Tidy nullptr usage

Move away from using 0 as pointer literal.

Done using clang-tidy. This is not complete as
run-clang-tidy can't handle all of qtbase in one go.

Change-Id: I1076a21f32aac0dab078af6f175f7508145eece0
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

24 files changed, 133 insertions, 133 deletions

diff --git a/src/plugins/platforms/xcb/gl_integrations/xcb_egl/qxcbeglcontext.h b/src/plugins/platforms/xcb/gl_integrations/xcb_egl/qxcbeglcontext.h
index c3ce8d8745..fda53f17a1 100644
--- a/src/plugins/platforms/xcb/gl_integrations/xcb_egl/qxcbeglcontext.h
+++ b/src/plugins/platforms/xcb/gl_integrations/xcb_egl/qxcbeglcontext.h
@@ -52,7 +52,7 @@ class QXcbEglContext : public QEGLPlatformContext
 public:
     QXcbEglContext(const QSurfaceFormat &glFormat, QPlatformOpenGLContext *share,
                            EGLDisplay display, const QVariant &nativeHandle)
-        : QEGLPlatformContext(glFormat, share, display, 0, nativeHandle)
+        : QEGLPlatformContext(glFormat, share, display, nullptr, nativeHandle)
     {
     }
 
diff --git a/src/plugins/platforms/xcb/gl_integrations/xcb_egl/qxcbeglwindow.cpp b/src/plugins/platforms/xcb/gl_integrations/xcb_egl/qxcbeglwindow.cpp
index 65beac227c..30e3381993 100644
--- a/src/plugins/platforms/xcb/gl_integrations/xcb_egl/qxcbeglwindow.cpp
+++ b/src/plugins/platforms/xcb/gl_integrations/xcb_egl/qxcbeglwindow.cpp
@@ -93,7 +93,7 @@ void QXcbEglWindow::create()
 {
     QXcbWindow::create();
 
-    m_surface = eglCreateWindowSurface(m_glIntegration->eglDisplay(), m_config, m_window, 0);
+    m_surface = eglCreateWindowSurface(m_glIntegration->eglDisplay(), m_config, m_window, nullptr);
 }
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
index 2b77062b16..57805d5571 100644
--- a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
+++ b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
@@ -223,13 +223,13 @@ QGLXContext::QGLXContext(QXcbScreen *screen, const QSurfaceFormat &format, QPlat
                          const QVariant &nativeHandle)
     : QPlatformOpenGLContext()
     , m_display(static_cast<Display *>(screen->connection()->xlib_display()))
-    , m_config(0)
-    , m_context(0)
-    , m_shareContext(0)
+    , m_config(nullptr)
+    , m_context(nullptr)
+    , m_shareContext(nullptr)
     , m_format(format)
     , m_isPBufferCurrent(false)
     , m_ownsContext(nativeHandle.isNull())
-    , m_getGraphicsResetStatus(0)
+    , m_getGraphicsResetStatus(nullptr)
     , m_lost(false)
 {
     if (nativeHandle.isNull())
@@ -254,14 +254,14 @@ void QGLXContext::init(QXcbScreen *screen, QPlatformOpenGLContext *share)
 
     GLXFBConfig config = qglx_findConfig(m_display, screen->screenNumber(), m_format);
     m_config = config;
-    XVisualInfo *visualInfo = 0;
+    XVisualInfo *visualInfo = nullptr;
     Window window = 0; // Temporary window used to query OpenGL context
 
     if (config) {
         const QByteArrayList glxExt = QByteArray(glXQueryExtensionsString(m_display, screen->screenNumber())).split(' ');
 
         // Resolve entry point for glXCreateContextAttribsARB
-        glXCreateContextAttribsARBProc glXCreateContextAttribsARB = 0;
+        glXCreateContextAttribsARBProc glXCreateContextAttribsARB = nullptr;
         if (glxExt.contains("GLX_ARB_create_context"))
             glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc) glXGetProcAddress((const GLubyte*)"glXCreateContextAttribsARB");
 
@@ -271,7 +271,7 @@ void QGLXContext::init(QXcbScreen *screen, QPlatformOpenGLContext *share)
 
         // Use glXCreateContextAttribsARB if available
         // Also, GL ES context creation requires GLX_EXT_create_context_es2_profile
-        if (glXCreateContextAttribsARB != 0
+        if (glXCreateContextAttribsARB != nullptr
                 && (m_format.renderableType() != QSurfaceFormat::OpenGLES || (supportsProfiles && glxExt.contains("GLX_EXT_create_context_es2_profile")))) {
             // Try to create an OpenGL context for each known OpenGL version in descending
             // order from the requested version.
@@ -358,9 +358,9 @@ void QGLXContext::init(QXcbScreen *screen, QPlatformOpenGLContext *share)
                     m_context = glXCreateContextAttribsARB(m_display, config, m_shareContext, true, contextAttributes.data());
                     if (!m_context && m_shareContext) {
                         // re-try without a shared glx context
-                        m_context = glXCreateContextAttribsARB(m_display, config, 0, true, contextAttributes.data());
+                        m_context = glXCreateContextAttribsARB(m_display, config, nullptr, true, contextAttributes.data());
                         if (m_context)
-                            m_shareContext = 0;
+                            m_shareContext = nullptr;
                     }
                 }
             }
@@ -375,9 +375,9 @@ void QGLXContext::init(QXcbScreen *screen, QPlatformOpenGLContext *share)
             m_context = glXCreateNewContext(m_display, config, GLX_RGBA_TYPE, m_shareContext, true);
             if (!m_context && m_shareContext) {
                 // re-try without a shared glx context
-                m_context = glXCreateNewContext(m_display, config, GLX_RGBA_TYPE, 0, true);
+                m_context = glXCreateNewContext(m_display, config, GLX_RGBA_TYPE, nullptr, true);
                 if (m_context)
-                    m_shareContext = 0;
+                    m_shareContext = nullptr;
             }
         }
 
@@ -399,7 +399,7 @@ void QGLXContext::init(QXcbScreen *screen, QPlatformOpenGLContext *share)
         m_context = glXCreateContext(m_display, visualInfo, m_shareContext, true);
         if (!m_context && m_shareContext) {
             // re-try without a shared glx context
-            m_shareContext = 0;
+            m_shareContext = nullptr;
             m_context = glXCreateContext(m_display, visualInfo, nullptr, true);
         }
 
@@ -444,7 +444,7 @@ void QGLXContext::init(QXcbScreen *screen, QPlatformOpenGLContext *share, const
     // Legacy contexts created using glXCreateContext are created using a visual
     // and the FBConfig cannot be queried. The only way to adapt these contexts
     // is to figure out the visual id.
-    XVisualInfo *vinfo = 0;
+    XVisualInfo *vinfo = nullptr;
     // If the VisualID is provided use it.
     VisualID vid = handle.visualId();
     if (!vid) {
@@ -464,13 +464,13 @@ void QGLXContext::init(QXcbScreen *screen, QPlatformOpenGLContext *share, const
         vinfo = XGetVisualInfo(dpy, VisualScreenMask | VisualIDMask, &v, &n);
         if (n < 1) {
             XFree(vinfo);
-            vinfo = 0;
+            vinfo = nullptr;
         }
     }
 
     // For contexts created with an FBConfig using the modern functions providing the
     // visual or window is not mandatory. Just query the config from the context.
-    GLXFBConfig config = 0;
+    GLXFBConfig config = nullptr;
     if (!vinfo) {
         int configId = 0;
         if (glXQueryContext(dpy, context, GLX_FBCONFIG_ID, &configId) != Success) {
@@ -595,8 +595,8 @@ bool QGLXContext::makeCurrent(QPlatformSurface *surface)
         if (interval >= 0 && interval != window->swapInterval() && screen) {
             typedef void (*qt_glXSwapIntervalEXT)(Display *, GLXDrawable, int);
             typedef void (*qt_glXSwapIntervalMESA)(unsigned int);
-            static qt_glXSwapIntervalEXT glXSwapIntervalEXT = 0;
-            static qt_glXSwapIntervalMESA glXSwapIntervalMESA = 0;
+            static qt_glXSwapIntervalEXT glXSwapIntervalEXT = nullptr;
+            static qt_glXSwapIntervalMESA glXSwapIntervalMESA = nullptr;
             static bool resolved = false;
             if (!resolved) {
                 resolved = true;
@@ -621,9 +621,9 @@ bool QGLXContext::makeCurrent(QPlatformSurface *surface)
 void QGLXContext::doneCurrent()
 {
     if (m_isPBufferCurrent)
-        glXMakeContextCurrent(m_display, 0, 0, 0);
+        glXMakeContextCurrent(m_display, 0, 0, nullptr);
     else
-        glXMakeCurrent(m_display, 0, 0);
+        glXMakeCurrent(m_display, 0, nullptr);
     m_isPBufferCurrent = false;
 }
 
@@ -658,12 +658,12 @@ QSurfaceFormat QGLXContext::format() const
 
 bool QGLXContext::isSharing() const
 {
-    return m_shareContext != 0;
+    return m_shareContext != nullptr;
 }
 
 bool QGLXContext::isValid() const
 {
-    return m_context != 0 && !m_lost;
+    return m_context != nullptr && !m_lost;
 }
 
 bool QGLXContext::m_queriedDummyContext = false;
@@ -675,7 +675,7 @@ bool QGLXContext::m_supportsThreading = true;
 // binary search.
 static const char *qglx_threadedgl_blacklist_renderer[] = {
     "Chromium",                             // QTBUG-32225 (initialization fails)
-    0
+    nullptr
 };
 
 static const char *qglx_threadedgl_blacklist_vendor[] = {
@@ -695,7 +695,7 @@ void QGLXContext::queryDummyContext()
         return;
 
     QOpenGLContext *oldContext = QOpenGLContext::currentContext();
-    QSurface *oldSurface = 0;
+    QSurface *oldSurface = nullptr;
     if (oldContext)
         oldSurface = oldContext->surface();
 
@@ -732,7 +732,7 @@ void QGLXContext::queryDummyContext()
 
     if (const char *renderer = (const char *) glGetString(GL_RENDERER)) {
         for (int i = 0; qglx_threadedgl_blacklist_renderer[i]; ++i) {
-            if (strstr(renderer, qglx_threadedgl_blacklist_renderer[i]) != 0) {
+            if (strstr(renderer, qglx_threadedgl_blacklist_renderer[i]) != nullptr) {
                 qCDebug(lcQpaGl).nospace() << "Multithreaded OpenGL disabled: "
                                              "blacklisted renderer \""
                                           << qglx_threadedgl_blacklist_renderer[i]
@@ -744,7 +744,7 @@ void QGLXContext::queryDummyContext()
     }
     if (const char *vendor = (const char *) glGetString(GL_VENDOR)) {
         for (int i = 0; qglx_threadedgl_blacklist_vendor[i]; ++i) {
-            if (strstr(vendor, qglx_threadedgl_blacklist_vendor[i]) != 0) {
+            if (strstr(vendor, qglx_threadedgl_blacklist_vendor[i]) != nullptr) {
                 qCDebug(lcQpaGl).nospace() << "Multithreaded OpenGL disabled: "
                                               "blacklisted vendor \""
                                            << qglx_threadedgl_blacklist_vendor[i]
@@ -759,7 +759,7 @@ void QGLXContext::queryDummyContext()
         // Blacklist Mesa drivers due to QTCREATORBUG-10875 (crash in creator),
         // QTBUG-34492 (flickering in fullscreen) and QTBUG-38221
         const char *mesaVersionStr = nullptr;
-        if (strstr(glxvendor, "Mesa Project") != 0) {
+        if (strstr(glxvendor, "Mesa Project") != nullptr) {
             mesaVersionStr = (const char *) glGetString(GL_VERSION);
             m_supportsThreading = false;
         }
diff --git a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp
index 34895caaa2..6814dbd844 100644
--- a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp
+++ b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp
@@ -133,7 +133,7 @@ bool QXcbGlxIntegration::handleXcbEvent(xcb_generic_event_t *event, uint respons
     Display *xdisplay = static_cast<Display *>(m_connection->xlib_display());
     XLockDisplay(xdisplay);
     bool locked = true;
-    Bool (*proc)(Display*, XEvent*, xEvent*) = XESetWireToEvent(xdisplay, responseType, 0);
+    Bool (*proc)(Display*, XEvent*, xEvent*) = XESetWireToEvent(xdisplay, responseType, nullptr);
     if (proc) {
         XESetWireToEvent(xdisplay, responseType, proc);
         XEvent dummy;
@@ -212,7 +212,7 @@ QPlatformOffscreenSurface *QXcbGlxIntegration::createPlatformOffscreenSurface(QO
     if (glxPbufferUsable)
         return new QGLXPbuffer(surface);
     else
-        return 0; // trigger fallback to hidden QWindow
+        return nullptr; // trigger fallback to hidden QWindow
 
 }
 
diff --git a/src/plugins/platforms/xcb/qxcbatom.cpp b/src/plugins/platforms/xcb/qxcbatom.cpp
index ecb73cb90b..79b5ba06e6 100644
--- a/src/plugins/platforms/xcb/qxcbatom.cpp
+++ b/src/plugins/platforms/xcb/qxcbatom.cpp
@@ -265,7 +265,7 @@ void QXcbAtom::initializeAllAtoms(xcb_connection_t *connection) {
         cookies[i] = xcb_intern_atom(connection, false, strlen(names[i]), names[i]);
 
     for (i = 0; i < QXcbAtom::NAtoms; ++i) {
-        xcb_intern_atom_reply_t *reply = xcb_intern_atom_reply(connection, cookies[i], 0);
+        xcb_intern_atom_reply_t *reply = xcb_intern_atom_reply(connection, cookies[i], nullptr);
         m_allAtoms[i] = reply->atom;
         free(reply);
     }
diff --git a/src/plugins/platforms/xcb/qxcbbackingstore.cpp b/src/plugins/platforms/xcb/qxcbbackingstore.cpp
index 741317d766..8f55bc2e96 100644
--- a/src/plugins/platforms/xcb/qxcbbackingstore.cpp
+++ b/src/plugins/platforms/xcb/qxcbbackingstore.cpp
@@ -229,7 +229,7 @@ void QXcbBackingStoreImage::resize(const QSize &size)
                                    m_xcb_format->bits_per_pixel,
                                    0, byteOrder,
                                    XCB_IMAGE_ORDER_MSB_FIRST,
-                                   0, ~0, 0);
+                                   nullptr, ~0, nullptr);
 
     const size_t segmentSize = imageDataSize(m_xcb_image);
 
@@ -412,13 +412,13 @@ bool QXcbBackingStoreImage::createSystemVShmSegment(xcb_connection_t *c, size_t
         return false;
     }
 
-    void *addr = shmat(id, 0, 0);
+    void *addr = shmat(id, nullptr, 0);
     if (addr == (void *)-1) {
         qCWarning(lcQpaXcb, "shmat() failed (%d: %s) for id %d", errno, strerror(errno), id);
         return false;
     }
 
-    if (shmctl(id, IPC_RMID, 0) == -1)
+    if (shmctl(id, IPC_RMID, nullptr) == -1)
         qCWarning(lcQpaXcb, "Error while marking the shared memory segment to be destroyed");
 
     const auto seg = xcb_generate_id(c);
@@ -780,7 +780,7 @@ QXcbBackingStore::~QXcbBackingStore()
 QPaintDevice *QXcbBackingStore::paintDevice()
 {
     if (!m_image)
-        return 0;
+        return nullptr;
     return m_rgbImage.isNull() ? m_image->image() : &m_rgbImage;
 }
 
@@ -1036,7 +1036,7 @@ void QXcbSystemTrayBackingStore::recreateImage(QXcbWindow *win, const QSize &siz
     xcb_create_pixmap(xcb_connection(), 32, m_xrenderPixmap, screen->root(), size.width(), size.height());
 
     m_xrenderPicture = xcb_generate_id(xcb_connection());
-    xcb_render_create_picture(xcb_connection(), m_xrenderPicture, m_xrenderPixmap, m_xrenderPictFormat, 0, 0);
+    xcb_render_create_picture(xcb_connection(), m_xrenderPicture, m_xrenderPixmap, m_xrenderPictFormat, 0, nullptr);
 
     // XRender expects premultiplied alpha
     if (m_image)
@@ -1077,7 +1077,7 @@ void QXcbSystemTrayBackingStore::initXRenderMode()
 
     m_windowPicture = xcb_generate_id(conn);
     xcb_void_cookie_t cookie =
-            xcb_render_create_picture_checked(conn, m_windowPicture, platformWindow->xcb_window(), vfmt->format, 0, 0);
+            xcb_render_create_picture_checked(conn, m_windowPicture, platformWindow->xcb_window(), vfmt->format, 0, nullptr);
     xcb_generic_error_t *error = xcb_request_check(conn, cookie);
     if (error) {
         qWarning("QXcbSystemTrayBackingStore: Failed to create Picture with format %x for window %x, error code %d",
diff --git a/src/plugins/platforms/xcb/qxcbclipboard.cpp b/src/plugins/platforms/xcb/qxcbclipboard.cpp
index 2cb6720d40..c2d9d060fb 100644
--- a/src/plugins/platforms/xcb/qxcbclipboard.cpp
+++ b/src/plugins/platforms/xcb/qxcbclipboard.cpp
@@ -226,8 +226,8 @@ QXcbClipboard::QXcbClipboard(QXcbConnection *c)
 {
     Q_ASSERT(QClipboard::Clipboard == 0);
     Q_ASSERT(QClipboard::Selection == 1);
-    m_clientClipboard[QClipboard::Clipboard] = 0;
-    m_clientClipboard[QClipboard::Selection] = 0;
+    m_clientClipboard[QClipboard::Clipboard] = nullptr;
+    m_clientClipboard[QClipboard::Selection] = nullptr;
     m_timestamp[QClipboard::Clipboard] = XCB_CURRENT_TIME;
     m_timestamp[QClipboard::Selection] = XCB_CURRENT_TIME;
     m_owner = connection()->getQtSelectionOwner();
@@ -316,7 +316,7 @@ QClipboard::Mode QXcbClipboard::modeForAtom(xcb_atom_t a) const
 QMimeData * QXcbClipboard::mimeData(QClipboard::Mode mode)
 {
     if (mode > QClipboard::Selection)
-        return 0;
+        return nullptr;
 
     xcb_window_t clipboardOwner = getSelectionOwner(atomForMode(mode));
     if (clipboardOwner == owner()) {
@@ -334,7 +334,7 @@ void QXcbClipboard::setMimeData(QMimeData *data, QClipboard::Mode mode)
     if (mode > QClipboard::Selection)
         return;
 
-    QXcbClipboardMime *xClipboard = 0;
+    QXcbClipboardMime *xClipboard = nullptr;
     // verify if there is data to be cleared on global X Clipboard.
     if (!data) {
         xClipboard = qobject_cast<QXcbClipboardMime *>(mimeData(mode));
@@ -353,7 +353,7 @@ void QXcbClipboard::setMimeData(QMimeData *data, QClipboard::Mode mode)
     if (m_clientClipboard[mode]) {
         if (m_clientClipboard[QClipboard::Clipboard] != m_clientClipboard[QClipboard::Selection])
             delete m_clientClipboard[mode];
-        m_clientClipboard[mode] = 0;
+        m_clientClipboard[mode] = nullptr;
         m_timestamp[mode] = XCB_CURRENT_TIME;
     }
 
@@ -416,7 +416,7 @@ xcb_window_t QXcbClipboard::requestor() const
                           XCB_WINDOW_CLASS_INPUT_OUTPUT,         // window class
                           platformScreen->screen()->root_visual, // visual
                           0,                                     // value mask
-                          0);                                    // value list
+                          nullptr);                                    // value list
 
         QXcbWindow::setWindowTitle(connection(), window,
                                    QStringLiteral("Qt Clipboard Requestor Window"));
@@ -529,7 +529,7 @@ void QXcbClipboard::handleSelectionClearRequest(xcb_selection_clear_event_t *eve
     if (newOwner != XCB_NONE) {
         if (m_clientClipboard[QClipboard::Clipboard] != m_clientClipboard[QClipboard::Selection])
             delete m_clientClipboard[mode];
-        m_clientClipboard[mode] = 0;
+        m_clientClipboard[mode] = nullptr;
         m_timestamp[mode] = XCB_CURRENT_TIME;
     }
 }
@@ -576,7 +576,7 @@ void QXcbClipboard::handleSelectionRequest(xcb_selection_request_event_t *req)
     xcb_atom_t multipleAtom = atom(QXcbAtom::MULTIPLE);
     xcb_atom_t timestampAtom = atom(QXcbAtom::TIMESTAMP);
 
-    struct AtomPair { xcb_atom_t target; xcb_atom_t property; } *multi = 0;
+    struct AtomPair { xcb_atom_t target; xcb_atom_t property; } *multi = nullptr;
     xcb_atom_t multi_type = XCB_NONE;
     int multi_format = 0;
     int nmulti = 0;
@@ -587,7 +587,7 @@ void QXcbClipboard::handleSelectionRequest(xcb_selection_request_event_t *req)
         QByteArray multi_data;
         if (req->property == XCB_NONE
             || !clipboardReadProperty(req->requestor, req->property, false, &multi_data,
-                                           0, &multi_type, &multi_format)
+                                           nullptr, &multi_type, &multi_format)
             || multi_format != 32) {
             // MULTIPLE property not formatted correctly
             xcb_send_event(xcb_connection(), false, req->requestor, XCB_EVENT_MASK_NO_EVENT, (const char *)&event);
@@ -842,7 +842,7 @@ QByteArray QXcbClipboard::clipboardReadIncrementalProperty(xcb_window_t win, xcb
             continue;
         prev_time = event->time;
 
-        if (clipboardReadProperty(win, property, true, &tmp_buf, &length, 0, 0)) {
+        if (clipboardReadProperty(win, property, true, &tmp_buf, &length, nullptr, nullptr)) {
             if (length == 0) {                // no more data, we're done
                 if (nullterm) {
                     buf.resize(offset+1);
@@ -900,7 +900,7 @@ QByteArray QXcbClipboard::getSelection(xcb_atom_t selection, xcb_atom_t target,
         return buf;
 
     xcb_atom_t type;
-    if (clipboardReadProperty(win, property, true, &buf, 0, &type, 0)) {
+    if (clipboardReadProperty(win, property, true, &buf, nullptr, &type, nullptr)) {
         if (type == atom(QXcbAtom::INCR)) {
             int nbytes = buf.size() >= 4 ? *((int*)buf.data()) : 0;
             buf = clipboardReadIncrementalProperty(win, property, nbytes, false);
diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index cbc930387f..435c4aee93 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -184,7 +184,7 @@ QXcbWindow *QXcbConnection::platformWindowFromId(xcb_window_t id)
     QXcbWindowEventListener *listener = m_mapper.value(id, 0);
     if (listener)
         return listener->toWindow();
-    return 0;
+    return nullptr;
 }
 
 #define HANDLE_PLATFORM_WINDOW_EVENT(event_t, windowMember, handler) \
@@ -803,7 +803,7 @@ xcb_window_t QXcbConnection::getQtSelectionOwner()
                           XCB_WINDOW_CLASS_INPUT_OUTPUT,      // window class
                           xcbScreen->root_visual,             // visual
                           0,                                  // value mask
-                          0);                                 // value list
+                          nullptr);                                 // value list
 
         QXcbWindow::setWindowTitle(connection(), m_qtSelectionOwner,
                                    QLatin1String("Qt Selection Owner for ") + QCoreApplication::applicationName());
@@ -830,7 +830,7 @@ xcb_window_t QXcbConnection::clientLeader()
                           0,
                           XCB_WINDOW_CLASS_INPUT_OUTPUT,
                           screen->screen()->root_visual,
-                          0, 0);
+                          0, nullptr);
 
 
         QXcbWindow::setWindowTitle(connection(), m_clientLeader,
@@ -1031,7 +1031,7 @@ void QXcbConnection::sync()
 {
     // from xcb_aux_sync
     xcb_get_input_focus_cookie_t cookie = xcb_get_input_focus(xcb_connection());
-    free(xcb_get_input_focus_reply(xcb_connection(), cookie, 0));
+    free(xcb_get_input_focus_reply(xcb_connection(), cookie, nullptr));
 }
 
 QXcbSystemTrayTracker *QXcbConnection::systemTrayTracker() const
@@ -1049,14 +1049,14 @@ QXcbSystemTrayTracker *QXcbConnection::systemTrayTracker() const
 Qt::MouseButtons QXcbConnection::queryMouseButtons() const
 {
     int stateMask = 0;
-    QXcbCursor::queryPointer(connection(), 0, 0, &stateMask);
+    QXcbCursor::queryPointer(connection(), nullptr, nullptr, &stateMask);
     return translateMouseButtons(stateMask);
 }
 
 Qt::KeyboardModifiers QXcbConnection::queryKeyboardModifiers() const
 {
     int stateMask = 0;
-    QXcbCursor::queryPointer(connection(), 0, 0, &stateMask);
+    QXcbCursor::queryPointer(connection(), nullptr, nullptr, &stateMask);
     return keyboard()->translateModifiers(stateMask);
 }
 
@@ -1114,7 +1114,7 @@ void QXcbSyncWindowRequest::invalidate()
 {
     if (m_window) {
         m_window->clearSyncWindowRequest();
-        m_window = 0;
+        m_window = nullptr;
     }
 }
 
@@ -1134,7 +1134,7 @@ void QXcbConnectionGrabber::release()
 {
     if (m_connection) {
         m_connection->ungrabServer();
-        m_connection = 0;
+        m_connection = nullptr;
     }
 }
 
diff --git a/src/plugins/platforms/xcb/qxcbconnection.h b/src/plugins/platforms/xcb/qxcbconnection.h
index 62c5e5d79e..2d89b971dc 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.h
+++ b/src/plugins/platforms/xcb/qxcbconnection.h
@@ -127,7 +127,7 @@ class Q_XCB_EXPORT QXcbConnection : public QXcbBasicConnection
 {
     Q_OBJECT
 public:
-    QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGrabServer, xcb_visualid_t defaultVisualId, const char *displayName = 0);
+    QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGrabServer, xcb_visualid_t defaultVisualId, const char *displayName = nullptr);
     ~QXcbConnection();
 
     QXcbConnection *connection() const { return const_cast<QXcbConnection *>(this); }
diff --git a/src/plugins/platforms/xcb/qxcbconnection_basic.cpp b/src/plugins/platforms/xcb/qxcbconnection_basic.cpp
index 1ba4b4a1b9..18dee89adb 100644
--- a/src/plugins/platforms/xcb/qxcbconnection_basic.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection_basic.cpp
@@ -93,7 +93,7 @@ static int nullErrorHandler(Display *dpy, XErrorEvent *err)
 static int ioErrorHandler(Display *dpy)
 {
     xcb_connection_t *conn = XGetXCBConnection(dpy);
-    if (conn != NULL) {
+    if (conn != nullptr) {
         /* Print a message with a textual description of the error */
         int code = xcb_connection_has_error(conn);
         const char *str = "Unknown error";
@@ -134,7 +134,7 @@ QXcbBasicConnection::QXcbBasicConnection(const char *displayName)
 
     xcb_extension_t *extensions[] = {
         &xcb_shm_id, &xcb_xfixes_id, &xcb_randr_id, &xcb_shape_id, &xcb_sync_id,
-        &xcb_render_id, &xcb_xkb_id, &xcb_input_id, 0
+        &xcb_render_id, &xcb_xkb_id, &xcb_input_id, nullptr
     };
 
     for (xcb_extension_t **ext_it = extensions; *ext_it; ++ext_it)
diff --git a/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp b/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
index fdf59c5ef4..bd62460b96 100644
--- a/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
@@ -166,7 +166,7 @@ void QXcbConnection::xi2SetupDevice(void *info, bool removeExisting)
         }
         case XCB_INPUT_DEVICE_CLASS_TYPE_BUTTON: {
             auto *bci = reinterpret_cast<xcb_input_button_class_t *>(classinfo);
-            xcb_atom_t *labels = 0;
+            xcb_atom_t *labels = nullptr;
             if (bci->num_buttons >= 5) {
                 labels = xcb_input_button_class_labels(bci);
                 xcb_atom_t label4 = labels[3];
@@ -527,7 +527,7 @@ void QXcbConnection::xi2HandleEvent(xcb_ge_event_t *event)
     int sourceDeviceId = xiEvent->deviceid; // may be the master id
     qt_xcb_input_device_event_t *xiDeviceEvent = nullptr;
     xcb_input_enter_event_t *xiEnterEvent = nullptr;
-    QXcbWindowEventListener *eventListener = 0;
+    QXcbWindowEventListener *eventListener = nullptr;
 
     switch (xiEvent->event_type) {
     case XCB_INPUT_BUTTON_PRESS:
diff --git a/src/plugins/platforms/xcb/qxcbcursor.cpp b/src/plugins/platforms/xcb/qxcbcursor.cpp
index fbadab4d50..639e4f039c 100644
--- a/src/plugins/platforms/xcb/qxcbcursor.cpp
+++ b/src/plugins/platforms/xcb/qxcbcursor.cpp
@@ -67,10 +67,10 @@ enum {
 };
 #undef CursorShape
 
-static PtrXcursorLibraryLoadCursor ptrXcursorLibraryLoadCursor = 0;
-static PtrXcursorLibraryGetTheme ptrXcursorLibraryGetTheme = 0;
-static PtrXcursorLibrarySetTheme ptrXcursorLibrarySetTheme = 0;
-static PtrXcursorLibraryGetDefaultSize ptrXcursorLibraryGetDefaultSize = 0;
+static PtrXcursorLibraryLoadCursor ptrXcursorLibraryLoadCursor = nullptr;
+static PtrXcursorLibraryGetTheme ptrXcursorLibraryGetTheme = nullptr;
+static PtrXcursorLibrarySetTheme ptrXcursorLibrarySetTheme = nullptr;
+static PtrXcursorLibraryGetDefaultSize ptrXcursorLibraryGetDefaultSize = nullptr;
 #endif
 
 static xcb_font_t cursorFont = 0;
@@ -118,7 +118,7 @@ static const uint8_t mcur_fdiag_bits[] = {
 static const uint8_t *cursor_bits16[] = {
     cur_ver_bits, mcur_ver_bits, cur_hor_bits, mcur_hor_bits,
     cur_bdiag_bits, mcur_bdiag_bits, cur_fdiag_bits, mcur_fdiag_bits,
-    0, 0, cur_blank_bits, cur_blank_bits };
+    nullptr, nullptr, cur_blank_bits, cur_blank_bits };
 
 static const uint8_t vsplit_bits[] = {
     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
@@ -219,7 +219,7 @@ static const uint8_t busym_bits[] = {
 
 static const uint8_t * const cursor_bits32[] = {
     vsplit_bits, vsplitm_bits, hsplit_bits, hsplitm_bits,
-    0, 0, 0, 0, whatsthis_bits, whatsthism_bits, busy_bits, busym_bits
+    nullptr, nullptr, nullptr, nullptr, whatsthis_bits, whatsthism_bits, busy_bits, busym_bits
 };
 
 static const uint8_t forbidden_bits[] = {
@@ -452,19 +452,19 @@ xcb_cursor_t QXcbCursor::createNonStandardCursor(int cshape)
 
     if (cshape == Qt::BlankCursor) {
         xcb_pixmap_t cp = xcb_create_pixmap_from_bitmap_data(conn, m_screen->root(), cur_blank_bits, 16, 16,
-                                                             1, 0, 0, 0);
+                                                             1, 0, 0, nullptr);
         xcb_pixmap_t mp = xcb_create_pixmap_from_bitmap_data(conn, m_screen->root(), cur_blank_bits, 16, 16,
-                                                             1, 0, 0, 0);
+                                                             1, 0, 0, nullptr);
         cursor = xcb_generate_id(conn);
         xcb_create_cursor(conn, cursor, cp, mp, 0, 0, 0, 0xFFFF, 0xFFFF, 0xFFFF, 8, 8);
     } else if (cshape >= Qt::SizeVerCursor && cshape < Qt::SizeAllCursor) {
         int i = (cshape - Qt::SizeVerCursor) * 2;
         xcb_pixmap_t pm = xcb_create_pixmap_from_bitmap_data(conn, m_screen->root(),
                                                              const_cast<uint8_t*>(cursor_bits16[i]),
-                                                             16, 16, 1, 0, 0, 0);
+                                                             16, 16, 1, 0, 0, nullptr);
         xcb_pixmap_t pmm = xcb_create_pixmap_from_bitmap_data(conn, m_screen->root(),
                                                               const_cast<uint8_t*>(cursor_bits16[i + 1]),
-                                                              16, 16, 1, 0, 0, 0);
+                                                              16, 16, 1, 0, 0, nullptr);
         cursor = xcb_generate_id(conn);
         xcb_create_cursor(conn, cursor, pm, pmm, 0, 0, 0, 0xFFFF, 0xFFFF, 0xFFFF, 8, 8);
     } else if ((cshape >= Qt::SplitVCursor && cshape <= Qt::SplitHCursor)
@@ -472,10 +472,10 @@ xcb_cursor_t QXcbCursor::createNonStandardCursor(int cshape)
         int i = (cshape - Qt::SplitVCursor) * 2;
         xcb_pixmap_t pm = xcb_create_pixmap_from_bitmap_data(conn, m_screen->root(),
                                                              const_cast<uint8_t*>(cursor_bits32[i]),
-                                                             32, 32, 1, 0, 0, 0);
+                                                             32, 32, 1, 0, 0, nullptr);
         xcb_pixmap_t pmm = xcb_create_pixmap_from_bitmap_data(conn, m_screen->root(),
                                                               const_cast<uint8_t*>(cursor_bits32[i + 1]),
-                                                              32, 32, 1, 0, 0, 0);
+                                                              32, 32, 1, 0, 0, nullptr);
         int hs = (cshape == Qt::PointingHandCursor || cshape == Qt::WhatsThisCursor
                   || cshape == Qt::BusyCursor) ? 0 : 16;
         cursor = xcb_generate_id(conn);
@@ -484,20 +484,20 @@ xcb_cursor_t QXcbCursor::createNonStandardCursor(int cshape)
         int i = (cshape - Qt::ForbiddenCursor) * 2;
         xcb_pixmap_t pm = xcb_create_pixmap_from_bitmap_data(conn, m_screen->root(),
                                                              const_cast<uint8_t*>(cursor_bits20[i]),
-                                                             20, 20, 1, 0, 0, 0);
+                                                             20, 20, 1, 0, 0, nullptr);
         xcb_pixmap_t pmm = xcb_create_pixmap_from_bitmap_data(conn, m_screen->root(),
                                                               const_cast<uint8_t*>(cursor_bits20[i + 1]),
-                                                              20, 20, 1, 0, 0, 0);
+                                                              20, 20, 1, 0, 0, nullptr);
         cursor = xcb_generate_id(conn);
         xcb_create_cursor(conn, cursor, pm, pmm, 0, 0, 0, 0xFFFF, 0xFFFF, 0xFFFF, 10, 10);
     } else if (cshape == Qt::OpenHandCursor || cshape == Qt::ClosedHandCursor) {
         bool open = cshape == Qt::OpenHandCursor;
         xcb_pixmap_t pm = xcb_create_pixmap_from_bitmap_data(conn, m_screen->root(),
                                                              const_cast<uint8_t*>(open ? openhand_bits : closedhand_bits),
-                                                             16, 16, 1, 0, 0, 0);
+                                                             16, 16, 1, 0, 0, nullptr);
         xcb_pixmap_t pmm = xcb_create_pixmap_from_bitmap_data(conn, m_screen->root(),
                                                              const_cast<uint8_t*>(open ? openhandm_bits : closedhandm_bits),
-                                                             16, 16, 1, 0, 0, 0);
+                                                             16, 16, 1, 0, 0, nullptr);
         cursor = xcb_generate_id(conn);
         xcb_create_cursor(conn, cursor, pm, pmm, 0, 0, 0, 0xFFFF, 0xFFFF, 0xFFFF, 8, 8);
     } else if (cshape == Qt::DragCopyCursor || cshape == Qt::DragMoveCursor
@@ -660,14 +660,14 @@ void QXcbCursor::queryPointer(QXcbConnection *c, QXcbVirtualDesktop **virtualDes
 QPoint QXcbCursor::pos() const
 {
     QPoint p;
-    queryPointer(connection(), 0, &p);
+    queryPointer(connection(), nullptr, &p);
     return p;
 }
 
 void QXcbCursor::setPos(const QPoint &pos)
 {
     QXcbVirtualDesktop *virtualDesktop = nullptr;
-    queryPointer(connection(), &virtualDesktop, 0);
+    queryPointer(connection(), &virtualDesktop, nullptr);
     xcb_warp_pointer(xcb_connection(), XCB_NONE, virtualDesktop->root(), 0, 0, 0, 0, pos.x(), pos.y());
     xcb_flush(xcb_connection());
 }
diff --git a/src/plugins/platforms/xcb/qxcbdrag.cpp b/src/plugins/platforms/xcb/qxcbdrag.cpp
index eb5b8f808e..47d58fa880 100644
--- a/src/plugins/platforms/xcb/qxcbdrag.cpp
+++ b/src/plugins/platforms/xcb/qxcbdrag.cpp
@@ -148,7 +148,7 @@ void QXcbDrag::init()
     source_time = XCB_CURRENT_TIME;
     target_time = XCB_CURRENT_TIME;
 
-    QXcbCursor::queryPointer(connection(), &current_virtual_desktop, 0);
+    QXcbCursor::queryPointer(connection(), &current_virtual_desktop, nullptr);
     drag_types.clear();
 
     //current_embedding_widget = 0;
@@ -384,13 +384,13 @@ void QXcbDrag::move(const QPoint &globalPos, Qt::MouseButtons b, Qt::KeyboardMod
     if (!findXdndAwareTarget(globalPos, &target))
         return;
 
-    QXcbWindow *w = 0;
+    QXcbWindow *w = nullptr;
     if (target) {
         w = connection()->platformWindowFromId(target);
         if (w && (w->window()->type() == Qt::Desktop) /*&& !w->acceptDrops()*/)
-            w = 0;
+            w = nullptr;
     } else {
-        w = 0;
+        w = nullptr;
         target = current_virtual_desktop->root();
     }
 
@@ -522,7 +522,7 @@ void QXcbDrag::drop(const QPoint &globalPos, Qt::MouseButtons b, Qt::KeyboardMod
     QXcbWindow *w = connection()->platformWindowFromId(current_proxy_target);
 
     if (w && w->window()->type() == Qt::Desktop) // && !w->acceptDrops()
-        w = 0;
+        w = nullptr;
 
     Transaction t = {
         connection()->time(),
@@ -716,7 +716,7 @@ void QXcbDrag::handle_xdnd_position(QPlatformWindow *w, const xcb_client_message
         target_time = e->data.data32[3];
     }
 
-    QMimeData *dropData = 0;
+    QMimeData *dropData = nullptr;
     Qt::DropActions supported_actions = Qt::IgnoreAction;
     if (currentDrag()) {
         dropData = currentDrag()->mimeData();
@@ -911,7 +911,7 @@ void QXcbDrag::send_leave()
     QXcbWindow *w = connection()->platformWindowFromId(current_proxy_target);
 
     if (w && (w->window()->type() == Qt::Desktop) /*&& !w->acceptDrops()*/)
-        w = 0;
+        w = nullptr;
 
     qCDebug(lcQpaXDnd) << "sending XdndLeave to target:" << current_target;
 
@@ -945,7 +945,7 @@ void QXcbDrag::handleDrop(QPlatformWindow *, const xcb_client_message_event_t *e
         target_time = l[2];
 
     Qt::DropActions supported_drop_actions;
-    QMimeData *dropData = 0;
+    QMimeData *dropData = nullptr;
     if (currentDrag()) {
         dropData = currentDrag()->mimeData();
         supported_drop_actions = Qt::DropActions(l[4]);
@@ -1152,7 +1152,7 @@ void QXcbDrag::handleSelectionRequest(const xcb_selection_request_event_t *event
         }
     }
 
-    QDrag *transactionDrag = 0;
+    QDrag *transactionDrag = nullptr;
     if (at >= 0) {
         transactionDrag = transactions.at(at).drag;
     } else if (at == -2) {
@@ -1222,7 +1222,7 @@ bool QXcbDrag::dndEnable(QXcbWindow *w, bool on)
         if (w->window()->type() == Qt::Desktop) {
             xcb_delete_property(xcb_connection(), w->xcb_window(), atom(QXcbAtom::XdndProxy));
             delete desktop_proxy;
-            desktop_proxy = 0;
+            desktop_proxy = nullptr;
         } else {
             qCDebug(lcQpaXDnd) << "not deleting XDndAware";
         }
diff --git a/src/plugins/platforms/xcb/qxcbimage.cpp b/src/plugins/platforms/xcb/qxcbimage.cpp
index 8f33e6ed31..b0e610dd51 100644
--- a/src/plugins/platforms/xcb/qxcbimage.cpp
+++ b/src/plugins/platforms/xcb/qxcbimage.cpp
@@ -221,7 +221,7 @@ xcb_pixmap_t qt_xcb_XPixmapFromBitmap(QXcbScreen *screen, const QImage &image)
     for (int i = 0; i < height; i++)
         memcpy(buf + (destLineSize * i), map + (bytesPerLine * i), destLineSize);
     xcb_pixmap_t pm = xcb_create_pixmap_from_bitmap_data(conn, screen->root(), buf,
-                                                         width, height, 1, 0, 0, 0);
+                                                         width, height, 1, 0, 0, nullptr);
     delete[] buf;
     return pm;
 }
@@ -249,7 +249,7 @@ xcb_cursor_t qt_xcb_createCursorXRender(QXcbScreen *screen, const QImage &image,
                                        32, 32, 32, 32,
                                        QSysInfo::ByteOrder == QSysInfo::BigEndian ? XCB_IMAGE_ORDER_MSB_FIRST : XCB_IMAGE_ORDER_LSB_FIRST,
                                        XCB_IMAGE_ORDER_MSB_FIRST,
-                                       0, 0, 0);
+                                       nullptr, 0, nullptr);
     if (!xi) {
         qWarning("qt_xcb_createCursorXRender: xcb_image_create failed");
         return XCB_NONE;
@@ -266,10 +266,10 @@ xcb_cursor_t qt_xcb_createCursorXRender(QXcbScreen *screen, const QImage &image,
     xcb_create_pixmap(conn, 32, pix, screen->root(), w, h);
 
     xcb_render_picture_t pic = xcb_generate_id(conn);
-    xcb_render_create_picture(conn, pic, pix, fmt->id, 0, 0);
+    xcb_render_create_picture(conn, pic, pix, fmt->id, 0, nullptr);
 
     xcb_gcontext_t gc = xcb_generate_id(conn);
-    xcb_create_gc(conn, gc, pix, 0, 0);
+    xcb_create_gc(conn, gc, pix, 0, nullptr);
     xcb_image_put(conn, pix, gc, xi, 0, 0, 0);
     xcb_free_gc(conn, gc);
 
diff --git a/src/plugins/platforms/xcb/qxcbintegration.cpp b/src/plugins/platforms/xcb/qxcbintegration.cpp
index efda6b67ce..3fd989e1f9 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.cpp
+++ b/src/plugins/platforms/xcb/qxcbintegration.cpp
@@ -130,7 +130,7 @@ QXcbIntegration *QXcbIntegration::m_instance = nullptr;
 
 QXcbIntegration::QXcbIntegration(const QStringList &parameters, int &argc, char **argv)
     : m_services(new QGenericUnixServices)
-    , m_instanceName(0)
+    , m_instanceName(nullptr)
     , m_canGrab(true)
     , m_defaultVisualId(UINT_MAX)
 {
@@ -146,7 +146,7 @@ QXcbIntegration::QXcbIntegration(const QStringList &parameters, int &argc, char
     m_nativeInterface.reset(new QXcbNativeInterface);
 
     // Parse arguments
-    const char *displayName = 0;
+    const char *displayName = nullptr;
     bool noGrabArg = false;
     bool doGrabArg = false;
     if (argc) {
diff --git a/src/plugins/platforms/xcb/qxcbkeyboard.cpp b/src/plugins/platforms/xcb/qxcbkeyboard.cpp
index 3caee3f409..e8286381a2 100644
--- a/src/plugins/platforms/xcb/qxcbkeyboard.cpp
+++ b/src/plugins/platforms/xcb/qxcbkeyboard.cpp
@@ -579,7 +579,7 @@ void QXcbKeyboard::selectEvents()
                 required_events,
                 required_map_parts,
                 required_map_parts,
-                0);
+                nullptr);
 
     xcb_generic_error_t *error = xcb_request_check(xcb_connection(), select);
     if (error) {
@@ -620,7 +620,7 @@ void QXcbKeyboard::updateVModMapping()
     vmod_mask = name_reply->virtualMods;
     // find the virtual modifiers for which names are defined.
     for (bit = 1; vmod_mask; bit <<= 1) {
-        vmod_name = 0;
+        vmod_name = nullptr;
 
         if (!(vmod_mask & bit))
             continue;
diff --git a/src/plugins/platforms/xcb/qxcbnativeinterface.cpp b/src/plugins/platforms/xcb/qxcbnativeinterface.cpp
index 81b889a80f..30fa6864ac 100644
--- a/src/plugins/platforms/xcb/qxcbnativeinterface.cpp
+++ b/src/plugins/platforms/xcb/qxcbnativeinterface.cpp
@@ -268,7 +268,7 @@ QPlatformNativeInterface::NativeResourceForIntegrationFunction QXcbNativeInterfa
     if (lowerCaseResource == "peekeventqueue")
         return NativeResourceForIntegrationFunction(reinterpret_cast<void *>(peekEventQueue));
 
-    return 0;
+    return nullptr;
 }
 
 QPlatformNativeInterface::NativeResourceForContextFunction QXcbNativeInterface::nativeResourceFunctionForContext(const QByteArray &resource)
@@ -291,7 +291,7 @@ QPlatformNativeInterface::NativeResourceForScreenFunction QXcbNativeInterface::n
         return NativeResourceForScreenFunction(reinterpret_cast<void *>(setAppTime));
     else if (lowerCaseResource == "setappusertime")
         return NativeResourceForScreenFunction(reinterpret_cast<void *>(setAppUserTime));
-    return 0;
+    return nullptr;
 }
 
 QPlatformNativeInterface::NativeResourceForWindowFunction QXcbNativeInterface::nativeResourceFunctionForWindow(const QByteArray &resource)
@@ -365,7 +365,7 @@ void *QXcbNativeInterface::startupId()
     QXcbConnection *defaultConnection = integration->defaultConnection();
     if (defaultConnection)
         return reinterpret_cast<void *>(const_cast<char *>(defaultConnection->startupId().constData()));
-    return 0;
+    return nullptr;
 }
 
 void *QXcbNativeInterface::x11Screen()
@@ -374,7 +374,7 @@ void *QXcbNativeInterface::x11Screen()
     QXcbConnection *defaultConnection = integration->defaultConnection();
     if (defaultConnection)
         return reinterpret_cast<void *>(defaultConnection->primaryScreenNumber());
-    return 0;
+    return nullptr;
 }
 
 void *QXcbNativeInterface::rootWindow()
@@ -383,7 +383,7 @@ void *QXcbNativeInterface::rootWindow()
     QXcbConnection *defaultConnection = integration->defaultConnection();
     if (defaultConnection)
         return reinterpret_cast<void *>(defaultConnection->rootWindow());
-    return 0;
+    return nullptr;
 }
 
 void *QXcbNativeInterface::display()
diff --git a/src/plugins/platforms/xcb/qxcbscreen.cpp b/src/plugins/platforms/xcb/qxcbscreen.cpp
index 8da299d491..8bcaa78122 100644
--- a/src/plugins/platforms/xcb/qxcbscreen.cpp
+++ b/src/plugins/platforms/xcb/qxcbscreen.cpp
@@ -318,7 +318,7 @@ bool QXcbVirtualDesktop::xResource(const QByteArray &identifier,
 
 static bool parseXftInt(const QByteArray& stringValue, int *value)
 {
-    Q_ASSERT(value != 0);
+    Q_ASSERT(value != nullptr);
     bool ok;
     *value = stringValue.toInt(&ok);
     return ok;
@@ -457,7 +457,7 @@ const xcb_visualtype_t *QXcbVirtualDesktop::visualForId(xcb_visualid_t visualid)
 {
     QMap<xcb_visualid_t, xcb_visualtype_t>::const_iterator it = m_visuals.find(visualid);
     if (it == m_visuals.constEnd())
-        return 0;
+        return nullptr;
     return &*it;
 }
 
@@ -577,7 +577,7 @@ QWindow *QXcbScreen::topLevelAt(const QPoint &p) const
     do {
         auto translate_reply = Q_XCB_REPLY_UNCHECKED(xcb_translate_coordinates, xcb_connection(), parent, child, x, y);
         if (!translate_reply) {
-            return 0;
+            return nullptr;
         }
 
         parent = child;
@@ -586,14 +586,14 @@ QWindow *QXcbScreen::topLevelAt(const QPoint &p) const
         y = translate_reply->dst_y;
 
         if (!child || child == root)
-            return 0;
+            return nullptr;
 
         QPlatformWindow *platformWindow = connection()->platformWindowFromId(child);
         if (platformWindow)
             return platformWindow->window();
     } while (parent != child);
 
-    return 0;
+    return nullptr;
 }
 
 void QXcbScreen::windowShown(QXcbWindow *window)
diff --git a/src/plugins/platforms/xcb/qxcbsessionmanager.cpp b/src/plugins/platforms/xcb/qxcbsessionmanager.cpp
index f880d4d722..2eb32c069e 100644
--- a/src/plugins/platforms/xcb/qxcbsessionmanager.cpp
+++ b/src/plugins/platforms/xcb/qxcbsessionmanager.cpp
@@ -69,7 +69,7 @@ public Q_SLOTS:
 };
 
 
-static SmcConn smcConnection = 0;
+static SmcConn smcConnection = nullptr;
 static bool sm_interactionActive;
 static bool sm_smActive;
 static int sm_interactStyle;
@@ -81,7 +81,7 @@ static bool sm_phase2;
 static bool sm_in_phase2;
 bool qt_sm_blockUserInput = false;
 
-static QSmSocketReceiver* sm_receiver = 0;
+static QSmSocketReceiver* sm_receiver = nullptr;
 
 static void resetSmState();
 static void sm_setProperty(const char *name, const char *type,
@@ -191,7 +191,7 @@ static void sm_performSaveYourself(QXcbSessionManager *sm)
 
     // generate a new session key
     timeval tv;
-    gettimeofday(&tv, 0);
+    gettimeofday(&tv, nullptr);
     sm->setSessionKey(QString::number(qulonglong(tv.tv_sec)) +
                       QLatin1Char('_') +
                       QString::number(qulonglong(tv.tv_usec)));
@@ -203,7 +203,7 @@ static void sm_performSaveYourself(QXcbSessionManager *sm)
     // tell the session manager about our program in best POSIX style
     sm_setProperty(QString::fromLatin1(SmProgram), argument0);
     // tell the session manager about our user as well.
-    struct passwd *entryPtr = 0;
+    struct passwd *entryPtr = nullptr;
 #if defined(_POSIX_THREAD_SAFE_FUNCTIONS) && (_POSIX_THREAD_SAFE_FUNCTIONS - 0 > 0)
     QVarLengthArray<char, 1024> buf(qMax<long>(sysconf(_SC_GETPW_R_SIZE_MAX), 1024L));
     struct passwd entry;
@@ -329,7 +329,7 @@ static void sm_saveYourselfPhase2Callback(SmcConn smcConn, SmPointer clientData)
 
 void QSmSocketReceiver::socketActivated(int)
 {
-    IceProcessMessages(SmcGetIceConnection(smcConnection), 0, 0);
+    IceProcessMessages(SmcGetIceConnection(smcConnection), nullptr, nullptr);
 }
 
 
@@ -337,11 +337,11 @@ void QSmSocketReceiver::socketActivated(int)
 
 QXcbSessionManager::QXcbSessionManager(const QString &id, const QString &key)
     : QPlatformSessionManager(id, key)
-    , m_eventLoop(0)
+    , m_eventLoop(nullptr)
 {
     resetSmState();
     char cerror[256];
-    char* myId = 0;
+    char* myId = nullptr;
     QByteArray b_id = id.toLatin1();
     char* prevId = b_id.data();
 
@@ -359,7 +359,7 @@ QXcbSessionManager::QXcbSessionManager(const QString &id, const QString &key)
     if (!qEnvironmentVariableIsSet("SESSION_MANAGER"))
         return;
 
-    smcConnection = SmcOpenConnection(0, 0, 1, 0,
+    smcConnection = SmcOpenConnection(nullptr, nullptr, 1, 0,
                                       SmcSaveYourselfProcMask |
                                       SmcDieProcMask |
                                       SmcSaveCompleteProcMask |
@@ -382,8 +382,8 @@ QXcbSessionManager::QXcbSessionManager(const QString &id, const QString &key)
 QXcbSessionManager::~QXcbSessionManager()
 {
     if (smcConnection)
-        SmcCloseConnection(smcConnection, 0, 0);
-    smcConnection = 0;
+        SmcCloseConnection(smcConnection, 0, nullptr);
+    smcConnection = nullptr;
     delete sm_receiver;
 }
 
@@ -411,7 +411,7 @@ bool QXcbSessionManager::allowsInteraction()
         QEventLoop eventLoop;
         m_eventLoop = &eventLoop;
         eventLoop.exec();
-        m_eventLoop = 0;
+        m_eventLoop = nullptr;
 
         sm_waitingForInteraction = false;
         if (sm_smActive) { // not cancelled
@@ -441,7 +441,7 @@ bool QXcbSessionManager::allowsErrorInteraction()
         QEventLoop eventLoop;
         m_eventLoop = &eventLoop;
         eventLoop.exec();
-        m_eventLoop = 0;
+        m_eventLoop = nullptr;
 
         sm_waitingForInteraction = false;
         if (sm_smActive) { // not cancelled
diff --git a/src/plugins/platforms/xcb/qxcbsystemtraytracker.cpp b/src/plugins/platforms/xcb/qxcbsystemtraytracker.cpp
index 684e603fab..ff5ad98cd2 100644
--- a/src/plugins/platforms/xcb/qxcbsystemtraytracker.cpp
+++ b/src/plugins/platforms/xcb/qxcbsystemtraytracker.cpp
@@ -64,11 +64,11 @@ QXcbSystemTrayTracker *QXcbSystemTrayTracker::create(QXcbConnection *connection)
     // Selection, tray atoms for GNOME, NET WM Specification
     const xcb_atom_t trayAtom = connection->atom(QXcbAtom::_NET_SYSTEM_TRAY_OPCODE);
     if (!trayAtom)
-        return 0;
+        return nullptr;
     const QByteArray netSysTray = QByteArrayLiteral("_NET_SYSTEM_TRAY_S") + QByteArray::number(connection->primaryScreenNumber());
     const xcb_atom_t selection = connection->internAtom(netSysTray.constData());
     if (!selection)
-        return 0;
+        return nullptr;
 
     return new QXcbSystemTrayTracker(connection, trayAtom, selection);
 }
diff --git a/src/plugins/platforms/xcb/qxcbvulkaninstance.cpp b/src/plugins/platforms/xcb/qxcbvulkaninstance.cpp
index b3f8a5832d..7c15882768 100644
--- a/src/plugins/platforms/xcb/qxcbvulkaninstance.cpp
+++ b/src/plugins/platforms/xcb/qxcbvulkaninstance.cpp
@@ -93,7 +93,7 @@ bool QXcbVulkanInstance::supportsPresent(VkPhysicalDevice physicalDevice,
 
 VkSurfaceKHR QXcbVulkanInstance::createSurface(QXcbWindow *window)
 {
-    VkSurfaceKHR surface = 0;
+    VkSurfaceKHR surface = nullptr;
 
     if (!m_createSurface) {
         m_createSurface = reinterpret_cast<PFN_vkCreateXcbSurfaceKHR>(
diff --git a/src/plugins/platforms/xcb/qxcbvulkanwindow.cpp b/src/plugins/platforms/xcb/qxcbvulkanwindow.cpp
index 25bc340f97..17d7d9791e 100644
--- a/src/plugins/platforms/xcb/qxcbvulkanwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbvulkanwindow.cpp
@@ -43,7 +43,7 @@ QT_BEGIN_NAMESPACE
 
 QXcbVulkanWindow::QXcbVulkanWindow(QWindow *window)
     : QXcbWindow(window),
-      m_surface(0)
+      m_surface(nullptr)
 {
 }
 
diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index f505ddbd1e..66030b9ad4 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -174,13 +174,13 @@ static inline XTextProperty* qstringToXTP(Display *dpy, const QString& s)
 {
     #include <X11/Xatom.h>
 
-    static XTextProperty tp = { 0, 0, 0, 0 };
+    static XTextProperty tp = { nullptr, 0, 0, 0 };
     static bool free_prop = true; // we can't free tp.value in case it references
                                   // the data of the static QByteArray below.
     if (tp.value) {
         if (free_prop)
             XFree(tp.value);
-        tp.value = 0;
+        tp.value = nullptr;
         free_prop = true;
     }
 
@@ -191,7 +191,7 @@ static inline XTextProperty* qstringToXTP(Display *dpy, const QString& s)
         QByteArray mapped = mapper->fromUnicode(s);
         char* tl[2];
         tl[0] = mapped.data();
-        tl[1] = 0;
+        tl[1] = nullptr;
         errCode = XmbTextListToTextProperty(dpy, tl, 1, XStdICCTextStyle, &tp);
         if (errCode < 0)
             qCDebug(lcQpaXcb, "XmbTextListToTextProperty result code %d", errCode);
@@ -280,7 +280,7 @@ void QXcbWindow::create()
         m_window = platformScreen->root();
         m_depth = platformScreen->screen()->root_depth;
         m_visualId = platformScreen->screen()->root_visual;
-        const xcb_visualtype_t *visual = 0;
+        const xcb_visualtype_t *visual = nullptr;
         if (connection()->hasDefaultVisualId()) {
             visual = platformScreen->visualForId(connection()->defaultVisualId());
             if (visual)
@@ -819,7 +819,7 @@ bool QXcbWindow::relayFocusToModalWindow() const
     while (w && w->parent())
         w = w->parent();
 
-    QWindow *modalWindow = 0;
+    QWindow *modalWindow = nullptr;
     const bool blocked = QGuiApplicationPrivate::instance()->isWindowBlocked(w, &modalWindow);
     if (blocked && modalWindow != w) {
         modalWindow->requestActivate();
@@ -1193,7 +1193,7 @@ void QXcbWindow::updateNetWmUserTime(xcb_timestamp_t timestamp)
                               XCB_WINDOW_CLASS_INPUT_OUTPUT,   // window class
                               m_visualId,                      // visual
                               0,                               // value mask
-                              0);                              // value list
+                              nullptr);                              // value list
             wid = m_netWmUserTimeWindow;
             xcb_change_property(xcb_connection(), XCB_PROP_MODE_REPLACE, m_window, atom(QXcbAtom::_NET_WM_USER_TIME_WINDOW),
                                 XCB_ATOM_WINDOW, 32, 1, &m_netWmUserTimeWindow);
@@ -1223,7 +1223,7 @@ void QXcbWindow::setTransparentForMouseEvents(bool transparent)
 
     xcb_rectangle_t rectangle;
 
-    xcb_rectangle_t *rect = 0;
+    xcb_rectangle_t *rect = nullptr;
     int nrect = 0;
 
     if (!transparent) {
@@ -1882,7 +1882,7 @@ void QXcbWindow::handleButtonPressEvent(int event_x, int event_y, int root_x, in
     if (m_embedded && !m_trayIconWindow) {
         if (window() != QGuiApplication::focusWindow()) {
             const QXcbWindow *container = static_cast<const QXcbWindow *>(parent());
-            Q_ASSERT(container != 0);
+            Q_ASSERT(container != nullptr);
 
             sendXEmbedMessage(container->xcb_window(), XEMBED_REQUEST_FOCUS);
         }
@@ -2087,7 +2087,7 @@ void QXcbWindow::handleXIMouseEvent(xcb_ge_event_t *event, Qt::MouseEventSource
 
     const Qt::MouseButton button = conn->xiToQtMouseButton(ev->detail);
 
-    const char *sourceName = 0;
+    const char *sourceName = nullptr;
     if (Q_UNLIKELY(lcQpaXInputEvents().isDebugEnabled())) {
         const QMetaObject *metaObject = qt_getEnumMetaObject(source);
         const QMetaEnum me = metaObject->enumerator(metaObject->indexOfEnumerator(qt_getEnumName(source)));
diff --git a/src/plugins/platforms/xcb/qxcbxsettings.cpp b/src/plugins/platforms/xcb/qxcbxsettings.cpp
index 88f15e344f..902f196ba9 100644
--- a/src/plugins/platforms/xcb/qxcbxsettings.cpp
+++ b/src/plugins/platforms/xcb/qxcbxsettings.cpp
@@ -256,7 +256,7 @@ QXcbXSettings::QXcbXSettings(QXcbVirtualDesktop *screen)
 QXcbXSettings::~QXcbXSettings()
 {
     delete d_ptr;
-    d_ptr = 0;
+    d_ptr = nullptr;
 }
 
 bool QXcbXSettings::initialized() const