diff --git a/src/plugins/android/androidbuildapkstep.cpp b/src/plugins/android/androidbuildapkstep.cpp
index a8b88e4627a461322e0f07d3af5f2dc95c10badf..6f44d87ad8c6d84888e7a4b19aa04152513b7cdd 100644
--- a/src/plugins/android/androidbuildapkstep.cpp
+++ b/src/plugins/android/androidbuildapkstep.cpp
@@ -44,6 +44,7 @@
 
 #include <qtsupport/qtkitinformation.h>
 
+#include <utils/algorithm.h>
 #include <utils/synchronousprocess.h>
 #include <utils/utilsicons.h>
 
@@ -157,7 +158,8 @@ bool AndroidBuildApkStep::init(QList<const BuildStep *> &earlierSteps)
     }
 
     JavaParser *parser = new JavaParser;
-    parser->setProjectFileList(target()->project()->files(ProjectExplorer::Project::AllFiles));
+    parser->setProjectFileList(Utils::transform(target()->project()->files(ProjectExplorer::Project::AllFiles),
+                                                &Utils::FileName::toString));
     parser->setSourceDirectory(androidPackageSourceDir());
     parser->setBuildDirectory(Utils::FileName::fromString(bc->buildDirectory().appendPath(Constants::ANDROID_BUILDDIRECTORY).toString()));
     setOutputParser(parser);
diff --git a/src/plugins/autotest/testcodeparser.cpp b/src/plugins/autotest/testcodeparser.cpp
index feb32c58dbef7e5816ebdc64213b0e2885864a9f..01b50a7e1e6ae9cef9af2d61db7a2102dc3b5207 100644
--- a/src/plugins/autotest/testcodeparser.cpp
+++ b/src/plugins/autotest/testcodeparser.cpp
@@ -343,7 +343,7 @@ void TestCodeParser::scanForTests(const QStringList &fileList, ITestParser *pars
         return;
     QStringList list;
     if (isFullParse) {
-        list = project->files(Project::SourceFiles);
+        list = Utils::transform(project->files(Project::SourceFiles), &Utils::FileName::toString);
         if (list.isEmpty()) {
             // at least project file should be there, but might happen if parsing current project
             // takes too long, especially when opening sessions holding multiple projects
diff --git a/src/plugins/beautifier/artisticstyle/artisticstyle.cpp b/src/plugins/beautifier/artisticstyle/artisticstyle.cpp
index 74e89fe5344d8e77fd6741f14dc956ba3dc2309c..d4825635346a60ff467bfc11c4306568344637a0 100644
--- a/src/plugins/beautifier/artisticstyle/artisticstyle.cpp
+++ b/src/plugins/beautifier/artisticstyle/artisticstyle.cpp
@@ -118,13 +118,13 @@ QString ArtisticStyle::configurationFile() const
     if (m_settings->useOtherFiles()) {
         if (const ProjectExplorer::Project *project
                 = ProjectExplorer::ProjectTree::currentProject()) {
-            const QStringList files = project->files(ProjectExplorer::Project::AllFiles);
-            for (const QString &file : files) {
+            const Utils::FileNameList files = project->files(ProjectExplorer::Project::AllFiles);
+            for (const Utils::FileName &file : files) {
                 if (!file.endsWith(".astylerc"))
                     continue;
-                const QFileInfo fi(file);
+                const QFileInfo fi = file.toFileInfo();
                 if (fi.isReadable())
-                    return file;
+                    return file.toString();
             }
         }
     }
diff --git a/src/plugins/beautifier/beautifierplugin.cpp b/src/plugins/beautifier/beautifierplugin.cpp
index ec0065ed95479b7d6c6170092fb74273674c8367..377e4612c239f242e7fe88a7ad006998a066a0b3 100644
--- a/src/plugins/beautifier/beautifierplugin.cpp
+++ b/src/plugins/beautifier/beautifierplugin.cpp
@@ -247,8 +247,7 @@ void BeautifierPlugin::autoFormatOnSave(Core::IDocument *document)
     // Check if file is contained in the current project (if wished)
     if (m_generalSettings->autoFormatOnlyCurrentProject()) {
         const ProjectExplorer::Project *pro = ProjectExplorer::ProjectTree::currentProject();
-        if (!pro || !pro->files(ProjectExplorer::Project::SourceFiles).contains(
-                    document->filePath().toString())) {
+        if (!pro || !pro->files(ProjectExplorer::Project::SourceFiles).contains(document->filePath())) {
             return;
         }
     }
diff --git a/src/plugins/beautifier/uncrustify/uncrustify.cpp b/src/plugins/beautifier/uncrustify/uncrustify.cpp
index 0f00d5fc698da19a5784ab675107f54bfcf2b4dd..d7157fc9f90c29aea4711b0c8a4fb888354e0377 100644
--- a/src/plugins/beautifier/uncrustify/uncrustify.cpp
+++ b/src/plugins/beautifier/uncrustify/uncrustify.cpp
@@ -160,13 +160,13 @@ QString Uncrustify::configurationFile() const
     if (m_settings->useOtherFiles()) {
         if (const ProjectExplorer::Project *project
                 = ProjectExplorer::ProjectTree::currentProject()) {
-            const QStringList files = project->files(ProjectExplorer::Project::AllFiles);
-            for (const QString &file : files) {
+            const Utils::FileNameList files = project->files(ProjectExplorer::Project::AllFiles);
+            for (const Utils::FileName &file : files) {
                 if (!file.endsWith("cfg"))
                     continue;
-                const QFileInfo fi(file);
+                const QFileInfo fi = file.toFileInfo();
                 if (fi.isReadable() && fi.fileName() == "uncrustify.cfg")
-                    return file;
+                    return file.toString();
             }
         }
     }
diff --git a/src/plugins/classview/classviewparser.cpp b/src/plugins/classview/classviewparser.cpp
index 8d4663819a10a0dff4402c974104cc37de4f1007..e206b180a1b5a8786dfd8d7208759c5e7c0961af 100644
--- a/src/plugins/classview/classviewparser.cpp
+++ b/src/plugins/classview/classviewparser.cpp
@@ -41,6 +41,8 @@
 #include <projectexplorer/session.h>
 #include <projectexplorer/project.h>
 #include <projectexplorer/projectnodes.h>
+
+#include <utils/algorithm.h>
 #include <utils/qtcassert.h>
 
 #include <QStandardItem>
@@ -635,12 +637,12 @@ void Parser::resetData(const CPlusPlus::Snapshot &snapshot)
     d->docLocker.unlock();
 
     // recalculate file list
-    QStringList fileList;
+    ::Utils::FileNameList fileList;
 
     // check all projects
     for (const Project *prj : SessionManager::projects())
         fileList += prj->files(Project::SourceFiles);
-    setFileList(fileList);
+    setFileList(::Utils::transform(fileList, &::Utils::FileName::toString));
 
     emit resetDataDone();
 }
@@ -722,7 +724,7 @@ QStringList Parser::addProjectTree(const ParserTreeItem::Ptr &item, const Projec
     if (cit != d->cachedPrjFileLists.constEnd()) {
         fileList = cit.value();
     } else {
-        fileList = project->files(Project::SourceFiles);
+        fileList = ::Utils::transform(project->files(Project::SourceFiles), &::Utils::FileName::toString);
         d->cachedPrjFileLists[projectPath] = fileList;
     }
     if (fileList.count() > 0) {
@@ -747,7 +749,7 @@ QStringList Parser::getAllFiles(const Project *project)
     if (cit != d->cachedPrjFileLists.constEnd()) {
         fileList = cit.value();
     } else {
-        fileList = project->files(Project::SourceFiles);
+        fileList = ::Utils::transform(project->files(Project::SourceFiles), &::Utils::FileName::toString);
         d->cachedPrjFileLists[nodePath] = fileList;
     }
     return fileList;
diff --git a/src/plugins/clearcase/clearcaseplugin.cpp b/src/plugins/clearcase/clearcaseplugin.cpp
index 9eea4a6cfb09d3ed39898fc604e641d0a96bf44d..c9d1b62fd49c796096b21ac67b3a47b4fa42a273 100644
--- a/src/plugins/clearcase/clearcaseplugin.cpp
+++ b/src/plugins/clearcase/clearcaseplugin.cpp
@@ -2044,7 +2044,7 @@ void ClearCasePlugin::updateIndex()
         return;
     m_checkInAllAction->setEnabled(false);
     m_statusMap->clear();
-    QFuture<void> result = Utils::runAsync(sync, project->files(Project::SourceFiles));
+    QFuture<void> result = Utils::runAsync(sync, transform(project->files(Project::SourceFiles), &FileName::toString));
     if (!m_settings.disableIndexer)
         ProgressManager::addTask(result, tr("Updating ClearCase Index"), ClearCase::Constants::TASK_INDEX);
 }
diff --git a/src/plugins/cmakeprojectmanager/cmakeproject.cpp b/src/plugins/cmakeprojectmanager/cmakeproject.cpp
index a47a7ee91e2341240200eeef1626f55db167fd74..cb085b3b5cf1a4659b997c834c795d3ff9074764 100644
--- a/src/plugins/cmakeprojectmanager/cmakeproject.cpp
+++ b/src/plugins/cmakeprojectmanager/cmakeproject.cpp
@@ -728,28 +728,27 @@ void CMakeProject::createGeneratedCodeModelSupport()
             = Utils::transform<QSet>(factories, [](const ExtraCompilerFactory *f) { return f->sourceTag(); });
 
     // Find all files generated by any of the extra compilers, in a rather crude way.
-    const QStringList fileList = files(SourceFiles, [&fileExtensions](const Node *n) {
+    const FileNameList fileList = files(SourceFiles, [&fileExtensions](const Node *n) {
         const QString fp = n->filePath().toString();
         const int pos = fp.lastIndexOf('.');
         return pos >= 0 && fileExtensions.contains(fp.mid(pos + 1));
     });
 
     // Generate the necessary information:
-    for (const QString &file : fileList) {
+    for (const FileName &file : fileList) {
         ExtraCompilerFactory *factory = Utils::findOrDefault(factories, [&file](const ExtraCompilerFactory *f) {
             return file.endsWith('.' + f->sourceTag());
         });
         QTC_ASSERT(factory, continue);
 
-        QStringList generated = filesGeneratedFrom(file);
+        QStringList generated = filesGeneratedFrom(file.toString());
         if (generated.isEmpty())
             continue;
 
         const FileNameList fileNames
                 = transform(generated,
                             [](const QString &s) { return FileName::fromString(s); });
-        m_extraCompilers.append(factory->create(this, FileName::fromString(file),
-                                                fileNames));
+        m_extraCompilers.append(factory->create(this, file, fileNames));
     }
 
     CppTools::GeneratedCodeModelSupport::update(m_extraCompilers);
diff --git a/src/plugins/cppeditor/resourcepreviewhoverhandler.cpp b/src/plugins/cppeditor/resourcepreviewhoverhandler.cpp
index 01cee87e92a7587e2db12d2c271ce58e825e587f..47c691760d115188d1973e974cb1c64c2a265749 100644
--- a/src/plugins/cppeditor/resourcepreviewhoverhandler.cpp
+++ b/src/plugins/cppeditor/resourcepreviewhoverhandler.cpp
@@ -142,14 +142,14 @@ static QString findResourceInProject(const QString &resName)
         return QString();
 
     if (auto *project = ProjectExplorer::ProjectTree::currentProject()) {
-        const QStringList files = project->files(ProjectExplorer::Project::AllFiles);
-        for (const QString &file : files) {
+        const Utils::FileNameList files = project->files(ProjectExplorer::Project::AllFiles);
+        for (const Utils::FileName &file : files) {
             if (!file.endsWith(".qrc"))
                 continue;
-            const QFileInfo fi(file);
+            const QFileInfo fi = file.toFileInfo();
             if (!fi.isReadable())
                 continue;
-            const QString fileName = findResourceInFile(s, file);
+            const QString fileName = findResourceInFile(s, file.toString());
             if (fileName.isEmpty())
                 continue;
 
diff --git a/src/plugins/cpptools/cppincludesfilter.cpp b/src/plugins/cpptools/cppincludesfilter.cpp
index 3f8c2d6af78cfdd1ef8264ec1117213283dc265d..f54eff5b4e056921755b91b0c0b9318165760b8c 100644
--- a/src/plugins/cpptools/cppincludesfilter.cpp
+++ b/src/plugins/cpptools/cppincludesfilter.cpp
@@ -159,8 +159,8 @@ void CppIncludesFilter::prepareSearch(const QString &entry)
         m_needsUpdate = false;
         QSet<QString> seedPaths;
         for (Project *project : SessionManager::projects()) {
-            foreach (const QString &filePath, project->files(Project::AllFiles))
-                seedPaths.insert(filePath);
+            foreach (const Utils::FileName &filePath, project->files(Project::AllFiles))
+                seedPaths.insert(filePath.toString());
         }
         foreach (DocumentModel::Entry *entry, DocumentModel::entries()) {
             if (entry)
diff --git a/src/plugins/cpptools/cpptoolsplugin.cpp b/src/plugins/cpptools/cpptoolsplugin.cpp
index af192cb0828017d1d590c5b3aeecce55fdeda0a6..f344ff871e8fc50aa46f4c543a181f750ab426ce 100644
--- a/src/plugins/cpptools/cpptoolsplugin.cpp
+++ b/src/plugins/cpptools/cpptoolsplugin.cpp
@@ -57,6 +57,7 @@
 #include <projectexplorer/project.h>
 #include <projectexplorer/projecttree.h>
 
+#include <utils/algorithm.h>
 #include <utils/fileutils.h>
 #include <utils/hostosinfo.h>
 #include <utils/macroexpander.h>
@@ -261,7 +262,8 @@ static QStringList findFilesInProject(const QString &name,
 
     QString pattern = QString(1, QLatin1Char('/'));
     pattern += name;
-    const QStringList projectFiles = project->files(ProjectExplorer::Project::AllFiles);
+    const QStringList projectFiles
+            = Utils::transform(project->files(ProjectExplorer::Project::AllFiles), &Utils::FileName::toString);
     const QStringList::const_iterator pcend = projectFiles.constEnd();
     QStringList candidateList;
     for (QStringList::const_iterator it = projectFiles.constBegin(); it != pcend; ++it) {
diff --git a/src/plugins/cpptools/symbolsfindfilter.cpp b/src/plugins/cpptools/symbolsfindfilter.cpp
index 9286a61138de4b9f926df7972d330fa45a56d971..a011fb3a752cd13cfac1a1ebfb573a0329950200 100644
--- a/src/plugins/cpptools/symbolsfindfilter.cpp
+++ b/src/plugins/cpptools/symbolsfindfilter.cpp
@@ -36,6 +36,7 @@
 #include <projectexplorer/projectexplorer.h>
 #include <projectexplorer/session.h>
 
+#include <utils/algorithm.h>
 #include <utils/runextensions.h>
 #include <utils/qtcassert.h>
 
@@ -128,7 +129,7 @@ void SymbolsFindFilter::startSearch(SearchResult *search)
     QSet<QString> projectFileNames;
     if (parameters.scope == SymbolSearcher::SearchProjectsOnly) {
         for (ProjectExplorer::Project *project : ProjectExplorer::SessionManager::projects())
-            projectFileNames += project->files(ProjectExplorer::Project::AllFiles).toSet();
+            projectFileNames += Utils::transform(project->files(ProjectExplorer::Project::AllFiles), &Utils::FileName::toString).toSet();
     }
 
     QFutureWatcher<SearchResultItem> *watcher = new QFutureWatcher<SearchResultItem>();
diff --git a/src/plugins/debugger/debuggerruncontrol.cpp b/src/plugins/debugger/debuggerruncontrol.cpp
index d8cb948372335822e974478e6b92ca648ffc3b96..2cb802f229ba01f04f6f88aa06b7cce6cec70d36 100644
--- a/src/plugins/debugger/debuggerruncontrol.cpp
+++ b/src/plugins/debugger/debuggerruncontrol.cpp
@@ -50,6 +50,7 @@
 #include <projectexplorer/taskhub.h>
 #include <projectexplorer/toolchain.h>
 
+#include <utils/algorithm.h>
 #include <utils/checkablemessagebox.h>
 #include <utils/fileutils.h>
 #include <utils/portlist.h>
@@ -276,7 +277,7 @@ void DebuggerRunTool::setStartMode(DebuggerStartMode startMode)
             projects.insert(0, startupProject);
         }
         foreach (Project *project, projects)
-            m_runParameters.projectSourceFiles.append(project->files(Project::SourceFiles));
+            m_runParameters.projectSourceFiles.append(transform(project->files(Project::SourceFiles), &FileName::toString));
         if (!projects.isEmpty())
             m_runParameters.projectSourceDirectory = projects.first()->projectDirectory().toString();
 
@@ -849,7 +850,7 @@ DebuggerRunTool::DebuggerRunTool(RunControl *runControl, Kit *kit, bool allowTer
     Project *project = runConfig ? runConfig->target()->project() : nullptr;
     if (project) {
         m_runParameters.projectSourceDirectory = project->projectDirectory().toString();
-        m_runParameters.projectSourceFiles = project->files(Project::SourceFiles);
+        m_runParameters.projectSourceFiles = transform(project->files(Project::SourceFiles), &FileName::toString);
     }
 
     m_runParameters.toolChainAbi = ToolChainKitInformation::targetAbi(kit);
diff --git a/src/plugins/genericprojectmanager/genericprojectplugin.cpp b/src/plugins/genericprojectmanager/genericprojectplugin.cpp
index edd5d42866bbf847748fbe0ecf9994603a6cca76..6c6a35431fd3132653e28022b6a5b43d3dbc8563 100644
--- a/src/plugins/genericprojectmanager/genericprojectplugin.cpp
+++ b/src/plugins/genericprojectmanager/genericprojectplugin.cpp
@@ -87,8 +87,7 @@ void GenericProjectPlugin::editFiles()
     if (!genericProject)
         return;
     SelectableFilesDialogEditFiles sfd(genericProject->projectDirectory(),
-                                       Utils::transform(genericProject->files(Project::AllFiles),
-                                                        [](const QString &f) { return Utils::FileName::fromString(f); }),
+                                       genericProject->files(Project::AllFiles),
                                        ICore::mainWindow());
     if (sfd.exec() == QDialog::Accepted)
         genericProject->setFiles(Utils::transform(sfd.selectedFiles(), &Utils::FileName::toString));
diff --git a/src/plugins/modeleditor/modelindexer.cpp b/src/plugins/modeleditor/modelindexer.cpp
index 476edaae262b5e44fb98c6ce3a35c25a24af8293..4df25cd54edb7a990128bf6b89c9ae820d639016 100644
--- a/src/plugins/modeleditor/modelindexer.cpp
+++ b/src/plugins/modeleditor/modelindexer.cpp
@@ -392,15 +392,15 @@ void ModelIndexer::scanProject(ProjectExplorer::Project *project)
         return;
 
     // TODO harmonize following code with findFirstModel()?
-    QStringList files = project->files(ProjectExplorer::Project::SourceFiles);
+    const Utils::FileNameList files = project->files(ProjectExplorer::Project::SourceFiles);
     QQueue<QueuedFile> filesQueue;
     QSet<QueuedFile> filesSet;
 
-    foreach (const QString &file, files) {
-        QFileInfo fileInfo(file);
+    for (const Utils::FileName &file : files) {
+        QFileInfo fileInfo = file.toFileInfo();
         Utils::MimeType mimeType = Utils::mimeTypeForFile(fileInfo);
         if (mimeType.name() == QLatin1String(Constants::MIME_TYPE_MODEL)) {
-            QueuedFile queuedFile(file, project, fileInfo.lastModified());
+            QueuedFile queuedFile(file.toString(), project, fileInfo.lastModified());
             filesQueue.append(queuedFile);
             filesSet.insert(queuedFile);
         }
@@ -474,20 +474,21 @@ QString ModelIndexer::findFirstModel(ProjectExplorer::FolderNode *folderNode)
 
 void ModelIndexer::forgetProject(ProjectExplorer::Project *project)
 {
-    QStringList files = project->files(ProjectExplorer::Project::SourceFiles);
+    const Utils::FileNameList files = project->files(ProjectExplorer::Project::SourceFiles);
 
     QMutexLocker locker(&d->indexerMutex);
-    foreach (const QString &file, files) {
+    for (const Utils::FileName &file : files) {
+        const QString fileString = file.toString();
         // remove file from queue
-        QueuedFile queuedFile(file, project);
+        QueuedFile queuedFile(fileString, project);
         if (d->queuedFilesSet.contains(queuedFile)) {
             QMT_CHECK(d->filesQueue.contains(queuedFile));
             d->filesQueue.removeOne(queuedFile);
             QMT_CHECK(!d->filesQueue.contains(queuedFile));
             d->queuedFilesSet.remove(queuedFile);
         }
-        removeModelFile(file, project);
-        removeDiagramReferenceFile(file, project);
+        removeModelFile(fileString, project);
+        removeDiagramReferenceFile(fileString, project);
     }
 }
 
diff --git a/src/plugins/nim/project/nimproject.cpp b/src/plugins/nim/project/nimproject.cpp
index e8083a9cf38d7bd84ea9f213f8aa428776abf0de..2b5e8c0bcc9f2932fc8ed50d6c110b8d342af86f 100644
--- a/src/plugins/nim/project/nimproject.cpp
+++ b/src/plugins/nim/project/nimproject.cpp
@@ -177,10 +177,7 @@ bool NimProject::supportsKit(Kit *k, QString *errorMessage) const
 
 FileNameList NimProject::nimFiles() const
 {
-    const QStringList nim = files(AllFiles, [](const ProjectExplorer::Node *n) {
-        return n->filePath().endsWith(".nim");
-    });
-    return Utils::transform(nim, [](const QString &fp) { return Utils::FileName::fromString(fp); });
+    return files(AllFiles, [](const ProjectExplorer::Node *n) { return n->filePath().endsWith(".nim"); });
 }
 
 QVariantMap NimProject::toMap() const
diff --git a/src/plugins/projectexplorer/abstractprocessstep.cpp b/src/plugins/projectexplorer/abstractprocessstep.cpp
index 9d5612c5fdf01949c613748b98f846e7d8b4c890..563cc4f97b76473516aee5fcc6b79b9358feb7a9 100644
--- a/src/plugins/projectexplorer/abstractprocessstep.cpp
+++ b/src/plugins/projectexplorer/abstractprocessstep.cpp
@@ -379,8 +379,8 @@ void AbstractProcessStep::taskAdded(const Task &task, int linkedOutputLines, int
 
         QList<QFileInfo> possibleFiles;
         QString fileName = Utils::FileName::fromString(filePath).fileName();
-        foreach (const QString &file, project()->files(Project::AllFiles)) {
-            QFileInfo candidate(file);
+        foreach (const Utils::FileName &file, project()->files(Project::AllFiles)) {
+            QFileInfo candidate = file.toFileInfo();
             if (candidate.fileName() == fileName)
                 possibleFiles << candidate;
         }
diff --git a/src/plugins/projectexplorer/allprojectsfilter.cpp b/src/plugins/projectexplorer/allprojectsfilter.cpp
index f03e5eef4906e79feb26b693918205f1b9d9adc8..24371ad4e12a27ce3f9a6d67544e5257e318ca3c 100644
--- a/src/plugins/projectexplorer/allprojectsfilter.cpp
+++ b/src/plugins/projectexplorer/allprojectsfilter.cpp
@@ -59,7 +59,7 @@ void AllProjectsFilter::prepareSearch(const QString &entry)
     if (!fileIterator()) {
         QStringList paths;
         for (Project *project : SessionManager::projects())
-            paths.append(project->files(Project::AllFiles));
+            paths.append(Utils::transform(project->files(Project::AllFiles), &Utils::FileName::toString));
         Utils::sort(paths);
         setFileIterator(new BaseFileFilter::ListIterator(paths));
     }
diff --git a/src/plugins/projectexplorer/allprojectsfind.cpp b/src/plugins/projectexplorer/allprojectsfind.cpp
index 46b7fbb8941539047b3c5ff8904ff4d4eeb9d2f6..aa0d7c6fbc95dbe4af46b5d3426d0b08577bbd84 100644
--- a/src/plugins/projectexplorer/allprojectsfind.cpp
+++ b/src/plugins/projectexplorer/allprojectsfind.cpp
@@ -88,7 +88,7 @@ Utils::FileIterator *AllProjectsFind::filesForProjects(const QStringList &nameFi
         QTextCodec *projectCodec = config->useGlobalSettings()
             ? Core::EditorManager::defaultTextCodec()
             : config->textCodec();
-        const QStringList filteredFiles = filterFiles(project->files(Project::AllFiles));
+        const QStringList filteredFiles = filterFiles(Utils::transform(project->files(Project::AllFiles), &Utils::FileName::toString));
         for (const QString &fileName : filteredFiles) {
             QTextCodec *codec = openEditorEncodings.value(fileName);
             if (!codec)
diff --git a/src/plugins/projectexplorer/currentprojectfilter.cpp b/src/plugins/projectexplorer/currentprojectfilter.cpp
index cc67c637c83d250c74c0ad5d9177711456b37742..1dd93b009fdac144c1e80045c1c3dcf412b6c10c 100644
--- a/src/plugins/projectexplorer/currentprojectfilter.cpp
+++ b/src/plugins/projectexplorer/currentprojectfilter.cpp
@@ -58,7 +58,7 @@ void CurrentProjectFilter::prepareSearch(const QString &entry)
     if (!fileIterator()) {
         QStringList paths;
         if (m_project) {
-            paths = m_project->files(Project::AllFiles);
+            paths = Utils::transform(m_project->files(Project::AllFiles), &Utils::FileName::toString);
             Utils::sort(paths);
         }
         setFileIterator(new BaseFileFilter::ListIterator(paths));
diff --git a/src/plugins/projectexplorer/project.cpp b/src/plugins/projectexplorer/project.cpp
index 71038c52d395d1a3a6034857c2e53a4d483c9f0b..04be03dadcfa3eecf402159365213e2d47f346c2 100644
--- a/src/plugins/projectexplorer/project.cpp
+++ b/src/plugins/projectexplorer/project.cpp
@@ -557,17 +557,17 @@ Project::RestoreResult Project::restoreSettings(QString *errorMessage)
     return result;
 }
 
-QStringList Project::files(Project::FilesMode fileMode,
+Utils::FileNameList Project::files(Project::FilesMode fileMode,
                            const std::function<bool(const Node *)> &filter) const
 {
-    QStringList result;
+    Utils::FileNameList result;
 
     if (!rootProjectNode())
         return result;
 
-    QSet<QString> alreadySeen;
+    QSet<Utils::FileName> alreadySeen;
     rootProjectNode()->forEachGenericNode([&](const Node *n) {
-        const QString path = n->filePath().toString();
+        const Utils::FileName path = n->filePath();
         const int count = alreadySeen.count();
         alreadySeen.insert(path);
         if (count == alreadySeen.count())
diff --git a/src/plugins/projectexplorer/project.h b/src/plugins/projectexplorer/project.h
index 1c832578593bd4ec5ba2a5adfa601595a10e149f..79e0e3506a9b13e61dd1863258af9b044425b3b9 100644
--- a/src/plugins/projectexplorer/project.h
+++ b/src/plugins/projectexplorer/project.h
@@ -135,8 +135,8 @@ public:
         GeneratedFiles = 0x2,
         AllFiles       = SourceFiles | GeneratedFiles
     };
-    QStringList files(FilesMode fileMode,
-                      const std::function<bool(const Node *)> &filter = {}) const;
+    Utils::FileNameList files(FilesMode fileMode,
+                              const std::function<bool(const Node *)> &filter = {}) const;
     virtual QStringList filesGeneratedFrom(const QString &sourceFile) const;
 
     static QString makeUnique(const QString &preferredName, const QStringList &usedNames);
diff --git a/src/plugins/projectexplorer/session.cpp b/src/plugins/projectexplorer/session.cpp
index dd6a4a7e80fe7cae2278e304dcc5d545f3297b88..f1143f317c27e3ab88b1e994e3630654c8000ee1 100644
--- a/src/plugins/projectexplorer/session.cpp
+++ b/src/plugins/projectexplorer/session.cpp
@@ -690,7 +690,7 @@ Project *SessionManager::projectForFile(const Utils::FileName &fileName)
 bool SessionManager::projectContainsFile(Project *p, const Utils::FileName &fileName)
 {
     if (!d->m_projectFileCache.contains(p))
-        d->m_projectFileCache.insert(p, p->files(Project::AllFiles));
+        d->m_projectFileCache.insert(p, Utils::transform(p->files(Project::AllFiles), &Utils::FileName::toString));
 
     return d->m_projectFileCache.value(p).contains(fileName.toString());
 }
diff --git a/src/plugins/pythoneditor/pythoneditorplugin.cpp b/src/plugins/pythoneditor/pythoneditorplugin.cpp
index 27aacc35c9b282d2daf47c937286aee0ab0710d7..051d1244954ac0b84200715660d41c2a08621e53 100644
--- a/src/plugins/pythoneditor/pythoneditorplugin.cpp
+++ b/src/plugins/pythoneditor/pythoneditorplugin.cpp
@@ -283,7 +283,7 @@ public:
         Q_UNUSED(mode);
         //return { Core::Id(PythonExecutableId) };
         PythonProject *project = static_cast<PythonProject *>(parent->project());
-        return project->files(ProjectExplorer::Project::AllFiles);
+        return Utils::transform(project->files(ProjectExplorer::Project::AllFiles), &Utils::FileName::toString);
     }
 
     bool canCreateHelper(Target *parent, const QString &buildTarget) const override
@@ -292,7 +292,7 @@ public:
         const QString script = buildTarget;
         if (script.endsWith(".pyqtc"))
             return false;
-        return project->files(ProjectExplorer::Project::AllFiles).contains(script);
+        return project->files(ProjectExplorer::Project::AllFiles).contains(FileName::fromString(script));
     }
 };
 
diff --git a/src/plugins/qmakeprojectmanager/qmakeproject.cpp b/src/plugins/qmakeprojectmanager/qmakeproject.cpp
index 872585fc80b6380a97b1b421cebeb6ff317251e9..c57dba6ae3d82fb1dd5c29c107eb6ef35f69354f 100644
--- a/src/plugins/qmakeprojectmanager/qmakeproject.cpp
+++ b/src/plugins/qmakeprojectmanager/qmakeproject.cpp
@@ -849,7 +849,7 @@ static void notifyChangedHelper(const FileName &fileName, QmakeProFile *file)
 void QmakeProject::notifyChanged(const FileName &name)
 {
     for (QmakeProject *project : s_projects) {
-        if (project->files(QmakeProject::SourceFiles).contains(name.toString()))
+        if (project->files(QmakeProject::SourceFiles).contains(name))
             notifyChangedHelper(name, project->rootProFile());
     }
 }
diff --git a/src/plugins/qmldesigner/components/componentcore/changestyleaction.cpp b/src/plugins/qmldesigner/components/componentcore/changestyleaction.cpp
index dfec087a452c37190bff5d16e67fdb044382b2b2..a6e746d3f0f9cfe11d82b46ca7149af43f737980 100644
--- a/src/plugins/qmldesigner/components/componentcore/changestyleaction.cpp
+++ b/src/plugins/qmldesigner/components/componentcore/changestyleaction.cpp
@@ -38,9 +38,9 @@ static QString styleConfigFileName(const QString &qmlFileName)
     ProjectExplorer::Project *currentProject = ProjectExplorer::SessionManager::projectForFile(Utils::FileName::fromString(qmlFileName));
 
     if (currentProject)
-        foreach (const QString &fileName, currentProject->files(ProjectExplorer::Project::SourceFiles))
+        foreach (const Utils::FileName &fileName, currentProject->files(ProjectExplorer::Project::SourceFiles))
             if (fileName.endsWith("qtquickcontrols2.conf"))
-                return fileName;
+                return fileName.toString();
 
     return QString();
 }
diff --git a/src/plugins/qmldesigner/components/integration/designdocument.cpp b/src/plugins/qmldesigner/components/integration/designdocument.cpp
index f83af521cb8e595df8a23dbd6d0eaacf6ce4750e..0e78864c140988d5e511722a09f960da47ad0c59 100644
--- a/src/plugins/qmldesigner/components/integration/designdocument.cpp
+++ b/src/plugins/qmldesigner/components/integration/designdocument.cpp
@@ -288,9 +288,9 @@ void DesignDocument::updateQrcFiles()
     ProjectExplorer::Project *currentProject = ProjectExplorer::SessionManager::projectForFile(fileName());
 
     if (currentProject) {
-        foreach (const QString &fileName, currentProject->files(ProjectExplorer::Project::SourceFiles)) {
+        for (const Utils::FileName &fileName : currentProject->files(ProjectExplorer::Project::SourceFiles)) {
             if (fileName.endsWith(".qrc"))
-                QmlJS::ModelManagerInterface::instance()->updateQrcFile(fileName);
+                QmlJS::ModelManagerInterface::instance()->updateQrcFile(fileName.toString());
         }
     }
 }
diff --git a/src/plugins/qmldesigner/designercore/instances/puppetcreator.cpp b/src/plugins/qmldesigner/designercore/instances/puppetcreator.cpp
index 85b3a698742b07bbc9263f06631304cefa4a67bd..93d02e378748d44cae23a2dd9c965bcbe6e108cc 100644
--- a/src/plugins/qmldesigner/designercore/instances/puppetcreator.cpp
+++ b/src/plugins/qmldesigner/designercore/instances/puppetcreator.cpp
@@ -150,10 +150,9 @@ QString PuppetCreator::getStyleConfigFileName() const
 {
 #ifndef QMLDESIGNER_TEST
     if (m_currentProject) {
-        for (const QString &fileName : m_currentProject->files(ProjectExplorer::Project::SourceFiles)) {
-            QFileInfo fileInfo(fileName);
-            if (fileInfo.fileName() == "qtquickcontrols2.conf")
-                return  fileName;
+        for (const Utils::FileName &fileName : m_currentProject->files(ProjectExplorer::Project::SourceFiles)) {
+            if (fileName.fileName() == "qtquickcontrols2.conf")
+                return  fileName.toString();
         }
     }
 #endif
diff --git a/src/plugins/qmldesigner/qmldesignerplugin.cpp b/src/plugins/qmldesigner/qmldesignerplugin.cpp
index d8ea45f1245388631e4fddf4a215b689db7c1c2f..a300537bec02ca6a2717692160a3d8fd51eeb655 100644
--- a/src/plugins/qmldesigner/qmldesignerplugin.cpp
+++ b/src/plugins/qmldesigner/qmldesignerplugin.cpp
@@ -213,9 +213,9 @@ static QStringList allUiQmlFilesforCurrentProject(const Utils::FileName &fileNam
     ProjectExplorer::Project *currentProject = ProjectExplorer::SessionManager::projectForFile(fileName);
 
     if (currentProject) {
-        foreach (const QString &fileName, currentProject->files(ProjectExplorer::Project::SourceFiles)) {
+        foreach (const Utils::FileName &fileName, currentProject->files(ProjectExplorer::Project::SourceFiles)) {
             if (fileName.endsWith(".ui.qml"))
-                list.append(fileName);
+                list.append(fileName.toString());
         }
     }
 
diff --git a/src/plugins/qmljseditor/qmljseditorplugin.cpp b/src/plugins/qmljseditor/qmljseditorplugin.cpp
index 068fbb4340b78e4b11a8997f5b45cff40b394e4d..2931b1f9c61bba523bdffefce33e713b71fac54c 100644
--- a/src/plugins/qmljseditor/qmljseditorplugin.cpp
+++ b/src/plugins/qmljseditor/qmljseditorplugin.cpp
@@ -349,10 +349,8 @@ void QmlJSEditorPlugin::autoFormatOnSave(Core::IDocument *document)
     // Check if file is contained in the current project (if wished)
     if (QmlJsEditingSettings::get().autoFormatOnlyCurrentProject()) {
         const ProjectExplorer::Project *pro = ProjectExplorer::ProjectTree::currentProject();
-        if (!pro || !pro->files(ProjectExplorer::Project::SourceFiles).contains(
-                    document->filePath().toString())) {
+        if (!pro || !pro->files(ProjectExplorer::Project::SourceFiles).contains(document->filePath()))
             return;
-        }
     }
 
     reformatFile();
diff --git a/src/plugins/qmljstools/qmljsmodelmanager.cpp b/src/plugins/qmljstools/qmljsmodelmanager.cpp
index bdf64615ec5f7532b709069b03fc7d4536ca9412..de9259933ff967d56ab6d32681ff8ddc3eb6b7fd 100644
--- a/src/plugins/qmljstools/qmljsmodelmanager.cpp
+++ b/src/plugins/qmljstools/qmljsmodelmanager.cpp
@@ -49,6 +49,8 @@
 #include <qtsupport/qtkitinformation.h>
 #include <qtsupport/qtsupportconstants.h>
 #include <texteditor/textdocument.h>
+
+#include <utils/algorithm.h>
 #include <utils/hostosinfo.h>
 #include <utils/mimetypes/mimedatabase.h>
 
@@ -84,15 +86,15 @@ ModelManagerInterface::ProjectInfo ModelManager::defaultProjectInfoForProject(
                                              Constants::QMLPROJECT_MIMETYPE,
                                              Constants::QMLTYPES_MIMETYPE,
                                              Constants::QMLUI_MIMETYPE };
-        projectInfo.sourceFiles = project->files(Project::SourceFiles,
-                                                 [&qmlTypeNames](const Node *n) {
+        projectInfo.sourceFiles = Utils::transform(project->files(Project::SourceFiles,
+                                                   [&qmlTypeNames](const Node *n) {
             if (const FileNode *fn = n->asFileNode()) {
                 return fn->fileType() == FileType::QML
                         && qmlTypeNames.contains(Utils::mimeTypeForFile(fn->filePath().toString(),
                                                                         MimeMatchMode::MatchExtension).name());
             }
             return false;
-        });
+        }), &FileName::toString);
         activeTarget = project->activeTarget();
     }
     Kit *activeKit = activeTarget ? activeTarget->kit() : KitManager::defaultKit();
diff --git a/src/plugins/qmlprojectmanager/qmlprojectrunconfiguration.cpp b/src/plugins/qmlprojectmanager/qmlprojectrunconfiguration.cpp
index 0282d5da39b88cec67139506298117b7fd8a7e97..bd49f9f093304ff21afdd8d1c12f725aa53ba2f8 100644
--- a/src/plugins/qmlprojectmanager/qmlprojectrunconfiguration.cpp
+++ b/src/plugins/qmlprojectmanager/qmlprojectrunconfiguration.cpp
@@ -261,15 +261,15 @@ void QmlProjectRunConfiguration::updateEnabledState()
                 || mainScriptMimeType.matchesName(QLatin1String(QmlJSTools::Constants::QMLPROJECT_MIMETYPE))) {
             // find a qml file with lowercase filename. This is slow, but only done
             // in initialization/other border cases.
-            foreach (const QString &filename, target()->project()->files(Project::AllFiles)) {
-                const QFileInfo fi(filename);
+            foreach (const Utils::FileName &filename, target()->project()->files(Project::AllFiles)) {
+                const QFileInfo fi = filename.toFileInfo();
 
                 if (!filename.isEmpty() && fi.baseName()[0].isLower()) {
                     Utils::MimeType type = Utils::mimeTypeForFile(fi);
                     if (type.matchesName(QLatin1String(ProjectExplorer::Constants::QML_MIMETYPE))
                             || type.matchesName(
                                 QLatin1String(ProjectExplorer::Constants::QMLUI_MIMETYPE))) {
-                        m_currentFileFilename = filename;
+                        m_currentFileFilename = filename.toString();
                         qmlFileFound = true;
                         break;
                     }
diff --git a/src/plugins/qmlprojectmanager/qmlprojectrunconfigurationwidget.cpp b/src/plugins/qmlprojectmanager/qmlprojectrunconfigurationwidget.cpp
index e7097b9aa5a3c1f4522ffd2abd8c05b5852a3db6..8af2c9a7912fd7d2cc704e588a55e8aded42246b 100644
--- a/src/plugins/qmlprojectmanager/qmlprojectrunconfigurationwidget.cpp
+++ b/src/plugins/qmlprojectmanager/qmlprojectrunconfigurationwidget.cpp
@@ -30,6 +30,8 @@
 #include <coreplugin/icore.h>
 #include <projectexplorer/projectexplorer.h>
 #include <projectexplorer/target.h>
+
+#include <utils/algorithm.h>
 #include <utils/detailswidget.h>
 
 #include <QLineEdit>
@@ -38,7 +40,6 @@
 #include <QLabel>
 #include <QStandardItemModel>
 
-#include <algorithm>
 
 using Core::ICore;
 using ProjectExplorer::ProjectExplorerPlugin;
@@ -114,7 +115,8 @@ void QmlProjectRunConfigurationWidget::updateFileComboBox()
     m_fileListModel->appendRow(new QStandardItem(QLatin1String(CURRENT_FILE)));
     QModelIndex currentIndex;
 
-    QStringList sortedFiles = project->files(ProjectExplorer::Project::AllFiles);
+    QStringList sortedFiles = Utils::transform(project->files(ProjectExplorer::Project::AllFiles),
+                                               &Utils::FileName::toString);
 
     // make paths relative to project directory
     QStringList relativeFiles;
diff --git a/src/plugins/qtsupport/baseqtversion.cpp b/src/plugins/qtsupport/baseqtversion.cpp
index 8c5c0511993a1c871455b5003f102793c83478e9..8d5122c18e4f1ef435f833ea59bb84614f97827f 100644
--- a/src/plugins/qtsupport/baseqtversion.cpp
+++ b/src/plugins/qtsupport/baseqtversion.cpp
@@ -1348,13 +1348,15 @@ void BaseQtVersion::populateQmlFileFinder(FileInProjectFinder *finder, const Tar
     // Sort files from startupProject to the front of the list ...
     if (startupProject) {
         projectDirectory = startupProject->projectDirectory().toString();
-        sourceFiles.append(startupProject->files(ProjectExplorer::Project::SourceFiles));
+        sourceFiles.append(Utils::transform(startupProject->files(ProjectExplorer::Project::SourceFiles),
+                                            &Utils::FileName::toString));
     }
 
     // ... then add all the other projects' files.
     for (const ProjectExplorer::Project *project : projects) {
         if (project != startupProject)
-            sourceFiles.append(project->files(ProjectExplorer::Project::SourceFiles));
+            sourceFiles.append(Utils::transform(project->files(ProjectExplorer::Project::SourceFiles),
+                                                &Utils::FileName::toString));
     }
 
     // If no target was given, but we've found a startupProject, then try to deduce a
diff --git a/src/plugins/qtsupport/qtoutputformatter.cpp b/src/plugins/qtsupport/qtoutputformatter.cpp
index c86d883055f065469968f46299ca666f80e41ba1..08a817dadcaae5de026832cab682a05a3a84d425 100644
--- a/src/plugins/qtsupport/qtoutputformatter.cpp
+++ b/src/plugins/qtsupport/qtoutputformatter.cpp
@@ -27,6 +27,8 @@
 
 #include <coreplugin/editormanager/editormanager.h>
 #include <projectexplorer/project.h>
+
+#include <utils/algorithm.h>
 #include <utils/ansiescapecodehandler.h>
 #include <utils/fileinprojectfinder.h>
 #include <utils/theme/theme.h>
@@ -85,7 +87,7 @@ QtOutputFormatter::QtOutputFormatter(Project *project)
     : d(new Internal::QtOutputFormatterPrivate(project))
 {
     if (project) {
-        d->projectFinder.setProjectFiles(project->files(Project::SourceFiles));
+        d->projectFinder.setProjectFiles(Utils::transform(project->files(Project::SourceFiles), &Utils::FileName::toString));
         d->projectFinder.setProjectDirectory(project->projectDirectory().toString());
 
         connect(project, &Project::fileListChanged,
@@ -279,7 +281,7 @@ void QtOutputFormatter::openEditor(const QString &fileName, int line, int column
 void QtOutputFormatter::updateProjectFileList()
 {
     if (d->project)
-        d->projectFinder.setProjectFiles(d->project.data()->files(Project::SourceFiles));
+        d->projectFinder.setProjectFiles(transform(d->project->files(Project::SourceFiles), &FileName::toString));
 }
 
 } // namespace QtSupport
diff --git a/src/plugins/todo/cpptodoitemsscanner.cpp b/src/plugins/todo/cpptodoitemsscanner.cpp
index 109e3aef7be3630dc436e0eaf21af66830696a82..46b6f3d9a799a8b30d2d89ed0a5a50c600baaaf3 100644
--- a/src/plugins/todo/cpptodoitemsscanner.cpp
+++ b/src/plugins/todo/cpptodoitemsscanner.cpp
@@ -32,6 +32,8 @@
 
 #include <cplusplus/TranslationUnit.h>
 
+#include <utils/algorithm.h>
+
 #include <cctype>
 
 namespace Todo {
@@ -57,7 +59,8 @@ void CppTodoItemsScanner::scannerParamsChanged()
 
     QSet<QString> filesToBeUpdated;
     foreach (const CppTools::ProjectInfo &info, modelManager->projectInfos())
-        filesToBeUpdated.unite(info.project().data()->files(ProjectExplorer::Project::SourceFiles).toSet());
+        filesToBeUpdated.unite(Utils::transform(info.project().data()->files(ProjectExplorer::Project::SourceFiles),
+                                                &Utils::FileName::toString).toSet());
 
     modelManager->updateSourceFiles(filesToBeUpdated);
 }
diff --git a/src/plugins/todo/todoitemsprovider.cpp b/src/plugins/todo/todoitemsprovider.cpp
index 8a5881e3d0f18d87c1bb21d15f58e59ed78e79bb..99ca36fc23172539c5f951d9acbd2698ded9168a 100644
--- a/src/plugins/todo/todoitemsprovider.cpp
+++ b/src/plugins/todo/todoitemsprovider.cpp
@@ -39,6 +39,8 @@
 #include <projectexplorer/projecttree.h>
 #include <projectexplorer/session.h>
 
+#include <utils/algorithm.h>
+
 #include <QRegExp>
 #include <QTimer>
 
@@ -120,7 +122,9 @@ void TodoItemsProvider::createScanners()
 void TodoItemsProvider::setItemsListWithinStartupProject()
 {
     QHashIterator<QString, QList<TodoItem> > it(m_itemsHash);
-    QSet<QString> fileNames = QSet<QString>::fromList(m_startupProject->files(Project::SourceFiles));
+    const QSet<QString> fileNames
+            = QSet<QString>::fromList(Utils::transform(m_startupProject->files(Project::SourceFiles),
+                                                       &Utils::FileName::toString));
 
     QVariantMap settings = m_startupProject->namedSettings(Constants::SETTINGS_NAME_KEY).toMap();
 
@@ -156,8 +160,9 @@ void TodoItemsProvider::setItemsListWithinSubproject()
             });
 
             // files must be both in the current subproject and the startup-project.
-            QSet<QString> fileNames = QSet<QString>::fromList(
-                        m_startupProject->files(ProjectExplorer::Project::SourceFiles));
+            const QSet<QString> fileNames
+                    = QSet<QString>::fromList(Utils::transform(m_startupProject->files(Project::SourceFiles),
+                                                               &Utils::FileName::toString));
             QHashIterator<QString, QList<TodoItem> > it(m_itemsHash);
             while (it.hasNext()) {
                 it.next();
diff --git a/src/plugins/valgrind/memchecktool.cpp b/src/plugins/valgrind/memchecktool.cpp
index e5821e142fa1db136b1d7d266019181123ebd37b..0aa48bfe04ad8f0a5c42bf2259efff86d288c74f 100644
--- a/src/plugins/valgrind/memchecktool.cpp
+++ b/src/plugins/valgrind/memchecktool.cpp
@@ -714,7 +714,8 @@ void MemcheckTool::maybeActiveRunConfigurationChanged()
 
 RunWorker *MemcheckTool::createRunWorker(RunControl *runControl)
 {
-    m_errorModel.setRelevantFrameFinder(makeFrameFinder(runControl->project()->files(Project::AllFiles)));
+    m_errorModel.setRelevantFrameFinder(makeFrameFinder(transform(runControl->project()->files(Project::AllFiles),
+                                                                  &FileName::toString)));
 
     auto runTool = new MemcheckToolRunner(runControl, runControl->runMode() == MEMCHECK_WITH_GDB_RUN_MODE);