CoreLib: use const (and const APIs) more

For CoW types const methods will be called.

Mark store_persistent_indexes() as const,
because this method does not modify the object.

Change-Id: Ic867913b4fb5aaebfbaaffe1d3be45cf7b646403
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

20 files changed, 44 insertions, 40 deletions

diff --git a/src/corelib/io/qsettings_mac.cpp b/src/corelib/io/qsettings_mac.cpp
index ceee165459..d73cc4d298 100644
--- a/src/corelib/io/qsettings_mac.cpp
+++ b/src/corelib/io/qsettings_mac.cpp
@@ -149,7 +149,7 @@ static QCFType<CFPropertyListRef> macValue(const QVariant &value)
 
                 bool singleton = (values.count() == 1);
                 if (singleton) {
-                    switch (values.first().type()) {
+                    switch (values.constFirst().type()) {
                     // should be same as above (look for LIST)
                     case QVariant::List:
                     case QVariant::StringList:
@@ -161,7 +161,7 @@ static QCFType<CFPropertyListRef> macValue(const QVariant &value)
                 }
 
                 cfkeys[numUniqueKeys] = QCFString::toCFStringRef(key);
-                cfvalues[numUniqueKeys] = singleton ? macValue(values.first()) : macList(values);
+                cfvalues[numUniqueKeys] = singleton ? macValue(values.constFirst()) : macList(values);
                 ++numUniqueKeys;
             }
 
diff --git a/src/corelib/io/qstandardpaths_mac.mm b/src/corelib/io/qstandardpaths_mac.mm
index 33c34d41af..f08a6dac53 100644
--- a/src/corelib/io/qstandardpaths_mac.mm
+++ b/src/corelib/io/qstandardpaths_mac.mm
@@ -273,7 +273,7 @@ QString QStandardPaths::displayName(StandardLocation type)
         return QCoreApplication::translate("QStandardPaths", "Applications");
 
     if (QCFType<CFURLRef> url = CFURLCreateWithFileSystemPath(kCFAllocatorDefault,
-            standardLocations(type).first().toCFString(),
+            standardLocations(type).constFirst().toCFString(),
             kCFURLPOSIXPathStyle, true)) {
         QCFString name;
         CFURLCopyResourcePropertyForKey(url, kCFURLLocalizedNameKey, &name, NULL);
diff --git a/src/corelib/itemmodels/qabstractitemmodel.cpp b/src/corelib/itemmodels/qabstractitemmodel.cpp
index 02b1e1c306..54afb8a974 100644
--- a/src/corelib/itemmodels/qabstractitemmodel.cpp
+++ b/src/corelib/itemmodels/qabstractitemmodel.cpp
@@ -58,8 +58,8 @@ QPersistentModelIndexData *QPersistentModelIndexData::create(const QModelIndex &
     QPersistentModelIndexData *d = 0;
     QAbstractItemModel *model = const_cast<QAbstractItemModel *>(index.model());
     QHash<QModelIndex, QPersistentModelIndexData *> &indexes = model->d_func()->persistent.indexes;
-    const QHash<QModelIndex, QPersistentModelIndexData *>::iterator it = indexes.find(index);
-    if (it != indexes.end()) {
+    const auto it = indexes.constFind(index);
+    if (it != indexes.cend()) {
         d = (*it);
     } else {
         d = new QPersistentModelIndexData(index);
@@ -603,13 +603,13 @@ void QAbstractItemModelPrivate::removePersistentIndexData(QPersistentModelIndexD
     }
     // make sure our optimization still works
     for (int i = persistent.moved.count() - 1; i >= 0; --i) {
-        int idx = persistent.moved[i].indexOf(data);
+        int idx = persistent.moved.at(i).indexOf(data);
         if (idx >= 0)
             persistent.moved[i].remove(idx);
     }
     // update the references to invalidated persistent indexes
     for (int i = persistent.invalidated.count() - 1; i >= 0; --i) {
-        int idx = persistent.invalidated[i].indexOf(data);
+        int idx = persistent.invalidated.at(i).indexOf(data);
         if (idx >= 0)
             persistent.invalidated[i].remove(idx);
     }
@@ -2544,13 +2544,13 @@ bool QAbstractItemModel::decodeData(int row, int column, const QModelIndex &pare
     for (int i = 0; i < rows.count(); ++i)
         rowsToInsert[rows.at(i)] = 1;
     for (int i = 0; i < rowsToInsert.count(); ++i) {
-        if (rowsToInsert[i] == 1){
+        if (rowsToInsert.at(i) == 1){
             rowsToInsert[i] = dragRowCount;
             ++dragRowCount;
         }
     }
     for (int i = 0; i < rows.count(); ++i)
-        rows[i] = top + rowsToInsert[rows[i]];
+        rows[i] = top + rowsToInsert.at(rows.at(i));
 
     QBitArray isWrittenTo(dragRowCount * dragColumnCount);
 
diff --git a/src/corelib/itemmodels/qitemselectionmodel.cpp b/src/corelib/itemmodels/qitemselectionmodel.cpp
index 56df8fd55a..6390d5f389 100644
--- a/src/corelib/itemmodels/qitemselectionmodel.cpp
+++ b/src/corelib/itemmodels/qitemselectionmodel.cpp
@@ -863,7 +863,7 @@ void QItemSelectionModelPrivate::_q_layoutAboutToBeChanged(const QList<QPersiste
     // optimization for when all indexes are selected
     // (only if there is lots of items (1000) because this is not entirely correct)
     if (ranges.isEmpty() && currentSelection.count() == 1) {
-        QItemSelectionRange range = currentSelection.first();
+        QItemSelectionRange range = currentSelection.constFirst();
         QModelIndex parent = range.parent();
         tableRowCount = model->rowCount(parent);
         tableColCount = model->columnCount(parent);
diff --git a/src/corelib/itemmodels/qsortfilterproxymodel.cpp b/src/corelib/itemmodels/qsortfilterproxymodel.cpp
index 18cb49d483..98202b71ae 100644
--- a/src/corelib/itemmodels/qsortfilterproxymodel.cpp
+++ b/src/corelib/itemmodels/qsortfilterproxymodel.cpp
@@ -275,7 +275,7 @@ public:
         const QVector<int> &source_to_proxy, const QVector<int> &source_items,
         int &proxy_low, int &proxy_high) const;
 
-    QModelIndexPairList store_persistent_indexes();
+    QModelIndexPairList store_persistent_indexes() const;
     void update_persistent_indexes(const QModelIndexPairList &source_indexes);
 
     void filter_about_to_be_changed(const QModelIndex &source_parent = QModelIndex());
@@ -1014,9 +1014,9 @@ void QSortFilterProxyModelPrivate::build_source_to_proxy_mapping(
   Maps the persistent proxy indexes to source indexes and
   returns the list of source indexes.
 */
-QModelIndexPairList QSortFilterProxyModelPrivate::store_persistent_indexes()
+QModelIndexPairList QSortFilterProxyModelPrivate::store_persistent_indexes() const
 {
-    Q_Q(QSortFilterProxyModel);
+    Q_Q(const QSortFilterProxyModel);
     QModelIndexPairList source_indexes;
     source_indexes.reserve(persistent.indexes.count());
     for (QPersistentModelIndexData *data : qAsConst(persistent.indexes)) {
diff --git a/src/corelib/kernel/qcoreapplication_win.cpp b/src/corelib/kernel/qcoreapplication_win.cpp
index 9cd8420a32..601733b939 100644
--- a/src/corelib/kernel/qcoreapplication_win.cpp
+++ b/src/corelib/kernel/qcoreapplication_win.cpp
@@ -59,12 +59,12 @@ int appCmdShow = 0;
 
 Q_CORE_EXPORT QString qAppFileName()
 {
-    return QFileInfo(QCoreApplication::arguments().first()).filePath();
+    return QFileInfo(QCoreApplication::arguments().constFirst()).filePath();
 }
 
 QString QCoreApplicationPrivate::appName() const
 {
-    return QFileInfo(QCoreApplication::arguments().first()).baseName();
+    return QFileInfo(QCoreApplication::arguments().constFirst()).baseName();
 }
 
 #else
diff --git a/src/corelib/kernel/qeventdispatcher_glib.cpp b/src/corelib/kernel/qeventdispatcher_glib.cpp
index 8c2b47dccb..8ca2ac1c39 100644
--- a/src/corelib/kernel/qeventdispatcher_glib.cpp
+++ b/src/corelib/kernel/qeventdispatcher_glib.cpp
@@ -143,7 +143,7 @@ static gboolean timerSourceCheckHelper(GTimerSource *src)
         || (src->processEventsFlags & QEventLoop::X11ExcludeTimers))
         return false;
 
-    if (src->timerList.updateCurrentTime() < src->timerList.first()->timeout)
+    if (src->timerList.updateCurrentTime() < src->timerList.constFirst()->timeout)
         return false;
 
     return true;
diff --git a/src/corelib/kernel/qtimerinfo_unix.cpp b/src/corelib/kernel/qtimerinfo_unix.cpp
index 8f5e8c9523..56337bdb45 100644
--- a/src/corelib/kernel/qtimerinfo_unix.cpp
+++ b/src/corelib/kernel/qtimerinfo_unix.cpp
@@ -591,7 +591,7 @@ int QTimerInfoList::activateTimers()
         if (isEmpty())
             break;
 
-        QTimerInfo *currentTimerInfo = first();
+        QTimerInfo *currentTimerInfo = constFirst();
         if (currentTime < currentTimerInfo->timeout)
             break; // no timer has expired
 
diff --git a/src/corelib/mimetypes/qmimedatabase.cpp b/src/corelib/mimetypes/qmimedatabase.cpp
index da84523dcb..a32031a788 100644
--- a/src/corelib/mimetypes/qmimedatabase.cpp
+++ b/src/corelib/mimetypes/qmimedatabase.cpp
@@ -406,7 +406,7 @@ QMimeType QMimeDatabase::mimeTypeForFile(const QString &fileName, MatchMode mode
 {
     if (mode == MatchExtension) {
         QMutexLocker locker(&d->mutex);
-        QStringList matches = d->mimeTypeForFileName(fileName);
+        const QStringList matches = d->mimeTypeForFileName(fileName);
         const int matchCount = matches.count();
         if (matchCount == 0) {
             return d->mimeTypeForName(d->defaultMimeType());
diff --git a/src/corelib/mimetypes/qmimeprovider.cpp b/src/corelib/mimetypes/qmimeprovider.cpp
index 677e87077f..dc6eb05d9a 100644
--- a/src/corelib/mimetypes/qmimeprovider.cpp
+++ b/src/corelib/mimetypes/qmimeprovider.cpp
@@ -205,7 +205,7 @@ bool QMimeBinaryProvider::isValid()
         return false;
 
     // We found exactly one file; is it the user-modified mimes, or a system file?
-    const QString foundFile = m_cacheFiles.first()->file.fileName();
+    const QString foundFile = m_cacheFiles.constFirst()->file.fileName();
     const QString localCacheFile = QStandardPaths::writableLocation(QStandardPaths::GenericDataLocation) + QLatin1String("/mime/mime.cache");
 
     return foundFile != localCacheFile;
@@ -629,7 +629,7 @@ void QMimeBinaryProvider::loadMimeTypePrivate(QMimeTypePrivate &data)
     // Let's assume that shared-mime-info is at least version 0.70
     // Otherwise we would need 1) a version check, and 2) code for parsing patterns from the globs file.
 #if 1
-    if (!mainPattern.isEmpty() && (data.globPatterns.isEmpty() || data.globPatterns.first() != mainPattern)) {
+    if (!mainPattern.isEmpty() && (data.globPatterns.isEmpty() || data.globPatterns.constFirst() != mainPattern)) {
         // ensure it's first in the list of patterns
         data.globPatterns.removeAll(mainPattern);
         data.globPatterns.prepend(mainPattern);
@@ -637,7 +637,7 @@ void QMimeBinaryProvider::loadMimeTypePrivate(QMimeTypePrivate &data)
 #else
     const bool globsInXml = sharedMimeInfoVersion() >= QT_VERSION_CHECK(0, 70, 0);
     if (globsInXml) {
-        if (!mainPattern.isEmpty() && data.globPatterns.first() != mainPattern) {
+        if (!mainPattern.isEmpty() && data.globPatterns.constFirst() != mainPattern) {
             // ensure it's first in the list of patterns
             data.globPatterns.removeAll(mainPattern);
             data.globPatterns.prepend(mainPattern);
diff --git a/src/corelib/statemachine/qhistorystate.cpp b/src/corelib/statemachine/qhistorystate.cpp
index c3361ad17e..338c89c688 100644
--- a/src/corelib/statemachine/qhistorystate.cpp
+++ b/src/corelib/statemachine/qhistorystate.cpp
@@ -209,6 +209,11 @@ QAbstractState *QHistoryState::defaultState() const
     return d->defaultTransition ? d->defaultTransition->targetState() : Q_NULLPTR;
 }
 
+static inline bool isSoleEntry(const QList<QAbstractState*> &states, const QAbstractState * state)
+{
+    return states.size() == 1 && states.first() == state;
+}
+
 /*!
   Sets this history state's default state to be the given \a state.
   \a state must be a sibling of this history state.
@@ -224,9 +229,7 @@ void QHistoryState::setDefaultState(QAbstractState *state)
                  "to this history state's group (%p)", state, parentState());
         return;
     }
-    if (!d->defaultTransition
-            || d->defaultTransition->targetStates().size() != 1
-            || d->defaultTransition->targetStates().first() != state) {
+    if (!d->defaultTransition || !isSoleEntry(d->defaultTransition->targetStates(), state)) {
         if (!d->defaultTransition || !qobject_cast<DefaultStateTransition*>(d->defaultTransition)) {
             d->defaultTransition = new DefaultStateTransition(this, state);
             emit defaultTransitionChanged(QHistoryState::QPrivateSignal());
diff --git a/src/corelib/statemachine/qstatemachine.cpp b/src/corelib/statemachine/qstatemachine.cpp
index 62a4c03d26..d5b01f3c8a 100644
--- a/src/corelib/statemachine/qstatemachine.cpp
+++ b/src/corelib/statemachine/qstatemachine.cpp
@@ -692,7 +692,7 @@ void QStateMachinePrivate::microstep(QEvent *event, const QList<QAbstractTransit
         // Add "implicit" assignments for restored properties to the first
         // (outermost) entered state
         Q_ASSERT(!enteredStates.isEmpty());
-        QAbstractState *s = enteredStates.first();
+        QAbstractState *s = enteredStates.constFirst();
         assignmentsForEnteredStates[s] << restorablesToPropertyList(pendingRestorables);
     }
 
diff --git a/src/corelib/thread/qthread_p.h b/src/corelib/thread/qthread_p.h
index 5f7d01f50f..adcd98b609 100644
--- a/src/corelib/thread/qthread_p.h
+++ b/src/corelib/thread/qthread_p.h
@@ -121,7 +121,7 @@ public:
     void addEvent(const QPostEvent &ev) {
         int priority = ev.priority;
         if (isEmpty() ||
-            last().priority >= priority ||
+            constLast().priority >= priority ||
             insertionOffset >= size()) {
             // optimization: we can simply append if the last event in
             // the queue has higher or equal priority
diff --git a/src/corelib/thread/qthreadpool.cpp b/src/corelib/thread/qthreadpool.cpp
index 9230854600..7ce757064f 100644
--- a/src/corelib/thread/qthreadpool.cpp
+++ b/src/corelib/thread/qthreadpool.cpp
@@ -228,7 +228,7 @@ int QThreadPoolPrivate::activeThreadCount() const
 void QThreadPoolPrivate::tryToStartMoreThreads()
 {
     // try to push tasks on the queue to any available threads
-    while (!queue.isEmpty() && tryStart(queue.first().first))
+    while (!queue.isEmpty() && tryStart(queue.constFirst().first))
         queue.removeFirst();
 }
 
diff --git a/src/corelib/thread/qwaitcondition_win.cpp b/src/corelib/thread/qwaitcondition_win.cpp
index f3a645c504..a95ca0b8fd 100644
--- a/src/corelib/thread/qwaitcondition_win.cpp
+++ b/src/corelib/thread/qwaitcondition_win.cpp
@@ -141,7 +141,7 @@ void QWaitConditionPrivate::post(QWaitConditionEvent *wce, bool ret)
 
     // wakeups delivered after the timeout should be forwarded to the next waiter
     if (!ret && wce->wokenUp && !queue.isEmpty()) {
-        QWaitConditionEvent *other = queue.first();
+        QWaitConditionEvent *other = queue.constFirst();
         SetEvent(other->event);
         other->wokenUp = true;
     }
diff --git a/src/corelib/tools/qcommandlineparser.cpp b/src/corelib/tools/qcommandlineparser.cpp
index 6587d900d2..a7ab8b9e70 100644
--- a/src/corelib/tools/qcommandlineparser.cpp
+++ b/src/corelib/tools/qcommandlineparser.cpp
@@ -887,7 +887,8 @@ QStringList QCommandLineParser::values(const QString &optionName) const
 bool QCommandLineParser::isSet(const QCommandLineOption &option) const
 {
     // option.names() might be empty if the constructor failed
-    return !option.names().isEmpty() && isSet(option.names().first());
+    const auto names = option.names();
+    return !names.isEmpty() && isSet(names.first());
 }
 
 /*!
@@ -905,7 +906,7 @@ bool QCommandLineParser::isSet(const QCommandLineOption &option) const
 */
 QString QCommandLineParser::value(const QCommandLineOption &option) const
 {
-    return value(option.names().first());
+    return value(option.names().constFirst());
 }
 
 /*!
@@ -923,7 +924,7 @@ QString QCommandLineParser::value(const QCommandLineOption &option) const
 */
 QStringList QCommandLineParser::values(const QCommandLineOption &option) const
 {
-    return values(option.names().first());
+    return values(option.names().constFirst());
 }
 
 /*!
diff --git a/src/corelib/tools/qeasingcurve.cpp b/src/corelib/tools/qeasingcurve.cpp
index 2851dc81d6..4b5f5e7830 100644
--- a/src/corelib/tools/qeasingcurve.cpp
+++ b/src/corelib/tools/qeasingcurve.cpp
@@ -444,7 +444,7 @@ struct BezierEase : public QEasingCurveFunction
 
     void init()
     {
-        if (_bezierCurves.last() == QPointF(1.0, 1.0)) {
+        if (_bezierCurves.constLast() == QPointF(1.0, 1.0)) {
             _init = true;
             _curveCount = _bezierCurves.count() / 3;
 
diff --git a/src/corelib/tools/qlocale_unix.cpp b/src/corelib/tools/qlocale_unix.cpp
index 9b0d338e46..095001e0a3 100644
--- a/src/corelib/tools/qlocale_unix.cpp
+++ b/src/corelib/tools/qlocale_unix.cpp
@@ -122,7 +122,7 @@ QLocale QSystemLocale::fallbackUiLocale() const
     // the first part of LANGUAGE if LANGUAGE is set and has a first part:
     QByteArray language = qgetenv("LANGUAGE");
     if (!language.isEmpty()) {
-        language = language.split(':').first();
+        language = language.split(':').constFirst();
         if (!language.isEmpty())
             return QLocale(QString::fromLatin1(language));
     }
diff --git a/src/corelib/tools/qringbuffer.cpp b/src/corelib/tools/qringbuffer.cpp
index db2004dfd9..4a2dfdec2b 100644
--- a/src/corelib/tools/qringbuffer.cpp
+++ b/src/corelib/tools/qringbuffer.cpp
@@ -74,14 +74,14 @@ void QRingBuffer::free(qint64 bytes)
     Q_ASSERT(bytes <= bufferSize);
 
     while (bytes > 0) {
-        const qint64 blockSize = buffers.first().size() - head;
+        const qint64 blockSize = buffers.constFirst().size() - head;
 
         if (tailBuffer == 0 || blockSize > bytes) {
             // keep a single block around if it does not exceed
             // the basic block size, to avoid repeated allocations
             // between uses of the buffer
             if (bufferSize <= bytes) {
-                if (buffers.first().size() <= basicBlockSize) {
+                if (buffers.constFirst().size() <= basicBlockSize) {
                     bufferSize = 0;
                     head = tail = 0;
                 } else {
@@ -114,8 +114,8 @@ char *QRingBuffer::reserve(qint64 bytes)
     } else {
         const qint64 newSize = bytes + tail;
         // if need buffer reallocation
-        if (newSize > buffers.last().size()) {
-            if (newSize > buffers.last().capacity() && (tail >= basicBlockSize
+        if (newSize > buffers.constLast().size()) {
+            if (newSize > buffers.constLast().capacity() && (tail >= basicBlockSize
                     || newSize >= MaxByteArraySize)) {
                 // shrink this buffer to its current size
                 buffers.last().resize(tail);
@@ -180,7 +180,7 @@ void QRingBuffer::chop(qint64 bytes)
             // the basic block size, to avoid repeated allocations
             // between uses of the buffer
             if (bufferSize <= bytes) {
-                if (buffers.first().size() <= basicBlockSize) {
+                if (buffers.constFirst().size() <= basicBlockSize) {
                     bufferSize = 0;
                     head = tail = 0;
                 } else {
@@ -198,7 +198,7 @@ void QRingBuffer::chop(qint64 bytes)
         bytes -= tail;
         buffers.removeLast();
         --tailBuffer;
-        tail = buffers.last().size();
+        tail = buffers.constLast().size();
     }
 }
 
diff --git a/src/corelib/tools/qtimezoneprivate_mac.mm b/src/corelib/tools/qtimezoneprivate_mac.mm
index 14b0523ca7..3a665c2b00 100644
--- a/src/corelib/tools/qtimezoneprivate_mac.mm
+++ b/src/corelib/tools/qtimezoneprivate_mac.mm
@@ -243,7 +243,7 @@ QTimeZonePrivate::Data QMacTimeZonePrivate::previousTransition(qint64 beforeMSec
         }
     }
     if (secsList.size() >= 1)
-        return data(qint64(secsList.last()) * 1000);
+        return data(qint64(secsList.constLast()) * 1000);
     else
         return invalidData();
 }