QtCore: port all QMutexLocker users to qt_{scoped,unique}_lock

... except four instances in QCoreApplication that would conflict with
another change.

Replace a locally-defined MutexUnlocker with a call to unlock() +
qScopedGuard'ed lock() to avoid having to spell out the locker type
while we can't depend on C++17 CTAD, yet.

In QSettings, move the new mutex locker into and out of
initDefaultPaths(), such as is idiomatic for std::unique_lock, but
wasn't possible with QMutexLocker (which is not movable).

Change-Id: I23056e13ecaa76159db583c7dccc6e05715e0788
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

13 files changed, 76 insertions, 66 deletions

diff --git a/src/corelib/animation/qpropertyanimation.cpp b/src/corelib/animation/qpropertyanimation.cpp
index a1baa112fc..2a3572d441 100644
--- a/src/corelib/animation/qpropertyanimation.cpp
+++ b/src/corelib/animation/qpropertyanimation.cpp
@@ -85,6 +85,7 @@
 #include "qpropertyanimation_p.h"
 
 #include <QtCore/QMutex>
+#include <QtCore/private/qlocking_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -261,7 +262,7 @@ void QPropertyAnimation::updateState(QAbstractAnimation::State newState,
     QPropertyAnimation *animToStop = 0;
     {
         static QBasicMutex mutex;
-        QMutexLocker locker(&mutex);
+        auto locker = qt_unique_lock(mutex);
         typedef QPair<QObject *, QByteArray> QPropertyAnimationPair;
         typedef QHash<QPropertyAnimationPair, QPropertyAnimation*> QPropertyAnimationHash;
         static QPropertyAnimationHash hash;
diff --git a/src/corelib/animation/qvariantanimation.cpp b/src/corelib/animation/qvariantanimation.cpp
index 01a699c5dc..216c015732 100644
--- a/src/corelib/animation/qvariantanimation.cpp
+++ b/src/corelib/animation/qvariantanimation.cpp
@@ -43,6 +43,7 @@
 #include <QtCore/qrect.h>
 #include <QtCore/qline.h>
 #include <QtCore/qmutex.h>
+#include <QtCore/private/qlocking_p.h>
 
 #include <algorithm>
 
@@ -426,7 +427,7 @@ void QVariantAnimation::registerInterpolator(QVariantAnimation::Interpolator fun
     // in such an order that we get here with interpolators == NULL,
     // to continue causes the app to crash on exit with a SEGV
     if (interpolators) {
-        QMutexLocker locker(&registeredInterpolatorsMutex);
+        const auto locker = qt_scoped_lock(registeredInterpolatorsMutex);
         if (int(interpolationType) >= interpolators->count())
             interpolators->resize(int(interpolationType) + 1);
         interpolators->replace(interpolationType, func);
@@ -443,7 +444,7 @@ QVariantAnimation::Interpolator QVariantAnimationPrivate::getInterpolator(int in
 {
     {
         QInterpolatorVector *interpolators = registeredInterpolators();
-        QMutexLocker locker(&registeredInterpolatorsMutex);
+        const auto locker = qt_scoped_lock(registeredInterpolatorsMutex);
         QVariantAnimation::Interpolator ret = 0;
         if (interpolationType < interpolators->count()) {
             ret = interpolators->at(interpolationType);
diff --git a/src/corelib/global/qglobal.cpp b/src/corelib/global/qglobal.cpp
index dd54ef61dc..dfd5137703 100644
--- a/src/corelib/global/qglobal.cpp
+++ b/src/corelib/global/qglobal.cpp
@@ -52,6 +52,7 @@
 #include <private/qlocale_tools_p.h>
 
 #include <qmutex.h>
+#include <QtCore/private/qlocking_p.h>
 
 #include <stdlib.h>
 #include <limits.h>
@@ -3351,7 +3352,7 @@ static QBasicMutex environmentMutex;
 */
 void qTzSet()
 {
-    QMutexLocker locker(&environmentMutex);
+    const auto locker = qt_scoped_lock(environmentMutex);
 #if defined(Q_OS_WIN)
     _tzset();
 #else
@@ -3365,7 +3366,7 @@ void qTzSet()
 */
 time_t qMkTime(struct tm *when)
 {
-    QMutexLocker locker(&environmentMutex);
+    const auto locker = qt_scoped_lock(environmentMutex);
     return mktime(when);
 }
 
@@ -3397,7 +3398,7 @@ time_t qMkTime(struct tm *when)
 */
 QByteArray qgetenv(const char *varName)
 {
-    QMutexLocker locker(&environmentMutex);
+    const auto locker = qt_scoped_lock(environmentMutex);
 #ifdef Q_CC_MSVC
     size_t requiredSize = 0;
     QByteArray buffer;
@@ -3465,7 +3466,7 @@ QByteArray qgetenv(const char *varName)
 QString qEnvironmentVariable(const char *varName, const QString &defaultValue)
 {
 #if defined(Q_OS_WIN) && !defined(Q_OS_WINRT)
-    QMutexLocker locker(&environmentMutex);
+    const auto locker = qt_scoped_lock(environmentMutex);
     QVarLengthArray<wchar_t, 32> wname(int(strlen(varName)) + 1);
     for (int i = 0; i < wname.size(); ++i) // wname.size() is correct: will copy terminating null
         wname[i] = uchar(varName[i]);
@@ -3513,7 +3514,7 @@ QString qEnvironmentVariable(const char *varName)
 */
 bool qEnvironmentVariableIsEmpty(const char *varName) noexcept
 {
-    QMutexLocker locker(&environmentMutex);
+    const auto locker = qt_scoped_lock(environmentMutex);
 #ifdef Q_CC_MSVC
     // we provide a buffer that can only hold the empty string, so
     // when the env.var isn't empty, we'll get an ERANGE error (buffer
@@ -3552,7 +3553,7 @@ int qEnvironmentVariableIntValue(const char *varName, bool *ok) noexcept
     static const int MaxDigitsForOctalInt =
         (std::numeric_limits<uint>::digits + NumBinaryDigitsPerOctalDigit - 1) / NumBinaryDigitsPerOctalDigit;
 
-    QMutexLocker locker(&environmentMutex);
+    const auto locker = qt_scoped_lock(environmentMutex);
 #ifdef Q_CC_MSVC
     // we provide a buffer that can hold any int value:
     char buffer[MaxDigitsForOctalInt + 2]; // +1 for NUL +1 for optional '-'
@@ -3617,7 +3618,7 @@ int qEnvironmentVariableIntValue(const char *varName, bool *ok) noexcept
 */
 bool qEnvironmentVariableIsSet(const char *varName) noexcept
 {
-    QMutexLocker locker(&environmentMutex);
+    const auto locker = qt_scoped_lock(environmentMutex);
 #ifdef Q_CC_MSVC
     size_t requiredSize = 0;
     (void)getenv_s(&requiredSize, 0, 0, varName);
@@ -3647,7 +3648,7 @@ bool qEnvironmentVariableIsSet(const char *varName) noexcept
 */
 bool qputenv(const char *varName, const QByteArray& value)
 {
-    QMutexLocker locker(&environmentMutex);
+    const auto locker = qt_scoped_lock(environmentMutex);
 #if defined(Q_CC_MSVC)
     return _putenv_s(varName, value.constData()) == 0;
 #elif (defined(_POSIX_VERSION) && (_POSIX_VERSION-0) >= 200112L) || defined(Q_OS_HAIKU)
@@ -3678,7 +3679,7 @@ bool qputenv(const char *varName, const QByteArray& value)
 */
 bool qunsetenv(const char *varName)
 {
-    QMutexLocker locker(&environmentMutex);
+    const auto locker = qt_scoped_lock(environmentMutex);
 #if defined(Q_CC_MSVC)
     return _putenv_s(varName, "") == 0;
 #elif (defined(_POSIX_VERSION) && (_POSIX_VERSION-0) >= 200112L) || defined(Q_OS_BSD4) || defined(Q_OS_HAIKU)
diff --git a/src/corelib/global/qlogging.cpp b/src/corelib/global/qlogging.cpp
index 621b6d7d13..491823f217 100644
--- a/src/corelib/global/qlogging.cpp
+++ b/src/corelib/global/qlogging.cpp
@@ -49,6 +49,7 @@
 #include "qvarlengtharray.h"
 #include "qdebug.h"
 #include "qmutex.h"
+#include <QtCore/private/qlocking_p.h>
 #include "qloggingcategory.h"
 #ifndef QT_BOOTSTRAPPED
 #include "qelapsedtimer.h"
@@ -1375,7 +1376,7 @@ QString qFormatLogMessage(QtMsgType type, const QMessageLogContext &context, con
 {
     QString message;
 
-    QMutexLocker lock(&QMessagePattern::mutex);
+    const auto locker = qt_scoped_lock(QMessagePattern::mutex);
 
     QMessagePattern *pattern = qMessagePattern();
     if (!pattern) {
@@ -2091,7 +2092,7 @@ QtMsgHandler qInstallMsgHandler(QtMsgHandler h)
 
 void qSetMessagePattern(const QString &pattern)
 {
-    QMutexLocker lock(&QMessagePattern::mutex);
+    const auto locker = qt_scoped_lock(QMessagePattern::mutex);
 
     if (!qMessagePattern()->fromEnvironment)
         qMessagePattern()->setPattern(pattern);
diff --git a/src/corelib/io/qfileselector.cpp b/src/corelib/io/qfileselector.cpp
index 500b475d1d..31c490de66 100644
--- a/src/corelib/io/qfileselector.cpp
+++ b/src/corelib/io/qfileselector.cpp
@@ -44,7 +44,7 @@
 #include <QtCore/QFile>
 #include <QtCore/QDir>
 #include <QtCore/QMutex>
-#include <QtCore/QMutexLocker>
+#include <QtCore/private/qlocking_p.h>
 #include <QtCore/QUrl>
 #include <QtCore/QFileInfo>
 #include <QtCore/QLocale>
@@ -312,7 +312,7 @@ void QFileSelector::setExtraSelectors(const QStringList &list)
 QStringList QFileSelector::allSelectors() const
 {
     Q_D(const QFileSelector);
-    QMutexLocker locker(&sharedDataMutex);
+    const auto locker = qt_scoped_lock(sharedDataMutex);
     QFileSelectorPrivate::updateSelectors();
     return d->extras + sharedData->staticSelectors;
 }
@@ -371,7 +371,7 @@ QStringList QFileSelectorPrivate::platformSelectors()
 
 void QFileSelectorPrivate::addStatics(const QStringList &statics)
 {
-    QMutexLocker locker(&sharedDataMutex);
+    const auto locker = qt_scoped_lock(sharedDataMutex);
     sharedData->preloadedStatics << statics;
     sharedData->staticSelectors.clear();
 }
diff --git a/src/corelib/io/qfilesystemwatcher_win.cpp b/src/corelib/io/qfilesystemwatcher_win.cpp
index c22a003931..5f91ce5e3d 100644
--- a/src/corelib/io/qfilesystemwatcher_win.cpp
+++ b/src/corelib/io/qfilesystemwatcher_win.cpp
@@ -48,6 +48,7 @@
 #include <qdatetime.h>
 #include <qdir.h>
 #include <qtextstream.h>
+#include <private/qlocking_p.h>
 
 #include <qt_windows.h>
 
@@ -423,7 +424,7 @@ QStringList QWindowsFileSystemWatcherEngine::addPaths(const QStringList &paths,
         end = threads.constEnd();
         for(jt = threads.constBegin(); jt != end; ++jt) {
             thread = *jt;
-            QMutexLocker locker(&(thread->mutex));
+            const auto locker = qt_scoped_lock(thread->mutex);
 
             const auto hit = thread->handleForDir.find(QFileSystemWatcherPathKey(absolutePath));
             if (hit != thread->handleForDir.end() && hit.value().flags < flags) {
@@ -478,7 +479,7 @@ QStringList QWindowsFileSystemWatcherEngine::addPaths(const QStringList &paths,
             // now look for a thread to insert
             bool found = false;
             for (QWindowsFileSystemWatcherEngineThread *thread : qAsConst(threads)) {
-                QMutexLocker locker(&(thread->mutex));
+                const auto locker = qt_scoped_lock(thread->mutex);
                 if (thread->handles.count() < MAXIMUM_WAIT_OBJECTS) {
                     DEBUG() << "Added handle" << handle.handle << "for" << absolutePath << "to watch" << fileInfo.absoluteFilePath()
                             << "to existing thread " << thread;
@@ -554,7 +555,7 @@ QStringList QWindowsFileSystemWatcherEngine::removePaths(const QStringList &path
             if (*jt == 0)
                 continue;
 
-            QMutexLocker locker(&(thread->mutex));
+            auto locker = qt_unique_lock(thread->mutex);
 
             QWindowsFileSystemWatcherEngine::Handle handle = thread->handleForDir.value(QFileSystemWatcherPathKey(absolutePath));
             if (handle.handle == INVALID_HANDLE_VALUE) {
@@ -587,7 +588,7 @@ QStringList QWindowsFileSystemWatcherEngine::removePaths(const QStringList &path
                             locker.unlock();
                             thread->stop();
                             thread->wait();
-                            locker.relock();
+                            locker.lock();
                             // We can't delete the thread until the mutex locker is
                             // out of scope
                         }
@@ -652,13 +653,13 @@ static QString msgFindNextFailed(const QWindowsFileSystemWatcherEngineThread::Pa
 
 void QWindowsFileSystemWatcherEngineThread::run()
 {
-    QMutexLocker locker(&mutex);
+    auto locker = qt_unique_lock(mutex);
     forever {
         QVector<HANDLE> handlesCopy = handles;
         locker.unlock();
         DEBUG() << "QWindowsFileSystemWatcherThread" << this << "waiting on" << handlesCopy.count() << "handles";
         DWORD r = WaitForMultipleObjects(handlesCopy.count(), handlesCopy.constData(), false, INFINITE);
-        locker.relock();
+        locker.lock();
         do {
             if (r == WAIT_OBJECT_0) {
                 int m = msg;
diff --git a/src/corelib/io/qloggingregistry.cpp b/src/corelib/io/qloggingregistry.cpp
index 7849dfd14c..e8eb18b4c1 100644
--- a/src/corelib/io/qloggingregistry.cpp
+++ b/src/corelib/io/qloggingregistry.cpp
@@ -41,6 +41,7 @@
 
 #include <QtCore/qfile.h>
 #include <QtCore/qlibraryinfo.h>
+#include <QtCore/private/qlocking_p.h>
 #include <QtCore/qstandardpaths.h>
 #include <QtCore/qtextstream.h>
 #include <QtCore/qdir.h>
@@ -356,7 +357,7 @@ void QLoggingRegistry::initializeRules()
 */
 void QLoggingRegistry::registerCategory(QLoggingCategory *cat, QtMsgType enableForLevel)
 {
-    QMutexLocker locker(&registryMutex);
+    const auto locker = qt_scoped_lock(registryMutex);
 
     if (!categories.contains(cat)) {
         categories.insert(cat, enableForLevel);
@@ -370,7 +371,7 @@ void QLoggingRegistry::registerCategory(QLoggingCategory *cat, QtMsgType enableF
 */
 void QLoggingRegistry::unregisterCategory(QLoggingCategory *cat)
 {
-    QMutexLocker locker(&registryMutex);
+    const auto locker = qt_scoped_lock(registryMutex);
     categories.remove(cat);
 }
 
@@ -413,7 +414,7 @@ void QLoggingRegistry::updateRules()
 QLoggingCategory::CategoryFilter
 QLoggingRegistry::installFilter(QLoggingCategory::CategoryFilter filter)
 {
-    QMutexLocker locker(&registryMutex);
+    const auto locker = qt_scoped_lock(registryMutex);
 
     if (!filter)
         filter = defaultCategoryFilter;
diff --git a/src/corelib/io/qprocess_unix.cpp b/src/corelib/io/qprocess_unix.cpp
index 951fc4ccaa..0c80daa024 100644
--- a/src/corelib/io/qprocess_unix.cpp
+++ b/src/corelib/io/qprocess_unix.cpp
@@ -89,6 +89,7 @@ QT_END_NAMESPACE
 #include "qprocess_p.h"
 #include "qstandardpaths.h"
 #include "private/qcore_unix_p.h"
+#include "private/qlocking_p.h"
 
 #ifdef Q_OS_MAC
 #include <private/qcore_mac_p.h>
@@ -404,7 +405,7 @@ void QProcessPrivate::startProcess()
             // CFBundle is not reentrant, since CFBundleCreate might return a reference
             // to a cached bundle object. Protect the bundle calls with a mutex lock.
             static QBasicMutex cfbundleMutex;
-            QMutexLocker lock(&cfbundleMutex);
+            const auto locker = qt_scoped_lock(cfbundleMutex);
             QCFType<CFBundleRef> bundle = CFBundleCreate(0, url);
             // 'executableURL' can be either relative or absolute ...
             QCFType<CFURLRef> executableURL = CFBundleCopyExecutableURL(bundle);
diff --git a/src/corelib/io/qsettings.cpp b/src/corelib/io/qsettings.cpp
index accde01f16..4a119a1e2f 100644
--- a/src/corelib/io/qsettings.cpp
+++ b/src/corelib/io/qsettings.cpp
@@ -47,6 +47,7 @@
 #include "qdir.h"
 #include "qfileinfo.h"
 #include "qmutex.h"
+#include "private/qlocking_p.h"
 #include "qlibraryinfo.h"
 #include "qtemporaryfile.h"
 #include "qstandardpaths.h"
@@ -210,7 +211,7 @@ QConfFile *QConfFile::fromName(const QString &fileName, bool _userPerms)
     ConfFileCache *unusedCache = unusedCacheFunc();
 
     QConfFile *confFile = 0;
-    QMutexLocker locker(&settingsGlobalMutex);
+    const auto locker = qt_scoped_lock(settingsGlobalMutex);
 
     if (!(confFile = usedHash->value(absPath))) {
         if ((confFile = unusedCache->take(absPath)))
@@ -225,7 +226,7 @@ QConfFile *QConfFile::fromName(const QString &fileName, bool _userPerms)
 
 void QConfFile::clearCache()
 {
-    QMutexLocker locker(&settingsGlobalMutex);
+    const auto locker = qt_scoped_lock(settingsGlobalMutex);
     unusedCacheFunc()->clear();
 }
 
@@ -937,7 +938,7 @@ void QConfFileSettingsPrivate::initFormat()
 #endif
 
     if (format > QSettings::IniFormat) {
-        QMutexLocker locker(&settingsGlobalMutex);
+        const auto locker = qt_scoped_lock(settingsGlobalMutex);
         const CustomFormatVector *customFormatVector = customFormatVectorFunc();
 
         int i = (int)format - (int)QSettings::CustomFormat1;
@@ -1052,11 +1053,11 @@ static QString make_user_path()
 }
 #endif // !Q_OS_WIN
 
-static void initDefaultPaths(QMutexLocker *locker)
+static std::unique_lock<QBasicMutex> initDefaultPaths(std::unique_lock<QBasicMutex> locker)
 {
     PathHash *pathHash = pathHashFunc();
 
-    locker->unlock();
+    locker.unlock();
 
     /*
        QLibraryInfo::location() uses QSettings, so in order to
@@ -1065,7 +1066,7 @@ static void initDefaultPaths(QMutexLocker *locker)
     */
     QString systemPath = QLibraryInfo::location(QLibraryInfo::SettingsPath) + QLatin1Char('/');
 
-    locker->relock();
+    locker.lock();
     if (pathHash->isEmpty()) {
         /*
            Lazy initialization of pathHash. We initialize the
@@ -1096,6 +1097,8 @@ static void initDefaultPaths(QMutexLocker *locker)
 #endif
 #endif // Q_OS_WIN
     }
+
+    return locker;
 }
 
 static Path getPath(QSettings::Format format, QSettings::Scope scope)
@@ -1103,10 +1106,10 @@ static Path getPath(QSettings::Format format, QSettings::Scope scope)
     Q_ASSERT((int)QSettings::NativeFormat == 0);
     Q_ASSERT((int)QSettings::IniFormat == 1);
 
-    QMutexLocker locker(&settingsGlobalMutex);
+    auto locker = qt_unique_lock(settingsGlobalMutex);
     PathHash *pathHash = pathHashFunc();
     if (pathHash->isEmpty())
-        initDefaultPaths(&locker);
+        locker = initDefaultPaths(std::move(locker));
 
     Path result = pathHash->value(pathHashKey(format, scope));
     if (!result.path.isEmpty())
@@ -1120,7 +1123,7 @@ static Path getPath(QSettings::Format format, QSettings::Scope scope)
 // Note: Suitable only for autotests.
 void Q_AUTOTEST_EXPORT clearDefaultPaths()
 {
-    QMutexLocker locker(&settingsGlobalMutex);
+    const auto locker = qt_scoped_lock(settingsGlobalMutex);
     pathHashFunc()->clear();
 }
 #endif // QT_BUILD_INTERNAL && Q_XDG_PLATFORM && !QT_NO_STANDARDPATHS
@@ -1200,7 +1203,7 @@ QConfFileSettingsPrivate::QConfFileSettingsPrivate(const QString &fileName,
 
 QConfFileSettingsPrivate::~QConfFileSettingsPrivate()
 {
-    QMutexLocker locker(&settingsGlobalMutex);
+    const auto locker = qt_scoped_lock(settingsGlobalMutex);
     ConfFileHash *usedHash = usedHashFunc();
     ConfFileCache *unusedCache = unusedCacheFunc();
 
@@ -1239,7 +1242,7 @@ void QConfFileSettingsPrivate::remove(const QString &key)
 
     QSettingsKey theKey(key, caseSensitivity);
     QSettingsKey prefix(key + QLatin1Char('/'), caseSensitivity);
-    QMutexLocker locker(&confFile->mutex);
+    const auto locker = qt_scoped_lock(confFile->mutex);
 
     ensureSectionParsed(confFile, theKey);
     ensureSectionParsed(confFile, prefix);
@@ -1267,7 +1270,7 @@ void QConfFileSettingsPrivate::set(const QString &key, const QVariant &value)
     QConfFile *confFile = confFiles.at(0);
 
     QSettingsKey theKey(key, caseSensitivity, nextPosition++);
-    QMutexLocker locker(&confFile->mutex);
+    const auto locker = qt_scoped_lock(confFile->mutex);
     confFile->removedKeys.remove(theKey);
     confFile->addedKeys.insert(theKey, value);
 }
@@ -1279,7 +1282,7 @@ bool QConfFileSettingsPrivate::get(const QString &key, QVariant *value) const
     bool found = false;
 
     for (auto confFile : qAsConst(confFiles)) {
-        QMutexLocker locker(&confFile->mutex);
+        const auto locker = qt_scoped_lock(confFile->mutex);
 
         if (!confFile->addedKeys.isEmpty()) {
             j = confFile->addedKeys.constFind(theKey);
@@ -1312,7 +1315,7 @@ QStringList QConfFileSettingsPrivate::children(const QString &prefix, ChildSpec
     int startPos = prefix.size();
 
     for (auto confFile : qAsConst(confFiles)) {
-        QMutexLocker locker(&confFile->mutex);
+        const auto locker = qt_scoped_lock(confFile->mutex);
 
         if (thePrefix.isEmpty())
             ensureAllSectionsParsed(confFile);
@@ -1351,7 +1354,7 @@ void QConfFileSettingsPrivate::clear()
     // Note: First config file is always the most specific.
     QConfFile *confFile = confFiles.at(0);
 
-    QMutexLocker locker(&confFile->mutex);
+    const auto locker = qt_scoped_lock(confFile->mutex);
     ensureAllSectionsParsed(confFile);
     confFile->addedKeys.clear();
     confFile->removedKeys = confFile->originalKeys;
@@ -1363,7 +1366,7 @@ void QConfFileSettingsPrivate::sync()
     // error we just try to go on and make the best of it
 
     for (auto confFile : qAsConst(confFiles)) {
-        QMutexLocker locker(&confFile->mutex);
+        const auto locker = qt_scoped_lock(confFile->mutex);
         syncConfFile(confFile);
     }
 }
@@ -3521,10 +3524,10 @@ void QSettings::setUserIniPath(const QString &dir)
 */
 void QSettings::setPath(Format format, Scope scope, const QString &path)
 {
-    QMutexLocker locker(&settingsGlobalMutex);
+    auto locker = qt_unique_lock(settingsGlobalMutex);
     PathHash *pathHash = pathHashFunc();
     if (pathHash->isEmpty())
-        initDefaultPaths(&locker);
+        locker = initDefaultPaths(std::move(locker));
     pathHash->insert(pathHashKey(format, scope), Path(path + QDir::separator(), true));
 }
 
@@ -3604,7 +3607,7 @@ QSettings::Format QSettings::registerFormat(const QString &extension, ReadFunc r
     Q_ASSERT(caseSensitivity == Qt::CaseSensitive);
 #endif
 
-    QMutexLocker locker(&settingsGlobalMutex);
+    const auto locker = qt_scoped_lock(settingsGlobalMutex);
     CustomFormatVector *customFormatVector = customFormatVectorFunc();
     int index = customFormatVector->size();
     if (index == 16) // the QSettings::Format enum has room for 16 custom formats
diff --git a/src/corelib/kernel/qcore_mac.cpp b/src/corelib/kernel/qcore_mac.cpp
index b048576f5b..e59835be48 100644
--- a/src/corelib/kernel/qcore_mac.cpp
+++ b/src/corelib/kernel/qcore_mac.cpp
@@ -44,6 +44,7 @@
 #include "qpair.h"
 #include "qmutex.h"
 #include "qvarlengtharray.h"
+#include "private/qlocking_p.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -135,7 +136,7 @@ os_log_type_t AppleUnifiedLogger::logTypeForMessageType(QtMsgType msgType)
 os_log_t AppleUnifiedLogger::cachedLog(const QString &subsystem, const QString &category)
 {
     static QBasicMutex mutex;
-    QMutexLocker locker(&mutex);
+    const auto locker = qt_scoped_lock(mutex);
 
     static QHash<QPair<QString, QString>, os_log_t> logs;
     const auto cacheKey = qMakePair(subsystem, category);
diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index 87dae896fa..6647ea99f5 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -55,6 +55,7 @@
 #include <qfileinfo.h>
 #include <qmutex.h>
 #include <private/qloggingregistry_p.h>
+#include <qscopeguard.h>
 #include <qstandardpaths.h>
 #ifndef QT_NO_QOBJECT
 #include <qthread.h>
@@ -70,6 +71,7 @@
 #include <private/qfactoryloader_p.h>
 #include <private/qfunctions_p.h>
 #include <private/qlocale_p.h>
+#include <private/qlocking_p.h>
 #include <private/qhooks_p.h>
 
 #ifndef QT_NO_QOBJECT
@@ -294,7 +296,7 @@ void qAddPreRoutine(QtStartUpFunction p)
 
     // Due to C++11 parallel dynamic initialization, this can be called
     // from multiple threads.
-    QMutexLocker locker(&globalRoutinesMutex);
+    const auto locker = qt_scoped_lock(globalRoutinesMutex);
     list->prepend(p); // in case QCoreApplication is re-created, see qt_call_pre_routines
 }
 
@@ -303,7 +305,7 @@ void qAddPostRoutine(QtCleanUpFunction p)
     QVFuncList *list = postRList();
     if (!list)
         return;
-    QMutexLocker locker(&globalRoutinesMutex);
+    const auto locker = qt_scoped_lock(globalRoutinesMutex);
     list->prepend(p);
 }
 
@@ -312,7 +314,7 @@ void qRemovePostRoutine(QtCleanUpFunction p)
     QVFuncList *list = postRList();
     if (!list)
         return;
-    QMutexLocker locker(&globalRoutinesMutex);
+    const auto locker = qt_scoped_lock(globalRoutinesMutex);
     list->removeAll(p);
 }
 
@@ -323,7 +325,7 @@ static void qt_call_pre_routines()
 
     QVFuncList list;
     {
-        QMutexLocker locker(&globalRoutinesMutex);
+        const auto locker = qt_scoped_lock(globalRoutinesMutex);
         // Unlike qt_call_post_routines, we don't empty the list, because
         // Q_COREAPP_STARTUP_FUNCTION is a macro, so the user expects
         // the function to be executed every time QCoreApplication is created.
@@ -342,7 +344,7 @@ void Q_CORE_EXPORT qt_call_post_routines()
         QVFuncList list;
         {
             // extract the current list and make the stored list empty
-            QMutexLocker locker(&globalRoutinesMutex);
+            const auto locker = qt_scoped_lock(globalRoutinesMutex);
             qSwap(*postRList, list);
         }
 
@@ -522,7 +524,7 @@ void QCoreApplicationPrivate::cleanupThreadData()
 #endif
 
         // need to clear the state of the mainData, just in case a new QCoreApplication comes along.
-        QMutexLocker locker(&threadData->postEventList.mutex);
+        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);
             if (pe.event) {
@@ -1705,7 +1707,7 @@ void QCoreApplicationPrivate::sendPostedEvents(QObject *receiver, int event_type
 
     ++data->postEventList.recursion;
 
-    QMutexLocker locker(&data->postEventList.mutex);
+    auto locker = qt_unique_lock(data->postEventList.mutex);
 
     // by default, we assume that the event dispatcher can go to sleep after
     // processing all events. if any new events are posted while we send
@@ -1821,13 +1823,8 @@ void QCoreApplicationPrivate::sendPostedEvents(QObject *receiver, int event_type
         // for the next event.
         const_cast<QPostEvent &>(pe).event = 0;
 
-        struct MutexUnlocker
-        {
-            QMutexLocker &m;
-            MutexUnlocker(QMutexLocker &m) : m(m) { m.unlock(); }
-            ~MutexUnlocker() { m.relock(); }
-        };
-        MutexUnlocker unlocker(locker);
+        locker.unlock();
+        const auto relocker = qScopeGuard([&locker] { locker.lock(); });
 
         QScopedPointer<QEvent> event_deleter(e); // will delete the event (with the mutex unlocked)
 
@@ -1864,7 +1861,7 @@ void QCoreApplicationPrivate::sendPostedEvents(QObject *receiver, int event_type
 void QCoreApplication::removePostedEvents(QObject *receiver, int eventType)
 {
     QThreadData *data = receiver ? receiver->d_func()->threadData : QThreadData::current();
-    QMutexLocker locker(&data->postEventList.mutex);
+    auto locker = qt_unique_lock(data->postEventList.mutex);
 
     // the QObject destructor calls this function directly.  this can
     // happen while the event loop is in the middle of posting events,
@@ -1927,7 +1924,7 @@ void QCoreApplicationPrivate::removePostedEvent(QEvent * event)
 
     QThreadData *data = QThreadData::current();
 
-    QMutexLocker locker(&data->postEventList.mutex);
+    const auto locker = qt_scoped_lock(data->postEventList.mutex);
 
     if (data->postEventList.size() == 0) {
 #if defined(QT_DEBUG)
diff --git a/src/corelib/kernel/qcoreapplication_win.cpp b/src/corelib/kernel/qcoreapplication_win.cpp
index 822b68cf62..961b96710e 100644
--- a/src/corelib/kernel/qcoreapplication_win.cpp
+++ b/src/corelib/kernel/qcoreapplication_win.cpp
@@ -47,6 +47,7 @@
 #ifndef QT_NO_QOBJECT
 #include "qmutex.h"
 #include <private/qthread_p.h>
+#include <private/qlocking_p.h>
 #endif
 #include "qtextstream.h"
 #include <ctype.h>
@@ -919,7 +920,7 @@ void QCoreApplicationPrivate::removePostedTimerEvent(QObject *object, int timerI
 {
     QThreadData *data = object->d_func()->threadData;
 
-    QMutexLocker locker(&data->postEventList.mutex);
+    const auto locker = qt_scoped_lock(data->postEventList.mutex);
     if (data->postEventList.size() == 0)
         return;
     for (int i = 0; i < data->postEventList.size(); ++i) {
diff --git a/src/corelib/text/qregexp.cpp b/src/corelib/text/qregexp.cpp
index d81826b47b..41f3508ff8 100644
--- a/src/corelib/text/qregexp.cpp
+++ b/src/corelib/text/qregexp.cpp
@@ -52,6 +52,7 @@
 #include "qstringlist.h"
 #include "qstringmatcher.h"
 #include "qvector.h"
+#include "private/qlocking_p.h"
 
 #include <limits.h>
 #include <algorithm>
@@ -3825,7 +3826,7 @@ static QBasicMutex engineCacheMutex;
 static void derefEngine(QRegExpEngine *eng, const QRegExpEngineKey &key)
 {
 #if !defined(QT_NO_REGEXP_OPTIM)
-    QMutexLocker locker(&engineCacheMutex);
+    const auto locker = qt_scoped_lock(engineCacheMutex);
     if (!eng->ref.deref()) {
         if (QRECache *c = engineCache()) {
             c->unusedEngines.insert(key, eng, 4 + key.pattern.length() / 4);
@@ -3846,7 +3847,7 @@ static void prepareEngine_helper(QRegExpPrivate *priv)
     Q_ASSERT(!priv->eng);
 
 #if !defined(QT_NO_REGEXP_OPTIM)
-    QMutexLocker locker(&engineCacheMutex);
+    const auto locker = qt_scoped_lock(engineCacheMutex);
     if (QRECache *c = engineCache()) {
         priv->eng = c->unusedEngines.take(priv->engineKey);
         if (!priv->eng)