;
         } else if (has_randr_extension && response_type == xrandr_first_event + XCB_RANDR_SCREEN_CHANGE_NOTIFY) {
             xcb_randr_screen_change_notify_event_t *change_event = (xcb_randr_screen_change_notify_event_t *)event;
-            foreach (QXcbScreen *s, m_screens) {
+            for (QXcbScreen *s : qAsConst(m_screens)) {
                 if (s->root() == change_event->root )
                     s->handleScreenChange(change_event);
             }
@@ -1736,7 +1736,7 @@ void QXcbConnection::processXcbEvents()
 
     // Indicate with a null event that the event the callbacks are waiting for
     // is not in the queue currently.
-    Q_FOREACH (PeekFunc f, m_peekFuncs)
+    for (PeekFunc f : qAsConst(m_peekFuncs))
         f(this, 0);
     m_peekFuncs.clear();
 

src/plugins/platforms/xcb/qxcbconnection_xi2.cpp

@@ -274,7 +274,7 @@ void QXcbConnection::xi2SetupDevices()
 
 void QXcbConnection::finalizeXInput2()
 {
-    foreach (XInput2TouchDeviceData *dev, m_touchDevices) {
+    for (XInput2TouchDeviceData *dev : qAsConst(m_touchDevices)) {
         if (dev->xiDeviceInfo)
             XIFreeDeviceInfo(dev->xiDeviceInfo);
         delete dev;
@@ -359,7 +359,7 @@ void QXcbConnection::xi2Select(xcb_window_t window)
         scrollBitMask = XI_MotionMask;
         scrollBitMask |= XI_ButtonReleaseMask;
         int i=0;
-        Q_FOREACH (const ScrollingDevice& scrollingDevice, m_scrollingDevices) {
+        for (const ScrollingDevice& scrollingDevice : qAsConst(m_scrollingDevices)) {
             if (tabletDevices.contains(scrollingDevice.deviceId))
                 continue; // All necessary events are already captured.
             xiEventMask[i].deviceid = scrollingDevice.deviceId;

src/plugins/platforms/xcb/qxcbcursor.cpp

@@ -343,7 +343,7 @@ QXcbCursor::~QXcbCursor()
         xcb_close_font(conn, cursorFont);
 
 #ifndef QT_NO_CURSOR
-    foreach (xcb_cursor_t cursor, m_cursorHash)
+    for (xcb_cursor_t cursor : qAsConst(m_cursorHash))
         xcb_free_cursor(conn, cursor);
 #endif
 }

src/plugins/platforms/xcb/qxcbkeyboard.cpp

@@ -1038,7 +1038,7 @@ QList<int> QXcbKeyboard::possibleKeys(const QKeyEvent *event) const
             // catch only more specific shortcuts, i.e. Ctrl+Shift+= also generates Ctrl++ and +,
             // but Ctrl++ is more specific than +, so we should skip the last one
             bool ambiguous = false;
-            foreach (int shortcut, result) {
+            for (int shortcut : qAsConst(result)) {
                 if (int(shortcut & ~Qt::KeyboardModifierMask) == qtKey && (shortcut & mods) == mods) {
                     ambiguous = true;
                     break;

src/plugins/platforms/xcb/qxcbscreen.cpp

@@ -158,7 +158,7 @@ void QXcbVirtualDesktop::updateWorkArea()
     QRect workArea = getWorkArea();
     if (m_workArea != workArea) {
         m_workArea = workArea;
-        foreach (QPlatformScreen *screen, m_screens)
+        for (QPlatformScreen *screen : qAsConst(m_screens))
             ((QXcbScreen *)screen)->updateAvailableGeometry();
     }
 }