ClangFormat: Do not remove whitespace twice

Previously the built-in engine was responsible for
clearing the extra whitespace. When ClangFormat plugin
is active and "Format edited code on file save" is selected
it clears the unnecessary whitespace on it's own and
we don't need to adjust the whitespace the second time.

Fixes: QTCREATORBUG-22239
Change-Id: I309f51c51aca8ab85b5cfb7809923b59a912b4e0
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/plugins/cppeditor/cppeditordocument.cpp

@@ -44,10 +44,12 @@
 #include <projectexplorer/session.h>
 
 #include <texteditor/icodestylepreferencesfactory.h>
+#include <texteditor/storagesettings.h>
 #include <texteditor/textdocumentlayout.h>
 #include <texteditor/texteditorsettings.h>
 
 #include <coreplugin/editormanager/editormanager.h>
+#include <utils/executeondestruction.h>
 #include <utils/mimetypes/mimedatabase.h>
 #include <utils/qtcassert.h>
 #include <utils/runextensions.h>
@@ -448,6 +450,8 @@ TextEditor::TabSettings CppEditorDocument::tabSettings() const
 
 bool CppEditorDocument::save(QString *errorString, const QString &fileName, bool autoSave)
 {
+    Utils::ExecuteOnDestruction resetSettingsOnScopeExit;
+
     if (indenter()->formatOnSave() && !autoSave) {
         auto *layout = qobject_cast<TextEditor::TextDocumentLayout *>(document()->documentLayout());
         const int documentRevision = layout->lastSaveRevision;
@@ -479,6 +483,12 @@ bool CppEditorDocument::save(QString *errorString, const QString &fileName, bool
             indenter()->format(editedRanges);
             cursor.endEditBlock();
         }
+
+        TextEditor::StorageSettings settings = storageSettings();
+        resetSettingsOnScopeExit.reset(
+            [this, defaultSettings = settings]() { setStorageSettings(defaultSettings); });
+        settings.m_cleanWhitespace = false;
+        setStorageSettings(settings);
     }
 
     return TextEditor::TextDocument::save(errorString, fileName, autoSave);