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

 Conflicts:
	src/corelib/tools/qhash.h
	src/gui/kernel/qevent.h
	src/widgets/kernel/qshortcut.cpp
	src/widgets/kernel/qshortcut.h

Change-Id: If61c206ee43ad1d97f5b07f58ac93c4583ce5620

62 files changed, 1002 insertions, 487 deletions

diff --git a/src/corelib/corelib.pro b/src/corelib/corelib.pro
index eca888385b..3430154d13 100644
--- a/src/corelib/corelib.pro
+++ b/src/corelib/corelib.pro
@@ -1,6 +1,6 @@
 TARGET	   = QtCore
 QT         =
-CONFIG    += exceptions metatypes install_metatypes
+CONFIG    += exceptions
 
 MODULE = core     # not corelib, as per project file
 MODULE_CONFIG = moc resources
@@ -17,6 +17,7 @@ DEFINES += QT_NO_USING_NAMESPACE QT_NO_FOREACH
 msvc:equals(QT_ARCH, i386): QMAKE_LFLAGS += /BASE:0x67000000
 
 CONFIG += simd optimize_full
+CONFIG += metatypes install_metatypes
 
 QMAKE_DOCS = $$PWD/doc/qtcore.qdocconf
 
diff --git a/src/corelib/doc/snippets/code/src_corelib_global_qglobal.cpp b/src/corelib/doc/snippets/code/src_corelib_global_qglobal.cpp
index eb75a29ca2..a540b88247 100644
--- a/src/corelib/doc/snippets/code/src_corelib_global_qglobal.cpp
+++ b/src/corelib/doc/snippets/code/src_corelib_global_qglobal.cpp
@@ -50,6 +50,7 @@
 
 //! [0]
 label->setAlignment(Qt::AlignLeft | Qt::AlignTop);
+label->setAlignment({ });
 //! [0]
 
 
diff --git a/src/corelib/global/qflags.h b/src/corelib/global/qflags.h
index bd3c219968..4f46de5eaa 100644
--- a/src/corelib/global/qflags.h
+++ b/src/corelib/global/qflags.h
@@ -93,8 +93,10 @@ class QFlags
                       "long long will overflow.");
     Q_STATIC_ASSERT_X((std::is_enum<Enum>::value), "QFlags is only usable on enumeration types.");
 
+#if QT_DEPRECATED_SINCE(5,15)
     struct Private;
     typedef int (Private::*Zero);
+#endif
     template <typename E> friend QDataStream &operator>>(QDataStream &, QFlags<E> &);
     template <typename E> friend QDataStream &operator<<(QDataStream &, QFlags<E>);
 public:
@@ -115,8 +117,11 @@ public:
     Q_DECL_CONSTEXPR inline QFlags(const QFlags &other);
     Q_DECL_CONSTEXPR inline QFlags &operator=(const QFlags &other);
 #endif
+    Q_DECL_CONSTEXPR inline QFlags() noexcept : i(0) {}
     Q_DECL_CONSTEXPR inline QFlags(Enum flags) noexcept : i(Int(flags)) {}
-    Q_DECL_CONSTEXPR inline QFlags(Zero = nullptr) noexcept : i(0) {}
+#if QT_DEPRECATED_SINCE(5,15)
+    QT_DEPRECATED_X("Use default constructor instead") Q_DECL_CONSTEXPR inline QFlags(Zero) noexcept : i(0) {}
+#endif
     Q_DECL_CONSTEXPR inline QFlags(QFlag flag) noexcept : i(flag) {}
 
     Q_DECL_CONSTEXPR inline QFlags(std::initializer_list<Enum> flags) noexcept
diff --git a/src/corelib/global/qfloat16.cpp b/src/corelib/global/qfloat16.cpp
index 6c21b7de5a..97709d7685 100644
--- a/src/corelib/global/qfloat16.cpp
+++ b/src/corelib/global/qfloat16.cpp
@@ -146,6 +146,14 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
+    \since 5.15
+    \fn qfloat16::copySign(qfloat16 sign) const noexcept
+
+    Returns a qfloat16 with the sign of \a sign but the rest of its value taken
+    from this qfloat16. Serves as qfloat16's equivalent of std::copysign().
+*/
+
+/*!
     \internal
     \since 5.14
     Implements qFpClassify() for qfloat16.
diff --git a/src/corelib/global/qfloat16.h b/src/corelib/global/qfloat16.h
index 9a4f1800a4..154b200475 100644
--- a/src/corelib/global/qfloat16.h
+++ b/src/corelib/global/qfloat16.h
@@ -84,6 +84,9 @@ public:
     bool isNaN() const noexcept { return ((b16 >> 8) & 0x7e) == 0x7e; }
     bool isFinite() const noexcept { return ((b16 >> 8) & 0x7c) != 0x7c; }
     Q_CORE_EXPORT int fpClassify() const noexcept;
+    // Can't specialize std::copysign() for qfloat16
+    qfloat16 copySign(qfloat16 sign) const noexcept
+    { return qfloat16(Wrap((sign.b16 & 0x8000) | (b16 & 0x7fff))); }
     // Support for std::numeric_limits<qfloat16>
     static constexpr qfloat16 _limit_epsilon()    noexcept { return qfloat16(Wrap(0x1400)); }
     static constexpr qfloat16 _limit_min()        noexcept { return qfloat16(Wrap(0x400)); }
@@ -92,7 +95,9 @@ public:
     static constexpr qfloat16 _limit_lowest()     noexcept { return qfloat16(Wrap(0xfbff)); }
     static constexpr qfloat16 _limit_infinity()   noexcept { return qfloat16(Wrap(0x7c00)); }
     static constexpr qfloat16 _limit_quiet_NaN()  noexcept { return qfloat16(Wrap(0x7e00)); }
-    // Signalling NaN is 0x7f00
+#if QT_CONFIG(signaling_nan)
+    static constexpr qfloat16 _limit_signaling_NaN() noexcept { return qfloat16(Wrap(0x7f00)); }
+#endif
     inline constexpr bool isNormal() const noexcept
     { return (b16 & 0x7fff) == 0 || ((b16 & 0x7c00) && (b16 & 0x7c00) != 0x7c00); }
 private:
@@ -327,6 +332,12 @@ public:
     { return QT_PREPEND_NAMESPACE(qfloat16)::_limit_infinity(); }
     static constexpr QT_PREPEND_NAMESPACE(qfloat16) quiet_NaN()
     { return QT_PREPEND_NAMESPACE(qfloat16)::_limit_quiet_NaN(); }
+#if QT_CONFIG(signaling_nan)
+    static constexpr QT_PREPEND_NAMESPACE(qfloat16) signaling_NaN()
+    { return QT_PREPEND_NAMESPACE(qfloat16)::_limit_signaling_NaN(); }
+#else
+    static constexpr bool has_signaling_NaN = false;
+#endif
 };
 
 template<> class numeric_limits<const QT_PREPEND_NAMESPACE(qfloat16)>
diff --git a/src/corelib/global/qglobal.cpp b/src/corelib/global/qglobal.cpp
index 799d953c8d..a35e55b8f0 100644
--- a/src/corelib/global/qglobal.cpp
+++ b/src/corelib/global/qglobal.cpp
@@ -250,7 +250,7 @@ Q_STATIC_ASSERT((std::is_same<qsizetype, qptrdiff>::value));
     Qt::Alignment type is simply a typedef for
     QFlags<Qt::AlignmentFlag>. QLabel::setAlignment() takes a
     Qt::Alignment parameter, which means that any combination of
-    Qt::AlignmentFlag values, or 0, is legal:
+    Qt::AlignmentFlag values, or \c{{ }}, is legal:
 
     \snippet code/src_corelib_global_qglobal.cpp 0
 
@@ -318,10 +318,20 @@ Q_STATIC_ASSERT((std::is_same<qsizetype, qptrdiff>::value));
 */
 
 /*!
+    \fn template <typename Enum> QFlags<Enum>::QFlags()
+    \since 5.15
+
+    Constructs a QFlags object with no flags set.
+*/
+
+/*!
     \fn template <typename Enum> QFlags<Enum>::QFlags(Zero)
+    \deprecated
 
     Constructs a QFlags object with no flags set. The parameter must be a
     literal 0 value.
+
+    Deprecated, use default constructor instead.
 */
 
 /*!
diff --git a/src/corelib/global/qlibraryinfo.cpp b/src/corelib/global/qlibraryinfo.cpp
index 2da5861ccf..f4341e34fd 100644
--- a/src/corelib/global/qlibraryinfo.cpp
+++ b/src/corelib/global/qlibraryinfo.cpp
@@ -890,10 +890,10 @@ void qt_core_boilerplate()
            "\n"
            "Installation prefix: %s\n"
            "Library path:        %s\n"
-           "Include path:        %s\n",
+           "Plugin path:         %s\n",
            qt_configure_prefix_path_str + 12,
            qt_configure_strs + qt_configure_str_offsets[QT_PREPEND_NAMESPACE(QLibraryInfo)::LibrariesPath - 1],
-           qt_configure_strs + qt_configure_str_offsets[QT_PREPEND_NAMESPACE(QLibraryInfo)::HeadersPath - 1]);
+           qt_configure_strs + qt_configure_str_offsets[QT_PREPEND_NAMESPACE(QLibraryInfo)::PluginsPath - 1]);
 
     QT_PREPEND_NAMESPACE(qDumpCPUFeatures)();
 
diff --git a/src/corelib/io/io.pri b/src/corelib/io/io.pri
index fe81689932..c4c6f41387 100644
--- a/src/corelib/io/io.pri
+++ b/src/corelib/io/io.pri
@@ -136,6 +136,7 @@ qtConfig(settings) {
     } else: darwin:!nacl {
         SOURCES += io/qsettings_mac.cpp
     }
+    wasm : SOURCES += io/qsettings_wasm.cpp
 }
 
 win32 {
diff --git a/src/corelib/io/qabstractfileengine.cpp b/src/corelib/io/qabstractfileengine.cpp
index 8a1679c5af..070139b608 100644
--- a/src/corelib/io/qabstractfileengine.cpp
+++ b/src/corelib/io/qabstractfileengine.cpp
@@ -658,7 +658,7 @@ QStringList QAbstractFileEngine::entryList(QDir::Filters filters, const QStringL
 QAbstractFileEngine::FileFlags QAbstractFileEngine::fileFlags(FileFlags type) const
 {
     Q_UNUSED(type);
-    return nullptr;
+    return {};
 }
 
 /*!
diff --git a/src/corelib/io/qdir.cpp b/src/corelib/io/qdir.cpp
index fae935fc24..526702d151 100644
--- a/src/corelib/io/qdir.cpp
+++ b/src/corelib/io/qdir.cpp
@@ -2372,8 +2372,9 @@ static QString qt_cleanPath(const QString &path, bool *ok)
 }
 
 /*!
-    Returns \a path with directory separators normalized (converted to "/") and
-    redundant ones removed, and "."s and ".."s resolved (as far as possible).
+    Returns \a path with directory separators normalized (that is, platform-native
+    separators converted to "/") and redundant ones removed, and "."s and ".."s
+    resolved (as far as possible).
 
     Symbolic links are kept. This function does not return the
     canonical path, but rather the simplest version of the input.
diff --git a/src/corelib/io/qfile.h b/src/corelib/io/qfile.h
index cf1465ec70..2099b2852f 100644
--- a/src/corelib/io/qfile.h
+++ b/src/corelib/io/qfile.h
@@ -84,6 +84,10 @@ public:
         // note: duplicated in qglobal.cpp (qEnvironmentVariable)
         return QString::fromUtf8(localFileName).normalized(QString::NormalizationForm_C);
     }
+    static inline QString decodeName(const char *localFileName)
+    {
+        return QString::fromUtf8(localFileName).normalized(QString::NormalizationForm_C);
+    }
 #else
     static inline QByteArray encodeName(const QString &fileName)
     {
@@ -93,9 +97,11 @@ public:
     {
         return QString::fromLocal8Bit(localFileName);
     }
+    static inline QString decodeName(const char *localFileName)
+    {
+        return QString::fromLocal8Bit(localFileName);
+    }
 #endif
-    inline static QString decodeName(const char *localFileName)
-        { return decodeName(QByteArray(localFileName)); }
 
 #if QT_DEPRECATED_SINCE(5,0)
     typedef QByteArray (*EncoderFn)(const QString &fileName);
diff --git a/src/corelib/io/qfileinfo.cpp b/src/corelib/io/qfileinfo.cpp
index 89834de29f..3fe1aec41f 100644
--- a/src/corelib/io/qfileinfo.cpp
+++ b/src/corelib/io/qfileinfo.cpp
@@ -134,7 +134,7 @@ uint QFileInfoPrivate::getFileFlags(QAbstractFileEngine::FileFlags request) cons
     // extra syscall. Bundle detecton on Mac can be slow, expecially on network
     // paths, so we separate out that as well.
 
-    QAbstractFileEngine::FileFlags req = nullptr;
+    QAbstractFileEngine::FileFlags req;
     uint cachedFlags = 0;
 
     if (request & (QAbstractFileEngine::FlagsMask | QAbstractFileEngine::TypesMask)) {
@@ -1145,6 +1145,25 @@ bool QFileInfo::isShortcut() const
             [d]() { return d->getFileFlags(QAbstractFileEngine::LinkType); });
 }
 
+
+/*!
+    Returns \c true if the object points to a junction;
+    otherwise returns \c false.
+
+    Junctions only exist on Windows' NTFS file system, and are typically
+    created by the \c{mklink} command. They can be thought of as symlinks for
+    directories, and can only be created for absolute paths on the local
+    volume.
+*/
+bool QFileInfo::isJunction() const
+{
+    Q_D(const QFileInfo);
+    return d->checkAttribute<bool>(
+            QFileSystemMetaData::LegacyLinkType,
+            [d]() { return d->metaData.isJunction(); },
+            [d]() { return d->getFileFlags(QAbstractFileEngine::LinkType); });
+}
+
 /*!
     Returns \c true if the object points to a directory or to a symbolic
     link to a directory, and that directory is the root directory; otherwise
diff --git a/src/corelib/io/qfileinfo.h b/src/corelib/io/qfileinfo.h
index 3ac028085a..7c7ff56ae4 100644
--- a/src/corelib/io/qfileinfo.h
+++ b/src/corelib/io/qfileinfo.h
@@ -113,6 +113,7 @@ public:
     bool isSymLink() const;
     bool isSymbolicLink() const;
     bool isShortcut() const;
+    bool isJunction() const;
     bool isRoot() const;
     bool isBundle() const;
 
diff --git a/src/corelib/io/qfilesystemmetadata_p.h b/src/corelib/io/qfilesystemmetadata_p.h
index 81f4b3ba13..3154658e5c 100644
--- a/src/corelib/io/qfilesystemmetadata_p.h
+++ b/src/corelib/io/qfilesystemmetadata_p.h
@@ -76,8 +76,7 @@ class Q_AUTOTEST_EXPORT QFileSystemMetaData
 {
 public:
     QFileSystemMetaData()
-        : knownFlagsMask(nullptr),
-          size_(-1)
+        : size_(-1)
     {
     }
 
@@ -111,8 +110,10 @@ public:
         AliasType           =        0x0,
 #endif
 #if defined(Q_OS_WIN)
+        JunctionType        = 0x04000000,
         WinLnkType          = 0x08000000,   // Note: Uses the same position for AliasType on Mac
 #else
+        JunctionType        =        0x0,
         WinLnkType          =        0x0,
 #endif
         SequentialType      = 0x00800000,   // Note: overlaps with QAbstractFileEngine::RootFlag
@@ -184,7 +185,7 @@ public:
 
     void clear()
     {
-        knownFlagsMask = nullptr;
+        knownFlagsMask = {};
     }
 
     void clearFlags(MetaDataFlags flags = AllMetaDataFlags)
@@ -205,8 +206,10 @@ public:
     bool wasDeleted() const                 { return (entryFlags & WasDeletedAttribute); }
 #if defined(Q_OS_WIN)
     bool isLnkFile() const                  { return (entryFlags & WinLnkType); }
+    bool isJunction() const                 { return (entryFlags & JunctionType); }
 #else
     bool isLnkFile() const                  { return false; }
+    bool isJunction() const                 { return false; }
 #endif
 
     qint64 size() const                     { return size_; }
@@ -356,9 +359,15 @@ inline void QFileSystemMetaData::fillFromFindData(WIN32_FIND_DATA &findData, boo
     if (setLinkType) {
         knownFlagsMask |=  LinkType;
         entryFlags &= ~LinkType;
-        if ((fileAttribute_ & FILE_ATTRIBUTE_REPARSE_POINT)
-            && (findData.dwReserved0 == IO_REPARSE_TAG_SYMLINK)) {
-            entryFlags |= LinkType;
+        if (fileAttribute_ & FILE_ATTRIBUTE_REPARSE_POINT) {
+            if (findData.dwReserved0 == IO_REPARSE_TAG_SYMLINK) {
+                entryFlags |= LinkType;
+#if defined(IO_REPARSE_TAG_MOUNT_POINT)
+            } else if ((fileAttribute_ & FILE_ATTRIBUTE_DIRECTORY)
+                    && (findData.dwReserved0 == IO_REPARSE_TAG_MOUNT_POINT)) {
+                entryFlags |= JunctionType;
+#endif
+            }
         }
     }
 }
diff --git a/src/corelib/io/qfsfileengine_win.cpp b/src/corelib/io/qfsfileengine_win.cpp
index 5b868cc447..dd4882a2bc 100644
--- a/src/corelib/io/qfsfileengine_win.cpp
+++ b/src/corelib/io/qfsfileengine_win.cpp
@@ -591,14 +591,14 @@ QAbstractFileEngine::FileFlags QFSFileEngine::fileFlags(QAbstractFileEngine::Fil
     if (type & Refresh)
         d->metaData.clear();
 
-    QAbstractFileEngine::FileFlags ret = 0;
+    QAbstractFileEngine::FileFlags ret;
 
     if (type & FlagsMask)
         ret |= LocalDiskFlag;
 
     bool exists;
     {
-        QFileSystemMetaData::MetaDataFlags queryFlags = 0;
+        QFileSystemMetaData::MetaDataFlags queryFlags;
 
         queryFlags |= QFileSystemMetaData::MetaDataFlags(uint(type))
                 & QFileSystemMetaData::Permissions;
diff --git a/src/corelib/io/qloggingcategory.cpp b/src/corelib/io/qloggingcategory.cpp
index 4d4784cdf7..5de8be116c 100644
--- a/src/corelib/io/qloggingcategory.cpp
+++ b/src/corelib/io/qloggingcategory.cpp
@@ -179,7 +179,7 @@ static void setBoolLane(QBasicAtomicInt *atomic, bool enable, int shift)
     The \c QtProject/qtlogging.ini file is looked up in all directories returned
     by QStandardPaths::GenericConfigLocation.
 
-    Set the \c QT_LOGGING_DEBUG environment variable to find out where you logging
+    Set the \c QT_LOGGING_DEBUG environment variable to find out where your logging
     rules are loaded from.
 
     \section2 Installing a Custom Filter
diff --git a/src/corelib/io/qprocess.h b/src/corelib/io/qprocess.h
index 9fda5fba11..585508adf1 100644
--- a/src/corelib/io/qprocess.h
+++ b/src/corelib/io/qprocess.h
@@ -278,7 +278,8 @@ Q_SIGNALS:
     void finished(int exitCode); // ### Qt 6: merge the two signals with a default value
 #endif
     void finished(int exitCode, QProcess::ExitStatus exitStatus);
-#if QT_DEPRECATED_SINCE(5,6)
+#if QT_DEPRECATED_SINCE(5, 6)
+    QT_DEPRECATED_X("Use QProcess::errorOccurred(QProcess::ProcessError) instead")
     void error(QProcess::ProcessError error);
 #endif
     void errorOccurred(QProcess::ProcessError error);
diff --git a/src/corelib/io/qprocess_unix.cpp b/src/corelib/io/qprocess_unix.cpp
index 0c80daa024..9edb4a6d11 100644
--- a/src/corelib/io/qprocess_unix.cpp
+++ b/src/corelib/io/qprocess_unix.cpp
@@ -246,7 +246,7 @@ bool QProcessPrivate::openChannel(Channel &channel)
             return false;
 
         // create the socket notifiers
-        if (threadData->hasEventDispatcher()) {
+        if (threadData.loadRelaxed()->hasEventDispatcher()) {
             if (&channel == &stdinChannel) {
                 channel.notifier = new QSocketNotifier(channel.pipe[1],
                                                        QSocketNotifier::Write, q);
@@ -377,7 +377,7 @@ void QProcessPrivate::startProcess()
         return;
     }
 
-    if (threadData->hasEventDispatcher()) {
+    if (threadData.loadRelaxed()->hasEventDispatcher()) {
         startupSocketNotifier = new QSocketNotifier(childStartedPipe[0],
                                                     QSocketNotifier::Read, q);
         QObject::connect(startupSocketNotifier, SIGNAL(activated(int)),
@@ -517,7 +517,7 @@ void QProcessPrivate::startProcess()
     if (stderrChannel.pipe[0] != -1)
         ::fcntl(stderrChannel.pipe[0], F_SETFL, ::fcntl(stderrChannel.pipe[0], F_GETFL) | O_NONBLOCK);
 
-    if (threadData->eventDispatcher.loadAcquire()) {
+    if (threadData.loadRelaxed()->eventDispatcher.loadAcquire()) {
         deathNotifier = new QSocketNotifier(forkfd, QSocketNotifier::Read, q);
         QObject::connect(deathNotifier, SIGNAL(activated(int)),
                          q, SLOT(_q_processDied()));
diff --git a/src/corelib/io/qprocess_win.cpp b/src/corelib/io/qprocess_win.cpp
index 3ba86063e3..05af5a5aee 100644
--- a/src/corelib/io/qprocess_win.cpp
+++ b/src/corelib/io/qprocess_win.cpp
@@ -590,7 +590,7 @@ void QProcessPrivate::startProcess()
     if (!pid)
         return;
 
-    if (threadData->hasEventDispatcher()) {
+    if (threadData.loadRelaxed()->hasEventDispatcher()) {
         processFinishedNotifier = new QWinEventNotifier(pid->hProcess, q);
         QObject::connect(processFinishedNotifier, SIGNAL(activated(HANDLE)), q, SLOT(_q_processDied()));
         processFinishedNotifier->setEnabled(true);
diff --git a/src/corelib/io/qresource.cpp b/src/corelib/io/qresource.cpp
index 86d361b06a..44657f8398 100644
--- a/src/corelib/io/qresource.cpp
+++ b/src/corelib/io/qresource.cpp
@@ -1486,7 +1486,7 @@ bool QResourceFileEngine::isSequential() const
 QAbstractFileEngine::FileFlags QResourceFileEngine::fileFlags(QAbstractFileEngine::FileFlags type) const
 {
     Q_D(const QResourceFileEngine);
-    QAbstractFileEngine::FileFlags ret = 0;
+    QAbstractFileEngine::FileFlags ret;
     if(!d->resource.isValid())
         return ret;
 
diff --git a/src/corelib/io/qsettings.cpp b/src/corelib/io/qsettings.cpp
index e485310e86..da2a790e1e 100644
--- a/src/corelib/io/qsettings.cpp
+++ b/src/corelib/io/qsettings.cpp
@@ -76,10 +76,6 @@
 #  include <ioLib.h>
 #endif
 
-#ifdef Q_OS_WASM
-#include <emscripten.h>
-#endif
-
 #include <algorithm>
 #include <stdlib.h>
 
@@ -295,7 +291,7 @@ after_loop:
 
 // see also qsettings_win.cpp, qsettings_winrt.cpp and qsettings_mac.cpp
 
-#if !defined(Q_OS_WIN) && !defined(Q_OS_MAC)
+#if !defined(Q_OS_WIN) && !defined(Q_OS_MAC) && !defined(Q_OS_WASM)
 QSettingsPrivate *QSettingsPrivate::create(QSettings::Format format, QSettings::Scope scope,
                                            const QString &organization, const QString &application)
 {
@@ -1188,7 +1184,9 @@ QConfFileSettingsPrivate::QConfFileSettingsPrivate(QSettings::Format format,
         confFiles.append(QConfFile::fromName(systemPath.path + orgFile, false));
     }
 
+#ifndef Q_OS_WASM // wasm needs to delay access until after file sync
     initAccess();
+#endif
 }
 
 QConfFileSettingsPrivate::QConfFileSettingsPrivate(const QString &fileName,
@@ -1551,13 +1549,6 @@ void QConfFileSettingsPrivate::syncConfFile(QConfFile *confFile)
                     perms |= QFile::ReadGroup | QFile::ReadOther;
                 QFile(confFile->name).setPermissions(perms);
             }
-#ifdef Q_OS_WASM
-        EM_ASM(
-            // Sync sandbox filesystem to persistent database filesystem. See QTBUG-70002
-            FS.syncfs(false, function(err) {
-            });
-        );
-#endif
         } else {
             setStatus(QSettings::AccessError);
         }
diff --git a/src/corelib/io/qsettings_p.h b/src/corelib/io/qsettings_p.h
index d18c96a06c..c30f099a72 100644
--- a/src/corelib/io/qsettings_p.h
+++ b/src/corelib/io/qsettings_p.h
@@ -57,6 +57,10 @@
 #include "QtCore/qiodevice.h"
 #include "QtCore/qstack.h"
 #include "QtCore/qstringlist.h"
+
+#include <QtCore/qvariant.h>
+#include "qsettings.h"
+
 #ifndef QT_NO_QOBJECT
 #include "private/qobject_p.h"
 #endif
@@ -253,6 +257,10 @@ protected:
     mutable QSettings::Status status;
 };
 
+#ifdef Q_OS_WASM
+class QWasmSettingsPrivate;
+#endif
+
 class QConfFileSettingsPrivate : public QSettingsPrivate
 {
 public:
@@ -281,7 +289,7 @@ public:
 
 private:
     void initFormat();
-    void initAccess();
+    virtual void initAccess();
     void syncConfFile(QConfFile *confFile);
     bool writeIniFile(QIODevice &device, const ParsedSettingsMap &map);
 #ifdef Q_OS_MAC
@@ -297,6 +305,9 @@ private:
     QString extension;
     Qt::CaseSensitivity caseSensitivity;
     int nextPosition;
+#ifdef Q_OS_WASM
+    friend class QWasmSettingsPrivate;
+#endif
 };
 
 QT_END_NAMESPACE
diff --git a/src/corelib/io/qsettings_wasm.cpp b/src/corelib/io/qsettings_wasm.cpp
new file mode 100644
index 0000000000..8d8f4b505c
--- /dev/null
+++ b/src/corelib/io/qsettings_wasm.cpp
@@ -0,0 +1,259 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qsettings.h"
+#ifndef QT_NO_SETTINGS
+
+#include "qsettings_p.h"
+#ifndef QT_NO_QOBJECT
+#include "qcoreapplication.h"
+#include <QFile>
+#endif // QT_NO_QOBJECT
+#include <QDebug>
+
+#include <QFileInfo>
+#include <QDir>
+#include <emscripten.h>
+
+QT_BEGIN_NAMESPACE
+
+static bool isReadReady = false;
+
+class QWasmSettingsPrivate : public QConfFileSettingsPrivate
+{
+public:
+    QWasmSettingsPrivate(QSettings::Scope scope, const QString &organization,
+                        const QString &application);
+    ~QWasmSettingsPrivate();
+
+    bool get(const QString &key, QVariant *value) const override;
+    QStringList children(const QString &prefix, ChildSpec spec) const override;
+    void clear() override;
+    void sync() override;
+    void flush() override;
+    bool isWritable() const override;
+
+    void syncToLocal(const char *data, int size);
+    void loadLocal(const QByteArray &filename);
+    void setReady();
+    void initAccess() override;
+
+private:
+    QString databaseName;
+    QString id;
+};
+
+static void QWasmSettingsPrivate_onLoad(void *userData, void *dataPtr, int size)
+{
+    QWasmSettingsPrivate *wasm = reinterpret_cast<QWasmSettingsPrivate *>(userData);
+
+    QFile file(wasm->fileName());
+    QFileInfo fileInfo(wasm->fileName());
+    QDir dir(fileInfo.path());
+    if (!dir.exists())
+        dir.mkpath(fileInfo.path());
+
+    if (file.open(QFile::WriteOnly)) {
+        file.write(reinterpret_cast<char *>(dataPtr), size);
+        file.close();
+        wasm->setReady();
+    }
+}
+
+static void QWasmSettingsPrivate_onError(void *userData)
+{
+    QWasmSettingsPrivate *wasm = reinterpret_cast<QWasmSettingsPrivate *>(userData);
+    if (wasm)
+        wasm->setStatus(QSettings::AccessError);
+}
+
+static void QWasmSettingsPrivate_onStore(void *userData)
+{
+    QWasmSettingsPrivate *wasm = reinterpret_cast<QWasmSettingsPrivate *>(userData);
+    if (wasm)
+        wasm->setStatus(QSettings::NoError);
+}
+
+static void QWasmSettingsPrivate_onCheck(void *userData, int exists)
+{
+    QWasmSettingsPrivate *wasm = reinterpret_cast<QWasmSettingsPrivate *>(userData);
+    if (wasm) {
+        if (exists)
+            wasm->loadLocal(wasm->fileName().toLocal8Bit());
+        else
+            wasm->setReady();
+    }
+}
+
+QSettingsPrivate *QSettingsPrivate::create(QSettings::Format format,
+                                           QSettings::Scope scope,
+                                           const QString &organization,
+                                           const QString &application)
+{
+    Q_UNUSED(format)
+    if (organization == QLatin1String("Qt"))
+    {
+        QString organizationDomain = QCoreApplication::organizationDomain();
+        QString applicationName = QCoreApplication::applicationName();
+
+        QSettingsPrivate *newSettings;
+        newSettings = new QWasmSettingsPrivate(scope, organizationDomain, applicationName);
+
+        newSettings->beginGroupOrArray(QSettingsGroup(normalizedKey(organization)));
+        if (!application.isEmpty())
+            newSettings->beginGroupOrArray(QSettingsGroup(normalizedKey(application)));
+
+        return newSettings;
+    }
+    return new QWasmSettingsPrivate(scope, organization, application);
+}
+
+QWasmSettingsPrivate::QWasmSettingsPrivate(QSettings::Scope scope, const QString &organization,
+                                           const QString &application)
+    : QConfFileSettingsPrivate(QSettings::NativeFormat, scope, organization, application)
+{
+    setStatus(QSettings::AccessError); // access error until sandbox gets loaded
+    databaseName = organization;
+    id = application;
+
+    emscripten_idb_async_exists("/home/web_user",
+                                fileName().toLocal8Bit(),
+                                reinterpret_cast<void*>(this),
+                                QWasmSettingsPrivate_onCheck,
+                                QWasmSettingsPrivate_onError);
+}
+
+QWasmSettingsPrivate::~QWasmSettingsPrivate()
+{
+}
+
+ void QWasmSettingsPrivate::initAccess()
+{
+     if (isReadReady)
+         QConfFileSettingsPrivate::initAccess();
+}
+
+bool QWasmSettingsPrivate::get(const QString &key, QVariant *value) const
+{
+    if (isReadReady)
+        return QConfFileSettingsPrivate::get(key, value);
+
+    return false;
+}
+
+QStringList QWasmSettingsPrivate::children(const QString &prefix, ChildSpec spec) const
+{
+    return QConfFileSettingsPrivate::children(prefix, spec);
+}
+
+void QWasmSettingsPrivate::clear()
+{
+    QConfFileSettingsPrivate::clear();
+    emscripten_idb_async_delete("/home/web_user",
+                                fileName().toLocal8Bit(),
+                                reinterpret_cast<void*>(this),
+                                QWasmSettingsPrivate_onStore,
+                                QWasmSettingsPrivate_onError);
+}
+
+void QWasmSettingsPrivate::sync()
+{
+    QConfFileSettingsPrivate::sync();
+
+    QFile file(fileName());
+    if (file.open(QFile::ReadOnly)) {
+        QByteArray dataPointer = file.readAll();
+
+        emscripten_idb_async_store("/home/web_user",
+                                  fileName().toLocal8Bit(),
+                                   reinterpret_cast<void *>(dataPointer.data()),
+                                   dataPointer.length(),
+                                   reinterpret_cast<void*>(this),
+                                   QWasmSettingsPrivate_onStore,
+                                   QWasmSettingsPrivate_onError);
+    }
+}
+
+void QWasmSettingsPrivate::flush()
+{
+    sync();
+}
+
+bool QWasmSettingsPrivate::isWritable() const
+{
+    return isReadReady && QConfFileSettingsPrivate::isWritable();
+}
+
+void QWasmSettingsPrivate::syncToLocal(const char *data, int size)
+{
+    QFile file(fileName());
+
+    if (file.open(QFile::WriteOnly)) {
+        file.write(data, size + 1);
+        QByteArray data = file.readAll();
+
+        emscripten_idb_async_store("/home/web_user",
+                                   fileName().toLocal8Bit(),
+                                   reinterpret_cast<void *>(data.data()),
+                                   data.length(),
+                                   reinterpret_cast<void*>(this),
+                                   QWasmSettingsPrivate_onStore,
+                                   QWasmSettingsPrivate_onError);
+        setReady();
+    }
+}
+
+void QWasmSettingsPrivate::loadLocal(const QByteArray &filename)
+{
+    emscripten_idb_async_load("/home/web_user",
+                              filename.data(),
+                              reinterpret_cast<void*>(this),
+                              QWasmSettingsPrivate_onLoad,
+                              QWasmSettingsPrivate_onError);
+}
+
+void QWasmSettingsPrivate::setReady()
+{
+    isReadReady = true;
+    setStatus(QSettings::NoError);
+    QConfFileSettingsPrivate::initAccess();
+}
+
+QT_END_NAMESPACE
+#endif // QT_NO_SETTINGS
diff --git a/src/corelib/io/qstandardpaths.cpp b/src/corelib/io/qstandardpaths.cpp
index 7874b854e4..7306f19fc9 100644
--- a/src/corelib/io/qstandardpaths.cpp
+++ b/src/corelib/io/qstandardpaths.cpp
@@ -359,22 +359,14 @@ QT_BEGIN_NAMESPACE
 /*!
     \fn QString QStandardPaths::writableLocation(StandardLocation type)
 
-    Returns the directory where files of \a type should be written to, or an empty string
-    if the location cannot be determined.
-
-    \note The storage location returned can be a directory that does not exist; i.e., it
-    may need to be created by the system or the user.
+    \include standardpath/functiondoc.qdocinc writableLocation
 */
 
 
 /*!
    \fn QStringList QStandardPaths::standardLocations(StandardLocation type)
 
-   Returns all the directories where files of \a type belong.
-
-   The list of directories is sorted from high to low priority, starting with
-   writableLocation() if it can be determined. This list is empty if no locations
-   for \a type are defined.
+   \include standardpath/functiondoc.qdocinc standardLocations
 
    \sa writableLocation()
  */
@@ -398,11 +390,7 @@ static bool existsAsSpecified(const QString &path, QStandardPaths::LocateOptions
 }
 
 /*!
-   Tries to find a file or directory called \a fileName in the standard locations
-   for \a type.
-
-   The full path to the first file or directory (depending on \a options) found is returned.
-   If no such file or directory can be found, an empty string is returned.
+    \include standardpath/functiondoc.qdocinc locate
  */
 QString QStandardPaths::locate(StandardLocation type, const QString &fileName, LocateOptions options)
 {
@@ -416,12 +404,7 @@ QString QStandardPaths::locate(StandardLocation type, const QString &fileName, L
 }
 
 /*!
-   Tries to find all files or directories called \a fileName in the standard locations
-   for \a type.
-
-   The \a options flag allows to specify whether to look for files or directories.
-
-   Returns the list of all the files that were found.
+    \include standardpath/functiondoc.qdocinc locateAll
  */
 QStringList QStandardPaths::locateAll(StandardLocation type, const QString &fileName, LocateOptions options)
 {
@@ -494,23 +477,7 @@ static inline QString
 #endif // Q_OS_WIN
 
 /*!
-  Finds the executable named \a executableName in the paths specified by \a paths,
-  or the system paths if \a paths is empty.
-
-  On most operating systems the system path is determined by the PATH environment variable.
-
-  The directories where to search for the executable can be set in the \a paths argument.
-  To search in both your own paths and the system paths, call findExecutable twice, once with
-  \a paths set and once with \a paths empty.
-
-  Symlinks are not resolved, in order to preserve behavior for the case of executables
-  whose behavior depends on the name they are invoked with.
-
-  \note On Windows, the usual executable extensions (from the PATHEXT environment variable)
-  are automatically appended, so that for instance findExecutable("foo") will find foo.exe
-  or foo.bat if present.
-
-  Returns the absolute file path to the executable, or an empty string if not found.
+    \include standardpath/functiondoc.qdocinc findExecutable
  */
 QString QStandardPaths::findExecutable(const QString &executableName, const QStringList &paths)
 {
@@ -568,10 +535,7 @@ QString QStandardPaths::findExecutable(const QString &executableName, const QStr
 }
 
 /*!
-    \fn QString QStandardPaths::displayName(StandardLocation type)
-
-    Returns a localized display name for the given location \a type or
-    an empty QString if no relevant location can be found.
+    \include standardpath/functiondoc.qdocinc displayName
 */
 
 #if !defined(Q_OS_MAC) && !defined(QT_BOOTSTRAPPED)
@@ -628,23 +592,7 @@ QString QStandardPaths::displayName(StandardLocation type)
 /*!
   \fn void QStandardPaths::setTestModeEnabled(bool testMode)
 
-  If \a testMode is true, this enables a special "test mode" in
-  QStandardPaths, which changes writable locations
-  to point to test directories, in order to prevent auto tests from reading from
-  or writing to the current user's configuration.
-
-  This affects the locations into which test programs might write files:
-  GenericDataLocation, DataLocation, ConfigLocation, GenericConfigLocation,
-  AppConfigLocation, GenericCacheLocation, CacheLocation.
-  Other locations are not affected.
-
-  On Unix, \c XDG_DATA_HOME is set to \e ~/.qttest/share, \c XDG_CONFIG_HOME is
-  set to \e ~/.qttest/config, and \c XDG_CACHE_HOME is set to \e ~/.qttest/cache.
-
-  On \macos, data goes to \e ~/.qttest/Application Support, cache goes to
-  \e ~/.qttest/Cache, and config goes to \e ~/.qttest/Preferences.
-
-  On Windows, everything goes to a "qttest" directory under Application Data.
+  \include standardpath/functiondoc.qdocinc setTestModeEnabled
 */
 
 static bool qsp_testMode = false;
diff --git a/src/corelib/io/qtemporaryfile.cpp b/src/corelib/io/qtemporaryfile.cpp
index acd31f4d84..55d13dad70 100644
--- a/src/corelib/io/qtemporaryfile.cpp
+++ b/src/corelib/io/qtemporaryfile.cpp
@@ -631,6 +631,12 @@ QString QTemporaryFilePrivate::defaultTemplateName()
     case sensitive. If the template is not present in the filename,
     QTemporaryFile appends the generated part to the filename given.
 
+    \note On Linux, QTemporaryFile will attempt to create unnamed temporary
+    files. If that succeeds, open() will return true but exists() will be
+    false. If you call fileName() or any function that calls it,
+    QTemporaryFile will give the file a name, so most applications will
+    not see a difference.
+
     \sa QDir::tempPath(), QFile
 */
 
diff --git a/src/corelib/io/qurl.cpp b/src/corelib/io/qurl.cpp
index a7650390f9..0a5f9256eb 100644
--- a/src/corelib/io/qurl.cpp
+++ b/src/corelib/io/qurl.cpp
@@ -823,7 +823,7 @@ recodeFromUser(const QString &input, const ushort *actions, int from, int to)
     QString output;
     const QChar *begin = input.constData() + from;
     const QChar *end = input.constData() + to;
-    if (qt_urlRecode(output, begin, end, nullptr, actions))
+    if (qt_urlRecode(output, begin, end, {}, actions))
         return output;
 
     return input.mid(from, to - from);
diff --git a/src/corelib/itemmodels/qabstractitemmodel.cpp b/src/corelib/itemmodels/qabstractitemmodel.cpp
index fc69e362c7..48b72880e6 100644
--- a/src/corelib/itemmodels/qabstractitemmodel.cpp
+++ b/src/corelib/itemmodels/qabstractitemmodel.cpp
@@ -432,7 +432,7 @@ Qt::ItemFlags QPersistentModelIndex::flags() const
 {
     if (d)
         return d->index.flags();
-    return 0;
+    return { };
 }
 
 /*!
@@ -2296,7 +2296,7 @@ Qt::ItemFlags QAbstractItemModel::flags(const QModelIndex &index) const
 {
     Q_D(const QAbstractItemModel);
     if (!d->indexValid(index))
-        return 0;
+        return { };
 
     return Qt::ItemIsSelectable|Qt::ItemIsEnabled;
 }
diff --git a/src/corelib/itemmodels/qsortfilterproxymodel.cpp b/src/corelib/itemmodels/qsortfilterproxymodel.cpp
index 978102035e..21303549ab 100644
--- a/src/corelib/itemmodels/qsortfilterproxymodel.cpp
+++ b/src/corelib/itemmodels/qsortfilterproxymodel.cpp
@@ -2682,6 +2682,7 @@ void QSortFilterProxyModel::setFilterCaseSensitivity(Qt::CaseSensitivity cs)
     d->filter_about_to_be_changed();
     d->filter_data.setCaseSensitivity(cs);
     d->filter_changed();
+    emit filterCaseSensitivityChanged(cs);
 }
 
 /*!
@@ -2707,6 +2708,7 @@ void QSortFilterProxyModel::setSortCaseSensitivity(Qt::CaseSensitivity cs)
 
     d->sort_casesensitivity = cs;
     d->sort();
+    emit sortCaseSensitivityChanged(cs);
 }
 
 /*!
@@ -2732,6 +2734,7 @@ void QSortFilterProxyModel::setSortLocaleAware(bool on)
 
     d->sort_localeaware = on;
     d->sort();
+    emit sortLocaleAwareChanged(on);
 }
 
 /*!
@@ -2856,6 +2859,7 @@ void QSortFilterProxyModel::setSortRole(int role)
         return;
     d->sort_role = role;
     d->sort();
+    emit sortRoleChanged(role);
 }
 
 /*!
@@ -2881,6 +2885,7 @@ void QSortFilterProxyModel::setFilterRole(int role)
     d->filter_about_to_be_changed();
     d->filter_role = role;
     d->filter_changed();
+    emit filterRoleChanged(role);
 }
 
 /*!
@@ -2907,6 +2912,7 @@ void QSortFilterProxyModel::setRecursiveFilteringEnabled(bool recursive)
     d->filter_about_to_be_changed();
     d->filter_recursive = recursive;
     d->filter_changed();
+    emit recursiveFilteringEnabledChanged(recursive);
 }
 
 #if QT_DEPRECATED_SINCE(5, 11)
diff --git a/src/corelib/itemmodels/qsortfilterproxymodel.h b/src/corelib/itemmodels/qsortfilterproxymodel.h
index 303226668f..91253dd601 100644
--- a/src/corelib/itemmodels/qsortfilterproxymodel.h
+++ b/src/corelib/itemmodels/qsortfilterproxymodel.h
@@ -68,12 +68,12 @@ class Q_CORE_EXPORT QSortFilterProxyModel : public QAbstractProxyModel
 #endif
     Q_PROPERTY(int filterKeyColumn READ filterKeyColumn WRITE setFilterKeyColumn)
     Q_PROPERTY(bool dynamicSortFilter READ dynamicSortFilter WRITE setDynamicSortFilter)
-    Q_PROPERTY(Qt::CaseSensitivity filterCaseSensitivity READ filterCaseSensitivity WRITE setFilterCaseSensitivity)
-    Q_PROPERTY(Qt::CaseSensitivity sortCaseSensitivity READ sortCaseSensitivity WRITE setSortCaseSensitivity)
-    Q_PROPERTY(bool isSortLocaleAware READ isSortLocaleAware WRITE setSortLocaleAware)
-    Q_PROPERTY(int sortRole READ sortRole WRITE setSortRole)
-    Q_PROPERTY(int filterRole READ filterRole WRITE setFilterRole)
-    Q_PROPERTY(bool recursiveFilteringEnabled READ isRecursiveFilteringEnabled WRITE setRecursiveFilteringEnabled)
+    Q_PROPERTY(Qt::CaseSensitivity filterCaseSensitivity READ filterCaseSensitivity WRITE setFilterCaseSensitivity NOTIFY filterCaseSensitivityChanged)
+    Q_PROPERTY(Qt::CaseSensitivity sortCaseSensitivity READ sortCaseSensitivity WRITE setSortCaseSensitivity NOTIFY sortCaseSensitivityChanged)
+    Q_PROPERTY(bool isSortLocaleAware READ isSortLocaleAware WRITE setSortLocaleAware NOTIFY sortLocaleAwareChanged)
+    Q_PROPERTY(int sortRole READ sortRole WRITE setSortRole NOTIFY sortRoleChanged)
+    Q_PROPERTY(int filterRole READ filterRole WRITE setFilterRole NOTIFY filterRoleChanged)
+    Q_PROPERTY(bool recursiveFilteringEnabled READ isRecursiveFilteringEnabled WRITE setRecursiveFilteringEnabled NOTIFY recursiveFilteringEnabledChanged)
 
 public:
     explicit QSortFilterProxyModel(QObject *parent = nullptr);
@@ -185,6 +185,16 @@ public:
 
     QStringList mimeTypes() const override;
     Qt::DropActions supportedDropActions() const override;
+
+Q_SIGNALS:
+    void dynamicSortFilterChanged(bool dynamicSortFilter);
+    void filterCaseSensitivityChanged(Qt::CaseSensitivity filterCaseSensitivity);
+    void sortCaseSensitivityChanged(Qt::CaseSensitivity sortCaseSensitivity);
+    void sortLocaleAwareChanged(bool sortLocaleAware);
+    void sortRoleChanged(int sortRole);
+    void filterRoleChanged(int filterRole);
+    void recursiveFilteringEnabledChanged(bool recursiveFilteringEnabled);
+
 private:
     Q_DECLARE_PRIVATE(QSortFilterProxyModel)
     Q_DISABLE_COPY(QSortFilterProxyModel)
diff --git a/src/corelib/kernel/qbasictimer.cpp b/src/corelib/kernel/qbasictimer.cpp
index ea8f8e2c77..623ecb9b8b 100644
--- a/src/corelib/kernel/qbasictimer.cpp
+++ b/src/corelib/kernel/qbasictimer.cpp
@@ -216,13 +216,11 @@ void QBasicTimer::stop()
 {
     if (id) {
         QAbstractEventDispatcher *eventDispatcher = QAbstractEventDispatcher::instance();
-        if (eventDispatcher) {
-            if (Q_UNLIKELY(!eventDispatcher->unregisterTimer(id))) {
-                qWarning("QBasicTimer::stop: Failed. Possibly trying to stop from a different thread");
-                return;
-            }
-            QAbstractEventDispatcherPrivate::releaseTimerId(id);
+        if (eventDispatcher && !eventDispatcher->unregisterTimer(id)) {
+            qWarning("QBasicTimer::stop: Failed. Possibly trying to stop from a different thread");
+            return;
         }
+        QAbstractEventDispatcherPrivate::releaseTimerId(id);
     }
     id = 0;
 }
diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index 6531cd8e0c..a66c71cff6 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -121,7 +121,6 @@
 #endif
 
 #ifdef Q_OS_WASM
-#include <emscripten.h>
 #include <emscripten/val.h>
 #endif
 
@@ -135,23 +134,6 @@
 
 QT_BEGIN_NAMESPACE
 
-#ifndef QT_NO_QOBJECT
-class QMutexUnlocker
-{
-public:
-    inline explicit QMutexUnlocker(QMutex *m)
-        : mtx(m)
-    { }
-    inline ~QMutexUnlocker() { unlock(); }
-    inline void unlock() { if (mtx) mtx->unlock(); mtx = 0; }
-
-private:
-    Q_DISABLE_COPY(QMutexUnlocker)
-
-    QMutex *mtx;
-};
-#endif
-
 #if defined(Q_OS_WIN) || defined(Q_OS_MAC)
 extern QString qAppFileName();
 #endif
@@ -497,13 +479,6 @@ QCoreApplicationPrivate::QCoreApplicationPrivate(int &aargc, char **aargv, uint
 
 QCoreApplicationPrivate::~QCoreApplicationPrivate()
 {
-#ifdef Q_OS_WASM
-    EM_ASM(
-        // unmount persistent directory as IDBFS
-        // see also QTBUG-70002
-        FS.unmount('/home/web_user');
-    );
-#endif
 #ifndef QT_NO_QOBJECT
     cleanupThreadData();
 #endif
@@ -517,25 +492,27 @@ QCoreApplicationPrivate::~QCoreApplicationPrivate()
 
 void QCoreApplicationPrivate::cleanupThreadData()
 {
-    if (threadData && !threadData_clean) {
+    auto thisThreadData = threadData.loadRelaxed();
+
+    if (thisThreadData && !threadData_clean) {
 #if QT_CONFIG(thread)
-        void *data = &threadData->tls;
+        void *data = &thisThreadData->tls;
         QThreadStorageData::finish((void **)data);
 #endif
 
         // need to clear the state of the mainData, just in case a new QCoreApplication comes along.
-        const auto locker = qt_scoped_lock(threadData->postEventList.mutex);
-        for (int i = 0; i < threadData->postEventList.size(); ++i) {
-            const QPostEvent &pe = threadData->postEventList.at(i);
+        const auto locker = qt_scoped_lock(thisThreadData->postEventList.mutex);
+        for (int i = 0; i < thisThreadData->postEventList.size(); ++i) {
+            const QPostEvent &pe = thisThreadData->postEventList.at(i);
             if (pe.event) {
                 --pe.receiver->d_func()->postedEvents;
                 pe.event->posted = false;
                 delete pe.event;
             }
         }
-        threadData->postEventList.clear();
-        threadData->postEventList.recursion = 0;
-        threadData->quitNow = false;
+        thisThreadData->postEventList.clear();
+        thisThreadData->postEventList.recursion = 0;
+        thisThreadData->quitNow = false;
         threadData_clean = true;
     }
 }
@@ -795,17 +772,8 @@ void QCoreApplicationPrivate::init()
     Q_ASSERT_X(!QCoreApplication::self, "QCoreApplication", "there should be only one application object");
     QCoreApplication::self = q;
 
-#ifdef Q_OS_WASM
-    EM_ASM(
-        // mount and sync persistent filesystem to sandbox
-        FS.mount(IDBFS, {}, '/home/web_user');
-        FS.syncfs(true, function(err) {
-            if (err)
-                Module.print(err);
-        });
-    );
-
 #if QT_CONFIG(thread)
+#ifdef Q_OS_WASM
     QThreadPrivate::idealThreadCount = emscripten::val::global("navigator")["hardwareConcurrency"].as<int>();
 #endif
 #endif
@@ -858,7 +826,8 @@ void QCoreApplicationPrivate::init()
 #ifndef QT_NO_QOBJECT
     // use the event dispatcher created by the app programmer (if any)
     Q_ASSERT(!eventDispatcher);
-    eventDispatcher = threadData->eventDispatcher.loadRelaxed();
+    auto thisThreadData = threadData.loadRelaxed();
+    eventDispatcher = thisThreadData->eventDispatcher.loadRelaxed();
 
     // otherwise we create one
     if (!eventDispatcher)
@@ -866,11 +835,11 @@ void QCoreApplicationPrivate::init()
     Q_ASSERT(eventDispatcher);
 
     if (!eventDispatcher->parent()) {
-        eventDispatcher->moveToThread(threadData->thread.loadAcquire());
+        eventDispatcher->moveToThread(thisThreadData->thread.loadAcquire());
         eventDispatcher->setParent(q);
     }
 
-    threadData->eventDispatcher = eventDispatcher;
+    thisThreadData->eventDispatcher = eventDispatcher;
     eventDispatcherReady();
 #endif
 
@@ -914,7 +883,7 @@ QCoreApplication::~QCoreApplication()
 #endif
 
 #ifndef QT_NO_QOBJECT
-    d_func()->threadData->eventDispatcher = nullptr;
+    d_func()->threadData.loadRelaxed()->eventDispatcher = nullptr;
     if (QCoreApplicationPrivate::eventDispatcher)
         QCoreApplicationPrivate::eventDispatcher->closingDown();
     QCoreApplicationPrivate::eventDispatcher = nullptr;
@@ -1185,7 +1154,7 @@ static bool doNotify(QObject *receiver, QEvent *event)
 bool QCoreApplicationPrivate::sendThroughApplicationEventFilters(QObject *receiver, QEvent *event)
 {
     // We can't access the application event filters outside of the main thread (race conditions)
-    Q_ASSERT(receiver->d_func()->threadData->thread.loadAcquire() == mainThread());
+    Q_ASSERT(receiver->d_func()->threadData.loadRelaxed()->thread.loadAcquire() == mainThread());
 
     if (extraData) {
         // application event filters are only called for objects in the GUI thread
@@ -1238,7 +1207,7 @@ bool QCoreApplicationPrivate::notify_helper(QObject *receiver, QEvent * event)
 
     // send to all application event filters (only does anything in the main thread)
     if (QCoreApplication::self
-            && receiver->d_func()->threadData->thread.loadAcquire() == mainThread()
+            && receiver->d_func()->threadData.loadRelaxed()->thread.loadAcquire() == mainThread()
             && QCoreApplication::self->d_func()->sendThroughApplicationEventFilters(receiver, event)) {
         filtered = true;
         return filtered;
@@ -1414,7 +1383,7 @@ int QCoreApplication::exec()
 
 void QCoreApplicationPrivate::execCleanup()
 {
-    threadData->quitNow = false;
+    threadData.loadRelaxed()->quitNow = false;
     in_exec = false;
     if (!aboutToQuitEmitted)
         emit q_func()->aboutToQuit(QCoreApplication::QPrivateSignal());
@@ -1451,7 +1420,7 @@ void QCoreApplication::exit(int returnCode)
 {
     if (!self)
         return;
-    QThreadData *data = self->d_func()->threadData;
+    QThreadData *data = self->d_func()->threadData.loadRelaxed();
     data->quitNow = true;
     for (int i = 0; i < data->eventLoops.size(); ++i) {
         QEventLoop *eventLoop = data->eventLoops.at(i);
@@ -1501,6 +1470,38 @@ bool QCoreApplication::sendSpontaneousEvent(QObject *receiver, QEvent *event)
 
 #endif // QT_NO_QOBJECT
 
+QCoreApplicationPrivate::QPostEventListLocker QCoreApplicationPrivate::lockThreadPostEventList(QObject *object)
+{
+    QPostEventListLocker locker;
+
+    if (!object) {
+        locker.threadData = QThreadData::current();
+        locker.locker = qt_unique_lock(locker.threadData->postEventList.mutex);
+        return locker;
+    }
+
+    auto &threadData = QObjectPrivate::get(object)->threadData;
+
+    // if object has moved to another thread, follow it
+    for (;;) {
+        // synchronizes with the storeRelease in QObject::moveToThread
+        locker.threadData = threadData.loadAcquire();
+        if (!locker.threadData) {
+            // destruction in progress
+            return locker;
+        }
+
+        auto temporaryLocker = qt_unique_lock(locker.threadData->postEventList.mutex);
+        if (locker.threadData == threadData.loadAcquire()) {
+            locker.locker = std::move(temporaryLocker);
+            break;
+        }
+    }
+
+    Q_ASSERT(locker.threadData);
+    return locker;
+}
+
 /*!
     \since 4.3
 
@@ -1536,32 +1537,14 @@ void QCoreApplication::postEvent(QObject *receiver, QEvent *event, int priority)
         return;
     }
 
-    QThreadData * volatile * pdata = &receiver->d_func()->threadData;
-    QThreadData *data = *pdata;
-    if (!data) {
+    auto locker = QCoreApplicationPrivate::lockThreadPostEventList(receiver);
+    if (!locker.threadData) {
         // posting during destruction? just delete the event to prevent a leak
         delete event;
         return;
     }
 
-    // lock the post event mutex
-    data->postEventList.mutex.lock();
-
-    // if object has moved to another thread, follow it
-    while (data != *pdata) {
-        data->postEventList.mutex.unlock();
-
-        data = *pdata;
-        if (!data) {
-            // posting during destruction? just delete the event to prevent a leak
-            delete event;
-            return;
-        }
-
-        data->postEventList.mutex.lock();
-    }
-
-    QMutexUnlocker locker(&data->postEventList.mutex);
+    QThreadData *data = locker.threadData;
 
     // if this is one of the compressible events, do compression
     if (receiver->d_func()->postedEvents
@@ -1860,8 +1843,8 @@ void QCoreApplicationPrivate::sendPostedEvents(QObject *receiver, int event_type
 
 void QCoreApplication::removePostedEvents(QObject *receiver, int eventType)
 {
-    QThreadData *data = receiver ? receiver->d_func()->threadData : QThreadData::current();
-    auto locker = qt_unique_lock(data->postEventList.mutex);
+    auto locker = QCoreApplicationPrivate::lockThreadPostEventList(receiver);
+    QThreadData *data = locker.threadData;
 
     // the QObject destructor calls this function directly.  this can
     // happen while the event loop is in the middle of posting events,
diff --git a/src/corelib/kernel/qcoreapplication_p.h b/src/corelib/kernel/qcoreapplication_p.h
index 3bad42d076..9d2fde619c 100644
--- a/src/corelib/kernel/qcoreapplication_p.h
+++ b/src/corelib/kernel/qcoreapplication_p.h
@@ -61,6 +61,7 @@
 #endif
 #ifndef QT_NO_QOBJECT
 #include "private/qobject_p.h"
+#include "private/qlocking_p.h"
 #endif
 
 #ifdef Q_OS_MACOS
@@ -140,6 +141,15 @@ public:
 
     static void checkReceiverThread(QObject *receiver);
     void cleanupThreadData();
+
+    struct QPostEventListLocker
+    {
+        QThreadData *threadData;
+        std::unique_lock<QMutex> locker;
+
+        void unlock() { locker.unlock(); }
+    };
+    static QPostEventListLocker lockThreadPostEventList(QObject *object);
 #endif // QT_NO_QOBJECT
 
     int &argc;
diff --git a/src/corelib/kernel/qcoreapplication_win.cpp b/src/corelib/kernel/qcoreapplication_win.cpp
index 37c43dee4f..824c0535ed 100644
--- a/src/corelib/kernel/qcoreapplication_win.cpp
+++ b/src/corelib/kernel/qcoreapplication_win.cpp
@@ -918,7 +918,7 @@ QDebug operator<<(QDebug dbg, const MSG &msg)
 #ifndef QT_NO_QOBJECT
 void QCoreApplicationPrivate::removePostedTimerEvent(QObject *object, int timerId)
 {
-    QThreadData *data = object->d_func()->threadData;
+    QThreadData *data = object->d_func()->threadData.loadRelaxed();
 
     const auto locker = qt_scoped_lock(data->postEventList.mutex);
     if (data->postEventList.size() == 0)
diff --git a/src/corelib/kernel/qeventdispatcher_unix.cpp b/src/corelib/kernel/qeventdispatcher_unix.cpp
index 5bc65b7110..2492d70005 100644
--- a/src/corelib/kernel/qeventdispatcher_unix.cpp
+++ b/src/corelib/kernel/qeventdispatcher_unix.cpp
@@ -463,13 +463,15 @@ bool QEventDispatcherUNIX::processEvents(QEventLoop::ProcessEventsFlags flags)
 
     // we are awake, broadcast it
     emit awake();
-    QCoreApplicationPrivate::sendPostedEvents(0, 0, d->threadData);
+
+    auto threadData = d->threadData.loadRelaxed();
+    QCoreApplicationPrivate::sendPostedEvents(0, 0, threadData);
 
     const bool include_timers = (flags & QEventLoop::X11ExcludeTimers) == 0;
     const bool include_notifiers = (flags & QEventLoop::ExcludeSocketNotifiers) == 0;
     const bool wait_for_events = flags & QEventLoop::WaitForMoreEvents;
 
-    const bool canWait = (d->threadData->canWaitLocked()
+    const bool canWait = (threadData->canWaitLocked()
                           && !d->interrupt.loadRelaxed()
                           && wait_for_events);
 
diff --git a/src/corelib/kernel/qeventdispatcher_win.cpp b/src/corelib/kernel/qeventdispatcher_win.cpp
index 87623f304a..8616631603 100644
--- a/src/corelib/kernel/qeventdispatcher_win.cpp
+++ b/src/corelib/kernel/qeventdispatcher_win.cpp
@@ -636,11 +636,11 @@ void QEventDispatcherWin32::registerSocketNotifier(QSocketNotifier *notifier)
     int type = notifier->type();
 #ifndef QT_NO_DEBUG
     if (sockfd < 0) {
-        qWarning("QSocketNotifier: Internal error");
+        qWarning("QEventDispatcherWin32::registerSocketNotifier: invalid socket identifier");
         return;
     }
     if (notifier->thread() != thread() || thread() != QThread::currentThread()) {
-        qWarning("QSocketNotifier: socket notifiers cannot be enabled from another thread");
+        qWarning("QEventDispatcherWin32: socket notifiers cannot be enabled from another thread");
         return;
     }
 #endif
@@ -697,11 +697,11 @@ void QEventDispatcherWin32::unregisterSocketNotifier(QSocketNotifier *notifier)
 #ifndef QT_NO_DEBUG
     int sockfd = notifier->socket();
     if (sockfd < 0) {
-        qWarning("QSocketNotifier: Internal error");
+        qWarning("QEventDispatcherWin32::unregisterSocketNotifier: invalid socket identifier");
         return;
     }
     if (notifier->thread() != thread() || thread() != QThread::currentThread()) {
-        qWarning("QSocketNotifier: socket notifiers cannot be disabled from another thread");
+        qWarning("QEventDispatcherWin32: socket notifiers cannot be disabled from another thread");
         return;
     }
 #endif
@@ -783,8 +783,7 @@ bool QEventDispatcherWin32::unregisterTimer(int timerId)
         qWarning("QEventDispatcherWin32::unregisterTimer: invalid argument");
         return false;
     }
-    QThread *currentThread = QThread::currentThread();
-    if (thread() != currentThread) {
+    if (thread() != QThread::currentThread()) {
         qWarning("QEventDispatcherWin32::unregisterTimer: timers cannot be stopped from another thread");
         return false;
     }
@@ -811,8 +810,7 @@ bool QEventDispatcherWin32::unregisterTimers(QObject *object)
         qWarning("QEventDispatcherWin32::unregisterTimers: invalid argument");
         return false;
     }
-    QThread *currentThread = QThread::currentThread();
-    if (object->thread() != thread() || thread() != currentThread) {
+    if (object->thread() != thread() || thread() != QThread::currentThread()) {
         qWarning("QEventDispatcherWin32::unregisterTimers: timers cannot be stopped from another thread");
         return false;
     }
@@ -837,10 +835,12 @@ bool QEventDispatcherWin32::unregisterTimers(QObject *object)
 QList<QEventDispatcherWin32::TimerInfo>
 QEventDispatcherWin32::registeredTimers(QObject *object) const
 {
+#ifndef QT_NO_DEBUG
     if (!object) {
         qWarning("QEventDispatcherWin32:registeredTimers: invalid argument");
         return QList<TimerInfo>();
     }
+#endif
 
     Q_D(const QEventDispatcherWin32);
     QList<TimerInfo> list;
@@ -853,13 +853,13 @@ QEventDispatcherWin32::registeredTimers(QObject *object) const
 
 bool QEventDispatcherWin32::registerEventNotifier(QWinEventNotifier *notifier)
 {
-    if (!notifier) {
-        qWarning("QWinEventNotifier: Internal error");
-        return false;
-    } else if (notifier->thread() != thread() || thread() != QThread::currentThread()) {
-        qWarning("QWinEventNotifier: event notifiers cannot be enabled from another thread");
+    Q_ASSERT(notifier);
+#ifndef QT_NO_DEBUG
+    if (notifier->thread() != thread() || thread() != QThread::currentThread()) {
+        qWarning("QEventDispatcherWin32: event notifiers cannot be enabled from another thread");
         return false;
     }
+#endif
 
     Q_D(QEventDispatcherWin32);
 
@@ -877,13 +877,13 @@ bool QEventDispatcherWin32::registerEventNotifier(QWinEventNotifier *notifier)
 
 void QEventDispatcherWin32::unregisterEventNotifier(QWinEventNotifier *notifier)
 {
-    if (!notifier) {
-        qWarning("QWinEventNotifier: Internal error");
-        return;
-    } else if (notifier->thread() != thread() || thread() != QThread::currentThread()) {
-        qWarning("QWinEventNotifier: event notifiers cannot be disabled from another thread");
+    Q_ASSERT(notifier);
+#ifndef QT_NO_DEBUG
+    if (notifier->thread() != thread() || thread() != QThread::currentThread()) {
+        qWarning("QEventDispatcherWin32: event notifiers cannot be disabled from another thread");
         return;
     }
+#endif
 
     Q_D(QEventDispatcherWin32);
 
@@ -1048,7 +1048,7 @@ bool QEventDispatcherWin32::event(QEvent *e)
 void QEventDispatcherWin32::sendPostedEvents()
 {
     Q_D(QEventDispatcherWin32);
-    QCoreApplicationPrivate::sendPostedEvents(0, 0, d->threadData);
+    QCoreApplicationPrivate::sendPostedEvents(0, 0, d->threadData.loadRelaxed());
 }
 
 HWND QEventDispatcherWin32::internalHwnd()
diff --git a/src/corelib/kernel/qeventloop.cpp b/src/corelib/kernel/qeventloop.cpp
index eacd0c4e73..5a5dfb06aa 100644
--- a/src/corelib/kernel/qeventloop.cpp
+++ b/src/corelib/kernel/qeventloop.cpp
@@ -106,7 +106,7 @@ QEventLoop::QEventLoop(QObject *parent)
     if (!QCoreApplication::instance() && QCoreApplicationPrivate::threadRequiresCoreApplication()) {
         qWarning("QEventLoop: Cannot be used without QApplication");
     } else {
-        d->threadData->ensureEventDispatcher();
+        d->threadData.loadRelaxed()->ensureEventDispatcher();
     }
 }
 
@@ -133,9 +133,10 @@ QEventLoop::~QEventLoop()
 bool QEventLoop::processEvents(ProcessEventsFlags flags)
 {
     Q_D(QEventLoop);
-    if (!d->threadData->hasEventDispatcher())
+    auto threadData = d->threadData.loadRelaxed();
+    if (!threadData->hasEventDispatcher())
         return false;
-    return d->threadData->eventDispatcher.loadRelaxed()->processEvents(flags);
+    return threadData->eventDispatcher.loadRelaxed()->processEvents(flags);
 }
 
 /*!
@@ -164,9 +165,11 @@ bool QEventLoop::processEvents(ProcessEventsFlags flags)
 int QEventLoop::exec(ProcessEventsFlags flags)
 {
     Q_D(QEventLoop);
+    auto threadData = d->threadData.loadRelaxed();
+
     //we need to protect from race condition with QThread::exit
-    QMutexLocker locker(&static_cast<QThreadPrivate *>(QObjectPrivate::get(d->threadData->thread.loadAcquire()))->mutex);
-    if (d->threadData->quitNow)
+    QMutexLocker locker(&static_cast<QThreadPrivate *>(QObjectPrivate::get(threadData->thread.loadAcquire()))->mutex);
+    if (threadData->quitNow)
         return -1;
 
     if (d->inExec) {
@@ -183,8 +186,11 @@ int QEventLoop::exec(ProcessEventsFlags flags)
         {
             d->inExec = true;
             d->exit.storeRelease(false);
-            ++d->threadData->loopLevel;
-            d->threadData->eventLoops.push(d->q_func());
+
+            auto threadData = d->threadData.loadRelaxed();
+            ++threadData->loopLevel;
+            threadData->eventLoops.push(d->q_func());
+
             locker.unlock();
         }
 
@@ -198,11 +204,12 @@ int QEventLoop::exec(ProcessEventsFlags flags)
                          "QCoreApplication::notify() and catch all exceptions there.\n");
             }
             locker.relock();
-            QEventLoop *eventLoop = d->threadData->eventLoops.pop();
+            auto threadData = d->threadData.loadRelaxed();
+            QEventLoop *eventLoop = threadData->eventLoops.pop();
             Q_ASSERT_X(eventLoop == d->q_func(), "QEventLoop::exec()", "internal error");
             Q_UNUSED(eventLoop); // --release warning
             d->inExec = false;
-            --d->threadData->loopLevel;
+            --threadData->loopLevel;
         }
     };
     LoopReference ref(d, locker);
@@ -217,7 +224,7 @@ int QEventLoop::exec(ProcessEventsFlags flags)
     // exception, which returns control to the browser while preserving the C++ stack.
     // Event processing then continues as normal. The sleep call below never returns.
     // QTBUG-70185
-    if (d->threadData->loopLevel > 1)
+    if (threadData->loopLevel > 1)
         emscripten_sleep(1);
 #endif
 
@@ -247,7 +254,7 @@ int QEventLoop::exec(ProcessEventsFlags flags)
 void QEventLoop::processEvents(ProcessEventsFlags flags, int maxTime)
 {
     Q_D(QEventLoop);
-    if (!d->threadData->hasEventDispatcher())
+    if (!d->threadData.loadRelaxed()->hasEventDispatcher())
         return;
 
     QElapsedTimer start;
@@ -276,21 +283,22 @@ void QEventLoop::processEvents(ProcessEventsFlags flags, int maxTime)
 void QEventLoop::exit(int returnCode)
 {
     Q_D(QEventLoop);
-    if (!d->threadData->hasEventDispatcher())
+    auto threadData = d->threadData.loadAcquire();
+    if (!threadData->hasEventDispatcher())
         return;
 
     d->returnCode.storeRelaxed(returnCode);
     d->exit.storeRelease(true);
-    d->threadData->eventDispatcher.loadRelaxed()->interrupt();
+    threadData->eventDispatcher.loadRelaxed()->interrupt();
 
 #ifdef Q_OS_WASM
     // QEventLoop::exec() never returns in emscripten. We implement approximate behavior here.
     // QTBUG-70185
-    if (d->threadData->loopLevel == 1) {
+    if (threadData->loopLevel == 1) {
         emscripten_force_exit(returnCode);
     } else {
         d->inExec = false;
-        --d->threadData->loopLevel;
+        --threadData->loopLevel;
     }
 #endif
 }
@@ -316,9 +324,10 @@ bool QEventLoop::isRunning() const
 void QEventLoop::wakeUp()
 {
     Q_D(QEventLoop);
-    if (!d->threadData->hasEventDispatcher())
+    auto threadData = d->threadData.loadAcquire();
+    if (!threadData->hasEventDispatcher())
         return;
-    d->threadData->eventDispatcher.loadRelaxed()->wakeUp();
+    threadData->eventDispatcher.loadRelaxed()->wakeUp();
 }
 
 
diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index d713555bb6..a2f76a6354 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -211,11 +211,12 @@ QObjectPrivate::QObjectPrivate(int version)
 
 QObjectPrivate::~QObjectPrivate()
 {
+    auto thisThreadData = threadData.loadRelaxed();
     if (extraData && !extraData->runningTimers.isEmpty()) {
-        if (Q_LIKELY(threadData->thread.loadAcquire() == QThread::currentThread())) {
+        if (Q_LIKELY(thisThreadData->thread.loadAcquire() == QThread::currentThread())) {
             // unregister pending timers
-            if (threadData->hasEventDispatcher())
-                threadData->eventDispatcher.loadRelaxed()->unregisterTimers(q_ptr);
+            if (thisThreadData->hasEventDispatcher())
+                thisThreadData->eventDispatcher.loadRelaxed()->unregisterTimers(q_ptr);
 
             // release the timer ids back to the pool
             for (int i = 0; i < extraData->runningTimers.size(); ++i)
@@ -228,7 +229,7 @@ QObjectPrivate::~QObjectPrivate()
     if (postedEvents)
         QCoreApplication::removePostedEvents(q_ptr, 0);
 
-    threadData->deref();
+    thisThreadData->deref();
 
     if (metaObject) metaObject->objectDestroyed(q_ptr);
 
@@ -915,11 +916,12 @@ QObject::QObject(QObjectPrivate &dd, QObject *parent)
 
     Q_D(QObject);
     d_ptr->q_ptr = this;
-    d->threadData = (parent && !parent->thread()) ? parent->d_func()->threadData : QThreadData::current();
-    d->threadData->ref();
+    auto threadData = (parent && !parent->thread()) ? parent->d_func()->threadData.loadRelaxed() : QThreadData::current();
+    threadData->ref();
+    d->threadData.storeRelaxed(threadData);
     if (parent) {
         QT_TRY {
-            if (!check_parent_thread(parent, parent ? parent->d_func()->threadData : 0, d->threadData))
+            if (!check_parent_thread(parent, parent ? parent->d_func()->threadData.loadRelaxed() : 0, threadData))
                 parent = 0;
             if (d->isWidget) {
                 if (parent) {
@@ -931,7 +933,7 @@ QObject::QObject(QObjectPrivate &dd, QObject *parent)
                 setParent(parent);
             }
         } QT_CATCH(...) {
-            d->threadData->deref();
+            threadData->deref();
             QT_RETHROW;
         }
     }
@@ -1308,7 +1310,7 @@ bool QObject::event(QEvent *e)
 
     case QEvent::ThreadChange: {
         Q_D(QObject);
-        QThreadData *threadData = d->threadData;
+        QThreadData *threadData = d->threadData.loadRelaxed();
         QAbstractEventDispatcher *eventDispatcher = threadData->eventDispatcher.loadRelaxed();
         if (eventDispatcher) {
             QList<QAbstractEventDispatcher::TimerInfo> timers = eventDispatcher->registeredTimers(this);
@@ -1475,7 +1477,7 @@ bool QObject::blockSignals(bool block) noexcept
 */
 QThread *QObject::thread() const
 {
-    return d_func()->threadData->thread.loadAcquire();
+    return d_func()->threadData.loadRelaxed()->thread.loadAcquire();
 }
 
 /*!
@@ -1522,7 +1524,7 @@ void QObject::moveToThread(QThread *targetThread)
 {
     Q_D(QObject);
 
-    if (d->threadData->thread.loadAcquire() == targetThread) {
+    if (d->threadData.loadRelaxed()->thread.loadAcquire() == targetThread) {
         // object is already in this thread
         return;
     }
@@ -1538,13 +1540,14 @@ void QObject::moveToThread(QThread *targetThread)
 
     QThreadData *currentData = QThreadData::current();
     QThreadData *targetData = targetThread ? QThreadData::get2(targetThread) : nullptr;
-    if (d->threadData->thread.loadAcquire() == 0 && currentData == targetData) {
+    QThreadData *thisThreadData = d->threadData.loadRelaxed();
+    if (!thisThreadData->thread.loadAcquire() && currentData == targetData) {
         // one exception to the rule: we allow moving objects with no thread affinity to the current thread
         currentData = d->threadData;
-    } else if (d->threadData != currentData) {
+    } else if (thisThreadData != currentData) {
         qWarning("QObject::moveToThread: Current thread (%p) is not the object's thread (%p).\n"
                  "Cannot move to target thread (%p)\n",
-                 currentData->thread.loadRelaxed(), d->threadData->thread.loadRelaxed(), targetData ? targetData->thread.loadRelaxed() : nullptr);
+                 currentData->thread.loadRelaxed(), thisThreadData->thread.loadRelaxed(), targetData ? targetData->thread.loadRelaxed() : nullptr);
 
 #ifdef Q_OS_MAC
         qWarning("You might be loading two sets of Qt binaries into the same process. "
@@ -1641,8 +1644,10 @@ void QObjectPrivate::setThreadData_helper(QThreadData *currentData, QThreadData
 
     // set new thread data
     targetData->ref();
-    threadData->deref();
-    threadData = targetData;
+    threadData.loadRelaxed()->deref();
+
+    // synchronizes with loadAcquire e.g. in QCoreApplication::postEvent
+    threadData.storeRelease(targetData);
 
     for (int i = 0; i < children.size(); ++i) {
         QObject *child = children.at(i);
@@ -1654,7 +1659,7 @@ void QObjectPrivate::_q_reregisterTimers(void *pointer)
 {
     Q_Q(QObject);
     QList<QAbstractEventDispatcher::TimerInfo> *timerList = reinterpret_cast<QList<QAbstractEventDispatcher::TimerInfo> *>(pointer);
-    QAbstractEventDispatcher *eventDispatcher = threadData->eventDispatcher.loadRelaxed();
+    QAbstractEventDispatcher *eventDispatcher = threadData.loadRelaxed()->eventDispatcher.loadRelaxed();
     for (int i = 0; i < timerList->size(); ++i) {
         const QAbstractEventDispatcher::TimerInfo &ti = timerList->at(i);
         eventDispatcher->registerTimer(ti.timerId, ti.interval, ti.timerType, q);
@@ -1712,7 +1717,9 @@ int QObject::startTimer(int interval, Qt::TimerType timerType)
         qWarning("QObject::startTimer: Timers cannot have negative intervals");
         return 0;
     }
-    if (Q_UNLIKELY(!d->threadData->hasEventDispatcher())) {
+
+    auto thisThreadData = d->threadData.loadRelaxed();
+    if (Q_UNLIKELY(!thisThreadData->hasEventDispatcher())) {
         qWarning("QObject::startTimer: Timers can only be used with threads started with QThread");
         return 0;
     }
@@ -1720,7 +1727,7 @@ int QObject::startTimer(int interval, Qt::TimerType timerType)
         qWarning("QObject::startTimer: Timers cannot be started from another thread");
         return 0;
     }
-    int timerId = d->threadData->eventDispatcher.loadRelaxed()->registerTimer(interval, timerType, this);
+    int timerId = thisThreadData->eventDispatcher.loadRelaxed()->registerTimer(interval, timerType, this);
     if (!d->extraData)
         d->extraData = new QObjectPrivate::ExtraData;
     d->extraData->runningTimers.append(timerId);
@@ -1794,8 +1801,9 @@ void QObject::killTimer(int id)
             return;
         }
 
-        if (d->threadData->hasEventDispatcher())
-            d->threadData->eventDispatcher.loadRelaxed()->unregisterTimer(id);
+        auto thisThreadData = d->threadData.loadRelaxed();
+        if (thisThreadData->hasEventDispatcher())
+            thisThreadData->eventDispatcher.loadRelaxed()->unregisterTimer(id);
 
         d->extraData->runningTimers.remove(at);
         QAbstractEventDispatcherPrivate::releaseTimerId(id);
@@ -3762,7 +3770,7 @@ void doActivate(QObject *sender, int signal_index, void **argv)
         list = &signalVector->at(-1);
 
     Qt::HANDLE currentThreadId = QThread::currentThreadId();
-    bool inSenderThread = currentThreadId == QObjectPrivate::get(sender)->threadData->threadId.loadRelaxed();
+    bool inSenderThread = currentThreadId == QObjectPrivate::get(sender)->threadData.loadRelaxed()->threadId.loadRelaxed();
 
     // We need to check against the highest connection id to ensure that signals added
     // during the signal emission are not emitted in this emission.
diff --git a/src/corelib/kernel/qobject_p.h b/src/corelib/kernel/qobject_p.h
index db62c03b7a..a421b55764 100644
--- a/src/corelib/kernel/qobject_p.h
+++ b/src/corelib/kernel/qobject_p.h
@@ -362,8 +362,13 @@ public:
     }
 public:
     ExtraData *extraData;    // extra data set by the user
-    QThreadData *getThreadData() const { return threadData; }
-    QThreadData *threadData; // id of the thread that owns the object
+    QThreadData *getThreadData() const { return threadData.loadAcquire(); }
+    // This atomic requires acquire/release semantics in a few places,
+    // e.g. QObject::moveToThread must synchronize with QCoreApplication::postEvent,
+    // because postEvent is thread-safe.
+    // However, most of the code paths involving QObject are only reentrant and
+    // not thread-safe, so synchronization should not be necessary there.
+    QAtomicPointer<QThreadData> threadData; // id of the thread that owns the object
 
     using ConnectionDataPointer = QExplicitlySharedDataPointer<ConnectionData>;
     QAtomicPointer<ConnectionData> connections;
diff --git a/src/corelib/kernel/qsocketnotifier.cpp b/src/corelib/kernel/qsocketnotifier.cpp
index 2a246b1204..78269ee605 100644
--- a/src/corelib/kernel/qsocketnotifier.cpp
+++ b/src/corelib/kernel/qsocketnotifier.cpp
@@ -147,12 +147,14 @@ QSocketNotifier::QSocketNotifier(qintptr socket, Type type, QObject *parent)
     d->sntype = type;
     d->snenabled = true;
 
+    auto thisThreadData = d->threadData.loadRelaxed();
+
     if (socket < 0)
         qWarning("QSocketNotifier: Invalid socket specified");
-    else if (!d->threadData->hasEventDispatcher())
+    else if (!thisThreadData->hasEventDispatcher())
         qWarning("QSocketNotifier: Can only be used with threads started with QThread");
     else
-        d->threadData->eventDispatcher.loadRelaxed()->registerSocketNotifier(this);
+        thisThreadData->eventDispatcher.loadRelaxed()->registerSocketNotifier(this);
 }
 
 /*!
@@ -234,16 +236,19 @@ void QSocketNotifier::setEnabled(bool enable)
         return;
     d->snenabled = enable;
 
-    if (!d->threadData->hasEventDispatcher()) // perhaps application/thread is shutting down
+
+    auto thisThreadData = d->threadData.loadRelaxed();
+
+    if (!thisThreadData->hasEventDispatcher()) // perhaps application/thread is shutting down
         return;
     if (Q_UNLIKELY(thread() != QThread::currentThread())) {
         qWarning("QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread");
         return;
     }
     if (d->snenabled)
-        d->threadData->eventDispatcher.loadRelaxed()->registerSocketNotifier(this);
+        thisThreadData->eventDispatcher.loadRelaxed()->registerSocketNotifier(this);
     else
-        d->threadData->eventDispatcher.loadRelaxed()->unregisterSocketNotifier(this);
+        thisThreadData->eventDispatcher.loadRelaxed()->unregisterSocketNotifier(this);
 }
 
 
diff --git a/src/corelib/kernel/qwineventnotifier.cpp b/src/corelib/kernel/qwineventnotifier.cpp
index d2ae9668fe..db5d44b276 100644
--- a/src/corelib/kernel/qwineventnotifier.cpp
+++ b/src/corelib/kernel/qwineventnotifier.cpp
@@ -124,7 +124,7 @@ QWinEventNotifier::QWinEventNotifier(HANDLE hEvent, QObject *parent)
  : QObject(*new QWinEventNotifierPrivate(hEvent, false), parent)
 {
     Q_D(QWinEventNotifier);
-    QAbstractEventDispatcher *eventDispatcher = d->threadData->eventDispatcher.loadRelaxed();
+    QAbstractEventDispatcher *eventDispatcher = d->threadData.loadRelaxed()->eventDispatcher.loadRelaxed();
     if (Q_UNLIKELY(!eventDispatcher)) {
         qWarning("QWinEventNotifier: Can only be used with threads started with QThread");
         return;
@@ -197,7 +197,7 @@ void QWinEventNotifier::setEnabled(bool enable)
         return;
     d->enabled = enable;
 
-    QAbstractEventDispatcher *eventDispatcher = d->threadData->eventDispatcher.loadRelaxed();
+    QAbstractEventDispatcher *eventDispatcher = d->threadData.loadRelaxed()->eventDispatcher.loadRelaxed();
     if (!eventDispatcher) { // perhaps application is shutting down
         if (!enable && d->waitHandle != nullptr)
             d->unregisterWaitObject();
@@ -256,7 +256,7 @@ void QWinEventNotifierPrivate::unregisterWaitObject()
 static void CALLBACK wfsoCallback(void *context, BOOLEAN /*ignore*/)
 {
     QWinEventNotifierPrivate *nd = reinterpret_cast<QWinEventNotifierPrivate *>(context);
-    QAbstractEventDispatcher *eventDispatcher = nd->threadData->eventDispatcher.loadRelaxed();
+    QAbstractEventDispatcher *eventDispatcher = nd->threadData.loadRelaxed()->eventDispatcher.loadRelaxed();
 
     // Happens when Q(Core)Application is destroyed before QWinEventNotifier.
     // https://bugreports.qt.io/browse/QTBUG-70214
diff --git a/src/corelib/plugin/qlibrary_p.h b/src/corelib/plugin/qlibrary_p.h
index db5afac98e..a58547a2c3 100644
--- a/src/corelib/plugin/qlibrary_p.h
+++ b/src/corelib/plugin/qlibrary_p.h
@@ -96,7 +96,7 @@ public:
     void setLoadHints(QLibrary::LoadHints lh);
 
     static QLibraryPrivate *findOrCreate(const QString &fileName, const QString &version = QString(),
-                                         QLibrary::LoadHints loadHints = nullptr);
+                                         QLibrary::LoadHints loadHints = { });
     static QStringList suffixes_sys(const QString &fullVersion);
     static QStringList prefixes_sys();
 
diff --git a/src/corelib/plugin/qpluginloader.cpp b/src/corelib/plugin/qpluginloader.cpp
index cadff4f32b..c2443dbdda 100644
--- a/src/corelib/plugin/qpluginloader.cpp
+++ b/src/corelib/plugin/qpluginloader.cpp
@@ -305,7 +305,6 @@ static QString locatePlugin(const QString& fileName)
         paths.append(fileName.left(slash)); // don't include the '/'
     } else {
         paths = QCoreApplication::libraryPaths();
-        paths.prepend(QStringLiteral(".")); // search in current dir first
     }
 
     for (const QString &path : qAsConst(paths)) {
diff --git a/src/corelib/serialization/qdatastream.h b/src/corelib/serialization/qdatastream.h
index 20d3953652..cc26f498dc 100644
--- a/src/corelib/serialization/qdatastream.h
+++ b/src/corelib/serialization/qdatastream.h
@@ -316,14 +316,31 @@ template <typename Container>
 QDataStream &writeAssociativeContainer(QDataStream &s, const Container &c)
 {
     s << quint32(c.size());
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
     // Deserialization should occur in the reverse order.
     // Otherwise, value() will return the least recently inserted
     // value instead of the most recently inserted one.
     auto it = c.constEnd();
     auto begin = c.constBegin();
     while (it != begin) {
+        QT_WARNING_PUSH
+        QT_WARNING_DISABLE_DEPRECATED
         --it;
+        QT_WARNING_POP
         s << it.key() << it.value();
+#else
+    auto it = c.constBegin();
+    auto end = c.constEnd();
+    while (it != end) {
+        const auto rangeStart = it++;
+        while (it != end && rangeStart.key() == it.key())
+            ++it;
+        const qint64 last = std::distance(rangeStart, it) - 1;
+        for (qint64 i = last; i >= 0; --i) {
+            auto next = std::next(rangeStart, i);
+            s << next.key() << next.value();
+        }
+#endif
     }
 
     return s;
diff --git a/src/corelib/text/qregularexpression.cpp b/src/corelib/text/qregularexpression.cpp
index 8d2187eb28..d0bdc0d45c 100644
--- a/src/corelib/text/qregularexpression.cpp
+++ b/src/corelib/text/qregularexpression.cpp
@@ -912,7 +912,7 @@ QRegularExpression::QRegularExpression(QRegularExpressionPrivate &dd)
 */
 QRegularExpressionPrivate::QRegularExpressionPrivate()
     : QSharedData(),
-      patternOptions(0),
+      patternOptions(),
       pattern(),
       mutex(),
       compiledPattern(nullptr),
diff --git a/src/corelib/text/qtextboundaryfinder.cpp b/src/corelib/text/qtextboundaryfinder.cpp
index 67dd15377b..070b041220 100644
--- a/src/corelib/text/qtextboundaryfinder.cpp
+++ b/src/corelib/text/qtextboundaryfinder.cpp
@@ -71,7 +71,7 @@ static void init(QTextBoundaryFinder::BoundaryType type, const QChar *chars, int
         }
     }
 
-    QUnicodeTools::CharAttributeOptions options = 0;
+    QUnicodeTools::CharAttributeOptions options;
     switch (type) {
     case QTextBoundaryFinder::Grapheme: options |= QUnicodeTools::GraphemeBreaks; break;
     case QTextBoundaryFinder::Word: options |= QUnicodeTools::WordBreaks; break;
diff --git a/src/corelib/thread/qreadwritelock.cpp b/src/corelib/thread/qreadwritelock.cpp
index 14654986a0..c8463de402 100644
--- a/src/corelib/thread/qreadwritelock.cpp
+++ b/src/corelib/thread/qreadwritelock.cpp
@@ -477,7 +477,7 @@ bool QReadWriteLockPrivate::lockForRead(int timeout)
             if (elapsed > timeout)
                 return false;
             waitingReaders++;
-            readerCond.wait(&mutex, timeout - elapsed);
+            readerCond.wait(&mutex, QDeadlineTimer(timeout - elapsed));
         } else {
             waitingReaders++;
             readerCond.wait(&mutex);
@@ -511,7 +511,7 @@ bool QReadWriteLockPrivate::lockForWrite(int timeout)
                 return false;
             }
             waitingWriters++;
-            writerCond.wait(&mutex, timeout - elapsed);
+            writerCond.wait(&mutex, QDeadlineTimer(timeout - elapsed));
         } else {
             waitingWriters++;
             writerCond.wait(&mutex);
diff --git a/src/corelib/thread/qthread.cpp b/src/corelib/thread/qthread.cpp
index 6a59043881..1248a53160 100644
--- a/src/corelib/thread/qthread.cpp
+++ b/src/corelib/thread/qthread.cpp
@@ -49,6 +49,8 @@
 #include "qthread_p.h"
 #include "private/qcoreapplication_p.h"
 
+#include <limits>
+
 QT_BEGIN_NAMESPACE
 
 /*
@@ -726,7 +728,8 @@ QThread::Priority QThread::priority() const
 */
 
 /*!
-    \fn bool QThread::wait(unsigned long time)
+    \fn bool QThread::wait(QDeadlineTimer deadline)
+    \since 5.15
 
     Blocks the thread until either of these conditions is met:
 
@@ -735,12 +738,14 @@ QThread::Priority QThread::priority() const
        execution (i.e. when it returns from \l{run()}). This function
        will return true if the thread has finished. It also returns
        true if the thread has not been started yet.
-    \li \a time milliseconds has elapsed. If \a time is ULONG_MAX (the
-        default), then the wait will never timeout (the thread must
-        return from \l{run()}). This function will return false if the
-        wait timed out.
+    \li The \a deadline is reached. This function will return false if the
+       deadline is reached.
     \endlist
 
+    A deadline timer set to \c QDeadlineTimer::Forever (the default) will never
+    time out: in this case, the function only returns when the thread returns
+    from \l{run()} or if the thread has not yet started.
+
     This provides similar functionality to the POSIX \c
     pthread_join() function.
 
@@ -833,9 +838,9 @@ void QThread::exit(int returnCode)
     }
 }
 
-bool QThread::wait(unsigned long time)
+bool QThread::wait(QDeadlineTimer deadline)
 {
-    Q_UNUSED(time);
+    Q_UNUSED(deadline);
     return false;
 }
 
@@ -966,6 +971,17 @@ void QThread::setEventDispatcher(QAbstractEventDispatcher *eventDispatcher)
     }
 }
 
+/*!
+    \fn bool QThread::wait(unsigned long time)
+    \overload
+*/
+bool QThread::wait(unsigned long time)
+{
+    if (time == std::numeric_limits<unsigned long>::max())
+        return wait(QDeadlineTimer(QDeadlineTimer::Forever));
+    return wait(QDeadlineTimer(time));
+}
+
 #if QT_CONFIG(thread)
 
 /*!
diff --git a/src/corelib/thread/qthread.h b/src/corelib/thread/qthread.h
index 8141f945b6..635dd94522 100644
--- a/src/corelib/thread/qthread.h
+++ b/src/corelib/thread/qthread.h
@@ -42,6 +42,7 @@
 #define QTHREAD_H
 
 #include <QtCore/qobject.h>
+#include <QtCore/qdeadlinetimer.h>
 
 // For QThread::create. The configure-time test just checks for the availability
 // of std::future and std::async; for the C++17 codepath we perform some extra
@@ -57,8 +58,6 @@
 #  endif
 #endif
 
-#include <limits.h>
-
 QT_BEGIN_NAMESPACE
 
 
@@ -135,8 +134,9 @@ public Q_SLOTS:
     void quit();
 
 public:
-    // default argument causes thread to block indefinetely
-    bool wait(unsigned long time = ULONG_MAX);
+    bool wait(QDeadlineTimer deadline = QDeadlineTimer(QDeadlineTimer::Forever));
+    // ### Qt6 inline this function
+    bool wait(unsigned long time);
 
     static void sleep(unsigned long);
     static void msleep(unsigned long);
diff --git a/src/corelib/thread/qthread_unix.cpp b/src/corelib/thread/qthread_unix.cpp
index 21abe372eb..efa3cb944e 100644
--- a/src/corelib/thread/qthread_unix.cpp
+++ b/src/corelib/thread/qthread_unix.cpp
@@ -771,7 +771,7 @@ void QThread::terminate()
 #endif
 }
 
-bool QThread::wait(unsigned long time)
+bool QThread::wait(QDeadlineTimer deadline)
 {
     Q_D(QThread);
     QMutexLocker locker(&d->mutex);
@@ -785,7 +785,7 @@ bool QThread::wait(unsigned long time)
         return true;
 
     while (d->running) {
-        if (!d->thread_done.wait(locker.mutex(), time))
+        if (!d->thread_done.wait(locker.mutex(), deadline))
             return false;
     }
     return true;
diff --git a/src/corelib/thread/qthread_win.cpp b/src/corelib/thread/qthread_win.cpp
index 996bcf0a71..44cb5653bf 100644
--- a/src/corelib/thread/qthread_win.cpp
+++ b/src/corelib/thread/qthread_win.cpp
@@ -610,7 +610,7 @@ void QThread::terminate()
     QThreadPrivate::finish(this, false);
 }
 
-bool QThread::wait(unsigned long time)
+bool QThread::wait(QDeadlineTimer deadline)
 {
     Q_D(QThread);
     QMutexLocker locker(&d->mutex);
@@ -627,9 +627,9 @@ bool QThread::wait(unsigned long time)
 
     bool ret = false;
 #ifndef Q_OS_WINRT
-    switch (WaitForSingleObject(d->handle, time)) {
+    switch (WaitForSingleObject(d->handle, deadline.remainingTime())) {
 #else
-    switch (WaitForSingleObjectEx(d->handle, time, false)) {
+    switch (WaitForSingleObjectEx(d->handle, deadline.remainingTime(), false)) {
 #endif
     case WAIT_OBJECT_0:
         ret = true;
diff --git a/src/corelib/thread/qthreadpool.cpp b/src/corelib/thread/qthreadpool.cpp
index 4d2389f699..5f23a78c8a 100644
--- a/src/corelib/thread/qthreadpool.cpp
+++ b/src/corelib/thread/qthreadpool.cpp
@@ -136,7 +136,7 @@ void QThreadPoolThread::run()
             manager->waitingThreads.enqueue(this);
             registerThreadInactive();
             // wait for work, exiting after the expiry timeout is reached
-            runnableReady.wait(locker.mutex(), manager->expiryTimeout);
+            runnableReady.wait(locker.mutex(), QDeadlineTimer(manager->expiryTimeout));
             ++manager->activeThreads;
             if (manager->waitingThreads.removeOne(this))
                 expired = true;
diff --git a/src/corelib/thread/qwaitcondition.h b/src/corelib/thread/qwaitcondition.h
index 11520e4cfe..079049af25 100644
--- a/src/corelib/thread/qwaitcondition.h
+++ b/src/corelib/thread/qwaitcondition.h
@@ -40,15 +40,12 @@
 #ifndef QWAITCONDITION_H
 #define QWAITCONDITION_H
 
-#include <QtCore/qglobal.h>
-
-#include <limits.h>
+#include <QtCore/QDeadlineTimer>
 
 QT_BEGIN_NAMESPACE
 
 #if QT_CONFIG(thread)
 
-class QDeadlineTimer;
 class QWaitConditionPrivate;
 class QMutex;
 class QReadWriteLock;
@@ -59,11 +56,16 @@ public:
     QWaitCondition();
     ~QWaitCondition();
 
-    // ### Qt 6: remove unsigned long overloads
-    bool wait(QMutex *lockedMutex, unsigned long time = ULONG_MAX);
-    bool wait(QMutex *lockedMutex, QDeadlineTimer deadline);
-    bool wait(QReadWriteLock *lockedReadWriteLock, unsigned long time = ULONG_MAX);
-    bool wait(QReadWriteLock *lockedReadWriteLock, QDeadlineTimer deadline);
+    bool wait(QMutex *lockedMutex,
+              QDeadlineTimer deadline = QDeadlineTimer(QDeadlineTimer::Forever));
+    bool wait(QReadWriteLock *lockedReadWriteLock,
+              QDeadlineTimer deadline = QDeadlineTimer(QDeadlineTimer::Forever));
+#if QT_DEPRECATED_SINCE(5, 15)
+    QT_DEPRECATED_VERSION_X_5_15("Use wait(QMutex *lockedMutex, QDeadlineTimer deadline) instead")
+    bool wait(QMutex *lockedMutex, unsigned long time);
+    QT_DEPRECATED_VERSION_X_5_15("Use wait(QReadWriteLock *lockedReadWriteLock, QDeadlineTimer deadline) instead")
+    bool wait(QReadWriteLock *lockedReadWriteLock, unsigned long time);
+#endif
 
     void wakeOne();
     void wakeAll();
@@ -80,21 +82,28 @@ private:
 #else
 
 class QMutex;
+class QReadWriteLock;
+
 class Q_CORE_EXPORT QWaitCondition
 {
 public:
     QWaitCondition() {}
     ~QWaitCondition() {}
 
-    bool wait(QMutex *mutex, unsigned long time = ULONG_MAX)
-    {
-        Q_UNUSED(mutex);
-        Q_UNUSED(time);
-        return true;
-    }
+    bool wait(QMutex *, QDeadlineTimer = QDeadlineTimer(QDeadlineTimer::Forever))
+    { return true; }
+    bool wait(QReadWriteLock *, QDeadlineTimer = QDeadlineTimer(QDeadlineTimer::Forever))
+    { return true; }
+#if QT_DEPRECATED_SINCE(5, 15)
+    bool wait(QMutex *, unsigned long) { return true; }
+    bool wait(QReadWriteLock *, unsigned long) { return true; }
+#endif
 
     void wakeOne() {}
     void wakeAll() {}
+
+    void notify_one() { wakeOne(); }
+    void notify_all() { wakeAll(); }
 };
 
 #endif // QT_CONFIG(thread)
diff --git a/src/corelib/thread/qwaitcondition.qdoc b/src/corelib/thread/qwaitcondition.qdoc
index eebc28f059..9da6f6f25c 100644
--- a/src/corelib/thread/qwaitcondition.qdoc
+++ b/src/corelib/thread/qwaitcondition.qdoc
@@ -119,10 +119,22 @@
     \sa wakeOne()
 */
 
+#if QT_DEPRECATED_SINCE(5, 15)
 /*!
     \fn bool QWaitCondition::wait(QMutex *lockedMutex, unsigned long time)
+    \obsolete use wait(QMutex *lockedMutex, QDeadlineTimer deadline) instead
+*/
+/*!
+    \fn bool QWaitCondition::wait(QReadWriteLock *lockedReadWriteLock, unsigned long time)
+    \obsolete use wait(QReadWriteLock *lockedReadWriteLock, QDeadlineTimer deadline) instead
+*/
+#endif
 
-    Releases the \a lockedMutex and waits on the wait condition.  The
+/*!
+    \fn bool QWaitCondition::wait(QMutex *lockedMutex, QDeadlineTimer deadline)
+    \since 5.12
+
+    Releases the \a lockedMutex and waits on the wait condition. The
     \a lockedMutex must be initially locked by the calling thread. If \a
     lockedMutex is not in a locked state, the behavior is undefined. If
     \a lockedMutex is a recursive mutex, this function
@@ -132,10 +144,10 @@
     \list
     \li Another thread signals it using wakeOne() or wakeAll(). This
        function will return true in this case.
-    \li \a time milliseconds has elapsed. If \a time is \c ULONG_MAX
-       (the default), then the wait will never timeout (the event
-       must be signalled). This function will return false if the
-       wait timed out.
+    \li the deadline given by \a deadline is reached. If \a deadline is
+       \c QDeadlineTimer::Forever (the default), then the wait will never
+       timeout (the event must be signalled). This function will return
+       false if the wait timed out.
     \endlist
 
     The \a lockedMutex will be returned to the same locked state. This
@@ -146,8 +158,8 @@
 */
 
 /*!
-    \fn bool QWaitCondition::wait(QReadWriteLock *lockedReadWriteLock, unsigned long time)
-    \since 4.4
+    \fn bool QWaitCondition::wait(QReadWriteLock *lockedReadWriteLock, QDeadlineTimer deadline)
+    \since 5.12
 
     Releases the \a lockedReadWriteLock and waits on the wait
     condition.  The \a lockedReadWriteLock must be initially locked by the
@@ -160,10 +172,10 @@
     \list
     \li Another thread signals it using wakeOne() or wakeAll(). This
        function will return true in this case.
-    \li \a time milliseconds has elapsed. If \a time is \c ULONG_MAX
-       (the default), then the wait will never timeout (the event
-       must be signalled). This function will return false if the
-       wait timed out.
+    \li the deadline given by \a deadline is reached. If \a deadline is
+       \c QDeadlineTimer::Forever (the default), then the wait will never
+       timeout (the event must be signalled). This function will return
+       false if the wait timed out.
     \endlist
 
     The \a lockedReadWriteLock will be returned to the same locked
diff --git a/src/corelib/thread/qwaitcondition_unix.cpp b/src/corelib/thread/qwaitcondition_unix.cpp
index dd7475cec5..a8dfb9999c 100644
--- a/src/corelib/thread/qwaitcondition_unix.cpp
+++ b/src/corelib/thread/qwaitcondition_unix.cpp
@@ -202,12 +202,14 @@ void QWaitCondition::wakeAll()
     report_error(pthread_mutex_unlock(&d->mutex), "QWaitCondition::wakeAll()", "mutex unlock");
 }
 
+#if QT_DEPRECATED_SINCE(5, 15)
 bool QWaitCondition::wait(QMutex *mutex, unsigned long time)
 {
     if (time == std::numeric_limits<unsigned long>::max())
         return wait(mutex, QDeadlineTimer(QDeadlineTimer::Forever));
     return wait(mutex, QDeadlineTimer(time));
 }
+#endif
 
 bool QWaitCondition::wait(QMutex *mutex, QDeadlineTimer deadline)
 {
@@ -229,12 +231,14 @@ bool QWaitCondition::wait(QMutex *mutex, QDeadlineTimer deadline)
     return returnValue;
 }
 
+#if QT_DEPRECATED_SINCE(5, 15)
 bool QWaitCondition::wait(QReadWriteLock *readWriteLock, unsigned long time)
 {
     if (time == std::numeric_limits<unsigned long>::max())
         return wait(readWriteLock, QDeadlineTimer(QDeadlineTimer::Forever));
     return wait(readWriteLock, QDeadlineTimer(time));
 }
+#endif
 
 bool QWaitCondition::wait(QReadWriteLock *readWriteLock, QDeadlineTimer deadline)
 {
diff --git a/src/corelib/time/qdatetime.cpp b/src/corelib/time/qdatetime.cpp
index 95a7255a04..accaea988e 100644
--- a/src/corelib/time/qdatetime.cpp
+++ b/src/corelib/time/qdatetime.cpp
@@ -1213,25 +1213,25 @@ QString QDate::toString(Qt::DateFormat format) const
 
     \table
     \header \li Expression \li Output
-    \row \li d \li the day as number without a leading zero (1 to 31)
-    \row \li dd \li the day as number with a leading zero (01 to 31)
+    \row \li d \li The day as a number without a leading zero (1 to 31)
+    \row \li dd \li The day as a number with a leading zero (01 to 31)
     \row \li ddd
-         \li the abbreviated localized day name (e.g. 'Mon' to 'Sun').
+         \li The abbreviated localized day name (e.g. 'Mon' to 'Sun').
              Uses the system locale to localize the name, i.e. QLocale::system().
     \row \li dddd
-         \li the long localized day name (e.g. 'Monday' to 'Sunday').
+         \li The long localized day name (e.g. 'Monday' to 'Sunday').
              Uses the system locale to localize the name, i.e. QLocale::system().
-    \row \li M \li the month as number without a leading zero (1 to 12)
-    \row \li MM \li the month as number with a leading zero (01 to 12)
+    \row \li M \li The month as a number without a leading zero (1 to 12)
+    \row \li MM \li The month as a number with a leading zero (01 to 12)
     \row \li MMM
-         \li the abbreviated localized month name (e.g. 'Jan' to 'Dec').
+         \li The abbreviated localized month name (e.g. 'Jan' to 'Dec').
              Uses the system locale to localize the name, i.e. QLocale::system().
     \row \li MMMM
-         \li the long localized month name (e.g. 'January' to 'December').
+         \li The long localized month name (e.g. 'January' to 'December').
              Uses the system locale to localize the name, i.e. QLocale::system().
-    \row \li yy \li the year as two digit number (00 to 99)
-    \row \li yyyy \li the year as four digit number. If the year is negative,
-            a minus sign is prepended in addition.
+    \row \li yy \li The year as a two digit number (00 to 99)
+    \row \li yyyy \li The year as a four digit number. If the year is negative,
+            a minus sign is prepended, making five characters.
     \endtable
 
     Any sequence of characters enclosed in single quotes will be included
@@ -1719,11 +1719,15 @@ QDate QDate::fromString(const QString &string, Qt::DateFormat format)
     \row \li MMMM
          \li The long localized month name (e.g. 'January' to 'December').
              Uses the system locale to localize the name, i.e. QLocale::system().
-    \row \li yy \li The year as two digit number (00 to 99)
-    \row \li yyyy \li The year as four digit number. If the year is negative,
-            a minus sign is prepended in addition.
+    \row \li yy \li The year as a two digit number (00 to 99)
+    \row \li yyyy \li The year as a four digit number, possibly plus a leading
+             minus sign for negative years.
     \endtable
 
+    \note Unlike the other version of this function, day and month names must
+    be given in the user's local language. It is only possible to use the English
+    names if the user's language is English.
+
     All other input characters will be treated as text. Any sequence
     of characters that are enclosed in single quotes will also be
     treated as text and will not be used as an expression. For example:
@@ -2063,30 +2067,30 @@ QString QTime::toString(Qt::DateFormat format) const
     \table
     \header \li Expression \li Output
     \row \li h
-         \li the hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
+         \li The hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
     \row \li hh
-         \li the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
+         \li The hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
     \row \li H
-         \li the hour without a leading zero (0 to 23, even with AM/PM display)
+         \li The hour without a leading zero (0 to 23, even with AM/PM display)
     \row \li HH
-         \li the hour with a leading zero (00 to 23, even with AM/PM display)
-    \row \li m \li the minute without a leading zero (0 to 59)
-    \row \li mm \li the minute with a leading zero (00 to 59)
-    \row \li s \li the whole second, without any leading zero (0 to 59)
-    \row \li ss \li the whole second, with a leading zero where applicable (00 to 59)
-    \row \li z \li the fractional part of the second, to go after a decimal
+         \li The hour with a leading zero (00 to 23, even with AM/PM display)
+    \row \li m \li The minute without a leading zero (0 to 59)
+    \row \li mm \li The minute with a leading zero (00 to 59)
+    \row \li s \li The whole second, without any leading zero (0 to 59)
+    \row \li ss \li The whole second, with a leading zero where applicable (00 to 59)
+    \row \li z \li The fractional part of the second, to go after a decimal
                 point, without trailing zeroes (0 to 999).  Thus "\c{s.z}"
                 reports the seconds to full available (millisecond) precision
                 without trailing zeroes.
-    \row \li zzz \li the fractional part of the second, to millisecond
+    \row \li zzz \li The fractional part of the second, to millisecond
                 precision, including trailing zeroes where applicable (000 to 999).
     \row \li AP or A
-         \li use AM/PM display. \e A/AP will be replaced by either
-             QLocale::amText() or QLocale::pmText().
+         \li Use AM/PM display. \e A/AP will be replaced by an upper-case
+             version of either QLocale::amText() or QLocale::pmText().
     \row \li ap or a
-         \li use am/pm display. \e a/ap will be replaced by a lower-case version of
-             QLocale::amText() or QLocale::pmText().
-    \row \li t \li the timezone (for example "CEST")
+         \li Use am/pm display. \e a/ap will be replaced by a lower-case version
+             of either QLocale::amText() or QLocale::pmText().
+    \row \li t \li The timezone (for example "CEST")
     \endtable
 
     Any sequence of characters enclosed in single quotes will be included
@@ -2437,23 +2441,30 @@ QTime QTime::fromString(const QString &string, Qt::DateFormat format)
     \table
     \header \li Expression \li Output
     \row \li h
-         \li the hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
+         \li The hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
     \row \li hh
-         \li the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
-    \row \li m \li the minute without a leading zero (0 to 59)
-    \row \li mm \li the minute with a leading zero (00 to 59)
-    \row \li s \li the whole second, without any leading zero (0 to 59)
-    \row \li ss \li the whole second, with a leading zero where applicable (00 to 59)
-    \row \li z \li the fractional part of the second, to go after a decimal
+         \li The hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
+    \row \li H
+         \li The hour without a leading zero (0 to 23, even with AM/PM display)
+    \row \li HH
+         \li The hour with a leading zero (00 to 23, even with AM/PM display)
+    \row \li m \li The minute without a leading zero (0 to 59)
+    \row \li mm \li The minute with a leading zero (00 to 59)
+    \row \li s \li The whole second, without any leading zero (0 to 59)
+    \row \li ss \li The whole second, with a leading zero where applicable (00 to 59)
+    \row \li z \li The fractional part of the second, to go after a decimal
                 point, without trailing zeroes (0 to 999).  Thus "\c{s.z}"
                 reports the seconds to full available (millisecond) precision
                 without trailing zeroes.
-    \row \li zzz \li the fractional part of the second, to millisecond
+    \row \li zzz \li The fractional part of the second, to millisecond
                 precision, including trailing zeroes where applicable (000 to 999).
-    \row \li AP
-         \li interpret as an AM/PM time. \e AP must be either "AM" or "PM".
-    \row \li ap
-         \li Interpret as an AM/PM time. \e ap must be either "am" or "pm".
+    \row \li AP or A
+         \li Interpret as an AM/PM time. \e A/AP will match an upper-case
+             version of either QLocale::amText() or QLocale::pmText().
+    \row \li ap or a
+         \li Interpret as an am/pm time. \e a/ap will match a lower-case version
+             of either QLocale::amText() or QLocale::pmText().
+    \row \li t \li the timezone (for example "CEST")
     \endtable
 
     All other input characters will be treated as text. Any sequence
@@ -3255,7 +3266,7 @@ inline QDateTime::Data::Data(Qt::TimeSpec spec)
         // the structure is too small, we need to detach
         d = new QDateTimePrivate;
         d->ref.ref();
-        d->m_status = mergeSpec(nullptr, spec);
+        d->m_status = mergeSpec({}, spec);
     }
 }
 
@@ -4358,61 +4369,9 @@ QString QDateTime::toString(Qt::DateFormat format) const
     \fn QString QDateTime::toString(const QString &format) const
     \fn QString QDateTime::toString(QStringView format) const
 
-    Returns the datetime as a string. The \a format parameter
-    determines the format of the result string.
-
-    These expressions may be used for the date:
-
-    \table
-    \header \li Expression \li Output
-    \row \li d \li the day as number without a leading zero (1 to 31)
-    \row \li dd \li the day as number with a leading zero (01 to 31)
-    \row \li ddd
-            \li the abbreviated localized day name (e.g. 'Mon' to 'Sun').
-            Uses the system locale to localize the name, i.e. QLocale::system().
-    \row \li dddd
-            \li the long localized day name (e.g. 'Monday' to 'Sunday').
-            Uses the system locale to localize the name, i.e. QLocale::system().
-    \row \li M \li the month as number without a leading zero (1-12)
-    \row \li MM \li the month as number with a leading zero (01-12)
-    \row \li MMM
-            \li the abbreviated localized month name (e.g. 'Jan' to 'Dec').
-            Uses the system locale to localize the name, i.e. QLocale::system().
-    \row \li MMMM
-            \li the long localized month name (e.g. 'January' to 'December').
-            Uses the system locale to localize the name, i.e. QLocale::system().
-    \row \li yy \li the year as two digit number (00-99)
-    \row \li yyyy \li the year as four digit number
-    \endtable
-
-    These expressions may be used for the time:
-
-    \table
-    \header \li Expression \li Output
-    \row \li h
-         \li the hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
-    \row \li hh
-         \li the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
-    \row \li H
-         \li the hour without a leading zero (0 to 23, even with AM/PM display)
-    \row \li HH
-         \li the hour with a leading zero (00 to 23, even with AM/PM display)
-    \row \li m \li the minute without a leading zero (0 to 59)
-    \row \li mm \li the minute with a leading zero (00 to 59)
-    \row \li s \li the whole second without a leading zero (0 to 59)
-    \row \li ss \li the whole second with a leading zero where applicable (00 to 59)
-    \row \li z \li the fractional part of the second, to go after a decimal
-                point, without trailing zeroes (0 to 999).  Thus "\c{s.z}"
-                reports the seconds to full available (millisecond) precision
-                without trailing zeroes.
-    \row \li zzz \li the fractional part of the second, to millisecond
-                precision, including trailing zeroes where applicable (000 to 999).
-    \row \li AP or A
-         \li use AM/PM display. \e A/AP will be replaced by either "AM" or "PM".
-    \row \li ap or a
-         \li use am/pm display. \e a/ap will be replaced by either "am" or "pm".
-    \row \li t \li the timezone (for example "CEST")
-    \endtable
+    Returns the datetime as a string. The \a format parameter determines the
+    format of the result string. See QTime::toString() and QDate::toString() for
+    the supported specifiers for time and date, respectively.
 
     Any sequence of characters enclosed in single quotes will be included
     verbatim in the output string (stripped of the quotes), even if it contains
@@ -5409,65 +5368,13 @@ QDateTime QDateTime::fromString(const QString &string, Qt::DateFormat format)
     Returns the QDateTime represented by the \a string, using the \a
     format given, or an invalid datetime if the string cannot be parsed.
 
-    Uses the calendar \a cal if supplied, else Gregorian. The illustrative
-    values and ranges below are given for the latter; other calendars may have
-    different ranges or values.
-
-    These expressions may be used for the date part of the format string:
-
-    \table
-    \header \li Expression \li Output
-    \row \li d \li the day as number without a leading zero (1 to 31)
-    \row \li dd \li the day as number with a leading zero (01 to 31)
-    \row \li ddd
-            \li the abbreviated localized day name (e.g. 'Mon' to 'Sun').
-    \row \li dddd
-            \li the long localized day name (e.g. 'Monday' to 'Sunday').
-    \row \li M \li the month as number without a leading zero (1-12)
-    \row \li MM \li the month as number with a leading zero (01-12)
-    \row \li MMM
-            \li the abbreviated localized month name (e.g. 'Jan' to 'Dec').
-    \row \li MMMM
-            \li the long localized month name (e.g. 'January' to 'December').
-    \row \li yy \li the year as two digit number (00-99)
-    \row \li yyyy \li the year as four digit number
-    \endtable
-
-    \note Unlike the other version of this function, day and month names must
-    be given in the user's local language. It is only possible to use the English
-    names if the user's language is English.
+    Uses the calendar \a cal if supplied, else Gregorian.
 
-    These expressions may be used for the time part of the format string:
-
-    \table
-    \header \li Expression \li Output
-    \row \li h
-            \li the hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
-    \row \li hh
-            \li the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
-    \row \li H
-            \li the hour without a leading zero (0 to 23, even with AM/PM display)
-    \row \li HH
-            \li the hour with a leading zero (00 to 23, even with AM/PM display)
-    \row \li m \li the minute without a leading zero (0 to 59)
-    \row \li mm \li the minute with a leading zero (00 to 59)
-    \row \li s \li the whole second without a leading zero (0 to 59)
-    \row \li ss \li the whole second with a leading zero where applicable (00 to 59)
-    \row \li z \li the fractional part of the second, to go after a decimal
-                point, without trailing zeroes (0 to 999).  Thus "\c{s.z}"
-                reports the seconds to full available (millisecond) precision
-                without trailing zeroes.
-    \row \li zzz \li the fractional part of the second, to millisecond
-                precision, including trailing zeroes where applicable (000 to 999).
-    \row \li AP or A
-         \li interpret as an AM/PM time. \e AP must be either "AM" or "PM".
-    \row \li ap or a
-         \li Interpret as an AM/PM time. \e ap must be either "am" or "pm".
-    \endtable
-
-    All other input characters will be treated as text. Any sequence
-    of characters that are enclosed in single quotes will also be
-    treated as text and not be used as an expression.
+    See QDate::fromString() and QTime::fromString() for the expressions
+    recognized in the format string to represent parts of the date and time.
+    All other input characters will be treated as text. Any sequence of
+    characters that are enclosed in single quotes will also be treated as text
+    and not be used as an expression.
 
     \snippet code/src_corelib_tools_qdatetime.cpp 12
 
diff --git a/src/corelib/time/qdatetimeparser.cpp b/src/corelib/time/qdatetimeparser.cpp
index 2c566e3584..70d6f280bf 100644
--- a/src/corelib/time/qdatetimeparser.cpp
+++ b/src/corelib/time/qdatetimeparser.cpp
@@ -407,7 +407,7 @@ bool QDateTimeParser::parseFormat(const QString &newFormat)
     QDTPDEBUGN("parseFormat: %s", newFormat.toLatin1().constData());
 
     QVector<SectionNode> newSectionNodes;
-    Sections newDisplay = 0;
+    Sections newDisplay;
     QStringList newSeparators;
     int i, index = 0;
     int add = 0;
@@ -1799,7 +1799,7 @@ int QDateTimeParser::SectionNode::maxChange() const
 
 QDateTimeParser::FieldInfo QDateTimeParser::fieldInfo(int index) const
 {
-    FieldInfo ret = 0;
+    FieldInfo ret;
     const SectionNode &sn = sectionNode(index);
     switch (sn.type) {
     case MSecSection:
diff --git a/src/corelib/time/qdatetimeparser_p.h b/src/corelib/time/qdatetimeparser_p.h
index d128e35ddc..ff8da956f0 100644
--- a/src/corelib/time/qdatetimeparser_p.h
+++ b/src/corelib/time/qdatetimeparser_p.h
@@ -83,7 +83,7 @@ public:
         DateTimeEdit
     };
     QDateTimeParser(QVariant::Type t, Context ctx, const QCalendar &cal = QCalendar())
-        : currentSectionIndex(-1), display(nullptr), cachedDay(-1), parserType(t),
+        : currentSectionIndex(-1), cachedDay(-1), parserType(t),
         fixday(false), spec(Qt::LocalTime), context(ctx), calendar(cal)
     {
         defaultLocale = QLocale::system();
diff --git a/src/corelib/time/qtimezoneprivate.cpp b/src/corelib/time/qtimezoneprivate.cpp
index 72a0e3c24e..7d6ef0a404 100644
--- a/src/corelib/time/qtimezoneprivate.cpp
+++ b/src/corelib/time/qtimezoneprivate.cpp
@@ -633,7 +633,13 @@ bool QTimeZonePrivate::isValidId(const QByteArray &ianaId)
 
     // Somewhat slack hand-rolled version:
     const int MinSectionLength = 1;
+#if defined(Q_OS_ANDROID) && !defined(Q_OS_ANDROID_EMBEDDED)
+    // Android has its own naming of zones.
+    // "Canada/East-Saskatchewan" has a 17-character second component.
+    const int MaxSectionLength = 17;
+#else
     const int MaxSectionLength = 14;
+#endif
     int sectionLength = 0;
     for (const char *it = ianaId.begin(), * const end = ianaId.end(); it != end; ++it, ++sectionLength) {
         const char ch = *it;
diff --git a/src/corelib/tools/qhash.h b/src/corelib/tools/qhash.h
index 9fd96686f5..045dcf6e18 100644
--- a/src/corelib/tools/qhash.h
+++ b/src/corelib/tools/qhash.h
@@ -322,7 +322,11 @@ public:
         QHashData::Node *i;
 
     public:
+#if QT_DEPRECATED_SINCE(5, 15)
         typedef std::bidirectional_iterator_tag iterator_category;
+#else
+        typedef std::forward_iterator_tag iterator_category;
+#endif
         typedef qptrdiff difference_type;
         typedef T value_type;
         typedef T *pointer;
@@ -347,21 +351,25 @@ public:
             i = QHashData::nextNode(i);
             return r;
         }
-        inline iterator &operator--() {
+#if QT_DEPRECATED_SINCE(5, 15)
+        inline QT_DEPRECATED iterator &operator--()
+        {
             i = QHashData::previousNode(i);
             return *this;
         }
-        inline iterator operator--(int) {
+        inline QT_DEPRECATED iterator operator--(int)
+        {
             iterator r = *this;
             i = QHashData::previousNode(i);
             return r;
         }
-        inline iterator operator+(int j) const
+        inline QT_DEPRECATED iterator operator+(int j) const
         { iterator r = *this; if (j > 0) while (j--) ++r; else while (j++) --r; return r; }
-        inline iterator operator-(int j) const { return operator+(-j); }
-        inline iterator &operator+=(int j) { return *this = *this + j; }
-        inline iterator &operator-=(int j) { return *this = *this - j; }
-        friend inline iterator operator+(int j, iterator k) { return k + j; }
+        inline QT_DEPRECATED iterator operator-(int j) const { return operator+(-j); }
+        inline QT_DEPRECATED iterator &operator+=(int j) { return *this = *this + j; }
+        inline QT_DEPRECATED iterator &operator-=(int j) { return *this = *this - j; }
+        friend inline QT_DEPRECATED iterator operator+(int j, iterator k) { return k + j; }
+#endif
 
         inline bool operator==(const const_iterator &o) const { return i == o.i; }
         inline bool operator!=(const const_iterator &o) const { return i != o.i; }
@@ -376,7 +384,11 @@ public:
         QHashData::Node *i;
 
     public:
+#if QT_DEPRECATED_SINCE(5, 15)
         typedef std::bidirectional_iterator_tag iterator_category;
+#else
+        typedef std::forward_iterator_tag iterator_category;
+#endif
         typedef qptrdiff difference_type;
         typedef T value_type;
         typedef const T *pointer;
@@ -404,21 +416,28 @@ public:
             i = QHashData::nextNode(i);
             return r;
         }
-        inline const_iterator &operator--() {
+#if QT_DEPRECATED_SINCE(5, 15)
+        inline QT_DEPRECATED const_iterator &operator--()
+        {
             i = QHashData::previousNode(i);
             return *this;
         }
-        inline const_iterator operator--(int) {
+        inline QT_DEPRECATED const_iterator operator--(int)
+        {
             const_iterator r = *this;
             i = QHashData::previousNode(i);
             return r;
         }
-        inline const_iterator operator+(int j) const
+        inline QT_DEPRECATED const_iterator operator+(int j) const
         { const_iterator r = *this; if (j > 0) while (j--) ++r; else while (j++) --r; return r; }
-        inline const_iterator operator-(int j) const { return operator+(-j); }
-        inline const_iterator &operator+=(int j) { return *this = *this + j; }
-        inline const_iterator &operator-=(int j) { return *this = *this - j; }
-        friend inline const_iterator operator+(int j, const_iterator k) { return k + j; }
+        inline QT_DEPRECATED const_iterator operator-(int j) const { return operator+(-j); }
+        inline QT_DEPRECATED const_iterator &operator+=(int j) { return *this = *this + j; }
+        inline QT_DEPRECATED const_iterator &operator-=(int j) { return *this = *this - j; }
+        friend inline QT_DEPRECATED const_iterator operator+(int j, const_iterator k)
+        {
+            return k + j;
+        }
+#endif
     };
     friend class const_iterator;
 
@@ -443,8 +462,14 @@ public:
 
         inline key_iterator &operator++() { ++i; return *this; }
         inline key_iterator operator++(int) { return key_iterator(i++);}
-        inline key_iterator &operator--() { --i; return *this; }
-        inline key_iterator operator--(int) { return key_iterator(i--); }
+#if QT_DEPRECATED_SINCE(5, 15)
+        inline QT_DEPRECATED key_iterator &operator--()
+        {
+            --i;
+            return *this;
+        }
+        inline QT_DEPRECATED key_iterator operator--(int) { return key_iterator(i--); }
+#endif
         const_iterator base() const { return i; }
     };
 
@@ -568,12 +593,31 @@ Q_INLINE_TEMPLATE QHash<Key, T> &QHash<Key, T>::unite(const QHash &other)
     if (d == &QHashData::shared_null) {
         *this = other;
     } else {
+#if QT_DEPRECATED_SINCE(5, 15)
         QHash copy(other);
         const_iterator it = copy.constEnd();
         while (it != copy.constBegin()) {
+            QT_WARNING_PUSH
+            QT_WARNING_DISABLE_DEPRECATED
             --it;
+            QT_WARNING_POP
             insertMulti(it.key(), it.value());
         }
+#else
+        QHash copy(other);
+        const_iterator it = copy.cbegin();
+        const const_iterator end = copy.cend();
+        while (it != end) {
+            const auto rangeStart = it++;
+            while (it != end && rangeStart.key() == it.key())
+                ++it;
+            const qint64 last = std::distance(rangeStart, it) - 1;
+            for (qint64 i = last; i >= 0; --i) {
+                auto next = std::next(rangeStart, i);
+                insertMulti(next.key(), next.value());
+            }
+        }
+#endif
     }
     return *this;
 }
@@ -1126,8 +1170,180 @@ Q_INLINE_TEMPLATE int QMultiHash<Key, T>::count(const Key &key, const T &value)
     return n;
 }
 
-Q_DECLARE_ASSOCIATIVE_ITERATOR(Hash)
-Q_DECLARE_MUTABLE_ASSOCIATIVE_ITERATOR(Hash)
+template<class Key, class T>
+class QHashIterator
+{
+    typedef typename QHash<Key, T>::const_iterator const_iterator;
+    typedef const_iterator Item;
+    QHash<Key, T> c;
+    const_iterator i, n;
+    inline bool item_exists() const { return n != c.constEnd(); }
+
+public:
+    inline QHashIterator(const QHash<Key, T> &container)
+        : c(container), i(c.constBegin()), n(c.constEnd())
+    {
+    }
+    inline QHashIterator &operator=(const QHash<Key, T> &container)
+    {
+        c = container;
+        i = c.constBegin();
+        n = c.constEnd();
+        return *this;
+    }
+    inline void toFront()
+    {
+        i = c.constBegin();
+        n = c.constEnd();
+    }
+    inline void toBack()
+    {
+        i = c.constEnd();
+        n = c.constEnd();
+    }
+    inline bool hasNext() const { return i != c.constEnd(); }
+    inline Item next()
+    {
+        n = i++;
+        return n;
+    }
+    inline Item peekNext() const { return i; }
+    inline const T &value() const
+    {
+        Q_ASSERT(item_exists());
+        return *n;
+    }
+    inline const Key &key() const
+    {
+        Q_ASSERT(item_exists());
+        return n.key();
+    }
+    inline bool findNext(const T &t)
+    {
+        while ((n = i) != c.constEnd())
+            if (*i++ == t)
+                return true;
+        return false;
+    }
+#if QT_DEPRECATED_SINCE(5, 15)
+    inline QT_DEPRECATED bool hasPrevious() const { return i != c.constBegin(); }
+    inline QT_DEPRECATED Item previous()
+    {
+        n = --i;
+        return n;
+    }
+    inline QT_DEPRECATED Item peekPrevious() const
+    {
+        const_iterator p = i;
+        return --p;
+    }
+    inline bool QT_DEPRECATED findPrevious(const T &t)
+    {
+        while (i != c.constBegin())
+            if (*(n = --i) == t)
+                return true;
+        n = c.constEnd();
+        return false;
+    }
+#endif
+};
+
+template<class Key, class T>
+class QMutableHashIterator
+{
+    typedef typename QHash<Key, T>::iterator iterator;
+    typedef typename QHash<Key, T>::const_iterator const_iterator;
+    typedef iterator Item;
+    QHash<Key, T> *c;
+    iterator i, n;
+    inline bool item_exists() const { return const_iterator(n) != c->constEnd(); }
+
+public:
+    inline QMutableHashIterator(QHash<Key, T> &container) : c(&container)
+    {
+        i = c->begin();
+        n = c->end();
+    }
+    inline QMutableHashIterator &operator=(QHash<Key, T> &container)
+    {
+        c = &container;
+        i = c->begin();
+        n = c->end();
+        return *this;
+    }
+    inline void toFront()
+    {
+        i = c->begin();
+        n = c->end();
+    }
+    inline void toBack()
+    {
+        i = c->end();
+        n = c->end();
+    }
+    inline bool hasNext() const { return const_iterator(i) != c->constEnd(); }
+    inline Item next()
+    {
+        n = i++;
+        return n;
+    }
+    inline Item peekNext() const { return i; }
+    inline void remove()
+    {
+        if (const_iterator(n) != c->constEnd()) {
+            i = c->erase(n);
+            n = c->end();
+        }
+    }
+    inline void setValue(const T &t)
+    {
+        if (const_iterator(n) != c->constEnd())
+            *n = t;
+    }
+    inline T &value()
+    {
+        Q_ASSERT(item_exists());
+        return *n;
+    }
+    inline const T &value() const
+    {
+        Q_ASSERT(item_exists());
+        return *n;
+    }
+    inline const Key &key() const
+    {
+        Q_ASSERT(item_exists());
+        return n.key();
+    }
+    inline bool findNext(const T &t)
+    {
+        while (const_iterator(n = i) != c->constEnd())
+            if (*i++ == t)
+                return true;
+        return false;
+    }
+#if QT_DEPRECATED_SINCE(5, 15)
+    inline QT_DEPRECATED bool hasPrevious() const { return const_iterator(i) != c->constBegin(); }
+    inline QT_DEPRECATED Item previous()
+    {
+        n = --i;
+        return n;
+    }
+    inline QT_DEPRECATED Item peekPrevious() const
+    {
+        iterator p = i;
+        return --p;
+    }
+    inline QT_DEPRECATED bool findPrevious(const T &t)
+    {
+        while (const_iterator(i) != c->constBegin())
+            if (*(n = --i) == t)
+                return true;
+        n = c->end();
+        return false;
+    }
+#endif
+};
 
 template <class Key, class T>
 uint qHash(const QHash<Key, T> &key, uint seed = 0)
diff --git a/src/corelib/tools/qscopedvaluerollback.h b/src/corelib/tools/qscopedvaluerollback.h
index f904b8dfcb..b8ceff6665 100644
--- a/src/corelib/tools/qscopedvaluerollback.h
+++ b/src/corelib/tools/qscopedvaluerollback.h
@@ -45,7 +45,11 @@
 QT_BEGIN_NAMESPACE
 
 template <typename T>
-class QScopedValueRollback
+class
+#if QT_HAS_CPP_ATTRIBUTE(nodiscard) && __cplusplus >= 201703L
+[[nodiscard]]
+#endif
+QScopedValueRollback
 {
 public:
     explicit QScopedValueRollback(T &var)
diff --git a/src/corelib/tools/qsimd.cpp b/src/corelib/tools/qsimd.cpp
index d7c1d8c4a9..75c380ee8a 100644
--- a/src/corelib/tools/qsimd.cpp
+++ b/src/corelib/tools/qsimd.cpp
@@ -685,7 +685,7 @@ static QT_FUNCTION_TARGET(RDRND) Q_DECL_COLD_FUNCTION bool checkRdrndWorks() noe
     // Check the results for equality
     if (testBuffer[0] == testBuffer[1]
         && testBuffer[0] == testBuffer[2]
-        && end == testBuffer + TestBufferSize && testBuffer[0] == testBuffer[3]) {
+        && (end < testBuffer + TestBufferSize || testBuffer[0] == testBuffer[3])) {
         fprintf(stderr, "WARNING: CPU random generator seem to be failing, "
                         "disabling hardware random number generation\n"
                         "WARNING: RDRND generated:");
diff --git a/src/corelib/tools/qsimd_p.h b/src/corelib/tools/qsimd_p.h
index c28624a25e..26e98c4542 100644
--- a/src/corelib/tools/qsimd_p.h
+++ b/src/corelib/tools/qsimd_p.h
@@ -346,7 +346,7 @@ extern Q_CORE_EXPORT QBasicAtomicInteger<unsigned> qt_cpu_features[2];
 #endif
 Q_CORE_EXPORT quint64 qDetectCpuFeatures();
 
-#if defined(Q_PROCESSOR_X86) && QT_COMPILER_SUPPORTS_HERE(RDRND)
+#if defined(Q_PROCESSOR_X86) && QT_COMPILER_SUPPORTS_HERE(RDRND) && !defined(QT_BOOTSTRAPPED)
 Q_CORE_EXPORT qsizetype qRandomCpu(void *, qsizetype) noexcept;
 #else
 static inline qsizetype qRandomCpu(void *, qsizetype) noexcept