More Qt 6 fixes

Task-number: QTCREATORBUG-24098
Change-Id: I1e30b49218b18f426aea6e4cd3680be513894746
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/fakevim/fakevimhandler.cpp

@@ -7234,8 +7234,8 @@ void FakeVimHandler::Private::invertCase(const Range &range)
         [] (const QString &text) -> QString {
             QString result = text;
             for (int i = 0; i < result.length(); ++i) {
-                QCharRef c = result[i];
-                c = c.isUpper() ? c.toLower() : c.toUpper();
+                const QChar c = result[i];
+                result[i] = c.isUpper() ? c.toLower() : c.toUpper();
             }
             return result;
         });

src/plugins/projectexplorer/editorconfiguration.h

@@ -34,9 +34,9 @@
 
 #include <memory>
 
-namespace Core {
-class IEditor;
-}
+QT_BEGIN_NAMESPACE
+class QTextCodec;
+QT_END_NAMESPACE
 
 namespace TextEditor {
 class BaseTextEditor;

src/plugins/projectexplorer/projectexplorer.cpp

@@ -147,17 +147,17 @@
 #include <utils/stringutils.h>
 #include <utils/utilsicons.h>
 
-#include <QFileInfo>
-#include <QSettings>
-
 #include <QAction>
+#include <QActionGroup>
 #include <QApplication>
 #include <QDir>
 #include <QFileDialog>
+#include <QFileInfo>
 #include <QInputDialog>
 #include <QMenu>
 #include <QMessageBox>
 #include <QPair>
+#include <QSettings>
 #include <QThreadPool>
 #include <QTimer>
 

src/plugins/texteditor/colorpreviewhoverhandler.cpp

@@ -222,7 +222,7 @@ static bool extractFuncAndArgs(const QString &s,
     retFuncName = removeWhitespace(s.mid(funcStart, funcEnd - funcStart + 1));
 
     QString argStr = s.mid(openBrace + 1, closeBrace - openBrace - 1);
-    retArgs = argStr.split(QLatin1Char(','), QString::KeepEmptyParts);
+    retArgs = argStr.split(',');
 
     return true;
 }

src/plugins/texteditor/highlightersettingspage.cpp

@@ -64,8 +64,8 @@ void HighlighterSettingsPage::HighlighterSettingsPagePrivate::migrateGenericHigh
     QDir userDefinitionPath(m_settings.definitionFilesPath());
     if (userDefinitionPath.mkdir("syntax")) {
         const auto link = Utils::HostOsInfo::isAnyUnixHost()
-                              ? QOverload<const QString &, const QString &>::of(&QFile::link)
-                              : QOverload<const QString &, const QString &>::of(&QFile::copy);
+                              ? static_cast<bool(*)(const QString &, const QString &)>(&QFile::link)
+                              : static_cast<bool(*)(const QString &, const QString &)>(&QFile::copy);
 
         for (const QFileInfo &file : userDefinitionPath.entryInfoList({"*.xml"}, QDir::Files))
             link(file.filePath(), file.absolutePath() + "/syntax/" + file.fileName());