diff --git a/src/plugins/android/androidmanifestdocument.cpp b/src/plugins/android/androidmanifestdocument.cpp
index e3473a891b0..6bb879de0f6 100644
--- a/src/plugins/android/androidmanifestdocument.cpp
+++ b/src/plugins/android/androidmanifestdocument.cpp
@@ -47,10 +47,10 @@ AndroidManifestDocument::AndroidManifestDocument(AndroidManifestEditorWidget *ed
             this, &Core::IDocument::changed);
 }
 
-bool AndroidManifestDocument::save(QString *errorString, const QString &fileName, bool autoSave)
+bool AndroidManifestDocument::save(QString *errorString, const Utils::FilePath &filePath, bool autoSave)
 {
     m_editorWidget->preSave();
-    bool result = TextDocument::save(errorString, fileName, autoSave);
+    bool result = TextDocument::save(errorString, filePath, autoSave);
     m_editorWidget->postSave();
     return result;
 }
diff --git a/src/plugins/android/androidmanifestdocument.h b/src/plugins/android/androidmanifestdocument.h
index 169047f0516..ce22c8b37f1 100644
--- a/src/plugins/android/androidmanifestdocument.h
+++ b/src/plugins/android/androidmanifestdocument.h
@@ -36,7 +36,7 @@ class AndroidManifestDocument : public TextEditor::TextDocument
 {
 public:
     explicit AndroidManifestDocument(AndroidManifestEditorWidget *editorWidget);
-    bool save(QString *errorString, const QString &fileName = QString(),
+    bool save(QString *errorString, const Utils::FilePath &filePath,
               bool autoSave = false) override;
 
     bool isModified() const override;
diff --git a/src/plugins/bineditor/bineditorplugin.cpp b/src/plugins/bineditor/bineditorplugin.cpp
index ae766e5be03..9781161a5b8 100644
--- a/src/plugins/bineditor/bineditorplugin.cpp
+++ b/src/plugins/bineditor/bineditorplugin.cpp
@@ -230,28 +230,27 @@ public:
         return type == TypeRemoved ? BehaviorSilent : IDocument::reloadBehavior(state, type);
     }
 
-    bool save(QString *errorString, const QString &fn, bool autoSave) override
+    bool save(QString *errorString, const Utils::FilePath &filePath, bool autoSave) override
     {
         QTC_ASSERT(!autoSave, return true); // bineditor does not support autosave - it would be a bit expensive
-        const FilePath fileNameToUse = fn.isEmpty() ? filePath() : FilePath::fromString(fn);
-        if (m_widget->save(errorString, filePath().toString(), fileNameToUse.toString())) {
+        const FilePath &fileNameToUse = filePath.isEmpty() ? this->filePath() : filePath;
+        if (m_widget->save(errorString, this->filePath().toString(), fileNameToUse.toString())) {
             setFilePath(fileNameToUse);
             return true;
-        } else {
-            return false;
         }
+        return false;
     }
 
-    OpenResult open(QString *errorString, const QString &fileName,
-                    const QString &realFileName) override
+    OpenResult open(QString *errorString, const Utils::FilePath &filePath,
+                    const Utils::FilePath &realFilePath) override
     {
-        QTC_CHECK(fileName == realFileName); // The bineditor can do no autosaving
-        return openImpl(errorString, fileName);
+        QTC_CHECK(filePath == realFilePath); // The bineditor can do no autosaving
+        return openImpl(errorString, filePath);
     }
 
-    OpenResult openImpl(QString *errorString, const QString &fileName, quint64 offset = 0)
+    OpenResult openImpl(QString *errorString, const Utils::FilePath &filePath, quint64 offset = 0)
     {
-        QFile file(fileName);
+        QFile file(filePath.toString());
         if (file.open(QIODevice::ReadOnly)) {
             file.close();
             quint64 size = static_cast<quint64>(file.size());
@@ -274,12 +273,11 @@ public:
             }
             if (offset >= size)
                 return OpenResult::CannotHandle;
-            setFilePath(FilePath::fromString(fileName));
+            setFilePath(filePath);
             m_widget->setSizes(offset, file.size());
             return OpenResult::Success;
         }
-        QString errStr = tr("Cannot open %1: %2").arg(
-                QDir::toNativeSeparators(fileName), file.errorString());
+        QString errStr = tr("Cannot open %1: %2").arg(filePath.toUserOutput(), file.errorString());
         if (errorString)
             *errorString = errStr;
         else
@@ -312,7 +310,7 @@ public:
     void provideNewRange(quint64 offset)
     {
         if (filePath().exists())
-            openImpl(nullptr, filePath().toString(), offset);
+            openImpl(nullptr, filePath(), offset);
     }
 
 public:
@@ -332,7 +330,7 @@ public:
         emit aboutToReload();
         int cPos = m_widget->cursorPosition();
         m_widget->clear();
-        const bool success = (openImpl(errorString, filePath().toString()) == OpenResult::Success);
+        const bool success = (openImpl(errorString, filePath()) == OpenResult::Success);
         m_widget->setCursorPosition(cPos);
         emit reloadFinished(success);
         return success;
diff --git a/src/plugins/clangtools/virtualfilesystemoverlay.cpp b/src/plugins/clangtools/virtualfilesystemoverlay.cpp
index db3e060e890..faf43db05bf 100644
--- a/src/plugins/clangtools/virtualfilesystemoverlay.cpp
+++ b/src/plugins/clangtools/virtualfilesystemoverlay.cpp
@@ -69,7 +69,7 @@ void VirtualFileSystemOverlay::update()
                     .pathAppended(doc->filePath().fileName() + ".auto");
             while (saved.path.exists())
                 saved.path = saved.path + ".1";
-            if (!doc->save(&error, saved.path.toString(), true)) {
+            if (!doc->save(&error, saved.path, true)) {
                 qCDebug(LOG) << error;
                 continue;
             }
diff --git a/src/plugins/coreplugin/documentmanager.cpp b/src/plugins/coreplugin/documentmanager.cpp
index b646e1e2600..7189182736f 100644
--- a/src/plugins/coreplugin/documentmanager.cpp
+++ b/src/plugins/coreplugin/documentmanager.cpp
@@ -744,17 +744,19 @@ static bool saveModifiedFilesHelper(const QList<IDocument *> &documents,
     return notSaved.isEmpty();
 }
 
-bool DocumentManager::saveDocument(IDocument *document, const QString &fileName, bool *isReadOnly)
+bool DocumentManager::saveDocument(IDocument *document,
+                                   const Utils::FilePath &filePath,
+                                   bool *isReadOnly)
 {
     bool ret = true;
-    QString effName = fileName.isEmpty() ? document->filePath().toString() : fileName;
-    expectFileChange(effName); // This only matters to other IDocuments which refer to this file
+    const Utils::FilePath &savePath = filePath.isEmpty() ? document->filePath() : filePath;
+    expectFileChange(savePath.toString()); // This only matters to other IDocuments which refer to this file
     bool addWatcher = removeDocument(document); // So that our own IDocument gets no notification at all
 
     QString errorString;
-    if (!document->save(&errorString, fileName, false)) {
+    if (!document->save(&errorString, filePath, false)) {
         if (isReadOnly) {
-            QFile ofi(effName);
+            QFile ofi(savePath.toString());
             // Check whether the existing file is writable
             if (!ofi.open(QIODevice::ReadWrite) && ofi.open(QIODevice::ReadOnly)) {
                 *isReadOnly = true;
@@ -769,7 +771,7 @@ bool DocumentManager::saveDocument(IDocument *document, const QString &fileName,
     }
 
     addDocument(document, addWatcher);
-    unexpectFileChange(effName);
+    unexpectFileChange(savePath.toString());
     m_instance->updateSaveAll();
     return ret;
 }
@@ -1314,7 +1316,7 @@ void DocumentManager::checkForReload()
     // handle deleted files
     EditorManager::closeDocuments(documentsToClose, false);
     for (auto it = documentsToSave.cbegin(), end = documentsToSave.cend(); it != end; ++it) {
-        saveDocument(it.key(), it.value());
+        saveDocument(it.key(), Utils::FilePath::fromString(it.value()));
         it.key()->checkPermissions();
     }
 
diff --git a/src/plugins/coreplugin/documentmanager.h b/src/plugins/coreplugin/documentmanager.h
index f05c7d0f10f..4072187ba8d 100644
--- a/src/plugins/coreplugin/documentmanager.h
+++ b/src/plugins/coreplugin/documentmanager.h
@@ -27,6 +27,7 @@
 
 #include <coreplugin/core_global.h>
 
+#include <utils/fileutils.h>
 #include <utils/id.h>
 
 #include <QObject>
@@ -79,7 +80,7 @@ public:
     static QString filePathKey(const QString &filePath, ResolveMode resolveMode);
 
     static bool saveDocument(IDocument *document,
-                             const QString &fileName = QString(),
+                             const Utils::FilePath &filePath = Utils::FilePath(),
                              bool *isReadOnly = nullptr);
 
     static QString allDocumentFactoryFiltersString(QString *allFilesFilter);
diff --git a/src/plugins/coreplugin/editormanager/editormanager.cpp b/src/plugins/coreplugin/editormanager/editormanager.cpp
index f7454638667..e0a3ffe3b7a 100644
--- a/src/plugins/coreplugin/editormanager/editormanager.cpp
+++ b/src/plugins/coreplugin/editormanager/editormanager.cpp
@@ -861,6 +861,9 @@ IEditor *EditorManagerPrivate::openEditor(EditorView *view, const QString &fileN
     IEditor *editor = nullptr;
     auto overrideCursor = Utils::OverrideCursor(QCursor(Qt::WaitCursor));
 
+    auto fp = Utils::FilePath::fromString(fn);
+    auto realFp = Utils::FilePath::fromString(realFn);
+
     IEditorFactory *factory = factories.takeFirst();
     while (factory) {
         editor = createEditor(factory, fn);
@@ -870,7 +873,7 @@ IEditor *EditorManagerPrivate::openEditor(EditorView *view, const QString &fileN
         }
 
         QString errorString;
-        IDocument::OpenResult openResult = editor->document()->open(&errorString, fn, realFn);
+        IDocument::OpenResult openResult = editor->document()->open(&errorString, fp, realFp);
         if (openResult == IDocument::OpenResult::Success)
             break;
 
@@ -933,7 +936,7 @@ IEditor *EditorManagerPrivate::openEditor(EditorView *view, const QString &fileN
         return nullptr;
 
     if (realFn != fn)
-        editor->document()->setRestoredFrom(realFn);
+        editor->document()->setRestoredFrom(realFp);
     addEditor(editor);
 
     if (newEditor)
@@ -2351,7 +2354,7 @@ void EditorManagerPrivate::autoSave()
                 || !QFileInfo(savePath).isWritable()) // FIXME: save them to a dedicated directory
             continue;
         QString errorString;
-        if (!document->autoSave(&errorString, saveName))
+        if (!document->autoSave(&errorString, Utils::FilePath::fromUserInput(saveName)))
             errors << errorString;
     }
     if (!errors.isEmpty())
@@ -2463,7 +2466,7 @@ bool EditorManagerPrivate::saveDocument(IDocument *document)
 
     emit m_instance->aboutToSave(document);
     // try saving, no matter what isReadOnly tells us
-    success = DocumentManager::saveDocument(document, QString(), &isReadOnly);
+    success = DocumentManager::saveDocument(document, FilePath(), &isReadOnly);
 
     if (!success && isReadOnly) {
         MakeWritableResult answer = makeFileWritable(document);
@@ -2503,7 +2506,7 @@ bool EditorManagerPrivate::saveDocumentAs(IDocument *document)
     }
 
     emit m_instance->aboutToSave(document);
-    const bool success = DocumentManager::saveDocument(document, absoluteFilePath.toString());
+    const bool success = DocumentManager::saveDocument(document, absoluteFilePath);
     document->checkPermissions();
 
     // TODO: There is an issue to be treated here. The new file might be of a different mime
diff --git a/src/plugins/coreplugin/idocument.cpp b/src/plugins/coreplugin/idocument.cpp
index 4a177a711fb..11c2d97839b 100644
--- a/src/plugins/coreplugin/idocument.cpp
+++ b/src/plugins/coreplugin/idocument.cpp
@@ -224,7 +224,7 @@ public:
     Utils::FilePath filePath;
     QString preferredDisplayName;
     QString uniqueDisplayName;
-    QString autoSaveName;
+    Utils::FilePath autoSavePath;
     Utils::InfoBar *infoBar = nullptr;
     Id id;
     optional<bool> fileIsReadOnly;
@@ -291,14 +291,14 @@ Id IDocument::id() const
     The open() method is used to load the contents of a file when a document is
     opened in an editor.
 
-    If the document is opened from an auto save file, \a realFileName is the
-    name of the auto save file that should be loaded, and \a fileName is the
+    If the document is opened from an auto save file, \a realFilePath is the
+    name of the auto save file that should be loaded, and \a filePath is the
     file name of the resulting file. In that case, the contents of the auto
     save file should be loaded, the file name of the IDocument should be set to
-    \a fileName, and the document state be set to modified.
+    \a filePath, and the document state be set to modified.
 
-    If the editor is opened from a regular file, \a fileName and \a
-    realFileName are the same.
+    If the editor is opened from a regular file, \a filePath and \a
+    filePath are the same.
 
     Use \a errorString to return an error message if this document cannot
     handle the file contents.
@@ -312,16 +312,16 @@ Id IDocument::id() const
     \sa shouldAutoSave()
     \sa setFilePath()
 */
-IDocument::OpenResult IDocument::open(QString *errorString, const QString &fileName, const QString &realFileName)
+IDocument::OpenResult IDocument::open(QString *errorString, const Utils::FilePath &filePath, const Utils::FilePath &realFilePath)
 {
     Q_UNUSED(errorString)
-    Q_UNUSED(fileName)
-    Q_UNUSED(realFileName)
+    Q_UNUSED(filePath)
+    Q_UNUSED(realFilePath)
     return OpenResult::CannotHandle;
 }
 
 /*!
-    Saves the contents of the document to the \a fileName on disk.
+    Saves the contents of the document to the \a filePath on disk.
 
     If \a autoSave is \c true, the saving is done for an auto-save, so the
     document should avoid cleanups or other operations that it does for
@@ -335,10 +335,10 @@ IDocument::OpenResult IDocument::open(QString *errorString, const QString &fileN
 
     \sa shouldAutoSave()
 */
-bool IDocument::save(QString *errorString, const QString &fileName, bool autoSave)
+bool IDocument::save(QString *errorString, const Utils::FilePath &filePath, bool autoSave)
 {
     Q_UNUSED(errorString)
-    Q_UNUSED(fileName)
+    Q_UNUSED(filePath)
     Q_UNUSED(autoSave)
     return false;
 }
@@ -613,11 +613,11 @@ void IDocument::setMimeType(const QString &mimeType)
 /*!
     \internal
 */
-bool IDocument::autoSave(QString *errorString, const QString &fileName)
+bool IDocument::autoSave(QString *errorString, const FilePath &filePath)
 {
-    if (!save(errorString, fileName, true))
+    if (!save(errorString, filePath, true))
         return false;
-    d->autoSaveName = fileName;
+    d->autoSavePath = filePath;
     return true;
 }
 
@@ -626,9 +626,9 @@ static const char kRestoredAutoSave[] = "RestoredAutoSave";
 /*!
     \internal
 */
-void IDocument::setRestoredFrom(const QString &name)
+void IDocument::setRestoredFrom(const Utils::FilePath &path)
 {
-    d->autoSaveName = name;
+    d->autoSavePath = path;
     d->restored = true;
     Utils::InfoBarEntry info(Id(kRestoredAutoSave),
                              tr("File was restored from auto-saved copy. "
@@ -641,9 +641,9 @@ void IDocument::setRestoredFrom(const QString &name)
 */
 void IDocument::removeAutoSaveFile()
 {
-    if (!d->autoSaveName.isEmpty()) {
-        QFile::remove(d->autoSaveName);
-        d->autoSaveName.clear();
+    if (!d->autoSavePath.isEmpty()) {
+        QFile::remove(d->autoSavePath.toString());
+        d->autoSavePath.clear();
         if (d->restored) {
             d->restored = false;
             infoBar()->removeInfo(Id(kRestoredAutoSave));
diff --git a/src/plugins/coreplugin/idocument.h b/src/plugins/coreplugin/idocument.h
index b468bf1a625..4e1860032bf 100644
--- a/src/plugins/coreplugin/idocument.h
+++ b/src/plugins/coreplugin/idocument.h
@@ -27,6 +27,7 @@
 
 #include "core_global.h"
 
+#include <utils/fileutils.h>
 #include <utils/id.h>
 
 #include <QObject>
@@ -87,9 +88,9 @@ public:
     void setId(Utils::Id id);
     Utils::Id id() const;
 
-    virtual OpenResult open(QString *errorString, const QString &fileName, const QString &realFileName);
+    virtual OpenResult open(QString *errorString, const Utils::FilePath &filePath, const Utils::FilePath &realFilePath);
 
-    virtual bool save(QString *errorString, const QString &fileName = QString(), bool autoSave = false);
+    virtual bool save(QString *errorString, const Utils::FilePath &filePath = Utils::FilePath(), bool autoSave = false);
 
     virtual QByteArray contents() const;
     virtual bool setContents(const QByteArray &contents);
@@ -124,8 +125,8 @@ public:
 
     void checkPermissions();
 
-    bool autoSave(QString *errorString, const QString &filePath);
-    void setRestoredFrom(const QString &name);
+    bool autoSave(QString *errorString, const Utils::FilePath &filePath);
+    void setRestoredFrom(const Utils::FilePath &path);
     void removeAutoSaveFile();
 
     bool hasWriteWarning() const;
diff --git a/src/plugins/coreplugin/textdocument.cpp b/src/plugins/coreplugin/textdocument.cpp
index d562831ef8e..4d6c45dadfc 100644
--- a/src/plugins/coreplugin/textdocument.cpp
+++ b/src/plugins/coreplugin/textdocument.cpp
@@ -82,7 +82,7 @@ QByteArray BaseTextDocument::decodingErrorSample() const
 }
 
 /*!
-    Writes out the contents (\a data) of the text file \a fileName.
+    Writes out the contents (\a data) of the text file \a filePath.
     Uses the format obtained from the last read() of the file.
 
     If an error occurs while writing the file, \a errorMessage is set to the
@@ -91,13 +91,15 @@ QByteArray BaseTextDocument::decodingErrorSample() const
     Returns whether the operation was successful.
 */
 
-bool BaseTextDocument::write(const QString &fileName, const QString &data, QString *errorMessage) const
+bool BaseTextDocument::write(const Utils::FilePath &filePath,
+                             const QString &data,
+                             QString *errorMessage) const
 {
-    return write(fileName, format(), data, errorMessage);
+    return write(filePath, format(), data, errorMessage);
 }
 
 /*!
-    Writes out the contents (\a data) of the text file \a fileName.
+    Writes out the contents (\a data) of the text file \a filePath.
     Uses the custom format \a format.
 
     If an error occurs while writing the file, \a errorMessage is set to the
@@ -106,11 +108,14 @@ bool BaseTextDocument::write(const QString &fileName, const QString &data, QStri
     Returns whether the operation was successful.
 */
 
-bool BaseTextDocument::write(const QString &fileName, const Utils::TextFileFormat &format, const QString &data, QString *errorMessage) const
+bool BaseTextDocument::write(const Utils::FilePath &filePath,
+                             const Utils::TextFileFormat &format,
+                             const QString &data,
+                             QString *errorMessage) const
 {
     if (debug)
-        qDebug() << Q_FUNC_INFO << this << fileName;
-    return format.writeFile(Utils::FilePath::fromString(fileName), data, errorMessage);
+        qDebug() << Q_FUNC_INFO << this << filePath;
+    return format.writeFile(filePath, data, errorMessage);
 }
 
 void BaseTextDocument::setSupportsUtf8Bom(bool value)
@@ -124,7 +129,7 @@ void BaseTextDocument::setLineTerminationMode(Utils::TextFileFormat::LineTermina
 }
 
 /*!
-    Autodetects file format and reads the text file specified by \a fileName
+    Autodetects file format and reads the text file specified by \a filePath
     into a list of strings specified by \a plainTextList.
 
     If an error occurs while writing the file, \a errorString is set to the
@@ -133,16 +138,21 @@ void BaseTextDocument::setLineTerminationMode(Utils::TextFileFormat::LineTermina
     Returns whether the operation was successful.
 */
 
-BaseTextDocument::ReadResult BaseTextDocument::read(const QString &fileName, QStringList *plainTextList, QString *errorString)
+BaseTextDocument::ReadResult BaseTextDocument::read(const Utils::FilePath &filePath,
+                                                    QStringList *plainTextList,
+                                                    QString *errorString)
 {
-    d->m_readResult =
-        Utils::TextFileFormat::readFile(Utils::FilePath::fromString(fileName), codec(),
-                                        plainTextList, &d->m_format, errorString, &d->m_decodingErrorSample);
+    d->m_readResult = Utils::TextFileFormat::readFile(filePath,
+                                                      codec(),
+                                                      plainTextList,
+                                                      &d->m_format,
+                                                      errorString,
+                                                      &d->m_decodingErrorSample);
     return d->m_readResult;
 }
 
 /*!
-    Autodetects file format and reads the text file specified by \a fileName
+    Autodetects file format and reads the text file specified by \a filePath
     into \a plainText.
 
     If an error occurs while writing the file, \a errorString is set to the
@@ -151,11 +161,16 @@ BaseTextDocument::ReadResult BaseTextDocument::read(const QString &fileName, QSt
     Returns whether the operation was successful.
 */
 
-BaseTextDocument::ReadResult BaseTextDocument::read(const QString &fileName, QString *plainText, QString *errorString)
+BaseTextDocument::ReadResult BaseTextDocument::read(const Utils::FilePath &filePath,
+                                                    QString *plainText,
+                                                    QString *errorString)
 {
-    d->m_readResult =
-        Utils::TextFileFormat::readFile(Utils::FilePath::fromString(fileName), codec(),
-                                        plainText, &d->m_format, errorString, &d->m_decodingErrorSample);
+    d->m_readResult = Utils::TextFileFormat::readFile(filePath,
+                                                      codec(),
+                                                      plainText,
+                                                      &d->m_format,
+                                                      errorString,
+                                                      &d->m_decodingErrorSample);
     return d->m_readResult;
 }
 
diff --git a/src/plugins/coreplugin/textdocument.h b/src/plugins/coreplugin/textdocument.h
index f1b1b4fc85e..7d16b6fa811 100644
--- a/src/plugins/coreplugin/textdocument.h
+++ b/src/plugins/coreplugin/textdocument.h
@@ -50,14 +50,14 @@ public:
     bool supportsUtf8Bom() const;
     Utils::TextFileFormat::LineTerminationMode lineTerminationMode() const;
 
-    ReadResult read(const QString &fileName, QStringList *plainTextList, QString *errorString);
-    ReadResult read(const QString &fileName, QString *plainText, QString *errorString);
+    ReadResult read(const Utils::FilePath &filePath, QStringList *plainTextList, QString *errorString);
+    ReadResult read(const Utils::FilePath &filePath, QString *plainText, QString *errorString);
 
     bool hasDecodingError() const;
     QByteArray decodingErrorSample() const;
 
-    bool write(const QString &fileName, const QString &data, QString *errorMessage) const;
-    bool write(const QString &fileName, const Utils::TextFileFormat &format, const QString &data, QString *errorMessage) const;
+    bool write(const Utils::FilePath &filePath, const QString &data, QString *errorMessage) const;
+    bool write(const Utils::FilePath &filePath, const Utils::TextFileFormat &format, const QString &data, QString *errorMessage) const;
 
     void setSupportsUtf8Bom(bool value);
     void setLineTerminationMode(Utils::TextFileFormat::LineTerminationMode mode);
diff --git a/src/plugins/cppeditor/cppeditordocument.cpp b/src/plugins/cppeditor/cppeditordocument.cpp
index 1de94133488..7fef7b5eff7 100644
--- a/src/plugins/cppeditor/cppeditordocument.cpp
+++ b/src/plugins/cppeditor/cppeditordocument.cpp
@@ -447,7 +447,7 @@ TextEditor::TabSettings CppEditorDocument::tabSettings() const
     return indenter()->tabSettings().value_or(TextEditor::TextDocument::tabSettings());
 }
 
-bool CppEditorDocument::save(QString *errorString, const QString &fileName, bool autoSave)
+bool CppEditorDocument::save(QString *errorString, const Utils::FilePath &filePath, bool autoSave)
 {
     Utils::ExecuteOnDestruction resetSettingsOnScopeExit;
 
@@ -490,7 +490,7 @@ bool CppEditorDocument::save(QString *errorString, const QString &fileName, bool
         setStorageSettings(settings);
     }
 
-    return TextEditor::TextDocument::save(errorString, fileName, autoSave);
+    return TextEditor::TextDocument::save(errorString, filePath, autoSave);
 }
 
 } // namespace Internal
diff --git a/src/plugins/cppeditor/cppeditordocument.h b/src/plugins/cppeditor/cppeditordocument.h
index b7a0219e0a2..ebb3e498b8f 100644
--- a/src/plugins/cppeditor/cppeditordocument.h
+++ b/src/plugins/cppeditor/cppeditordocument.h
@@ -71,7 +71,7 @@ public:
     TextEditor::TabSettings tabSettings() const override;
 
     bool save(QString *errorString,
-              const QString &fileName = QString(),
+              const Utils::FilePath &filePath = Utils::FilePath(),
               bool autoSave = false) override;
 
 signals:
diff --git a/src/plugins/cpptools/cpppointerdeclarationformatter_test.cpp b/src/plugins/cpptools/cpppointerdeclarationformatter_test.cpp
index bd2959b83c5..6e8bf332e62 100644
--- a/src/plugins/cpptools/cpppointerdeclarationformatter_test.cpp
+++ b/src/plugins/cpptools/cpppointerdeclarationformatter_test.cpp
@@ -106,7 +106,9 @@ public:
         QScopedPointer<TextEditor::BaseTextEditor> editor(
                     TextEditor::PlainTextEditorFactory::createPlainTextEditor());
         QString error;
-        editor->document()->open(&error, document->fileName(), document->fileName());
+        editor->document()->open(&error,
+                                 Utils::FilePath::fromString(document->fileName()),
+                                 Utils::FilePath::fromString(document->fileName()));
         QVERIFY(error.isEmpty());
 
         // Set cursor position
diff --git a/src/plugins/designer/formwindowfile.cpp b/src/plugins/designer/formwindowfile.cpp
index 7e85f13e472..57442568139 100644
--- a/src/plugins/designer/formwindowfile.cpp
+++ b/src/plugins/designer/formwindowfile.cpp
@@ -65,51 +65,51 @@ FormWindowFile::FormWindowFile(QDesignerFormWindowInterface *form, QObject *pare
             m_resourceHandler, &ResourceHandler::updateResources);
 }
 
-Core::IDocument::OpenResult FormWindowFile::open(QString *errorString, const QString &fileName,
-                                                 const QString &realFileName)
+Core::IDocument::OpenResult FormWindowFile::open(QString *errorString,
+                                                 const Utils::FilePath &filePath,
+                                                 const Utils::FilePath &realFilePath)
 {
     if (Designer::Constants::Internal::debug)
-        qDebug() << "FormWindowFile::open" << fileName;
+        qDebug() << "FormWindowFile::open" << filePath.toUserOutput();
 
     QDesignerFormWindowInterface *form = formWindow();
     QTC_ASSERT(form, return OpenResult::CannotHandle);
 
-    if (fileName.isEmpty())
+    if (filePath.isEmpty())
         return OpenResult::ReadError;
 
-    const QFileInfo fi(fileName);
-    const QString absfileName = fi.absoluteFilePath();
-
     QString contents;
-    Utils::TextFileFormat::ReadResult readResult = read(absfileName, &contents, errorString);
+    Utils::TextFileFormat::ReadResult readResult = read(filePath.absoluteFilePath(),
+                                                        &contents,
+                                                        errorString);
     if (readResult == Utils::TextFileFormat::ReadEncodingError)
         return OpenResult::CannotHandle;
     if (readResult != Utils::TextFileFormat::ReadSuccess)
         return OpenResult::ReadError;
 
-    form->setFileName(absfileName);
+    form->setFileName(filePath.absoluteFilePath().toString());
     const QByteArray contentsBA = contents.toUtf8();
     QBuffer str;
     str.setData(contentsBA);
     str.open(QIODevice::ReadOnly);
     if (!form->setContents(&str, errorString))
         return OpenResult::CannotHandle;
-    form->setDirty(fileName != realFileName);
+    form->setDirty(filePath != realFilePath);
 
     syncXmlFromFormWindow();
-    setFilePath(Utils::FilePath::fromString(absfileName));
+    setFilePath(filePath.absoluteFilePath());
     setShouldAutoSave(false);
     resourceHandler()->updateProjectResources();
 
     return OpenResult::Success;
 }
 
-bool FormWindowFile::save(QString *errorString, const QString &name, bool autoSave)
+bool FormWindowFile::save(QString *errorString, const FilePath &filePath, bool autoSave)
 {
-    const FilePath actualName = name.isEmpty() ? filePath() : FilePath::fromString(name);
+    const FilePath &actualName = filePath.isEmpty() ? this->filePath() : filePath;
 
     if (Designer::Constants::Internal::debug)
-        qDebug() << Q_FUNC_INFO << name << "->" << actualName;
+        qDebug() << Q_FUNC_INFO << filePath << "->" << actualName;
 
     QTC_ASSERT(m_formWindow, return false);
 
@@ -119,7 +119,7 @@ bool FormWindowFile::save(QString *errorString, const QString &name, bool autoSa
     const QString oldFormName = m_formWindow->fileName();
     if (!autoSave)
         m_formWindow->setFileName(actualName.toString());
-    const bool writeOK = writeFile(actualName.toString(), errorString);
+    const bool writeOK = writeFile(actualName, errorString);
     m_shouldAutoSave = false;
     if (autoSave)
         return writeOK;
@@ -228,7 +228,7 @@ bool FormWindowFile::reload(QString *errorString, ReloadFlag flag, ChangeType ty
     } else {
         emit aboutToReload();
         const bool success
-                = (open(errorString, filePath().toString(), filePath().toString()) == OpenResult::Success);
+                = (open(errorString, filePath(), filePath()) == OpenResult::Success);
         emit reloadFinished(success);
         return success;
     }
@@ -247,11 +247,11 @@ QString FormWindowFile::fallbackSaveAsFileName() const
     return m_suggestedName;
 }
 
-bool FormWindowFile::writeFile(const QString &fn, QString *errorString) const
+bool FormWindowFile::writeFile(const Utils::FilePath &filePath, QString *errorString) const
 {
     if (Designer::Constants::Internal::debug)
-        qDebug() << Q_FUNC_INFO << filePath() << fn;
-    return write(fn, format(), m_formWindow->contents(), errorString);
+        qDebug() << Q_FUNC_INFO << this->filePath() << filePath;
+    return write(filePath, format(), m_formWindow->contents(), errorString);
 }
 
 QDesignerFormWindowInterface *FormWindowFile::formWindow() const
diff --git a/src/plugins/designer/formwindowfile.h b/src/plugins/designer/formwindowfile.h
index d5791e74615..ca0ad50b3f1 100644
--- a/src/plugins/designer/formwindowfile.h
+++ b/src/plugins/designer/formwindowfile.h
@@ -48,9 +48,9 @@ public:
     ~FormWindowFile() override { }
 
     // IDocument
-    OpenResult open(QString *errorString, const QString &fileName,
-                    const QString &realFileName) override;
-    bool save(QString *errorString, const QString &fileName, bool autoSave) override;
+    OpenResult open(QString *errorString, const Utils::FilePath &filePath,
+                    const Utils::FilePath &realFilePath) override;
+    bool save(QString *errorString, const Utils::FilePath &filePath, bool autoSave) override;
     QByteArray contents() const override;
     bool setContents(const QByteArray &contents) override;
     bool shouldAutoSave() const override;
@@ -62,7 +62,7 @@ public:
     // Internal
     void setFallbackSaveAsFileName(const QString &fileName);
 
-    bool writeFile(const QString &fileName, QString *errorString) const;
+    bool writeFile(const Utils::FilePath &filePath, QString *errorString) const;
 
     QDesignerFormWindowInterface *formWindow() const;
     void syncXmlFromFormWindow();
diff --git a/src/plugins/diffeditor/diffeditordocument.cpp b/src/plugins/diffeditor/diffeditordocument.cpp
index 546fe9e27e0..d4a8f7851da 100644
--- a/src/plugins/diffeditor/diffeditordocument.cpp
+++ b/src/plugins/diffeditor/diffeditordocument.cpp
@@ -265,7 +265,7 @@ bool DiffEditorDocument::isSaveAsAllowed() const
     return state() == LoadOK;
 }
 
-bool DiffEditorDocument::save(QString *errorString, const QString &fileName, bool autoSave)
+bool DiffEditorDocument::save(QString *errorString, const Utils::FilePath &filePath, bool autoSave)
 {
     Q_UNUSED(errorString)
     Q_UNUSED(autoSave)
@@ -273,7 +273,7 @@ bool DiffEditorDocument::save(QString *errorString, const QString &fileName, boo
     if (state() != LoadOK)
         return false;
 
-    const bool ok = write(fileName, format(), plainText(), errorString);
+    const bool ok = write(filePath, format(), plainText(), errorString);
 
     if (!ok)
         return false;
@@ -282,9 +282,8 @@ bool DiffEditorDocument::save(QString *errorString, const QString &fileName, boo
     setDescription(QString());
     Core::EditorManager::clearUniqueId(this);
 
-    const QFileInfo fi(fileName);
     setTemporary(false);
-    setFilePath(FilePath::fromString(fi.absoluteFilePath()));
+    setFilePath(filePath.absoluteFilePath());
     setPreferredDisplayName(QString());
     emit temporaryStateChanged();
 
@@ -306,16 +305,16 @@ bool DiffEditorDocument::reload(QString *errorString, ReloadFlag flag, ChangeTyp
     Q_UNUSED(type)
     if (flag == FlagIgnore)
         return true;
-    return open(errorString, filePath().toString(), filePath().toString()) == OpenResult::Success;
+    return open(errorString, filePath(), filePath()) == OpenResult::Success;
 }
 
-Core::IDocument::OpenResult DiffEditorDocument::open(QString *errorString, const QString &fileName,
-                              const QString &realFileName)
+Core::IDocument::OpenResult DiffEditorDocument::open(QString *errorString, const Utils::FilePath &filePath,
+                              const Utils::FilePath &realFilePath)
 {
-    QTC_CHECK(fileName == realFileName); // does not support autosave
+    QTC_CHECK(filePath == realFilePath); // does not support autosave
     beginReload();
     QString patch;
-    ReadResult readResult = read(fileName, &patch, errorString);
+    ReadResult readResult = read(filePath, &patch, errorString);
     if (readResult == TextFileFormat::ReadIOError
         || readResult == TextFileFormat::ReadMemoryAllocationError) {
         return OpenResult::ReadError;
@@ -326,13 +325,12 @@ Core::IDocument::OpenResult DiffEditorDocument::open(QString *errorString, const
     if (!ok) {
         *errorString = tr("Could not parse patch file \"%1\". "
                           "The content is not of unified diff format.")
-                .arg(fileName);
+                .arg(filePath.toUserOutput());
     } else {
-        const QFileInfo fi(fileName);
         setTemporary(false);
         emit temporaryStateChanged();
-        setFilePath(FilePath::fromString(fi.absoluteFilePath()));
-        setDiffFiles(fileDataList, fi.absolutePath());
+        setFilePath(filePath.absoluteFilePath());
+        setDiffFiles(fileDataList, filePath.absoluteFilePath().toString());
     }
     endReload(ok);
     if (!ok && readResult == TextFileFormat::ReadEncodingError)
diff --git a/src/plugins/diffeditor/diffeditordocument.h b/src/plugins/diffeditor/diffeditordocument.h
index a034feb4391..a4dc866553a 100644
--- a/src/plugins/diffeditor/diffeditordocument.h
+++ b/src/plugins/diffeditor/diffeditordocument.h
@@ -81,11 +81,11 @@ public:
     QString fallbackSaveAsFileName() const override;
 
     bool isSaveAsAllowed() const override;
-    bool save(QString *errorString, const QString &fileName, bool autoSave) override;
+    bool save(QString *errorString, const Utils::FilePath &filePath, bool autoSave) override;
     void reload();
     bool reload(QString *errorString, ReloadFlag flag, ChangeType type) override;
-    OpenResult open(QString *errorString, const QString &fileName,
-                    const QString &realFileName) override;
+    OpenResult open(QString *errorString, const Utils::FilePath &filePath,
+                    const Utils::FilePath &realFilePath) override;
     bool selectEncoding();
     State state() const { return m_state; }
 
diff --git a/src/plugins/diffeditor/diffeditorwidgetcontroller.cpp b/src/plugins/diffeditor/diffeditorwidgetcontroller.cpp
index 3cddcdf55d0..e1221e63aed 100644
--- a/src/plugins/diffeditor/diffeditorwidgetcontroller.cpp
+++ b/src/plugins/diffeditor/diffeditorwidgetcontroller.cpp
@@ -202,7 +202,7 @@ void DiffEditorWidgetController::patch(bool revert, int fileIndex, int chunkInde
         if (PatchTool::runPatch(EditorManager::defaultTextCodec()->fromUnicode(patch),
                                 contentsCopyDir, 0, revert)) {
             QString errorString;
-            if (textDocument->reload(&errorString, contentsCopyFileName))
+            if (textDocument->reload(&errorString, FilePath::fromString(contentsCopyFileName)))
                 m_document->reload();
         }
     }
diff --git a/src/plugins/git/giteditor.cpp b/src/plugins/git/giteditor.cpp
index 0904c96c9cd..476f0d2cd55 100644
--- a/src/plugins/git/giteditor.cpp
+++ b/src/plugins/git/giteditor.cpp
@@ -283,14 +283,14 @@ void GitEditorWidget::addDiffActions(QMenu *menu, const DiffChunk &chunk)
     });
 }
 
-void GitEditorWidget::aboutToOpen(const QString &fileName, const QString &realFileName)
+void GitEditorWidget::aboutToOpen(const Utils::FilePath &filePath,
+                                  const Utils::FilePath &realFilePath)
 {
-    Q_UNUSED(realFileName)
+    Q_UNUSED(realFilePath)
     Utils::Id editorId = textDocument()->id();
     if (editorId == Git::Constants::GIT_COMMIT_TEXT_EDITOR_ID
             || editorId == Git::Constants::GIT_REBASE_EDITOR_ID) {
-        QFileInfo fi(fileName);
-        const QString gitPath = fi.absolutePath();
+        const QString gitPath = filePath.absolutePath().toString();
         setSource(gitPath);
         textDocument()->setCodec(
                     GitClient::instance()->encoding(gitPath, "i18n.commitEncoding"));
diff --git a/src/plugins/git/giteditor.h b/src/plugins/git/giteditor.h
index b24639a1d6d..6eaf454a356 100644
--- a/src/plugins/git/giteditor.h
+++ b/src/plugins/git/giteditor.h
@@ -59,7 +59,7 @@ private:
 
     void init() override;
     void addDiffActions(QMenu *menu, const VcsBase::DiffChunk &chunk) override;
-    void aboutToOpen(const QString &fileName, const QString &realFileName) override;
+    void aboutToOpen(const Utils::FilePath &filePath, const Utils::FilePath &realFilePath) override;
     QString changeUnderCursor(const QTextCursor &) const override;
     VcsBase::BaseAnnotationHighlighter *createAnnotationHighlighter(const QSet<QString> &changes) const override;
     QString decorateVersion(const QString &revision) const override;
diff --git a/src/plugins/imageviewer/imageviewerfile.cpp b/src/plugins/imageviewer/imageviewerfile.cpp
index 821e6ba77c0..d39e4931baf 100644
--- a/src/plugins/imageviewer/imageviewerfile.cpp
+++ b/src/plugins/imageviewer/imageviewerfile.cpp
@@ -80,22 +80,25 @@ ImageViewerFile::~ImageViewerFile()
     cleanUp();
 }
 
-Core::IDocument::OpenResult ImageViewerFile::open(QString *errorString, const QString &fileName,
-                                                  const QString &realFileName)
+Core::IDocument::OpenResult ImageViewerFile::open(QString *errorString,
+                                                  const Utils::FilePath &filePath,
+                                                  const Utils::FilePath &realfilePath)
 {
-    QTC_CHECK(fileName == realFileName); // does not support auto save
-    OpenResult success = openImpl(errorString, fileName);
+    QTC_CHECK(filePath == realfilePath); // does not support auto save
+    OpenResult success = openImpl(errorString, filePath);
     emit openFinished(success == OpenResult::Success);
     return success;
 }
 
-Core::IDocument::OpenResult ImageViewerFile::openImpl(QString *errorString, const QString &fileName)
+Core::IDocument::OpenResult ImageViewerFile::openImpl(QString *errorString,
+                                                      const Utils::FilePath &filePath)
 {
     cleanUp();
 
-    if (!QFileInfo(fileName).isReadable())
+    if (!filePath.isReadableFile())
         return OpenResult::ReadError;
 
+    const QString &fileName = filePath.toString();
     QByteArray format = QImageReader::imageFormat(fileName);
     // if it is impossible to recognize a file format - file will not be open correctly
     if (format.isEmpty()) {
@@ -141,7 +144,7 @@ Core::IDocument::OpenResult ImageViewerFile::openImpl(QString *errorString, cons
         emit imageSizeChanged(m_pixmap->size());
     }
 
-    setFilePath(Utils::FilePath::fromString(fileName));
+    setFilePath(filePath);
     setMimeType(Utils::mimeTypeForFile(fileName).name());
     return OpenResult::Success;
 }
@@ -163,7 +166,7 @@ bool ImageViewerFile::reload(QString *errorString,
     if (flag == FlagIgnore)
         return true;
     emit aboutToReload();
-    bool success = (openImpl(errorString, filePath().toString()) == OpenResult::Success);
+    bool success = (openImpl(errorString, filePath()) == OpenResult::Success);
     emit reloadFinished(success);
     return success;
 }
diff --git a/src/plugins/imageviewer/imageviewerfile.h b/src/plugins/imageviewer/imageviewerfile.h
index cf8c29fc60b..4cab47a45c1 100644
--- a/src/plugins/imageviewer/imageviewerfile.h
+++ b/src/plugins/imageviewer/imageviewerfile.h
@@ -57,8 +57,8 @@ public:
     ImageViewerFile();
     ~ImageViewerFile() override;
 
-    OpenResult open(QString *errorString, const QString &fileName,
-                    const QString &realFileName) override;
+    OpenResult open(QString *errorString, const Utils::FilePath &filePath,
+                    const Utils::FilePath &realFilePath) override;
 
     ReloadBehavior reloadBehavior(ChangeTrigger state, ChangeType type) const override;
     bool reload(QString *errorString, ReloadFlag flag, ChangeType type) override;
@@ -78,7 +78,7 @@ signals:
 
 private:
     void cleanUp();
-    OpenResult openImpl(QString *errorString, const QString &fileName);
+    OpenResult openImpl(QString *errorString, const Utils::FilePath &filePath);
 
     ImageType m_type = TypeInvalid;
 #ifndef QT_NO_SVG
diff --git a/src/plugins/modeleditor/modeldocument.cpp b/src/plugins/modeleditor/modeldocument.cpp
index bcb1322715a..2209bd3601c 100644
--- a/src/plugins/modeleditor/modeldocument.cpp
+++ b/src/plugins/modeleditor/modeldocument.cpp
@@ -66,26 +66,25 @@ ModelDocument::~ModelDocument()
     delete d;
 }
 
-Core::IDocument::OpenResult ModelDocument::open(QString *errorString, const QString &fileName,
-                                                const QString &realFileName)
+Core::IDocument::OpenResult ModelDocument::open(QString *errorString,
+                                                const Utils::FilePath &filePath,
+                                                const Utils::FilePath &realFilePath)
 {
-    Q_UNUSED(fileName)
+    Q_UNUSED(filePath)
 
-    OpenResult result = load(errorString, realFileName);
+    OpenResult result = load(errorString, realFilePath.toString());
     return result;
 }
 
-bool ModelDocument::save(QString *errorString, const QString &name, bool autoSave)
+bool ModelDocument::save(QString *errorString, const Utils::FilePath &filePath, bool autoSave)
 {
     if (!d->documentController) {
         *errorString = tr("No model loaded. Cannot save.");
         return false;
     }
 
-    QString actualName = filePath().toString();
-    if (!name.isEmpty())
-        actualName = name;
-    d->documentController->projectController()->setFileName(actualName);
+    const Utils::FilePath actualName = filePath.isEmpty() ? this->filePath() : filePath;
+    d->documentController->projectController()->setFileName(actualName.toString());
     try {
         d->documentController->projectController()->save();
     } catch (const qmt::Exception &ex) {
diff --git a/src/plugins/modeleditor/modeldocument.h b/src/plugins/modeleditor/modeldocument.h
index 5f7a99cd56c..dc4430623ff 100644
--- a/src/plugins/modeleditor/modeldocument.h
+++ b/src/plugins/modeleditor/modeldocument.h
@@ -48,9 +48,10 @@ signals:
     void contentSet();
 
 public:
-    OpenResult open(QString *errorString, const QString &fileName,
-                               const QString &realFileName) override;
-    bool save(QString *errorString, const QString &fileName, bool autoSave) override;
+    OpenResult open(QString *errorString,
+                    const Utils::FilePath &filePath,
+                    const Utils::FilePath &realFilePath) override;
+    bool save(QString *errorString, const Utils::FilePath &filePath, bool autoSave) override;
     bool shouldAutoSave() const override;
     bool isModified() const override;
     bool isSaveAsAllowed() const override;
diff --git a/src/plugins/resourceeditor/resourceeditorw.cpp b/src/plugins/resourceeditor/resourceeditorw.cpp
index 2f5ddc3729e..d782ae7d5fd 100644
--- a/src/plugins/resourceeditor/resourceeditorw.cpp
+++ b/src/plugins/resourceeditor/resourceeditorw.cpp
@@ -120,15 +120,15 @@ ResourceEditorW::~ResourceEditorW()
 }
 
 Core::IDocument::OpenResult ResourceEditorDocument::open(QString *errorString,
-                                                         const QString &fileName,
-                                                         const QString &realFileName)
+                                                         const Utils::FilePath &filePath,
+                                                         const Utils::FilePath &realFilePath)
 {
     if (debugResourceEditorW)
-        qDebug() <<  "ResourceEditorW::open: " << fileName;
+        qDebug() <<  "ResourceEditorW::open: " << filePath;
 
     setBlockDirtyChanged(true);
 
-    m_model->setFileName(realFileName);
+    m_model->setFileName(realFilePath.toString());
 
     OpenResult openResult = m_model->reload();
     if (openResult != OpenResult::Success) {
@@ -138,22 +138,21 @@ Core::IDocument::OpenResult ResourceEditorDocument::open(QString *errorString,
         return openResult;
     }
 
-    setFilePath(FilePath::fromString(fileName));
+    setFilePath(filePath);
     setBlockDirtyChanged(false);
-    m_model->setDirty(fileName != realFileName);
+    m_model->setDirty(filePath != realFilePath);
     m_shouldAutoSave = false;
 
     emit loaded(true);
     return OpenResult::Success;
 }
 
-bool ResourceEditorDocument::save(QString *errorString, const QString &name, bool autoSave)
+bool ResourceEditorDocument::save(QString *errorString, const FilePath &filePath, bool autoSave)
 {
     if (debugResourceEditorW)
-        qDebug(">ResourceEditorW::save: %s", qPrintable(name));
+        qDebug() << ">ResourceEditorW::save: " << filePath;
 
-    const FilePath oldFileName = filePath();
-    const FilePath actualName = name.isEmpty() ? oldFileName : FilePath::fromString(name);
+    const FilePath &actualName = filePath.isEmpty() ? this->filePath() : filePath;
     if (actualName.isEmpty())
         return false;
 
@@ -161,14 +160,14 @@ bool ResourceEditorDocument::save(QString *errorString, const QString &name, boo
     m_model->setFileName(actualName.toString());
     if (!m_model->save()) {
         *errorString = m_model->errorMessage();
-        m_model->setFileName(oldFileName.toString());
+        m_model->setFileName(this->filePath().toString());
         m_blockDirtyChanged = false;
         return false;
     }
 
     m_shouldAutoSave = false;
     if (autoSave) {
-        m_model->setFileName(oldFileName.toString());
+        m_model->setFileName(this->filePath().toString());
         m_model->setDirty(true);
         m_blockDirtyChanged = false;
         return true;
@@ -272,8 +271,7 @@ bool ResourceEditorDocument::reload(QString *errorString, ReloadFlag flag, Chang
     if (flag == FlagIgnore)
         return true;
     emit aboutToReload();
-    QString fn = filePath().toString();
-    const bool success = (open(errorString, fn, fn) == OpenResult::Success);
+    const bool success = (open(errorString, filePath(), filePath()) == OpenResult::Success);
     emit reloadFinished(success);
     return success;
 }
diff --git a/src/plugins/resourceeditor/resourceeditorw.h b/src/plugins/resourceeditor/resourceeditorw.h
index 55fd3bfab57..628c6b138e3 100644
--- a/src/plugins/resourceeditor/resourceeditorw.h
+++ b/src/plugins/resourceeditor/resourceeditorw.h
@@ -51,9 +51,9 @@ public:
     ResourceEditorDocument(QObject *parent = nullptr);
 
     //IDocument
-    OpenResult open(QString *errorString, const QString &fileName,
-                    const QString &realFileName) override;
-    bool save(QString *errorString, const QString &fileName, bool autoSave) override;
+    OpenResult open(QString *errorString, const Utils::FilePath &filePath,
+                    const Utils::FilePath &realFilePath) override;
+    bool save(QString *errorString, const Utils::FilePath &filePath, bool autoSave) override;
     QString plainText() const;
     QByteArray contents() const override;
     bool setContents(const QByteArray &contents) override;
diff --git a/src/plugins/scxmleditor/scxmleditordocument.cpp b/src/plugins/scxmleditor/scxmleditordocument.cpp
index 10acfe24c50..22cf8285896 100644
--- a/src/plugins/scxmleditor/scxmleditordocument.cpp
+++ b/src/plugins/scxmleditor/scxmleditordocument.cpp
@@ -57,32 +57,33 @@ ScxmlEditorDocument::ScxmlEditorDocument(MainWidget *designWidget, QObject *pare
     });
 }
 
-Core::IDocument::OpenResult ScxmlEditorDocument::open(QString *errorString, const QString &fileName, const QString &realFileName)
+Core::IDocument::OpenResult ScxmlEditorDocument::open(QString *errorString,
+                                                      const Utils::FilePath &filePath,
+                                                      const Utils::FilePath &realFilePath)
 {
-    Q_UNUSED(realFileName)
+    Q_UNUSED(realFilePath)
 
-    if (fileName.isEmpty())
+    if (filePath.isEmpty())
         return OpenResult::ReadError;
 
     if (!m_designWidget)
         return OpenResult::ReadError;
 
-    const QFileInfo fi(fileName);
-    const QString absfileName = fi.absoluteFilePath();
-    if (!m_designWidget->load(absfileName)) {
+    const FilePath &absoluteFilePath = filePath.absoluteFilePath();
+    if (!m_designWidget->load(absoluteFilePath.toString())) {
         *errorString = m_designWidget->errorMessage();
         return OpenResult::ReadError;
     }
 
-    setFilePath(Utils::FilePath::fromString(absfileName));
+    setFilePath(absoluteFilePath);
 
     return OpenResult::Success;
 }
 
-bool ScxmlEditorDocument::save(QString *errorString, const QString &name, bool autoSave)
+bool ScxmlEditorDocument::save(QString *errorString, const FilePath &filePath, bool autoSave)
 {
-    const FilePath oldFileName = filePath();
-    const FilePath actualName = name.isEmpty() ? oldFileName : FilePath::fromString(name);
+    const FilePath oldFileName = this->filePath();
+    const FilePath actualName = filePath.isEmpty() ? oldFileName : filePath;
     if (actualName.isEmpty())
         return false;
     bool dirty = m_designWidget->isDirty();
diff --git a/src/plugins/scxmleditor/scxmleditordocument.h b/src/plugins/scxmleditor/scxmleditordocument.h
index 537c7eb0273..587343a70b0 100644
--- a/src/plugins/scxmleditor/scxmleditordocument.h
+++ b/src/plugins/scxmleditor/scxmleditordocument.h
@@ -49,8 +49,10 @@ public:
     explicit ScxmlEditorDocument(Common::MainWidget *designWidget, QObject *parent = nullptr);
 
     // IDocument
-    OpenResult open(QString *errorString, const QString &fileName, const QString &realFileName) override;
-    bool save(QString *errorString, const QString &fileName, bool autoSave) override;
+    OpenResult open(QString *errorString,
+                    const Utils::FilePath &filePath,
+                    const Utils::FilePath &realFilePath) override;
+    bool save(QString *errorString, const Utils::FilePath &filePath, bool autoSave) override;
     bool shouldAutoSave() const override;
     bool isSaveAsAllowed() const override;
     bool isModified() const override;
diff --git a/src/plugins/texteditor/textdocument.cpp b/src/plugins/texteditor/textdocument.cpp
index eb6ae5b0ddc..2a52c425753 100644
--- a/src/plugins/texteditor/textdocument.cpp
+++ b/src/plugins/texteditor/textdocument.cpp
@@ -600,7 +600,7 @@ SyntaxHighlighter *TextDocument::syntaxHighlighter() const
  * If \a autoSave is true, the cursor will be restored and some signals suppressed
  * and we do not clean up the text file (cleanWhitespace(), ensureFinalNewLine()).
  */
-bool TextDocument::save(QString *errorString, const QString &saveFileName, bool autoSave)
+bool TextDocument::save(QString *errorString, const FilePath &filePath, bool autoSave)
 {
     QTextCursor cursor(&d->m_document);
 
@@ -638,11 +638,9 @@ bool TextDocument::save(QString *errorString, const QString &saveFileName, bool
         if (d->m_storageSettings.m_addFinalNewLine)
           ensureFinalNewLine(cursor);
         cursor.endEditBlock();
-      }
+    }
 
-    QString fName = filePath().toString();
-    if (!saveFileName.isEmpty())
-        fName = saveFileName;
+    const Utils::FilePath &savePath = filePath.isEmpty() ? this->filePath() : filePath;
 
     // check if UTF8-BOM has to be added or removed
     Utils::TextFileFormat saveFormat = format();
@@ -659,7 +657,7 @@ bool TextDocument::save(QString *errorString, const QString &saveFileName, bool
         }
     }
 
-    const bool ok = write(fName, saveFormat, d->m_document.toPlainText(), errorString);
+    const bool ok = write(savePath, saveFormat, d->m_document.toPlainText(), errorString);
 
     // restore text cursor and scroll bar positions
     if (autoSave && undos < d->m_document.availableUndoSteps()) {
@@ -681,9 +679,8 @@ bool TextDocument::save(QString *errorString, const QString &saveFileName, bool
         return true;
 
     // inform about the new filename
-    const QFileInfo fi(fName);
     d->m_document.setModified(false); // also triggers update of the block revisions
-    setFilePath(Utils::FilePath::fromUserInput(fi.absoluteFilePath()));
+    setFilePath(savePath.absoluteFilePath());
     emit changed();
     return true;
 }
@@ -715,33 +712,35 @@ bool TextDocument::isModified() const
     return d->m_document.isModified();
 }
 
-Core::IDocument::OpenResult TextDocument::open(QString *errorString, const QString &fileName,
-                                               const QString &realFileName)
+Core::IDocument::OpenResult TextDocument::open(QString *errorString,
+                                               const Utils::FilePath &filePath,
+                                               const Utils::FilePath &realFilePath)
 {
-    emit aboutToOpen(fileName, realFileName);
-    OpenResult success = openImpl(errorString, fileName, realFileName, /*reload =*/ false);
+    emit aboutToOpen(filePath, realFilePath);
+    OpenResult success = openImpl(errorString, filePath, realFilePath, /*reload =*/ false);
     if (success == OpenResult::Success) {
-        setMimeType(Utils::mimeTypeForFile(fileName).name());
+        setMimeType(Utils::mimeTypeForFile(filePath.toString()).name());
         emit openFinishedSuccessfully();
     }
     return success;
 }
 
-Core::IDocument::OpenResult TextDocument::openImpl(QString *errorString, const QString &fileName,
-                                                   const QString &realFileName, bool reload)
+Core::IDocument::OpenResult TextDocument::openImpl(QString *errorString,
+                                                   const Utils::FilePath &filePath,
+                                                   const Utils::FilePath &realFilePath,
+                                                   bool reload)
 {
     QStringList content;
 
     ReadResult readResult = Utils::TextFileFormat::ReadIOError;
 
-    if (!fileName.isEmpty()) {
-        const QFileInfo fi(fileName);
-        readResult = read(realFileName, &content, errorString);
+    if (!filePath.isEmpty()) {
+        readResult = read(realFilePath, &content, errorString);
         const int chunks = content.size();
 
         // Don't call setUndoRedoEnabled(true) when reload is true and filenames are different,
         // since it will reset the undo's clear index
-        if (!reload || fileName == realFileName)
+        if (!reload || filePath == realFilePath)
             d->m_document.setUndoRedoEnabled(reload);
 
         QTextCursor c(&d->m_document);
@@ -775,7 +774,7 @@ Core::IDocument::OpenResult TextDocument::openImpl(QString *errorString, const Q
 
         // Don't call setUndoRedoEnabled(true) when reload is true and filenames are different,
         // since it will reset the undo's clear index
-        if (!reload || fileName == realFileName)
+        if (!reload || filePath == realFilePath)
             d->m_document.setUndoRedoEnabled(true);
 
         auto documentLayout =
@@ -783,8 +782,8 @@ Core::IDocument::OpenResult TextDocument::openImpl(QString *errorString, const Q
         QTC_ASSERT(documentLayout, return OpenResult::CannotHandle);
         documentLayout->lastSaveRevision = d->m_autoSaveRevision = d->m_document.revision();
         d->updateRevisions();
-        d->m_document.setModified(fileName != realFileName);
-        setFilePath(Utils::FilePath::fromUserInput(fi.absoluteFilePath()));
+        d->m_document.setModified(filePath != realFilePath);
+        setFilePath(filePath);
     }
     if (readResult == Utils::TextFileFormat::ReadIOError)
         return OpenResult::ReadError;
@@ -800,10 +799,10 @@ bool TextDocument::reload(QString *errorString, QTextCodec *codec)
 
 bool TextDocument::reload(QString *errorString)
 {
-    return reload(errorString, filePath().toString());
+    return reload(errorString, filePath());
 }
 
-bool TextDocument::reload(QString *errorString, const QString &realFileName)
+bool TextDocument::reload(QString *errorString, const FilePath &realFilePath)
 {
     emit aboutToReload();
     auto documentLayout =
@@ -812,8 +811,8 @@ bool TextDocument::reload(QString *errorString, const QString &realFileName)
     if (documentLayout)
         marks = documentLayout->documentClosing(); // removes text marks non-permanently
 
-    const QString &file = filePath().toString();
-    bool success = openImpl(errorString, file, realFileName, /*reload =*/ true) == OpenResult::Success;
+    bool success = openImpl(errorString, filePath(), realFilePath, /*reload =*/true)
+                   == OpenResult::Success;
 
     if (documentLayout)
         documentLayout->documentReloaded(marks, this); // re-adds text marks
diff --git a/src/plugins/texteditor/textdocument.h b/src/plugins/texteditor/textdocument.h
index f67b55fa6e9..98e6546045a 100644
--- a/src/plugins/texteditor/textdocument.h
+++ b/src/plugins/texteditor/textdocument.h
@@ -112,7 +112,7 @@ public:
     void removeMarkFromMarksCache(TextMark *mark);
 
     // IDocument implementation.
-    bool save(QString *errorString, const QString &fileName, bool autoSave) override;
+    bool save(QString *errorString, const Utils::FilePath &filePath, bool autoSave) override;
     QByteArray contents() const override;
     bool setContents(const QByteArray &contents) override;
     bool shouldAutoSave() const override;
@@ -127,10 +127,10 @@ public:
     void setFallbackSaveAsPath(const QString &fallbackSaveAsPath);
     void setFallbackSaveAsFileName(const QString &fallbackSaveAsFileName);
 
-    OpenResult open(QString *errorString, const QString &fileName,
-                    const QString &realFileName) override;
+    OpenResult open(QString *errorString, const Utils::FilePath &filePath,
+                    const Utils::FilePath &realFilePath) override;
     virtual bool reload(QString *errorString);
-    bool reload(QString *errorString, const QString &realFileName);
+    bool reload(QString *errorString, const Utils::FilePath &realFilePath);
 
     bool setPlainText(const QString &text);
     QTextDocument *document() const;
@@ -156,7 +156,7 @@ public:
         const std::function<Utils::FilePath()> &filePath);
 
 signals:
-    void aboutToOpen(const QString &fileName, const QString &realFileName);
+    void aboutToOpen(const Utils::FilePath &filePath, const Utils::FilePath &realFilePath);
     void openFinishedSuccessfully();
     void contentsChangedWithPosition(int position, int charsRemoved, int charsAdded);
     void tabSettingsChanged();
@@ -167,7 +167,9 @@ protected:
     virtual void applyFontSettings();
 
 private:
-    OpenResult openImpl(QString *errorString, const QString &fileName, const QString &realFileName,
+    OpenResult openImpl(QString *errorString,
+                        const Utils::FilePath &filePath,
+                        const Utils::FilePath &realFileName,
                         bool reload);
     void cleanWhitespace(QTextCursor &cursor, bool inEntireDocument, bool cleanIndentation);
     void ensureFinalNewLine(QTextCursor &cursor);
diff --git a/src/plugins/texteditor/texteditor.cpp b/src/plugins/texteditor/texteditor.cpp
index 057123e2152..ab0cd652ff7 100644
--- a/src/plugins/texteditor/texteditor.cpp
+++ b/src/plugins/texteditor/texteditor.cpp
@@ -1464,10 +1464,10 @@ TextDocument *TextEditorWidget::textDocument() const
     return d->m_document.data();
 }
 
-void TextEditorWidget::aboutToOpen(const QString &fileName, const QString &realFileName)
+void TextEditorWidget::aboutToOpen(const Utils::FilePath &filePath, const Utils::FilePath &realFilePath)
 {
-    Q_UNUSED(fileName)
-    Q_UNUSED(realFileName)
+    Q_UNUSED(filePath)
+    Q_UNUSED(realFilePath)
 }
 
 void TextEditorWidget::openFinishedSuccessfully()
diff --git a/src/plugins/texteditor/texteditor.h b/src/plugins/texteditor/texteditor.h
index b48c7b3ee3d..8860b405671 100644
--- a/src/plugins/texteditor/texteditor.h
+++ b/src/plugins/texteditor/texteditor.h
@@ -186,7 +186,7 @@ public:
     TextDocument *textDocument() const;
     QSharedPointer<TextDocument> textDocumentPtr() const;
 
-    virtual void aboutToOpen(const QString &fileName, const QString &realFileName);
+    virtual void aboutToOpen(const Utils::FilePath &filePath, const Utils::FilePath &realFilePath);
     virtual void openFinishedSuccessfully();
     // IEditor
     QByteArray saveState() const;
diff --git a/src/plugins/vcsbase/submiteditorfile.cpp b/src/plugins/vcsbase/submiteditorfile.cpp
index 453be31228e..7cda09855e9 100644
--- a/src/plugins/vcsbase/submiteditorfile.cpp
+++ b/src/plugins/vcsbase/submiteditorfile.cpp
@@ -51,22 +51,23 @@ SubmitEditorFile::SubmitEditorFile(VcsBaseSubmitEditor *editor) :
             this, &Core::IDocument::contentsChanged);
 }
 
-Core::IDocument::OpenResult SubmitEditorFile::open(QString *errorString, const QString &fileName,
-                                                   const QString &realFileName)
+Core::IDocument::OpenResult SubmitEditorFile::open(QString *errorString,
+                                                   const Utils::FilePath &filePath,
+                                                   const Utils::FilePath &realFilePath)
 {
-    if (fileName.isEmpty())
+    if (filePath.isEmpty())
         return OpenResult::ReadError;
 
     FileReader reader;
-    if (!reader.fetch(Utils::FilePath::fromString(realFileName), QIODevice::Text, errorString))
+    if (!reader.fetch(realFilePath, QIODevice::Text, errorString))
         return OpenResult::ReadError;
 
     const QString text = QString::fromLocal8Bit(reader.data());
     if (!m_editor->setFileContents(text.toUtf8()))
         return OpenResult::CannotHandle;
 
-    setFilePath(FilePath::fromString(fileName));
-    setModified(fileName != realFileName);
+    setFilePath(filePath.absoluteFilePath());
+    setModified(filePath != realFilePath);
     return OpenResult::Success;
 }
 
@@ -88,16 +89,16 @@ void SubmitEditorFile::setModified(bool modified)
     emit changed();
 }
 
-bool SubmitEditorFile::save(QString *errorString, const QString &fileName, bool autoSave)
+bool SubmitEditorFile::save(QString *errorString, const FilePath &filePath, bool autoSave)
 {
-    const FilePath fName = fileName.isEmpty() ? filePath() : FilePath::fromString(fileName);
+    const FilePath &fName = filePath.isEmpty() ? this->filePath() : filePath;
     FileSaver saver(fName, QIODevice::WriteOnly | QIODevice::Truncate | QIODevice::Text);
     saver.write(m_editor->fileContents());
     if (!saver.finalize(errorString))
         return false;
     if (autoSave)
         return true;
-    setFilePath(FilePath::fromUserInput(fName.toFileInfo().absoluteFilePath()));
+    setFilePath(fName.absoluteFilePath());
     setModified(false);
     if (!errorString->isEmpty())
         return false;
diff --git a/src/plugins/vcsbase/submiteditorfile.h b/src/plugins/vcsbase/submiteditorfile.h
index de326c61014..cbc5f22dea7 100644
--- a/src/plugins/vcsbase/submiteditorfile.h
+++ b/src/plugins/vcsbase/submiteditorfile.h
@@ -39,13 +39,13 @@ class SubmitEditorFile : public Core::IDocument
 public:
     explicit SubmitEditorFile(VcsBaseSubmitEditor *editor);
 
-    OpenResult open(QString *errorString, const QString &fileName,
-                    const QString &realFileName) override;
+    OpenResult open(QString *errorString, const Utils::FilePath &filePath,
+                    const Utils::FilePath &realFilePath) override;
     QByteArray contents() const override;
     bool setContents(const QByteArray &contents) override;
 
     bool isModified() const override { return m_modified; }
-    bool save(QString *errorString, const QString &fileName, bool autoSave) override;
+    bool save(QString *errorString, const Utils::FilePath &filePath, bool autoSave) override;
     ReloadBehavior reloadBehavior(ChangeTrigger state, ChangeType type) const override;
 
     void setModified(bool modified = true);