Another round of replacing 0 with nullptr

This time based on grepping to also include documentation, tests and
examples previously missed by the automatic tool.

Change-Id: Ied1703f4bcc470fbc275f759ed5b7c588a5c4e9f
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

112 files changed, 233 insertions, 233 deletions

diff --git a/src/corelib/doc/snippets/code/doc_src_properties.cpp b/src/corelib/doc/snippets/code/doc_src_properties.cpp
index 47dff630f8..5a5627abfd 100644
--- a/src/corelib/doc/snippets/code/doc_src_properties.cpp
+++ b/src/corelib/doc/snippets/code/doc_src_properties.cpp
@@ -106,7 +106,7 @@ class MyClass : public QObject
     Q_PROPERTY(Priority priority READ priority WRITE setPriority NOTIFY priorityChanged)
 
 public:
-    MyClass(QObject *parent = 0);
+    MyClass(QObject *parent = nullptr);
     ~MyClass();
 
     enum Priority { High, Low, VeryHigh, VeryLow };
diff --git a/src/corelib/doc/snippets/eventfilters/filterobject.h b/src/corelib/doc/snippets/eventfilters/filterobject.h
index 354aa4ff5c..d249743a15 100644
--- a/src/corelib/doc/snippets/eventfilters/filterobject.h
+++ b/src/corelib/doc/snippets/eventfilters/filterobject.h
@@ -58,7 +58,7 @@ class FilterObject : public QObject
     Q_OBJECT
 
 public:
-    FilterObject(QObject *parent = 0);
+    FilterObject(QObject *parent = nullptr);
     bool eventFilter(QObject *object, QEvent *event) override;
     void setFilteredObject(QObject *object);
 
diff --git a/src/corelib/doc/snippets/qsortfilterproxymodel-details/main.cpp b/src/corelib/doc/snippets/qsortfilterproxymodel-details/main.cpp
index 2a7b310716..a79f07c3ae 100644
--- a/src/corelib/doc/snippets/qsortfilterproxymodel-details/main.cpp
+++ b/src/corelib/doc/snippets/qsortfilterproxymodel-details/main.cpp
@@ -55,7 +55,7 @@
 class MyItemModel : public QStandardItemModel
 {
 public:
-    MyItemModel(QWidget *parent = 0);
+    MyItemModel(QWidget *parent = nullptr);
 };
 
 MyItemModel::MyItemModel(QWidget *parent)
@@ -65,7 +65,7 @@ MyItemModel::MyItemModel(QWidget *parent)
 class Widget : public QWidget
 {
 public:
-    Widget(QWidget *parent = 0);
+    Widget(QWidget *parent = nullptr);
 };
 
 Widget::Widget(QWidget *parent)
diff --git a/src/corelib/doc/snippets/qstring/main.cpp b/src/corelib/doc/snippets/qstring/main.cpp
index cb557ac023..419b98366d 100644
--- a/src/corelib/doc/snippets/qstring/main.cpp
+++ b/src/corelib/doc/snippets/qstring/main.cpp
@@ -55,7 +55,7 @@
 class Widget : public QWidget
 {
 public:
-    Widget(QWidget *parent = 0);
+    Widget(QWidget *parent = nullptr);
 
     void constCharPointer();
     void constCharArray();
diff --git a/src/corelib/doc/snippets/qstringlist/main.cpp b/src/corelib/doc/snippets/qstringlist/main.cpp
index 5284a5fb78..fceadc4e99 100644
--- a/src/corelib/doc/snippets/qstringlist/main.cpp
+++ b/src/corelib/doc/snippets/qstringlist/main.cpp
@@ -55,7 +55,7 @@ using namespace std;
 class Widget : public QWidget
 {
 public:
-    Widget(QWidget *parent = 0);
+    Widget(QWidget *parent = nullptr);
 };
 
 Widget::Widget(QWidget *parent)
diff --git a/src/corelib/doc/snippets/qstringlistmodel/main.cpp b/src/corelib/doc/snippets/qstringlistmodel/main.cpp
index 4c9519d2b2..fa7f414526 100644
--- a/src/corelib/doc/snippets/qstringlistmodel/main.cpp
+++ b/src/corelib/doc/snippets/qstringlistmodel/main.cpp
@@ -53,7 +53,7 @@
 class Widget : public QWidget
 {
 public:
-    Widget(QWidget *parent = 0);
+    Widget(QWidget *parent = nullptr);
 };
 
 Widget::Widget(QWidget *parent)
diff --git a/src/corelib/global/qglobal.h b/src/corelib/global/qglobal.h
index 25c31e4067..deb3dfe454 100644
--- a/src/corelib/global/qglobal.h
+++ b/src/corelib/global/qglobal.h
@@ -1184,7 +1184,7 @@ Q_CORE_EXPORT QString qtTrId(const char *id, int n = -1);
 #  define dynamic_cast QT_PREPEND_NAMESPACE(qt_dynamic_cast_check)
 
   template<typename T, typename X>
-  T qt_dynamic_cast_check(X, T* = 0)
+  T qt_dynamic_cast_check(X, T* = nullptr)
   { return T::dynamic_cast_will_always_fail_because_rtti_is_disabled; }
 #endif
 
diff --git a/src/corelib/io/qfilesystemengine_win.cpp b/src/corelib/io/qfilesystemengine_win.cpp
index b3d7ecfed8..d876fdf4ae 100644
--- a/src/corelib/io/qfilesystemengine_win.cpp
+++ b/src/corelib/io/qfilesystemengine_win.cpp
@@ -567,7 +567,7 @@ QString QFileSystemEngine::nativeAbsoluteFilePath(const QString &path)
     // can be //server or //server/share
     QString absPath;
     QVarLengthArray<wchar_t, MAX_PATH> buf(qMax(MAX_PATH, path.size() + 1));
-    wchar_t *fileName = 0;
+    wchar_t *fileName = nullptr;
     DWORD retLen = GetFullPathName((wchar_t*)path.utf16(), buf.size(), buf.data(), &fileName);
     if (retLen > (DWORD)buf.size()) {
         buf.resize(retLen);
diff --git a/src/corelib/io/qfilesystemwatcher_win.cpp b/src/corelib/io/qfilesystemwatcher_win.cpp
index b131524614..29dd78030b 100644
--- a/src/corelib/io/qfilesystemwatcher_win.cpp
+++ b/src/corelib/io/qfilesystemwatcher_win.cpp
@@ -406,7 +406,7 @@ QStringList QWindowsFileSystemWatcherEngine::addPaths(const QStringList &paths,
         pathInfo = fileInfo;
 
         // Look for a thread
-        QWindowsFileSystemWatcherEngineThread *thread = 0;
+        QWindowsFileSystemWatcherEngineThread *thread = nullptr;
         QWindowsFileSystemWatcherEngine::Handle handle;
         QList<QWindowsFileSystemWatcherEngineThread *>::const_iterator jt, end;
         end = threads.constEnd();
diff --git a/src/corelib/io/qstandardpaths_android.cpp b/src/corelib/io/qstandardpaths_android.cpp
index 1f4e0de1e7..f4a2a8f121 100644
--- a/src/corelib/io/qstandardpaths_android.cpp
+++ b/src/corelib/io/qstandardpaths_android.cpp
@@ -134,7 +134,7 @@ static QString getExternalStoragePublicDirectory(const char *directoryField)
  * Locations where applications can place persistent files it owns.
  * E.g., /storage/org.app/Music
  */
-static QString getExternalFilesDir(const char *directoryField = 0)
+static QString getExternalFilesDir(const char *directoryField = nullptr)
 {
     QString &path = (*androidDirCache)[QLatin1String("APPNAME_%1").arg(QLatin1String(directoryField))];
     if (!path.isEmpty())
diff --git a/src/corelib/io/qwindowspipereader_p.h b/src/corelib/io/qwindowspipereader_p.h
index 5ec9dc379c..2842343597 100644
--- a/src/corelib/io/qwindowspipereader_p.h
+++ b/src/corelib/io/qwindowspipereader_p.h
@@ -62,7 +62,7 @@ class Q_CORE_EXPORT QWindowsPipeReader : public QObject
 {
     Q_OBJECT
 public:
-    explicit QWindowsPipeReader(QObject *parent = 0);
+    explicit QWindowsPipeReader(QObject *parent = nullptr);
     ~QWindowsPipeReader();
 
     void setHandle(HANDLE hPipeReadEnd);
diff --git a/src/corelib/io/qwindowspipewriter_p.h b/src/corelib/io/qwindowspipewriter_p.h
index f7f68b688c..39e8ffe40a 100644
--- a/src/corelib/io/qwindowspipewriter_p.h
+++ b/src/corelib/io/qwindowspipewriter_p.h
@@ -111,7 +111,7 @@ class Q_CORE_EXPORT QWindowsPipeWriter : public QObject
 {
     Q_OBJECT
 public:
-    explicit QWindowsPipeWriter(HANDLE pipeWriteEnd, QObject *parent = 0);
+    explicit QWindowsPipeWriter(HANDLE pipeWriteEnd, QObject *parent = nullptr);
     ~QWindowsPipeWriter();
 
     bool write(const QByteArray &ba);
diff --git a/src/corelib/kernel/qeventdispatcher_cf_p.h b/src/corelib/kernel/qeventdispatcher_cf_p.h
index eb84b0a64c..2d76bf53da 100644
--- a/src/corelib/kernel/qeventdispatcher_cf_p.h
+++ b/src/corelib/kernel/qeventdispatcher_cf_p.h
@@ -209,7 +209,7 @@ class Q_CORE_EXPORT QEventDispatcherCoreFoundation : public QAbstractEventDispat
     Q_OBJECT
 
 public:
-    explicit QEventDispatcherCoreFoundation(QObject *parent = 0);
+    explicit QEventDispatcherCoreFoundation(QObject *parent = nullptr);
     void startingUp() override;
     ~QEventDispatcherCoreFoundation();
 
diff --git a/src/corelib/kernel/qeventdispatcher_win.cpp b/src/corelib/kernel/qeventdispatcher_win.cpp
index 03d003bb0f..44487d57e2 100644
--- a/src/corelib/kernel/qeventdispatcher_win.cpp
+++ b/src/corelib/kernel/qeventdispatcher_win.cpp
@@ -162,8 +162,8 @@ LRESULT QT_WIN_CALLBACK qt_internal_proc(HWND hwnd, UINT message, WPARAM wp, LPA
 #else
     auto q = reinterpret_cast<QEventDispatcherWin32 *>(GetWindowLong(hwnd, GWL_USERDATA));
 #endif
-    QEventDispatcherWin32Private *d = 0;
-    if (q != 0)
+    QEventDispatcherWin32Private *d = nullptr;
+    if (q != nullptr)
         d = q->d_func();
 
     switch (message) {
@@ -187,7 +187,7 @@ LRESULT QT_WIN_CALLBACK qt_internal_proc(HWND hwnd, UINT message, WPARAM wp, LPA
             break;
         }
         if (type >= 0) {
-            Q_ASSERT(d != 0);
+            Q_ASSERT(d != nullptr);
             QSNDict *sn_vec[4] = { &d->sn_read, &d->sn_write, &d->sn_except, &d->sn_read };
             QSNDict *dict = sn_vec[type];
 
@@ -217,7 +217,7 @@ LRESULT QT_WIN_CALLBACK qt_internal_proc(HWND hwnd, UINT message, WPARAM wp, LPA
         return 0;
     }
     case WM_QT_ACTIVATENOTIFIERS: {
-        Q_ASSERT(d != 0);
+        Q_ASSERT(d != nullptr);
 
         // Postpone activation if we have unhandled socket notifier messages
         // in the queue. WM_QT_ACTIVATENOTIFIERS will be posted again as a result of
@@ -242,7 +242,7 @@ LRESULT QT_WIN_CALLBACK qt_internal_proc(HWND hwnd, UINT message, WPARAM wp, LPA
         return 0;
     }
     case WM_TIMER:
-        Q_ASSERT(d != 0);
+        Q_ASSERT(d != nullptr);
 
         if (wp == d->sendPostedEventsTimerId)
             q->sendPostedEvents();
@@ -250,7 +250,7 @@ LRESULT QT_WIN_CALLBACK qt_internal_proc(HWND hwnd, UINT message, WPARAM wp, LPA
             d->sendTimerEvent(wp);
         return 0;
     case WM_QT_SENDPOSTEDEVENTS:
-        Q_ASSERT(d != 0);
+        Q_ASSERT(d != nullptr);
 
         // We send posted events manually, if the window procedure was invoked
         // by the foreign event loop (e.g. from the native modal dialog).
@@ -268,7 +268,7 @@ LRESULT QT_WIN_CALLBACK qt_internal_proc(HWND hwnd, UINT message, WPARAM wp, LPA
 LRESULT QT_WIN_CALLBACK qt_GetMessageHook(int code, WPARAM wp, LPARAM lp)
 {
     QEventDispatcherWin32 *q = qobject_cast<QEventDispatcherWin32 *>(QAbstractEventDispatcher::instance());
-    Q_ASSERT(q != 0);
+    Q_ASSERT(q != nullptr);
     QEventDispatcherWin32Private *d = q->d_func();
     MSG *msg = reinterpret_cast<MSG *>(lp);
     // Windows unexpectedly passes PM_NOYIELD flag to the hook procedure,
diff --git a/src/corelib/kernel/qeventdispatcher_win_p.h b/src/corelib/kernel/qeventdispatcher_win_p.h
index 9ee4eb725d..a5c063e062 100644
--- a/src/corelib/kernel/qeventdispatcher_win_p.h
+++ b/src/corelib/kernel/qeventdispatcher_win_p.h
@@ -73,7 +73,7 @@ class Q_CORE_EXPORT QEventDispatcherWin32 : public QAbstractEventDispatcher
     Q_DECLARE_PRIVATE(QEventDispatcherWin32)
 
 public:
-    explicit QEventDispatcherWin32(QObject *parent = 0);
+    explicit QEventDispatcherWin32(QObject *parent = nullptr);
     ~QEventDispatcherWin32();
 
     bool QT_ENSURE_STACK_ALIGNED_FOR_SSE processEvents(QEventLoop::ProcessEventsFlags flags) override;
@@ -103,7 +103,7 @@ public:
     HWND internalHwnd();
 
 protected:
-    QEventDispatcherWin32(QEventDispatcherWin32Private &dd, QObject *parent = 0);
+    QEventDispatcherWin32(QEventDispatcherWin32Private &dd, QObject *parent = nullptr);
     virtual void sendPostedEvents();
     void doUnregisterSocketNotifier(QSocketNotifier *notifier);
     void doUnregisterEventNotifier(QWinEventNotifier *notifier);
diff --git a/src/corelib/kernel/qjni.cpp b/src/corelib/kernel/qjni.cpp
index 5f652d70e3..b593483e59 100644
--- a/src/corelib/kernel/qjni.cpp
+++ b/src/corelib/kernel/qjni.cpp
@@ -81,7 +81,7 @@ static QByteArray toBinaryEncClassName(const QByteArray &className)
     return QByteArray(className).replace('/', '.');
 }
 
-static jclass getCachedClass(const QByteArray &classBinEnc, bool *isCached = 0)
+static jclass getCachedClass(const QByteArray &classBinEnc, bool *isCached = nullptr)
 {
     QReadLocker locker(cachedClassesLock);
     const QHash<QString, jclass>::const_iterator &it = cachedClasses->constFind(QString::fromLatin1(classBinEnc));
diff --git a/src/corelib/kernel/qjni_p.h b/src/corelib/kernel/qjni_p.h
index ec8525e6e1..b5139d404b 100644
--- a/src/corelib/kernel/qjni_p.h
+++ b/src/corelib/kernel/qjni_p.h
@@ -72,7 +72,7 @@ public:
     ~QJNIEnvironmentPrivate();
     JNIEnv *operator->();
     operator JNIEnv*() const;
-    static jclass findClass(const char *className, JNIEnv *env = 0);
+    static jclass findClass(const char *className, JNIEnv *env = nullptr);
 
 private:
     friend class QAndroidJniEnvironment;
diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp
index b3807b145d..60588e9329 100644
--- a/src/corelib/kernel/qmetatype.cpp
+++ b/src/corelib/kernel/qmetatype.cpp
@@ -579,7 +579,7 @@ const QMetaObject *QMetaType::metaObject() const
 }
 
 /*!
-    \fn void *QMetaType::create(const void *copy = 0) const
+    \fn void *QMetaType::create(const void *copy = nullptr) const
     \since 5.0
 
     Returns a copy of \a copy, assuming it is of the type that this
@@ -624,7 +624,7 @@ void QMetaType::destroy(void *data) const
 }
 
 /*!
-    \fn void *QMetaType::construct(void *where, const void *copy = 0) const
+    \fn void *QMetaType::construct(void *where, const void *copy = nullptr) const
     \since 5.0
 
     Constructs a value of the type that this QMetaType instance
diff --git a/src/corelib/kernel/qpoll.cpp b/src/corelib/kernel/qpoll.cpp
index 8b87bfe79d..f41c413db6 100644
--- a/src/corelib/kernel/qpoll.cpp
+++ b/src/corelib/kernel/qpoll.cpp
@@ -177,7 +177,7 @@ int qt_poll(struct pollfd *fds, nfds_t nfds, const struct timespec *timeout_ts)
     }
 
     fd_set read_fds, write_fds, except_fds;
-    struct timeval tv, *ptv = 0;
+    struct timeval tv, *ptv = nullptr;
 
     if (timeout_ts) {
         tv = timespecToTimeval(*timeout_ts);
diff --git a/src/corelib/kernel/qproperty.h b/src/corelib/kernel/qproperty.h
index 156696dace..ab93cdccc6 100644
--- a/src/corelib/kernel/qproperty.h
+++ b/src/corelib/kernel/qproperty.h
@@ -207,7 +207,7 @@ public:
 namespace Qt {
     template <typename Functor>
     auto makePropertyBinding(Functor &&f, const QPropertyBindingSourceLocation &location = QT_PROPERTY_DEFAULT_BINDING_LOCATION,
-                             std::enable_if_t<std::is_invocable_v<Functor>> * = 0)
+                             std::enable_if_t<std::is_invocable_v<Functor>> * = nullptr)
     {
         return QPropertyBinding<std::invoke_result_t<Functor>>(std::forward<Functor>(f), location);
     }
@@ -321,7 +321,7 @@ public:
 #ifndef Q_CLANG_QDOC
     template <typename Functor>
     explicit QProperty(Functor &&f, const QPropertyBindingSourceLocation &location = QT_PROPERTY_DEFAULT_BINDING_LOCATION,
-                       typename std::enable_if_t<std::is_invocable_r_v<T, Functor&>> * = 0)
+                       typename std::enable_if_t<std::is_invocable_r_v<T, Functor&>> * = nullptr)
         : QProperty(QPropertyBinding<T>(std::forward<Functor>(f), location))
     {}
 #else
@@ -821,7 +821,7 @@ public:
 #ifndef Q_CLANG_QDOC
     template <typename Functor>
     explicit QObjectBindableProperty(Functor &&f, const QPropertyBindingSourceLocation &location = QT_PROPERTY_DEFAULT_BINDING_LOCATION,
-                       typename std::enable_if_t<std::is_invocable_r_v<T, Functor&>> * = 0)
+                       typename std::enable_if_t<std::is_invocable_r_v<T, Functor&>> * = nullptr)
         : QObjectBindableProperty(QPropertyBinding<T>(std::forward<Functor>(f), location))
     {}
 #else
diff --git a/src/corelib/kernel/qsystemerror.cpp b/src/corelib/kernel/qsystemerror.cpp
index a2df9dee93..030c38e045 100644
--- a/src/corelib/kernel/qsystemerror.cpp
+++ b/src/corelib/kernel/qsystemerror.cpp
@@ -76,7 +76,7 @@ namespace {
 static QString windowsErrorString(int errorCode)
 {
     QString ret;
-    wchar_t *string = 0;
+    wchar_t *string = nullptr;
     FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM,
                   NULL,
                   errorCode,
diff --git a/src/corelib/plugin/qmachparser.cpp b/src/corelib/plugin/qmachparser.cpp
index 11670cafe9..9d0b4de4f5 100644
--- a/src/corelib/plugin/qmachparser.cpp
+++ b/src/corelib/plugin/qmachparser.cpp
@@ -103,7 +103,7 @@ int QMachOParser::parse(const char *m_s, ulong fdlen, const QString &library, QS
         return ns(QLibrary::tr("file too small"), library, errorString);
 
     // find out if this is a fat Mach-O binary first
-    const my_mach_header *header = 0;
+    const my_mach_header *header = nullptr;
     const fat_header *fat = reinterpret_cast<const fat_header *>(m_s);
     if (fat->magic == qToBigEndian(FAT_MAGIC)) {
         // find our architecture in the binary
diff --git a/src/corelib/thread/qthread.cpp b/src/corelib/thread/qthread.cpp
index e0d252b8ee..2f6a7a18ba 100644
--- a/src/corelib/thread/qthread.cpp
+++ b/src/corelib/thread/qthread.cpp
@@ -895,7 +895,7 @@ bool QThread::isRunning() const
 }
 
 // No threads: so we can just use static variables
-static QThreadData *data = 0;
+static QThreadData *data = nullptr;
 
 QThreadData *QThreadData::current(bool createIfNecessary)
 {
diff --git a/src/corelib/thread/qthread_p.h b/src/corelib/thread/qthread_p.h
index c853bd1de4..0a73bf8a36 100644
--- a/src/corelib/thread/qthread_p.h
+++ b/src/corelib/thread/qthread_p.h
@@ -208,7 +208,7 @@ public:
 class QThreadPrivate : public QObjectPrivate
 {
 public:
-    QThreadPrivate(QThreadData *d = 0);
+    QThreadPrivate(QThreadData *d = nullptr);
     ~QThreadPrivate();
 
     mutable QMutex mutex;
diff --git a/src/corelib/tools/qscopedpointer.cpp b/src/corelib/tools/qscopedpointer.cpp
index eb08bdba62..7647916e99 100644
--- a/src/corelib/tools/qscopedpointer.cpp
+++ b/src/corelib/tools/qscopedpointer.cpp
@@ -126,7 +126,7 @@ QT_BEGIN_NAMESPACE
  */
 
 /*!
-    \fn template <typename T, typename Cleanup> QScopedPointer<T, Cleanup>::QScopedPointer(T *p = 0)
+    \fn template <typename T, typename Cleanup> QScopedPointer<T, Cleanup>::QScopedPointer(T *p = nullptr)
 
     Constructs this QScopedPointer instance and sets its pointer to \a p.
 */
@@ -242,7 +242,7 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
-    \fn template <typename T, typename Cleanup> void QScopedPointer<T, Cleanup>::reset(T *other = 0)
+    \fn template <typename T, typename Cleanup> void QScopedPointer<T, Cleanup>::reset(T *other = nullptr)
 
     Deletes the existing object it is pointing to (if any), and sets its pointer to
     \a other. QScopedPointer now owns \a other and will delete it in its
diff --git a/src/corelib/tools/qscopedpointer_p.h b/src/corelib/tools/qscopedpointer_p.h
index c1c44e7695..233c2201dc 100644
--- a/src/corelib/tools/qscopedpointer_p.h
+++ b/src/corelib/tools/qscopedpointer_p.h
@@ -64,7 +64,7 @@ template <typename T, typename Cleanup = QScopedPointerDeleter<T> >
 class QCustomScopedPointer : public QScopedPointer<T, Cleanup>
 {
 public:
-    explicit inline QCustomScopedPointer(T *p = 0)
+    explicit inline QCustomScopedPointer(T *p = nullptr)
         : QScopedPointer<T, Cleanup>(p)
     {
     }
@@ -107,7 +107,7 @@ template <typename T>
 class QScopedSharedPointer : public QCustomScopedPointer<T, QScopedPointerSharedDeleter<T> >
 {
 public:
-    explicit inline QScopedSharedPointer(T *p = 0)
+    explicit inline QScopedSharedPointer(T *p = nullptr)
         : QCustomScopedPointer<T, QScopedPointerSharedDeleter<T> >(p)
     {
     }
diff --git a/src/dbus/qdbus_symbols.cpp b/src/dbus/qdbus_symbols.cpp
index dd74307fda..bd4299809b 100644
--- a/src/dbus/qdbus_symbols.cpp
+++ b/src/dbus/qdbus_symbols.cpp
@@ -56,7 +56,7 @@ void (*qdbus_resolve_me(const char *name))();
 #if !defined QT_LINKED_LIBDBUS
 
 #if QT_CONFIG(library)
-static QLibrary *qdbus_libdbus = 0;
+static QLibrary *qdbus_libdbus = nullptr;
 
 void qdbus_unloadLibDBus()
 {
@@ -66,7 +66,7 @@ void qdbus_unloadLibDBus()
         qdbus_libdbus->unload();
     }
     delete qdbus_libdbus;
-    qdbus_libdbus = 0;
+    qdbus_libdbus = nullptr;
 }
 #endif
 
@@ -118,7 +118,7 @@ bool qdbus_loadLibDBus()
     }
 
     delete lib;
-    lib = 0;
+    lib = nullptr;
     return false;
 #else
     return true;
diff --git a/src/gui/doc/snippets/textdocument-listitems/mainwindow.cpp b/src/gui/doc/snippets/textdocument-listitems/mainwindow.cpp
index 7daf4f46c3..5179208f61 100644
--- a/src/gui/doc/snippets/textdocument-listitems/mainwindow.cpp
+++ b/src/gui/doc/snippets/textdocument-listitems/mainwindow.cpp
@@ -130,9 +130,9 @@ void MainWindow::showList()
     headerLabels << tr("Lists");
     treeWidget->setHeaderLabels(headerLabels);
 
-    QTreeWidgetItem *parentItem = 0;
+    QTreeWidgetItem *parentItem = nullptr;
     QTreeWidgetItem *item;
-    QTreeWidgetItem *lastItem = 0;
+    QTreeWidgetItem *lastItem = nullptr;
     parentItems.clear();
     previousItems.clear();
 
diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index 2f9349bb55..1499c4b57e 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -1752,7 +1752,7 @@ void restoreOverrideCursor();
 static QFont font();
 static QFont font(const QWidget*);
 static QFont font(const char *className);
-static void setFont(const QFont &, const char* className = 0);
+static void setFont(const QFont &, const char *className = nullptr);
 static QFontMetrics fontMetrics();
 
 #ifndef QT_NO_CLIPBOARD
diff --git a/src/gui/opengl/qopenglfunctions.h b/src/gui/opengl/qopenglfunctions.h
index 76552cdd0e..c288df53b5 100644
--- a/src/gui/opengl/qopenglfunctions.h
+++ b/src/gui/opengl/qopenglfunctions.h
@@ -68,7 +68,7 @@ typedef double GLdouble;
         unsigned clamped = qMin(unsigned(error - GL_INVALID_ENUM), 4U); \
         const char *errors[] = { "GL_INVALID_ENUM", "GL_INVALID_VALUE", "GL_INVALID_OPERATION", "Unknown" }; \
         printf("GL error at %s:%d: %s\n", __FILE__, __LINE__, errors[clamped]); \
-        int *value = 0; \
+        int *value = nullptr; \
         *value = 0; \
     }
 #else
diff --git a/src/gui/painting/qcoregraphics.mm b/src/gui/painting/qcoregraphics.mm
index 302fa1b049..ef29f4a490 100644
--- a/src/gui/painting/qcoregraphics.mm
+++ b/src/gui/painting/qcoregraphics.mm
@@ -510,7 +510,7 @@ void QMacCGContext::initialize(const QImage *image, QPainter *painter)
                 clip &= painterClip;
         }
 
-        qt_mac_clip_cg(context, clip, 0);
+        qt_mac_clip_cg(context, clip, nullptr);
 
         CGContextTranslateCTM(context, deviceTransform.dx(), deviceTransform.dy());
     }
diff --git a/src/gui/platform/windows/qwindowsguieventdispatcher_p.h b/src/gui/platform/windows/qwindowsguieventdispatcher_p.h
index c6506f2dc9..804c7e936d 100644
--- a/src/gui/platform/windows/qwindowsguieventdispatcher_p.h
+++ b/src/gui/platform/windows/qwindowsguieventdispatcher_p.h
@@ -60,7 +60,7 @@ class Q_GUI_EXPORT QWindowsGuiEventDispatcher : public QEventDispatcherWin32
 {
     Q_OBJECT
 public:
-    explicit QWindowsGuiEventDispatcher(QObject *parent = 0);
+    explicit QWindowsGuiEventDispatcher(QObject *parent = nullptr);
 
     static const char *windowsMessageName(UINT msg);
 
diff --git a/src/gui/text/qstatictext.cpp b/src/gui/text/qstatictext.cpp
index 2d4fd5594d..b702764688 100644
--- a/src/gui/text/qstatictext.cpp
+++ b/src/gui/text/qstatictext.cpp
@@ -84,7 +84,7 @@ QStaticTextUserData::~QStaticTextUserData()
     class MyWidget: public QWidget
     {
     public:
-        MyWidget(QWidget *parent = 0) : QWidget(parent), m_staticText("This is static text")
+        MyWidget(QWidget *parent = nullptr) : QWidget(parent), m_staticText("This is static text")
 
     protected:
         void paintEvent(QPaintEvent *)
diff --git a/src/gui/text/windows/qwindowsfontdatabase.cpp b/src/gui/text/windows/qwindowsfontdatabase.cpp
index 36d8da0ce8..9ee1c5aba6 100644
--- a/src/gui/text/windows/qwindowsfontdatabase.cpp
+++ b/src/gui/text/windows/qwindowsfontdatabase.cpp
@@ -1139,7 +1139,7 @@ QFontEngine *QWindowsFontDatabase::createEngine(const QFontDef &request, const Q
                                                 int dpi,
                                                 const QSharedPointer<QWindowsFontEngineData> &data)
 {
-    QFontEngine *fe = 0;
+    QFontEngine *fe = nullptr;
 
     LOGFONT lf = fontDefToLOGFONT(request, faceName);
     const bool preferClearTypeAA = lf.lfQuality == CLEARTYPE_QUALITY;
diff --git a/src/gui/text/windows/qwindowsfontengine.cpp b/src/gui/text/windows/qwindowsfontengine.cpp
index cbf50f65da..dd0fbbf262 100644
--- a/src/gui/text/windows/qwindowsfontengine.cpp
+++ b/src/gui/text/windows/qwindowsfontengine.cpp
@@ -642,7 +642,7 @@ qreal QWindowsFontEngine::minRightBearing() const
         HDC hdc = m_fontEngineData->hdc;
         SelectObject(hdc, hfont);
         if (ttf) {
-            ABC *abc = 0;
+            ABC *abc = nullptr;
             int n = tm.tmLastChar - tm.tmFirstChar;
             if (n <= max_font_count) {
                 abc = new ABC[n+1];
@@ -706,7 +706,7 @@ static inline QPointF qt_to_qpointf(const POINTFX &pt, qreal scale, qreal stretc
 #endif
 
 static bool addGlyphToPath(glyph_t glyph, const QFixedPoint &position, HDC hdc,
-                           QPainterPath *path, bool ttf, glyph_metrics_t *metric = 0,
+                           QPainterPath *path, bool ttf, glyph_metrics_t *metric = nullptr,
                            qreal scale = 1.0, qreal stretch = 1.0)
 {
     MAT2 mat;
diff --git a/src/gui/text/windows/qwindowsfontengine_p.h b/src/gui/text/windows/qwindowsfontengine_p.h
index 8a676affcd..22130924ad 100644
--- a/src/gui/text/windows/qwindowsfontengine_p.h
+++ b/src/gui/text/windows/qwindowsfontengine_p.h
@@ -115,7 +115,7 @@ public:
     bool supportsTransformation(const QTransform &transform) const override;
 
 #ifndef Q_CC_MINGW
-    void getGlyphBearings(glyph_t glyph, qreal *leftBearing = 0, qreal *rightBearing = 0) override;
+    void getGlyphBearings(glyph_t glyph, qreal *leftBearing = nullptr, qreal *rightBearing = nullptr) override;
 #endif
 
     bool hasUnreliableGlyphOutline() const override;
diff --git a/src/network/kernel/qnetworkinterface_unix.cpp b/src/network/kernel/qnetworkinterface_unix.cpp
index 4b8c58cb40..5b34b99caa 100644
--- a/src/network/kernel/qnetworkinterface_unix.cpp
+++ b/src/network/kernel/qnetworkinterface_unix.cpp
@@ -209,7 +209,7 @@ static QSet<QByteArray> interfaceNames(int socket)
 static QNetworkInterfacePrivate *findInterface(int socket, QList<QNetworkInterfacePrivate *> &interfaces,
                                                struct ifreq &req)
 {
-    QNetworkInterfacePrivate *iface = 0;
+    QNetworkInterfacePrivate *iface = nullptr;
     int ifindex = 0;
 
 #if !defined(QT_NO_IPV6IFNAME) || defined(SIOCGIFINDEX)
@@ -618,7 +618,7 @@ static QList<QNetworkInterfacePrivate *> interfaceListing()
     for (ifaddrs *ptr = interfaceListing; ptr; ptr = ptr->ifa_next) {
         // Find the interface
         QLatin1String name(ptr->ifa_name);
-        QNetworkInterfacePrivate *iface = 0;
+        QNetworkInterfacePrivate *iface = nullptr;
         QList<QNetworkInterfacePrivate *>::Iterator if_it = interfaces.begin();
         for ( ; if_it != interfaces.end(); ++if_it)
             if ((*if_it)->name == name) {
diff --git a/src/platformsupport/devicediscovery/qdevicediscovery_dummy_p.h b/src/platformsupport/devicediscovery/qdevicediscovery_dummy_p.h
index fe669c8dec..92a9351f2e 100644
--- a/src/platformsupport/devicediscovery/qdevicediscovery_dummy_p.h
+++ b/src/platformsupport/devicediscovery/qdevicediscovery_dummy_p.h
@@ -60,7 +60,7 @@ class QDeviceDiscoveryDummy : public QDeviceDiscovery
     Q_OBJECT
 
 public:
-    QDeviceDiscoveryDummy(QDeviceTypes types, QObject *parent = 0);
+    QDeviceDiscoveryDummy(QDeviceTypes types, QObject *parent = nullptr);
     QStringList scanConnectedDevices() override;
 };
 
diff --git a/src/platformsupport/devicediscovery/qdevicediscovery_static_p.h b/src/platformsupport/devicediscovery/qdevicediscovery_static_p.h
index 93110c3c55..0cf70a32a8 100644
--- a/src/platformsupport/devicediscovery/qdevicediscovery_static_p.h
+++ b/src/platformsupport/devicediscovery/qdevicediscovery_static_p.h
@@ -60,7 +60,7 @@ class QDeviceDiscoveryStatic : public QDeviceDiscovery
     Q_OBJECT
 
 public:
-    QDeviceDiscoveryStatic(QDeviceTypes types, QObject *parent = 0);
+    QDeviceDiscoveryStatic(QDeviceTypes types, QObject *parent = nullptr);
     QStringList scanConnectedDevices() override;
 
 private:
diff --git a/src/platformsupport/devicediscovery/qdevicediscovery_udev.cpp b/src/platformsupport/devicediscovery/qdevicediscovery_udev.cpp
index 96af9a2b47..1853c2260a 100644
--- a/src/platformsupport/devicediscovery/qdevicediscovery_udev.cpp
+++ b/src/platformsupport/devicediscovery/qdevicediscovery_udev.cpp
@@ -60,7 +60,7 @@ QDeviceDiscovery *QDeviceDiscovery::create(QDeviceTypes types, QObject *parent)
 {
     qCDebug(lcDD) << "udev device discovery for type" << types;
 
-    QDeviceDiscovery *helper = 0;
+    QDeviceDiscovery *helper = nullptr;
     struct udev *udev;
 
     udev = udev_new();
diff --git a/src/platformsupport/input/evdevkeyboard/qevdevkeyboardhandler.cpp b/src/platformsupport/input/evdevkeyboard/qevdevkeyboardhandler.cpp
index d951688b4f..788a135f9e 100644
--- a/src/platformsupport/input/evdevkeyboard/qevdevkeyboardhandler.cpp
+++ b/src/platformsupport/input/evdevkeyboard/qevdevkeyboardhandler.cpp
@@ -250,8 +250,8 @@ QEvdevKeyboardHandler::KeycodeAction QEvdevKeyboardHandler::processKeycode(quint
     KeycodeAction result = None;
     bool first_press = pressed && !autorepeat;
 
-    const QEvdevKeyboardMap::Mapping *map_plain = 0;
-    const QEvdevKeyboardMap::Mapping *map_withmod = 0;
+    const QEvdevKeyboardMap::Mapping *map_plain = nullptr;
+    const QEvdevKeyboardMap::Mapping *map_withmod = nullptr;
 
     quint8 modifiers = m_modifiers;
 
diff --git a/src/platformsupport/input/tslib/qtslib_p.h b/src/platformsupport/input/tslib/qtslib_p.h
index ffd60cd0e3..b49531ebd3 100644
--- a/src/platformsupport/input/tslib/qtslib_p.h
+++ b/src/platformsupport/input/tslib/qtslib_p.h
@@ -64,7 +64,7 @@ class QTsLibMouseHandler : public QObject
     Q_OBJECT
 
 public:
-    QTsLibMouseHandler(const QString &key, const QString &specification, QObject *parent = 0);
+    QTsLibMouseHandler(const QString &key, const QString &specification, QObject *parent = nullptr);
     ~QTsLibMouseHandler();
 
 private slots:
diff --git a/src/plugins/platforms/android/androidjniaccessibility.cpp b/src/plugins/platforms/android/androidjniaccessibility.cpp
index 4d263831e1..8d9a968b4f 100644
--- a/src/plugins/platforms/android/androidjniaccessibility.cpp
+++ b/src/plugins/platforms/android/androidjniaccessibility.cpp
@@ -98,7 +98,7 @@ namespace QtAndroidAccessibility
 
     QAccessibleInterface *interfaceFromId(jint objectId)
     {
-        QAccessibleInterface *iface = 0;
+        QAccessibleInterface *iface = nullptr;
         if (objectId == -1) {
             QWindow *win = qApp->focusWindow();
             if (win)
@@ -164,7 +164,7 @@ namespace QtAndroidAccessibility
             QPoint pos = QHighDpi::fromNativePixels(QPoint(int(x), int(y)), root->window());
 
             QAccessibleInterface *child = root->childAt(pos.x(), pos.y());
-            QAccessibleInterface *lastChild = 0;
+            QAccessibleInterface *lastChild = nullptr;
             while (child && (child != lastChild)) {
                 lastChild = child;
                 child = child->childAt(pos.x(), pos.y());
diff --git a/src/plugins/platforms/android/androidjnimain.h b/src/plugins/platforms/android/androidjnimain.h
index 63be5910f9..6902f89341 100644
--- a/src/plugins/platforms/android/androidjnimain.h
+++ b/src/plugins/platforms/android/androidjnimain.h
@@ -96,9 +96,9 @@ namespace QtAndroid
     };
     void setSystemUiVisibility(SystemUiVisibility uiVisibility);
 
-    jobject createBitmap(QImage img, JNIEnv *env = 0);
+    jobject createBitmap(QImage img, JNIEnv *env = nullptr);
     jobject createBitmap(int width, int height, QImage::Format format, JNIEnv *env);
-    jobject createBitmapDrawable(jobject bitmap, JNIEnv *env = 0);
+    jobject createBitmapDrawable(jobject bitmap, JNIEnv *env = nullptr);
 
     const char *classErrorMsgFmt();
     const char *methodErrorMsgFmt();
diff --git a/src/plugins/platforms/android/androidjnimenu.cpp b/src/plugins/platforms/android/androidjnimenu.cpp
index de2fdaa0e2..fe5de1f882 100644
--- a/src/plugins/platforms/android/androidjnimenu.cpp
+++ b/src/plugins/platforms/android/androidjnimenu.cpp
@@ -59,12 +59,12 @@ using namespace QtAndroid;
 namespace QtAndroidMenu
 {
     static QList<QAndroidPlatformMenu *> pendingContextMenus;
-    static QAndroidPlatformMenu *visibleMenu = 0;
+    static QAndroidPlatformMenu *visibleMenu = nullptr;
     static QRecursiveMutex visibleMenuMutex;
 
     static QSet<QAndroidPlatformMenuBar *> menuBars;
-    static QAndroidPlatformMenuBar *visibleMenuBar = 0;
-    static QWindow *activeTopLevelWindow = 0;
+    static QAndroidPlatformMenuBar *visibleMenuBar = nullptr;
+    static QWindow *activeTopLevelWindow = nullptr;
     static QRecursiveMutex menuBarMutex;
 
     static jmethodID openContextMenuMethodID = 0;
diff --git a/src/plugins/platforms/android/qandroideventdispatcher.h b/src/plugins/platforms/android/qandroideventdispatcher.h
index 85d4cee6cb..8a29ed7e7e 100644
--- a/src/plugins/platforms/android/qandroideventdispatcher.h
+++ b/src/plugins/platforms/android/qandroideventdispatcher.h
@@ -48,7 +48,7 @@ class QAndroidEventDispatcher : public QUnixEventDispatcherQPA
 {
     Q_OBJECT
 public:
-    explicit QAndroidEventDispatcher(QObject *parent = 0);
+    explicit QAndroidEventDispatcher(QObject *parent = nullptr);
     ~QAndroidEventDispatcher();
     void start();
     void stop();
diff --git a/src/plugins/platforms/android/qandroidinputcontext.cpp b/src/plugins/platforms/android/qandroidinputcontext.cpp
index 5add7b0746..fc71b391c0 100644
--- a/src/plugins/platforms/android/qandroidinputcontext.cpp
+++ b/src/plugins/platforms/android/qandroidinputcontext.cpp
@@ -91,7 +91,7 @@ private:
 
 } // namespace anonymous
 
-static QAndroidInputContext *m_androidInputContext = 0;
+static QAndroidInputContext *m_androidInputContext = nullptr;
 static char const *const QtNativeInputConnectionClassName = "org/qtproject/qt/android/QtNativeInputConnection";
 static char const *const QtExtractedTextClassName = "org/qtproject/qt/android/QtExtractedText";
 static jclass m_extractedTextClass = 0;
diff --git a/src/plugins/platforms/directfb/main.cpp b/src/plugins/platforms/directfb/main.cpp
index de84827777..85e7f08917 100644
--- a/src/plugins/platforms/directfb/main.cpp
+++ b/src/plugins/platforms/directfb/main.cpp
@@ -64,7 +64,7 @@ public:
 QPlatformIntegration * QDirectFbIntegrationPlugin::create(const QString& system, const QStringList& paramList)
 {
     Q_UNUSED(paramList);
-    QDirectFbIntegration *integration = 0;
+    QDirectFbIntegration *integration = nullptr;
 
     if (!system.compare(QLatin1String("directfb"), Qt::CaseInsensitive))
         integration = new QDirectFbIntegration;
diff --git a/src/plugins/platforms/directfb/qdirectfb_egl.cpp b/src/plugins/platforms/directfb/qdirectfb_egl.cpp
index 95e6093fab..f38ad8f306 100644
--- a/src/plugins/platforms/directfb/qdirectfb_egl.cpp
+++ b/src/plugins/platforms/directfb/qdirectfb_egl.cpp
@@ -58,7 +58,7 @@ QT_BEGIN_NAMESPACE
 extern QDirectFBEGLHooks platform_hook;
 static QDirectFBEGLHooks *hooks = &platform_hook;
 #else
-static QDirectFBEGLHooks *hooks = 0;
+static QDirectFBEGLHooks *hooks = nullptr;
 #endif
 
 /**
diff --git a/src/plugins/platforms/directfb/qdirectfbconvenience.cpp b/src/plugins/platforms/directfb/qdirectfbconvenience.cpp
index c67a76f989..460596a18c 100644
--- a/src/plugins/platforms/directfb/qdirectfbconvenience.cpp
+++ b/src/plugins/platforms/directfb/qdirectfbconvenience.cpp
@@ -50,7 +50,7 @@ QT_BEGIN_NAMESPACE
 
 IDirectFB *QDirectFbConvenience::dfbInterface()
 {
-    static IDirectFB *dfb = 0;
+    static IDirectFB *dfb = nullptr;
     if (!dfb) {
         DFBResult result = DirectFBCreate(&dfb);
         if (result != DFB_OK) {
@@ -247,7 +247,7 @@ QEvent::Type QDirectFbConvenience::eventType(DFBWindowEventType type)
         return QEvent::None;
     }
 }
-QDirectFbKeyMap *QDirectFbConvenience::dfbKeymap = 0;
+QDirectFbKeyMap *QDirectFbConvenience::dfbKeymap = nullptr;
 QDirectFbKeyMap *QDirectFbConvenience::keyMap()
 {
     if (!dfbKeymap)
diff --git a/src/plugins/platforms/directfb/qdirectfbconvenience.h b/src/plugins/platforms/directfb/qdirectfbconvenience.h
index 19fc068307..dd10f6bc85 100644
--- a/src/plugins/platforms/directfb/qdirectfbconvenience.h
+++ b/src/plugins/platforms/directfb/qdirectfbconvenience.h
@@ -98,13 +98,13 @@ template <typename T>
 class QDirectFBPointer : public QScopedPointer<T, QDirectFBInterfaceCleanupHandler<T> >
 {
 public:
-    QDirectFBPointer(T *t = 0)
+    QDirectFBPointer(T *t = nullptr)
         : QScopedPointer<T, QDirectFBInterfaceCleanupHandler<T> >(t)
     {}
 
     T** outPtr()
     {
-        this->reset(0);
+        this->reset(nullptr);
         return &this->d;
     }
 };
diff --git a/src/plugins/platforms/integrity/qintegrityhidmanager.h b/src/plugins/platforms/integrity/qintegrityhidmanager.h
index c8780b2dc2..1e421328c2 100644
--- a/src/plugins/platforms/integrity/qintegrityhidmanager.h
+++ b/src/plugins/platforms/integrity/qintegrityhidmanager.h
@@ -52,7 +52,7 @@ class QIntegrityHIDManager : public QThread
 {
     Q_OBJECT
 public:
-    QIntegrityHIDManager(const QString &key, const QString &specification, QObject *parent = 0);
+    QIntegrityHIDManager(const QString &key, const QString &specification, QObject *parent = nullptr);
     ~QIntegrityHIDManager();
 
     void run(void);
diff --git a/src/plugins/platforms/ios/optional/nsphotolibrarysupport/plugin.mm b/src/plugins/platforms/ios/optional/nsphotolibrarysupport/plugin.mm
index 8b372b8749..2a3d8c603e 100644
--- a/src/plugins/platforms/ios/optional/nsphotolibrarysupport/plugin.mm
+++ b/src/plugins/platforms/ios/optional/nsphotolibrarysupport/plugin.mm
@@ -52,7 +52,7 @@ class QIosOptionalPlugin_NSPhotoLibrary : public QObject, QIosOptionalPluginInte
     Q_INTERFACES(QIosOptionalPluginInterface)
 
 public:
-    explicit QIosOptionalPlugin_NSPhotoLibrary(QObject* = 0) {};
+    explicit QIosOptionalPlugin_NSPhotoLibrary(QObject * = nullptr) {};
     ~QIosOptionalPlugin_NSPhotoLibrary() {}
 
     UIViewController* createImagePickerController(QIOSFileDialog *fileDialog) const override
diff --git a/src/plugins/platforms/ios/optional/nsphotolibrarysupport/qiosfileengineassetslibrary.mm b/src/plugins/platforms/ios/optional/nsphotolibrarysupport/qiosfileengineassetslibrary.mm
index c5244a51ad..01524a00e8 100644
--- a/src/plugins/platforms/ios/optional/nsphotolibrarysupport/qiosfileengineassetslibrary.mm
+++ b/src/plugins/platforms/ios/optional/nsphotolibrarysupport/qiosfileengineassetslibrary.mm
@@ -54,7 +54,7 @@ static QThreadStorage<QString> g_iteratorCurrentUrl;
 static QThreadStorage<QPointer<QIOSAssetData> > g_assetDataCache;
 
 static const int kBufferSize = 10;
-static ALAsset *kNoAsset = 0;
+static ALAsset *kNoAsset = nullptr;
 
 static bool ensureAuthorizationDialogNotBlocked()
 {
@@ -366,7 +366,7 @@ bool QIOSFileEngineAssetsLibrary::close()
         // Delete later, so that we can reuse the asset if a QFile is
         // opened with the same path during the same event loop cycle.
         m_data->deleteLater();
-        m_data = 0;
+        m_data = nullptr;
     }
     return true;
 }
@@ -410,7 +410,7 @@ qint64 QIOSFileEngineAssetsLibrary::read(char *data, qint64 maxlen)
     if (!bytesRead)
         return 0;
 
-    NSError *error = 0;
+    NSError *error = nullptr;
     [[asset defaultRepresentation] getBytes:(uint8_t *)data fromOffset:m_offset length:bytesRead error:&error];
 
     if (error) {
diff --git a/src/plugins/platforms/ios/qioseventdispatcher.h b/src/plugins/platforms/ios/qioseventdispatcher.h
index 1f4c78dc74..cdbaa0931d 100644
--- a/src/plugins/platforms/ios/qioseventdispatcher.h
+++ b/src/plugins/platforms/ios/qioseventdispatcher.h
@@ -53,7 +53,7 @@ public:
     bool processPostedEvents() override;
 
 protected:
-    explicit QIOSEventDispatcher(QObject *parent = 0);
+    explicit QIOSEventDispatcher(QObject *parent = nullptr);
 };
 
 class QIOSJumpingEventDispatcher : public QIOSEventDispatcher
@@ -61,7 +61,7 @@ class QIOSJumpingEventDispatcher : public QIOSEventDispatcher
     Q_OBJECT
 
 public:
-    QIOSJumpingEventDispatcher(QObject *parent = 0);
+    QIOSJumpingEventDispatcher(QObject *parent = nullptr);
     bool processEvents(QEventLoop::ProcessEventsFlags flags) override;
 
     // Public since we can't friend Objective-C methods
@@ -76,4 +76,4 @@ private:
 
 QT_END_NAMESPACE
 
-#endif // QIOSEVENTDISPATCHER_H
\ No newline at end of file
+#endif // QIOSEVENTDISPATCHER_H
diff --git a/src/plugins/platforms/ios/qiosglobal.mm b/src/plugins/platforms/ios/qiosglobal.mm
index a523d1be45..c0428dacb9 100644
--- a/src/plugins/platforms/ios/qiosglobal.mm
+++ b/src/plugins/platforms/ios/qiosglobal.mm
@@ -185,7 +185,7 @@ FirstResponderCandidate::FirstResponderCandidate(UIResponder *responder)
 {
 }
 
-UIResponder *FirstResponderCandidate::s_firstResponderCandidate = 0;
+UIResponder *FirstResponderCandidate::s_firstResponderCandidate = nullptr;
 
 QT_END_NAMESPACE
 
diff --git a/src/plugins/platforms/ios/qiosinputcontext.h b/src/plugins/platforms/ios/qiosinputcontext.h
index c59c5328af..36421a57c3 100644
--- a/src/plugins/platforms/ios/qiosinputcontext.h
+++ b/src/plugins/platforms/ios/qiosinputcontext.h
@@ -111,7 +111,7 @@ public:
     void scrollToCursor();
     void scroll(int y);
 
-    void updateKeyboardState(NSNotification *notification = 0);
+    void updateKeyboardState(NSNotification *notification = nullptr);
 
     const ImeState &imeState() { return m_imeState; }
     const KeyboardState &keyboardState() { return m_keyboardState; }
diff --git a/src/plugins/platforms/ios/qiosmenu.mm b/src/plugins/platforms/ios/qiosmenu.mm
index 74a77de757..737d7798ab 100644
--- a/src/plugins/platforms/ios/qiosmenu.mm
+++ b/src/plugins/platforms/ios/qiosmenu.mm
@@ -54,7 +54,7 @@
 // m_currentMenu points to the currently visible menu.
 // Only one menu will be visible at a time, and if a second menu
 // is shown on top of a first, the first one will be told to hide.
-QIOSMenu *QIOSMenu::m_currentMenu = 0;
+QIOSMenu *QIOSMenu::m_currentMenu = nullptr;
 
 // -------------------------------------------------------------------------
 
@@ -441,7 +441,7 @@ void QIOSMenu::dismiss()
         break;
     }
 
-    m_currentMenu = 0;
+    m_currentMenu = nullptr;
     m_visible = false;
 }
 
@@ -458,13 +458,13 @@ void QIOSMenu::toggleShowUsingUIMenuController(bool show)
         Q_ASSERT(m_menuController);
         [[UIMenuController sharedMenuController] setMenuVisible:NO animated:YES];
         [m_menuController release];
-        m_menuController = 0;
+        m_menuController = nullptr;
     }
 }
 
 void QIOSMenu::toggleShowUsingUIPickerView(bool show)
 {
-    static QObject *focusObjectWithPickerView = 0;
+    static QObject *focusObjectWithPickerView = nullptr;
 
     if (show) {
         Q_ASSERT(!m_pickerView);
@@ -477,12 +477,12 @@ void QIOSMenu::toggleShowUsingUIPickerView(bool show)
     } else {
         Q_ASSERT(focusObjectWithPickerView);
         focusObjectWithPickerView->removeEventFilter(this);
-        focusObjectWithPickerView = 0;
+        focusObjectWithPickerView = nullptr;
 
         Q_ASSERT(m_pickerView);
         [m_pickerView listenForKeyboardWillHideNotification:NO];
         [m_pickerView release];
-        m_pickerView = 0;
+        m_pickerView = nullptr;
 
         qApp->inputMethod()->update(Qt::ImEnabled | Qt::ImPlatformData);
     }
diff --git a/src/plugins/platforms/qnx/qqnxabstractnavigator.h b/src/plugins/platforms/qnx/qqnxabstractnavigator.h
index 24e28dae96..abacf80f54 100644
--- a/src/plugins/platforms/qnx/qqnxabstractnavigator.h
+++ b/src/plugins/platforms/qnx/qqnxabstractnavigator.h
@@ -50,7 +50,7 @@ class QQnxAbstractNavigator : public QObject
 {
     Q_OBJECT
 public:
-    explicit QQnxAbstractNavigator(QObject *parent = 0);
+    explicit QQnxAbstractNavigator(QObject *parent = nullptr);
     ~QQnxAbstractNavigator();
 
     bool invokeUrl(const QUrl &url);
diff --git a/src/plugins/platforms/qnx/qqnxabstractvirtualkeyboard.h b/src/plugins/platforms/qnx/qqnxabstractvirtualkeyboard.h
index 24be03b46c..92f6308487 100644
--- a/src/plugins/platforms/qnx/qqnxabstractvirtualkeyboard.h
+++ b/src/plugins/platforms/qnx/qqnxabstractvirtualkeyboard.h
@@ -64,7 +64,7 @@ public:
     enum KeyboardMode { Default, Url, Email, Web, NumPunc, Number, Symbol, Phone, Pin, Password, Alphanumeric };
     enum EnterKeyType { DefaultReturn, Connect, Done, Go, Join, Next, Search, Send, Submit };
 
-    explicit QQnxAbstractVirtualKeyboard(QObject *parent = 0);
+    explicit QQnxAbstractVirtualKeyboard(QObject *parent = nullptr);
 
     virtual bool showKeyboard() = 0;
     virtual bool hideKeyboard() = 0;
diff --git a/src/plugins/platforms/qnx/qqnxbuffer.cpp b/src/plugins/platforms/qnx/qqnxbuffer.cpp
index cd05a679b1..b02a989ea8 100644
--- a/src/plugins/platforms/qnx/qqnxbuffer.cpp
+++ b/src/plugins/platforms/qnx/qqnxbuffer.cpp
@@ -77,7 +77,7 @@ QQnxBuffer::QQnxBuffer(screen_buffer_t buffer)
 
     // Get access to buffer's data
     errno = 0;
-    uchar *dataPtr = 0;
+    uchar *dataPtr = nullptr;
     Q_SCREEN_CRITICALERROR(
             screen_get_buffer_property_pv(buffer, SCREEN_PROPERTY_POINTER, (void **)&dataPtr),
             "Failed to query buffer pointer");
diff --git a/src/plugins/platforms/qnx/qqnxbuffer.h b/src/plugins/platforms/qnx/qqnxbuffer.h
index 9ee0d5d60c..4b8adb20db 100644
--- a/src/plugins/platforms/qnx/qqnxbuffer.h
+++ b/src/plugins/platforms/qnx/qqnxbuffer.h
@@ -55,8 +55,8 @@ public:
     virtual ~QQnxBuffer();
 
     screen_buffer_t nativeBuffer() const { return m_buffer; }
-    const QImage *image() const { return (m_buffer != 0) ? &m_image : 0; }
-    QImage *image() { return (m_buffer != 0) ? &m_image : 0; }
+    const QImage *image() const { return (m_buffer != nullptr) ? &m_image : nullptr; }
+    QImage *image() { return (m_buffer != nullptr) ? &m_image : nullptr; }
 
     QRect rect() const { return m_image.rect(); }
 
diff --git a/src/plugins/platforms/qnx/qqnxbuttoneventnotifier.h b/src/plugins/platforms/qnx/qqnxbuttoneventnotifier.h
index aa2c118b3a..7cc67f2459 100644
--- a/src/plugins/platforms/qnx/qqnxbuttoneventnotifier.h
+++ b/src/plugins/platforms/qnx/qqnxbuttoneventnotifier.h
@@ -64,7 +64,7 @@ public:
         ButtonDown
     };
 
-    explicit QQnxButtonEventNotifier(QObject *parent = 0);
+    explicit QQnxButtonEventNotifier(QObject *parent = nullptr);
     ~QQnxButtonEventNotifier();
 
 public Q_SLOTS:
diff --git a/src/plugins/platforms/qnx/qqnxinputcontext_imf.cpp b/src/plugins/platforms/qnx/qqnxinputcontext_imf.cpp
index ce3a445d7c..79f6273e9f 100644
--- a/src/plugins/platforms/qnx/qqnxinputcontext_imf.cpp
+++ b/src/plugins/platforms/qnx/qqnxinputcontext_imf.cpp
@@ -76,8 +76,8 @@
 static QQnxInputContext *sInputContextInstance;
 static QColor sSelectedColor(0,0xb8,0,85);
 
-static const input_session_t *sSpellCheckSession = 0;
-static const input_session_t *sInputSession = 0;
+static const input_session_t *sSpellCheckSession = nullptr;
+static const input_session_t *sInputSession = nullptr;
 static bool isSessionOkay(input_session_t *ic)
 {
     return ic !=0 && sInputSession != 0 && ic->component_id == sInputSession->component_id;
@@ -515,13 +515,13 @@ static spannable_string_t *toSpannableString(const QString &text)
 }
 
 
-static const input_session_t *(*p_ictrl_open_session)(connection_interface_t *) = 0;
-static void (*p_ictrl_close_session)(input_session_t *) = 0;
-static int32_t (*p_ictrl_dispatch_event)(event_t*) = 0;
-static int32_t (*p_imf_client_init)() = 0;
-static void (*p_imf_client_disconnect)() = 0;
-static int32_t (*p_vkb_init_selection_service)() = 0;
-static int32_t (*p_ictrl_get_num_active_sessions)() = 0;
+static const input_session_t *(*p_ictrl_open_session)(connection_interface_t *) = nullptr;
+static void (*p_ictrl_close_session)(input_session_t *) = nullptr;
+static int32_t (*p_ictrl_dispatch_event)(event_t*) = nullptr;
+static int32_t (*p_imf_client_init)() = nullptr;
+static void (*p_imf_client_disconnect)() = nullptr;
+static int32_t (*p_vkb_init_selection_service)() = nullptr;
+static int32_t (*p_ictrl_get_num_active_sessions)() = nullptr;
 static bool s_imfInitFailed = false;
 
 static bool imfAvailable()
@@ -602,7 +602,7 @@ QQnxInputContext::~QQnxInputContext()
     qInputContextDebug();
 
     Q_ASSERT(sInputContextInstance == this);
-    sInputContextInstance = 0;
+    sInputContextInstance = nullptr;
 
     if (!imfAvailable())
         return;
@@ -735,7 +735,7 @@ void QQnxInputContext::closeSession()
 
     if (sInputSession) {
         p_ictrl_close_session((input_session_t *)sInputSession);
-        sInputSession = 0;
+        sInputSession = nullptr;
     }
     // These are likely already in the right state but this depends on the text control
     // having called reset or commit.  So, just in case, set them to proper values.
diff --git a/src/plugins/platforms/qnx/qqnxnavigatoreventhandler.h b/src/plugins/platforms/qnx/qqnxnavigatoreventhandler.h
index 3e10052459..6bedfaf963 100644
--- a/src/plugins/platforms/qnx/qqnxnavigatoreventhandler.h
+++ b/src/plugins/platforms/qnx/qqnxnavigatoreventhandler.h
@@ -48,7 +48,7 @@ class QQnxNavigatorEventHandler : public QObject
 {
     Q_OBJECT
 public:
-    explicit QQnxNavigatorEventHandler(QObject *parent = 0);
+    explicit QQnxNavigatorEventHandler(QObject *parent = nullptr);
 
     bool handleOrientationCheck(int angle);
     void handleOrientationChange(int angle);
diff --git a/src/plugins/platforms/qnx/qqnxnavigatoreventnotifier.h b/src/plugins/platforms/qnx/qqnxnavigatoreventnotifier.h
index 17c31c096c..a761faea1c 100644
--- a/src/plugins/platforms/qnx/qqnxnavigatoreventnotifier.h
+++ b/src/plugins/platforms/qnx/qqnxnavigatoreventnotifier.h
@@ -51,7 +51,7 @@ class QQnxNavigatorEventNotifier : public QObject
 {
     Q_OBJECT
 public:
-    explicit QQnxNavigatorEventNotifier(QQnxNavigatorEventHandler *eventHandler, QObject *parent = 0);
+    explicit QQnxNavigatorEventNotifier(QQnxNavigatorEventHandler *eventHandler, QObject *parent = nullptr);
     ~QQnxNavigatorEventNotifier();
 
 public Q_SLOTS:
diff --git a/src/plugins/platforms/qnx/qqnxnavigatorpps.h b/src/plugins/platforms/qnx/qqnxnavigatorpps.h
index 3c818f51a6..c58903b6b6 100644
--- a/src/plugins/platforms/qnx/qqnxnavigatorpps.h
+++ b/src/plugins/platforms/qnx/qqnxnavigatorpps.h
@@ -50,7 +50,7 @@ class QQnxNavigatorPps : public QQnxAbstractNavigator
 {
     Q_OBJECT
 public:
-    explicit QQnxNavigatorPps(QObject *parent = 0);
+    explicit QQnxNavigatorPps(QObject *parent = nullptr);
     ~QQnxNavigatorPps();
 
 protected:
diff --git a/src/plugins/platforms/qnx/qqnxrasterbackingstore.cpp b/src/plugins/platforms/qnx/qqnxrasterbackingstore.cpp
index e70092b97e..fe68927fda 100644
--- a/src/plugins/platforms/qnx/qqnxrasterbackingstore.cpp
+++ b/src/plugins/platforms/qnx/qqnxrasterbackingstore.cpp
@@ -89,7 +89,7 @@ void QQnxRasterBackingStore::flush(QWindow *window, const QRegion &region, const
     if (!m_needsPosting)
         return;
 
-    QQnxWindow *targetWindow = 0;
+    QQnxWindow *targetWindow = nullptr;
     if (window)
         targetWindow = static_cast<QQnxWindow *>(window->handle());
 
diff --git a/src/plugins/platforms/qnx/qqnxwindow.cpp b/src/plugins/platforms/qnx/qqnxwindow.cpp
index 22a00d3d40..9d3b921c44 100644
--- a/src/plugins/platforms/qnx/qqnxwindow.cpp
+++ b/src/plugins/platforms/qnx/qqnxwindow.cpp
@@ -566,7 +566,7 @@ void QQnxWindow::removeFromParent()
         if (Q_UNLIKELY(!m_parentWindow->m_childWindows.removeAll(this)))
             qFatal("QQnxWindow: Window Hierarchy broken; window has parent, but parent hasn't got child.");
         else
-            m_parentWindow = 0;
+            m_parentWindow = nullptr;
     } else if (m_screen) {
         m_screen->removeWindow(this);
     }
@@ -634,7 +634,7 @@ void QQnxWindow::lower()
 
 void QQnxWindow::requestActivateWindow()
 {
-    QQnxWindow *focusWindow = 0;
+    QQnxWindow *focusWindow = nullptr;
     if (QGuiApplication::focusWindow())
         focusWindow = static_cast<QQnxWindow*>(QGuiApplication::focusWindow()->handle());
 
@@ -664,7 +664,7 @@ void QQnxWindow::requestActivateWindow()
                   platformScreen->rootWindow()->m_windowGroupName == currentWindow->m_parentGroupName) {
                 currentWindow = platformScreen->rootWindow();
             } else {
-                currentWindow = 0;
+                currentWindow = nullptr;
             }
         }
 
diff --git a/src/plugins/platforms/wasm/qwasmcompositor.cpp b/src/plugins/platforms/wasm/qwasmcompositor.cpp
index 72fccd4a2b..9a16ae7719 100644
--- a/src/plugins/platforms/wasm/qwasmcompositor.cpp
+++ b/src/plugins/platforms/wasm/qwasmcompositor.cpp
@@ -454,7 +454,7 @@ void QWasmCompositor::drawFrameWindow(QWasmFrameOptions options, QPainter *paint
     const QColor &c2 = options.palette.shadow().color();
     const QColor &c3 = options.palette.midlight().color();
     const QColor &c4 = options.palette.dark().color();
-    const QBrush *fill = 0;
+    const QBrush *fill = nullptr;
 
     const qreal devicePixelRatio = painter->device()->devicePixelRatio();
     if (!qFuzzyCompare(devicePixelRatio, qreal(1))) {
diff --git a/src/plugins/platforms/xcb/nativepainting/qcolormap_x11.cpp b/src/plugins/platforms/xcb/nativepainting/qcolormap_x11.cpp
index b4a9d64eb8..0eb522e1ed 100644
--- a/src/plugins/platforms/xcb/nativepainting/qcolormap_x11.cpp
+++ b/src/plugins/platforms/xcb/nativepainting/qcolormap_x11.cpp
@@ -320,7 +320,7 @@ static void init_direct(QXcbColormapPrivate *d, bool ownColormap)
     XStoreColors(X11->display, d->colormap, colorTable.data(), colorTable.count());
 }
 
-static QXcbColormap **cmaps = 0;
+static QXcbColormap **cmaps = nullptr;
 
 void QXcbColormap::initialize()
 {
@@ -343,7 +343,7 @@ void QXcbColormap::initialize()
         d->visual = DefaultVisual(display, i);
         d->defaultVisual = true;
 
-        Visual *argbVisual = 0;
+        Visual *argbVisual = nullptr;
 
         if (X11->visual && i == DefaultScreen(display)) {
             // only use the outside colormap on the default screen
@@ -356,7 +356,7 @@ void QXcbColormap::initialize()
             d->visual = find_visual(display, i, X11->visual_class, X11->visual_id,
                                     &d->depth, &d->defaultVisual);
         } else if (!X11->custom_cmap) {
-            XStandardColormap *stdcmap = 0;
+            XStandardColormap *stdcmap = nullptr;
             int ncmaps = 0;
 
 #if QT_CONFIG(xrender)
diff --git a/src/plugins/platforms/xcb/nativepainting/qpixmap_x11.cpp b/src/plugins/platforms/xcb/nativepainting/qpixmap_x11.cpp
index d55a49768c..bf45b409c5 100644
--- a/src/plugins/platforms/xcb/nativepainting/qpixmap_x11.cpp
+++ b/src/plugins/platforms/xcb/nativepainting/qpixmap_x11.cpp
@@ -282,9 +282,9 @@ static uint n_bits(uint v)
     return i;
 }
 
-static uint *red_scale_table   = 0;
-static uint *green_scale_table = 0;
-static uint *blue_scale_table  = 0;
+static uint *red_scale_table   = nullptr;
+static uint *green_scale_table = nullptr;
+static uint *blue_scale_table  = nullptr;
 
 static void cleanup_scale_tables()
 {
@@ -546,10 +546,10 @@ void QX11PlatformPixmap::fromImage(const QImage &img, Qt::ImageConversionFlags f
 
     Display *dpy   = xinfo.display();
     Visual *visual = (Visual *)xinfo.visual();
-    XImage *xi = 0;
+    XImage *xi = nullptr;
     bool    trucol = (visual->c_class >= TrueColor);
     size_t  nbytes = image.sizeInBytes();
-    uchar  *newbits= 0;
+    uchar  *newbits= nullptr;
 
 #if QT_CONFIG(xrender)
     if (alphaCheck.hasXRenderAndAlpha()) {
diff --git a/src/plugins/platforms/xcb/nativepainting/qtessellator.cpp b/src/plugins/platforms/xcb/nativepainting/qtessellator.cpp
index 1afa00cfc9..388f5aba76 100644
--- a/src/plugins/platforms/xcb/nativepainting/qtessellator.cpp
+++ b/src/plugins/platforms/xcb/nativepainting/qtessellator.cpp
@@ -725,7 +725,7 @@ void QTessellatorPrivate::cancelCoincidingEdges()
 {
     Vertex **vv = vertices.sorted;
 
-    QCoincidingEdge *tl = 0;
+    QCoincidingEdge *tl = nullptr;
     int tlSize = 0;
 
     for (int i = 0; i < vertices.nPoints - 1; ++i) {
diff --git a/src/plugins/platforms/xcb/qxcbdrag.cpp b/src/plugins/platforms/xcb/qxcbdrag.cpp
index 401863790c..d2143ce953 100644
--- a/src/plugins/platforms/xcb/qxcbdrag.cpp
+++ b/src/plugins/platforms/xcb/qxcbdrag.cpp
@@ -95,9 +95,9 @@ static xcb_window_t xdndProxy(QXcbConnection *c, xcb_window_t w)
     if (reply && reply->type == XCB_ATOM_WINDOW) {
         xcb_window_t p = *((xcb_window_t *)xcb_get_property_value(reply.get()));
         if (proxy != p)
-            proxy = 0;
+            proxy = XCB_NONE;
     } else {
-        proxy = 0;
+        proxy = XCB_NONE;
     }
 
     return proxy;
@@ -690,7 +690,7 @@ int QXcbDrag::findTransactionByTime(xcb_timestamp_t timestamp)
 
 #if 0
 // for embedding only
-static QWidget* current_embedding_widget  = 0;
+static QWidget* current_embedding_widget  = nullptr;
 static xcb_client_message_event_t last_enter_event;
 
 
diff --git a/src/plugins/sqldrivers/db2/qsql_db2.cpp b/src/plugins/sqldrivers/db2/qsql_db2.cpp
index e644a556e6..e3cfa0ae15 100644
--- a/src/plugins/sqldrivers/db2/qsql_db2.cpp
+++ b/src/plugins/sqldrivers/db2/qsql_db2.cpp
@@ -1052,7 +1052,7 @@ QVariant QDB2Result::data(int field)
         return *d->valueCache[field];
 
 
-    QVariant* v = 0;
+    QVariant *v = nullptr;
     switch (info.metaType().id()) {
         case QVariant::LongLong:
             v = new QVariant((qint64) qGetBigIntData(d->hStmt, field, isNull));
diff --git a/src/plugins/sqldrivers/db2/qsql_db2_p.h b/src/plugins/sqldrivers/db2/qsql_db2_p.h
index 79ae54ab2d..abe65c4208 100644
--- a/src/plugins/sqldrivers/db2/qsql_db2_p.h
+++ b/src/plugins/sqldrivers/db2/qsql_db2_p.h
@@ -72,8 +72,8 @@ class Q_EXPORT_SQLDRIVER_DB2 QDB2Driver : public QSqlDriver
     friend class QDB2ResultPrivate;
 
 public:
-    explicit QDB2Driver(QObject* parent = 0);
-    QDB2Driver(Qt::HANDLE env, Qt::HANDLE con, QObject* parent = 0);
+    explicit QDB2Driver(QObject *parent = nullptr);
+    QDB2Driver(Qt::HANDLE env, Qt::HANDLE con, QObject *parent = nullptr);
     ~QDB2Driver();
     bool hasFeature(DriverFeature) const override;
     void close() override;
diff --git a/src/plugins/sqldrivers/ibase/qsql_ibase.cpp b/src/plugins/sqldrivers/ibase/qsql_ibase.cpp
index 6b7ee8f133..7be2df6dd9 100644
--- a/src/plugins/sqldrivers/ibase/qsql_ibase.cpp
+++ b/src/plugins/sqldrivers/ibase/qsql_ibase.cpp
@@ -487,7 +487,7 @@ QVariant QIBaseResultPrivate::fetchBlob(ISC_QUAD *bId)
 }
 
 template<typename T>
-static QList<QVariant> toList(char** buf, int count, T* = 0)
+static QList<QVariant> toList(char** buf, int count, T* = nullptr)
 {
     QList<QVariant> res;
     for (int i = 0; i < count; ++i) {
@@ -624,7 +624,7 @@ QVariant QIBaseResultPrivate::fetchArray(int pos, ISC_QUAD *arr)
 }
 
 template<typename T>
-static char* fillList(char *buffer, const QList<QVariant> &list, T* = 0)
+static char* fillList(char *buffer, const QList<QVariant> &list, T* = nullptr)
 {
     for (int i = 0; i < list.size(); ++i) {
         T val;
diff --git a/src/plugins/sqldrivers/ibase/qsql_ibase_p.h b/src/plugins/sqldrivers/ibase/qsql_ibase_p.h
index e7c908cf2b..9109c2b40f 100644
--- a/src/plugins/sqldrivers/ibase/qsql_ibase_p.h
+++ b/src/plugins/sqldrivers/ibase/qsql_ibase_p.h
@@ -73,8 +73,8 @@ class Q_EXPORT_SQLDRIVER_IBASE QIBaseDriver : public QSqlDriver
     Q_DECLARE_PRIVATE(QIBaseDriver)
     Q_OBJECT
 public:
-    explicit QIBaseDriver(QObject *parent = 0);
-    explicit QIBaseDriver(isc_db_handle connection, QObject *parent = 0);
+    explicit QIBaseDriver(QObject *parent = nullptr);
+    explicit QIBaseDriver(isc_db_handle connection, QObject *parent = nullptr);
     virtual ~QIBaseDriver();
     bool hasFeature(DriverFeature f) const override;
     bool open(const QString &db,
diff --git a/src/plugins/sqldrivers/oci/qsql_oci.cpp b/src/plugins/sqldrivers/oci/qsql_oci.cpp
index 4edafd1029..5bf9400180 100644
--- a/src/plugins/sqldrivers/oci/qsql_oci.cpp
+++ b/src/plugins/sqldrivers/oci/qsql_oci.cpp
@@ -511,7 +511,7 @@ int QOCIResultPrivate::bindValues(QVariantList &values, IndicatorArray &indicato
             values[i].detach();
         const QVariant &val = values.at(i);
 
-        OCIBind * hbnd = 0; // Oracle handles these automatically
+        OCIBind * hbnd = nullptr; // Oracle handles these automatically
         sb2 *indPtr = &indicators[i];
         *indPtr = val.isNull() ? -1 : 0;
 
@@ -897,10 +897,10 @@ QOCICols::QOCICols(int size, QOCIResultPrivate* dp)
     : fieldInf(size), d(dp)
 {
     ub4 dataSize = 0;
-    OCIDefine* dfn = 0;
+    OCIDefine *dfn = nullptr;
     int r;
 
-    OCIParam* param = 0;
+    OCIParam *param = nullptr;
     sb4 parmStatus = 0;
     ub4 count = 1;
     int idx = 0;
@@ -1184,7 +1184,7 @@ OraFieldInfo QOCICols::qMakeOraField(const QOCIResultPrivate* p, OCIParam* param
 {
     OraFieldInfo ofi;
     ub2 colType(0);
-    text *colName = 0;
+    text *colName = nullptr;
     ub4 colNameLen(0);
     sb1 colScale(0);
     ub2 colLength(0);
diff --git a/src/plugins/sqldrivers/oci/qsql_oci_p.h b/src/plugins/sqldrivers/oci/qsql_oci_p.h
index 295c131f1a..a3366abb77 100644
--- a/src/plugins/sqldrivers/oci/qsql_oci_p.h
+++ b/src/plugins/sqldrivers/oci/qsql_oci_p.h
@@ -75,8 +75,8 @@ class Q_EXPORT_SQLDRIVER_OCI QOCIDriver : public QSqlDriver
     friend class QOCIResultPrivate;
 
 public:
-    explicit QOCIDriver(QObject* parent = 0);
-    QOCIDriver(OCIEnv* env, OCISvcCtx* ctx, QObject* parent = 0);
+    explicit QOCIDriver(QObject *parent = nullptr);
+    QOCIDriver(OCIEnv *env, OCISvcCtx *ctx, QObject *parent = nullptr);
     ~QOCIDriver();
     bool hasFeature(DriverFeature f) const;
     bool open(const QString &db,
diff --git a/src/plugins/sqldrivers/odbc/qsql_odbc.cpp b/src/plugins/sqldrivers/odbc/qsql_odbc.cpp
index a58c782b60..5a00a000f7 100644
--- a/src/plugins/sqldrivers/odbc/qsql_odbc.cpp
+++ b/src/plugins/sqldrivers/odbc/qsql_odbc.cpp
@@ -227,7 +227,7 @@ void QODBCResultPrivate::updateStmtHandleState()
     disconnectCount = drv_d_func() ? drv_d_func()->disconnectCount : 0;
 }
 
-static QString qWarnODBCHandle(int handleType, SQLHANDLE handle, int *nativeCode = 0)
+static QString qWarnODBCHandle(int handleType, SQLHANDLE handle, int *nativeCode = nullptr)
 {
     SQLINTEGER nativeCode_ = 0;
     SQLSMALLINT msgLen = 0;
@@ -275,7 +275,7 @@ static QString qWarnODBCHandle(int handleType, SQLHANDLE handle, int *nativeCode
 }
 
 static QString qODBCWarn(const SQLHANDLE hStmt, const SQLHANDLE envHandle = 0,
-                         const SQLHANDLE pDbC = 0, int *nativeCode = 0)
+                         const SQLHANDLE pDbC = 0, int *nativeCode = nullptr)
 {
     QString result;
     if (envHandle)
@@ -299,12 +299,12 @@ static QString qODBCWarn(const SQLHANDLE hStmt, const SQLHANDLE envHandle = 0,
     return result;
 }
 
-static QString qODBCWarn(const QODBCResultPrivate* odbc, int *nativeCode = 0)
+static QString qODBCWarn(const QODBCResultPrivate* odbc, int *nativeCode = nullptr)
 {
     return qODBCWarn(odbc->hStmt, odbc->dpEnv(), odbc->dpDbc(), nativeCode);
 }
 
-static QString qODBCWarn(const QODBCDriverPrivate* odbc, int *nativeCode = 0)
+static QString qODBCWarn(const QODBCDriverPrivate* odbc, int *nativeCode = nullptr)
 {
     return qODBCWarn(0, odbc->hEnv, odbc->hDbc, nativeCode);
 }
diff --git a/src/plugins/styles/android/qandroidstyle.cpp b/src/plugins/styles/android/qandroidstyle.cpp
index 8036655b04..d19e249cb4 100644
--- a/src/plugins/styles/android/qandroidstyle.cpp
+++ b/src/plugins/styles/android/qandroidstyle.cpp
@@ -1193,7 +1193,7 @@ QSize QAndroidStyle::AndroidStateDrawable::sizeImage(const QStyleOption *opt) co
 
 const QAndroidStyle::AndroidDrawable * QAndroidStyle::AndroidStateDrawable::bestAndroidStateMatch(const QStyleOption *opt) const
 {
-    const AndroidDrawable *bestMatch = 0;
+    const AndroidDrawable *bestMatch = nullptr;
     if (!opt) {
         if (m_states.size())
             return m_states[0].second;
diff --git a/src/plugins/styles/android/qandroidstyle_p.h b/src/plugins/styles/android/qandroidstyle_p.h
index 5730bdfe2c..ca4b435046 100644
--- a/src/plugins/styles/android/qandroidstyle_p.h
+++ b/src/plugins/styles/android/qandroidstyle_p.h
@@ -257,10 +257,10 @@ public:
         virtual void drawControl(const QStyleOption *opt, QPainter *p, const QWidget *w);
         virtual QRect subElementRect(SubElement subElement,
                                      const QStyleOption *option,
-                                     const QWidget *widget = 0) const;
+                                     const QWidget *widget = nullptr) const;
         virtual QRect subControlRect(const QStyleOptionComplex *option,
                                      SubControl sc,
-                                     const QWidget *widget = 0) const;
+                                     const QWidget *widget = nullptr) const;
         virtual QSize sizeFromContents(const QStyleOption *opt,
                                        const QSize &contentsSize,
                                        const QWidget *w) const;
@@ -294,7 +294,7 @@ public:
         virtual void drawControl(const QStyleOption *option, QPainter *p, const QWidget *w);
         virtual QRect subElementRect(SubElement subElement,
                                      const QStyleOption *option,
-                                     const QWidget *widget = 0) const;
+                                     const QWidget *widget = nullptr) const;
 
         QSize sizeFromContents(const QStyleOption *opt,
                                const QSize &contentsSize,
@@ -315,7 +315,7 @@ public:
         QSize sizeFromContents(const QStyleOption *opt,
                                        const QSize &contentsSize, const QWidget *w) const;
         QRect subControlRect(const QStyleOptionComplex *option, SubControl sc,
-                                     const QWidget *widget = 0) const;
+                             const QWidget *widget = nullptr) const;
     private:
         AndroidDrawable *m_seekBarThumb;
     };
@@ -327,7 +327,7 @@ public:
         virtual ~AndroidSpinnerControl(){}
         virtual QRect subControlRect(const QStyleOptionComplex *option,
                                      SubControl sc,
-                                     const QWidget *widget = 0) const;
+                                     const QWidget *widget = nullptr) const;
     };
 
     typedef QList<AndroidItemStateInfo *> AndroidItemStateInfoList;
@@ -337,34 +337,34 @@ public:
     ~QAndroidStyle();
 
     virtual void drawPrimitive(PrimitiveElement pe, const QStyleOption *opt, QPainter *p,
-                               const QWidget *w = 0) const;
+                               const QWidget *w = nullptr) const;
 
     virtual void drawControl(QStyle::ControlElement element, const QStyleOption *opt, QPainter *p,
-                             const QWidget *w = 0) const;
+                             const QWidget *w = nullptr) const;
 
     virtual QRect subElementRect(SubElement subElement, const QStyleOption *option,
-                                 const QWidget *widget = 0) const;
+                                 const QWidget *widget = nullptr) const;
     virtual void drawComplexControl(ComplexControl cc, const QStyleOptionComplex *opt, QPainter *p,
-                                    const QWidget *widget = 0) const;
+                                    const QWidget *widget = nullptr) const;
     virtual SubControl hitTestComplexControl(ComplexControl cc, const QStyleOptionComplex *opt,
-                                             const QPoint &pt, const QWidget *widget = 0) const;
+                                             const QPoint &pt, const QWidget *widget = nullptr) const;
     virtual QRect subControlRect(ComplexControl cc, const QStyleOptionComplex *opt,
-                                 SubControl sc, const QWidget *widget = 0) const;
+                                 SubControl sc, const QWidget *widget = nullptr) const;
 
-    virtual int pixelMetric(PixelMetric metric, const QStyleOption *option = 0,
-                            const QWidget *widget = 0) const;
+    virtual int pixelMetric(PixelMetric metric, const QStyleOption *option = nullptr,
+                            const QWidget *widget = nullptr) const;
 
     virtual QSize sizeFromContents(ContentsType ct, const QStyleOption *opt,
-                                   const QSize &contentsSize, const QWidget *w = 0) const;
+                                   const QSize &contentsSize, const QWidget *w = nullptr) const;
 
-    virtual QPixmap standardPixmap(StandardPixmap standardPixmap, const QStyleOption *opt = 0,
-                                   const QWidget *widget = 0) const;
+    virtual QPixmap standardPixmap(StandardPixmap standardPixmap, const QStyleOption *opt = nullptr,
+                                   const QWidget *widget = nullptr) const;
 
     virtual QPixmap generatedIconPixmap(QIcon::Mode iconMode, const QPixmap &pixmap,
                                         const QStyleOption *opt) const;
 
-    int styleHint(StyleHint hint, const QStyleOption *option = 0, const QWidget *widget = 0,
-                  QStyleHintReturn *returnData = 0) const;
+    int styleHint(StyleHint hint, const QStyleOption *option = nullptr, const QWidget *widget = nullptr,
+                  QStyleHintReturn *returnData = nullptr) const;
 
     virtual QPalette standardPalette() const;
     void polish(QWidget *widget);
diff --git a/src/plugins/styles/mac/qmacstyle_mac.mm b/src/plugins/styles/mac/qmacstyle_mac.mm
index 904f94fc95..c0862001f4 100644
--- a/src/plugins/styles/mac/qmacstyle_mac.mm
+++ b/src/plugins/styles/mac/qmacstyle_mac.mm
@@ -1469,7 +1469,7 @@ QStyleHelper::WidgetSizePolicy QMacStylePrivate::aquaSizeConstrain(const QStyleO
     if (guess_size)
         ret = qt_aqua_guess_size(widg, large, small, mini);
 
-    QSize *sz = 0;
+    QSize *sz = nullptr;
     if (ret == QStyleHelper::SizeSmall)
         sz = &small;
     else if (ret == QStyleHelper::SizeLarge)
@@ -6489,7 +6489,7 @@ bool QMacStyle::event(QEvent *e)
 {
     Q_D(QMacStyle);
     if(e->type() == QEvent::FocusIn) {
-        QWidget *f = 0;
+        QWidget *f = nullptr;
         QWidget *focusWidget = QApplication::focusWidget();
 #if QT_CONFIG(graphicsview)
         if (QGraphicsView *graphicsView = qobject_cast<QGraphicsView *>(focusWidget)) {
diff --git a/src/plugins/styles/mac/qmacstyle_mac_p.h b/src/plugins/styles/mac/qmacstyle_mac_p.h
index 88f104cccf..d1d6bc6339 100644
--- a/src/plugins/styles/mac/qmacstyle_mac_p.h
+++ b/src/plugins/styles/mac/qmacstyle_mac_p.h
@@ -77,28 +77,28 @@ public:
     void polish(QPalette &pal);
 
     void drawPrimitive(PrimitiveElement pe, const QStyleOption *opt, QPainter *p,
-                       const QWidget *w = 0) const;
+                       const QWidget *w = nullptr) const;
     void drawControl(ControlElement element, const QStyleOption *opt, QPainter *p,
-                     const QWidget *w = 0) const;
-    QRect subElementRect(SubElement r, const QStyleOption *opt, const QWidget *widget = 0) const;
+                     const QWidget *w = nullptr) const;
+    QRect subElementRect(SubElement r, const QStyleOption *opt, const QWidget *widget = nullptr) const;
     void drawComplexControl(ComplexControl cc, const QStyleOptionComplex *opt, QPainter *p,
-                            const QWidget *w = 0) const;
+                            const QWidget *w = nullptr) const;
     SubControl hitTestComplexControl(ComplexControl cc, const QStyleOptionComplex *opt,
-                               const QPoint &pt, const QWidget *w = 0) const;
+                               const QPoint &pt, const QWidget *w = nullptr) const;
     QRect subControlRect(ComplexControl cc, const QStyleOptionComplex *opt, SubControl sc,
-                         const QWidget *w = 0) const;
+                         const QWidget *w = nullptr) const;
     QSize sizeFromContents(ContentsType ct, const QStyleOption *opt,
-                           const QSize &contentsSize, const QWidget *w = 0) const;
+                           const QSize &contentsSize, const QWidget *w = nullptr) const;
 
-    int pixelMetric(PixelMetric pm, const QStyleOption *opt = 0, const QWidget *widget = 0) const;
+    int pixelMetric(PixelMetric pm, const QStyleOption *opt = 0, const QWidget *widget = nullptr) const;
 
     QPalette standardPalette() const;
 
-    virtual int styleHint(StyleHint sh, const QStyleOption *opt = 0, const QWidget *w = 0,
-                          QStyleHintReturn *shret = 0) const;
+    virtual int styleHint(StyleHint sh, const QStyleOption *opt = 0, const QWidget *w = nullptr,
+                          QStyleHintReturn *shret = nullptr) const;
 
     QPixmap standardPixmap(StandardPixmap sp, const QStyleOption *opt,
-                           const QWidget *widget = 0) const;
+                           const QWidget *widget = nullptr) const;
 
     QPixmap generatedIconPixmap(QIcon::Mode iconMode, const QPixmap &pixmap,
                                 const QStyleOption *opt) const;
@@ -108,11 +108,11 @@ public:
 
     bool event(QEvent *e);
 
-    QIcon standardIcon(StandardPixmap standardIcon, const QStyleOption *opt = 0,
-                       const QWidget *widget = 0) const;
+    QIcon standardIcon(StandardPixmap standardIcon, const QStyleOption *opt = nullptr,
+                       const QWidget *widget = nullptr) const;
     int layoutSpacing(QSizePolicy::ControlType control1, QSizePolicy::ControlType control2,
-                      Qt::Orientation orientation, const QStyleOption *option = 0,
-                      const QWidget *widget = 0) const;
+                      Qt::Orientation orientation, const QStyleOption *option = nullptr,
+                      const QWidget *widget = nullptr) const;
 
 private:
     Q_DISABLE_COPY_MOVE(QMacStyle)
diff --git a/src/testlib/qappletestlogger_p.h b/src/testlib/qappletestlogger_p.h
index 62c6d95c5a..6075f9fccb 100644
--- a/src/testlib/qappletestlogger_p.h
+++ b/src/testlib/qappletestlogger_p.h
@@ -69,11 +69,11 @@ public:
     void leaveTestFunction() override;
 
     void addIncident(IncidentTypes type, const char *description,
-                     const char *file = 0, int line = 0) override;
+                     const char *file = nullptr, int line = 0) override;
     void addMessage(QtMsgType, const QMessageLogContext &,
             const QString &) override;
     void addMessage(MessageTypes type, const QString &message,
-                            const char *file = 0, int line = 0) override;
+                            const char *file = nullptr, int line = 0) override;
 
     void addBenchmarkResult(const QBenchmarkResult &result) override
     { Q_UNUSED(result); }
diff --git a/src/testlib/qxctestlogger.mm b/src/testlib/qxctestlogger.mm
index d9e56cf542..a40ee5e643 100644
--- a/src/testlib/qxctestlogger.mm
+++ b/src/testlib/qxctestlogger.mm
@@ -214,7 +214,7 @@ private:
 
 // ---------------------------------------------------------
 
-static XCTestSuiteRun *s_qtTestSuiteRun = 0;
+static XCTestSuiteRun *s_qtTestSuiteRun = nullptr;
 
 @implementation QtTestLibTests
 
diff --git a/src/testlib/qxctestlogger_p.h b/src/testlib/qxctestlogger_p.h
index 8baa5aa27f..bd844e28e4 100644
--- a/src/testlib/qxctestlogger_p.h
+++ b/src/testlib/qxctestlogger_p.h
@@ -74,10 +74,10 @@ public:
     void leaveTestFunction() override;
 
     void addIncident(IncidentTypes type, const char *description,
-        const char *file = 0, int line = 0) override;
+        const char *file = nullptr, int line = 0) override;
 
     void addMessage(MessageTypes type, const QString &message,
-        const char *file = 0, int line = 0) override;
+        const char *file = nullptr, int line = 0) override;
 
     void addBenchmarkResult(const QBenchmarkResult &result) override;
 
diff --git a/src/tools/moc/util/generate_keywords.cpp b/src/tools/moc/util/generate_keywords.cpp
index c2cfe37fab..28c5eeff38 100644
--- a/src/tools/moc/util/generate_keywords.cpp
+++ b/src/tools/moc/util/generate_keywords.cpp
@@ -301,7 +301,7 @@ struct State
 
 void newState(QList<State> &states, const char *token, const char *lexem, bool pre)
 {
-    const char * ident = 0;
+    const char *ident = nullptr;
     if (is_ident_start(*lexem))
         ident = pre?"PP_CHARACTER" : "CHARACTER";
     else if (*lexem == '#')
@@ -311,7 +311,7 @@ void newState(QList<State> &states, const char *token, const char *lexem, bool p
     while (*lexem) {
         int next = states[state].next[(int)*lexem];
         if (!next) {
-            const char * t = 0;
+            const char *t = nullptr;
             if (ident)
                 t = ident;
             else
@@ -324,7 +324,7 @@ void newState(QList<State> &states, const char *token, const char *lexem, bool p
         state = next;
         ++lexem;
         if (ident && !is_ident_char(*lexem))
-            ident = 0;
+            ident = nullptr;
     }
     states[state].token = token;
 }
diff --git a/src/tools/qlalr/examples/glsl/glsl-lex.l b/src/tools/qlalr/examples/glsl/glsl-lex.l
index 2a9618edf8..c92aad296b 100644
--- a/src/tools/qlalr/examples/glsl/glsl-lex.l
+++ b/src/tools/qlalr/examples/glsl/glsl-lex.l
@@ -142,7 +142,7 @@ icst ({dec}|0{oct}*|0[xX]{hex}+)
 "lowp" { return LOW_PRECISION; }
 
 #[ \t]+[0-9]+.* {
-  char *eptr = 0;
+  char *eptr = nullptr;
   context.line = (int) strtod(&yytext[1], &eptr);
   QString fn = QString::fromUtf8(eptr).trimmed();
   if (fn.length() > 2)
diff --git a/src/widgets/doc/snippets/code/doc_src_qt4-styles.cpp b/src/widgets/doc/snippets/code/doc_src_qt4-styles.cpp
index f550ee36ce..e288b66b86 100644
--- a/src/widgets/doc/snippets/code/doc_src_qt4-styles.cpp
+++ b/src/widgets/doc/snippets/code/doc_src_qt4-styles.cpp
@@ -88,5 +88,5 @@ void drawControl(ControlElement element,
 void drawControl(ControlElement element,
                  const QStyleOption *option,
                  QPainter *painter,
-                 const QWidget *widget = 0) const;
+                 const QWidget *widget = nullptr) const;
 //! [3]
diff --git a/src/widgets/doc/snippets/graphicssceneadditem/graphicssceneadditemsnippet.cpp b/src/widgets/doc/snippets/graphicssceneadditem/graphicssceneadditemsnippet.cpp
index 3d5c172dca..f928142e05 100644
--- a/src/widgets/doc/snippets/graphicssceneadditem/graphicssceneadditemsnippet.cpp
+++ b/src/widgets/doc/snippets/graphicssceneadditem/graphicssceneadditemsnippet.cpp
@@ -61,7 +61,7 @@ public:
 
     void drawItems(QPainter *painter, int numItems, QGraphicsItem *items[],
                    const QStyleOptionGraphicsItem options[],
-                   QWidget *widget = 0) override;
+                   QWidget *widget = nullptr) override;
 };
 
 //! [0]
diff --git a/src/widgets/doc/snippets/qlistview-dnd/model.h b/src/widgets/doc/snippets/qlistview-dnd/model.h
index 3d418dca14..3d723f9540 100644
--- a/src/widgets/doc/snippets/qlistview-dnd/model.h
+++ b/src/widgets/doc/snippets/qlistview-dnd/model.h
@@ -59,7 +59,7 @@ class DragDropListModel : public QStringListModel
     Q_OBJECT
 
 public:
-    DragDropListModel(const QStringList &strings, QObject *parent = 0);
+    DragDropListModel(const QStringList &strings, QObject *parent = nullptr);
 
     Qt::ItemFlags flags(const QModelIndex &index) const override;
 
diff --git a/src/widgets/doc/snippets/qstackedwidget/main.cpp b/src/widgets/doc/snippets/qstackedwidget/main.cpp
index c68a992332..6a0e78a40a 100644
--- a/src/widgets/doc/snippets/qstackedwidget/main.cpp
+++ b/src/widgets/doc/snippets/qstackedwidget/main.cpp
@@ -53,7 +53,7 @@
 class Widget : public QWidget
 {
 public:
-    Widget(QWidget *parent = 0);
+    Widget(QWidget *parent = nullptr);
 };
 
 Widget::Widget(QWidget *parent)
diff --git a/src/widgets/doc/snippets/qstyleoption/main.cpp b/src/widgets/doc/snippets/qstyleoption/main.cpp
index 529f88f1d9..7606efa1ae 100644
--- a/src/widgets/doc/snippets/qstyleoption/main.cpp
+++ b/src/widgets/doc/snippets/qstyleoption/main.cpp
@@ -54,7 +54,7 @@
 class MyPushButton : public QPushButton
 {
 public:
-    MyPushButton(QWidget *parent = 0);
+    MyPushButton(QWidget *parent = nullptr);
 
     void paintEvent(QPaintEvent *) override;
 };
diff --git a/src/widgets/doc/snippets/qstyleplugin/main.cpp b/src/widgets/doc/snippets/qstyleplugin/main.cpp
index 1c61581572..3a3a42be16 100644
--- a/src/widgets/doc/snippets/qstyleplugin/main.cpp
+++ b/src/widgets/doc/snippets/qstyleplugin/main.cpp
@@ -57,7 +57,7 @@ class MyStylePlugin : public QStylePlugin
     Q_OBJECT
     Q_PLUGIN_METADATA(IID "org.qt-project.Qt.QStyleFactoryInterface" FILE "mystyleplugin.json")
 public:
-    MyStylePlugin(QObject *parent = 0);
+    MyStylePlugin(QObject *parent = nullptr);
 
     QStyle *create(const QString &key) override;
 };
diff --git a/src/widgets/doc/snippets/reading-selections/window.h b/src/widgets/doc/snippets/reading-selections/window.h
index a3e6cd42b3..25bfac5e29 100644
--- a/src/widgets/doc/snippets/reading-selections/window.h
+++ b/src/widgets/doc/snippets/reading-selections/window.h
@@ -61,7 +61,7 @@ class MainWindow : public QMainWindow
 {
     Q_OBJECT
 public:
-    MainWindow(QWidget *parent = 0);
+    MainWindow(QWidget *parent = nullptr);
 
 private slots:
     void fillSelection();
diff --git a/src/widgets/doc/snippets/splitter/splitter.cpp b/src/widgets/doc/snippets/splitter/splitter.cpp
index 0a86f5f759..e77eaf90d5 100644
--- a/src/widgets/doc/snippets/splitter/splitter.cpp
+++ b/src/widgets/doc/snippets/splitter/splitter.cpp
@@ -56,7 +56,7 @@ void processSize(int)
 
 int main()
 {
-    QWidget *parent = 0;
+    QWidget *parent = nullptr;
 
 //! [0]
     QSplitter *splitter = new QSplitter(parent);
diff --git a/src/widgets/doc/snippets/splitterhandle/splitter.h b/src/widgets/doc/snippets/splitterhandle/splitter.h
index 8df7bc14a2..5788871c95 100644
--- a/src/widgets/doc/snippets/splitterhandle/splitter.h
+++ b/src/widgets/doc/snippets/splitterhandle/splitter.h
@@ -61,7 +61,7 @@ class QPaintEvent;
 class Splitter : public QSplitter
 {
 public:
-    Splitter(Qt::Orientation orientation, QWidget *parent = 0);
+    Splitter(Qt::Orientation orientation, QWidget *parent = nullptr);
 
 protected:
     QSplitterHandle *createHandle() override;
diff --git a/src/widgets/doc/snippets/updating-selections/window.h b/src/widgets/doc/snippets/updating-selections/window.h
index 0fb9c7eba8..26d11a659e 100644
--- a/src/widgets/doc/snippets/updating-selections/window.h
+++ b/src/widgets/doc/snippets/updating-selections/window.h
@@ -61,7 +61,7 @@ class MainWindow : public QMainWindow
 {
     Q_OBJECT
 public:
-    MainWindow(QWidget *parent = 0);
+    MainWindow(QWidget *parent = nullptr);
 
 public slots:
     void updateSelection(const QItemSelection &selected,
diff --git a/src/widgets/doc/src/modelview.qdoc b/src/widgets/doc/src/modelview.qdoc
index d60a68c8da..d95e49d6cc 100644
--- a/src/widgets/doc/src/modelview.qdoc
+++ b/src/widgets/doc/src/modelview.qdoc
@@ -535,7 +535,7 @@
      {
          Q_OBJECT
      public:
-         StarDelegate(QWidget *parent = 0);
+         StarDelegate(QWidget *parent = nullptr);
          void paint(QPainter *painter, const QStyleOptionViewItem &option,
                     const QModelIndex &index) const;
          QSize sizeHint(const QStyleOptionViewItem &option,
diff --git a/src/widgets/graphicsview/qgraphicsitem.cpp b/src/widgets/graphicsview/qgraphicsitem.cpp
index d8d0b61f43..43da7b7ade 100644
--- a/src/widgets/graphicsview/qgraphicsitem.cpp
+++ b/src/widgets/graphicsview/qgraphicsitem.cpp
@@ -5294,7 +5294,7 @@ void QGraphicsItem::setBoundingRegionGranularity(qreal granularity)
 
 /*!
     \fn virtual void QGraphicsItem::paint(QPainter *painter, const
-    QStyleOptionGraphicsItem *option, QWidget *widget = 0) = 0
+    QStyleOptionGraphicsItem *option, QWidget *widget = nullptr) = 0
 
     This function, which is usually called by QGraphicsView, paints the
     contents of an item in local coordinates.
diff --git a/src/widgets/graphicsview/qgraphicsitem_p.h b/src/widgets/graphicsview/qgraphicsitem_p.h
index fe8be8eae7..7264c62b3c 100644
--- a/src/widgets/graphicsview/qgraphicsitem_p.h
+++ b/src/widgets/graphicsview/qgraphicsitem_p.h
@@ -82,8 +82,8 @@ public:
     QDeclarativeListProperty(QObject *o, QList<T *> &list)
         : object(o), data(&list), append(qlist_append), count(qlist_count), at(qlist_at),
           clear(qlist_clear), dummy1(nullptr), dummy2(nullptr) {}
-    QDeclarativeListProperty(QObject *o, void *d, AppendFunction a, CountFunction c = 0, AtFunction t = 0,
-                    ClearFunction r = 0)
+    QDeclarativeListProperty(QObject *o, void *d, AppendFunction a, CountFunction c = nullptr, AtFunction t = nullptr,
+                    ClearFunction r = nullptr)
         : object(o), data(d), append(a), count(c), at(t), clear(r), dummy1(nullptr), dummy2(nullptr) {}
 
     bool operator==(const QDeclarativeListProperty &o) const {
diff --git a/src/widgets/graphicsview/qgraphicsscenelinearindex.cpp b/src/widgets/graphicsview/qgraphicsscenelinearindex.cpp
index 06f9125612..85e524096c 100644
--- a/src/widgets/graphicsview/qgraphicsscenelinearindex.cpp
+++ b/src/widgets/graphicsview/qgraphicsscenelinearindex.cpp
@@ -54,7 +54,7 @@
 #include <private/qgraphicsscenelinearindex_p.h>
 
 /*!
-    \fn QGraphicsSceneLinearIndex::QGraphicsSceneLinearIndex(QGraphicsScene *scene = 0):
+    \fn QGraphicsSceneLinearIndex::QGraphicsSceneLinearIndex(QGraphicsScene *scene = nullptr):
 
     Construct a linear index for the given \a scene.
 */
diff --git a/src/widgets/kernel/qapplication.cpp b/src/widgets/kernel/qapplication.cpp
index fdfb54881a..87bca40468 100644
--- a/src/widgets/kernel/qapplication.cpp
+++ b/src/widgets/kernel/qapplication.cpp
@@ -358,7 +358,7 @@ int QApplicationPrivate::enabledAnimations = QPlatformTheme::GeneralUiEffect;
 bool QApplicationPrivate::widgetCount = false;
 #ifdef QT_KEYPAD_NAVIGATION
 Qt::NavigationMode QApplicationPrivate::navigationMode = Qt::NavigationModeKeypadTabOrder;
-QWidget *QApplicationPrivate::oldEditFocus = 0;
+QWidget *QApplicationPrivate::oldEditFocus = nullptr;
 #endif
 
 inline bool QApplicationPrivate::isAlien(QWidget *widget)
diff --git a/src/widgets/kernel/qboxlayout.cpp b/src/widgets/kernel/qboxlayout.cpp
index a23b89a8a5..b01227b8d5 100644
--- a/src/widgets/kernel/qboxlayout.cpp
+++ b/src/widgets/kernel/qboxlayout.cpp
@@ -149,8 +149,8 @@ void QBoxLayoutPrivate::effectiveMargins(int *left, int *top, int *right, int *b
 #ifdef Q_OS_MAC
     Q_Q(const QBoxLayout);
     if (horz(dir)) {
-        QBoxLayoutItem *leftBox = 0;
-        QBoxLayoutItem *rightBox = 0;
+        QBoxLayoutItem *leftBox = nullptr;
+        QBoxLayoutItem *rightBox = nullptr;
 
         if (left || right) {
             leftBox = list.value(0);
@@ -194,8 +194,8 @@ void QBoxLayoutPrivate::effectiveMargins(int *left, int *top, int *right, int *b
             }
         }
     } else {    // vertical layout
-        QBoxLayoutItem *topBox = 0;
-        QBoxLayoutItem *bottomBox = 0;
+        QBoxLayoutItem *topBox = nullptr;
+        QBoxLayoutItem *bottomBox = nullptr;
 
         if (top || bottom) {
             topBox = list.value(0);
diff --git a/src/widgets/kernel/qgridlayout.cpp b/src/widgets/kernel/qgridlayout.cpp
index 51797b0cf1..339677378f 100644
--- a/src/widgets/kernel/qgridlayout.cpp
+++ b/src/widgets/kernel/qgridlayout.cpp
@@ -253,7 +253,7 @@ void QGridLayoutPrivate::effectiveMargins(int *left, int *top, int *right, int *
     int rightMost = 0;
     int bottomMost = 0;
 
-    QWidget *w = 0;
+    QWidget *w = nullptr;
     const int n = things.count();
     for (int i = 0; i < n; ++i) {
         QGridBox *box = things.at(i);
diff --git a/src/widgets/styles/qstyle.cpp b/src/widgets/styles/qstyle.cpp
index d327bca5fe..239d873649 100644
--- a/src/widgets/styles/qstyle.cpp
+++ b/src/widgets/styles/qstyle.cpp
@@ -2317,8 +2317,8 @@ QPalette QStyle::standardPalette() const
 /*!
     \since 4.1
 
-    \fn QIcon QStyle::standardIcon(StandardPixmap standardIcon, const QStyleOption *option = 0,
-                                   const QWidget *widget = 0) const = 0;
+    \fn QIcon QStyle::standardIcon(StandardPixmap standardIcon, const QStyleOption *option = nullptr,
+                                   const QWidget *widget = nullptr) const = 0;
 
     Returns an icon for the given \a standardIcon.
 
diff --git a/src/widgets/widgets/qcombobox.cpp b/src/widgets/widgets/qcombobox.cpp
index a03de6e7f2..7f7bcefb7a 100644
--- a/src/widgets/widgets/qcombobox.cpp
+++ b/src/widgets/widgets/qcombobox.cpp
@@ -2516,7 +2516,7 @@ bool QComboBoxPrivate::showNativePopup()
     int itemsCount = q->count();
     m_platformMenu->setTag(quintptr(itemsCount));
 
-    QPlatformMenuItem *currentItem = 0;
+    QPlatformMenuItem *currentItem = nullptr;
     int currentIndex = q->currentIndex();
 
     for (int i = 0; i < itemsCount; ++i) {
diff --git a/src/widgets/widgets/qdockwidget.cpp b/src/widgets/widgets/qdockwidget.cpp
index 6f5f345a40..548078098c 100644
--- a/src/widgets/widgets/qdockwidget.cpp
+++ b/src/widgets/widgets/qdockwidget.cpp
@@ -295,7 +295,7 @@ bool QDockWidgetLayout::wmSupportsNativeWindowDeco()
  */
 bool QDockWidgetLayout::nativeWindowDeco(bool floating) const
 {
-    return wmSupportsNativeWindowDeco() && floating && item_list.at(QDockWidgetLayout::TitleBar) == 0;
+    return wmSupportsNativeWindowDeco() && floating && item_list.at(QDockWidgetLayout::TitleBar) == nullptr;
 }
 
 
@@ -919,7 +919,7 @@ bool QDockWidgetPrivate::mousePressEvent(QMouseEvent *event)
             // check if the tool window is movable... do nothing if it
             // is not (but allow moving if the window is floating)
             (!hasFeature(this, QDockWidget::DockWidgetMovable) && !q->isFloating()) ||
-            (qobject_cast<QMainWindow*>(parent) == 0 && !floatingTab) ||
+            (qobject_cast<QMainWindow*>(parent) == nullptr && !floatingTab) ||
             isAnimating() || state != nullptr) {
             return false;
         }
@@ -1032,7 +1032,7 @@ void QDockWidgetPrivate::nonClientAreaMouseEvent(QMouseEvent *event)
                 break;
             if (state != nullptr)
                 break;
-            if (qobject_cast<QMainWindow*>(parent) == 0 && qobject_cast<QDockWidgetGroupWindow*>(parent) == 0)
+            if (qobject_cast<QMainWindow*>(parent) == nullptr && qobject_cast<QDockWidgetGroupWindow*>(parent) == nullptr)
                 break;
             if (isAnimating())
                 break;
@@ -1083,7 +1083,7 @@ void QDockWidgetPrivate::moveEvent(QMoveEvent *event)
     if (state == nullptr || !state->dragging || !state->nca)
         return;
 
-    if (!q->isWindow() && qobject_cast<QDockWidgetGroupWindow*>(parent) == 0)
+    if (!q->isWindow() && qobject_cast<QDockWidgetGroupWindow*>(parent) == nullptr)
         return;
 
     // When the native window frame is being dragged, all we get is these mouse
diff --git a/src/widgets/widgets/qlcdnumber.cpp b/src/widgets/widgets/qlcdnumber.cpp
index 4d299d8739..929b57a1e1 100644
--- a/src/widgets/widgets/qlcdnumber.cpp
+++ b/src/widgets/widgets/qlcdnumber.cpp
@@ -52,7 +52,7 @@ public:
     void init();
     void internalSetString(const QString& s);
     void drawString(const QString& s, QPainter &, QBitArray * = nullptr, bool = true);
-    //void drawString(const QString &, QPainter &, QBitArray * = 0) const;
+    //void drawString(const QString &, QPainter &, QBitArray * = nullptr) const;
     void drawDigit(const QPoint &, QPainter &, int, char, char = ' ');
     void drawSegment(const QPoint &, char, QPainter &, int, bool = false);
 
diff --git a/src/widgets/widgets/qmainwindowlayout.cpp b/src/widgets/widgets/qmainwindowlayout.cpp
index 76d9a33e06..95ee90eb31 100644
--- a/src/widgets/widgets/qmainwindowlayout.cpp
+++ b/src/widgets/widgets/qmainwindowlayout.cpp
@@ -646,7 +646,7 @@ QSize QMainWindowLayoutState::sizeHint() const
 #if QT_CONFIG(dockwidget)
     result = dockAreaLayout.sizeHint();
 #else
-    if (centralWidgetItem != 0)
+    if (centralWidgetItem)
         result = centralWidgetItem->sizeHint();
 #endif
 
@@ -664,7 +664,7 @@ QSize QMainWindowLayoutState::minimumSize() const
 #if QT_CONFIG(dockwidget)
     result = dockAreaLayout.minimumSize();
 #else
-    if (centralWidgetItem != 0)
+    if (centralWidgetItem)
         result = centralWidgetItem->minimumSize();
 #endif
 
@@ -685,9 +685,9 @@ void QMainWindowLayoutState::apply(bool animated)
 //    dumpLayout(dockAreaLayout, QString());
     dockAreaLayout.apply(animated);
 #else
-    if (centralWidgetItem != 0) {
+    if (centralWidgetItem) {
         QMainWindowLayout *layout = qt_mainwindow_layout(mainWindow);
-        Q_ASSERT(layout != 0);
+        Q_ASSERT(layout);
         layout->widgetAnimator.animate(centralWidgetItem->widget(), centralWidgetRect, animated);
     }
 #endif
@@ -744,7 +744,7 @@ QLayoutItem *QMainWindowLayoutState::itemAt(int index, int *x) const
     if (QLayoutItem *ret = dockAreaLayout.itemAt(x, index))
         return ret;
 #else
-    if (centralWidgetItem != 0 && (*x)++ == index)
+    if (centralWidgetItem  && (*x)++ == index)
         return centralWidgetItem;
 #endif
 
@@ -762,9 +762,9 @@ QLayoutItem *QMainWindowLayoutState::takeAt(int index, int *x)
     if (QLayoutItem *ret = dockAreaLayout.takeAt(x, index))
         return ret;
 #else
-    if (centralWidgetItem != 0 && (*x)++ == index) {
+    if (centralWidgetItem && (*x)++ == index) {
         QLayoutItem *ret = centralWidgetItem;
-        centralWidgetItem = 0;
+        centralWidgetItem = nullptr;
         return ret;
     }
 #endif
@@ -807,7 +807,7 @@ bool QMainWindowLayoutState::contains(QWidget *widget) const
     if (!dockAreaLayout.indexOf(widget).isEmpty())
         return true;
 #else
-    if (centralWidgetItem != 0 && centralWidgetItem->widget() == widget)
+    if (centralWidgetItem && centralWidgetItem->widget() == widget)
         return true;
 #endif
 
@@ -856,7 +856,7 @@ QList<int> QMainWindowLayoutState::gapIndex(QWidget *widget,
 
 #if QT_CONFIG(toolbar)
     // is it a toolbar?
-    if (qobject_cast<QToolBar*>(widget) != 0) {
+    if (qobject_cast<QToolBar*>(widget) != nullptr) {
         result = toolBarAreaLayout.gapIndex(pos);
         if (!result.isEmpty())
             result.prepend(0);
@@ -866,7 +866,7 @@ QList<int> QMainWindowLayoutState::gapIndex(QWidget *widget,
 
 #if QT_CONFIG(dockwidget)
     // is it a dock widget?
-    if (qobject_cast<QDockWidget *>(widget) != 0
+    if (qobject_cast<QDockWidget *>(widget) != nullptr
             || qobject_cast<QDockWidgetGroupWindow *>(widget)) {
         bool disallowTabs = false;
 #if QT_CONFIG(tabbar)
@@ -894,7 +894,7 @@ bool QMainWindowLayoutState::insertGap(const QList<int> &path, QLayoutItem *item
 
 #if QT_CONFIG(toolbar)
     if (i == 0) {
-        Q_ASSERT(qobject_cast<QToolBar*>(item->widget()) != 0);
+        Q_ASSERT(qobject_cast<QToolBar*>(item->widget()) != nullptr);
         return toolBarAreaLayout.insertGap(path.mid(1), item);
     }
 #endif
@@ -2155,7 +2155,7 @@ bool QMainWindowLayout::plug(QLayoutItem *widgetItem)
     QRect globalRect = currentGapRect;
     globalRect.moveTopLeft(parentWidget()->mapToGlobal(globalRect.topLeft()));
 #if QT_CONFIG(dockwidget)
-    if (qobject_cast<QDockWidget*>(widget) != 0) {
+    if (qobject_cast<QDockWidget*>(widget) != nullptr) {
         QDockWidgetLayout *layout = qobject_cast<QDockWidgetLayout*>(widget->layout());
         if (layout->nativeWindowDeco()) {
             globalRect.adjust(0, layout->titleHeight(), 0, 0);
@@ -2262,7 +2262,7 @@ void QMainWindowLayout::animationFinished(QWidget *widget)
 
 #if QT_CONFIG(dockwidget)
 #if QT_CONFIG(tabbar)
-        if (qobject_cast<QDockWidget*>(widget) != 0) {
+        if (qobject_cast<QDockWidget*>(widget) != nullptr) {
             // info() might return null if the widget is destroyed while
             // animating but before the animationFinished signal is received.
             if (QDockAreaLayoutInfo *info = dockInfo(widget))